Friday, December 21, 2018

Top ten posts at Drosophila Models of Human Diseases

Celebrating the year's end with a list of the most-viewed blog posts:

If it sickens flies, do I want it in me? Using Drosophila to assess toxicity of plant extracts









And the most-viewed post of all time (as of December 2018):
Results from Drosophila contribute to study of the neurodevelopmental disorder Vici syndrome

Diet and the gut

Pereira MT, Malik M, Nostro JA, Mahler GJ, Musselman LP. Effect of dietary additives on intestinal permeability in both Drosophila and a human cell co-culture. Dis Model Mech. 2018 Nov 28;11(12). pii: dmm034520. PMID: 30504122.

From the abstract: "Increased intestinal barrier permeability has been correlated with aging and disease, including type 2 diabetes, Crohn's disease, celiac disease, multiple sclerosis and irritable bowel syndrome. The prevalence of these ailments has risen together with an increase in industrial food processing and food additive consumption. Additives, including sugar, metal oxide nanoparticles, surfactants and sodium chloride, have all been suggested to increase intestinal permeability. We used two complementary model systems to examine the effects of food additives on gut barrier function: a Drosophila in vivo model and an in vitro human cell co-culture model. ... This study extends previous work in flies and humans showing that diet can play a role in the health of the gut barrier. ..."

Genetic models of Parkinson's disease -- review article and database

Breger LS, Fuzzati Armentero MT. Genetically engineered animal models of Parkinson's disease: from worm to rodent. Eur J Neurosci. 2018 Dec 14. PMID: 30552719.

From the abstract: "Parkinson's disease (PD) is a progressive neurological disorder ... The EU Joint Programme - Neurodegenerative Disease Research (JPND) has promoted the creation of an online database aiming at summarising the different features of experimental models of Parkinson's disease. This review discusses available genetic models of PD and the extent to which they adequately mirror the human pathology ..."

Circadian rhythms, Parkinson's disease, and fruit fly research

De Lazzari F, Bisaglia M, Zordan MA, Sandrelli F. Circadian Rhythm Abnormalities in Parkinson's Disease from Humans to Flies and Back. Int J Mol Sci. 2018 Dec 6;19(12). pii: E3911. PMID: 30563246.

From the abstract: "Clinical and research studies have suggested a link between Parkinson's disease (PD) and alterations in the circadian clock. Drosophila melanogaster may represent a useful model to study the relationship between the circadian clock and PD. ... Here, we describe the fly circadian and dopaminergic systems and report recent studies which indicate the presence of circadian abnormalities in some fly PD genetic models. We discuss the use of Drosophila to investigate whether, in adults, the disruption of the circadian system might be causative of brain neurodegeneration. We also consider approaches using Drosophila, which might provide new information ... As a corollary, ... we suggest that genetic models of PD could be used to perform lifelong screens for drug-modulators of general and/or circadian-related PD traits."

Drosophila as "providing an unparalleled opportunity to combine dietary manipulation with models of human metabolic disease and cancer" (Review Article)

Warr CG, Shaw KH, Azim A, Piper MDW, Parsons LM. Using Mouse and Drosophila Models to Investigate the Mechanistic Links between Diet, Obesity, Type II Diabetes, and Cancer. Int J Mol Sci. 2018 Dec 18;19(12). pii: E4110. PMID: 30567377.

The abstract: "Many of the links between diet and cancer are controversial and over simplified. To date, human epidemiological studies consistently reveal that patients who suffer diet-related obesity and/or type II diabetes have an increased risk of cancer, suffer more aggressive cancers, and respond poorly to current therapies. However, the underlying molecular mechanisms that increase cancer risk and decrease the response to cancer therapies in these patients remain largely unknown. Here, we review studies in mouse cancer models in which either dietary or genetic manipulation has been used to model obesity and/or type II diabetes. These studies demonstrate an emerging role for the conserved insulin and insulin-like growth factor signaling pathways as links between diet and cancer progression. However, these models are time consuming to develop and expensive to maintain. As the world faces an epidemic of obesity and type II diabetes we argue that the development of novel animal models is urgently required. We make the case for Drosophila as providing an unparalleled opportunity to combine dietary manipulation with models of human metabolic disease and cancer. Thus, combining diet and cancer models in Drosophila can rapidly and significantly advance our understanding of the conserved molecular mechanisms that link diet and diet-related metabolic disorders to poor cancer patient prognosis."

Friday, December 14, 2018

Studies in Drosophila help reveal how Dengue and Zika virus cause disease

Shah, et al. (2018) Comparative Flavivirus-Host Protein Interaction Mapping Reveals Mechanisms of Dengue and Zika Virus Pathogenesis. Cell 175(7):1931-1945.e18

Graphical abstract for this report in Cell
from the Bellen, Andino, & Krogan labs
Summary: "Mosquito-borne flaviviruses, including dengue virus (DENV) and Zika virus (ZIKV), are a growing public health concern. Systems-level analysis of how flaviviruses hijack cellular processes through virus-host protein-protein interactions (PPIs) provides information about their replication and pathogenic mechanisms. We used affinity purification-mass spectrometry (AP-MS) to compare flavivirus-host interactions for two viruses (DENV and ZIKV) in two hosts (human and mosquito). Conserved virus-host PPIs revealed that the flavivirus NS5 protein suppresses interferon stimulated genes by inhibiting recruitment of the transcription complex PAF1C and that chemical modulation of SEC61 inhibits DENV and ZIKV replication in human and mosquito cells. Finally, we identified a ZIKV-specific interaction between NS4A and ANKLE2, a gene linked to hereditary microcephaly, and showed that ZIKV NS4A causes microcephaly in Drosophila in an ANKLE2-dependent manner. Thus, comparative flavivirus-host PPI mapping provides biological insights and, when coupled with in vivo models, can be used to unravel pathogenic mechanisms."

Note: when available from PubMed, the full author list and PubMed ID will be added.

Wednesday, November 21, 2018

... and another! Fly study helps point to possible genetic cause of an ARID

Kazeminasab S, Taskiran II, Fattahi Z, Bazazzadegan N, Hosseini M, Rahimi M, Oladnabi M, Haddadi M, Celik A, Ropers HH, Najmabadi H, Kahrizi K. CNKSR1 gene defect can cause syndromic autosomal recessive intellectual disability. Am J Med Genet B Neuropsychiatr Genet. 2018 Nov 18. doi: 10.1002/ajmg.b.32648. PMID: 30450701.

From the abstract: "... A novel frameshift mutation in CNKSR1 gene was detected by Next-Generation Sequencing (NGS) in an Iranian family with syndromic autosomal recessive intellectual disability (ARID). CNKSR1 encodes a connector enhancer of kinase suppressor of Ras 1 ... CNKSR1 interacts with proteins which have already been shown to be associated with intellectual disability (ID) in the MAPK signaling pathway and promotes cell migration through RhoA-mediated c-Jun N-terminal kinase (JNK) activation. Lack of CNKSR1 transcripts and protein was observed in lymphoblastoid cells derived from affected patients using qRT-PCR and western blot analysis ...  RNAi-mediated knockdown of cnk, the CNKSR1 orthologue in Drosophila melanogaster brain, led to defects in eye and mushroom body (MB) structures. In conclusion, our findings support the possible role of CNKSR1 in brain development which can lead to cognitive impairment."

Tuesday, November 20, 2018

Drosophila studies contributed to -- another -- study that identifies a human disease gene

Ansar M, Chung HL, Taylor RL, Nazir A, Imtiaz S, Sarwar MT, Manousopoulou A, Makrythanasis P, Saeed S, Falconnet E, Guipponi M, Pournaras CJ, Ansari MA, Ranza E, Santoni FA, Ahmed J, Shah I, Gul K, Black GC, Bellen HJ, Antonarakis SE. Bi-allelic Loss-of-Function Variants in DNMBP Cause Infantile Cataracts. Am J Hum Genet. 2018 Oct 4;103(4):568-578. PMID: 30290152; PMCID: PMC6174361.

From the abstract: "Infantile and childhood-onset cataracts form a heterogeneous group of disorders; among the many genetic causes, numerous pathogenic variants in additional genes associated with autosomal-recessive infantile cataracts remain to be discovered. We identified three consanguineous families affected by bilateral infantile cataracts. Using exome sequencing, we found homozygous loss-of-function variants in DNMBP ... The phenotypes of all affected individuals include infantile-onset cataracts. RNAi-mediated knockdown of the Drosophila ortholog still life (sif), enriched in lens-secreting cells, affects the development of these cells as well as the localization of E-cadherin, alters the distribution of septate junctions in adjacent cone cells, and leads to a ∼50% reduction in electroretinography amplitudes in young flies. ... We therefore conclude that DNMBP loss-of-function variants cause infantile-onset cataracts in humans."

Big thank you to the US NIH Office of Research Infrastructure Programs (ORIP) for support of projects that generated fly stocks and other resources used in this study.

Wednesday, October 24, 2018

Drosophila studies help identify mutations in NUS1 as contributors to Parkinson's Disease

Guo JF, Zhang L, Li K, Mei JP, Xue J, Chen J, Tang X, Shen L, Jiang H, Chen C, Guo H, Wu XL, Sun SL, Xu Q, Sun QY, Chan P, Shang HF, Wang T, Zhao GH, Liu JY, Xie XF, Jiang YQ, Liu ZH, Zhao YW, Zhu ZB, Li JD, Hu ZM, Yan XX, Fang XD, Wang GH, Zhang FY, Xia K, Liu CY, Zhu XW, Yue ZY, Li SC, Cai HB, Zhang ZH, Duan RH, Tang BS. Coding mutations in NUS1 contribute to Parkinson's disease. Proc Natl Acad Sci U S A. 2018 Oct 22. pii: 201809969. PMID: 30348779.

The abstract: "Whole-exome sequencing has been successful in identifying genetic factors contributing to familial or sporadic Parkinson's disease (PD). However, this approach has not been applied to explore the impact of de novo mutations on PD pathogenesis. Here, we sequenced the exomes of 39 early onset patients, their parents, and 20 unaffected siblings to investigate the effects of de novo mutations on PD. We identified 12 genes with de novo mutations (MAD1L1, NUP98, PPP2CB, PKMYT1, TRIM24, CEP131, CTTNBP2, NUS1, SMPD3, MGRN1, IFI35, and RUSC2), which could be functionally relevant to PD pathogenesis. Further analyses of two independent case-control cohorts (1,852 patients and 1,565 controls in one cohort and 3,237 patients and 2,858 controls in the other) revealed that NUS1 harbors significantly more rare nonsynonymous variants (P = 1.01E-5, odds ratio = 11.3) in PD patients than in controls. Functional studies in Drosophila demonstrated that the loss of NUS1 could reduce the climbing ability, dopamine level, and number of dopaminergic neurons in 30-day-old flies and could induce apoptosis in fly brain. Together, our data suggest that de novo mutations could contribute to early onset PD pathogenesis and identify NUS1 as a candidate gene for PD."

Thursday, October 11, 2018

Drosophila research studies contribute to patient diagnosis for patients with previously undiagnosed diseases

Splinter et al. Effect of Genetic Diagnosis on Patients with Previously Undiagnosed Disease. New England Journal of Medicine. DOI: 10.1056/NEJMoa1714458

This article, which can be accessed free at NEJM, includes a description of how studies in Drosophila and other model systems contribute to identification by the Undiagnosed Diseases Network of disease-causing variants in genome data from previously undiagnosed patients. As stated in the article, "The model organisms screening center was directly involved in the diagnosis of eight patients in this study."

Monday, October 1, 2018

Cross-species study to identify modifiers of alpha-synuclein levels

Rousseaux MWC, Vázquez-Vélez GE, Al-Ramahi I, Jeong HH, Bajic A, Revelli JP, Ye H, Phan ET, Deger JM, Perez AM, Kim JY, Lavery LA, Xu Q, Li MZ, Kang H, Kim JJ, Shulman JM, Westbrook TF, Elledge SJ, Liu Z, Botas J, Zoghbi HY. A druggable genome screen identifies modifiers of α-synuclein levels via a tiered cross-species validation approach. J Neurosci. 2018 Sep 24. pii: 0254-18. PMID: 30249792.

From the abstract: "Accumulation of α-Synuclein (α-Syn) causes Parkinson's disease (PD) as well as other synucleopathies. ... increased α-Syn levels are intrinsically tied to PD pathogenesis and underscore the importance of identifying the factors that regulate its levels. In this study, we establish a pooled RNAi screening approach and validation pipeline to probe the druggable genome for modifiers of α-Syn levels and identify 60 promising targets. Using a cross-species, tiered validation approach, we validate six strong candidates that modulate α-Syn levels and toxicity in cell lines, Drosophila, human neurons and mouse brain of both sexes. ... This approach has broad applicability to the multitude of neurological diseases that are caused by mutations in genes whose dosage is critical for brain function."

Friday, August 31, 2018

Results from a fly genetic screen implicate a long non-coding RNA in Charcot-Marie-Tooth disease

Muraoka Y, Nakamura A, Tanaka R, Suda K, Azuma Y, Kushimura Y, Piccolo LL, Yoshida H, Mizuta I, Tokuda T, Mizuno T, Nakagawa M, Yamaguchi M. Genetic screening of the genes interacting with Drosophila FIG4 identified a novel link between CMT-causing gene and long noncoding RNAs. Exp Neurol. 2018 Aug 27. pii: S0014-4886(18)30377-7. PMID: 30165075.

From the abstract: "Neuron-specific knockdown of the dFIG4 gene, a Drosophila homologue of human FIG4 and one of the causative genes for Charcot-Marie-Tooth disease (CMT), reduces the locomotive abilities of adult flies, as well as causing defects at neuromuscular junctions ... By genetic screening, we detected 9 and 15 chromosomal regions whose deletions either suppressed or enhanced the rough eye phenotype induced by the dFIG4 knockdown. By further genetic screening ... we identified the gene CR18854 that suppressed the rough eye phenotype and the loss-of-cone cell phenotype. The CR18854 gene encodes a long non-coding RNA (lncRNA) consisting of 2566 bases. ... We also obtained data indicating genetic interaction between CR18854 and Cabeza, a Drosophila homologue of human FUS, which is one of the causing genes for amyotrophic lateral sclerosis (ALS). These results suggest that lncRNAs such as CR18854 and hsrω are involved in a common pathway in CMT and ALS pathogenesis."

Wednesday, August 29, 2018

New fly model: Cigarette smoke-induced COPD

Prange R, Thiedmann M, Bhandari A, Mishra N, Sinha A, Häsler R, Rosenstiel P, Uliczka K, Wagner C, Yildirim AÖ, Fink C, Roeder T. A Drosophila model of cigarette smoke induced COPD identifies Nrf2 signaling as an expedient target for intervention. Aging (Albany NY). 2018 Aug 27. PMID: 30153653.

From the abstract: "Chronic obstructive pulmonary disease (COPD) is among the most important causes of death. ... Here, we developed a simple cigarette smoke induced Drosophila model of COPD based on chronic cigarette smoke exposure that recapitulates major pathological hallmarks of the disease and thus can be used to investigate new therapeutic strategies. ... the Drosophila COPD model recapitulates many major hallmarks of COPD and it is highly useful to evaluate the potential of alternative therapeutic strategies."

TREK-1 potassium channel in heart health: From Drosophila genetic screen to mammalian follow-up studies

Abraham DM, Lee TE, Watson LJ, Mao L, Chandok GS, Wang HG, Frangakis S, Pitt GS, Shah SH, Wolf MJ, Rockman HA. The two-pore-domain potassium channel TREK-1 mediates cardiac fibrosis and diastolic dysfunction. J Clin Invest. 2018 Aug 28. PMID: 30153110.

From the abstract: "Cardiac two pore domain potassium channels (K2P) exist in organisms from Drosophila to humans ... We identified a K2P gene, CG8713 (sandman), in a Drosophila genetic screen and show that sandman is critical to cardiac function. Mice lacking an ortholog of sandman, TWIK related potassium channel (TREK-1 or Kcnk2), exhibit exaggerated pressure overload induced concentric hypertrophy and alterations in fetal gene expression ... These findings indicate a central role for cardiac fibroblast TREK-1 in the pathogenesis of pressure overload-induced cardiac dysfunction and serve as a conceptual basis for its inhibition for as a potential therapy."

Tuesday, August 28, 2018

Drosophila, diabetes, and kidney disease

Rani L, Gautam NK. Drosophila renal system as an in-vivo tool for target identification and screening of potential therapeutics for the diabetic nephropathy. Curr Drug Targets. 2018 Aug 7. PMID: 30088447.

From the abstract: "... This review provides evidence for the use of Drosophila renal system as an in-vivo tool for identifying drug target against the disease. ... It also illustrates the use of Drosophila based tools for pre-screening of a potential drug for the disease."

Expression of human disease alleles in Drosophila used to study cellular mechanisms of diseases associated with polyglutamine expansion

Vu A, Humphries T, Vogel S, Haberman A. Polyglutamine repeat proteins disrupt actin structure in Drosophila photoreceptors. Mol Cell Neurosci. 2018 Aug 24. PMID: 30149064.

The abstract: "Expansions of polygutamine-encoding stretches in several genes cause neurodegenerative disorders including Huntington's Disease and Spinocerebellar Ataxia type 3. Expression of the human disease alleles in Drosophila melanogaster neurons recapitulates cellular features of these disorders, and has therefore been used to model the cell biology of these diseases. Here, we show that polyglutamine disease alleles expressed in Drosophila photoreceptors disrupt actin structure at rhabdomeres, as other groups have shown they do in Drosophila and mammalian dendrites. We show this actin regulatory pathway works through the small G protein Rac and the actin nucleating protein Form3. We also find that Form3 has additional functions in photoreceptors, and that loss of Form3 results in the specification of extra photoreceptors in the eye."

Review: Using Drosophila to help interpret genome-wide association study (GWAS) data related to Alzheimer's Disease

Dourlen P, Chapuis J, Lambert JC. Using High-Throughput Animal or Cell-Based Models to Functionally Characterize GWAS Signals. Curr Genet Med Rep. 2018;6(3):107-115. PMID: 30147999; PMCID: PMC6096908.

From the abstract: "... genome-wide association studies (GWASs) constituted a breakthrough in our understanding of the genetic architecture of multifactorial diseases. For Alzheimer's disease (AD), more than 20 risk loci have been identified. However, we are now facing three new challenges: (i) identifying the functional SNP or SNPs in each locus, (ii) identifying the causal gene(s) in each locus, and (iii) understanding these genes' contribution to pathogenesis. ... To address these issues ... a number of high-throughput strategies have been implemented ... Here, we review high-throughput screening, high-content screening, and the use of the Drosophila model (primarily with reference to AD)."

Monday, August 27, 2018

Review: Omega-Class GSTs in Neurodegenerative Diseases

Kim Y, Cha SJ, Choi HJ, Kim K. Omega Class Glutathione S-Transferase: Antioxidant Enzyme in Pathogenesis of Neurodegenerative Diseases. Oxid Med Cell Longev. 2017;2017:5049532. PMID: 29435097; PMCID: PMC5757135.

From the abstract: "The omega class glutathione S-transferases (GSTOs) are multifunctional enzymes involved in cellular defense and have distinct structural and functional characteristics, which differ from those of other GSTs. ... In this review, we briefly introduce recent studies and summarize the novel biological functions and mechanisms underpinning neuroprotective effects of GstOs in Drosophila."

Fly Study Points to Bacterial Regulation of Acetate as Factor in Vibrio cholera virulence

Liimatta K, Flaherty E, Ro G, Nguyen DK, Prado C, Purdy AE. A putative acetylation system in Vibrio cholerae modulates virulence in arthropod hosts. Appl Environ Microbiol. 2018 Aug 24. PMID: 30143508.

From the abstract: "Acetylation is a broadly conserved mechanism of covalently modifying the proteome to precisely control protein activity. In bacteria, central metabolic enzymes and regulatory proteins, including those involved in virulence, can be targeted for acetylation. In this study, we directly link a putative acetylation system to metabolite-dependent virulence in the pathogen Vibrio cholerae ... The Drosophila model of Vibrio cholerae infection has revealed that bacterial regulation of acetate and other small metabolites from within the fly gastrointestinal tract is crucial to its virulence. Here, we demonstrate that genes that may modify the proteome of V. cholerae affect virulence towards Drosophila ... These findings further highlight the many layers of regulation that tune bacterial metabolism to alter the trajectory of interactions between bacteria and their hosts."

Wednesday, August 22, 2018

Review of fly research in the area of Parkinson's disease

Fatima A, Jyoti S, Siddique YH. Models of Parkinson's disease with special emphasis on Drosophila melanogaster. CNS Neurol Disord Drug Targets. 2018 Aug 20. PMID: 30129420.

Abstract: "Parkinson's disease is the second most common neurodegenerative disorder affecting more than 1% of the population average 60. The majority of PD cases are sporadic and are probably caused by a combination of risk factors but 5-10% of the PD cases are familial. Due to the high degree of gene conservation between humans, mice and insects using animal model system is a valuable approach to further elucidate the roles of the genes in PD. The present review highlights the models use to study PD symptoms with special emphasis on Drosophila."

Friday, August 17, 2018

Review of fly research in the area of Huntington's Disease

Rosas-Arellano A, Estrada-Mondragón A, Piña R, Mantellero CA, Castro MA. The Tiny Drosophila Melanogaster for the Biggest Answers in Huntington's Disease. Int J Mol Sci. 2018 Aug 14;19(8). PMID: 30110961.

The abstract: "The average life expectancy for humans has increased over the last years. However, the quality of the later stages of life is low and is considered a public health issue of global importance. Late adulthood and the transition into the later stage of life occasionally leads to neurodegenerative diseases that selectively affect different types of neurons and brain regions, producing motor dysfunctions, cognitive impairment, and psychiatric disorders that are progressive, irreversible, without remission periods, and incurable. Huntington's disease (HD) is a common neurodegenerative disorder. In the 25 years since the mutation of the huntingtin (HTT) gene was identified as the molecule responsible for this neural disorder, a variety of animal models, including the fruit fly, have been used to study the disease. Here, we review recent research that used Drosophila as an experimental tool for improving knowledge about the molecular and cellular mechanisms underpinning HD."

Tuesday, August 14, 2018

Preprint: "A Drosophila Model for Behavioral Sleep Modification"

BioRxiv Preprint: "A Drosophila Model for Behavioral Sleep Modification"
Samuel J Belfer, Alexander G Bashaw, Michael L Perlis, Matthew S Kayser



From the abstract: "Insomnia is the most common sleep disorder among adults, especially affecting individuals of advanced age or with neurodegenerative disease. ... Cognitive Behavioral Therapy for Insomnia (CBT-I) is the first-line treatment for insomnia ... Despite the well-documented efficacy of CBT-I, little is known regarding how CBT-I works at a cellular and molecular level ... Here, guided by human behavioral sleep therapies, we developed a Drosophila model for behavioral modification of sleep. ... We apply this sleep opportunity restriction paradigm to aging and Alzheimer's disease fly models, and find that sleep impairments in these models are reversible with sleep restriction ... This work establishes a model to investigate the neurobiological basis of CBT-I, and provides a platform that can be exploited towards novel treatment targets for insomnia."

Friday, July 27, 2018

Using fruit flies and house flies to study cholera

Purdy AE. Fly Models of Vibrio cholerae Infection and Colonization. Methods Mol Biol. 2018;1839:77-96. doi: 10.1007/978-1-4939-8685-9_8. PubMed PMID: 30047056.

From the abstract: "Studies of Vibrio cholerae pathogenesis in the context of novel eukaryotic model systems have expanded our understanding of genes that underlie V. cholerae interactions with humans, as well as host organisms in the environment. ... The Drosophila model for V. cholerae infection is a powerful tool for discovering new genetic pathways that govern bacterial physiology and colonization in the arthropod gastrointestinal tract. Assays to measure both virulence and colonization have been established and are easily adopted in labs unfamiliar with Drosophila work. Experiments to compare survival of flies colonized with different bacterial mutants are simple to perform and can be completed in less than a week, allowing colonization to be quantified and localized easily. The availability of molecular and genetic tools for the fly enables further exploration of host factors that restrict V. cholerae colonization and invasive infection. Based on the Drosophila system, a house fly (Musca domestica) model of V. cholerae colonization has also been developed. The new house fly model may prove a useful tool for examining V. cholerae infection dynamics in the context of a host carrying a complex microbial community, with a fundamentally different ecology that may increase its chances of acting as a vector for cholera disease."

Wednesday, July 25, 2018

Neurons vs. Glia: "Paradigm shift" in understanding a disease mechanism suggested by results of fly research

Hope KA, LeDoux MS, Reiter LT. Glial overexpression of Dube3a causes seizures and synaptic impairments in Drosophila concomitant with down regulation of the Na(+)/K(+) pump ATPα. Neurobiol Dis. 2017 Dec;108:238-248. PMID: 28888970; PMCID: PMC5675773.

Abstract: "Duplication 15q syndrome (Dup15q) is an autism-associated disorder co-incident with high rates of pediatric epilepsy. Additional copies of the E3 ubiquitin ligase UBE3A are thought to cause Dup15q phenotypes, yet models overexpressing UBE3A in neurons have not recapitulated the epilepsy phenotype. We show that Drosophila endogenously expresses Dube3a (fly UBE3A homolog) in glial cells and neurons, prompting an investigation into the consequences of glial Dube3a overexpression. Here we expand on previous work showing that the Na+/K+ pump ATPα is a direct ubiquitin ligase substrate of Dube3a. A robust seizure-like phenotype was observed in flies overexpressing Dube3a in glial cells, but not neurons. Glial-specific knockdown of ATPα also produced seizure-like behavior, and this phenotype was rescued by simultaneously overexpressing ATPα and Dube3a in glia. Our data provides the basis of a paradigm shift in Dup15q research given that clinical phenotypes have long been assumed to be due to neuronal UBE3A overexpression."

Monday, July 23, 2018

Review: Drosophila as a model for study of Ras-related biology and disease

Goyal Y, Schüpbach T, Shvartsman SY. A quantitative model of developmental RTK signaling. Dev Biol. 2018 Jul 17. pii: S0012-1606(18)30357-9. PMID: 30026122.

From the abstract: "Receptor tyrosine kinases (RTKs) control a wide range of developmental processes, from the first stages of embryogenesis to postnatal growth and neurocognitive development in the adult. A significant share of our knowledge about RTKs comes from genetic screens in model organisms ... Aberrant activation of such pathways has also been recognized in many forms of cancer. More recently, studies of human developmental syndromes established that excessive activation of RTKs and their downstream signaling effectors, most notably the Ras signaling pathway, can also lead to structural and functional defects. ... This mini review summarizes current state of knowledge about Torso-dependent Ras activation and discusses its potential to serve as a quantitative model for studying the general principles of Ras signaling in development and disease."

What are the RASopathies? Answers at RASopathiesNET.

Two reviews discuss Notch signaling research and related human diseases

Salazar JL, Yamamoto S. Integration of Drosophila and Human Genetics to Understand Notch Signaling Related Diseases. Adv Exp Med Biol. 2018;1066:141-185. PMID: 30030826.

Abstract: "Notch signaling research dates back to more than one hundred years, beginning with the identification of the Notch mutant in the fruit fly Drosophila melanogaster. Since then, research on Notch and related genes in flies has laid the foundation of what we now know as the Notch signaling pathway. In the 1990s, basic biological and biochemical studies of Notch signaling components in mammalian systems, as well as identification of rare mutations in Notch signaling pathway genes in human patients with rare Mendelian diseases or cancer, increased the significance of this pathway in human biology and medicine. In the 21st century, Drosophila and other genetic model organisms continue to play a leading role in understanding basic Notch biology. Furthermore, these model organisms can be used in a translational manner to study underlying mechanisms of Notch-related human diseases and to investigate the function of novel disease associated genes and variants. In this chapter, we first briefly review the major contributions of Drosophila to Notch signaling research, discussing the similarities and differences between the fly and human pathways. Next, we introduce several biological contexts in Drosophila in which Notch signaling has been extensively characterized. Finally, we discuss a number of genetic diseases caused by mutations in genes in the Notch signaling pathway in humans and we expand on how Drosophila can be used to study rare genetic variants associated with these and novel disorders. By combining modern genomics and state-of-the art technologies, Drosophila research is continuing to reveal exciting biology that sheds light onto mechanisms of disease."

Alfred V, Vaccari T. Mechanisms of Non-canonical Signaling in Health and Disease: Diversity to Take Therapy up a Notch? Adv Exp Med Biol. 2018;1066:187-204. PMID: 30030827.

Abstract: "Non-canonical Notch signaling encompasses a wide range of cellular processes, diverging considerably from the established paradigm. It can dispense of ligand, proteolytic or nuclear activity. Non-canonical Notch signaling events have been studied mostly in the fruit fly Drosophila melanogaster, the organism in which Notch was identified first and a powerful model for understanding signaling outcomes. However, non-canonical events are ill-defined and their involvement in human physiology is not clear, hampering our understanding of diseases arising from Notch signaling alterations. At a time in which therapies based on specific targeting of Notch signaling are still an unfulfilled promise, detailed understanding of non-canonical Notch events might be key to devising more specific and less toxic pharmacologic options. Based on the blueprint of non-canonical signaling in Drosophila, here, we review and rationalize current evidence about non-canonical Notch signaling. Our effort might inform Notch biologists developing new research avenues and clinicians seeking future treatment of Notch-dependent diseases."

Thursday, July 19, 2018

New fly model of FUS toxicity

Bogaert E, Boeynaems S, Kato M, Guo L, Caulfield TR, Steyaert J, Scheveneels W, Wilmans N, Haeck W, Hersmus N, Schymkowitz J, Rousseau F, Shorter J, Callaerts P, Robberecht W, Van Damme P, Van Den Bosch L. Molecular Dissection of FUS Points at Synergistic Effect of Low-Complexity Domains in Toxicity. Cell Rep. 2018 Jul 17;24(3):529-537.e4. PMID: 30021151.

From the abstract: "RNA-binding protein aggregation is a pathological hallmark of several neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). To gain better insight into the molecular interactions underlying this process, we investigated FUS, which is mutated and aggregated in both ALS and FTLD. We generated a Drosophila model of FUS toxicity ..."

Wednesday, July 18, 2018

Review -- Fruit Flies in the study of Human Genetic Disease

Oriel C, Lasko P. Recent Developments in Using Drosophila as a Model for Human Genetic Disease. Int J Mol Sci. 2018 Jul 13;19(7). pii: E2041. PMID: 30011838.

Abstract: "Many insights into human disease have been built on experimental results in Drosophila, and research in fruit flies is often justified on the basis of its predictive value for questions related to human health. Additionally, there is now a growing recognition of the value of Drosophila for the study of rare human genetic diseases, either as a means of validating the causative nature of a candidate genetic variant found in patients, or as a means of obtaining functional information about a novel disease-linked gene when there is little known about it. For these reasons, funders in the US, Europe, and Canada have launched targeted programs to link human geneticists working on discovering new rare disease loci with researchers who work on the counterpart genes in Drosophila and other model organisms. Several of these initiatives are described here, as are a number of output publications that validate this new approach."

Tuesday, July 17, 2018

Drosophila research a highlight in a review article about obesity-related research

Mirth CK, Piper MD. Matching complex dietary landscapes with the signalling pathways that regulate life history traits. Curr Opin Genet Dev. 2017 Dec;47:9-16. doi: 10.1016/j.gde.2017.08.001. PMID: 28822885.

From the abstract: "The rise in obesity in human populations has reinvigorated research focused on how nutrition impacts life history traits, including body size, lifespan, reproductive success, stress resistance and propensity for disease. ... Here, we offer our perspective on how to integrate insights from the cellular to the whole organism to understand the regulation of life history traits."

Wednesday, July 11, 2018

Fly model of cholera used to explore cellular mechanisms of disease

Fast D, Kostiuk B, Foley E, Pukatzki S. Commensal pathogen competition impacts host viability. Proc Natl Acad Sci U S A. 2018 Jul 3;115(27):7099-7104. PMID: 29915049.

From the abstract: "While the structure and regulatory networks that govern type-six secretion system (T6SS) activity of Vibrio cholerae are becoming increasingly clear, we know less about the role of T6SS in disease. Under laboratory conditions, V. cholerae uses T6SS to outcompete many Gram-negative species, including other V. cholerae strains and human commensal bacteria. ... We used the Drosophila melanogaster model of cholera to define the contribution of T6SS to V. cholerae pathogenesis. ... interactions between T6SS and host commensals impact pathogenesis. Inactivation of T6SS, or removal of commensal bacteria, attenuates disease severity. Reintroduction of the commensal, Acetobacter pasteurianus, into a germ-free host is sufficient to restore T6SS-dependent pathogenesis in which T6SS and host immune responses regulate viability. Together, our data demonstrate that T6SS acts on commensal bacteria to promote the pathogenesis of V. cholerae."

Review article: "Insights from intoxicated Drosophila"

Petruccelli E, Kaun KR. Insights from intoxicated Drosophila. Alcohol. 2018 Mar 21. pii: S0741-8329(18)30040-5. doi: 10.1016/j.alcohol.2018.03.004. PMID: 29980341.

The abstract: "Our understanding of alcohol use disorder (AUD), particularly alcohol's effects on the nervous system, has unquestionably benefited from the use of model systems such as Drosophila melanogaster. Here, we briefly introduce the use of flies in alcohol research, and highlight the genetic accessibility and neurobiological contribution that flies have made to our understanding of AUD. Future fly research offers unique opportunities for addressing unresolved questions in the alcohol field, such as the neuromolecular and circuit basis for cravings and alcohol-induced neuroimmune dysfunction. This review strongly advocates for interdisciplinary approaches and translational collaborations with the united goal of confronting the major health problems associated with alcohol abuse and addiction."

Review: Fly models in the study of Friedreich's Ataxia

Monnier V, Llorens JV, Navarro JA. Impact of Drosophila Models in the Study and Treatment of Friedreich's Ataxia. Int J Mol Sci. 2018 Jul 7;19(7). PMID: 29986523.

From the abstract: "Drosophila melanogaster has been for over a century the model of choice of several neurobiologists to decipher the formation and development of the nervous system as well as to mirror the pathophysiological conditions of many human neurodegenerative diseases. The rare disease Friedreich’s ataxia (FRDA) is not an exception. Since the isolation of the responsible gene more than two decades ago, the analysis of the fly orthologue has proven to be an excellent avenue to understand the development and progression of the disease, to unravel pivotal mechanisms underpinning the pathology and to identify genes and molecules that might well be either disease biomarkers or promising targets for therapeutic interventions. In this review, we aim to summarize the collection of findings provided by the Drosophila models but also to go one step beyond and propose the implications of these discoveries for the study and cure of this disorder. ..."

Study investigates impact of human LAMP2A in Drosophila model of Parkinsons disease

Issa AR, Sun J, Petitgas C, Mesquita A, Dulac A, Robin M, Mollereau B, Jenny A, Chérif-Zahar B, Birman S. The lysosomal membrane protein LAMP2A promotes autophagic flux and prevents SNCA-induced Parkinson disease-like symptoms in the Drosophila brain. Autophagy. 2018 Jul 10. PMID: 29989488.

From the abstract: "The autophagy-lysosome pathway plays a fundamental role in the clearance of aggregated proteins and protection against cellular stress and neurodegenerative conditions. Alterations in autophagy processes, including macroautophagy and chaperone-mediated autophagy (CMA), have been described in Parkinson disease (PD). CMA is a selective autophagic process that depends on LAMP2A (Lysosomal associated membrane protein 2A), a mammal and bird-specific membrane glycoprotein that translocates cytosolic proteins containing a KFERQ-like peptide motif across the lysosomal membrane. Drosophila reportedly lack CMA and use endosomal microautophagy (eMI) as an alternative selective autophagic process. Here we report that neuronal expression of human LAMP2A protected Drosophila against starvation and oxidative stress, and delayed locomotor decline in aging flies without extending their lifespan. LAMP2A also prevented the progressive locomotor and oxidative defects induced by neuronal expression of PD-associated human SNCA (synuclein alpha) with alanine-to-proline mutation at position 30 (SNCAA30P). ... These results indicate that LAMP2A can promote autophagosome formation and potentiate autophagic flux in the Drosophila brain, leading to enhanced stress resistance and neuroprotection."

Tuesday, July 10, 2018

Cactus-feeding flies provide opportunity for study of metabolic syndrome

Cázarez-García D, Ramírez Loustalot-Laclette M, Ann Markow T, Winkler R. Lipidomic profiles of Drosophila melanogaster and cactophilic fly species: models of human metabolic diseases. Integr Biol (Camb). 2017 Nov 13;9(11):885-891. doi: 10.1039/c7ib00155j. PubMed PMID: 29043354.

Abstract: "The metabolic syndrome (MetS) is associated with serious diseases and represents an important threat for global public health. The common fruit fly (Drosophila melanogaster) has served as a model organism to study physiological processes of the MetS, because central metabolic pathways are conserved among species, and because the flies are easy to cultivate in a laboratory. In nature, D. melanogaster is a fruit generalist, feeding on diets rich in simple carbohydrates. Other Drosophilids, however, have specialized on distinct resources. Drosophila mojavensis, for example, is endemic to the Sonoran Desert, where it feeds on necrotic cacti which are low in carbohydrates. Its close relative Drosophila arizonae is cactophilic as well, but is also found breeding in fruits containing simple sugars. Previous studies have shown that high-sugar diets negatively affect the larval development of D. mojavensis and increase their triglyceride content, compared to D. melanogaster. More general metabolic profiles, in response to these different diets, however, have yet to be produced for any of the species. In addition, because D. arizonae appears somewhat intermediate between D. melanogaster and D. mojavensis in its development times and survival under the above mentioned diets, its general metabolic profiles are also of interest. Thus, in the present study we ask to what extent the general metabolism of these three different Drosophila species is affected by diets of distinct protein-sugar ratios. To obtain an un-biased view on possibly novel phenomena, we combined untargeted metabolomics with Random Forest data mining."

Monday, July 9, 2018

Book: Drosophila Models of Human Diseases

The book Drosophila Models of Human Diseases (Masamitsu Yamaguchi, editor) is now available. Chapters include coverage of neurodegenerative diseases, cancer, 'humanized' fly resources, and other topics. More information at the publisher's website.

Interested in books about Drosophila research? See also this page.

Effects of genistein in a fly model of Parkinsons Disease

Siddique YH, Naz F, Jyoti S, Ali F, Rahul. Effect of Genistein on the Transgenic Drosophila Model of Parkinson's Disease. J Diet Suppl. 2018 Jul 3:1-14. PMID: 29969325.

From the abstract: "Parkinson's disease (PD) is the second-most common neurodegenerative disorder and is characterized by the degeneration of dopaminergic neurons in the substantia nigra pars compacta. ... PD flies were exposed to 10, 20, 30, and 40 µM of genistein (mixed in diet) for 24 days. A significant dose-dependent increase in the life span and delay in the loss of climbing ability were observed in the PD flies exposed to genistein (p < .05). A significant dose-dependent decrease in oxidative stress markers and increase in dopamine content were observed in PD flies exposed to genistein. However, the exposure of genistein did not inhibit the expression of α-synuclein in the brains of PD flies."

Metabolic study in a Drosophila model of Huntington Disease

Sameni S, Syed A, Marsh JL, Digman MA. The phasor-FLIM fingerprints reveal shifts from OXPHOS to enhanced glycolysis in Huntington Disease. Sci Rep. 2016 Oct 7;6:34755. doi: 10.1038/srep34755. PubMed PMID: 27713486; PubMed Central PMCID: PMC5054433.

From the abstract: "Huntington disease (HD) is an autosomal neurodegenerative disorder ... Impairment in energy metabolism is a common trend in Huntington pathogenesis ... Here, we used the phasor approach and Fluorescence Lifetime Imaging Microscopy (FLIM) to measure changes between free and bound fractions of NADH as a indirect measure of metabolic alteration in living cells. Using Phasor-FLIM, pixel maps of metabolic alteration in HEK293 cell lines and in transgenic Drosophila expressing expanded and unexpanded polyQ HTT exon1 in the eye disc were developed. We found a significant shift towards increased free NADH, indicating an increased glycolytic state for cells and tissues expressing the expanded polyQ compared to unexpanded control. In the nucleus, a further lifetime shift occurs towards higher free NADH suggesting a possible synergism between metabolic dysfunction and transcriptional regulation. Our results indicate that metabolic dysfunction in HD shifts to increased glycolysis leading to oxidative stress and cell death. This powerful label free method can be used to screen native HD tissue samples and for potential drug screening."

Drosophila used in study related to polyQ-related neurodegeneration

Zhang Q, Chen ZS, An Y, Liu H, Hou Y, Li W, Lau KF, Koon AC, Ngo JCK, Chan HYE. A peptidylic inhibitor for neutralizing expanded CAG RNA-induced nucleolar stress in polyglutamine diseases. RNA. 2018 Apr;24(4):486-498. PMID: 29295891; PMCID: PMC5855950.

Abstract: "Polyglutamine (polyQ) diseases are a class of progressive neurodegenerative disorders characterized by the expression of both expanded CAG RNA and misfolded polyQ protein. We previously reported that the direct interaction between expanded CAG RNA and nucleolar protein nucleolin (NCL) impedes preribosomal RNA (pre-rRNA) transcription, and eventually triggers nucleolar stress-induced apoptosis in polyQ diseases. Here, we report that a 21-amino acid peptide, named "beta-structured inhibitor for neurodegenerative diseases" (BIND), effectively suppresses toxicity induced by expanded CAG RNA. When administered to a cell model, BIND potently inhibited cell death induced by expanded CAG RNA with an IC50 value of ∼0.7 µM. We showed that the function of BIND is dependent on Glu2, Lys13, Gly14, Ile18, Glu19, and Phe20. BIND treatment restored the subcellular localization of nucleolar marker protein and the expression level of pre-45s rRNA Through isothermal titration calorimetry analysis, we demonstrated that BIND suppresses nucleolar stress via a direct interaction with CAG RNA in a length-dependent manner. The mean binding constants (KD) of BIND to SCA2CAG22 , SCA2CAG42 , SCA2CAG55 , and SCA2CAG72 RNA are 17.28, 5.60, 4.83, and 0.66 µM, respectively. In vivo, BIND ameliorates retinal degeneration and climbing defects, and extends the lifespan of Drosophila expressing expanded CAG RNA. These effects suggested that BIND can suppress neurodegeneration in diverse polyQ disease models in vivo and in vitro without exerting observable cytotoxic effect. Our results collectively demonstrated that BIND is an effective inhibitor of expanded CAG RNA-induced toxicity in polyQ diseases."

Drosophila used in study related to ALS/FTLD

Mordes DA, Prudencio M, Goodman LD, Klim JR, Moccia R, Limone F, Pietilainen O, Chowdhary K, Dickson DW, Rademakers R, Bonini NM, Petrucelli L, Eggan K. Dipeptide repeat proteins activate a heat shock response found in C9ORF72-ALS/FTLD patients. Acta Neuropathol Commun. 2018 Jul 4;6(1):55. PMID: 29973287.

Abstract: "A hexanucleotide (GGGGCC) repeat expansion in C9ORF72 is the most common genetic contributor to amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). Reduced expression of the C9ORF72 gene product has been proposed as a potential contributor to disease pathogenesis. Additionally, repetitive RNAs and dipeptide repeat proteins (DPRs), such as poly-GR, can be produced by this hexanucleotide expansion that disrupt a number of cellular processes, potentially contributing to neural degeneration. To better discern which of these mechanisms leads to disease-associated changes in patient brains, we analyzed gene expression data generated from the cortex and cerebellum. We found that transcripts encoding heat shock proteins (HSPs) regulated by the HSF1 transcription factor were significantly induced in C9ORF72-ALS/FTLD patients relative to both sporadic ALS/FTLD cases and controls. Treatment of human neurons with chemically synthesized DPRs was sufficient to activate a similar transcriptional response. Expression of GGGGCC repeats and also poly-GR in the brains of Drosophila lead to the upregulation of HSF1 and the same highly-conserved HSPs. Additionally, HSF1 was a modifier of poly-GR toxicity in Drosophila. Our results suggest that the expression of DPRs are associated with upregulation of HSF1 and activation of a heat shock response in C9ORF72-ALS/FTLD."

Investigation of the effects of green tea on a fly model of Huntington's Disease

Varga J, Dér NP, Zsindely N, Bodai L. Green tea infusion alleviates neurodegeneration induced by mutant Huntingtin in Drosophila. Nutr Neurosci. 2018 Jul 4:1-7. PMID: 29973113.

From the abstract: "Green tea infusion contains a complex mixture of polyphenolic compounds that were shown to provide health benefits. It was previously demonstrated that (-)-epigallocatechin-3-gallate, ... present in green tea, has a suppressing effect on various aspects of pathogenesis in models of Huntington's disease (HD) ... In this study, we aimed to investigate, whether green tea infusion prepared as for human consumption has similar positive effects. ... We used a transgenic Drosophila model of HD to study the effects of green tea on mutant Huntingtin induced phenotypes. ... We found that green tea supplementation reduced mutant Huntingtin induced neurodegeneration in Drosophila and positively impacted the longevity of mutant Huntingtin expressing flies. However, green tea did not rescue reduced viability of Drosophila expressing mutant Huntingtin or increased longevity of wild-type fruit flies. ... Our results indicate that green tea consumption might have a modest positive effect on symptoms of HD."

Review of use of various model organisms for Alzheimer's-related research

Sharma N, Khurana N, Muthuraman A. Lower vertebrate and invertebrate models of Alzheimer's disease - A review. Eur J Pharmacol. 2017 Nov 15;815:312-323. PMID: 28943103.

From the abstract: "Alzheimer's disease is a common neurodegenerative disorder ... various lower chordate animals like Danio rerio, Drosophila melanogaster, Caenorhabditis elegans and Ciona intestinalis have been proved to be an important model for the in vivo determination of targets of drugs with least limitations. In this article, we reviewed different studies conducted on theses models for the better understanding of the pathophysiology of AD and their subsequent application as a potential tool in the preclinical evaluation of new drugs."

Fruit flies and kidney disease -- a review and a research article

Millet-Boureima C, Porras Marroquin J, Gamberi C. Modeling Renal Disease "On the Fly". Biomed Res Int. 2018 May 31;2018:5697436. doi: 10.1155/2018/5697436. eCollection 2018. Review. PubMed PMID: 29955604; PubMed Central PMCID: PMC6000847.

Abstract: "Detoxification is a fundamental function for all living organisms that need to excrete catabolites and toxins to maintain homeostasis. Kidneys are major organs of detoxification that maintain water and electrolyte balance to preserve physiological functions of vertebrates. In insects, the renal function is carried out by Malpighian tubules and nephrocytes. Due to differences in their circulation, the renal systems of mammalians and insects differ in their functional modalities, yet carry out similar biochemical and physiological functions and share extensive genetic and molecular similarities. Evolutionary conservation can be leveraged to model specific aspects of the complex mammalian kidney function in the genetic powerhouse Drosophila melanogaster to study how genes interact in diseased states. Here, we compare the human and Drosophila renal systems and present selected fly disease models."

Hermle T, Schneider R, Schapiro D, Braun DA, van der Ven AT, Warejko JK, Daga A, Widmeier E, Nakayama M, Jobst-Schwan T, Majmundar AJ, Ashraf S, Rao J, Finn LS, Tasic V, Hernandez JD, Bagga A, Jalalah SM, El Desoky S, Kari JA, Laricchia KM, Lek M, Rehm HL, MacArthur DG, Mane S, Lifton RP, Shril S, Hildebrandt F. GAPVD1 and ANKFY1 Mutations Implicate RAB5 Regulation in Nephrotic Syndrome. J Am Soc Nephrol. 2018 Jun 29. pii: ASN.2017121312. doi: 10.1681/ASN.2017121312. [Epub ahead of print] PubMed PMID: 29959197.

From the abstract: "... Steroid-resistant nephrotic syndrome (SRNS) is a frequent cause of CKD. The discovery of monogenic causes of SRNS has revealed specific pathogenetic pathways, but these monogenic causes do not explain all cases of SRNS. ... To identify novel monogenic causes of SRNS, we screened 665 patients by whole-exome sequencing. We then evaluated the in vitro functional significance of two genes and the mutations therein that we discovered through this sequencing and conducted complementary studies in podocyte-like Drosophila nephrocytes. ... In Drosophila, silencing Gapvd1 impaired endocytosis and caused mistrafficking of the nephrin ortholog. ... Mutations in GAPVD1 and probably in ANKFY1 are novel monogenic causes of NS. The discovery of these genes implicates RAB5 regulation in the pathogenesis of human NS."

Friday, June 29, 2018

Review of DNA repair, disease, and Drosophila research

Cotterill S. Diseases Associated with Mutation of Replication and Repair Proteins. Adv Exp Med Biol. 2018;1076:215-234. PMID: 29951822.

The abstract: "Alterations in proteins that function in DNA replication and repair have been implicated in the development of human diseases including cancer, premature ageing, skeletal disorders, mental retardation, microcephaly, and neurodegeneration. Drosophila has orthologues of most human replication and repair proteins and high conservation of the relevant cellular pathways, thus providing a versatile system in which to study how these pathways are corrupted leading to the diseased state. In this chapter I will briefly review the diseases associated with defects in replication and repair proteins and discuss how past and future studies on the Drosophila orthologues of such proteins can contribute to the dissection of the mechanisms involved in disease development."

Discussion of Drosophila-based bioassay of prion infectivity

Thackray AM, Andréoletti O, Bujdoso R. The use of PrP transgenic Drosophila to replace and reduce vertebrate hosts in the bioassay of mammalian prion infectivity. F1000Res. 2018 May 15;7:595. PMID: 29946445; PMCID: PMC5998032.

The abstract: "Prion diseases are fatal neurodegenerative conditions of humans and vertebrate species. The transmissible prion agent is a novel infectious particle composed principally of PrP Sc, an abnormal isomer of the normal host protein PrP C. The only reliable method to detect mammalian prion infectivity is by bioassay, invariably in a vertebrate host. The current prion bioassays typically involve intracerebral or peripheral inoculation of test material into the experimental host and subsequent euthanasia when clinical signs of terminal prion disease become evident. It may be months or years before the onset of clinical disease becomes evident and a pre-determined clinical end-point is reached. Consequently, bioassay of prion infectivity in vertebrate species is cumbersome, time consuming, expensive, and increasingly open to ethical debate because these animals are subjected to terminal neurodegenerative disease. Prions are a significant risk to public health through the potential for zoonotic transmission of animal prion diseases. Attention has focussed on the measurement of prion infectivity in different tissues and blood from prion-infected individuals in order to determine the distribution of infectious prions in diseased hosts. New animal models are required in order to replace or reduce, where possible, the dependency on the use of vertebrate species, including the 'gold standard' mouse prion bioassay, to assess prion infectivity levels. Here we highlight the development of a Drosophila-based prion bioassay, a highly sensitive and rapid invertebrate animal system that can efficiently detect mammalian prions. This novel invertebrate model system will be of considerable interest to biologists who perform prion bioassays as it will promote reduction and replacement in the number of sentient animals currently used for this purpose. This article is a composite of previous methods that provides an overview of the methodology of the model and discusses the experimental data to promote its viability for use instead of more sentient hosts."

Monday, June 25, 2018

Fly studies used to gain functional understanding of changes associated with Huntington's disease

Al-Ramahi I, Lu B, Di Paola S, Pang K, de Haro M, Peluso I, Gallego-Flores T, Malik NT, Erikson K, Bleiberg BA, Avalos M, Fan G, Rivers LE, Laitman AM, Diaz-García JR, Hild M, Palacino J, Liu Z, Medina DL, Botas J. High-Throughput Functional Analysis Distinguishes Pathogenic, Nonpathogenic, and Compensatory Transcriptional Changes in Neurodegeneration. Cell Syst. 2018 Jun 6. pii: S2405-4712(18)30228-X. PMID: 29936182.

From the abstract: "Discriminating transcriptional changes that drive disease pathogenesis from nonpathogenic and compensatory responses is a daunting challenge. ... Here we integrate functional testing and network approaches to analyze previously reported transcriptional alterations in the brains of Huntington disease (HD) patients. We selected 312 genes whose expression is dysregulated both in HD patients and in HD mice and then replicated and/or antagonized each alteration in a Drosophila HD model. High-throughput behavioral testing in this model and controls revealed that transcriptional changes in synaptic biology and calcium signaling are compensatory, whereas alterations involving the actin cytoskeleton and inflammation drive disease. Knockdown of disease-driving genes in HD patient-derived cells lowered mutant Huntingtin levels and activated macroautophagy, suggesting a mechanism for mitigating pathogenesis. Our multilayered approach can thus untangle the wealth of information generated by transcriptomics and identify early therapeutic intervention points."

Drosophila study informs understanding of Wolfram syndrome 1

Sakakibara Y, Sekiya M, Fujisaki N, Quan X, Iijima KM. Knockdown of wfs1, a fly homolog of Wolfram syndrome 1, in the nervous system increases susceptibility to age- and stress-induced neuronal dysfunction and degeneration in Drosophila. PLoS Genet. 2018 Jan 22;14(1):e1007196. PMID: 29357349; PMCID: PMC5794194.

From the abstract: "Wolfram syndrome (WS), caused by loss-of-function mutations in the Wolfram syndrome 1 gene (WFS1), is characterized by juvenile-onset diabetes mellitus, bilateral optic atrophy, and a wide spectrum of neurological and psychiatric manifestations. ... the mechanisms underlying neurodegeneration caused by WFS1 deficiency remain elusive. Here, we investigated the role of WFS1 in the maintenance of neuronal integrity in vivo by knocking down the expression of wfs1, the Drosophila homolog of WFS1, in the central nervous system. Neuronal knockdown of wfs1 caused age-dependent behavioral deficits and neurodegeneration in the fly brain. ... This study highlights the protective role of wfs1 against age-associated neurodegeneration and furthers our understanding of potential disease-modifying factors that determine susceptibility and resilience to age-associated neurodegenerative diseases."

Wednesday, June 20, 2018

Genetic modifiers of neurodegeneration

Early online from Genetics:

Genetic Modifiers of Neurodegeneration in a Drosophila Model of Parkinson's Disease
Sierra Lavoy, Vinita G. Chittoor-Vinod, Clement Y. Chow and Ian Martin

From the abstract: "... There is increasing evidence that background genetic variation is a strong driver of disease variability ... To understand the genotype-phenotype relationship ... a large number of backgrounds must be studied. This can be efficiently achieved using model organism collections such as the Drosophila Genetic Reference Panel (DGRP). Here, we used the DGRP to assess the variability of locomotor dysfunction in a LRRK2 G2019S Drosophila melanogaster model of Parkinson's disease. We find substantial variability in the LRRK2 G2019S locomotor phenotype in different DGRP backgrounds. A genome-wide association study for candidate genetic modifiers reveals 177 genes that drive wide phenotypic variation, including 19 top association genes. Genes involved in the outgrowth and regulation of neuronal projections are enriched in these candidate modifiers. RNAi functional testing of the top association and neuronal projection-related genes reveals that pros, pbl, ct and CG33506 significantly modify age-related dopamine neuron loss and associated locomotor dysfunction in the Drosophila LRRK2 G2019S model. These results demonstrate how natural genetic variation can be used as a powerful tool to identify genes that modify disease-related phenotypes. ..."

Monday, June 4, 2018

Fly model contributes to understanding of spinocerebellar ataxia type 1

Bondar VV, Adamski CJ, Onur TS, Tan Q, Wang L, Diaz-Garcia J, Park J, Orr HT, Botas J, Zoghbi HY. PAK1 regulates ATXN1 levels providing an opportunity to modify its toxicity in Spinocerebellar ataxia type 1. Hum Mol Genet. 2018 May 30. PMID: 29860311.

The abstract: "Spinocerebellar ataxia type 1 (SCA1) is caused by the expansion of a trinucleotide repeat that encodes a polyglutamine tract in ataxin-1 (ATXN1). The expanded polygultamine in ATXN1 increases the protein's stability and results in its accumulation and toxicity. Previous studies have demonstrated that decreasing ATXN1 levels ameliorates SCA1 phenotypes and pathology in mouse models. We rationalized that reducing ATXN1 levels through pharmacological inhibition of its modulators could provide a therapeutic avenue for SCA1. Here, through a forward genetic screen in Drosophila we identified, p21-activated kinase 3 (Pak3) as a modulator of ATXN1 levels. Loss-of-function of fly Pak3 and Pak1, whose mammalian homologs are Group I of PAKs, reduces ATXN1 levels, and accordingly, improves disease pathology in a Drosophila model of SCA1. Knockdown of PAK1 potently reduces ATXN1 levels in mammalian cells independent of the well-characterized S776 phosphorylation site (known to stabilize ATXN1) thus revealing a novel molecular pathway that regulates ATXN1 levels. Furthermore, pharmacological inhibition of PAKs decreases ATXN1 levels in a mouse model of SCA1. To explore the potential of using PAK inhibitors in combination therapy, we combined the pharmacological inhibition of PAK with MSK1, a previously identified modulator of ATXN1, and examined their effects on ATXN1 levels. We found that inhibition of both pathways results in an additive decrease in ATXN1 levels. Together, this study identifies PAK signaling as a distinct molecular pathway that regulates ATXN1 levels and presents a promising opportunity to pursue for developing potential therapeutics for SCA1."

Review of fly models of Friedreich's Ataxia

Calap-Quintana P, Navarro JA, González-Fernández J, Martínez-Sebastián MJ, Moltó MD, Llorens JV. Drosophila melanogaster Models of Friedreich's Ataxia. Biomed Res Int. 2018 Apr 5;2018:5065190. PMID: 29850527; PMCID: PMC5907503.

From the abstract: "Friedreich's ataxia (FRDA) is a rare inherited recessive disorder affecting the central and peripheral nervous systems and other extraneural organs such as the heart and pancreas. This incapacitating condition usually manifests in childhood or adolescence, exhibits an irreversible progression that confines the patient to a wheelchair, and leads to early death. FRDA is caused by a reduced level of the nuclear-encoded mitochondrial protein frataxin due to an abnormal GAA triplet repeat expansion in the first intron of the human FXN gene. FXN is evolutionarily conserved, with orthologs in essentially all eukaryotes and some prokaryotes, leading to the development of experimental models of this disease in different organisms. These FRDA models have contributed substantially to our current knowledge of frataxin function and the pathogenesis of the disease, as well as to explorations of suitable treatments. Drosophila melanogaster, an organism that is easy to manipulate genetically, has also become important in FRDA research. This review describes the substantial contribution of Drosophila to FRDA research ..."

Thursday, May 31, 2018

FlyRNAi: in vivo fly RNAi screen identifies ortholog of SPO...

FlyRNAi: in vivo fly RNAi screen identifies ortholog of SPO...: Rossi F, Molnar C, Hashiyama K, Heinen JP, Pampalona J, Llamazares S, Reina J, Hashiyama T, Rai M, Pollarolo G, Fernández-Hernández I, Gonza...

Friday, May 18, 2018

New fly model of Essential Tremor

Smith P, Arias R, Sonti S, Odgerel Z, Santa-Maria I, McCabe BD, Tsaneva-Atanasova K, Louis ED, Hodge JJL, Clark LN. A Drosophila Model of Essential Tremor. Sci Rep. 2018 May 16;8(1):7664. PMID: 29769701.

The abstract: "Essential Tremor (ET) is one of the most common neurological diseases, with an estimated 7 million affected individuals in the US; the pathophysiology of the disorder is poorly understood. Recently, we identified a mutation (KCNS2 (Kv9.2), c.1137 T > A, p.(D379E) in an electrically silent voltage-gated K+ channel α-subunit, Kv9.2, in a family with ET, that modulates the activity of Kv2 channels. We have produced transgenic Drosophila lines that express either the human wild type Kv9.2 (hKv9.2) or the ET causing mutant Kv9.2 (hKv9.2-D379E) subunit in all neurons. We show that the hKv9.2 subunit modulates activity of endogenous Drosophila K+ channel Shab. The mutant hKv9.2-D379E subunit showed significantly higher levels of Shab inactivation and a higher frequency of spontaneous firing rate consistent with neuronal hyperexcitibility. We also observed behavioral manifestations of nervous system dysfunction including effects on night time activity and sleep. This functional data further supports the pathogenicity of the KCNS2 (p.D379E) mutation, consistent with our prior observations including co-segregation with ET in a family, a likely pathogenic change in the channel pore domain and absence from population databases. The Drosophila hKv9.2 transgenic model recapitulates several features of ET and may be employed to advance our understanding of ET disease pathogenesis."

Fly model of neurodegeneration used in study of glycation

Vicente Miranda H, Gomes MA, Branco-Santos J, Breda C, Lázaro DF, Lopes LV, Herrera F, Giorgini F, Outeiro TF. Glycation potentiates neurodegeneration in models of Huntington's disease. Sci Rep. 2016 Nov 18;6:36798. PMID: 27857176; PMCID: PMC5114697.

From the abstract: "Protein glycation is an age-dependent posttranslational modification associated with several neurodegenerative disorders, including Alzheimer's and Parkinson's diseases. By modifying amino-groups, glycation interferes with folding of proteins, increasing their aggregation potential. Here, we studied the effect of pharmacological and genetic manipulation of glycation on huntingtin (HTT), the causative protein in Huntington's disease (HD). ... increased glycation enhanced HTT toxicity in human cells and neurodegeneration in fruit flies, impairing eclosion and decreasing life span. Overall, our study provides evidence that glycation modulates HTT exon-1 aggregation and toxicity ...."

Thursday, May 17, 2018

Fly model of Alzheimer's disease to test a potential therapeutic treatment

Beg T, Jyoti S, Naz F, Rahul, Ali F, Ali SK, Reyad AM, Siddique YH. Protective effect of kaempferol on the transgenic Drosophila model of Alzheimer's disease. CNS Neurol Disord Drug Targets. 2018 May 8. PMID: 29745345.

From the abstract: "Alzheimer's disease (AD) is characterized by the accumulation and deposition of β-amyloid peptides leading to a progressive neuronal damage and cell loss. Besides several hypotheses for explaining the neurodegenerative mechanisms, oxidative stress has been considered to be one of them. Till date, there is no cure for AD, but the pathogenesis of the disease could be delayed by the use of natural antioxidants. In this context, we decided to study the effect of kaempferol against the transgenic Drosophila expressing human Aβ-42. ...The AD flies were allowed to feed on the diet having 10, 20, 30 and 40µM of kaempferol for 30 days. After 30 days of exposure, the Aβ-flies were studied ... The results of the present study reveal that the exposure of AD flies to kaempferol delayed the loss of climbing ability, memory, reduced the oxidative stress and acetylcholinesterase activity."

Context matters: results of fly studies suggests contribution of "deleterious heteromosaicism" to disease

Akiyama T, User SD, Gibson MC. Somatic clones heterozygous for recessive disease alleles of BMPR1A exhibit unexpected phenotypes in Drosophila. Elife. 2018 May 10;7. PMID: 29745898.

The abstract: "The majority of mutations studied in animal models are designated as recessive based on the absence of visible phenotypes in germline heterozygotes. Accordingly, genetic studies primarily rely on homozygous loss-of-function to determine gene requirements, and a conceptually-related 'two-hit model' remains the central paradigm in cancer genetics. Here we investigate pathogenesis due to somatic mutation in epithelial tissues, a process that predominantly generates heterozygous cell clones. To study somatic mutation in Drosophila, we generated inducible alleles that mimic human Juvenile polyposis-associated BMPR1A mutations. Unexpectedly, four of these mutations had no phenotype in heterozygous carriers but exhibited clear tissue-level effects when present in somatic clones of heterozygous cells. We conclude that these alleles are indeed recessive when present in the germline, but nevertheless deleterious when present in heterozygous clones. This unforeseen effect, deleteriousheteromosaicism, suggests a 'one-hit' mechanism for disease initiation that may explain some instances of pathogenesis associated with spontaneous mutation."

Review of Drosophila research related to ALS

Zhang K, Coyne AN, Lloyd TE. Drosophila models of amyotrophic lateral sclerosis with defects in RNA metabolism. Brain Res. 2018 May 9. PMID: 29752901.

From the abstract: " ... The conservation of nervous system biology coupled with the rapid life cycle and powerful genetic tools in the fly have enabled the identification of novel therapeutic targets that have been validated in vertebrate model systems and human patients. A recent example is in the study of the devastating motor neuron degenerative disease amyotrophic lateral sclerosis (ALS). ... In this review, we will discuss the utilization of Drosophila models of ALS with defects in RNA metabolism."

Study of a fly model of fragile X-syndrome suggests "a potentially general mechanism for intellectual disability"

Franco LM, Okray Z, Linneweber GA, Hassan BA, Yaksi E. Reduced Lateral Inhibition Impairs Olfactory Computations and Behaviors in a Drosophila Model of Fragile X Syndrome. Curr Biol. 2017 Apr 24;27(8):1111-1123. PMID: 28366741; PMCID: PMC5405172.

From the abstract: "Fragile X syndrome (FXS) patients present neuronal alterations that lead to severe intellectual disability, but the underlying neuronal circuit mechanisms are poorly understood. An emerging hypothesis postulates that reduced GABAergic inhibition of excitatory neurons is a key component in the pathophysiology of FXS. Here, we directly test this idea in a FXS Drosophila model. ... We provide direct evidence that deficient inhibition impairs sensory computations and behavior in an in vivo model of FXS. Together with evidence of impaired inhibition in autism and Rett syndrome, these findings suggest a potentially general mechanism for intellectual disability."

Also appearing recently, this review:

Drozd M, Bardoni B, Capovilla M. Modeling Fragile X Syndrome in Drosophila. Front Mol Neurosci. 2018 Apr 16;11:124. doi: 10.3389/fnmol.2018.00124. PMID: 29713264; PMCID: PMC5911982.

Fly studies help shed light on contribution of KAT2B variants to ADD3-associated disorders

Gonçalves S, Patat J, Guida MC, Lachaussée N, Arrondel C, Helmstädter M, Boyer O, Gribouval O, Gubler MC, Mollet G, Rio M, Charbit M, Bole-Feysot C, Nitschke P, Huber TB, Wheeler PG, Haynes D, Juusola J, Billette de Villemeur T, Nava C, Afenjar A, Keren B, Bodmer R, Antignac C, Simons M. A homozygous KAT2B variant modulates the clinical phenotype of ADD3 deficiency in humans and flies. PLoS Genet. 2018 May 16;14(5):e1007386. PMID: 29768408.

The abstract: "Recent evidence suggests that the presence of more than one pathogenic mutation in a single patient is more common than previously anticipated. One of the challenges hereby is to dissect the contribution of each gene mutation, for which animal models such as Drosophila can provide a valuable aid. Here, we identified three families with mutations in ADD3, encoding for adducin-γ, with intellectual disability, microcephaly, cataracts and skeletal defects. In one of the families with additional cardiomyopathy and steroid-resistant nephrotic syndrome (SRNS), we found a homozygous variant in KAT2B, encoding the lysine acetyltransferase 2B, with impact on KAT2B protein levels in patient fibroblasts, suggesting that this second mutation might contribute to the increased disease spectrum. In order to define the contribution of ADD3 and KAT2B mutations for the patient phenotype, we performed functional experiments in the Drosophila model. We found that both mutations were unable to fully rescue the viability of the respective null mutants of the Drosophila homologs, hts and Gcn5, suggesting that they are indeed pathogenic in flies. While the KAT2B/Gcn5 mutation additionally showed a significantly reduced ability to rescue morphological and functional defects of cardiomyocytes and nephrocytes (podocyte-like cells), this was not the case for the ADD3 mutant rescue. Yet, the simultaneous knockdown of KAT2B and ADD3 synergistically impaired kidney and heart function in flies as well as the adhesion and migration capacity of cultured human podocytes, indicating that mutations in both genes may be required for the full clinical manifestation. Altogether, our studies describe the expansion of the phenotypic spectrum in ADD3 deficiency associated with a homozygous likely pathogenic KAT2B variant and thereby identify KAT2B as a susceptibility gene for kidney and heart disease in ADD3-associated disorders."

Thursday, May 10, 2018

Review on how fly and worm studies are helping to elucidate mechanisms that how sleep is induced by sickness

Davis KC, Raizen DM. A mechanism for sickness sleep: lessons from invertebrates. J Physiol. 2017 Aug 15;595(16):5415-5424. PMID: 28028818; PubMed Central PMCID: PMC5556163.

From the abstract: "During health, animal sleep is regulated by an internal clock and by the duration of prior wakefulness. During sickness, sleep is regulated by cytokines released from either peripheral cells or from cells within the nervous system. These cytokines regulate central nervous system neurons to induce sleep. Recent research in the invertebrates Caenorhabditis elegans and Drosophila melanogaster has led to new insights into the mechanism of sleep during sickness. ... We will here review key findings that have elucidated the central neuroendocrine mechanism of sleep during sickness. ... We speculate that these mechanisms may play a maladaptive role in human pathological conditions such as in the fatigue and anorexia associated with autoimmune diseases, with major depression, and with unexplained chronic fatigue."

Bubblegum and double bubble: silly fly gene names, serious study related to adrenoleukodystrophy

Gordon HB, Valdez L, Letsou A. Etiology and treatment of adrenoleukodystrophy: new insights from Drosophila. Dis Model Mech. 2018 May 8. pii: dmm.031286. PMID: 29739804.

From the abstract: "Adrenoleukodystrophy (ALD) is a fatal progressive neurodegenerative disorder affecting brain white matter. The most common form of ALD is X-linked (X-ALD) and results from mutation of the ABCD1-encoded very long chain fatty acid (VLCFA) transporter. X-ALD is clinically heterogeneous, with the cerebral form being the most severe. Diagnosed in boys usually between the ages of 4 and 8, cerebral X-ALD symptoms progress rapidly (in as little as two years) through declines in cognition, learning, and behavior, to paralysis and ultimately to a vegetative state and death. Currently, there are no good treatments for X-ALD. Here we exploit the Drosophila bubblegum (bgm) double bubble (dbb) model of neurometabolic disease to expand diagnostic power and therapeutic potential for adrenoleukodystrophy. We show that loss of the Drosophila long/very long chain acyl-CoA synthetase genes bgm and/or dbb is indistinguishable from loss of the Drosophila ABC transporter gene dABCD1 ... we show that it is a lack of lipid metabolic pathway product and not (as commonly thought) an accumulation of pathway precursor that is causative of neurometabolic disease: addition of medium chain fatty acids to the diet of bgm or dbb flies prevents the onset of neurodegeneration. Taken together, our data provide new foundations both for diagnosing adrenoleukodystrophy and for designing effective, mechanism-based treatment protocols."

Tuesday, May 8, 2018

FlyRNAi: Drosophila cell-based RNAi screen related to treat...

FlyRNAi: Drosophila cell-based RNAi screen related to treat...: Lin WH, He M, Fan YN, Baines RA. An RNAi-mediated screen identifies novel targets for next-generation antiepileptic drugs based on increased...

Characterization of a Drosophila model of NGLY1 deficiency

Defects in the Neuroendocrine Axis Contribute to Global Development Delay in a Drosophila Model of NGLY1 Deficiency

Tamy Portillo Rodriguez, Joshua D. Mast, Tom Hartl, Tom Lee, Peter Sand and Ethan O. Perlstein
G3: GENES, GENOMES, GENETICS Early online May 7, 2018;

From the abstract: "N-glycanase 1 (NGLY1) Deficiency is a rare monogenic multi-system disorder ... Here we conducted a natural history study and chemical-modifier screen on the Drosophila melanogaster NGLY1 homolog, Pngl. We generated a new fly model of NGLY1 Deficiency, engineered with a nonsense mutation in Pngl at codon 420 that results in a truncation of the C-terminal carbohydrate-binding PAW domain. Homozygous mutant animals exhibit global development delay, pupal lethality and small body size as adults. ... We found that the cholesterol-derived ecdysteroid molting hormone 20-hydroxyecdysone (20E) partially rescued the global developmental delay in mutant homozygotes. Targeted expression of a human NGLY1 transgene to tissues involved in ecdysteroidogenesis, e.g., prothoracic gland, also partially rescues global developmental delay in mutant homozygotes. Finally, the proteasome inhibitor bortezomib is a potent enhancer of global developmental delay in our fly model ... Together, these results demonstrate the therapeutic relevance of a new fly model of NGLY1 Deficiency for drug discovery and gene modifier screens."

Monday, April 2, 2018

New fly model of mitochondrial disease associated with disruption of SLC25A46

1: Suda K, Ueoka I, Azuma Y, Muraoka Y, Yoshida H, Yamaguchi M. Novel Drosophila model for mitochondrial diseases by targeting of a solute carrier protein SLC25A46. Brain Res. 2018 Mar 28. pii: S0006-8993(18)30163-X. PMID: 29604258.

From the abstract: "Mutations in SLC25A46 gene have been identified in mitochondrial diseases that are sometimes classified as Charcot-Marie-Tooth disease type 2, optic atrophy and Leigh syndrome. Human SLC25A46 functions as a transporter across the outer mitochondrial membrane. However, it is still unknown how the neurodegeneration occurring in these diseases relates to the loss of SLC25A46 function. Drosophila has CG5755 (dSLC25A46) as a single human SLC25A46 homolog. Here we established pan-neuron specific dSLC25A46 knockdown flies, and examined their phenotypes. ... The dSLC25A46 knockdown fly ... recapitulates most of the phenotypes in mitochondrial disease patients, providing a useful tool to study these diseases."

Drosophila analysis helps point to changes in the human gene VPS13D as the cause of a newly identified type of ataxia

Seong E, Insolera R, Dulovic M, Kamsteeg EJ, Trinh J, Brüggemann N, Sandford E, Li S, Ozel AB, Li JZ, Jewett T, Kievit AJA, Münchau A, Shakkottai V, Klein C, Collins C, Lohmann K, van de Warrenburg BP, Burmeister M. Mutations in VPS13D lead to a new recessive ataxia with spasticity and mitochondrial defects. Ann Neurol. 2018 Mar 31. PMID: 29604224.

From the abstract: "... In an international collaboration, we independently performed exome sequencing in seven families with recessive ataxia and/or spastic paraplegia. To evaluate the role of VPS13D mutations, we evaluated a Drosophila knock-out model and investigated mitochondrial function in patient-derived fibroblast cultures. ... Our study demonstrates that compound heterozygous mutations in VPS13D cause movement disorders along the ataxia-spasticity spectrum, making VPS13D the fourth VPS13 paralog involved in neurological disorders. This article is protected by copyright. All rights reserved."

Friday, March 23, 2018

Review article -- Drosophila as a model to study diabetes

Murillo-Maldonado JM, Riesgo-Escovar JR. Development and diabetes on the fly. Mech Dev. 2017 Apr;144(Pt B):150-155. PMID: 27702607.

From the abstract: "... Genetic model organisms, like the common fruit fly, Drosophila melanogaster, offer the possibility of studying the panoply of life processes in normal and diseased states like diabetes mellitus, from a plethora of different perspectives. ..."

Experiments in the fly help identify a genetic cause of primary ovarian insufficiency

Chen A, Tiosano D, Guran T, Baris HN, Bayram Y, Mory A, Shapiro-Kulnane L, Hodges CA, Coban Akdemir Z, Turan S, Jhangiani SN, van den Akker F, Hoppel CL, Salz HK, Lupski JR, Buchner DA. Mutations in the mitochondrial ribosomal protein MRPS22 lead to primary ovarian insufficiency. Hum Mol Genet. 2018 Mar 16. PMID: 29566152.

From the abstract: "Primary ovarian insufficiency (POI) is characterized by amenorrhea and loss or dysfunction of ovarian follicles prior to the age of 40. ... the genetic etiology of POI most often remains unknown. Here we report MRPS22 homozygous missense variants ... identified in four females ... as a novel genetic cause of POI in adolescents. Both missense mutations identified in MRPS22 are rare, occurred in highly evolutionarily conserved residues, and are predicted to be deleterious to protein function. .... Furthermore, we demonstrate in a Drosophila model that mRpS22 deficiency specifically in somatic cells of the ovary had no effect on fertility, whereas flies with mRpS22 deficiency specifically in germ cells were infertile and agametic, demonstrating a cell autonomous requirement for mRpS22 in germ cell development. These findings collectively identify that MRPS22 ... is critical for ovarian development and may therefore provide insight into the pathophysiology and treatment of ovarian dysfunction."

Wednesday, March 21, 2018

Why Fruit Flies Are the New Lab Rats | Essay | Zócalo Public Square

Why Fruit Flies Are the New Lab Rats | Essay | Zócalo Public Square: Set out a bowl of fruit, and they will arrive: small, buff-colored flies with garnet eyes and an attraction to fermenting bananas. Annoying but not harmful ...

Friday, March 16, 2018

Fly models of kidney disease: Drosophila nephrocytes "represent a novel and easy-to-use alternative in experimental nephrology"

Helmstädter M, Simons M. Using Drosophila nephrocytes in genetic kidney disease. Cell Tissue Res. 2017 Jul;369(1):119-126. PMID: 28401308.

The abstract: "Renal diseases are a growing health burden, and innovative models to study their pathomechanisms are greatly needed. Here, we highlight how the fruit fly Drosophila melanogaster can be used to model kidney diseases. We focus on the nephrocyte that has recently been shown to exhibit podocyte and proximal tubular cell features. These cells can be manipulated with precise genetic tools to dissect filtration and reabsorption mechanisms. Thus, they represent a novel and easy-to-use alternative in experimental nephrology."

Wednesday, February 28, 2018

Fly studies contribute to identification pathogenic variant in individuals with lethargy, acidosis, aciduria, hyperammonemia

Oláhová M, Yoon WH, Thompson K, Jangam S, Fernandez L, Davidson JM, Kyle JE, Grove ME, Fisk DG, Kohler JN, Holmes M, Dries AM, Huang Y, Zhao C, Contrepois K, Zappala Z, Frésard L, Waggott D, Zink EM, Kim YM, Heyman HM, Stratton KG, Webb-Robertson BM; Undiagnosed Diseases Network, Snyder M, Merker JD, Montgomery SB, Fisher PG, Feichtinger RG, Mayr JA, Hall J, Barbosa IA, Simpson MA, Deshpande C, Waters KM, Koeller DM, Metz TO, Morris AA, Schelley S, Cowan T, Friederich MW, McFarland R, Van Hove JLK, Enns GM, Yamamoto S, Ashley EA, Wangler MF, Taylor RW, Bellen HJ, Bernstein JA, Wheeler MT. Biallelic Mutations in ATP5F1D, which Encodes a Subunit of ATP Synthase, Cause a Metabolic Disorder. Am J Hum Genet. 2018 Feb 16. pii: S0002-9297(18)30042-9. PMID: 29478781.

From the abstract: "... Here, we describe two individuals, each with homozygous missense variants in ATP5F1D, who presented with episodic lethargy, metabolic acidosis, 3-methylglutaconic aciduria, and hyperammonemia. ... Knockdown of Drosophila ATPsynδ, the ATP5F1D homolog, in developing eyes and brains caused a near complete loss of the fly head, a phenotype that was fully rescued by wild-type human ATP5F1D. In contrast, expression of the ATP5F1D c.245C>T and c.317T>G variants rescued the head-size phenotype but recapitulated the eye and antennae defects seen in other genetic models of mitochondrial oxidative phosphorylation deficiency. Our data establish c.245C>T (p.Pro82Leu) and c.317T>G (p.Val106Gly) in ATP5F1D as pathogenic variants leading to a Mendelian mitochondrial disease featuring episodic metabolic decompensation."

Friday, February 16, 2018

Review discusses re-think of pathogenesis underlying Ehlers-Danlos syndrome based on results of fly study

Xiao G, Zhou B. ZIP13: A Study of Drosophila Offers an Alternative Explanation for the Corresponding Human Disease. Front Genet. 2018 Jan 31;8:234. PMID: 29445391; PubMed Central PMCID: PMC5797780.

The abstract: "The fruit fly Drosophila melanogaster has become an important model organism to investigate metal homeostasis and human diseases. Previously we identified dZIP13 (CG7816), a member of the ZIP transporter family (SLC39A) and presumably a zinc importer, is in fact physiologically primarily responsible to move iron from the cytosol into the secretory compartments in the fly. This review will discuss the implication of this finding for the etiology of Spondylocheirodysplasia-Ehlers-Danlos Syndrome (SCD-EDS), a human disease defective in ZIP13. We propose an entirely different model in that lack of iron in the secretory compartment may underlie SCD-EDS. Altogether three different working models are discussed, supported by relevant findings made in different studies, with uncertainties, and questions remained to be solved. We speculate that the distinct ZIP13 sequence features, different from those of all other ZIP family members, may confer it special transport properties."

Tuesday, February 6, 2018

Drosophila experiments help inform study of Menkes disease

Zlatic SA, Vrailas-Mortimer A, Gokhale A, Carey LJ, Scott E, Burch R, McCall MM, Rudin-Rush S, Davis JB, Hartwig C, Werner E, Li L, Petris M, Faundez V. Rare Disease Mechanisms Identified by Genealogical Proteomics of Copper Homeostasis Mutant Pedigrees. Cell Syst. 2018 Jan 30. pii: S2405-4712(18)30008-5. PMID: 29397366.

From the abstract: "Rare neurological diseases shed light onto universal neurobiological processes. However, molecular mechanisms connecting genetic defects to their disease phenotypes are elusive. Here, we obtain mechanistic information by comparing proteomes of cells from individuals with rare disorders with proteomes from their disease-free consanguineous relatives. ... We found connections between copper dyshomeostasis and the UCHL1/PARK5 pathway of Parkinson disease, which we validated with mitochondrial respiration and Drosophila genetics assays. We propose that our genealogical "omics" strategy can be broadly applied to identify mechanisms linking a genomic locus to its phenotypes."

Saturday, January 27, 2018

Preprint describes contribution of Drosophila double-knockdown assay to understanding 16p11.2 deletion syndrome

Pervasive epistasis in cell proliferation pathways modulates neurodevelopmental defects of autism-associated 16p11.2 deletion

Janani Iyer, Mayanglambam Dhruba Singh, Matthew Jensen, Payal Patel, Lucilla Pizzo, Emily Huber, Haley Koerselman, Alexis T. Weiner, Paola Lepanto, Komal Vadodaria, Alexis Kubina, Qingyu Wang, Abigail Talbert, Sneha Yennawar, Jose Badano, J. Robert Manak, Melissa M. Rolls, Arjun Krishnan, Santhosh Girirajan

From the abstract: "We used RNA interference in Drosophila melanogaster to evaluate the phenotype, function, and interactions of conserved 16p11.2 homologs ... Leveraging the Drosophila eye for studying gene interactions, we performed 561 pairwise knockdowns of gene expression, and identified 24 interactions between 16p11.2 homologs ... and 62 interactions with other neurodevelopmental genes ... Overall, these results point towards a new model for pathogenicity of rare CNVs, where CNV genes interact with each other in conserved pathways to modulate expression of the neurodevelopmental phenotype."

Tuesday, January 23, 2018

Methods report--using the fly eye to study Tau toxicity

Dourlen P. Identification of Tau Toxicity Modifiers in the Drosophila Eye. Methods Mol Biol. 2017;1523:375-389 PMID: 27975266.

The abstract: "Drosophila is a powerful model to study human diseases thanks to its genetic tools and ease of screening. Human genes can be expressed in targeted organs and their toxicity assessed on easily scorable external phenotypes that can be used as readout to perform genetic screen of toxicity modifiers. In this chapter, I describe how to express human Tau protein in the Drosophila eye, assess protein expression by western blot, assess Tau toxicity by quantifying the size of the Tau-induced rough eye, and perform a genetic screen of modifiers of Tau toxicity in the Drosophila eye."

Drosophila contributes to platform for identification of "tumor calibrated inhibitors"

Sonoshita M, Scopton AP, Ung PMU, Murray MA, Silber L, Maldonado AY, Real A, Schlessinger A, Cagan RL, Dar AC. A whole-animal platform to advance a clinical kinase inhibitor into new disease space. Nat Chem Biol. 2018 Jan 22. PMID: 29355849.

From the abstract: "Synthetic tailoring of approved drugs for new indications is often difficult ... Here, we report a multidisciplinary approach for accessing novel target and chemical space starting from an FDA-approved kinase inhibitor. By combining chemical and genetic modifier screening with computational modeling, we identify distinct kinases that strongly enhance ('pro-targets') or limit ('anti-targets') whole-animal activity of the clinical kinase inhibitor sorafenib in a Drosophila medullary thyroid carcinoma (MTC) model. ... Through progressive synthetic refinement, we report a new class of 'tumor calibrated inhibitors' with unique polypharmacology and strongly improved therapeutic index in fly and human MTC xenograft models. This platform provides a rational approach to creating new high-efficacy and low-toxicity drugs."

Wednesday, January 3, 2018

Drosophila model points to involvement of potassium channel in aging hearts

Klassen MP, Peters CJ, Zhou S, Williams HH, Jan LY, Jan YN. Age-dependent diastolic heart failure in an in vivo Drosophila model. Elife. 2017 Mar 22;6. pii: e20851. PMID: 28328397; PMCID: PMC5362267.

The abstract: "While the signals and complexes that coordinate the heartbeat are well established, how the heart maintains its electromechanical rhythm over a lifetime remains an open question with significant implications to human health. Reasoning that this homeostatic challenge confronts all pulsatile organs, we developed a high resolution imaging and analysis toolset for measuring cardiac function in intact, unanesthetized Drosophila melanogaster. We demonstrate that, as in humans, normal aging primarily manifests as defects in relaxation (diastole) while preserving contractile performance. Using this approach, we discovered that a pair of two-pore potassium channel (K2P) subunits, largely dispensable early in life, are necessary for terminating contraction (systole) in aged animals, where their loss culminates in fibrillatory cardiac arrest. As the pumping function of its heart is acutely dispensable for survival, Drosophila represents a uniquely accessible model for understanding the signaling networks maintaining cardiac performance during normal aging."

Drosophila gut as model for uncovering mechanisms of antimicrobial activity

Liu X, Hodgson JJ, Buchon N. Drosophila as a model for homeostatic,antibacterial, and antiviral mechanisms in the gut. PLoS Pathog. 2017 May 4;13(5):e1006277. PMID: 28472194; PMCID: PMC5417715.

This review article includes an illustrated comparison of fly and mammalian guts and their interactions with microbes such as bacteria and viruses.

Tuesday, January 2, 2018

Protocol for testing of candidate heart-disease genes in Drosophila

Zhu JY, Fu Y, Richman A, Han Z. Validating Candidate Congenital Heart Disease Genes in Drosophila. Bio Protoc. 2017 Jun 20;7(12). pii: e2350. PMID: 29276722; PMCID: PMC5739056.

From the abstract: "... A high throughput in vivo model system to validate candidate gene association with pathology is ... useful. We present such a system employing Drosophila to validate candidate congenital heart disease (CHD) genes. The protocols exploit comprehensive libraries of UAS-GeneX-RNAi fly strains ... These protocols were recently used to evaluate more than 100 candidate CHD genes implicated by patient whole-exome sequencing (Zhu et al., 2017)."

Protocol for infection of Drosophila with a parasite for research studies related to leishmaniasis

Okuda K, Silverman N. Drosophila Model of Leishmania amazonensis Infection. Bio Protoc. 2017 Dec 5;7(23). pii: e2640. PMID: 29276726; PMCID: PMC5738924.

The abstract: "This protocol describes how to generate and harvest antibody-free L. amazonensis amastigotes, and how to infect adult Drosophila melanogaster with these parasites. This model recapitulates key aspects of the interactions between Leishmania amastigotes and animal phagocytes."