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."

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."

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."

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 ..."

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."

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."

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."

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."

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."