Reports related to neurodegenerative diseases use Drosophila as a test system

Aging Cell. 2021 Apr 28:e13365. doi: 10.1111/acel.13365. Online ahead of print.

Vesicular glutamate transporter modulates sex differences in dopamine neuron
vulnerability to age-related neurodegeneration.

Buck SA, Steinkellner T, Aslanoglou D, Villeneuve M, Bhatte SH, Childers VC), Rubin SA, De Miranda BR, O'Leary EI, Neureiter EG, Fogle KJ, Palladino MJ, Logan RW, Glausier JR, Fish KN, Lewis DA(2), Greenamyre JT, McCabe BD, Cheetham CEJ, Hnasko TS, Freyberg Z

Age is the greatest risk factor for Parkinson's disease (PD) which causes progressive loss of dopamine (DA) neurons, with males at greater risk than females. Intriguingly, some DA neurons are more resilient to degeneration than others. Increasing evidence suggests that vesicular glutamate transporter (VGLUT) expression in DA neurons plays a role in this selective vulnerability. We investigated the role of DA neuron VGLUT in sex- and age-related differences in DA neuron vulnerability using the genetically tractable Drosophila model. We found sex differences in age-related DA neurodegeneration and its associated locomotor behavior, where males exhibit significantly greater decreases in both DA neuron number and locomotion during aging compared with females. We discovered that dynamic changes in DA neuron VGLUT expression mediate these age- and sex-related differences, as a potential compensatory mechanism for diminished DA neurotransmission during aging. Importantly, female Drosophila possess higher levels of VGLUT expression in DA neurons compared with males, and this finding is conserved across flies, rodents, and humans. Moreover, we showed that diminishing VGLUT expression in DA neurons eliminates females' greater resilience to DA neuron loss across aging. This offers a new mechanism for sex differences in selective DA neuron vulnerability to age-related DA neurodegeneration. Finally, in mice, we showed that the ability of DA neurons to achieve optimal control over VGLUT expression is essential for DA neuron survival. These findings lay the groundwork for the manipulation of DA neuron VGLUT expression as a novel therapeutic strategy to boost DA neuron resilience to age- and PD-related neurodegeneration.

DOI: 10.1111/acel.13365
PMID: 33909313

 

Cell Death Dis. 2020 Sep 10;11(9):739. doi: 10.1038/s41419-020-02942-8.

Enhanced accumulation of reduced glutathione by Scopoletin improves
survivability of dopaminergic neurons in Parkinson's model.

Pradhan P, Majhi O, Biswas A, Joshi VK, Sinha D

Parkinson's disease (PD) is a neuromotor disorder, primarily manifested by motor anomalies due to progressive loss of dopaminergic neurons. Although alterations in genetic factors have been linked with its etiology, exponential accumulation of environmental entities such as reactive oxygen species (ROS) initiate a cyclic chain reaction resulting in accumulation of cellular inclusions, dysfunctional mitochondria, and overwhelming of antioxidant machinery, thus accelerating disease pathogenesis. Involvement of oxidative stress in PD is further substantiated through ROS induced Parkinsonian models and elevated oxidative markers in clinical PD samples; thereby, making modulation of neuronal oxidative load as one of the major approaches in management of PD. Here we have found a potent antioxidant moiety Scopoletin (Sp), a common derivative in most of the nootropic herbs, with robust neuroprotective ability. Sp increased cellular resistance to ROS through efficient recycling of GSH to prevent oxidative damage. The Sp treated cells showed higher loads of reduced glutathione making them resistant to perturbation of antioxidant machinery or neurotoxin MPP+. Sp could restore the redox balance, mitochondrial function, and prevented oxidative damage, leading to recovery of dopaminergic neural networks and motion abilities in Drosophila genetic model of PD. Our data also suggest that Sp, in combination increases the therapeutic potency of L-DOPA by mitigating its chronic toxicity. Together, we highlight the possible ability of Sp in preventing oxidative stress mediated loss of dopaminergic neurons and at the same time enhance the efficacy of dopamine recharging regimens.

DOI: 10.1038/s41419-020-02942-8
PMCID: PMC7484898
PMID: 32913179

Drosophila used in study associating variants in UNC13B with epilepsy and/or febrile seizures

Brain. 2021 Apr 20:awab164. doi: 10.1093/brain/awab164. Online ahead of print.

UNC13B variants associated with partial epilepsy with favourable outcome.

Wang J(, Qiao JD, Liu XR, Liu DT, Chen YH, Wu Y, Sun Y, Yu J, Ren RN, Mei Z, Liu YX, Shi YW, Jiang M, Lin SM, He N, Li B, Bian WJ, Li BM(, Yi YH, Su T, Liu HK, Gu WY, Liao WP; China Epilepsy Gene 1.0 Project.

From the abstract:

"The unc-13 homolog B (UNC13B) gene encodes a presynaptic protein ... In this study we screened for novel genetic variants in a cohort of 446 unrelated cases (families) with partial epilepsy ... UNC13B variants were identified in 12 individuals affected by partial epilepsy and/or febrile seizures from eight unrelated families. ... The identified UNC13B variants included one nonsense variant, two variants at or around a splice site, one compound heterozygous missense variant, and four missense variants that cosegregated in the families. The frequency of UNC13B variants identified in the present study was significantly higher than that in a control cohort of Han Chinese and controls of the East Asian and all populations in the Genome Aggregation Database. Computational modeling, including hydrogen bond and docking analyses, suggested that the variants lead to functional impairment. In Drosophila, seizure rate and duration were increased by Unc13b knockdown compared to wild-type flies, but these effects were less pronounced than in sodium voltage-gated channel alpha subunit 1 (Scn1a) knockdown Drosophila. Electrophysiologic recordings showed that excitatory neurons in Unc13b-deficient flies exhibited increased excitability. These results suggest that UNC13B is potentially associated with epilepsy. ..."

DOI: 10.1093/brain/awab164
PMID: 33876820

Cross-species analysis related to Huntington's disease (fly, mouse, human)

Elife. 2021 Apr 19;10:e64564. doi: 10.7554/eLife.64564. Online ahead of print.

Downregulation of glial genes involved in synaptic function mitigates Huntington's Disease pathogenesis.

Onur TS, Laitman A, Zhao H, Keyho R, Kim H, Wang J, Mair M, Wang H, Li L, Perez A, de Haro M, Wan YW, Allen G, Lu B, Al-Ramahi I, Liu Z, Botas J

Abstract:

Most research on neurodegenerative diseases has focused on neurons, yet glia help form and maintain the synapses whose loss is so prominent in these conditions. To investigate the contributions of glia to Huntington's disease (HD), we profiled the gene expression alterations of Drosophila expressing human mutant Huntingtin (mHTT) in either glia or neurons and compared these changes to what is observed in HD human and HD mice striata. A large portion of conserved genes are concordantly dysregulated across the three species; we tested these genes in a high-throughput behavioral assay and found that downregulation of genes involved in synapse assembly mitigated pathogenesis and behavioral deficits. To our surprise, reducing dNRXN3 function in glia was sufficient to improve the phenotype of flies expressing mHTT in neurons, suggesting that mHTT's toxic effects in glia ramify throughout the brain. This supports a model in which dampening synaptic function is protective because it attenuates the  excitotoxicity that characterizes HD.

DOI: 10.7554/eLife.64564
PMID: 33871358

Comparison in Drosophila of 13 different human RASopathy isoforms points to differences in pathways affected and therapeutic responses

iScience. 2021 Mar 13;24(4):102306. doi: 10.1016/j.isci.2021.102306.

Drosophila RASopathy models identify disease subtype differences and biomarkers of drug efficacy.

Das TK, Gatto J, Mirmira R, Hourizadeh E, Kaufman D, Gelb BD, Cagan R

Abstract:

RASopathies represent a family of mostly autosomal dominant diseases that are caused by missense variants in the rat sarcoma viral oncogene/mitogen activated protein kinase (RAS/MAPK) pathway including KRAS, NRAS, BRAF, RAF1, and SHP2. These variants are associated with overlapping but distinct phenotypes that affect the heart, craniofacial, skeletal, lymphatic, and nervous systems. Here, we report an analysis of 13 Drosophila transgenic lines, each expressing a different human RASopathy isoform. Similar to their human counterparts, each Drosophila line displayed common aspects but also important differences including distinct signaling pathways such as the Hippo and SAPK/JNK signaling networks. We identified multiple classes of clinically relevant drugs-including statins and histone deacetylase inhibitors-that improved viability across most RASopathy lines; in contrast, several canonical RAS pathway inhibitors proved less broadly effective. Overall, our study compares and contrasts a large number of RASopathy-associated variants including their therapeutic responses.

DOI: 10.1016/j.isci.2021.102306
PMCID: PMC8026909
PMID: 33855281

Conflict of interest statement: B.G. declares royalties from GeneDx, Correlegan, LabCorp, and Prevention Genetics. B.G. is a named inventor on issued patents related to PTPN11, SHOC2, RAF1, and SOS1 mutations in Noonan syndrome. The Icahn School of Medicine at Mount Sinai licensed the patent to several diagnostics companies and has received royalty payments, some of which are distributed to B.G. B.G. and R.C. are principal investigators for a sponsored research agreement from Onconova.

Study looks at molecular mechsnisms underlying circadian rhythm disruption in fly model of Fragile X syndrome

Neurosci Bull. 2021 Apr 15. doi: 10.1007/s12264-021-00682-z.

Dysregulated CRMP Mediates Circadian Deficits in a Drosophila Model of Fragile X Syndrome.

Zhao J, Xue J, Zhu T, He H, Kang H, Jiang X, Huang W, Duan R

Abstract:

Fragile X syndrome (FXS) is the leading inherited cause of intellectual disability, resulting from the lack of functional fragile X mental retardation protein (FMRP), an mRNA binding protein mainly serving as a translational regulator. Loss of FMRP leads to dysregulation of target mRNAs. The Drosophila model of FXS show an abnormal circadian rhythm with disruption of the output pathway downstream of the clock network. Yet the FMRP targets involved in circadian regulation have not been identified. Here, we identified collapsing response mediator protein (CRMP) mRNA as a target of FMRP. Knockdown of pan-neuronal CRMP expression ameliorated the circadian defects and abnormal axonal structures of clock neurons (ventral lateral neurons) in dfmr1 mutant flies. Furthermore, specific reduction of CRMP in the downstream output insulin-producing cells attenuated the aberrant circadian behaviors. Molecular analyses revealed that FMRP binds with CRMP mRNA and negatively regulates its translation. Our results indicate that CRMP is an FMRP target and establish an essential role for CRMP in the circadian output in FXS Drosophila.

DOI: 10.1007/s12264-021-00682-z
PMID: 33856646

Light-activated receptors tested in Drosophila model of Parkinson's disease

PLoS Genet. 2021 Apr 15;17(4):e1009479. doi: 10.1371/journal.pgen.1009479.

Optogenetic delivery of trophic signals in a genetic model of Parkinson's disease.

Ingles-Prieto A, Furthmann N, Crossman SH Tichy AM, Hoyer N, Petersen M, Zheden V, Biebl J, Reichhart E, Gyoergy A, Siekhaus DE, Soba P, Winklhofer KF, Janovjak H

Abstract:

Optogenetics has been harnessed to shed new mechanistic light on current and future therapeutic strategies. This has been to date achieved by the regulation of ion flow and electrical signals in neuronal cells and neural circuits that are known to be affected by disease. In contrast, the optogenetic delivery of trophic biochemical signals, which support cell survival and are implicated in degenerative disorders, has never been demonstrated in an animal model of disease. Here, we reengineered the human and Drosophila melanogaster REarranged during Transfection (hRET and dRET) receptors to be activated by light, creating one-component optogenetic tools termed Opto-hRET and Opto-dRET. Upon blue light stimulation, these receptors robustly induced the MAPK/ERK proliferative signaling pathway in cultured cells. In PINK1B9 flies that exhibit loss of PTEN-induced putative kinase 1 (PINK1), a kinase associated with familial Parkinson's disease (PD), light activation of Opto-dRET suppressed mitochondrial defects, tissue degeneration and behavioral deficits. In human cells with PINK1 loss-of-function, mitochondrial fragmentation was rescued using Opto-dRET via the PI3K/NF-кB pathway. Our results demonstrate that a light-activated receptor can ameliorate disease hallmarks in a genetic model of PD. The optogenetic delivery of trophic signals is cell type-specific and reversible and thus has the potential to inspire novel strategies towards a spatio-temporal regulation of tissue repair.

DOI: 10.1371/journal.pgen.1009479
PMID: 33857132

Fly model related to FIG-4 associated neurological disorders uncovers potential link to epigenetic regulation

Neuroreport. 2021 May 5;32(7):562-568. doi: 10.1097/WNR.0000000000001636.

Identification of Rpd3 as a novel epigenetic regulator of Drosophila FIG 4, a
Charcot-Marie-Tooth disease-causing gene.

Muraoka Y, Nikaido A, Kowada R, Kimura H, Yamaguchi M, Yoshida H

Abstract:

Mutations in the factor-induced-gene 4 (FIG 4) gene are associated with multiple disorders, including Charcot-Marie-Tooth disease (CMT), epilepsy with polymicrogyria, Yunis-Varón syndrome and amyotrophic lateral sclerosis. The wide spectrum of disorders associated with FIG 4 may be related to the dysregulated epigenetics. Using Gene Expression Omnibus, we found that HDAC1 binds to the FIG 4 gene locus in the genome of human CD4+ T cells. Rpd3 is a well-known Drosophila homolog of human HDAC1. We previously established Drosophila models targeting Drosophila FIG 4 (dFIG 4) that exhibited defective locomotive ability, abnormal synapse morphology at neuromuscular junctions, enlarged vacuoles in the fat body and aberrant compound eye morphology. Genetic crossing experiments followed by physiological and immunocytochemical analyses revealed that Rpd3 mutations suppressed these defects induced by dFIG 4 knockdown. This demonstrated Rpd3 to be an important epigenetic regulator of dFIG 4, suggesting that the inhibition of HDAC1 represses the pathogenesis of FIG 4-associated disorders, including CMT. Defects in epigenetic regulators, such as HDAC1, may also explain the diverse symptoms of FIG 4-associated disorders.

Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.

DOI: 10.1097/WNR.0000000000001636
PMID: 33850086