Drosophila studies contribute to a study associating variants of PP2A/PPP2R4 with juvenile-onset parkinsonism

Brain. 2022 Sep 8:awac326. doi: 10.1093/brain/awac326 

PTPA variants and impaired PP2A activity in early-onset parkinsonism with
intellectual disability

Fevga C, Tesson C, Mascaro AC, Courtin T, van Coller R, Sakka S, Ferraro F, Farhat N, Bardien S, Damak M, Carr J, Ferrien M, Boumeester V, Hundscheid J, Grillenzoni N, Kessissoglou IA, Kuipers DJS, Quadri M; French and Mediterranean Parkinson disease Genetics Study Group; International Parkinsonism Genetics Network, Corvol JC, Mhiri C, Hassan BA, Breedveld GJ, Lesage S, Mandemakers W, Brice A, Bonifati V

Abstract:

The protein phosphatase 2A complex (PP2A), the major Ser/Thr phosphatase in the brain, is involved in a number of signaling pathways and functions, including the regulation of crucial proteins for neurodegeneration, such as alpha-synuclein, tau, and LRRK2. Here, we report the identification of variants in the PTPA/PPP2R4 gene, encoding a major PP2A activator, in two families with early-onset parkinsonism and intellectual disability. We carried out clinical studies and genetic analyses, including genome-wide linkage analysis, whole-exome sequencing, and Sanger sequencing of candidate variants. We next performed functional studies on the disease-associated variants in cultured cells and knock-down of ptpa in Drosophila melanogaster. We first identified a homozygous PTPA variant, c.893T > G (p.Met298Arg), in patients from a South African family with early-onset parkinsonism and intellectual disability. Screening of a large series of additional families yielded a second homozygous variant, c.512C > A (p.Ala171Asp), in a Libyan family with a similar phenotype. Both variants co-segregate with disease in the respective families. The affected subjects display juvenile-onset parkinsonism and intellectual disability. The motor symptoms were responsive to treatment with levodopa and deep brain stimulation of the subthalamic nucleus. In overexpression studies, both the PTPA p.Ala171Asp and p.Met298Arg variants were associated with decreased PTPA RNA stability and decreased PTPA protein levels; the p.Ala171Asp variant additionally displayed decreased PTPA protein stability. Crucially, expression of both variants was associated with decreased PP2A complex levels and impaired PP2A phosphatase activation. PTPA ortholog knock-down in Drosophila neurons induced a significant impairment of locomotion in the climbing test. This defect was age-dependent and fully reversed by L-DOPA treatment. We conclude that bi-allelic missense PTPA variants associated with impaired activation of the PP2A phosphatase cause autosomal recessive early-onset parkinsonism with intellectual disability. Our findings might also provide new insights for understanding the role of the PP2A complex in the pathogenesis of more common forms of neurodegeneration.

DOI: 10.1093/brain/awac326
PMID: 36073231

Study exploring impact of phophorylation state of PINK1 includes rescue of PINK1 definiciency in Drosophila as investigative tool (relevance to Parkinsons Disease)

EMBO Rep. 2020 Aug 5;21(8):e48686. doi: 10.15252/embr.201948686. Epub 2020 Jun 2.

PINK1 phosphorylates Drp1(S616) to regulate mitophagy-independent mitochondrial dynamics.

Han H, Tan J, Wang R, Wan H, He Y, Yan X, Guo J, Gao Q, Li J, Shang S, Chen F, Tian R, Liu W,
Liao L, Tang B, Zhang Z

Abstract:

Impairment of PINK1/parkin-mediated mitophagy is currently proposed to be the molecular basis of mitochondrial abnormality in Parkinson's disease (PD). We here demonstrate that PINK1 directly phosphorylates Drp1 on S616. Drp1S616 phosphorylation is significantly reduced in cells and mouse tissues deficient for PINK1, but unaffected by parkin inactivation. PINK1-mediated mitochondrial fission is Drp1S616 phosphorylation dependent. Overexpression of either wild-type Drp1 or of the phosphomimetic mutant Drp1S616D, but not a dephosphorylation-mimic mutant Drp1S616A, rescues PINK1 deficiency-associated phenotypes in Drosophila. Moreover, Drp1 restores PINK1-dependent mitochondrial fission in ATG5-null cells and ATG7-null Drosophila. Reduced Drp1S616 phosphorylation is detected in fibroblasts derived from 4 PD patients harboring PINK1 mutations and in 4 out of 7 sporadic PD cases. Taken together, we have identified Drp1 as a substrate of PINK1 and a novel mechanism how PINK1 regulates mitochondrial fission independent of parkin and autophagy. Our results further link impaired PINK1-mediated Drp1S616 phosphorylation with the pathogenesis of both familial and sporadic PD.

DOI: 10.15252/embr.201948686
PMCID: PMC7403662
PMID: 32484300

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

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 leads to new model for cellular mechanisms underlying diseases associated with disruption of Valosin-Containing Proteins

Nat Commun. 2021 Jan 21;12(1):513. doi: 10.1038/s41467-020-20796-8.

SVIP is a molecular determinant of lysosomal dynamic stability, neurodegeneration and lifespan.

Johnson AE, Orr BO, Fetter RD, Moughamian AJ, Primeaux LA,
Geier EG, Yokoyama JS, Miller BL, Davis GW
 

From the abstract:

Missense mutations in Valosin-Containing Protein (VCP) are linked to diverse degenerative diseases including IBMPFD, amyotrophic lateral sclerosis (ALS), muscular dystrophy and Parkinson's disease. Here, we characterize a VCP-binding co-factor (SVIP) that specifically recruits VCP to lysosomes. ... We also establish multiple links between SVIP and VCP-dependent disease in our Drosophila model system. ... Finally, we identify a human SVIP mutation and confirm the pathogenicity of this mutation in our Drosophila model. We propose a model for VCP disease based on the differential, co-factor-dependent recruitment of VCP to intracellular organelles.

DOI: 10.1038/s41467-020-20796-8
PMID: 33479240

Wondering what's IBMPFD? Answer: Inclusion body myopathy with early-onset Paget disease and frontotemporal dementia.

Results using a fly model of Parkinsons Disease suggests Skp1 is a potential therapeutic target for neurodegenerative diseases

iScience. 2020 Jul 16;23(8):101375. doi: 10.1016/j.isci.2020.101375. Online
ahead of print.

Drosophila Skp1 Homologue SkpA Plays a Neuroprotective Role in Adult Brain.

Dabool L, Hakim-Mishnaevski K, Juravlev L, Flint-Brodsly N, Mandel

S, Kurant E.

Abstract:

Skp1, a component of the ubiquitin E3 ligases, was found to be decreased in the brains of sporadic Parkinson's disease (PD) patients, and its overexpression prevented death of murine neurons in culture. Here we expose the neuroprotective role of the Drosophila skp1 homolog, skpA, in the adult brain. Neuronal knockdown of skpA leads to accumulation of ubiquitinated protein aggregates and loss of dopaminergic neurons accompanied by motor dysfunction and reduced lifespan. Conversely, neuronal overexpression of skpA reduces aggregate load, improves age-related motor decline, and prolongs lifespan. Moreover, SkpA rescues neurodegeneration in a Drosophila model of PD. We also show that a Drosophila homolog of FBXO7, the F Box protein, Nutcracker (Ntc), works in the same pathway with SkpA. However, skpA overexpression rescues ntc knockdown phenotype, suggesting that SkpA interacts with additional F box proteins in the adult brain neurons. Collectively, our study discloses Skp1/SkpA as a potential therapeutic target in neurodegenerative diseases.

DOI: 10.1016/j.isci.2020.101375
PMID: 32739834

Studies in Drosophila point to potential therapeutic approach for treatment of Parkinson's Disease based on modulation of kynurenine metabolism

Cunningham PC, Waldeck K, Ganetzky B, Babcock DT. Neurodegeneration and locomotor dysfunction in Drosophila scarlet mutants. J Cell Sci. 2018 Sep 17;131(18). pii: jcs216697. doi: 10.1242/jcs.216697. PubMed PMID: 30154211; PubMed Central PMCID: PMC6176922.

From the abstract: "Parkinson's disease (PD) is characterized by the loss of dopaminergic neurons, resulting in progressive locomotor dysfunction. Identification of genes required for the maintenance of these neurons should help to identify potential therapeutic targets. ... Here, we show that Drosophila melanogaster scarlet mutants exhibit an age-dependent progressive loss of dopaminergic neurons, along with subsequent locomotor defects and a shortened lifespan. ... we show that expression of wild-type Scarlet is neuroprotective in a model of PD, suggesting that manipulating kynurenine metabolism may be a potential therapeutic option in treating PD."

Flies used to test drug activity predicted using dynamic combinatorial chemistry approach

Canal-Martín A, Sastre J, Sánchez-Barrena MJ, Canales A, Baldominos S, Pascual N, Martínez-González L, Molero D, Fernández-Valle ME, Sáez E, Blanco-Gabella P, Gómez-Rubio E, Martín-Santamaría S, Sáiz A, Mansilla A, Cañada FJ, Jiménez-Barbero J, Martínez A, Pérez-Fernández R. Insights into real-time chemical processes in a calcium sensor protein-directed dynamic library. Nat Commun. 2019 Jun 26;10(1):2798. PMID: 31243268; PMCID: PMC6595003.

Abstract: "Dynamic combinatorial chemistry (DCC) has proven its potential in drug discovery speeding the identification of modulators of biological targets. However, the exchange chemistries typically take place under specific reaction conditions, with limited tools capable of operating under physiological parameters. Here we report a catalyzed protein-directed DCC working at low temperatures that allows the calcium sensor NCS-1 to find the best ligands in situ. Ultrafast NMR identifies the reaction intermediates of the acylhydrazone exchange, tracing the molecular assemblies and getting a real-time insight into the essence of DCC processes at physiological pH. Additionally, NMR, X-ray crystallography and computational methods are employed to elucidate structural and mechanistic aspects of the molecular recognition event. The DCC approach leads us to the identification of a compound stabilizing the NCS-1/Ric8a complex and whose therapeutic potential is proven in a Drosophila model of disease with synaptic alterations."

Automated tracking of leg movement in free-moving flies contributes to characterization of fly models of neurodegenerative diseases

Wu S, Tan KJ, Govindarajan LN, Stewart JC, Gu L, Ho JWH, Katarya M, Wong BH, Tan EK, Li D, Claridge-Chang A, Libedinsky C, Cheng L, Aw SS. Fully automated leg tracking of Drosophila neurodegeneration models reveals distinct conserved movement signatures. PLoS Biol. 2019 Jun 27;17(6):e3000346. PubMed PMID: 31246996.

Abstract: "Some neurodegenerative diseases, like Parkinsons Disease (PD) and Spinocerebellar ataxia 3 (SCA3), are associated with distinct, altered gait and tremor movements that are reflective of the underlying disease etiology. Drosophila melanogaster models of neurodegeneration have illuminated our understanding of the molecular mechanisms of disease. However, it is unknown whether specific gait and tremor dysfunctions also occur in fly disease mutants. To answer this question, we developed a machine-learning image-analysis program, Feature Learning-based LImb segmentation and Tracking (FLLIT), that automatically tracks leg claw positions of freely moving flies recorded on high-speed video, producing a series of gait measurements. Notably, unlike other machine-learning methods, FLLIT generates its own training sets and does not require user-annotated images for learning. Using FLLIT, we carried out high-throughput and high-resolution analysis of gait and tremor features in Drosophila neurodegeneration mutants for the first time. We found that fly models of PD and SCA3 exhibited markedly different walking gait and tremor signatures, which recapitulated characteristics of the respective human diseases. Selective expression of mutant SCA3 in dopaminergic neurons led to a gait signature that more closely resembled those of PD flies. This suggests that the behavioral phenotype depends on the neurons affected rather than the specific nature of the mutation. Different mutations produced tremors in distinct leg pairs, indicating that different motor circuits were affected. Using this approach, fly models can be used to dissect the neurogenetic mechanisms that underlie movement disorders."

Parkinson's disease-related study in human cultured cells and Drosophila

Saridaki T, Nippold M, Dinter E, Roos A, Diederichs L, Fensky L, Schulz JB, Falkenburger BH. FYCO1 mediates clearance of α-synuclein aggregates through a Rab7-dependent mechanism. J Neurochem. 2018 Aug;146(4):474-492. PubMed PMID: 29747217.

From the abstract: "Parkinson's disease can be caused by mutations in the α-synuclein gene and is characterized by aggregates of α-synuclein protein. We have previously shown that over-expression of the small GTPase Rab7 can induce clearance of α-synuclein aggregates. In this study, we investigate which Rab7 effectors mediate this effect. To model Parkinson's disease, we expressed the pathogenic A53T mutant of α-synuclein in HEK293T cells and Drosophila melanogaster. ... Coexpression of FYCO1 in the fly model decreased α-synuclein aggregates as shown by the filter trap assay and rescued the locomotor deficit resulting from neuronal A53T-α-synuclein expression. ..."

Reports related to neurodegenerative and neuromuscular disorders

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 Aug 15;27(16):2863-2873.PMID: 29860311; PMCID: PMC6077814.

From the abstract: "... Loss-of-function of fly Pak3 or Pak1, whose mammalian homologs belong to Group I of PAK proteins, reduces ATXN1 levels, and accordingly, improves disease pathology in a Drosophila model of SCA1. Knockdown of PAK1 potently reduces ATXN1 levels in mammalian cells ... 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."

Adusumalli S, Ngian ZK, Lin WQ, Benoukraf T, Ong CT. Increased intron retention is a post-transcriptional signature associated with progressive aging and Alzheimer's disease. Aging Cell. 2019 Mar 13:e12928. PMID: 30868713.

From the abstract: "Intron retention (IR) by alternative splicing is a conserved regulatory mechanism that can affect gene expression and protein function during adult development and age-onset diseases. ... By profiling the transcriptome of Drosophila head cells at different ages, we observed a significant increase in IR events for many genes during aging. ... our results suggest that an increased IR is an conserved signature that is associated with aging. ... changes of IR pattern during aging may regulate the transition from healthy to pathological state in late-onset sporadic AD."

Wang TH, Wang SY, Wang XD, Jiang HQ, Yang YQ, Wang Y, Cheng JL, Zhang CT, Liang WW, Feng HL. Fisetin Exerts Antioxidant and Neuroprotective Effects in Multiple Mutant hSOD1 Models of Amyotrophic Lateral Sclerosis by Activating ERK. Neuroscience. 2018 May 21;379:152-166. PMID: 29559385.

From the abstract: "Oxidative stress exhibits a central role in the course of amyotrophic lateral sclerosis (ALS) ... Fisetin, a natural antioxidant, has shown benefits in varied neurodegenerative diseases. ... Three different hSOD1-related mutant models were used ... results indicate that fisetin protects cells from ROS damage and improves the pathological behaviors caused by oxidative stress in disease models related to SOD1 gene mutations ... providing a potential treatment for ALS."

Lakkappa N, Krishnamurthy PT, M D P, Hammock BD, Hwang SH. Soluble epoxide hydrolase inhibitor, APAU, protects dopaminergic neurons against rotenone induced neurotoxicity: Implications for Parkinson's disease. Neurotoxicology. 2019 Jan;70:135-145. PMID: 30472438.

From the abstract: "Epoxyeicosatrienoic acids (EETs), metabolites of arachidonic acid, play a crucial role in cytoprotection by attenuating oxidative stress, inflammation and apoptosis. EETs are rapidly metabolised in vivo by the soluble epoxide hydrolase (sEH). Increasing the half life of EETs by inhibiting the sEH enzyme is a novel strategy for neuroprotection. ... sEH inhibitors APAU was screened in silico and further evaluated for their antiparkinson activity against rotenone (ROT) induced neurodegeneration in N27 dopaminergic cell line and Drosophila melanogaster model of Parkinson disease (PD). ..."

 Krench M, Cho RW, Littleton JT. A Drosophila model of Huntington disease-like 2 exhibits nuclear toxicity and distinct pathogenic mechanisms from Huntington disease. Hum Mol Genet. 2016 Aug 1;25(15):3164-3177. PMID: 27288455; PMCID: PMC5179919.

From the abstract: "Huntington disease-like 2 (HDL2) and Huntington disease (HD) are adult-onset neurodegenerative diseases ... we generated and characterized a Drosophila HDL2 model and compared it with a previously established HD model. We find that neuronal expression of HDL2-Q15 is not toxic, while the expression of an expanded HDL2-Q138 protein is lethal. HDL2-Q138 forms large nuclear aggregates, with only smaller puncta observed in the cytoplasm. This is in contrast to what is observed in a Drosophila model of HD, where polyQ aggregates localize exclusively to the cytoplasm. ... We conclude that while HD and HDL2 have similar clinical profiles, distinct pathogenic mechanisms are likely to drive toxicity in Drosophila models of these disorders."

Poska H, Haslbeck M, Kurudenkandy FR, Hermansson E, Chen G, Kostallas G, Abelein A, Biverstål H, Crux S, Fisahn A, Presto J, Johansson J. Dementia-related Bri2 BRICHOS is a versatile molecular chaperone that efficiently inhibits Aβ42 toxicity in Drosophila. Biochem J. 2016 Oct 15;473(20):3683-3704. PMID: 27514716.

From the abstract: "Formation of fibrils of the amyloid-β peptide (Aβ) is suggested to play a central role in neurodegeneration in Alzheimer's disease (AD), for which no effective treatment exists. The BRICHOS domain is a part of several disease-related proproteins ... we find that transgenic expression of the Bri2 BRICHOS domain in the Drosophila central nervous system (CNS) or eyes efficiently inhibits Aβ42 toxicity. ... These findings suggest that Bri2 BRICHOS can be a physiologically relevant chaperone for Aβ in the CNS ..."

Exploration of sensitivity to iron in fly models related to Parkinson's disease

Zhu ZJ, Wu KC, Yung WH, Qian ZM, Ke Y. Differential interaction between iron and mutant alpha-synuclein causes distinctive Parkinsonian phenotypes in Drosophila. Biochim Biophys Acta. 2016 pr;1862(4):518-525. PMID: 26769358.

From the abstract: "Alpha-synuclein aggregation is the central hallmark of both sporadic and familial Parkinson's disease (PD). ... Iron accumulation is invariably found in PD. Recent studies showed that mutant and wild-type alpha-synuclein may have differential interaction with iron and mutant alpha-synuclein toxicity could be preferentially exacerbated by iron. We hence hypothesized that iron overload could selectively influence mutant alpha-synuclein toxicity and disease phenotypes. To test the hypothesis, we investigated if Drosophila melanogaster over-expressing A53T, A30P, and wild-type (WT) alpha-synuclein have different responses to iron treatment. We showed that iron treatment induced similar reduction of survival rate in all flies but induced a more severe motor decline in A53T and A30P mutant alpha-synuclein expressing flies, suggesting interaction between mutant alpha-synuclein and iron. Although no significant difference in total head iron content was found among these flies, we demonstrated that iron treatment induced selective DA neuron loss in motor-related PPM3 cluster only in the flies that express A53T and A30P mutant alpha-synuclein. We provided the first in vivo evidence that iron overload could induce distinctive neuropathology and disease phenotypes in mutant but not WT alpha-synuclein expressing flies ..."

Preprint: Fly model of neurodegeneration -- exploring LRRK2 and Rab's

New on the BioRxiv preprint server (not yet peer reviewed):

Neurodegeneration caused by LRRK2-G2019S requires Rab10 in select dopaminergic neurons

Stavroula Petridi, C. Adam Middleton, Alison Fellgett, Laura Covill, Amy Stewart, Jack Munns, Friederike Elisabeth Kohrs, P. Robin Hiesinger, Laurence Wilson, Sangeeta Chawla, Christopher J. H. Elliott

https://www.biorxiv.org/content/10.1101/586073v1

From the Significance Statement: "A key question in Parkinson’s is why dopamine neurons die particularly fast in some parts of the substantia nigra. We focused on the commonest Parkinson’s-related mutation, LRRK2-G2019S. ... Rab10 knock-out rescues G2019S-induced visual and movement degeneration, leaving sleep dysfunction unaffected. ... Rab3 is found in a different subset of dopaminergic neurons and shows no synergy with LRRK2-G2019S. We propose that variations in Rab expression contribute to differences in neurodegeneration ..."

Review of fly models of Parkinson's disease (now at PubMed Central)

Nagoshi E. Drosophila Models of Sporadic Parkinson's Disease. Int J Mol Sci. 2018 Oct 26;19(11). pii: E3343. doi: 10.3390/ijms19113343. PMID: 30373150; PMCID: PMC6275057.

From the abstract: "Parkinson's disease (PD) is the most common cause of movement disorders ... It is increasingly recognized as a complex group of disorders ... With the exception of the rare monogenic forms, the majority of PD cases result from an interaction between multiple genetic and environmental risk factors. The search for these risk factors and the development of preclinical animal models are in progress ... This review summarizes the studies that capitalize on modeling sporadic (i.e., nonfamilial) PD using Drosophila melanogaster and discusses their methodologies, new findings, and future perspectives."

Drosophila as "integral tool" for neurodegenerative disease research and personalized medicine -- review article now available in PubMed Central

Deal SL, Yamamoto S. Unraveling Novel Mechanisms of Neurodegeneration Through a Large-Scale Forward Genetic Screen in Drosophila. Front Genet. 2019 Jan 14;9:700. PMID: 30693015; PMCID: PMC6339878.

The abstract: "Neurodegeneration is characterized by progressive loss of neurons. Genetic and environmental factors both contribute to demise of neurons, leading to diverse devastating cognitive and motor disorders, including Alzheimer's and Parkinson's diseases in humans. Over the past few decades, the fruit fly, Drosophila melanogaster, has become an integral tool to understand the molecular, cellular and genetic mechanisms underlying neurodegeneration. Extensive tools and sophisticated technologies allow Drosophila geneticists to identify and study evolutionarily conserved genes that are essential for neural maintenance. In this review, we will focus on a large-scale mosaic forward genetic screen on the fly X-chromosome that led to the identification of a number of essential genes that exhibit neurodegenerative phenotypes when mutated. Most genes identified from this screen are evolutionarily conserved and many have been linked to human diseases with neurological presentations. Systematic electrophysiological and ultrastructural characterization of mutant tissue in the context of the Drosophila visual system, followed by a series of experiments to understand the mechanism of neurodegeneration in each mutant led to the discovery of novel molecular pathways that are required for neuronal integrity. Defects in mitochondrial function, lipid and iron metabolism, protein trafficking and autophagy are recurrent themes, suggesting that insults that eventually lead to neurodegeneration may converge on a set of evolutionarily conserved cellular processes. Insights from these studies have contributed to our understanding of known neurodegenerative diseases such as Leigh syndrome and Friedreich's ataxia and have also led to the identification of new human diseases. By discovering new genes required for neural maintenance in flies and working with clinicians to identify patients with deleterious variants in the orthologous human genes, Drosophila biologists can play an active role in personalized medicine."

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 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."

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."

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."