Biology subjects

Whitworth, A. J.

Publications and source records attributed to Whitworth, A. J..

17 recordsLinked to original sources

bioRxiv2026

Cross-platform multi-laboratory screening identifies HUWE1, USP33 and USP20 as negative-regulators of autophagy or mitophagy with relevance to neurodegeneration

Autophagy and mitophagy are essential cellular processes implicated in neurodegenerative diseases, yet few tractable targets have been robustly validated for therapeutic modulation of these pathways. In an industry-academia consortium we carried out an extensive literature review and expert curation, leading to selection of 29 genes previously reported to enhance autophagy upon genetic or pharmacological modulation. These genes were classified based on whether downregulation or overexpression induced autophagic activity. Using siRNA knockdown, small-molecule modulators, and transient transfection approaches, we systematically screened these targets in parallel across HeLa and HEK-293 cell lines using high- and low-content phenotypic imaging. Promising candidates were further evaluated in induced pluripotent stem cell (iPSC)-derived neurons and in Drosophila models. Three targets emerged as top candidates: HUWE1 downregulation consistently enhanced autophagy and aggregate clearance, while USP33 downregulation promoted mitophagy. We also identified USP20, a close homologue of USP33, as an inhibitor of mitophagy, a role not previously assigned to this protein. These effects on autophagy/mitophagy were corroborated in Drosophila, highlighting their potential functional relevance across species. This cross-platform, multi-laboratory study establishes a framework for identifying and validating regulators of autophagy and mitophagy and provides a route which enables a comprehensive reassessment of the current target literature in this field. The validation of HUWE1, USP20, and USP33 as candidate therapeutic targets offers new opportunities for intervention in neurodegenerative diseases.

neuroscience↗

bioRxiv2024

Clu1/Clu form mitochondria-associated granules upon metabolic transitions and regulate mitochondrial protein translation via ribosome interactions

Mitochondria perform essential metabolic functions and respond rapidly to changes in metabolic and stress conditions. As the majority of mitochondrial proteins are nuclear-encoded, intricate post-transcriptional regulation is crucial to enable mitochondria to adapt to changing cellular demands. The eukaryotic Clustered mitochondria protein family has emerged as an important regulator of mitochondrial function during metabolic shifts. Here, we show that the Drosophila melanogaster and Saccharomyces cerevisiae Clu/Clu1 proteins form dynamic, membraneless granules adjacent to mitochondria in response to metabolic changes. Yeast Clu1 regulates the translation of a subset of nuclear-encoded mitochondrial protein by interacting with their mRNAs while these are engaged in translation. We further show that Clu1 regulates translation by interacting with polysomes, independently of whether it is in a diffuse or granular state. Our results demonstrate remarkable functional conservation with other members of the Clustered mitochondria protein family and suggests that Clu/Clu1 granules isolate and concentrate ribosomes engaged in translating their mRNA targets, thus, integrating metabolic signals with the regulation of mitochondrial protein synthesis.

molecular biology↗

bioRxiv2024

Essential conserved neuronal motors kinesin-1 and kinesin-3 regulate Abeta42 toxicity in vivo

Alzheimers Disease is the leading cause of dementia and the most common neurodegenerative disorder. Understanding the molecular pathology of Alzheimers Disease may help identify new ways to reduce neuronal damage. In the past decades Drosophila has become a powerful tool in modelling mechanisms underlying human diseases. Here we investigate how the expression of the human 42-residue {beta}-amyloid (A{beta}) carrying the E22G pathogenic "Arctic" mutation (A{beta}42Arc) affects axonal health and behaviour of Drosophila. We find that A{beta}42Arc flies present aberrant neurons, with altered axonal transport of mitochondrial and an increased number of terminal boutons at neuromuscular junctions. We demonstrate that the major axonal motor proteins kinesin-1 and kinesin-3 are essential for the correct development of neurons in Drosophila larvae and similar findings are replicated in human iPSC-derived cortical neurons. We then show that the over-expression of kinesin-1 or kinesin-3 restores the correct number of terminal boutons in A{beta}42Arc expressing neurons and that this is associated with a rescue of the overall neuronal function, measured by negative geotaxis locomotor behavioural assay. We therefore provide new evidence in understanding the mechanisms of axonal transport defects in Alzheimers Disease, and our results indicate that kinesins should be considered as potential drug targets to help reduce dementia-associated disorders.

cell biology↗

bioRxiv2023

Activation of the Keap1/Nrf2 pathway suppresses mitochondrial dysfunction in C9orf72 ALS/FTD in vivo models and patient iNeurons

Mitochondrial dysfunction such as excess production of reactive oxygen species (ROS) and defective mitochondrial dynamics are common features of C9orf72 Amyotrophic Lateral Sclerosis/Frontotemporal Dementia (ALS/FTD), but it remains unclear whether these are causative or a consequence of the pathogenic process. To address this, we have performed a comprehensive characterisation of mitochondrial dysfunction in vivo model, analysing multiple transgenic Drosophila models of C9orf72-related pathology, which can be correlated to disease-relevant locomotor deficits. Genetic manipulations to reverse different aspects of mitochondrial disruption revealed that only genetic upregulation of antioxidants such as mitochondrial Sod2 and catalase were able to rescue C9orf72 locomotor deficits, suggesting a causative link between mitochondrial dysfunction, ROS and behavioural phenotypes. By analysing the Keap1/Nuclear factor erythroid 2-related factor 2 (Nrf2) pathway, a central antioxidant response pathway, we observed a blunted response in the C9orf72 models. However, both genetic reduction of Keap1 and its pharmacological targeting by dimethyl fumarate (DMF), was able to rescue C9orf72-related motor deficits. In addition, analysis of C9orf72 patient-derived iNeurons showed increased ROS that was suppressed by DMF treatment. These results indicate that mitochondrial oxidative stress is an upstream pathogenic mechanism leading to downstream mitochondrial dysfunction such as alterations in mitochondrial function and turnover. Consequently, our data support targeting the Keap1/Nrf2 signalling pathway as a viable therapeutic strategy for C9orf72-related ALS/FTD.

neuroscience↗

bioRxiv2023

Mitochondrial CISD1/Cisd accumulation blocks mitophagy and genetic or pharmacological inhibition rescues neurodegenerative phenotypes in Pink1/parkin models

BackgroundMitochondrial dysfunction and toxic protein aggregates have been shown to be key features in the pathogenesis of neurodegenerative diseases, such as Parkinsons disease (PD). Functional analysis of genes linked to PD have revealed that the E3 ligase Parkin and the mitochondrial kinase PINK1 are important factors for mitochondrial quality control. PINK1 phosphorylates and activates Parkin, which in turn ubiquitinates mitochondrial proteins priming them and the mitochondrion itself for degradation. However, it is unclear whether dysregulated mitochondrial degradation or the toxic build-up of certain Parkin ubiquitin substrates is the driving pathophysiological mechanism leading to PD. The iron-sulphur cluster containing proteins CISD1 and CISD2 have been identified as major targets of Parkin in various proteomic studies. MethodsWe employed in vivo Drosophila and human cell culture models to study the role of CISD proteins in cell and tissue viability as well as aged-related neurodegeneration, specifically analysing aspects of mitophagy and autophagy using orthogonal assays. ResultsWe discovered that the Drosophila homolog Cisd accumulates during aging, as well as in Pink1 and parkin mutant flies. We observed that build-up of Cisd is particularly toxic in neurons, resulting in mitochondrial defects and Ser65-phospho-Ubiquitin accumulation. Age-related increase of Cisd blocks mitophagy and impairs autophagy flux. Importantly, reduction of Cisd levels upregulates mitophagy in vitro and in vivo, and ameliorates pathological phenotypes in locomotion, lifespan and neurodegeneration in Pink1/parkin mutant flies. In addition, we show that pharmacological inhibition of CISD1/2 by rosiglitazone and NL-1 induces mitophagy in human cells and rescues the defective phenotypes of Pink1/parkin mutants. ConclusionAltogether, our studies indicate that Cisd accumulation during aging and in Pink1/parkin mutants is a key driver of pathology by blocking mitophagy, and genetically and pharmacologically inhibiting CISD proteins may offer a potential target for therapeutic intervention.

neuroscience↗

bioRxiv2023

Regulation of Human PINK1 ubiquitin kinase by Serine167, Serine228 and Cysteine412 phosphorylation

Loss-of-function mutations in the human PINK1 kinase (hPINK1) are causative of early-onset Parkinsons disease (PD). Activation of hPINK1 induces phosphorylated ubiquitin to initiate removal of damaged mitochondria by autophagy. Previously we solved the structure of the insect PINK1 orthologue, Tribolium castaneum PINK1, and showed that autophosphorylation of Ser205 was critical for ubiquitin interaction and phosphorylation (Kumar, Tamjar, Waddell et al., 2017). In this advance, we report new findings on the regulation of hPINK1 by phosphorylation. We reconstitute E. coli expressed hPINK1 activity in vitro by direct incorporation of phosphoserine at the equivalent site Serine 228 (pSer228), providing direct evidence for a role for Ser228 phosphorylation in hPINK1 activation. Furthermore, using mass spectrometry, we identify six novel Ser/Thr autophosphorylation sites including regulatory Serine167 phosphorylation (pSer167), which in addition to pSer228 is required for ubiquitin recognition and phosphorylation. Strikingly, we also detect phosphorylation of a conserved Cysteine412 (pCys412) residue in the hPINK1 activation segment. Structural modelling suggests that pCys412 inhibits ubiquitin recognition and we demonstrate that mutation of Cys412 to Ala renders hPINK1 more active towards ubiquitin when expressed in human cells. These results outline new insights into hPINK1 activation by pSer167 and pSer228 and a novel inhibitory mechanism mediated by pCys412. These findings will aid in the development of small molecule activators of hPINK1.

biochemistry↗

bioRxiv2023

USP8 inhibition promotes Parkin-independent mitophagy in the Drosophila brain and in human neurons

Stress-induced mitophagy, a tightly regulated process that targets dysfunctional mitochondria for autophagy-dependent degradation, mainly relays on two proteins, PINK1 and Parkin, which genes are mutated in some forms of familiar Parkinsons Disease (PD). Upon mitochondrial damage, the protein kinase PINK1 accumulates on the organelle surface where it controls the recruitment of the E3-ubiquitin ligase Parkin. On mitochondria, Parkin ubiquitinates a subset of mitochondrial resident proteins located on the outer mitochondrial membrane, leading to the recruitment of downstream cytosolic autophagic adaptors, and subsequent autophagosome formation. Importantly, PINK1/Parkin-independent mitophagy pathways also exist that can be counteracted by specific deubiquitinating enzymes (DUBs). Downregulation of these specific DUBs can presumably enhances basal mitophagy, and be beneficial in models in which accumulation of defective mitochondria is implicated. Among these DUBs, USP8 is an interesting target because of its role in the endosomal pathway and autophagy, and its beneficial effects, when inhibited, in models of neurodegeneration. Based on this, we evaluated autophagy and mitophagy levels when USP8 activity is altered. We used genetic approaches in D. melanogaster to measure autophagy and mitophagy in vivo, and complementary in vitro approaches to investigate the molecular pathway that regulates mitophagy via USP8. We found an inverse correlation between basal mitophagy and USP8 levels, in that inhibition of USP8 correlates with increased Parkin-independent mitophagy. These results suggest the existence of a yet uncharacterized mitophagic pathway that is inhibited by USP8.

cell biology↗

bioRxiv2022

FBXO7/ntc and USP30 antagonistically set the basal ubiquitination threshold for mitophagy.

Functional analyses of genes linked to heritable forms of Parkinsons disease (PD) have revealed fundamental insights into the biological processes underpinning pathogenic mechanisms. Mutations in PARK15/FBXO7 cause autosomal recessive PD and FBXO7 has been shown to regulate mitochondrial homeostasis. We investigated the extent to which FBXO7 and its Drosophila orthologue, ntc, share functional homology and explored its role in mitophagy in vivo. We show that ntc mutants partially phenocopy Pink1 and parkin mutants and ntc overexpression supresses parkin phenotypes. Furthermore, ntc can modulate basal mitophagy in a Pink1- and parkin-independent manner by promoting the ubiquitination of mitochondrial proteins, a mechanism that is opposed by the deubiquitinase USP30. This basal ubiquitination serves as the substrate for Pink1-mediated phosphorylation which triggers stress-induced mitophagy. We propose that FBXO7/ntc works in equilibrium with USP30 to provide a checkpoint for mitochondrial quality control in basal conditions in vivo and presents a new avenue for therapeutic approaches.

molecular biology↗

bioRxiv2022

N-terminal acetylation shields proteins from degradation and promotes age-dependent motility and longevity

Most eukaryotic proteins are N-terminally acetylated, but the functional impact on a global scale has remained obscure. Using genome-wide CRISPR knockout screens in human cells, we reveal a strong genetic dependency between a major N-terminal acetyltransferase and specific ubiquitin ligases. Biochemical analyses uncover that both the ubiquitin ligase complex UBR4-KCMF1 and the acetyltransferase NatC recognize proteins bearing an unacetylated N-terminal methionine followed by a hydrophobic residue. NatC KO-induced protein degradation and phenotypes are reversed by UBR knockdown, demonstrating the central cellular role of this interplay. We reveal that loss of Drosophila NatC is associated with male sterility, reduced longevity, and age-dependent loss of motility due to developmental muscle defects. Remarkably, muscle-specific overexpression of UbcE2M, one of the proteins targeted for NatC KO mediated degradation, suppresses defects of NatC deletion. In conclusion, NatC-mediated N-terminal acetylation acts as a protective mechanism against protein degradation, which is relevant for increased longevity and motility. In BriefVarland, Silva et al. define that a major cellular role of N-terminal acetylation is shielding proteins from proteasomal degradation by specific ubiquitin ligases. The human N-terminal acetyltransferase NatC protects the neddylation regulator UBE2M from degradation, while overexpression of Drosophila UBE2M/UbcE2M rescues the longevity and motility defects of NatC deletion. HighlightsO_LIN-terminal acetylation by NatC protects proteins from degradation, including UBE2M C_LIO_LIUBR4-KCMF1 targets unacetylated N-terminal Met followed by a hydrophobic residue C_LIO_LIDrosophila NatC is required for adult longevity and motility in elderly C_LIO_LIOverexpression of UBE2M/UbcE2M suppresses Drosophila NatC deletion phenotypes C_LI

molecular biology↗

bioRxiv2021

Parkin drives pS65-Ub turnover independently of canonical autophagy in Drosophila

Parkinsons disease-related proteins, PINK1 and Parkin, act in a common pathway to maintain mitochondrial quality control. While the PINK1-Parkin pathway can promote autophagic mitochondrial turnover (mitophagy) in cell culture, recent studies have questioned whether they contribute to mitophagy in vivo, and alternative PINK1- and Parkin-dependent mitochondrial quality control pathways have been proposed. To determine the mechanisms by which the Pink1-Parkin pathway operates in vivo, we developed methods to detect Ser65-phosphorylated ubiquitin (pS65-Ub) in Drosophila. Exposure to the oxidant paraquat led to robust, Pink1-dependent pS65-Ub production. Surprisingly, parkin-null flies displayed strikingly elevated basal levels of pS65-Ub, suggestive of disrupted flux through the Pink1-parkin pathway. Depletion of the core autophagy proteins Atg1, Atg5 and Atg8a did not cause pS65-Ub accumulation to the same extent as loss of parkin, and overexpression of parkin was able to reduce both basal and paraquat-induced pS65-Ub levels in an Atg5-null background. Taken together, these results suggest that the Pink1-parkin pathway is able to promote mitochondrial turnover independently of canonical autophagy in vivo.

cell biology↗

bioRxiv2021

A late-stage assembly checkpoint of the human mitochondrial ribosome large subunit

The epitranscriptome plays a key regulatory role in cellular processes in health and disease, including ribosome biogenesis. Here, analysis of the human mitochondrial transcriptome shows that 2-O-methylation is limited to residues of the mitoribosomal large subunit (mtLSU) 16S mt-rRNA, modified by MRM1, MRM2, and MRM3. Ablation of MRM2 leads to a severe impairment of the oxidative phosphorylation system, caused by defective mitochondrial translation and accumulation of mtLSU assembly intermediates. Structures of these particles (2.58 [A]) present disordered RNA domains, partial occupancy of bL36m and bound MALSU1:L0R8F8:mtACP anti-association module. Additionally, we present five mtLSU assembly states with different intersubunit interface configurations. Complementation studies demonstrate that the methyltransferase activity of MRM2 is dispensable for mitoribosome biogenesis. The Drosophila melanogaster orthologue, DmMRM2, is an essential gene, with its knock-down leading to developmental arrest. This work identifies a key late-stage quality control step during mtLSU assembly, ultimately contributing to the maintenance of mitochondrial homeostasis.

molecular biology↗

bioRxiv2021

A cell-penetrant peptide blocking C9ORF72-repeat RNA nuclear export suppresses neurodegeneration

Hexanucleotide repeat expansions in C9ORF72 are the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), a spectrum of incurable debilitating neurodegenerative diseases. Here, we report a novel ALS/FTD drug concept with in vivo and in vitro therapeutic activity in preclinical models of C9ORF72-ALS/FTD. Our data demonstrate that supplementation or oral administration of a cell-penetrant peptide, which competes with the SRSF1:NXF1 interaction, confers neuroprotection by inhibiting the nuclear export of pathological C9ORF72-repeat transcripts in various models of disease including primary neurons, patient-derived motor neurons and Drosophila. Our drug-like rationale for disrupting the nuclear export of microsatellite repeat transcripts in neurological disorders provides a promising alternative to conventional small molecule inhibitors often limited by poor blood-brain barrier penetrance.

molecular biology↗

bioRxiv2021

Safety and efficacy of C9ORF72-repeat RNA nuclear export inhibition in amyotrophic lateral sclerosis

BackgroundLoss of motor neurons in amyotrophic lateral sclerosis (ALS) leads to progressive paralysis and death. Dysregulation of thousands of RNA molecules with roles in multiple cellular pathways hinders the identification of ALS-causing alterations over downstream changes secondary to the neurodegenerative process. How many and which of these pathological gene expression changes require therapeutic normalisation remains a fundamental question. MethodsHere, we investigated genome-wide RNA changes in C9ORF72-ALS patient-derived neurons and Drosophila, as well as upon neuroprotection taking advantage of our gene therapy approach which specifically inhibits the SRSF1-dependent nuclear export of pathological C9ORF72-repeat transcripts. This is a critical study to evaluate (i) the overall safety and efficacy of the partial depletion of SRSF1, a member of a protein family involved itself in gene expression, and (ii) a unique opportunity to identify neuroprotective RNA changes. ResultsOur study demonstrates that manipulation of 362 transcripts out of 2,257 pathological changes in C9ORF72-ALS patient-derived neurons is sufficient to confer neuroprotection upon partial depletion of SRSF1. In particular, expression of 90 disease-altered transcripts is fully reverted upon neuroprotection leading to the characterisation of a human C9ORF72-ALS disease-modifying gene expression signature. These findings were further investigated in vivo in diseased and neuroprotected Drosophila transcriptomes, highlighting a list of 21 neuroprotective changes conserved with 16 human orthologues in patient-derived neurons. We also functionally validated the high therapeutic potential of one of these disease-modifying transcripts, demonstrating that inhibition of ALS-upregulated human KCNN1-3 (Drosophila SK) voltage-gated potassium channel orthologs mitigates degeneration of human motor neurons as well as Drosophila motor deficits. ConclusionsStrikingly, manipulating the expression levels of a small proportion of RNAs is sufficient to induce a therapeutic effect, further indicating that the SRSF1-targeted gene therapy approach is safe in the above preclinical models as it does not disrupt globally gene expression. The efficacy of this intervention is also validated at genome-wide level with therapeutically-induced RNA changes involved in the vast majority of biological processes affected in C9ORF72-ALS. Finally, the identification of a characteristic signature with key RNA changes modified in both the disease state and upon neuroprotection also provides potential new therapeutic targets and biomarkers.

systems biology↗

bioRxiv2020

Decreasing pdzd8-mediated mitochondrial-ER contacts in neurons improves fitness by increasing mitophagy

The complex cellular architecture of neurons combined with their longevity makes maintaining a healthy mitochondrial network particularly important and challenging. One of the many roles of mitochondrial-ER contact sites (MERCs) is to mediate mitochondrial quality control through regulating mitochondrial turn over. Pdzd8 is a newly discovered MERC protein, the organismal functions of which have not yet been explored. Here we identify and provide the first functional characterization of the Drosophila melanogaster ortholog of Pdzd8. We find that reducing pdzd8-mediated MERCs in neurons slows age-associated decline in locomotor activity and increases lifespan in Drosophila. The protective effects of pdzd8 knockdown in neurons correlate with an increase in mitophagy, suggesting that increased mitochondrial turnover may support healthy aging of neurons. In contrast, increasing MERCs by expressing a constitutive, synthetic ER-mitochondria tether disrupts mitochondrial transport and synapse formation, accelerates age-related decline in locomotion and reduces lifespan. We also show that depletion of pdzd8 rescues the locomotor defects characterizing an Alzheimers disease (AD) fly model over-expressing Amyloid{beta}1-42 (A{beta}42) and prolongs the survival of flies fed with mitochondrial toxins. Together, our results provide the first in vivo evidence that MERCs mediated by the tethering protein pdzd8 play a critical role in the regulation of mitochondrial quality control and neuronal homeostasis.

cell biology↗

bioRxiv2020

Drosophila phosphatidylinositol-4 kinase fwd promotes mitochondrial fission and can suppress Pink1/parkin phenotypes

Balanced mitochondrial fission and fusion play an important role in shaping and distributing mitochondria, as well as contributing to mitochondrial homeostasis and adaptation to stress. In particular, mitochondrial fission is required to facilitate degradation of damaged or dysfunctional units via mitophagy. Two Parkinsons disease factors, PINK1 and Parkin, are considered key mediators of damage-induced mitophagy, and promoting mitochondrial fission is sufficient to suppress the pathological phenotypes in Pink1/parkin mutant Drosophila. We sought additional factors that impinge on mitochondrial dynamics and which may also suppress Pink1/parkin phenotypes. We found that the Drosophila phosphatidylinositol 4-kinase III{beta} homologue, Four wheel drive (Fwd), promotes mitochondrial fission downstream of the pro-fission factor Drp1. Previously described only as male sterile, we identified several new phenotypes in fwd mutants, including locomotor deficits and shortened lifespan, which are accompanied by mitochondrial dysfunction. Finally, we found that fwd overexpression can suppress locomotor deficits and mitochondrial disruption in Pink1/parkin mutants, consistent with its function in promoting mitochondrial fission. Together these results shed light on the complex mechanisms of mitochondrial fission and further underscore the potential of modulating mitochondrial fission/fusion dynamics in the context of neurodegeneration. Author SummaryMitochondria are dynamic oganelles that can fuse and divide, in part to facilitate turnover of damaged components. These processes are essential to maintain a healthy mitochondrial network, and, in turn, maintain cell viability. This is critically important in high-energy, post-mitotic tissues such as neurons. We previously identified Drosophila phosphatidylinositol-4 kinase fwd as a pro-fission factor in a cell-based screen. Here we show that loss of fwd regulates mitochondrial fission in vivo, and acts genetically downstream of Drp1. We identified new phenotypes in fwd mutants, similar to loss of Pink1/parkin, two genes linked to Parkinsons disease and key regulators of mitochondrial homeostasis. Importantly, fwd overexpression is able to substantially suppress locomotor and mitochondrial phenotypes in Pink1/parkin mutants, suggesting manipulating phophoinositides may represent a novel route to tackling Parkinsons disease.

cell biology↗

bioRxiv2019

Mitochondrial impairment activates the Wallerian pathway through depletion of NMNAT2 leading to SARM1-dependent axon degeneration

Wallerian degeneration of physically injured axons involves a well-defined molecular pathway linking loss of axonal survival factor NMNAT2 to activation of pro-degenerative protein SARM1. Manipulating the pathway through these proteins led to the identification of non-axotomy insults causing axon degeneration by a Wallerian-like mechanism, including several involving mitochondrial impairment. Mitochondrial dysfunction is heavily implicated in Parkinsons disease, Charcot-Marie-Tooth disease, hereditary spastic paraplegia and other axonal disorders. However, whether and how mitochondrial impairment activates Wallerian degeneration has remained unclear. Here, we show that disruption of mitochondrial membrane potential leads to axonal NMNAT2 depletion in mouse sympathetic neurons, increasing the substrate-to-product ratio (NMN/NAD) of this NAD-synthesising enzyme, a metabolic fingerprint of Wallerian degeneration. The mechanism appears to involve both impaired NMNAT2 synthesis and reduced axonal transport. Expression of WLDS and Sarm1 deletion both protect axons after mitochondrial uncoupling. Blocking the pathway also confers neuroprotection and increases the lifespan of flies with Pink1 loss-of-function mutation, which causes severe mitochondrial defects. These data indicate that mitochondrial impairment replicates all the major steps of Wallerian degeneration, placing it upstream of NMNAT2 loss, with the potential to contribute to axon pathology in mitochondrial disorders.

neuroscience↗

bioRxiv2018

Basal mitophagy is widespread in Drosophila but minimally affected by loss of Pink1 or parkin

Parkinsons disease factors, PINK1 and parkin, are strongly implicated in stress-induced mitophagy in vitro, but little is known about their impact on basal mitophagy in vivo. We generated transgenic Drosophila expressing fluorescent mitophagy reporters to evaluate the impact of Pink1/parkin mutations on basal mitophagy under physiological conditions. We find that mitophagy is readily detectable and abundant in many tissues including Parkinsons disease relevant dopaminergic neurons. However, we did not detect mitolysosomes in flight muscle. Surprisingly, in Pink1 or parkin null flies we did not observe any substantial impact on basal mitophagy. As these flies exhibit locomotor defects and dopaminergic neuron loss, our findings raise questions about current assumptions of the pathogenic mechanism associated with the PINK1/Parkin pathway. Our findings provide evidence that Pink1 and parkin are not essential for bulk basal mitophagy in Drosophila. They also emphasize that mechanisms underpinning basal mitophagy remain largely obscure.\n\nSummaryPINK1/parkin are key mediators of stress-induced mitophagy in vitro but their impact on basal mitophagy in vivo is unclear. Novel Drosophila reporters lines reveal abundant mitophagy in many tissues including dopaminergic neurons but is unaffected by loss of PINK1/parkin.

cell biology↗