Mitochondrial dysfunction and mitophagy defect triggered by heterozygous GBA mutations

Abstract

Heterozygous mutations in GBA, the gene encoding the lysosomal enzyme glucosylceramidase beta/β-glucocerebrosidase, comprise the most common genetic risk factor for Parkinson disease (PD), but the mechanisms underlying this association remain unclear. Here, we show that in GbaL444P/WT knockin mice, the L444P heterozygous Gba mutation triggers mitochondrial dysfunction by inhibiting autophagy and mitochondrial priming, two steps critical for the selective removal of dysfunctional mitochondria by autophagy, a process known as mitophagy. In SHSY-5Y neuroblastoma cells, the overexpression of L444P GBA impeded mitochondrial priming and autophagy induction when endogenous lysosomal GBA activity remained intact. By contrast, genetic depletion of GBA inhibited lysosomal clearance of autophagic cargo. The link between heterozygous GBA mutations and impaired mitophagy was corroborated in postmortem brain tissue from PD patients carrying heterozygous GBA mutations, where we found increased mitochondrial content, mitochondria oxidative stress and impaired autophagy. Our findings thus suggest a mechanistic basis for mitochondrial dysfunction associated with GBA heterozygous mutations.Abbreviations: AMBRA1: autophagy/beclin 1 regulator 1; BECN1: beclin 1, autophagy related; BNIP3L/Nix: BCL2/adenovirus E1B interacting protein 3-like; CCCP: carbonyl cyanide 3-chloroyphenylhydrazone; CYCS: cytochrome c, somatic; DNM1L/DRP1: dynamin 1-like; ER: endoplasmic reticulum; GBA: glucosylceramidase beta; GBA-PD: Parkinson disease with heterozygous GBA mutations; GD: Gaucher disease; GFP: green fluorescent protein; LC3B: microtubule-associated protein 1 light chain 3 beta; LC3B-II: lipidated form of microtubule-associated protein 1 light chain 3 beta; MitoGreen: MitoTracker Green; MitoRed: MitoTracker Red; MMP: mitochondrial membrane potential; MTOR: mechanistic target of rapamycin kinase; MYC: MYC proto-oncogene, bHLH transcription factor; NBR1: NBR1, autophagy cargo receptor; Non-GBA-PD: Parkinson disease without GBA mutations; PD: Parkinson disease; PINK1: PTEN induced putative kinase 1; PRKN/PARK2: parkin RBR E3 ubiquitin protein ligase; RFP: red fluorescent protein; ROS: reactive oxygen species; SNCA: synuclein alpha; SQSTM1/p62: sequestosome 1; TIMM23: translocase of inner mitochondrial membrane 23; TOMM20: translocase of outer mitochondrial membrane 20; VDAC1/Porin: voltage dependent anion channel 1; WT: wild type

Mechanisms and roles of mitophagy in neurodegenerative diseases

“…During erythrocyte maturation, NIX is essential for mitochondrial clearance, where mitophagy plays a developmental role. Autophagosome can recognize target mitochondria through LC3 adapters (in ubiquitin‐dependent and ubiquitin‐independent manners) and the direct interaction of LC3 with its receptors …”

“…Autophagosome can recognize target mitochondria through LC3 adapters (in ubiquitin-dependent and ubiquitin-independent manners) and the direct interaction of LC3 with its receptors. 34…”

In Vivo Mitochondrial Function in Idiopathic and Genetic Parkinson’s Disease

“…Whereas homozygous GBA mutation cause Gaucher disease (GD), GBA heterozygosity is a potential risk factor for developing PD with an earlier age of onset and a major risk to develop dementia compared to idiopathic PD [17]. Moreover, recent studies showed that GBA heterozygous mutation is linked with dysfunction in mitophagy [18,19].…”

ECSIT prevents Alzheimer’s disease pathology by regulating neuronal mitochondrial ROS and mitophagy

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