ATP13A2/PARK9 regulates endo-/lysosomal cargo sorting and proteostasis through a novel PI(3, 5)P2-mediated scaffolding function

Abstract

ATP13A2 (also called PARK9), is a transmembrane endo-/lysosomal-associated P5 type transport ATPase. Loss-of-function mutations in ATP13A2 result in the Kufor-Rakeb Syndrome (KRS), a form of autosomal Parkinson's disease (PD). In spite of a growing interest in ATP13A2, very little is known about its physiological role in stressed cells. Recent studies suggest that the N-terminal domain of ATP13A2 may hold key regulatory functions, but their nature remains incompletely understood. To this end, we generated a set of melanoma and neuroblastoma cell lines stably overexpressing wild-type (WT), catalytically inactive (D508N) and N-terminal mutants, or shRNA against ATP13A2. We found that under proteotoxic stress conditions, evoked by the proteasome inhibitor Bortezomib, endo-/lysosomal associated full-length ATP13A2 WT, catalytically-inactive or N-terminal fragment mutants, reduced the intracellular accumulation of ubiquitin-conjugated (Ub) proteins, independent of autophagic degradation. In contrast, ATP13A2 silencing increased the intracellular accumulation of Ub-proteins, a pattern also observed in patient-derived fibroblasts harbouring ATP13A2 loss-of function mutations. In treated cells, ATP13A2 evoked endocytic vesicle relocation and increased cargo export through nanovesicles. Expression of an ATP13A2 mutant abrogating PI(3,5)P2 binding or chemical inhibition of the PI(3,5)P2-generating enzyme PIKfyve, compromised vesicular trafficking/nanovesicles export and rescued intracellular accumulation of Ub-proteins in response to proteasomal inhibition. Hence, our study unravels a novel activity-independent scaffolding role of ATP13A2 in trafficking/export of intracellular cargo in response to proteotoxic stress.

Mutated ATP10B increases Parkinson’s disease risk by compromising lysosomal glucosylceramide export

“…To investigate whether ATP10B exerts a cell protective effect, stable cell lines were exposed to the heavy metals MnCl 2 and ZnCl 2 , the 26S proteasome inhibitor bortezomib and the mitochondrial complex I inhibitor rotenone, stressors that evoked a phenotype in cell models of ATP13A2 loss of function, another late endo-lysosomal P-type ATPase implicated in PD [26,48,68]. ATP10B WT significantly protected HeLa cells against rotenone and MnCl 2 , but not against ZnCl 2 or Bortezomib (Fig.…”

Increased Lysosomal Exocytosis Induced by Lysosomal Ca2+ Channel Agonists Protects Human Dopaminergic Neurons from α-Synuclein Toxicity

“…PARK9 encodes a lysosomal type 5 P-type ATPase involved in cation homeostasis (Gitler et al, 2009;Kong et al, 2014;, the loss of function of which leads to lysosomal dysfunction (Usenovic et al, 2012;Dehay et al, 2012;Lopes da Fonseca et al, 2016;Bento et al, 2016). ATP13A2/ PARK9 also localizes to multivesicular bodies and contributes to the formation of intraluminal vesicles, and may regulate sorting and trafficking of cargos through inositol phosphate(3,5)P2 binding to the N terminus of PARK9 (Holemans et al, 2015;Demirsoy et al, 2017). Loss of PARK9 function in patient fibroblasts leads to ␣-syn accumulation , but whether ␣-syn also accumulates in patient dopaminergic neurons and if the molecular machinery contributing to ␣-syn accumulation is amenable to therapeutic interventions remain unknown.…”

Clinical and genetic analysis of ATP13A2 in hereditary spastic paraplegia expands the phenotype

“…ATP13A2 mutations in HSP (SPG78, OMIM 617225) were first described in a consanguineous Pakistani family (Kara et al, 2016), followed by three reports on five more families (Erro, Picillo, Manara, Pellecchia, & Barone, 2019;Estrada-Cuzcano et al, 2017;van de Warrenburg et al, 2016). ATP13A2 encodes a lysosomal enzyme which serves as an inorganic cation transporter that regulates endolysosomal cargo sorting and neuronal integrity (Demirsoy et al, 2017;Ramonet et al, 2011).…”