PINK1-mediated phosphorylation of the Parkin ubiquitin-like domain primes mitochondrial translocation of Parkin and regulates mitophagy.
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ABSTRACT:
SUBMITTER: Shiba-Fukushima K
PROVIDER: S-EPMC3525937 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Mutations in the mitochondrial protein kinase PINK1 are associated with autosomal recessive Parkinson disease (PD). We and other groups have reported that PINK1 activates Parkin E3 ligase activity both directly via phosphorylation of Parkin serine 65 (Ser(65))--which lies within its ubiquitin-like domain (Ubl)--and indirectly through phosphorylation of ubiquitin at Ser(65). How Ser(65)-phosphorylated ubiquitin (ubiquitin(Phospho-Ser65)) contributes to Parkin activation is currently unknown. Here, we demonstrate that ubiquitin(Phospho-Ser65) binding to Parkin dramatically increases the rate and stoichiometry of Parkin phosphorylation at Ser(65) by PINK1 in vitro. Analysis of the Parkin structure, corroborated by site-directed mutagenesis, shows that the conserved His302 and Lys151 residues play a critical role in binding of ubiquitin(Phospho-Ser65), thereby promoting Parkin Ser(65) phosphorylation and activation of its E3 ligase activity in vitro. Mutation of His302 markedly inhibits Parkin Ser(65) phosphorylation at the mitochondria, which is associated with a marked reduction in its E3 ligase activity following mitochondrial depolarisation. We show that the binding of ubiquitin(Phospho-Ser65) to Parkin disrupts the interaction between the Ubl domain and C-terminal region, thereby increasing the accessibility of Parkin Ser(65). Finally, purified Parkin maximally phosphorylated at Ser(65) in vitro cannot be further activated by the addition of ubiquitin(Phospho-Ser65). Our results thus suggest that a major role of ubiquitin(Phospho-Ser65) is to promote PINK1-mediated phosphorylation of Parkin at Ser(65), leading to maximal activation of Parkin E3 ligase activity. His302 and Lys151 are likely to line a phospho-Ser(65)-binding pocket on the surface of Parkin that is critical for the ubiquitin(Phospho-Ser65) interaction. This study provides new mechanistic insights into Parkin activation by ubiquitin(Phospho-Ser65), which could aid in the development of Parkin activators that mimic the effect of ubiquitin(Phospho-Ser65).
| S-EPMC4552487 | biostudies-literature
Project description:Ubiquitin phosphorylation by the mitochondrial protein kinase PTEN-induced kinase 1 (PINK1), upon mitochondrial depolarization, is an important intermediate step in the recycling of damaged mitochondria via mitophagy. As mutations in PINK1 can cause early-onset Parkinson's disease (PD), there has been a growing interest in small-molecule activators of PINK1-mediated mitophagy as potential PD treatments. Herein, we show that N6-substituted adenosines, such as N6-(2-furanylmethyl)adenosine (known as kinetin riboside) and N6-benzyladenosine, activate PINK1 in HeLa cells and induce PINK1-dependent mitophagy in primary mouse fibroblasts. Interestingly, pre-treatment of HeLa cells and astrocytes with these compounds inhibited elevated ubiquitin phosphorylation that is induced by established mitochondrial depolarizing agents, carbonyl cyanide m-chlorophenyl-hydrazine and niclosamide. Together, this highlights N6-substituted adenosines as progenitor PINK1 activators that could potentially be developed, in the future, as treatments for aged and sporadic PD patients who have elevated phosphorylated ubiquitin levels in the brain.
| S-EPMC10258795 | biostudies-literature
Project description:PINK1 is a mitochondrial kinase proposed to have a role in the pathogenesis of Parkinson's disease through the regulation of mitophagy. Here, we show that the PINK1 main cleavage product, PINK152, after being generated inside mitochondria, can exit these organelles and localize to the cytosol, where it is not only destined for degradation by the proteasome but binds to Parkin. The interaction of cytosolic PINK1 with Parkin represses Parkin translocation to the mitochondria and subsequent mitophagy. Our work therefore highlights the existence of two cellular pools of PINK1 that have different effects on Parkin translocation and mitophagy.
| S-EPMC4303452 | biostudies-other
Project description:Loss-of-function mutations in the PTEN-induced kinase 1 (PINK1) or parkin genes, which encode a mitochondrially localized serine/threonine kinase and a ubiquitin-protein ligase, respectively, result in recessive familial forms of Parkinsonism. Genetic studies in Drosophila indicate that PINK1 acts upstream of Parkin in a common pathway that influences mitochondrial integrity in a subset of tissues, including flight muscle and dopaminergic neurons. The mechanism by which PINK1 and Parkin influence mitochondrial integrity is currently unknown, although mutations in the PINK1 and parkin genes result in enlarged or swollen mitochondria, suggesting a possible regulatory role for the PINK1/Parkin pathway in mitochondrial morphology. To address this hypothesis, we examined the influence of genetic alterations affecting the machinery that governs mitochondrial morphology on the PINK1 and parkin mutant phenotypes. We report that heterozygous loss-of-function mutations of drp1, which encodes a key mitochondrial fission-promoting component, are largely lethal in a PINK1 or parkin mutant background. Conversely, the flight muscle degeneration and mitochondrial morphological alterations that result from mutations in PINK1 and parkin are strongly suppressed by increased drp1 gene dosage and by heterozygous loss-of-function mutations affecting the mitochondrial fusion-promoting factors OPA1 and Mfn2. Finally, we find that an eye phenotype associated with increased PINK1/Parkin pathway activity is suppressed by perturbations that reduce mitochondrial fission and enhanced by perturbations that reduce mitochondrial fusion. Our studies suggest that the PINK1/Parkin pathway promotes mitochondrial fission and that the loss of mitochondrial and tissue integrity in PINK1 and parkin mutants derives from reduced mitochondrial fission.
| S-EPMC2234197 | biostudies-literature
Project description:The kinase PINK1 and the E3 ubiquitin (Ub) ligase Parkin participate in mitochondrial quality control. The phosphorylation of Ser65 in Parkin's ubiquitin-like (UBl) domain by PINK1 stimulates Parkin activation and translocation to damaged mitochondria, which induces mitophagy generating polyUb chain. However, Parkin Ser65 phosphorylation is insufficient for Parkin mitochondrial translocation. Here we report that Ser65 in polyUb chain is also phosphorylated by PINK1, and that phosphorylated polyUb chain on mitochondria tethers Parkin at mitochondria. The expression of Tom70MTS-4xUb SE, which mimics phospho-Ser65 polyUb chains on the mitochondria, activated Parkin E3 activity and its mitochondrial translocation. An E3-dead form of Parkin translocated to mitochondria with reduced membrane potential in the presence of Tom70(MTS)-4xUb SE, whereas non-phospho-polyUb mutant Tom70(MTS)-4xUb SA abrogated Parkin translocation. Parkin binds to the phospho-polyUb chain through its RING1-In-Between-RING (IBR) domains, but its RING0-linker is also required for mitochondrial translocation. Moreover, the expression of Tom70(MTS)-4xUb SE improved mitochondrial degeneration in PINK1-deficient, but not Parkin-deficient, Drosophila. Our study suggests that the phosphorylation of mitochondrial polyUb by PINK1 is implicated in both Parkin activation and mitochondrial translocation, predicting a chain reaction mechanism of mitochondrial phospho-polyUb production by which rapid translocation of Parkin is achieved.
| S-EPMC4256268 | biostudies-literature
Project description:We have previously reported that the Parkinson's disease-associated kinase PINK1 (PTEN-induced putative kinase 1) is activated by mitochondrial depolarization and stimulates the Parkin E3 ligase by phosphorylating Ser65 within its Ubl (ubiquitin-like) domain. Using phosphoproteomic analysis, we identified a novel ubiquitin phosphopeptide phosphorylated at Ser65 that was enriched 14-fold in HEK (human embryonic kidney)-293 cells overexpressing wild-type PINK1 stimulated with the mitochondrial uncoupling agent CCCP (carbonyl cyanide m-chlorophenylhydrazone), to activate PINK1, compared with cells expressing kinase-inactive PINK1. Ser65 in ubiquitin lies in a similar motif to Ser65 in the Ubl domain of Parkin. Remarkably, PINK1 directly phosphorylates Ser65 of ubiquitin in vitro. We undertook a series of experiments that provide striking evidence that Ser65-phosphorylated ubiquitin (ubiquitinPhospho-Ser65) functions as a critical activator of Parkin. First, we demonstrate that a fragment of Parkin lacking the Ubl domain encompassing Ser65 (?Ubl-Parkin) is robustly activated by ubiquitinPhospho-Ser65, but not by non-phosphorylated ubiquitin. Secondly, we find that the isolated Parkin Ubl domain phosphorylated at Ser65 (UblPhospho-Ser65) can also activate ?Ubl-Parkin similarly to ubiquitinPhospho-Ser65. Thirdly, we establish that ubiquitinPhospho-Ser65, but not non-phosphorylated ubiquitin or UblPhospho-Ser65, activates full-length wild-type Parkin as well as the non-phosphorylatable S65A Parkin mutant. Fourthly, we provide evidence that optimal activation of full-length Parkin E3 ligase is dependent on PINK1-mediated phosphorylation of both Parkin at Ser65 and ubiquitin at Ser65, since only mutation of both proteins at Ser65 completely abolishes Parkin activation. In conclusion, the findings of the present study reveal that PINK1 controls Parkin E3 ligase activity not only by phosphorylating Parkin at Ser65, but also by phosphorylating ubiquitin at Ser65. We propose that phosphorylation of Parkin at Ser65 serves to prime the E3 ligase enzyme for activation by ubiquitinPhospho-Ser65, suggesting that small molecules that mimic ubiquitinPhospho-Ser65 could hold promise as novel therapies for Parkinson's disease.
| S-EPMC4000136 | biostudies-literature
Project description:Defective mitophagy linked to dysfunction in the proteins Parkin and PTEN-induced putative kinase 1 (PINK1) is implicated in the pathogenesis of Parkinson's disease. Although the mechanism by which Parkin mediates mitophagy in a PINK1-dependent manner is becoming clearer, the triggers for this mitophagy pathway remain elusive. Reactive oxygen species (ROS) have been suggested as such triggers, but this proposal remains controversial because ROS scavengers fail to retard mitophagy. Here we demonstrate that the role of ROS in mitophagy has been underappreciated as a result of the inefficiency of ROS scavengers to control ROS bursts after high-dose treatment with carbonyl cyanide m-chlorophenylhydrazone. Supporting this, combinatorial treatment with N-acetyl-l-cysteine and catalase substantially inhibited the ROS upsurge and PINK1-dependent Parkin translocation to mitochondria in response to carbonyl cyanide m-chlorophenylhydrazone treatment. In addition to the chemical mitophagy inducer, overexpression of voltage-dependent anion channel 1 (VDAC1) induced Parkin translocation to mitochondria, presumably by stimulating ROS generation. Similarly, combined N-acetyl-l-cysteine and catalase treatment also suppressed VDAC1-induced redistribution of Parkin. Alongside these observations, we also found that the elevated protein level of PINK1 was not necessary for Parkin translocation to mitochondria. Thus, our data suggest that ROS may act as a trigger for the induction of Parkin/PINK1-dependent mitophagy. In addition, our study casts doubt on the importance of protein quantity of PINK1 in the recruitment of Parkin to mitochondria.
| S-EPMC5633131 | biostudies-other
Project description:The PTEN-induced putative kinase protein 1 (PINK1) and ubiquitin (UB) ligase PARKIN direct damaged mitochondria for mitophagy. PINK1 promotes PARKIN recruitment to the mitochondrial outer membrane (MOM) for ubiquitylation of MOM proteins with canonical and noncanonical UB chains. PINK1 phosphorylates both Ser65 (S65) in the UB-like domain of PARKIN and the conserved Ser in UB itself, but the temporal sequence and relative importance of these events during PARKIN activation and mitochondria quality control remain poorly understood. Using "UB(S65A)-replacement," we find that PARKIN phosphorylation and activation, and ubiquitylation of Lys residues on a cohort of MOM proteins, occur similarly irrespective of the ability of the UB-replacement to be phosphorylated on S65. In contrast, polyubiquitin (poly-UB) chain synthesis, PARKIN retention on the MOM, and mitophagy are reduced in UB(S65A)-replacement cells. Analogous experiments examining roles of individual UB chain linkage types revealed the importance of K6 and K63 chain linkages in mitophagy, but phosphorylation of K63 chains by PINK1 did not enhance binding to candidate mitophagy receptors optineurin (OPTN), sequestosome-1 (p62), and nuclear dot protein 52 (NDP52) in vitro. Parallel reaction monitoring proteomics of total mitochondria revealed the absence of p-S65-UB when PARKIN cannot build UB chains, and <0.16% of the monomeric UB pool underwent S65 phosphorylation upon mitochondrial damage. Combining p-S65-UB and p-S65-PARKIN in vitro showed accelerated transfer of nonphosphorylated UB to PARKIN itself, its substrate mitochondrial Rho GTPase (MIRO), and UB. Our data further define a feed-forward mitochondrial ubiquitylation pathway involving PARKIN activation upon phosphorylation, UB chain synthesis on the MOM, UB chain phosphorylation, and further PARKIN recruitment and enzymatic amplification via binding to phosphorylated UB chains.
| S-EPMC4450373 | biostudies-other
Project description:Mitochondrial dysfunction has been linked to the pathogenesis of a large number of inherited diseases in humans, including Parkinson's disease, the second most common neurodegenerative disorder. The Parkinson's disease genes pink1 and parkin, which encode a mitochondrially targeted protein kinase, and an E3 ubiquitin ligase, respectively, participate in a key mitochondrial quality-control pathway that eliminates damaged mitochondria. In the current study, we established an in vivo PINK1/Parkin-induced photoreceptor neuron degeneration model in Drosophila with the aim of dissecting the PINK1/Parkin pathway in detail. Using LC-MS/MS analysis, we identified Serine 346 as the sole autophosphorylation site of Drosophila PINK1 and found that substitution of Serine 346 to Alanine completely abolished the PINK1 autophosphorylation. Disruption of either PINK1 or Parkin phosphorylation impaired the PINK1/Parkin pathway, and the degeneration phenotype of photoreceptor neurons was obviously alleviated. Phosphorylation of PINK1 is not only required for the PINK1-mediated mitochondrial recruitment of Parkin but also induces its kinase activity toward Parkin. In contrast, phosphorylation of Parkin by PINK1 is dispensable for its translocation but required for its activation. Moreover, substitution with autophosphorylation-deficient PINK1 failed to rescue pink1 null mutant phenotypes. Taken together, our findings suggest that autophosphorylation of PINK1 is essential for the mitochondrial translocation of Parkin and for subsequent phosphorylation and activation of Parkin.
| S-EPMC5261015 | biostudies-literature
Project description:Loss of the E3 ubiquitin ligase Parkin causes early onset Parkinson's disease, a neurodegenerative disorder of unknown etiology. Parkin has been linked to multiple cellular processes including protein degradation, mitochondrial homeostasis, and autophagy; however, its precise role in pathogenesis is unclear. Recent evidence suggests that Parkin is recruited to damaged mitochondria, possibly affecting mitochondrial fission and/or fusion, to mediate their autophagic turnover. The precise mechanism of recruitment and the ubiquitination target are unclear. Here we show in Drosophila cells that PINK1 is required to recruit Parkin to dysfunctional mitochondria and promote their degradation. Furthermore, PINK1 and Parkin mediate the ubiquitination of the profusion factor Mfn on the outer surface of mitochondria. Loss of Drosophila PINK1 or parkin causes an increase in Mfn abundance in vivo and concomitant elongation of mitochondria. These findings provide a molecular mechanism by which the PINK1/Parkin pathway affects mitochondrial fission/fusion as suggested by previous genetic interaction studies. We hypothesize that Mfn ubiquitination may provide a mechanism by which terminally damaged mitochondria are labeled and sequestered for degradation by autophagy.
| S-EPMC2841909 | biostudies-other