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| 2. |
- Caulfield, Thomas R., et al.
(författare)
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Phosphorylation by PINK1 Releases the UBL Domain and Initializes the Conformational Opening of the E3 Ubiquitin Ligase Parkin
- 2014
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Ingår i: PloS Computational Biology. - : Public Library of Science (PLoS). - 1553-734X .- 1553-7358. ; 10:11, s. e1003935-
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Tidskriftsartikel (refereegranskat)abstract
- Loss-of-function mutations in PINK1 or PARKIN are the most common causes of autosomal recessive Parkinson's disease. Both gene products, the Ser/Thr kinase PINK1 and the E3 Ubiquitin ligase Parkin, functionally cooperate in a mitochondrial quality control pathway. Upon stress, PINK1 activates Parkin and enables its translocation to and ubiquitination of damaged mitochondria to facilitate their clearance from the cell. Though PINK1-dependent phosphorylation of Ser65 is an important initial step, the molecular mechanisms underlying the activation of Parkin's enzymatic functions remain unclear. Using molecular modeling, we generated a complete structural model of human Parkin at all atom resolution. At steady state, the Ub ligase is maintained inactive in a closed, auto-inhibited conformation that results from intra-molecular interactions. Evidently, Parkin has to undergo major structural rearrangements in order to unleash its catalytic activity. As a spark, we have modeled PINK1-dependent Ser65 phosphorylation in silico and provide the first molecular dynamics simulation of Parkin conformations along a sequential unfolding pathway that could release its intertwined domains and enable its catalytic activity. We combined free (unbiased) molecular dynamics simulation, Monte Carlo algorithms, and minimalbiasing methods with cell-based high content imaging and biochemical assays. Phosphorylation of Ser65 results in widening of a newly defined cleft and dissociation of the regulatory N-terminal UBL domain. This motion propagates through further opening conformations that allow binding of an Ub-loaded E2 co-enzyme. Subsequent spatial reorientation of the catalytic centers of both enzymes might facilitate the transfer of the Ub moiety to charge Parkin. Our structure-function study provides the basis to elucidate regulatory mechanisms and activity of the neuroprotective Parkin. This may open up new avenues for the development of small molecule Parkin activators through targeted drug design.
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| 3. |
- Fiesel, Fabienne C., et al.
(författare)
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Structural and Functional Impact of Parkinson Disease-Associated Mutations in the E3 Ubiquitin Ligase Parkin
- 2015
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Ingår i: Human Mutation. - : Hindawi Limited. - 1059-7794 .- 1098-1004. ; 36:8, s. 774-786
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Tidskriftsartikel (refereegranskat)abstract
- Mutations in the PARKIN/PARK2 gene that result in loss-of-function of the encoded, neuroprotective E3 ubiquitin ligase Parkin cause recessive, familial early-onset Parkinson disease. As an increasing number of rare Parkin sequence variants with unclear pathogenicity are identified, structure-function analyses will be critical to determine their disease relevance. Depending on the specific amino acids affected, several distinct pathomechanisms can result in loss of Parkin function. These include disruption of overall Parkin folding, decreased solubility, and protein aggregation. However pathogenic effects can also result from misregulation of Parkin autoinhibition and of its enzymatic functions. In addition, interference of binding to coenzymes, substrates, and adaptor proteins can affect its catalytic activity too. Herein, we have performed a comprehensive structural and functional analysis of 21 PARK2 missense mutations distributed across the individual protein domains. Using this combined approach, we were able to pinpoint some of the pathogenic mechanisms of individual sequence variants. Similar analyses will be critical in gaining a complete understanding of the complex regulations and enzymatic functions of Parkin. These studies will not only highlight the important residues, but will also help to develop novel therapeutics aimed at activating and preserving an active, neuroprotective form of Parkin.
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| 5. |
- Springer, W, et al.
(författare)
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Heterozygous PINK1 p.G411S mutation increases risk for Parkinson's disease (PD)
- 2016
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Ingår i: Movement Disorders. - : Wiley. - 0885-3185. ; 31:Suppl. S2, s. 282-282
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Konferensbidrag (refereegranskat)abstract
- Objective: To investigate the possible disease-association and pathogenic mechanisms of heterozygous PINK1 mutations from a genetic, functional, and structural perspective. Background: It has been postulated that heterozygous mutations in recessive PD genes may increase disease risk. In particular, the PINK1 p.G411S mutation has been reported in families with dominant inheritance patterns, suggesting that it might confer a sizeable disease risk. Methods: We performed a pedigree analysis of seven patients with a heterozygous PINK1 p.G411S mutation with at least one additional affected family member. We screened five case-control series and performed a meta-analysis of previous studies that had examined the variant. For functional cell-based analyses, we used patients skin fibroblast from PINK1 p.G411S or p.Q456X heterozygotes and investigated endogenous protein levels and kinase activity by biochemistry and imaging. For structural analyses, we performed molecular modeling and generated monomeric and dimeric forms of wild type (WT) and mutant PINK1 protein. Using molecular dynamics simulations, we analyzed effects of the p.G411S mutation on WT PINK1 in a heterodimeric complex over time. Results: Our analyses revealed a genetic association of heterozygous PINK1 p.G411S mutation with an increased risk for PD and a possible dominant inheritance with incomplete co-segregation. In patients skin fibroblasts, we establish a dominant negative mode for heterozygous p.G411S mutations under endogenous conditions. While total PINK1 protein levels were similar to controls upon mitochondrial stress, cellular PINK1 kinase activity was significantly reduced in p.G411S heterozygotes compared to WT and importantly to p.Q456X heterozygotes, which resulted in 50% reduction of PINK1 protein levels. Structural analyses supported our hypothesis that the p.G411S mutation can poison PINK1 WT in a heterodimeric complex and thus effectively reduce cellular PINK1 kinase activity. This in turn impairs the protective functions of the PINK1/PARKIN-mediated mitochondrial quality control. Conclusions: Our study uncovers increased disease risk and molecular mechanisms of a particular heterozygous mutation in a recessive PD gene. Based on genetic and clinical evaluation as well as functional and structural characterization, we established PINK1 p.G411S as a rare genetic risk factor with a relatively large effect size conferred by a dominant negative function phenotype.
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| 6. |
- Fiesel, Fabienne C., et al.
(författare)
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Substitution of PINK1 Gly411 modulates substrate receptivity and turnover
- 2023
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Ingår i: Autophagy. - : Informa UK Limited. - 1554-8627 .- 1554-8635. ; 19:6, s. 1711-1732
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Tidskriftsartikel (refereegranskat)abstract
- The ubiquitin (Ub) kinase-ligase pair PINK1-PRKN mediates the degradation of damaged mitochondria by macroautophagy/autophagy (mitophagy). PINK1 surveils mitochondria and upon stress accumulates on the mitochondrial surface where it phosphorylates serine 65 of Ub to activate PRKN and to drive mitochondrial turnover. While loss of either PINK1 or PRKN is genetically linked to Parkinson disease (PD) and activating the pathway seems to have great therapeutic potential, there is no formal proof that stimulation of mitophagy is always beneficial. Here we used biochemical and cell biological methods to study single nucleotide variants in the activation loop of PINK1 to modulate the enzymatic function of this kinase. Structural modeling and in vitro kinase assays were used to investigate the molecular mechanism of the PINK1 variants. In contrast to the PD-linked PINK1G411S mutation that diminishes Ub kinase activity, we found that the PINK1G411A variant significantly boosted Ub phosphorylation beyond levels of PINK1 wild type. This resulted in augmented PRKN activation, mitophagy rates and increased viability after mitochondrial stress in midbrain-derived, gene-edited neurons. Mechanistically, the G411A variant stabilizes the kinase fold of PINK1 and transforms Ub to adopt the preferred, C-terminally retracted conformation for improved substrate turnover. In summary, we identify a critical role of residue 411 for substrate receptivity that may now be exploited for drug discovery to increase the enzymatic function of PINK1. The genetic substitution of Gly411 to Ala increases mitophagy and may be useful to confirm neuroprotection in vivo and might serve as a critical positive control during therapeutic development. Abbreviations: ATP: adenosine triphosphate; CCCP: carbonyl cyanide m-chlorophenyl hydrazone; Ub-CR: ubiquitin with C-terminally retracted tail; CTD: C-terminal domain (of PINK1); ELISA: enzyme-linked immunosorbent assay; HCI: high-content imaging; IB: immunoblot; IF: immunofluorescence; NPC: neuronal precursor cells; MDS: molecular dynamics simulation; PD: Parkinson disease; p-S65-Ub: ubiquitin phosphorylated at Ser65; RMSF: root mean scare fluctuation; TOMM: translocase of outer mitochondrial membrane; TVLN: ubiquitin with T66V and L67N mutation, mimics Ub-CR; Ub: ubiquitin; WT: wild-type.
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| 7. |
- Puschmann, Andreas, et al.
(författare)
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Heterozygous PINK1 p.G411S increases risk of Parkinson's disease via a dominant-negative mechanism
- 2017
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Ingår i: Brain. - : Oxford University Press (OUP). - 1460-2156 .- 0006-8950. ; 140:1, s. 98-117
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Tidskriftsartikel (refereegranskat)abstract
- SEE GANDHI AND PLUN-FAVREAU DOI101093/AWW320 FOR A SCIENTIFIC COMMENTARY ON THIS ARTICLE: It has been postulated that heterozygous mutations in recessive Parkinson's genes may increase the risk of developing the disease. In particular, the PTEN-induced putative kinase 1 (PINK1) p.G411S (c.1231G>A, rs45478900) mutation has been reported in families with dominant inheritance patterns of Parkinson's disease, suggesting that it might confer a sizeable disease risk when present on only one allele. We examined families with PINK1 p.G411S and conducted a genetic association study with 2560 patients with Parkinson's disease and 2145 control subjects. Heterozygous PINK1 p.G411S mutations markedly increased Parkinson's disease risk (odds ratio = 2.92, P = 0.032); significance remained when supplementing with results from previous studies on 4437 additional subjects (odds ratio = 2.89, P = 0.027). We analysed primary human skin fibroblasts and induced neurons from heterozygous PINK1 p.G411S carriers compared to PINK1 p.Q456X heterozygotes and PINK1 wild-type controls under endogenous conditions. While cells from PINK1 p.Q456X heterozygotes showed reduced levels of PINK1 protein and decreased initial kinase activity upon mitochondrial damage, stress-response was largely unaffected over time, as expected for a recessive loss-of-function mutation. By contrast, PINK1 p.G411S heterozygotes showed no decrease of PINK1 protein levels but a sustained, significant reduction in kinase activity. Molecular modelling and dynamics simulations as well as multiple functional assays revealed that the p.G411S mutation interferes with ubiquitin phosphorylation by wild-type PINK1 in a heterodimeric complex. This impairs the protective functions of the PINK1/parkin-mediated mitochondrial quality control. Based on genetic and clinical evaluation as well as functional and structural characterization, we established p.G411S as a rare genetic risk factor with a relatively large effect size conferred by a partial dominant-negative function phenotype.
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| 8. |
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| 9. |
- Watzlawik, Jens O., et al.
(författare)
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Basal activity of PINK1 and PRKN in cell models and rodent brain
- 2023
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Ingår i: Autophagy. - 1554-8627.
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Tidskriftsartikel (refereegranskat)abstract
- The ubiquitin kinase-ligase pair PINK1-PRKN recognizes and transiently labels damaged mitochondria with ubiquitin phosphorylated at Ser65 (p-S65-Ub) to mediate their selective degradation (mitophagy). Complete loss of PINK1 or PRKN function unequivocally leads to early-onset Parkinson disease, but it is debated whether impairments in mitophagy contribute to disease later in life. While the pathway has been extensively studied in cell culture upon acute and massive mitochondrial stress, basal levels of activation under endogenous conditions and especially in vivo in the brain remain undetermined. Using rodent samples, patient-derived cells, and isogenic neurons, we here identified age-dependent, brain region-, and cell type-specific effects and determined expression levels and extent of basal and maximal activation of PINK1 and PRKN. Our work highlights the importance of defining critical risk and therapeutically relevant levels of PINK1-PRKN signaling which will further improve diagnosis and prognosis and will lead to better stratification of patients for future clinical trials.
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