SFXN2 contributes mitochondrial dysfunction‑induced apoptosis as a substrate of Parkin
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE294872 | GEO | 2025/08/08
REPOSITORIES: GEO
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Project description:Loss-of-function variants in the PRKN gene encoding the ubiquitin E3 ligase PARKIN cause autosomal recessive early-onset Parkinson’s disease (PD). Extensive in vitro and in vivo studies have reported that PARKIN is involved in multiple pathways of mitochondrial quality control, including mitochondrial degradation and biogenesis. However, these findings are surrounded by substantial controversy due to conflicting experimental data. In addition, the existing PARKIN-deficient mouse models have failed to faithfully recapitulate PD phenotypes. Therefore, we have investigated the mitochondrial role of PARKIN during ageing and in response to stress by employing a series of conditional Parkin knockout mice. We report that PARKIN loss does not affect oxidative phosphorylation (OXPHOS) capacity and mitochondrial DNA (mtDNA) levels in the brain, heart, and skeletal muscle of aged mice. We also demonstrate that PARKIN deficiency does not exacerbate the brain defects and the pro-inflammatory phenotype observed in mice carrying high levels of mtDNA mutations. To rule out compensatory mechanisms activated during embryonic development of Parkin-deficient mice, we generated a mouse model where loss of PARKIN was induced in adult dopaminergic (DA) neurons. Surprisingly, also these mice did not show motor impairment or neurodegeneration, and no major transcriptional changes were found in isolated midbrain DA neurons. Finally, we report a patient with compound heterozygous PRKN pathogenic variants that lacks PARKIN and has developed PD. The PARKIN deficiency did not impair OXPHOS activities or induce mitochondrial pathology in skeletal muscle from the patient. Altogether, our results argue that PARKIN is dispensable for OXPHOS function in adult mammalian tissues.
2024-04-03 | GSE263057 | GEO
Project description:Mitophagy, the selective degradation of mitochondria by autophagy, affects defective mitochondria following damage or stress. At the onset of mitophagy, parkin ubiquitylates proteins on mitochondrial outer membrane (MOM). While the role of parkin at the onset of mitophagy is well understood, less is known about its activity during later stages of the process. Here we used HeLa cells expressing catalytically active or inactive parkin to perform temporal analysis of the proteome, ubiquitylome and phosphoproteome during 18 hours after induction of mitophagy by mitochondrial uncoupler CCCP. Abundance profiles of proteins downregulated in parkin-dependent manner revealed a stepwise, “outside-in” directed degradation of mitochondrial subcompartments. While ubiquitylation of MOM proteins was enriched among early parkin-dependent targets, numerous mitochondrial inner membrane, matrix and cytosolic proteins were also found ubiquitinated at later stages of mitophagy. Phosphoproteome analysis revealed a possible cross-talk between phosphorylation and ubiquitylation during mitophagy on several key parkin targets, such as VDAC1/2.
2022-01-17 | PXD027586 | Pride
Project description:The mitochondrial kinase PINK1 and the cytosolic ubiquitin ligase (E3) Parkin is involved in mitochondrial quality control. PINK1, which phosphorylates ubiquitin at serine 65 residue and the ubiquitin-like (Ubl) domain of Parkin at serine 65 residue, promotes the Parkin activation and translocation to damaged mitochondria. When Parkin is activated, the Ubl domain are ubiquitinated at lysine 27 (K27) and lysine 48 (K48) residues. It remains unclear whether K27/K48 ubiquitination contributes to Parkin activity. In this study, we blocked the ubiquitination of K27 and/or K48 residues to examine the effects of the Parkin Ubl ubiquitination in Drosophila. Parkin replaced K27 with arginine (K27R) rescued the lethality of flies by PINK1 and Parkin co-expression whereas K48 replacement with arginine did not. Parkin K27R exhibited less ability of mitochondrial fragmentation and mitochondrial arrest, which are mediated by the degradation of Parkin E3 substrates Mitofusin and Miro, respectively. The pathogenic K27N Parkin, unlike K27R Parkin, was found to be completely devoid of E3 activity, suggesting not only that K27N Parkin is not ubiquitin-modified at the K27 residue but also that the structure of the Ubl domain itself is largely affected. Ubiquitin attached to the K27 residue of the Ubl domain during PINK1-mediated Parkin activation was likely to be phosphorylated because K27R Parkin showed less ability of Parkin self-association upon the reduction of the mitochondrial membrane potential. Our study suggests a new Parkin activation mechanism where an activating complex for Parkin is formed through phospho-ubiquitin attached to the K27 residue of the Ubl domain.
2022-08-24 | PXD026554 | JPOST Repository
Project description:Damaged mitochondria can be cleared from the cell by mitophagy, using a pathway formed by the recessive Parkinson’s disease genes PINK1 and Parkin. Whether the pathway senses diverse forms of mitochondrial damage by a common mechanism, however, remains uncertain. Here, using a novel Parkin reporter in genome-wide screens, we identified that diverse forms of mitochondrial damage converge on loss of mitochondrial membrane potential (MMP) to activate PINK1. Loss of MMP, but not the PAM import motor, blocked progression of PINK1 import through the translocase of the inner membrane (TIM23), causing it to remain bound to the translocase of the outer membrane (TOM). Ablation of TIM23 was sufficient to arrest PINK1 in TOM, irrespective of MMP. Meanwhile, TOM (including subunit TOMM5) was required for PINK1 retention on the mitochondrial surface. The energy-state outside of the mitochondria further modulated the pathway by controlling the rate of new PINK1 synthesis. Together, our findings point to a convergent mechanism of PINK1-Parkin activation by mitochondrial damage: loss of MMP stalls PINK1 import during its transfer from TOM to TIM23.
2025-08-06 | GSE298056 | GEO
Project description:Parkin, an E3 ubiquitin ligase, plays an essential role in mitochondrial quality control. However, the mechanisms by which Parkin connects mitochondrial homeostasis to cellular metabolism in adipose tissue remain unclear. Here, we demonstrate that Park2 gene (encodes Parkin) deletion specifically from adipose tissue protects mice against high-fat diet and aging-induced obesity. Despite a mild reduction in mitophagy, mitochondrial DNA (mtDNA) content and mitochondrial function are significantly increased in Park2 deficient white adipocytes. Moreover, Park2 gene deletion robustly elevates mitochondrial biogenesis by increasing Pgc1α protein stability through mitochondrial superoxide-activated Nqo1. Both in vitro and in vivo studies show that Nqo1 overexpression elevates Pgc1α protein level and mtDNA content and enhances mitochondrial activity in mouse and human adipocytes. Taken together, our findings indicate that Parkin regulates mitochondrial homeostasis by balancing mitophagy and Pgc1α-mediated mitochondrial biogenesis in white adipocytes, suggesting a potential therapeutic target in adipocytes to combat obesity and obesity-associated disorders.
2022-09-29 | GSE207496 | GEO
Project description:Dysfunctional Parkin-mediated mitophagic culling of senescent or damaged mitochondria is a major pathological process underlying Parkinson disease and a potential genetic mechanism of cardiomyopathy. Despite epidemiological associations between Parkinson disease and heart failure, the role of Parkin and mitophagic quality control in maintaining normal cardiac homeostasis is poorly understood.We used germline mutants and cardiac-specific RNA interference to interrogate Parkin regulation of cardiomyocyte mitochondria and examine functional crosstalk between mitophagy and mitochondrial dynamics in Drosophila heart tubes. 5 wild-type mouse hearts; 4 germline Parkin knockout mouse hearts Please note that the mouse cardiac examples were an adjunct to the Drosophila studies that comprised most of the associated publication. However, mRNA-sequencing was only performed on the mouse samples, not the Drosophila heart tubes.
2015-10-31 | E-GEOD-74517 | biostudies-arrayexpress
Project description:More than half of disease-causing missense variants are thought to lead to protein degradation, but the molecular mechanism of how these variants are recognized by the cell remains enigmatic. To approach this issue we have applied deep mutational scanning experiments to test the degradation of thousands of missense protein variants in large multiplexed experiments in cultured human cells. As a model protein we selected the ubiquitin-protein ligase Parkin, where known missense variants result in an autosomal recessive early onset Parkinsonism. The resulting mutational map comprises 9219 out of the 9300 (>99%) possible single-amino-acid substitution and nonsense Parkin variants. With a few notable exceptions, the majority of the destabilizing mutations are located within the structured domains of the protein, while the flexible linker regions are more tolerant to mutations. The cellular abundance data correlate with Parkin structural stability, evolutionary conservation, and separates known disease-linked variants from benign variants. Systematic mapping of degradation signals (degrons) shows that inherent primary degrons in Parkin largely overlap with regions that are highly sensitive to mutations. We identify a degron region proximal to the ACT element, which is enhanced by substitutions to hydrophobic residues. The vast majority of unstable Parkin variants are degraded through the ubiquitin-proteasome system and are stabilized at lowered temperatures. In conclusion, in addition to providing a diagnostic tool for rare genetic disorders, deep mutational scanning technologies have the potential to reveal both protein specific and general information on the specificity of the protein quality control network and the ubiquitin-proteasome system.
2024-01-31 | GSE254618 | GEO
Project description:Dysfunctional Parkin-mediated mitophagic culling of senescent or damaged mitochondria is a major pathological process underlying Parkinson disease and a potential genetic mechanism of cardiomyopathy. Despite epidemiological associations between Parkinson disease and heart failure, the role of Parkin and mitophagic quality control in maintaining normal cardiac homeostasis is poorly understood.We used germline mutants and cardiac-specific RNA interference to interrogate Parkin regulation of cardiomyocyte mitochondria and examine functional crosstalk between mitophagy and mitochondrial dynamics in Drosophila heart tubes.
2015-10-31 | GSE74517 | GEO
Project description:Purpose: The E3 ubiquitin ligase Parkin is a well-characterized regulator of mitochondrial autophagy (mitophagy); however, it is becoming increasingly appreciated to perform additional roles in various compartments of the cell. Our laboratory confirmed the presence of Parkin in the nucleus of various tissues (biochemical fractionations) and cell types (immunofluorescent imaging). Hypoxia-induced nuclear translocation of Parkin occured independent of the mitophagy regulator PINK1, and Parkinson's disease-associated mutants were restricted from the nuclueus. Accordingly, we inserted a nuclear localization sequence (NLS) at the n-terminus of Parkin and overexpressed both NLS Parkin and the wild-type protein in HeLa cells cultured at normoxia and hypoxia. Next-generation RNA-sequencing (RNA-seq) was used to determine the effect of nuclear Parkin on cellular transcription. Methods: mCherry-tagged NLS and wild-type Parkin were overexpressed in HeLa cells. Differential expression analyses were performed on Parkin vs. mCherry control cells and NLS Parkin vs. mCherry control cells at normoxia and following 12hr of hypoxia (n=3/group/condition). Paired-end sequencing was performed using the HiSeq4000. FastQC v0.11.3 was used for quality control, Trimmomatic v0.36 was used to trim reads which were aligned to the human genome (GRCh37.p13) using the STAR aligner v2.5.3a. Read quantification was performed with RSEM v 1.3.0 and the Gencode release 19. The R BioConductor packages edgeR and limma were used to implement the limma-voom method for differential expression analysis. Results: During normoxia, Parkin had no effect on basal transcription; however, overexpression of NLS Parkin was associated with 168 differentially expressed genes (DEGs: fold-change </= 1.5, FDR < 0.05) relative to mCherry control cells. Following hypoxia, the transcriptome associated with the overexpression of wild-type Parkin more closely resembled that of NLS Parkin. Along these lines, Parkin overexpression during hypoxia coincided with a total of 158 DEGs, 37% of which were shared with NLS Parkin. Overlapping and shared DEGs among Parkin and NLS Parkin were implicated in cellular metabolism, HIF1 signaling and survival. Our follow up co-immunoprecipitation and real-time quantitative PCR studies demonstrated that Parkin interacts with the Estrogen Related Receptor Alpha (ERRa) to promote the induction of its downstream target genes. Conclusions: Nuclear translocation of Parkin is a novel means by which this cytoprotective protein contributes to cellular homeostasis and especially critical during hypoxia.
2019-11-06 | GSE139989 | GEO
Project description:PINK1/parkin-dependent mitophagy initially involves (phospho) ubiquitin-proteasome-dependent degradation of certain outer mitochondrial membrane (OMM) proteins (e.g. mitofusins) and then the recruitment of autophagy effectors to more stable ubiquitinated OMM proteins. It is widely assumed that such ubiquitinated mitochondria are ultimately degraded via wholesale mitophagy. However, we demonstrate that mitochondrial degradation occurs via step-wise delivery of separate mitochondrial sub-compartments to lysosomes. OMM and inner mitochondrial material appears to become separately isolated for autophagolysosomal degradation, not only in parkin-overexpressing HeLa cells but also in cells that express endogenous parkin (human embryonic kidney cells and neural progenitor cells) with slower mitophagy kinetics. The remaining inner mitochondrial material becomes degraded only after much prolonged membrane depolarization, involving another proteasome-sensitive step. These combined microscopy and proteomics analyses lend support to the idea that cell stress-induced parkin-dependent mitophagy is a complex regulated multi-step process with distinct sub-compartments separately targeted to autophagic degradation.
2025-05-26 | PXD034136 | Pride