Protein import motor complex reacts to mitochondrial misfolding by reducing protein import and activating mitophagy
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA854161 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR19901592.fastq.gz | Fastqsanger.gz | |||
| SRR19901593.fastq.gz | Fastqsanger.gz |
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Project description:Mitophagy is essential to maintain mitochondrial function and prevent diseases. It activates upon mitochondria depolarization, which causes PINK1 stabilization on the mitochondrial outer membrane. Strikingly, a number of conditions, including mitochondrial protein misfolding, can induce mitophagy without a loss in membrane potential. The underlying molecular details remain unclear. Here, we report that a loss of mitochondrial protein import, mediated by the pre-sequence translocase-associated motor complex PAM, is sufficient to induce mitophagy in polarized mitochondria. A genome-wide CRISPR/Cas9 screen for mitophagy inducers identifies components of the PAM complex. Protein import defects are able to induce mitophagy without a need for depolarization. Upon mitochondrial protein misfolding, PAM dissociates from the import machinery resulting in decreased protein import and mitophagy induction. Our findings extend the current mitophagy model to explain mitophagy induction upon conditions that do not affect membrane polarization, such as mitochondrial protein misfolding.
2022-08-04 | GSE207212 | GEO
Project description:Upon mitochondrial dysfunction, mitophagy has been described to be activated by a breakdown of membrane potential leading to PINK1 accumulation on the outer membrane and engulfment of mitochondria for degradation. However, recent findings have indicated that mitophagy may also be triggered in the absence of membrane potential alterations. Here, we report mechanistic details on how inhibition of protein import induces mitophagy independent of mitochondrial membrane depolarization. Carrying out a genome-wide CRISPR/Cas9 screen for regulators of mitophagy, we found that the pre-sequence translocase-associated motor complex PAM controls mitophagy induction. Loss of PAM caused defects in protein import and was sufficient to induce mitophagy without depolarization. Quantitative interaction and aggregation proteomics revealed that PAM was highly sensitive to proteostasis perturbation; upon misfolding conditions, PAM dissociated from the import machinery, sequestered into the insoluble fraction and caused mitophagy despite an intact membrane potential. Our findings extend the current mitophagy model and provide mechanistic insight into how proteostasis perturbation leads to mitophagy induction. They reveal the PAM complex as key folding sensor integrating proteostasis, import and mitophagy.
2022-09-03 | PXD022560 | Pride
Project description:Mitophagy is essential to maintain mitochondrial function and prevent diseases. It activates upon mitochondria depolarization, which causes PINK1 stabilization on the mitochondrial outer membrane. Strikingly, a number of conditions, including mitochondrial protein misfolding, can induce mitophagy without a loss in membrane potential. The underlying molecular details remain unclear. Here, we report that a loss of mitochondrial protein import, mediated by the pre-sequence translocase-associated motor complex PAM, is sufficient to induce mitophagy in polarized mitochondria. A genome-wide CRISPR/Cas9 screen for mitophagy inducers identifies components of the PAM complex. Protein import defects are able to induce mitophagy without a need for depolarization. Upon mitochondrial protein misfolding, PAM dissociates from the import machinery resulting in decreased protein import and mitophagy induction. Our findings extend the current mitophagy model to explain mitophagy induction upon conditions that do not affect membrane polarization, such as mitochondrial protein misfolding.
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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.
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2023-03-17 | GSE227295 | GEO
Project description:Upon mitochondrial dysfunction, mitophagy has been described to be activated by a breakdown of membrane potential leading to PINK1 accumulation on the outer membrane and engulfment of mitochondria for degradation. However, recent findings have indicated that mitophagy may also be triggered in the absence of membrane potential alterations. Here, we report mechanistic details on how inhibition of protein import induces mitophagy independent of mitochondrial membrane depolarization. Carrying out a genome-wide CRISPR/Cas9 screen for regulators of mitophagy, we found that the pre-sequence translocase-associated motor complex PAM controls mitophagy induction. Loss of PAM caused defects in protein import and was sufficient to induce mitophagy without depolarization. Quantitative interaction and aggregation proteomics revealed that PAM was highly sensitive to proteostasis perturbation; upon misfolding conditions, PAM dissociated from the import machinery, sequestered into the insoluble fraction and caused mitophagy despite an intact membrane potential. Our findings extend the current mitophagy model and provide mechanistic insight into how proteostasis perturbation leads to mitophagy induction. They reveal the PAM complex as key folding sensor integrating proteostasis, import and mitophagy.
2022-09-03 | PXD022524 | Pride
Project description:Upon mitochondrial dysfunction, mitophagy has been described to be activated by a breakdown of membrane potential leading to PINK1 accumulation on the outer membrane and engulfment of mitochondria for degradation. However, recent findings have indicated that mitophagy may also be triggered in the absence of membrane potential alterations. Here, we report mechanistic details on how inhibition of protein import induces mitophagy independent of mitochondrial membrane depolarization. Carrying out a genome-wide CRISPR/Cas9 screen for regulators of mitophagy, we found that the pre-sequence translocase-associated motor complex PAM controls mitophagy induction. Loss of PAM caused defects in protein import and was sufficient to induce mitophagy without depolarization. Quantitative interaction and aggregation proteomics revealed that PAM was highly sensitive to proteostasis perturbation; upon misfolding conditions, PAM dissociated from the import machinery, sequestered into the insoluble fraction and caused mitophagy despite an intact membrane potential. Our findings extend the current mitophagy model and provide mechanistic insight into how proteostasis perturbation leads to mitophagy induction. They reveal the PAM complex as key folding sensor integrating proteostasis, import and mitophagy.
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Project description:Mitochondrial protein import clogging as a mechanism of disease
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Project description:The biogenesis of nearly all mitochondrial proteins begins with translation on cytosolic ribosomes. How these proteins are subsequently delivered to mitochondria remains poorly understood. Here, we systematically investigated the coupling of mitochondrial protein translation and import using selective ribosome profiling in human cells. Cotranslational targeting requires an N-terminal presequence on the nascent protein and contributes to mRNA localization at the mitochondrial surface. This pathway is predominantly used by large, multidomain and topologically complex proteins, whose import efficiency is enhanced when targeted cotranslationally. In contrast to protein targeting to the endoplasmic reticulum (ER), cotranslational mitochondrial import does not favor membrane proteins and initiates late during translation, specifically upon the exposure of a complex globular fold in the nascent protein. Our findings reveal a multi-layered protein sorting system that recognizes both the targeting signal and protein folding status during translation.
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Project description:Aim: To identify regulatory factors that control: (1) chloroplast protein importand (2) chloroplast-to-nucleus signalling. This project is a joint proposal from the Jarvis lab which is interested in chloroplast protein import [1] and the Moller lab which is interested in plastid-to-nucleus signalling [2]. Background: The majority of chloroplast proteins are encoded in the nucleus and imported post-translationally into chloroplasts. The abundance of chloroplast proteins may therefore be regulated at multiple levels. It is well documented that the nuclear gene expression is responsive to (largely unknown) signals from the chloroplast [23] and evidence is now emerging that protein import is also a regulated process [1]. Protein import into chloroplasts is mediated by protein complexes in the outer and inner envelope membranes called Toc and Tic respectively. Biochemical studies of pea chloroplasts identified several Toc/Tic components. These proteins are mechanistic or structural components of the import apparatus. Arabidopsis homologues of the pea Toc/Tic proteins were identified by the AGI. Pea Toc34 is represented in Arabidopsis by two genes "Toc33 and Toc34" and pea Toc75 is represented by three genes. These different Tocs have different expression patterns and are proposed to have different precursor protein recognition specificities. The factors that regulate Toc expression in concert with the needs of plastids in developmentally different cells are unknown. Proposal: Two Arabidopsis mutants will be analysed. The ppi1 mutant is null for the putative precursor protein receptor Toc33 [1]and the ppi3 mutant is null for a putative component of the protein import channel Toc75-IV (on chromosome IV). ppi1 plants are yellow-green in appearance but remarkably healthy and grow only slightly more slowly than wild type. By contrast ppi3 plants are indistinguishable from wild type by eye although analysis of the mutant's chloroplast proteome is beginning to reveal some differences (K. Lilley personal communication). Gene expression changes in ppi1 are likely to be quite extensive. Retardation of chloroplast development in ppi1 will activate retrograde signalling pathways so that many nuclear photosynthetic genes are down-regulated. Changes in the expression of photosynthetic genes and of the genes responsible for mediating these responses may therefore be observed. Any regulatory and signalling genes identified will be of interest to the Moller lab. The expression of factors that regulate Toc/Tic gene expression may also be altered in ppi1. It should be possible to distinguish these factors from those involved in the general control of chloroplast gene expression by comparing the results from the two mutants. Genes affected in both mutants are more likely to be involved in regulating chloroplast import since it is unlikely that widespread changes in gene expression will be observed in ppi3. Changes in the expression of factors that regulate import post-translationallyand of the Toc/Tic genes themselves (many are on the RNA) may also be observed. References: 1. Jarvis P. et al. (1998) Science 282: 100-103. 2. Moller S.G. et al. (2001) Genes Dev. 15:90-103. 3. Jarvis P. (2001) Curr. Biol. 11: R307-R310.
2022-11-21 | E-NASC-35 | biostudies-arrayexpress