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MitoCPR - a surveillance pathway that protects mitochondria in response to mitochondrial import stress [yeast]

ABSTRACT: Mitochondrial functions are essential for cell viability and rely on protein import into the organelle. Physiological perturbations and disease conditions can lead to mitochondrial import defect. We find that in budding yeast, mitochondrial import defects result in activation of a surveillance mechanism, which we termed mitoCPR. The mitoCPR is aimed at ameliorating mitochondrial import and protecting mitochondria during import stress. This is mediated by the mitoCPR effector, Cis1, which associates with mitochondria to reduce the accumulation of mitochondrial preproteins at the organelle's surface. Clearance of preproteins depends on the AAA-ATPase Msp1 and the proteasome, suggesting that Cis1 facilitates the degradation of unimported proteins that accumulate at the mitochondrial surface. We further show that mitoCPR is critical for maintaining mitochondrial functions during mitochondrial import stress and provide evidence that it is an ancient, conserved mitochondrial protection mechanism.

ORGANISM(S): Saccharomyces cerevisiae

PROVIDER: GSE96727 | GEO | 2019/03/16

REPOSITORIES: GEO

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mitoCPR - a surveillance pathway that protects mitochondria in response to mitochondrial import stress

Project description:Mitochondrial functions are essential for cell viability and rely on protein import into the organelle. Various disease and stress conditions can lead to mitochondrial import defects. We find that inhibition of mitochondrial import in budding yeast activates a surveillance mechanism, mitoCPR, that is aimed at ameliorating mitochondrial import and protecting mitochondria during import stress. mitoCPR induces expression of Cis1 which associates with the mitochondrial translocase to reduce the accumulation of mitochondrial precursor proteins at the organelle surface. Clearance of precursor proteins depends on the Cis1 interacting AAA+ ATPase Msp1 and the proteasome suggesting that Cis1 facilitates degradation of un-imported proteins at the mitochondrial surface.

2018-04-20 | GSE107784 | GEO

mitoCPR - a surveillance pathway that protects mitochondria in response to mitochondrial import stress [human]

Project description:Mitochondrial functions are essential for cell viability and rely on protein import into the organelle. Physiological perturbations and disease conditions can lead to mitochondrial import defect. We find that in budding yeast, mitochondrial import defects result in activation of a surveillance mechanism, which we termed mitoCPR. The mitoCPR is aimed at ameliorating mitochondrial import and protecting mitochondria during import stress. This is mediated by the mitoCPR effector, Cis1, which associates with mitochondria to reduce the accumulation of mitochondrial preproteins at the organelle's surface. Clearance of preproteins depends on the AAA-ATPase Msp1 and the proteasome, suggesting that Cis1 facilitates the degradation of unimported proteins that accumulate at the mitochondrial surface. We further show that mitoCPR is critical for maintaining mitochondrial functions during mitochondrial import stress and provide evidence that it is an ancient, conserved mitochondrial protection mechanism.

2019-03-16 | GSE96726 | GEO

Protein import motor complex reacts to mitochondrial misfolding by reducing protein import and activating mitophagy

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

Mitochondrial protein import clogging as a mechanism of disease

Project description:Mitochondrial biogenesis requires the import of >1,000 mitochondrial preproteins from the cytosol. Most studies on mitochondrial protein import are focused on the core import machinery. Whether and how the biophysical properties of substrate preproteins affect overall import efficiency is underexplored. Here, we show that protein traffic into mitochondria can be disrupted by amino acid substitutions in a single substrate preprotein. Pathogenic missense mutations in adenine nucleotide translocase 1 (Ant1), and its yeast homolog Aac2, cause the protein to accumulate along the protein import pathway, thereby obstructing general protein translocation into mitochondria. This impairs mitochondrial respiration, cytosolic proteostasis and cell viability independent of Ant1’s nucleotide transport activity. The mutations act synergistically, as double mutant Aac2/Ant1 cause severe clogging primarily at the Translocase of the Outer Membrane (TOM) complex. This confers extreme toxicity in yeast. In mice, expression of a super-clogger Ant1 variant led to neurodegeneration and an age-dependent dominant myopathy that phenocopy Ant1-induced human disease, suggesting clogging as a mechanism of disease. More broadly, this work implies the existence of uncharacterized amino acid requirements for mitochondrial carrier proteins to avoid clogging and subsequent disease.

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mitoCPR - a surveillance pathway that protects mitochondria in response to mitochondrial import stress

Project description:mitoCPR - a surveillance pathway that protects mitochondria in response to mitochondrial import stress

| PRJNA421360 | ENA

mitoCPR - a surveillance pathway that protects mitochondria in response to mitochondrial import stress

Project description:mitoCPR - a surveillance pathway that protects mitochondria in response to mitochondrial import stress

| PRJNA379466 | ENA

Mitochondrial protein import stress augments alpha-synuclein aggregation and neurodegeneration independent of bioenergetics

Project description:Several genetic and environmental risk factors for Parkinson’s disease have been identified that converge on mitochondria as central elements in the disease process. However, the mechanisms by which mitochondrial dysfunction contributes to neurodegeneration remain incompletely understood. Non-bioenergetic pathways of the mitochondria are increasingly appreciated, but confounding bioenergetic defects are a major barrier to experimental validation. Here, we describe a novel bioenergetics-independent mechanism by which mild mitochondrial protein import stress augments neurodegeneration. We induced this mitochondrial protein import stress in an established mouse model of Parkinson’s disease expressing the A53T mutated form of human alpha-synuclein (SNCA). Mice with import stress in addition to the A53T mutation demonstrated increased size of SNCA aggregates, co-aggregation of mitochondrial preproteins with SNCA protein, worsened neurodegeneration and changes in gene expression, as determined by whole-transcriptome RNA-sequencing analysis of the forebrain (striatum), cerebellum, spinal cord, as well as heart and skeletal muscle.

2023-10-08 | GSE236975 | GEO

Inter-organellar and systemic survival responses to impaired mitochondrial matrix protein import in skeletal muscle

Project description:Mitochondrial functions are largely performed by proteins imported from cytosol. Impaired protein import in mitochondria affects the maintenance of intra-mitochondrial anabolic and energy metabolic pathways. It leads to cytosolic accumulation of mistargeted proteins and activation of cellular stress responses. To explore the communication between these mechanism in mammalian system, we targeted the co-chaperone of mitochondrial Hsp70, a GrpE Like protein 1 (Grpel1), in mice. We show that loss of protein import into mitochondrial matrix results in mitochondrial dysfunction, which triggers stress responses. The total shut down of mtHSP70 function by overall knockout of Grpel1 resulted in early embryonic lethality, and tamoxifen-induced skeletal muscle-specific knockout of Grpel1 caused rapid muscular atrophy. We show here, with transcriptomics analysis, that protein-import failure in mitochondria increased cellular proteotoxic stress due to mitochondrial dysfunction. As a control mechanism, it triggered adaptive stress responses, including unfolded protein responses and integrated stress responses. Metabolic profiling of skeletal muscle-specific knockout mice revealed amino acid and TCA cycle intermediates shuttle between serum and muscle.

2022-10-04 | GSE198540 | GEO

Profiling of mRNA localization of nuclear-encoded mitochondrial proteins in zebrafish.

Project description:Current evidence suggests that nuclear-encoded mitochondrial proteins can be locally translated at the mitochondrial surface and co-translationally or post-translationally imported into mitochondria. mRNA localization on the mitochondrial membrane, a prerequisite for localized translation, remains uncharacterized in higher eukaryotic organisms. We employed fractionation-sequencing to profile mitochondria-associated mRNAs in zebrafish larvae. Our transcriptome-wide analysis reveals the localization of mRNAs of only 12% of the nuclear-encoded mitochondrial proteins to the mitochondrial surface, which suggests that post-translational import is the dominant mode of protein import to mitochondria. Additionally, the mRNAs which were localized to the mitochondrial membrane consisted mostly of those encoding proteins involved in mitochondrial dynamics, suggesting their site-specific translation. Finally, we show that the loss of function of the MIA pathway responsible for the post-translational import of a subclass of mitochondrial proteins, triggers mitochondrial localization of mRNAs encoding proteins that are imported to mitochondria via other pathways. Thus, our study suggests that mRNA targeting and localized translation could be relevant in higher eukaryotes to combat stress conditions affecting mitochondrial biogenesis in general.

2023-10-28 | GSE160355 | GEO

Comparative analysis of transcripts from mia40-4int mutant and wild-type Saccharomyces cerevisiae strains quantified in RNA-seq experiment

Project description:The vast majority of the mitochondrial proteome originates from nuclear genes and is transported into the organelle after synthesis in the cytosol. Complex machineries, which maintain the specificity of protein import and sorting exist. Dysfunctions of mitochondrial protein sorting pathways result in diminishing specific substrate proteins, followed by systemic pathology of the organelle and organismal death. Cellular responses that are caused by slowdown in the transport of mitochondrial proteins are unknown. Here we have used RNA-seq transcription profiling of Saccharomyces cerevisiae to uncover the changes in the cellular transcriptome in the response to mitochondrial protein import dysfunction caused by mutation in the MIA40 gene. Mia40 is a key component of the mitochondrial intermembrane import and assembly (MIA) pathway. Mia40-4int mutant used in this study is not viable at high temperatures, while in the low, permissive temperature it expresses growth rate comparable to the wild-type strain. Even during the permissive temperature culture mutant cells are characterized by decreased accumulation of MIA substrate proteins. Thus permissive growth conditions were used in the present experiment to emphasise primary responses to mitochondrial protein import defect.

2015-07-31 | E-MTAB-3588 | biostudies-arrayexpress

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