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Mitochondrial respiration maintains autophagy to support stress resistance in quiescent cells

ABSTRACT: Mitochondrial oxidative phosphorylation (OXPHOS) generates ATP and is required for pyrimidine nucleotide synthesis during proliferation. In contrast, the role of OXPHOS in post-mitotic cells, beyond its contribution to ATP production, is less understood. Here, we show that in non-proliferating cells, OXPHOS ensures protection against oxidative stress by sustaining autophagy. Autophagy is suppressed and oxidative stress resistance is compromised in OXPHOS-deficient non-proliferating cells in vitro and in TFAM knockout mice in vivo, while attenuation of autophagy in OXPHOS-functional cells phenocopies the effects of OXPHOS deficiency. Mechanistically, the regulation of the autophagy / stress response by OXPHOS does not require changes in gene expression, AMPK/mTOR1/ULK1 signaling or NADH levels. Instead, OXPHOS maintains ROS levels to prevent activation of ATG4, a ROS-activated inhibitor of autophagy. We propose that protection against oxidative stress via the ROS-ATG4 axis is a novel function of mitochondrial respiration in non-proliferating cells that may have consequences for cancer therapy and beyond.

ORGANISM(S): Homo sapiens

PROVIDER: GSE146025 | GEO | 2022/01/07

REPOSITORIES: GEO

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Mitochondrial respiration is necessary to combat oxidative stress in quiescent cells

Project description:Mitochondrial oxidative phosphorylation (OXPHOS) makes ATP and supports biosynthesis during proliferation, but its role in non-proliferating cells, beyond ATP production, is less understood. Here we show that OXPHOS protects quiescent (but not proliferating) cells from oxidative stress. Using in vivo models of OXPHOS deficiency (whole body and endothelium-specific) we show that OXPHOS mediated resistance to ROS (i) maintains selectivity of ROS-based anticancer therapy by protecting normal tissues during treatment, and in quiescent endothelium (ii) ameliorates systemic LPS-induced inflammation and (iii) attenuates symptoms of the inflammatory bowel disease. ROS-resistance provided by OXPHOS is independent of its role in biosynthesis or NADH recycling. Instead, in quiescent cells OXPHOS constitutively generates low levels of endogenous ROS that support basal autophagic flux and protect from exogenous ROS challenge. Hence, during evolution cells acquired mitochondria to profit from oxidative metabolism, but also built in an OXPHOS-dependent mechanism to guard against the resulting oxidative stress.

2022-10-13 | PXD021376 | Pride

Protein Kinase / suppresses liver cancer by repressing autophagy and oxidative phosphorylation in hepatocytes [DH]

Project description:Oxidative stress plays a critical role in liver tissue damage and in hepatocellular carcinoma (HCC) initiation and progression. However, the mechanisms that regulate autophagy and metabolic reprogramming during the generation of reactive oxygen species (ROS), and how ROS promotes tumorigenesis, still need to be fully understood. We show that protein kinase C (PKC) / loss in hepatocytes promotes autophagy and oxidative phosphorylation. This results in ROS generation, which through NRF2 drives HCC cell autonomously and non-autonomously. Although PKC / promotes tumorigenesis in oncogene-driven cancer models, emerging evidence demonstrate that it is a tumor suppressor in more complex carcinogenic processes. Consistently, PKC / levels negatively correlate with HCC histological tumor grade, establishing this kinase as a tumor suppressor in liver cancer.

2020-06-30 | GSE147800 | GEO

Protein Kinase / suppresses liver cancer by repressing autophagy and oxidative phosphorylation in hepatocytes [RD]

Project description:Oxidative stress plays a critical role in liver tissue damage and in hepatocellular carcinoma (HCC) initiation and progression. However, the mechanisms that regulate autophagy and metabolic reprogramming during the generation of reactive oxygen species (ROS), and how ROS promotes tumorigenesis, still need to be fully understood. We show that protein kinase C (PKC) / loss in hepatocytes promotes autophagy and oxidative phosphorylation. This results in ROS generation, which through NRF2 drives HCC cell autonomously and non-autonomously. Although PKC/ promotes tumorigenesis in oncogene-driven cancer models, emerging evidence demonstrate that it is a tumor suppressor in more complex carcinogenic processes. Consistently, PKC / levels negatively correlate with HCC histological tumor grade, establishing this kinase as a tumor suppressor in liver cancer.

2020-06-30 | GSE147778 | GEO

Autophagy maintains metabolism and functional activity of a subset of aged hematopoietic stem cells [ERRBS]

Project description:Autophagy is critical for protecting HSCs from metabolic stress. Here, we used a genetic approach to inactivate autophagy in adult HSCs by deleting the Atg12 gene. We show that loss of autophagy causes accumulation of mitochondria and an oxidative phosphorylation (OXPHOS)-activated metabolic state, which drives accelerated myeloid differentiation likely through epigenetic deregulations rather than transcriptional changes, and impairs HSC self-renewal activity and regenerative potential.

2017-03-03 | GSE89338 | GEO

Non-canonical BIM-regulated energy metabolism determines drug-induced liver necrosis.

Project description:Paracetamol (acetaminophen, APAP) overdose severely damages mitochondria and triggers several apoptotic processes in hepatocytes, but the final outcome is fulminant necrotic cell death, resulting in acute liver failure and mortality. Here, we studied this switch of cell death modes and demonstrate a non-canonical role of the apoptosis-regulating BCL-2 homolog BIM/Bcl2l11 in promoting necrosis by regulating cellular bioenergetics. BIM deficiency enhanced total ATP production and shifted the bioenergetic profile towards glycolysis, resulting in persistent protection from APAP-induced liver injury. Modulation of glucose levels and deletion of mitofusins confirmed that severe APAP toxicity occurs only in cells dependent on oxidative phosphorylation. Glycolytic hepatocytes maintained elevated ATP levels and reduced ROS, which enabled lysosomal recycling of damaged mitochondria by mitophagy. The present study highlights how metabolism and bioenergetics affect drug-induced liver toxicity, and identifies BIM as important regulator of glycolysis, mitochondrial respiration, and oxidative stress signaling.

2023-09-08 | GSE242368 | GEO

K48/K63-linked polyubiquitination of ATG9A at K581/K838 by TRAF6 E3 ligase

Project description:Excessive generation and accumulation of highly reactive oxidizing molecules causes oxidative stress and oxidative damage to cellular components. Accumulating evidence indicates that autophagy diminishes oxidative damage in cells and maintains redox homeostasis by degrading and recycling intracellular damaged components. However, the molecular mechanisms underlying the activation of oxidative stress-mediated autophagic response remain elusive. Here we show that ubiquitin E3 ligase TNF receptor-associated factor 6 (TRAF6) and the deubiquitinase A20 coordinate to regulate ATG9A ubiquitination and autophagy activation in cells responding to oxidative stress. The reactive oxygen species (ROS)-dependent TRAF6-mediated non-proteolytic, K48/63-linked ubiquitination of ATG9A enhances its association with Beclin 1 and the assembly of class III phosphatidylinositol-3-kinase (PI3KC3/VPS34) UVRAG complex, thereby stimulating autophagy. Notably, depletion of ATG9A or expression of the ATG9A ubiquitination mutants markedly decreases ROS-induced VPS34 activation and autophagy. We further find that lipopolysaccharide (LPS)-induced ROS production also stimulates TRAF6-mediated ATG9A ubiquitination and enhances the assembly of the UVRAG-containing VPS34 complex in an ATG9A-dependent manner. Ablation of ATG9A causes aberrant TLR4 endosomal trafficking and decreased phosphorylation of IRF-3 in LPS-stimulated macrophages. Our findings provide important insight into how K48/K63-linked ubiquitination of ATG9A contributes to the regulation of oxidative stress-induced autophagy.

2022-02-24 | PXD030415 | Pride

Autophagy maintains metabolism and functional activity of a subset of aged hematopoietic stem cells [gene expression]

2017-03-03 | GSE81719 | GEO

Autophagy maintains metabolism and functional activity of a subset of aged hematopoietic stem cells [RRBS]

2017-03-03 | GSE81720 | GEO

Calcium signaling controls pathogenic Th17 cell-mediated inflammation by regulating mitochondrial metabolism

Project description:Pathogenic Th17 cells play an important role in many autoimmune and inflammatory diseases. Their function is dependent on signaling through the T cell receptor (TCR) and cytokines that activate the transcription factor signal transducer and activator of transcription 3 (STAT3). TCR engagement activates stromal interaction molecule 1 (STIM1) and calcium (Ca2+) influx through the Ca2+ release-activated Ca2+ (CRAC) channel. We here show that deletion of STIM1 and Ca2+ influx in T cells expressing a hyperactive form of STAT3 (STAT3C) attenuates pathogenic Th17 cell function and multiorgan inflammation associated with STAT3C expression. Deletion of STIM1 in pathogenic Th17 cells impairs the expression of nuclear encoded mitochondrial electron transport chain genes and oxidative phosphorylation (OXPHOS) but enhances reactive oxygen species (ROS) production. Deletion of STIM1 or inhibition of OXPHOS is associated with impaired Th17 cell function and a non-pathogenic Th17 gene expression signature. Our findings establish STIM1 and Ca2+ signals as a critical regulator of OXPHOS and oxidative stress in pathogenic Th17 cells and multiorgan inflammation.

2019-01-17 | GSE125204 | GEO

Transcriptomic analysis by array of reactivation of dihydroorotate dehydrogenase by respiration restores tumor growth of mitochondrial DNA-depleted cancer cells.

Project description:Tumor cells without mitochondrial DNA (mtDNA) reconstitute oxidative phosphorylation (OXPHOS) by acquiring host mitochondria from stromal cells, but the reasons why functional respiration is crucial for tumorigenesis remain unclear. To address this issue, we used time-resolved analysis of the initial stages of tumor formation by cells devoid of mtDNA and genetic manipulations of components of OXPHOS. We show that pyrimidine biosynthesis, supported by respiration-linked dihydroorotate dehydrogenase (DHODH), is strictly required to overcome cell cycle arrest, while mitochondrial ATP generation is dispensable for tumorigenesis.

2018-10-01 | E-MTAB-6150 | biostudies-arrayexpress

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