Mitochondrial transfer mediates endothelial cell engraftment through mitophagy
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE255798 | GEO | 2024/02/15
REPOSITORIES: GEO
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Project description:Clearance of damaged mitochondria via mitophagy is crucial for cellular homeostasis. While the role of ubiquitin (Ub) ligase PARKIN in mitophagy has been extensively studied, increasing evidence suggests the existence of PARKIN-independent mitophagy in highly metabolically active organs such as the heart. Here, we identify a crucial role for Cullin-RING Ub ligase 5 (CRL5) in basal mitochondrial turnover in cardiomyocytes. CRL5 is a multi-subunit Ub ligase comprised by the catalytic RING box protein RBX2 (also known as SAG), scaffold protein Cullin 5 (CUL5), and a substrate-recognizing receptor. Analysis of the mitochondrial outer membrane-interacting proteome uncovered a robust association of CRLs with mitochondria. Subcellular fractionation, immunostaining, and immunogold electron microscopy established that RBX2 and Cul5, two core components of CRL5, localizes to mitochondria. Depletion of RBX2 inhibited mitochondrial ubiquitination and turnover, impaired mitochondrial membrane potential and respiration, and increased cell death in cardiomyocytes. In vivo, deletion of the Rbx2 gene in adult mouse hearts suppressed mitophagic activity, provoked accumulation of damaged mitochondria in the myocardium, and disrupted myocardial metabolism, leading to rapid development of dilated cardiomyopathy and heart failure. Similarly, ablation of RBX2 in the developing heart resulted in dilated cardiomyopathy and heart failure. Notably, the action of RBX2 in mitochondria is not dependent on PARKIN, and PARKIN gene deletion had no impact on the onset and progression of cardiomyopathy in RBX2-deficient hearts. Furthermore, RBX2 controls the stability of PINK1 in mitochondria. Proteomics and biochemical analyses further revealed a global impact of RBX2 deficiency on the mitochondrial proteome and identified several mitochondrial proteins as its putative substrates. These findings identify RBX2-CRL5 as a mitochondrial Ub ligase that controls mitophagy under physiological conditions in a PARKIN-independent, PINK1-dependent manner, thereby regulating cardiac homeostasis.
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Project description:Mitochondria are vital for cellular energy supply and intracellular signaling after stress. Here, we aimed to investigate how mitochondria respond to acute DNA damage with respect to mitophagy, which is an important mitochondrial quality control process. Our results show that mitophagy increases after DNA damage in primary fibroblasts, murine neurons, and C. elegans neurons. Our results indicate that modulation of mitophagy after DNA damage is independent of the type of DNA damage stimuli used and that the protein Spata18 is an important player in this process. Knockdown of Spata18 suppresses mitophagy, disturbs mitochondrial Ca2+ homeostasis, affects ATP production, and attenuates DNA repair. Importantly, mitophagy after DNA damage is a vital cellular response to maintain mitochondrial functions and DNA repair.
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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.
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Project description:During early post-natal stage, cardiomyocytes undergo dramatic structural, metabolic, electrophysiological and cell cycle alterations towards maturation. Among them, the metabolic shift from carbohydrates to fatty acids metabolism is achieved along with mitochondrial biogenesis, dynamic switch and mitophagy. However, the regulatory mechanisms responsible for coordinated mitochondrial dynamics and mitophagy in mitochondrial maturation remain unclear. Here, we found that ablation of PDK1 in post-natal cardiomyocytes impairs mitochondrial maturation and metabolism, characterizing by arrest of mitochondria in neonatal stage, low levels of a subset of fatty acids and acylcarnitines. In addition, loss of PDK1 results in dysregulated mitochondrial dynamics and mitophagy. An imbalance of the AMPK-mTOR pathway and reduced phosphorylation of PDK1 substrates, including PKA and PKC family members, are observed. These results demonstrated that PDK1 ensures mitochondrial maturation and metabolic shift through kinase-dependent substrate phosphorylation and maintenance of the AMPK-mTOR axis to coordinate mitochondrial dynamics and mitophagy.
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Project description:Bladder cancer is one of the most common malignancy in the urinary tract with high recurrence and drug resistance in clinics. Alternative treatments from existing drugs might be a promising strategy. Nitazoxanide (NTZ), an FDA-approved antiprotozoal drug, has got increasingly noticed because of its favorable safety profile and antitumor potential, yet the effects in bladder cancer and underlying mechanisms remain poorly understood. Herein, we find that NTZ induces mitochondrial damage and mitophagy initiation through PINK1-generated phospho-ubiquitin(pS65-Ub) and autophagy receptor-mediated pathway even in the absence of Atg5/Beclin1. Meanwhile, NTZ inhibits lysosomal degradation activity, leading to mitophagy flux impairment at late stage. Mitochondrial reactive oxygen species (ROS) production is critical in this process, as eliminating ROS with N-acetylcysteine (NAC) efficiently inhibits PINK1 signaling-mediated mitophagy initiation and alleviates lysosomal dysfunction. Co-treatment with NTZ and autophagy inhibitor Chloroquine (CQ) to aggravate mitophagy flux impairment promotes NTZ-induced apoptosis, while alleviation of mitophagy flux impairment with ROS scavenger reduced cell death. Moreover, we also discover a similar signaling response in the 3D bladder tumor spheroid after NTZ exposure. In vivo study reveals a significant inhibition of orthotopic bladder tumors with no obvious systemic toxicity. Together, our results uncover the anti-tumor activities of NTZ with the involvement of ROS-mediated mitophagy modulation at different stages and demonstrate it as a potential drug candidate for fighting against bladder tumors.
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Project description:Metabolic dysfunction associated steatotic liver disease (MASLD) is characterized by a constant accumulation of lipids in the liver. This lipotoxicity in the liver is associated with dysregulation of the first step in lipid catabolism called beta oxidation in the mitochondrial matrix, eventually leading to mitochondrial dysfunction. To evaluate possible involvement of mitochondrial DNA methylation in this lipid metabolic dysfunction we investigated the functional metabolic effects of mitochondrial overexpression of CpG (MSssI) and GpC (MCviPI) DNA methyltransferases in relation to gene expression and (mito)epigenetic signatures. Overall, the results show that mitochondrial GpC and to a lesser extent CpG methylation increase bile acid metabolic gene expression, inducing cholestasis by mito-nuclear epigenetic reprogramming. Moreover, increased expression of metabolic nuclear receptors in both MSssI and MCviPI cells promote mitochondrial swelling and induce basal overactivation of mitochondrial respiration which favours lipid accumulation and metabolic-stress induced mitophagy and autophagy stress responses. Altogether GpC and CpG mitochondrial induce a metabolic challenging environment that is similar to mitochondrial dysfunction in the progression of MASLD.
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Project description:Metabolic dysfunction associated steatotic liver disease (MASLD) is characterized by a constant accumulation of lipids in the liver. This lipotoxicity in the liver is associated with dysregulation of the first step in lipid catabolism called beta oxidation in the mitochondrial matrix, eventually leading to mitochondrial dysfunction. To evaluate possible involvement of mitochondrial DNA methylation in this lipid metabolic dysfunction we investigated the functional metabolic effects of mitochondrial overexpression of CpG (MSssI) and GpC (MCviPI) DNA methyltransferases in relation to gene expression and (mito)epigenetic signatures. Overall, the results show that mitochondrial GpC and to a lesser extent CpG methylation increase bile acid metabolic gene expression, inducing cholestasis by mito-nuclear epigenetic reprogramming. Moreover, increased expression of metabolic nuclear receptors in both MSssI and MCviPI cells promote mitochondrial swelling and induce basal overactivation of mitochondrial respiration which favours lipid accumulation and metabolic-stress induced mitophagy and autophagy stress responses. Altogether GpC and CpG mitochondrial induce a metabolic challenging environment that is similar to mitochondrial dysfunction in the progression of MASLD.
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