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Proteomic profiling of brain mitochondrial-derived vesicles

ABSTRACT: The generation of mitochondrial-derived vesicles (MDVs) is implicated in a plethora of vital cell functions, from mitochondrial quality control to peroxisomal biogenesis. The discovery of distinct subtypes of MDVs has revealed the selective inclusion of mitochondrial cargo in response to varying stimuli. However, the true scope and variety of MDVs is currently unclear, and unbiased approaches have yet to be used to understand their biology. Furthermore, as mitochondrial dysfunction has been implicated in many neurodegenerative diseases, it is essential to understand MDV pathways in the nervous system. To address this, we sought to identify the cargo in brain MDVs. We used an in vitro budding assay and proteomic approach to identify proteins selectively enriched in MDVs. 72 proteins were identified as MDV enriched, of which 31% were OXPHOS proteins. Interestingly, the OXPHOS proteins localized to specific modules of the respiratory complexes, hinting at the inclusion of sub-assemblies in MDVs. Small TIM chaperones were also highly enriched in MDVs, linking mitochondrial chaperone-mediated protein transport to MDV formation. As the two Parkinson’s disease genes PINK1 and Parkin have been previously implicated in MDV biogenesis in response to oxidative stress, we compared the MDV proteomes from the brains of wild-type mice with those of PINK1-/- and Parkin-/- mice. No significant difference was found, suggesting that PINK1- and Parkin-dependent MDVs make up a small proportion of all MDVs in the brain. Our findings demonstrate a previously uncovered landscape of MDV complexity and provide a foundation from which to discover further novel MDV functions.

INSTRUMENT(S): timsTOF Pro

ORGANISM(S): Mus Musculus (mouse)

TISSUE(S): Brain

SUBMITTER: Rosalind Roberts

LAB HEAD: Edward A Fon

PROVIDER: PXD020197 | Pride | 2020-09-07

REPOSITORIES: Pride

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Project description:Mitochondria share attributes of vesicular transport with their bacterial ancestors given their ability to form mitochondrial-derived vesicles (MDVs). MDV formation enhances with stress and has been explored for its potential role in mitochondrial-directed cellular and extracellular signalling. Although the fate of MDVs as a form of mitochondrial quality control and cellular communication has been suggested, the proteomic cargo has remained mostly undefined. In this study, we strategically used an in vitro MDV budding/reconstitution assay, following graded oxidative stress on cardiac mitochondria, to identify and characterize the MDV proteome. Our results confirmed previously identified cardiac MDV markers while also revealing a complete map of the MDV proteome, paving the way to understanding the likely roles for MDV release. MDV cargo was particularly enriched with mitochondrial matrix and inner membrane proteins. Oxidative stress vulnerability of proteins directed the cargo loading, which was enhanced by antimycin A (Ant-A). Among OXPHOS complexes, complexes III and V were found to be Ant-A-sensitive. Proteins from metabolic pathways such as TCA cycle, amino acid, fatty acid and aldehyde metabolism, Fe-S cluster, antioxidant response proteins, autophagy and vesicular processes were also found to be Ant-A sensitive. Intriguingly, proteins containing hyper-reactive cysteine residues (HRCR), which act as redox switches in regulating metabolic pathways, including professional redox enzymes and those that are involved in iron metabolism were found to be loaded in MDVs with Ant-A sensitivity. Lastly, we estimated a possible significant contribution of MDVs to the formation of extracellular vesicles, which can serve as an indicator of mitochondrial stress. In conclusion, using graded oxidative stress, our study gives a layout of MDV proteomics signature, delineates the cargo selectivity and hints at the potential of MDVs and the novel protein cargo identified to serve as vital biomarkers during mitochondrial stress and its related pathologies.

Project description:This study aims to investigate the role and mechanism of DEK in asthmatic airway inflammation and in regulating PTEN-induced putative kinase 1 (PINK1)-Parkin mediated mitophagy, NLRP3 (NOD-like receptor family pyrin domain containing 3) inflammasome activation, and apoptosis. We found that recombinant DEK protein (rmDEK) promoted eosinophils recruitment, mitochondrial fragmentation, and outer membrane 20 (TOM20) and LC3 co-localization representing mitophagosomes in bronchoalveolar lavage fluid (BALF) in house dust mite (HDM) induced-asthma. rmDEK also reduced co-localization of mitochondrial fusion protein mitofusin1 (MFN1) and mitochondria, and the protein level of manganese superoxide dismutase (MnSOD), enhanced microtubule-associated protein1 light chain 3 (LC3) and voltage-dependent anion channels (VDAC) co-localization which also represent the mitophagosomes in airway epithelial cells, furthermore, increased dynamin-related protein 1 (DRP1) expression, PINK1-Parkin-mediated mitophagy, NLRP3 inflammasome activation, and apoptosis. In the DEK knockout mice, HDM induced asthmatic airway inflammation, MnSOD, PINK1-Parkin protein level, Parkin mediated mitophagy characterized by LC3 and Parkin co-localization in the airways, ROS generation, NLRP3 inflammation and apoptosis were fully reversed. Similar effects of rmDEK were also observed in the BEAS-2B cells, which were rescued by the autophagy inhibitor 3-MA. Moreover, DEK silencing diminished the Parkin, LC3, DRP1 translocation to mitochondria; as well as mitochondrial ROS; TOM20 and mitochondrial DNA mediated mitochondrial oxidative damage. ChIP-sequence analysis showed that DEK was enriched on the AAA domain-containing protein 3A (ATAD3A) promoter and could positively regulate ATAD3A expression. Additionally, ATAD3A was highly expressed in HDM-induced asthma models. Furthermore, ATAD3A interacted with DRP1, and knockdown of ATAD3A could down-regulate DRP1 and mitochondrial oxidative damage. Conclusively, DEK deficiency alleviates airway inflammation in asthma by down-regulating PINK1-Parkin mitophagy, NLRP3 inflammasome activation, and apoptosis. The mechanism may be through the DEK/ATAD3A/DRP1 signaling axis. Our findings may provide new potential therapeutic targets for asthma treatment.

Project description:Loss-of-function mutations in the parkin gene can cause early onset Parkinson’s disease, a movement disorder resulting from the selective degeneration of dopaminergic neurons in the basal ganglia. Analogously, movement deficits and loss of a subset of dopaminergic neurons are observed in Drosophila melanogaster homozygous for null mutations in parkin. Parkin is an E3 ubiquitin ligase that functions with the mitochondrial localized serine/threonine kinase PINK1 in a pathway required to maintain mitochondrial integrity. We previously established that the PINK1/Parkin pathway functions in Drosophila dopaminergic and cholinergic neurons to maintain mitochondrial membrane potential. However, the mechanisms through which the PINK/Parkin pathway selectively impacts dopaminergic neuron survival remains unclear, as do the mechanisms that lead to the selective vulnerability of dopaminergic neurons in Parkinson’s disease. Because the transcriptome of a cell determines its identity we hypothesized that knowledge of the transcriptional alterations that occur in dopaminergic neurons isolated from parkin null Drosophila would provide insight into the mystery of selective vulnerability in Parkinson's disease. Results: To test our hypothesis we measured the transcriptome of dopaminergic and cholinergic neurons isolated from isogenic heterozygous and homozygous parkin null mutants using a novel flow cytometry-based method we developed. Computational analysis and experimental confirmation demonstrate that our method allows for the successful expression analysis of defined neural subsets from the Drosophila brain. In addition, our dataset implicates iron handling and dopamine signaling as being significantly dysregulated in parkin null dopaminergic neurons. Conclusions: Our flow cytometry-based method allows for the isolation and microarray analysis of neuronal subsets from the adult Drosophila brain. Our microarray analyses implicate iron handling and dopamine metabolism as contributing factors in the etiology of parkin-associated early onset Parkinson’s disease. Here we provide a novel dataset that may serve as a foundation for subsequent functional analyses of the pathways underlying neuronal selective vulnerability in Parkinson's disease.

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.

			Action	DRS
	MDVExpDesign.xlsx	Xlsx
	Modificationdata.zip	Other
	PINK1colonydata.zip	Other
	Parkincolonydata.zip	Other
	Trempe_10_Slot1-19_1_3358.d.zip	Other

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Proteomic profiling of brain mitochondrial-derived vesicles

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