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Epigenetic dysregulation of the Drp1 binding partners MiD49 and MiD51 increases mitotic mitochondrial fission and promotes pulmonary arterial hypertension: mechanism and therapeutic implications

ABSTRACT: Mitotic fission is increased in hyperproliferative, apoptosis-resistant diseases, such as pulmonary arterial hypertension (PAH). PAH’s fissogenic phenotype includes activation of the fission mediator, dynamin related protein 1 (Drp1), which must complex with its adaptor proteins to cause fission. Drp1-induced fission has been therapeutically targeted in experimental PAH. Here we examine the role of two recently discovered, poorly understood, Drp1 adapter proteins, mitochondrial dynamics protein of 49 and 51 kDa (MiD49 and MiD51) in normal vascular cells and explore the role of their dysregulation in the pathogenesis of PAH. MiDs are increased in PAH PASMC. This accelerates Drp1-mediated mitotic fission, which increases cell proliferation and decreases apoptosis. Silencing MiDs (but not Fis1 or MFF) promotes mitochondrial fusion and G1-phase cell cycle arrest through an ERK1/2 and CDK4-dependent mechanism. Augmenting MiDs in normal cells causes fission and recapitulates the PAH phenotype. MiD upregulation results from decreased microRNA-34a-3p (miR-34a-3p) expression. Circulatory miR34a-3p expression is decreased in PAH patients as well as in preclinical models of PAH. Silencing MiDs or augmenting miR-34a-3p regresses experimental PAH. We used microarrays to identify differences in miR expression in pulmonary artery smooth muscle cells (PASMC) taken from either pulmonary arterial hypertension patients or healthy controls

ORGANISM(S): synthetic construct Homo sapiens

PROVIDER: GSE108707 | GEO | 2018/01/31

REPOSITORIES: GEO

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Project description:NFU1 is an iron-sulfur (Fe-S) scaffold protein, involved in Fe-S assembly and transfer to a range of mitochondrial metalloproteins. Patients with the NFU1G208C mutation develop pulmonary arterial hypertension (PAH) with 70% penetrance. Rats with NFU1G206C homozygous mutation demonstrated the PAH phenotype showing increased pulmonary vasculature remodeling, right ventricular (RV) hypertrophy, and RV pressure. In the present study, we discovered phenotypic metabolic changes in pulmonary arterial smooth muscle cells (PASMC) from NFU1G206C homozygous mutant rats associated with alterations in the mitochondrial proteome. Quantitative analysis of the mitochondrial proteome showed significant changes in the abundance of 208 proteins involved in various metabolic and antioxidant functions in response to the NFU1 mutation. Our data indicates that the NFU1G206C homozygous mutant rats have decreased expression of complex I and II, which are known to depend on iron-sulfur clusters, and increased expression of complexes III to V, accompanied with a significant decrease in mitochondrial function, pyruvate dehydrogenase (PDH) activity and amplified glycolysis and anabolism in PASMC. The NFU1 mutation produced a dysregulated antioxidant system in the mitochondria which leads to increased levels of reactive oxygen species. Due to alterations in apoptosis regulating proteins, the NFU1G206C cells were found to exhibit high proliferation rates and resistance to apoptosis as compared with the wild type (WT). Finally, the NFU1G206C mitochondrial proteome showed significant abundance changes in proteins that regulate fatty acid (FA) metabolism and exhibited increased FA oxidation compared to WT, suggesting increased FA oxidation compensates for the decreased PDH activity. In conclusion, our data indicates that the NFU1G206C mutation induces a metabolic shift in the PASMC, which results in a hyper-proliferative and apoptosis resistant phenotype and presents a novel cellular model to study PAH.