1miR-23a-mediated PGC-Iα and GJA1 downregulation contributed to E2 deficiency-associated myocardial structural and electrical remodeling

Aim It is well known that menopause could worsen age-related ventricular concentric remodeling and increased incidence of arrhythmias following estrogen （E2） deficiency. However, the underlying mechanisms of such phenomena are not fully understood. Mitochondria, as the ＇cellular power station＇ of hearts, play an impor- tant role in maintaining normal cardiac function and structure. Therefore, the present study aims to investigate whether mitochondrial compromise and gap junction impairment induced by miR-23a is responsible for E2 deficien- cy associated structural and electrical remodeling. Results： We found mitochondrial structural damages and respira- tory function impairment in myocardium of both postmenopausal and OVX mice and E2 supplement reversed mito- chondrial dysfunction in OVX mice, suggesting that E2 deficiency could induce mitochondrial compromise in the lar remodeling, which can be regulated via MicroRNAs （miRNAs）-dependent mechanism. We recently identified Asymmetric dimethylarginine （ADMA） positively correlates to vascular remodeling-based diseases. Here, we hy- pothesized that ADMA induces SMC phenotypic change via a miRNA-dependent mechanism. Methods and Results Microarray analysis enabled the identification of 7 deregulated microRNAs in ADMA-treated human aortic artery smooth muscle cells （hASMCs）. miR-182 was validated by real-time-PCR. Isobaric tags for relative and absolute quantitation （iTRAQ） based analysis of the hASMC proteome revealed that transfection of an miR-182 inhibitor sig- nificantly increased myeloid-associated differentiation marker （MYADM）, which was verified using Western blot and reporter activity quantization with the MYADM 3＇-UTR dual-luciferase reporter system, miR-182 knockdown further repressed Sprouty2 and enhanced MYADM, leading to ERIC/MAP kinase-dependent and MYADM-depend- ent hASMC phenotypic change including proliferation, migration and differentiation marker gene expression change. In vivo, adeno-miR-182 markedly suppressed carotid neointimal formation by using balloon-injured rat carotid artery model, specifically via decreased MYADM expression. Atherosclerotic lesions from patients with high ADMA plas- ma levels exhibited decreased miR-182 expression levels and elevated MYADM expression levels. In patients with coronary heart disease （n- 164）, the miR-182 expression level in plasma was negatively correlated with the plas- ma ADMA levels. Conclusions miR-182 is a novel SMC phenotypic modulator by targeting MYADM and can be a potential therapeutic target combating vascular remodeling-associated diseases. Reduced plasma miR-182 levels might be a new predictor of high vascular remodeling risk especially in patient with coronary heart disease.