Synergistic Induction Of MiR-126by Hypoxia And HDAC Inhibitors In Cardiac Myocytes

Histone acetyltransferase (histone acetykransferase, HAT) and histone acetylation enzyme (histone deacetylase, HDAC) regulates level of histone acetylation via deacetylation or acetylation of histone terminal amino acid residues. HDAC inhibitors increasing level of histone acetylation to regulate gene expression.studies have shown that the treatment for hypertrophic cardiomyopathy or heart failure, but its protective mechanism has not yet been clearly. Micro-RNA126(miR-126) is an endothelial cell specific micro-RNA, In heart tissue activated cells regulate protein kinase (extracellular regulated protein kinases Erk) and protein kinase B (Protain Akt kinase B), and increasing pro-angiogenic signaling. miR-126is involved in the HDAC inhibitors to protect the ischemic heart, has not been clear.Purpose:To explore the function and mechanism of HDAC inhibitors in hypertrophic cardiomyopathy and heart failure by study the Synergistic Induction of miR-126with Hypoxia and HDAC Inhibitors in Cardiac Myocytes.Method:Cardiac myocytes culture and exposure to hypoxia, Cells were pretreated for1h with TSA (100nmol/L) or DMSO. Total RNA was isolated from myocardial tissue using Trizol reagent.A quantitative real-time reverse transcription-PCR assay from Ambion was used to quantify miR-126expression. The downstream effectors of miR-126include ERK and Akt were Tested with Western Blot. Total HAT activity and total HDAC activity were quantified using commercially available kits. Cells with or without lentivirus infection and test the same index to make sure that Hypoxia and HDAC inhibition synergistically induce miR-126expression. In vivo the heart of TSA treatment and a similar mouse model of acute myocardial infarction were tested the infarct size and the miR-126expression.Result:We found that HDAC and HAT activity under acute hypoxia, Hypoxia and HDAC inhibition synergistically induce miR-126expression,as the same with The downstream effectors of miR-126include ERK and Akt.And Hypoxia/TSA-induction of ERK and Akt is regulated by miR-126. MiR-126expression was increased1.8±0.2-fold (p<0.05) after1h of hypoxic exposure and this was further enhanced to3.2±0.3-fold (p<0.01) by simultaneously blocking HDAC with the pan-HDAC inhibitor Tricostatin A (TSA). TSA alone did not increase miR-126. In parallel, hypoxia and TSA synergistically increased pp-ERK and p-Akt without effecting VEGF-A level. Knockdown of miR-126with si-RNA eliminated inductions of pp-ERK and p-Akt by hypoxia, whereas miR-126overexpression mimicked hypoxia and amplified pp-ERK and p-Akt in parallel with miR-126.Conclusion:Hypoxia and HDAC inhibition synergistically induce miR-126expression, suggest that miR-126has a mechanistic role in the protective actions of HDAC inhibitors during late stage hypertrophy.