Transforming Growth Factor Beta2Increases Heart Development-related Transcription Factors Through Histone H3Hyperacetylation In H9C2Cells

ObjectiveTransforming growth factor beta2(TGF-β2) plays an important role inheart development, however, the underlying mechanism is not clear. Thepresent study is to investigate the effect of TGF-β2on histone3acetylationand its role in regulating the expression of heart development-relatedtranscription factors and related mechanism.MethodsMyocardial cell H9C2were cultured in vitro and treated with TGF-β2at concentrations of1.25μg/L,2.5μg/L,5μg/L,10μg/L,20μg/L. Invertedphase contrast microscope(IPCM) was applied to observe cell morphologyand cell-counting at different timepoints (post-intervention12h,24h,48hand72h) and draw the cell-growth curve. Quantitative real-time PCR assaywas used to select suitable intervention concentration of TGF-β2bycomparing the mRNA expressions of Mef2c and GATA4. The acetylation level of histone H3was detected using Western blot. HATs ActivityColorimetric Assay Kit was used to measure the level of HATs activity. And,levels of H3acetylation in promoter regions of Mef2c and GATA4weremeasured by chromatin immunoprecipitation（ChIP）Real-time PCRassaies.ResultsThe proliferation activity of myocardial cell H9C2was enhance aftertreatment of H9C2cells with TGF-β2at concentration of5μg/L（p<0.05）. The up-regulation of mRNA expressions of Mef2c and GATA4byTGF-β2was in a dose dependent manner, and reached peak at the dose of5μg/L, increased by1.8folds and2.3folds, respectively compared to thecontrol’s（p <0.05）. The treatment of TGF-β2increased acetylation level ofhistone H3by4-fold, as well as the HATs activities by1.34-fold（p <0.05）.The intervention of TGF-β2increased so well the levels of histone H3acetylation in the promoter regions of Mef2c and GATA4by2.56-and2.16-fold, respectively（p <0.05）.ConclusionTGF-β2could enhance the proliferative ablities of myocardial cellH9C2at the concentration of5μg/L in vitro, and increase the level of histoneH3acetylation and then up-regulate the expressions of Mef2c and GATA4. These findings reveal that the effect of TGF-β2on heartdevelopment-related genes may be mediated by histone acetylaion,suggesting a new mechanism during cardiogenesis.