Overexpression of Myocardin-related transcription factor-A attenuated middle cerebral artery occlusion/reperfusion-induced apoptosis via the Mcl-1/Cyt C/cleaved caspase 3 pathway

To investigate the effect of Myocardin related transcription factor A(MRTF-A)on apoptosis induced by ischemic/reperfusion(I/R),middle cerebral artery occlusion/reperfusion(MCAO/R)in rats were applied to mimic I/R.The neurological deficit score,cerebral infarct size,cortical neuron apoptosis and cleaved caspase 3 level were evaluated to determine the effect and the level of apoptosis by TTC straining,terminal deoxynucleotidyl transferase dUTP nick end labeling(TUNEL)straining,Western blot and immunofuorescence staining.The myeloid cell leukemia-1(Mcl-1)expression,release of cytochrome C(Cyt C)and its colocalization with apoptotic pro-tease activating factor-1(Apaf-1)were analyzed by quantitative real-time PCR(qRT-PCR),Western blot,and immunofuorescence staining.The results showed that MRTF-A over-expression could decrease the neurological deficit score and reduce cerebral infarct size(P<0.01 versus Sham).In the MRTF-A-I/R group,TUNEL-positive cells and apoptosis ratio(%)(51.61±6.17%)were significantly decreased compared to the Neg-I/R group(76.45±8.77%)at 24 h reperfusion.Meanwhile,the cleaved caspase 3 expression revealed a similar trend while the expression of Mcl-1 was the opposite.Moreover,MRTF-A overexpression significantly enhanced Mcl-1 fAuorescence intensity,which up-regulated the mRNA and protein level(P<0.05or P<0.01 versus Neg-I/R).Furthermore,MRTF-A overexpression markedly inhibited the release of Cyt C,and decreased the colocalization with Apaf-1 in the cytoplasm(P<0.05 or P<0.01.versus Neg-I/R).All the data indicated that MRTF-A overexpression could improve the neu-rological function against cerebral I/R-induced apoptosis since underlying mechanism might be involved in the Mc-1/Cyt C/cleaved caspase 3 signaling pathway.