RNA interfering retinoblastoma-like protein 2 gene induces apoptosis of human cardiac stem cells mediated by DNA methyltransferase

AIM: Retinoblastoma-like protein 2 (Rbl-2) plays an important role in the cell proliferation and DNA methyltransferase (DNMT) may involve in the regulation of differentiation in embryonic stem cells. This study is to investigate the effect of knocking down Rbl-2 by specific siRNA on apoptosis in human cardiac stem cells.METHODS: The siRNA of Rbl-2 (siRbl-2) was transfected into human cardiac stem cells. The mRNA expression of Rbl-2 and DNMT-3B was detected by real-time RT-PCR 48 h after transfection. The DNMT-3B protein expression and the activation of caspase-3 were determined by Western-blotting. The cell apoptosis was analyzed by flow cytometry with annexin V-FITC/PI staining. RESULTS: Knocking down of Rbl-2 gene increased the expression of DNMT-3B in human cardiac stem cells, and induced cell apoptosis. Compared with negative control group, caspase-3 was activated and cleaved caspase-3 was increased in the stem cells transfected with siRbl-2. The cleaved caspase-3 accounted for more proportions of total caspase-3 in transfected cells than that in non-transfected cells (P<0.01). The apoptotic rate was also increased significantly in transfected group (P<0.01).CONCLUSION: Rbl-2 plays an important role in the regulation of survival and apoptosis in human cardiac stem cells. This regulatory mechanism may involve in epigenetic modification, which is mediated by DNMT.