MicroRNA-22-3p Regulates the Expression of Kruppel-like Factor 6 to Affect the Cardiomyocyte-like Differentiation of Bone Marrow Mesenchymal Stem Cell / 中国医学科学院学报

Objective To explore the effect of microRNA-22-3p (miR-22-3p) regulating the expression of Kruppel-like factor 6 (KLF6) on the cardiomyocyte-like differentiation of bone marrow mesenchymal stem cell (BMSC). Methods Rat BMSC was isolated and cultured,and the third-generation BMSC was divided into a control group,a 5-azacytidine(5-AZA)group,a mimics-NC group,a miR-22-3p mimics group,a miR-22-3p mimics+pcDNA group,and a miR-22-3p mimics+pcDNA-KLF6 group.Real-time fluorescent quantitative PCR (qRT-PCR) was carried out to determine the expression of miR-22-3p and KLF6 in cells.Immunofluorescence staining was employed to detect the expression of Desmin,cardiac troponin T (cTnT),and connexin 43 (Cx43).Western blotting was employed to determine the protein levels of cTnT,Cx43,Desmin,and KLF6,and flow cytometry to detect the apoptosis of BMSC.The targeting relationship between miR-22-3p and KLF6 was analyzed by dual luciferase reporter gene assay. Results Compared with the control group,5-AZA up-regulated the expression of miR-22-3p (q=7.971,P<0.001),Desmin (q=7.876,P<0.001),cTnT (q=10.272,P<0.001),and Cx43 (q=6.256,P<0.001),increased the apoptosis rate of BMSC (q=12.708,P<0.001),and down-regulated the mRNA (q=20.850,P<0.001) and protein (q=11.080,P<0.001) levels of KLF6.Compared with the 5-AZA group and the mimics-NC group,miR-22-3p mimics up-regulated the expression of miR-22-3p (q=3.591,P<0.001;q=11.650,P<0.001),Desmin (q=5.975,P<0.001;q=13.579,P<0.001),cTnT (q=7.133,P<0.001;q=17.548,P<0.001),and Cx43 (q=4.571,P=0.037;q=11.068,P<0.001),and down-regulated the mRNA (q=7.384,P<0.001;q=28.234,P<0.001) and protein (q=4.594,P=0.036;q=15.945,P<0.001) levels of KLF6.The apoptosis rate of miR-22-3p mimics group was lower than that of 5-AZA group (q=8.216,P<0.001).Compared with the miR-22-3p mimics+pcDNA group,miR-22-3p mimics+pcDNA-KLF6 up-regulated the mRNA(q=23.891,P<0.001) and protein(q=13.378,P<0.001)levels of KLF6,down-regulated the expression of Desmin (q=9.505,P<0.001),cTnT (q=10.985,P<0.001),and Cx43 (q=8.301,P<0.001),and increased the apoptosis rate (q=4.713,P=0.029).The dual luciferase reporter gene experiment demonstrated that KLF6 was a potential target gene of miR-22-3p. Conclusion MiR-22-3p promotes cardiomyocyte-like differentiation of BMSC by inhibiting the expression of KLF6.

Inhibitory effects of Pin1 silencing by siRNA on apoptosis of H9c2 cardiomyo-cytes induced by hypoxia/reoxygenation / 中国免疫学杂志

Objective:Pin1 plays an important role in the pathogenesis of cardiovascular disease,our study aims to investigate the effects of Pin1 silencing by siRNA on H9c2 apoptosis induced by hypoxia/reoxygenation.Methods:H9c2 cells were cultured and subjected to a hypoxia/reoxygenation (H/R) condition in vitro,mimicking ischemic/reperfusion injury in vivo.The mRNA and protein expression of Pin1 were detected by RT-qPCR and Western blot.H9c2 cells were divided into control group,H/R group,H/R+Pin1 siRNA group,H/R+scramble siRNA group.MTT and flow cytometry with Annexin V-FITC/PI staining were respectively performed to detect cell viability and apoptosis.The expression of Bax and Bcl-2 were measured by Western blot.The activity of Caspase-3 was detected by automatic biochemistry analytic instrument.Results:The mRNA and protein levels of Pin1 were highly expressed in the cells of H/R group.Transfection with Pin1 siRNA strikingly inhibited the expression of Pin1.Compared with H/R group,Pin1 siRNA markedly increased cell viability,decreased the cell apoptosis and the Caspase-3 activity.Furthermore,the increased Bcl-2,decreased Bax and the ratio of Bcl-2 to Bax were observed in Pin1 siRNA group (P<0.05) compared with H/R group.Conclusion:Downregulation of Pin1 protects hypoxia/reoxygenation-injured H9c2 cells from apoptosis,which is possibly through the upregulation of Bcl-2 and downregulation of Bax and Caspase-3 activity.