Signaling pathways mediating cardiac myocyte gene expression in cardiogenic cells derived from mesenchymal stem cells

Abstract

[한글]

[영문]

Despite treatment of mesenchymal stem cells (MSCs) for cardiac repair, specific stimuli and signal pathways that may control cardiogenic differentiation remains to be completely defined. In cardiogenic cells (CGCs) derived from MSCs using PKC activator (PMA, phorbol 12-myristate 13-acetate), cardiac-specific signal pathways were investigated by various stimuli; i) MAPK pathway by platelet-derived growth factor (PDGF) and U0126 (MEK inhibitor), ii) PKB/Akt pathway by insulin growth factor (IGF), iii) Ca2+-related pathway by endothelin-1 (ET-1). In the mitogen activated protein kinase (MAPK), phosphorylation level of MEK and ERK1/2 was elevated each 2.5-fold and 1.5-fold by PDGF stimulation, respectively. And, CGCs treated with U0126 were down-regulated in phosphorylation of ERK1/2 about 6-fold compared to PDGF only. Stress-responsive MAPK family, namely, the c-Jun N-terminal kinases (JNKs) and the p38-MAPKs were analogous to cardiomyocytes in the phosphorylation level of PDGF treated CGCs about 92% and 99%, respectively. In PKB/Akt signaling pathway, phosphorylation level of Akt, mTOR (mammalian target of rapamycin) and 4E-BP (eIF4E binding protein) of CGCs by IGF were similar to those of cardiomyocytes. The lasting increase in Ca2+ of cytoplasm was reflected by fluo4-AM combined with intracellular Ca2+. In ET-1 stimulation, phosphorylation and activation of CaMKⅡ and calcineurin (CaN) were detected in CGCs by immunoblot and immunocytochemistry. These result demonstrate that gene expression of CGCs are likely to cardiomyocytes and it is assumed that these pathways function to influence the change of intracellular signaling when cardiogenic differentiation are progress.