Gli2 Accelerates Cardiac Progenitor Gene Expression During Mouse Embryonic Stem Cell Differentiation

Abstract

The Hedgehog (HH) signalling pathway and its primary transducer, GLI2, regulate cardiomyogenesis in vivo and in differentiating P19 embryonal carcinoma (EC) cells. To further assess the role of HH signalling during mouse embryonic stem (mES) cell differentiation, we studied the effects of GLI2 overexpression during mES cell differentiation. GLI2 overexpression resulted in temporal enhancement of cardiac progenitor genes, Mef2c and Nkx2-5, along with enhancement of Tbx5, Myhc6, and Myhc7 in day 6 differentiating mES cells. Mass spectrometric analysis of proteins that immunoprecipitate with GLI2 determined that GLI2 forms a complex with BRG1 during mES cell differentiation. Furthermore, modulation of HH signalling during P19 EC cell differentiation followed by chromatin immunoprecipitation with an anti-BRG1 antibody determined that HH signalling regulates BRG1 enrichment on Mef2c. Therefore, HH signalling accelerates cardiac progenitor gene expression during mES cell differentiation potentially by recruiting a chromatin remodelling factor to at least one cardiac progenitor gene.