Peroxisome proliferator-activated receptor alpha is involved in cardiomyocyte differentiation of murine embryonic stem cells in vitro.

Peroxisome proliferator-activated receptor alpha (PPARalpha) plays a key role in the transcriptional regulation of genes involved in cellular lipid and energy metabolism, which is abundantly expressed in tissues with high energy demand, including the mammalian heart. Although multiple roles for PPARalpha in adult cardiomyocytes have been proposed, little is known about the significance of PPARalpha in early differentiation of cardiomyocytes. To address this issue, murine embryonic stem (ES) cells were adopted in this study since they would differentiate in vitro into cardiomyocytes that faithfully recapitulated cardiomyocyte differentiation in vivo. As determined by semi-quantitative RT-PCR and Western-blot, both PPARalpha and its coactivatior PGC-1alpha were increased during cardiomyocyte differentiation. A positive correlation between PPARalpha and Troponin-T expression was also observed by immunofluorescence in early differentiation. Application of PPARalpha antagonist GW6471 prevented cardiomyocyte differentiation as indicated by reduced expression of cardiac specific genes (alpha-MHC, MLC2v) and cardiac sarcomeric proteins (alpha-Actinin, Troponin-T). However, gene expression of cardiac specific transcription factors (GATA4, Nkx2.5, and MEF2C) remained unchanged. Moreover, cardiomyocyte differentiation of EBs could be efficiently stimulated by WY14643 treatment, the specific agonist of PPARalpha. Taken together, these results suggested a facilitating role of PPARalpha in cardiomyocyte differentiation of murine ES cells in vitro.