The cellular signals controlling the formation of cardiomyocytes, vascular smooth muscle, and endothelial cells from stem cell-derived mesoderm are poorly understood. To identify these signals, a mouse embryonic stem cell (ESC)-based differentiation assay was screened against a small molecule library resulting in a 1,4-dihydropyridine inducer of type II TGF-β receptor (TGFBR2) degradation-1 (ITD-1). ITD analogs enhanced proteasomal degradation of TGFBR2, effectively clearing the receptor from the cell surface and selectively inhibiting intracellular signaling (IC50 ∼0.4-0.8 μM). ITD-1 was used to evaluate TGF-β involvement in mesoderm formation and cardiopoietic differentiation, which occur sequentially during early development, revealing an essential role in both processes in ESC cultures. ITD-1 selectively enhanced the differentiation of uncommitted mesoderm to cardiomyocytes, but not to vascular smooth muscle and endothelial cells. ITD-1 is a highly selective TGF-β inhibitor and reveals an unexpected role for TGF-β signaling in controlling cardiomyocyte differentiation from multipotent cardiovascular precursors. © 2012 Elsevier Inc.
Willems, E., Cabral-Teixeira, J., Schade, D., Cai, W., Reeves, P., Bushway, P. J., … Mercola, M. (2012). Small molecule-mediated TGF-β type II receptor degradation promotes cardiomyogenesis in embryonic stem cells. Cell Stem Cell, 11(2), 242–252. https://doi.org/10.1016/j.stem.2012.04.025