Small Molecule-Mediated TGF-β Type II Receptor Degradation Promotes Cardiomyogenesis in Embryonic Stem Cells

SummaryThe 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.

Graphical AbstractFigure optionsDownload full-size imageDownload high-quality image (277 K)Download as PowerPoint slideHighlights► Highly selective small molecule inhibitor of TGF-β degrades TGFBR2 specifically ► TGF-β signaling is essential for mesoderm establishment in mouse ESCs ► Degradation of TGFBR2 promotes cardiac fate specifically in mouse and human ESCs ► Chemical biology approach to correlate or separate biological activities