A Nodal-to-TGF Cascade Exerts Biphasic Control Over Cardiopoiesis Short Communication

Rationale: The transforming growth factor- (TGF) family member Nodal promotes cardiogenesis, but the mechanism is unclear despite the relevance of TGF family proteins for myocardial remodeling and regeneration. Objective: To determine the function(s) of TGF family members during stem cell cardiogenesis. Methods and Results: Murine embryonic stem cells were engineered with a constitutively active human type I Nodal receptor (caACVR1b) to mimic activation by Nodal and found to secrete a paracrine signal that promotes cardiogenesis. Transcriptome and gain- and loss-of-function studies identified the factor as TGF2. Both Nodal and TGF induced early cardiogenic progenitors in embryonic stem cell cultures at day 0 to 2 of differentiation. However, Nodal expression declines by day 4 due to feedback inhibition, whereas TGF persists. At later stages (days 4–6), TGF suppresses the formation of cardiomyocytes from multipotent Kdr progenitors while promoting the differentiation of vascular smooth muscle and endothelial cells. Conclusions: Nodal induces TGF, and both stimulate the formation of multipotent cardiovascular Kdr progenitors. TGF, however, becomes uniquely responsible for controlling subsequent lineage segregation by stimulating vascular smooth muscle and endothelial lineages and simultaneously blocking cardiomyocyte differentiation. (Circ Res. 2012;111:876-881.)