Sense and antisense TGF beta 3 mRNA levels correlate with cardiac valve induction.

The formation of the valves in the heart is a spatially and temporally controlled process. A tissue interaction between the endothelium and its adjacent myocardium initiates the transformation of the endothelium into the mesenchymal precursors of the heart valve. One or more of the molecules implicated as critical for valve formation are members of the transforming growth factor beta family of molecules. Presented here is a spatial and temporal analysis of TGF beta 2 and TGF beta 3 in the chick heart during valve formation. We show that TGF beta 3 mRNA is concentrated in AV canal tissue where valve formation will occur, consistent with previous observations that TGF beta 3 production is critical during valve formation. Additionally, an RNA complementary to TGF beta 3 encoding mRNA is present in the heart. The temporally controlled appearance of RNA complementary to TGF beta 3 suggests that this molecule may play a role in the regulation of TGF beta 3 production in the heart.