Cardiac growth factors.

The role of polypeptide growth factors in cardiovascular ontogeny, function, and pathologic states is poorly understood. Recent investigations demonstrate that the myocardium produces both known and novel growth factors, which are highly regulated during development and disease, and have suggested that peptide growth factors may direct cardiac organogenesis and adaptation. Aspects of growth factor production, transduction, and action in myocardium are distinct to the cardiac muscle lineage and were not foreseen from results in simpler systems. Transforming growth factor beta 1 and fibroblast growth factors (FGFs) selectively up-regulate an ensemble of tissue-specific genes associated with the fetal myocardium. One of these, encoding the skeletal muscle isoform of alpha-actin, is activated by basic FGF yet is inhibited by acidic FGF. A serum response element of this gene is selectively induced, in cardiac myocytes, by basic FGF but not acidic FGF. Thus, cardiac muscle is an especially intriguing model for the analysis of growth factor signalling pathways that control differentiated gene transcription.