Fibroblast growth factor-2 stimulates phospholipase Cβ in adult cardiomyocytes

Although fibroblast growth factor-2 (FGF-2) plays an important role in cardioprotection and growth, little is known about the signals triggered by it in the adult heart. We therefore examined FGF-2-induced effects on phosphoinositide-specific phospholipase C (PI-PLC) isozymes, which produce second messengers linked to the inotropic and hypertrophic response of the myocardium. FGF-2, administered by retrograde perfusion to the isolated heart, induced an increase in inositol-1,4,5-trisphosphate levels in the cytosol, as well as an increase in total PI-PLC activity associated with sarcolemmal and cytosolic fractions. Furthermore FGF-2 induced a time-dependent elevation in cardiomyocyte membrane-associated PLC gamma1 and PLC β1 activities, assayed in immunoprecipitated fractions, and moreover, increased the membrane levels of PLC β1 and PLC β3. Activation of PLC β is suggestive of FGF-2-induced cross-talk between FGF-receptor tyrosine kinase and G-protein-coupled signaling in adult cardiomyocytes and underscores the importance of FGF-2 in cardiac physiology.Key words: FGF-2, signal transduction, PLC gamma, PLC β, cardiomyocytes.