STIMULUS-DEPENDENT SUBCELLULAR-LOCALIZATION OF ACTIVATED PROTEIN-KINASE-C - A STUDY WITH ACIDIC FIBROBLAST GROWTH-FACTOR AND TRANSFORMING GROWTH-FACTOR-BETA-1 IN CARDIAC MYOCYTES

Protein kinase C (PKC) isozymes regulate a number of cardiac functions including contractility, gene expression, and hypertrophy. There are at least six PKC isozymes in neonatal rat ventricular myocytes. We hav e shown previously that stimulation of cardiac myocytes in culture wit h norepinephrine (NE) or phorbol 12-myristate 13-acetate (PMA) results in translocation of each isozyme to distinct subcellular sites. In th e present work, we demonstrated that PKC isozymes vary in their sensit ivity to stimulation by acidic fibroblast growth factor (aFGF) and tra nsforming growth factor-beta 1 (TGF-beta 1). Moreover, immunocytochemi cal studies indicated differences in the subcellular localization of a ctivated isozymes following stimulation with each growth factor. These data suggest that the site of translocation and the resulting functio n of individual PKC isozymes are distinct for different PKC activators . Identification of the PKC isozymes that respond to aFGF and TGF-beta 1 and their subcellular localization may provide a molecular basis fo r the divergent cardiac functions mediated by these two growth factors . (C) 1995 Academic Press Limited