Classical, novel and atypical isoforms of PKC stimulate ANF- and TRE/AP-1-regulated-promoter activity in ventricular cardiomyocytes

Cultured neonatal rat ventricular myocytes were co-transfected with expression plasmids encoding protein kinase C (PKC) isoforms from each of the PKC subfamilies (classical PKC-α, novel PKC-ε or atypical PKC-ξ) together with an atrial natriuretic factor (ANF) reporter plasmid. Each PKC had been rendered constitutively active by a single Ala→Glu mutation or a small deletion in the inhibitory pseudosubstrate site. cPKC-α, nPKC-ε or aPKC-ξ expression plasmids each stimulated ANF-promoter activity and expression of a reporter gene under the control of a 12-O-tetradecanoylphorbol 13-acetate-response element (TRE). Upregulation of the ANF promoter is characteristic of the hypertrophic response in the heart ventricle and a TRE is present in the ANF promoter. Thus all subfamilies of PKC may have the potential to contribute to hypertrophic response in cardiomyocytes