EXPRESSION OF PROTEIN-KINASE-C ISOFORMS IN RENAL TISSUE

PKC plays a central role for the regulation of renal function. PKC consists of a family of isoenzymes. By employing Northern blot techniques we have demonstrated that mRNA transcripts for the classical Ca2+-dependent, diacylglycerol-activated isoform alpha, the novel, Ca2+-independent isoform delta and the atypical isoform zeta are abundantly expressed in the rat kidney. The novel PKC-epsilon was weakly expressed. The classical PKCs >beta I, beta II and gamma could not be detected. The mRNA expression of PKC-delta and -zeta increased with age. The intrarenal localization of PKC-alpha, -delta and -zeta isoforms were studied in the adult kidney using in situ hybridization. In the cortex, the PKC-alpha isofom showed the strongest hybridization signal. PKC alpha, delta and zeta were all distributed in the outer medulla. The PKC-alpha probe detected particularly strong signal in the outer stripe of the outer medulla. Western blot confirmed the presence of the PKC-alpha, -delta and -zeta enzymes in renal tissue. The results show cell-specific and developmentally-dependent expression of three types of PKC isoforms with different responses to diacylglycerol and calcium. The developmental increase of both PKC-delta and PKC-zeta suggests a specific role for these isoforms for the functional regulation of the mature kidney.