Immunolocalization of Protein Kinase C Isoenzymes α, βI, βII and γ in Adult and Developing Rat Kidney

Protein kinase C (PKC) plays an important role not only in signal transduction mechanisms in various biological processes, but also in the regulation of growth and differentiation during development. We studied the classical PKCα, βI, βII and γ, with regard to their expression in adult and developing rat kidney. PKCα appeared in the ureteric bud at embryonic day (E) 16, and the proximal and distal anlage at E18. After birth, the immunoreactivity of PKCα gradually decreased. In adult, PKCα was expressed intensely in the connecting tubule (CNT), the collecting ducts (CD) and the renal corpuscle, and weakly in the proximal and distal tubules. PKCβI appeared in the ureteric bud at E16, and the proximal anlage at E18. After birth, the immunoreactivity of PKCβI gradually disappeared from the CD and proximal tubule. In adult, PKCβI was expressed in the intercalated cells of the CNT and cortical CD, the proximal straight tubule, and the renal corpuscle. PKCβII appeared in distal anlage at E18, and increased markedly after birth. In the CD, PKCβII immunoreactivity appeared after birth. In adult, PKCβII was expressed in the distal tubule, the CNT and the CD. The immunoreactivity for PKCγ appeared only in the proximal anlage at E18, and increased temporally around the time of birth. However, no immunoreactivity for PKCγ was observed in adult rat kidney. These results indicate that classical PKC isoforms appear to play a role in the regulation of various renal functions and differentiation within specific functional units of the uriniferous tubule in rat kidney.