DIFFERENTIAL RECOVERY OF PROTEIN KINASE-C-ALPHA AND KINASE-C-EPSILON ISOZYMES AFTER LONG-TERM PHORBOL ESTER TREATMENT IN RAT RENAL MESANGIAL CELLS

Glomerular mesangial cells have been shown to express two protein kinase C (PKC) isozymes, PKC-α and PKC-e{open}. Upon long-term treatment with phorbol ester PKC-α is depleted faster than PKC-e{open}. Here we demonstrate that removal of phorbol ester results in a differential recovery of PKC-α and -e{open} isozymes. Whereas PKC-e{open} starts to recover within 1h, PKC-α does not begin to recover before 4 h after removal of phorbol ester. These data suggest a differential rate of protein synthesis of PKC-α and -e{open}. In parallel to the recovery of PKC isozymes mesangial cells also regained their functional responsiveness, i.e., stimulation of prostaglandin synthesis and feedback inhibition of angiotensin II-stimulated InsP3 formation. © 1991 Academic Press, Inc.