PROTEIN-KINASE-C ISOZYMES IN PROSTATIC EPITHELIAL-CELLS FROM NORMAL, DIABETIC AND INSULIN-TREATED DIABETIC RATS

1. Immunoblot experiments in rat prostatic epithelium using a non-sele ctive antibody against protein kinase C (PKC) allowed to detect three PKC subspecies of 87.5, 55.5 and 34.6 kDa that showed higher, similar and lower immunoreactivity in the membrane than in the cytosolic compa rtment, respectively. 2. Specific monoclonal antisera revealed that th e PKC-gamma isozyme is not expressed in the rat prostatic epithelium, whereas the PKC-P isozyme was noted only in the cytosolic fraction sho wing an apparent molecular weight of 75.5 kDa.3. Induction of diabetes by streptozotocin led to modifications in the expression of PKC isozy mes so that the immunoreactivities of the 87.5- and 55.5-kDa PKC forms decreased in both cytosolic and membrane subcellular fractions to dif ferent extents. 4. The most important decrease was chat of the 55.5-kD a PKC form in cytosol that returned to control values by insulin thera py, whereas PKC-beta suffered also some decrease in diabetes and incre ased again with insulin treatment.