MULTIPLE ISOFORMS OF THE REGULATORY SUBUNIT FOR PHOSPHATIDYLINOSITOL 3-KINASE (PI3-KINASE) ARE EXPRESSED IN NEURONS IN THE RAT-BRAIN

Phosphatidylinositol 3-kinase (PI3-kinase) is a heterodimeric enzyme c omposed of a catalytic subunit of 110 kDa and an adaptor regulatory su bunit. We investigated the presence and localization of five isoforms of the regulatory subunits, p55 alpha, p55 gamma, p85 alpha, p85 beta, and p50 alpha, in the rat brain. In situ hybridization histochemistry using isoform-specific cRNA probes revealed that all five isoforms we re expressed in the neurons of the brain. Interestingly, most neuronal cells including Purkinje cells in the cerebellum and pyramidal cells in the cerebrum expressed all five isoforms. Immunohistochemical stain ing also showed the localization of p55 alpha, p55 gamma, p85 alpha, a nd p50 alpha in the neuronal cells in the brain. Expression of multipl e isoforms in neurons suggests that they may play important roles in s ignal transduction in the brain. (C) 1998 Academic Press.