Alterations of nuclear localization of transcription factor c-Jun in brain of diabetic rats with hyperglycemia

De novo protein synthesis in eukaryotes is mainly controlled at the level of gene transcription by transcription factors in the nucleus. In this communication, the expression and nuclear localization of the activator protein-1 (AP1) family member c-Jun in nuclear and cytosolic fractions of brain and retina from streptozotocin (STZ)-injected diabetic rats were determined in order to evaluate the possibility that transportation of AP1 family members from the cytoplasm to the nucleus could play a role in diabetes. Immunoblotting assays with a specific antibody revealed a much higher expression of immunoreactive c-Jun in nuclear fractions than in cytosolic fractions of the cerebral cortex, hippocampus, striatum and cerebellum after diabetes induction by administration of STZ. In contrast, administration of STZ failed to affect the nuclear localization of c-Jun detected in the hypothalamus, midbrain, medulla-pons and retina. These results suggest that the STZ-injected diabetic rat shows differential alterations in nuclear localization of c-Jun protein in the brain and retina.