Protein kinase C δ regulates anti-apoptotic αB-crystallin in the retina of type 2 diabetes

We investigated the relationship between phosphorylation of alphaB-crystallin (αBC) and retinal apoptosis in type 2 diabetes. The retinas of male Otsuka Long–Evans Tokushima fatty (OLETF) rats at 24 and 35 weeks were used as an animal model for type 2 diabetes and sex- and age-matched Long–Evans Tokushima Otsuka (LETO) rats were used as controls. In the retinas of 35-week OLETF rats, the interaction between αBC and protein kinase C delta (PKC δ) among the PKC isozymes, αBC phosphorylation at Ser45 (S45p-αBC), TUNEL-positive apoptotic ganglion cells, several apoptotic signs, and co-localization of S45p-αBC and TUNEL significantly increased as compared with other groups while the αBC–Bax interaction greatly decreased. These changes were abolished by rottlerin treatment, a highly specific PKC δ inhibitor. These results suggest that PKC δ is involved in regulation of anti-apoptotic function of αBC in the retina of type 2 diabetes.