Light-induced CREB phosphorylation and gene expression in rat retinal cells.

The signal pathway for light-induced expression of c-fos and the neuropeptide somatostatin (SS) in rat retinal cells was investigated. Flashing light induced c-fos and SS mRNA in the inner nuclear layer and the ganglion cell layer. As both c-fos and SS genes have a cyclic AMP response element (CRE) in their promoters, CRE-binding protein (CREB) phosphorylation in retinal cells was examined with a phospho-CREB-specific antibody. Both flashing light and administration of the L-type Ca2+ channel activator Bay K 8644 induced phosphorylation of CREB in the nuclei of the amacrine cells and the ganglion cells where c-fos/SS mRNAs were expressed. These cells could be double-stained with anti-calmodulin kinase II (anti-CaM kinase II) monoclonal antibody and phospho-CREB-specific polyclonal antiserum after Bay K 8644 administration, indicating the colocalization of phosphorylated CREB at Ser133 and CaM kinase II in the neural retina.