Gene activation of CREB by light/dark cycle in the rat retina

研究了光诱导视网膜细胞基因表达的信号通路。闪光可诱导内核层（INL）内缘和神经节核层（GNL）细胞内c-fos和生长抑素的表达。由于c-fos基因和生长抑素基因的启动子中都含有cAMP反应元件（CRE），因此用磷酸化CREB特异性抗体检测视网膜细胞中CREB的磷酸化。闪光灯照射1 min，CREB的磷酸化水平最高，与视网膜同一部位c-fos和生长抑素mRNA的表达密切相关。给予L型Ca^<2+>通道激活剂Bay K 8644也可诱导大鼠视网膜CREB磷酸化以及c-fos和生长抑素的表达。钙调蛋白激酶II免疫反应性视网膜细胞的分布与磷酸化CREB免疫反应性一致。因此，我们认为，在神经视网膜中，光刺激的转录反应是通过Ca 2 +/钙调素依赖性蛋白激酶催化的CREB磷酸化来调节的。

The signal pathway of the light-induced gene expression in retinal cells was investigated. Flashing light induced c-fos and somatostatin in the cells of the inner border of the inner nuclear layr (INL) and the ganglion nuclear layr (GNL). As both c-fos and somatostatin genes have cAMP responsive element (CRE) in their promoters, CREB phosphorylation in retinal cells was examined with phospho-CREB specific antibody. One min exposure to flashing light induced maximum phosphorylation of CREB showing close correlation with c-fos and somatostatin mRNA expression in the same portion of the retina. Administration of L-type Ca^<2+> channel activator Bay K 8644 also induced CREB phosphorylation and c-fos and somatostatin expression in the rat retina. The distribution of calmodulin kinase II immunoreactive retina cells was in good accordance with the phospho-CREB immunoreactivity. Thus we propose that transcriptional response to light stimulation is regulated via CREB phosphorylation catalyzed by Ca^<2+>/calmodulin-dependent protein kinase in neural retina.