Kutty G, Duncan T, Nickerson J M, Si J S, Van Veen T, Chader G J, Wiggert B
National Eye Institute, National Institutes of Health, Bethesda, MD 20892.
Exp Eye Res. 1994 Jan;58(1):65-75. doi: 10.1006/exer.1994.1195.
Ambient light appears to play a role in regulating gene and protein expression of interphotoreceptor retinoid-binding protein (IRBP), a protein that facilitates the transport of retinoids between the neural retina and pigment epithelium in the visual cycle. Pregnant CD-1 mice were placed in the dark approximately 48 hr before parturition, and the pups were reared for 14 days under these conditions. Control animals were reared on a 12 hr light/12 hr dark cycle. Northern blotting of total RNA isolated from whole mouse eyes at post-natal days 7-14 (P7-P14) showed a marked reduction in IRBP message in the light-deprived animals to 10-20% of levels in control animals. Reprobing of the blots for opsin and S-antigen message showed a significant decrease of about 80-90% in opsin message at 5.1 kb but no change in S-antigen message in the eyes of light-deprived mice. Light microscopic examination of the light-deprived mouse retinas showed no apparent abnormalities in morphological development and immunocytochemistry demonstrated normal distribution and levels of IRBP protein. Immunochemical quantitation of IRBP protein confirmed that there was no reduction in light-deprived as compared to normal mouse eyes. Similarly, when adult mice were light-deprived for 14 days, a marked reduction in IRBP message was also observed with no decrease in the amount of IRBP protein. Thus, light deprivation causes a large decrease in IRBP message in the mouse eye, but IRBP protein is not decreased. The dramatic effect of light deprivation on IRBP mRNA and some opsin mRNAs, but not on S-antigen message and the fact that IRBP protein levels are relatively unaffected, suggest a complex pathway of light regulation of photoreceptor function previously not encountered. This may involve regulatory controls at levels including gene transcription, mRNA stability or protein degradation that may make use of a feedback control mechanism involving light- or dark-dependent signal transduction.
环境光似乎在调节视网膜间类视黄醇结合蛋白（IRBP）的基因和蛋白质表达中发挥作用，IRBP是一种在视觉循环中促进类视黄醇在神经视网膜和色素上皮之间运输的蛋白质。妊娠的CD-1小鼠在分娩前约48小时置于黑暗环境中，幼崽在这些条件下饲养14天。对照动物在12小时光照/12小时黑暗周期下饲养。对出生后第7 - 14天（P7 - P14）从整个小鼠眼睛分离的总RNA进行Northern印迹分析显示，光照剥夺的动物中IRBP信息显著减少至对照动物水平的10 - 20%。对印迹重新检测视蛋白和S抗原信息显示，光照剥夺小鼠眼睛中5.1 kb处的视蛋白信息显著减少约80 - 90%，但S抗原信息没有变化。对光照剥夺的小鼠视网膜进行光镜检查显示形态发育无明显异常，免疫细胞化学显示IRBP蛋白分布和水平正常。IRBP蛋白的免疫化学定量证实，与正常小鼠眼睛相比，光照剥夺组没有减少。同样，当成年小鼠光照剥夺14天时，也观察到IRBP信息显著减少，但IRBP蛋白量没有减少。因此，光照剥夺导致小鼠眼睛中IRBP信息大幅减少，但IRBP蛋白没有减少。光照剥夺对IRBP mRNA和一些视蛋白mRNA有显著影响，但对S抗原信息没有影响，以及IRBP蛋白水平相对未受影响这一事实，表明存在一条以前未遇到的复杂的光调节光感受器功能途径。这可能涉及包括基因转录、mRNA稳定性或蛋白质降解水平的调节控制，可能利用了涉及光或暗依赖性信号转导的反馈控制机制。
