Li Bo, Suzuki-Kerr Haruna, Lim Christopher J J, Martis Renita M, Yang Fenger Ou, Carlos Erl, Donaldson Paul J, Poulsen Raewyn C, Lim Julie C
Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand.
New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand.
Invest Ophthalmol Vis Sci. 2025 Jun 2;66(6):24. doi: 10.1167/iovs.66.6.24.
To determine whether light influences time-of-day differences in the expression of circadian clock and redox genes and the antioxidant glutathione (GSH) in cultured rat lenses.
Rat Wistar lenses (6 weeks) were cultured over a 24-hour period either in 12 hours of light and then 12 hours of dark (12-hour light/12-hour dark) or in constant darkness (12-hour dark/12-hour dark). Lenses were collected at 0 hour, after 12 hours, and then 24 hours after culture, and either quantitative PCR was performed to examine the expression of core clock genes and GSH-related redox genes or high-performance liquid chromatography was used to measure intracellular GSH levels. Lenses were collected at 10 AM, 2 PM, 6 PM, and 10 PM, fixed, sectioned, and labeled with the antibodies against the light-sensing melanopsin protein.
Under 12-hour light/12-hour dark conditions, core clock genes and redox genes involved in GSH synthesis displayed time-of-day differences in their expression patterns which were not maintained under constant darkness. GSH levels remained constant under both lighting conditions. Melanopsin was localized to the epithelial cells at the anterior epithelium but absent from epithelial cells in the equatorial epithelium and fiber cells.
The lens possesses the ability to detect light via melanopsin localized exclusively in the anterior lens epithelium. This may act as a cue for the lens to drive day and night differences in the expression of clock genes and/or redox genes, ensuring that GSH levels are maintained at normal physiological levels to provide protection from oxidative stress across the light/dark cycle.
确定光照是否会影响培养的大鼠晶状体中昼夜节律钟基因、氧化还原基因以及抗氧化剂谷胱甘肽（GSH）表达的昼夜差异。
将6周龄的Wistar大鼠晶状体在24小时内分别培养于12小时光照然后12小时黑暗（12小时光照/12小时黑暗）或持续黑暗（12小时黑暗/12小时黑暗）条件下。在培养0小时、12小时及24小时后收集晶状体，进行定量PCR检测核心生物钟基因和GSH相关氧化还原基因的表达，或用高效液相色谱法测量细胞内GSH水平。在上午10点、下午2点、下午6点和晚上10点收集晶状体，固定、切片，并用抗感光黑素蛋白的抗体进行标记。
在12小时光照/12小时黑暗条件下，参与GSH合成的核心生物钟基因和氧化还原基因的表达模式存在昼夜差异，而在持续黑暗条件下这种差异未得到维持。在两种光照条件下GSH水平均保持恒定。黑素蛋白定位于前囊上皮细胞，但赤道上皮细胞和纤维细胞的上皮细胞中不存在。
晶状体具有通过仅定位于晶状体前上皮的黑素蛋白检测光的能力。这可能作为一种信号，促使晶状体驱动生物钟基因和/或氧化还原基因表达的昼夜差异，确保GSH水平维持在正常生理水平，以在光暗循环中提供抗氧化应激保护。
