Lou M F, Xu G T, Cui X L
Department of Veterinary and Biomedical Sciences, University of Nebraska-Lincoln 68583, USA.
Curr Eye Res. 1995 Oct;14(10):951-8. doi: 10.3109/02713689508995135.
To further investigate the role of protein-thiol mixed disulfides in cataractogenesis, an in vitro H2O2 cataract model was used with rat lenses to study the effect of aging, and the dynamic changes in the cortex, nucleus and the lens protein fractions. A group of lenses was exposed to H2O2-containing media (0.6 mM) for 1 to 3 days so that cortical cataract was induced gradually. Another group of lenses was first subjected to H2O2 exposure for one day and then recovered in the oxidant-free media for one or two days. These lenses were examined for the distribution of free glutathione and protein-thiol mixed disulfides (protein-glutathione and protein-cysteine) in the cortical and nuclear regions as well as in the water soluble and water insoluble fractions. Similar to the results reported earlier, the glutathione depletion in the whole lens occurred immediately and extensively during the 3-day H2O2 exposure. This loss was evenly distributed in the cortical and nuclear fractions. The level of protein-glutathione increased rapidly and continued throughout the 3 days. Most of the accumulation was found in the cortex and in both lens protein fractions. The protein-cysteine modification responded more slowly and less to oxidative stress. The delayed formation occurred mainly in the nucleus and in both lens protein fractions. In the recovery group, glutathione depletion was less drastic in the cortical and nuclear regions, but the elevated protein-glutathione in both regions and both protein fractions spontaneously decreased to its respective basal level within 1 day. Protein-cysteine on the other hand remained quite high, and in some cases it continued to rise in the absence of oxidation. Aging showed little effect on the response of rat lenses to oxidative stress. Similar patterns in glutathione and protein-thiol mixed disulfides occurred in both age groups (1, 23 months) and in both chronic oxidative stress and recovery conditions.
为了进一步研究蛋白质-硫醇混合二硫键在白内障形成中的作用，使用大鼠晶状体的体外过氧化氢白内障模型来研究衰老的影响以及皮质、核和晶状体蛋白质组分的动态变化。一组晶状体暴露于含0.6 mM过氧化氢的培养基中1至3天，从而逐渐诱导皮质性白内障。另一组晶状体先暴露于过氧化氢中一天，然后在无氧化剂的培养基中恢复一或两天。检测这些晶状体皮质和核区域以及水溶性和水不溶性组分中游离谷胱甘肽和蛋白质-硫醇混合二硫键（蛋白质-谷胱甘肽和蛋白质-半胱氨酸）的分布。与早期报道的结果相似，在3天的过氧化氢暴露期间，整个晶状体中的谷胱甘肽立即大量消耗。这种损失在皮质和核组分中均匀分布。蛋白质-谷胱甘肽水平迅速升高并在3天内持续上升。大部分积累发生在皮质以及两种晶状体蛋白质组分中。蛋白质-半胱氨酸修饰对氧化应激的反应较慢且程度较小。延迟形成主要发生在核以及两种晶状体蛋白质组分中。在恢复组中，皮质和核区域的谷胱甘肽消耗不那么剧烈，但两个区域和两种蛋白质组分中升高的蛋白质-谷胱甘肽在1天内自发降至各自的基础水平。另一方面，蛋白质-半胱氨酸仍然相当高，在某些情况下，在没有氧化的情况下它继续上升。衰老对大鼠晶状体对氧化应激的反应影响很小。在两个年龄组（1、23个月）以及慢性氧化应激和恢复条件下，谷胱甘肽和蛋白质-硫醇混合二硫键都出现了相似的模式。
