紫外线辐射对α-晶状体蛋白分子伴侣活性的作用

Effect of UV irradiation on the molecular chaperone activity of α-crystallin

目的 研究在老化和白内障形成过程中紫外线 (UV)辐射对α 晶状体蛋白分子伴侣活性的作用。方法 新生Sprague Dawley大鼠皮下注射亚硒酸钠诱导硒性白内障 (SC) ,采用SephacrylS 3 0 0HR分离幼年和老年兔晶状体皮质和核以及SC大鼠α 晶状体蛋白。以α 晶状体蛋白对过氧化氢酶热凝聚的抑制作为分子伴侣活性指标 ,观察UV B (3 0 0nm )辐射α 晶状体蛋白后 ,其伴侣活性的变化。结果 UV辐射新生和老年兔晶状体核αL 晶状体蛋白后 3 0h ,与辐射前比较伴侣活性降低约 18%和 14 % ,而皮质的变化不显著 ;至 10 0h时 ,老年兔皮质、核和新生兔核αL 晶状体蛋白的伴侣活性分别下降 8%、2 7%和 2 3 %。辐射第 192h ,正常大鼠和SC晶状体αH 和αL 晶状体蛋白的伴侣活性显著降低 ,正常组分别下降 3 5 %和 2 3 % ,SC组下降 3 1%和 10 %。结论 UV B辐射可降低α 晶状体蛋白的分子伴侣活性 ,并呈时间依赖效应。UV辐射对老年α 晶状体蛋白分子伴侣活性影响比幼年显著 ,晶状体核比皮质对UV辐射敏感 ,αH 晶状体蛋白比αL 晶状体蛋白敏感。UV辐射可进一步降低硒性白内障α 晶状体蛋白的分子伴侣活性。

ObjectiveTo evaluate the effect of ultraviolet(UV) irradiation on molecular chaperone activity of α crystallin during ageing and cataract formation.MethodsSodium selenite was subcutaneously injected in newborn Sprague Dawley rats to create the selenite induced cataract . α Crystallin of newborn and old rabbits and selenite cataractous lenses in both cortex and nucleus were separated by chromatography on Sephacryl S 300HR. The preventive effects of α crystallin on thermally induced aggregation of catalase (chaperone activity) were measured spectrophotometrically. The change of chaperone activity of α crystallin after UV B (300 nm) irradiation was observed. ResultsThe preventive ability of α L crystallin in nucleus from newborn and old lenses was less than that of the control ( approximately 18% and 14%) after 30 hours UV irradiation, and there was no significant decrease of chaperone activity in cortex. After 100 hours UV irradiation, the chaperone activities of α L crystallin in cortex and nucleus from old lenses and in nucleus from newborn lenses were diminished approximately 8%, 27% and 23% compared with those without UV irradiation, respectively. There was a remarkably decrease of chaperone activity in both α H crystallin and α L crystallin from rat clear and selenite cataractous lenses after 192 hours irradiation. The protection by α H crystallin and α L crystallin in clear lenses was decreased 35% and 23%, 31% and 10% in selenite cataractous lenses respectively.ConclusionThe molecular chaperone activity of α crystallin was compromised by UV B irradiation in time-dependent manner. The effect of UV irradiation on chaperone activity of α crystallin from old rabbit lenses was greater than that from newborn lenses. Moreover, α crystallin from nucleus was more sensitive to UV than α crystallin derived from cortex, and α H crystallin was more susceptible than α L crystallin in both cortex and nucleus. UV irradiation further decreased chaperone activity of α crystallin from selenite cataractous lenses.