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首页> 外文期刊>Free Radical Biology and Medicine: The Official Journal of the Oxygen Society >Hypericin-mediated photooxidative damage of alpha-crystallin in human lens epithelial cells
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Hypericin-mediated photooxidative damage of alpha-crystallin in human lens epithelial cells

机译：金丝桃素介导的人晶状体上皮细胞中α-晶状体蛋白的光氧化损伤

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摘要

St. John's wort (Hypericum perfomtum), a perennial herb native to Europe, is widely used for and seems to be effective in treatment of mild to moderate depression. Hypericin, a singlet oxygen-generating photosensitizer that absorbs in both the visible and the UVA range, is considered to be one of the bioactive ingredients of St. John's wort, and commercial preparations are frequently calibrated to contain a standard concentration. Hypericin can accumulate in ocular tissues, including lenses, and can bind in vitro to a-crystallin, a major lens protein, a-crystallin is required for lens transparency and also acts as a chaperone to ensure its own integrity and the integrity of all lens proteins. Because there is no crystallin turnover, damage to a-crystallin is cumulative over the lifetime of the lens and can lead to cataracts, the principal cause of blindness worldwide. In this work we study hypericin photosensitization of a-crystallin and detect extensive polymerization of bovine a-crystallin exposed in vitro to hypericin and UVA. We use fluorescence confocal microscopy to visualize binding between hypericin and a-crystallin in a human lens epithelial (HLE) cell line. Further, we show that UVA irradiation of hypericin-treated HLE cells results in a dramatic decrease in a-crystallin detection concurrent with a dramatic accumulation of the tryptophan oxidation product N-formylkynurenine (NFK). Examination of actin in HLE cells indicates that this cytoskeleton protein accumulates NFK resulting from hypericin-mediated photosensitization. This work also shows that filtration of wavelengths < 400 nm provides incomplete protection against a-crystallin modification and NFK accumulation, suggesting that even by wearing UV-blocking sunglasses, routine users of St. John's wort cannot adequately shield their lenses from hypericin-mediated photosensitized damage.
机译：圣约翰草（Hypericum perfomtum）是欧洲多年生的多年生草本植物，被广泛用于治疗轻度至中度抑郁症，并且似乎有效。金丝桃素是一种能在可见光和UVA范围内吸收的产生单线态氧的光敏剂，被认为是圣约翰草的生物活性成分之一，市售产品经常经过校准以包含标准浓度。金丝桃素可以在包括晶状体在内的眼组织中积累，并可以在体外与α-晶状体蛋白（一种主要的晶状体蛋白）结合，α-晶状体蛋白是晶状体透明性所必需的，还可以作为分子伴侣以确保其自身的完整性和所有晶状体的完整性蛋白质。由于没有晶状体蛋白转换，因此α-晶状体蛋白的损伤在​​晶状体的整个生命周期中都会累积，并会导致白内障，这是全世界失明的主要原因。在这项工作中，我们研究了α-晶状体蛋白的金丝桃素的光敏性，并检测了体外暴露于金丝桃素和UVA的牛α-晶状蛋白的广泛聚合。我们使用荧光共聚焦显微镜观察人晶状体上皮（HLE）细胞系中金丝桃素和α-晶状体蛋白之间的结合。此外，我们显示，用金丝桃素处理过的HLE细胞进行UVA照射会导致a-晶状蛋白检测的急剧下降，同时色氨酸氧化产物N-甲酰基kynurenine（NFK）急剧积累。 HLE细胞中肌动蛋白的检查表明，这种细胞骨架蛋白会积聚由金丝桃素介导的光敏作用产生的NFK。这项工作还表明，波长<400 nm的滤光片不能提供针对a-晶状蛋白修饰和NFK积累的不完全保护，这表明即使戴上防紫外线太阳镜，圣约翰草的常规使用者也无法充分遮挡其镜片，免受金丝桃素介导的光敏性影响。损伤。

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