Chemistry Department, Molecular Sciences Research Hub, Imperial College London, 82 Wood Lane, London W12 0BZ, UK; International Tomography Center SB RAS, Institutskaya street 3A, Novosibirsk 630090, Russia.
Center for Physical Sciences and Technology, Saulėtekio av. 3, Vilnius LT-10257, Lithuania; Chemistry Department, Vilnius University, Naugarduko st. 24, Vilnius LT-03225, Lithuania.
J Photochem Photobiol B. 2021 Dec;225:112346. doi: 10.1016/j.jphotobiol.2021.112346. Epub 2021 Oct 23.
An eye lens is constantly exposed to the solar UV radiation, which is considered the most important external source of age-related changes to eye lens constituents. The accumulation of modifications of proteins and lipids with age can eventually lead to the development of progressive lens opacifications, such as cataracts. Though the impact of solar UV radiation on the structure and function of proteins is actively studied, little is known about the effect of photodamage on plasma membranes of lens cells. In this work we exploit Fluorescence Lifetime Imaging Microscopy (FLIM), together with viscosity-sensitive fluorophores termed molecular rotors, to study the changes in viscosity of plasma membranes of porcine eye lens resulting from two different types of photodamage: Type I (electron transfer) and Type II (singlet oxygen) reactions. We demonstrate that these two types of photodamage result in clearly distinct changes in viscosity - a decrease in the case of Type I damage and an increase in the case of Type II processes. Finally, to simulate age-related changes that occur in vivo, we expose an intact eye lens to UV-A light under anaerobic conditions. The observed decrease in viscosity within plasma membranes is consistent with the ability of eye lens constituents to sensitize Type I photodamage under natural irradiation conditions. These changes are likely to alter the transport of metabolites and predispose the whole tissue to the development of pathological processes such as cataracts.
晶状体不断受到太阳紫外线辐射的影响，而紫外线辐射被认为是导致眼晶状体成分与年龄相关变化的最重要外部来源。随着年龄的增长，蛋白质和脂质的修饰不断积累，最终可能导致晶状体逐渐混浊，例如白内障。尽管人们积极研究太阳紫外线辐射对蛋白质结构和功能的影响，但对于光损伤对晶状体细胞质膜的影响知之甚少。在这项工作中，我们利用荧光寿命成像显微镜（FLIM）和称为分子转子的粘度敏感荧光染料，研究了两种不同类型的光损伤（I 型（电子转移）和 II 型（单线态氧）反应）对猪眼晶状体质膜粘度的变化。我们证明，这两种类型的光损伤会导致粘度发生明显不同的变化——I 型损伤导致粘度降低，而 II 型过程则导致粘度增加。最后，为了模拟体内发生的与年龄相关的变化，我们在无氧条件下使完整的眼晶状体暴露于 UV-A 光下。质膜内粘度的观察到的降低与眼晶状体成分在自然辐射条件下敏化 I 型光损伤的能力一致。这些变化可能会改变代谢物的运输，并使整个组织容易发生白内障等病理过程。
