EXPRESSION AND FUNCTION OF STRESS PROTEIN IN THE OCULAR TISSUE

细胞通过增加一组蛋白质的水平来应对环境的不利变化，这组蛋白质被称为热休克或应激蛋白质。有人认为，这些蛋白质提供了保护，防止应激诱导的变性蛋白质的形成，甚至可能促进它们的复性。该报告支持70kodalton应激蛋白(SP70)在视觉系统中的作用，该报告表明，在整个动物短暂的高温期间诱导的视网膜应激蛋白的表达，与视网膜对随后的光损伤的敏感性显著降低有关。SP70在人视网膜组织中的特殊功能仍有待阐明。为了探索该蛋白的生理功能，我们检测了它在正常和应激状态下的人视网膜中的定位。我们比较了SP70在正常人和绝对期青光眼患者视网膜中的免疫定位。正常人视网膜呈弥漫性免疫染色。…外核层免疫组化染色较弱。而绝对期青光眼患者的视网膜内节段和光感受器细胞核均有明显的免疫染色。这项研究的结果表明，在人的视网膜中，SP70的诱导是由于眼压升高所致。在大鼠视网膜的实验中，早期的工作表明，将麻醉大鼠的体温提高到41-42ﾟC，可以增加其SP70的含量，并且在SP70升高的过程中，视网膜对光损伤具有抵抗力。在此基础上，我们测定了青年(3月龄)和老年(20月龄)Fisher 344大鼠在正常条件下和短暂高温后视网膜各层中SP70的水平。其目的是确定视网膜SP70的紊乱是否可能与Fisher大鼠视网膜中光感受器随着年龄的增长而逐渐丧失的证据充分相关。高温后，20月龄大鼠视网膜各层感光细胞的SP70免疫反应均低于3月龄大鼠。由于已知SP70可以保护细胞免受代谢应激的致命影响，在老年大鼠中观察到的下降表明，视网膜对代谢应激的反应存在损害，这可能使光感受器更容易受到光损伤和破坏。将需要进一步的工作来确定这种缺陷是一个致病因素还是老年性视网膜变性的一种附带现象。较少

Cells respond to adverse changes in the environment by increasing the levels of a group of proteins referred to as heat shock, or stress, proteins. It is suggested that these proteins provide protection against the stress-induced formation of denatured proteins andmay even facilitate their renaturation. The role of 70 kilodalton stress protein (SP70) in the visual system is supported in the report, that showed the expression of stress protein in the retina, which was induced by a brief period of hyperthermia in the whole animal, correlated with a marked reduction in retinal susceptibility to subsequent light damage. The particular function of SP70 in human retinal tissue remains to be elucidated. To explore the physiological functions of this protein, its localization in the normal and stressed human retina was examined. We compared the immunolocalization of SP70 in normal human retina and in one with absolute glaucoma. The normal human retina showed diffuse immunostaining throughout. … More The outer nuclear layr was poorly immunostained. However, the retina with absolute glaucoma, demonstrated obvious immunostaining in the inner segments and in the nuclei of the photoreceptor cells. Results of this study suggest an induction of SP70 in the human retina stressed by increased intraocular pressure. In the experiment with rat retina, earlier work has shown that its content of SP70 can be increased by raising the anesthetized rat's body temperature to 41-42ﾟC and that during the time of the elevated SP70, the retina is resistant to light damage. On the basis of this connection, we evaluated the levels of SP70 in each of the layrs of the retina of young (3 month) and old (20 month) Fisher 344 rats under normal conditions and after being challenged by a brief period of hyperthermia. The aim was to determine if a disturbance in retinal SP70 might correlate with the well documented gradual loss of photoreceptors in the Fisher rat retina as a function of increasing age. During the post-hyperthermia period, the 20 month old rats showed consistently lower levels of SP70 immunoreactivity than the 3 month old rats in all of the retinal layrs that include the various parts of the photoreceptor cells. Since SP70 is known to protect cells from the lethal effects of methabolic stress, decline observed in the older rats suggests that there is an impairment of the retinal response to metabolic stress which may render the photoreceptors more susceptible to the light damage and destruction. Further work will be required to determine if this defect is a causative factor or an epiphenomenon of age-lerated retinal degeneration. Less