Proteinase Inhbitors & Crystallin Fragments in Cataract

描述：在老化过程中，晶状体总蛋白中越来越多的比例由于聚集和/或交联而变得不溶于水（Wl）。这些物种进一步交联成共价多聚体被认为在年龄相关（老年性）白内障发展过程中导致混浊。文献中描述了多种晶体蛋白的翻译后修饰作为交联机制的致病因素，但它们的相对作用尚不清楚。由于老年性白内障的发展是一个缓慢的过程，有时需要数年的时间，一些特定的修饰可能会加速交联机制，导致晶状体混浊。我们的研究结果表明，修饰的晶体蛋白片段在晶体蛋白交联过程中起着积极的作用。为了理解晶体蛋白片段的这种作用，必须确定它们的起源、翻译后修饰和交联机制，以便将它们作为一个致病因素。根据我们的研究结果，我们假设bA3/A1 -crystallin含有蛋白酶活性，但在体内由于酶活性需要激活而受到调节，而活性酶被a-crystallin抑制。bA3/ a1 -晶体蛋白蛋白酶水解a-， b-和g-晶体蛋白，晶体蛋白片段经过翻译后修饰，导致它们本身以及与phakinin和filenin（透镜状丝蛋白）交联形成共价多聚体。这些共价多聚体引起晶状体混浊。为了验证上述假设，拟开展的研究将重点回答以下三个主要问题：(A) bA3/ a1结晶蛋白arg键水解蛋白酶活性激活的分子机制是什么？(B) A3/ a1晶体蛋白蛋白酶活性在体内是如何调控的？(C)翻译后修饰的晶体蛋白片段本身以及与phakinin和filenin的共价交联机制是什么？上述研究将为年龄相关性白内障发展过程中混浊如何发展的核心问题提供答案。由于这些研究将使用人体晶状体，因此这些发现将有助于阐明A3/ a1 -晶体蛋白蛋白酶在晶体蛋白水解中的作用，它们在体内的调节，特别是晶体蛋白片段本身以及与phakinin和filenin交联的机制。

DESCRIPTION: During aging, an increasing proportion of total lens proteins becomes water insoluble (Wl), either due to aggregation and/or cross-linking. A further cross-linking of these species into covalent multimers is believed to cause opacity during age-related (senile) cataract development. A variety of post-translational modifications of crystallins are described in the literature as causative factors for cross-linking mechanism, but their relative roles remain unclear. Because the senile cataract development is a slow process and sometimes takes years, few specific modifications might act as triggers to accelerate the cross-linking mechanism and cause lens opacity. Our results show that modified crystallin fragments play an active role in the crystallin cross-linking process. To understand such a role of crystallin fragments, one must determine their origin, post-translational modifications and cross-linking mechanism in order to implicate them as a causative factor. Based on our results, we have hypothesized that bA3/A1 -crystallin contains proteinase activity, but the activity is regulated in vivo because the enzyme activity needed activation, and the active enzyme is inhibited by a-crystallin. The bA3/A1-crystallin proteinase proteolyses a-, b- and g-crystallins, and the crystallin fragments undergo post-translational modifications, leading to their cross-linking per se and with phakinin and filensin (lens beaded filament proteins) to form covalent multimers. These covalent multimers cause lens opacity. To test the above hypothesis, the proposed studies will be focused to answer the following three major questions: (A) What is the molecular mechanism of activation of an Arg-bond hydrolyzing proteinase activity of bA3/ A1-crystallin? (B) How is the b A3/A1-crystaltin proteinase activity regulated in vivo? (C) What is the covalent crosslinking mechanism of post-translationally modified crystallin fragments per se and with phakinin and filensin? The above studies will provide an answer to the central question of how opacity develops during age-related cataract development. Because human lenses will be used in these studies, the findings will be relevant in elucidating the role of b A3/A1-crystallin proteinase in the proteolysis of crystallins, their regulation in vivo, and in particular the mechanism of cross-linking of crystallin fragments per se and with phakinin and filensin.