BIOLOGICAL PROPERTIES OF RPE MELANIN

简介(由申请人提供)：建议的长远目标 保护视网膜色素上皮(RPE)免受氧化应激。氧化 老年人RPE的损伤可能会降低其支持视网膜的能力 光感受器，导致老年性黄斑变性等疾病。 这个应用的重点是黑色素。黑色素，这是一个标志 RPE细胞的特征，在某些条件下可以表现出抗氧化特性， 尽管黑色素还没有经过仔细的研究以确定它是否 实际上保护细胞免受氧化应激的伤害。RPE细胞的黑色素是 不同寻常的是，它在胚胎发生后几乎没有周转，而且它可能， 因此，随着年龄的增长，你容易发生变化。潜在的假设是 这种应用是黑色素保护RPE细胞免受氧化应激的影响 蓝光、氧化还原活性金属离子和反应性物质在视网膜外层的诱导 氧物种，但老化会改变黑色素的物理化学性质， 降低了它作为抗氧化剂的效率。在这个项目中，细胞生物学家和 一位生物物理学家计划合作，使用灵敏的电子自旋共振 (ESR)方法、细胞培养模型以及几种生化和形态 氧化应激和细胞毒性的测量，以解决这些具体目标： (1)确定牛或人RPE黑色素是否抑制脂质 过氧化，老化是否影响这一特性，以及是否机制 黑色素所谓的抗氧化功能可以通过实验来确定 对颜料颗粒进行改性。(2)原封不动或试验性引入 吞噬修饰黑色素颗粒进入培养的人RPE细胞系 (ARPE-19细胞)以确定黑色素在体内是否具有抗氧化剂功能 细胞和保护细胞免受光或化学诱导的氧化 压力。(3)测定抗氧化剂和细胞保护性能 年轻和老年人类供体的黑色素在氧化应激方面不同 细胞，以及细胞是否老化的RPE，采用复制模型 衰老，调节黑色素的抗氧化功能。详细分析了 黑色素的物理化学性质及其生物学检测 RPE单元内的功能，将提供有关 RPE颗粒的重要类别，其特性可能会随着年龄的变化而改变。

DESCRIPTION (provided by applicant): The long-term objective of the proposed protect the retinal pigment epithelium (RPE) from oxidative stress. Oxidative injury to the aged RPE may reduce its ability to support retinal photoreceptors, contributing to diseases like age-related macular degeneration. This application focuses on the pigment melanin. Melanin, which is a hallmark feature of RPE cells, can show antioxidant properties under some conditions, although melanin has not been carefully investigated to determine whether it actually protects cells from oxidative stress. The melanin of RPE cells is unusual in that it shows little turnover after embryogenesis and it may, therefore, be susceptible to changes with age. The underlying hypothesis of this application is that melanin protects RPE cells from oxidative stress induced in the outer retina by blue light, redox active metal ions and reactive oxygen species, but aging modifies melanin's physicochemical properties, reducing its efficiency as an antioxidant. In this project a cell biologist and a biophysicist plan to collaborate, using sensitive electron spin resonance (ESR) methods, cell culture models, and several biochemical and morphologic measures of oxidative stress and cytotoxicity, to address these specific aims: (1) To determine whether bovine or human RPE melanin inhibits lipid peroxidation, whether aging affects this property and whether the mechanism of melanin's putative antioxidant function can be identified by experimentally modifying the pigment granules. (2) To introduce intact or experimentally modified melanin granules by phagocytosis into a cultured human RPE cell line (ARPE-19 cells) to determine whether melanin functions as an antioxidant within cells and protects cells from photically- or chemically-induced oxidative stress. (3) To determine whether the antioxidant and cyto-protective properties of melanin from young and aged human donors differs in oxidatively-stressed cells, and whether cellular aging of the RPE, using the model of replicative senescence, modulates melanin's antioxidant function. Detailed analysis of the physicochemical properties of melanin, coupled with testing of its biological functions within RPE cells, will provide fundamental information about an important class of RPE granules whose properties may change with age.