QUANTITATION OF PROTEIN TURNOVER IN THE HUMAN LENS USING THE 14C BOMB-PULSE

该子项目是利用 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得主要资金， 因此可以在其他CRISP条目中表示。列出的机构是 研究中心，而研究中心不一定是研究者所在的机构。 研究健康人体中大分子的合成和修复是困难的。 1955年至1963年的地面核武器试验产生了巨大的14 CO2“炸弹脉冲”，它迅速分布在地球仪周围，并内在地标记了生物圈中所有可交换的碳。自1963年《禁核试条约》以来，大气中的14 C炸弹脉冲呈指数级下降，平均寿命约为16年，这不是由于放射性衰变，而是由于扩散和与海洋和生物圈的平衡。所有活着的人都被标记了，所有有机大分子中的14 C浓度都可以灵敏地识别它们是何时合成的。 事实上，我们都是长期准稳定同位素示踪研究的对象，在这项研究中，可以通过使用加速器质谱（AMS）来计算亚毫克样品中的单个14 C原子来确定分子合成的日期。 我们试图利用这种有效的分子计时器来建立，量化，并确定在健康的成年人的眼睛晶状体蛋白质营业额的具体性质。来自60岁以上晶状体的初步数据表明，老化核纤维细胞的晶状体蛋白质含有比细胞本身明显年轻的碳。这作为人核纤维细胞中体内蛋白质周转的直接证据，并验证了有争议的假设，即人眼透镜通过从头蛋白质产生在其核心（至少部分）保持稳态。我们将测量在爆炸脉冲峰值后形成的晶状体核芯中纯化蛋白质的碳周转率，再加上一些老化的对照。与从老年供体收集的数据相比，年轻晶状体中的蛋白质掺入将提供直接证据，证明当我们达到中年时，该速率是否会减弱。更好地了解透镜的维护可以提供一个有用的新工具，以了解和最终预防最常见的透镜病理形式，年龄相关核性（ARN）白内障。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Studying synthesis and repair of macromolecules in healthy humans is difficult. Above ground testing of nuclear weapons from 1955-1963 produced a large "bomb-pulse" of 14CO2, which was quickly distributed around the globe and intrinsically labeled all exchangeable carbon in the biosphere. Since the Test Ban Treaty in 1963, the atmospheric 14C bomb-pulse has been decreasing exponentially with a mean life of ~ 16 years, not due to radioactive decay, but due to diffusion and equilibration with the oceans and biosphere. All living humans have been labeled, and the 14C concentration in all organic macromolecules can sensitively identify when they were synthesized. In reality, we are all subjects in a long-term quasi-stable isotope tracer study in which molecular synthesis can be dated through the use of accelerator mass spectrometry (AMS) to count individual 14C atoms in sub-milligram samples. We seek to utilize this effective molecular chronometer to establish, quantify, and identify the specific nature of protein turnover in healthy adult human eye lenses. Preliminary data from lenses age 60 and greater suggests that the crystallin proteins of aged nuclear fiber cells contain carbon significantly younger than the cells themselves. This serves as direct evidence of in vivo protein turnover in human nuclear fiber cells and verifies the controversial hypothesis that the human eye lens maintains homeostasis at its core (at least in part) by de novo protein production. We will measure carbon turnover in purified proteins from the nuclear core of lenses formed after the peak of the bomb-pulse plus some aged controls. Compared with the data gathered from older donors, dating protein incorporation in younger lenses will provide direct evidence if this rate is attenuated when we reach middle age. A better understanding of lens maintenance could provide a useful new tool to understand and ultimately prevent the most common form of lens pathology, age related nuclear (ARN) cataract.