Glycation inactivation of human CD59 and diabetic complications

描述（由申请人提供）：慢性高血糖（hyperglycemia）是导致糖尿病并发症的原因，包括肾病、视网膜病变、神经病变和加速动脉粥样硬化，这些都是成年人群发病和死亡的主要原因。然而，高血糖如何引起糖尿病并发症仍然知之甚少。我们和其他人的大量临床研究表明，补体系统作为免疫系统的主要效应器和炎症介质，可能在这些并发症的发病机制中发挥重要作用。特别是，我们已经确定人类CD59，一种关键的补体调节蛋白，保护细胞免受补体介导的损伤，被糖基化（葡萄糖与蛋白质的非酶结合）抑制。这是因为人类CD59含有一个糖基化基序，它是由位于h5a0的H44残基从蛋白活性位点的K41残基形成的。有趣的是，这种糖基化基序不存在于其他物种的CD59中。我们的假设是，由于其独特的H44残基，hCD59的糖基化失活可能代表了高血糖和人类糖尿病血管增生性并发症之间难以捉摸的联系。然而，实践和伦理方面的考虑阻碍了进行临床研究以在人类中全面验证这一假设。因此，我们的策略是确定补体损害糖尿病并发症目标器官的细胞和分子机制，重点是发展分子工程小鼠，现在在我们的实验室中可用。我们将通过STZ注射（1型糖尿病模型）使这些小鼠发生糖尿病，并利用我们上一代mCD59KO小鼠回交Apoe-/-背景，研究hCD59糖化失活在糖尿病心血管疾病中的作用。具体来说，我们将比较糖尿病hCD59野生型（糖基化失活敏感）转基因小鼠和糖尿病hCD59Gln44突变型（糖基化失活抗性）转基因小鼠，在mCd59KO和Apoe-/-背景下。这项工作的成功完成将提供：1)为补体和hCD59糖化失活在糖尿病心血管并发症发病机制中的作用提供明确的证据；2)需要动物模型来研究糖尿病并发症的机制、治疗和预防；3)强有力的证据支持未来对人类补体和糖尿病的研究。

DESCRIPTION (provided by applicant): Chronic high blood sugar levels (hyperglycemia) are responsible for diabetic complications including nephropathy, retinopathy, neuropathy and accelerated atherosclerosis, all major causes of morbidity and mortality in the adult population. However, how hyperglycemia causes diabetic complications is still poorly understood. Extensive clinical studies by us and others indicate that the complement system, a major effector of the immune system and mediator of inflammation, may play a significant role in the pathogenesis of these complications. In particular, we have established that human CD59, a key complement regulatory protein that protects cells from complement-mediated damage, is inhibited by glycation, the non-enzymatic attachment of glucose to proteins. This is because human CD59 contains a glycation motif, formed by its H44 residue at H 5A0 from its K41 residue in the active site of the protein. Interestingly, this glycation motif is not present in CD59 from other species. Our hypothesis is that glycation- inactivation of hCD59 due to its unique H44 residue could represent the elusive link between hyperglycemia and the vascular proliferative complications of human diabetes. However, practical and ethical considerations preclude conducting clinical studies to test this hypothesis comprehensively in humans. Therefore, our strategy to determine the cellular and molecular mechanism by which complement damages the target organs of diabetic complications has focused on developing molecular engineered mice that are now available in our laboratory. We will make these mice diabetic by STZ injection (type 1 diabetes model), and investigate the role of glycation-inactivation of hCD59 in diabetic cardiovascular disease taking advantage of our previous generation of mCD59KO mice backcrossed into the Apoe-/- background. Specifically, we will compare diabetic hCD59 wild type (glycation-inactivation sensitive) transgenic mice with diabetic hCD59Gln44 mutant (glycation- inactivation resistant) transgenic mice, both in a mCd59KO and Apoe-/-background. Successful accomplishment of this work will provide: 1) clear evidence for the role of complement and glycation-inactivation of hCD59 in the pathogenesis of the cardiovascular complications of diabetes; 2) needed animal models to study mechanism, therapy and prevention of diabetic complications; and 3) strong evidence to support future studies on complement and diabetes in humans.