CD46: Protecting the Host from Complement Attack

描述（由申请人提供）：膜辅因子蛋白（MCP，CD 46）是一种补体调节蛋白，可结合C3 b和C4 b，并作为其有限蛋白水解降解的辅因子。在过去的资助周期中，一个主要的进展是发现CD 46突变易患非典型溶血性尿毒症综合征（阿胡斯）。这一发现对治疗方案有直接影响，因为肾移植对CD 46缺乏症有治愈作用。这是特别重要的，因为阿胡斯可能是一种危及生命的疾病，在患者（通常是幼儿）中复发，约50%发生肾衰竭。非典型HUS现在被认为是由于补体调节蛋白突变引起的补体失调疾病。我们将讨论CD 46缺乏如何诱发阿胡斯。这项资助的一个主要目标是表征CD 46的原位调节活性。在阿胡斯患者及其家族中，我们将1）建立一种鉴定突变并确定突变蛋白质功能库的设施; 2）使用模型系统（表达突变蛋白的CHO细胞、来自阿胡斯家族的EB病毒转化的人B淋巴细胞和人内皮细胞），原位评估抑制活性; RNAi将用于产生具有特异性抑制剂缺乏状态的细胞; 3）使用scFv-补体调节物嵌合体将抑制剂靶向RBC和内皮细胞，以纠正缺陷并确定最有效的调节物抑制混合物以阻断补体活化; 4）监测调节物的膜运动，因为它们与Ab和病原体交联并响应补体活化。这些特定施舍背后的一个主题是探索宿主限制补体激活改变和损伤的自身细胞的过程。这种现象我们称为TRACS，用于补体系统的靶向和限制性激活，研究很少。我们认为，补体激活自身组织的概况具有独特的目的和独特的功能相比，其激活微生物。我们的长期目标是理解这是如何使用阿胡斯中的CD 46缺陷作为说明性实例来实现的。我们的建议将有助于确定补体调节因子CD 46的缺乏如何导致人类疾病溶血性尿毒综合征，以及开发提供调节因子治疗此类疾病的方法

DESCRIPTION (provided by applicant): Membrane cofactor protein (MCP, CD46) is a complement regulatory protein that binds C3b and C4b and serves as a cofactor for their limited proteolytic degradation. A major development during the past grant cycle was the discovery that mutations in CD46 predispose to atypical hemolytlc uremic syndrome (aHUS). This finding has an immediate impact on treatment options since renal transplantation would be curative in CD46 deficiency. This is especially significant since aHUS can be a life-threatening condition that recurs in patients (usually young children) with about 50% developing renal failure. Atypical HUS is now recognized as a disease of complement deregulation due to mutations in complement regulatory proteins. We will address how CD46 deficiency predisposes to aHUS. A major goal of this grant is to characterize CD46's regulatory activity in situ. In patients with aHUS and their families, we will 1) establish a facility to identify mutations and determine the functional repertoire of the mutant proteins; 2) use model systems (CHO cells expressing the mutant proteins, EB virus transformed human B lymphocytes from aHUS families, and human endothelial cells), assess Inhibitory activity in situ; RNAi will be employed to create cells with a specific inhibitor deficiency state; 3) employ scFv-complement regulator(s) chimeras to target inhibitors to RBCs and endothelial cells in order to correct the deficiency and to define the most potent inhibitory mix of regulators to block complement activation; 4) monitor membrane movements of regulators as they are cross-linked with Abs and pathogens and in response to complement activation. A theme underlying these specific alms is to explore the process whereby the host limits complement activation on altered and injured self cells. This phenomenon we have termed TRACS, for targeted and restricted activation of the complement system, is little studied. We propose that the profile of complement activation on self-tissue has unique purposes and distinct features compared to its activation on microbes. Our long term goal is to understand how this is accomplished using CD46 deficiency In aHUS as the Illustrative example. Our proposal will help define how deficiency of the complement regulator CD46 predisposes to human disease hemolytic uremic syndrome as well as develop ways to deliver regulators to treat such conditions