CD46: Protecting the Host from Complement Attack

描述(由申请人提供)：膜辅因子蛋白(MCP，CD46)是一种补体调节蛋白，结合C3b和C4b，并作为其有限蛋白降解的辅因子。在过去的赠款周期中，一个主要的发展是发现CD46的突变容易患上非典型溶血性尿毒症综合征(AHUS)。这一发现对治疗方案产生了直接影响，因为肾移植可以治愈CD46缺乏症。这一点尤其重要，因为AHUS可能是一种危及生命的疾病，在约50%发展为肾功能衰竭的患者(通常是年幼的儿童)中复发。由于补体调节蛋白的突变，非典型HUS现在被认为是一种补体去调节的疾病。我们将解决CD46缺陷是如何诱发aHUS的。这笔赠款的一个主要目标是表征CD46的S调节活动的原位特征。在aHUS患者及其家属中，我们将1)建立一个设施来鉴定突变和确定突变蛋白的功能谱系；2)使用模型系统(表达突变蛋白的CHO细胞、EB病毒转化的来自aHUS家族的人B淋巴细胞和人内皮细胞)，原位评估抑制活性；将利用RNAi创造具有特定抑制因子缺乏状态的细胞；3)使用单链抗体-补体调节因子(S)嵌合体靶向RBC和内皮细胞的抑制因子，以纠正这一缺陷，并确定最有效的抑制调节剂组合来阻断补体激活；4)监测调节器的膜运动，因为它们与抗体和病原体交联，并对补体激活做出反应。这些特定施舍背后的一个主题是探索宿主限制对改变和受伤的自我细胞的补体激活的过程。这种我们称之为TRACS的现象，即补体系统的靶向和限制性激活，很少被研究。我们认为，补体在自身组织上的激活与其在微生物上的激活相比，具有独特的目的和独特的特征。我们的长期目标是以aHUS的CD46缺乏为例来理解这是如何实现的。我们的建议将有助于确定补体调节因子CD46缺乏如何易患人类疾病溶血性尿毒症综合征，以及开发提供调节因子来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