Human complement C4 isotypes in Lupus

狼疮中的人类补体 C4 同种型

基本信息

批准号：
9206441
负责人：
Michael Craig Carroll
金额：
$ 22.13万
依托单位：
BOSTON CHILDREN'S HOSPITAL
依托单位国家：
美国
项目类别：
财政年份：
2016
资助国家：
美国
起止时间：
2016-01-15 至 2018-04-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9206441
关键词：
Address Affect Alleles Amides Amino Acids Animal Model Antigen-Antibody Complex Antigens Apoptotic Autoimmune Process Autoimmunity B-Lymphocytes Bacteria Binding Carbohydrates Cells Chemicals Complement Complement 1q Complement component C4a Crystallization DNA Sequence Defect Development Erythrocytes Esters Exclusion Frequencies Genes Genetic Genetic study Goals HLA Antigens Haplotypes Histidine Human Humoral Immunities Hybrids Impairment In Vitro Individual Infection Inflammation Influenza A virus Interferon Type I Lead Learning Letters Ligands Lupus Modeling Monoclonal Antibodies Mouse Strains Mus Pathway interactions Phenotype Predisposition Protein Isoforms Proteins Reaction Reagent Role Side Site Streptococcus pneumoniae Structure Structure of germinal center of lymph node Surface Surface Antigens Testing Tissues Viral complement C4d enzyme replacement therapy hydroxyl group in vivo mouse model novel pathogen public health relevance small molecule thioester tool

项目摘要

DESCRIPTION (provided by applicant): The finding that individuals bearing genetic or acquired deficiency in C1q or C4 almost always develop lupus has been referred to as the "Lupus Paradox". Like many loci within the Human Leukocyte Antigen locus (HLA), the complement C4 locus, which is located in the class III region, is highly polymorphic. There are two highly conserved isotypes, C4A and C4B, which encode structural variability in the isotypic region (4 amino acids) which regulate covalent binding of the internal thioester. While the most common haplotype is C4A and C4B, the number of alleles at the C4 locus can vary from 0 to 4. For example, allelic deficiency in C4A or C4B occurs at a frequency of about 4% and 1%, respectively. In contrast to humans, mice express a single functional C4 allele; the DNA sequence of the murine C4 gene in the isotypic region is a hybrid of human C4A and C4B. A key function of C4 is to bind covalently to its target following enzymatic cleavage. C4 is highly reactive once it is activated and studies using small molecule ligands in vitro determined that C4A retains its activity longer and primarily forms amide bonds; whereas, C4B forms ester bonds with the antigen surface. It is predicted that the in vitro chemical difference will have significant effects on C4 function in vivo. The availability of animal models to test the importanc of the two isoforms in vivo would be important to move the field forward. The goal of the current proposal is characterize two novel strains of mice in which the C4 locus was "edited" in the isotypic region to express either C4A or C4B protein. Aim 1: Characterize gene "edited" strains of mice bearing hu C4A or C4B isotypic sequences. We expect to learn from this aim if C4A and C4B differ in their protection of mice against viral and bacterial pathogens. Aim 2: Test the hypothesis that structural differences in the isotypic region of C4 influence protection in a murin model of lupus. We expect to learn from this aim if the C4A protein is more efficient than C4B in clearance of nucleolar antigens and in protection in a murine lupus model. Summary: The successful completion of this study will not only provide valuable reagents and novel tools to push the field forward but could lead to development of protein replacement therapy.

描述（由申请人提供）：C1q 或 C4 具有遗传性或后天性缺陷的个体几乎总是会患上狼疮，这一发现被称为“狼疮悖论”，就像人类白细胞抗原基因座 (HLA) 内的许多基因座一样。 C4位点位于III类区域，具有高度多态性，有两种高度保守的同种型：C4A和C4B，它们编码结构变异。调节内部硫酯共价结合的同种型区域（4 个氨基酸）虽然最常见的单倍型是 C4A 和 C4B，但 C4 基因座的等位基因数量可以从 0 到 4 不等。例如，C4A 或 C4B 中的等位基因缺陷。发生频率分别约为 4% 和 1% 与人类相比，小鼠在 C4 基因中表达单一功能性 C4 等位基因；同种型区域是人 C4A 和 C4B 的杂合体，C4 的一个关键功能是在酶裂解后与其靶标共价结合，一旦被激活，C4 就会具有高反应性，并且使用小分子配体进行的体外研究确定 C4A 可以更长时间地保留其活性。且主要形成酰胺键；而C4B与抗原表面形成酯键，预计体外化学差异将对C4功能在动物模型中的可用性产生显着影响。在体内测试两种亚型的重要性对于推动该领域的发展非常重要，当前提案的目标是表征两种新的小鼠品系，其中 C4 基因座在同种型区域中被“编辑”以表达 C4A 或 C4B。目标 1：表征具有 hu C4A 或 C4B 同种型序列的基因“编辑”小鼠品系，我们希望从该目标中了解 C4A 和 C4B 是否存在差异。目标 2：测试 C4 同种型区域的结构差异影响小鼠狼疮模型的保护作用的假设，我们希望从这一目标中了解 C4A 蛋白是否比 C4B 更有效。摘要：这项研究的成功完成不仅将为推动该领域的发展提供有价值的试剂和新工具，而且可能导致蛋白质替代疗法的发展。