Genetic Basis of Non-Familial IgA Nephropathy

非家族性 IgA 肾病的遗传基础

• 批准号: 8088062
• 负责人: Tongzhong Ju
• 金额: $ 29.99万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-06-16 至 2013-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8088062
• 关键词: 7p13; Address; Amino Acids; Anabolism; Antibodies; Antigens; Autoantibodies; Autoimmune Diseases; B-Lymphocytes; Binding; Biological Assay; Blood Cells; CD19 gene; Cell Line; Cell surface; Cells; Complementary DNA; Deposition; Diagnosis; Embryo; Enzyme-Linked Immunosorbent Assay; Enzymes; Evaluation; Exons; Galactose; Galactosyltransferases; Genes; Genetic; Glomerulonephritis; Glycopeptides; Glycoproteins; Goals; Health; Hematopoietic stem cells; Human; IGA Glomerulonephritis; IgA1; Immunoglobulin A; Immunoglobulins; In Vitro; Inflammation; Kidney Diseases; Kidney Failure; Light; Link; Mammals; Maps; Masks; Membrane Glycoproteins; Methods; Molecular; Molecular Chaperones; Mono-S; Mus; Mutate; Mutation; O-Glycans Biosynthesis Pathway; Pathogenesis; Pathway interactions; Patients; Peripheral B-Lymphocyte; Peripheral Blood Lymphocyte; Plasma Cells; Polysaccharides; Prevention; Proteins; Recombinants; Sampling; Serum; Severities; Site; Somatic Mutation; Structure; Syndrome; Testing; Tn antigen; Tumor Cell Line; Xq24; base; glycosylation; in vivo; inhibitor/antagonist; insight; multicatalytic endopeptidase complex; novel; novel diagnostics; novel therapeutic intervention; novel therapeutics; peripheral blood; prevent; sialosyl-Tn antigen

DESCRIPTION (provided by applicant): Immunoglobulin A (IgA) nephropathy (IgAN) or Berger's disease is an autoimmune disease resulting from the abnormal deposit of IgA in the glomerulus. Primary IgAN is the most common form of primary glomerulonephritis, leading to progressive renal failure in almost one third of the patients. Numerous studies have suggested that IgAN results from abnormal O-glycosylation of IgA1. Normal IgA1 is unique among immunoglobulins in that it contains ~5 Ser/Thr-linked O-glycans with mono-sialylated and di-sialylated core 1 structures. The pathogenesis of the IgAN is associated with a deficiency of galactose in O-glycans and concomitant expression of the Tn antigen (GalNAc?-Ser/Thr) in its hinge region of IgA1. Tn antigen is normally masked through addition of galactose by the T-synthase to generate the core 1 structure (Gal(3GalNAc-R). We discovered that T-synthase requires a unique molecular chaperone we termed Cosmc that helps to fold the T-synthase during its biosynthesis in the ER. Cosmc is encoded on Xq24 and is an ER chaperone that prevents the aggregation/proteasomal degradation of the T-synthase. Preliminary studies show that somatic mutations in Cosmc cause expression of the Tn antigen. We now hypothesize that somatic mutations of Cosmc in IgA-secreting B cells cause undergalactosylation of IgA1 and result in non-familial or sporadic IgAN. In this proposal, we will focus on three Specific Aims. Aim 1: We will analyze Cosmc in Tn/CD19(+) B lymphocytes from peripheral blood of patient with IgAN. For all mutations found, the effects of mutation on Cosmc chaperone toward the T-synthase will be examined by in vitro complementation assays. We will isolate, immortalize and establish the Tn/CD19(+) or Tn/IgA(+) Blymphocytes from patients with IgAN, examine the cDNA and gene for Cosmc; introduce wild type Cosmc into the B cells to restore T-synthase activity; and test whether Cosmc expression corrects O-glycosylation of cell surface glycoproteins and IgA1. Aim 2: We will define the structures of O-glycans on each site of the hinge region in IgA from patients with IgAN. Aim 3: We will characterize the autoantibodies in sera of patients with IgAN using a glycan microarray including various glycans and synthetic glycopeptides representing the IgA1 hinge region, and establish an ELISA method for potential diagnosis of IgAN from serum samples. Understanding the genetic basis for IgAN will shed light on developing new diagnostics and therapeutic treatments for IgAN. PUBLIC HEALTH RELEVANCE Our goal of this project is to investigate the genetic basis or molecular mechanism of non-familial IgA nephropathy (IgAN), the most common form of primary glomerulonephritis leading to progressive renal failure in almost one third of the patients. IgAN is caused by the deposit of IgA1 in glomerulus because the IgA1 carries aberrant O-glycans such as Tn antigen. O-glycan biosynthesis is regulated by Cosmc, core 1 (3-galactosyltransferase specific molecular chaperone, through assisting the folding of core 1 (3- galactosyltrasferase (T-synthase) which is a key enzyme guarding the pathway. Human Cosmc is encoded by a single-Exon gene Cosmc on Xq24. Somatic mutation in Cosmc is responsible for the abnormal expression of Tn and sialylTn antigens in human tumor cell lines and blood cells of patients with Tn syndrome. We hypothesize that the somatic mutation of X-linked Cosmc in IgA1 secreting B cell is associated with IgAN. To test our hypothesis, we will focus on three Aims for this proposal: 1) Examine Cosmc gene in Tn(+), IgA1 secreting B cells or plasma cells isolated from patients with IgAN and matched healthy controls; examine the Cosmc gene from immortalized Tn(+), IgA1 secreting B cells or plasma cells; correct the O-glycan structure on IgA1 by introducing the wild type Cosmc into these cells; 2) Define the O-glycan structure on each site of hinge region in IgA1; 3) Characterize the autoimmune antibody in sera of patients with IgAN. These studies will directly address the molecular mechanism of IgAN, which will have an important impact on our understanding of the pathogenesis of IgA1, and provide new diagnostics and avenues of treatment or prevention for sporadic IgAN.

描述（由申请人提供）：免疫球蛋白A（IGA）肾病（IGAN）或Berger病是一种自身免疫性疾病，是由于IgA异常沉积在肾小球中。原发性IGAN是原发性肾小球肾炎的最常见形式，导致近三分之一的患者进行性肾衰竭。大量研究表明，Igan是由IgA1异常的O-糖基化引起的。正常IgA1在免疫球蛋白中是独一无二的，因为它包含约5个ser/th-th-cind-cind-con-glycans，其单溶解和二酰亚化的核心1结构。 Igan的发病机理与O-Glycans中半乳糖的缺乏以及TN抗原（​​Galnac？-ser/Thr）在其IgA1的铰链区域的同时表达有关。通常，通过T-synthase添加半乳糖来生成核心1结构（GAL（3GALNAC-R）。我们发现T-伴侣需要我们称为独特的分子伴侣COSMC，从而帮助折叠t-synthase在IS的生物合成过程中，我们称为thenthase insermc insermc endernemoded osnemoded， T-Anthase的聚集/蛋白酶体的降解表明，COSMC中的体细胞突变会导致TN抗原的表达。我们将分析来自IGAN患者的TN/CD19（+）B淋巴细胞。患有IGAN的患者，检查COSMC的cDNA和基因；将野生型COSMC引入B细胞中以恢复T合酶活性。并测试COSMC表达是否校正细胞表面糖蛋白和IGA1的O-糖基化。 AIM 2：我们将定义IgA患者IgA中铰链区域的每个位点上的O-聚糖结构。 AIM 3：我们将使用一个聚糖微阵列（包括各种聚糖和代表IGA1铰链区域的合成糖肽）来表征IGAN患者血清中的自身抗体，并建立了一种潜在的ELISA方法，以潜在地诊断出从血清样品中诊断出Igan。了解IGAN的遗传基础将阐明为Igan开发新的诊断和治疗治疗。 公共卫生相关性我们的目标是研究非家庭IgA肾病（IGAN）的遗传基础或分子机制，这是原发性肾小球肾炎最常见的形式，导致近三分之一患者的肾脏肾衰竭。 Igan是由IgA1沉积在肾小球中引起的，因为IgA1带有异常的O-聚糖，例如TN抗原。 O-glycan biosynthesis is regulated by Cosmc, core 1 (3-galactosyltransferase specific molecular chaperone, through assisting the folding of core 1 (3- galactosyltrasferase (T-synthase) which is a key enzyme guarding the pathway. Human Cosmc is encoded by a single-Exon gene Cosmc on Xq24. Somatic mutation in Cosmc is responsible for the人类肿瘤细胞系中Tn和siAlltn抗原的异常表达，我们假设在IgA1分泌B细胞中X-C-COSMC的体细胞突变与IGAN相关，我们将重点介绍三个细胞。从IGAN和健康对照中分离出来；从永生的TN（+），IgA1分泌的B细胞或浆细胞中，将野生型COSMC纠正IgA1上的O-Glycan结构； 3）表征IGAN患者血清中的自身免疫性抗体。这些研究将直接解决Igan的分子机制，这将对我们对IGA1发病机理的理解产生重要影响，并为零星Igan提供新的诊断和治疗或预防途径。