Cosmc - A Novel Molecular Chaperone Regulating O-Glycans

Cosmc - 调节 O-聚糖的新型分子伴侣

基本信息

批准号：
7942228
负责人：
RICHARD D CUMMINGS
金额：
$ 7.35万
依托单位：
EMORY UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2009
资助国家：
美国
起止时间：
2009-09-30 至 2010-02-28
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7942228
关键词：
ATP-sepharose Address Amino Acids Animals Antigens Autoimmune Diseases Binding Biochemical Biological Process Cell Extracts Cell Line Cells Colon Carcinoma Common Neoplasm Complementary DNA Complex Defect Development Endothelial Cells Epitopes Future Galactosyltransferases Gene Family Genes Glycoproteins Golgi Apparatus Henoch-Schoenlein Purpura Histology Homologous Gene Human Immunoglobulin A Insecta Integral Membrane Protein Invertebrates Kidney Diseases Knockout Mice Length Link Malignant - descriptor Malignant Epithelial Cell Malignant Neoplasms Mammalian Cell Membrane Messenger RNA Molecular Molecular Chaperones Mucins Mus Mutate Nature Oligosaccharides Pathology Phenotype Polysaccharides Protein Glycosylation Proteins Recombinants Retrieval Role Signal Transduction Structure Syndrome T-Lymphocyte Testing Tissues Tn antigen Tumor Antigens Viral Tumor Antigens base cancer cell disulfide bond glycosyltransferase human disease insight multicatalytic endopeptidase complex novel polypeptide sialosyl-T antigen sialosyl-Tn antigen sugar sugar nucleotide

项目摘要

DESCRIPTION (provided by applicant): Human core 1 beta3-galactosyltransferase (T-synthase) generates the core 1 O-glycan Galbeta1 3GalNAc-alpha1-Ser/Thr or T-antigen, which is a precursor for many extended O-glycans in animal glycoproteins. Lack of T-synthase activity leads to expression of the Tn antigen GalNAc-alpha 1 -Ser/Thr, a common tumor associated antigen. This application arises from our discovery that T-synthase activity in cells requires the co-expression of a unique protein that we termed Cosmc (COre 1 beta3-Gal-T Specific Molecular Chaperone). Cosmc may be a unique chaperone primarily involved in folding and maturation of T-synthase. Cosmc is X-linked (Xq23) and its Cdna predicts a 318 amino acid transmembrane protein (approximately 36.4 kDa polypeptide size) with type-II membrane topology. Both human lymphoblastoid Jurkat and LSC colon carcinoma cell lines contain a normal gene and mRNA encoding T-synthase, but lack T-synthase activity. However, both cell lines contain a mutated, non-functional Cosmc; expression of wild-type Cosmc cDNA in both cell lines restores T-synthase activity and T-antigen expression. In cells lacking Cosmc, newly synthesized T-synthase is targeted to proteasomes for degradation. Cosmc binds ATP, consistent with a chaperone function, and Cosmc is primarily localized in the ER and Tsynthase is primarily in the Golgi. We hypothesize that Cosmc acts as a specific molecular chaperone in assisting the folding, stability, and/or targeting of T-synthase. To test this hypothesis we propose three specific aims. Aim 1 - We will define the subcellular localization of Cosmc and T-synthase and explore the mechanisms of Cosmc localization and its potential chaperone/escort function. Aim 2 - We will define whether Cosmc assists other glycosyltransferases and define its potential interaction with T-synthase and/or other proteins (e.g. chaperones) and ATP. Aim 3 - To define other possible biological functions of Cosmc and directly test our hypothesis, we will generate mice containing conventional and targeted, endothelial cell-specific deletions of Cosmc. An understanding of the structure and function of Cosmc should provide important new insights into the molecular basis of several human diseases, including IgA nephropathy, Tn-Syndrome, Henoch-Schonlein purpura, and malignant transformation associated with Tn antigen expression and lack of T-synthase activity.

描述（由申请人提供）：人核1β3-半乳糖基转移酶（T-合酶）生成核心1 O-Glycan galbeta1 3galnac-alpha1-ser/thr或thr或t-抗原，这是动物糖蛋白中许多延伸的O-聚糖的前体。缺乏T合酶活性导致TN抗原Galnac-Alpha 1 -Ser/Thr（一种相关肿瘤相关的抗原）的表达。该应用是由于我们发现细胞中的T合酶活性需要我们称为COSMC的独特蛋白（Core 1 Beta3-Gal-T特异性分子伴侣）的共表达。 COSMC可能是主要涉及T合酶折叠和成熟的独特伴侣。 COSMC是X连锁的（XQ23），其cDNA预测具有II型膜拓扑的318个氨基酸跨膜蛋白（约36.4 kDa多肽大小）。人淋巴母细胞的Jurkat和LSC结肠癌细胞系都含有正常的基因和编码T合酶的mRNA，但缺乏T合酶活性。但是，这两种细胞系都包含突变的非功能性COSMC。野生型COSMC cDNA在两种细胞系中的表达恢复了T合酶活性和T抗原表达。在缺乏COSMC的细胞中，新合成的T合酶针对蛋白酶体降解。 COSMC结合ATP，与伴侣功能一致，COSMC主要定位在ER中，Tsynthase主要在高尔基体中。我们假设COSMC充当特定的分子伴侣，以帮助T合酶的折叠，稳定性和/或靶向。为了检验这一假设，我们提出了三个具体目标。 AIM 1-我们将定义COSMC和T合酶的亚细胞定位，并探索COSMC定位的机理及其潜在的伴侣/伴随功能。 AIM 2-我们将定义COSMC是否有助于其他糖基转移酶，并定义其与T合酶和/或其他蛋白质（例如伴侣）和ATP的潜在相互作用。目标3-为了定义COSMC的其他可能的生物学功能并直接检验我们的假设，我们将生成包含COSMC的常规和靶向内皮细胞特异性缺失的小鼠。对COSMC的结构和功能的理解应提供对几种人类疾病的分子基础的重要新见解，包括IgA肾病，TN-Syndrome，Henoch-Schonlein purpura以及与TN抗原表达和缺乏T-Synthase活性相关的恶性转化。