OGT Overexpression in Women with Lupus

狼疮女性中 OGT 过度表达

基本信息

批准号：
7510078
负责人：
BRUCE C. RICHARDSON
金额：
$ 19.7万
依托单位：
UNIVERSITY OF MICHIGAN AT ANN ARBOR
依托单位国家：
美国
项目类别：
财政年份：
2008
资助国家：
美国
起止时间：
2008-07-01 至 2010-04-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7510078
关键词：
Acetylglucosamine Affect Age Animal Model Autoantibodies Autoimmune Diseases Autoimmunity B-Lymphocytes CD8B1 gene Cell physiology Cells Cessation of life Couples DNA DNA Methylation Development Diabetes Mellitus Disease Epigenetic Process Estrogens Female Flare Frequencies Gene Expression Genes Genetic Gonadal Steroid Hormones Hexosamines Hormonal Risk Factor Human Link Lupus MAPK14 gene MAPK8 gene Messenger RNA Methylation Modification Nerve Degeneration Pathway interactions Patients Pattern Phosphorylation Post-Translational Protein Processing Predisposition Prevalence Production Protein Dephosphorylation Protein Overexpression Proteins Public Health Risk Role Serine Severities Signal Pathway Signal Transduction Signaling Molecule Surveys Systemic Lupus Erythematosus T-Lymphocyte TNFSF5 gene Testing Threonine Time Transgenes Transgenic Mice UDP-N-acetylglucosamine-peptide beta-N-acetylglucosaminyltransferase Woman X Chromosome base bisulfite demethylation disability insight male men prevent

项目摘要

DESCRIPTION (provided by applicant): Lupus afflicts women 9 times more often than men. Estrogen contributes to lupus severity, but does not completely explain the increased risk. Impaired DNA methylation, a repressive epigenetic modification, causes overexpression of T cell genes that contribute to lupus. DNA methylation also silences one X chromosome in women. CD40LG is an X-linked gene known to be overexpressed in lupus and contribute to autoantibody production. We found that CD40LG on the inactive X demethylates and is overexpressed in women but not men with lupus, predisposing women to lupus. Other X-linked genes may also demethylate, predisposing to autoimmunity. We surveyed methylation sensitive T cell genes, and identified O-linked N-acetylglucosamine transferase (OGT) as another X-linked gene overexpressed in demethylated female T cells. OGT couples N-acetylglucosamine (GlcNAc) to serines and threonines in a variety of proteins including signaling molecules, modifying function in a manner analogous to phosphorylation and referred to as the hexosamine signaling pathway (HSP). HSP abnormalities are implicated in diabetes and neurodegeneration, but little is known regarding its role in T cells. We hypothesize that demethylation of OGT on the inactive X results in overexpression in women, altering HSP signaling and contributing to pathogenic T cell function by modifying signaling. We will test this hypothesis by: 1) Comparing OGT mRNA and protein levels in control and demethylated CD4+ and CD8+ T cells from healthy men and women with levels in CD4+ and CD8+ T cells from men and women with inactive lupus, active lupus, and disease/age controls, and confirming OGT demethylation by bisulfite sequencing, 2) Determining if OGT overexpression impairs T cell ERK, JNK and/or p38 pathway signaling and modifies T cell gene expression patterns, and 3) Determining the functional significance of T cell OGT overexpression on the development of autoimmunity using transgenic mice with a T cell specific inducible OGT transgene. These studies will characterize a new pathway regulating T cell gene expression, and characterize how abnormalities in the pathway may predispose women to autoimmunity. PUBLIC HEALTH RELEVANCE: Lupus is an autoimmune disease primarily affecting women, causing disability and sometimes death. The reason women are predisposed to lupus is unknown. Our group has found that a mechanism regulating gene expression, called DNA methylation, is defective in T lymphocytes from lupus patients, causing overexpression of genes that make the cells attack the body. This contributes to lupus in those with the appropriate genetic makeup. Women have 2 X chromosomes, while men have only one. One X chromosome is inactivated by DNA methylation in women to prevent them from expressing the genes twice as much as men. However, genes on the second X chromosome demethylate in women with lupus, causing overexpression of genes that may contribute to their disease. We have found that OGT, an X chromosome gene important in regulating cellular function, doubles expression in T lymphocytes from women when DNA methylation is inhibited. This suggests that OGT may also be overexpressed in women with lupus, contributing to their disease. The studies described in this application will determine if women with lupus overexpress OGT, and determine the functional consequences. The results may provide new insights into mechanisms causing autoimmunity in women, and suggest new ways to treat the disease.

描述（由申请人提供）：女性患狼疮的几率是男性的 9 倍。雌激素会导致狼疮的严重程度，但并不能完全解释风险增加的原因。 DNA 甲基化受损是一种抑制性表观遗传修饰，会导致 T 细胞基因过度表达，从而导致狼疮。 DNA 甲基化还会沉默女性的一条 X 染色体。 CD40LG 是一种 X 连锁基因，已知在狼疮中过度表达并有助于自身抗体的产生。我们发现，不活跃的 X 上的 CD40LG 会去甲基化，并在患有狼疮的女性而非男性中过度表达，从而使女性易患狼疮。其他 X 连锁基因也可能去甲基化，导致自身免疫。我们调查了甲基化敏感的 T 细胞基因，并确定 O-连接 N-乙酰氨基葡萄糖转移酶 (OGT) 是另一种在去甲基化雌性 T 细胞中过度表达的 X-连接基因。 OGT 将 N-乙酰氨基葡萄糖 (GlcNAc) 与多种蛋白质（包括信号分子）中的丝氨酸和苏氨酸偶联，以类似于磷酸化的方式改变功能，称为己糖胺信号传导途径 (HSP)。 HSP 异常与糖尿病和神经退行性疾病有关，但对其在 T 细胞中的作用知之甚少。我们假设失活 X 上的 OGT 去甲基化会导致女性过度表达，从而改变 HSP 信号传导并通过改变信号传导促进致病性 T 细胞功能。我们将通过以下方式检验这一假设：1) 将健康男性和女性的对照和去甲基化 CD4+ 和 CD8+ T 细胞中的 OGT mRNA 和蛋白质水平与患有非活动性狼疮、活动性狼疮和疾病的男性和女性的 CD4+ 和 CD8+ T 细胞中的水平进行比较/年龄对照，并通过亚硫酸氢盐测序确认 OGT 去甲基化，2) 确定 OGT 过度表达是否损害 T 细胞 ERK、JNK 和/或 p38 通路信号传导和修改 T 细胞基因表达模式，以及 3) 使用具有 T 细胞特异性诱导 OGT 转基因的转基因小鼠确定 T 细胞 OGT 过表达对自身免疫发展的功能意义。这些研究将描述调节 T 细胞基因表达的新途径，并描述该途径的异常如何使女性易患自身免疫性疾病。公共卫生相关性：狼疮是一种自身免疫性疾病，主要影响女性，导致残疾，有时甚至死亡。女性易患狼疮的原因尚不清楚。我们的研究小组发现，狼疮患者的 T 淋巴细胞中一种称为 DNA 甲基化的调节基因表达的机制存在缺陷，导致基因过度表达，从而使细胞攻击身体。对于具有适当基因组成的人来说，这会导致狼疮。女性有 2 条 X 染色体，而男性只有 1 条。女性体内的一条 X 染色体因 DNA 甲基化而失活，以防止她们的基因表达量是男性的两倍。然而，患有狼疮的女性第二条 X 染色体上的基因去甲基化，导致可能导致其疾病的基因过度表达。我们发现，当 DNA 甲基化受到抑制时，OGT（一种对调节细胞功能很重要的 X 染色体基因）在女性 T 淋巴细胞中表达加倍。这表明 OGT 也可能在患有狼疮的女性中过度表达，从而导致她们的疾病。本申请中描述的研究将确定患有狼疮的女性是否过度表达 OGT，并确定其功能后果。这些结果可能为导致女性自身免疫的机制提供新的见解，并提出治疗该疾病的新方法。