REGULATION OF CD154 EXPRESSION

CD154表达的调节

• 批准号: 7094258
• 负责人: WILLIAM FREDERICK CARSON RIGBY
• 金额: $ 31.07万
• 依托单位: DARTMOUTH COLLEGE
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-07-01 至 2008-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7094258
• 关键词: CD40 molecule; RNA binding protein; RNA splicing; cell line; clinical research; genetic regulatory element; helper T lymphocyte; homopolynucleotide; human subject; immunoregulation; laboratory mouse; leukocyte activation /transformation; ligands; messenger RNA; nucleic acid metabolism; protein isoforms; pyrimidines

DESCRIPTION (provided by applicant): CD154 (CD40 ligand) expression by activated T cells plays a central role in the immune response. As such, CD154 expression has been implicated as a major target in the treatment of rheumatic diseases and validated by the demonstrated efficacy of CD154 blockade in animal models of Rheumatoid Arthritis and Systemic Lupus Erythematosus. Furthermore, CD154 gene expression is dysregulated in patients with Systemic Lupus Erythematosus. CD 154 (CD40 ligand) expression exhibits a unique pattern of regulation relative to cytokines. These studies have directly implicated CD154 mRNA degradation. We have established that a polypyrimidine-rich region in the 3'UTR of the CD154 mRNA is necessary and sufficient to reduce chimeric reporter gene expression in both cell lines and normal human CD4+ T lymphocytes, thus identifying this region as a cis-acting element. Furthermore, we have identified two proteins that bind to this polypyrimidine-rich region as distinct splice isoforms (PTB, PTB-T) of the PTB gene. This finding suggest that these proteins are trans-acting factors that determine the function of this region in mRNA decay. Overexpression of the novel smaller splice isoform we call PTB-T, consistently inhibits reporter gene expression in a CD154 3'UWR specific manner in normal human CD4+ T lymphocytes and cell lines. These data suggest the hypothesis that PTB-T interacts with the polypyrimidine-rich region in the CD154 3'UTR to mediate mRNA degradation. We propose to directly test this hypothesis as well as determine the biologic role of PTB-T in the modulation of CD154 mRNA stability. Subsequently, we will identify the pathway(s) by which PTB-T mediates these effects. In this manner, we will functionally delineate the molecular mechanism(s) which regulate CD154 mRNA turnover in vivo and determine their contribution to the unique pattern of CD154 gene regulation as well as the immune response. These studies will generate insights important for the development of approaches that will selectively modulate CD154 expression.

描述（由申请人提供）：活化T细胞表达的CD154（CD40配体）在免疫反应中发挥核心作用。因此，CD154 表达已被认为是治疗风湿性疾病的主要靶点，并通过类风湿关节炎和系统性红斑狼疮动物模型中 CD154 阻断的功效得到验证。此外，系统性红斑狼疮患者的 CD154 基因表达失调。 CD 154（CD40 配体）表达表现出相对于细胞因子的独特调节模式。这些研究直接暗示了 CD154 mRNA 的降解。我们已经确定，CD154 mRNA 3'UTR 中富含多聚嘧啶的区域对于减少细胞系和正常人 CD4+ T 淋巴细胞中的嵌合报告基因表达是必要且充分的，因此将该区域鉴定为顺式作用元件。此外，我们还鉴定了两种与该富含多聚嘧啶的区域结合的蛋白质，作为 PTB 基因的不同剪接亚型（PTB、PTB-T）。这一发现表明这些蛋白质是反式作用因子，决定了该区域在 mRNA 衰变中的功能。我们称为 PTB-T 的新型较小剪接异构体的过表达，在正常人 CD4+ T 淋巴细胞和细胞系中以 CD154 3'UWR 特异性方式持续抑制报告基因表达。 这些数据表明，PTB-T 与 CD154 3'UTR 中富含多聚嘧啶的区域相互作用以介导 mRNA 降解。我们建议直接检验这一假设并确定 PTB-T 在调节 CD154 mRNA 稳定性中的生物学作用。随后，我们将确定 PTB-T 介导这些效应的途径。通过这种方式，我们将从功能上描述调节体内 CD154 mRNA 周转的分子机制，并确定它们对 CD154 基因调节的独特模式以及免疫反应的贡献。这些研究将为开发选择性调节 CD154 表达的方法提供重要的见解。