Human Angiotensin II Receptor Gene Regulation

人血管紧张素 II 受体基因调控

• 批准号: 6621718
• 负责人: TERRY S ELTON
• 金额: $ 21.9万
• 依托单位: BRIGHAM YOUNG UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-08-01 至 2003-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6621718
• 关键词: RNA splicing; affinity chromatography; angiotensin II; angiotensin receptor; cell line; fluorescence resonance energy transfer; genetic regulation; genetic transcription; genetic translation; messenger RNA; polymerase chain reaction; protein isoforms; receptor expression; ribosomes; transcription factor; transfection; vascular smooth muscle

Abnormal growth of vascular smooth muscle cells (VSMC) is central to the pathophysiology of various cardiovascular diseases such as atherosclerosis, hypertension and restenosis after angioplasty. These abnormalities can be manifested as changes in the state of VSMC proliferation, differentiation, gene expression patterns and morphology. Currently, the peptide hormone, angiotensin II (Ang II), is believed to play a pivotal role in the development of hypertension and atherosclerosis since it acts as a growth promoting factor in VSMC. The biological responses to Ang II are mediated by its interaction with two distinct high affinity G protein-coupled receptors (GPCRs) now designated AT1R and AT2R. While characterizing the human AT1R (hAT1R) gene, it was demonstrated that human tissues can express at least eight alternatively spliced hAT1R mRNA transcripts which differ only in their 5'-untranslated regions (5'-UTR). Currently, very little is known about the functional significance of each splice variant or how they are regulated. Therefore, the long term goals of this project are to functionally characterize each splice variant and to investigate the molecular mechanisms that govern the expression of these mRNAs. An understanding of these processes is critical since aberrant transcriptional, post- transcriptional and/or translational regulation of hAT1R gene expression may result in the over-expression of the hAT1R which would lead to exaggerated Ang II responsiveness and possibly result in cardiovascular disease. The Specific Aims of this proposal are to: 1) Test the hypothesis that hAT1R mRNA splice variants are differentially expressed in human tissues and investigate the transcriptional regulation of the hAT1R gene by the distal and proximal promoter regions, 2) Test the hypothesis that hAT1R mRNA splice variants have distinct mRNA half-lives, which can be regulated by physiological stimuli, 3) Test the hypothesis that hAT1R mRNA splice variants are translated with different efficiencies, 4) Characterize the internal ribosome entry site (IRES) harbored in exon-1 of the hAT1R mRNA 5'-UTR and identify trans-acting factors which recognize this element, and 5) Test the hypothesis that "long" and "short" hAT1R isoforms can form hetero-dimers and that these hetero-dimers are functionally distinct.

血管平滑肌细胞（VSMC）的异常生长是各种心血管疾病（例如动脉粥样硬化、高血压和血管成形术后再狭窄）的病理生理学的核心。 这些异常可表现为VSMC增殖、分化状态、基因表达模式和形态的改变。 目前，肽类激素血管紧张素 II (Ang II) 被认为在高血压和动脉粥样硬化的发展中发挥着关键作用，因为它充当 VSMC 的生长促进因子。 对 Ang II 的生物反应是通过其与两种不同的高亲和力 G 蛋白偶联受体 (GPCR) 的相互作用介导的，现在称为 AT1R 和 AT2R。 在表征人类 AT1R (hAT1R) 基因时，研究表明人类组织可以表达至少 8 个选择性剪​​接的 hAT1R mRNA 转录物，这些转录物仅在 5'-非翻译区 (5'-UTR) 上有所不同。目前，人们对每个剪接变体的功能意义或它们的调控方式知之甚少。 因此，该项目的长期目标是对每个剪接变体进行功能表征，并研究控制这些 mRNA 表达的分子机制。 了解这些过程至关重要，因为 hAT1R 基因表达的异常转录、转录后和/或翻译调节可能导致 hAT1R 过度表达，从而导致 Ang II 反应过度，并可能导致心血管疾病。 该提案的具体目标是：1) 检验 hAT1R mRNA 剪接变体在人体组织中差异表达的假设，并研究远端和近端启动子区域对 hAT1R 基因的转录调控，2) 检验 hAT1R mRNA 的假设剪接变体具有不同的 mRNA 半衰期，可以通过生理刺激调节，3) 测试 hAT1R mRNA 剪接变体翻译的假设不同的效率，4) 表征 hAT1R mRNA 5'-UTR 外显子 1 中隐藏的内部核糖体进入位点 (IRES)，并识别识别该元件的反式作用因子，以及 5) 检验“长”和“短的 hAT1R 同种型可以形成异二聚体，并且这些异二聚体在功能上是不同的。