Human Angiotensin II Receptor Gene Regulation

人血管紧张素 II 受体基因调控

• 批准号: 6436185
• 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 2005-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6436185
• 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）的异常生长是动脉粥样硬化、高血压和血管成形术后再狭窄等各种心血管疾病的病理生理机制的核心。这些异常可以表现为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起关键作用，因为它是VSMC的生长促进因子。对Ang II的生物学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，这些转录物仅在它们的5'-非翻译区（5'-UTR）不同。目前，人们对每个剪接变体的功能意义以及它们是如何被调节的知之甚少。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/或翻译调控可能导致hAT1R过表达，从而导致Ang II反应性夸大，并可能导致心血管疾病。本建议的具体目标是：1)验证hAT1R mRNA剪接变异体在人体组织中存在差异表达的假设，并研究远端启动子区和近端启动子区对hAT1R基因的转录调控；2)验证hAT1R mRNA剪接变异体具有不同的mRNA半衰期，可受生理刺激调节；3)验证hAT1R mRNA剪接变异体翻译效率不同的假设。4)表征hAT1R mRNA 5'-UTR外显子1中的内部核糖体进入位点（IRES），并鉴定识别该元件的反式作用因子；5)验证“长”和“短”hAT1R异构体可以形成异二聚体的假设，并且这些异二聚体在功能上是不同的。