Translational Control by Nutrients

营养物质的翻译控制

• 批准号: 6711295
• 负责人: MARIA HATZOGLOU
• 金额: $ 1.89万
• 依托单位: CASE WESTERN RESERVE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-03-15 至 2007-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6711295
• 关键词: aminoacid transport; arginine; biological signal transduction; biotransformation; cell line; conformation; gel mobility shift assay; gene environment interaction; gene expression; genetic mapping; genetic regulation; genetic translation; immunologic techniques; lysine; membrane transport proteins; messenger RNA; molecular cloning; nucleic acid hybridization; nucleic acid sequence; nucleic acid structure; nutrient bioavailability; nutrition related tag; protein biosynthesis; protein purification; tissue /cell culture; translation factor

The mechanism of translational control of the arginine/lysine transporter mRNA by amino acid availability will be studied. The essential amino acids arginine and lysine, are mainly transported via the cat-1 (cationic amino acid transporter 1) protein of the Y+ system. The cat-1 gene is expressed in all cell types and in high levels in proliferating cells, emphasizing the importance of the cat-1 protein for growth and development of mammals. Mammalian cells have developed an adaptive response to changes in amino acid availability. When the amino acid supply is limited, protein synthesis decreases and there are increases in catabolism of cellular proteins, amino acid biosynthesis, and amino acid transport across the plasma membrane. Together these responses provide the amino acids, which are essential for cell survival. A significant part of this adaptive response is the increased expression of the cat-1 gene. This involves the coordinate increases in transcription, mRNA stability and translation, thus enabling the cells to transport the essential amino acids lysine and arginine once they become available. This proposal will study a novel mechanism, used for the synthesis of the cat-1 protein during limited amino acid supply, when global protein synthesis is inhibited. This mechanism involves translation initiation via an internal ribosomal entry sequence (IRES), a mechanism known to regulate translation of viral mRNAs in infected cells. This IRES is found within the 5'-untranslated region of the cat-1 mRNA. The studies proposed will determine the molecular events that lead to increased IRES-mediated translation of the transporter mRNA during amino acid starvation. Our hypothesis is that during amino acid starvation a protein is synthesized which by binding within the 5'-untranslated region of the cat-1 mRNA, mediates an active IRES conformation. We will determine the following: (1) the cell signaling pathway leading to IRES-activation (2) the cis-mRNA sequence/structure for IRES- activity (3) the trans-acting factors that mediate IRES- conformational change and translational activity. Delineation of the molecular mechanisms of regulation of essential amino acid transport into mammalian cells by substrate availability, will be a valuable guide of how to improve human health during catabolic stress conditions.

研究氨基酸有效性对精氨酸/赖氨酸转运体mRNA翻译控制的机制。必需氨基酸精氨酸和赖氨酸主要通过Y+系统的cat-1（阳离子氨基酸转运蛋白1）蛋白进行转运。猫-1基因在所有细胞类型中均有表达，在增殖细胞中表达水平较高，强调了猫-1蛋白对哺乳动物生长发育的重要性。哺乳动物细胞已经对氨基酸可用性的变化产生了适应性反应。当氨基酸供应受限时，蛋白质合成减少，细胞蛋白质分解代谢、氨基酸生物合成和氨基酸跨质膜转运增加。这些反应共同提供了细胞生存所必需的氨基酸。这种适应性反应的一个重要部分是猫-1基因表达的增加。这涉及到转录、mRNA稳定性和翻译的坐标增加，从而使细胞能够在必需氨基酸赖氨酸和精氨酸可用时运输它们。本研究将研究一种新的机制，用于在氨基酸供应有限的情况下，当整体蛋白质合成受到抑制时，猫-1蛋白的合成。该机制涉及通过内部核糖体进入序列（IRES）启动翻译，这是一种在感染细胞中调节病毒mrna翻译的机制。该IRES位于cat-1 mRNA的5'-未翻译区。提出的研究将确定在氨基酸饥饿期间导致ires介导的转运体mRNA翻译增加的分子事件。我们的假设是，在氨基酸饥饿期间，一种蛋白质被合成，该蛋白质通过结合在cat-1 mRNA的5'-非翻译区，介导活跃的IRES构象。我们将确定以下内容：(1)导致IRES激活的细胞信号通路(2)IRES活性的顺式mrna序列/结构(3)介导IRES构象变化和翻译活性的反式作用因子。通过底物有效性来描述必需氨基酸转运进入哺乳动物细胞的调控分子机制，将为如何在分解代谢应激条件下改善人类健康提供有价值的指导。