PH CONTROL OF PROTEIN SYNTHESIS

蛋白质合成的 pH 控制

• 批准号: 6517551
• 负责人: Peter James Garlick
• 金额: $ 28.98万
• 依托单位: STATE UNIVERSITY NEW YORK STONY BROOK
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-06-01 至 2004-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6517551
• 关键词: acidity /alkalinity; adenosine triphosphate; alkalosis; ammonium chloride; clinical research; creatine phosphate; cyclic aminoacid; extracellular; gene expression; hemodialysis; human subject; intracellular; laboratory rat; liver metabolism; nitrogen; northern blottings; nuclear magnetic resonance spectroscopy; phenylalanine; protein biosynthesis; respiratory acidosis; respiratory oxygen; sodium bicarbonate; translation factor

Patients with renal failure, diabetic ketosis, severe trauma or sepsis often become acidotic. Moreover, they are also susceptible to body protein wasting. Experimental acidosis has been shown to result in negative nitrogen balance, and body protein loss in acidotic patients can be alleviated by normalization of pH. Previous work has concentrated on the effects of pH on protein degradation and no systematic studies have been performed on pH and protein synthesis. However, measurements in animals and human volunteers have shown that both metabolic and respiratory acidosis are associated with depressed rates of synthesis of skeletal muscle protein and serum albumin. The purpose of the present proposal is therefore to characterize the relationship between protein synthesis rates in tissues, especially muscle and liver, of rats and humans in relation to changes in intra- and extracellular pH, to confirm the hypotheses: (i) that changes in blood pH, both by metabolic and respiratory means, modify rates of tissue protein synthesis and gene expression and contribute to the protein wasting of patients with acidosis, and (ii) that these effects of pH operate directly via the intracellular pH and do not involve extracellular mediators such as hormones. The studies will employ measurements of rates of protein synthesis in tissues of rats and human volunteers to characterize the responses to changes in intra- and extracellular pH induced by metabolic and respiratory means and to confirm that these effects are rapid, operate over the full range of pH from acidosis to alkalosis and are independent of oxygen supply. In the animals, the responses of gene expression in the liver will be investigated by determining the levels of mRNA for 3 liver proteins. In particular, the treatments studied will produce different changes in the infra- and extracellular pH. Measurements of intracellular pH will be made by nuclear magnetic resonance, to confirm the hypothesis that changes in protein synthesis are determined by the intracellular rather than extracellular pH. A separate set of studies will be performed in isolated tissues and cells, to determine whether responses to changes in pH are direct or act through circulating hormones. The cellular and molecular mechanisms through peptide chain initiation and initiation factors eIF-2 and eIF-4 will also be identified. Finally, the effect of changes in pH on tissue protein synthesis will be measured in human volunteers and hemodialysis patients, to identify the role of pH control of protein synthesis in health and in protein wasting conditions with abnormalities of pH control.

肾衰竭，糖尿病性酮症，严重创伤或败血症的患者通常会变得酸性。 此外，它们也容易受到身体蛋白质浪费的影响。 实验性酸中毒已被证明会导致负氮平衡，并且酸性患者的身体蛋白质损失可以通过pH归一化来缓解。先前的工作集中在pH对蛋白质降解的影响上，并且在pH和蛋白质合成上没有进行系统研究。 但是，动物和人类志愿者的测量表明，代谢和呼吸酸中毒都与骨骼肌蛋白和血清白蛋白的合成率降低有关。因此，本提案的目的是为了表征组织中蛋白质合成速率，尤其是大鼠和人类的蛋白质合成率与细胞内pH和细胞外pH的变化有关的关系，以证实假设的假设：（i）通过代谢和呼吸道含量的蛋白质蛋白质和基因构成的蛋白质含量，均与呼吸的速度变化，并促进了蛋白质的蛋白质和基因的蛋白质，并贡献了蛋白质的蛋白质，并撰写了贡献蛋白质（促成蛋白质），从而贡献了该蛋白质的贡献，这些蛋白质是贡献的。 pH的作用直接通过细胞内pH起作用，不涉及细胞外介质（例如激素）。这项研究将采用大鼠和人类志愿者组织中蛋白质合成速率的测量，以表征对代谢和呼吸道种手段引起的细胞内和细胞外pH变化的反应，并确认这些作用是快速的，在酸中毒到碱性病到碱的全范围内运作，并且独立于牛根供应。 在动物中，将通过确定3个肝蛋白的mRNA水平来研究肝脏中基因表达的反应。 特别是，所研究的处理将在细胞外pH和细胞外pH中产生不同的变化。细胞内pH的测量将由核磁共振进行，以确认蛋白质合成的变化由细胞内而不是细胞外pH决定的假设。 将在孤立的组织和细胞中进行一系列研究，以确定对pH变化的反应是直接或通过循环激素作用。还将确定通过肽链启动和引发因子EIF-2和EIF-4的细胞和分子机制。 最后，将在人类志愿者和血液透析患者中​​测量pH变化对组织蛋白质合成的影响，以确定pH控制蛋白质合成在健康和蛋白质浪费条件下的作用，并具有pH对照异常。