Regulation of Protein Synthesis and Erythropoiesis

我们的长期目标是有助于理解血红蛋白合成的调节和 在正常和异常的血液学条件下的红系分化，特别强调 血红素和蛋白质合成在这些过程中的作用。完整网织红细胞的蛋白质合成及其功能 裂解产物依赖于血红素的可用性。血红素是血红蛋白的修饰基， 红细胞及其晚期前体细胞中的主要蛋白质。生化研究表明 在缺Heine或缺铁的情况下，蛋白质合成在以下水平受到抑制 由于血红素调节的翻译抑制物(HRI)的激活而启动。HRI是一种受血红素调控的 使真核生物起始因子2(EIF2a)的ct亚单位磷酸化的蛋白激酶。磷酸化 Eif2的ct亚基在翻译启动过程中会损害其循环，导致蛋白质的停止。 综合。研究设计为：(1)阐明HRI调控红色的分子机制 血细胞生成，(2)评估HRI在红细胞疾病中的保护作用，以及(3) 阐明HRI应激激活的分子机制。要采用的方法是 转基因小鼠的产生、血液学分析、组织学和电子显微镜观察 红系祖细胞集落培养检测、蛋白印迹分析和蛋白激酶 检测、细胞培养、小鼠胚胎表型检测、重组DNA技术。我们最近 研究表明，HRI不仅是珠蛋白合成所必需的，也是Heine生物合成所必需的。HRI也是 对地中海贫血和红细胞生成性原畸形症小鼠的生存很重要。我们建议的研究 可能导致HRI在治疗人类红细胞病患者方面的潜在应用。

Our long-term objective is to contribute to the understanding of the regulation of hemoglobin synthesis and erythroid differentiation in normal and abnormal hematological conditions, with particular emphasis on the roles of heme and protein synthesis in these processes. Protein synthesis in intact reticulocytes and their lysates is dependent on the availability of heme. Heme serves as the prosthetic group of the hemoglobin, the predominant protein in red blood cell (RBC) and its late precursor cells. Biochemical studies have shown that, under conditions of heine-deficiency or iron-deficiency, protein synthesis is inhibited at the level of initiation due to the activation of the heme-regulated translational inhibitor (HRI). HRI is a heme-regulated protein kinasc that phosphorylates the ct-subunit of eukaryotic initiation factor 2 (eIF2a). Phosphorylation of the ct-subunit of eIF2 impairs its recycling in translational initiation and results in the cessation of protein synthesis. The research designs are (1) To Elucidate the Molecular Mechanism by which HRI Regulates Red Blood Cell Production, (2) To Assess the Protective Role of HRI in Red Blood Cell Disorders, and (3) To Delineate the Molecular Mechanism of Stress-Activation of HRI. The methods to be employed are the generation of genetically modified mice, hematological analysis, histological and electron microscopic examinations, colony culture assays for erythroid progenitors, Western-blot analysis and protein kinase assays, cell culture, phenotypic examination of mouse embryos, recombinant DNA techniques. Our recent study indicate that HRI is not only necessary for globin synthesis, but also for heine biosynthesis. HRI is also important for the survival of mice with thalassemia and erythropoietic protoporphria. Our proposed study may lead to potential application of HRI in treating human patients with red cell diseases.