Mechanisms of Hemoglobin Adaptation to Hypoxia in High-altitude Rodents

该研究项目的目的是阐明 对高海拔缺氧的生理适应，这是一种由降低的 为呼吸组织的细胞提供氧气。具体而言，拟议的研究将 涉及血红蛋白变异结构和功能分析， 随着血液生化和有氧代谢的适应性变化， 鹿鼠（Peromyscus maniculatus）。深入了解了 使高海拔动物能够在慢性缺氧的条件下生存和发挥功能 可以帮助我们理解和管理人类的疾病过程， 危及氧气运输系统通过识别 缺氧耐受性，有可能复制机制与新的药物为基础的 治疗、基因治疗和基于血红蛋白的血液替代品。这种高度 跨学科研究将整合分子群体的工具和理论 遗传学、分子进化、结构生物学和蛋白质生物化学。具体 本研究项目的目的是（1）确定特定的氨基酸突变， 负责血红蛋白适应缺氧;（2）评估是否 血红蛋白结构的改变也与调节有关， 循环红血中不同血红蛋白异构体的组成化学计量 细胞;和（3）评估所观察到的结构和 监管变化。在首次对DNA序列进行了人口水平的调查后， 变异，以确定高海拔地区珠蛋白基因中自然发生的突变， 鹿鼠，这项研究将涉及一个群体遗传分析，以推断哪一个 观察到的氨基酸变化可能归因于积极的达尔文选择， 在mRNA和蛋白质水平上分析调控变异， 计算分析预测对血红蛋白-氧亲和力的影响，以及"体外" 实验分析，以评估所确定的结构和监管变化 影响固有氧亲和力，以及对温度、质子的敏感性（玻尔 效应）、变构效应物以及活性氧和一氧化氮的代谢。 通过识别自然界中进化的血红蛋白适应机制， 高海拔啮齿动物种群，拟议的研究项目应提供新的 深入了解缺氧耐受的分子基础。叙事 拟议研究项目的目标是确定 在高海拔地区出生的小鼠中进化出的血红蛋白功能 环境.通过识别特定的分子机制， 使高海拔动物能够在低氧环境下生存和活动 条件下，有可能在治疗中复制该机制 治疗危害氧气运输系统的人类疾病。

The purpose of the proposed research project is to elucidate the molecular basis of physiological adaptation to high-altitude hypoxia, a condition resulting from a reduced supply of oxygen to the cells of respiring tissues. Specifically, the proposed research will involve a structural and functional analysis of hemoglobin variation that is associated with adaptive variation in the blood biochemistry and aerobic metabolism of high-altitude deer mice (Peromyscus maniculatus). Insights into the molecular mechanisms that allow high-altitude animals to survive and function under conditions of chronic hypoxia can aid our understanding and management of disease processes in humans that compromise the oxygen transport system. By identifying the molecular underpinnings of hypoxia tolerance, it may be possible to replicate the mechanism with novel drug-based therapy, gene therapy, and hemoglobin-based blood substitutes. This highly interdisciplinary study will integrate the tools and theory of molecular population genetics, molecular evolution, structural biology, and protein biochemistry. The specific aims of this research project are (1) To identify the specific amino acid mutations that are responsible for hemoglobin adaptation to hypoxia; (2) To assess whether modifications of hemoglobin structure are also associated with regulatory adjustments in the composition stoichiometry of different hemoglobin isoforms in circulating red blood cells; and (3) To assess the functional consequences of the observed structural and regulatory changes. After first conducting a population-level survey of DNA sequence variation to identify naturally occurring mutations in the globin genes of high-altitude deer mice, this study will involve a population-genetic analysis to infer which of the observed amino-acid changes may be attributable to positive Darwinian selection, an analysis of regulatory variation at the mRNA and protein levels, an 'in silico' computational analysis to predict effects on hemoglobin-oxygen affinity, and an 'in vitro' experimental analysis to assess how the identified structural and regulatory changes influence intrinsic oxygen affinity, as well as sensitivities to temperature, protons (Bohr effect), allosteric effectors, and metabolism of reactive oxygen species and nitric oxide. By identifying mechanisms of hemoglobin adaptation that have evolved in natural populations of high-altitude rodents, the proposed research project should provide novel insights into the molecular basis of hypoxia tolerance. Narrative The goal of the proposed research project is to identify the specific changes in hemoglobin function that have evolved in mice that are native to high-altitude environments. By identifying the specific molecular mechanisms that have enabled high-altitude animals to survive and function under low oxygen conditions, it may be possible to replicate the mechanism in therapeutic treatments of human diseases that compromise the oxygen transport system.