Mechanisms of Hemoglobin Adaptation to Hypoxia in High-altitude Rodents

这项拟议的研究项目的目的是阐明 对高海拔低氧的生理适应，一种由减少的 给呼吸组织的细胞提供氧气。具体而言，拟议的研究将 涉及相关的血红蛋白变异的结构和功能分析 高原地区血液生化和有氧代谢的适应性变化 鹿鼠(Permyscus Manulatus)。对分子机制的洞察 允许高海拔动物在慢性低氧条件下生存和活动 可以帮助我们理解和管理人类的疾病过程 破坏氧气输送系统。通过确定分子基础， 耐缺氧，有可能复制与新型药物为主的机制 治疗、基因治疗和以血红蛋白为基础的血液替代品。如此之高 跨学科研究将整合分子种群的工具和理论 遗传学、分子进化、结构生物学和蛋白质生物化学。具体的 这项研究项目的目的是(1)确定特定的氨基酸突变 负责血红蛋白对缺氧的适应；(2)评估 血红蛋白结构的改变也与 循环红血中不同亚型血红蛋白的组成化学计量 细胞；以及(3)评估观察到的结构和 监管方面的变化。在首先对DNA序列进行种群水平调查之后 识别高海拔地区珠蛋白基因自然发生突变的变异 鹿鼠，这项研究将涉及种群遗传分析，以推断哪些 观察到的氨基酸变化可能归因于达尔文的积极选择，以及 蛋白质和基因表达水平的调控变异分析 计算分析以预测对血红蛋白-氧亲和力和体外效应的影响 评估已确定的结构和监管变化的实验分析 影响固有氧亲和力以及对温度、质子的敏感性(玻尔 作用)，变构效应，以及活性氧物种和一氧化氮的代谢。 通过识别在自然界中进化的血红蛋白适应机制 高海拔啮齿动物种群，建议的研究项目应提供新的 对耐低氧的分子基础的洞察。叙述性 拟议研究项目的目标是确定在 在高海拔地区的小鼠体内进化出的血红蛋白功能 环境。通过确定特定的分子机制， 使高海拔动物能够在低氧环境下生存和活动 条件下，有可能复制这一机制在治疗 对危害氧气运输系统的人类疾病的治疗。

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.