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.

Public Health Relevance

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.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL087216-05
Application #
8288770
Study Section
Special Emphasis Panel (ZRG1-CVS-A (50))
Program Officer
Luksenburg, Harvey
Project Start
2008-09-22
Project End
2014-06-30
Budget Start
2012-07-01
Budget End
2014-06-30
Support Year
5
Fiscal Year
2012
Total Cost
$257,813
Indirect Cost
$59,813
Name
University of Nebraska Lincoln
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
555456995
City
Lincoln
State
NE
Country
United States
Zip Code
68588
Gaudry, Michael J; Storz, Jay F; Butts, Gary Tyler et al. (2014) Repeated evolution of chimeric fusion genes in the ?-globin gene family of laurasiatherian mammals. Genome Biol Evol 6:1219-34
Cheviron, Zachary A; Connaty, Alex D; McClelland, Grant B et al. (2014) Functional genomics of adaptation to hypoxic cold-stress in high-altitude deer mice: transcriptomic plasticity and thermogenic performance. Evolution 68:48-62
Cheviron, Zachary A; Natarajan, Chandrasekhar; Projecto-Garcia, Joana et al. (2014) Integrating evolutionary and functional tests of adaptive hypotheses: a case study of altitudinal differentiation in hemoglobin function in an Andean Sparrow, Zonotrichia capensis. Mol Biol Evol 31:2948-62
Tufts, Danielle M; Revsbech, Inge G; Cheviron, Zachary A et al. (2013) Phenotypic plasticity in blood-oxygen transport in highland and lowland deer mice. J Exp Biol 216:1167-73
Natarajan, Chandrasekhar; Inoguchi, Noriko; Weber, Roy E et al. (2013) Epistasis among adaptive mutations in deer mouse hemoglobin. Science 340:1324-7
Damsgaard, Christian; Storz, Jay F; Hoffmann, Federico G et al. (2013) Hemoglobin isoform differentiation and allosteric regulation of oxygen binding in the turtle, Trachemys scripta. Am J Physiol Regul Integr Comp Physiol 305:R961-7
Weber, Roy E; Fago, Angela; Malte, Hans et al. (2013) Lack of conventional oxygen-linked proton and anion binding sites does not impair allosteric regulation of oxygen binding in dwarf caiman hemoglobin. Am J Physiol Regul Integr Comp Physiol 305:R300-12
Storz, Jay F; Opazo, Juan C; Hoffmann, Federico G (2013) Gene duplication, genome duplication, and the functional diversification of vertebrate globins. Mol Phylogenet Evol 66:469-78
Revsbech, Inge G; Tufts, Danielle M; Projecto-Garcia, Joana et al. (2013) Hemoglobin function and allosteric regulation in semi-fossorial rodents (family Sciuridae) with different altitudinal ranges. J Exp Biol 216:4264-71
Inoguchi, Noriko; Oshlo, Jake R; Natarajan, Chandrasekhar et al. (2013) Deer mouse hemoglobin exhibits a lowered oxygen affinity owing to mobility of the E helix. Acta Crystallogr Sect F Struct Biol Cryst Commun 69:393-8

Showing the most recent 10 out of 30 publications