Genetic Mechanisms Regulating Hypoxia Tolerance in the Brain - Hypoxia represents a critical element in the pathogenesis of many human diseases, such as ischemic
stroke, myocardial infarction and cancer and solid tumors. Understanding the mechanisms regulating hypoxia
tolerance or susceptibility is essential for developing effective strategies for medical interventions. In this
regard, we have generated a hypoxia-tolerant Drosophila melanogaster strain through laboratory-directed
evolution (over >300 generations in descending environmental O2 levels with every several generations),
sequenced their genomes and analyzed them in these flies. In parallel, we took advantage of the natural
experimental evolution of humans in high-altitude regions of the world by sequencing and analyzing the whole
genomes of Ethiopian and Andean highlanders. Through a comparative genomic approach combining our
results with those of others, we obtained a group of evolutionarily conserved genes (28 human/23 Drosophila
genes) that are potentially involved in regulating hypoxia tolerance in human highlanders and hypoxia-tolerant
flies. Indeed, we discovered that ubiquitous knock-down of the expression of genes (Dm/Human), i.e.,
grn/GATA3, Mkk4/MAP2K4, pyd/TJP1, and shep/RBMS3, dramatically enhanced hypoxia tolerance in vivo in
Drosophila. These mechanisms have a strong potential to be translated into novel targets for developing
therapeutic strategies to treat hypoxia-related diseases. Our central hypothesis is that the group of
evolutionary conserved genes regulates hypoxia tolerance in neurons and glial cells in humans. Our
specific aims are: 1) To determine the role of evolutionarily conserved candidate genes (obtained from
our Results in D. melanogaster and human highlanders) in hypoxia tolerance in vivo in whole
organisms. We will determine the role of 23 candidate genes individually in hypoxia tolerance with ubiquitous
or tissue/cell-specific knocking-down or overexpression using UAS/Gal4 system in D. melanogaster, and 2) To
elucidate the role of evolutionarily conserved candidate genes in hypoxia tolerance in human iPSC-derived neuronal and glial cells. We will delineate the specific role of the candidate genes in protecting
human neuronal and glial cells against hypoxia-induced injury by altering their expression using CRISPR/Cas9
system. We believe that this high-risk high-reward project will provide novel information about the mechanisms
underlying hypoxia tolerance or vulnerability.
