Changes in Histone Isoform Abundance and Histone Post-Translational Modifications during Anoxia Tolerance and Recovery in WS40NE cells of Austrofundulus limnaeus

Abstract

Anoxia is an often-lethal stressor to vertebrates, yet some vertebrates have adapted cellular mechanisms to survive in anoxic conditions. Embryos of the annual killifish Austrofundulus limnaeus have the greatest tolerance to anoxia of all vertebrates, yet the epigenetic mechanisms that support their anoxia tolerance are unknown. Using mass spectrometry, 1043 unique biologically relevant histone post-translational modifications (unimod+histone residue) were detected in WS40NE cells, representing thirteen types of biologically relevant histone post-translational modifications (hPTMs) present during normoxia, 1 d anoxia, 4 d anoxia, and aerobic recovery from anoxia. Of these 1043 hPTMs, 816 were significantly differentially expressed in at least one comparison. Thirty-six significant hPTMs were considered highly condition dependent. Additionally, at least four histone isoforms were differentially expressed, representing H2A, H2B, and H3 isoforms. Our data suggests that specific histone modifications as well as changes in histone isoform abundance in WS40NE cells may be necessary to successfully respond to extreme changes in oxygen availability.