title: HIF-1alpha-targeted pathways are activated by heat acclimation and contribute to acclimation-ischemic cross-tolerance in the heart.
abstract: Hypoxia-inducible factor-1 (HIF-1) is a key regulator of the cellular hypoxic response. We previously showed that HIF-1 activation is essential for heat acclimation (AC) in Caenorhabditis elegans. Metabolic changes in AC rat hearts indicate HIF-1alpha activation in mammals as well. Here we characterize the HIF-1alpha profile and the transcriptional activation of its target genes following AC and following heat stress (HS) in hearts from nonacclimated (C; 24 degrees C) and AC (34 degrees C, 1 mo) rats. We used Western blot and immunohistochemistry to measure HIF-1alpha levels and EMSA and RT-PCR/quantitative RT-PCR to detect expression of the HIF-1alpha-targeted genes, including vascular endothelial growth factor (Vegf), heme oxygenase-1 (HO1), erythropoietin (Epo), and Epo receptor (EpoR). EpoR and Epo mRNA levels were measured to determine systemic effects in the kidneys and cross-tolerance effects in C and AC ischemic hearts (Langendorff, 75% ischemia, 40 min). The results demonstrated that 1) after AC, HIF-1alpha protein levels were increased, 2) HS alone induced transient HIF-1alpha upregulation, and 3) VEGF and HO1 mRNA levels increased after HS, with greater magnitude in the AC hearts. Epo mRNA in AC kidneys and EpoR mRNA in AC hearts were also elevated. In AC hearts, EpoR expression was markedly higher after HS or ischemia. Hearts from AC rats were dramatically protected against infarction after ischemia-perfusion. We conclude that HIF-1 contributes to the acclimation-ischemia cross-tolerance mechanism in the heart by induction of both chronic and inducible adaptive components.
authors.affiliation: Faculty of Dental Medicine, The Hebrew University, Jerusalem, Israel.
authors.forename: Alina
authors.initials: A
authors.lastname: Maloyan
authors.forename: Luba
authors.initials: L
authors.lastname: Eli-Berchoer
authors.forename: Gregg L
authors.initials: GL
authors.lastname: Semenza
authors.forename: Gary
authors.initials: G
authors.lastname: Gerstenblith
authors.forename: Michael D
authors.initials: MD
authors.lastname: Stern
authors.forename: Michal
authors.initials: M
authors.lastname: Horowitz
mesh_terms: D000818:Animals; D015153:Blotting, Western; D001831:Body Temperature; D017173:Caenorhabditis elegans; D002467:Cell Nucleus / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004921:Erythropoietin / Q000378:metabolism; D006321:Heart / Q000502:physiology; D051547:Heme Oxygenase-1 / Q000378:metabolism; D006358:Hot Temperature; D000860:Hypoxia / Q000378:metabolism; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism*; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D007511:Ischemia / Q000378:metabolism; D007668:Kidney / Q000378:metabolism; D008297:Male; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D015233:Models, Statistical; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017467:Receptors, Erythropoietin / Q000378:metabolism; D015427:Reperfusion Injury; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013347:Subcellular Fractions / Q000378:metabolism; D013696:Temperature; D013997:Time Factors; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D015854:Up-Regulation; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
chemical_list: C497444:Hif1a protein, rat; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D012333:RNA, Messenger; D017467:Receptors, Erythropoietin; D042461:Vascular Endothelial Growth Factor A; D004921:Erythropoietin; D051547:Heme Oxygenase-1