title: Hypoxia inducible factor regulates the cardiac expression and secretion of apelin.
abstract: Apelin and its G-protein-coupled receptor APJ have various beneficial effects on cardiac function and blood pressure. The mechanisms that regulate apelin gene expression are not known. Because apelin gene expression has been shown to increase in cardiac ischemia, we investigated if apelin (Apln) gene expression was sensitive to hypoxia. Here we show that hypoxia increases the apelin expression in rat myocardium and in cultured cardiomyocytes. Pharmacological activation of hypoxia inducible factor by desferrioxamine (DFO) or expression of a constitutively active form of HIF-1alpha increased apelin expression in cardiomyocyte cultures. The induction of apelin by hypoxia was abolished on transient expression of the HIF inhibitory PAS protein in cardiomyocytes. Increased apelin expression induced by hypoxia or DFO was accompanied by the processing of the cellular storage form proapelin into smaller apelin peptides and increased secretion of these biologically active forms of apelin. In a rat in vivo model, acute myocardial infarction (24 h) led to a transient increase in ventricular apelin mRNA levels. Our results indicate that apelin gene is regulated by hypoxia in cardiac myocytes via the HIF pathway, suggesting a role for apelin as a potential marker for acute cardiac hypoxia with a possible compensatory role in myocardial tissue suffering from oxygen deprivation.
authors.affiliation: Department of Physiology, University of Oulu and Biocenter Oulu, Finland.
authors.forename: Veli-Pekka
authors.initials: VP
authors.lastname: Ronkainen
authors.forename: Jarkko J
authors.initials: JJ
authors.lastname: Ronkainen
authors.forename: Sandra L
authors.initials: SL
authors.lastname: Hänninen
authors.forename: Hanna
authors.initials: H
authors.lastname: Leskinen
authors.forename: Jorge L
authors.initials: JL
authors.lastname: Ruas
authors.forename: Teresa
authors.initials: T
authors.lastname: Pereira
authors.forename: Lorenz
authors.initials: L
authors.lastname: Poellinger
authors.forename: Olli
authors.initials: O
authors.lastname: Vuolteenaho
authors.forename: Pasi
authors.initials: P
authors.lastname: Tavi
mesh_terms: D000818:Animals; D000073861:Apelin; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation / Q000502:physiology*; D000860:Hypoxia / Q000235:genetics; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000502:physiology*; D036341:Intercellular Signaling Peptides and Proteins; D009206:Myocardium / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats
chemical_list: D000073861:Apelin; C498579:Apln protein, rat; D002352:Carrier Proteins; C497444:Hif1a protein, rat; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D036341:Intercellular Signaling Peptides and Proteins; D012333:RNA, Messenger