Involvement of Ca2+-independent phospholipase A2 in the translocation of hypoxia-inducible factor-1alpha to the nucleus under hypoxic conditions.
We investigated the role of Ca2+-independent phospholipase A2 (iPLA2) as well as cytosolic phospholipase A2 (cPLA2) in hypoxia-inducible factor-1 (HIF-1)-dependent gene expression. An inhibitor of both iPLA2 and cPLA2, methyl arachidonyl fluorophosphonate (MAFP), prevented hypoxia-induced erythropoietin mRNA expression without affecting HIF-1alpha accumulation in Hep3B cells. The DNA-binding of HIF-1alpha was suppressed by MAFP as confirmed by luciferase reporter gene assays with the hypoxia response element. Translocation of HIF-1alpha to the nucleus assessed by its presence in the nuclear extracts of cells exposed to hypoxia, was diminished by MAFP. However, hypoxia-dependent gene expression was not affected in mesangial cells obtained from cPLA2alpha null mice. Furthermore, a specific iPLA2 inhibitor, bromoenol lactone, suppressed erythropoietin mRNA expression and HIF-1alpha translocation to the nucleus under hypoxic conditions. Thus, iPLA2, but not cPLA2alpha, may play an important role in regulating the transport of HIF-1alpha to the nucleus.
Osada-Oka
Mayuko
M
Department of Pathological Biochemistry, Kyoto Pharmaceutical University, Kyoto, Japan.
Takahashi
Minoru
M
Akiba
Satoshi
S
Sato
Takashi
T
D021581:Active Transport, Cell Nucleus / Q000187:drug effects; D000818:Animals; D001095:Arachidonic Acids / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D015687:Cell Hypoxia / Q000502:physiology; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism*; D002478:Cells, Cultured; D003600:Cytosol / Q000201:enzymology; D004305:Dose-Response Relationship, Drug; D004921:Erythropoietin / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression / Q000235:genetics; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism*; D015151:Immunoblotting; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D050527:Mesangial Cells / Q000166:cytology / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D063065:Organophosphonates / Q000494:pharmacology; D010741:Phospholipases A / Q000235:genetics / Q000378:metabolism*; D054467:Phospholipases A2; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism
D001095:Arachidonic Acids; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D063065:Organophosphonates; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D042461:Vascular Endothelial Growth Factor A; C104810:methyl arachidonylfluorophosphonate; D004921:Erythropoietin; D008156:Luciferases; D010741:Phospholipases A; D054467:Phospholipases A2; D002118:Calcium