Role of the phosphatidylinositol-3-kinase and extracellular regulated kinase pathways in the induction of hypoxia-inducible factor (HIF)-1 activity and the HIF-1 target vascular endothelial growth factor in ovarian granulosa cells in response to follicle-stimulating hormone.
FSH stimulation of granulosa cells (GCs) results in increased hypoxia-inducible factor (HIF)-1alpha protein levels and HIF-1 activity that is necessary for up-regulation of certain FSH target genes including vascular endothelial growth factor. We report that the role of the phosphatidylinositol (PI)-3-kinase/AKT pathway in increasing HIF-1alpha protein in FSH-stimulated GCs extends beyond an increase in mammalian target of rapamycin-stimulated translation. FSH increases phosphorylation of the AKT target mouse double-minute 2 (MDM2); a phosphomimetic mutation of MDM2 is sufficient to induce HIF-1 activity. The PI3-kinase/AKT target forkhead box-containing protein O subfamily 1 (FOXO1) also effects the accumulation of HIF-1alpha as evidenced by the ability of a constitutively active FOXO1 mutant to inhibit the induction by FSH of HIF-1alpha protein and HIF-1 activity. Activation of the PI3-kinase/AKT pathway in GCs by IGF-I is sufficient to induce HIF-1alpha protein but surprisingly not HIF-1 activity. HIF-1 activity also appears to require a PD98059-sensitive protein (kinase) activity stimulated by FSH that is both distinct from mitogen-activated ERK kinase1/2 or 5 and independent of the PI3-kinase/AKT pathway. These results indicate that FSH-stimulated HIF-1 activation leading to up-regulation of targets such as vascular endothelial growth factor requires not only PI3-kinase/AKT-mediated activation of mammalian target of rapamycin as well as phosphorylation of FOXO1 and possibly MDM2 but also a protein (kinase) activity that is inhibited by the classic ERK kinase inhibitor PD98059 but not ERK1/2 or 5. Thus, regulation of HIF-1 activity in GCs by FSH under normoxic conditions is complex and requires input from multiple signaling pathways.
Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
Hena
H
Alam
Jennifer
J
Weck
Evelyn
E
Maizels
Youngkyu
Y
Park
Eun Jig
EJ
Lee
Margaret
M
Ashcroft
Mary
M
Hunzicker-Dunn
D000818:Animals; D002478:Cells, Cultured; D048049:Extracellular Signal-Regulated MAP Kinases / Q000502:physiology*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology*; D051858:Forkhead Transcription Factors / Q000037:antagonists & inhibitors; D006107:Granulosa Cells / Q000187:drug effects* / Q000378:metabolism; D051793:Hypoxia-Inducible Factor 1 / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000037:antagonists & inhibitors; D010053:Ovary / Q000187:drug effects* / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology*; D010766:Phosphorylation / Q000187:drug effects; D011494:Protein Kinases / Q000502:physiology; D051736:Proto-Oncogene Proteins c-mdm2 / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D058570:TOR Serine-Threonine Kinases; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism*; D000071161:Forkhead Box Protein O1
D048049:Extracellular Signal-Regulated MAP Kinases; D005640:Follicle Stimulating Hormone; D051858:Forkhead Transcription Factors; D051793:Hypoxia-Inducible Factor 1; D007334:Insulin-Like Growth Factor I; D009419:Nerve Tissue Proteins; D019869:Phosphatidylinositol 3-Kinases; D011494:Protein Kinases; D051736:Proto-Oncogene Proteins c-mdm2; D058570:TOR Serine-Threonine Kinases; D042461:Vascular Endothelial Growth Factor A; C467498:vascular endothelial growth factor A, rat; C074639:Foxo1 protein, rat; D000071161:Forkhead Box Protein O1; C497208:Mdm2 protein, rat; C546843:mTOR protein, mouse; C546845:mTOR protein, rat