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.
Alam
Hena
H
Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
Weck
Jennifer
J
Maizels
Evelyn
E
Park
Youngkyu
Y
Lee
Eun Jig
EJ
Ashcroft
Margaret
M
Hunzicker-Dunn
Mary
M
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