title: Molecular basis of bone morphogenetic protein-15 signaling in granulosa cells.
abstract: Bone morphogenetic protein-15 (BMP-15), an oocyte growth factor belonging to the transforming growth factor-beta superfamily, has recently been shown to be necessary for normal female fertility in mammals. We have previously demonstrated that BMP-15 regulates granulosa cell (GC) proliferation and differentiation; namely, BMP-15 promotes GC mitosis, suppresses follicle-stimulating hormone (FSH) receptor expression, and stimulates kit ligand expression. Although the role of BMP-15 in female reproduction has progressively deserved much attention, there is nothing known to date about the signaling pathway and receptors for BMP-15. Using rat primary GCs and a human GC cell line, COV434, we have now found that administration of BMP-15 causes a rapid and transient phosphorylation, thus activation, of the Smad1/5/8 pathway. BMP-15 also stimulated promoter activity of a selective BMP-responsive reporter construct, further demonstrating the stimulation of Smad1/5/8 signaling by BMP-15. In contrast, BMP-15 stimulation of Smad2 phosphorylation was very weak. To identify the receptors for BMP-15, we utilized recombinant extracellular domains of individual transforming growth factor-beta superfamily receptors and found that activin receptor-like kinase-6 extracellular domain most effectively co-immunoprecipitates with BMP-15, whereas BMP receptor type II extracellular domain was most effective in inhibiting BMP-15 bioactivity on FSH-induced progesterone production and GC thymidine incorporation. We also investigated whether activation of the MAPK pathway is necessary for BMP-15 biological activity and found that the addition of U0126, an inhibitor of ERK1/2 phosphorylation, suppresses BMP-15 activity on GC mitotsis but not on FSH-induced progesterone production, suggesting a selective signaling cascade in GC proliferation and differentiation.
authors.affiliation: Department of Reproductive Medicine, University of California San Diego, School of Medicine, La Jolla, California 92093-0633, USA.
authors.forename: R Kelly
authors.initials: RK
authors.lastname: Moore
authors.forename: Fumio
authors.initials: F
authors.lastname: Otsuka
authors.forename: Shunichi
authors.initials: S
authors.lastname: Shimasaki
mesh_terms: D030201:Activin Receptors, Type I / Q000235:genetics / Q000378:metabolism; D028341:Activins / Q000378:metabolism; D000818:Animals; D055430:Bone Morphogenetic Protein 15; D052005:Bone Morphogenetic Protein Receptors, Type I; D052006:Bone Morphogenetic Protein Receptors, Type II; D002070:Butadienes / Q000494:pharmacology; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005640:Follicle Stimulating Hormone / Q000378:metabolism; D017930:Genes, Reporter; D006107:Granulosa Cells / Q000187:drug effects / Q000502:physiology*; D055429:Growth Differentiation Factor 9; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009570:Nitriles / Q000494:pharmacology; D053764:Presenilin-1; D011374:Progesterone / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D051381:Rats; D017207:Rats, Sprague-Dawley; D017978:Receptors, Growth Factor; D018125:Receptors, Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D051785:Smad Proteins; D051898:Smad1 Protein; D013936:Thymidine / Q000378:metabolism; D015534:Trans-Activators / Q000378:metabolism
chemical_list: C525901:BMP15 protein, human; C525904:Bmp15 protein, rat; D055430:Bone Morphogenetic Protein 15; D002070:Butadienes; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; C525897:GDF9 protein, human; C525899:Gdf9 protein, rat; D055429:Growth Differentiation Factor 9; D036341:Intercellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D009570:Nitriles; C508853:PSEN1 protein, human; D053764:Presenilin-1; D017978:Receptors, Growth Factor; D018125:Receptors, Transforming Growth Factor beta; D011993:Recombinant Fusion Proteins; C497399:SMAD1 protein, human; D051785:Smad Proteins; D051898:Smad1 Protein; C497400:Smad1 protein, rat; D015534:Trans-Activators; C113580:U 0126; D028341:Activins; D011374:Progesterone; D005640:Follicle Stimulating Hormone; D017346:Protein Serine-Threonine Kinases; D020928:Mitogen-Activated Protein Kinases; D030201:Activin Receptors, Type I; C498218:BMPR2 protein, human; C498220:Bmpr2 protein, rat; D052005:Bone Morphogenetic Protein Receptors, Type I; D052006:Bone Morphogenetic Protein Receptors, Type II; D013936:Thymidine