title: Recombinant BMP4 and BMP7 increase activin A production by up-regulating inhibin βA subunit and furin expression in human granulosa-lutein cells.
abstract: BACKGROUND
  Granulosa cell-derived activins play important roles in the regulation of ovarian functions. To date, there is limited information pertaining to the intracellular regulation, assembly, and secretion of endogenous activin A in human granulosa cells.
  
  
  OBJECTIVE
  The aim of this study was to examine the effects of BMP4 and BMP7 on furin expression and activin A production as well as the underlying mechanisms of action in human granulosa cells.
  
  
  METHODS
  An established immortalized human granulosa cell line (SVOG) and primary granulosa-lutein cells were used as study models. Expression of inhibin subunits and furin as well as activin A accumulation were examined after exposure to recombinant human BMP4 or BMP7. A BMP type I receptor inhibitor (dorsomorphin), a furin inhibitor (Decanoyl-Arg-Val-Lys-Arg-chloromethylketone), and small interfering RNAs targeting SMAD4 and furin were used to verify the specificity of the effects and investigate potential mechanisms.
  
  
  METHODS
  The study was conducted in an academic center.
  
  
  METHODS
  Specific mRNA and protein levels were examined using real time qPCR and Western blot. Activin A levels were measured using enzyme immunoassay.
  
  
  RESULTS
  Treatment with bone morphogenetic protein (BMP) 4 and BMP7 significantly increased furin mRNA and protein, inhibin βA mRNA, and activin A accumulation. Pre-treatment with dorsomorphin or SMAD4 knockdown reversed the stimulatory effects of BMP4 and BMP7 on furin and inhibin βA expression. In addition, furin knockdown or pre-treatment with a furin inhibitor attenuated the BMP4- and BMP7-induced accumulation of activin A.
  
  
  CONCLUSIONS
  Recombinant BMP4 and BMP7 increase the production of bioactive mature activin A by up-regulating both the production and proteolytic processing of inhibin βA subunit in human granulosa cells. The enhancement of inhibin βA subunit processing is attributable to a SMAD-dependent up-regulation of its proprotein convertase, furin. These findings provide a potential mechanism by which theca cells can regulate neighboring granulosa cells in the ovary.
authors.affiliation: Department of Obstetrics and Gynaecology, Child & Family Research Institute, University of British Columbia, Vancouver, Canada V5Z 4H4.
authors.forename: Hsun-Ming
authors.initials: HM
authors.lastname: Chang
authors.forename: Jung-Chien
authors.initials: JC
authors.lastname: Cheng
authors.forename: Christian
authors.initials: C
authors.lastname: Klausen
authors.forename: Peter C K
authors.initials: PC
authors.lastname: Leung
mesh_terms: D028341:Activins / Q000235:genetics* / Q000378:metabolism; D055415:Bone Morphogenetic Protein 4 / Q000494:pharmacology* / Q000502:physiology; D055419:Bone Morphogenetic Protein 7 / Q000494:pharmacology* / Q000502:physiology; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005260:Female; D045683:Furin / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D028322:Inhibin-beta Subunits / Q000235:genetics* / Q000378:metabolism; D008184:Luteal Cells / Q000187:drug effects* / Q000378:metabolism*; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D059748:Proteolysis / Q000187:drug effects; D011994:Recombinant Proteins / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics
chemical_list: C525809:BMP4 protein, human; C525819:BMP7 protein, human; D055415:Bone Morphogenetic Protein 4; D055419:Bone Morphogenetic Protein 7; D011994:Recombinant Proteins; C422405:activin A; C103008:inhibin beta A subunit; D028341:Activins; D028322:Inhibin-beta Subunits; C468731:FURIN protein, human; D045683:Furin