title: Role of TGFbeta/Smad signaling in gremlin induction of human trabecular meshwork extracellular matrix proteins.
abstract: OBJECTIVE
  The bone morphogenic protein (BMP) antagonist gremlin is elevated in glaucomatous trabecular meshwork (TM) cells and tissues and elevates intraocular pressure (IOP). Gremlin also blocks BMP4 inhibition of transforming growth factor (TGF)-β2 induction of TM extracellular matrix (ECM) proteins. The purpose of this study was to determine whether Gremlin regulates ECM proteins in cultured human TM cells.
  
  
  METHODS
  Human TM cells were treated with recombinant gremlin to determine the effects on ECM gene and protein expression. Expression of the ECM genes FN, COL1, PAI1, and ELN was examined in cultured human TM cells by quantitative RT-PCR and Western immunoblot analysis. TM cells were pretreated with TGFBR inhibitors (LY364947, SB431542 or TGFBR1/TGFB2 siRNAs), inhibitors of the Smad signaling pathway (SIS3 or Smad2/3/4 siRNAs), or CTGF siRNA to identify the signaling pathway(s) involved in gremlin induction of ECM gene and protein expression.
  
  
  RESULTS
  All ECM genes analyzed (FN, COL1, PAI1, and ELN) were induced by gremlin. This gremlin induction of ECM genes and protein expression was blocked by inhibitors of TGFBR and the canonical Smad2/3/4 and CTGF signaling pathways.
  
  
  CONCLUSIONS
  Gremlin employs canonical TGFβ2/Smad signaling to induce ECM genes and proteins in cultured human TM cells. Gremlin also induces both TGFβ2 and CTGF, which can act downstream to mediate some of these ECM changes in TM cells.
authors.affiliation: Department of Cell Biology and Anatomy, North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas 76107, USA.
authors.forename: Anirudh
authors.initials: A
authors.lastname: Sethi
authors.forename: Ankur
authors.initials: A
authors.lastname: Jain
authors.forename: Gulab S
authors.initials: GS
authors.lastname: Zode
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Wordinger
authors.forename: Abbot F
authors.initials: AF
authors.lastname: Clark
mesh_terms: D015153:Blotting, Western; D002478:Cells, Cultured; D055513:Connective Tissue Growth Factor / Q000096:biosynthesis; D016326:Extracellular Matrix Proteins / Q000096:biosynthesis* / Q000235:genetics; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000494:pharmacology*; D009994:Osmolar Concentration; D020033:Protein Isoforms / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D011994:Recombinant Proteins / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology*; D051785:Smad Proteins / Q000378:metabolism*; D013997:Time Factors; D014129:Trabecular Meshwork / Q000166:cytology / Q000378:metabolism*; D053781:Transforming Growth Factor beta2 / Q000378:metabolism*
chemical_list: C526317:CCN2 protein, human; D016326:Extracellular Matrix Proteins; C486399:GREM1 protein, human; D036341:Intercellular Signaling Peptides and Proteins; D020033:Protein Isoforms; D012333:RNA, Messenger; D011994:Recombinant Proteins; D051785:Smad Proteins; D053781:Transforming Growth Factor beta2; D055513:Connective Tissue Growth Factor