title: Cellular fibronectin expression in human trabecular meshwork and induction by transforming growth factor-β2.
abstract: OBJECTIVE
  Levels of TGF-β2 are higher in POAG aqueous humor, causing deposition of extracellular matrix (ECM) proteins, including fibronectin (FN), in the glaucomatous human trabecular meshwork (HTM) that may be responsible for elevated IOP. The purpose of this study was to identify the expression of cellular FN (cFN) isoforms (EDA and EDB) in HTM cells and tissues, and to determine whether TGF-β2 can induce cFN expression and fibril formation in cultured HTM cells.
  
  
  METHODS
  Expression of cFN mRNA isoforms and induction by recombinant TGF-β2 (5 ng/mL) were determined by quantitative RT-PCR. The TGF-β2 induction of EDA isoform protein expression and FN fibril formation were analyzed using Western immunoblots and immunocytochemistry (ICC), respectively. Immunohistochemistry (IHC) analysis was used to examine total FN and EDA isoform expression in normal (NTM) and glaucomatous (GTM) trabecular meshwork (TM) tissues.
  
  
  RESULTS
  Both cFN mRNA isoforms were expressed in cultured HTM cells and were induced by TGF-β2 after 2, 4, and 7 days (P < 0.05). Similarly, EDA isoform protein and fibril formation were increased after 4 and 7 days of TGF-β2 treatment. Finally, GTM tissues had significantly greater EDA isoform protein levels (1.7-fold, P < 0.05) compared to NTM tissues.
  
  
  CONCLUSIONS
  This study demonstrated that cFN isoforms are expressed and induced in HTM cells by TGF-β2. Also, increased EDA isoform protein levels were seen in GTM tissues. Our findings suggest that induction of cFN isoform expression in the TM ECM may be a novel pathologic mechanism involved in the TM changes associated with glaucoma.
authors.affiliation: Department of Cell Biology and Anatomy, and the North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas.
authors.forename: Wanda E
authors.initials: WE
authors.lastname: Medina-Ortiz
authors.forename: Ricardo
authors.initials: R
authors.lastname: Belmares
authors.forename: Sandra
authors.initials: S
authors.lastname: Neubauer
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; D005353:Fibronectins / Q000096:biosynthesis / Q000187:drug effects / Q000235:genetics*; D005786:Gene Expression Regulation; D005901:Glaucoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014129:Trabecular Meshwork / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D053781:Transforming Growth Factor beta2 / Q000494:pharmacology*
chemical_list: D005353:Fibronectins; D012333:RNA, Messenger; D053781:Transforming Growth Factor beta2
keywords: TGF-β2; fibronectin; glaucoma; trabecular meshwork
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