In vitro localization of TIGR/MYOC in trabecular meshwork extracellular matrix and binding to fibronectin

Invest Ophthalmol Vis Sci. 2002 Jan;43(1):151-61.


Purpose: To determine whether trabecular meshwork-inducible glucocorticoid response/myocilin (TIGR/MYOC) protein associates with the extracellular matrix (ECM) of human trabecular meshwork (HTM) cells.

Methods: The extracellular localization of TIGR/MYOC was examined by immunofluorescence microscopy in HTM cultures treated with and without dexamethasone and ascorbate and in a transformed HTM cell line, TM-1, transiently transfected with TIGR/MYOC cDNA. Antibodies to TIGR/MYOC, fibronectin, laminin, type IV collagen, or thrombospondin were used to determine the extracellular localization of TIGR/MYOC. Solid phase binding assays using 125I-recombinant TIGR/MYOC and types I and IV collagens, fibronectin, and laminin were done to examine the association of TIGR/MYOC with these proteins and to identify a specific TIGR/MYOC binding site within fibronectin. The domains of fibronectin tested were the fibrin/collagen binding domain, the RGD domain, and the Heparin II (Hep II) domain.

Results: TIGR/MYOC colocalized with fibronectin, laminin, and type IV collagen, but not thrombospondin in both dexamethasone and dexamethasone/ascorbate-treated HTM cultures and in TM-1 cultures transfected with TIGR/MYOC cDNA. In solid phase binding assays, 125I-TIGR/MYOC bound fibronectin but not laminin or type IV collagen. Binding to fibronectin could be competed with excess TIGR/MYOC or fibronectin. Specific binding was found for the Hep II domain of fibronectin.

Conclusions: TIGR/MYOC can associate with components of the ECM via interactions with the Hep II domain of fibronectin. The interactions with the Hep II domain of fibronectin could alter cell-matrix interactions in the TM and provides an interesting lead to explore the role(s) of TIGR/MYOC in both steroid-induced and primary open angle glaucoma.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Ascorbic Acid / pharmacology
  • Binding Sites
  • Cells, Cultured
  • Collagen / metabolism
  • Cytoskeletal Proteins
  • Dexamethasone / pharmacology
  • Extracellular Matrix / metabolism*
  • Eye Proteins / genetics
  • Eye Proteins / metabolism*
  • Fibronectins / metabolism*
  • Glycoproteins / genetics
  • Glycoproteins / metabolism*
  • Humans
  • Laminin / metabolism
  • Microscopy, Fluorescence
  • Protein Binding
  • Trabecular Meshwork / cytology
  • Trabecular Meshwork / drug effects
  • Trabecular Meshwork / metabolism*
  • Transfection


  • Cytoskeletal Proteins
  • Eye Proteins
  • Fibronectins
  • Glycoproteins
  • Laminin
  • trabecular meshwork-induced glucocorticoid response protein
  • Dexamethasone
  • Collagen
  • Ascorbic Acid