October 1997
Volume 38, Issue 11
Free
Articles  |   October 1997
Type XII collagen contributes to diversities in human corneal and limbal extracellular matrices.
Author Affiliations
  • H Wessel
    Department of Ophthalmology, University of Pittsburgh School of Medicine, Pennsylvania, USA.
  • S Anderson
    Department of Ophthalmology, University of Pittsburgh School of Medicine, Pennsylvania, USA.
  • D Fite
    Department of Ophthalmology, University of Pittsburgh School of Medicine, Pennsylvania, USA.
  • E Halvas
    Department of Ophthalmology, University of Pittsburgh School of Medicine, Pennsylvania, USA.
  • J Hempel
    Department of Ophthalmology, University of Pittsburgh School of Medicine, Pennsylvania, USA.
  • N SundarRaj
    Department of Ophthalmology, University of Pittsburgh School of Medicine, Pennsylvania, USA.
Investigative Ophthalmology & Visual Science October 1997, Vol.38, 2408-2422. doi:
  • Views
  • PDF
  • Share
  • Tools
    • Alerts
      ×
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation

      H Wessel, S Anderson, D Fite, E Halvas, J Hempel, N SundarRaj; Type XII collagen contributes to diversities in human corneal and limbal extracellular matrices.. Invest. Ophthalmol. Vis. Sci. 1997;38(11):2408-2422.

      Download citation file:


      © ARVO (1962-2015); The Authors (2016-present)

      ×
  • Supplements
Abstract

PURPOSE: To characterize diversities in the extracelhtlar matrices (ECMs) of the corneal and the surrounding limbal epithelium and stroma. METHODS: Immunohistochemical analyses were employed for screening monoclonal antibodies (mAbs) developed against ECM components of the human corneal epithelial basement membrane (BM) zone. In the current study, mAb BM8 was used as the monospecific probe to characterize its antigen (AgBM8) immunochemically, and to immunoselect a complementary DNA (cDNA) clone encoding AgBM8. Direct biochemical and cDNA sequence analyses were performed for the further characterization of AgBM8. An indirect colloidal gold-conjugated antibody technique was employed for immunoelectron microscopic analysis to study the distribution of AgBM8 in the corneal ECMs. RESULTS: The protein AgBM8, isolated from rabbit corneal stromal and epithelial tissues, was identified as the long-splice variant form of type XII collagen based on its size (approximately 340 kDa disulfide-linked subunits), the presence of collagenous domain(s) and a noncollagenous domain of approximately 300 kDa in its subunit structure, and its internal amino acid sequences. The identity of AgBM8 was further confirmed from the amino acid sequence (517 amino acids) deduced from the sequence of a cDNA immunoselected with mAb BM8. Immunofluorescence analyses indicated that the long form of type XII collagen is present in the ECMs of corneal stroma and in the sclera, as well as in the corneal epithelial BM zone but is absent in the limbal and conjunctival epithelial BM zones. It was not detectable in the subepithelial loose connective tissues in the limbus and in the bulbar conjunctiva. Immunoelectron microscopic analyses indicated that the long variant form of type XII collagen is present in corneal epithelial BM, Bowman's membrane, and the interfibrillar matrix of the corneal stroma. In the stroma, colloidal gold was distributed along the collagen fibrils with a periodicity of 150 to 200 nm. CONCLUSIONS: The long variant form of human type XII collagen, a member of the fibril-associated collagens with interrupted triple helices, referred to as FACITs, contributes to the differences in the BM zones of the cornea and limbus. Although many of the dense connective tissues in adult animals contain the short variant form of type XII collagen, human corneal stroma, the BM zone, and the sclera contain the long variant form as the predominant form of type XII collagen. In the corneal stroma, type XII collagen may be organized along the collagen fibrils in a uniform head-to-tail pattern.

×
×

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.

×