Discrete expression and distribution pattern of TIMP-3 in the human retina and choroid

Janice A. Vranka, Elaine Johnson, Xianghong Zhu, Amy Shepardson, J. Preston Alexander, John M.B. Bradley, Mary K. Wirtz, Richard G. Weleber, Michael L. Klein, Ted S. Acott

Research output: Contribution to journalArticle

57 Scopus citations

Abstract

Purpose. Extracellular matrix homeostasis is dependent in part upon a family of matrix metalloproteinases and their specific inhibitors, the tissue inhibitors of metalloproteinases (TIMPs). Recently, gene defects in TIMP-3 have been identified in the affected individuals of several families with Sorsby's fundus dystrophy (SFD). Very little information is available regarding TIMP-3 function or even its existence in the retina or choroid. Methods. We used reverse transcription-polymerase chain reaction and Northern analysis to evaluate the expression of TIMP mRNA and Western immunoblots to evaluate TIMP protein produced by select cells of the human retina and choroid. We also used these methods and immunohistochemistry to localize the TIMPs in the retina and choroid. Results. TIMP-3 transcripts are found in cultured human retinal pigment epithelium (RPE), choroidal microcapillary endothelium and pericytes. RPE cells also express and secrete TIMP-3 protein, which is localized to the extracellular matrix and is not found in culture medium; TIMP-1 and -2 are found almost exclusively in the medium. Immunohistochemistry of human retina/choroid sections shows pronounced TIMP-3 immunostaining in Bruch's membrane, particularly near the surface of the RPE and endothelial cells, presumably in their basement membranes, with minimal staining in other portions of the retina. Immunostaining for TIMP-1 is absent and for TIMP-2 is much less prevalent, but detectable in Bruch's membrane. Conclusions. TIMP-1, -2 and -3 exhibit distinctive expression patterns in the retina and choroid. This distribution and expression pattern partially explains why TIMP-3 mutations result in SFD, rather than other retinal pathologies, such as those associated with proliferative diabetic retinopathy.

Original languageEnglish (US)
Pages (from-to)102-110
Number of pages9
JournalCurrent Eye Research
Volume16
Issue number2
DOIs
StatePublished - Mar 17 1997

Keywords

  • Bruch's membrane
  • Choroidal microvasculature
  • Human
  • Macular degeneration
  • Matrix metalloproteinase inhibitor
  • Retinal pigment epithelium (RPE)

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

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