Cultured Muller cells have high levels of epidermal growth factor receptors

R. S. Roque, Ruth B Caldwell, M. A. Behzadian

Research output: Contribution to journalArticle

47 Scopus citations

Abstract

High levels of epidermal growth factor (EGF)-receptors have been reported in membrane homogenates of bovine retinas, but the biologic function and tissue target of EGF in the retina have not been established fully. Because EGF participation has been suggested in the mechanisms of wound healing and Muller cells undergo changes after retinal injury, the authors studied EGF receptor expression and functional role of this substance in cultured Muller cells. These cells (isolated from normal rats) were tested for the glial cell markers: vimentin, S-100 protein, and carbonic anhydrase C. These markers were found to be positive through all passages used in the experiments. The 125I-EGF binding in Muller cells was highly specific, concentration dependent, and saturable. Compared with 3T3 fibroblasts, Muller cells bound threefold more EGF. Binding kinetics and Scatchard and analyses showed the higher level of binding was related to the greater number of receptors on these cells (Muller cells, 2.4 x 105 receptors/cell; 3T3 fibroblasts, 7.1 x 104 receptors/cell) rather than a change in affinity of the receptors to bind the ligand. Nonlinear-regression analyses suggested the presence of two classes of affinity sites. The high level of EGF-receptor expression in Muller cells was confirmed by western blot analyses that showed increased reactivity of the approximately 170-kilodalton receptor band to a monoclonal anti-EGF receptor antibody. Moreover, EGF treatment of Muller cells resulted in two- to threefold increase in DNA synthesis, as evidenced by 3H-thymidine uptake studies. These findings support a functional role for EGF in Muller cell proliferation in retinal disease.

Original languageEnglish (US)
Pages (from-to)2587-2595
Number of pages9
JournalInvestigative Ophthalmology and Visual Science
Volume33
Issue number9
StatePublished - Jan 1 1992

Keywords

  • DNA synthesis
  • S-100 protein
  • carbonic anhydrase C
  • cultured Muller cells
  • epidermal growth factor

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

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