Cultured Muller cells have high levels of epidermal growth factor receptors

• Published in: Investigative ophthalmology & visual science Vol. 33; no. 9; pp. 2587 - 2595
• Main Authors: Roque, RS, Caldwell, RB, Behzadian, MA
• Format: Journal Article
• Language: English
• Published: Rockville, MD ARVO 01.08.1992; Association for Research in Vision and Ophtalmology
• Subjects: 3T3 Cells - metabolism; Animals; Biological and medical sciences; Carbonic Anhydrases - metabolism; Cells, Cultured; DNA - biosynthesis; Epidermal Growth Factor - metabolism; Eye and associated structures. Visual pathways and centers. Vision; Fundamental and applied biological sciences. Psychology; Immunoenzyme Techniques; Mice; Neuroglia - metabolism; Radioligand Assay; Rats; Rats, Mutant Strains; Receptor, Epidermal Growth Factor - metabolism; Retina - cytology; Retina - metabolism; S100 Proteins - metabolism; Vertebrates: nervous system and sense organs; Vimentin - metabolism; Eye; Cell culture; Epidermal growth factor; Animal; Muller cell; Gene expression; Biological activity; Biological receptor
• ISSN: 0146-0404; 1552-5783

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 Müller cells undergo changes after retinal injury, the authors studied EGF receptor expression and functional role of this substance in cultured Müller 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 Müller cells was highly specific, concentration dependent, and saturable. Compared with 3T3 fibroblasts, Müller cells bound threefold more EGF. Binding kinetics and Scatchard analyses showed the higher level of binding was related to the greater number of receptors on these cells (Müller cells, 2.4 x 10(5) receptors/cell; 3T3 fibroblasts, 7.1 x 10(4) 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 Müller 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 Müller 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 Müller cell proliferation in retinal disease.