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Expression of three forms of melanoma growth stimulating activity (MGSA)/gro in human retinal pigment epithelial cells.

Jaffe GJ, Richmond A, Van Le L, Shattuck RL, Cheng QC, Wong F, Roberts W
Invest Ophthalmol Vis Sci. 1993 34 (9): 2776-85

PMID: 8344798

PURPOSE - To characterize mRNA expression and protein production of the cytokine MGSA/gro in human retinal pigment epithelial (RPE) cells and to determine whether expression of MGSA/gro is modulated by serum and the cytokines interleukin 1 beta (IL-1 beta), tumor necrosis factor alpha (TNF alpha), or transforming growth factor beta (TGF beta) mediators implicated in proliferative vitreoretinopathy (PVR).

METHODS - Reverse-transcription polymerase chain reaction was used to determine the steady-state mRNA expression of three forms of MGSA/gro, alpha, beta, and gamma, by cultured human RPE cells in the presence or absence of recombinant IL-1 beta, TNF alpha, or TGF beta, or when serum-starved cells were re-fed with medium containing serum. Immunocytochemistry was used to characterize RPE cell-associated MGSA/gro protein, and immunoprecipitation of MGSA/gro from cell-conditioned medium was used to demonstrate MGSA/gro secretion.

RESULTS - MGSA/gro mRNA was expressed minimally under basal conditions. Expression for all three forms of MGSA/gro mRNA was induced in a dose- and time-dependent manner after exposure to IL-1 beta, to a lesser extent after exposure to TNF alpha, but not after exposure to TGF beta. Serum induced MGSA/gro alpha and gamma transcripts, but not beta transcripts. Cell-associated MGSA/gro was identified on RPE cells grown in the absence of cytokines, but MGSA/gro was not secreted under these conditions. Exposure to IL-1 beta did not consistently cause increased cell-associated MGSA/gro; however, IL-1 beta induced secretion of MGSA/gro in a time-dependent manner.

CONCLUSION - MGSA/gro is produced by human RPE in response to mediators implicated in PVR. Because MGSA/gro is a pleiotropic modulator of cell proliferation and inflammation, it may contribute to the intraocular wound healing response that characterizes PVR.

MeSH Terms (17)

Blood Proteins Cells, Cultured Chemokine CXCL1 Chemokines, CXC Chemotactic Factors Cytokines Electrophoresis, Polyacrylamide Gel Gene Expression Regulation Growth Substances Humans Immunoenzyme Techniques Intercellular Signaling Peptides and Proteins Neoplasm Proteins Pigment Epithelium of Eye Polymerase Chain Reaction Recombinant Proteins RNA, Messenger

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