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


CONCLUSIONS
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.
Jaffe
G J
GJ
Department of Ophthalmology, Duke University, Durham, North Carolina.
Richmond
A
A
Van Le
L
L
Shattuck
R L
RL
Cheng
Q C
QC
Wong
F
F
Roberts
W
W
D001798:Blood Proteins / Q000494:pharmacology; D002478:Cells, Cultured; D054360:Chemokine CXCL1; D019743:Chemokines, CXC; D002630:Chemotactic Factors / Q000235:genetics / Q000378:metabolism*; D016207:Cytokines / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D005786:Gene Expression Regulation / Q000187:drug effects; D006133:Growth Substances / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007124:Immunoenzyme Techniques; D036341:Intercellular Signaling Peptides and Proteins; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D010857:Pigment Epithelium of Eye / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology
D001798:Blood Proteins; C475829:CXCL1 protein, human; C499707:CXCL3 protein, human; D054360:Chemokine CXCL1; D019743:Chemokines, CXC; D002630:Chemotactic Factors; D016207:Cytokines; D006133:Growth Substances; D036341:Intercellular Signaling Peptides and Proteins; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins