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Marian S. Chin, Chandrasekharam N. Nagineni, Laura C. Hooper, Barbara Detrick, John J. Hooks; Cyclooxygenase-2 Gene Expression and Regulation in Human Retinal Pigment Epithelial Cells. Invest. Ophthalmol. Vis. Sci. 2001;42(10):2338-2346.
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purpose. Cyclooxygenases (COX) orchestrate a variety of homeostatic processes
and participate in various pathophysiological conditions. The retinal
pigment epithelium (RPE) cell performs a variety of regulatory
functions within the retina. The conditions under which COX-1 and COX-2
are expressed and upregulated in human RPE (HRPE) cells were
methods. COX gene expression was examined using RT-PCR analysis of untreated
HRPE cultures or cultures exposed to bacterial lipopolysaccharide or
various cytokines. COX proteins were detected by immunohistochemistry
and Western blot analysis. Prostaglandin (PG) production was analyzed
results. Examination of untreated RPE cells revealed the presence of COX-2 mRNA
and the absence of COX-1 mRNA. Moreover, cytokine stimulation more
readily enhanced COX-2 gene expression than COX-1 gene expression.
IL-1β, the most potent inducer of COX-2, also resulted in detection
of COX-2 protein by immunocytochemical staining and Western blot
analysis. There was a direct relationship between both the appearance
and amount of COX-2 mRNA and protein synthesis and the degree of PG
synthesis by RPE cells. Furthermore, COX inhibitors significantly
decreased PG production. Pretreatment of RPE cells with a NF-κB
inhibitor, PDTC, resulted in dose-dependent decrease in
IL-1β–induced COX-2 gene expression and PG production.
conclusions. COX-2 was the predominant isoform of cyclooxygenase in untreated HRPE
cells. When HRPE cells were treated with proinflammatory cytokines,
COX-2 gene expression and synthesis of PGs were enhanced. NF-κB
mediated the induction of COX-2 gene expression in HRPE cells. These
studies indicate that RPE cells may participate in normal and
pathologic retinal conditions through the induction of
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