1.Sensitivity of CD95-induced apoptosis in different proliferative status of human retinal pigment epithelial cells.
Jin Hee CHANG ; Se Woong KANG ; Don Il HAM
Korean Journal of Ophthalmology 2001;15(2):74-80
It is known that CD95 (APO-1/Fas) is expressed on the cell surface, and apoptotic cell death can be induced by the CD95 ligation in the cultured, proliferating human retinal pigment epithelial (RPE) cells. However, little is known about CD95 on the non-proliferating RPE cells. In this study, human RPE cells were cultured up to 4 weeks after they reached the confluence, to simulate the non-proliferating RPE cells in situ. There was no significant difference in CD95 expression on the cell surface between the predominantly proliferating, preconfluent cells and predominantly non-proliferating, postconfluent cells in flow cytometric assays. However, unlike proliferating cells, no cellular death occurred in the predominantly non-proliferating cells after the treatment of agonistic anti-CD95 antibody with cycloheximide, pretreated with interferon-gamma. Our results suggest that the CD95/CD95L system probably plays a physiologic role in vivo to remove the abnormal, proliferating RPE cells, and factors other than the surface expression of CD95 may determine the sensitivity to the CD95 signals.
Antigens, CD95/*pharmacology
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Apoptosis/*physiology
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Cells, Cultured
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Human
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Pigment Epithelium of Eye/cytology/*drug effects/*physiology
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Sensitivity and Specificity
2.TGF-betas Synthesized by RPE Cells Have Autocrine Activity on Mesenchymal Transformation and Cell Proliferation.
Sung Chul LEE ; Soon Hyun KIM ; Hyoung Jun KOH ; Oh Woong KWON
Yonsei Medical Journal 2001;42(3):271-277
The present study investigated the effects of transforming growth factor (TGF)-beta on retinal pigment epithelial (RPE) transformation in a simplified model and also whether or not TGF-beta exhibits similar proliferation effects on transformed RPE cells that it has on primary RPE cells. Furthermore, we examined the cell proliferation effects of RPE-conditioned medium (CM). A vertical wound measuring 2 mm in diameter was made on primary RPE monolayers. The expression of alpha- smooth muscle actin (SMA) by the cells located at the wound edges was observed using a confocal microscope under immunofluorescent staining. Cell proliferation was measured by incorporating 3H-thymidine into DNA. The presence of alpha- SMA was observed in the cells within the wound after treatment with TGF-beta2, while negative expression was observed in control cells. TGF-betas inhibited the proliferation of the primary cultures of RPE cells in a dose-dependent manner, but the spindle-shaped late-passaged RPE cells were not inhibited by these growth factors. The medium conditioned by RPE cells stimulated the proliferation of subconjunctival fibroblasts and inhibited the proliferation of primary RPE cells, in a manner similar to TGF-beta. These findings demonstrate that TGF-beta-stimulated RPE cells may evoke proliferative vitreoretinopathy through mesenchymal transformation and cell proliferation.
Actins/analysis
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Animal
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Cell Division/drug effects
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Cells, Cultured
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Culture Media, Conditioned
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DNA/biosynthesis
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Mesoderm/*cytology
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Pigment Epithelium of Eye/*cytology
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Rabbits
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Swine
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Transforming Growth Factor beta/*physiology
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Vitreoretinopathy, Proliferative/etiology