RRC ID 39245
Author Ueda M, Masu Y, Ando A, Maeda H, Del Monte MA, Uyama M, Ito S.
Title Prevention of ornithine cytotoxicity by proline in human retinal pigment epithelial cells.
Journal Invest Ophthalmol Vis Sci
Abstract PURPOSE:To investigate the relationship between ornithine-delta-aminotransferase (OAT) deficiency and ornithine accumulation and the specific degeneration of retinal pigment epithelial (RPE) cells in gyrate atrophy.
METHODS:Human RPE cells, human hepatoma cells, and human fibroblast cells were treated with 5-fluoromethylornithine (5-FMOrn), a specific irreversible inhibitor of OAT. Ornithine cytotoxicity was determined by using a [3H]thymidine incorporation assay and immunohistochemical staining for cytokeratin. The effects of various metabolites of ornithine and arginine, such as creatine, creatine phosphate, I-delta 1-pyrroline-5-carboxylic acid (L-P5C), and proline, which may be deficient in gyrate atrophy on RPE cell damage by ornithine, were determined by the same procedures.
RESULTS:When the human RPE cells, HepG2 hepatoma cells, and WI-38 fibroblast cells were treated with 0.5 mM 5-FMOrn for 30 minutes, which inactivated OAT, ornithine exhibited severe time- and dose-dependent inhibition of DNA synthesis in the human RPE cells but not in the HepG2 hepatoma cells or WI-38 fibroblast cells. The inhibition of DNA synthesis was accompanied by drastic changes in morphologic appearance, disorganization of the cytoskeleton, and cell death. Ornithine or 5-FMOrn alone did not exhibit such cytotoxicity to the RPE cells. Proline prevented the cytotoxicity of ornithine.
CONCLUSIONS:These findings suggest that an elevated level of ornithine combined with an increased sensitivity to ornithine as a result of OAT deficiency may be crucial to the specific RPE degeneration in gyrate atrophy. They suggest also that abnormalities of proline metabolism may be involved in the progress of gyrate atrophy.
Volume 39(5)
Pages 820-7
Published 1998-4-1
PMID 9538890
MeSH Arginine / pharmacology Carcinoma, Hepatocellular / drug therapy Carcinoma, Hepatocellular / enzymology Carcinoma, Hepatocellular / pathology Cell Death / drug effects Cell Division / drug effects Cell Line Cell Survival / drug effects DNA / biosynthesis DNA / drug effects DNA Replication / drug effects Dose-Response Relationship, Drug Enzyme Inhibitors / pharmacology* Fibroblasts / drug effects Fibroblasts / enzymology Fibroblasts / pathology Fluorescent Antibody Technique, Indirect Humans Keratins / metabolism Liver Neoplasms / drug therapy Liver Neoplasms / enzymology Liver Neoplasms / pathology Ornithine / analogs & derivatives* Ornithine / metabolism Ornithine / pharmacology Ornithine / toxicity* Ornithine-Oxo-Acid Transaminase / antagonists & inhibitors* Pigment Epithelium of Eye / drug effects* Pigment Epithelium of Eye / enzymology Pigment Epithelium of Eye / pathology Proline / pharmacology*
IF 3.47
Times Cited 20
Human and Animal Cells WI-38 Hep G2(RCB0459)