title: Expression and localization of enzymes of arginine metabolism in the rat eye.
abstract: OBJECTIVE
  Production of NO may be regulated by argininosuccinate synthetase and argininosuccinate lyase which recycle citrulline to arginine, and by arginase which hydrolyzes arginine to urea and ornithine. Expression of these and related enzymes in rat eye was studied.
  
  
  METHODS
  mRNAs for the enzymes were analyzed by reverse transcription-polymerase chain reaction (RT-PCR). Localization of the enzyme proteins and mRNAs was analyzed by immunohistochemistry and in situ hybridization, respectively.
  
  
  RESULTS
  In RT-PCR analysis, arginase II (nonhepatic type) mRNA was detected in retina and weakly in cornea, whereas arginase I (hepatic type) mRNA was not detected in any area. mRNAs for argininosuccinate synthetase, argininosuccinate lyase, ornithine aminotransferase and ornithine decarboxylase were present in all areas. In immunohistochemical analysis, arginase II was stained in cornea, epithelium of iris and ciliary process, inner part of neural retina and retinal pigment epithelium. Immunostaining of ornithine aminotransferase resembled that of arginase II. In in situ hybridization, arginase II and ornithine aminotransferase mRNAs were located much as seen with the enzyme proteins.
  
  
  CONCLUSIONS
  These results indicate that arginine recycling activity from citrulline is present widely in ocular tissues, whereas expression of arginase II differs among the tissues. We suggest that NO production may be regulated by these enzymes in the cells where NO synthase is colocalized. Colocalization of arginase II and ornithine aminotransferase suggests a role for arginase II in collagen synthesis in the eye.
authors.affiliation: Department of Molecular Genetics, Kumamoto University School of Medicine, Kumamoto, 860-0811, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Koshiyama
authors.forename: T
authors.initials: T
authors.lastname: Gotoh
authors.forename: K
authors.initials: K
authors.lastname: Miyanaka
authors.forename: T
authors.initials: T
authors.lastname: Kobayashi
authors.forename: A
authors.initials: A
authors.lastname: Negi
authors.forename: M
authors.initials: M
authors.lastname: Mori
mesh_terms: D000818:Animals; D001119:Arginase / Q000235:genetics / Q000378:metabolism; D001120:Arginine / Q000378:metabolism*; D004798:Enzymes / Q000235:genetics / Q000378:metabolism*; D005123:Eye / Q000201:enzymology / Q000378:metabolism*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008297:Male; D009953:Ornithine-Oxo-Acid Transaminase / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D014018:Tissue Distribution
chemical_list: D004798:Enzymes; D007527:Isoenzymes; D012333:RNA, Messenger; D001120:Arginine; D009953:Ornithine-Oxo-Acid Transaminase; D001119:Arginase