Cloning of the bovine plasma selenium-dependent glutathione peroxidase (GP) cDNA from the ocular ciliary epithelium: expression of the plasma and cellular forms within the mammalian eye.
In the anterior segment of the mammalian eye, the ocular ciliary epithelium produces the aqueous humor, a fluid that nourishes and protects the avascular tissues from oxidative stress. This report details the results of a study of molecular cloning, sequencing, and expression of plasma glutathione peroxidase (GPx-P) from the bovine ocular ciliary epithelium. The bovine GPx-P cDNA contains an open reading frame of 226 amino acids with a calculated molecular weight of 24,860. The corresponding amino acid sequence showed an overall identity of 88% with the human GPx-P, 88.5% with the rat GPx-P, and 46.4% with the cellular bovine glutathione peroxidase (GPx-1). The levels of GPx-P and GPx-1 transcripts in ocular tissues were analyzed and the ciliary epithelium was found to express the highest levels of GPx-P transcripts in human and bovine eyes, whereas the cornea of calf eyes expressed the highest levels of GPx-1 transcripts. Surprisingly, the lens, on which oxidants have profound effects leading to cataract formation, expressed the lowest levels of GPx-P and GPx-1 transcripts in human donor eyes. These results provide new evidence of differential gene expression of the GPx-P and GPx-1 forms in the mammalian eye and stresses the functional role of the ocular ciliary epithelium in protecting the anterior segment of the eye from oxidative damage.
Martín-Alonso
J M
JM
Department of Ophthalmology and Visual Science, Yale University School of Medicine, New Haven, CT 06510.
Ghosh
S
S
Coca-Prados
M
M
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002417:Cattle; D002924:Ciliary Body / Q000201:enzymology*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics / Q000378:metabolism; D004848:Epithelium / Q000201:enzymology; D005123:Eye / Q000201:enzymology*; D015870:Gene Expression / Q000235:genetics; D005979:Glutathione Peroxidase / Q000096:biosynthesis* / Q000097:blood / Q000737:chemistry / Q000235:genetics; D006801:Humans; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D015183:Restriction Mapping; D012643:Selenium / Q000494:pharmacology; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid
D018076:DNA, Complementary; D005979:Glutathione Peroxidase; D012643:Selenium