Disease of Ornithine-Proline Pathway: A △1-pyrroline-5-carboxylate Reductase Deficiency in the Retina of Retinal Degeneration Mice
The discovery of a genetic defect in ornithine oxoacid aminotransferase (L-ornithine: 2-oxoacid aminotransferase, EC 22.214.171.124) in gyrate atrophy of the choroid and retina1,2,3, prompted us to study the ornithine metabolism of the eye4. We soon found high 361 activities of ornithine oxoacid aminotransferase and △1-pyrroline-5-carboxylate reductase (L-proline:NAD(P)+5-oxidoreductase, EC 126.96.36.199) (P5C reductase) in the retina and retinal pigment epithelium4,5. Gyrate atrophy of the choroid and retina is a disease related to the category of choroideremia and retinitis pigmentosa (primary, hereditary, pigmentary retinopathy), these are much frequent cause of the human hereditary blindness, however the biochemical pathogenesis of these diseases remains to be solved. In this paper we describe an intracellular proline synthetic pathway from ornithine uncovered in the bovine cornea and retinal outer layers(including the choroid) which presumably participates in the biosynthesis of proline-rich proteins such as collagen and glycoproteins, and the characteristic postnatal changes and the deficiency of this pathway in C3H retinal degeneration mice.
KeywordsRetinitis Pigmentosa Ocular Tissue Arginase Activity Retinal Outer Layer Pigmentary Retinopathy
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