Hormonal regulation of ornithine aminotransferase biosynthesis in rat liver and kidney

Lyons, Robert T.; Pitot, Henry C.

doi:10.1016/0003-9861(77)90062-5

Cited by 26 publications

(9 citation statements)

References 32 publications

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“…The promoter of the human and rat OAT gene contains numerous AGGTCA-like motifs related to the binding site for estrogen (39). In addition, administration of 17␤-estradiol (50 g/100 g BW) to male Sprague-Dawley and Holtzman rats induces a progressive increase in renal OAT mRNA, protein, and activity (24,29). Finally, two estrogen receptor (ER) subtypes that belong to the superfamily of nuclear receptors, ER-␣ and ER-␤, are expressed in several mouse and rat tissues where they mediate the effects of estrogens.…”

Section: Discussionmentioning

confidence: 99%

Ornithine metabolism in male and female rat kidney: mitochondrial expression of ornithine aminotransferase and arginase II

Levillain

Hus-Citharel²,

Garvi³

et al. 2004

American Journal of Physiology-Renal Physiology

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.-In the kidney, L-ornithine is reabsorbed along the proximal convoluted tubule (PCT), transported by basolateral carriers, and produced by arginase II (AII). Here, the renal metabolic fate of L-ornithine was analyzed in male and female rats. Kidneys and renal zones were dissected and used for Western blot analysis, immunofluorescence, and electron microscopic studies. Ornithine aminotransferase (OAT) and AII were localized using specific antibodies. Ornithine oxidation was determined by incubating microdissected tubules with L-[1-14 C] or L-[U-14 C]ornithine in the presence or absence of energy-providing substrates. Ornithine decarboxylase (ODC) mRNAs were localized by in situ hybridization. The 48-kDa OAT protein was detected in male and female kidneys, but its level was fourfold higher in the latter. OAT relative distribution increased from the superficial cortex toward the outer medulla to reach its highest level. Almost all OAT protein was localized in cortical and medullary proximal straight tubules (CPST and OSPST, respectively). In proximal straight tubule (PST), AII protein distribution overlapped that of OAT. No gender difference in AII protein level was found. OAT and AII were colocalized within PST mitochondria. 14 C]ornithine demonstrated the complete oxidation of ornithine. In conclusion, the OAT gene was expressed more in female rat proximal tubules than in male. Because OAT and AII proteins overlapped in PST mitochondria, L-argininederived ornithine may be preferentially converted to L-glutamate, as proven by ornithine oxidation. However, the coexpression of ODC, glutamate decarboxylase, and glutamine synthetase in PST suggests that L-ornithine can also be metabolized to putrescine, GABA, and L-glutamine. The fate of L-ornithine may depend on the cellular context. L-ornithine; L-arginine; proximal tubules; isolated nephron segments; Western blot analysis; immunofluorescence; electron microscopy; mitochondria; ornithine decarboxylase THE AMINO ACID L-ORNITHINE is absent from food and is not a constituent of proteins; therefore, vertebrate organisms are dependent on its formation. In kidneys, four sources of Lornithine can be considered: 1) L-ornithine is present in the blood and then transported across the basolateral membranes of a variety of renal cells (36,40); 2) L-ornithine is filtered in glomeruli and reabsorbed by specific carriers located in the apical membrane of the proximal convoluted tubule (PCT) (43); 3) in PCT, the enzyme L-arginine:glycine amidinotransferase (GAT; EC 2.1.4.1) metabolizes L-arginine in the presence of L-glycine and produces guanidinoacetic acid and Lornithine (42); and 4) in the whole proximal straight tubule (PST) of several mammals including rats, the extrahepatic arginase II isoenzyme (AII; EC 3.5.3.1) hydrolyzes L-arginine into urea and L-ornithine (23).L-Ornithine is known to play a pivotal role in several metabolic pathways as precursor for L-proline, L-glutamate, L-glutamine, L-citrulline, and L-arginine biosynthesis. Interestingly, renal tubular cells contain...

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Section: Discussionmentioning

confidence: 99%

Ornithine metabolism in male and female rat kidney: mitochondrial expression of ornithine aminotransferase and arginase II

Levillain

Hus-Citharel²,

Garvi³

et al. 2004

American Journal of Physiology-Renal Physiology

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“…Several reports clearly documented the hormonal regulation of OAT gene in the rat liver and kidney. In this species, the renal expression of OAT gene is upregulated by estrogens and triiodothyronine (Herzfeld & Knox, 1968;Lyons & Pitot, 1977;Mueckler & Pitot, 1983;Mueckler et al, 1984). During the post-natal development of the rat kidney, the sexual dimorphism of the expression of OAT gene increased in parallel with the endogenous synthesis of estrogens (Herzfeld & Knox, 1968).…”

Section: Discussionmentioning

confidence: 99%

Orchidectomy Upregulates While Testosterone Treatment Downregulates the Expression of Ornithine Aminotransferase Gene in the Mouse Kidney

Levillain¹,

Dégletagne²,

Letexier³

et al. 2011

Basic and Clinical Endocrinology Up-to-Date

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“…It is well established that estrogen induces OKT activity in rat kidney but not in liver and that the estrogen effect on kidney is mediated by triiodothyronine (Ta) (15,28,56). Glucagon, on the other hand, induced OKT activity in liver but not in kidney; the glucagon effect was observed only in rats on low protein diets and the enzyme induction was abolished by glucose (27).…”

Section: Induction Of Enzyme or Enzyme Replacementmentioning

confidence: 97%

Gyrate atrophy of the choroid and retina

1981

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Gyrate atrophy of the choroid and retina is caused by deficient activity of ornithine ketoacid aminotransferase, a pyridoxal phosphate dependent enzyme. Besides the typical eye findings, abnormalities have been found on muscle biopsy, electro-encephalography, electromyography and electrocardiography, establishing this as a generalized disorder. Ornithine is markedly elevated in plasma and other body fluids. Plasma lysine, glutamate, glutamine and creatine are reduced. The possible contributions of these biochemical disturbances to the pathogenesis of gyrate atrophy are discussed. The disease is one of the few examples of an inherited chorioretinal dystrophy whose underlying biochemical defect is known. It therefore offers a unique opportunity to develop and test rational approaches to therapy. These include lowering of the abnormally high ornithine by dietary restriction of its precursor arginine, facilitation of ornithine excretion by administration of alpha-aminoisobutyric acid, replacement of deficient products such as lysine or creatine, or increasing residual enzyme activity by high levels of cofactor (vitamin B6). The results of several studies employing such approaches to therapy are presented as well as preliminary indications of possible benefit in a few patients.

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Hormonal regulation of ornithine aminotransferase biosynthesis in rat liver and kidney

Cited by 26 publications

References 32 publications

Ornithine metabolism in male and female rat kidney: mitochondrial expression of ornithine aminotransferase and arginase II

Ornithine metabolism in male and female rat kidney: mitochondrial expression of ornithine aminotransferase and arginase II

Orchidectomy Upregulates While Testosterone Treatment Downregulates the Expression of Ornithine Aminotransferase Gene in the Mouse Kidney

Gyrate atrophy of the choroid and retina

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