l-Ornithine-induced inactivation of mammalian ornithine decarboxylase in vitro

Danzin, Charles; Persson, Lo

doi:10.1111/j.1432-1033.1987.tb13481.x

Cited by 9 publications

(5 citation statements)

References 16 publications

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“…thine, independent of the polyamines, might affect the activity of ODC by altering the level of antizyme or directly inactivating ODC. Ornithine has been reported to inactivate partially purified ODC in the absence of stabilizing thiols (Danzin and Persson, 1987). In summary, the H35 cells cultured in serum-free medium for a 3-day period were quite similar to those cells continually cultured with serum in regards to their growth rate, levels of ornithine, polyamines, and ODC in response to TPA administration.…”

Section: Discussionmentioning

confidence: 68%

The level of substrate ornithine can alter polyamine‐dependent DNA synthesis following phorbolester stimulation of cultured hepatoma cells

Byus

1991

Journal Cellular Physiology

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Although the precise intracellular function(s) of the polyamines remain incompletely defined, a myraid of evidence now shows that the polyamines must accumulate or be maintained at a specific intracellular concentration in order for all mammalian cells to grow or divide. The initial step in polyamine biosynthesis normally involves the decarboxylation of ornithine by the enzyme ornithine decarboxylase (ODCase E.C. 4.1.1.17) to yield putrescine. Increases in the steady-state level of intracellular ornithine have been reported to markedly alter the accumulation of the polyamines following stimulation of Reuber H35 Hepatoma cells with 12-O-tetradecanoylphorbol-beta-acetate (TPA) in the presence of serum (Wu and Byus: (Biochem. Biophys. Acta 804:89-99, 1984); Wu et al.: (Cancer Res. 41:3384-3391, 1981). We wished to determine whether or not incubation of H35 hepatoma cells with exogenous ornithine would result in a stimulation of DNA synthesis following treatment with the mitogens TPA and insulin. For these studies, H35 cells were maintained under serum-free conditions for 2-3 days in order to obtain synchronous cultures suitable for analysis of the level of DNA synthesis. Cultures treated in this manner were highly viable, maintained similar growth rates, and possessed the equivalent levels of intracellular ornithine and polyamines as the serum-containing cultures. Arginine levels, however, were approximately twofold higher following culture under serum-restricted conditions for 3 days. The addition of exogenous ornithine (0.5 mM) was accompanied by a 4-5-fold increase in intracellular steady-state ornithine levels and by a 6-8-fold increase in the presence of TPA and ornithine. In a manner identical to the serum-containing cultures (Wu and Byus (1984] the addition of TPA and exogenous ornithine to the serum-free cells caused a dose-dependent increase in intracellular putrescine (up to 5-fold) and a concomitant decrease in ODC activity in comparison to stimulation with TPA alone. The addition of TPA led to a 3-5-fold increase in the incorporation of tritiated thymidine into DNA. In the presence of exogenous ornithine, TPA-induced DNA synthesis was further stimulated more than twofold in a dose-dependent manner. Insulin (10(-10)-10(-8) M) proved to be more efficacious as a mitogen in the H35 cells and led to greater stimulation of DNA synthesis than TPA. Insulin alone also resulted in a higher steady-state level of ornithine and putrescine in comparison with TPA alone.(ABSTRACT TRUNCATED AT 250 WORDS)

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Section: Discussionmentioning

confidence: 68%

The level of substrate ornithine can alter polyamine‐dependent DNA synthesis following phorbolester stimulation of cultured hepatoma cells

Byus

1991

Journal Cellular Physiology

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“…The reduction in ODC activity was similar to the observations of Dircks et al [10] who found reduced ODC activity in cells cultured in ornithine-rich media. It has also recently been shown that L-ornithine inactivates mammalian ODC in vitro [11]. There have been no published reports on the effect of dietary ornithine on renal AdoMetDC activity.…”

Section: Discussionmentioning

confidence: 99%

Effect of Dietary Ornithine on Renal and Hepatic Polyamine Synthesis

Bedford¹,

Smith²,

Summers³

1988

Ann Nutr Metab

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Chicks with genetically elevated renal arginase activity were fed crystalline amino acid diets varying in ornithine concentration (0, 1 or 2%) to assess the potential for precursor regulation of polyamine synthesis. Renal arginase and renal and hepatic ornithine decarboxylase activities fell when ornithine was fed. Renal and hepatic ornithine concentrations rose while putrescine concentrations varied quadratically with ornithine feeding. Spermidine and spermine concentrations were not affected by diet. It was concluded that ornithine syntesized in vivo was a more potent stimulator of polyamine synthesis than ornithine of dietary origin.

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“…Changes in he patic concentrations of deAdoMet were sim ilar but smaller. Concentrations of MTA and deAdoMet in muscle were not affected by diet with mean values ± SD of 0.41 ± 0.17 (19) and 0.93 ± 1.18 (19) mol/g tissue re spectively.…”

Section: Resultsmentioning

confidence: 87%

“…The lack of effect of DFMO on tissue amino acid concentra tions confirms that it acts as a specific inhib itor of ODC and that the action of ODC under these physiological conditions seems to have only a minor effect on tissue orni thine pools. The influence of DFMO on ODC was likely minimized by the high tissue concentration of ornithine, however, which has been shown to inhibit ODC in vitro [19].…”

Section: Discussionmentioning

confidence: 99%

Effects of Dietary Polyamine Precursors on the Metabolism and Tissue Concentrations of Amino Acids in the Rat

Smith¹,

Lindqvist²,

Alakuijala³

et al. 1989

Ann Nutr Metab

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Experiments were conducted to determine the effects of dietary supplements of amino acid precursors of polyamines on amino acid metabolism in the rat in order to better understand comparative aspects of polyamine metabolism. Rats were fed isonitrogenous combinations of methionine, ornithine, arginine and 2-difluoromethylornithine in casein-based diets. It was observed that hepatic concentrations of methionine, 5’-deoxy-5’-methylthioadenosine and decarboxylated S-adenosylmethionine were more easily influenced by diet than were arginine and metabolites. It was concluded that rats may be more refractory to exogenous polyamine precursor amino acids than are chicks because of the presence of a functional urea cycle.

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l-Ornithine-induced inactivation of mammalian ornithine decarboxylase in vitro

Cited by 9 publications

References 16 publications

The level of substrate ornithine can alter polyamine‐dependent DNA synthesis following phorbolester stimulation of cultured hepatoma cells

The level of substrate ornithine can alter polyamine‐dependent DNA synthesis following phorbolester stimulation of cultured hepatoma cells

Effect of Dietary Ornithine on Renal and Hepatic Polyamine Synthesis

Effects of Dietary Polyamine Precursors on the Metabolism and Tissue Concentrations of Amino Acids in the Rat

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