Function and Origin of Multiple Ionic Forms of Hormone-Induced Ornithine Decarboxylase

Richards, Jennifer H.; Janzen, A.; Peng, Ted; Strumpfer, A.

doi:10.1006/abbi.1993.1012

Cited by 6 publications

(4 citation statements)

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“…Ornithine decarboxylase is a very minor component of the total soluble protein in most cells and can be induced by a large variety of growth-promoting stimuli such as hormones, growth factors, tissue regeneration activities, drugs and bile acids (6)(7)(8)(9)(10). There are existing multiple isoforms of ornithine decarboxylase in mammalian cells (11), of which one isoform can be stimulated by guanosine S'-triphosphate (GTP) (12,13).…”

Section: Introductionmentioning

confidence: 99%

Ornithine Decarboxylase Levels in Patients with Normal Colonic Mucosa

Zehnter¹,

Roisch²,

Kruis³

et al. 1996

CCLM

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We describe a systematic examination of oraithine decarboxylase activity in 120 colonic mucosal samples which were obtained from 20 subjects without colonic disease to establish the normal mean and standard deviation from proximal to distal colon. Ornithine decarboxylase activity was determined by releasing CO 2 from Z)L-[l-14 C]omithine. The mean ornithine decarboxylase levels (CO 2 liberated) ranged from 0.26 ± 0.08 nmol/h-mg protein in the caecum to 0.44 ±0.16 nmol/h · mg protein in the rectum. There was no difference between sex and age. Ornithine decarboxylase was not stimulated by guanosine 5'-triphosphate. -Difluoromethylornithine showed an ornithine decarboxylase inhibition of 97.1%. Ornithine decarboxylase activity can be measured with reliable precision and reproducibility. The knowledge of the normal range of ornithine decarboxylase activity in normal human colonic mucosa is necessary for the determination of ornithine decarboxylase activity in pathological findings, especially in malignant transformation.

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Section: Introductionmentioning

confidence: 99%

Ornithine Decarboxylase Levels in Patients with Normal Colonic Mucosa

Zehnter¹,

Roisch²,

Kruis³

et al. 1996

CCLM

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“…Multiple peaks of ODC activity elute from anion exchange chromatography columns loaded with extracts of various tissue and cultured cell types (5-8, 35, 40 -42). It has been demonstrated in several experimental systems that phosphatase treatment and rechromatography of the second, more acidic peak of ODC shifts the enzyme's elution position to that of the first peak (35,42). Furthermore, the initial, more basic peak of ODC can be phosphorylated by CKII, whereas the second, more acidic peak of ODC is not a substrate for this kinase (41).…”

Section: Induction Of Unphosphorylated and Phosphorylated Odc Inmentioning

confidence: 99%

Multisite Phosphorylation of Ornithine Decarboxylase in Transformed Macrophages Results in Increased Intracellular Enzyme Stability and Catalytic Efficiency

Reddy¹,

Mcllheran

Cochran

et al. 1996

Journal of Biological Chemistry

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Ornithine decarboxylase (ODC) is the initial inducible enzyme in the polyamine biosynthetic pathway. In the transformed macrophage-derived RAW264 cell line, ODC was overproduced and existed in both unphosphorylated and phosphorylated forms. To date, the only protein kinase known to phosphorylate mammalian ODC is casein kinase II (CKII). ODC was phosphorylated in vitro by CKII and subjected to exhaustive sequential proteolysis with trypsin and V8 protease. Two-dimensional peptide mapping showed only a single phosphopeptide; two-dimensional phosphoamino acid analysis of the phosphopeptide revealed only 32 P-labeled serine. ODC was metabolically radiolabeled with 32 P i in RAW264 cells and also subjected to proteolysis, two-dimensional peptide mapping, and phosphoamino acid analysis. Two phosphopeptides were generated from the metabolically radiolabeled ODC, including one that migrated similarly to the peptide phosphorylated by CKII in vitro. Each of the in situ radiolabeled ODC peptides contained both 32 P-labeled serine and threonine residues. Thus, in RAW264 cells, ODC is phosphorylated on at least one serine residue in addition to that phosphorylated by CKII and on at least two threonine residues. Phosphorylated ODC had an increased stability to intracellular proteolysis compared with unphosphorylated ODC, their half-lives being 49.2 ؎ 3.78 and 23.9 ؎ 2.6 min (p ‫؍‬ 0.001), respectively. The phosphorylated and unphosphorylated forms of ODC were independently purified to homogeneity. Kinetic analysis revealed that the catalytic efficiency of the phosphorylated form of ODC was 50% greater than that of the unphosphorylated form; the unphosphorylated ODC had a V max of 20.54 ؎ 1.65 mol/min/mg, whereas the phosphorylated form had a V max of 30.61 ؎ 2.6 mol/min/mg (p ‫؍‬ 0.005). Phosphorylation of ODC by CKII has no effect on enzyme activity. Taken together, these findings demonstrate that regulation of ODC activity is governed by as yet unidentified protein kinases.Ornithine decarboxylase (ODC, EC 4.1.1.17) 1 is the initial rate-limiting enzyme in polyamine biosynthesis. Putrescine, the product of ODC catalysis, and the subsequent metabolic pathway products spermidine and spermine are small aliphatic nitrogenous bases that fulfill structural and regulatory roles in protein and nucleic acid biosynthesis and function (1). Cellular ODC activity increases rapidly and transiently in response to trophic, proliferative, or toxic stimuli (2). Both somatic cell genetic and pharmacologic experimental approaches have demonstrated that expression of ODC is essential for cell growth. Regulation of enzyme expression at the levels of DNA transcription, mRNA translation, and protein turnover have been described (for reviews, see Refs. 3 and 4). However, little is known about potential posttranslational regulation of ODC.Multiple forms of ODC protein occur in a variety of cells and tissues. Anion exchange chromatography resolves several peaks of ODC activity in extracts prepared from calf liver (5), rat thymus and kidney (6), rat he...

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“…This behaviour may be explained by the presence of multiple forms of the enzyme. Indeed, in the rat liver and kidney, two distinct ionic forms have already been isolated by ion-exchange chromatography, one of them showing a much longer half-life after hormonal treatment (Richards et al, 1993). Moreover, two enzymatic forms displaying different kinetic properties have been observed in the rat liver after thioacetamide injection (Obenrader and Prouty, 1977) as well as in the rat heart after isoproterenol or T3 treatment (Lau and Slotkin, 1979).…”

Section: Discussionmentioning

confidence: 99%

Ornithine decarboxylase activity is associated with proliferation but not with T₃‐induced differentiation of Caco‐2 cells

Jumarie

Malo

1995

Journal Cellular Physiology

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Ornithine decarboxylase (ODC) activity and polyamine (putrescine, spermidine, spermine) concentrations were measured in parallel in enterocyte-like Caco-2 cells maintained under various culture conditions. ODC activity was maximal at the beginning of the exponential growth phase, decreasing dramatically thereafter to a negligible level at confluency (day 9). Kinetic studies performed on day 3 revealed the presence of a single enzyme with a Km around 200 microM and a Vmax of about 2 nmol CO2 released/h/mg protein. Similar values were obtained in both serum-supplemented and transferrin/selenium (TS)-defined culture media, indicating that ODC kinetic parameters are not affected by any factors present in serum. Polyamine concentrations were maximal on day 5. By day 9, they returned to initial levels and remained at these fairly high values until day 21. Since we have previously shown (Jumarie and Malo, 1994, in Vitro Cell. Dev. Biol., 30A:753-760) that triiodothyronine (T3) stimulates differentiation but not proliferation of Caco-2 cells maintained in TS-defined medium, we investigated if it induces differentiation by a polyamine-dependent mechanism. Short- and long-term measurements revealed similar ODC activity and polyamine levels whether T3 was present or not in the culture medium. These results clearly demonstrate that polyamine synthesis is more likely to be associated with Caco-2 cell proliferation, and that the T3 effect on Caco-2 cell differentiation does not involve polyamine biosynthesis. Moreover, our data show that ODC activity is not solely regulated by intracellular polyamine concentration.

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Function and Origin of Multiple Ionic Forms of Hormone-Induced Ornithine Decarboxylase

Cited by 6 publications

References 0 publications

Ornithine Decarboxylase Levels in Patients with Normal Colonic Mucosa

Ornithine Decarboxylase Levels in Patients with Normal Colonic Mucosa

Multisite Phosphorylation of Ornithine Decarboxylase in Transformed Macrophages Results in Increased Intracellular Enzyme Stability and Catalytic Efficiency

Ornithine decarboxylase activity is associated with proliferation but not with T₃‐induced differentiation of Caco‐2 cells

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Function and Origin of Multiple Ionic Forms of Hormone-Induced Ornithine Decarboxylase

Cited by 6 publications

References 0 publications

Ornithine Decarboxylase Levels in Patients with Normal Colonic Mucosa

Ornithine Decarboxylase Levels in Patients with Normal Colonic Mucosa

Multisite Phosphorylation of Ornithine Decarboxylase in Transformed Macrophages Results in Increased Intracellular Enzyme Stability and Catalytic Efficiency

Ornithine decarboxylase activity is associated with proliferation but not with T3‐induced differentiation of Caco‐2 cells

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Ornithine decarboxylase activity is associated with proliferation but not with T₃‐induced differentiation of Caco‐2 cells