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Polyamine regulation of ornithine decarboxylase and its antizyme in intestinal epithelial cells

Q Yuan1, R M Ray, M J Viar

  • 1Department of Physiology, College of Medicine, The University of Tennessee, Memphis, Tennessee 38163, USA.

American Journal of Physiology. Gastrointestinal and Liver Physiology
|December 21, 2000
PubMed

Insights

Polyamines regulate ornithine decarboxylase (ODC) activity. Spermine is most effective, while putrescine is least effective, in this regulation, independent of ODC antizyme induction.

Area of Science:

  • Biochemistry
  • Cell Biology
  • Molecular Biology

Background:

  • Ornithine decarboxylase (ODC) activity is regulated by polyamines through ODC antizyme.
  • Polyamines are known to induce ODC antizyme and inhibit ODC activity.
  • Cellular polyamine interconversion complicates understanding individual polyamine roles.

Purpose of the Study:

  • To investigate the specific roles of putrescine, spermidine, and spermine in regulating ODC activity.
  • To determine the involvement of ODC antizyme in polyamine-mediated ODC regulation.
  • To elucidate polyamine effects on ODC in intestinal epithelial crypt (IEC-6) cells.

Main Methods:

  • Utilized diethylglyoxal bis(guanylhydrazone) (DEGBG), an inhibitor of S-adenosylmethionine decarboxylase, to block spermidine and spermine synthesis.
  • Administered exogenous polyamines to DEGBG-treated IEC-6 cells.
  • Measured ODC activity, intracellular polyamine levels, and ODC protein levels.

Main Results:

  • Putrescine, spermidine, and spermine inhibited serum-stimulated ODC activity by 85%, 46%, and 0% (control) respectively, in the presence of DEGBG.
  • ODC activity increased in DEGBG-treated cells despite high putrescine levels.
  • Spermine was more effective than spermidine in reducing ODC activity in DEGBG-treated cells; putrescine was least effective.
  • High putrescine did not induce ODC antizyme when spermidine and spermine levels were low.
  • ODC activity decay and protein reduction occurred without antizyme induction in DEGBG-treated cells.

Conclusions:

  • Spermine is the most potent polyamine regulator of ODC activity, while putrescine is the least effective.
  • Upregulation of ODC antizyme is not essential for the degradation of ODC protein.
  • Polyamines exert distinct regulatory effects on ODC activity, independent of antizyme induction in certain conditions.

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