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Related Experiment Video

Updated: Jul 13, 2026

Exploring the Arginine Methylome by Nuclear Magnetic Resonance Spectroscopy

Exploring the Arginine Methylome by Nuclear Magnetic Resonance Spectroscopy

Published on: December 16, 2021

Polyamine homeostasis in arginase knockout mice.

Joshua L Deignan¹, Justin C Livesay, Lisa M Shantz

¹Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095-1732, USA.

American Journal of Physiology. Cell Physiology

|August 10, 2007

Summary

Arginase enzymes produce ornithine for polyamine synthesis, but this study found that disrupting arginase I and II in mice did not significantly alter polyamine levels, suggesting dietary sources are key.

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Area of Science:

Biochemistry
Metabolic pathways
Molecular biology

Background:

Ornithine decarboxylase (ODC) is crucial for polyamine metabolism, but the primary source of ornithine remains unclear.
Arginase enzymes (I and II) can produce ornithine, potentially regulating polyamine production.

Purpose of the Study:

To investigate the role of arginase I and II in polyamine homeostasis.
To determine if disrupting arginase activity affects tissue polyamine levels in mice.

Main Methods:

Analysis of polyamine levels in livers, brains, kidneys, and small intestines of arginase I and II single and double knockout mice at 2 weeks of age.
Measurement of ornithine decarboxylase (ODC) activity.
Quantification of mRNA levels for ornithine aminotransferase (OAT), antizyme 1 (AZ1), and spermidine/spermine-N(1)-acetyltransferase (SSAT).

Main Results:

Minimal increase in putrescine in the liver and kidneys of arginase II knockout mice; spermidine and spermine levels were maintained.
ODC activity was not significantly altered and did not correlate with putrescine fluctuations.
Minor changes in OAT, AZ1, and SSAT mRNA levels, with a notable increase in OAT expression in the liver of arginase I knockout and double knockout mice.

Conclusions:

Endogenous arginase-derived ornithine may not be essential for maintaining polyamine homeostasis in mice.
Disruption of arginase I impacts putrescine catabolism in the liver when ornithine levels are low.
Dietary intake likely provides sufficient polyamines for mammalian tissue maintenance.