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Changes in ornithine decarboxylase and antizyme activities in developing mouse brain
H Onoue1, S Matsufuji, M Nishiyama
1Department of Nutrition, Jikei University School of Medicine, Tokyo, Japan.
The Biochemical Journal
|March 15, 1988
Summary
Mouse brain ornithine decarboxylase (ODC) is inhibited by ODC antizyme. This inhibitor
Area of Science:
- Biochemistry
- Molecular Biology
- Neuroscience
Background:
- Ornithine decarboxylase (ODC) is a key enzyme in polyamine synthesis.
- ODC activity is tightly regulated during development.
- ODC antizyme is a known inhibitor of ODC.
Purpose of the Study:
- To characterize the ODC inhibitor in mouse brain.
- To investigate the developmental regulation of ODC and antizyme in mouse brain.
- To explore the relationship between ODC, antizyme, and ODC activity during mouse brain development.
Main Methods:
- Enzyme kinetics assays.
- Immunochemical analysis using monoclonal antibodies.
- Radioimmunoassay for ODC protein.
- Cycloheximide treatment to assess protein stability.
Main Results:
- A macromolecular inhibitor, identified as ODC antizyme, was found in mouse brain.
- Mouse brain antizyme did not cross-react immunochemically with antibodies to rat liver antizyme.
- ODC activity and putrescine content decreased postnatally, while free antizyme activity increased.
- An ODC-antizyme complex was present at birth and decreased, with inactive ODC protein detected later.
- Cycloheximide treatment rapidly degraded ODC activity and the ODC-antizyme complex, but not free antizyme or inactive ODC protein.
Conclusions:
- Mouse brain contains a distinct ODC antizyme.
- Developmental changes in mouse brain involve dynamic regulation of ODC and antizyme.
- Inactive ODC protein and free antizyme are relatively stable, suggesting distinct regulatory mechanisms.