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Cell cycle-dependent regulation of pyrimidine biosynthesis
Frederic D Sigoillot1, J Andrew Berkowski, Severine M Sigoillot
1Department of Biochemistry and Molecular Biology, Wayne State University School of Medicine, Detroit, Michigan 48201,USA.
The Journal of Biological Chemistry
|November 20, 2002
Summary
Pyrimidine biosynthesis is upregulated during S phase to meet DNA synthesis demands. This regulation is controlled by the phosphorylation of the CAD protein, influenced by MAPK and PKA signaling cascades.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- De novo pyrimidine biosynthesis is crucial for proliferating cells requiring nucleotides for DNA synthesis.
- Cell cycle progression involves dynamic regulation of metabolic pathways to meet cellular demands.
Purpose of the Study:
- To investigate the cell cycle-dependent regulation of de novo pyrimidine biosynthesis.
- To elucidate the role of the multifunctional protein CAD and its regulatory mechanisms in mammalian pyrimidine synthesis.
Main Methods:
- Synchronization of baby hamster kidney cells using serum deprivation.
- Analysis of pyrimidine biosynthetic pathway activity and nucleotide pools during the cell cycle.
- Investigation of the allosteric regulation of CAD, including its phosphorylation status and modulation by MAPK and PKA.
Main Results:
- Pyrimidine biosynthesis was upregulated 1.9-fold during S phase and downregulated as cells progressed through the cycle.
- Nucleotide pools were depleted and replenished during cell division, indicating utilization matched formation.
- Altered allosteric regulation of CAD, including sensitivity to 5-phosphoribosyl-1-pyrophosphate and loss of UTP inhibition, correlated with S phase.
- CAD phosphorylation by MAPK and PKA, and subsequent dephosphorylation, precisely controlled pathway activation and termination.
Conclusions:
- Cell cycle-dependent regulation of pyrimidine biosynthesis is achieved through sequential phosphorylation and dephosphorylation of CAD.
- MAPK and PKA signaling cascades orchestrate the precise timing of CAD activation and deactivation, ensuring adequate nucleotide supply for DNA synthesis.