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Protein kinase A is required for chromosomal DNA replication
V Costanzo1, E V Avvedimento, M E Gottesman
1Dipartimento di Biologia e Patologia Molecolare e Cellulare "L. Califano", c/o Centro di Endocrinologia ed Oncologia Sperimentale del CNR, II Medical School, University of Naples, Via S. Pansini 5, Naples, 80131, Italy.
Current Biology : CB
|September 2, 1999
Summary
Protein kinase A (PKA) activity, peaking in late mitosis, is essential for initiating DNA replication. PKA ensures proper cell cycle progression by regulating the release of Cdc6 from chromatin, preventing DNA over-replication.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Cell cycle progression requires precise regulation of DNA replication.
- The pre-replication complex (ORC, Cdc6, MCM) assembles on chromatin during late mitosis.
- Cyclin-dependent kinases (Cdks) and nuclear membrane dynamics control replication initiation and prevent re-replication.
Purpose of the Study:
- To investigate the role of protein kinase A (PKA) oscillations in regulating DNA replication.
- To determine the specific stage and mechanism by which PKA influences the cell cycle.
- To elucidate PKA's requirement for the transition from mitosis to S phase.
Main Methods:
- Utilized Xenopus egg extracts to study cell cycle events.
- Monitored PKA activity oscillations during the cell cycle.
- Assessed the impact of PKA inhibition on pre-replication complex assembly and DNA replication.
Main Results:
- PKA activity oscillates, peaking in late mitosis, and is induced by M-phase-promoting Cdk.
- PKA is required from mitosis exit until nuclear envelope formation.
- PKA inhibition blocked Cdc6 release from chromatin, inhibiting DNA replication.
- PKA is not required for the initial assembly of ORC2, Cdc6, and MCM3 on chromatin.
Conclusions:
- PKA activation in late M phase is crucial for initiating the subsequent S phase.
- PKA regulates DNA replication by controlling the release of Cdc6, a key event for replication initiation.
- These findings highlight PKA as a critical regulator linking mitosis exit to S phase entry.