Dataset Information

Role of RPA Phosphorylation in the ATR-Dependent G2 Cell Cycle Checkpoint.

ABSTRACT: Cells respond to DNA double-strand breaks by initiating DSB repair and ensuring a cell cycle checkpoint. The primary responder to DSB repair is non-homologous end joining, which is an error-prone repair pathway. However, when DSBs are generated after DNA replication in the G2 phase of the cell cycle, a second DSB repair pathway, homologous recombination, can come into action. Both ATM and ATR are important for DSB-induced DSB repair and checkpoint responses. One method of ATM and ATR working together is through the DNA end resection of DSBs. As a readout and marker of DNA end resection, RPA is phosphorylated at Ser4/Ser8 of the N-terminus of RPA32 in response to DSBs. Here, the significance of RPA32 Ser4/Ser8 phosphorylation in response to DNA damage, specifically in the S phase to G2 phase of the cell cycle, is examined. RPA32 Ser4/Ser8 phosphorylation in G2 synchronized cells is necessary for increases in TopBP1 and Rad9 accumulation on chromatin and full activation of the ATR-dependent G2 checkpoint. In addition, our data suggest that RPA Ser4/Ser8 phosphorylation modulates ATM-dependent KAP-1 phosphorylation and Rad51 chromatin loading in G2 cells. Through the phosphorylation of RPA Ser4/Ser8, ATM acts as a partner with ATR in the G2 phase checkpoint response, regulating key downstream events including Rad9, TopBP1 phosphorylation and KAP-1 phosphorylation/activation via the targeting of RPA32 Ser4/Ser8.

SUBMITTER: Liu S

PROVIDER: S-EPMC10742774 | biostudies-literature | 2023 Dec

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Role of RPA Phosphorylation in the ATR-Dependent G2 Cell Cycle Checkpoint.

Liu Shengqin S Byrne Brendan M BM Byrne Thomas N TN Oakley Gregory G GG

Genes 20231213 12

Cells respond to DNA double-strand breaks by initiating DSB repair and ensuring a cell cycle checkpoint. The primary responder to DSB repair is non-homologous end joining, which is an error-prone repair pathway. However, when DSBs are generated after DNA replication in the G2 phase of the cell cycle, a second DSB repair pathway, homologous recombination, can come into action. Both ATM and ATR are important for DSB-induced DSB repair and checkpoint responses. One method of ATM and ATR working tog ...[more]

PMID: 38137027

Similar Datasets

Project description:Cell cycle checkpoints, activated by stressful events, halt the cell cycle progression, and prevent the transmission of damaged DNA. These checkpoints prompt cell repair but also trigger cell death if damage persists. Decision-making between these responses is multifactorial and context-dependent, with the tumor suppressor p53 playing a central role. In many tumor cells, p53 alterations lead to G1/S checkpoint loss and the weakening of the G2 checkpoint, rendering cell viability dependent on the strength of the latter through mechanisms not fully characterized. Cells with a strong pro-survival drive can evade cell death despite substantial DNA lesions. Deciphering the integration of survival pathways with p53-dependent and -independent mechanisms governing the G2/M transition is crucial for understanding G2 arrest functionality and predicting tumor cell response to chemotherapy. The serine/threonine kinase GRK2 emerges as a signaling node in cell cycle modulation. In cycling cells, but not in G2 checkpoint-arrested cells, GRK2 protein levels decline during G2/M transition through a process triggered by CDK2-dependent phosphorylation of GRK2 at the S670 residue and Mdm2 ubiquitination. We report now that this downmodulation in G2 prevents the unscheduled activation of the PI3K/AKT pathway, allowing cells to progress into mitosis. Conversely, higher GRK2 levels lead to tyrosine phosphorylation by the kinase c-Abl, promoting the direct association of GRK2 with the p85 regulatory subunit of PI3K and AKT activation in a GRK2 catalytic-independent manner. Hyperactivation of AKT is conditioned by p53's scaffolding function, triggering FOXO3a phosphorylation, impaired Cyclin B1 accumulation, and CDK1 activation, causing a G2/M transition delay. Upon G2 checkpoint activation, GRK2 potentiates early arrest independently of p53 through AKT activation. However, its ability to overcome the G2 checkpoint in viable conditions depends on p53. Our results suggest that integrating the GRK2/PI3K/AKT axis with non-canonical functions of p53 might confer a survival advantage to tumor cells.

Dataset Information

Role of RPA Phosphorylation in the ATR-Dependent G2 Cell Cycle Checkpoint.

Publications

Role of RPA Phosphorylation in the ATR-Dependent G2 Cell Cycle Checkpoint.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets