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ATM-dependent Phosphorylation of the Fanconi Anemia Protein PALB2 Promotes the DNA Damage Response
Yingying Guo1, Wanjuan Feng1, Shirley M H Sy2
1From the School of Biomedical Sciences.
Abstract:
The Fanconi anemia protein PALB2, also known as FANCN, protects genome integrity by regulating DNA repair and cell cycle checkpoints. Exactly how PALB2 functions may be temporally coupled with detection and signaling of DNA damage is not known. Intriguingly, we found that PALB2 is transformed into a hyperphosphorylated state in response to ionizing radiation (IR). IR treatment specifically triggered PALB2 phosphorylation at Ser-157 and Ser-376 in manners that required the master DNA damage response kinase Ataxia telangiectasia mutated, revealing potential mechanistic links between PALB2 and the Ataxia telangiectasia mutated-dependent DNA damage responses. Consistently, dysregulated PALB2 phosphorylation resulted in sustained activation of DDRs. Full-blown PALB2 phosphorylation also required the breast and ovarian susceptible gene product BRCA1, highlighting important roles of the BRCA1-PALB2 interaction in orchestrating cellular responses to genotoxic stress. In summary, our phosphorylation analysis of tumor suppressor protein PALB2 uncovers new layers of regulatory mechanisms in the maintenance of genome stability and tumor suppression.
Insights
The Fanconi anemia protein PALB2 (also known as FANCN) becomes hyperphosphorylated after DNA damage, a process crucial for genome stability. This phosphorylation, regulated by ATM and BRCA1, is vital for DNA damage response signaling.
Area of Science:
- Molecular Biology
- Genetics
- Cancer Research
Background:
- PALB2 (FANCN) is a key protein in maintaining genome integrity through DNA repair and cell cycle checkpoints.
- The precise temporal regulation of PALB2 function during DNA damage response is not fully understood.
Purpose of the Study:
- To investigate the post-translational modifications of PALB2 in response to DNA damage.
- To elucidate the role of specific kinases, such as ATM, and interacting proteins, like BRCA1, in regulating PALB2 function during genotoxic stress.
Main Methods:
- Analysis of PALB2 phosphorylation status following ionizing radiation (IR) exposure.
- Investigating the requirement of ATM and BRCA1 for IR-induced PALB2 phosphorylation.
- Assessing the impact of dysregulated PALB2 phosphorylation on DNA damage response (DDR) activation.
Main Results:
- PALB2 undergoes hyperphosphorylation in response to IR, specifically at Ser-157 and Ser-376.
- This phosphorylation is dependent on the DNA damage response kinase ATM.
- BRCA1 is essential for full PALB2 phosphorylation, underscoring the importance of the BRCA1-PALB2 complex in cellular stress responses.
- Altered PALB2 phosphorylation leads to sustained activation of DDR pathways.
Conclusions:
- PALB2 phosphorylation is a critical regulatory mechanism in response to DNA damage.
- The ATM and BRCA1-dependent phosphorylation of PALB2 highlights its integration into established DNA damage response networks.
- These findings reveal novel regulatory layers for genome stability and tumor suppression mediated by PALB2.
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