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Updated: Oct 25, 2025
Visualizing and Quantifying Endonuclease-Based Site-Specific DNA Damage
Published on: August 21, 2021
Epithelial cell transforming factor ECT2 is an important regulator of DNA double-strand break repair and genome
Cheng Cao1, Peiyi Han1, Ling Liu1
1Tianjin Medical University Cancer Institute and Hospital, The Province and Ministry Co-Sponsored Collaborative Innovation Center for Medical Epigenetics, Key Laboratory of Immune Microenvironment and Disease (Ministry of Education), Key Laboratory of Breast Cancer Prevention and Therapy (Ministry of Education), School of Basic Medical Sciences, Tianjin Medical University, Tianjin, China.
Abstract:
Proteins containing breast cancer type 1 (BRCA1) C-terminal domains play crucial roles in response to and repair of DNA damage. Epithelial cell transforming factor (epithelial cell transforming sequence 2 [ECT2]) is a member of the BRCA1 C-terminal protein family, but it is not known if ECT2 directly contributes to DNA repair. In this study, we report that ECT2 is recruited to DNA lesions in a poly (ADP-ribose) polymerase 1-dependent manner. Using co-immunoprecipitation analysis, we showed that ECT2 physically associates with KU70-KU80 and BRCA1, proteins involved in nonhomologous end joining and homologous recombination, respectively. ECT2 deficiency impairs the recruitment of KU70 and BRCA1 to DNA damage sites, resulting in defective DNA double-strand break repair, an accumulation of damaged DNA, and hypersensitivity of cells to genotoxic insults. Interestingly, we demonstrated that ECT2 promotes DNA repair and genome integrity largely independently of its canonical guanine nucleotide exchange activity. Together, these results suggest that ECT2 is directly involved in DNA double-strand break repair and is an important genome caretaker.
Insights
Epithelial cell transforming sequence 2 (ECT2) protein directly aids DNA double-strand break repair by associating with key repair proteins. This function is vital for maintaining genome integrity and preventing DNA damage accumulation.
Area of Science:
- Molecular Biology
- Genetics
- Cell Biology
Background:
- Proteins with BRCA1 C-terminal domains are critical for DNA damage response and repair.
- The role of Epithelial cell transforming sequence 2 (ECT2) in direct DNA repair remains unclear.
Purpose of the Study:
- To investigate the direct involvement of ECT2 in DNA double-strand break repair pathways.
- To elucidate the mechanism by which ECT2 contributes to genome integrity.
Main Methods:
- Recruitment of ECT2 to DNA lesions was assessed.
- Co-immunoprecipitation was used to identify ECT2 interacting proteins.
- DNA repair assays were performed in ECT2-deficient cells.
Main Results:
- ECT2 is recruited to DNA lesions dependent on poly (ADP-ribose) polymerase 1.
- ECT2 physically interacts with KU70-KU80 and BRCA1.
- ECT2 deficiency leads to impaired DNA repair, DNA damage accumulation, and increased sensitivity to genotoxic agents.
- ECT2 promotes DNA repair independently of its guanine nucleotide exchange activity.
Conclusions:
- ECT2 plays a direct role in DNA double-strand break repair.
- ECT2 functions as a critical genome caretaker, independent of its canonical enzymatic activity.
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