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Mre11 exonuclease activity removes the chain-terminating nucleoside analog gemcitabine from the nascent strand during
L Boeckemeier1, R Kraehenbuehl1,2, A Keszthelyi1
1North West Cancer Research Institute, School of Medical Sciences, Bangor University, Bangor, Gwynedd LL57 2UW, UK.
Abstract:
The Mre11 nuclease is involved in early responses to DNA damage, often mediated by its role in DNA end processing. MRE11 mutations and aberrant expression are associated with carcinogenesis and cancer treatment outcomes. While, in recent years, progress has been made in understanding the role of Mre11 nuclease activities in DNA double-strand break repair, their role during replication has remained elusive. The nucleoside analog gemcitabine, widely used in cancer therapy, acts as a replication chain terminator; for a cell to survive treatment, gemcitabine needs to be removed from replicating DNA. Activities responsible for this removal have, so far, not been identified. We show that Mre11 3' to 5' exonuclease activity removes gemcitabine from nascent DNA during replication. This contributes to replication progression and gemcitabine resistance. We thus uncovered a replication-supporting role for Mre11 exonuclease activity, which is distinct from its previously reported detrimental role in uncontrolled resection in recombination-deficient cells.
Insights
The Mre11 nuclease
Area of Science:
- Molecular Biology
- DNA Repair
- Cancer Research
Background:
- Mre11 nuclease is crucial for DNA damage response and DNA end processing.
- MRE11 mutations are linked to cancer development and treatment efficacy.
- Mre11's role in DNA replication, particularly in response to chemotherapeutics, remains unclear.
Purpose of the Study:
- To investigate the role of Mre11 nuclease activity in DNA replication.
- To identify the cellular mechanisms responsible for removing gemcitabine from replicating DNA.
Main Methods:
- Utilized molecular biology techniques to study Mre11 nuclease activity.
- Investigated the impact of Mre11 on gemcitabine removal during DNA replication.
Main Results:
- Mre11's 3' to 5' exonuclease activity removes gemcitabine from nascent DNA during replication.
- This activity supports replication progression and confers gemcitabine resistance.
- Discovered a novel replication-promoting function for Mre11 exonuclease activity.
Conclusions:
- Mre11 exonuclease activity plays a vital role in removing replication-blocking chemotherapeutics like gemcitabine.
- This finding reveals a distinct, replication-supportive function of Mre11, separate from its known roles in DNA repair.
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