Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - DPC_REPAIR (Mechanism of DNA-protein cross-link repair in S phase)

Teaser

We are addressing how a specific type of DNA lesion known as DNA-protein crosslink is repaired during DNA replication.This is highly relevant to society because DNA-protein crosslinks are highly cytotoxic lesions known to trigger cancer in humans. Moreover, DNA-protein...

Summary

We are addressing how a specific type of DNA lesion known as DNA-protein crosslink is repaired during DNA replication.
This is highly relevant to society because DNA-protein crosslinks are highly cytotoxic lesions known to trigger cancer in humans. Moreover, DNA-protein crosslinks are the byproduct of most chemotherapeutic drugs used in the clinic to treat cancer.
Thus, if we can understand how DNA-protein crosslinks are repaired, we will be able to develop new treatments to fight cancer in the futur.

Work performed

\"During the first 18 months of this project, we addressed parts of aim 1 and aim 2 of my ERC proposal.

Particularly, we have delineated the molecular function of DVC1 in DPC repair (aim 1.1 and aim 1.3) and we provide the molecular events that activate and target the protease to DNA-protein crosslinks (aim 2.1). Contrary to what was anticipated, DVC1-mediated DPC degradation does not require DPC ubiquitylation. Instead the protease is activated when a nascent strand is extended to the lesion which appears to be the essential event that targets the protease.

We have also established collaborations to identify new factors involved in DNA-protein crosslink repair by mass spectrometry (aim 2.3). We have conducted a big mass spectrometry screen to identify the main factors that are recruited to replicating DNA protein crosslinks containing plasmids in Xenopus egg extracts. This unbiased screen revealed that the proteasome was specifically recruited to DPC containing plasmids and we provide evidence that the proteasome degrades DNA-protein crosslinks that are ubiquitylated during replication. The proteasome appears to act as a new independent pathway of DNA-protein crosslink degradation during S phase. We are also trying to identify the E3 ligase that is responsible for ubiquitylating DNA-protein crosslinks during replication. These investigations are all part of aim 2.

These findings are currently under review at Molecular Cell and were made publically available on BioRxiv (MS ID#: BIORXIV/2018/381889).\"

Final results

Our findings provide new and important mechanistic insights on how DNA-protein crosslinks are repaired which go well beyond the state of the art of the field. Moreover, they have identified new factors that participate in the repair reaction. These factors provide new attractive targets for drug development that could be used to sensitise cells to chemotherapeutic drugs.