Destabilization of the MiniChromosome Maintenance (MCM) complex modulates the cellular response to DNA double strand breaks induced by Etoposide.

ABSTRACT: DNA replication during S phase involves thousands of replication forks that must be coordinated to ensure that every DNA section is only replicated once. The minichromosome maintenance proteins, MCM2 to MCM7, form a heteromeric DNA helicase required for both initiation of DNA replication and elongation of DNA replication. Although only two DNA helicase activities are required to establish a bidirectional replication fork from each origin of replication, a large excess of MCM complexes is loaded and distributed along the chromatin. The function of the additional MCM complexes is not well understood, as most of them are displaced from the DNA during S-phase, apparently without playing an active role in DNA replication. DNA damage response (DDR) kinases activated by stalled forks prevent the replication machinery from being activated, indicating a tight relationship between DDR and DNA replication. To investigate the role of MCM proteins in the cellular response to DNA damage, we used shRNA targeting MCM2 or MCM3 to determine the impact of the reduction of the MCM complex. The alteration of MCM proteins induced a change in the activation of important factors of the DDR in response to Etoposide treatment. The phosphorylation of γ-H2AX, CHK1 and CHK2 is affected following DNA damage induced by treatment with Etoposide without affecting cell viability. Using assays measuring homologous recombination (HR) and non-homologous end-joining (NHEJ), we have identified a decrease of HR, but not NHEJ, associated with a decrease of the MCM complex demonstrating a role for the MCM complex in homologous recombination.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Epithelial Cell, Cell Culture

DISEASE(S): Colon Cancer

SUBMITTER: Francois-Michel Boisvert  

LAB HEAD: Francois-Michel Boisvert

PROVIDER: PXD009539 | Pride | 2019-11-12

REPOSITORIES: Pride