A novel kinase-independent function of Chk1 in the replication of damaged DNA

SPERONI J, MANSILLA S, FEDERICO MF, HABIF M AND GOTTIFREDI V

Cold Spring Harbor Laboratories

Congreso; Cold Spring harbour meeting. EUKARYOTIC DNA REPLICATION AND GENOME MAINTENANCE; 2010

Cold Spring Harbor Laboratories

Chk1 is broadly known as a central kinase involved in the cell cycle response to the accumulation of damaged DNA. The kinase activity of Chk1 is also essential for unperturbed DNA replication. The activation of Chk1 is totally dependent on its phosphorylation by ATR and in general, the negative regulation of ATR or Chk1 cause similar consequences in cells. Intriguingly, using DNA combing technology and specific siRNA-dependent downregulation, we have observed that Chk1 contribution to the maintenance of fork progression after an UV insult is more robust when compared to ATR. In line with this, we found that the kinase domain of Chk1 is not required for the maintenance of fork progression immediately after UV irradiation. Instead, a recently identified motif of Chk1 involved in its release from chromatin is necessary to maintain replication fork progression after UV-induced DNA damage. Moreover, this motif of Chk1 also promotes the organization of the specialized polymerase pol eta into subnuclear focal structures. This is particularly interesting since pol eta sustains DNA synthesis by using UV-damaged DNA as templates for replication. Together, our data put forward a potential kinase-independent contribution of Chk1 to the replication of damaged DNA.