The spindle-stabilization function of Cdc14 is required to promote recombinational DNA repair

Abstract

Eukaryotic cells are constantly threatened by innumerable sources of genotoxic stresses that cause DNA damage. In order to maintain genome integrity, cells have developed a coordinated signaling network known as the DNA Damage Response (DDR). While numerous kinases have been thoroughly studied during the activation of the DDR, the role of protein phosphatases remains elusive. Previous data coming from our group have revealed the importance of the phosphatase Cdc14 in promoting recombinational DNA repair. However, how this phosphatase exerts its molecular function in the DDR is still unknown. Here we show that a DSB (double strand break) induced by the expression of the HO endonuclease is actively recruited to one of the SPBs (Spindle Pole Bodies). DSB-SPB interaction requires the N-terminus domain of the SPB protein Mps3 and a competent DNA damage checkpoint activation. Curiously, microtubules destabilization by nocodazole treatment during the induction of the DNA break disrupts SPB-DSB interaction and impairs HR (homologous recombination), indicating that SPB integrity and SPB-DSB binding are essential features of the DNA repair process. Surprisingly, inactivation of Cdc14 during the induction of the DNA lesion causes continuous misalignment of the metaphase spindle, increases oscillatory SPBs movements, and impairs DSB-SPB tethering, suggesting a role of the phosphatase in DNA repair by promoting spindle stability. In a screen looking for Cdc14 substrates at the SPBs after the induction of a DNA break, we identified Spc110, the intranuclear receptor for the γ-tubulin complex. Loss of Cdk-dependent Spc110 phosphorylation during DSB induction causes the same phenotypes as cdc14-1 mutants. Together, our results point to the function of Cdc14 in DNA repair by promoting SPB stabilization and SPB-DSB interaction, and suggest that the relocation of damage sites to the SPBs plays an important role in a naturally occurring repair process that minimizes genome instability.