The cell-cycle checkpoint kinase Chk1 is required for mammalian homologous recombination repair.

TY - JOUR

T1 - The cell-cycle checkpoint kinase Chk1 is required for mammalian homologous recombination repair.

AU - Sørensen, Claus Storgaard

AU - Hansen, Lasse Tengbjerg

AU - Dziegielewski, Jaroslaw

AU - Syljuåsen, Randi G

AU - Lundin, Cecilia

AU - Bartek, Jiri

AU - Helleday, Thomas

N1 - Keywords: Animals; Camptothecin; Cricetinae; DNA; DNA Damage; DNA Repair; DNA-Binding Proteins; Humans; Hydroxyurea; Protein Kinases; Rad51 Recombinase; Recombination, Genetic; Signal Transduction

PY - 2005

Y1 - 2005

N2 - The essential checkpoint kinase Chk1 is required for cell-cycle delays after DNA damage or blocked DNA replication. However, it is unclear whether Chk1 is involved in the repair of damaged DNA. Here we establish that Chk1 is a key regulator of genome maintenance by the homologous recombination repair (HRR) system. Abrogation of Chk1 function with small interfering RNA or chemical antagonists inhibits HRR, leading to persistent unrepaired DNA double-strand breaks (DSBs) and cell death after replication inhibition with hydroxyurea or DNA-damage caused by camptothecin. After hydroxyurea treatment, the essential recombination repair protein RAD51 is recruited to DNA repair foci performing a vital role in correct HRR. We demonstrate that Chk1 interacts with RAD51, and that RAD51 is phosphorylated on Thr 309 in a Chk1-dependent manner. Consistent with a functional interplay between Chk1 and RAD51, Chk1-depleted cells failed to form RAD51 nuclear foci after exposure to hydroxyurea, and cells expressing a phosphorylation-deficient mutant RAD51(T309A) were hypersensitive to hydroxyurea. These results highlight a crucial role for the Chk1 signalling pathway in protecting cells against lethal DNA lesions through regulation of HRR.

AB - The essential checkpoint kinase Chk1 is required for cell-cycle delays after DNA damage or blocked DNA replication. However, it is unclear whether Chk1 is involved in the repair of damaged DNA. Here we establish that Chk1 is a key regulator of genome maintenance by the homologous recombination repair (HRR) system. Abrogation of Chk1 function with small interfering RNA or chemical antagonists inhibits HRR, leading to persistent unrepaired DNA double-strand breaks (DSBs) and cell death after replication inhibition with hydroxyurea or DNA-damage caused by camptothecin. After hydroxyurea treatment, the essential recombination repair protein RAD51 is recruited to DNA repair foci performing a vital role in correct HRR. We demonstrate that Chk1 interacts with RAD51, and that RAD51 is phosphorylated on Thr 309 in a Chk1-dependent manner. Consistent with a functional interplay between Chk1 and RAD51, Chk1-depleted cells failed to form RAD51 nuclear foci after exposure to hydroxyurea, and cells expressing a phosphorylation-deficient mutant RAD51(T309A) were hypersensitive to hydroxyurea. These results highlight a crucial role for the Chk1 signalling pathway in protecting cells against lethal DNA lesions through regulation of HRR.

U2 - 10.1038/ncb1212

DO - 10.1038/ncb1212

M3 - Journal article

C2 - 15665856

SN - 1465-7392

VL - 7

SP - 195

EP - 201

JO - Nature Cell Biology

JF - Nature Cell Biology

IS - 2

ER -