Chk1 is an essential kinase that is regulated by Atr and required for the G2/M DNA damage checkpoint
- Qinghua Liu1,2,3,
- Saritha Guntuku1,2,
- Xian-Shu Cui4,
- Shuhei Matsuoka1,2,
- David Cortez1,2,
- Katsuyuki Tamai7,
- Guangbin Luo1,5,
- Sandra Carattini-Rivera1,5,
- Francisco DeMayo6,
- Allan Bradley1,5,
- Larry A. Donehower4,6, and
- Stephen J. Elledge1,2,5,8
- 1Howard Hughes Medical Institute, 2Verna and Marrs McLean Department of Biochemistry, 3Program in Cell and Molecular Biology, 4Department of Molecular Virology and Microbiology, 5Department of Molecular and Human Genetics, and 6Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030 USA; 7Medical and Biological Laboratories Co., Ltd., Ina, Nagano 396-0002, Japan
Abstract
Chk1, an evolutionarily conserved protein kinase, has been implicated in cell cycle checkpoint control in lower eukaryotes. By gene disruption, we show that CHK1 deficiency results in a severe proliferation defect and death in embryonic stem (ES) cells, and peri-implantation embryonic lethality in mice. Through analysis of a conditional CHK1-deficient cell line, we demonstrate that ES cells lacking Chk1 have a defective G2/M DNA damage checkpoint in response to γ-irradiation (IR). CHK1heterozygosity modestly enhances the tumorigenesis phenotype ofWNT-1 transgenic mice. We show that in human cells, Chk1 is phosphorylated on serine 345 (S345) in response to UV, IR, and hydroxyurea (HU). Overexpression of wild-type Atr enhances, whereas overexpression of the kinase-defective mutant Atr inhibits S345 phosphorylation of Chk1 induced by UV treatment. Taken together, these data indicate that Chk1 plays an essential role in the mammalian DNA damage checkpoint, embryonic development, and tumor suppression, and that Atr regulates Chk1.
Keywords
Footnotes
-
↵8 Corresponding author.
-
E-MAIL selledge{at}bcm.tmc.edu; FAX (713) 798-8717.
-
- Received March 20, 2000.
- Accepted May 1, 2000.
- Cold Spring Harbor Laboratory Press
