title: Nuclear Chk1 prevents premature mitotic entry.
abstract: Chk1 inhibits the premature activation of the cyclin-B1-Cdk1. However, it remains controversial whether Chk1 inhibits Cdk1 in the centrosome or in the nucleus before the G2-M transition. In this study, we examined the specificity of the mouse monoclonal anti-Chk1 antibody DCS-310, with which the centrosome was stained. Conditional Chk1 knockout in mouse embryonic fibroblasts reduced nuclear but not centrosomal staining with DCS-310. In Chk1(+/myc) human colon adenocarcinoma (DLD-1) cells, Chk1 was detected in the nucleus but not in the centrosome using an anti-Myc antibody. Through the combination of protein array and RNAi technologies, we identified Ccdc-151 as a protein that crossreacted with DCS-310 on the centrosome. Mitotic entry was delayed by expression of the Chk1 mutant that localized in the nucleus, although forced immobilization of Chk1 to the centrosome had little impact on the timing of mitotic entry. These results suggest that nuclear but not centrosomal Chk1 contributes to correct timing of mitotic entry.
authors.affiliation: Division of Biochemistry, Aichi Cancer Center Research Institute, Chikusa-ku, Nagoya 464-8681, Japan. minagaki@aichi-cc.jp
authors.forename: Makoto
authors.initials: M
authors.lastname: Matsuyama
authors.forename: Hidemasa
authors.initials: H
authors.lastname: Goto
authors.forename: Kousuke
authors.initials: K
authors.lastname: Kasahara
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Kawakami
authors.forename: Makoto
authors.initials: M
authors.lastname: Nakanishi
authors.forename: Tohru
authors.initials: T
authors.lastname: Kiyono
authors.forename: Naoki
authors.initials: N
authors.lastname: Goshima
authors.forename: Masaki
authors.initials: M
authors.lastname: Inagaki
mesh_terms: D000818:Animals; D016203:CDC2 Protein Kinase / Q000378:metabolism; D002453:Cell Cycle; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism*; D018385:Centrosome / Q000378:metabolism; D000071877:Checkpoint Kinase 1; D056744:Cyclin B1 / Q000235:genetics / Q000378:metabolism; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D008938:Mitosis; D009154:Mutation; D011494:Protein Kinases / Q000096:biosynthesis* / Q000235:genetics; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering
chemical_list: D056744:Cyclin B1; D016271:Proto-Oncogene Proteins c-myc; D034741:RNA, Small Interfering; D011494:Protein Kinases; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1; C000605869:Chek1 protein, mouse; D016203:CDC2 Protein Kinase