Nuclear Chk1 prevents premature mitotic entry
Makoto Matsuyama1, Hidemasa Goto, Kousuke Kasahara
1Division of Biochemistry, Aichi Cancer Center Research Institute, Chikusa-ku, Nagoya 464-8681, Japan. minagaki@aichi-cc.jp
Journal of Cell Science
|June 2, 2011
Summary
Nuclear Chk1 (Checkpoint kinase 1) regulates the timing of mitotic entry, while centrosomal staining was found to be a false positive. This clarifies Chk1
Area of Science:
- Cell cycle regulation
- Molecular biology
- Cancer research
Background:
- Checkpoint kinase 1 (Chk1) is known to inhibit cyclin-B1-Cdk1 activation, preventing premature mitosis.
- The precise location where Chk1 exerts its inhibitory function (nucleus or centrosome) before the G2-M transition is debated.
Purpose of the Study:
- To investigate the specific role of Chk1 localization in regulating the timing of mitotic entry.
- To determine whether Chk1 functions in the nucleus or centrosome before the G2-M transition.
Main Methods:
- Utilized a specific anti-Chk1 antibody (DCS-310) and conditional Chk1 knockout mouse embryonic fibroblasts.
- Employed anti-Myc antibody in Chk1(+/myc) human colon adenocarcinoma (DLD-1) cells.
- Combined protein array and RNAi technologies to identify cross-reacting proteins.
- Generated Chk1 mutants with altered subcellular localization (nuclear vs. centrosomal).
Main Results:
- The anti-Chk1 antibody DCS-310 showed cross-reactivity with Ccdc-151 at the centrosome.
- Conditional Chk1 knockout reduced nuclear staining but not centrosomal staining with DCS-310.
- Chk1 was detected in the nucleus, not the centrosome, in DLD-1 cells.
- Nuclear Chk1 localization delayed mitotic entry, whereas centrosomal Chk1 had minimal impact.
Conclusions:
- Nuclear Chk1, not centrosomal Chk1, is crucial for the correct timing of mitotic entry.
- The anti-Chk1 antibody DCS-310 can lead to misinterpretation of Chk1 localization at the centrosome due to cross-reactivity.
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