Related Experiment Videos
Activation of the protein kinase p38 in the spindle assembly checkpoint and mitotic arrest
K Takenaka1, T Moriguchi, E Nishida
1Department of Biophysics, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo-ku, Kyoto 606-01, Japan.
Abstract:
The mitogen-activated protein kinase (MAPK) superfamily comprises classical MAPK (also called ERK), c-Jun amino-terminal or stress-activated protein kinase (JNK or SAPK), and p38. Although MAPK is essential for meiotic processes in Xenopus oocytes and the spindle assembly checkpoint in Xenopus egg extracts, the role of members of the MAPK superfamily in M phase or the spindle assembly checkpoint during somatic cell cycles has not been elucidated. The kinase p38, but not MAPK or JNK, was activated in mammalian cultured cells when the cells were arrested in M phase by disruption of the spindle with nocodazole. Addition of activated recombinant p38 to Xenopus cell-free extracts caused arrest of the extracts in M phase, and injection of activated p38 into cleaving embryos induced mitotic arrest. Treatment of NIH 3T3 cells with a specific inhibitor of p38 suppressed activation of the checkpoint by nocodazole. Thus, p38 functions as a component of the spindle assembly checkpoint in somatic cell cycles.
Insights
The p38 kinase is activated during M phase arrest in somatic cells. This study reveals p38
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- The mitogen-activated protein kinase (MAPK) superfamily, including ERK, JNK, and p38, plays critical roles in cellular processes.
- While MAPK is known to be essential for meiotic processes and the spindle assembly checkpoint in Xenopus oocytes and egg extracts, its role in somatic cell M phase and spindle assembly checkpoint remains unclear.
Purpose of the Study:
- To investigate the role of MAPK superfamily members, specifically p38, in the spindle assembly checkpoint during somatic cell cycles.
- To determine if p38 activation is involved in M phase arrest induced by spindle disruption in mammalian cells.
Main Methods:
- Activation of p38 kinase in mammalian cultured cells arrested in M phase by nocodazole treatment.
- Addition of activated recombinant p38 to Xenopus cell-free extracts to observe M phase arrest.
- Injection of activated p38 into Xenopus embryos to assess mitotic arrest.
- Treatment of NIH 3T3 cells with a p38 inhibitor to evaluate its effect on spindle assembly checkpoint activation.
Main Results:
- p38 kinase, but not MAPK or JNK, was activated in mammalian cells arrested in M phase due to spindle disruption.
- Activated p38 induced M phase arrest in Xenopus cell-free extracts and mitotic arrest in cleaving embryos.
- Inhibition of p38 activity suppressed nocodazole-induced spindle assembly checkpoint activation in NIH 3T3 cells.
Conclusions:
- p38 kinase functions as a key component of the spindle assembly checkpoint in somatic cell cycles.
- p38 activation is crucial for mediating M phase arrest in response to spindle damage during mitosis.