Centrosome-associated Chk1 prevents premature activation of cyclin-B-Cdk1 kinase

TY - JOUR

T1 - Centrosome-associated Chk1 prevents premature activation of cyclin-B-Cdk1 kinase

AU - Krämer, Alwin

AU - Mailand, Niels

AU - Lukas, Claudia

AU - Syljuåsen, Randi G

AU - Wilkinson, Christopher J

AU - Nigg, Erich A

AU - Bartek, Jiri

AU - Lukas, Jiri

PY - 2004/9

Y1 - 2004/9

N2 - Entry into mitosis occurs after activation of Cdk1, resulting in chromosome condensation in the nucleus and centrosome separation, as well as increased microtubule nucleation activity in the cytoplasm. The active cyclin-B1-Cdk1 complex first appears at the centrosome, suggesting that the centrosome may facilitate the activation of mitotic regulators required for the commitment of cells to mitosis. However, the signalling pathways involved in controlling the initial activation of Cdk1 at the centrosome remain largely unknown. Here, we show that human Chk1 kinase localizes to interphase, but not mitotic, centrosomes. Chemical inhibition of Chk1 resulted in premature centrosome separation and activation of centrosome-associated Cdk1. Forced immobilization of kinase-inactive Chk1 to centrosomes also resulted in premature Cdk1 activation. Conversely, under such conditions wild-type Chk1 impaired activation of centrosome-associated Cdk1, thereby resulting in DNA endoreplication and centrosome amplification. Activation of centrosomal Cdk1 in late prophase seemed to be mediated by cytoplasmic Cdc25B, whose activity is controlled by centrosome-associated Chk1. These results suggest that centrosome-associated Chk1 shields centrosomal Cdk1 from unscheduled activation by cytoplasmic Cdc25B, thereby contributing to proper timing of the initial steps of cell division, including mitotic spindle formation.

AB - Entry into mitosis occurs after activation of Cdk1, resulting in chromosome condensation in the nucleus and centrosome separation, as well as increased microtubule nucleation activity in the cytoplasm. The active cyclin-B1-Cdk1 complex first appears at the centrosome, suggesting that the centrosome may facilitate the activation of mitotic regulators required for the commitment of cells to mitosis. However, the signalling pathways involved in controlling the initial activation of Cdk1 at the centrosome remain largely unknown. Here, we show that human Chk1 kinase localizes to interphase, but not mitotic, centrosomes. Chemical inhibition of Chk1 resulted in premature centrosome separation and activation of centrosome-associated Cdk1. Forced immobilization of kinase-inactive Chk1 to centrosomes also resulted in premature Cdk1 activation. Conversely, under such conditions wild-type Chk1 impaired activation of centrosome-associated Cdk1, thereby resulting in DNA endoreplication and centrosome amplification. Activation of centrosomal Cdk1 in late prophase seemed to be mediated by cytoplasmic Cdc25B, whose activity is controlled by centrosome-associated Chk1. These results suggest that centrosome-associated Chk1 shields centrosomal Cdk1 from unscheduled activation by cytoplasmic Cdc25B, thereby contributing to proper timing of the initial steps of cell division, including mitotic spindle formation.

KW - CDC2 Protein Kinase

KW - Cell Cycle Proteins

KW - Cell Division

KW - Cell Line

KW - Centrosome

KW - Cyclin B

KW - Cyclin B1

KW - Cyclins

KW - Enzyme Activation

KW - Humans

KW - Interphase

KW - Microscopy, Confocal

KW - Protein Binding

KW - Protein Kinases

KW - Spindle Apparatus

KW - cdc25 Phosphatases

U2 - 10.1038/ncb1165

DO - 10.1038/ncb1165

M3 - Journal article

C2 - 15311285

SN - 1465-7392

VL - 6

SP - 884

EP - 891

JO - Nature Cell Biology

JF - Nature Cell Biology

IS - 9

ER -