Cdc7 kinase stimulates Aurora B kinase in M-phase

Sayuri Ito,Jiri Bartek,Kozo Tanaka,Gaik-Theng Toh,Kinue Kuniyasu,Hisao Masai,Masaaki Sawa,Masaki Inagaki,Mayumi Shindo,Hidemasa Goto,Masayuki Yamada

doi:10.1038/s41598-019-54738-2

Abstract

The conserved serine-threonine kinase, Cdc7, plays a crucial role in initiation of DNA replication by facilitating the assembly of an initiation complex. Cdc7 is expressed at a high level and exhibits significant kinase activity not only during S-phase but also during G2/M-phases. A conserved mitotic kinase, Aurora B, is activated during M-phase by association with INCENP, forming the chromosome passenger complex with Borealin and Survivin. We show that Cdc7 phosphorylates and stimulates Aurora B kinase activity in vitro. We identified threonine-236 as a critical phosphorylation site on Aurora B that could be a target of Cdc7 or could be an autophosphorylation site stimulated by Cdc7-mediated phosphorylation elsewhere. We found that threonines at both 232 (that has been identified as an autophosphorylation site) and 236 are essential for the kinase activity of Aurora B. Cdc7 down regulation or inhibition reduced Aurora B activity in vivo and led to retarded M-phase progression. SAC imposed by paclitaxel was dramatically reversed by Cdc7 inhibition, similar to the effect of Aurora B inhibition under the similar situation. Our data show that Cdc7 contributes to M-phase progression and to spindle assembly checkpoint most likely through Aurora B activation.

Highlights

The conserved serine-threonine kinase, Cdc7-Dbf[4], phosphorylates Mcm in the pre-Replicative Complex and facilitates recruitment of other replication factors including Cdc[45] for initiation of DNA replication[1,2,3,4,5,6,7,8]
Phosphorylation of Aurora B increased in the presence of Cdc[7] (Fig. 1a, lanes 11 and 12), and this may be due to Cdc7-mediated direct phosphorylation and/ or to increased autophosphorylation activity of Aurora B
Cdc[7] increased in vitro phosphorylation of Histone H3 S28 by the human Aurora B/ INCENP, but did not affect or only slightly increased the autophosphorylation level of Aurora B detected by antiPlk1-pT210 antibody (Fig. 1b,e)

Summary

Introduction

The conserved serine-threonine kinase, Cdc7-Dbf[4], phosphorylates Mcm in the pre-Replicative Complex (pre-RC) and facilitates recruitment of other replication factors including Cdc[45] for initiation of DNA replication[1,2,3,4,5,6,7,8]. Aurora B, a conserved mitotic kinase, is activated during M-phase by association with INCENP22, forming the chromosome passenger complex (CPC) with Borealin and Survivin[23,24,25,26,27,28]. It plays critical roles in chromosome separation and cytokinesis by translocating from chromatin to centromere to mid-body. CPC, phosphorylated by Cdk[1], binds to Shugosin, and localizes at inner centromere[29] This step requires Aurora B kinase, as well as Bub[1] and Haspin kinases. We show that Aurora B activation in early M-phase by Cdc[7] contributes to efficient M-phase progression and to efficient operation of SAC

Methods

Results

Conclusion