DNA replication licensing factor Cdc6 and Plk4 kinase antagonistically regulate centrosome duplication via Sas-6

Xiaowei Xu,Si Li,Boyan Zhang,Wangfei Chi,Shijiao Huang,Fan Huang,Qing Jiang,Jingyan Fu,Gang Wang,Chuanmao Zhang

doi:10.1038/ncomms15164

Abstract

Centrosome number is tightly controlled during the cell cycle to ensure proper spindle assembly and cell division. However, the underlying mechanism that controls centrosome number remains largely unclear. We show herein that the DNA replication licensing factor Cdc6 is recruited to the proximal side of the centrioles via cyclin A to negatively regulate centrosome duplication by binding and inhibiting the cartwheel protein Sas-6 from forming a stable complex with another centriole duplication core protein, STIL. We further demonstrate that Cdc6 colocalizes with Plk4 at the centrosome, and interacts with Plk4 during S phase. Plk4 disrupts the interaction between Sas-6 and Cdc6, and suppresses the inhibitory role of Cdc6 on Sas-6 by phosphorylating Cdc6. Overexpressing wild-type Cdc6 or Plk4-unphosphorylatable Cdc6 mutant 2A reduces centrosome over-duplication caused by Plk4 overexpression or hydroxyurea treatment. Taken together, our data demonstrate that Cdc6 and Plk4 antagonistically control proper centrosome duplication during the cell cycle.

Highlights

Centrosome number is tightly controlled during the cell cycle to ensure proper spindle assembly and cell division
Several DNA replication initiation proteins that interact with cyclin E and cyclin A are directly involved in centrosome duplication
By co-IP in HEK293 cells co-transfected with GFP-Plk[4] and Myc-Cdc[6] and synchronized to the G1/S transition, S or G2 phase, we found that the interaction between Plk[4] and Cdc[6] was limited to S phase (Fig. 4d), suggesting that a functional interplay between Plk[4] and Cdc[6] exists only during S phase

Summary

Introduction

Centrosome number is tightly controlled during the cell cycle to ensure proper spindle assembly and cell division. Our data demonstrate that Cdc[6] and Plk[4] antagonistically control proper centrosome duplication during the cell cycle. Several DNA replication initiation proteins that interact with cyclin E and cyclin A are directly involved in centrosome duplication. An inhibitor of DNA replication initiation, prevents centrosome over-duplication in the S phase-arrested human breast cancer cell line MDA-MB-231 Plk[4] phosphorylates the F-box protein Fbxw[5] and stabilizes the Sas-6 protein level by inhibiting SCF-Fbxw[5] E3 ligase-dependent Sas-6 ubiquitination and degradation, triggering centrosome duplication[31]. None of the DNA replication-related proteins have been identified as Plk[4] kinase substrates

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Results

Conclusion