Polo-like Kinase 1 Licenses CENP-A Deposition at Centromeres

Abstract

Summary: To ensure the stable transmission of the genome during vertebrate cell division, the mitotic spindle must attach to a single locus on each chromosome, termed the centromere. The fundamental requirement for faithful centromere inheritance is the controlled deposition of the centromere-specifying histone, CENP-A. However, the regulatory mechanisms that ensure the precise control of CENP-A deposition have proved elusive. Here, we identify Polo-like kinase 1 (Plk1) as a centromere-localized regulator required to initiate CENP-A deposition in human cells. We demonstrate that faithful CENP-A deposition requires integrated signals from Plk1 and cyclin-dependent kinase (CDK), with Plk1 promoting the localization of the key CENP-A assembly factor, the Mis18 complex, and CDK inhibiting Mis18 complex assembly. By bypassing these regulated steps, we uncoupled CENP-A deposition from cell cycle progression, resulting in mitotic defects. Thus, CENP-A deposition is controlled by a two-step regulatory paradigm comprised of Plk1 and CDK that is crucial for genomic integrity.

The distinct functions of CENP-C and CENP-T/W in centromere propagation and function inXenopusegg extracts

“…This is consistent with a recent study showing that down regulation of CENP-C, but not of CENP-T, reduces Mis18 complex localization to G1 centromeres in human cells. 43 Another interesting finding is the sequential recruitment of CENP-C, CENP-T and CENP-W to a na€ ıve chromatin template whose centromeres contain CENP-A nucleosomes but no CCAN proteins (Fig. 7).…”

Formin-mediated epigenetic maintenance of centromere identity

“…Upon anaphase onset, released from the CDKbased inhibition and promoted by the Polo kinase 1 (Plk1)-based stimulation, the Mis18 complex (consisting Mis18a, Mis18b and Mis18 binding protein 1) localizes to the centromere to license the process of new CENP-A recruitment. 7,39 The Mis18 complex is crucial for the recruitment of Holliday junction recognition protein (HJURP), a chaperon that binds to CENP-A in a prenucleosomal complex, to the centromere to execute its nucleosome assembly functions for new CENP-A. 5,6,40 Notably, the localization of HJURP at G1 centromeres appears to be transient, as HeLa cells yield a 2»3 hr time window in early G1 in which HJURP can be detected on the centromere.…”

“…We now know that mammalian cells address this issue by replenishing the CENP-A level per centromere in early G1 phase of the cell cycle, right after the previous round of genome division and before the next round of DNA replication. 2 Although several important stages and molecular players have been identified to license, load and stabilize newly synthesized CENP-A proteins at centromeres labeled with preexisted and diluted CENP-A, [3][4][5][6][7] a complete understanding is missing regarding how new CENP-A proteins become stably incorporated into centromeric nucleosomes during early G1.…”

Nucleoporins NPP-10, NPP-13 and NPP-20 are required for HCP-4 nuclear import to establish correct centromere assembly

“…However, post-translational modification is a potent mechanism for timing the activity of proteins of the centromere-kinetochore complex. An attractive mechanism for coupling cell cycle regulation with centromere/kinetochore activity is phosphorylation by cell cycle-dependent kinases (Gascoigne and Cheeseman, 2011;McKinley and Cheeseman, 2014). Adding or removing sumoylation also influences the properties of many centromeric and kinetochore proteins without guiding them to degradation (reviewed by Wan et al, 2012).…”