The cyclin A centrosomal localization sequence recruits MCM5 and Orc1 to regulate centrosome reduplication

Abstract

SummaryCentrosomes are the major microtubule-organizing centers in animal cells and regulate formation of a bipolar mitotic spindle. Aberrant centrosome number causes chromosome mis-segregation, and has been implicated in genomic instability and tumor development. Previous studies have demonstrated a role for the DNA replication factors MCM5 and Orc1 in preventing centrosome reduplication. Cyclin A-Cdk2 localizes on centrosomes by means of a modular centrosomal localization sequence (CLS) that is distinct from that of cyclin E. Here, we show that cyclin A interacts with both MCM5 and Orc1 in a CLS-dependent but Cdk-independent manner. Although the MRAIL hydrophobic patch is contained within the cyclin A CLS, binding of both MCM5 and Orc1 to cyclin A does not require a wild-type hydrophobic patch. The same domain in MCM5 that mediates interaction with cyclin E also binds cyclin A, resulting in centrosomal localization of MCM5. Finally, unlike its function in DNA synthesis, MCM5-mediated inhibition of centrosome reduplication in S-phase-arrested CHO cells does not require binding to other MCM family members. These results suggest that cyclins E and A sequentially prevent centrosome reduplication throughout interphase by recruitment of DNA replication factors such as MCM5 and Orc1.

The Centrosome and Its Duplication Cycle

“…However, some clues are emerging from the direct involvement of proteins required to control the initiation of DNA replication in both processes. Cdk2's partners, cyclin E and cyclin A, both interact with MCM5 and recruit it to the centrosome where they repress centrosome am-plification in S phase -arrested CHO cells (Ferguson and Maller 2008;Ferguson et al 2010). Moreover, cyclin A has been found to promote Orc1 localization to centrosomes where Orc1 prevents cyclin E -dependent reduplication of centrosomes (Hemerly et al 2009).…”

Let's huddle to prevent a muddle: centrosome declustering as an attractive anticancer strategy

“…49 Subsequently, rising Cyclin A levels induce firing of DNA replication origins, degradation of the majority of ORC1, and translocation of the remainder of ORC1 and MCM5 to the cytosol and centrosome. [50][51][52] ORC1 removal from the nucleus prevents untimely DNA replication relicensure. At the centrosome, ORC1 and MCM5 impede centriole licensing by inhibiting Cyclin E-mediated centriole disengagement.…”

Meier-Gorlin syndrome mutations disrupt an Orc1 CDK inhibitory domain and cause centrosome reduplication

“…Surprisingly, several DNA replication proteins localize to centrosomes, including the origin recognition complex (ORC), some subunits of the minichromosome maintenance (MCM) helicase complex, and geminin (Prasanth et al 2004;Tachibana and Nigg 2006;Stuermer et al 2007;Ferguson and Maller 2008;Hemerly et al 2009;Ferguson et al 2010;Knockleby and Lee 2010). In the nucleus, these proteins are required for prereplicative complex (pre-RC) assembly to license during the G1 phase origins of DNA replication for chromosome duplication, a process that ensures that DNA replication only initiates at each origin once per cell division cycle (Stillman 2005).…”