GCP6 is a substrate of Plk4 and required for centriole duplication

Abstract

SummaryCentriole duplication occurs once per cell cycle and requires Plk4, a member of the Polo-like kinase family. A key component of the centrosome is the c-tubulin ring complex (c-TuRC) that nucleates microtubules. GCP6 is a member of the c-TuRC, but its role in human cells and the regulation of its functions remain unclear. Here we report that depletion of human GCP6 prevents assembly of the c-TuRC and induces a high percentage of monopolar spindles. These spindles are characterized by a loss of centrosomal c-tubulin and reduced centriole numbers. We found that GCP6 is localized in the pericentriolar material but also at distal portions of centrioles. In addition, GCP6 is required for centriole duplication and Plk4-induced centriole overduplication. GCP6 interacts with and is phosphorylated by Plk4. Moreover, we find that Plk4-dependent phosphorylation of GCP6 regulates centriole duplication. These data suggest that GCP6 is a target of Plk4 in centriole biogenesis.

The Centrosome and Its Duplication Cycle

“…Consistently, overexpression of Plk4 can promote the recruitment of Ana2/STIL and Sas-6 to supernumerary centrioles (Kleylein-Sohn et al 2007;Stevens et al 2010). A number of Plk4/ ZYG-1 substrates have been identified-SAS-6 (Kitagawa et al 2009), Cep152 (Hatch et al 2010), and a component of g-TuRC GCP6 (Bahtz et al 2012), but their significance is not clear. More recently, it has been shown in Drosophila that Plk4 phosphorylates Ana2 in its conserved STAN motif to enable it to bind to Sas-6.…”

The where, when and how of microtubule nucleation – one ring to rule them all

“…In addition, centriole duplication requires phosphorylation of GCP6 by Plk4, a known regulator of centriole biogenesis (Bahtz et al, 2012). The mechanism, by which these phosphorylation events are linked to centriole biogenesis, has not been revealed.…”

MZT1 regulates microtubule nucleation by linking γTuRC assembly to adapter-mediated targeting and activation

“…Thus, the activity of γTuRC is tightly controlled by targeting and activation factors that spatially restrict nucleation to microtubule-organizing centers (MTOCs) such as the centrosome. Surprisingly, whereas assembly and targeting of human γTuRC seem to involve all GCPs (Bahtz et al, 2012;Choi et al, 2010;Izumi et al, 2008;Scheidecker et al, 2015), only γ-tubulin, GCP2 and GCP3, which form the smaller subcomplex γTuSC, are essential in flies and fungi, and are sufficient for microtubule nucleation and targeting to MTOCs (Anders et al, 2006;Fujita et al, 2002;Lin et al, 2015;Venkatram et al, 2004;Vérollet et al, 2006;Xiong and Oakley, 2009). These observations suggest that there are important organism-specific differences in the manner by which nucleation template assembly is linked to targeting and activation.…”

“…However, in human cells γTuRC pre-assembly, targeting and activation are linked in the sense that all of these steps seem to involve the γTuRC-specific GCP4, GCP5 and GCP6 (Bahtz et al, 2012;Choi et al, 2010;Izumi et al, 2008;Scheidecker et al, 2015), but the underlying mechanism has not been revealed. In fact, a systematic comparative analysis of the roles of all human GCPs in γTuRC assembly and function has never been conducted.…”