Cep55, a Microtubule-bundling Protein, Associates with Centralspindlin to Control the Midbody Integrity and Cell Abscission during Cytokinesis

Abstract

We report here an efficient functional genomic analysis by combining information on the gene expression profiling, cellular localization, and loss-of-function studies. Through this analysis, we identified Cep55 as a regulator required for the completion of cytokinesis. We found that Cep55 localizes to the mitotic spindle during prometaphase and metaphase and to the spindle midzone and the midbody during anaphase and cytokinesis. At the terminal stage of cytokinesis, Cep55 is required for the midbody structure and for the completion of cytokinesis. In Cep55-knockdown cells, the Flemming body is absent, and the structural and regulatory components of the midbody are either absent or mislocalized. Cep55 also facilitates the membrane fusion at the terminal stage of cytokinesis by controlling the localization of endobrevin, a v-SNARE required for cell abscission. Biochemically, Cep55 is a microtubule-associated protein that efficiently bundles microtubules. Cep55 directly binds to MKLP1 in vitro and associates with the MKLP1-MgcRacGAP centralspindlin complex in vivo. Cep55 is under the control of centralspindlin, as knockdown of centralspindlin abolished the localization of Cep55 to the spindle midzone. Our study defines a cellular mechanism that links centralspindlin to Cep55, which, in turn, controls the midbody structure and membrane fusion at the terminal stage of cytokinesis.

Human ESCRT-III and VPS4 proteins are required for centrosome and spindle maintenance

“…This behavior is well documented for CEP55, which migrates from the centrosome to the midbody upon phosphorylation by Cdk1 and Erk2 (18,33,34). Cell cycle-dependent centrosomal and midbody localization patterns have now also been reported for IST1 (22) and VPS4 (this study) and for the CHMP4-binding protein, TTC19, which was recently show to translocate together with its binding partner, FYVE-CENT, from centrosomes to midbodies (35).…”

Cytokinesis microtubule organisers at a glance

“…CYK4 also interacts with a multifunctional contractile ring protein, anillin (D'Avino et al, 2008;Gregory et al, 2008;Piekny and Maddox, 2010). In late telophase, CEP55, an adaptor protein that is essential for midbody recruitment of the endosomal sorting complex required for transport (ESCRT) proteins (Caballe and Martin-Serrano, 2011), localises to the Flemming body by directly interacting with MKLP1 in a manner that is negatively regulated by PLK1-mediated phosphorylation (Bastos and Barr, 2010;Zhao et al, 2006). FIP3, another adaptor protein that interacts with Arf6 and Rab11 GTPases, competes with ECT2 for CYK4 binding and localises to the Flemming body as ECT2 leaves in late telophase (Simon et al, 2008).…”

Cytokinesis and cancer

“…Microtubule-associated proteins PRC1 [13,14] Centralspindlin complex CYK-4 [2,15] MKLP1 [2,15] Chromosome passenger complex INCENP [16,17] Survinin [16,17] Borealin [16,17] Aurora B [16,17] ESRCTs and associated proteins CEP55 [30][31][32] TSG101 [31,32] ALIX [31,32] CHMP1B [33] Spastin [33] CHMP4B [31,32,34] FYVE-CENT [34] TTC19 [34] Kinesins KIF4A [14] MKLP2 [17] MPP1 [22] KIF14 [23] KIF13A [34] Additional proteins NuSAP [18] Orbit [19] ASP [20] TBCD [21] ECT2 [24] FIP3 [25] PLK1 [26,27] Septins [28] Anillin [29] during anaphase and cytokinesis and is important for the last step of abscission. CEP55 binds directly MKLP1 and is controlled by centralspindlin, since knockdown of centralspindlin abolishes CEP55 from the midbody [30].…”

“…CEP55 binds directly MKLP1 and is controlled by centralspindlin, since knockdown of centralspindlin abolishes CEP55 from the midbody [30]. Interestingly, CEP55 also interacts with Tsg101, an endosomal sorting complex required for transport (ESC-RT)-I subunit, and Alix, an ESCRT-associated protein and recruits these to the midbody.…”