PRC1 Cooperates with CLASP1 to Organize Central Spindle Plasticity in Mitosis

Abstract

During cell division, chromosome segregation is governed by the interaction of spindle microtubules with the kinetochore. A dramatic remodeling of interpolar microtubules into an organized central spindle between the separating chromatids is required for the initiation and execution of cytokinesis. Central spindle organization requires mitotic kinesins, microtubulebundling protein PRC1, and Aurora B kinase complex. However, the precise role of PRC1 in central spindle organization has remained elusive. Here we show that PRC1 recruits CLASP1 to the central spindle at early anaphase onset. CLASP1 belongs to a conserved microtubule-binding protein family that mediates the stabilization of overlapping microtubules of the central spindle. PRC1 physically interacts with CLASP1 and specifies its localization to the central spindle. Repression of CLASP1 leads to sister-chromatid bridges and depolymerization of spindle midzone microtubules. Disruption of PRC1-CLASP1 interaction by a membrane-permeable peptide abrogates accurate chromosome segregation, resulting in sister chromatid bridges. These findings reveal a key role for the PRC1-CLASP1 interaction in achieving a stable anti-parallel microtubule organization essential for faithful chromosome segregation. We propose that PRC1 forms a link between stabilization of CLASP1 association with central spindle microtubules and anti-parallel microtubule elongation.

Mitotic Regulator SKAP Forms a Link between Kinetochore Core Complex KMN and Dynamic Spindle Microtubules

“…Briefly, HeLa cells were grown on a glass bottom culture dish (MatTek) at 37°C with 10% CO 2 after various transfections with siRNA or scrambled (control) oligonucleotides; HeLa cells were then transiently transfected with EGFP-CENP-B followed by synchronization. Then images were collected using a DeltaVision DVI microscopy system built on an Olympus IX-70 inverted microscope base as described previously (7,25). For imaging, time points were acquired every 5 s for 5 min with a ϫ100, 1.35 numerical aperture objective lens on the imaging system (DeltaVision Core, Applied Precision) fitted with a 37°C environmental chamber.…”

PLK1 Phosphorylates Mitotic Centromere-associated Kinesin and Promotes Its Depolymerase Activity

“…DNA was stained with DAPI (Sigma). Images were collected using a DeltaVision wide field deconvolution microscope system as described previously (52).…”

Cytokinesis microtubule organisers at a glance

“…In addition to its function in the regulation of interphase microtubule dynamics, CLASP also controls the architecture of the bipolar mitotic spindle (Walczak, 2005) and the central spindle (Inoue et al, 2000;Inoue et al, 2004). The central spindle localisation of CLASP depends upon its interaction with PRC1 (Liu et al, 2009), similarly to its Schizosaccharomyces pombe orthologue cls1p (also called peg1p) (Bratman and Chang, 2007). Depletion of one of the three CLASPs in C. elegans causes a synthetic cytokinesis failure in PRC1 mutant embryos, which show only mild cytokinesis failure in the first cell division (Bringmann et al, 2007).…”