Welburn Lab – The EMBO Journal Image PRC1 associates with microtubule motors to stabilize the anaphase central spindle, however how they interact remains elusive. This study reveals the molecular basis for the cell cycle regulation of mitotic motor-PRC1 complexes to organize antiparallel microtubule bundle, and to ensure central spindle integrity, midbody assembly and cytokinesis. Authors Gluszek-Kustusz, A., Craske, B., Legal, T., McHugh, T., and Welburn, J. Summary of Paper by Natalia Kochanova, Earnshaw Lab To complete mitosis, chromosomes attach to the microtubules through the kinetochores and segregate. Apart from these microtubules, there are other microtubules, not attached to the chromosomes, which contribute to antiparallel microtubule structures in the central spindle. From anaphase on, these arrays form the midzone, separating two cohorts of segregating chromosomes. The recent Welburn lab study focused on the protein regulator of cytokinesis 1 (PRC1), which crosslinks the microtubules in the midzone, and kinesin CENP-E, which is recruited by PRC1 to the central spindle in anaphase. The team found that the C terminus of CENP-E is essential for its recruitment by PRC1. By sequence alignment they discovered a hydrophobic phenylalanine FF motif, which they named named ФФ motif and confirmed it to be essential for the recruitment of motors to PRC1 in vivo. A considerable part of work comprised in vitro studies, which all complement in vivo experiments. CENP-E 2605-2701 ФФ motif mutant failed to interact with PRC1 both in vivo an in vitro. The interaction also seemed to be phosphorylation-dependent, as the phosphomimetic CENP-E mutant failed to interact and localize to the midzone in vivo. Alphafold structure prediction of PRC1 - CENP-E interaction allowed to find 3 residues of PRC1 responsible for the interaction with CENP-E. This mutant, named MEE mutant, was not able to rescue endogenous PRC1 depletion, leading to several fold increase in binucleated cells. Interestingly, another molecular motor, kinesin Kif4A, needed two ФФ motifs for the interaction with PRC1 in vitro and recruitment to the midzone. As CENP-E was reported to slide microtubules, the team tested this ability of CENP-E in the presence of PRC1. Indeed, with all the components in the system, free microtubules were crosslinked and moved along the other microtubules attached to the coverslip. This work gives the mechanistic basis for PRC1 and CENP-E interaction and correct cytokinesis. It could potentially help to selectively target the cytokinesis of cancer cells as a part of cancer therapeutics. Related links Jornal link Welburn Group DOI This article was published on 2024-06-17
