Role of Kif15 and its novel mitotic partner KBP in K-fiber dynamics and chromosome alignment.

Nathalie Brouwers,Isabelle Vernos,Nuria Mallol Martinez,Daniela Cimini

doi:10.1371/journal.pone.0174819

Abstract

Faithful segregation of the genetic material during the cell cycle is key for the continuation of life. Central to this process is the assembly of a bipolar spindle that aligns the chromosomes and segregates them to the two daughter cells. Spindle bipolarity is strongly dependent on the activity of the homotetrameric kinesin Eg5. However, another kinesin, Kif15, also provides forces needed to separate the spindle poles during prometaphase and to maintain spindle bipolarity at metaphase. Here we identify KBP as a specific interaction partner of Kif15 in mitosis. We show that KBP promotes the localization of Kif15 to the spindle equator close to the chromosomes. Both Kif15 and KBP are required for the alignment of all the chromosomes to the metaphase plate and the assembly of stable kinetochore fibers of the correct length. Taken together our data uncover a novel role for Kif15 in complex with KBP during mitosis.

Highlights

Faithful segregation of the genetic material during cell division is key for the continuation of life
To obtain better insights into the role of Kif15 during mitosis we used a SILAC approach combined with quantitative mass spectrometry to identify novel interaction partners
Kif15 has been shown to play a role in bipolar spindle formation in concert with the dominant bipolar kinesin Eg5, providing pushing forces that separate the centrosomes/spindle poles after nuclear envelope breakdown (NEBD) [6,7,10]

Summary

Introduction

Faithful segregation of the genetic material during cell division is key for the continuation of life. Central to this process is the formation of the bipolar spindle that moves chromosomes to first align them on the metaphase plate and provide the forces to segregate them to the daughter cells. Molecular motors play essential roles both in bipolar spindle assembly and chromosome alignment. The homotetrameric kinesin Eg5 plays a major role in spindle bipolarity by generating forces driving centrosome separation and by cross-linking and sliding antiparallel microtubules (MTs) apart [1]. Eg5 is not essential for the maintenance of spindle bipolarity in metaphase [6,7]

Methods

Results

Conclusion