Two XMAP215/TOG Microtubule Polymerases, Alp14 and Dis1, Play Non-Exchangeable, Distinct Roles in Microtubule Organisation in Fission Yeast

Abstract

Proper bipolar spindle assembly underlies accurate chromosome segregation. A cohort of microtubule-associated proteins orchestrates spindle microtubule formation in a spatiotemporally coordinated manner. Among them, the conserved XMAP215/TOG family of microtubule polymerase plays a central role in spindle assembly. In fission yeast, two XMAP215/TOG members, Alp14 and Dis1, share essential roles in cell viability; however how these two proteins functionally collaborate remains undetermined. Here we show the functional interplay and specification of Alp14 and Dis1. Creation of new mutant alleles of alp14, which display temperature sensitivity in the absence of Dis1, enabled us to conduct detailed analyses of a double mutant. We have found that simultaneous inactivation of Alp14 and Dis1 results in early mitotic arrest with very short, fragile spindles. Intriguingly, these cells often undergo spindle collapse, leading to a lethal “cut” phenotype. By implementing an artificial targeting system, we have shown that Alp14 and Dis1 are not functionally exchangeable and as such are not merely redundant paralogues. Interestingly, while Alp14 promotes microtubule nucleation, Dis1 does not. Our results uncover that the intrinsic specification, not the spatial regulation, between Alp14 and Dis1 underlies the collaborative actions of these two XMAP215/TOG members in mitotic progression, spindle integrity and genome stability.

How Essential Kinesin-5 Becomes Non-Essential in Fission Yeast: Force Balance and Microtubule Dynamics Matter

“…Alp14 and Dis1 belong to a conserved MAP family of XMAP215/Stu2/TOG that catalyses microtubule polymerisation [51][52][53][54][55][56]85,86]. As aforementioned, Alp7 forms a stable complex with Alp14 and targets the Alp14 microtubule polymerase to the SPB upon mitotic onset [49,57].…”

Identification and evaluation of the novel genes for transcript normalization during female gametophyte development in sugarcane

“…The MOR1 gene belongs to the ARM repeat superfamily containing CLIP-associated (CLASP) N terminal and plays an essential role in maintaining microtubule stability (Grallert et al, 2006). The homologous gene in yeast, XMAP215 encodes microtubule polymerase, is associated with microtubule formation underlying chromosome segregation spatiotemporally (Yukawa et al, 2019). In animals including Drosophila, The XMAP215 gene was also identified as the regulator of microtubule arrangement, equipping protein with unique spatial configuration and further playing numerous vital functions (Brittle & Ohkura, 2005).…”

Microtubule length correlates with spindle length inC. elegansmeiosis

“…Specifically for meiotic divisions previous research has shown that MT growth dynamics are crucial for correct meiotic spindle formation and function, as treatment of mouse oocytes with taxol impairs MT and chromosome organization as well as meiotic progression and leads to aneuploidy (1). Further, mutations or disruptions in proteins involved in MT de-/polymerization, such as XMAP215/Dis1 family proteins (18)(19)(20)(21)(22) and their regulators or MCAK (23)(24)(25)(26) result in abnormal spindle structures, misaligned chromosomes, and failed chromosome segregation in yeast, Drosophila, mice and various other organisms. In addition, oocytes from older mice exhibit altered spindle MT dynamics which may contribute to age-related increase in chromosome segregation errors that are observed in these animals (2).…”