chTOG is a conserved mitotic error correction factor

Abstract

Accurate chromosome segregation requires kinetochores on duplicated chromatids to biorient by attaching to dynamic microtubules from opposite spindle poles, which exerts forces to bring kinetochores under tension. However, kinetochores initially bind to microtubules indiscriminately, resulting in errors that must be corrected. While the Aurora B protein kinase destabilizes low-tension attachments by phosphorylating kinetochores, low-tension attachments are intrinsically less stable than those under higher tension in vitro independent of Aurora activity. Intrinsic tension-sensitive behavior requires the microtubule regulator Stu2 (budding yeast Dis1/XMAP215 ortholog), which we demonstrate here is likely a conserved function for the TOG protein family. The human TOG protein, chTOG, localizes to kinetochores independent of microtubules by interacting with Hec1. We identify a chTOG mutant that regulates microtubule dynamics but accumulates erroneous kinetochore-microtubule attachments that are not destabilized by Aurora B. Thus, TOG proteins confer a unique, intrinsic error correction activity to kinetochores that ensures accurate chromosome segregation.

Counteraction between Astrin-PP1 and Cyclin-B-CDK1 pathways protects chromosome-microtubule attachments independent of biorientation

“…Our analysis of attachment status showed that chTOG1, EB1-EB3 complex and SKA complex are not essential for maintaining end-on attachments in the absence of Aurora-B activity (Supplementary Table 1 and Supplementary Fig. 1d ), consistent with intact kinetochore-microtubule attachment in cells depleted of chTOG1 50 , 51 , EB1 47 , APC 47 or SKA3 44 , 52 in the absence of microtubule-destabilising cold treatment. Uniquely Astrin or SKAP depleted cells showed a reduction in the number of end-on attached kinetochores and loss of bouquet-like chromosome arrangement in monopolar spindles in this screen (Supplementary Fig.…”

Defining endogenous TACC3–chTOG–clathrin–GTSE1 interactions at the mitotic spindle using induced relocalization

“…1 C; ), consistent with previous observations ( Gergely et al, 2000 , 2003 ; Royle et al, 2005 ; Foraker et al, 2012 ; Bendre et al, 2016 ; Herman et al, 2020 ). Overexpression of TACC3 can result in the formation of aggregates ( Gergely et al, 2000 ; Hood et al, 2013 ), which have recently been described as liquid-like phase-separated structures ( So et al, 2019 ).…”

Structural basis of Stu2 recruitment to yeast kinetochores

“…A further component of the response to erroneous attachment is the plus-end microtubule polymerase, Stu2 (the yeast ortholog of XMAP215/ch-TOG in metazoans). Its polymerization activity depends on plus-end binding, through a set of N-terminal TOG domains ( Figure 1A ; Al-Bassam et al, 2006 ; Ayaz et al, 2012 ; Ayaz et al, 2014 ; Fox et al, 2014 ), but its kinetochore association is independent of microtubules ( Hsu and Toda, 2011 ; Kakui et al, 2013 ; Miller et al, 2016 ; Miller et al, 2019 ; Vasileva et al, 2017 ; Herman et al, 2020 ). In single-molecule experiments in vitro, kinetochores under low tension detach more frequently from microtubules than under higher tension ( Akiyoshi et al, 2010 ), but only when Stu2 is present ( Miller et al, 2016 ).…”