Hec1 sequentially recruits Zwint-1 and ZW10 to kinetochores for faithful chromosome segregation and spindle checkpoint control

Abstract

Faithful chromosome segregation is essential for maintaining the genomic integrity, which requires coordination among chromosomes, kinetochores, centrosomes and spindles during mitosis. Previously, we discovered a novel coiled-coil protein, highly expressed in cancer 1 (Hec1), which is indispensable for this process. However, the precise underlying mechanism remains unclear. Here, we show that Hec1 directly interacts with human ZW10 interacting protein (Zwint-1), a binding partner of Zeste White 10 (ZW10) that is required for chromosome motility and spindle checkpoint control. In mitotic cells, Hec1 transiently forms complexes with Zwint-1 and ZW10 in a temporal and spatial manner. Although the three proteins have variable cell cycle-dependent expression profiles, they can only be co-immunoprecipitated during M phase. Immunofluorescent study showed that Hec1 and Zwint-1 co-localize at kinetochores beginning at prophase and that ZW10 joins them later at prometaphase. Depletion of Hec1 impairs the recruitment of both Zwint-1 and ZW10 to kinetochores, while depletion of Zwint-1 abrogates the kinetochore localization of ZW10 but not Hec1. The results suggest that the localization of Hec1 at kinetochores is required for the sequential recruitment of Zwint-1 and ZW10. Disrupting this recruitment by inhibiting the expression of Hec1 or Zwint-1 causes chromosome missegregation, spindle checkpoint failure, and eventually cell death upon cytokinesis. Taken together, these results, at least in part, provide a molecular basis to explain how Hec1 plays a crucial role for spindle checkpoint control and faithful chromosome segregation.

Drosophila Mis12 Complex Acts as a Single Functional Unit Essential for Anaphase Chromosome Movement and a Robust Spindle Assembly Checkpoint

“…In addition to providing the attachment site for kinetochore microtubules, the Ndc80 complex is also crucial for recruitment of certain of the SAC proteins including the RZZ complex and Mad2 (Martin-Lluesma et al 2002;DeLuca et al 2003;Lin et al 2006). We were unable to detect Ndc80 at kinetochores in both mis12 and nsl1 mutant stage-14 embryos (Figure 4).…”

Overexpression of androgen receptor enhances the binding of the receptor to the chromatin in prostate cancer

“…A recent study by Lin and co-authors (2010) suggested SKP2 as a potential target in cancer treatment and prevention, because inhibition of SKP2 triggered cellular senescence in p53/PTEN-deficient PC-3 cells and tumor regression in mice. ZWINT (ZW10 interactor), on the other hand, encodes a kinetokore protein (Starr et al, 2000) that has been suggested to have a role in the development of some malignancies (Obuse et al, 2004;Kops et al, 2005;Lin et al, 2006). We have previously shown ZWINT to be an androgen-regulated gene (Waltering et al, 2009).…”

Spindly switch controls anaphase: Spindly and RZZ functions in chromosome attachment and mitotic checkpoint control

“…[72][73][74] The kinetochore localization of the RZZ complex requires Zwint-1, an inner kinetochore plate protein that interacts with the KMN network [75][76][77][78] and with ZW10. 79 Knockdown of Zwint-1 by RNAi depletes ZW10 from kinetochores and causes an RZZ loss-of-function phenotype.…”