Conservation of the Centromere/Kinetochore Protein ZW10

Abstract

Mutations in the essential Drosophila melanogaster gene zw10 disrupt chromosome segregation, producing chromosomes that lag at the metaphase plate during anaphase of mitosis and both meiotic divisions. Recent evidence suggests that the product of this gene, DmZW10, acts at the kinetochore as part of a tension-sensing checkpoint at anaphase onset. DmZW10 displays an intriguing cell cycle–dependent intracellular distribution, apparently moving from the centromere/kinetochore at prometaphase to kinetochore microtubules at metaphase, and back to the centromere/kinetochore at anaphase (Williams, B.C., M. Gatti, and M.L. Goldberg. 1996. J. Cell Biol. 134:1127-1140).We have identified ZW10-related proteins from widely diverse species with divergent centromere structures, including several Drosophilids, Caenorhabditis elegans, Arabidopsis thaliana, Mus musculus, and humans. Antibodies against the human ZW10 protein display a cell cycle–dependent staining pattern in HeLa cells strikingly similar to that previously observed for DmZW10 in dividing Drosophila cells. Injections of C. elegans ZW10 antisense RNA phenocopies important aspects of the mutant phenotype in Drosophila: these include a strong decrease in brood size, suggesting defects in meiosis or germline mitosis, a high percentage of lethality among the embryos that are produced, and the appearance of chromatin bridges at anaphase. These results indicate that at least some aspects of the functional role of the ZW10 protein in ensuring proper chromosome segregation are conserved across large evolutionary distances.

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

“…These results indicate that depletion of Hec1 or Zwint-1 leads to misaligned chromosomes at metaphase, lagging chromosomes at anaphase, and eventual cell death. The effects of Hec1-and Zwint-1-depletion were consistent with those observed in Drosophila zw10 mutants that the lagging chromosomes and premature chromosome segregation arise from the attenuated poleward chromosome movement and spindle checkpoint defects (Williams et al, 1992;Williams and Goldberg, 1994;Starr et al, 1997;Basto et al, 2000).…”

“…During mitosis, Zwint-1 was colocalized with Hec1 at kinetochores from prophase to anaphase in more than 100 mitotic cells examined ( Figure 3b and c), while ZW10 was observed at kinetochores from prometaphase to metaphase only. Intriguingly, ZW10 decorated the spindle poles as well as their proximal microtubules at metaphase, suggesting distinct yet potentially interrelated roles for each individual protein at various stages of mitosis ( Figure 3c) (Starr et al, 1997). Taken together, Hec1 and Zwint-1 appear to arrive at kinetochores prior to ZW10, suggesting that Hec1 and Zwint-1 may play a role in recruiting ZW10 to kinetochores.…”

A new look at kinetochore structure in vertebrate somatic cells using high-pressure freezing and freeze substitution

“…The attachment and proper positioning of chromosomes on the spindle likely involves cytoplasmic dynein (Echeverri et al 1996) andCENP-E (1997;Schaar et al 1997;Wood et al 1997), both of which are located in the outer plate and corona. The possible functions of other kinetochore components, including ZW10 (e.g., Starr et al 1997), CENP-F (also known as mitosin; Liao et al 1995) and MCAK (Wordeman and Mitchison 1995), remain to be determined. The composition of facultative proteins on the kinetochore changes during the course of mitosis.…”

“…Thus antibody staining of phosphorylated 3F3/2 epitopes, Mad and Bub proteins is lost or diminished after the kinetochore acquires Mts. Several other components, including ZW10, cytoplasmic dynein, and CENP-E, fully or partially redistribute into the K-Fiber during late metaphase and early anaphase (Echeverri et al 1996;Cooke et al 1997;Starr et al 1997;Yao et al 1997).…”

CENP-E Is Essential for Reliable Bioriented Spindle Attachment, but Chromosome Alignment Can Be Achieved via Redundant Mechanisms in Mammalian Cells

“…One possibility, recently suggested by Chan et al (2000), is that dynein-mediated kinetochore-Mt interactions are monitored by zeste white 10 (ZW10) and ROD (Rough Deal). ZW10 and ROD are required for dynein localization to the kinetochore (Starr et al, 1997) and checkpoint function in Drosophila and human cells (Basto et al, 2000;Chan et al, 2000;Savoian et al, 2000).…”