Chromosomal attachments set length and microtubule number in the Saccharomyces cerevisiae mitotic spindle.
Bottom Line: The length of the mitotic spindle varies among different cell types.A simple model for spindle length regulation requires balancing two forces: pulling, due to micro-tubules that attach to the chromosomes at their kinetochores, and pushing, due to interactions between microtubules that emanate from opposite spindle poles.In the budding yeast Saccharomyces cerevisiae, we show that spindle length scales with kinetochore number, increasing when kinetochores are inactivated and shortening on addition of synthetic or natural kinetochores, showing that kinetochore-microtubule interactions generate an inward force to balance forces that elongate the spindle.
Affiliation: Molecular and Cellular Biology Department, Harvard University, Cambridge, MA 02138 FAS Center for Systems Biology, Harvard University, Cambridge, MA 02138.Show MeSH
Mentions: Synthetic kinetochores can replace natural kinetochores by biorienting and segregating chromosomes (Kiermaier etÂ al., 2009; Lacefield etÂ al., 2009). Recruiting a fusion of the Lac repressor and Ask1, a component of the microtubule-binding Dam1 complex, to a LacO array creates a synthetic kinetochore that bypasses the need for CBF3 and thus does not require Ndc10 or Ctf13 (Figure 4A; Lacefield etÂ al., 2009). We introduced the synthetic kinetochore (sKT) to ndc10-1 cells by integrating LacO arrays on a one, two, or three chromosomes, thus reattaching them to the mitotic spindle (Figure 4B).
Affiliation: Molecular and Cellular Biology Department, Harvard University, Cambridge, MA 02138 FAS Center for Systems Biology, Harvard University, Cambridge, MA 02138.