Biology

Dr. Soumya Mukherjee
Postdoctoral associate, Dept. of Genetics, Cell Biology, & Development, University of Minnesota

Abstract:

Motor proteins associate with the mitotic spindle to exert outwardly directed forces, which are necessary for maintenance of the mitotic spindle. These pushing forces are transmitted to chromosomes aligned on the spindle, and generate opposing tension in the chromatin that connects oppositely attached sister chromatids. We found that the magnitude of tension acts as a mechanical signal to ensure the fidelity of chromosome segregation during mitosis.  Modulation of outward forces using genetic perturbations led to a gradient in tension magnitude over multiple isogenic budding yeast strains. We found that a decreasing gradient in tension led to an increasing gradient in the rates of kinetochore detachment and anaphase chromosome mis-segregration, and in metaphase time. Simulations and experiments indicated that these tension responses originate from a tension-dependent kinetochore phosphorylation gradient. Therefore, the cell is exquisitely tuned to the magnitude of tension as a signal to detect potential chromosome segregation errors during mitosis.