May 27, 2010

During mitosis, chromosome segregation depends on proper assembly and function of kinetochores, which are protein complexes necessary for chromosome attachment to the microtubules of the spindle. Kinetochores are made of dozens of proteins, and the accurate assembly, localization, and dynamics of these proteins are important. A recent paper has shown that the chaperone complex Hsp90-Sgt1 interacts with Mis12, a known key player in kinetochore assembly. Image above shows mitotic spindles lacking proper Sgt1 function, with only very stable kinetochore-bound microtubules preserved. Some spindles with this treatment look normal (top), while many others have kinetochores without microtubule attachment (arrowheads). Kinetochores are in red, microtubules in green, and DNA in blue.

Reference: Alexander E. Davies and Kenneth B. Kaplan, 2010. Originally published in Journal of Cell Biology, doi: 10.1083/jcb.200910036. Paper can be found here.