During mitosis, many structural, regulatory, and checkpoint proteins work towards the goal of accomplishing equal chromosome segregation. Microtubules of the mitotic spindle attach to kinetochores on chromosomes, and this attachment of microtubules to all kinetochores on all chromosomes provides a checkpoint signal that instructs the cell to undergo chromosome segregation. A protein called Spindly was previously known to localize the microtubule motor dynein to kinetochores. A recent paper has found an additional role for Spindly in coordinating microtubule attachment to kinetochores and mitotic checkpoint signaling. Image above shows mitotic spindles (PM, M) in control cells and cells with lower levels of Spindly. In cells with decreased Spindly, mitotic spindles are often abnormal – some are longer (L), some have more than two spindle poles (MP), and some are twisted (T). DNA is in blue, microtubules are in green, and kinetochores are in red.
Reference: Marin Barisic, Bénédicte Sohm, Petra Mikolcevic, Cornelia Wandke, Veronika Rauch, Thomas Ringer, Michael Hess, Günther Bonn, and Stephan Geley. Authors’ Molecular Biology of the Cell paper can be found here.