Taxol-Stabilized Microtubules Can Position the Cytokinetic Furrow in Mammalian Cells

MCB (2005/09)
Ed Salmon @ University of North Carolina

This is an important paper in cytokinesis field because it suggested quality (dynamics), but not quantity, is important for cleavage furrow positioning.

In the classic JC Canman's monopolar cell division paper, it appeared there are some stabilized microtubules passing throught kinetochore to the furrow region. This paper further supports the conclusion above by employing taxol to artificially stabilized microtubules. When treat cells with taxol before microinjecting Mad2 antibody to inactivate checkpoint. The cell cortex still formed furrows although it's temporally later than usual. Besides, those furrows usually didn't progress to complete. When taxol was employed in anaphase, it delayed furrow initiation but didn't perturb furrow positioning. Authors concluded that taxol-stabilized microtubules can act to position the furrow and that loss of microtubule dynamics delay the timing of furrow onset and prevents completion.

This system is a good model for finding the stimulatory signal for furrow initiation. Authors thought stable microtubules at the cortex locally activates Rho, or it promote the delivery of a stimnulatory factor transported along the MTs.

However, INCENP was not found in those ingressing furrows. It is not surprised becasue CCP complex translocation is MT-dynamics-dependent. In cultured cells, other paper reported that Survivin depletion causes mislocalization of MKLP1 from an unstablized midzone. Withuot MKLP1, there should be no MgcRacGAP, and then on Ect2, and then Rho. It is surprised that without all those proteins those taxol-stabilized MTs induced furrows could still ingress. Further work should be done to clearify if there is any mistake in those papers.