Mitotic-Specific Mechanosensing and Contractile-Protein Redistribution Control Cell Shape

Current Biology 16:1962
Douglas Robinson @ JHU School of Medicine

This is a short paper talking about asymmetric cell shape induced contractile-protein redistribution during cytokinesis. Authors employed extrinsic force to generate asymmetric cell shape and found myosin-II and cortexillin, an actin-cross linker, can response to this change, concentrating at the forced region and processing contraction. This phenomenon is spindle independent and cytokinesis specific.

“In early cytokinesis, mechanical load overrides spindle cues and slows cytokinesis progression while contractile proteins accumulate and correct shape asymmetries. In late cytokinesis, mechanical perturbation also directs contractile proteins but without apparently disrupting cytokinesis”

It is a shame that authors didn’t address possible reasons for these findings. I think a bigger question should be answered first before this issue. That is what proteins work in the same way as myosin-II and cortexillin. And which proteins in them are truly responsible for the different effect between early and late cytokinesis. Maybe some of those proteins are essential for early cytokinesis events which are titrated by the extra-mechanical force on cortical somewhere else. I am disappointed that authors didn’t show any experimental data related to myosin-II upstream proteins, such as Rho Kinase, Citron Kinase, Rho etc… And more, it is quite common cell blebbing at polar region. Exists there any similarity between?

After all, this paper showed that there exists a cortical mechanism which is cytokinesis specific and independent to mitotic spindles. This mechanism might play a role in cytokinesis by regulating cortex activities and cell shape.