Dual modes of contractility tailor cytokinesis to the requirements of diverse tissues.

The actomyosin network generates contractile forces underlying cell shape changes. While actomyosin equatorial contractility is essential for cytokinesis, less is known about the importance of contractility at the poles. This question is pertinent in multicellular organisms where cytokinesis must adapt to the constraints imposed by diverse cell types. Here, we manipulated contractility at the equator and poles during cytokinesis genetically in Drosophila. We examined the consequences of these alterations on cytokinesis in two different cell types: non-polarized and non-adherent large spermatocytes and polarized epithelial cells of the thorax that tightly adhere to their neighbors via cell-cell junctions. We found that high polar and mild equatorial contractility was optimal for spermatocyte cytokinesis. Conversely, polar contractility was dispensable for epithelial cell cytokinesis, whereas a threshold of equatorial contractility was required to remodel cell-cell junctions. Our comparative study illustrates how cytokinesis adapts to tissue specificity via the modulation of polar and equatorial contractility.