Dynamin contributes to cytokinesis by stabilizing actin filaments in the contractile ring

Abstract

Dynamin has been proposed to play an important role in cytokinesis, although the nature of its contribution has remained unclear. Dictyostelium discoideum has five dynamin-like proteins: DymA, DymB, DlpA, DlpB and DlpC. Cells mutant for dymA, dlpA or dlpB presented defects in cytokinesis that resulted in multinucleation when the cells were cultured in suspension. However, the cells could divide normally when attached to the substratum; this latter process depends on traction-mediated cytokinesis B. A dynamin GTPase inhibitor also blocked cytokinesis in suspension, suggesting an important role for dynamin in cytokinesis A, which requires a contractile ring powered by myosin II. Myosin II did not properly localize to the cleavage furrow in dynamin mutant cells, and the furrow shape was distorted. DymA and DlpA were associated with actin filaments at the furrow. Fluorescence recovery after photobleaching and a DNase I binding assay showed that actin filaments in the contractile ring were significantly fragmented in mutant cells. Dynamin is therefore involved in the stabilization of actin filaments in the furrow, which, in turn, maintain proper myosin II organization. We conclude that the lack of these dynamins disrupts proper actomyosin organization and thereby disables cytokinesis A.

Membrane remodeling during embryonic abscission in Caenorhabditis elegans

“…Based on our finding that myosin levels remained normal on the ingressing furrow in DYN-1-depleted embryos (Fig. S3, C and D), this phenotype was unlikely to be a result of a defect in actomyosin ring stability, as was observed previously in Dictyostelium discoideum after dynamin inhibition (Masud Rana et al, 2013).…”

Regulation of the Total Cell Surface Area in Dividing Dictyostelium Cells

“…In Dictyostelium cells, we have not observed clathrin at the spindle. In Dictyostelium cells, clathrin evenly localizes in the cell cortex, whereas dynamin is known to localize at the cleavage furrow (Masud Rana et al, 2013;Fujimoto et al, 2019).…”

A novel mode of cytokinesis without cell-substratum adhesion

“…The cells were placed in Lipidure-coated or non-coated glass bottom dishes and observed under an inverted differential interference-contrast microscope (DIC) or a phase-contrast microscope (Olympus, IX71). To visualize the nucleus, DAPI-stained cells were observed under a fluorescence microscope (Nikon, TMD300) by UV illumination 47 . The cells expressing GFP-histone or GFP-myosin II were observed with a DeltaVision microscope system based on an Olympus IX71 inverted microscope (GE Healthcare Life Sciences, Japan) with a 60× objective lens (PLAPON 60× OTIRFM, NA 1.45).…”