A novel role for clathrin in cytokinesis

Abstract

Using clathrin-minus Dictyostelium cells, we identified a novel requirement for clathrin during cytokinesis. In suspension culture, clathrin-minus cells failed to divide and became large and multinucleate. This cytokinesis deficiency was not attributable to a pleiotropic effect on the actomyosin cytoskeleton, since other cellular events driven by myosin II (e.g., cortical contraction and capping of concanavalin A receptors) remained intact in clathrin-minus cells. Examination of cells expressing myosin II tagged with green f luorescent protein showed that clathrin-minus cells failed to assemble myosin II into a functional contractile ring. This inability to localize myosin II to a particular location was specific for cytokinesis, since clathrin-minus cells moving across a substrate localized myosin II properly to their posterior cortexes. These results demonstrate that clathrin is essential for construction of a functional contractile ring during cell division.Cytokinesis, which follows nuclear division in a coordinated fashion, is the process by which one cell divides into two (1). During late anaphase/early telophase, as condensed chromosomes move toward opposite poles of a cell, a contractile ring assembles in the center of the cell. As the contractile ring pinches the cell in half, two cells are formed. While many of the cellular properties involved in cytokinesis have been studied extensively, central questions remain. Especially lacking is information about how the plasma membrane and associated proteins integrate with the contractile ring to form a cleavage furrow during cytokinesis.The best characterized proteins of the contractile ring are actin and myosin II. Actin filaments form the scaffold for the contractile ring, whereas myosin II is the motor that drives constriction of the ring. Additional proteins, both membranebound and cytosolic, are certainly involved in contractile ring formation and function. Some proteins identified recently include racE, a small GTPase required for cytokinesis in Dictyostelium (2), and septins, identified first in Saccharomyces cerevisiae (3) and then in Drosophila (4). In addition, the actin-binding protein anillin (5, 6) and the formin-like protein diaphanous (7) are required for cytokinesis in Drosophila. In Dictyostelium, the actin-binding protein cortexillin (8) and the cytoskeletal protein coronin (9) both function in cytokinesis.

Myosin II localization during cytokinesis occurs by a mechanism that does not require its motor domain

“…USA 95 (1998) 13655 furrow by accessory proteins that recognize the myosin II tail, and such proteins are worth searching for. Intriguingly, myosin II does not localize to the furrow region in clathrin heavy chain-null mutants of Dictyostelium (25). This observation might imply that myosin II transporters could be membranous elements, perhaps driven along microtubules by kinesin-like motors, as suggested by Vallee et al (26).…”

Mutations inCog7affect Golgi structure, meiotic cytokinesis and sperm development duringDrosophilaspermatogenesis

“…Several studies have indicated that actomyosin ring assembly and remodelling during cytokinesis is strictly dependent on membrane trafficking during furrowing. For example in Dictyostelium, clathrin-minus cells fail to assemble myosin II into a functional contractile ring and mutations in syntaxin1 disrupt actin organisation during furrow formation of Drosophila embryos (Niswonger and O'Halloran, 1997;Burgess et al, 1997). Interestingly, live analysis of fluorescent tagged vesicles and F-actin movement during cytokinesis of postcellurized Drosophila embryos has suggested a model in which actin and membrane are delivered as a unit to the invaginating furrows (Albertson et al, 2008).…”

Two-pore channel 1 interacts with citron kinase, regulating completion of cytokinesis

“…Endolysosomal involvement in cytokinesis has been previously demonstrated; both copine A, a calcium-dependent membrane binding protein involved in endolysosomal membrane trafficking, 53 and clathrin-mediated membrane trafficking and processing of proteins are required for cytokinesis in Dictyostelium. 54 Endosomal sorting complex required for transport (ESCRT) components, originally found to be involved in endosomal sorting and multivesicular endosome biogenesis, have also been identified in cytokinesis control. 55 Abscission is known to be carried out by the combination of several events including vesicle trafficking, microtubule remodeling and membrane deformation.…”