Molecular mechanisms of contractile-ring constriction and membrane trafficking in cytokinesis

Abstract

In this review, we discuss the molecular mechanisms of cytokinesis from plants to humans, with a focus on contribution of membrane trafficking to cytokinesis. Selection of the division site in fungi, metazoans, and plants is reviewed, as well as the assembly and constriction of a contractile ring in fungi and metazoans. We also provide an introduction to exocytosis and endocytosis, and discuss how they contribute to successful cytokinesis in eukaryotic cells. The conservation in the coordination of membrane deposition and cytoskeleton during cytokinesis in fungi, metazoans, and plants is highlighted.

Keywords: Contractile ring; Cytokinesis; Endocytosis; Exocytosis; Membrane deposition.

Fig. 1

Cytokinesis in different model organisms. a Cytokinesis in fission yeast. Cytokinesis nodes, containing myosin-II, mark the division site. Actin filaments promote node condensation to form the contractile ring by interaction with myosin-II. The ring begins to constrict after the cell exits from mitosis. Septum formation takes place behind the ring. The middle layer of the fully formed septum is then digested to separate the two daughter cells. b Cytokinesis in metazoans. Active RhoA promotes furrow ingression after being activated by centralspindlin. The actomyosin ring then forms at the division site. After furrow ingression, the secondary ingression at the midbody is mediated by the ESCRT-III complex. Abscission of the midbody leads to cell separation. c Cytokinesis in plants. Formation of the preprophase band marks the division site, made of actin and microtubules. The phragmoplast mediates the formation and expansion of the cell plate. Maturation and expansion of the cell plate completes the cell division by fusing with the plasma membrane

Fig. 2

Illustration of exocytosis and endocytosis. a Exocytosis. (1) Vesicle delivery to the plasma membrane where it is (2) tethered by a tethering complex such as the exocyst, mediated by Rab GTPase. (3) SNARE proteins present on the vesicle and membrane are brought into proximity and (4) form a four helix bundle, templated by an SM protein. (5) SNARE complex formation drives fusion of vesicle to the plasma membrane, and NSF and SNAP proteins disassemble the cis SNARE complex. b Endocytosis. (1) Cargos and adaptor proteins on the membrane surface begin to cluster, (2) which recruits coat proteins such as clathrin. (3) The coat proteins promote membrane bending and invagination to form the endocytic pit. (4) Branched actin filaments are assembled and dynamin is recruited to the neck, with the help of F-BAR domain containing proteins, the vesicle is pinched off from the plasma membrane and is uncoated (5)

Fig. 3

Membrane deposition and extracellular matrix formation at the division site during cytokinesis. a Animal cells. The exocyst localizes to the leading edge of the cleavage furrow just behind the contractile ring to tether vesicles during furrow ingression. At the midbody, actin and microtubules serve as tracks to deliver secretory vesicles and transport endocytic vesicles to promote abscission. b Fission yeast. Vesicles are initially tethered at the contractile ring by the exocyst tethering complex before ring constriction. The exocyst remains at the outer rim as the ring constricts and the TRAPP-II complex tethers vesicles along the division plane during septum formation. c Plant cells. Secretory vesicles are delivered to the phragmoplast by microtubule tracks and fuse together to expand outward to form the cell plate. The exocyst and TRAPP-II complexes cooperate in vesicle tethering and fusion