Cytokinesis in animal cells

Abstract

Cell division ends with the physical separation of the two daughter cells, a process known as cytokinesis. This final event ensures that nuclear and cytoplasmic contents are accurately partitioned between the two nascent cells. Cytokinesis is one of the most dramatic changes in cell shape and requires an extensive reorganization of the cell's cytoskeleton. Here, we describe the cytoskeletal structures, factors, and signaling pathways that orchestrate this robust and yet highly dynamic process in animal cells. Finally, we discuss possible future directions in this growing area of cell division research and its implications in human diseases, including cancer.

Figure 1.

Schematic diagram illustrating the different stages of cytokinesis in animal cells. Microtubules are depicted in blue, the actomyosin contractile ring and the midbody ring in red, and the endosomal sorting complex required for transport (ESCRT)-III spiral filaments in green.

Figure 2.

Schematic diagram of the RhoA-activated signaling pathways controlling actomyosin dynamics during cytokinesis. See text for details. Dia, diaphanous; GAP, GTPase-activating protein; GDP, guanosine diphosphate; GEF, guanine nucleotide exchange factor; GTP, guanosine-triphosphate; MRLC, myosin regulatory light chain; ROK, Rho kinase.

Figure 3.

Model of RhoA regulation during cytokinesis. The centralspindlin complex binds to ECT2 and travels to the plus ends of both equatorial and central spindle microtubules. On reaching the cortex, ECT2 activates RhoA, which, in turn, promotes the assembly of the actomyosin ring (not depicted). The RacGAP component of centralspindlin inhibits Rac GTPase to reduce cortical stiffness and inhibit cell adhesion, thus, allowing robust and rapid furrow ingression. GAP, GTPase-activating protein; GDP, guanosine diphosphate; GTP, guanosine triphosphate.

Figure 4.

Midbody formation and structure in late cytokinesis. (A) Electron microscopy image of a HeLa cell in cytokinesis is shown at the top and at the bottom is a magnification of the midbody. MR, midbody ring. Scale bar, 1 µm. (B) Midbody stages in late cytokinesis. HeLa cells were fixed and stained to detect tubulin and DNA. Insets show a 3× magnification of the midbody. The arrowheads indicate the midbody rings, and the arrows specify the abscission site. Scale bar, 10 µm.