Dynamics of endosomal sorting complex required for transport (ESCRT) machinery during cytokinesis and its role in abscission

TLDR

Abscission, the final step of cytokinesis that severs the intercellular bridge, requires ESCRT machinery, yet the specific role of ESCRT‑III in this membrane scission remains unclear. The study aims to clarify the role of ESCRT components, particularly ESCRT‑III, during cytokinetic abscission. Using structured illumination microscopy and time‑lapse imaging, the authors tracked ESCRT dynamics during abscission. TSG101 and CHMP4B are sequentially recruited to the bridge center forming cortical rings, and CHMP4B and VPS4 are acutely recruited to the constriction site immediately before abscission, demonstrating a direct role for these ESCRT components in cytokinetic membrane scission.

Abstract

The final stage of cytokinesis is abscission, the cutting of the narrow membrane bridge connecting two daughter cells. The endosomal sorting complex required for transport (ESCRT) machinery is required for cytokinesis, and ESCRT-III has membrane scission activity in vitro, but the role of ESCRTs in abscission has been undefined. Here, we use structured illumination microscopy and time-lapse imaging to dissect the behavior of ESCRTs during abscission. Our data reveal that the ESCRT-I subunit tumor-susceptibility gene 101 (TSG101) and the ESCRT-III subunit charged multivesicular body protein 4b (CHMP4B) are sequentially recruited to the center of the intercellular bridge, forming a series of cortical rings. Late in cytokinesis, however, CHMP4B is acutely recruited to the narrow constriction site where abscission occurs. The ESCRT disassembly factor vacuolar protein sorting 4 (VPS4) follows CHMP4B to this site, and cell separation occurs immediately. That arrival of ESCRT-III and VPS4 correlates both spatially and temporally with the abscission event suggests a direct role for these proteins in cytokinetic membrane abscission.