Burning cellular bridges: Two pathways to the big breakup

Abstract

During cytokinetic abscission, the endosomal sorting complex required for transport (ESCRT) proteins are recruited to the midbody and direct the severing of the intercellular bridge. In this issue, Christ et al. (2016. J. Cell Biol. http://dx.doi.org/10.1083/jcb.201507009) demonstrate that two separate but redundant pathways exist to recruit ESCRT-III proteins to the midbody.

Figure 1.

Model for the recruitment of CHMP4B and CHMP4C to the midbody and their roles in regulating the timing of abscission. PLK-1 phosphorylation of CEP55 inhibits its binding to MKLP1. At the end of anaphase, PLK1 is degraded and MKLP1 recruits CEP55 to the midbody. CEP55 recruits TSG101 and ALIX to the midbody, and Christ et al. (2016) demonstrate that there are two pathways that lead to the subsequent recruitment of CHMP4B: one through ESCRT-I–ESCRT-II–CHMP6 and the second directly through ALIX. ALIX also recruits CHMP4C, which, upon phosphorylation by the CPC, is hypothesized to form a ternary complex with ANCHR and VPS4. Formation of this complex prevents VPS4 from facilitating the completion of abscission until all chromatin is cleared from the intercellular bridge.