The exocyst complex and Rab5 are required for abscission by localizing ESCRT III subunits to the cytokinetic bridge

Abstract

Cytokinesis is the final step of cell division following chromosome segregation that generates two daughter cells. The conserved exocyst complex is required for scission of the intercellular cytokinetic bridge, although the molecular mechanisms it employs in this process are unclear. We identify and validate the early endocytic GTPase Rab5 as interacting with the exocyst complex in mammalian cells. Rab5 localizes in the cytokinetic bridge and on the midbody ring in a manner similar to the exocyst complex. Depletion of Rab5 led to delayed abscission. Caenorhabditis elegans orthologs of both exocyst complex subunits and Rab5 localize along the cleavage furrow and are required for cytokinesis in early embryos. Cytokinetic cells depleted of either Rab5 or the exocyst subunits Exoc3 and Exoc4 showed impaired deposition of the endosomal sorting complexes required for transport (ESCRT) III subunits CHMP2B and/or CHMP4B near the midbody ring. The study reveals an evolutionarily conserved role for the early endocytic marker Rab5 in cytokinetic abscission. In addition, it uncovers a key requirement of the exocyst and Rab5 for the delivery of components of the membrane-severing ESCRT III machinery to complete cytokinesis.

Regulation of the Total Cell Surface Area in Dividing Dictyostelium Cells

“…Conversely, from the experiments using the secA null mutant, the increase in the cell surface is critical for cytokinesis. Previous studies have reported that the delivery of intracellular membrane vesicles to the cell membrane is required for constriction of the cleavage furrow in zebrafish, C. elegans embryos, Drosophila spermatocytes, and yeast (Li et al, 2006;Robinett et al, 2009;Giansanti et al, 2015;Wang et al, 2016;Kumar et al, 2019). As a candidate of the membrane vesicles source, Golgi-derived vesicles, lysosome, or endosome has been reported (Arden et al, 2007;Boucrot and Kirchhausen, 2007;Goss and Toomre, 2008;Montagnac et al, 2009).…”

Meeting report – the Microtubules, Motors, Transport and Trafficking (M2T2) 2019 meeting

“…Both Rab5 and exocyst complex subunits localize at the midbody ring in the cytokinetic bridge and are required for delivering the membrane abscising ESCRT-III machinery to this site to enable abscission. This work suggests that early endosomes could play roles in cytokinetic abscission in addition to the documented roles of secretory vesicles and recycling endosomes (Kumar et al, 2019b).…”

Rabs in Signaling and Embryonic Development

“…Oocytes depleted of Rab5 display defective yolk protein internalization [47]. Interestingly, it was recently shown in C. elegans embryos that Rab5 was enriched at cleavage furrows [48]. Depletion of Rab5 in four-and six-cell embryos caused multinucleated blastomeres, revealing a role for Rab5 in cytokinesis in C. elegans [48].…”

“…Interestingly, it was recently shown in C. elegans embryos that Rab5 was enriched at cleavage furrows [48]. Depletion of Rab5 in four-and six-cell embryos caused multinucleated blastomeres, revealing a role for Rab5 in cytokinesis in C. elegans [48]. Notably, Rab5 was shown to be important for cell boundary formation during fly cellularization [49].…”