ISM2019 (Microscopy)

RESOLVING ESCRT-III SPIRALS AT THE INTERCELLULAR BRIDGE OF DIVIDING CELLS USING 3D STORM


Inna Goliand 1 Shai Adar 1 Inbar Segal 1 Dikla Nachmias 1 Tali Dadosh 2 Michael M. Kozlov 3 Natalie Elia 1
1Department of Life Sciences and NIBN, Ben-Gurion University of the Negev, Beer-Sheva, Israel
2Department of Chemical Research Support, Faculty of Chemistry, Weizmann Institute of Science, Rehovot, Israel
3Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel

The ESCRT machinery mediates membrane fission in a variety of processes in cells. According to current models, ESCRT-III proteins drive membrane fission by assembling into helical filaments on membranes. Here, we used 3D STORM imaging of endogenous ESCRT-III component IST1 to reveal the evolution of the structural organization of ESCRT-III in mammalian cytokinetic abscission. Using this approach, ESCRT-III ring and spiral assemblies were resolved and characterized at different stages of abscission. Visualization of IST1 structures in cells lacking the microtubule-severing enzyme spastin and in cells depleted of specific ESCRT-III components or the ATPase VPS4 demonstrated the contribution of these components to the organization and function of ESCRTs in cells. This work provides direct evidence that ESCRT-III proteins form helical filaments to mediate their function in cells and raises new mechanistic scenarios for ESCRT-driven cytokinetic abscission.

Graphical Abstract