Septin Dynamics Are Essential for Exocytosis

Abstract

Background: Septins serve as scaffolds for membrane-associated protein complexes. Results: Knockdown of septin-2 or disruption of septin assembly/disassembly impairs interactions between exocytic proteins and inhibits late steps of exocytosis. Conclusion: Septins undergo dynamic reorganization to facilitate localized and timely interactions between exocytosis-essential proteins. Significance: Both the presence of septin-2 and active reorganization of septin oligomers are required for exocytosis.

Septins guide microtubule protrusions induced by actin-depolymerizing toxins like Clostridium difficile transferase (CDT)

“…Septins are conserved GTP-binding proteins, which form hetero-oligomers and polymers, and are considered as the fourth component of the cytoskeleton in addition to microfilaments, microtubules, and intermediate filaments (11)(12)(13). Septins are involved in numerous functions, including cytokinesis, ciliogenesis, neurite development, and exocytosis (14)(15)(16)(17). They have scaffold functions, act as membrane diffusion barriers, and are involved in hostpathogen interactions.…”

Biophysical dissection of schistosome septins: Insights into oligomerization and membrane binding

“…Our results imply that septins may play a far more active role in the process of exocytosis than the currently proposed regulatory role, mediated through focal septin assemblies on the surface of the emerging secretory vesicle [45][46][47]. Based on our findings it is tempting to propose that septins form a mesh on the membrane surface that 21 contributes to the process of membrane deformation and that serves as a scaffold to which other proteins from the exocytotic pathway adhere.…”

Septins in kidney: A territory little explored

“…The authors also showed that FCF-treatment of MDCK cells led to changes in the size and distribution of SEPT2 filaments and accumulation of cargo-carrying intracellular vesicles destined to be trafficked to the plasma membrane, indicating that SEPT2 and dynamic reorganization of septin filaments are essential for exocytosis (Tokhtaeva et al, 2015). Several other studies point out a role for septins in vesicle trafficking, proposing also inhibitory effects for septins in exocytosis (Amin et al, 2008;Beites et al, 1999;Wasik et al, 2012).…”

“…The authors found that SEPT9 cross-links preassembled actin stress fibers at the front of migrating kidney epithelial cells and thereby maintains the organization of the lamellar actin network (Dolat et al, 2014). protein by reducing its post-Golgi trafficking (Tokhtaeva et al, 2015).…”