title: Exocytotic fusion pore stability and topological defects in the membrane with orientational degree of ordering.
abstract: Regulated exocytosis is a process that strongly depends on the formation and stability of the fusion pore. It was indicated experimentally and theoretically that narrow and highly curved fusion pore may be stabilized by accumulation of anisotropic membrane components possessing orientational ordering. On the other hand, narrow fusion pore may also undergo repetitive opening and closing, disruption in the so called kiss and run process or become completely opened in the process of full fusion of the vesicle with the membrane. In this paper we attempt to elucidate the subtle interplay between the stabilizing and destabilizing processes in the fusion neck. A possible physical mechanism which may lead to disruption of the stable fusion pore or complete fusion of the vesicle with the membrane is discussed. It is indicated that topologically driven defects of the in-plane orientational membrane ordering in the region of the fusion pore may disrupt the fusion. Alternatively, it may facilitate repetitive opening and closing of the fusion pore or induce full fusion of the vesicle with the target membrane.
authors.affiliation: Department of Condensed Matter Physics, J. Stefan Institute, SI-1000 Ljubljana, Slovenia.
authors.forename: Dalija
authors.initials: D
authors.lastname: Jesenek
authors.forename: Sárka
authors.initials: S
authors.lastname: Perutková
authors.forename: Veronika
authors.initials: V
authors.lastname: Kralj-Iglič
authors.forename: Samo
authors.initials: S
authors.lastname: Kralj
authors.forename: Aleš
authors.initials: A
authors.lastname: Iglič
mesh_terms: D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D005089:Exocytosis / Q000502:physiology*; D008561:Membrane Fusion / Q000502:physiology*; D008962:Models, Theoretical; D022142:Secretory Vesicles / Q000378:metabolism