Interplay between surface and bending energy helps membrane protrusion formation

Abstract

We consider a one-dimensional elastic membrane, which is pushed by growing filaments. The filaments tend to grow by creating local protrusions in the membrane and this process has surface energy and bending energy costs. Although it is expected that with increasing surface tension and bending rigidity, it should become more difficult to create a protrusion, we find that for a fixed bending rigidity, as the surface tension increases, protrusions are more easily formed. This effect also gives rise to non-trivial dependence of membrane velocity on the surface tension, characterized by a dip and a peak. We explain this unusual phenomenon by studying in detail the interplay of the surface and the bending energy and show that this interplay is responsible for a qualitative shape change of the membrane, which gives rise to the above effect. * rajkumar.sadhu@bose.res.in

A theoretical model of efficient phagocytosis driven by curved membrane proteins and active cytoskeleton forces

“…This property defines them as out-of-equilibrium, as they can not arise in an energy conserving system. These active forces represent the pushing forces exerted on the membrane by polymerizing actin filaments, 61–64 which we do not model explicitly to reduce the complexity of the model. 65…”

“…This property defines them as outof-equilibrium, as they can not arise in an energy conserving system. These active forces represent the pushing forces exerted on the membrane by polymerizing actin filaments, [61][62][63][64] which we do not model explicitly to reduce the complexity of the model. 65 Unless specified, we use a vesicle of the total number of vertices, N = 3127 (radius B 20 l min ), where l min is the unit of length in our model and defines the minimum bond length.…”

Experimental and theoretical model for the origin of coiling of cellular protrusions around fibers

“…Cellular protrusions play important roles in exploring and sensing the extracellular environment, during cell spreading and adhesion, cell migration, and cell–cell interaction 1 – 5 . Lamellipodia and filopodia are protrusive structures formed at the leading edge of a migratory cell 6 – 12 . These protrusions enable cells to adhere and spread on fiber-like surfaces 13 – 15 , such as the fibers of the extracellular matrix (ECM) 16 , 17 , as well as cylindrical protrusions of other cells, such as glial cells spreading over neighboring axonal extensions 18 .…”

Three-dimensional chiral morphodynamics of chemomechanical active shells

“…Symmetry-breaking is a fundamental morphogenetic process in the development of organisms starting from their spherical zygotes to complex three-dimensional (3D) patterns and shapes, as widely observed in cell polarity establishment ( 1 ), cell protrusions ( 2 , 3 ), and gastrula invagination ( 4 , 5 ). Among these, left–right symmetry-breaking is one of the most basic and fascinating morphogenetic processes relevant to the biochemical and mechanical spiral pattern formation during early embryonic development ( 6 , 7 ).…”