Induced Nanoscale Membrane Curvature Bypasses Clathrin’s Essential Endocytic Function

Abstract

During clathrin-mediated endocytosis (CME), flat plasma membrane is rapidly remodeled to produce a nanometer-scale spherical vesicle. The mechanisms underlying this shape change are not known, but it has been hypothesized that the clathrin coat stabilizes membrane curvature. Here, we used nanopatterning to produce glass-like substrates with U-shaped features mimicking membrane shapes induced by fibrillar materials such as collagen. These substrates bend the ventral plasma membranes of cells grown on them into shapes characteristic of the energetically-unfavorable U-shaped intermediate stage of CME. This induced plasma membrane curvature recruits the endocytic machinery, enhances endocytic site maturation, and partially bypasses clathrin's role in CME, supporting the conclusion that clathrin's essential endocytic function is to stabilize membrane curvature.

Plasma membrane nanodeformations promote actin polymerization through CIP4/CDC42 recruitment and regulate type II IFN signaling

“…Membrane curvature might promote its assembly on plasma membrane to facilitate endocytosis. This coupling between plasma membrane curvature and endocytosis dynamics was previously demonstrated for clathrin-mediated endocytosis and proposed for clathrin-independent pathways ( 10 , 11 , 49 , 50 ). These curved membrane regions could therefore be hotspots for various endocytic pathways because of the possible reduction of membrane bending energy.…”

“…Of these, cell deformation caused by nanoscale topographical features of the culture substrate has been shown to alter key cellular functions such as adhesion (1,2), differentiation (3)(4)(5), proliferation (6,7), and migration (8). In parallel, plasma membrane curvature has been shown to influence several molecular processes, including focal adhesion formation (1,8,9), clathrin-mediated endocytosis (10,11), and actin polymerization (12,13). However, numerous gaps remain in the understanding of these molecular mechanisms and their connection with changes in cellular behavior.…”

Fluidic shear stress alters clathrin dynamics and vesicle formation in endothelial cells

“…These can be divided into contact-derived stresses, originating from vessel topography, curvature, and stiffness, and flow-derived stresses such as fluidic shear stress (FSS), pressure, and tensile strain caused by the blood flow (Dessalles et al, 2021). It has been shown in non-endothelial cells that intrinsic plasma membrane curvature dramatically impacts the proteome required for endocytosis (Cail et al, 2022), while stiffer substrates (Baschieri et al, 2018), cell squeezing, and increased osmotic pressure inhibit endocytosis (Ferguson et al, 2017). The mechanical impact on endocytosis has been recently reviewed (Joseph and Liu, 2020).…”

Endocytic myosin-1 is a force-insensitive, power-generating motor

“…During clathrin-mediated endocytosis (CME), the plasma membrane invaginates into a pit and undergoes scission to become a cytoplasmic vesicle. The endocytic coat can deform membranes and stabilize curvature for membranes under low tension (Dannhauser and Ungewickell, 2012; Busch et al, 2015; Cail et al, 2022), but in the cell, bending is resisted by membrane tension (Hassinger et al, 2017). Under conditions of high membrane tension, the actin cytoskeleton assists plasma membrane invagination (Boulant et al, 2011; Kaplan et al, 2022).…”