Remodelling of membrane tubules by the actin cytoskeleton

Abstract

Inside living cells, the remodelling of membrane tubules by actomyosin networks is crucial for processes such as intracellular trafficking or organelle reshaping. In this review, we first present various in vivo situations in which actin affects membrane tubule remodelling, then we recall some results on force production by actin dynamics and on membrane tubules physics. Finally, we show that our knowledge of the underlying mechanisms by which actomyosin dynamics affect tubule morphology has recently been moved forward. This is thanks to in vitro experiments that mimic cellular membranes and actin dynamics and allow deciphering the physics of tubule remodelling in biochemically controlled conditions, and shed new light on tubule shape regulation.

Spatial Control of Arp2/3-Induced Actin Polymerization on Phase-Separated Giant Unilamellar Vesicles

“…Our results pave the way for studies mimicking biological processes, such as endocytosis or intracellular trafficking. Indeed, such cell processes require crosstalk between the cytoskeleton and domains formed in biological membranes . Using phase-separated membranes, we could also build more complicated systems in which different actin activators could coexist on the same membrane, as is the case in cells.…”

“…Indeed, such cell processes require crosstalk between the cytoskeleton and domains formed in biological membranes. 51 Using phase-separated membranes, we could also build more complicated systems in which different actin activators could coexist on the same membrane, as is the case in cells. For instance, the lamellipodium contains both Arp2/3 and formins that simultaneously activate actin polymerization at the cell membrane and nucleate different types of networks.…”

Membrane-dependent actin polymerization mediated by the Legionella pneumophila effector protein MavH

“…In diverse cellular processes, the actin network has been implicated in membrane deformation by generating pulling or pushing forces [50]. To examine morphological changes of liposomes caused by membrane-dependent actin polymerization mediated by MavH, we employed TIRFM and electron microscopy (EM) approaches.…”

Studying actin-induced cell shape changes using Giant Unilamellar Vesicles and reconstituted actin networks

“…Finally, the same assay was adapted to reconstitute dynamic actin networks at the surface of membrane nanotubes formed from GUVs ( Figure 2E ) [ 43 ]. The objective of this study was to decipher the largely unknown mechanisms by which actin dynamics contribute to the remodeling of membrane nanotubes inside the cell [ 44 ]. During intracellular trafficking, nanotubes are pulled by molecular motors walking on microtubules at the velocity of one micrometer per second.…”