Journal Article

Membrane Tension Acts Through PLD2 and mTORC2 to Limit Actin Network Assembly During Neutrophil Migration

Chintamen, Sana, Fletcher, Daniel A., Wu, Lani F., Altschuler, Steven J., Weiner, Orion D., Diz-Muñoz, Alba, Thurley, Kevin

2016

Overview

For efficient polarity and migration, cells need to regulate the magnitude and spatial distribution of actin assembly. This process is coordinated by reciprocal interactions between the actin cytoskeleton and mechanical forces. Actin polymerization-based protrusion increases tension in the plasma membrane, which in turn acts as a long-range inhibitor of actin assembly. These interactions form a negative feedback circuit that limits the magnitude of membrane tension in neutrophils and prevents expansion of the existing front and the formation of secondary fronts. It has been suggested that the plasma membrane directly inhibits actin assembly by serving as a physical barrier that opposes protrusion. Here we show that efficient control of actin polymerization-based protrusion requires an additional mechanosensory feedback cascade that indirectly links membrane tension with actin assembly. Specifically, elevated membrane tension acts through phospholipase D2 (PLD2) and the mammalian target of rapamycin complex 2 (mTORC2) to limit actin nucleation. In the absence of this pathway, neutrophils exhibit larger leading edges, higher membrane tension, and profoundly defective chemotaxis. Mathematical modeling suggests roles for both the direct (mechanical) and indirect (biochemical via PLD2 and mTORC2) feedback loops in organizing cell polarity and motility-the indirect loop is better suited to enable competition between fronts, whereas the direct loop helps spatially organize actin nucleation for efficient leading edge formation and cell movement. This circuit is essential for polarity, motility, and the control of membrane tension.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Actin Cytoskeleton - metabolism / Actins - metabolism / Barriers / Behavior / Biology and Life Sciences / Blotting, Western / Cell adhesion & migration / Cell Membrane - metabolism / Cell Movement / Cell Polarity / Competition / Cytoskeleton / Engineering and Technology / Eukaryotes / Experiments / HEK293 Cells / HL-60 Cells / Humans / Knowledge sharing / Mathematical models / Mechanistic Target of Rapamycin Complex 2 / Mechanotransduction, Cellular / Medical research / Medicine and Health Sciences / Membrane proteins / Membranes / Microscopy, Fluorescence - methods / Models, Biological / Motility / Multiprotein Complexes - genetics / Multiprotein Complexes - metabolism / Neutrophils / Neutrophils - metabolism / Nucleation / Observations / Phospholipase D - genetics / Phospholipase D - metabolism / Physical Sciences / Physiological aspects / Plasma / Polymerization / Protein-protein interactions / Rapamycin / RNA Interference / Scholarships & fellowships / Simulation / Spatial distribution / Tension / TOR Serine-Threonine Kinases - genetics / TOR Serine-Threonine Kinases - metabolism