Membrane Tension Acts Through PLD2 and mTORC2 to Limit Actin Network Assembly During Neutrophil Migration.
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.
Cardiovascular Research Institute and Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California, United States of America.|Bioengineering Department and Biophysics Program, University of California Berkeley, Berkeley, California, United States of America.
Alba
A
Diz-Muñoz
Dept. of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California, United States of America.
Kevin
K
Thurley
Cardiovascular Research Institute and Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California, United States of America.
Sana
S
Chintamen
Dept. of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California, United States of America.
Steven J
SJ
Altschuler
Dept. of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California, United States of America.
Lani F
0000-0002-0052-7537
LF
Wu
Bioengineering Department and Biophysics Program, University of California Berkeley, Berkeley, California, United States of America.
Daniel A
DA
Fletcher
Cardiovascular Research Institute and Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California, United States of America.
Orion D
OD
Weiner
D008841:Actin Cytoskeleton / Q000378:metabolism*; D000199:Actins / Q000378:metabolism; D015153:Blotting, Western; D002462:Cell Membrane / Q000378:metabolism*; D002465:Cell Movement; D016764:Cell Polarity; D057809:HEK293 Cells; D018922:HL-60 Cells; D006801:Humans; D000076225:Mechanistic Target of Rapamycin Complex 2; D040542:Mechanotransduction, Cellular; D008856:Microscopy, Fluorescence / Q000379:methods; D008954:Models, Biological; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism*; D009504:Neutrophils / Q000378:metabolism*; D010739:Phospholipase D / Q000235:genetics / Q000378:metabolism*; D058105:Polymerization; D034622:RNA Interference; D058570:TOR Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*
D000199:Actins; D046912:Multiprotein Complexes; D000076225:Mechanistic Target of Rapamycin Complex 2; D058570:TOR Serine-Threonine Kinases; C105606:phospholipase D2; D010739:Phospholipase D