Local Myo9b RhoGAP activity regulates cell motility

TY - JOUR

T1 - Local Myo9b RhoGAP activity regulates cell motility

AU - Hemkemeyer, Sandra A

AU - Vollmer, Veith

AU - Schwarz, Vera

AU - Lohmann, Birgit

AU - Honnert, Ulrike

AU - Taha, Muna

AU - Schnittler, Hans-Joachim

AU - Bähler, Martin

N1 - Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.

PY - 2020/12/4

Y1 - 2020/12/4

N2 - To migrate, cells assume a polarized morphology, extending forward with a leading edge with their trailing edge retracting back toward the cell body. Both cell extension and retraction critically depend on the organization and dynamics of the actin cytoskeleton, and the small, monomeric GTPases Rac and Rho are important regulators of actin. Activation of Rac induces actin polymerization and cell extension, whereas activation of Rho enhances acto-myosin II contractility and cell retraction. To coordinate migration, these processes must be carefully regulated. The myosin Myo9b, a Rho GTPase-activating protein (GAP), negatively regulates Rho activity and deletion of Myo9b in leukocytes impairs cell migration through increased Rho activity. However, it is not known whether cell motility is regulated by global or local inhibition of Rho activity by Myo9b. Here, we addressed this question by using Myo9b-deficient macrophage-like cells that expressed different recombinant Myo9b constructs. We found that Myo9b accumulates in lamellipodial extensions generated by Rac-induced actin polymerization as a function of its motor activity. Deletion of Myo9b in HL-60-derived macrophages altered cell morphology and impaired cell migration. Reintroduction of Myo9b or Myo9b motor and GAP mutants revealed that local GAP activity rescues cell morphology and migration. In summary, Rac activation leads to actin polymerization and recruitment of Myo9b, which locally inhibits Rho activity to enhance directional cell migration.

AB - To migrate, cells assume a polarized morphology, extending forward with a leading edge with their trailing edge retracting back toward the cell body. Both cell extension and retraction critically depend on the organization and dynamics of the actin cytoskeleton, and the small, monomeric GTPases Rac and Rho are important regulators of actin. Activation of Rac induces actin polymerization and cell extension, whereas activation of Rho enhances acto-myosin II contractility and cell retraction. To coordinate migration, these processes must be carefully regulated. The myosin Myo9b, a Rho GTPase-activating protein (GAP), negatively regulates Rho activity and deletion of Myo9b in leukocytes impairs cell migration through increased Rho activity. However, it is not known whether cell motility is regulated by global or local inhibition of Rho activity by Myo9b. Here, we addressed this question by using Myo9b-deficient macrophage-like cells that expressed different recombinant Myo9b constructs. We found that Myo9b accumulates in lamellipodial extensions generated by Rac-induced actin polymerization as a function of its motor activity. Deletion of Myo9b in HL-60-derived macrophages altered cell morphology and impaired cell migration. Reintroduction of Myo9b or Myo9b motor and GAP mutants revealed that local GAP activity rescues cell morphology and migration. In summary, Rac activation leads to actin polymerization and recruitment of Myo9b, which locally inhibits Rho activity to enhance directional cell migration.

KW - Actin Cytoskeleton/metabolism

KW - Cell Movement/physiology

KW - Cells, Cultured

KW - GTPase-Activating Proteins/genetics

KW - Humans

KW - Macrophages/cytology

KW - Myosins/genetics

KW - Pseudopodia/metabolism

U2 - 10.1074/jbc.RA120.013623

DO - 10.1074/jbc.RA120.013623

M3 - SCORING: Journal article

C2 - 33268376

VL - 296

JO - J BIOL CHEM

JF - J BIOL CHEM

SN - 0021-9258

M1 - 100136

ER -