TY - JOUR
T1 - Two distinct cytoplasmic regions of the beta2 integrin chain regulate RhoA function during phagocytosis
AU - Wiedemann, Agnès
AU - Patel, Jayesh C
AU - Lim, Jenson
AU - Tsun, Andy
AU - van Kooyk, Yvette
AU - Caron, Emmanuelle
PY - 2006/3/27
Y1 - 2006/3/27
N2 - AlphaMbeta2 integrins mediate phagocytosis of opsonized particles in a process controlled by RhoA, Rho kinase, myosin II, Arp2/3, and actin polymerization. AlphaMbeta2, Rho, Arp2/3, and F-actin accumulate underneath bound particles; however, the mechanism regulating Rho function during alphaMbeta2-mediated phagocytosis is poorly understood. We report that the binding of C3bi-opsonized sheep red blood cells (RBCs) to alphaMbeta2 increases Rho-GTP, but not Rac-GTP, levels. Deletion of the cytoplasmic domain of beta2, but not of alphaM, abolished Rho recruitment and activation, as well as phagocytic uptake. Interestingly, a 16-amino acid (aa) region in the membrane-proximal half of the beta2 cytoplasmic domain was necessary for activating Rho. Three COOH-terminal residues (aa 758-760) were essential for beta2-induced accumulation of Rho at complement receptor 3 (CR3) phagosomes. Activation of Rho was necessary, but not sufficient, for its stable recruitment underneath bound particles or for uptake. However, recruitment of active Rho was sufficient for phagocytosis. Our data shed light on the mechanism of outside-in signaling, from ligated integrins to the activation of Rho GTPase signaling.
AB - AlphaMbeta2 integrins mediate phagocytosis of opsonized particles in a process controlled by RhoA, Rho kinase, myosin II, Arp2/3, and actin polymerization. AlphaMbeta2, Rho, Arp2/3, and F-actin accumulate underneath bound particles; however, the mechanism regulating Rho function during alphaMbeta2-mediated phagocytosis is poorly understood. We report that the binding of C3bi-opsonized sheep red blood cells (RBCs) to alphaMbeta2 increases Rho-GTP, but not Rac-GTP, levels. Deletion of the cytoplasmic domain of beta2, but not of alphaM, abolished Rho recruitment and activation, as well as phagocytic uptake. Interestingly, a 16-amino acid (aa) region in the membrane-proximal half of the beta2 cytoplasmic domain was necessary for activating Rho. Three COOH-terminal residues (aa 758-760) were essential for beta2-induced accumulation of Rho at complement receptor 3 (CR3) phagosomes. Activation of Rho was necessary, but not sufficient, for its stable recruitment underneath bound particles or for uptake. However, recruitment of active Rho was sufficient for phagocytosis. Our data shed light on the mechanism of outside-in signaling, from ligated integrins to the activation of Rho GTPase signaling.
KW - Actins/metabolism
KW - Amino Acid Sequence
KW - Animals
KW - CD18 Antigens/genetics
KW - COS Cells
KW - Cell Line, Tumor
KW - Cercopithecus aethiops
KW - Complement C3b/chemistry
KW - Erythrocytes/chemistry
KW - Guanosine Triphosphate/metabolism
KW - Macrophage-1 Antigen/genetics
KW - Macrophages/drug effects
KW - Mice
KW - Molecular Sequence Data
KW - Mutation
KW - Phagocytosis/drug effects
KW - Phagosomes/metabolism
KW - Tetradecanoylphorbol Acetate/pharmacology
KW - Threonine/genetics
KW - Transfection
KW - rac1 GTP-Binding Protein/metabolism
KW - rhoA GTP-Binding Protein/genetics
U2 - 10.1083/jcb.200508075
DO - 10.1083/jcb.200508075
M3 - Article
C2 - 16567504
VL - 172
SP - 1069
EP - 1079
JO - Journal of Cell Biology
JF - Journal of Cell Biology
SN - 0021-9525
IS - 7
ER -