TY - JOUR
T1 - Genetic perturbation of the putative cytoplasmic membrane-proximal salt bridge aberrantly activates α4 integrins
AU - Imai, Yoichi
AU - Park, Eun Jeong
AU - Peer, Dan
AU - Peixoto, António
AU - Cheng, Guiying
AU - Von Andrian, Ulrich H.
AU - Carman, Christopher V.
AU - Shimaoka, Motomu
N1 - Copyright:
Copyright 2021 Elsevier B.V., All rights reserved.
PY - 2008/12/15
Y1 - 2008/12/15
N2 - α 4 integrins play a pivotal role in leukocyte migration and tissue-specific homing. The ability of integrins to bind ligand is dynamically regulated by activation-dependent conformational changes triggered in the cytoplasmic domain. An NMR solution structure defined a putative membrane-proximal salt bridge between the α llbβ 3 integrin cytoplasmic tails, which restrains integrins in their low-affinity state. However, the physiological importance of this salt bridge in α 4 integrin regulation remains to be elucidated. To address this question, we disrupted the salt bridge in murine germ line by mutating the conserved cytoplasmic arginine R GFFKR in α 4 integrins. In lymphocytes from knock-in mice (α 4-R/A GFFKR), α 4β 1 and α 4β 7 integrins exhibited constitu-tively up-regulated ligand binding. However, transmigration of these cells across VCAM-1 and MAdCAM-1 substrates, or across endothelial monolayers, was reduced. Perturbed detachment of the tail appeared to cause the reduced cell migration of α 4-R/A GFFKR lymphocytes. In vivo, α 4-R/A GGGKR cells exhibited increased firm adhesion to Peyer patch venules but reduced homing to the gut. Our results demonstrate that the membrane-proximal salt bridge plays a critical role in supporting proper α 4 integrin adhesive dynamics. Loss of this interaction destabilizes the nonadhesive conformation, and thereby perturbs the properly balanced cycles of adhesion and deadhesion required for efficient cell migration.
AB - α 4 integrins play a pivotal role in leukocyte migration and tissue-specific homing. The ability of integrins to bind ligand is dynamically regulated by activation-dependent conformational changes triggered in the cytoplasmic domain. An NMR solution structure defined a putative membrane-proximal salt bridge between the α llbβ 3 integrin cytoplasmic tails, which restrains integrins in their low-affinity state. However, the physiological importance of this salt bridge in α 4 integrin regulation remains to be elucidated. To address this question, we disrupted the salt bridge in murine germ line by mutating the conserved cytoplasmic arginine R GFFKR in α 4 integrins. In lymphocytes from knock-in mice (α 4-R/A GFFKR), α 4β 1 and α 4β 7 integrins exhibited constitu-tively up-regulated ligand binding. However, transmigration of these cells across VCAM-1 and MAdCAM-1 substrates, or across endothelial monolayers, was reduced. Perturbed detachment of the tail appeared to cause the reduced cell migration of α 4-R/A GFFKR lymphocytes. In vivo, α 4-R/A GGGKR cells exhibited increased firm adhesion to Peyer patch venules but reduced homing to the gut. Our results demonstrate that the membrane-proximal salt bridge plays a critical role in supporting proper α 4 integrin adhesive dynamics. Loss of this interaction destabilizes the nonadhesive conformation, and thereby perturbs the properly balanced cycles of adhesion and deadhesion required for efficient cell migration.
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U2 - 10.1182/blood-2008-03-144543
DO - 10.1182/blood-2008-03-144543
M3 - Article
C2 - 18809756
AN - SCOPUS:58149393174
SN - 0006-4971
VL - 112
SP - 5007
EP - 5015
JO - Blood
JF - Blood
IS - 13
ER -