The unique disulfide bond-stabilized W1 ?4-?1 loop in the ?4 ?-propeller domain regulates integrin ?4?7 affinity and signaling.

ABSTRACT: Integrin ?4?7 mediates rolling and firm adhesion of lymphocytes pre- and post-activation, which is distinct from most integrins only mediating firm cell adhesion upon activation. This two-phase cell adhesion suggests a unique molecular basis for the dynamic interaction of ?4?7 with its ligand, mucosal addressin cell adhesion molecule 1 (MAdCAM-1). Here we report that a disulfide bond-stabilized W1 ?4-?1 loop in ?4 ?-propeller domain plays critical roles in regulating integrin ?4?7 affinity and signaling. Either breaking the disulfide bond or deleting the disulfide bond-occluded segment in the W1 ?4-?1 loop inhibited rolling cell adhesion supported by the low-affinity interaction between MAdCAM-1 and inactive ?4?7 but negligibly affected firm cell adhesion supported by the high-affinity interaction between MAdCAM-1 and Mn(2+)-activated ?4?7. Additionally, disrupting the disulfide bond or deleting the disulfide bond-occluded segment not only blocked the conformational change and activation of ?4?7 triggered by talin or phorbol-12-myristate-13-acetate via inside-out signaling but also disrupted integrin-mediated outside-in signaling and impaired phosphorylation of focal adhesion kinase and paxillin. Thus, these findings reveal a particular molecular basis for ?4?7-mediated rolling cell adhesion and a novel regulatory element of integrin affinity and signaling.

SUBMITTER: Yue J 

PROVIDER: S-EPMC3656279 | biostudies-literature | 2013 May

REPOSITORIES: biostudies-literature