Activation-dependent changes in soluble fibronectin binding and expression of β1 integrin activation epitopes in T cells: relationship to T cell adhesion and migration

Abstract

The relationship between activation-dependent changes in g 1 integrin conformation, T cell adhesion to immobilized fibronectin, and T cell migration in vitro was analyzed in this study. Stimulation of Jurkat T cells and peripheral T cells with Mn 2+ , the activating g 1 integrin-specific monoclonal antibody (mAb) TS2/16, CD2, or CD28 stimulation led to increased adhesion, soluble fibronectin (FN) binding and expression of the activation epitope defined by the g 1 integrin mAb HUTS-21. Phorbol 12-myristate 13-acetate treatment increased adhesion, but not soluble FN binding or HUTS-21 epitope expression. In peripheral T cells, CD3 or CD7 stimulation also led to increased adhesion, soluble FN binding and HUTS-21 epitope expression. Soluble FN blocked peripheral T cell adhesion induced by Mn 2+ or TS2/ 16, but had no effect on adhesion induced by the other integrin-activating signals. In contrast , migration induced by TS2/16, CD2, CD3, CD7 or CD28 stimulation was blocked by excess soluble FN. Phosphoinositide 3-OH kinase (PI 3-K) inhibitors blocked receptor-mediated increases in cell adhesion, but not soluble FN binding or HUTS-21 expression. Migration was similarly unaffected by PI 3-K inhibitors, with the exception of CD7-and CD28-induced migration, which was specifically blocked by LY294,002. These results suggest that activation-dependent changes in g 1 integrin conformation are PI 3-K-independent and are involved in T cell migration but not adhesion.

Two Functional Active Conformations of the Integrin α2β1, Depending on Activation Condition and Cell Type

“…Here we only used divalent cations for activation because TS2/16 had no effect on these cell types, and addition of DTT resulted in a marked down-regulation of ␣2␤1, as determined by AK-7 binding (data not shown). The latter is consistent with previous reports describing that DTT can affect integrin expression on lymphocytes (39). Activation of ␣2␤1 on PBMC and Jurkat cells by the divalent cations Mn 2ϩ and Co 2ϩ resulted in a significant increase in collagen binding, indicating that ␣2␤1 was activated (p Ͻ 0.05; Fig.…”

Control of TCR-Mediated Activation of β1 Integrins by the ZAP-70 Tyrosine Kinase Interdomain B Region and the Linker for Activation of T Cells Adapter Protein

“…In addition, the Y315 and Y292 residues in ZAP-70 mediate positive and negative regulatory effects on CD3/TCR-mediated activation of PI3-K. LAT appears to play a central role in ZAP-70-dependent regulation of PI3-K by the TCR because the Y315 and Y292 residues regulate ZAP-70-mediated phosphorylation of LAT tyrosines 171 and 191, which are known to mediate binding of LAT to the p85 regulatory subunit of PI3-K upon TCR stimulation (31). These results are consistent with previous studies that have implicated PI3-K in the regulation of integrin function by the CD3/ TCR (16,61).…”

Sustained Induction of ERK, Protein Kinase B, and p70 S6 Kinase Regulates Cell Spreading and Formation of F-actin Microspikes Upon Ligation of Integrins by Galectin-8, a Mammalian Lectin

“…These functions rely on spatio-temporal expression of adhesive as well as anti-adhesive components of the ECM proteins (6). ECM proteins like fibronectin (7)(8)(9), collagen (10), and laminin (11) are best characterized, though other types of proteins, including mammalian lectins, also function as modulators of cell adhesion. Selectins mediate cell-cell interactions (12) through calciumdependent recognition of sialylated glycans (13,14), whereas galectins, animal lectins that specifically bind ␤-galactoside residues (15), were implicated as modulators of cell-matrix interactions.…”