Cross Talk between β₁and α_VIntegrins: β₁Affects β₃mRNA Stability

Abstract

There is increasing evidence that a fine-tuned integrin cross talk can generate a high degree of specificity in cell adhesion, suggesting that spatially and temporally coordinated expression and activation of integrins are more important for regulated cell adhesive functions than the intrinsic specificity of individual receptors. However, little is known concerning the molecular mechanisms of integrin cross talk. With the use of beta(1)-null GD25 cells ectopically expressing the beta(1)A integrin subunit, we provide evidence for the existence of a cross talk between beta(1) and alpha(V) integrins that affects the ratio of alpha(V)beta(3) and alpha(V)beta(5) integrin cell surface levels. In particular, we demonstrate that a down-regulation of alpha(V)beta(3) and an up-regulation of alpha(V)beta(5) occur as a consequence of beta(1)A expression. Moreover, with the use of GD25 cells expressing the integrin isoforms beta(1)B and beta(1)D, as well as two beta(1) cytoplasmic domain deletion mutants lacking either the entire cytoplasmic domain (beta(1)TR) or only its "variable" region (beta(1)COM), we show that the effects of beta(1) over alpha(V) integrins take place irrespective of the type of beta(1) isoform, but require the presence of the "common" region of the beta(1) cytoplasmic domain. In an attempt to establish the regulatory mechanism(s) whereby beta(1) integrins exert their trans-acting functions, we have found that the down-regulation of alpha(V)beta(3) is due to a decreased beta(3) subunit mRNA stability, whereas the up-regulation of alpha(V)beta(5) is mainly due to translational or posttranslational events. These findings provide the first evidence for an integrin cross talk based on the regulation of mRNA stability.

Integrin αvβ1 promotes infection by human metapneumovirus

“…Moreover, the integrin-specific siRNAs tested here did not inhibit RSV infectivity, suggesting that dampened hMPV growth is not attributable to a nonspecific effect of siRNA (41). A small number of siRNA-treated cells exhibited increased surface expression of ␤1 integrin, possibly via dysregulation of integrin homeostatic networks, altered ␤1 integrin mRNA transcription, or ␤1 integrin pairing with alternate ␣ subunits (42,43). Therefore, we may have underestimated the effect of siRNA-mediated knockdown of integrin expression on hMPV infection.…”

E-cadherin endocytosis regulates the activity of Rap1: a traffic light GTPase at the crossroads between cadherin and integrin function

“…The inhibitors of Src kinase 4-amino-5-(4-chlorophenyl)-7-(tbutyl)pyrazolo [3,4-d]pyrimidine (PP2) and 4-amino-1-tert-butyl-3-(1Ј-naphthyl)pyrazolo [3,4-d]pyrimidine (PP1) were from Calbiochem. Fibronectin (FN) was purified from human plasma as described previously (Retta et al, 2001). Glutathione-Sepharose 4B, protein A-Sepharose and protein G-Sepharose were from Amersham Biosciences.…”

“…GE11 and GD25 cell lines do not express integrins of the ␤ 1 family and have been a valuable model for the functional characterization of distinct ␤ 1 isoforms as well as for the analysis of crosstalk mechanisms between either distinct integrins or integrins and cadherins (Retta et al, 2001;Gimond et al, 1999). GD25 cells expressing the human ␤ 1 A integrin isoform or ␤ 1 TR mutant, lacking the entire cytoplasmic domain, were previously described (Retta et al, 2001).…”

“…GE11 and GD25 cell lines do not express integrins of the ␤ 1 family and have been a valuable model for the functional characterization of distinct ␤ 1 isoforms as well as for the analysis of crosstalk mechanisms between either distinct integrins or integrins and cadherins (Retta et al, 2001;Gimond et al, 1999). GD25 cells expressing the human ␤ 1 A integrin isoform or ␤ 1 TR mutant, lacking the entire cytoplasmic domain, were previously described (Retta et al, 2001). All cell lines were cultured at 37°C and 5% CO 2 atmosphere in Dulbecco's modified Eagle's medium (DMEM; Invitrogen), supplemented with 10% fetal calf serum (FCS; Invitrogen), 2 mM glutamine, 100 U/ml penicillin, and 100 g/ml streptomycin, except for FRT and MCF10A cells, which were cultured in Coon's F-12 medium (Biochrom AG) and mammary epithelial cell medium (MEGM; Cambrex Corporation), respectively.…”

Extended interaction of β1 integrin subunit-deficient cells (GD25) with surfaces modified with fibronectin-derived peptides: Culture optimization, adhesion and cytokine panel studies

“…The β1A integrin splice variant is ubiquitously expressed [19,20], has a broad distribution in vivo [21,22], is capable of activating focal adhesion kinase tyrosine phosphorylation and localizes to focal adhesions [23]. Previous studies employing the GD25 and GD25 β1A lines have not considered the reaction of the cells past 24 h of adhesion and have not examined how the loss of the β1-integrin affects the cellular response to biomaterials beyond the use of protein adsorbed to TCPS [6,[24][25][26][27][28][29][30][31][32][33][34]. In this study, cytokine release from cells adhered to PEGylated-RGD-modifed gelatin sIPNs (RGD-sIPN) and PEGylated-PHSRN-modified gelatin sIPNs (PHSRN-sIPNs) were compared to cells adhered to TCPS, TCPS-FN and sIPN, with PEG hydrogel controls.…”