scholarly journals Association between a transmembrane protein tyrosine phosphatase and the cadherin-catenin complex.

1996 ◽  
Vol 134 (6) ◽  
pp. 1519-1529 ◽  
Author(s):  
R M Kypta ◽  
H Su ◽  
L F Reichardt

Cadherins are calcium-dependent cell adhesion molecules that play fundamental roles in embryonic development, tissue morphogenesis, and cancer. A prerequisite for their function is association with the actin cytoskeleton via the catenins. Tyrosine phosphorylation of beta-catenin, which correlates with a reduction in cadherin-dependent cell adhesion, may provide cells with a mechanism to regulate cadherin activity. Here we report that beta-catenin immune precipitates from PC12 cells contain tyrosine phosphatase activity which dephosphorylates beta-catenin in vitro. In addition, we show that a member of the leukocyte antigen-related protein (LAR)-related transmembrane tyrosine phosphatase family (LAR-PTP) associates with the cadherin-catenin complex. This association required the amino-terminal domain of beta-catenin but does not require the armadillo repeats, which mediate association with cadherins. The interaction also is detected in PC9 cells, which lack alpha-catenin. Thus, the association is not mediated by alpha-catenin or by cadherins. Interestingly, LAR-PTPs are phosphorylated on tyrosine in a TrkA-dependent manner, and their association with the cadherin-catenin complex is reduced in cells treated with NGF. We propose that changes in tyrosine phosphorylation of beta-catenin mediated by TrkA and LAR-PTPs control cadherin adhesive function during processes such as neurite outgrowth.

1994 ◽  
Vol 124 (5) ◽  
pp. 729-741 ◽  
Author(s):  
L Hinck ◽  
WJ Nelson ◽  
J Papkoff

Wnt-1 homologs have been identified in invertebrates and vertebrates and play important roles in cellular differentiation and organization. In Drosophila, the products of the segment polarity genes wingless (the Wnt-1 homolog) and armadillo participate in a signal transduction pathway important for cellular boundary formation in embryonic development, but functional interactions between the proteins are unknown. We have examined Wnt-1 function in mammalian cells in which armadillo (beta-catenin and plakoglobin) is known to bind to and regulate cadherin cell adhesion proteins. We show that Wnt-1 expression results in the accumulation of beta-catenin and plakoglobin. In addition, binding of beta-catenin to the cell adhesion protein, cadherin, is stabilized, resulting in a concomitant increase in the strength of calcium-dependent cell-cell adhesion. Thus, a consequence of the functional interaction between Wnt-1 and armadillo family members is the strengthening of cell-cell adhesion, which may lead to the specification of cellular boundaries.


1997 ◽  
Vol 110 (8) ◽  
pp. 1013-1022 ◽  
Author(s):  
J.E. Nieset ◽  
A.R. Redfield ◽  
F. Jin ◽  
K.A. Knudsen ◽  
K.R. Johnson ◽  
...  

Cadherins are calcium-dependent, cell surface glycoproteins involved in cell-cell adhesion. To function in cell-cell adhesion, the transmembrane cadherin molecule must be associated with the cytoskeleton via cytoplasmic proteins known as catenins. Three catenins, alpha-catenin, beta-catenin and gamma-catenin (also known as plakoglobin), have been identified. beta-catenin or plakoglobin is associated directly with the cadherin; alpha-catenin binds to beta-catenin/plakoglobin and serves to link the cadherin/catenin complex to the actin cytoskeleton. The domains on the cadherin and betacatenin/plakoglobin that are responsible for protein-protein interactions have been mapped. However, little is known about the molecular interactions between alpha-catenin and beta-catenin/plakoglobin or about the interactions between alpha-catenin and the cytoskeleton. In this study we have used the yeast two-hybrid system to map the domains on alpha-catenin that allow it to associate with beta-catenin/plakoglobin and with alpha-actinin. We also identify a region on alpha-actinin that is responsible for its interaction with alpha-catenin. The yeast two-hybrid data were confirmed with biochemical studies.


1992 ◽  
Vol 118 (3) ◽  
pp. 671-679 ◽  
Author(s):  
K A Knudsen ◽  
M J Wheelock

E- and N-cadherin are members of a family of calcium-dependent, cell surface glycoproteins involved in cell-cell adhesion. Extracellularly, the transmembrane cadherins self-associate, while, intracellularly, they interact with the actin-based cytoskeleton. Several intracellular proteins, collectively termed catenins, have been noted to co-immunoprecipitate with E- and N-cadherin and are thought to be involved in linking the cadherins to the cytoskeleton. Two catenins have been identified recently: a 102-kD vinculin-like protein (alpha-catenin) and a 92-kD Drosophila armadillo/plakoglobin-like protein (beta-catenin). Here, we show that plakoglobin, or an 83-kD plakoglobin-like protein, co-immunoprecipitates and colocalizes with both E- and N-cadherin. The 83-kD protein is immunologically distinct from the 92-kD beta-catenin and, because of its molecular mass, likely represents the cadherin-associated protein called gamma-catenin. Thus, two different members of a plakoglobin family associate with N- and E-cadherin and, together with the 102-kD alpha-catenin, appear to participate in linking the cadherins to the actin-based cytoskeleton.


1999 ◽  
Vol 112 (18) ◽  
pp. 3005-3014 ◽  
Author(s):  
N. Ilan ◽  
S. Mahooti ◽  
D.L. Rimm ◽  
J.A. Madri

Catenins function as regulators of cellular signaling events in addition to their previously documented roles in adherens junction formation and function. Evidence to date suggests that beta and gamma catenins can act as signaling molecules, bind transcriptional factors and translocate to the nucleus. Beta- and gamma-catenin are also major substrates for protein tyrosine kinases, and tyrosine phosphorylation of junctional proteins is correlated with decreased adhesiveness. One way in which catenin functions are modulated is by dynamic incorporation into junctional complexes which controls, in part, the cytoplasmic levels of catenins. Here we show that: (1) vascular endothelial growth factor (VEGF) induces beta-catenin tyrosine phosphorylation in a time-, and dose-dependent manner and that VEGF receptors co-localize to areas of endothelial cell-cell contact in vitro and in vivo. (2) Platelet-endothelial cell adhesion molecule (PECAM)-1 can function as a reservoir for, and modulator of, tyrosine phosphorylated beta-catenin. (3) PECAM-1 can prevent beta-catenin nuclear translocation in transfected SW480 colon carcinoma cells. We suggest that PECAM-1 may play a role in modulating beta-catenin tyrosine phosphorylation levels, localization and signaling and by doing so, functions as an important modulator of the endothelium.


2003 ◽  
Vol 14 (6) ◽  
pp. 2520-2529 ◽  
Author(s):  
Carol Wadham ◽  
Jennifer R Gamble ◽  
Mathew A Vadas ◽  
Yeesim Khew-Goodall

Cell-cell adhesion regulates processes important in embryonal development, normal physiology, and cancer progression. It is regulated by various mechanisms including tyrosine phosphorylation. We have previously shown that the protein tyrosine phosphatase Pez is concentrated at intercellular junctions in confluent, quiescent monolayers but is nuclear in cells lacking cell-cell contacts. We show here with an epithelial cell model that Pez localizes to the adherens junctions in confluent monolayers. A truncation mutant lacking the catalytic domain acts as a dominant negative mutant to upregulate tyrosine phosphorylation at adherens junctions. We identified β-catenin, a component of adherens junctions, as a substrate of Pez by a “substrate trapping” approach and by in vitro dephosphorylation with recombinant Pez. Consistent with this, ectopic expression of the dominant negative mutant caused an increase in tyrosine phosphorylation of β-catenin, demonstrating that Pez regulates the level of tyrosine phosphorylation of adherens junction proteins, including β-catenin. Increased tyrosine phosphorylation of adherens junction proteins has been shown to decrease cell-cell adhesion, promoting cell migration as a result. Accordingly, the dominant negative Pez mutant enhanced cell motility in an in vitro “wound” assay. This suggests that Pez is also a regulator of cell motility, most likely through its action on cell-cell adhesion.


1994 ◽  
Vol 107 (6) ◽  
pp. 1583-1591 ◽  
Author(s):  
C.E. Turner ◽  
J.T. Miller

Paxillin is a cytoskeletal protein involved in actin-membrane attachment at sites of cell adhesion to the extracellular matrix. Extensive tyrosine phosphorylation of this protein occurs during integrin-mediated cell adhesion, embryonic development, fibroblast transformation and following stimulation of cells by mitogens that operate through the family of seven membrane-spanning G-protein-coupled receptors. Paxillin binds in vitro to the focal adhesion protein vinculin as well as to the SH3 domain of c-src and, when tyrosine phosphorylated, to the SH2 domain of v-crk. Here, we report the complementary DNA, and derived amino acid sequence, that codes for approximately 90% of the paxillin protein. We have identified a region in the amino-terminal half of the protein that supports the binding of both vinculin and the focal adhesion tyrosine kinase, pp125Fak. Although there is no significant overall homology with other identified proteins, the carboxyl third of paxillin contains one LIM domain and three LIM-like sequences. The LIM motif is common to a number of transcription factors and to two other focal adhesion proteins, zyxin and cysteine-rich protein. In addition to several potential tyrosine phosphorylation sites there are five tyrosine-containing sequences that conform to SH2-binding motifs. The protein also contains a short proline-rich region indicative of a SH3-binding domain. Taken together, these data suggest that paxillin is a unique cytoskeletal protein capable of interaction with a variety of intracellular signalling, and structural, molecules important in growth control and the regulation of cytoskeletal organization.(ABSTRACT TRUNCATED AT 250 WORDS)


2007 ◽  
Vol 6 (6) ◽  
pp. 931-939 ◽  
Author(s):  
Fang Li ◽  
Michael J. Svarovsky ◽  
Amy J. Karlsson ◽  
Joel P. Wagner ◽  
Karen Marchillo ◽  
...  

ABSTRACT Candida albicans is the leading cause of systemic fungal infections in immunocompromised humans. The ability to form biofilms on surfaces in the host or on implanted medical devices enhances C. albicans virulence, leading to antimicrobial resistance and providing a reservoir for infection. Biofilm formation is a complex multicellular process consisting of cell adhesion, cell growth, morphogenic switching between yeast form and filamentous states, and quorum sensing. Here we describe the role of the C. albicans EAP1 gene, which encodes a glycosylphosphatidylinositol-anchored, glucan-cross-linked cell wall protein, in adhesion and biofilm formation in vitro and in vivo. Deleting EAP1 reduced cell adhesion to polystyrene and epithelial cells in a gene dosage-dependent manner. Furthermore, EAP1 expression was required for C. albicans biofilm formation in an in vitro parallel plate flow chamber model and in an in vivo rat central venous catheter model. EAP1 expression was upregulated in biofilm-associated cells in vitro and in vivo. Our results illustrate an association between Eap1p-mediated adhesion and biofilm formation in vitro and in vivo.


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