Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:B0FTZ7 (catenin)
 18,795 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cadherins are Ca(2+)-dependent, cell surface glycoproteins involved in cell-cell adhesion. Extracellularly, transmembrane cadherins such as E-, P-, and N-cadherin self-associate, while intracellularly they interact indirectly with the actin-based cytoskeleton. Several intracellular proteins termed catenins, including alpha-catenin, beta-catenin, and plakoglobin, are tightly associated with these cadherins and serve to link them to the cytoskeleton. Here, we present evidence that in fibroblasts alpha-actinin, but not vinculin, colocalizes extensively with the N-cadherin/catenin complex. This is in contrast to epithelial cells where both cytoskeletal proteins colocalize extensively with E-cadherin and catenins. We further show that alpha-actinin, but not vinculin, coimmunoprecipitates specifically with alpha- and beta-catenin from N- and E-cadherin-expressing cells, but only if alpha-catenin is present. Moreover, we show that alpha-actinin coimmunoprecipitates with the N-cadherin/catenin complex in an actin-independent manner. We therefore propose that cadherin/catenin complexes are linked to the actin cytoskeleton via a direct association between alpha-actinin and alpha-catenin.
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PMID:Interaction of alpha-actinin with the cadherin/catenin cell-cell adhesion complex via alpha-catenin. 779 Mar 78

The elevation of tyrosine phosphorylation level is thought to induce the dysfunction of cadherin through the tyrosine phosphorylation of beta catenin. We evaluated this assumption using two cell lines. First, using temperature-sensitive v-src-transfected MDCK cells, we analyzed the modulation of cadherin-based cell adhesion by tyrosine phosphorylation. Cell aggregation and dissociation assays at nonpermissive and permissive temperatures indicated that elevation of the tyrosine phosphorylation does not totally affect the cell adhesion ability of cadherin but shifts it from a strong to a weak state. The tyrosine phosphorylation levels of beta catenin, ZO-1, ERM (ezrin/radixin/moesin), but not alpha catenin, vinculin, and alpha-actinin, were elevated in the weak state. To evaluate the involvement of the tyrosine phosphorylation of beta catenin in this shift of cadherin-based cell adhesion, we introduced v-src kinase into L fibroblasts expressing the cadherin-alpha catenin fusion protein, in which beta catenin is not involved in cell adhesion. The introduction of v-src kinase in these cells shifted their adhesion from a strong to a weak state. These findings indicated that the tyrosine phosphorylation of beta catenin is not required for the strong-to-weak state shift of cadherin-based cell adhesion, but that the tyrosine phosphorylation of other junctional proteins, ERM, ZO-1 or unidentified proteins is involved.
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PMID:V-src kinase shifts the cadherin-based cell adhesion from the strong to the weak state and beta catenin is not required for the shift. 855 50

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.
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PMID:Characterization of the interactions of alpha-catenin with alpha-actinin and beta-catenin/plakoglobin. 915 27

The integrity of the vascular endothelium is mainly dependent upon the organization of interendothelial adherens junctions (AJ). These junctions are formed by the homotypic interaction of a transmembrane protein, vascular endothelial cadherin (VE-cadherin), which is complexed to an intracellular protein network including alpha-, beta-, and gamma-catenin. Additional proteins such as vinculin and alpha-actinin have been suggested to link the VE-cadherin/catenin complex to the actin-based cytoskeleton. During the process of hematogenous metastasis, circulating tumor cells must disrupt these intercellular junctions in order to extravasate. In the present study, we have investigated the influence of tumor cell-endothelial cell interaction upon interendothelial AJ. We show that human breast adenocarcinoma cells (MCF-7), but not normal human mammary epithelial cells, induce a rapid endothelial cell (EC) dissociation which correlates with the loss of VE-cadherin expression at the site of tumor cell-EC contact and with profound changes in vinculin distribution and organization. This process could not be inhibited by metalloproteinase nor serine protease inhibitors. Immunoprecipitations and Western blot analysis demonstrate that the overall expression of VE-cadherin and vinculin as well as the composition of the VE-cadherin/catenins complex are not affected by tumor cells while the tyrosine phosphorylation status of proteins within the complex is significantly altered. Our data suggest that tumor cells modulate AJ protein distribution and phosphorylation in EC and may, thereby, facilitate EC dissociation.
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PMID:Alteration of interendothelial adherens junctions following tumor cell-endothelial cell interaction in vitro. 943 30

Alterations in the expression or function of molecules that affect cellular adhesion and proliferation are thought to be critical events for tumor progression. Loss of expression of the cell adhesion molecule E-cadherin and increased expression of the epidermal growth factor receptor are two prominent molecular events that are associated with tumorigenesis. The regulation of E-cadherin-dependent cell adhesion by epidermal growth factor (EGF) was therefore examined in the human breast cancer cell line, MDA-MB-468. In this study, changes were observed in the subcellular distribution of components that mediate the cytoplasmic connection between E-cadherin and the actin-based cytoskeleton in response to activation of the EGF receptor. Serum withdrawal activated E-cadherin-dependent cell-cell aggregation in MDA-MB-468 cells, and this treatment stimulated the interaction of actin, alpha-actinin, and vinculin with E-cadherin complexes, despite the absence of alpha-catenin in these cells. By contrast, the co-precipitation of actin with E-cadherin was not detected in several alpha-catenin positive epithelial cell lines. Treatment with EGF inhibited cellular aggregation but did not affect either the levels of E-cadherin or catenin expression nor the association of catenins (beta-catenin, plakoglobin/gamma-catenin, or p120(cas)) with E-cadherin. However, EGF treatment of the MDA-MB-468 cell line dissociated actin, alpha-actinin, and vinculin from the E-cadherin-catenin complex, and this coincided with a robust phosphorylation of beta-catenin, plakoglobin/gamma-catenin, and p120(cas) on tyrosine residues. Furthermore, inactivation of the EGF receptor in serum-treated MDA-MB-468 cells with either a function-blocking antibody or EGF receptor kinase inhibitors mimicked the effects of serum starvation by stimulating both cellular aggregation and assembly of E-cadherin complexes with vinculin and actin. These results demonstrate that the EGF receptor directly regulates cell-cell adhesion through modulation of the interaction of E-cadherin with the actin cytoskeleton and thus substantiates the coordinate role of both of these molecules in tumor progression and metastasis.
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PMID:The epidermal growth factor receptor modulates the interaction of E-cadherin with the actin cytoskeleton. 953 96

E-cadherin is the major cell-cell adhesion molecule expressed by epithelial cells. Cadherins form a complex with three cytoplasmic proteins, alpha-, beta-, and gamma-catenin, and the interaction between them is crucial for anchoring the actin cytoskeleton to the intercellular adherens junctions. The invasive behavior of cancer cells has been attributed to a dysfunction of these molecules. In this study, we examined the distribution of the cadherin-catenin complex in a Chinese human thyroid cancer cell line, CGTH W-2, compared with that in normal human thyroid epithelial cells. In the normal cells, using immunofluorescence staining, E-cadherin and alpha-, beta-, and gammm-catenin were found to be localized at the intercellular junction and appeared as 135, 102, 90, and 80 kD proteins on Western blots. In CGTH W-2 cells, no E-cadherin and gamma-catenin immunoreactivity was detected by immunofluorescence or Western blotting; alpha- and beta-catenin were detected as 102 and 90 kD proteins on blots but gave a diffuse cytoplasmic immunofluorescence staining pattern in most cells, while beta-catenin was also distributed throughout the cytoplasm in most cells but was found at the cell junction in some, where it colocalized with alpha-actinin. The present data indicate that the loss of cell adhesiveness in these cancer cells may be due to incomplete assembly of the cadherin-catenin complex at the cell junction. However, this defect did not affect the linkage of actin bundles to vinculin-enriched intercellular junctions.
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PMID:Distribution of the cadherin-catenin complex in normal human thyroid epithelium and a thyroid carcinoma cell line. 970 70

The interaction of cadherin-catenin complex with the actin-based cytoskeleton through alpha-catenin is indispensable for cadherin-based cell adhesion activity. We reported previously that E-cadherin-alpha-catenin fusion molecules showed cell adhesion and cytoskeleton binding activities when expressed in nonepithelial L cells. Here, we constructed deletion mutants of E-cadherin-alpha-catenin fusion molecules lacking various domains of alpha-catenin and introduced them into L cells. Detailed analysis identified three distinct functional domains of alpha-catenin: a vinculin/alpha-actinin-binding domain, a ZO-1-binding domain, and an adhesion-modulation domain. Furthermore, cell dissociation assay revealed that the fusion molecules containing the ZO-1-binding domain in addition to the adhesion-modulation domain conferred the strong state of cell adhesion activity on transfectants, although those lacking the ZO-1-binding domain conferred only the weak state. The disorganization of actin-based cytoskeleton by cytochalasin D treatment shifted the cadherin-based cell adhesion from the strong to the weak state. In the epithelial cells, where alpha-catenin was not precisely colocalized with ZO-1, the ZO-1-binding domain did not completely support the strong state of cell adhesion activity. Our studies showed that the interaction of alpha-catenin with the actin-based cytoskeleton through the ZO-1-binding domain is required for the strong state of E-cadherin-based cell adhesion activity.
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PMID:Functional domains of alpha-catenin required for the strong state of cadherin-based cell adhesion. 1008 72

N-cadherin is a member of the Ca(2+)-dependent cell adhesion molecules and plays an important role in the assembly of the adherens junction in chicken cardiomyocytes. In addition to being present at the cell-cell junction, N-cadherin is associated with costameres in extrajunctional regions. The significance of the N-cadherin-associated costameres and whether catenins are components of costameres in chicken cardiomyocytes are not known. In this study, double-labeling immunofluorescence microscopy was used to determine the extrajunctional distribution of both N-cadherin and its cytoplasmic associated proteins, alpha- and beta-catenins, and their relationship to myofibrillar Z-disc alpha-actinin. N-cadherin, alpha-, and beta-catenins were all found to be present at the extrajunctional region and, in some cases, were codistributed with myofibrillar alpha-actinin exhibiting a periodic staining pattern. Confocal microscopy confirmed that both N-cadherin and beta-catenin colocalized with peripheral myofibrillar alpha-actinin on the dorsal surface of cardiomyocytes as components of the costameres. Intracellular application of antibodies specific for the cytoplasmic portions of N-cadherin, alpha-, and beta-catenin, either by electroporation or microinjection, resulted in myofibril disorganization and disassembly. These results suggest the existence of N-cadherin/catenin-based costameres in the dorsal surface of cultured chicken cardiomyocytes in addition to the integrin/vinculin-based costameres found in the ventral surface and indicate that the former set of costameres is essential for cardiac myofibrillogenesis.
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PMID:N-cadherin/catenin-based costameres in cultured chicken cardiomyocytes. 1046 8

Microinjection of fluorophore-tagged cytoskeletal proteins has been a useful tool in studies of formation of focal adhesions (FA). We used this method to study the maintenance of adherens junctions (AJ) and tight junctions (TJ) of epithelial Madin-Darby bovine kidney cells. We chose alpha-actinin and vinculin as markers, because they are present both at adherens junctions and focal adhesions and their binding partners have been well characterized. Isolated FITC-labelled chicken alpha-actinin and vinculin were injected into confluent cells where they were rapidly incorporated both in FAs and AJs. The FAs remained unchanged, whereas cell-cell contacts began to fade within an hour after injection and the cells were joined to polykaryons having 5 to 13 nuclei. Short fragments of cell membranes containing injected proteins, actin, beta-catenin, cadherin, claudin, occludin and ZO-1 were visible inside the polykaryons indicating that both AJs and TJs were disintegrated as a single complex. Microinjected FITC-labelled vinculin head domain was also incorporated to both AJs and FAs, but instead of fusions it rapidly induced the detachment of the cells from the substratum probably due to high affinity of vinculin head to talin. Vinculin tail domain had no apparent effect on the cell morphology. Since small GTPases are involved in the building up of AJs, we injected active and inactive forms of cdc42 and rac proteins together with vinculin to see their effect. Active forms reduced the formation of polykaryons presumably by strengthening AJs, whereas inactive forms had no apparent effect. We suggest that excess alpha-actinin and vinculin uncouple the cell-cell adhesion junctions from the intracellular cytoskeleton which leads to fragmentation of junctional complexes and subsequent cell fusion. The results show that cell-cell adhesion sites are more dynamic and more sensitive than FAs to an imbalance in the amount of free alpha-actinin and intact vinculin.
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PMID:Role of vinculin in the maintenance of cell-cell contacts in kidney epithelial MDBK cells. 1115 87

Costameres, vinculin-containing structures found in skeletal and cardiac muscle, are thought to anchor the Z-discs of the peripheral myofibrils to the sarcolemma. Several lines of evidence indicate that two different sets of costameres, integrin- and N-cadherin-based, are present in cardiac muscles. In this study, immunoblot analysis was used to study the expression of N-cadherin, alpha-catenin, beta-catenin, vinculin, talin, and laminin in rat cardiac muscles at embryonic days 15 and 19, the day of birth (postnatal day 0), postnatal weeks 1, 2, 3, and 4, and in the adult. Double immunofluorescence microscopy was performed to study the spatial and temporal distribution of these two sets of costameres in rat cardiomyocytes. Costameric staining for N-cadherin, codistributed with beta-catenin, was strong from embryonic day 15 up to postnatal week 2, gradually decreased after postnatal week 3, and was undetectable at postnatal week 4 and in the adult. Confocal microscopy showed that N-cadherin colocalized with alpha-actinin at cortical myofibrils. Double-labeling of beta-catenin and talin indicated the coexistence of N-cadherin/catenin- and integrin/talin-based costameres in rat cardiac muscle. Although beta-catenin and vinculin were co-localized at the costamere of cardiomyocytes from embryonic day 15 to postnatal week 3, staining for beta-catenin or talin was mutually exclusive at all stages examined. These results demonstrate the simultaneous, but mutually exclusive, existence of N-cadherin/catenin- and integrin/talin-based costameres in rat cardiomyocytes between late embryonic stages and postnatal week 3, while only integrin/talin-based costameres were found in adult rats. The N-cadherin/catenin-based costameres in rat cardiac muscles may play a role in myofibrillogenesis similar to that of their counterparts in cultured cardiomyocytes.
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PMID:Role of N-cadherin- and integrin-based costameres in the development of rat cardiomyocytes. 1183 97


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