scholarly journals p120, a p120-related protein (p100), and the cadherin/catenin complex.

1995 ◽  
Vol 130 (2) ◽  
pp. 369-381 ◽  
Author(s):  
J M Staddon ◽  
C Smales ◽  
C Schulze ◽  
F S Esch ◽  
L L Rubin

Cadherins and catenins play an important role in cell-cell adhesion. Two of the catenins, beta and gamma, are members of a group of proteins that contains a repeating amino acid motif originally described for the Drosophila segment polarity gene armadillo. Another member of this group is a 120-kD protein termed p120, originally identified as a substrate of the tyrosine kinase pp60src. In this paper, we show that endothelial and epithelial cells express p120 and p100, a 100-kD, p120-related protein. Peptide sequencing of p100 establishes it as highly related to p120. p120 and p100 both appear associated with the cadherin/catenin complex, but independent p120/catenin and p100/catenin complexes can be isolated. This association is shown by coimmunoprecipitation of cadherins and catenins with an anti-p120/p100 antibody, and of p120/p100 with cadherin or catenin antibodies. Immunocytochemical analysis with a p120-specific antibody reveals junctional colocalization of p120 and beta-catenin in epithelial cells. Catenins and p120/p100 also colocalize in endothelial and epithelial cells in culture and in tissue sections. The cellular content of p120/p100 and beta-catenin is similar in MDCK cells, but only approximately 20% of the p120/p100 pool associates with the cadherin/catenin complex. Our data provide further evidence for interactions among the different arm proteins and suggest that p120/p100 may participate in regulating the function of cadherins and, thereby, other processes influenced by cell-cell adhesion.

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.


2000 ◽  
Vol 113 (8) ◽  
pp. 1319-1334 ◽  
Author(s):  
P.Z. Anastasiadis ◽  
A.B. Reynolds

p120 catenin (p120) is the prototypic member of a growing subfamily of Armadillo-domain proteins found at cell-cell junctions and in nuclei. In contrast to the functions of the classical catenins (alpha-catenin, beta-catenin, and gamma-catenin/plakoglobin), which have been studied extensively, the first clues to p120's biological function have only recently emerged, and its role remains controversial. Nonetheless, it is now clear that p120 affects cell-cell adhesion through its interaction with the highly conserved juxtamembrane domain of classical cadherins, and is likely to have additional roles in the nucleus. Here, we summarize the data on the potential involvement of p120 both in promotion of and in prevension of adhesion, and propose models that attempt to reconcile some of the disparities in the literature. We also discuss the structural relationships and functions of several known p120 family members, as well as the potential roles of p120 in signaling and cancer.


2006 ◽  
Vol 17 (8) ◽  
pp. 3345-3355 ◽  
Author(s):  
Maya Elbert ◽  
David Cohen ◽  
Anne Müsch

Mammalian Par1 is a family of serine/threonine kinases comprised of four homologous isoforms that have been associated with tumor suppression and differentiation of epithelial and neuronal cells, yet little is known about their cellular functions. In polarizing kidney epithelial (Madin-Darby canine kidney [MDCK]) cells, the Par1 isoform Par1b/MARK2/EMK1 promotes the E-cadherin–dependent compaction, columnarization, and cytoskeletal organization characteristic of differentiated columnar epithelia. Here, we identify two functions of Par1b that likely contribute to its role as a tumor suppressor in epithelial cells. 1) The kinase promotes cell–cell adhesion and resistance of E-cadherin to extraction by nonionic detergents, a measure for the association of the E-cadherin cytoplasmic domain with the actin cytoskeleton, which is critical for E-cadherin function. 2) Par1b attenuates the effect of Dishevelled (Dvl) expression, an inducer of wnt signaling that causes transformation of epithelial cells. Although Dvl is a known Par1 substrate in vitro, we determined, after mapping the PAR1b-phosphorylation sites in Dvl, that PAR1b did not antagonize Dvl signaling by phosphorylating the wnt-signaling molecule. Instead, our data suggest that both proteins function antagonistically to regulate the assembly of functional E-cadherin–dependent adhesion complexes.


Development ◽  
1993 ◽  
Vol 118 (4) ◽  
pp. 1191-1207 ◽  
Author(s):  
M. Peifer ◽  
S. Orsulic ◽  
D. Sweeton ◽  
E. Wieschaus

The epithelial sheet is a structural unit common to many tissues. Its organization appears to depend on the function of the multi-protein complexes that form adherens junctions. Elegant cell biological experiments have provided support for hypotheses explaining the function of adherens junctions and of their components. These systems, however, lack the ability to test function within an entire organism during development. The realization that the product of the Drosophila segment polarity gene armadillo is related to the vertebrate adhesive junction components plakoglobin and beta-catenin led to the suggestion that armadillo might provide a genetic handle to study adhesive junction structure and function. An examination of the potential function of Armadillo in cell-cell adhesive junctions was initiated using the Drosophila ovary as the model system. We examined the distribution of Armadillo in the Drosophila ovary and demonstrated that this localization often parallels the location of cell-cell adhesive junctions. The consequences of removing armadillo function from the germ-line cells of the ovary were also examined. Germ-line armadillo mutations appear to disrupt processes requiring cell adhesion and integrity of the actin cytoskeleton, consistent with a role for Armadillo in cell-cell adhesive junctions. We have also used armadillo mutations to examine the effects on ovarian development of altering the stereotyped cell arrangements of the ovary. The implications of these results for the role of adhesive junctions during development are discussed.


2003 ◽  
Vol 14 (5) ◽  
pp. 1964-1977 ◽  
Author(s):  
Mauro Cozzolino ◽  
Venturina Stagni ◽  
Laura Spinardi ◽  
Nadia Campioni ◽  
Carla Fiorentini ◽  
...  

Cadherin-mediated cell–cell adhesion is dynamically modulated during epithelial–mesenchymal transition triggered by activation of receptor tyrosine kinases (RTK) in epithelial cells. Several cadherin-binding proteins have been identified that control cell–cell adhesion. However, the mechanisms by which intercellular adhesion and cell motility are coregulated are still unknown. Here, we delineate a hitherto uncharted cooperation between RTKs, RhoA GTPase, and p120 catenin in instructing a motile behavior to epithelial cells. We found that expression of an N-terminus–deleted p120 catenin in a variety of epithelial cell types, including primary keratinocytes, effectively competes for endogenous p120 at cadherin binding sites and abrogates EGF-stimulated cell motility as well as HGF-induced cell scattering. The deleted mutant also inhibits the PI3K-dependent RhoA activation ensuing receptor activation. Conversely, we also show that the ectopic expression of full-length p120 in epithelial cells promotes cytoskeletal changes, stimulates cell motility, and activates RhoA. Both motogenic response to p120 and RhoA activation require coactivation of signaling downstream of RTKs as they are suppressed by ablation of the Ras/PI3K pathway. These studies demonstrate that p120 catenin is a necessary target of RTKs in regulating cell motility and help define a novel pathway leading to RhoA activation, which may contribute to the early steps of metastatic invasion.


Development ◽  
1989 ◽  
Vol 105 (2) ◽  
pp. 263-270 ◽  
Author(s):  
Y. Hirai ◽  
A. Nose ◽  
S. Kobayashi ◽  
M. Takeichi

The role of Ca2+-dependent cell-cell adhesion molecules, E- and P-cadherins, in the histogenesis of mouse embryonic lung was studied. All epithelial cells of the lung express both E- and P-cadherin at the early developmental stage. P-cadherin, however, gradually disappears during development, initially from the main bronchi and eventually from all epithelial cells. When a monoclonal antibody to E-cadherin (ECCD-1) was added to monolayer cultures of lung epithelial cells, it induced a partial disruption of their cell-cell adhesion, while a monoclonal antibody to P-cadherin (PCD-1) showed a subtle effect. A mixture of the two antibodies, however, displayed a synergistic effect. We then tested the effect of the antibodies on the morphogenesis of lung primordia using an organ culture system. In control media, the explants formed typical bronchial trees. In the presence of ECCD-1, the explants grew up at the same rate as in the control, but their morphogenesis was affected. The control explants formed round epithelial lobules with an open luminal space at the tips of the bronchial trees, whereas the lobules of explants incubated with ECCD-1 tended to be flat and devoid of the luminal space. PCD-1 showed a similar but very small effect. A mixture of the two antibodies, however, showed a stronger effect: the branching of epithelia was partially suppressed and the arrangement of epithelial cells was distorted in many places. These results suggest that E- and P-cadherin have a synergistic role in the organization of epithelial cells in lung morphogenesis.


Development ◽  
1993 ◽  
Vol 118 (2) ◽  
pp. 629-640 ◽  
Author(s):  
S. Schneider ◽  
K. Herrenknecht ◽  
S. Butz ◽  
R. Kemler ◽  
P. Hausen

In the course of an analysis of cell-cell adhesion in the Xenopus embryo, antibodies directed against alpha- and beta-catenin were applied to investigate their relation to the cadherins occurring early in this system. The results demonstrate that alpha- and beta-catenin are provided maternally and increase in amount throughout embryogenesis. Immunoprecipitations indicate that both of the catenins are complexed to U-cadherin in the early phase of embryogenesis and to E-cadherin, when it appears during gastrulation. An excess of alpha-catenin occurs in free form in the early embryo, whereas all of the beta-catenin seems to be complexed to cadherin. Synthesis of the two components throughout early embryogenesis and their binding to newly synthesized cadherins were demonstrated by metabolic labelling. The spatial distribution of alpha-catenin was analysed by immunohistology. During cleavage alpha-catenin is deposited evenly along the plasma membranes within the embryo, while the cell peripheries at the surface of the embryo remain devoid of alpha-catenin. At later stages, the pattern of alpha-catenin distribution becomes more complex. Quantitative differences in the intensity of staining along the plasma membranes in the different regions of the embryo can be distinguished. Particularly the appearance of E-cadherin in the gastrula ectoderm is accompanied by conspicuous depositions of alpha-catenin along the respective plasma membranes in this layer. All cells in the later embryo, apart from the neural crest cells, carry alpha-catenin on their plasma membranes indicating the universal character of cadherin-mediated cell-cell adhesion in the Xenopus embryo.


1995 ◽  
Vol 269 (6) ◽  
pp. C1433-C1449 ◽  
Author(s):  
P. A. Piepenhagen ◽  
W. J. Nelson

Structural and functional differences among epithelial cells of kidney nephrons may be regulated by variations in cell-to-cell (cell-cell) and cell-to-substratum (cell-substratum) junctions. Using immunofluorescence microscopy, we demonstrate that the cadherin-associated proteins alpha- and beta-catenin are localized to basolateral membranes of cells in all nephron segments, whereas plakoglobin, a protein associated with both classical and desmosomal cadherins, is localized to noninterdigitated lateral membranes in the distal half of the nephron where it colocalizes with desmoplakin and cytokeratin K8. Plakoglobin is also present in capillary endothelial cells where staining for the other catenins and desmosomal proteins is not observed. Immunofluorescence for laminin A and alpha 6-integrin, proteins that mediate cell-substratum contacts, reveal no correlations with the other staining patterns observed. These data indicate that plakoglobin and beta-catenin subserve distinct functions in cell-cell adhesion and suggest that E-cadherin-mediated contacts generate a basal level of cell-cell adhesion, whereas desmosomal junctions provide additional strength to cell-cell contacts in the distal nephron.


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