Characterization of the interactions of alpha-catenin with alpha-actinin and beta-catenin/plakoglobin

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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Wnt-1 modulates cell-cell adhesion in mammalian cells by stabilizing beta-catenin binding to the cell adhesion protein cadherin

The Journal of Cell Biology ◽

10.1083/jcb.124.5.729 ◽

1994 ◽

Vol 124 (5) ◽

pp. 729-741 ◽

Cited By ~ 260

Author(s):

L Hinck ◽

WJ Nelson ◽

J Papkoff

Keyword(s):

Cell Adhesion ◽

Mammalian Cells ◽

Signal Transduction Pathway ◽

Beta Catenin ◽

Adhesion Protein ◽

Calcium Dependent ◽

Cell Adhesion Protein ◽

Segment Polarity ◽

Dependent Cell ◽

Cell Cell

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.

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Plakoglobin, or an 83-kD homologue distinct from beta-catenin, interacts with E-cadherin and N-cadherin.

The Journal of Cell Biology ◽

10.1083/jcb.118.3.671 ◽

1992 ◽

Vol 118 (3) ◽

pp. 671-679 ◽

Cited By ~ 158

Author(s):

K A Knudsen ◽

M J Wheelock

Keyword(s):

Cell Adhesion ◽

Cell Surface ◽

Molecular Mass ◽

Beta Catenin ◽

Calcium Dependent ◽

Intracellular Proteins ◽

Dependent Cell ◽

Cell Surface Glycoproteins ◽

E Cadherin ◽

Cell Cell

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.

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