Echinoid Is a Component of Adherens Junctions That Cooperates with DE-Cadherin to Mediate Cell Adhesion

Abstract

Echinoid is an immunoglobulin domain-containing transmembrane protein that modulates cell-cell signaling by Notch and the EGF receptors. We show that, in the Drosophila wing disc epithelium, Echinoid is a component of adherens junctions that cooperates with DE-Cadherin in cell adhesion. Echinoid and beta-catenin (a DE-Cadherin interacting protein) each possess a C-terminal PDZ domain binding motif that binds to Bazooka/PAR-3; these motifs redundantly position Bazooka to adherens junctions. Echinoid also links to actin filaments by binding to Canoe/AF-6/afadin. Moreover, interfaces between Echinoid- and Echinoid+ cells, like those between DE-Cadherin- and DE-Cadherin+ cells, are deficient in adherens junctions and form actin cables. These characteristics probably facilitate the strong sorting behavior of cells that lack either of these cell-adhesion molecules. Finally, cells lacking either Echinoid or DE-Cadherin accumulate a high density of the reciprocal protein, further suggesting that Echinoid and DE-Cadherin play similar and complementary roles in cell adhesion.

Localization and requirement for Myosin II at the dorsal‐ventral compartment boundary of the Drosophila wing

“…Asymmetric and complementary distributions of Myosin II and Baz have not been reported previously in the context of normal wing development, but have been described in association with clones of cells mutant for the transmembrane immunoglobulin domain encoding gene echinoid (Wei et al, 2005;Laplante and Nilson, 2006). Echinoid protein (Ed) localizes to the adherens junction in wing imaginal disc cells, can bind to Baz, and appears to act as a cell adhesion molecule (Wei et al, 2005).…”

“…Recent studies have revealed that in certain contexts, Myosin II and Par-3 exhibit asymmetric and complementary distributions (Zallen and Wieschaus, 2004;Wei et al, 2005). Par-3 is encoded in Drosophila by the bazooka gene (baz).…”

“…Echinoid protein (Ed) localizes to the adherens junction in wing imaginal disc cells, can bind to Baz, and appears to act as a cell adhesion molecule (Wei et al, 2005). Ed has also been linked to Notch signaling (Ahmed et al, 2003;Escudero et al, 2003;Rawlins et al, 2003).…”

“…Ed has also been linked to Notch signaling (Ahmed et al, 2003;Escudero et al, 2003;Rawlins et al, 2003). ed mutant clones in the wing are ringed by an F-actin cable that is also associated with elevated staining for Myosin II and decreased staining for Baz (Wei et al, 2005). These observations prompted us to investigate whether Ed protein localization is modulated with respect to the D-V compartment boundary.…”

β-Catenin regulates excitatory postsynaptic strength at hippocampal synapses

“…Our attempts to determine the contribution of Velis and S-SCAM in ␤-catenin-dependent regulation of synaptic AMPARs were inconclusive, and Par-3, whose binding to ␤-catenin has been recently reported (40), or additional as yet to be identified ␤-catenin-interacting PDZ proteins could provide a link to the AMPAR modification. Other non-PDZ interactions of ␤-catenin could also play a role.…”