Vinculin Is Part of the Cadherin–Catenin Junctional Complex: Complex Formation between α-Catenin and Vinculin

Abstract

In epithelial cells, α-, β-, and γ-catenin are involved in linking the peripheral microfilament belt to the transmembrane protein E-cadherin. α-Catenin exhibits sequence homologies over three regions to vinculin, another adherens junction protein. While vinculin is found in cell–matrix and cell–cell contacts, α-catenin is restricted to the latter. To elucidate, whether vinculin is part of the cell–cell junctional complex, we investigated complex formation and intracellular targeting of vinculin and α-catenin. We show that α-catenin colocalizes at cell–cell contacts with endogenous vinculin and also with the transfected vinculin head domain forming immunoprecipitable complexes. In vitro, the vinculin NH2-terminal head binds to α-catenin, as seen by immunoprecipitation, dot overlay, cosedimentation, and surface plasmon resonance measurements. The K d of the complex was determined to 2–4 × 10−7 M. As seen by overlays and affinity mass spectrometry, the COOH-terminal region of α-catenin is involved in this interaction.Complex formation of vinculin and α-catenin was challenged in transfected cells. In PtK2 cells, intact α-catenin and α-catenin1-670, harboring the β-catenin– binding site, were directed to cell–cell contacts. In contrast, α-catenin697–906 fragments were recruited to cell–cell contacts, focal adhesions, and stress fibers. Our results imply that in vivo α-catenin, like vinculin, is tightly regulated in its ligand binding activity.

Changing Roles of Cadherins and Catenins during Progression of Squamous Intraepithelial Lesions in the Uterine Cervix

“…The latter possibility was shown for some tumor cells by Hazan et al, 37 and more recently it was shown that vinculin can form a complex with ␣-catenin and thereby participate in the formation of adherens junctions. 52 However, we did not find any evidence for this in our in vitro cultures, because no vinculin was coimmunoprecipitated with E-cadherin (data not shown). Whether the absence of ␣-catenin was caused by inactivating mutations in SIL cells remains to be investigated.…”

Different behavior of l-Afadin and Neurabin-II during the formation and destruction of cell – cell adherens junction

“…Of these proteins, a-catenin interacts with F-actin (Rimm et al, 1995). a-Catenin moreover interacts with a-actinin and vinculin, other F-actinbinding proteins (Knudsen et al, 1995;Weiss et al, 1998). In epithelial cells, cadherin is concentrated at ZA but also distributed along the entire lateral membrane (Nelson et al, 1990).…”

Small Rho GTPase-mediated actin dynamics at endothelial adherens junctions

“…4 Although the cadherin-catenin complex is commonly described as the 'core' VE-cadherin complex, many other proteins can associate, such as scaffolding proteins and cytoskeletal regulators. 3,5 Some of these proteins, including vinculin, [6][7][8][9][10][11] epithelial protein lost in neoplasm (EPLIN) 12,13 a-actinin 14 and afadin, 15,16 have been found to bind to both a-catenin and actin and are therefore suggested to act as a link between the cadherin-catenin complex and actin. However, biochemical studies showed that a minimal cadherin-catenin complex consisting of E-cadherin, b-catenin and aE-catenin can directly bind to filamentous actin (F-actin).…”