Adherens Junctions

Abstract

Adherens junctions (AJs) are dynamic structures found in between cells that couple intercellular adhesion to the cytoskeleton thereby creating a transcellular network that coordinates the behaviour of a population of cells. Regulation of AJ formation and maintenance is crucial for cell shape, migration, morphogenesis and tissue homeostasis and repair. AJs not only regulate cell adhesion and cell shape but also form spatial landmarks for a variety of signalling complexes, thereby regulating other cellular functions next to adhesion.

Key concept:

• AJs are essential for tissue integrity by coupling intercellular adhesion to the cytoskeleton.

• AJ formation and maintenance requires the cooperative activity of two types of intercellular adhesive receptor complexes, the classical cadherin/catenin and nectin/afadin complexes.

• Catenins provide cadherin-mediated adhesion with a dynamic link to the cytoskeleton, regulate cadherin cell surface stability and couple AJs with signal pathways that regulate gene expression.

• Cadherin-mediated adhesion and the AJs proteins β-catenin and p120ctn regulate the Wnt pathway important for cell fate and differentiation decisions.

• AJs serve as spatially defined signal platforms by recruiting a range of signal transduction proteins. This is not only important for regulation of intercellular adhesive interactions and AJ stability but also allows for communication of cell surface changes to the nucleus.

• The formation, maintenance and disassembly of AJs are regulated at different levels that involve rapid changes as well as indirect mechanisms that regulate gene expression.

• The establishment of polarity is closely coupled to the formation of AJs.

• Classical cadherins are essential for the formation of not only AJs but also desmosomes and tight junctions.

• Alterations in AJ components directly contribute to human diseases, such as cancer and developmentally related syndromes.

• AJs and human disease.