Adherens junction

Cell–cell junctions that connect the actin cytoskeleton of adjacent cells

Adherens junctions are a type of cell junction that play a crucial role in maintaining the structural integrity of tissues by connecting the actin cytoskeleton of adjacent cells. These junctions are essential for the formation and maintenance of tissues and are involved in various cellular processes, including cell signaling, cell adhesion, and tissue morphogenesis.

Structure

Adherens junctions are composed of cadherins, which are transmembrane proteins that mediate cell-cell adhesion. The extracellular domains of cadherins from adjacent cells interact in a calcium-dependent manner, forming a strong adhesive bond. The intracellular domains of cadherins are linked to the actin cytoskeleton through a complex of proteins, including catenins such as _-catenin, _-catenin, and p120-catenin.

Cadherins

Cadherins are a family of transmembrane proteins that are critical for the function of adherens junctions. They are characterized by their ability to bind calcium ions, which is necessary for their adhesive function. Different types of cadherins, such as E-cadherin, N-cadherin, and P-cadherin, are expressed in different tissues and contribute to tissue-specific adhesion properties.

Catenins

Catenins are cytoplasmic proteins that link cadherins to the actin cytoskeleton. _-catenin binds directly to the cytoplasmic domain of cadherins, while _-catenin connects _-catenin to actin filaments. p120-catenin regulates the stability and turnover of cadherins at the cell membrane.

Function

Adherens junctions are involved in several key functions:

• Cell adhesion: They provide strong adhesive contacts between cells, which is essential for the maintenance of tissue architecture.
• Signal transduction: Adherens junctions participate in signaling pathways that regulate cell behavior, including cell proliferation, differentiation, and migration.
• Tissue morphogenesis: During development, adherens junctions play a role in the shaping and organization of tissues by coordinating cell movements and rearrangements.

Role in Disease

Dysfunction of adherens junctions is implicated in various diseases, including cancer. Loss of E-cadherin function, for example, is associated with increased tumor invasiveness and metastasis. Additionally, mutations in catenin genes can lead to developmental disorders and contribute to the progression of certain cancers.

Related pages

• Tight junction
• Desmosome
• Gap junction
• Cell adhesion

Gallery

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  Diagram of adherens junctions showing structural proteins