heterophilic cell-cell adhesion via plasma membrane cell adhesion molecules

Definition

Target type: biologicalprocess

The attachment of an adhesion molecule in one cell to a nonidentical adhesion molecule in an adjacent cell. [ISBN:0198506732]

Heterophilic cell-cell adhesion, mediated by plasma membrane cell adhesion molecules (CAMs), is a crucial process in multicellular organisms, enabling cells to interact and form tissues, organs, and maintain tissue integrity. It involves the binding of different types of CAMs on the surfaces of two distinct cells, facilitated by non-identical binding partners. This intricate process is essential for diverse biological functions, including:

* **Development and morphogenesis**: During embryonic development, heterophilic adhesion plays a critical role in cell sorting, migration, and the formation of tissues and organs. Cells expressing specific CAMs adhere to and interact with other cells expressing complementary CAMs, leading to the precise organization and assembly of tissues.

* **Tissue homeostasis**: In adult organisms, heterophilic adhesion is crucial for maintaining tissue integrity and function. It provides the adhesive forces that hold cells together, preventing cell dissociation and maintaining tissue structure. Additionally, it contributes to cell signaling and the regulation of cell behavior.

* **Immune responses**: Heterophilic adhesion plays a role in immune cell interactions and the regulation of immune responses. Immune cells express specific CAMs that enable them to adhere to other cells, such as endothelial cells, leukocytes, and antigen-presenting cells. This adhesion facilitates communication and the activation of immune responses.

* **Wound healing**: During wound healing, heterophilic adhesion is essential for the migration and adhesion of cells to the wound site, promoting tissue repair.

The mechanisms underlying heterophilic cell-cell adhesion via CAMs are complex and involve multiple steps:

1. **CAM expression and localization**: Cells express specific types of CAMs on their plasma membrane, often in a polarized manner. This controlled expression and localization ensure that cells adhere to appropriate partners.

2. **Ligand binding**: CAMs from different cells interact via their extracellular domains. This interaction is typically specific, with CAMs binding to complementary ligands on opposing cells.

3. **Transmembrane signaling**: Binding of CAMs to their ligands triggers intracellular signaling cascades that regulate cell behavior, including adhesion, migration, and gene expression.

4. **Cytoskeletal interactions**: CAMs often interact with the cytoskeleton, providing structural support and facilitating the transmission of forces across cell junctions.

**Examples of heterophilic CAMs**:

* **Cadherins**: A large family of calcium-dependent CAMs that mediate cell-cell adhesion in a variety of tissues. Different cadherins exhibit differential binding affinities, enabling cells to sort and assemble into specific tissues.

* **Immunoglobulin superfamily (IgSF) CAMs**: A diverse family of CAMs that share immunoglobulin-like domains in their extracellular regions. IgSF CAMs are involved in various cellular functions, including adhesion, signaling, and immune responses.

* **Selectins**: A family of carbohydrate-binding CAMs that mediate cell-cell adhesion in various contexts, including leukocyte trafficking and immune responses.

* **Integrins**: Transmembrane receptors that link the extracellular matrix to the cytoskeleton. While integrins primarily mediate cell-matrix adhesion, they can also participate in heterophilic cell-cell interactions.

Heterophilic cell-cell adhesion via CAMs is a highly dynamic process that is regulated by numerous factors, including:

* **Cell type**: Different cell types express different CAMs, determining their adhesive properties and interactions.

* **Extracellular environment**: Factors such as the composition of the extracellular matrix, soluble factors, and mechanical cues can influence CAM expression and function, regulating cell-cell adhesion.

* **Developmental stage**: CAM expression and function can change during development, leading to tissue remodeling and organogenesis.

Understanding the mechanisms of heterophilic cell-cell adhesion is crucial for understanding various biological processes, including development, tissue homeostasis, immune responses, and disease. Dysregulation of heterophilic adhesion can contribute to various diseases, including cancer, autoimmune disorders, and developmental defects. Research efforts continue to unravel the intricate mechanisms of heterophilic adhesion and its role in normal and pathological conditions.'
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