Celladhesion

Cell adhesion is the process by which cells attach to one another and to the extracellular matrix (ECM) through specialized cell adhesion molecules (CAMs). This adhesion is essential for tissue structure, development, wound healing, and the maintenance of tissue homeostasis. Adhesion is dynamic and regulated by calcium levels, mechanical forces, and intracellular signaling.

Cell-cell adhesion is mediated primarily by cadherins, which form homophilic interactions in adherens junctions and desmosomes and are linked to the actin cytoskeleton or intermediate filaments via catenins and other adaptor proteins. Other cell-cell CAMs include members of the immunoglobulin superfamily and selectins, the latter involved in transient leukocyte-endothelium interactions during immune surveillance.

Cell-ECM adhesion is mediated mainly by integrins, heterodimeric receptors that bind ECM proteins such as collagen, laminin, and fibronectin. Integrins connect to the actin cytoskeleton through adaptor proteins like talin and vinculin and initiate intracellular signaling cascades, including focal adhesion kinase (FAK) and Src family kinases, which regulate cytoskeletal organization, cell survival, and gene expression.

Adhesion complexes include adherens junctions and desmosomes (cell-cell), focal adhesions and hemidesmosomes (cell-ECM). These structures coordinate mechanical strength with signal transduction, supporting processes such as morphogenesis, tissue remodeling, and responses to injury.

In physiology and disease, cell adhesion influences development, wound healing, and immune function. It also affects cancer progression, where loss or alteration of adhesion molecules like E-cadherin can promote invasion and metastasis. Studying adhesion involves microscopy, biochemistry of CAMs, and genetic or pharmacological disruption of adhesion pathways.