1.17.3 Cell Cell Adhesion Definition

Cell Cell Adhesion Definition is a description of the physical attachment established between the surfaces of two adjacent cells through direct binding interactions between adhesion molecules present on each cell's surface, forming a specific category of cell adhesion distinguished from cell-matrix adhesion by the fact that the attachment connects one cell directly to another rather than to the surrounding extracellular matrix.

Conceptual Basis

Direct Attachment Between Adjacent Cells

Cell-cell adhesion is defined by the direct physical engagement occurring between corresponding adhesion molecules positioned on the surfaces of two neighboring cells, establishing a binding interaction that spans the narrow space separating the two cell surfaces and physically links them together.

Distinguished From Cell-Matrix Adhesion

Cell-cell adhesion is distinguished from cell-matrix adhesion specifically by the identity of the binding partner involved: cell-cell adhesion connects a cell to another cell, whereas cell-matrix adhesion connects a cell to the structural molecules of the surrounding extracellular matrix rather than to a neighboring cell.

Structural Organization

Adhesive Junctions

Cell-cell adhesion is commonly organized into specialized structures termed adhesive junctions, discrete regions of the cell surface at which adhesion molecules and their associated intracellular components are concentrated, forming a structurally reinforced point of attachment between the two adjoining cells rather than a diffuse attachment distributed uniformly across the entire cell surface.

Coupling to the Intracellular Cytoskeleton

Cell-cell adhesion molecules are frequently linked, through intracellular adaptor proteins, to the internal cytoskeletal framework of the cell, mechanically coupling the adhesive contact at the cell surface to the internal structural network of the cell and thereby distributing mechanical forces experienced at the adhesive junction throughout the broader cell body.

Functional Roles

Establishing and Maintaining Tissue Architecture

Cell-cell adhesion provides the physical basis through which individual cells are held together in the specific spatial arrangement characteristic of a given tissue, contributing directly to the overall structural organization and mechanical integrity of that tissue.

Restraining Cell Movement

Because cell-cell adhesion physically anchors a cell to its neighbors, strong and stable cell-cell adhesive contacts normally restrain the capacity of an individual cell to detach from its surrounding cells and move independently, contributing to the stationary, tissue-integrated behavior characteristic of normal, non-migratory cells.

Generating Adhesion-Dependent Signaling

Cell-cell adhesion contacts commonly generate intracellular signals as a direct consequence of the physical engagement between the adhesion molecules of the two adjoining cells, influencing downstream processes including proliferation and survival in a manner dependent on the cell's ongoing state of contact with its neighbors.

Relationship to Broader Cell Adhesion and Cancer Cell Biology

One of the Two Principal Categories of Cell Adhesion

Cell-cell adhesion constitutes one of the two principal categories comprising the broader concept of cell adhesion, complementing cell-matrix adhesion as the two fundamental ways in which cells establish physical attachment within a tissue.

Consequences of Reduced Cell-Cell Adhesion in Cancer Cells

Because cell-cell adhesion normally restrains cell movement and maintains tissue integration, reduced cell-cell adhesion is closely associated with the capacity of cancer cells to detach from their surrounding tissue and behave in a more independent, mobile manner, positioning altered cell-cell adhesion as a significant contributor to the invasive and disseminated behavior characteristic of cancer cell adhesion.