What Is Cell Adhesion?

Cell adhesion molecule (CAM) is a collective name for many molecules that mediate contact and binding between cells or between cells and extracellular matrix (ECM). Adhesion molecules work in the form of receptor-ligand binding, allowing cell-to-cell, cell-to-matrix, or cell-to-matrix-to-cell adhesion to participate in cell recognition, cell activation, and signal transduction. Cell proliferation and differentiation, and cell extension and movement, are the molecular basis for a series of important physiological and pathological processes such as immune response, inflammation, coagulation, tumor metastasis, and wound healing.

Cell adhesion molecule (CAM) is a collective name for many molecules that mediate contact and binding between cells or between cells and extracellular matrix (ECM). Adhesion molecules work in the form of receptor-ligand binding, allowing cell-to-cell, cell-to-matrix, or cell-to-matrix-to-cell adhesion to participate in cell recognition, cell activation, and signal transduction. Cell proliferation and differentiation, and cell extension and movement, are the molecular basis for a series of important physiological and pathological processes such as immune response, inflammation, coagulation, tumor metastasis, and wound healing.

Chinese name

Cell adhesion molecule

Foreign name

cell adhesion molecule

Abbreviation

CAM

Attributes

molecule

Classification of cell adhesion molecules

Adhesion molecules can be divided into integrin family, selectin family, immunoglobulin super family, and cadherin family according to their structural characteristics. In addition, there are some adhesion molecules that have not yet been classified.

(1) Integrin family

The integrin family is a heterodimer composed of two chains (or subunits) connected by non-covalent bonds. There are at least 14 -subunits and 8 -subunits, so there are many molecules. The -subunits can be used to divide the integrin family into 8 groups. Tissues are widely distributed. One type of integrin can be distributed in many cells, and the same type of cell often has multiple expressions of integrin. The expression of certain integrins is significantly cell-type specific. The expression level of integrin molecules can change with cell differentiation and growth status.

(2) IgSF superfamily (IgSF)

In the immune system, as well as in the nervous system and other biological systems, many molecules involved in antigen recognition or cell-to-cell interaction have similar structural characteristics to Ig, that is, they have one or more IgV-like or C-like domains. These diverse, widely distributed molecules with diverse recognition functions are called immunoglobulin superfamily. Most of the ligands recognized by IgSF in adhesion molecules are IgSF molecules and integrin family members.

(3) Selectin family

Selectin is a type I membrane molecule. Its extracellular membrane lectin (CL) domain can bind to certain carbohydrates and is the site of selectin binding ligands. Selectins recognize some oligosaccharide groups, mainly sialylated Lewis oligosaccharides (sialyl Lweis, sLe or CD15 _s ) or similar structural molecules. The selectin family includes three members, L-selectin (CD62L), P-selectin (CD62P), and E-selectin (CD62E), which are mainly expressed on the surface of leukocytes, endothelial cells, and certain tumor cells.

(4) Cadherin family

Cadherin is a family of calcium-dependent adhesion molecules. Cadherin plays an important role in maintaining the formation of solid tissues and selectively accumulating and rearranging cells during growth and development. Cadherin is a type I membrane molecule. E-cadherin, N-cadherin and P-cadherin are closely related to immunology.

(5) Other adhesion molecules

Such as peripheral lymph node addressin (PNAd), skin lymphocyte-associated antigen (CLA) and CD44.

Cell Adhesion Molecules Function

Adhesion molecules are involved in many important physiological functions and pathological processes of the body, such as:

(1) Transmission of auxiliary activation signals in mutual recognition of immune cells

When immune cells are stimulated by antigens, they must also have auxiliary receptors to receive auxiliary activation signals in order to be activated. There are many types of helper receptors. The most common are adhesion molecules on T cells and corresponding adhesion molecules on antigen-presenting cells: CD4 / MH type II molecules, CD8 / MHC type I molecules, CD28 / CD80 and CD86, CD2 / CD58, LFA-1 / ICAM-1, etc. While T cells recognize the antigen, if the co-stimulatory signal provided by CD80 (or CD86) is absent, the response of the T cells is in a state of incompetence.

(2) Mediate the adhesion of leukocytes and vascular endothelial cells during inflammation

The expression levels and binding affinity of specific adhesion molecules and their corresponding ligands are important molecular foundations in the development of different types of inflammation.

(3) Lymphocyte homing

Lymphocyte homing is the directed swimming of lymphocytes. Its molecular basis is the interaction between an adhesion molecule called a lymphocyte homing receptor and an adhesion molecule called an addressin on endothelial cells. [1]

Cell adhesion molecules and cell adhesion molecule related diseases and research

(1) Atherosclerosis (athero-sclerosis, As)

Monocytes adhere to vascular endothelial cells and migrate into endothelial cells to take up lipids and transform them into foam cells, which are early events of atherosclerosis. Cell adhesion molecules play an important role in mediating monocyte-endothelial cell adhesion. Intercellular adhesion molecule-1, vascular cell adhesion molecule-1, E-selectin and P-selectin have been demonstrated to be expressed in endothelial cells, smooth muscle cells and macrophages in human atherosclerotic plaque lesions It was found that the expression of these cell adhesion molecules is related to the infiltration of inflammatory cells such as macrophages in diseased tissues. [2] The high expression of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 in endothelial cells, smooth muscle cells and macrophages may be involved in some aspects of the development of atherosclerosis. The expression of tumor necrosis factor alpha is related to the expression of intercellular adhesion molecule 1 and vascular cell adhesion molecule 1 and the degree of atherosclerotic lesions. [3]

(2) Tumor

Cell adhesion molecules, as a class of cell surface transmembrane glycoproteins, are highly valued for their relationship with tumorigenesis, invasion, and metastasis. The adhesion molecule E-cadherin and its related protein -loop The expression of -catenin and epithelial cell adhesion molecule (EP-CAM) in breast cancer, laryngeal cancer, esophageal cancer and other tumors and their clinical significance are known. [4]

(3) Related research in nerve cells

Neural cell adhesion molecules (NCAMs) belong to the immunoglobulin superfamily of cell adhesion molecules. They were first discovered in chicken retinas and brains by Rutishauser and others in 1976. They are expressed in most vertebrates and invertebrates Central nervous system and peripheral nervous system, membrane surface glycoproteins that mediate adhesion between cells and cells, extracellular matrix (ECM). In normal nerve cell axon growth, aggregation, nerve cell transfer, formation of nerve fiber myelin sheath, nerve fiber bundling, construction of neural pathways, transmembrane signal transduction, synaptic plasticity and learning and memory brain development The process plays an important role.