Definitions of Cell Adhesion Molecules
Cell adhesion molecules are involved in cell-cell and cell and extracellular matrix interactions between molecules. Cell adhesion refers to the adhesion between cells, is a form of information exchange between cells. The information exchange of soluble neurotransmitters known as cell adhesion molecules. Cell adhesion molecules is a kind of independent molecular structure, by recognizing the adhesion of its specific receptor and the occurrence of adhesion between the phenomenon.
The composition of cell adhesion molecules
Cell adhesion molecules are transmembrane glycoproteins, molecular structure consists of three parts: ① the extracellular region, the N-terminal part of the peptide chain, with sugar chain, responsible for the identification and ligand; ② transmembrane region, mostly one Transmembrane; ③ cytoplasmic region, the C-terminal part of the peptide chain, generally smaller, or with the plasma membrane component directly connected to, or with the intracellular signal molecules connected to chemical activation of signal transduction pathway.
The role of most cell adhesion molecules depends on divalent cations, such as Ca2+, Mg2+. There are three modes of action of cell adhesion molecules: mutual recognition and binding of homologous Cell adhesion molecules on two adjacent cell surfaces (affinity adhesion); different Cell adhesion molecules on two adjacent cell surfaces Mutual recognition and binding (affinity adhesion); two adjacent cell surface of the same Cell adhesion molecules molecules by extracellular connective molecules recognize and bind each other.
Research and Development of Cell Adhesion Molecules
Cell adhesion molecules group development: Cell adhesion moleculeshas referred to laminin (LN) and fibronectin (FN) and other components of the extracellular matrix (ECM) of the protein. Cell adhesion molecules has recently been clearly considered a group of molecular family. In particular, the discovery of ECM receptor groups, revealed that Cell adhesion molecules is a large number of large family. Because the Cell adhesion molecules category of molecules in vitro culture show cell adhesion activity, so called Cell adhesion molecules. But its role in the body mechanism is not entirely clear.
Cell adhesion molecules research direction: Cell adhesion molecules in the cell connection is one of the ways. The same kind of cells to the same kind of Cell adhesion molecules connection said the same kind of connection, intercellular communication with different heterogeneous Cell adhesion molecules connection. Known in the same kind of connection is the neural cell adhesion molecule (N Cell adhesion molecules) and calcium-dependent adhesin, other connections are mostly heterogeneous connections.
Cell adhesion molecules physiological role is the second research. Cell adhesion is a biological phenomenon in which cells maintain morphological structure and function. Previously, Cell adhesion molecules refers to transmembrane proteins such as thy-1 and LFA-3 on cell membranes. Now that the Cell adhesion molecules is not simply a structural connection, but through the mechanical connection between cells to identify the outside world, or the outside world to convey information to the cell. Such as transmembrane protein contains concentrated tyrosine kinase, indicating that there is information between the Cell adhesion molecules transfer function.
In recent years, monoclonal technology has been identified by a variety of cell adhesion and related to Cell adhesion molecules, known Cell adhesion molecules can be divided into 5 super-family. More Cell adhesion molecules will be identified and clarified as the study progresses.
The main effect of cell adhesion molecules
The change in the amount of expression of adhesion molecules is another important aspect of the regulation of adhesion. Adhesion molecule configuration changes and the number of changes in the expression is not completely separate the two processes, the two may co-exist to complete the regulation of adhesion. Such as lymphocyte activation not only adhesion molecule configuration changes lead to increased affinity, but also associated with the increase in the number of adhesion molecules.
Cell surface adhesion molecules:
The expression of adhesion molecules on the cell surface can be regulated by two ways: to induce the transfer of cell adhesion molecules to the cell surface and to induce the re-synthesis of adhesion molecules. The transfer process takes place in a matter of seconds, but the duration is short. Such as thrombin and histamine on endothelial cells can induce endothelial cells stored in the CD62 molecules quickly transferred to the cell surface, and then quickly endocytosis and disappeared; and as CD11b / CD18, CD11c / CD18 stored in neutrophils Of the cytoplasm particles, in the PMA, TNF, IL-1 stimulation after rapid transfer to the cell surface. Re-synthesis process occurs more slowly, generally takes a few hours, but to maintain a longer time. IL-1 and TNF-α can induce E-selectin and V Cell adhesion molecules-1 molecule re-synthesis and expression in HUVECs, and peaked at 4 hours after induction, and maintained for more than 24 hours.
Cytokine inflammatory mediators:
IL-1, IL-3, IL-4, IL-8, PAF, GM-CSF, TNF-α, TNF-βand IFN-γand inflammatory mediators such as leukotrienes, histamine and thrombin. In leukocytes and/or vascular endothelial cells, the adhesion of leukocytes to vascular endothelial cells is regulated (Table 2-6). In the body may have a variety of regulatory factors exist, influence each other, and there may be more unknown factors involved in cell adhesion between the regulation process.
Cell growth and development status:
In addition to these cytokines, inflammatory mediators can regulate the expression of cell adhesion molecules, the growth, development, differentiation and metabolic state of cells themselves can also affect the expression of adhesion molecules. During embryonic development, the expression of cell adhesion molecules changes according to certain rules, so that different cells can be combined according to certain rules, the formation of different tissues or organs. Tumor cells and its normal tissue cells compared to the expression of adhesion molecules can be very different, which may be some tumor cells prone to infiltration, metastasis and other phenomena of molecular basis. In addition, there are also significant changes in the expression of adhesion molecules on lymphocytes in differentiated and developing states, such as memory T cells expressing more CD2 than naive T cells without antigen-stimulated T cells , LFA-1, CD44, VLA-4. The expression level of L-selectin in naive T cells was significantly higher than that of memory T cells.