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Cell adhesion is the process by which cells interact and attach to neighbouring cells through specialised molecules of the cell surface. This process can occur either through direct contact between cell surfaces such as cell junctions or indirect interaction, where cells attach to surrounding extracellular matrix, a gel-like structure containing molecules released by cells into spaces between them. Cells adhesion occurs from the interactions between cell-adhesion molecules (CAMs), transmembrane proteins located on the cell surface. Cell adhesion links cells in different ways and can be involved in signal transduction for cells to detect and respond to changes in the surroundings. Other cellular processes regulated by cell adhesion include cell migration and tissue development in multicellular organisms. Alterations in cell adhesion can disrupt important cellular processes and lead to a variety of diseases, including cancer and arthritis. Cell adhesion is also essential for infectious organisms, such as bacteria or viruses, to cause diseases.
Cell adhesion molecules (CAMs) are a subset of cell surface proteins that are involved in the binding of cells with other cells or with the extracellular matrix (ECM), in a process called cell adhesion. In essence, CAMs help cells stick to each other and to their surroundings. CAMs are crucial components in maintaining tissue structure and function. In fully developed animals, these molecules play an integral role in generating force and movement and consequently ensuring that organs are able to execute their functions normally. In addition to serving as "molecular glue", CAMs play important roles in the cellular mechanisms of growth, contact inhibition, and apoptosis. Aberrant expression of CAMs may result in a wide range of pathologies, ranging from frostbite to cancer.
The L1 family is a family of cell adhesion molecules that includes four different L1-like proteins. They are members of the immunoglobulin superfamily. The members of the L1-family in humans are called L1 or L1cam, CHL1, Neurofascin and NRCAM. L1 family members are found on neurons, especially on their axons. Sometimes they are found on glia, such as Schwann cells, radial glia and Bergmann glia cells and, as such, are important for neural cell migration during development. L1 family members are expressed throughout the vertebrate and invertebrate kingdoms.
L1, also known as L1CAM, is a transmembrane protein member of the L1 protein family, encoded by the L1CAM gene. This protein, of 200-220 kDa, is a neuronal cell adhesion molecule with a strong implication in cell migration, adhesion, neurite outgrowth, myelination and neuronal differentiation. It also plays a key role in treatment-resistant cancers due to its function. It was first identified in 1984 by M. Schachner who found the protein in post-mitotic mice neurons.
Cell junctions are a class of cellular structures consisting of multiprotein complexes that provide contact or adhesion between neighboring cells or between a cell and the extracellular matrix in animals. They also maintain the paracellular barrier of epithelia and control paracellular transport. Cell junctions are especially abundant in epithelial tissues. Combined with cell adhesion molecules and extracellular matrix, cell junctions help hold animal cells together.
Neural cell adhesion molecule (NCAM), also called CD56, is a homophilic binding glycoprotein expressed on the surface of neurons, glia and skeletal muscle. Although CD56 is often considered a marker of neural lineage commitment due to its discovery site, CD56 expression is also found in, among others, the hematopoietic system. Here, the expression of CD56 is mostly associated with, but not limited to, natural killer cells. CD56 has been detected on other lymphoid cells, including gamma delta (γδ) Τ cells and activated CD8+ T cells, as well as on dendritic cells. NCAM has been implicated as having a role in cell–cell adhesion, neurite outgrowth, synaptic plasticity, and learning and memory.
DSCAM and Dscam are both abbreviations for Down syndrome cell adhesion molecule. In humans, DSCAM refers to a gene that encodes one of several protein isoforms.
The immunoglobulin domain, also known as the immunoglobulin fold, is a type of protein domain that consists of a 2-layer sandwich of 7-9 antiparallel β-strands arranged in two β-sheets with a Greek key topology, consisting of about 125 amino acids.
CD155 also known as the poliovirus receptor is a protein that in humans is encoded by the PVR gene.
Afadin is a protein that in humans is encoded by the AFDN gene.
Poliovirus receptor-related 2 (PVRL2), also known as nectin-2 and CD112, is a human plasma membrane glycoprotein.
Cell adhesion molecule 1 is a protein that, in humans, is encoded by the CADM1 gene.
Poliovirus receptor-related 1 (PVRL1), also known as nectin-1 and CD111 (formerly herpesvirus entry mediator C, HVEC) is a human protein of the immunoglobulin superfamily (IgSF), also considered a member of the nectins. It is a membrane protein with three extracellular immunoglobulin domains, a single transmembrane helix and a cytoplasmic tail. The protein can mediate Ca2+-independent cellular adhesion further characterizing it as IgSF cell adhesion molecule (IgSF CAM).
Cell adhesion molecule 3 is a protein that in humans is encoded by the CADM3 gene.
The following outline is provided as an overview of and topical guide to immunology:
V-set domains are Ig-like domains resembling the antibody variable domain. V-set domains are found in diverse protein families, including immunoglobulin light and heavy chains; in several T-cell receptors such as CD2, CD4, CD80, and CD86; in myelin membrane adhesion molecules; in junctional adhesion molecules (JAM); in tyrosine-protein kinase receptors; and in the programmed cell death protein 1 (PD1).
IgSF CAMs are cell adhesion molecules that belong to Immunoglobulin superfamily. It is regarded as the most diverse superfamily of CAMs. This family is characterized by their extracellular domains containing Ig-like domains. The Ig domains are then followed by Fibronectin type III domain repeats and IgSFs are anchored to the membrane by a GPI moiety. This family is involved in both homophilic or heterophilic binding and has the ability to bind integrins or different IgSF CAMs.
Synaptic stabilization is crucial in the developing and adult nervous systems and is considered a result of the late phase of long-term potentiation (LTP). The mechanism involves strengthening and maintaining active synapses through increased expression of cytoskeletal and extracellular matrix elements and postsynaptic scaffold proteins, while pruning less active ones. For example, cell adhesion molecules (CAMs) play a large role in synaptic maintenance and stabilization. Gerald Edelman discovered CAMs and studied their function during development, which showed CAMs are required for cell migration and the formation of the entire nervous system. In the adult nervous system, CAMs play an integral role in synaptic plasticity relating to learning and memory.
A junctional adhesion molecule (JAM) is a protein that is a member of the immunoglobulin superfamily, and is expressed in a variety of different tissues, such as leukocytes, platelets, and epithelial and endothelial cells. They have been shown to regulate signal complex assembly on both their cytoplasmic and extracellular domains through interaction with scaffolding that contains a PDZ domain and adjacent cell's receptors, respectively. JAMs adhere to adjacent cells through interactions with integrins LFA-1 and Mac-1, which are contained in leukocyte β2 and α4β1, which is contained in β1. JAMs have many influences on leukocyte-endothelial cell interactions, which are primarily moderated by the integrins discussed above. They interact in their cytoplasmic domain with scaffold proteins that contain a PDZ domain, which are common protein interaction modules that target short amino acid sequences at the C-terminus of proteins, to form tight junctions in both epithelial and endothelial cells as polarity is gained in the cell.
Nectin-3, also known as nectin cell adhesion molecule 3, is a protein that in humans is encoded by the NECTIN3 gene.
References
- ↑ nectins at the US National Library of Medicine Medical Subject Headings (MeSH)
- ↑ Takai Y, Irie K, Shimizu K, Sakisaka T, Ikeda W (Aug 2003). "Nectins and nectin-like molecules: roles in cell adhesion, migration, and polarization". Cancer Science. 94 (8): 655–67. doi: 10.1111/j.1349-7006.2003.tb01499.x . PMID 12901789.
- 1 2 Fuchs, Anja; Colonna, M (October 2006). "The role of NK cell recognition of nectin and nectin-like proteins in tumor immunosurveillance". Seminars in Cancer Biology. 16 (5): 359–366. doi:10.1016/j.semcancer.2006.07.002. PMID 16904340.
- ↑ Miyoshi J, Takai Y (Sep 2007). "Nectin and nectin-like molecules: biology and pathology". American Journal of Nephrology. 27 (6): 590–604. doi: 10.1159/000108103 . PMID 17823505.
- ↑ Nectin 4 – cell adhesion molecule 4
- ↑ "NECTIN1 nectin cell adhesion molecule 1 [Homo sapiens (human)] - Gene - NCBI".
- ↑ "FDA grants accelerated approval to enfortumab vedotin-ejfv for metastatic urothelial cancer". fda.gov. 20 December 2019. Retrieved May 30, 2021.