Definition of Cadherin and Integrin
Cadherin and Integrin are both types of cell adhesion molecules that play important roles in cell-cell and cell-matrix interactions.
Cadherins are transmembrane proteins that mediate calcium-dependent cell-cell adhesion. They are found in many different cell types and are responsible for maintaining the structural integrity of tissues. Cadherins form homophilic interactions, meaning they bind to other cadherins of the same type on adjacent cells.
Integrins are also transmembrane proteins, but they mediate cell-matrix adhesion. They are found on the surface of cells and bind to extracellular matrix proteins such as fibronectin, collagen, and laminin. Integrins can also interact with other cell surface receptors and signal transduction pathways to regulate cell behavior, such as cell migration, proliferation, and differentiation.
Both cadherins and integrins are important for cell signaling, tissue development, and maintenance of tissue architecture. Dysregulation of cadherin or integrin expression or function can lead to a variety of diseases, including cancer, cardiovascular disease, and autoimmune disorders.
Cadherins are a type of cell adhesion molecule (CAM) that play a critical role in the formation and maintenance of tissue structure. They are calcium-dependent transmembrane proteins that mediate cell-to-cell adhesion in a homophilic manner, meaning they interact with other cadherin molecules of the same type on neighboring cells.
Cadherins are primarily found in epithelial and neural tissues, and they are classified based on their tissue distribution and molecular structure. There are four main types of cadherins:
- Classical cadherins: These are the most common type of cadherins and are found in epithelial tissues. They are characterized by their extracellular domain, which contains five cadherin repeats and a calcium-binding site.
- Desmosomal cadherins: These are found in desmosomes, which are structures that provide mechanical stability to tissues that are subject to mechanical stress. They are characterized by their extracellular domain, which contains only three cadherin repeats and no calcium-binding site.
- Protocadherins: These are a large family of cadherins that are found in neural tissues. They are characterized by their variable extracellular domain, which contains different numbers and arrangements of cadherin repeats.
- Non-classical cadherins: These are a diverse group of cadherins that do not fit into the other categories. They include cadherin-11, which is found in mesenchymal tissues and plays a role in cell migration and tissue formation.
The mechanism of cadherin-mediated cell adhesion involves the interaction between the extracellular domains of cadherin molecules on neighboring cells, which creates a strong bond between them. This bond is maintained by calcium ions, which stabilize the interaction between the cadherin molecules.
Cadherins play a crucial role in tissue formation and maintenance, and alterations in their expression or function can lead to a variety of diseases, including cancer and developmental disorders.
Integrins are a type of cell adhesion molecule (CAM) that play a crucial role in cell-to-cell and cell-to-extracellular matrix (ECM) interactions. They are transmembrane proteins that bind to ECM proteins, such as collagen, fibronectin, and laminin, as well as to other integrin molecules on neighboring cells. Unlike cadherins, integrins can bind to a variety of ECM proteins and can mediate cell adhesion in both a homophilic and heterophilic manner.
Integrins are found in a variety of cell types and tissues and are involved in numerous cellular processes, including:
- Cell adhesion and migration: Integrins facilitate cell adhesion to the ECM and promote cell migration during development, tissue repair, and immune response.
- Signaling: Integrins can activate intracellular signaling pathways that regulate cellular processes such as cell proliferation, differentiation, and survival.
- Gene expression: Integrins can regulate gene expression by altering the activity of transcription factors and chromatin remodeling enzymes.
There are 24 different integrin molecules, each composed of an alpha and beta subunit that combine to form a heterodimer. The specific combination of subunits determines the ligand-binding specificity of the integrin molecule. For example, the alpha5beta1 integrin binds to fibronectin, while the alpha2beta1 integrin binds to collagen.
Integrin-mediated cell adhesion is a dynamic process that involves the binding and release of integrin molecules from the ECM. This process is regulated by a variety of factors, including cytoskeletal proteins, signaling molecules, and ECM proteins.
Dysregulation of integrin function or expression can lead to a variety of diseases, including cancer, autoimmune disorders, and cardiovascular disease. As a result, integrins have become an important target for the development of novel therapeutics.
Differences between Cadherins and Integrins
Cadherins and integrins are two types of cell adhesion molecules that play critical roles in cell-to-cell and cell-to-ECM interactions. While both molecules mediate adhesion, there are several key differences between them:
- Ligand specificity: Cadherins mediate cell adhesion in a homophilic manner, meaning they interact with other cadherin molecules of the same type on neighboring cells. In contrast, integrins can bind to a variety of ECM proteins, such as collagen, fibronectin, and laminin, as well as to other integrin molecules on neighboring cells.
- Calcium dependence: Cadherins are calcium-dependent transmembrane proteins that require calcium ions to mediate cell adhesion. In contrast, integrins do not require calcium ions for their function.
- Structure: Cadherins are composed of a single transmembrane protein that interacts with other cadherin molecules on neighboring cells. Integrins are composed of two transmembrane proteins, alpha and beta subunits, that interact with both ECM proteins and other integrin molecules.
- Tissue distribution: Cadherins are primarily found in epithelial and neural tissues, while integrins are found in a variety of cell types and tissues.
- Function: While both cadherins and integrins mediate cell adhesion, their functions are distinct. Cadherins primarily mediate cell-cell adhesion and play a crucial role in tissue formation and maintenance. Integrins mediate both cell-cell and cell-ECM adhesion and are involved in numerous cellular processes, including cell migration, signaling, and gene expression.
While both cadherins and integrins are important for cell adhesion and play critical roles in cellular processes, their ligand specificity, calcium dependence, structure, tissue distribution, and function differ significantly.
Cell adhesion is a critical process that allows cells to interact with each other and with the extracellular matrix. Cadherins and integrins are two types of cell adhesion molecules that mediate cell-to-cell and cell-to-ECM interactions, respectively. While both molecules are important for cell adhesion, they differ in ligand specificity, calcium dependence, structure, tissue distribution, and function.
Understanding the differences between cadherins and integrins is essential for gaining insights into cellular processes such as tissue formation, maintenance, and repair, and for developing new therapeutic approaches for diseases associated with dysregulated cell adhesion.
- The Cell Adhesion Molecule Resource – https://www.celladhesionmolecules.org/
- The Cadherin Resource – http://cadherin.stanford.edu/
- The Integrin Resource – http://www.integrins.org/