Definition of Adherens Junctions and Desmosomes
Adherens junctions are a type of cell junction found in epithelial and endothelial tissues that play an important role in cell-cell adhesion. These junctions are composed of transmembrane proteins called cadherins, which interact with actin filaments in the cytoskeleton of adjacent cells. Adherens junctions are located in the lateral membranes of cells and form a continuous belt-like structure called the zonula adherens.
Functionally, adherens junctions play an important role in maintaining tissue integrity and organization, as they anchor adjacent cells together and allow them to communicate and exchange signals. They also help to regulate cell behavior, such as cell proliferation, differentiation, and migration.
Examples of tissues that contain adherens junctions include the epithelial lining of the intestines, the endothelium of blood vessels, and the skin. Dysfunction or loss of adherens junctions has been linked to a variety of diseases, including cancer, heart disease, and developmental disorders.
Desmosomes are another type of cell junction found in epithelial and some muscle tissues that also play an important role in cell-cell adhesion. They are composed of transmembrane proteins called desmogleins and desmocollins, which interact with intermediate filaments in the cytoskeleton of adjacent cells. Desmosomes are located in the lateral membranes of cells and form discrete, button-like structures called macula adherens.
Functionally, desmosomes also play a key role in maintaining tissue integrity and strength by anchoring adjacent cells together and providing resistance to mechanical stress. They are especially important in tissues that experience high levels of mechanical stress, such as the skin and heart.
Examples of tissues that contain desmosomes include the epidermis of the skin, the lining of the digestive tract, and cardiac muscle tissue. Defects or mutations in desmosome components have been linked to a number of diseases, including various forms of skin disorders and cardiomyopathies.
Comparison between Adherens Junctions and Desmosomes
Adherens junctions and desmosomes are two types of cell junctions that play important roles in cell-cell adhesion and tissue integrity. While they share some similarities, they also have important differences.
Structurally, adherens junctions are composed of cadherins that interact with actin filaments, while desmosomes are composed of desmogleins and desmocollins that interact with intermediate filaments. Adherens junctions form a continuous belt-like structure called the zonula adherens, while desmosomes form discrete button-like structures called macula adherens.
In terms of function, adherens junctions play a key role in cell-cell adhesion, tissue organization, and regulation of cell behavior, while desmosomes are primarily involved in tissue strength and resistance to mechanical stress. Adherens junctions are also involved in signaling pathways, while desmosomes are not.
Finally, there are some tissues that have both adherens junctions and desmosomes, such as the epidermis of the skin. In these cases, the two types of junctions work together to provide both adhesion and strength to the tissue.
In conclusion, adherens junctions and desmosomes are two types of cell junctions that play important roles in cell-cell adhesion and tissue integrity. Adherens junctions are composed of cadherins that interact with actin filaments and are involved in tissue organization, cell behavior regulation, and signaling pathways.
Desmosomes are composed of desmogleins and desmocollins that interact with intermediate filaments and are primarily involved in tissue strength and resistance to mechanical stress. While both junctions are important, they have different structural components, functions, and mechanisms of action. Understanding the differences between these junctions is essential for understanding their roles in maintaining tissue integrity and for developing treatments for diseases that involve junction dysfunction.
Here are some references that you can use to learn more about adherens junctions and desmosomes:
- Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K., & Walter, P. (2002). Molecular Biology of the Cell. 4th edition. New York: Garland Science. Chapter 19.
- Gumbiner, B. M. (1996). Cell adhesion: the molecular basis of tissue architecture and morphogenesis. Cell, 84(3), 345-357.
- Green, K. J., Getsios, S., & Troyanovsky, S. (2010). Intercellular junction assembly, dynamics, and homeostasis. Cold Spring Harbor perspectives in biology, 2(2), a000125.
- Hynes, R. O. (2002). Integrins: bidirectional, allosteric signaling machines. Cell, 110(6), 673-687.
- Nekrasova, O., Green, K. J., & Choi, H. J. (2013). Interplay of cadherin-mediated cell adhesion and canonical Wnt signaling. Cold Spring Harbor perspectives in biology, 5(3), a009148.
- Sokolowski, J., & Thomas, U. (2019). Comparison of adherens junctions and desmosomes. Journal of cell science, 132(14), jcs227456.
- Takeichi, M. (1991). Cadherin cell adhesion receptors as a morphogenetic regulator. Science, 251(5000), 1451-1455.