p120 catenin is a protein found inside cells that plays a role in how cells connect and interact. It contributes to the organization and integrity of tissues and organs. This protein is involved in maintaining the structure of various cellular components and influencing how cells behave.
Cellular Architecture and p120 Catenin’s Place
p120 catenin primarily resides at specialized cell-cell connections called adherens junctions. These junctions hold neighboring cells together to form cohesive tissues. At these sites, p120 catenin directly associates with cadherin proteins, which are transmembrane proteins.
This interaction stabilizes cadherin proteins at the cell surface. Without p120 catenin, cadherin proteins can be internalized, leading to weakened cell-cell adhesion. This association also promotes cadherin clustering, necessary for forming adherens junctions.
Beyond Structure p120 Catenin as a Regulator
Beyond its role in stabilizing cell-cell connections, p120 catenin functions as a dynamic regulator, influencing various cellular activities. It transmits signals that affect cell shape, movement, and growth. This protein modulates the activity of small GTPases, such as RhoA, Rac1, and Cdc42, which are master regulators of the cell’s internal scaffolding, known as the actin cytoskeleton.
By influencing these Rho family GTPases, p120 catenin helps control processes like the formation of stress fibers and focal adhesions, which are structures involved in cell attachment and movement. For instance, overexpression of p120 catenin can lead to decreased RhoA activity while increasing the activity of Rac1 and Cdc42, thereby promoting cell migration. This regulatory capacity allows p120 catenin to orchestrate a balance between stable cell adhesion and the cell’s ability to move within tissues.
p120 Catenin in Health and Disease
The proper function of p120 catenin is important for maintaining tissue integrity, and its dysfunction has significant implications for human health, particularly in cancer. Alterations in p120 catenin levels, its location within the cell, or its activity can contribute to the development and progression of various cancers. For example, reduced p120 catenin expression is often associated with diminished E-cadherin function and tumor progression. This can lead to cells becoming less adhesive and more migratory, a characteristic feature of aggressive cancers.
In some cases, the loss of p120 catenin can lead to increased metastatic potential, as observed in certain breast cancer models where its absence promotes early tumor dissemination. This is because the cells become more prone to single-cell migration and exhibit increased invasive behavior. Conversely, in specific cancer types like invasive lobular carcinoma, a complete loss of p120 catenin can impair tumor formation, suggesting context-dependent roles in disease progression. Furthermore, changes in the phosphorylation status of p120 catenin can affect E-cadherin-mediated cell adhesion and influence the ability of tumor cells to spread to distant sites. Beyond cancer, p120 catenin also has roles in other conditions, including maintaining epidermal function, participating in embryonic development, and influencing inflammatory responses.