Cells Rely on Cell-Adhesion Molecules to Form Tissues
- Cells within tissues are interconnected through cell-to-cell junctions, which rely on cell-adhesion molecules (CAMs) found in the plasma membranes of neighboring cells.
- These junctions are crucial for maintaining the structure and function of tissues and organs.
Definition
Cell-adhesion molecules (CAMs)
Cell-adhesion molecules (CAMs) are proteins that span the phospholipid bilayer of the membrane.
While you are not required to have detailed knowledge of individual CAM types, understanding their general role in cell adhesion and tissue formation is essential.
Structure and Function of CAMs
- Certain domains of CAMs are embedded within the bilayer, while others protrude into the extracellular environment.
- Junction formation occurs when CAMs on adjacent cells bind together through their extracellular domains.
- In some cases, the same CAM type is present in both cells, facilitating symmetrical junctions that group similar cell types.
- In other cases, different CAMs interact to form asymmetrical junctions, allowing for connections between distinct cell types and creating more complex tissue structures.
CAMs are highly specific to the cells they bind to, ensuring proper tissue organization
Importance of Cell Adhesion
- Cell adhesion maintains tissue architecture.
- It ensures structural integrity and facilitates functional relationships between adjacent cells.
- Certain junctions:
- Prevent extracellular movement of substances, maintaining compartmentalization in tissues.
- Facilitate controlled transport of substances when necessary.
- In the immune system:
- CAMs help distinguish between self and foreign cells, a critical function in immune responses.
- In cancer biology, loss of adhesion can lead to metastasis, as cells detach from the primary tumor and migrate to form secondary tumors.
In the heart, gap junctions allow electrical signals to travel rapidly across cardiac cells, ensuring that the heart beats as a coordinated unit.
Common Mistake- Students often confuse cell adhesion with the extracellular matrix (ECM).
- While both contribute to tissue structure, CAMs directly link cells to each other, whereas the ECM provides a scaffold for cells to attach to.
When CAMs fail, the risk of malignancy spreading through metastasis increases.
