Key Concepts of Cell Adhesion Molecules to Know for Cell Biology

Cell adhesion molecules (CAMs) are vital for how cells stick together and communicate. They influence everything from tissue structure to immune responses, making them key players in cell biology and essential for advancements in cell and tissue engineering.

1. Integrins

   • Transmembrane receptors that facilitate cell-extracellular matrix (ECM) adhesion.
   • Composed of alpha and beta subunits, allowing for diverse ligand binding.
   • Play a crucial role in cell signaling, influencing cell survival, proliferation, and migration.

2. Cadherins

   • Calcium-dependent adhesion molecules that mediate cell-cell interactions.
   • Essential for maintaining tissue integrity and structure, particularly in epithelial tissues.
   • Involved in signaling pathways that regulate cell behavior and tissue development.

3. Selectins

   • Cell surface glycoproteins that mediate transient cell-cell adhesion, particularly in the immune response.
   • Important for leukocyte rolling and migration during inflammation.
   • Composed of three types: L-selectin (leukocytes), E-selectin (endothelial cells), and P-selectin (platelets).

4. Immunoglobulin superfamily (IgSF) CAMs

   • A diverse group of proteins involved in cell adhesion and immune responses.
   • Characterized by the presence of immunoglobulin-like domains.
   • Play roles in neuronal development, immune cell interactions, and tissue repair.

5. Mucins

   • High molecular weight glycoproteins that provide a protective barrier on epithelial surfaces.
   • Involved in cell signaling and adhesion, particularly in the respiratory and gastrointestinal tracts.
   • Contribute to the formation of mucus, aiding in lubrication and pathogen defense.

6. Proteoglycans

   • Glycoproteins consisting of a core protein and glycosaminoglycan (GAG) chains.
   • Play a key role in the structural integrity of the ECM and in cell signaling.
   • Involved in regulating cell adhesion, migration, and proliferation through interactions with growth factors.

7. Focal adhesions

   • Complexes that anchor cells to the ECM, composed of integrins and associated proteins.
   • Serve as signaling hubs that transmit mechanical and biochemical signals to the cell.
   • Critical for processes such as cell migration, proliferation, and differentiation.

8. Desmosomes

   • Specialized structures that provide strong adhesion between adjacent cells, particularly in tissues subject to mechanical stress.
   • Composed of cadherin proteins and intermediate filaments, contributing to tissue stability.
   • Important in maintaining the integrity of epithelial and cardiac tissues.

9. Tight junctions

   • Junctions that create a barrier between adjacent cells, preventing the passage of molecules and ions.
   • Composed of claudins and occludins, regulating paracellular transport.
   • Essential for maintaining cell polarity and the selective permeability of epithelial layers.

10. Gap junctions

    • Intercellular channels that allow direct communication between adjacent cells.
    • Composed of connexins, facilitating the transfer of ions and small molecules.
    • Play a critical role in coordinating cellular activities and maintaining tissue homeostasis.