Cell Adhesion from cells to tissue.docx

Cell Adhesion, from cells to tissue Adhesion molecules play important roles in various physiological processes by mediating interactions between cells and their surrounding environment. These molecules are classified into different families based on their structures and functions. Cell adhesions, su...

Cell Adhesion, from cells to tissue Adhesion molecules play important roles in various physiological processes by mediating interactions between cells and their surrounding environment. These molecules are classified into different families based on their structures and functions. Cell adhesions, such as integrin-mediated, cadherin-based, selectin-mediated, immunoglobulin superfamily (IgSF) adhesions, and extracellular matrix (ECM)-based adhesions, exhibit distinct molecular characteristics, involving unique components, ligand interactions, signaling pathways, and cytoskeletal connections; however, they share a common goal of establishing and maintaining interactions with their environment through ligand-receptor interactions, activating signaling cascades, and utilizing cytoskeletal links. In tissues, particularly epithelia, different adhesion structures and junctions play distinct and vital roles in maintaining tissue integrity, barrier function, and dynamic cellular processes. Tight junctions are essential for establishing a selectively permeable barrier, regulating the passage of ions and molecules between epithelial cells. Adherens junctions, formed by cadherin-mediated interactions, contribute to cell-cell adhesion and tissue cohesion by connecting the actin cytoskeletons of adjacent cells. Desmosomes, characterized by cadherin proteins and intermediate filaments, provide mechanical strength and resistance to mechanical stress by anchoring cells together. Gap junctions enable direct communication between adjacent cells by forming channels that allow the exchange of small molecules and ions. Focal adhesions, mediated by integrins, connect cells to the extracellular matrix, facilitating signaling, migration, and tissue remodelling. Altogether, these adhesion structures orchestrate the intricate balance between cellular cohesion, barrier function, and responsiveness to environmental cues, contributing to the overall homeostasis and functionality of epithelial tissues. Experimental evidence identifying adhesion molecules, their interacting partners, and the mechanisms mediating their function has been derived from a variety of techniques. For example, co-immunoprecipitation studies have been instrumental in elucidating protein-protein interactions involved in adhesion. Using this approach, researchers have successfully isolated adhesion molecules and their binding partners from cell lysates, confirming specific molecular associations. Additionally, crystallography and nuclear magnetic resonance (NMR) spectroscopy have provided high-resolution structural information, detailing the precise atomic interactions between adhesion molecules and their ligands. Live-cell imaging techniques, including total internal reflection fluorescence (TIRF) microscopy, have allowed real-time visualization of adhesion events, capturing the spatiotemporal dynamics of adhesion molecule activity.