Cell-cell fusion and stem cell plasticity: Emerging paradigms in tissue regeneration

Figure 1 Schematic illustration of the cell fusion process. The diagram shows the sequential steps of cell-cell fusion: (1) Cell recognition and adhesion: Two distinct cells recognize each other through receptor-ligand interactions, initiating adhesion; (2) Cytoskeletal rearrangement: Actin cytoskeleton remodeling promotes membrane proximity and prepares for fusion; (3) Membrane apposition and dehydration: The opposing plasma membranes are brought into close contact, and local dehydration of the intermembrane space occurs; (4) Hemifusion: The outer leaflets of the lipid bilayers merge, forming an intermediate hemifusion structure; and (5) Fusion pore formation: A pore opens between the two cells, enabling cytoplasmic continuity and resulting in a fully fused multinucleated cell.