Hemidesmosomer

Hemidesmosomes are specialized cell-matrix adhesion structures that anchor the basal surface of epithelial cells to the underlying basement membrane. They contribute to tissue integrity by linking the keratin intermediate filament network inside the cell to extracellular matrix components, providing resistance to mechanical stress.

A typical hemidesmosome contains a transmembrane protein complex and cytoplasmic plaque proteins. The transmembrane portion principally consists of integrin α6β4 and collagen XVII (BP180), which interact with laminin-332 in the basement membrane. Inside the cell, a dense plaque includes proteins such as BP230 (dystonin), plectin, and the cytoplasmic tail of β4 integrin, which connect to keratin intermediate filaments. This arrangement forms a link between the cytoskeleton and the extracellular matrix, stabilizing the attachment of epithelial cells to the basement membrane.

Hemidesmosome assembly and disassembly are dynamic processes that occur during development, wound healing, and cell migration. Formation strengthens cell-mian junctions in resting epithelia, while disassembly allows cells to migrate over the basement membrane during repair or remodeling.

Clinical relevance is most evident in diseases affecting hemidesmosome components. Autoimmune bullous diseases such as bullous pemphigoid involve autoantibodies against BP180 (collagen XVII) and BP230, leading to subepidermal blistering. Genetic defects in hemidesmosome components, including ITGA6, ITGB4, COL17A1, and PLEC, underlie certain forms of epidermolysis bullosa and related disorders, highlighting the role of hemidesmosomes in maintaining epithelial adhesion and tissue integrity.