Hemidesmosomit

Hemidesmosomit, known in English as hemidesmosomes, are specialized cell-matrix adhesion complexes that anchor epithelial cells to the underlying basement membrane. They play a key role in maintaining tissue integrity by resisting mechanical stress.

These structures consist of a dense cytoplasmic plaque linked to keratin intermediate filaments by plakins such as BP230 (BP antigen 230) and plectin. The transmembrane core is formed primarily by integrin α6β4 and the transmembrane collagen XVII (BP180). The extracellular domains interact with laminin-332 in the basement membrane, helping to secure the cell to its substrate.

The hemidesmosome is typically located at the basal or basolateral surface of stratified epithelial cells, including keratinocytes in skin and mucous membranes. They provide a stable anchor for the epidermis and contribute to resistance to shear forces.

Formation and turnover: assembly occurs during cell adhesion, regulated by signaling and cytoskeletal dynamics; disassembly occurs during wound healing or remodeling; reassembly re-establishes adhesion. The dynamic nature allows remodeling during growth and repair.

Clinical relevance: Autoimmune diseases such as bullous pemphigoid target hemidesmosome components (BP180 and BP230, and occasionally integrin α6β4), leading to subepidermal blistering. Genetic defects affecting hemidesmosome proteins or laminin-332 can cause epidermolysis bullosa with skin fragility, characterized by blistering and erosion. Tightly regulated hemidesmosome function is essential for barrier integrity.