Involvement of corneodesmosome degradation and lamellar granule transportation in the desquamation process.

Desquamation in the mammalian skin is a well-balanced process of producing corneocytes and shedding them from the surface of the skin. The corneodesmosome, which is a modified desmosome, is the main adhesive structure in the cornified cell layer. The major extracellular constituents of corneodesmosomes are desmoglein 1, desmocollin 1, and corneodesmosin. Proteases involved in the degradation of corneodesmosomes and their inhibitors are secreted from lamellar granules in the granular cell layer. Genetic defects in corneodesmosin and protease inhibitors result in accelerated desquamation and severe barrier impairment. Abnormalities in transportation and secretion of lamellar granules underlie ichthyosis seen in certain human diseases.