Characterization and Purification of Human Corneodesmosin, an Epidermal Basic Glycoprotein Associated with Corneocyte-specific Modified Desmosomes

Abstract

Using monoclonal antibodies, we identified a new protein in mammalian epidermis, which we called corneodesmosin. It is located in the extracellular part of the modified desmosomes in the cornified layer of the tissue, and its proteolysis (from 52-56 to 33 kDa) is thought to be a major prerequisite of desquamation. We have now further characterized human corneodesmosin. Proteolysis of purified cornified cell envelopes produced immunoreactive fragments, confirming the covalent linkage of the protein to these structures. Sequential extraction of epidermal proteins indicated that the 52-56-kDa precursor form of the protein exists in two distinct pools, one extracted with a nondenaturing hypotonic buffer, and the other with urea. Two-dimensional gel analysis and reactivity with phosphoserine-specific antibodies showed that it is a basic phosphoprotein. Deglycosylation experiments, reactivity with lectins, and chromatography on concanavalin A-Sepharose indicated that corneodesmosin is N-glycosylated. Partial sequences, 10 and 15 amino acids long, of the purified 52-56-kDa corneodesmosin showed identity with sequences predicted from a previously cloned gene, proved to be expressed in the epidermis and designated S. This indicates that corneodesmosin is probably encoded by the S gene, the function of which was unknown until now. A model of corneodesmosin maturation during cornification is proposed.

Epidermal detachment, desmosomal dissociation, and destabilization of corneodesmosin in Spink5-/- mice

“…In humans, this antibody recognizes three clusters of bands as follows: a full-length cluster (52-56 kDa), which is mainly found in the keratinosomes and present in the detergent-soluble pool; an intermediate-size cluster (40-48 kDa), which primarily exists in the detergentinsoluble fraction and is thought to contribute to desmosome stabilization; and a small-size cluster (33-36 kDa), which is normally present in the uppermost SC, and probably lacks adhesive properties Simon et al 1997Simon et al , 2001). In mouse skin, F28-F27 also recognizes three Cdsn clusters, but the sizes are slightly different from those observed in humans, that is, 75 kDa, 45-60 kDa, and 36-40 kDa, respectively .…”

Refined Characterization of Corneodesmosin Proteolysis during Terminal Differentiation of Human Epidermis and Its Relationship to Desquamation

“…Cdsn is synthesized in the upper spinous and/or lower granular layers in the form of a 52-56-kDa phosphorylated basic glycoprotein. It is ex-ported by cytoplasmic vesicles called keratinosomes into the extracellular space where it interacts with the core of the desmosomes just before their transformation into corneodesmosomes (9,13,22,23). Cdsn is a 529-amino acid-long, glycine-and serine-rich protein.…”

Targeted ablation of Arnt in mouse epidermis results in profound defects in desquamation and epidermal barrier function

“…Their major functional components are transmembrane glycoproteins of the cadherin family, Dsg1 and Dsc1 (Serre et al, 1991;Rawlings and Matts, 2005), and a specific corneosomal protein corneodesmosin (Rawlings et al, 1994;Simon et al, 1997). In normal epidermis, corneosomes provide a connection between corneocytes in the lowermost stratum corneum, and their gradual degradation upon ascension towards the surface of the corny layer eventually leads to desquamation (Rawlings et al, 1994).…”