The widespread human desmocollin Dsc2 and tissue-specific patterns of synthesis of various desmocollin subtypes.

By comparison of the cDNA-derived amino acid sequences and the cell type-specific patterns of synthesis we have identified desmocollin Dsc2 as the most widespread, perhaps ubiquitous desmocollin subtype. Using Northern blot analyses and ribonuclease protection assays we have found an approximately 5.6 kb mRNA encoding Dsc2 in all the diverse human tissues, tumors and cell lines examined that are known to possess desmosomes, i.e. not only epithelial cells but also myocardiac cells and lymph nodes. By contrast, desmocollin subtypes Dsc1 and Dsc3 have been detected only in certain stratified squamous epithelia, with the most conspicuous restriction of Dsc1 to epidermis and--remarkably, but unexplained--lymph nodes, and in certain carcinomas and cell lines derived therefrom. We have also determined that both Dsc2 mRNA splice forms, the one encoding the larger polypeptide a and the one coding for the shorter Dsc2b, occur in all the diverse tissues and cell lines examined. We also show that certain cells such as the epidermal keratinocyte line HaCaT and the vulvar carcinoma-derived line A-431 continually synthesize more than one Dsc subtype. The cell type-specific patterns of synthesis of the various Dsg and Dsc subtypes are discussed in relation to tissue development during embryogenesis and to malignant transformations, and the utilization of reagents for the specific Dsg and Dsc subtypes in tumor diagnosis is proposed.