THE WIDESPREAD HUMAN DESMOCOLLIN DSC2 AND TISSUE-SPECIFIC PATTERNS OFSYNTHESIS OF VARIOUS DESMOCOLLIN SUBTYPES

By comparison of the cDNA-derived amino acid sequences and the cell ty pe-specific patterns of synthesis me have identified desmocollin Dsc2 as the most widespread, perhaps ubiquitous desmocollin subtype. Using Northern blot analyses and ribonuclease protection assays we have foun d an approximately 5.6 kb mRNA encoding Dsc2 in all the diverse human tissues, tumors and cell lines examined that are known to possess desm osomes, i.e. not only epithelial cells but also myocardiac cells and l ymph 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 unex plained - lymph nodes, and in certain carcinomas and cell lines derive d 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 examine d. We also show that certain cells such as the epidermal keratinocyte line HaCaT and the vulvar carcinoma-derived line A-431 continually syn thesize more than one Dsc subtype. The cell type-specific patterns of synthesis of the various Dsg and Dsc subtypes are discussed in relatio n to tissue development during embryogenesis and to malignant transfor mations, and the utilization of reagents for the specific Dsg and Dsc subtypes in tumor diagnosis is proposed.