Intermediate Filament-co-localized Molecules with Myosin Heavy Chain Epitopes Define Distinct Cellular Domains in Hair Follicles and Epidermis

Background: Proteins linking intermediate filaments to other cytoskeletal components have important functions in maintaining tissue integrity and cell shape.

Results: We found a set of monoclonal antibodies raised against specific human sarcomeric myosin heavy chain (MyHC) isoforms labels cells in distinct regions of the mammalian epidermis. The antigens co-localize with intermediate filament-containing structures. A slow MyHC-related antigen is punctate on the cell surface and co-localizes with desmoplakin at desmosomal junctions of all suprabasal epidermal layers from rat foetal day 16 onwards, in the root sheath of the hair follicle and in intercalated disks of cardiomyocytes. A fast MyHC-related antigen occurs in cytoplasmic filaments in a subset of basal cells of skin epidermis and bulb, but not neck, of hair follicles. A fast IIA MyHC-related antigen labels filaments of a single layer of cells in hair bulb. This 230,000 Mr antigen co-purifies with keratin. No obvious candidate for any of the antigens appears in the literature.

Conclusions: We describe a set of molecules that co-localize with intermediate filament in specific cell subsets in epithelial tissues. These antigens presumably influence intermediate filament structure or function.