CYTOPLASMIC DESMOSOMES AND INTERMEDIATE FILAMENT DISTURBANCE FOLLOWING ACRYLAMIDE TREATMENT IN CULTURED RAT KERATINOCYTES

The present paper describes disturbances in the organization of tonofi laments and desmosomes of rat lingual and epidermal keratinocytes afte r treatment of the cells with acrylamide in culture. This treatment in duced changes in cell shape, reduction of intercellular adhesion and a perinuclear accumulation of cytoplasmic organelles. Using specific an tibodies for cytokeratins, the filaments were disorganized particularl y in the perinuclear region. In untreated cells, keratin filament labe lling was very weak or absent above and below the nucleus thus leaving a black nuclear space in fluorescine microscopy. Following acrylamide treatment, the keratin filament labelling covered the nuclear space w hich indicated the accumulation of these filaments all around the nucl eus. Furthermore, the desmosomal junctions were often associated with thick keratin bundles. Antibodies for desmoplakins revealed a reductio n in intercellular labelling and stronger cytoplasmic labelling. Ultra structurally, well-developed long tonofilaments were found to associat e with large desmosomal junctions. Furthermore, small-sized desmosomal structures were identified within the cytoplasm. Morphologically, the se were identical to cell surface desmosomes and were almost always as sociated with well-developed tonofilaments. The effect of acrylamide o n the protein kinase A activity might be implicated in the disturbance s of the desmosome-intermediate filament complex and in the initiation of contractile forces necessary for perinuclear accumulation of inter mediate filaments and for the formation of intact cytoplasmic desmosom es. The acrylamide-induced intermediate filament and desmosomal change s may provide valuable information on the mechanism of intact cytoplas mic desmosome formation in several skin diseases and in squamous cell carcinoma.