TAN-LIKE IMMUNOREACTIVITY IN ALZHEIMER AND CONTROL SKIN FIBROBLASTS

The presence of the microtubule-associated protein tan in skin fibroblasts derived from Alzheimer patients and normal controls was investigated using a panel of well-characterized anti-tau antibodies against epitopes spanning the tau protein from the amino to the carboxyl end. The antibodies immunolabeled a fine, fibrillar cytoplasmic network in all skin fibroblasts. Disruption of the microtubule network with colchicine did not affect the immunolabeling of the fibrillar network nor did treatment with cytochalasin B known to disrupt the microfilament network. Immunoelectron microscopy with the antitau antibodies revealed colocalization of the label with the 10 nm intermediate filaments, Furthermore, immunoblots found no reactivity against purified vimentin, suggesting that the antibodies recognize an intermediate filament-associated protein. The findings indicate the presence of tau or a protein with considerable homology to tau in fibroblasts associated with intermediate filaments and not microtubules. (C) 1994 Wiley-Liss, Inc.