EXPRESSION OF 3-REPEAT AND 4-REPEAT TAU-ISOFORMS IN MOUSE-LIVER

Tau protein is a member of the family of microtubule-associated protei ns, which support microtubule polymerization and stability. Under path ological conditions, tau is a major constituent of neurofibrillary tan gles in nerve cells of patients with Alzheimer's disease. Neurofibrill ary tangles share some morphological, biochemical and immunological pr operties with cytoplasmic inclusions associated with other diseases, s uch as Mallory bodies in the livers of patients with alcoholic hepatit is and in corresponding mouse models. Recently a Mallory body componen t was identified that in molecular mass and isoelectric point resemble s the abnormally phosphorylated tau of neurofibrillary tangles. There has been, however, so far no report describing the occurrence of tau i n normal liver. We now demonstrate the expression of two tau isoforms containing three and four repeats, respectively, of the microtubule bi nding domains in normal mouse liver and kidney. This finding provides evidence for a physiological role of tau in the liver and, consequentl y, the basis for the involvement of tau in pathological situations.