A NOVEL CORRELATION BETWEEN THE LEVELS OF BETA-AMYLOID PROTEIN-PRECURSOR AND TAU-TRANSCRIPTS IN THE AGED HUMAN BRAIN

Beta-amyloid protein precursor (APP) and tau are implicated in the pathogenesis of Alzheimer's disease. We quantified the levels of APP and tau-transcripts in the three cortical regions of 38 aged human brains obtained from consecutive autopsied patients. The level of APP mRNA was directly proportional to that of tau-mRNA to a remarkable extent, suggesting coordinate expression of the APP and tau-genes, whereas much weaker correlations were noted among mRNAs encoding other neuronal proteins. From the previous data on the differential expression of APP and tau-mRNAs, the levels of APP-751 and -695 mRNAs were calculated and found to be proportional to those of four-repeat and three-repeat tau-mRNAs, respectively, whereas that of APP-770 mRNA was rather constant. These results suggest that the mRNA concentrations of APP isoforms are linked to those of tau-isoforms in the aged human brain.