ALTERED GLYCOSYLATION PATTERN OF PROTEINS IN ALZHEIMER-DISEASE

Post-translational modifications due to glycosylation of proteins in h uman brains from patients with Alzheimer disease (AD) were analyzed us ing lectin histochemistry. Results indicate a significant increase in the production of O-glycosylated (containing Gal beta 1,3GalNAc alpha 1,0 Ser/Thr or GalNAc alpha 1,0 Ser/Thr) proteins in neuritic plaques and neurofibrillary tangles which are the major histopathological hall marks of AD brains. These alterations were determined by positive labe lling with lectins obtained from Amaranthus leucocarpus (ALL) and Macr obrachium rosenbergii (MRL) respectively. Immunohistochemistry indicat ed that the lectin-staining labelled specifically both neurofibrillary tangles and neuritic plaques. In contrast, lectins labelling was rest ricted to microvessels in normal control brains. These results provide evidence that modifications of the specific glycosylation patterns ar e closely related with the presence of the hallmark lesions of this di sease, suggesting that an abnormal enzymatic processing of proteins ma y be an early event in the neuronal degeneration which characterises A D.