Increased Mr 60,000 protein phosphorylation is correlated with neocortical neurofibrillary tangles in Alzheimer's disease.

Increased Mr 60,000 protein phosphorylation has been found in the cytosol fraction of brain tissue from Alzheimer's disease patients. A correlation between this biochemical change and the morphologic abnormalities found in Alzheimer's disease was sought. Three neuropathologic features were studied: neurofibrillary tangles and neuritic plaques, findings characteristic of Alzheimer's disease, and gliosis, a non-specific change. The number of tangles correlated well with the extent of Mr 60,000 protein phosphorylation (p less than 0.001); but the number of plaques did not. To investigate the possibility that gliosis causes the increased Mr 60,000 protein phosphorylation, cases of Pick's disease and multi-infarct dementia were also studied. The levels of Mr 60,000 protein phosphorylation in these cases were comparable to those seen in normal controls. These findings suggest that the increased Mr 60,000 protein phosphorylation is closely related to diseased, tangle-bearing neurons and is not directly related to neuritic plaque formation or secondary gliosis.