Primate-like amyloid-beta sequence but no cerebral amyloidosis in aged tree shrews.

- Pawlik M, Fuchs E, Walker LC, Levy E

Neurobiol Aging 1999 Jan-Feb;20(1):47-51.

A central pathological feature of Alzheimer's disease is the profuse deposition of amyloid-beta protein (Abeta) in the brain parenchyma and vessel walls. Abeta also forms deposits in the brains of a variety of mammals, including all aged non-human primates studied to date. The sequence of Abeta in these animals is identical to that in humans. No Abeta deposits have been found in the brains of wild-type rats and mice, suggesting that the three amino acid differences between their Abeta and that of amyloid-bearing mammals impedes the fibrillogenicity of Abeta. Analysis of the primary sequence of the beta-amyloid precursor protein in tree shrews revealed a 98% similarity and 97% identity with the human protein. Furthermore, the predicted amino acid sequence of Abeta in tree shrews is identical to that in humans. However, immunohistochemical analysis failed to reveal beta-amyloid deposits in the neural parenchyma or vasculature of eight aged (7-8 years) tree shrews (Tupaia belangeri). The lack of correlation between the Abeta sequence and amyloid formation suggests that other factors contribute to cerebral amyloid deposition in aged animals.

This abstract at PubMed.