Analysis of N-glycans of pathological tau: possible occurrence of aberrantprocessing of tau in Alzheimer's disease

In a previous study [Wang et al, (1996) Nat, Med, 2, 871-875], Wang et al, found (i) that abnormally hyperphosphorylated tau (AD P-tau) isolated from Alzheimer's disease (AD) brain as paired helical Filaments (PHF)-tau and as cytosolic AD P-tau but not tau from normal brain were stained by lectins, and (ii) that on in vitro deglycosylation the PHF untwisted into sheets of thin straight filaments, suggesting that tau only in AD brains is glycosyla ted, To elucidate the primary structure of N-glycans, we comparatively anal yzed the N-glycan structures obtained from PHF-tau and AD P-tau, More than half of N-glycans found in PHF-tau and AD P-tau were different, High mannos e-type sugar chains and truncated N-glycans were found in both taus in addi tion to a small amount of sialylated bi- and triantennary sugar chains. Mor e truncated glycans were richer in PHF-tau than AD P-tau, This enrichment o f more truncated glycans in PHF might be involved in promoting the assembly and or stabilizing the pathological fibrils in AD. (C) 2001 Published by E lsevier Science B.V. on behalf of the Federation of European Riochemical So cieties.