The Journal of Neuroscience, April 1, 2001, 21(7):2240-2246
S100
Interaction with Tau Is Promoted by Zinc and Inhibited by
Hyperphosphorylation in Alzheimer's Disease
W. Haung
Yu1, 2 and
Paul E.
Fraser1, 3
1 Centre for Research in Neurodegenerative Diseases,
2 Department of Pharmacology, and 3 Department
of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
M5S 3H2
The zinc-binding protein S100
has been identified as an
interacting partner with the microtubule-associated protein tau. Both
proteins are individually affected in Alzheimer's disease (AD).
S100
, is overexpressed in the disease, whereas hyperphosphorylated tau constitutes the primary component of neurofibrillary tangles. In
this study, we examine factors that modulate their binding and the
potential role the complex may play in AD pathogenesis. Zinc was
identified as a critical component in the binding process and a primary
modulator of S100
-associated cellular responses. Abnormally
phosphorylated tau extracted from AD tissue displayed a dramatically
reduced capacity to bind S100
, which was restored by pretreatment
with alkaline phosphatase. In differentiated SH-SY5Y cells, exogenous
S100
was internalized and colocalized with tau consistent with an
intracellular association. This was enhanced by the addition of zinc
and eliminated by divalent metal chelators. S100
uptake was also
accompanied by extensive neurite outgrowth that may be mediated by its
interaction with tau. S100
-tau binding may represent a key pathway
for neurite development, possibly through S100
modulation of tau
phosphorylation and/or functional stabilization of microtubules and
process formation. S100
-tau interaction may be disrupted by
hyperphosphorylation and/or imbalances in zinc metabolism, and this may
contribute to the neurite dystrophy associated with AD.
Key words:
S100
; tau; Alzheimer's disease; zinc; binding; colocalization; neuronal development
Copyright © 2001 Society for Neuroscience 0270-6474/01/2172240-07$05.00/0