The carboxy‐terminal fragment of inhibitor‐2 of protein phosphatase‐2A induces Alzheimer disease pathology and cognitive impairment

Abstract

Development of rational therapeutic treatments of Alzheimer disease (AD) requires the elucidation of the etiopathogenic mechanisms of neurofibrillary degeneration and β-amyloidosis, the two hallmarks of this disease. Here we show, employing an adeno-associated virus serotype 1 (AAV1)-induced expression of the C-terminal fragment (I(2CTF)) of I(2)(PP2A), also called SET, in rat brain, decrease in protein phosphatase 2A (PP2A) activity, abnormal hyperphosphorylation of tau, and neurodegeneration; littermates treated identically but with vector only, i.e., AAV1-enhanced green fluorescent protein (GFP), served as a control. Furthermore, there was an increase in the level of activated glycogen synthase kinase-3β and enhanced expression of intraneuronal Aβ in AAV1-I(2CTF) animals. Morris water maze behavioral test revealed that infection with AAV1-I(2CTF) induced spatial reference memory and memory consolidation deficits and a decrease in the brain level of pSer133-CREB. These findings suggest a novel etiopathogenic mechanism of AD, which is initiated by the cleavage of I(2)(PP2A), producing I(2CTF), and describe a novel disease-relevant nontransgenic animal model of AD.