(expressing mutant human APP, PS1, and tau), PS1KI (expressing human mutant PS1, but not developing any AD-like pathology), and WT mice at. 3 and 12 ...
ICAD - Abstract Submission P3: Tuesday, July 19, 2011 Poster Presentations P3 a mouse one array whole genome DNA microarray we investigated the global gene expression profile in the hippocampi obtained from 3xTgAD (expressing mutant human APP, PS1, and tau), PS1KI (expressing human mutant PS1, but not developing any AD-like pathology), and WT mice at 3 and 12 months of age (m.o.a.). Hierarchical clustering analysis was performed by using Cluster 3.0 and treeview software. Data were also analyzed with the Ingenuity Pathways Analysis (IPA) in order to achieve a classification of the results on the basis of their biological functions and disclose functional networks and/or pathways. Results: Our study investigated, with clustering analysis, the expression profile of 3xTg-AD and PS1KI mice in comparison to WT mice at 3 m.o.a as well as WT mice at 12 m.o.a. vs WT mice at 3 m.o.a. The analysis revealed that 3xTG AD mice at 3 m.o.a. and WT mice at 12 m.o.a undergo the selective upregulation of 63 transcripts that are instead found down regulated in PS1 at 3 m.o.a. The IPA analysis of the upregulated transcripts indicated that these genes were involved in: Amyloid plaques formation (APPB2, LPL) Calcium signaling (TRPM3, JAK3), Potassium channel expression (KNEC2), Neuron development and differentation (DULLARD, FGF10, JHDM1D) Nerve injury (FLT3), Neurodegenaration (NCAM, IRF1, TMEM1106B), Apoptosis (FAIM3, CSTB, ST6GAL2, TRIAP1, IRF1), Neurite formation (Neu4), Senescence (HDAC8), Cell cycle progression (HAUS8, NOL8, SNAPC2), inflammation (GPR182) and the expression of Olfactory receptors (OLFR731, OLFR958). Conclusions: We find that the over-expression of AD-related genes such as mutant APP, PS1, and tau in 3xTg-AD mice up regulate early on the expression of genes that are upregulated by aging in WT mice at 12 m.o.a. These genes are critical for amyloid dismetabolism, neuronal survival, calcium homeostasis, inflammation and aging, suggesting that the pro-AD environment present in the 3xTg-AD animal accelerates the expression of some genes that are modulated by aging. These results may help to unravel the role of gene expression in both AD progression and/or senescence. P3-209
PITAVASTATIN DECREASES TAU LEVELS VIA THE INACTIVATION OF RHO FAMILY SMALL G PROTEINS
Tadanori Hamano1, Shu-Hui Yen2, Tania Gendron3, Li-wen Ko2, Norimichi Shirafuji4, Makoto Yoneda1, Masaru Kuriyama5, 1University of Fukui, Fukui, Japan; 2Mayo Clinic Jacksonville, Jacksonville, Florida, United States; 3Mayo Clinic Jacksonville, Jacksonville, Florida, Japan; 4 Fukui Saiseikai Hospital, Fukui-city, Japan; 5Univerisity of Fukui, Fukui, Japan. Background: Epidemiological studies have shown that long-term treatment with hydroxymethylglutaryl-CoA (HMG-CoA) reductase inhibitors (statins) decreases the risk of developing Alzheimer’s disease (AD). However, this decreased risk cannot be fully explained by a reduction in cholesterol levels. Statins have pleiotropic effects by lowering the concentration of isoprenoid intermediates, including geranylgeranyl pyrophosphate and farnesyl pyrophosphate. Members of the Rho and Rab family of small G proteins require the addition of these isoprenyl moieties to their C-terminus for normal GTPase function. Although several studies have shown that statins may reduce amyloid-beta protein (Ab) levels, there have been few reports on the interaction between statins and the tau protein. Methods: M1C cells that express wild-type human brain tau (4R0N) via Tetracycline Off induction (Ko et al., J Alzheimers Dis 2004; Hamano et al., Eur J Neursci 2008; Hamano et al., IJCEP 2009) were treated with 0.5 to 10 mM of pitavastatin for 24 h. The levels of total and phosphorylated tau were examined before and after pitavastatin treatment by Western blotting and immunocytochemistry. Results: Pitavastatin reduces total and phosphorylated tau levels in a cellular model of tauopathy, as well as in primary neuronal cultures. This pitavastatin-induced tau decrease is reversed by the addition of mevalonate, or geranylgeranyl pyrophosphate. Of note, the maturation of small G proteins was found to be disrupted by pitavastatin treatment, as was the activity of glycogen synthase kinase 3b (GSK3b), a major tau kinase. Clostridium difficile toxin A, an inhibitor of glycosylation of small G proteins, decreased tau levels. Similarly, Rho kinase (ROCK) inhibitor decreased phosphorylated tau levels, and also appeared to inactivate GSK3b.
S583
Conclusions: Although the mechanisms of tau decrease by pitavastatin require further examination, this report sheds light on the metabolism of tau protein.
P3-210
Tyr 682 ON APP INTRACELLULAR DOMAIN MODULATES NGF SIGNALING
Carmela Matrone1, Luca La Rosa1, Alessia Barbagallo2, Delio Mercanti1, Moses Chao3, Pietro Calissano4, Luciano D’Adamio2, 1National Council of Research, Rome, Italy; 2Albert Einstein Medical College, New York, New York, United States; 3Skirball Institute of Biomolecular Medicine,, New York, New York, United States; 4European Brain Institute, Rome, Italy. Background: A large body of evidence indicates the imbalances in the NGF receptor signaling and/or in proNGF/NGF ratio as early cause of the cholinergic dysfunction in Alzheimer’s disease (AD) (Calissano et al., 2009). We have previously demonstrated that an NGF signaling impairment in hippocampal neurons activates the amyloidogenic APP pathways leading to Abeta deposition/accumulation and downstream toxicity (Matrone et al., 2008;2009). The physiological role of APP is poorly understood. Behavioral and plasticity studies, as well as biochemical data, indicate a role of APP in nervous system development (Ring et al., 2007; Li et al., 1997; Puzzo et al., 2008). Several evidence suggests that phosphorylation-dephosphorylation on Thr668 and Tyr682 in the cytoplasmic tail (YENTP motif) modulates APP interactions and function (Zhou et al, 2001; Tamayev et al, 2009). Moreover, APPyg mice in which Tyr682 is replaced with a Gly, shows an altered APP processing, with a reduced ß-cleavage and enhanced a-processing, but with no obvious alteration in brain and at synaptic levels (Barbagallo et al., 2010). Methods: Our studies were carried out in in vivo hippocampal slices from APPwt, APPko and APPyg mice as well as in primary cultures from APPwt mice and in ^ HEK293 cells. Transverse hippocampal slices (250 Amm) were transferred to a chamber where they were exposed to NGF and incubated at 29 C with artificial cerebrospinal fluid (ACSF) continuously bubbled with 95% O2 and 5% CO2. Hippocampal neurons were cultured according the procedures previously reported (Matrone et al., 2008;2009). Results: Here we show that NGF induces a Tyr(s) phosphorylation of APP intracellular domain. Such phosphorylation is associated to an increase in a secretase-mediated APP processing and prevented by TrkA inhibitors. Relevantly, Tyr 682 on APP YENTP motif is essential to NGF signaling, since TrkA failed to be phosphorylated and activated by NGF in APPyg mice. Moreover, APP appears to mediate TrkA availability on plasma membrane as, in absence of APP, it is preferentially localized in cytoplasmatic compartment in APPyg mice and HEK293 cells. Conclusions: These data provide evidence of a specific NGF-mediated interplay between TrkA and APP via Tyr682. This, in turn may be operative as for NGF signaling and APP physiological processing.
P3-211
HYPERACTIVATION OF PI3-KINASE-AKT SIGNALING: A CENTRAL MOLECULAR LINK BETWEEN EARLY AMULOID BETA AND TAU PATHOGENESIS IN ALZHEIMER’S DISEASE
Cora O’ Neill1, Frank LaFerla2, Meghan Coakley1, 1University College Cork, Cork, Ireland; 2University of California, Irvine, California, United States. Background: Identifying the early molecular targets that respond to Abeta and particularly those that impact on tau function is central to understanding cognitive decline and neurodegeneration in Alzheimer’s disease (AD). The PI3-K/Akt pathway is important in this regard. Firstly, several studies, including our own, show an aberrant hyperactivation of this signalling pathway in AD neurons which correlates with Braak disease stage. Importantly, Abeta induced activation of the serine threonine kinase Akt can induce phosphorylation of tau at Ser214 in vitro which potently
