Hypertension increases tau hyperphosphorylation and beta-amyloid production in pigs

Poster Presentations: P4 progranulin-positive capillary densities (P<0.005). In temporal cortex, progranulin-positive capillary densities correlated with DP, but not NP or NFT (P<0.01). Conclusions: This study is the first to link progranulin to microvascular alterations in AD. These microvascular alterations were most closely associated with the earliest pathological features of Alzheimer’s in each discrete area (neurofibrillary tanlges in hippocampus and diffuse amyloid plaques in neocortex). These findings suggest that aberrant wound-healing and angiogenesis may play a role in the early pathogenesis of AD and have implications for the development of new therapeutic strategies for AD. P4-044

IMMUNOSTAINING EVIDENCE FOR ANGIOGENIC ACTIVITY IN ALZHEIMER’S DISEASE BRAIN TISSUE

James Mclarnon, Alden Ling, Nattinee Jantaratnotai, Claudia Schwab, Patrick McGeer, University of British Columbia, Vancouver, British Columbia, Canada. Background: Some evidence suggests abnormalities in cerebral microvasculature may contribute to the overall pathology in Alzheimer’s disease (AD). Perturbations in cerebral vessels include changes in structural and functional properties of vessels leading to impaired blood flow with cerebral hypoperfusion and leaky blood-brain barrier (BBB) as putative characteristic features of the disease. At present, however, the possibility that angiogenesis, the formation of new blood vessels, is present in AD brain is unclear. Methods: To address the question of angiogenic activity in AD, we have employed the transcription factor, Ets-1, a reported regulator for neovascularization in vascular endothelial cells, as a marker for vascular remodeling in AD and nondemented (ND) brain tissue. Results: Double staining immunostaining showed a significant elevation in cortical immunoreactivity for von Willebrand factor (vWF) a marker for endothelial cells, in AD, compared with ND, tissue. Ets-1 staining was also very low in hippocampal tissue from ND cases but was relatively abundant in the hippocampus of AD brain tissue. Overall less than 5% of microvessels in cortical ND tissue demonstrated Ets-1 expression; the corresponding value for AD brain tissue was in excess of 20% of vessels staining positive for the transcription factor. The patterns of Ets-1 immunostaining indicated both intravascular and extravascular expression of the factor. Subsets of Ets-1 positive microvessels in AD brain tissue showed colocalization with vascular endothelial growth factor (VEGF), a potent proangiogenic agent. Interestingly, evidence for Ets-1 activity in proximity to clusters of microglial cells was also evident in most AD cases. Conclusions: The findings indicate Ets-1 as a novel factor for denoting vascular perturbations, and possibly angiogenic activity, in AD brain and that vascular remodeling could be associated with inflammatory reactivity in the disease. P4-045

CEREBRAL ISCHEMIA-INDUCED ELEVATION OF O-GLCNACYLATION CAUSES AKT INHIBITION AND APOPTOSIS 1

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Jianhua Shi , Jinhua Gu , Inge Grundke-Iqbal , Khalid Iqbal , Fei Liu , Cheng-Xin Gong4, 1Nantong University, Nantong, China; 2Medical School of Nantong University, Nantong, China; 3New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, United States; 4New York State Institute for Basic Research, Staten Island, New York, United States. Background: Vascular factors predisposing to cerebrovascular disease or stroke are associated with and exacerbate Alzheimer’s disease (AD). Recent studies have suggested that ischemia/reperfusion injury involves O-GlcNAcylation, a posttranslational protein modification by b-N-acetylglucosamine (GlcNAc). This study is aimed to investigate the role of O-GlcNAcylation induced by cerebral ischemia in AKT signaling and neuronal cell death. Methods: O-GlcNAcylation level and apoptotic markers in mouse hippocampal cell line HT22, in mouse primary hippocampal culture cells at DIV 10 with Oxygen-Glucose deprivation (OGD) and in mouse brain tissue of middle cerebral artery occlusion (MCAO) model were measured by using Western blots or immunochemistry staining. To investigate if O-GlcNAcylation causes apoptotic events, we altered O-GlcNAcylation level via

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genetic means in HEK293FT cells and detected apoptotic markers with different methods. To study the role of O-GlcNAcylation in apoptosis, we determined AKT activity, and levels of Bad phosphorylation, cleaved Caspase 3 and PARP with Western blots. Results: We found elevated O-GlcNAcylation level and apoptosis in cultured cells with OGD and in the brains of MCAO mice. Overexpression of OGT in Hek293FT cells led to decreased cell viability, cell morphological changes such as condensed and/or fragmented nuclei, increased apoptotic cell number as determined by flow cytometry, and enhanced caspase-3 subfamily protease activities. O-GlcNAcylation decreased AKT activity by inhibition of its phosphorylation at threonine 308 and serine 473 sites. The decrease of AKT activity led to caspase 3-dependent cell apoptosis. By co-immuno-precipitation and mutagenesis, we found that AKT was O-GlcNAcylated at both threonine 308 and serine 473. AKT overexpression attenuated OGT-induced apoptotic events. In ischemic models, AKT phosphorylation was decreased that correlated to the increase of O-GlcNAcylation. Conclusions: Our results suggest that cerebral ischemia-induced elevation of O-GlcNAcylation downregulates AKT activity by inhibition of its phosphorylation and induces caspase 3-dependent neuronal apoptosis. Ischemia might exacerbate AD by this molecular mechanism. P4-046

HYPERTENSION INCREASES TAU HYPERPHOSPHORYLATION AND BETAAMYLOID PRODUCTION IN PIGS

Yu-Min Kuo, Yao-Hsiang Shih, Chu-Wan Lee, Meei-Jyh Jiang, PaoYang Lin, National Cheng Kung University, Tainan, Taiwan. Background: Alzheimer’s disease (AD) is an age-related neurodegenerative disorder. Epidemiological studies suggest that mid-age hypertension is associated with late-onset AD. However, whether hypertension is a cause for AD or merely a comorbid remains unclear. The objective of this study is to study the causal relationship between hypertension and AD. Methods: Hypertension was induced by abdominal aortic coarctation (AAC) in the seven-month-old (70 Kg - 85 Kg) Lanyu miniature pigs. The blood pressure (BP) and AD-related pathology (i.e tau hyperphosphorylation, Ab production) in the hippocampus were measured 1, 2 and 3 months after the surgery. Sham operation served as controls. Results: Two months after the surgery, the systolic, diastolic and mean BPs were higher in the AAC pigs than that of the control animals. The levels of hippocampal phosphorylated tau (p212-tau, p412-tau), hippocampal p216-GSK3b, diastolic BPs and mean BPs were positively correlated to each other. The p412-tau-postive stains were especially evident in the mossy fibers beneath the pyramidal neurons of the CA3/2 regions. The level of Akt, a GSK3b upstream kinase, was unaffected by AAC; whereas, the other kinase—PKC–was activated by AAC. Furthermore, both the levels of Ab40 and Ab42 were increased in the hippocampus 3 months after the AAC. Conclusions: These results suggest that chronic hypertension contributes to the pathogenesis of AD. P4-047

NICOTINAMIDE RIBOSIDE PROMOTES COGNITIVE FUNCTION AND SYNAPTIC PLASTICITY IN AN ALZHEIMER’S MOUSE MODEL THROUGH UP REGULATION OF PGC-1AMEDIATED BACE1 DEGRADATION

Bing Gong, Pan Yong, Lindsay Knable, Prashant Vempati, Lap Ho, Jun Wang, Giulio Pasinetti, Mount Sinai School of Medicine, New York, New York, United States. Background: Nicotinamide adenine dinucleotide (NAD)+ has been identified as a key regulator of the lifespan extending effects of calorie restriction (CR), and the activation of NAD + expression has been linked with a decrease in amyloid toxicity in Alzheimer’s disease (AD). Nicotinamide Riboside (NR) is a NAD + precursor, which is a coenzyme involved in redox activities in the mitochondrial electron transport chain and promotes peroxisome proliferator-activated receptor (PPAR)-g co-activator 1 (PGC)-1a expression in the brain. Increasing evidence has shown that PGC-1a is a crucial regulator of beta-Amyloid (Ab) clearance by affecting BACE1 degradation. In this study we tested the hypothesis that NR treatment in an AD mouse model could