too little or too late, at a point of no return for AD.We review alternative on-going drug trials and therapies for preclinical AD, that is,on asymptom- atic patients ...
Poster Presentations: P1 P1-108
WHY "AMYLOID CASCADE" IS A MISGUIDED HYPOTHESIS OF ALZHEIMER’S DEMENTIA ETIOLOGY
Jerzy W. Leszek1, Anton Scott Goustin2, Markku Kurkinen3, 1Medical University of Wroclaw, Wroclaw, Poland; 2Wayne State University, Detroit, Michigan, United States; 3Wayne State University School of Medicine, Detroit, Michigan, United States. Contact e-mail: jerzy.leszek@ umed.wroc.pl Background: Alzheimer’s dementia(AD) refers to mind disorders characterized by a progressive and irreversible memory loss and mental decline. Causes for AD are not know, and there is no cure or treatment for AD Methods: We argue, research and development of treatments for AD, the way it has been done,is too limited and takes too long time to have any impact on the disease. We revisit recent clinical drug trials to understand why the trials failed and,indeed, why they could not have succeeded in the first place. Results: Did the trials fail simply because our ideas about AD etiology are not correct.Did the trials fail because what was done was too little or too late, at a point of no return for AD.We review alternative on-going drug trials and therapies for preclinical AD, that is,on asymptomatic patients and people at risk, designed to prevent or slow the progression of AD Conclusions: We predict these trials are going to fail too because amyloid plaques and neurofibrillary tangles are not causing AD but are the outcome of brain cells dying. P1-109
MITOCHONDRIAL DYSFUNCTION INDUCED BYA POSTTRANSLATIONALLY MODIFIED AMYLOID LINKED TO A FAMILIAL MUTATION IN AN ALTERNATIVE MODEL OF NEURODEGENERATION
Krysti Todd, Agueda Rostagno, Jorge Ghiso, NYU School of Medicine, New York, New York, United States. Contact e-mail: krysti.todd@ med.nyu.edu Background: Familial British dementia (FBD) is an early-onset non-amyloid beta (Abeta) cerebral amyloidosis that presents with severe cognitive decline and strikingly similar neuropathological features to those present in Alzheimer’s disease (AD). FBD is associated with a single nucleotide transition (T to A) in the stop codon of a gene encoding BRI2, leading to the production of an elongated precursor protein, ABriPP. Following furin-like proteolytic processing at its C-terminus, ABriPP releases a longer than normal 34 amino acid peptide, ABri, exhibiting amyloidogenic properties not seen in its 23 amino acid physiologic counterpart Bri1-23. Deposited ABri exhibits abundant posttranslational pyroglumate (pE) formation at the N-terminus, as with truncated forms of Abeta found in AD deposits, and coexists with neurofibrillary tangles morphologically and biochemically identical to those found in AD. Here we aim to use FBD as an alternative model to elucidate the effect of familial mutations and posttranslational modifications on the relationship between amyloid structure and toxicity and assess whether common detrimental cellular pathways to those elicited by Abeta are targeted. Methods: The structural properties of ABri and Bri1-23 peptide variants were evaluated using various biochemical and biophysical techniques.SH-SY5Y human neuroblastoma cells were challenged with the ABri, Bri1-23, and Abeta peptides followed by examination of resulting alterations in mitochondrial function and neurotoxicity. Results: The presence of N-terminal pyroglutamate conferred to the ABri molecule enhanced and accelerated aggregation/fibrillization properties and hydrophobicity, while Bri1-23 pE/E lacked these characteristics. Accordingly, ABri pE, but not ABri E or Bri1-23 pE/E, induced oxidative stress and a loss of mitochondrial membrane potential in SH-SY5Y neuronal cells. This mitochondrial dysfunction culminated in the release of cytochrome c and activation of caspase-mediated apoptotic mechanisms in a manner comparable to that of cells challenged with Abeta. Conclusions: Structural alterations of the ABri peptide induced by the FBD mutation combined with pE posttranslational modification often present in other protein folding disorders resulted in neurotoxicity with involvement of oxidative stress, mitochondrial dysfunction, and activation of caspase-mediated cell death mechanisms. Overall, the
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results highlight a combined detrimental effect of familial mutations and posttranslational modifications in the molecular pathogenesis of neurodegenerative disorders. P1-110
ASSESSING THE POTENTIAL RISK OF SILICA NANOPARTICLE EXPOSURE IN DEVELOPING ALZHEIMER’S-LIKE PATHOLOGY
Quan Ma, Xifei Yang, Chune He, Jianjun Liu, Shenzhen Center for Disease Control and Prevention, Shenzhen, China. Contact e-mail: mquan999@ 126.com Background: Silica nanoparticles (SiNPs) are among nanomaterials with the highest total output in the industry and have been formulated for cellular and non-viral gene delivery in the central nerve system. However, the potential neurotoxicity of SiNPs remains largely unclear. Methods: CCK-8 assay was performed to assess cell viability. Transmission electron microscopy (TEM) was used to reveal the distribution of SiNPs. Hoech st33342/PI and TUNEL staining was performed to measure apoptosis. Immunofluorescent staining was performed to measure the change of Ab 1-42. Western-blot analysis was performed to measure the phosphorylation of tau. Results: In this study, we showed by transmission electron microcopy uptake of SiNPs by human SK-N-SH and mouse neuro2 a neuroblastoma cells treated with 10.0 mg/ ml of 15-nm SiNPs for 24h. SiNPs were mainly localized in the cytoplasm of the cells. The treatment of SiNPs of various concentrations impaired the morphology ofSK-N-SH and N2a cells, characterized by increased number of round cells, diminishing of dendrite-like processes and decreased cell density. SiNPs significantly decreased the cell viability, induced cellular apoptosis, and elevated the levels of intracellular reactive oxygen species (ROS) in a dose-dependent manner in both cell lines. Additionally, increased deposit of intracellular b-amyloid1-42(Ab 1-42) and enhanced phosphorylation of tau at Ser262 and Ser396, two specific pathological hallmarks of Alzheimer’s disease (AD), were observed in SK-N-SH and N2a cells treated with SiNPs. Concomitantly, the expression of amyloid precursor protein (APP) was up-regulated, while amyloid-b-degrading enzyme neprilysin was down-regulated in SiNP-treated cells. Activity-dependent phosphorylation of glycogen syntheses kinase(GSK)-3b at Ser9 (in active form) was significantly decreased in SiNP-treated SK-N-SH cells. Conclusions:Taken together, these data demonstrated that exposure to SiNPs induced neurotoxicity and pathological signs of AD. Thepre-Alzheimer-like pathology induced by SiNPs might result from the dys-regulated expression of APP/neprilysin and activation of GSK-3b. This is the first study providing evidence indicating that in addition to neurotoxicity induced by SiNPs, the application of SiNPs might increase the risk of developing AD. Acknowledgements: This work was supported by the Upgrade Scheme of Shenzhen Municipal Key Laboratory (ZDSY20120615085804889,CXB201005260068A). Keyword: Silica nanoparticles (SiNPs); Neurotoxicity; Alzheimer’sdisease(AD); bamyloid(Ab); Tau. P1-111
PHOSPHOLIPID TRANSFER PROTEIN IS EXPRESSED AND INVOLVED IN HDL BIOGENESIS AND REMODELING AT THE BLOOD-BRAIN BARRIER
Anil Manavalan Paul1, Elham Fanaee-Danesh2, Alexandra Kober3, Martina Zandl4, Jyotsna Pippal5, Ute Panzenboeck2, 1Medical University, Graz, Austria; 2Institute of Pathophysiology and Immunology, Graz, Austria; 3Institute of Pathophysiology and Immunology, Medical University of Graz, Graz, Austria; 4Institute of Pathophysiology and Immunology, Medical University of Graz, Graz, Austria; 5Institut f€ur Pathophysiologie und Immunologie, Graz, Austria. Contact e-mail: elham.fanaee-danesh@ stud.medunigraz.at Background: High plasma high-density lipoproteins (HDL) protect against neurodegenerative disease. However, the underlying mechanisms are largely unexplored. Phospholipid transfer protein (PLTP) is a key protein involved in plasma HDL remodeling and is thought to influence pathogenesis of Alzheimer’s disease. We reported earlier that liver-X receptor (LXR) activation promotes cellular cholesterol efflux and formation of HDL-like
