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Epigenetic regulation of tau gene expression
Oral O3-06: Prevalence and Trends
O3-05-06
EPIGENETIC REGULATION OF TAU GENE EXPRESSION
Gavin Meredith1, Anthony D’Ippolito2, George Marnellos1, Christopher Phiel2, 1Life Technologies, Carlsbad, Calif., United States; 2 Ohio State University, Columbus, Ohio, United States. Background: The formation of neurofibrillary tangles is one of the characteristic features in the brains of patients with Alzheimer’s disease. Hyperphosphorylation of tau protein by kinases such as Gsk-3 have been implicated in neurodegeneration. As such, small molecule inhibitors of Gsk-3 have been pursued as a potential therapeutics in the effort to slow or prevent neurodegeneration. Methods: Taq Man qPCR was performed on RNA isolated from wild-type and Gsk-3-deficient mouse embryonic stem cells. A role for Gsk-3 in DNA methylation at the Mapt locus was revealed by isolation of total genomic methylated DNA from wild-type and Gsk-3-deficient mouse embryonic stem cells using the Methyl Miner kit. Libraries of methylated DNA were created, and whole-genome sequencing was performed on a SOLiD machine. Bioinformatic analysis of data identified regions of the mouse genome that were differentially methylated in the Gsk-3-deficient cells. Results: Here we present data showing that Gsk-3 activity also regulates the expression of tau mRNA. Tau mRNA expression is reduced by more than 80% in Gsk-3 deficient cells. This reduction in gene expression is accompanied by changes in DNA methylation at the Mapt locus. Conclusions: These data suggest that inhibition of Gsk-3 activity not only affects tau phosphorylation, but also provides a second layer of possible beneficial effects by reducing the expression of tau mRNA. Finally, the role of DNA methylation in regulating tau gene expression affords a novel therapeutic approach to preventing tangle-related neurodegeneration. O3-05-07
THE RELATIONSHIP BETWEEN BETA-AMYLOID PROTEIN PRECURSOR AND TAU IN ALZHEIMER’S DISEASE-RELATED IRON DISRUPTION
James Duce1, Peng Lei1, Andrew Tsatsanis1, Scott Ayton1, Linh Lam1, Paul Adlard2, Giuseppe Ciccotosto3, Colin Masters4, Roberto Cappai3, Kevin Barnham5, Jack Rogers6, David Finkelstein1, Ashley Bush7, 1Mental Health Research Institute, Melbourne, Australia; 2The Mental Health Research Institute, Melbourne, Australia; 3The University of Melbourne, Melbourne, Australia; 4MHRI, Melbourne, VIC, Australia; 5The University of Melbourne, Parkville, Australia; 6Massachusetts General Hospital, Charlestown, Massachusetts, United States; 7Mental Health Research Institute, University of Melbourne, Melbourne, Australia. Background: Alzheimer’s disease (AD) is complicated by pro-oxidant neuronal Fe2+ elevation adjacent toneurofibrillary tangles composed of the microtubule-associated protein tau and extracellularzinc accumulation in beta-amyloid containing plaques. Cellulariron homeostasis is tightly regulated as unbound iron catalyzes the production of toxic reactive oxygen species. Ferroxidases oxidize Fe2+ to Fe3+and are essential for maintaining intracellular iron homeostasis, partlythrough ferroportin binding on the cell surface. Correlated with increasediron, ferroxidase activities may be disrupted with age and exacerbated in neurodegenerative diseases. Methods: Amyloid precursor protein (APP) ferroxidase activity andit’s inhibition by zinc was determined through a variety of assays measuring aproteins ability to alter Fe2+ levels. To confirm the role of APP and tau in iron homeostasis, APP-/- and tau -/neuronal cultures and whole animals were analyzed by a variety of techniques monitoring iron status and interaction with other known iron efflux proteins. Human post-mortem analysis alsodetermined ferroxidase activity and iron content in correlation with diseaseonset. Results: H-ferritin-like ferroxidase activity in APP facilitates the efflux of iron from the neuron via its transport to the cell surface whereit interacts with the iron exporter; ferroportin. Deletion of APP induces intracellulariron accumulation. However, zinc also directly inhibits APP ferroxidaseactivity and abnormal cortical zinc buffering, via beta-amyloid transfer in the AD brain, may link amyloid pathology with neuronal iron accumulation. Iron dyshomeostasis may alsobe exacerbated through tau’s role in APP trafficking to the cell surface. Deletion of tau from primary neurons decreased cell surface APP expression, causing aniron export lesion that resulted in an age-dependent neuronal iron accumulation
S509
paralleling APP deficient studies. Conclusions: Results are consistent with APP being able to modify the intracellular labile iron pool but that tau is required to transport the enzyme to its correct location. Mislocalization of either protein as well as zinc have major implications on disrupted APP ferroxidase activity with age and AD. Collectively, these data indicate a new relationship between two characteristic AD-related proteins and how disruption in either or both functions can lead to pro-oxidant neuronal Fe2+ elevation. O3-05-08
NOVEL PRIONIC AND ANTI-PRIONIC MECHANISMS IN ALZHEIMER’S DISEASE
Dale Bredesen1, Veronique Corset2, Clare Peters-Libeu3, Patricia Spilman4, Karen Poksay3, Olivier Descamps3, Olivia Gorostiza3, Varghese John3, Patrick Mehlen5, 1Buck Institute for Age Research, Novato, Calif., United States; 2CNRS UMR, 28, Rue Laennec, France; 3The Buck Institute for Research on Aging, Novato, Calif., United States; 4Buck Institute for Research on Aging, Novato, Calif., United States; 5CNRS FRE, Lyon, France. Background: Previous studies have shown that the amyloid-beta (Abeta) peptides that collect in the brains of patients with Alzheimer’s disease (AD) exhibit a prionic effect. We and others have shown that amyloid precursor protein (APP) may be processed proteolytically in two mutually antagonistic ways: cleavage at the beta, gamma, and caspase sites produces four peptides that mediate neurite retraction, synapse loss, and programmed cell death. In contrast, cleavage at the alpha site results in two peptides that mediate neurite extension, synaptic maintenance, and anti-apoptotic signaling. Thus APP may function as a molecular switch involved in plasticity. We now report that the decision between these two alternative cleavage pathways of APP is governed by ligand binding. Furthermore, we show that Abeta peptide is a direct inhibitor of APP cleavage by ADAM-10. Methods: In order to determine what effect the interaction of Abeta peptide has on the processing of APP, we added rat Abeta 1-40 to primary cultures of hippocampal neurons from PDAPP J20 transgenic mice, and then assayed human Abeta 1-42 with an ELISA specific for human Abeta1-42. To determine whether Abeta has a direct effect on ADAM-10 cleavage of APP, we utilized a chimeric protein, MBP-C125, which consists of the maltose binding protein fused to the C-terminal 125 residues of APP. Results: Rat Abeta 1-40 increased the human Abeta 1-42 by over two-fold in primary cultures of J20 hippocampal neurons. However, netrin-1 reduced the net production of human Abeta1-42. The prionic effect of adding Abeta 1-40 was tempered by the presence of netrin-1. MBP-C125 was cleaved by ADAM10. However, this cleavage was inhibited by Abeta1-40. This inhibitory effect was not due to competition for the ADAM10, since Abeta 1-40 was not effectively cleaved in the presence of APP. In both B103 and H4 cells, Abeta reduced sAPPalpha, whereas netrin-1 increased sAPP alpha. p75NTR, which interacts with APP, displayed an additive effect with Abeta on the reduction of sAPP alpha. Conclusions: Abeta peptide displays prionic-i.e., positive feedback-effects, utilizing a novel mechanism that involves protease inhibition. Our results also describe the first endogenous antiprion: netrin-1 reduces the Abeta-APP prionic loop production of Abeta. TUESDAY, JULY-19, 2011 ORAL O3-06 PREVALENCE AND TRENDS O3-06-01
THE 10/66 DEMENTIA RESEARCH GROUP COHORT STUDIES IN MIDDLE INCOME COUNTRIES: DEMENTIA INCIDENCE AND MORTALITY IN LATIN AMERICA AND CHINA
Martin Prince1, Daisy Acosta2, Cleusa Ferri1, Mariella Guerra3, Yueqin Huang4, Juan Llibre Rodriguez5, Aquiles Salas6, Ana Sosa7, 1King’s College London, London, United Kingdom; 2Universidad Nacional Pedro Henriquez Ure~na, Santo Domingo, Dominican Republic; 3National Institute of Mental Health, Lima, Peru; 4Peking University, Beijing, China; 5Medical University of Havana, Havana, Cuba; 6Universidad Central de Venezuela, Caracas, Venezuela; 7National Institute of Neurology and Neurosurgery of Mexico, National Autonomous University of Mexico, Mexico City, Mexico. Background: Impressions that the prevalence of dementia may be lower in low and middle (LMIC), compared with high income countries (HIC) were qualified
O3-05-06
EPIGENETIC REGULATION OF TAU GENE EXPRESSION
Gavin Meredith1, Anthony D’Ippolito2, George Marnellos1, Christopher Phiel2, 1Life Technologies, Carlsbad, Calif., United States; 2 Ohio State University, Columbus, Ohio, United States. Background: The formation of neurofibrillary tangles is one of the characteristic features in the brains of patients with Alzheimer’s disease. Hyperphosphorylation of tau protein by kinases such as Gsk-3 have been implicated in neurodegeneration. As such, small molecule inhibitors of Gsk-3 have been pursued as a potential therapeutics in the effort to slow or prevent neurodegeneration. Methods: Taq Man qPCR was performed on RNA isolated from wild-type and Gsk-3-deficient mouse embryonic stem cells. A role for Gsk-3 in DNA methylation at the Mapt locus was revealed by isolation of total genomic methylated DNA from wild-type and Gsk-3-deficient mouse embryonic stem cells using the Methyl Miner kit. Libraries of methylated DNA were created, and whole-genome sequencing was performed on a SOLiD machine. Bioinformatic analysis of data identified regions of the mouse genome that were differentially methylated in the Gsk-3-deficient cells. Results: Here we present data showing that Gsk-3 activity also regulates the expression of tau mRNA. Tau mRNA expression is reduced by more than 80% in Gsk-3 deficient cells. This reduction in gene expression is accompanied by changes in DNA methylation at the Mapt locus. Conclusions: These data suggest that inhibition of Gsk-3 activity not only affects tau phosphorylation, but also provides a second layer of possible beneficial effects by reducing the expression of tau mRNA. Finally, the role of DNA methylation in regulating tau gene expression affords a novel therapeutic approach to preventing tangle-related neurodegeneration. O3-05-07
THE RELATIONSHIP BETWEEN BETA-AMYLOID PROTEIN PRECURSOR AND TAU IN ALZHEIMER’S DISEASE-RELATED IRON DISRUPTION
James Duce1, Peng Lei1, Andrew Tsatsanis1, Scott Ayton1, Linh Lam1, Paul Adlard2, Giuseppe Ciccotosto3, Colin Masters4, Roberto Cappai3, Kevin Barnham5, Jack Rogers6, David Finkelstein1, Ashley Bush7, 1Mental Health Research Institute, Melbourne, Australia; 2The Mental Health Research Institute, Melbourne, Australia; 3The University of Melbourne, Melbourne, Australia; 4MHRI, Melbourne, VIC, Australia; 5The University of Melbourne, Parkville, Australia; 6Massachusetts General Hospital, Charlestown, Massachusetts, United States; 7Mental Health Research Institute, University of Melbourne, Melbourne, Australia. Background: Alzheimer’s disease (AD) is complicated by pro-oxidant neuronal Fe2+ elevation adjacent toneurofibrillary tangles composed of the microtubule-associated protein tau and extracellularzinc accumulation in beta-amyloid containing plaques. Cellulariron homeostasis is tightly regulated as unbound iron catalyzes the production of toxic reactive oxygen species. Ferroxidases oxidize Fe2+ to Fe3+and are essential for maintaining intracellular iron homeostasis, partlythrough ferroportin binding on the cell surface. Correlated with increasediron, ferroxidase activities may be disrupted with age and exacerbated in neurodegenerative diseases. Methods: Amyloid precursor protein (APP) ferroxidase activity andit’s inhibition by zinc was determined through a variety of assays measuring aproteins ability to alter Fe2+ levels. To confirm the role of APP and tau in iron homeostasis, APP-/- and tau -/neuronal cultures and whole animals were analyzed by a variety of techniques monitoring iron status and interaction with other known iron efflux proteins. Human post-mortem analysis alsodetermined ferroxidase activity and iron content in correlation with diseaseonset. Results: H-ferritin-like ferroxidase activity in APP facilitates the efflux of iron from the neuron via its transport to the cell surface whereit interacts with the iron exporter; ferroportin. Deletion of APP induces intracellulariron accumulation. However, zinc also directly inhibits APP ferroxidaseactivity and abnormal cortical zinc buffering, via beta-amyloid transfer in the AD brain, may link amyloid pathology with neuronal iron accumulation. Iron dyshomeostasis may alsobe exacerbated through tau’s role in APP trafficking to the cell surface. Deletion of tau from primary neurons decreased cell surface APP expression, causing aniron export lesion that resulted in an age-dependent neuronal iron accumulation
S509
paralleling APP deficient studies. Conclusions: Results are consistent with APP being able to modify the intracellular labile iron pool but that tau is required to transport the enzyme to its correct location. Mislocalization of either protein as well as zinc have major implications on disrupted APP ferroxidase activity with age and AD. Collectively, these data indicate a new relationship between two characteristic AD-related proteins and how disruption in either or both functions can lead to pro-oxidant neuronal Fe2+ elevation. O3-05-08
NOVEL PRIONIC AND ANTI-PRIONIC MECHANISMS IN ALZHEIMER’S DISEASE
Dale Bredesen1, Veronique Corset2, Clare Peters-Libeu3, Patricia Spilman4, Karen Poksay3, Olivier Descamps3, Olivia Gorostiza3, Varghese John3, Patrick Mehlen5, 1Buck Institute for Age Research, Novato, Calif., United States; 2CNRS UMR, 28, Rue Laennec, France; 3The Buck Institute for Research on Aging, Novato, Calif., United States; 4Buck Institute for Research on Aging, Novato, Calif., United States; 5CNRS FRE, Lyon, France. Background: Previous studies have shown that the amyloid-beta (Abeta) peptides that collect in the brains of patients with Alzheimer’s disease (AD) exhibit a prionic effect. We and others have shown that amyloid precursor protein (APP) may be processed proteolytically in two mutually antagonistic ways: cleavage at the beta, gamma, and caspase sites produces four peptides that mediate neurite retraction, synapse loss, and programmed cell death. In contrast, cleavage at the alpha site results in two peptides that mediate neurite extension, synaptic maintenance, and anti-apoptotic signaling. Thus APP may function as a molecular switch involved in plasticity. We now report that the decision between these two alternative cleavage pathways of APP is governed by ligand binding. Furthermore, we show that Abeta peptide is a direct inhibitor of APP cleavage by ADAM-10. Methods: In order to determine what effect the interaction of Abeta peptide has on the processing of APP, we added rat Abeta 1-40 to primary cultures of hippocampal neurons from PDAPP J20 transgenic mice, and then assayed human Abeta 1-42 with an ELISA specific for human Abeta1-42. To determine whether Abeta has a direct effect on ADAM-10 cleavage of APP, we utilized a chimeric protein, MBP-C125, which consists of the maltose binding protein fused to the C-terminal 125 residues of APP. Results: Rat Abeta 1-40 increased the human Abeta 1-42 by over two-fold in primary cultures of J20 hippocampal neurons. However, netrin-1 reduced the net production of human Abeta1-42. The prionic effect of adding Abeta 1-40 was tempered by the presence of netrin-1. MBP-C125 was cleaved by ADAM10. However, this cleavage was inhibited by Abeta1-40. This inhibitory effect was not due to competition for the ADAM10, since Abeta 1-40 was not effectively cleaved in the presence of APP. In both B103 and H4 cells, Abeta reduced sAPPalpha, whereas netrin-1 increased sAPP alpha. p75NTR, which interacts with APP, displayed an additive effect with Abeta on the reduction of sAPP alpha. Conclusions: Abeta peptide displays prionic-i.e., positive feedback-effects, utilizing a novel mechanism that involves protease inhibition. Our results also describe the first endogenous antiprion: netrin-1 reduces the Abeta-APP prionic loop production of Abeta. TUESDAY, JULY-19, 2011 ORAL O3-06 PREVALENCE AND TRENDS O3-06-01
THE 10/66 DEMENTIA RESEARCH GROUP COHORT STUDIES IN MIDDLE INCOME COUNTRIES: DEMENTIA INCIDENCE AND MORTALITY IN LATIN AMERICA AND CHINA
Martin Prince1, Daisy Acosta2, Cleusa Ferri1, Mariella Guerra3, Yueqin Huang4, Juan Llibre Rodriguez5, Aquiles Salas6, Ana Sosa7, 1King’s College London, London, United Kingdom; 2Universidad Nacional Pedro Henriquez Ure~na, Santo Domingo, Dominican Republic; 3National Institute of Mental Health, Lima, Peru; 4Peking University, Beijing, China; 5Medical University of Havana, Havana, Cuba; 6Universidad Central de Venezuela, Caracas, Venezuela; 7National Institute of Neurology and Neurosurgery of Mexico, National Autonomous University of Mexico, Mexico City, Mexico. Background: Impressions that the prevalence of dementia may be lower in low and middle (LMIC), compared with high income countries (HIC) were qualified