- Email: [email protected]
Role of the BDNF Val66Met polymorphism in hippocampal synaptic plasticity
Poster Presentations P1 determine if changes in energy balance, induced by consumption of a high-fat diet, alter the onset and progression of AD-like features in a triple transgenic (3xTgAD) mouse model. 3xTgAD mice over-express human amyloid precursor protein (APPSwe), presenilin-1 (PS-1M146V) and tauP301, and develop progressive age-dependent cognitive deficits as well as amyloid-beta plaque pathology and neurofibrillary tangles. Methods: Male 3xTgAD and non transgenic control mice (Non-Tg) mice were placed on a 60% high-fat or chow diet at 2 months of age. Body weight and food intake was monitored weekly. In separate groups of mice at 3-4, 7-8 and 11-12 months of age, cognitive function was assessed using Y-maze spontaneous alternation (SA) and Morris water maze (MWM) tasks. Results: Body weight was significantly increased in high fat groups at all time points. 3xTgAD mice on a chow diet displayed deficits compared to Non-Tg control mice on a chow diet in MWM task from 3-4 months and in the SA task from 11-12 months of age. Highfat diet had no significant effect on memory in 3xTgAD mice compared to 3xTgAD mice on chow at any age. In contrast Non-Tg control mice on high-fat diet performed significantly worse in MWM at 7-8 months and in SA at 11-12 months compared to Non-Tg mice on a control chow diet. Conclusions: These results indicate that a high-fat diet for up to 10 months of age has no effect on memory in a transgenic mouse model of AD with existing memory deficits. However, in contrast, a high-fat diet causes memory impairments in mice with normal cognitive performance. P1-155
ROLE OF THE BDNF VAL66MET POLYMORPHISM IN HIPPOCAMPAL SYNAPTIC PLASTICITY
Ipe Ninan1, Karishma Dagar2, Rosalia Perez-Castro2, Mark R. Plummer3, Francis S. Lee4, Moses V. Chao2, 1Department of Psychiatry, NYU School of Medicine, New York, NY, USA; 2Skirball Institute, NYU School of Medicine, New York, NY, USA; 33Department of Cell Biology and Neuroscience, Rutgers University, New Jersey, NJ, USA; 4Department of Psychiatry, Weill Medical College of Cornell University, New York, NY, USA. Contact e-mail: [email protected] Background: The Val66Met polymorphism in the Brain-Derived Neurotrophic Factor (BDNF) gene has been recently linked to Alzheimer’s disease. Also, the BDNF Val66Met polymorphism affects episodic memory and affective behaviors, and results in a defect in regulated release of BDNF. Methods: Given the purported role of hippocampal synaptic plasticity in memory, we examined synaptic neurotransmission and plasticity in the hippocampal CA3-CA1 synapses of BDNFMet/Met mice. Results: Although basal synaptic neurotransmission was normal, both young and adult mice had shown significant impairment of long-term potentiation which was NMDA receptor-dependent. We also found that NMDA receptor-dependent long-term depression was impaired in the BDNFMet/Met mice. However, mGluR-dependent long-term depression was normal in the BDNFMet/Met mice. Consistent with the NMDA receptor-dependent synaptic plasticity impairment, we observed a significant decrease in NMDA receptor neurotransmission in the CA1 pyramidal neurons of BDNFMet/Met mice. Conclusions: Thus, the BDNF Val66Met polymorphism causes an impairment of NMDA receptor neurotransmission and synaptic plasticity in the hippocampus. The effect of BDNF Val66Met polymorphism on hippocampal synaptic plasticity might play a role in cognitive dysfunction in Alzheimer’s disease. P1-156
TAU PROTEIN AGGREGATES INDUCE DYSREGULATION OF GENE EXPRESSION IN SPECIFIC BRAIN REGIONS OF RAT MODEL OF TAUOPATHY
Peter Filipcik1, Martin Cente1, Juraj Kucerak1, Branislav Kovacech1, Rostislav Skrabana1, Michal Novak1,2, 1Institute of Neuroimmunology, Bratislava, Slovakia; 2Axon Neuroscience GmbH, Vienna, Austria. Contact e-mail: [email protected] Background: Protein aggregates are common feature of several neurodegenerative diseases. Tauopathies including Alzheimer’s disease are well characterized by intracellular accumulation of microtubule associated protein tau in the form of paired helical filaments, which leads to the formation of neurofibrillary tangles (NFT). Transgenic rat expressing truncated tau exerts
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high load of NFT’s and therefore represent an ideal model for study of molecular events associated with generation and/or elimination of these lesions from affected brain regions. Methods: Transcriptional analysis of specific brain regions was performed using PCR arrays. Contra lateral side of the brain was used for biochemical analysis. Phosphorylation profile of tau protein was determined in soluble and sarcosyl insoluble fraction of endogenous and transgenic tau by western blot using specific AD associated markers. Results: Analysis of transcription level of specific groups of genes coding for proteins involved in the processes of neurotoxicity, inflammation and signal transduction led to identification of several significantly dysregulated genes. The expression of genes, which were up-regulated more than 2 fold in aged animals were investigated in the course of neurofibrilary degeneration of the transgenic rat model. The data suggest that level of gene transcripts for several stress associated and immune markers such as HSP27, complement component C3, and CD18 correlate with the load of NFT’s in aged transgenic animals expressing truncated tau protein. Interestingly expression of none of the tested tau protein kinases such as GSK3beta, MAPK and cdk5 kinase was found dysregulated when compared to control non-transgenic animals. Conclusions: Based on the correlation between levels of AD specific biomarkers and expression levels of tested genes we have estimated temporal order of biological events during development of neurofibrilary pathology. Our data point to massive expression of immune markers as a consequence of neurodegeneration. P1-157
MODELING ALZHEIMER’S DISEASE IN DROSOPHILA MELANOGASTER FOR LARGESCALE COMPOUND SCREENING
Matt B. Mahoney, Lenard Diggins, Marianna Foos, Emily Lund, James Mediatore, Phil O’Neil, Jim Symonds, Alfred T. Villaluz, Carol M. Singh, Vitruvean, LLC, Watertown, MA, USA. Contact e-mail: [email protected] Background: Alzheimer’s disease (AD), the most prevalent of neurodegenerative diseases, is growing increasingly common in the elderly, gradually depriving them of memory and cognitive function. Hallmarks of the disease include severe dementia, seemingly associated with amyloid plaques and neurofibrillary tangles in the CNS. However, the mechanisms that cause AD are not completely understood. Currently, there are no treatments that effectively ameliorate or abate disease progression, although many candidates are in clinic trials. Over the past decade, the fruit fly, Drosophila melanogaster, has been used as a vehicle for AD research, typically as an implement for identification and validation of targets. More recently, Drosophila have been used to test potential therapeutics for efficacy. Methods: Vitruvean, LLC has developed a Drosophila-based, medium-throughput behavioral screening platform for discovery and validation of compound treatments for neurodegenerative diseases, including Alzheimer’s, Parkinson’s, and Huntington’s diseases. Vitruvean uses this automated system to screen compounds for modification of progressively degenerating climbing phenotypes. We are currently investigating multiple models of AD, generated by overexpressing derivatives and variations of human APP and human tau transgenes in the fly CNS. Results: Using the PhenoScreen system, we were able to identify histone deacetylase inhibitors (TSA, SAHA), gamma-secretase inhibitors (Compound E), aggregation inhibitors (Methylene Blue), and cholinesterase inhibitors (Physostigmine, Tacrine) as being positive in one or more of our AD models. Such compounds have been previously shown to have positive effects in other AD model systems. Furthermore, we have been able to profile compound effects on behavior over multiple Drosophila AD models, providing us with information regarding which pathway they may affect. We were also able to assess some of these compounds in a Huntington’s disease line in hopes of further understanding their mechanisms. Conclusions: We demonstrate the utility of different Drosophila models of AD that are amenable to use in the PhenoScreen platform for drug discovery and validation. We have shown that potentially therapeutic compound classes can be used to reverse the degenerating behavior in multiple AD models highlighting different aspects of the disease. We believe that this screening system and this battery of fly models can be used to facilitate drug discovery for Alzheimer’s disease.
ROLE OF THE BDNF VAL66MET POLYMORPHISM IN HIPPOCAMPAL SYNAPTIC PLASTICITY
Ipe Ninan1, Karishma Dagar2, Rosalia Perez-Castro2, Mark R. Plummer3, Francis S. Lee4, Moses V. Chao2, 1Department of Psychiatry, NYU School of Medicine, New York, NY, USA; 2Skirball Institute, NYU School of Medicine, New York, NY, USA; 33Department of Cell Biology and Neuroscience, Rutgers University, New Jersey, NJ, USA; 4Department of Psychiatry, Weill Medical College of Cornell University, New York, NY, USA. Contact e-mail: [email protected] Background: The Val66Met polymorphism in the Brain-Derived Neurotrophic Factor (BDNF) gene has been recently linked to Alzheimer’s disease. Also, the BDNF Val66Met polymorphism affects episodic memory and affective behaviors, and results in a defect in regulated release of BDNF. Methods: Given the purported role of hippocampal synaptic plasticity in memory, we examined synaptic neurotransmission and plasticity in the hippocampal CA3-CA1 synapses of BDNFMet/Met mice. Results: Although basal synaptic neurotransmission was normal, both young and adult mice had shown significant impairment of long-term potentiation which was NMDA receptor-dependent. We also found that NMDA receptor-dependent long-term depression was impaired in the BDNFMet/Met mice. However, mGluR-dependent long-term depression was normal in the BDNFMet/Met mice. Consistent with the NMDA receptor-dependent synaptic plasticity impairment, we observed a significant decrease in NMDA receptor neurotransmission in the CA1 pyramidal neurons of BDNFMet/Met mice. Conclusions: Thus, the BDNF Val66Met polymorphism causes an impairment of NMDA receptor neurotransmission and synaptic plasticity in the hippocampus. The effect of BDNF Val66Met polymorphism on hippocampal synaptic plasticity might play a role in cognitive dysfunction in Alzheimer’s disease. P1-156
TAU PROTEIN AGGREGATES INDUCE DYSREGULATION OF GENE EXPRESSION IN SPECIFIC BRAIN REGIONS OF RAT MODEL OF TAUOPATHY
Peter Filipcik1, Martin Cente1, Juraj Kucerak1, Branislav Kovacech1, Rostislav Skrabana1, Michal Novak1,2, 1Institute of Neuroimmunology, Bratislava, Slovakia; 2Axon Neuroscience GmbH, Vienna, Austria. Contact e-mail: [email protected] Background: Protein aggregates are common feature of several neurodegenerative diseases. Tauopathies including Alzheimer’s disease are well characterized by intracellular accumulation of microtubule associated protein tau in the form of paired helical filaments, which leads to the formation of neurofibrillary tangles (NFT). Transgenic rat expressing truncated tau exerts
S219
high load of NFT’s and therefore represent an ideal model for study of molecular events associated with generation and/or elimination of these lesions from affected brain regions. Methods: Transcriptional analysis of specific brain regions was performed using PCR arrays. Contra lateral side of the brain was used for biochemical analysis. Phosphorylation profile of tau protein was determined in soluble and sarcosyl insoluble fraction of endogenous and transgenic tau by western blot using specific AD associated markers. Results: Analysis of transcription level of specific groups of genes coding for proteins involved in the processes of neurotoxicity, inflammation and signal transduction led to identification of several significantly dysregulated genes. The expression of genes, which were up-regulated more than 2 fold in aged animals were investigated in the course of neurofibrilary degeneration of the transgenic rat model. The data suggest that level of gene transcripts for several stress associated and immune markers such as HSP27, complement component C3, and CD18 correlate with the load of NFT’s in aged transgenic animals expressing truncated tau protein. Interestingly expression of none of the tested tau protein kinases such as GSK3beta, MAPK and cdk5 kinase was found dysregulated when compared to control non-transgenic animals. Conclusions: Based on the correlation between levels of AD specific biomarkers and expression levels of tested genes we have estimated temporal order of biological events during development of neurofibrilary pathology. Our data point to massive expression of immune markers as a consequence of neurodegeneration. P1-157
MODELING ALZHEIMER’S DISEASE IN DROSOPHILA MELANOGASTER FOR LARGESCALE COMPOUND SCREENING
Matt B. Mahoney, Lenard Diggins, Marianna Foos, Emily Lund, James Mediatore, Phil O’Neil, Jim Symonds, Alfred T. Villaluz, Carol M. Singh, Vitruvean, LLC, Watertown, MA, USA. Contact e-mail: [email protected] Background: Alzheimer’s disease (AD), the most prevalent of neurodegenerative diseases, is growing increasingly common in the elderly, gradually depriving them of memory and cognitive function. Hallmarks of the disease include severe dementia, seemingly associated with amyloid plaques and neurofibrillary tangles in the CNS. However, the mechanisms that cause AD are not completely understood. Currently, there are no treatments that effectively ameliorate or abate disease progression, although many candidates are in clinic trials. Over the past decade, the fruit fly, Drosophila melanogaster, has been used as a vehicle for AD research, typically as an implement for identification and validation of targets. More recently, Drosophila have been used to test potential therapeutics for efficacy. Methods: Vitruvean, LLC has developed a Drosophila-based, medium-throughput behavioral screening platform for discovery and validation of compound treatments for neurodegenerative diseases, including Alzheimer’s, Parkinson’s, and Huntington’s diseases. Vitruvean uses this automated system to screen compounds for modification of progressively degenerating climbing phenotypes. We are currently investigating multiple models of AD, generated by overexpressing derivatives and variations of human APP and human tau transgenes in the fly CNS. Results: Using the PhenoScreen system, we were able to identify histone deacetylase inhibitors (TSA, SAHA), gamma-secretase inhibitors (Compound E), aggregation inhibitors (Methylene Blue), and cholinesterase inhibitors (Physostigmine, Tacrine) as being positive in one or more of our AD models. Such compounds have been previously shown to have positive effects in other AD model systems. Furthermore, we have been able to profile compound effects on behavior over multiple Drosophila AD models, providing us with information regarding which pathway they may affect. We were also able to assess some of these compounds in a Huntington’s disease line in hopes of further understanding their mechanisms. Conclusions: We demonstrate the utility of different Drosophila models of AD that are amenable to use in the PhenoScreen platform for drug discovery and validation. We have shown that potentially therapeutic compound classes can be used to reverse the degenerating behavior in multiple AD models highlighting different aspects of the disease. We believe that this screening system and this battery of fly models can be used to facilitate drug discovery for Alzheimer’s disease.