- Email: [email protected]
GENE EXPRESSION NETWORK ANALYSIS IMPLICATES THE IMMUNE RESPONSE IN GENETIC SUSCEPTIBILITY TO LATE-ONSET AD
P256
O4-03-06
Oral Sessions: O4-04: Genetics: Beyond GWAS—Follow-up Studies of Alzheimer’s Disease GWAS
PGC-1a GENE THERAPY IMPROVES MEMORY AND DECREASES AMYLOID BETA IN APP23 MICE
Loukia Katsouri1, Yau Mun Lim2, Nicholas Mazarakis2, Magdalena Sastre2, 1Imperial College, London, United Kingdom; 2Imperial College London, London, United Kingdom. Contact e-mail: l.katsouri@ imperial.ac.uk Background: PPARg-coactivator-1a (PGC-1a) is a transcriptional regulator which is involved in mitochondrial biogenesis and in the control of genes regulating oxidative stress and inflammation. We and others have found that the brains of Alzheimer’s disease (AD) patients show reduced PGC-1a expression compared to healthy subjects, thus implying that PGC-1a overexpression could be protective against AD. In addition, in vitro results have revealed that overexpression of PGC-1a increases the levels of neurotrophic soluble APPa and reduces Ab generation. Methods: The aim of this study was to investigate the role of PGC-1a as a therapeutic target for AD. To achieve this we generated a lentiviral vector expressing PGC-1a and delivered it by stereotaxic injection bilaterally into the frontal cortex and the hippocampus of wild-type and AD transgenic mice (APP23) at the age of 8-m.o. As control, wild-type and APP23 mice were injected with an eGFP-expressing vector and a battery of behavioural tests was performed 1- and 4-months post surgery (open field, object location test (OLT), novel object recognition test (ORT) and Y-maze). After completion of the behavioural tasks, the animals were sacrificed and transcardially perfused with PBS. The right brain hemisphere was collected for immunohistochemistry and the left hemisphere was dissected into distinct brain areas and used for immunoblotting. Results: There were no significant differences in weight, anxiety or mobility between the mice that received the eGFP or the PGC-1a lentiviral vectors at 1- and 4-months post-surgery. Behavioural analysis showed that the APP23 mice that received the PGC-1a vector have improved spatial working and spatial reference memory, by using the Y-maze and the OLT task respectively, compared to the control APP23 group 4-months post surgery. In addition, PGC-1a overexpression improved recognition memory in the ORT test. Protein and immunohistochemical analysis revealed a significant reduction in Ab and amyloid plaques in the mice that have received the PGC1a lentiviral vector. Conclusions: The results from the present study demonstrate that PGC1a lentiviral injection into the brain is tolerable and safe to be used for gene therapy in mice. These data also indicate that PGC-1a gene transfer could have a potential therapeutic use in AD.
WEDNESDAY, JULY 16, 2014 ORAL SESSIONS O4-04 GENETICS: BEYOND GWAS—FOLLOW-UP STUDIES OF ALZHEIMER’S DISEASE GWAS O4-04-01
GENE EXPRESSION NETWORK ANALYSIS IMPLICATES THE IMMUNE RESPONSE IN GENETIC SUSCEPTIBILITY TO LATE-ONSET AD
Peter Holmans1, Celine Bellenguez2, Li-San Wang3, Gerard D. Schellenberg4, Sudha Seshadri5, Philippe Amouyel6, Julie Williams7, Lesley Jones7, 1Cardiff University, Cardiff, Wales, United Kingdom; 2INSERM U744, Lille, France; 3University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States; 4University of Pennsylvania, Philadelphia, Pennsylvania, United States; 5Boston University School of Medicine, Boston, Massachusetts, United States; 6 Inserm / Univ Lille 2 / Institut Pasteur de Lille, Lille Cedex, France; 7 Cardiff University, Cardiff, Wales, United Kingdom. Contact e-mail: [email protected] Background: Pathway analysis of genome-wide association studies (GWAS) has robustly implicated several areas of biology in the aetiology of late-onset Alzheimer’s disease, notably the immune system,
cholesterol metabolism, protein ubiquitination and endocytosis. However, such analyses require pre-specified pathways, and are thus limited to genes with biological annotations. This annotation gap can be reduced by using gene expression data to create modules of co-expressed genes, and testing these for association to disease. Recently, Zhang et al. used this approach to implicate a module related to microglia in AD risk, by comparing module connectivity between AD case and control expression data, but did not test their module for enrichment of association in GWAS data. Methods: We used the expression data of Gibbs et al., consisting of of gene expression data from four brain regions in a sample of approximately 150 control brains, to create 117 modules of co-expressed genes, using weighted gene correlation network analysis These modules were tested for enrichment of association with late-onset AD in the International Genomics of Alzheimer’s Project (IGAP) GWAS dataset, consisting of 17,008 cases and 37,646 controls using ALIGATOR and GSEA Results: Four expression modules were significantly associated with AD after correction for multiple testing, one from each brain region. Functional analysis of the modules using DAVID showed that each module was related to the immune response. In total, the four modules contained 294 distinct genes, of which 151 were common to two or more modules. These 151 genes were significantly enriched for AD risk in IGAP (p¼0.000004) with the remainder showing no enrichment (p¼0.505). The TYROBP gene highlighted by Zhang et al. was found to be a hub gene in the expression network formed by these 151 genes Conclusions: Gene expression network analysis can at least partly overcome the biological annotation gap, and complement analysis of pre-defined pathways. When constructing the networks, building consensus modules from multiple expression datasets can greatly increase the power of the enrichment analyses.
O4-04-02
A NOVEL SUSCEPTIBILITY LOCUS FOR NEUROFIBRILLARY TANGLES AT PTPRD: EVIDENCE OF PLEIOTROPIC EFFECTS ON OTHER BRAIN PATHOLOGIES
Lori B. Chibnik1, Charles C. White1, Towfique Raj2, Shubhabrata Mukherjee3, Joshua M. Shulman4, Paul Crane3, Thomas Montine3, David Bennett5, Philip De Jager1, 1Brigham and Women’s Hospital, Boston, Massachusetts, United States; 2Brigham and Women’s Hospital/Harvard Medical School, Boston, Massachusetts, United States; 3University of Washington, Seattle, Washington, United States; 4 Baylor, Houston, Texas, United States; 5Rush University Medical Center, Chicago, Illinois, United States. Contact e-mail: [email protected]. harvard.edu Background: Individuals with dementia, including those clinically diagnosed with Alzheimer’s Disease (AD), often show mixed pathologies on postmortem examination. We performed independent genome-wide association studies (GWAS) for seven pathologies that influence risk of dementia, and then applied a pleiotropic approach to find variants that have shared effects across multiple pathologies. Methods: We investigated 903 brain samples from 2 cohort studies on aging. We began with standard single-trait GWAS for 7 pathology traits: neuritic and diffuse plaques, neurofibrillary tangles, cerebral amyloid angiopathy, micro- and macroscopic infarcts, and Lewy body pathology. Next we assessed a pleiotropic effect by employing an inverted ordinal logistic regression model genome-wide, where alleles are treated as the outcome and traits are treated as independent variables (MultiPhen). In addition, pathway analyses are currently being performed using MAGENTA software in order to identify functionally related genesets that underlay the shared genetic architecture. Results: We report the first susceptibility locus (rs560380) that influences the deposition of neurofibrillary tangles at PTPRD (p¼3x10 -8), and replicate this result in an independent dataset (p¼0.02 for Braak tangle stages and p¼0.01 for CERAD amyloid stages). In addition, we evaluate the possibility that a
O4-03-06
Oral Sessions: O4-04: Genetics: Beyond GWAS—Follow-up Studies of Alzheimer’s Disease GWAS
PGC-1a GENE THERAPY IMPROVES MEMORY AND DECREASES AMYLOID BETA IN APP23 MICE
Loukia Katsouri1, Yau Mun Lim2, Nicholas Mazarakis2, Magdalena Sastre2, 1Imperial College, London, United Kingdom; 2Imperial College London, London, United Kingdom. Contact e-mail: l.katsouri@ imperial.ac.uk Background: PPARg-coactivator-1a (PGC-1a) is a transcriptional regulator which is involved in mitochondrial biogenesis and in the control of genes regulating oxidative stress and inflammation. We and others have found that the brains of Alzheimer’s disease (AD) patients show reduced PGC-1a expression compared to healthy subjects, thus implying that PGC-1a overexpression could be protective against AD. In addition, in vitro results have revealed that overexpression of PGC-1a increases the levels of neurotrophic soluble APPa and reduces Ab generation. Methods: The aim of this study was to investigate the role of PGC-1a as a therapeutic target for AD. To achieve this we generated a lentiviral vector expressing PGC-1a and delivered it by stereotaxic injection bilaterally into the frontal cortex and the hippocampus of wild-type and AD transgenic mice (APP23) at the age of 8-m.o. As control, wild-type and APP23 mice were injected with an eGFP-expressing vector and a battery of behavioural tests was performed 1- and 4-months post surgery (open field, object location test (OLT), novel object recognition test (ORT) and Y-maze). After completion of the behavioural tasks, the animals were sacrificed and transcardially perfused with PBS. The right brain hemisphere was collected for immunohistochemistry and the left hemisphere was dissected into distinct brain areas and used for immunoblotting. Results: There were no significant differences in weight, anxiety or mobility between the mice that received the eGFP or the PGC-1a lentiviral vectors at 1- and 4-months post-surgery. Behavioural analysis showed that the APP23 mice that received the PGC-1a vector have improved spatial working and spatial reference memory, by using the Y-maze and the OLT task respectively, compared to the control APP23 group 4-months post surgery. In addition, PGC-1a overexpression improved recognition memory in the ORT test. Protein and immunohistochemical analysis revealed a significant reduction in Ab and amyloid plaques in the mice that have received the PGC1a lentiviral vector. Conclusions: The results from the present study demonstrate that PGC1a lentiviral injection into the brain is tolerable and safe to be used for gene therapy in mice. These data also indicate that PGC-1a gene transfer could have a potential therapeutic use in AD.
WEDNESDAY, JULY 16, 2014 ORAL SESSIONS O4-04 GENETICS: BEYOND GWAS—FOLLOW-UP STUDIES OF ALZHEIMER’S DISEASE GWAS O4-04-01
GENE EXPRESSION NETWORK ANALYSIS IMPLICATES THE IMMUNE RESPONSE IN GENETIC SUSCEPTIBILITY TO LATE-ONSET AD
Peter Holmans1, Celine Bellenguez2, Li-San Wang3, Gerard D. Schellenberg4, Sudha Seshadri5, Philippe Amouyel6, Julie Williams7, Lesley Jones7, 1Cardiff University, Cardiff, Wales, United Kingdom; 2INSERM U744, Lille, France; 3University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States; 4University of Pennsylvania, Philadelphia, Pennsylvania, United States; 5Boston University School of Medicine, Boston, Massachusetts, United States; 6 Inserm / Univ Lille 2 / Institut Pasteur de Lille, Lille Cedex, France; 7 Cardiff University, Cardiff, Wales, United Kingdom. Contact e-mail: [email protected] Background: Pathway analysis of genome-wide association studies (GWAS) has robustly implicated several areas of biology in the aetiology of late-onset Alzheimer’s disease, notably the immune system,
cholesterol metabolism, protein ubiquitination and endocytosis. However, such analyses require pre-specified pathways, and are thus limited to genes with biological annotations. This annotation gap can be reduced by using gene expression data to create modules of co-expressed genes, and testing these for association to disease. Recently, Zhang et al. used this approach to implicate a module related to microglia in AD risk, by comparing module connectivity between AD case and control expression data, but did not test their module for enrichment of association in GWAS data. Methods: We used the expression data of Gibbs et al., consisting of of gene expression data from four brain regions in a sample of approximately 150 control brains, to create 117 modules of co-expressed genes, using weighted gene correlation network analysis These modules were tested for enrichment of association with late-onset AD in the International Genomics of Alzheimer’s Project (IGAP) GWAS dataset, consisting of 17,008 cases and 37,646 controls using ALIGATOR and GSEA Results: Four expression modules were significantly associated with AD after correction for multiple testing, one from each brain region. Functional analysis of the modules using DAVID showed that each module was related to the immune response. In total, the four modules contained 294 distinct genes, of which 151 were common to two or more modules. These 151 genes were significantly enriched for AD risk in IGAP (p¼0.000004) with the remainder showing no enrichment (p¼0.505). The TYROBP gene highlighted by Zhang et al. was found to be a hub gene in the expression network formed by these 151 genes Conclusions: Gene expression network analysis can at least partly overcome the biological annotation gap, and complement analysis of pre-defined pathways. When constructing the networks, building consensus modules from multiple expression datasets can greatly increase the power of the enrichment analyses.
O4-04-02
A NOVEL SUSCEPTIBILITY LOCUS FOR NEUROFIBRILLARY TANGLES AT PTPRD: EVIDENCE OF PLEIOTROPIC EFFECTS ON OTHER BRAIN PATHOLOGIES
Lori B. Chibnik1, Charles C. White1, Towfique Raj2, Shubhabrata Mukherjee3, Joshua M. Shulman4, Paul Crane3, Thomas Montine3, David Bennett5, Philip De Jager1, 1Brigham and Women’s Hospital, Boston, Massachusetts, United States; 2Brigham and Women’s Hospital/Harvard Medical School, Boston, Massachusetts, United States; 3University of Washington, Seattle, Washington, United States; 4 Baylor, Houston, Texas, United States; 5Rush University Medical Center, Chicago, Illinois, United States. Contact e-mail: [email protected]. harvard.edu Background: Individuals with dementia, including those clinically diagnosed with Alzheimer’s Disease (AD), often show mixed pathologies on postmortem examination. We performed independent genome-wide association studies (GWAS) for seven pathologies that influence risk of dementia, and then applied a pleiotropic approach to find variants that have shared effects across multiple pathologies. Methods: We investigated 903 brain samples from 2 cohort studies on aging. We began with standard single-trait GWAS for 7 pathology traits: neuritic and diffuse plaques, neurofibrillary tangles, cerebral amyloid angiopathy, micro- and macroscopic infarcts, and Lewy body pathology. Next we assessed a pleiotropic effect by employing an inverted ordinal logistic regression model genome-wide, where alleles are treated as the outcome and traits are treated as independent variables (MultiPhen). In addition, pathway analyses are currently being performed using MAGENTA software in order to identify functionally related genesets that underlay the shared genetic architecture. Results: We report the first susceptibility locus (rs560380) that influences the deposition of neurofibrillary tangles at PTPRD (p¼3x10 -8), and replicate this result in an independent dataset (p¼0.02 for Braak tangle stages and p¼0.01 for CERAD amyloid stages). In addition, we evaluate the possibility that a