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Ramamurthy E, Agarwal S, Toong N, Sestili H, Kaplow IM, Chen Z, Phan B, Pfenning AR. Regression convolutional neural network models implicate peripheral immune regulatory variants in the predisposition to Alzheimer's disease. PLoS Comput Biol 2024; 20:e1012356. [PMID: 39186798 DOI: 10.1371/journal.pcbi.1012356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Accepted: 07/23/2024] [Indexed: 08/28/2024] Open
Abstract
Alzheimer's disease (AD) involves aggregation of amyloid β and tau, neuron loss, cognitive decline, and neuroinflammatory responses. Both resident microglia and peripheral immune cells have been associated with the immune component of AD. However, the relative contribution of resident and peripheral immune cell types to AD predisposition has not been thoroughly explored due to their similarity in gene expression and function. To study the effects of AD associated variants on cis-regulatory elements, we train convolutional neural network (CNN) regression models that link genome sequence to cell type-specific levels of open chromatin, a proxy for regulatory element activity. We then use in silico mutagenesis of regulatory sequences to predict the relative impact of candidate variants across these cell types. We develop and apply criteria for evaluating our models and refine our models using massively parallel reporter assay (MPRA) data. Our models identify multiple AD-associated variants with a greater predicted impact in peripheral cells relative to microglia or neurons. Our results support their use as models to study the effects of AD-associated variants and even suggest that peripheral immune cells themselves may mediate a component of AD predisposition. We make our library of CNN models and predictions available as a resource for the community to study immune and neurological disorders.
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Affiliation(s)
- Easwaran Ramamurthy
- Computational Biology Department, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Snigdha Agarwal
- Computational Biology Department, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Noelle Toong
- Computational Biology Department, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Heather Sestili
- Computational Biology Department, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Irene M Kaplow
- Computational Biology Department, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Ziheng Chen
- Computational Biology Department, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - BaDoi Phan
- Computational Biology Department, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Andreas R Pfenning
- Computational Biology Department, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
- Neuroscience Institute, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
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Oveisgharan S, Yu L, de Paiva Lopes K, Tasaki S, Wang Y, Menon V, Schneider JA, Seyfried NT, Bennett DA. Proteins linking APOE ɛ4 with Alzheimer's disease. Alzheimers Dement 2024; 20:4499-4511. [PMID: 38856164 PMCID: PMC11247662 DOI: 10.1002/alz.13867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 02/29/2024] [Accepted: 04/08/2024] [Indexed: 06/11/2024]
Abstract
INTRODUCTION The ɛ4 allele of the apolipoprotein E gene (APOE ɛ4) is the strongest genetic risk factor for Alzheimer's disease (AD), but the mechanisms connecting APOE ɛ4 to AD are not clear. METHODS Participants (n = 596) were from two clinical-pathological studies. Tissues from dorsolateral prefrontal cortex were examined to identify 8425 proteins. Post mortem pathological assessment used immunohistochemistry to obtain amyloid beta (Aβ) load and tau tangle density. RESULTS In separate models, APOE ɛ4 was associated with 18 proteins, which were associated with Aβ and tau tangles. Examining the proteins in a single model identified Netrin-1 and secreted frizzled-related protein 1 (SFRP1) as the two proteins linking APOE ɛ4 with Aβ with the largest effect sizes and Netrin-1 and testican-3 linking APOE ɛ4 with tau tangles. DISCUSSION We identified Netrin-1, SFRP1, and testican-3 as the most promising proteins that link APOE ɛ4 with Aβ and tau tangles. HIGHLIGHTS Of 8425 proteins extracted from prefrontal cortex, 18 were related to APOE ɛ4. The 18 proteins were also related to amyloid beta (Aβ) and tau. The 18 proteins were more related to APOE ɛ4 than other AD genetic risk variants. Netrin-1 and secreted frizzled-related protein 1 were the two most promising proteins linking APOE ɛ4 with Aβ. Netrin-1 and testican-3 were two most promising proteins linking APOE ɛ4 with tau.
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Affiliation(s)
- Shahram Oveisgharan
- Rush Alzheimer's Disease CenterRush University Medical CenterChicagoIllinoisUSA
- Department of Neurological SciencesRush University Medical CenterChicagoIllinoisUSA
| | - Lei Yu
- Rush Alzheimer's Disease CenterRush University Medical CenterChicagoIllinoisUSA
- Department of Neurological SciencesRush University Medical CenterChicagoIllinoisUSA
| | - Katia de Paiva Lopes
- Rush Alzheimer's Disease CenterRush University Medical CenterChicagoIllinoisUSA
- Department of Neurological SciencesRush University Medical CenterChicagoIllinoisUSA
| | - Shinya Tasaki
- Rush Alzheimer's Disease CenterRush University Medical CenterChicagoIllinoisUSA
- Department of Neurological SciencesRush University Medical CenterChicagoIllinoisUSA
| | - Yanling Wang
- Rush Alzheimer's Disease CenterRush University Medical CenterChicagoIllinoisUSA
| | - Vilas Menon
- Center for Translational and Computational NeuroimmunologyDepartment of Neurology & Taub Institute for Research on Alzheimer's Disease and the Aging BrainColumbia University Irving Medical CenterNew YorkNew YorkUSA
| | - Julie A. Schneider
- Rush Alzheimer's Disease CenterRush University Medical CenterChicagoIllinoisUSA
- Department of Neurological SciencesRush University Medical CenterChicagoIllinoisUSA
- Department of PathologyRush University Medical CenterChicagoIllinoisUSA
| | - Nicholas T. Seyfried
- Department of NeurologyEmory University School of MedicineAtlantaGeorgiaUSA
- Department of BiochemistryEmory UniversityAtlantaGeorgiaUSA
| | - David A. Bennett
- Rush Alzheimer's Disease CenterRush University Medical CenterChicagoIllinoisUSA
- Department of Neurological SciencesRush University Medical CenterChicagoIllinoisUSA
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Yoo L, Mendoza D, Richard AJ, Stephens JM. KAT8 beyond Acetylation: A Survey of Its Epigenetic Regulation, Genetic Variability, and Implications for Human Health. Genes (Basel) 2024; 15:639. [PMID: 38790268 PMCID: PMC11121512 DOI: 10.3390/genes15050639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2024] [Revised: 05/07/2024] [Accepted: 05/09/2024] [Indexed: 05/26/2024] Open
Abstract
Lysine acetyltransferase 8, also known as KAT8, is an enzyme involved in epigenetic regulation, primarily recognized for its ability to modulate histone acetylation. This review presents an overview of KAT8, emphasizing its biological functions, which impact many cellular processes and range from chromatin remodeling to genetic and epigenetic regulation. In many model systems, KAT8's acetylation of histone H4 lysine 16 (H4K16) is critical for chromatin structure modification, which influences gene expression, cell proliferation, differentiation, and apoptosis. Furthermore, this review summarizes the observed genetic variability within the KAT8 gene, underscoring the implications of various single nucleotide polymorphisms (SNPs) that affect its functional efficacy and are linked to diverse phenotypic outcomes, ranging from metabolic traits to neurological disorders. Advanced insights into the structural biology of KAT8 reveal its interaction with multiprotein assemblies, such as the male-specific lethal (MSL) and non-specific lethal (NSL) complexes, which regulate a wide range of transcriptional activities and developmental functions. Additionally, this review focuses on KAT8's roles in cellular homeostasis, stem cell identity, DNA damage repair, and immune response, highlighting its potential as a therapeutic target. The implications of KAT8 in health and disease, as evidenced by recent studies, affirm its importance in cellular physiology and human pathology.
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Affiliation(s)
- Lindsey Yoo
- Adipocyte Biology Laboratory, Pennington Biomedical, Baton Rouge, LA 70808, USA; (L.Y.); (D.M.); (A.J.R.)
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
| | - David Mendoza
- Adipocyte Biology Laboratory, Pennington Biomedical, Baton Rouge, LA 70808, USA; (L.Y.); (D.M.); (A.J.R.)
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Allison J. Richard
- Adipocyte Biology Laboratory, Pennington Biomedical, Baton Rouge, LA 70808, USA; (L.Y.); (D.M.); (A.J.R.)
| | - Jacqueline M. Stephens
- Adipocyte Biology Laboratory, Pennington Biomedical, Baton Rouge, LA 70808, USA; (L.Y.); (D.M.); (A.J.R.)
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
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Maninger JK, Nowak K, Goberdhan S, O'Donoghue R, Connor-Robson N. Cell type-specific functions of Alzheimer's disease endocytic risk genes. Philos Trans R Soc Lond B Biol Sci 2024; 379:20220378. [PMID: 38368934 PMCID: PMC10874703 DOI: 10.1098/rstb.2022.0378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 09/12/2023] [Indexed: 02/20/2024] Open
Abstract
Endocytosis is a key cellular pathway required for the internalization of cellular nutrients, lipids and receptor-bound cargoes. It is also critical for the recycling of cellular components, cellular trafficking and membrane dynamics. The endocytic pathway has been consistently implicated in Alzheimer's disease (AD) through repeated genome-wide association studies and the existence of rare coding mutations in endocytic genes. BIN1 and PICALM are two of the most significant late-onset AD risk genes after APOE and are both key to clathrin-mediated endocytic biology. Pathological studies also demonstrate that endocytic dysfunction is an early characteristic of late-onset AD, being seen in the prodromal phase of the disease. Different cell types of the brain have specific requirements of the endocytic pathway. Neurons require efficient recycling of synaptic vesicles and microglia use the specialized form of endocytosis-phagocytosis-for their normal function. Therefore, disease-associated changes in endocytic genes will have varied impacts across different cell types, which remains to be fully explored. Given the genetic and pathological evidence for endocytic dysfunction in AD, understanding how such changes and the related cell type-specific vulnerabilities impact normal cellular function and contribute to disease is vital and could present novel therapeutic opportunities. This article is part of a discussion meeting issue 'Understanding the endo-lysosomal network in neurodegeneration'.
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Affiliation(s)
| | - Karolina Nowak
- Cardiff University, Dementia Research Institute, Cardiff University¸ Cardiff, CF24 4HQ, UK
| | - Srilakshmi Goberdhan
- Cardiff University, Dementia Research Institute, Cardiff University¸ Cardiff, CF24 4HQ, UK
| | - Rachel O'Donoghue
- Cardiff University, Dementia Research Institute, Cardiff University¸ Cardiff, CF24 4HQ, UK
| | - Natalie Connor-Robson
- Cardiff University, Dementia Research Institute, Cardiff University¸ Cardiff, CF24 4HQ, UK
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Basavarajappa BS, Subbanna S. Unlocking the epigenetic symphony: histone acetylation's impact on neurobehavioral change in neurodegenerative disorders. Epigenomics 2024; 16:331-358. [PMID: 38321930 PMCID: PMC10910622 DOI: 10.2217/epi-2023-0428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Accepted: 01/23/2024] [Indexed: 02/08/2024] Open
Abstract
Recent genomics and epigenetic advances have empowered the exploration of DNA/RNA methylation and histone modifications crucial for gene expression in response to stress, aging and disease. Interest in understanding neuronal plasticity's epigenetic mechanisms, influencing brain rewiring amid development, aging and neurodegenerative disorders, continues to grow. Histone acetylation dysregulation, a commonality in diverse brain disorders, has become a therapeutic focus. Histone acetyltransferases and histone deacetylases have emerged as promising targets for neurodegenerative disorder treatment. This review delves into histone acetylation regulation, potential therapies and future perspectives for disorders like Alzheimer's, Parkinson's and Huntington's. Exploring genetic-environmental interplay through models and studies reveals molecular changes, behavioral insights and early intervention possibilities targeting the epigenome in at-risk individuals.
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Affiliation(s)
- Balapal S Basavarajappa
- Center for Dementia Research, Nathan Kline Institute for Psychiatric Research, Orangeburg, NY 10962, USA
- Molecular Imaging & Neuropathology Area, New York State Psychiatric Institute, NY 10032, USA
- Department of Psychiatry, Columbia University Irving Medical Center, NY 10032, USA
- Department of Psychiatry, New York University Langone Medical Center, NY 10016, USA
| | - Shivakumar Subbanna
- Center for Dementia Research, Nathan Kline Institute for Psychiatric Research, Orangeburg, NY 10962, USA
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Xu DC, Sas-Nowosielska H, Donahue G, Huang H, Pourshafie N, Good CR, Berger SL. Histone acetylation in an Alzheimer's disease cell model promotes homeostatic amyloid-reducing pathways. Acta Neuropathol Commun 2024; 12:3. [PMID: 38167174 PMCID: PMC10759377 DOI: 10.1186/s40478-023-01696-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Accepted: 11/21/2023] [Indexed: 01/05/2024] Open
Abstract
Alzheimer's Disease (AD) is a disorder characterized by cognitive decline, neurodegeneration, and accumulation of amyloid plaques and tau neurofibrillary tangles in the brain. Dysregulation of epigenetic histone modifications may lead to expression of transcriptional programs that play a role either in protecting against disease genesis or in worsening of disease pathology. One such histone modification, acetylation of histone H3 lysine residue 27 (H3K27ac), is primarily localized to genomic enhancer regions and promotes active gene transcription. We previously discovered H3K27ac to be more abundant in AD patient brain tissue compared to the brains of age-matched non-demented controls. In this study, we use iPSC-neurons derived from familial AD patients with an amyloid precursor protein (APP) duplication (APPDup neurons) as a model to study the functional effect of lowering CBP/P300 enzymes that catalyze H3K27ac. We found that homeostatic amyloid-reducing genes were upregulated in the APPDup neurons compared to non-demented controls. We lowered CBP/P300 to reduce H3K27ac, which led to decreased expression of numerous of these homeostatic amyloid-reducing genes, along with increased extracellular secretion of a toxic amyloid-β species, Aβ(1-42). Our findings suggest that epigenomic histone acetylation, including H3K27ac, drives expression of compensatory genetic programs in response to AD-associated insults, specifically those resulting from APP duplication, and thus may play a role in mitigating AD pathology in neurons.
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Affiliation(s)
- Daniel C Xu
- Department of Cell and Developmental Biology, Perelman School of Medicine Philadelphia, Penn Institute of Epigenetics, Philadelphia, PA, 19104, USA
| | - Hanna Sas-Nowosielska
- Department of Cell and Developmental Biology, Perelman School of Medicine Philadelphia, Penn Institute of Epigenetics, Philadelphia, PA, 19104, USA
| | - Greg Donahue
- Department of Cell and Developmental Biology, Perelman School of Medicine Philadelphia, Penn Institute of Epigenetics, Philadelphia, PA, 19104, USA
| | - Hua Huang
- Department of Cell and Developmental Biology, Perelman School of Medicine Philadelphia, Penn Institute of Epigenetics, Philadelphia, PA, 19104, USA
| | - Naemeh Pourshafie
- Department of Cell and Developmental Biology, Perelman School of Medicine Philadelphia, Penn Institute of Epigenetics, Philadelphia, PA, 19104, USA
| | - Charly R Good
- Department of Cell and Developmental Biology, Perelman School of Medicine Philadelphia, Penn Institute of Epigenetics, Philadelphia, PA, 19104, USA
| | - Shelley L Berger
- Department of Cell and Developmental Biology, Perelman School of Medicine Philadelphia, Penn Institute of Epigenetics, Philadelphia, PA, 19104, USA.
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Tsalenchuk M, Gentleman SM, Marzi SJ. Linking environmental risk factors with epigenetic mechanisms in Parkinson's disease. NPJ Parkinsons Dis 2023; 9:123. [PMID: 37626097 PMCID: PMC10457362 DOI: 10.1038/s41531-023-00568-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Accepted: 08/16/2023] [Indexed: 08/27/2023] Open
Abstract
Sporadic Parkinson's disease (PD) is a progressive neurodegenerative disease, with a complex risk structure thought to be influenced by interactions between genetic variants and environmental exposures, although the full aetiology is unknown. Environmental factors, including pesticides, have been reported to increase the risk of developing the disease. Growing evidence suggests epigenetic changes are key mechanisms by which these environmental factors act upon gene regulation, in disease-relevant cell types. We present a systematic review critically appraising and summarising the current body of evidence of the relationship between epigenetic mechanisms and environmental risk factors in PD to inform future research in this area. Epigenetic studies of relevant environmental risk factors in animal and cell models have yielded promising results, however, research in humans is just emerging. While published studies in humans are currently relatively limited, the importance of the field for the elucidation of molecular mechanisms of pathogenesis opens clear and promising avenues for the future of PD research. Carefully designed epidemiological studies carried out in PD patients hold great potential to uncover disease-relevant gene regulatory mechanisms. Therefore, to advance this burgeoning field, we recommend broadening the scope of investigations to include more environmental exposures, increasing sample sizes, focusing on disease-relevant cell types, and recruiting more diverse cohorts.
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Affiliation(s)
- Maria Tsalenchuk
- UK Dementia Research Institute, Imperial College London, London, UK
- Department of Brain Sciences, Imperial College London, London, UK
| | | | - Sarah J Marzi
- UK Dementia Research Institute, Imperial College London, London, UK.
- Department of Brain Sciences, Imperial College London, London, UK.
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Nott A, Holtman IR. Genetic insights into immune mechanisms of Alzheimer's and Parkinson's disease. Front Immunol 2023; 14:1168539. [PMID: 37359515 PMCID: PMC10285485 DOI: 10.3389/fimmu.2023.1168539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 04/17/2023] [Indexed: 06/28/2023] Open
Abstract
Microglia, the macrophages of the brain, are vital for brain homeostasis and have been implicated in a broad range of brain disorders. Neuroinflammation has gained traction as a possible therapeutic target for neurodegeneration, however, the precise function of microglia in specific neurodegenerative disorders is an ongoing area of research. Genetic studies offer valuable insights into understanding causality, rather than merely observing a correlation. Genome-wide association studies (GWAS) have identified many genetic loci that are linked to susceptibility to neurodegenerative disorders. (Post)-GWAS studies have determined that microglia likely play an important role in the development of Alzheimer's disease (AD) and Parkinson's disease (PD). The process of understanding how individual GWAS risk loci affect microglia function and mediate susceptibility is complex. A rapidly growing number of publications with genomic datasets and computational tools have formulated new hypotheses that guide the biological interpretation of AD and PD genetic risk. In this review, we discuss the key concepts and challenges in the post-GWAS interpretation of AD and PD GWAS risk alleles. Post-GWAS challenges include the identification of target cell (sub)type(s), causal variants, and target genes. Crucially, the prediction of GWAS-identified disease-risk cell types, variants and genes require validation and functional testing to understand the biological consequences within the pathology of the disorders. Many AD and PD risk genes are highly pleiotropic and perform multiple important functions that might not be equally relevant for the mechanisms by which GWAS risk alleles exert their effect(s). Ultimately, many GWAS risk alleles exert their effect by changing microglia function, thereby altering the pathophysiology of these disorders, and hence, we believe that modelling this context is crucial for a deepened understanding of these disorders.
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Affiliation(s)
- Alexi Nott
- Department of Brain Sciences, Imperial College London, London, United Kingdom
- UK Dementia Research Institute, Imperial College London, London, United Kingdom
| | - Inge R. Holtman
- Department of Biomedical Sciences of Cells and Systems, Section Molecular Neurobiology, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
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