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Fitz NF, Sahu A, Lu Y, Ambrosio F, Lefterov I, Koldamova R. Extracellular Vesicles in Young Serum Contribute to the Restoration of Age-Related Brain Transcriptomes and Cognition in Old Mice. Int J Mol Sci 2023; 24:12550. [PMID: 37628730 PMCID: PMC10454174 DOI: 10.3390/ijms241612550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 08/01/2023] [Accepted: 08/03/2023] [Indexed: 08/27/2023] Open
Abstract
We have previously demonstrated that circulating extracellular vesicles (EVs) are essential to the beneficial effect of young serum on the skeletal muscle regenerative cascade. Here, we show that infusions of young serum significantly improve age-associated memory deficits, and that these effects are abolished after serum depletion of EVs. RNA-seq analysis of the choroid plexus demonstrates EV-mediated effects on genes involved in barrier function and trans-barrier transport. Comparing the differentially expressed genes to recently published chronological aging clock genes reveals a reversal of transcriptomic aging in the choroid plexus. Following young serum treatment, the hippocampal transcriptome demonstrates significant upregulation of the anti-aging gene Klotho, along with an abrogated effect after EV depletion. Transcriptomic profiling of Klotho knockout and heterozygous mice shows the downregulation of genes associated with transport, exocytosis, and lipid transport, while upregulated genes are associated with activated microglia. The results of our study indicate the significance of EVs as vehicles to deliver signals from the periphery to the brain and the importance of Klotho in maintaining brain homeostasis.
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Affiliation(s)
- Nicholas F. Fitz
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Amrita Sahu
- Department of Physical Medicine and Rehabilitation, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Yi Lu
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Fabrisia Ambrosio
- Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, MA 02115, USA
- Discovery Center for Musculoskeletal Recovery, Schoen Adams Research Institute at Spaulding, Charlestown, MA 02129, USA
| | - Iliya Lefterov
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Radosveta Koldamova
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15260, USA
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Lu Y, Saibro-Girardi C, Fitz NF, McGuire MR, Ostach MA, Mamun-Or-Rashid ANM, Lefterov I, Koldamova R. Multi-transcriptomics reveals brain cellular responses to peripheral infection in Alzheimer's disease model mice. Cell Rep 2023; 42:112785. [PMID: 37436901 PMCID: PMC10530196 DOI: 10.1016/j.celrep.2023.112785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 05/03/2023] [Accepted: 06/24/2023] [Indexed: 07/14/2023] Open
Abstract
Peripheral inflammation has been linked to various neurodegenerative disorders, including Alzheimer's disease (AD). Here we perform bulk, single-cell, and spatial transcriptomics in APP/PS1 mice intranasally exposed to Staphylococcus aureus to determine how low-grade peripheral infection affects brain transcriptomics and AD-like pathology. Chronic exposure led to increased amyloid plaque burden and plaque-associated microglia, significantly affecting the transcription of brain barrier-associated cells, which resulted in barrier leakage. We reveal cell-type- and spatial-specific transcriptional changes related to brain barrier function and neuroinflammation during the acute infection. Both acute and chronic exposure led to brain macrophage-associated responses and detrimental effects in neuronal transcriptomics. Finally, we identify unique transcriptional responses at the amyloid plaque niches following acute infection characterized by higher disease-associated microglia gene expression and a larger effect on astrocytic or macrophage-associated genes, which could facilitate amyloid and related pathologies. Our findings provide important insights into the mechanisms linking peripheral inflammation to AD pathology.
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Affiliation(s)
- Yi Lu
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Carolina Saibro-Girardi
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Nicholas Francis Fitz
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Mikayla Ranae McGuire
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Mary Ann Ostach
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - A N M Mamun-Or-Rashid
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Iliya Lefterov
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15261, USA.
| | - Radosveta Koldamova
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15261, USA.
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Lefterov I, Fitz NF, Lu Y, Koldamova R. APOEε4 and risk of Alzheimer's disease - time to move forward. Front Neurosci 2023; 17:1195724. [PMID: 37274212 PMCID: PMC10235508 DOI: 10.3389/fnins.2023.1195724] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 05/02/2023] [Indexed: 06/06/2023] Open
Abstract
The inheritance of Apolipoprotein E4 (APOEε4) brings the highest genetic risk of Alzheimer's disease (AD), arguably the highest genetic risk in human pathology. Since the discovery of the association, APOE protein isoforms have been at the center of tens of thousands of studies and reports. While, without a doubt, our knowledge about the normal physiological function of APOE isoforms in the brain has increased tremendously, the questions of how the inheritance of the APOEε4 allele translates into a risk of AD, and the risk is materialized, remain unanswered. Moreover, the knowledge about the risk associated with APOEε4 has not helped design a meaningful preventative or therapeutic strategy. Animal models with targeted replacement of Apoe have been generated and, thanks to the recent NIH/NIA/Alzheimer's disease Association initiative, are now freely available to AD researchers. While helpful in many aspects, none of the available models recapitulates normal physiological transcriptional regulation of the human APOE gene cluster. Changes in epigenetic regulation of APOE alleles in animal models in response to external insults have rarely been if ever, addressed. However, these animal models provide a useful tool to handle questions and investigate protein-protein interactions with proteins expressed by other recently discovered genes and gene variants considered genetic risk factors of AD, like Triggering Receptor expressed on Myeloid cells 2 (TREM2). In this review, we discuss genetic and epigenetic regulatory mechanisms controlling and influencing APOE expression and focus on interactions of APOE and TREM2 in the context of microglia and astrocytes' role in AD-like pathology in animal models.
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Fitz NF, Barchowsky A, Koldamova R, Lefterov I. Genome-wide Alteration of Histone Methylation Profiles Associated with Cognitive Changes in Response to Developmental Arsenic Exposure in Mice. Toxicol Rep 2022; 9:393-403. [PMID: 35299870 PMCID: PMC8920871 DOI: 10.1016/j.toxrep.2022.03.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 02/16/2022] [Accepted: 03/02/2022] [Indexed: 11/18/2022] Open
Abstract
Inorganic arsenic is a xenobiotic entering the body primarily through contaminated drinking water and food. There are defined mechanisms that describe arsenic’s association with increased cancer incidence, however mechanisms explaining arsenic exposure and neurodevelopmental or aging disorders are poorly defined. In recent years, arsenic effects on epigenome have become a particular focus. We hypothesize that human relevant arsenic exposure during particular developmental windows, or long-term exposure later in life induce pathophysiological neural changes through epigenomic alterations, in particular histone methylation profile, manifesting as cognitive decline. C57BL/6 wild-type mice were continually exposed to sodium arsenite (100 µg/L) in drinking water prior to mating through weaning of the experimental progeny. A second cohort of aged APP/PS mice were chronically exposed to the same level of arsenic. Cognitive testing, histological examination of brains and genome-wide methylation levels of H3K4me3 and H3K27me3 examined after ChIP-seq were used to determine the effects of arsenic exposure. Developmental arsenic exposure caused significantly diminished cognition in wild-type mice. The analysis of ChIP-seq data and experiments with mouse embryonic stem cells demonstrated that epigenetic changes induced by arsenic exposure translated into gene expression alterations associated with neuronal development and neurological disease. Increased hippocampal amyloid plaques levels of APP/PS mice and cognitive decline provided evidence that arsenic exposure aggravated an existing Alzheimer’s disease-like phenotype. We show developmental arsenic exposure significantly impacts histone modifications in brain which remain present into adulthood and provide a potential mechanism by which developmental arsenic exposure influences cognitive functions. We also show that human relevant, chronic arsenic exposure has deleterious effects on adult APP/PS mice and exacerbates existing Alzheimer’s disease-like symptoms. The results demonstrate how developmental arsenic exposure impacts the brain epigenome, leading to altered gene expression later in life. Developmental arsenic exposure impacts biologically significant histone modifications in brain. Decreased trimethylation of H3K27 is associated with processes related to neuron fate and development. Histone modification in brain present a potential mechanism how developmental arsenic exposure impacts cognitive functions. Arsenic exacerbates cognitive deficits and neuroinflammation in AD model mice.
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Fitz NF, Nam KN, Koldamova R, Lefterov I. snoRNAs in plasma extracellular vesicles of AD patients are differentially associated with APOE genotype. Alzheimers Dement 2021. [DOI: 10.1002/alz.055619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Sahu A, Clemens ZJ, Shinde SN, Sivakumar S, Pius A, Bhatia A, Picciolini S, Carlomagno C, Gualerzi A, Bedoni M, Van Houten B, Lovalekar M, Fitz NF, Lefterov I, Barchowsky A, Koldamova R, Ambrosio F. Regulation of aged skeletal muscle regeneration by circulating extracellular vesicles. Nat Aging 2021; 1:1148-1161. [PMID: 35665306 PMCID: PMC9165723 DOI: 10.1038/s43587-021-00143-2] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Accepted: 10/27/2021] [Indexed: 12/21/2022]
Abstract
Heterochronic blood exchange (HBE) has demonstrated that circulating factors restore youthful features to aged tissues. However, the systemic mediators of those rejuvenating effects remain poorly defined. We show here that the beneficial effect of young blood on aged muscle regeneration was diminished when serum was depleted of extracellular vesicles (EVs). Whereas EVs from young animals rejuvenate aged cell bioenergetics and skeletal muscle regeneration, aging shifts EV subpopulation heterogeneity and compromises downstream benefits on recipient cells. Machine learning classifiers revealed that aging shifts the nucleic acid, but not protein, fingerprint of circulating EVs. Alterations in sub-population heterogeneity were accompanied by declines in transcript levels of the pro-longevity protein, α-Klotho, and injection of EVs improved muscle regeneration in a Klotho mRNA-dependent manner. These studies demonstrate that EVs play a key role in the rejuvenating effects of HBE and that Klotho transcripts within EVs phenocopy the effects of young serum on aged skeletal muscle.
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Affiliation(s)
- Amrita Sahu
- Department of Physical Medicine & Rehabilitation, University of Pittsburgh, Pittsburgh, PA
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA
| | - Zachary J. Clemens
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA
| | - Sunita N. Shinde
- Department of Physical Medicine & Rehabilitation, University of Pittsburgh, Pittsburgh, PA
| | - Sruthi Sivakumar
- Department of Physical Medicine & Rehabilitation, University of Pittsburgh, Pittsburgh, PA
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA
| | - Abish Pius
- Department of Physical Medicine & Rehabilitation, University of Pittsburgh, Pittsburgh, PA
- Department of Computational & Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh PA
| | - Ankit Bhatia
- Robotics Institute, Carnegie Mellon University, Pittsburgh, PA
| | - Silvia Picciolini
- Laboratory of Nanomedicine and Clinical Biophotonics (LABION), IRCCS Fondazione Don Carlo Gnocchi, Milan, Italy
| | - Cristiano Carlomagno
- Laboratory of Nanomedicine and Clinical Biophotonics (LABION), IRCCS Fondazione Don Carlo Gnocchi, Milan, Italy
| | - Alice Gualerzi
- Laboratory of Nanomedicine and Clinical Biophotonics (LABION), IRCCS Fondazione Don Carlo Gnocchi, Milan, Italy
| | - Marzia Bedoni
- Laboratory of Nanomedicine and Clinical Biophotonics (LABION), IRCCS Fondazione Don Carlo Gnocchi, Milan, Italy
| | - Bennett Van Houten
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA
| | - Mita Lovalekar
- Department of Sports Medicine and Nutrition, School of Health and Rehabilitation Sciences, University of Pittsburgh, Pittsburgh PA
| | - Nicholas F. Fitz
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA
| | - Iliya Lefterov
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA
| | - Aaron Barchowsky
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA
| | - Radosveta Koldamova
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA
| | - Fabrisia Ambrosio
- Department of Physical Medicine & Rehabilitation, University of Pittsburgh, Pittsburgh, PA
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA
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Fitz NF, Wang J, Kamboh MI, Koldamova R, Lefterov I. Small nucleolar RNAs in plasma extracellular vesicles and their discriminatory power as diagnostic biomarkers of Alzheimer's disease. Neurobiol Dis 2021; 159:105481. [PMID: 34411703 PMCID: PMC9382696 DOI: 10.1016/j.nbd.2021.105481] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 07/20/2021] [Accepted: 08/09/2021] [Indexed: 12/13/2022] Open
Abstract
The clinical diagnosis of Alzheimer’s disease, at its early stage, remains a difficult task. Advanced imaging technologies and laboratory assays to detect Aβ peptides Aβ42 and Aβ400 total and phosphorylated tau in CSF provide a set of biomarkers of developing AD brain pathology and facilitate the diagnostic process. The search for biofiuid biomarkers, other than in CSF, and the development of biomarker assays have accelerated significantly and now represent the fastest-growingfield in AD research. The goal of this study was to determine the differential enrichment of noncoding RNAs (ncRNAs) in plasma-derived extracellular vesicles (EV) of AD patients and Cognitively Normal controls (NC). Using RNA-seq, we profiled four signficant classes of ncRNAs: miRNAs, snoRNAs, tRNAs, and piRNAs. We report a significant enrichment of SNORDs – a group of snoRNAs, in AD samples compared to NC. To verify the differential enrichment of two clusters of SNORDs – SNORD115 and SNORD116, localized on human chromosome 15q11-q13, we used plasma samples of an independent group of AD patients and NC. We applied ddPCR technique and identified SNORD115 and SNORD116 with a high discriminatory power to differentiate AD samples from NC. The results of our study present evidence that AD is associated with changes in the enrichment of SNORDs, transcribed from imprinted genomic loci, in plasma EV and provide a rationale to further explore the validity of those SNORDs as plasma biomarkers of AD.
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Affiliation(s)
- Nicholas F Fitz
- Department of Environmental & Occupational Health, School of Public Health, University of Pittsburgh, Pittsburgh, PA 15261, United States of America
| | - Jiebiao Wang
- Department of Biostatistics, School of Public Health, University of Pittsburgh, Pittsburgh, PA 15261, United States of America
| | - M Ilyas Kamboh
- Department of Human Genetics, School of Public Health, University of Pittsburgh, Pittsburgh, PA 15261, United States of America
| | - Radosveta Koldamova
- Department of Environmental & Occupational Health, School of Public Health, University of Pittsburgh, Pittsburgh, PA 15261, United States of America.
| | - Iliya Lefterov
- Department of Environmental & Occupational Health, School of Public Health, University of Pittsburgh, Pittsburgh, PA 15261, United States of America.
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Fitz NF, Nam KN, Letronne F, Wolfe CM, Playso BE, Lefterov I, Koldamova R. Role of
TREM2
deficiency in Alzheimer’s disease model mice expressing human APOE3 or APOE4. Alzheimers Dement 2020. [DOI: 10.1002/alz.046343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Fitz NF, Wolfe CM, Playso BE, Biedrzycki RJ, Lu Y, Nam KN, Lefterov I, Koldamova R. Trem2 deficiency differentially affects phenotype and transcriptome of human APOE3 and APOE4 mice. Mol Neurodegener 2020; 15:41. [PMID: 32703241 PMCID: PMC7379780 DOI: 10.1186/s13024-020-00394-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 07/16/2020] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Alzheimer's Disease (AD) is a neurodegenerative disorder influenced by aging and genetic risk factors. The inheritance of APOEε4 and variants of Triggering Receptor Expressed on Myeloid cells 2 (TREM2) are major genetic risk factors for AD. Recent studies showed that APOE binds to TREM2, thus raising the possibility of an APOE-TREM2 interaction that can modulate AD pathology. METHODS The aim of this study was to investigate this interaction using complex AD model mice - a crossbreed of Trem2ko and APP/PSEN1dE9 mice expressing human APOE3 or APOE4 isoforms (APP/E3 and APP/E4 respectively), and their WT littermates (E3 and E4), and evaluate cognition, steady-state amyloid load, plaque compaction, plaque growth rate, glial response, and brain transcriptome. RESULTS In both, APP/E3 and APP/E4 mice, Trem2 deletion reduced plaque compaction but did not significantly affect steady-state plaque load. Importantly, the lack of TREM2 increased plaque growth that negatively correlated to the diminished microglia barrier, an effect most pronounced at earlier stages of amyloid deposition. We also found that Trem2 deficiency significantly decreased plaque-associated APOE protein in APP/E4 but not in APP/E3 mice in agreement with RNA-seq data. Interestingly, we observed a significant decrease of Apoe mRNA expression in plaque-associated microglia of APP/E4/Trem2ko vs APP/E4 mice. The absence of TREM2, worsened cognitive performance in APP transgenic mice but not their WT littermates. Gene expression analysis identified Trem2 signature - a cluster of highly connected immune response genes, commonly downregulated as a result of Trem2 deletion in all genotypes including APP and WT littermates. Furthermore, we identified sets of genes that were affected in TREM2- and APOE isoform-dependent manner. Among them were Clec7a and Csf1r upregulated in APP/E4 vs APP/E3 mice, a result further validated by in situ hybridization analysis. In contrast, Tyrobp and several genes involved in the C1Q complement cascade had a higher expression level in APP/E3 versus their APP/E4 counterparts. CONCLUSIONS Our data demonstrate that lack of Trem2 differentially impacts the phenotype and brain transcriptome of APP mice expressing human APOE isoforms. The changes probably reflect the different effect of APOE isoforms on amyloid deposition.
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Affiliation(s)
- Nicholas F. Fitz
- Department of Environmental & Occupational Health, University of Pittsburgh, 130 De Soto Street, Pittsburgh, PA 15261 USA
| | - Cody M. Wolfe
- Department of Environmental & Occupational Health, University of Pittsburgh, 130 De Soto Street, Pittsburgh, PA 15261 USA
| | - Brittany E. Playso
- Department of Environmental & Occupational Health, University of Pittsburgh, 130 De Soto Street, Pittsburgh, PA 15261 USA
| | - Richard J. Biedrzycki
- Department of Environmental & Occupational Health, University of Pittsburgh, 130 De Soto Street, Pittsburgh, PA 15261 USA
| | - Yi Lu
- Department of Environmental & Occupational Health, University of Pittsburgh, 130 De Soto Street, Pittsburgh, PA 15261 USA
| | - Kyong Nyon Nam
- Department of Environmental & Occupational Health, University of Pittsburgh, 130 De Soto Street, Pittsburgh, PA 15261 USA
| | - Iliya Lefterov
- Department of Environmental & Occupational Health, University of Pittsburgh, 130 De Soto Street, Pittsburgh, PA 15261 USA
| | - Radosveta Koldamova
- Department of Environmental & Occupational Health, University of Pittsburgh, 130 De Soto Street, Pittsburgh, PA 15261 USA
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Lefterov I, Wolfe CM, Fitz NF, Nam KN, Letronne F, Biedrzycki RJ, Kofler J, Han X, Wang J, Schug J, Koldamova R. APOE2 orchestrated differences in transcriptomic and lipidomic profiles of postmortem AD brain. Alzheimers Res Ther 2019; 11:113. [PMID: 31888770 PMCID: PMC6937981 DOI: 10.1186/s13195-019-0558-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 11/19/2019] [Indexed: 12/15/2022]
Abstract
BACKGROUND The application of advanced sequencing technologies and improved mass-spectrometry platforms revealed significant changes in gene expression and lipids in Alzheimer's disease (AD) brain. The results so far have prompted further research using "multi-omics" approaches. These approaches become particularly relevant, considering the inheritance of APOEε4 allele as a major genetic risk factor of AD, disease protective effect of APOEε2 allele, and a major role of APOE in brain lipid metabolism. METHODS Postmortem brain samples from inferior parietal lobule genotyped as APOEε2/c (APOEε2/carriers), APOEε3/3, and APOEε4/c (APOEε4/carriers), age- and gender-matched, were used to reveal APOE allele-associated changes in transcriptomes and lipidomes. Differential gene expression and co-expression network analyses were applied to identify up- and downregulated Gene Ontology (GO) terms and pathways for correlation to lipidomics data. RESULTS Significantly affected GO terms and pathways were determined based on the comparisons of APOEε2/c datasets to those of APOEε3/3 and APOEε4/c brain samples. The analysis of lists of genes in highly correlated network modules and of those differentially expressed demonstrated significant enrichment in GO terms associated with genes involved in intracellular proteasomal and lysosomal degradation of proteins, protein aggregates and organelles, ER stress, and response to unfolded protein, as well as mitochondrial function, electron transport, and ATP synthesis. Small nucleolar RNA coding units important for posttranscriptional modification of mRNA and therefore translation and protein synthesis were upregulated in APOEε2/c brain samples compared to both APOEε3/3 and APOEε4/c. The analysis of lipidomics datasets revealed significant changes in ten major lipid classes (exclusively a decrease in APOEε4/c samples), most notably non-bilayer-forming phosphatidylethanolamine and phosphatidic acid, as well as mitochondrial membrane-forming lipids. CONCLUSIONS The results of this study, despite the advanced stage of AD, point to the significant differences in postmortem brain transcriptomes and lipidomes, suggesting APOE allele associated differences in pathogenic mechanisms. Correlations within and between lipidomes and transcriptomes indicate coordinated effects of changes in the proteasomal system and autophagy-canonical and selective, facilitating intracellular degradation, protein entry into ER, response to ER stress, nucleolar modifications of mRNA, and likely myelination in APOEε2/c brains. Additional research and a better knowledge of the molecular mechanisms of proteostasis in the early stages of AD are required to develop more effective diagnostic approaches and eventually efficient therapeutic strategies.
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Affiliation(s)
- Iliya Lefterov
- Department of Environmental and Occupational Health, University of Pittsburgh, 130 De Soto Str., Pittsburgh, PA, 15261, USA.
| | - Cody M Wolfe
- Department of Environmental and Occupational Health, University of Pittsburgh, 130 De Soto Str., Pittsburgh, PA, 15261, USA
| | - Nicholas F Fitz
- Department of Environmental and Occupational Health, University of Pittsburgh, 130 De Soto Str., Pittsburgh, PA, 15261, USA
| | - Kyong Nyon Nam
- Department of Environmental and Occupational Health, University of Pittsburgh, 130 De Soto Str., Pittsburgh, PA, 15261, USA
| | - Florent Letronne
- Department of Environmental and Occupational Health, University of Pittsburgh, 130 De Soto Str., Pittsburgh, PA, 15261, USA
| | - Richard J Biedrzycki
- Department of Environmental and Occupational Health, University of Pittsburgh, 130 De Soto Str., Pittsburgh, PA, 15261, USA
| | - Julia Kofler
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15219, USA
| | - Xianlin Han
- Department of Medicine & Biochemistry, Barshop Institute for Longevity and Aging Studies, UT Health-San Antonio, San Antonio, TX, 78229, USA
| | - Jianing Wang
- Department of Medicine & Biochemistry, Barshop Institute for Longevity and Aging Studies, UT Health-San Antonio, San Antonio, TX, 78229, USA
| | - Jonathan Schug
- Department of Genetics, Functional Genomics Core, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Radosveta Koldamova
- Department of Environmental and Occupational Health, University of Pittsburgh, 130 De Soto Str., Pittsburgh, PA, 15261, USA.
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Fitz NF, Nam KN, Koldamova R, Lefterov I. Therapeutic targeting of nuclear receptors, liver X and retinoid X receptors, for Alzheimer's disease. Br J Pharmacol 2019; 176:3599-3610. [PMID: 30924124 PMCID: PMC6715597 DOI: 10.1111/bph.14668] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 02/15/2019] [Accepted: 02/24/2019] [Indexed: 12/18/2022] Open
Abstract
After 15 years of research into Alzheimer's disease (AD) therapeutics, including billions of US dollars provided by federal agencies, pharmaceutical companies, and private foundations, there are still no meaningful therapies that can delay the onset or slow the progression of AD. An understanding of the proteolytic processing of amyloid precursor protein (APP) and the hypothesis that pathogenic mechanisms in familial and sporadic forms of AD are very similar led to the assumption that pharmacological inhibition of secretases or immunological approaches to clear amyloid depositions in the brain would have been the core to drug discovery strategies and successful therapies. However, there are other understudied approaches including targeting genes, gene networks, and metabolic pathways outside the proteolytic processing of APP. The advancement of newly developed sequencing technologies and mass spectrometry, as well as the availability of animal models expressing human apolipoprotein E isoforms, has been critical in rationalizing additional AD therapeutics. The purpose of this review is to present one of those approaches, based on the role of ligand-activated nuclear liver X and retinoid X receptors in the brain. This therapeutic approach was initially proposed utilizing in vitro models 15 years ago and has since been examined in numerous studies using AD-like mouse models. LINKED ARTICLES: This article is part of a themed section on Therapeutics for Dementia and Alzheimer's Disease: New Directions for Precision Medicine. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.18/issuetoc.
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Affiliation(s)
- Nicholas F Fitz
- Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Kyong Nyon Nam
- Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Radosveta Koldamova
- Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Iliya Lefterov
- Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania
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Castranio EL, Wolfe CM, Nam KN, Letronne F, Fitz NF, Lefterov I, Koldamova R. ABCA1 haplodeficiency affects the brain transcriptome following traumatic brain injury in mice expressing human APOE isoforms. Acta Neuropathol Commun 2018; 6:69. [PMID: 30049279 PMCID: PMC6062955 DOI: 10.1186/s40478-018-0569-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 07/12/2018] [Indexed: 02/07/2023] Open
Abstract
Expression of human Apolipoprotein E (APOE) modulates the inflammatory response in an isoform specific manner, with APOE4 isoform eliciting a stronger pro-inflammatory response, suggesting a possible mechanism for worse outcome following traumatic brain injury (TBI). APOE lipidation and stability is modulated by ATP-binding cassette transporter A1 (ABCA1), a transmembrane protein that transports lipids and cholesterol onto APOE. We examined the impact of Abca1 deficiency and APOE isoform expression on the response to TBI using 3-months-old, human APOE3+/+ (E3/Abca1+/+) and APOE4+/+ (E4/Abca1+/+) targeted replacement mice, and APOE3+/+ and APOE4+/+ mice with only one functional copy of the Abca1 gene (E3/Abca1+/-; E4/Abca1+/-). TBI-treated mice received a craniotomy followed by a controlled cortical impact (CCI) brain injury in the left hemisphere; sham-treated mice received the same surgical procedure without the impact. We performed RNA-seq using samples from cortices and hippocampi followed by genome-wide differential gene expression analysis. We found that TBI significantly impacted unique transcripts within each group, however, the proportion of unique transcripts was highest in E4/Abca1+/- mice. Additionally, we found that Abca1 haplodeficiency increased the expression of microglia sensome genes among only APOE4 injured mice, a response not seen in injured APOE3 mice, nor in either group of sham-treated mice. To identify gene networks, or modules, correlated to TBI, APOE isoform and Abca1 haplodeficiency, we used weighted gene co-expression network analysis (WGCNA). The module that positively correlated to TBI groups was associated with immune response and featured hub genes that were microglia-specific, including Trem2, Tyrobp, Cd68 and Hexb. The modules positively correlated with APOE4 isoform and negatively to Abca1 haplodeficient mice represented "protein translation" and "oxidation-reduction process", respectively. Our results reveal E4/Abca1+/- TBI mice have a distinct response to injury, and unique gene networks are associated with APOE isoform, Abca1 insufficiency and injury.
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Affiliation(s)
- Emilie L Castranio
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, 15261, USA
| | - Cody M Wolfe
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, 15261, USA
| | - Kyong Nyon Nam
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, 15261, USA
| | - Florent Letronne
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, 15261, USA
| | - Nicholas F Fitz
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, 15261, USA
| | - Iliya Lefterov
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, 15261, USA.
| | - Radosveta Koldamova
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, 15261, USA.
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Koldamova R, Lefterov I, Fitz NF, Nam KN, Wolfe CM, Iordanova B, Koldamova R, Lefterov I. P4‐051: EFFECT OF APOE ISOFORM ON MICROGLIAL RESPONSE TO AMYLOID‐BETA. Alzheimers Dement 2018. [DOI: 10.1016/j.jalz.2018.06.2454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Lefterov I, Fitz NF, Wolfe CM, Nam KN, Letronne F, Kofler J, Han X, Schug J, Koldamova R. P4‐253: MULTI‐OMICS PROFILING IDENTIFIES APOE‐ALLELE‐ASSOCIATED LIPID AND GENE EXPRESSION PATTERNS IN ALZHEIMER'S DISEASE. Alzheimers Dement 2018. [DOI: 10.1016/j.jalz.2018.07.075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
| | | | | | | | | | | | - Xianlin Han
- University of Texas Health Sciences Center, San AntonioSan AntonioTXUSA
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Fitz NF, Carter AY, Tapias V, Castranio EL, Kodali R, Lefterov I, Koldamova R. ABCA1 Deficiency Affects Basal Cognitive Deficits and Dendritic Density in Mice. J Alzheimers Dis 2018; 56:1075-1085. [PMID: 28106559 PMCID: PMC5302049 DOI: 10.3233/jad-161056] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
ATP-binding cassette transporter A1 (ABCA1) mediates cholesterol efflux to lipid-free apolipoproteins and regulates the generation of high density lipoproteins. Previously, we have shown that lack of Abca1 significantly increases amyloid deposition and cognitive deficits in Alzheimer’s disease model mice expressing human amyloid-β protein precursor (APP). The goal of this study was to determine if ABCA1 plays a role in memory deficits caused by amyloid-β (Aβ) oligomers and examine neurite architecture of pyramidal hippocampal neurons. Our results confirm previous findings that Abca1 deficiency significantly impairs spatial memory acquisition and retention in the Morris water maze and long-term memory in novel object recognition of APP transgenic mice at a stage of early amyloid pathology. Neither test demonstrated a significant difference between Abca1ko and wild-type (WT) mice. We also examined the effect of intra-hippocampal infused Aβ oligomers on cognitive performance of Abca1ko mice, compared to control infusion of scrambled Aβ peptide. Age-matched WT mice undergoing the same infusions were also used as controls. In this model system, we found a statistically significant difference between WT and Abca1ko mice infused with scrambled Aβ, suggesting that Abca1ko mice are vulnerable to the effect of mild stresses. Moreover, examination of neurite architecture in the hippocampi revealed a significant decrease in neurite length, number of neurite segments, and branches in Abca1ko mice when compared to WT mice. We conclude that mice lacking ABCA1 have basal cognitive deficits that prevent them from coping with additional stressors, which is in part due to impairment of neurite morphology in the hippocampus.
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Affiliation(s)
- Nicholas F Fitz
- Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Alexis Y Carter
- Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Victor Tapias
- Department of Neurology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Emilie L Castranio
- Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Ravindra Kodali
- Department of Structural Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Iliya Lefterov
- Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Radosveta Koldamova
- Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
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Rompala GR, Mounier A, Wolfe CM, Lin Q, Lefterov I, Homanics GE. Heavy Chronic Intermittent Ethanol Exposure Alters Small Noncoding RNAs in Mouse Sperm and Epididymosomes. Front Genet 2018; 9:32. [PMID: 29472946 PMCID: PMC5809758 DOI: 10.3389/fgene.2018.00032] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 01/24/2018] [Indexed: 02/02/2023] Open
Abstract
While the risks of maternal alcohol abuse during pregnancy are well-established, several preclinical studies suggest that chronic preconception alcohol consumption by either parent may also have significance consequences for offspring health and development. Notably, since isogenic male mice used in these studies are not involved in gestation or rearing of offspring, the cross-generational effects of paternal alcohol exposure suggest a germline-based epigenetic mechanism. Many recent studies have demonstrated that the effects of paternal environmental exposures such as stress or malnutrition can be transmitted to the next generation via alterations to small noncoding RNAs in sperm. Therefore, we used high throughput sequencing to examine the effect of preconception ethanol on small noncoding RNAs in sperm. We found that chronic intermittent ethanol exposure altered several small noncoding RNAs from three of the major small RNA classes in sperm, tRNA-derived small RNA (tDR), mitochondrial small RNA, and microRNA. Six of the ethanol-responsive small noncoding RNAs were evaluated with RT-qPCR on a separate cohort of mice and five of the six were confirmed to be altered by chronic ethanol exposure, supporting the validity of the sequencing results. In addition to altered sperm RNA abundance, chronic ethanol exposure affected post-transcriptional modifications to sperm small noncoding RNAs, increasing two nucleoside modifications previously identified in mitochondrial tRNA. Furthermore, we found that chronic ethanol reduced epididymal expression of a tRNA methyltransferase, Nsun2, known to directly regulate tDR biogenesis. Finally, ethanol-responsive sperm tDR are similarly altered in extracellular vesicles of the epididymis (i.e., epididymosomes), supporting the hypothesis that alterations to sperm tDR emerge in the epididymis and that epididymosomes are the primary source of small noncoding RNAs in sperm. These results add chronic ethanol to the growing list of paternal exposures that can affect small noncoding RNA abundance and nucleoside modifications in sperm. As small noncoding RNAs in sperm have been shown to causally induce heritable phenotypes in offspring, additional research is warranted to understand the potential effects of ethanol-responsive sperm small noncoding RNAs on offspring health and development.
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Affiliation(s)
- Gregory R Rompala
- Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, United States
| | - Anais Mounier
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, United States
| | - Cody M Wolfe
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, United States
| | - Qishan Lin
- Mass Spectrometry Facility, Center for Functional Genomics, University at Albany, Rensselaer, NY, United States
| | - Iliya Lefterov
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, United States
| | - Gregg E Homanics
- Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, United States.,Department of Anesthesiology, University of Pittsburgh, Pittsburgh, PA, United States.,Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, United States.,Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, United States
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Nam KN, Wolfe CM, Fitz NF, Letronne F, Castranio EL, Mounier A, Schug J, Lefterov I, Koldamova R. Integrated approach reveals diet, APOE genotype and sex affect immune response in APP mice. Biochim Biophys Acta Mol Basis Dis 2018; 1864:152-161. [PMID: 29038051 PMCID: PMC5714325 DOI: 10.1016/j.bbadis.2017.10.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 10/04/2017] [Accepted: 10/12/2017] [Indexed: 01/02/2023]
Abstract
Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder that is influenced by genetic and environmental risk factors, such as inheritance of ε4 allele of APOE (APOE4), sex and diet. Here, we examined the effect of high fat diet (HFD) on amyloid pathology and expression profile in brains of AD model mice expressing human APOE isoforms (APP/E3 and APP/E4 mice). APP/E3 and APP/E4 mice were fed HFD or Normal diet for 3months. We found that HFD significantly increased amyloid plaques in male and female APP/E4, but not in APP/E3 mice. To identify differentially expressed genes and gene-networks correlated to diet, APOE isoform and sex, we performed RNA sequencing and applied Weighted Gene Co-expression Network Analysis. We determined that the immune response network with major hubs Tyrobp/DAP12, Csf1r, Tlr2, C1qc and Laptm5 correlated significantly and positively to the phenotype of female APP/E4-HFD mice. Correspondingly, we found that in female APP/E4-HFD mice, microglia coverage around plaques, particularly of larger size, was significantly reduced. This suggests altered containment of the plaque growth and sex-dependent vulnerability in response to diet. The results of our study show concurrent impact of diet, APOE isoform and sex on the brain transcriptome and AD-like phenotype.
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Affiliation(s)
- Kyong Nyon Nam
- Department of Environmental and Occupational Health, University of Pittsburgh, United States
| | - Cody M Wolfe
- Department of Environmental and Occupational Health, University of Pittsburgh, United States
| | - Nicholas F Fitz
- Department of Environmental and Occupational Health, University of Pittsburgh, United States
| | - Florent Letronne
- Department of Environmental and Occupational Health, University of Pittsburgh, United States
| | - Emilie L Castranio
- Department of Environmental and Occupational Health, University of Pittsburgh, United States
| | - Anais Mounier
- Department of Environmental and Occupational Health, University of Pittsburgh, United States
| | - Jonathan Schug
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - Iliya Lefterov
- Department of Environmental and Occupational Health, University of Pittsburgh, United States.
| | - Radosveta Koldamova
- Department of Environmental and Occupational Health, University of Pittsburgh, United States.
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Castranio EL, Mounier A, Wolfe CM, Nam KN, Fitz NF, Letronne F, Schug J, Koldamova R, Lefterov I. Gene co-expression networks identify Trem2 and Tyrobp as major hubs in human APOE expressing mice following traumatic brain injury. Neurobiol Dis 2017; 105:1-14. [PMID: 28502803 DOI: 10.1016/j.nbd.2017.05.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 05/01/2017] [Accepted: 05/10/2017] [Indexed: 01/09/2023] Open
Abstract
Traumatic brain injury (TBI) is strongly linked to an increased risk of developing dementia, including chronic traumatic encephalopathy and possibly Alzheimer's disease (AD). APOEε4 allele of human Apolipoprotein E (APOE) gene is the major genetic risk factor for late onset AD and has been associated with chronic traumatic encephalopathy and unfavorable outcome following TBI. To determine if there is an APOE isoform-specific response to TBI we performed controlled cortical impact on 3-month-old mice expressing human APOE3 or APOE4 isoforms. Following injury, we used several behavior paradigms to test for anxiety and learning and found that APOE3 and APOE4 targeted replacement mice demonstrate cognitive impairments following moderate TBI. Transcriptional profiling 14days following injury revealed a significant effect of TBI, which was similar in both genotypes. Significantly upregulated by injury in both genotypes were mRNA expression and protein level of ABCA1 transporter and APOJ, but not APOE. To identify gene-networks correlated to injury and APOE isoform, we performed Weighted Gene Co-expression Network Analysis. We determined that the network mostly correlated to TBI in animals expressing both isoforms is immune response with major hub genes including Trem2, Tyrobp, Clec7a and Cd68. We also found a significant increase of TREM2, IBA-1 and GFAP protein levels in the brains of injured mice. We identified a network representing myelination that correlated significantly with APOE isoform in both injury groups. This network was significantly enriched in oligodendrocyte signature genes, such as Mbp and Plp1. Our results demonstrate unique and distinct gene networks at this acute time point for injury and APOE isoform, as well as a network driven by APOE isoform across TBI groups.
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Affiliation(s)
- Emilie L Castranio
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA
| | - Anais Mounier
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA
| | - Cody M Wolfe
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA
| | - Kyong Nyon Nam
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA
| | - Nicholas F Fitz
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA
| | - Florent Letronne
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA
| | - Jonathan Schug
- Functional Genomics Core, Department of Genetics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Radosveta Koldamova
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA.
| | - Iliya Lefterov
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA.
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Carter AY, Letronne F, Fitz NF, Mounier A, Wolfe CM, Nam KN, Reeves VL, Kamboh H, Lefterov I, Koldamova R. Liver X receptor agonist treatment significantly affects phenotype and transcriptome of APOE3 and APOE4 Abca1 haplo-deficient mice. PLoS One 2017; 12:e0172161. [PMID: 28241068 PMCID: PMC5328633 DOI: 10.1371/journal.pone.0172161] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Accepted: 01/31/2017] [Indexed: 12/13/2022] Open
Abstract
ATP-binding cassette transporter A1 (ABCA1) controls cholesterol and phospholipid efflux to lipid-poor apolipoprotein E (APOE) and is transcriptionally controlled by Liver X receptors (LXRs) and Retinoic X Receptors (RXRs). In APP transgenic mice, lack of Abca1 increased Aβ deposition and cognitive deficits. Abca1 haplo-deficiency in mice expressing human APOE isoforms, increased level of Aβ oligomers and worsened memory deficits, preferentially in APOE4 mice. In contrast upregulation of Abca1 by LXR/RXR agonists significantly ameliorated pathological phenotype of those mice. The goal of this study was to examine the effect of LXR agonist T0901317 (T0) on the phenotype and brain transcriptome of APP/E3 and APP/E4 Abca1 haplo-deficient (APP/E3/Abca1+/- and APP/E4/Abca1+/-) mice. Our data demonstrate that activated LXRs/RXR ameliorated APOE4-driven pathological phenotype and significantly affected brain transcriptome. We show that in mice expressing either APOE isoform, T0 treatment increased mRNA level of genes known to affect brain APOE lipidation such as Abca1 and Abcg1. In both APP/E3/Abca1+/- and APP/E4/Abca1+/- mice, the application of LXR agonist significantly increased ABCA1 protein level accompanied by an increased APOE lipidation, and was associated with restoration of APOE4 cognitive deficits, reduced levels of Aβ oligomers, but unchanged amyloid load. Finally, using Gene set enrichment analysis we show a significant APOE isoform specific response to LXR agonist treatment: Gene Ontology categories “Microtubule Based Process” and “Synapse Organization” were differentially affected in T0-treated APP/E4/Abca1+/- mice. Altogether, the results are suggesting that treatment of APP/E4/Abca1+/- mice with LXR agonist T0 ameliorates APOE4-induced AD-like pathology and therefore targeting the LXR-ABCA1-APOE regulatory axis could be effective as a potential therapeutic approach in AD patients, carriers of APOEε4.
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Affiliation(s)
- Alexis Y. Carter
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Florent Letronne
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Nicholas F. Fitz
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Anais Mounier
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Cody M. Wolfe
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Kyong Nyon Nam
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Valerie L. Reeves
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Hafsa Kamboh
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Iliya Lefterov
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, USA
- * E-mail: (RK); (IL)
| | - Radosveta Koldamova
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, USA
- * E-mail: (RK); (IL)
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Fitz NF, Carter AY, Nam KN, Castranio EL, Mounier A, Wolfe CM, Lefterov I, Koldamova R. P4‐065: Impact of Apoe Polymorphisms on Amyloid‐Beta Oligomerization and Associated Cognitive Decline. Alzheimers Dement 2016. [DOI: 10.1016/j.jalz.2016.06.2155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Nam KN, Mounier A, Fitz NF, Wolfe C, Schug J, Lefterov I, Koldamova R. RXR controlled regulatory networks identified in mouse brain counteract deleterious effects of Aβ oligomers. Sci Rep 2016; 6:24048. [PMID: 27051978 PMCID: PMC4823697 DOI: 10.1038/srep24048] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 03/16/2016] [Indexed: 11/21/2022] Open
Abstract
Bexarotene, a selective agonist for Retinoid X receptors (RXR) improves cognitive deficits and amyloid-β (Aβ) clearance in mice. Here we examine if the effect of bexarotene on RXR cistrome and transcriptomes depend on APOE isoform and Aβ deposition. We found bexarotene increased RXR binding to promoter regions in cortex of APOE3 mice. Rho family GTPases and Wnt signaling pathway were highly enriched in ChIP-seq and RNA-seq datasets and members of those pathways - Lrp1, Lrp5, Sfrp5 and Sema3f were validated. The effect of APOE isoform was compared in APOE3 and APOE4 mice and we found significant overlapping in affected pathways. ChIP-seq using mouse embryonic stem cells and enrichment levels of histone marks H3K4me3 and H3K27me3 revealed that, bexarotene induced epigenetic changes, consistent with increased neuronal differentiation and in correlation with changes in transcription. Comparison of transcriptome in APOE3 and APP/APOE3 mice revealed that amyloid deposition significantly affects the response to bexarotene. In primary neurons, bexarotene ameliorated the damaged dendrite complexity and loss of neurites caused by Aβ42. Finally, we show that the disruption of actin cytoskeleton induced by Aβ42in vitro was inhibited by bexarotene treatment. Our results suggest a mechanism to establish RXR therapeutic targets with significance in neurodegeneration.
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Affiliation(s)
- Kyong Nyon Nam
- Department of Environmental &Occupational Health, University of Pittsburgh, Pittsburgh, PA, 15219, USA
| | - Anais Mounier
- Department of Environmental &Occupational Health, University of Pittsburgh, Pittsburgh, PA, 15219, USA
| | - Nicholas F Fitz
- Department of Environmental &Occupational Health, University of Pittsburgh, Pittsburgh, PA, 15219, USA
| | - Cody Wolfe
- Department of Environmental &Occupational Health, University of Pittsburgh, Pittsburgh, PA, 15219, USA
| | - Jonathan Schug
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Iliya Lefterov
- Department of Environmental &Occupational Health, University of Pittsburgh, Pittsburgh, PA, 15219, USA
| | - Radosveta Koldamova
- Department of Environmental &Occupational Health, University of Pittsburgh, Pittsburgh, PA, 15219, USA
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Fitz NF, Tapias V, Cronican AA, Castranio EL, Saleem M, Carter AY, Lefterova M, Lefterov I, Koldamova R. Opposing effects of Apoe/Apoa1 double deletion on amyloid-β pathology and cognitive performance in APP mice. Brain 2015; 138:3699-715. [PMID: 26510953 DOI: 10.1093/brain/awv293] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2015] [Accepted: 08/14/2015] [Indexed: 11/14/2022] Open
Abstract
UNLABELLED ATP binding cassette transporter A1 (encoded by ABCA1) regulates cholesterol efflux from cells to apolipoproteins A-I and E (ApoA-I and APOE; encoded by APOA1 and APOE, respectively) and the generation of high density lipoproteins. In Abca1 knockout mice (Abca1(ko)), high density lipoproteins and ApoA-I are virtually lacking, and total APOE and APOE-containing lipoproteins in brain substantially decreased. As the ε4 allele of APOE is the major genetic risk factor for late-onset Alzheimer's disease, ABCA1 role as a modifier of APOE lipidation is of significance for this disease. Reportedly, Abca1 deficiency in mice expressing human APP accelerates amyloid deposition and behaviour deficits. We used APP/PS1dE9 mice crossed to Apoe and Apoa1 knockout mice to generate Apoe/Apoa1 double-knockout mice. We hypothesized that Apoe/Apoa1 double-knockout mice would mimic the phenotype of APP/Abca1(ko) mice in regards to amyloid plaques and cognitive deficits. Amyloid pathology, peripheral lipoprotein metabolism, cognitive deficits and dendritic morphology of Apoe/Apoa1 double-knockout mice were compared to APP/Abca1(ko), APP/PS1dE9, and single Apoa1 and Apoe knockouts. Contrary to our prediction, the results demonstrate that double deletion of Apoe and Apoa1 ameliorated the amyloid pathology, including amyloid plaques and soluble amyloid. In double knockout mice we show that (125)I-amyloid-β microinjected into the central nervous system cleared at a rate twice faster compared to Abca1 knockout mice. We tested the effect of Apoe, Apoa1 or Abca1 deficiency on spreading of exogenous amyloid-β seeds injected into the brain of young pre-depositing APP mice. The results show that lack of Abca1 augments dissemination of exogenous amyloid significantly more than the lack of Apoe. In the periphery, Apoe/Apoa1 double-knockout mice exhibited substantial atherosclerosis and very high levels of low density lipoproteins compared to APP/PS1dE9 and APP/Abca1(ko). Plasma level of amyloid-β42 measured at several time points for each mouse was significantly higher in Apoe/Apoa1 double-knockout then in APP/Abca1(ko) mice. This result demonstrates that mice with the lowest level of plasma lipoproteins, APP/Abca1(ko), have the lowest level of peripheral amyloid-β. Unexpectedly, and independent of amyloid pathology, the deletion of both apolipoproteins worsened behaviour deficits of double knockout mice and their performance was undistinguishable from those of Abca1 knockout mice. Finally we observed that the dendritic complexity in the CA1 region of hippocampus but not in CA2 is significantly impaired by Apoe/Apoa1 double deletion as well as by lack of ABCA1. IN CONCLUSION (i) plasma lipoproteins may affect amyloid-β clearance from the brain by the 'peripheral sink' mechanism; and (ii) deficiency of brain APOE-containing lipoproteins is of significance for dendritic complexity and cognition.
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Affiliation(s)
- Nicholas F Fitz
- 1 Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA
| | - Victor Tapias
- 2 Department of Neurology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Andrea A Cronican
- 1 Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA
| | - Emilie L Castranio
- 1 Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA
| | - Muzamil Saleem
- 3 Biological Sciences, Bayer School of Natural and Environmental Sciences, Duquesne University, Pittsburgh, PA 15282, USA
| | - Alexis Y Carter
- 1 Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA
| | - Martina Lefterova
- 4 Department of Pathology, Stanford University, Stanford, CA 94305, USA
| | - Iliya Lefterov
- 1 Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA
| | - Radosveta Koldamova
- 1 Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA
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Lefterov I, Koldamova R. Metabolic Disorders and Neurodegeneration, introduction to the special issue. Neurobiol Dis 2015; 72 Pt A:1-2. [PMID: 25301714 DOI: 10.1016/j.nbd.2014.09.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Lefterov I, Schug J, Mounier A, Nam KN, Fitz NF, Koldamova R. RNA-sequencing reveals transcriptional up-regulation of Trem2 in response to bexarotene treatment. Neurobiol Dis 2015; 82:132-140. [PMID: 26071899 DOI: 10.1016/j.nbd.2015.05.019] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Revised: 05/15/2015] [Accepted: 05/28/2015] [Indexed: 01/08/2023] Open
Abstract
We have recently demonstrated that short term bexarotene treatment of APP/PS1 mice significantly improves their cognitive performance. While there were no changes in plaque load, or insoluble Aβ levels in brain, biochemical analysis strongly suggested improved clearance of soluble Aβ, including Aβ oligomers. To get further insight into molecular mechanisms underlying this therapeutic effect, we explored genome-wide differential gene expression in brain of bexarotene and control treated APP/PS1 mice. We performed high throughput massively parallel sequencing on mRNA libraries generated from cortices of bexarotene or vehicle treated APP/PS1 mice and compared the expression profiles for differential gene expression. Gene Ontology (GO) Biological Process categories with the highest fold enrichment and lowest False Discovery Rate (FDR) are clustered in GO terms immune response, inflammatory response, oxidation-reduction and immunoglobulin mediated immune response. Chromatin immunoprecipitation (ChIP) followed by ChIP-QPCR, and RT-QPCR expression assays were used to validate select genes, including Trem2, Tyrobp, Apoe and Ttr, differentially expressed in response to Retinoid X Receptor (RXR) activation. We found that bexarotene significantly increased the phagocytosis of soluble and insoluble Aβ in BV2 cells. The results of our study demonstrate that in AD model mice expressing human APP, gene networks up-regulated in response to RXR activation by the specific, small molecule, ligand bexarotene may influence diverse regulatory pathways that are considered critical for cognitive performance, inflammatory response and Aβ clearance, and may provide an explanation of the bexarotene therapeutic effect at the molecular level. This study also confirms that unbiased massive parallel sequencing approaches are useful and highly informative for revealing brain molecular and cellular mechanisms underlying responses to activated nuclear hormone receptors in AD animal models.
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Affiliation(s)
- Iliya Lefterov
- Department of Environmental & Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA.
| | - Jonathan Schug
- Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania, Philadelphia, PA 19104, USA; Functional Genomics Core, Department of Genetics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Anais Mounier
- Department of Environmental & Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA
| | - Kyong Nyon Nam
- Department of Environmental & Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA
| | - Nicholas F Fitz
- Department of Environmental & Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA
| | - Radosveta Koldamova
- Department of Environmental & Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA.
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Fitz NF, Castranio EL, Carter AY, Kodali R, Lefterov I, Koldamova R. Improvement of memory deficits and amyloid-β clearance in aged APP23 mice treated with a combination of anti-amyloid-β antibody and LXR agonist. J Alzheimers Dis 2015; 41:535-49. [PMID: 24643138 DOI: 10.3233/jad-132789] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Passive amyloid-β (Aβ) vaccination has shown significant effects on amyloid pathology in pre-depositing amyloid-β protein precursor (AβPP) mice but the results in older mice are inconsistent. A therapeutic effect of LXR and RXR agonists consisting of improved memory deficits and Aβ pathology has been demonstrated in different Alzheimer's disease (AD) mouse models. Here, we report the effect of a combination of N-terminal Aβ antibody and synthetic LXR agonist T0901317 (T0) on AD-like phenotype of APP23 mice. To examine the therapeutic potential of this combination, the treatment of mice started at 11 months of age, when amyloid phenotype in this model is fully developed, and continued for 50 days. We show that Aβ immunization with or without LXR agonist restored the performance of APP23 transgenic mice in two behavior paradigms without affecting the existing amyloid plaques. Importantly, we did not observe an increase of brain microhemorrhage which is considered a significant side effect of Aβ vaccination. Target engagement was confirmed by increased Abca1 and ApoE protein level as well as increased ApoE lipidation in soluble brain extract. In interstitial fluid obtained by microdialysis, we demonstrate that immunization and T0 significantly reduced Aβ levels, indicating an increased Aβ clearance. We found no interaction between the immunotherapy and T0, suggesting no synergism, at least with these doses. The results of our study demonstrate that anti-Aβ treatments can ameliorate cognitive deficits in AβPP mice with advanced AD-like phenotype in conjunction with a decrease of Aβ in brain interstitium and increase of ApoE lipidation without affecting the existing amyloid plaques.
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Affiliation(s)
- Nicholas F Fitz
- Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Emilie L Castranio
- Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Alexis Y Carter
- Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Ravindra Kodali
- Department of Structural Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Iliya Lefterov
- Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Radosveta Koldamova
- Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
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Koldamova R, Fitz NF, Lefterov I. ATP-binding cassette transporter A1: from metabolism to neurodegeneration. Neurobiol Dis 2014; 72 Pt A:13-21. [PMID: 24844148 PMCID: PMC4302328 DOI: 10.1016/j.nbd.2014.05.007] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Revised: 05/01/2014] [Accepted: 05/06/2014] [Indexed: 01/04/2023] Open
Abstract
ATP-binding cassette transporter A1 (ABCA1) mediates cholesterol efflux to lipid-free apolipoprotein A-I (apoA-I) and apolipoprotein E (apoE). ABCA1 is an essential regulator of high density lipoproteins (HDL) and reverse cholesterol transport - a role that determines its importance for atherosclerosis. Over the last 10 years studies have provided convincing evidence that ABCA1, via its control of apoE lipidation, also has a role in Alzheimer's disease (AD). A series of reports have revealed a significant impact of ABCA1 on Aβ deposition and clearance in AD model mice, as well as an association of common and rare ABCA1 gene variants with the risk for AD. Since APOE is the major genetic risk factor for late onset AD, the regulation of apoE level or its functionality by ABCA1 may prove significant for AD pathogenesis. ABCA1 is transcriptionally regulated by Liver X Receptors (LXR) and Retinoic X Receptors (RXR) which provides a starting point for drug discovery and development of synthetic LXR and RXR agonists for treatment of metabolic and neurodegenerative disorders. This review summarizes the recent results of research on ABCA1, particularly relevant to atherosclerosis and AD.
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Affiliation(s)
- Radosveta Koldamova
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA.
| | - Nicholas F Fitz
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA
| | - Iliya Lefterov
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA.
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Fitz N, Castranio E, Carter A, Lefterov I, Koldamova R. P1‐074: EFFECTS OF APOLIPOPROTEIN E ON COGNITIVE PERFORMANCE AND AMYLOID OLIGOMERIZATION IN A MOUSE MODEL. Alzheimers Dement 2014. [DOI: 10.1016/j.jalz.2014.05.310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Nicholas Fitz
- University of PittsburghPittsburghPennsylvaniaUnited States
| | | | - Alexis Carter
- University of PittsburghPittsburghPennsylvaniaUnited States
| | - Iliya Lefterov
- University of PittsburghPittsburghPennsylvaniaUnited States
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Koldamova R, Schug J, Lefterova M, Cronican AA, Fitz NF, Davenport FA, Carter A, Castranio EL, Lefterov I. Genome-wide approaches reveal EGR1-controlled regulatory networks associated with neurodegeneration. Neurobiol Dis 2013; 63:107-14. [PMID: 24269917 DOI: 10.1016/j.nbd.2013.11.005] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 10/17/2013] [Accepted: 11/12/2013] [Indexed: 11/29/2022] Open
Abstract
Early growth response gene 1 (Egr1) is a member of the immediate early gene (IEG) family of transcription factors and plays a role in memory formation. To identify EGR1 target genes in brain of Alzheimer's disease (AD) model mice - APP23, we applied chromatin immunoprecipitation (ChIP) followed by high-throughput DNA sequencing (ChIP-seq). Functional annotation of genes associated with EGR1 binding revealed a set of related networks including synaptic vesicle transport, clathrin-mediated endocytosis (CME), intracellular membrane fusion and transmission of signals elicited by Ca(2+) influx. EGR1 binding is associated with significant enrichment of activating chromatin marks and appears enriched near genes that are up-regulated in the brains of APP23 mice. Among the putative EGR1 targets identified and validated in this study are genes related to synaptic plasticity and transport of proteins, such as Arc, Grin1, Syn2, Vamp2 and Stx6, and genes implicated in AD such as Picalm, Psen2 and App. We also demonstrate a potential regulatory link between EGR1 and its newly identified targets in vivo, since conditions that up-regulate Egr1 levels in brain, such as a spatial memory test, also lead to increased expression of the targets. On the other hand, protein levels of EGR1 and ARC, SYN2, STX6 and PICALM are significantly lower in the brain of adult APP mice than in age-matched wild type animals. The results of this study suggest that EGR1 regulates the expression of genes involved in CME, vesicular transport and synaptic transmission that may be critical for AD pathogenesis.
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Affiliation(s)
- Radosveta Koldamova
- Department of Environmental & Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA.
| | - Jonathan Schug
- Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania, Philadelphia, PA 19104, USA; Functional Genomics Core, Department of Genetics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Martina Lefterova
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Andrea A Cronican
- Department of Environmental & Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA
| | - Nicholas F Fitz
- Department of Environmental & Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA
| | - Faith A Davenport
- Department of Environmental & Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA
| | - Alexis Carter
- Department of Environmental & Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA
| | - Emilie L Castranio
- Department of Environmental & Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA
| | - Iliya Lefterov
- Department of Environmental & Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA.
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Fitz NF, Cronican AA, Lefterov I, Koldamova R. Comment on "ApoE-directed therapeutics rapidly clear β-amyloid and reverse deficits in AD mouse models". Science 2013; 340:924-c. [PMID: 23704552 DOI: 10.1126/science.1235809] [Citation(s) in RCA: 131] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Cramer et al. (Reports, 23 March 2012, p. 1503; published online 9 February 2012) demonstrated in a mouse model for Alzheimer's disease (AD) that treatment of APP/PS1ΔE9 mice with bexarotene decreased Aβ pathology and ameliorated memory deficits. We confirm the reversal of memory deficits in APP/PS1ΔE9 mice expressing human APOE3 or APOE4 to the levels of their nontransgenic controls and the significant decrease of interstitial fluid Aβ, but not the effects on amyloid deposition.
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Affiliation(s)
- Nicholas F Fitz
- Department of Environmental and Occupational Health, University of Pittsburgh, 100 Technology Drive, Pittsburgh, PA 15219, USA
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Cronican AA, Fitz NF, Carter A, Saleem M, Shiva S, Barchowsky A, Koldamova R, Schug J, Lefterov I. Genome-wide alteration of histone H3K9 acetylation pattern in mouse offspring prenatally exposed to arsenic. PLoS One 2013; 8:e53478. [PMID: 23405071 PMCID: PMC3566160 DOI: 10.1371/journal.pone.0053478] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Accepted: 11/29/2012] [Indexed: 01/19/2023] Open
Abstract
Chronic exposure to arsenic in drinking water, especially in utero or perinatal exposure, can initiate neurological and cognitive dysfunction, as well as memory impairment. Several epidemiological studies have demonstrated cognitive and learning deficits in children with early exposure to low to moderate levels of arsenic, but pathogenic mechanisms or etiology for these deficits are poorly understood. Since in vivo studies show a role for histone acetylation in cognitive performance and memory formation, we examined if prenatal exposure to arsenic causes changes in the epigenomic landscape. We exposed C57Bl6/J mice to 100 μg/L arsenic in the drinking water starting 1 week before conception till birth and applied chromatin immunoprecipitation followed by high-throughput massive parallel sequencing (ChIP-seq) to evaluate H3K9 acetylation pattern in the offspring of exposed and control mice. Arsenic exposure during embryonic life caused global hypo-acetylation at H3K9 and changes in functional annotation with highly significant representation of Krüppel associated box (KRAB) transcription factors in brain samples from exposed pups. We also found that arsenic exposure of adult mice impaired spatial and episodic memory, as well as fear conditioning performance. This is the first study to demonstrate: a) genome wide changes in H3K9 acetylation pattern in an offspring prenatally exposed to arsenic, and b) a connection between moderate arsenic exposure and cognitive impairment in adult mice. The results also emphasize the applicability of Next Generation Sequencing methodology in studies aiming to reveal the role of environmental factors, other than dietary restriction, in developmental reprogramming through histone modifications during embryonic development.
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Affiliation(s)
- Andrea A. Cronican
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Nicholas F. Fitz
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Alexis Carter
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Muzamil Saleem
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Sruti Shiva
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Aaron Barchowsky
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Radosveta Koldamova
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Jonathan Schug
- Functional Genomics and Next-Generation Sequencing Core, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail: (JS); (IL)
| | - Iliya Lefterov
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- * E-mail: (JS); (IL)
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Lefterov I, Koldamova R, Fitz N. P4‐239: ABCA1 deficiency differentially affects the amyloid phenotype of APOE‐ε3‐ and APOE‐ε4‐targeted replacement mice. Alzheimers Dement 2012. [DOI: 10.1016/j.jalz.2012.05.2103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Iliya Lefterov
- University of PittsburghPittsburghPennsylvaniaUnited States
| | | | - Nicholas Fitz
- University of PittsburghPittsburghPennsylvaniaUnited States
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Fitz N, Chronican A, Kodali R, Wetzel R, Lefterov I, Koldamova R. P4‐013: ABCA1 deficiency decreases Amyloid clearance and increases Amyloid aggregation in Alzheimer's disease mouse model. Alzheimers Dement 2011. [DOI: 10.1016/j.jalz.2011.05.2032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Nicholas Fitz
- University of PittsburghPittsburghPennsylvaniaUnited States
| | | | | | - Ronald Wetzel
- University of PittsburghPittsburghPennsylvaniaUnited States
| | - Iliya Lefterov
- University of PittsburghPittsburghPennsylvaniaUnited States
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Lefterov I, Lefterova M, Chronican A, Fitz N, Schug J, Koldamova R. P4‐016: Egr1 binding and histone modification mapping in brain of mouse model of AD. Alzheimers Dement 2011. [DOI: 10.1016/j.jalz.2011.05.2034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Iliya Lefterov
- University of Pittsburgh/GSPHPittsburghPennsylvaniaUnited States
| | | | | | - Nicholas Fitz
- University of PittsburghPittsburghPennsylvaniaUnited States
| | - Jonathan Schug
- University of PennsylvaniaPhiladelphiaPennsylvaniaUnited States
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Lefterov I, Fitz NF, Cronican AA, Fogg A, Lefterov P, Kodali R, Wetzel R, Koldamova R. Apolipoprotein A-I deficiency increases cerebral amyloid angiopathy and cognitive deficits in APP/PS1DeltaE9 mice. J Biol Chem 2010; 285:36945-57. [PMID: 20739292 PMCID: PMC2978623 DOI: 10.1074/jbc.m110.127738] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2010] [Revised: 08/20/2010] [Indexed: 11/06/2022] Open
Abstract
A hallmark of Alzheimer disease (AD) is the deposition of amyloid β (Aβ) in brain parenchyma and cerebral blood vessels, accompanied by cognitive decline. Previously, we showed that human apolipoprotein A-I (apoA-I) decreases Aβ(40) aggregation and toxicity. Here we demonstrate that apoA-I in lipidated or non-lipidated form prevents the formation of high molecular weight aggregates of Aβ(42) and decreases Aβ(42) toxicity in primary brain cells. To determine the effects of apoA-I on AD phenotype in vivo, we crossed APP/PS1ΔE9 to apoA-I(KO) mice. Using a Morris water maze, we demonstrate that the deletion of mouse Apoa-I exacerbates memory deficits in APP/PS1ΔE9 mice. Further characterization of APP/PS1ΔE9/apoA-I(KO) mice showed that apoA-I deficiency did not affect amyloid precursor protein processing, soluble Aβ oligomer levels, Aβ plaque load, or levels of insoluble Aβ in brain parenchyma. To examine the effect of Apoa-I deletion on cerebral amyloid angiopathy, we measured insoluble Aβ isolated from cerebral blood vessels. Our data show that in APP/PS1ΔE9/apoA-I(KO) mice, insoluble Aβ(40) is increased more than 10-fold, and Aβ(42) is increased 1.5-fold. The increased levels of deposited amyloid in the vessels of cortices and hippocampi of APP/PS1ΔE9/apoA-I(KO) mice, measured by X-34 staining, confirmed the results. Finally, we demonstrate that lipidated and non-lipidated apoA-I significantly decreased Aβ toxicity against brain vascular smooth muscle cells. We conclude that lack of apoA-I aggravates the memory deficits in APP/PS1ΔE9 mice in parallel to significantly increased cerebral amyloid angiopathy.
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MESH Headings
- Amyloid beta-Protein Precursor/physiology
- Animals
- Apolipoprotein A-I/physiology
- Behavior, Animal
- Blotting, Western
- Brain/metabolism
- Brain/pathology
- Cells, Cultured
- Cerebral Amyloid Angiopathy/etiology
- Cerebral Amyloid Angiopathy/pathology
- Cholesterol/metabolism
- Embryo, Mammalian/cytology
- Embryo, Mammalian/metabolism
- Enzyme-Linked Immunosorbent Assay
- Humans
- Immunoenzyme Techniques
- Maze Learning
- Memory Disorders/etiology
- Memory Disorders/pathology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Transgenic
- Mutation/genetics
- Myocytes, Smooth Muscle/metabolism
- Presenilin-1/physiology
- RNA, Messenger/genetics
- Rats
- Rats, Sprague-Dawley
- Reverse Transcriptase Polymerase Chain Reaction
- Sequence Deletion
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Affiliation(s)
- Iliya Lefterov
- From the Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, Pennsylvania 15219 and
| | - Nicholas F. Fitz
- From the Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, Pennsylvania 15219 and
| | - Andrea A. Cronican
- From the Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, Pennsylvania 15219 and
| | - Allison Fogg
- From the Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, Pennsylvania 15219 and
| | - Preslav Lefterov
- From the Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, Pennsylvania 15219 and
| | - Ravindra Kodali
- the Department of Structural Biology and
- Pittsburgh Institute for Neurodegenerative Disorders, University of Pittsburgh, Pittsburgh, Pennsylvania 15260
| | - Ronald Wetzel
- the Department of Structural Biology and
- Pittsburgh Institute for Neurodegenerative Disorders, University of Pittsburgh, Pittsburgh, Pennsylvania 15260
| | - Radosveta Koldamova
- From the Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, Pennsylvania 15219 and
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Koldamova R, Fitz NF, Lefterov I. The role of ATP-binding cassette transporter A1 in Alzheimer's disease and neurodegeneration. Biochim Biophys Acta Mol Cell Biol Lipids 2010; 1801:824-30. [PMID: 20188211 DOI: 10.1016/j.bbalip.2010.02.010] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2010] [Revised: 02/12/2010] [Accepted: 02/15/2010] [Indexed: 01/03/2023]
Abstract
ATP-binding cassette transporter A1 - ABCA1, is the most extensively studied transporter in human pathology. ABCA1 became a primary subject of research in many academic and pharmaceutical laboratories immediately after the discovery that mutations at the gene locus cause severe familial High Density Lipoprotein (HDL) deficiency and, in the homozygous form - Tangier disease. The protein is the major regulator of intracellular cholesterol efflux which is the initial and essential step in the biogenesis and formation of nascent HDL particles. The transcriptional regulation of ABCA1 by nuclear Liver X Receptors (LXR) provided a starting point for drug discovery and development of synthetic LXR ligands/ABCA1 activators for treatment of arteriosclerosis. A series of reports that revealed the role of ABCA1 in Abeta deposition and clearance, as well as the possibility for association of some ABCA1 genetic variants with risk for Alzheimer's disease (AD) brought a new dimension to ABCA1 research. The LXR-ABCA1-APOE regulatory axis is now considered a promising therapeutic target in AD, which includes the only proven risk factor for AD - APOE, at two distinct levels - transcriptional regulation by LXR, and ABCA1 controlled lipidation which can influence Abeta aggregation and amyloid clearance. This review will summarize the results of research on ABCA1, particularly related to AD and neurodegeneration.
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Affiliation(s)
- Radosveta Koldamova
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA.
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Suresh S, Demirci FY, Lefterov I, Kammerer CM, Ramsey-Goldman R, Manzi S, Kamboh MI. Functional and genetic characterization of the promoter region of apolipoprotein H (beta2-glycoprotein I). FEBS J 2010; 277:951-63. [PMID: 20089041 DOI: 10.1111/j.1742-4658.2009.07538.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
This study characterized the human apolipoprotein H [APOH; beta(2)-glycoprotein I (beta(2)GPI)] promoter and its variants by in vitro functional experiments and investigated their relationship with human plasma beta(2)GPI levels. We examined the individual effects of 12 APOH promoter single nucleotide polymorphisms in the 5' flanking region of APOH (approximately 1.4 kb) on luciferase activity in COS-1 cells and HepG2 cells and their impact on plasma beta(2)GPI levels in 799 American White people, the DNA binding properties of the APOH promoter using an electrophoretic mobility shift assay in HepG2 cells, the effects of serial deletion analysis of the APOH 5' flanking region in COS-1 and HepG2 cells and cross-species conservation of the APOH promoter sequence. The variant alleles of three single nucleotide polymorphisms (-1219G>A, -643T>C and -32C>A) showed significantly lower luciferase expression (51, 40 and 37%, respectively) as compared with the wild-type allele. The electrophoretic mobility shift assay demonstrated that these three variants specifically bind with protein(s) from HepG2 cell nuclear extracts. Three-site haplotype analysis (-1219G>A, -643T>C and -32C>A) revealed one haplotype carrying -32A (allele frequency = 0.075) to be significantly associated with decreased plasma beta(2)GPI levels (P < 0.001). Deletion analysis localized the core APOH promoter to approximately 160 bp upstream of ATG codon with the presence of critical cis-acting elements between -166 and -65. Cross-species conservation analysis of the APOH promoters of seven species indicated that basic promoter elements are highly conserved across species. In conclusion, we have characterized the functional promoter of APOH and identified functional variants that affect the transcriptional activity of the APOH promoter.
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Affiliation(s)
- Sangita Suresh
- Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
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Cronican AA, Fitz NF, Pham T, Fogg A, Kifer B, Koldamova R, Lefterov I. Proton pump inhibitor lansoprazole is a nuclear liver X receptor agonist. Biochem Pharmacol 2010; 79:1310-6. [PMID: 20060385 DOI: 10.1016/j.bcp.2009.12.018] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2009] [Revised: 12/12/2009] [Accepted: 12/16/2009] [Indexed: 12/22/2022]
Abstract
The liver X receptors (LXRalpha and LXRbeta) are transcription factors that control the expression of genes primarily involved in cholesterol metabolism. In the brain, in addition to normal neuronal function, cholesterol metabolism is important for APP proteolytic cleavage, secretase activities, Abeta aggregation and clearance. Particularly significant in this respect is LXR mediated transcriptional control of APOE, which is the only proven risk factor for late onset Alzheimer's disease. Using a transactivation reporter assay for screening pharmacologically active compounds and off patent drugs we identified the proton pump inhibitor Lansoprazole as an LXR agonist. In secondary screens and counter-screening assays, it was confirmed that Lansoprazole directly activates LXR, increases the expression of LXR target genes in brain-derived human cell lines, and increases Abca1 and Apo-E protein levels in primary astrocytes derived from wild type but not LXRalpha/beta double knockout mice. Other PPIs activate LXR as well, but the efficiency of activation depends on their structural similarities to Lansoprazole. The identification of a widely used drug with LXR agonist-like activity opens the possibility for systematic preclinical testing in at least two diseases--Alzheimer's disease and atherosclerosis.
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Affiliation(s)
- Andrea A Cronican
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA
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Koldamova R, Fitz N, Cronican A, Fogg A, Eggelstone S, Tulloch T, Carter A, Lefterov I. P2‐160: Critical role of Abca1 in maintaining functional apoE and apoA‐I and their impact on A‐beta aggregation and clearance from brain. Alzheimers Dement 2009. [DOI: 10.1016/j.jalz.2009.04.472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Lefterov I. S5‐02‐03: Role of Abca1, ApoE and ApoA‐I in Alzheimer's disease pathogenesis: Lessons from complex animal models. Alzheimers Dement 2009. [DOI: 10.1016/j.jalz.2009.05.579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Lefterov I, Bookout A, Wang Z, Staufenbiel M, Mangelsdorf D, Koldamova R. Expression profiling in APP23 mouse brain: inhibition of Abeta amyloidosis and inflammation in response to LXR agonist treatment. Mol Neurodegener 2007; 2:20. [PMID: 17953774 PMCID: PMC2214725 DOI: 10.1186/1750-1326-2-20] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2007] [Accepted: 10/22/2007] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND Recent studies demonstrate that in addition to its modulatory effect on APP processing, in vivo application of Liver X Receptor agonist T0901317 (T0) to APP transgenic and non-transgenic mice decreases the level of Abeta42. Moreover, in young Tg2576 mice T0 completely reversed contextual memory deficits. Compared to other tissues, the regulatory functions of LXRs in brain remain largely unexplored and our knowledge so far is limited to the cholesterol transporters and apoE. In this study we applied T0 to APP23 mice for various times and examined gene and protein expression. We also performed a series of experiments with primary brain cells derived from wild type and LXR knockout mice subjected to various LXR agonist treatments and inflammatory stimuli. RESULTS We demonstrate an upregulation of genes related to lipid metabolism/transport, metabolism of xenobiotics and detoxification. Downregulated genes are involved in immune response and inflammation, cell death and apoptosis. Additional treatment experiments demonstrated an increase of soluble apolipoproteins E and A-I and a decrease of insoluble Abeta. In primary LXRwt but not in LXRalpha-/-beta-/- microglia and astrocytes LXR agonists suppressed the inflammatory response induced by LPS or fibrillar Abeta. CONCLUSION The results show that LXR agonists could alleviate AD pathology by acting on amyloid deposition and brain inflammation. An increased understanding of the LXR controlled regulation of Abeta aggregation and clearance systems will lead to the development of more specific and powerful agonists targeting LXR for the treatment of AD.
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Affiliation(s)
- Iliya Lefterov
- Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA 15219, USA
| | - Angie Bookout
- Department of Pharmacology, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Zhu Wang
- Department of Pharmacology, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Matthias Staufenbiel
- Department of Nervous System, Novartis Institutes of BioMedical Research, CH-4002 Basel, Switzerland
| | - David Mangelsdorf
- Department of Pharmacology, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Radosveta Koldamova
- Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA 15219, USA
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Abstract
Studies, ranging from epidemiological to in vitro and in vivo experimental settings have provided convincing evidence that different aspects of brain lipid metabolism may influence Alzheimer disease pathogenesis through effects on beta-amyloid deposition and clearance. It has been demonstrated that transcription factors called nuclear liver X receptors (LXR) and their responsive genes provide natural regulatory mechanisms and influence AD pathogenesis through their modulatory effects on intracellular cholesterol content, cholesterol efflux and possibly via anti-inflammatory mechanisms. Here, we provide a brief summary of the approaches undertaken by different groups that lead to the nowadays working model of LXR and ABCA1 regulatory role in brain amyloidogenesis and amyloid clearance and we highlight the therapeutic potential of LXR agonists.
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Affiliation(s)
- Radosveta Koldamova
- Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA 15219, USA.
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Abstract
ABCA1 (ATP-binding cassette transporter A1) is a major regulator of cholesterol efflux and high density lipoprotein (HDL) metabolism. Mutations in human ABCA1 cause severe HDL deficiencies characterized by the virtual absence of apoA-I and HDL and prevalent atherosclerosis. Recently, it has been reported that the lack of ABCA1 causes a significant reduction of apoE protein level in the brain of ABCA1 knock-out (ABCA1-/-) mice. ApoE isoforms strongly affect Alzheimer disease (AD) pathology and risk. To determine further the effect of ABCA1 on amyloid deposition, we used APP23 transgenic mice in which the human familial Swedish AD mutant is expressed only in neurons. We demonstrated that the targeted disruption of ABCA1 increases amyloid deposition in APP23 mice, and the effect is manifested by an increased level of Abeta immunoreactivity, as well as thioflavine S-positive plaques in brain parenchyma. We found that the lack of ABCA1 also considerably increased the level of cerebral amyloid angiopathy and exacerbated cerebral amyloid angiopathy-related microhemorrhage in APP23/ABCA1-/- mice. Remarkably, the elevation in parenchymal and vascular amyloid in APP23/ABCA1-/- mice was accompanied by a dramatic decrease in the level of soluble brain apoE, although insoluble apoE was not changed. The elevation of insoluble Abeta fraction in old APP23/ABCA1-/- mice, accompanied by a lack of changes in APP processing and soluble beta-amyloid in young APP23/ABCA1-/- animals, supports the conclusion that the ABCA1 deficiency increases amyloid deposition. These results suggest that ABCA1 plays a role in the pathogenesis of parenchymal and cerebrovascular amyloid pathology and thus may be considered a therapeutic target in AD.
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Affiliation(s)
- Radosveta Koldamova
- Department of Pharmacology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA.
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Klunk WE, Lopresti BJ, Debnath ML, Huang GF, Shao L, Lefterov I, Koldamova R, Ikonomovic MD, DeKosky ST, Mathis CA. [P‐096]: Low binding of the amyloid PET tracer, PIB, to transgenic PS1/APP mouse brain compared to human AD brain explained by Bmax. Alzheimers Dement 2005. [DOI: 10.1016/j.jalz.2005.06.170] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
| | | | | | | | - Li Shao
- University of PittsburghPittsburghPAUSA
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Klunk WE, Lopresti BJ, Debnath ML, Holt DP, Wang Y, Huang GF, Shao L, Lefterov I, Koldamova R, Ikonomovic M, DeKosky ST, Mathis CA. P2-031 Amyloid deposits in transgenic PS1/APP mice do not bind the amyloid pet tracer, PIB, in the same manner as human brain amyloid. Neurobiol Aging 2004. [DOI: 10.1016/s0197-4580(04)80779-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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