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Azmi MB, Sehgal SA, Asif U, Musani S, Abedin MFE, Suri A, Ahmed SDH, Qureshi SA. Genetic insights into obesity: in silico identification of pathogenic SNPs in MBOAT4 gene and their structural molecular dynamics consequences. J Biomol Struct Dyn 2023:1-17. [PMID: 37921712 DOI: 10.1080/07391102.2023.2274970] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Accepted: 10/18/2023] [Indexed: 11/04/2023]
Abstract
Membrane Bound O-Acyltransferase Domain-Containing 4 (MBOAT4) protein catalyzes ghrelin acylation, leading to prominent ghrelin activity, hence characterizing its role as an anti-obesity target. We extracted 625 exonic SNPs from the ENSEMBL database and one phenotype-based missense mutation associated with obesity (A46T) from the HGMD (Human Gene Mutation Database). These were differentiated on deleterious missense SNPs of the MBOAT4 gene through MAF (minor allele frequency: <0.01) cut-off criteria in relation to some bioinformatics-based supervised machine learning tools. We found 8 rare-coding and harmful missense SNPs. The consensus classifier (PredictSNP) tool predicted that the SNP (G57S, C: rs561065025) was the most pathogenic. Several trained in silico algorithms have predicted decreased protein stability [ΔΔG (kcal/mol)] function in the presence of these rare-coding pathogenic mutations in the MBOAT4 gene. Then, a stereochemical quality check (i.e. validation and assessment) of the 3D model was performed, followed by a blind cavity docking approach, used to search for druggable cavities and molecular interactions with citrus flavonoids of the Rutaceae family, ranked with energetic estimations. Significant interactions with Phloretin 3',5'-Di-C-Glucoside were also observed at R304, W306, N307, A311, L314 and H338 with (iGEMDOCK: -95.82 kcal/mol and AutoDock: -7.80 kcal/mol). The RMSD values and other variables of MD simulation analyses on this protein further validated its significant interactions with the above flavonoids. The MBOAT4 gene and its molecular interactions could serve as an interventional future anti-obesity target. The current study's findings will benefit future prospects for large population-based studies and drug development, particularly for generating personalized medicine.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Muhammad Bilal Azmi
- Department of Biochemistry, Dow Medical College, Dow University of Health Sciences, Karachi, Pakistan
| | - Sheikh Arslan Sehgal
- Department of Bioinformatics, Institute of Biochemistry, Biotechnology and Bioinformatics, The Islamia University of Bahawalpur, Bahawalpur, Pakistan
| | - Uzma Asif
- Department of Biochemistry, Medicine Program, Batterjee Medical College, Jeddah, Saudi Arabia
| | - Sarah Musani
- Dow Medical College, Dow University of Health Sciences, Karachi, Pakistan
| | | | - Azeema Suri
- Dow Medical College, Dow University of Health Sciences, Karachi, Pakistan
| | - Syed Danish Haseen Ahmed
- Department of Biochemistry, Dow Medical College, Dow University of Health Sciences, Karachi, Pakistan
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Abstract
Alzheimer's disease (AD) is the most common type of dementia in seniors. Current efforts to understand the etiopathogenesis of this neurodegenerative disorder have brought forth questions about systemic factors in the development of AD. Ghrelin is a brain-gut peptide that is activated by ghrelin O-acyltransferase (GOAT) and signals via its receptor, growth hormone secretagogue receptor (GHSR). With increasing recognition of the neurotropic effects of ghrelin, the role of ghrelin system deregulation in the development of AD has been accentuated in recent years. In this review, we summarized recent research progress regarding the mechanisms of ghrelin signaling dysregulation and its contribution to AD brain pathology. In addition, we also discussed the therapeutic potential of strategies targeting ghrelin signaling for the treatment of this neurological disease.
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Yu M, Zhu QQ, Niu ML, Li N, Ren BQ, Yu TB, Zhou ZS, Guo JD, Zhou Y. Ghrelin infusion into the basolateral amygdala suppresses CTA memory formation in rats via the PI3K/Akt/mTOR and PLC/PKC signaling pathways. Acta Pharmacol Sin 2022; 43:2242-2252. [PMID: 35169271 PMCID: PMC9433413 DOI: 10.1038/s41401-022-00859-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 01/03/2022] [Indexed: 12/11/2022] Open
Abstract
Ghrelin is a circulating orexigenic hormone that promotes feeding behavior and regulates metabolism in humans and rodents. We previously reported that local infusion of ghrelin into the basolateral amygdala (BLA) blocked memory acquisition for conditioned taste aversion (CTA) by activating growth hormone secretagogue receptor 1a. In this study, we further explored the underlying mechanism and signaling pathways mediating ghrelin modulation of CTA memory in rats. Pharmacological agents targeting distinct signaling pathways were infused into the BLA during conditioning. We showed that preadministration of the PI3K inhibitor LY294002 abolished the repressive effect of ghrelin on CTA memory. Moreover, LY294002 pretreatment prevented ghrelin from inhibiting Arc and zif268 mRNA expression in the BLA triggered by CTA memory retrieval. Preadministration of rapamycin eliminated the repressive effect of ghrelin, while Gsk3 inhibitors failed to mimic ghrelin's effect. In addition, PLC and PKC inhibitors microinfused in the BLA blocked ghrelin's repression of CTA acquisition. These results demonstrate that ghrelin signaling in the BLA shapes CTA memory via the PI3K/Akt/mTOR and PLC/PKC pathways. We conducted in vivo multichannel recordings from mouse BLA neurons and found that microinjection of ghrelin (20 µM) suppressed intrinsic excitability. By means of whole-cell recordings from rat brain slices, we showed that bath application of ghrelin (200 nM) had no effect on basal synaptic transmission or synaptic plasticity of BLA pyramidal neurons. Together, this study reveals the mechanism underlying ghrelin-induced interference with CTA memory acquisition in rats, i.e., suppression of intrinsic excitability of BLA principal neurons via the PI3K/Akt/mTOR and PLC/PKC pathways.
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Affiliation(s)
- Ming Yu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Qingdao University, Qingdao, 266071, China
| | - Qian-Qian Zhu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Qingdao University, Qingdao, 266071, China
| | - Ming-Lu Niu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Qingdao University, Qingdao, 266071, China
| | - Nan Li
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Qingdao University, Qingdao, 266071, China
| | - Bai-Qing Ren
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Qingdao University, Qingdao, 266071, China
| | - Teng-Bo Yu
- Department of Sports Medicine, Affiliated Hospital of Qingdao University, Qingdao, 266000, China.
| | - Zhi-Shang Zhou
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao, 266071, China
| | - Ji-Dong Guo
- Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Yu Zhou
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Qingdao University, Qingdao, 266071, China.
- Department of rehabilitation medicine, Affiliated Hospital of Qingdao University, Qingdao, 266000, China.
- Institute of Brain Sciences and Related Disorders, Qingdao University, Qingdao, 266071, China.
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Li N, Xiao K, Mi X, Li N, Guo L, Wang X, Sun Y, Li GD, Zhou Y. Ghrelin signaling in dCA1 suppresses neuronal excitability and impairs memory acquisition via PI3K/Akt/GSK-3β cascades. Neuropharmacology 2022; 203:108871. [PMID: 34742928 DOI: 10.1016/j.neuropharm.2021.108871] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [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: 06/09/2021] [Revised: 11/01/2021] [Accepted: 11/01/2021] [Indexed: 12/22/2022]
Abstract
Ghrelin is a circulating peptide hormone that promotes feeding and regulates metabolism in humans and rodents. The action of ghrelin is mediated by the growth hormone secretagogue receptor type 1a (GHSR-1a) that is widely distributed in the brain, including the hippocampus. Studies have demonstrated the critical role of hippocampal ghrelin/GHS-R1a signaling in synaptic physiology and memory. However, those findings are controversial, and the mechanism underlying ghrelin modulation of learning and memory is uncertain. Here, we report that micro-infusion of ghrelin in the CA1 region of the dorsal hippocampus during training specifically impairs memory acquisition. The activation of GHS-R1a and the subsequent PI3K/Akt/GSK3β signaling cascades are involved in this process. Moreover, we report that bath application of ghrelin suppresses the intrinsic excitability of dCA1 pyramidal neurons through activating GHS-R1a, and PI3K inhibitor LY294002 blocks ghrelin's effect. However, LY294002 fails to rescue ghrelin-induced LTP impairment. Our findings support an adverse effect of ghrelin-dependent activation of GHS-R1a on memory acquisition, and suggest that PI3K/Akt/GSK3β signaling-dependent repression of neuronal intrinsic excitability is an important novel mechanism underlying memory inhibition of ghrelin in the hippocampus.
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Affiliation(s)
- Nan Li
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Qingdao University, Qingdao, Shandong, 266071, China
| | - Kewei Xiao
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Qingdao University, Qingdao, Shandong, 266071, China
| | - Xue Mi
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Qingdao University, Qingdao, Shandong, 266071, China
| | - Na Li
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Qingdao University, Qingdao, Shandong, 266071, China
| | - Li Guo
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Qingdao University, Qingdao, Shandong, 266071, China
| | - Xiaorong Wang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Qingdao University, Qingdao, Shandong, 266071, China
| | - Yuxiang Sun
- Department of Nutrition, Texas A&M University, College Station, TX, 77843, United States
| | - Guo-Dong Li
- Department of Surgery, Valley Presbyterian Hospital, Van Nuys, CA, 91405, United States
| | - Yu Zhou
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Qingdao University, Qingdao, Shandong, 266071, China; Institute of Brain Sciences and Related Disorders, Qingdao University, Qingdao, Shandong, 266071, China; Department of Rehabilitation Medicine, Affiliated Hospital of Qingdao University, Qingdao, Shangdong, 266000, China.
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Kumon H, Yoshino Y, Funahashi Y, Mori H, Ueno M, Ozaki Y, Yamazaki K, Ochi S, Mori T, Iga JI, Nagai M, Nomoto M, Ueno SI. PICALM mRNA Expression in the Blood of Patients with Neurodegenerative Diseases and Geriatric Depression. J Alzheimers Dis 2021; 79:1055-1062. [PMID: 33386803 PMCID: PMC7990403 DOI: 10.3233/jad-201046] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [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: 12/24/2022]
Abstract
BACKGROUND Phosphatidylinositol-binding clathrin assembly protein (PICALM) is a validated genetic risk factor for late-onset Alzheimer's disease (AD) and is associated with other neurodegenerative diseases. However, PICALM expression in the blood of neurodegenerative diseases remains elusive. OBJECTIVE This study aimed to assess the usefulness of PICALM expression levels in the blood of patients with AD, Parkinson's disease (PD), dementia with Lewy bodies (DLB), and geriatric major depressive disorder (MDD) as a diagnostic biomarker. METHODS In total, 45, 20, 21, and 19 patients with AD, PD, DLB, and geriatric MDD, respectively, and 54 healthy controls (HCs) were enrolled in the study. Expression data from Gene Expression Omnibus database (GSE97760), (GSE133347) and (GSE98793), (GSE48350), and (GSE144459) were used to validate the ability of biomarkers in the blood of patients with AD, PD, geriatric MDD, and a postmortem human AD brain and animal model of AD (3xTg-AD mouse), respectively. RESULTS PICALM mRNA expression in human blood was significantly increased in patients with AD compared with that in HCs. PICALM mRNA expression and age were negatively correlated only in patients with AD. PICALM mRNA expression in human blood was significantly lower in patients with PD than in HCs. No changes in PICALM mRNA expression were found in patients with DLB and geriatric MDD. CONCLUSION PICALM mRNA expression in blood was higher in patients with AD, but lower in patients with PD, which suggests that PICALM mRNA expression in human blood may be a useful biomarker for differentiating neurodegenerative diseases and geriatric MDD.
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Affiliation(s)
- Hiroshi Kumon
- Department of Neuropsychiatry, Molecules and Function, Graduate School of Medicine, Ehime University, Toon, Ehime, Japan
| | - Yuta Yoshino
- Department of Neuropsychiatry, Molecules and Function, Graduate School of Medicine, Ehime University, Toon, Ehime, Japan
| | - Yu Funahashi
- Department of Neuropsychiatry, Molecules and Function, Graduate School of Medicine, Ehime University, Toon, Ehime, Japan
| | - Hiroaki Mori
- Department of Neuropsychiatry, Molecules and Function, Graduate School of Medicine, Ehime University, Toon, Ehime, Japan
| | - Mariko Ueno
- Department of Neuropsychiatry, Molecules and Function, Graduate School of Medicine, Ehime University, Toon, Ehime, Japan
| | - Yuki Ozaki
- Department of Neuropsychiatry, Molecules and Function, Graduate School of Medicine, Ehime University, Toon, Ehime, Japan
| | - Kiyohiro Yamazaki
- Department of Neuropsychiatry, Molecules and Function, Graduate School of Medicine, Ehime University, Toon, Ehime, Japan
| | - Shinichiro Ochi
- Department of Neuropsychiatry, Molecules and Function, Graduate School of Medicine, Ehime University, Toon, Ehime, Japan
| | - Takaaki Mori
- Department of Neuropsychiatry, Molecules and Function, Graduate School of Medicine, Ehime University, Toon, Ehime, Japan
| | - Jun-Ichi Iga
- Department of Neuropsychiatry, Molecules and Function, Graduate School of Medicine, Ehime University, Toon, Ehime, Japan
| | - Masahiro Nagai
- Department of Neurology and Clinical Pharmacology, Graduate School of Medicine, Ehime University, Toon, Ehime, Japan
| | - Masahiro Nomoto
- Department of Neurology and Clinical Pharmacology, Graduate School of Medicine, Ehime University, Toon, Ehime, Japan
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Xing S, Li Q, Xiong B, Chen Y, Feng F, Liu W, Sun H. Structure and therapeutic uses of butyrylcholinesterase: Application in detoxification, Alzheimer's disease, and fat metabolism. Med Res Rev 2020; 41:858-901. [PMID: 33103262 DOI: 10.1002/med.21745] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 09/21/2020] [Accepted: 10/12/2020] [Indexed: 02/06/2023]
Abstract
Structural information of butyrylcholinesterase (BChE) and its variants associated with several diseases are discussed here. Pure human BChE has been proved safe and effective in treating organophosphorus (OPs) poisoning and has completed Phase 1 and 2 pharmacokinetic (PK) and safety studies. The introduction of specific mutations into native BChE to endow it a self-reactivating property has gained much progress in producing effective OPs hydrolases. The hydrolysis ability of native BChE on cocaine has been confirmed but was blocked to clinical application due to poor PK properties. Several BChE mutants with elevated cocaine hydrolysis activity were published, some of which have shown safety and efficiency in treating cocaine addiction of human. The increased level of BChE in progressed Alzheimer's disease patients made it a promising target to elevate acetylcholine level and attenuate cognitive status. A variety of selective BChE inhibitors with high inhibitory activity published in recent years are reviewed here. BChE could influence the weight and insulin secretion and resistance of BChE knockout (KO) mice through hydrolyzing ghrelin. The BChE-ghrelin pathway could also regulate aggressive behaviors of BChE-KO mice.
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Affiliation(s)
- Shuaishuai Xing
- School of Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Qi Li
- School of Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Baichen Xiong
- School of Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Yao Chen
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, China
| | - Feng Feng
- Department of Natural Medicinal Chemistry, China Pharmaceutical University, Nanjing, China.,Institute of Food and Pharmaceuticals Research, Jiangsu Food and Pharmaceuticals Science College, Nanjing, China
| | - Wenyuan Liu
- School of Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Haopeng Sun
- School of Pharmacy, China Pharmaceutical University, Nanjing, China
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Kim S, Nam Y, Shin SJ, Park YH, Jeon SG, Kim JI, Kim MJ, Moon M. The Potential Roles of Ghrelin in Metabolic Syndrome and Secondary Symptoms of Alzheimer's Disease. Front Neurosci 2020; 14:583097. [PMID: 33071750 PMCID: PMC7543232 DOI: 10.3389/fnins.2020.583097] [Citation(s) in RCA: 10] [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] [Received: 07/15/2020] [Accepted: 08/26/2020] [Indexed: 12/12/2022] Open
Abstract
Although the major causative factors of Alzheimer's disease (AD) are the accumulation of amyloid β and hyperphosphorylated tau, AD can also be caused by metabolic dysfunction. The major clinical symptom of AD is cognitive dysfunction. However, AD is also accompanied by various secondary symptoms such as depression, sleep-wake disturbances, and abnormal eating behaviors. Interestingly, the orexigenic hormone ghrelin has been suggested to have beneficial effects on AD-related metabolic syndrome and secondary symptoms. Ghrelin improves lipid distribution and alters insulin sensitivity, effects that are hypothesized to delay the progression of AD. Furthermore, ghrelin can relieve depression by enhancing the secretion of hormones such as serotonin, noradrenaline, and orexin. Moreover, ghrelin can upregulate the expression of neurotrophic factors such as brain-derived neurotrophic factor and modulate the release of proinflammatory cytokines such as tumor necrosis factor α and interleukin 1β. Ghrelin alleviates sleep-wake disturbances by increasing the levels of melatonin, melanin-concentrating hormone. Ghrelin reduces the risk of abnormal eating behaviors by increasing neuropeptide Y and γ-aminobutyric acid. In addition, ghrelin increases food intake by inhibiting fatty acid biosynthesis. However, despite the numerous studies on the role of ghrelin in the AD-related pathology and metabolic disorders, there are only a few studies that investigate the effects of ghrelin on secondary symptoms associated with AD. In this mini review, our purpose is to provide the insights of future study by organizing the previous studies for the role of ghrelin in AD-related pathology and metabolic disorders.
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Affiliation(s)
- Sujin Kim
- Department of Biochemistry, College of Medicine, Konyang University, Daejeon, South Korea
| | - Yunkwon Nam
- Department of Biochemistry, College of Medicine, Konyang University, Daejeon, South Korea
| | - Soo Jung Shin
- Department of Biochemistry, College of Medicine, Konyang University, Daejeon, South Korea
| | - Yong Ho Park
- Department of Biochemistry, College of Medicine, Konyang University, Daejeon, South Korea
| | - Seong Gak Jeon
- Department of Biochemistry, College of Medicine, Konyang University, Daejeon, South Korea.,Department of Neural Development and Disease, Korea Brain Research Institute (KBRI), Daegu, South Korea
| | - Jin-Il Kim
- Department of Nursing, College of Nursing, Jeju National University, Jeju-si, South Korea
| | - Min-Jeong Kim
- Department of Biochemistry, College of Medicine, Konyang University, Daejeon, South Korea
| | - Minho Moon
- Department of Biochemistry, College of Medicine, Konyang University, Daejeon, South Korea
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Ochi S, Iga JI, Funahashi Y, Yoshino Y, Yamazaki K, Kumon H, Mori H, Ozaki Y, Mori T, Ueno SI. Identifying Blood Transcriptome Biomarkers of Alzheimer's Disease Using Transgenic Mice. Mol Neurobiol 2020; 57:4941-4951. [PMID: 32816243 PMCID: PMC7541363 DOI: 10.1007/s12035-020-02058-2] [Citation(s) in RCA: 10] [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] [Received: 05/04/2020] [Accepted: 08/07/2020] [Indexed: 12/23/2022]
Abstract
The testing of pathological biomarkers of Alzheimer's disease (AD), such as amyloid beta and tau, is time-consuming, expensive, and invasive. Here, we used 3xTg-AD mice to identify and validate putative novel blood transcriptome biomarkers of AD that can potentially be identified in the blood of patients. mRNA was extracted from the blood and hippocampus of 3xTg-AD and control mice at different ages and used for microarray analysis. Network and functional analyses revealed that the differentially expressed genes between AD and control mice modulated the immune and neuroinflammation systems. Five novel gene transcripts (Cdkn2a, Apobec3, Magi2, Parp3, and Cass4) showed significant increases with age, and their expression in the blood was collated with that in the hippocampus only in AD mice. We further assessed previously identified candidate biomarker genes. The expression of Trem1 and Trem2 in both the blood and brain was significantly increased with age. Decreased Tomm40 and increased Pink1 mRNA levels were observed in the mouse blood. The changes in the expression of Snca and Apoe mRNA in the mouse blood and brain were similar to those found in human AD blood. Our results demonstrated that the immune and neuroinflammatory system is involved in the pathophysiologies of aging and AD and that the blood transcriptome might be useful as a biomarker of AD.
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Affiliation(s)
- Shinichiro Ochi
- Department of Neuropsychiatry, Molecules and Function, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, 791-0295, Japan
| | - Jun-Ichi Iga
- Department of Neuropsychiatry, Molecules and Function, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, 791-0295, Japan.
| | - Yu Funahashi
- Department of Neuropsychiatry, Molecules and Function, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, 791-0295, Japan
| | - Yuta Yoshino
- Department of Neuropsychiatry, Molecules and Function, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, 791-0295, Japan
| | - Kiyohiro Yamazaki
- Department of Neuropsychiatry, Molecules and Function, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, 791-0295, Japan
| | - Hiroshi Kumon
- Department of Neuropsychiatry, Molecules and Function, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, 791-0295, Japan
| | - Hiroaki Mori
- Department of Neuropsychiatry, Molecules and Function, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, 791-0295, Japan
| | - Yuki Ozaki
- Department of Neuropsychiatry, Molecules and Function, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, 791-0295, Japan
| | - Takaaki Mori
- Department of Neuropsychiatry, Molecules and Function, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, 791-0295, Japan
| | - Shu-Ichi Ueno
- Department of Neuropsychiatry, Molecules and Function, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, 791-0295, Japan
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Abstract
Dementia is an overarching term which describes a group of symptoms that result in long-term decline in cognitive functioning that is significant enough to affect daily function. It is caused by a number of different diseases, the most common of which is Alzheimer's disease. Currently, there are no definitive biomarkers for preclinical or diagnostic use, or which differentiate between underlying disease types. The purpose of this review is to highlight several important areas of research on blood-based biomarkers of dementia, with a specific focus on epigenetic biomarkers. A systematic search of the literature identified 77 studies that compared blood DNA methylation between individuals with dementia and controls and 45 studies that measured microRNA. Very few studies were identified that focused on histone modifications. There were many promising findings from studies in the field of blood-based epigenetic biomarkers of dementia, however, a lack of consistency in study design, technologies, and platforms used for the biomarker measurement, as well as statistical analysis methods, have hampered progress. To date, there are very few findings that have been independently replicated across more than one study, indicating a preponderance of false-positive findings and the field has likely been plagued by positive publication bias. Here, we highlight and discuss several of the limitations of existing studies and provide recommendations for how these could be overcome in future research. A robust framework should be followed to enable development of the most valid and reproducible biomarkers with the strongest clinical utility. Defining a series of biomarkers that may be complimentary to each other could permit a stronger multifactorial biomarker to be developed that would allow for not only accurate dementia diagnosis but preclinical detection.
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Affiliation(s)
- Peter D Fransquet
- Department of Epidemiology and Preventive Medicine, Monash University , Melbourne , Australia.,Disease Epigenetics, Murdoch Children's Research Institute , Parkville , Australia
| | - Joanne Ryan
- Department of Epidemiology and Preventive Medicine, Monash University , Melbourne , Australia.,Disease Epigenetics, Murdoch Children's Research Institute , Parkville , Australia
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