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Li X, He Q, Zhao N, Chen X, Li T, Cheng B. High intensity interval training ameliorates cognitive impairment in T2DM mice possibly by improving PI3K/Akt/mTOR Signaling-regulated autophagy in the hippocampus. Brain Res 2021; 1773:147703. [PMID: 34743961 DOI: 10.1016/j.brainres.2021.147703] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 10/11/2021] [Accepted: 10/22/2021] [Indexed: 10/19/2022]
Abstract
Exercise can improve cognitive impairment in type 2 diabetes mellitus (T2DM). However, the underlying mechanisms are not clear, and the optimal exercise modes for cognitive benefits are controversial. The aim of this study was to investigate the effects of high-intensity interval training (HIIT) and moderate-intensity interval training (MICT) on cognitive function and the PI3K/Akt/mTOR pathway as well as autophagy in T2DM mice. The results showed that 8 weeks of HIIT and MICT intervention could improve the spatial learning and memory ability of T2DM mice, as determined by the Morris water maze (MWM) test. Both HIIT and MICT similarly improved autophagy, as evidenced by increased Beclin1 and LC3 II/I ratios and decreased p62. Meanwhile, HIIT and MICT inhibited excessive activation of the PI3K/Akt/mTOR pathway in the hippocampus. HIIT induced a larger reduction in mTOR activity than MICT. This study suggests that both HIIT and MICT can alleviate cognitive decline induced by T2DM, improve autophagy in the hippocampus, and downregulate the excessive activation of the PI3K/Akt/mTOR signaling pathway, with similar effects.
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Affiliation(s)
- Xuejiao Li
- School of Physical Education of Shandong University, Jinan, China
| | - Qiang He
- School of Physical Education of Shandong University, Jinan, China
| | - Na Zhao
- Key Laboratory of Adolescent Health Assessment and Exercise Intervention of Ministry of Education, East China Normal University, Shanghai, China
| | - Xianghe Chen
- College of Physical Education, Yangzhou University, Yangzhou, China
| | - Tuojian Li
- School of Physical Education of Shandong University, Jinan, China
| | - Bin Cheng
- School of Physical Education of Shandong University, Jinan, China.
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Hobday AL, Parmar MS. The Link Between Diabetes Mellitus and Tau Hyperphosphorylation: Implications for Risk of Alzheimer's Disease. Cureus 2021; 13:e18362. [PMID: 34725612 PMCID: PMC8555851 DOI: 10.7759/cureus.18362] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 09/28/2021] [Indexed: 11/13/2022] Open
Abstract
Diabetes mellitus (DM) is characterized by hyperglycemia caused by a lack of insulin, insulin resistance, or both. It is associated with the development of secondary complications resulting in several comorbidities. Recent studies have revealed an increased risk of developing cognitive dysfunction or dementia in diabetes patients. Diabetes mellitus is considered a risk factor for many neurodegenerative diseases, including Alzheimer's disease (AD). There is increasing evidence to support a link between DM and AD. Studies have shown the dysfunction of insulin signaling in the brain, resulting in increased tau protein phosphorylation (hyperphosphorylation), a hallmark and biomarker of AD pathology, leading to accumulation of neurofibrillary tangles. In DM, the insulin dysfunction in the brain is reported to alter the glycogen synthase kinase-3β (GSK-3β) activity showing to enhance tau phosphorylation. In DM and AD, GSK-3β signaling has been involved in the physiological and pathological processes, respectively. This potentially explains why DM patients have an increased risk of developing AD with disease progression and aging. Interestingly, several in vivo studies with oral antidiabetic drugs and insulin treatment in DM have improved cognitive function and decreased tau hyperphosphorylation. This article will review the relationship between DM and AD as it relates to tau pathology. More understanding of the link between DM and AD could change the approach researchers and clinicians take toward both diseases, potentially leading to new treatments and preventative strategies in the future.
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Affiliation(s)
- Amy L Hobday
- Foundational Sciences, Nova Southeastern University Dr. Kiran C. Patel College of Osteopathic Medicine, Clearwater, USA
| | - Mayur S Parmar
- Foundational Sciences, Nova Southeastern University Dr. Kiran C. Patel College of Osteopathic Medicine, Clearwater, USA
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3
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Querfurth H, Lee HK. Mammalian/mechanistic target of rapamycin (mTOR) complexes in neurodegeneration. Mol Neurodegener 2021; 16:44. [PMID: 34215308 PMCID: PMC8252260 DOI: 10.1186/s13024-021-00428-5] [Citation(s) in RCA: 106] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 02/01/2021] [Indexed: 12/12/2022] Open
Abstract
Novel targets to arrest neurodegeneration in several dementing conditions involving misfolded protein accumulations may be found in the diverse signaling pathways of the Mammalian/mechanistic target of rapamycin (mTOR). As a nutrient sensor, mTOR has important homeostatic functions to regulate energy metabolism and support neuronal growth and plasticity. However, in Alzheimer's disease (AD), mTOR alternately plays important pathogenic roles by inhibiting both insulin signaling and autophagic removal of β-amyloid (Aβ) and phospho-tau (ptau) aggregates. It also plays a role in the cerebrovascular dysfunction of AD. mTOR is a serine/threonine kinase residing at the core in either of two multiprotein complexes termed mTORC1 and mTORC2. Recent data suggest that their balanced actions also have implications for Parkinson's disease (PD) and Huntington's disease (HD), Frontotemporal dementia (FTD) and Amyotrophic Lateral Sclerosis (ALS). Beyond rapamycin; an mTOR inhibitor, there are rapalogs having greater tolerability and micro delivery modes, that hold promise in arresting these age dependent conditions.
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Affiliation(s)
- Henry Querfurth
- Department of Neurology, Tufts Medical Center, Boston, Massachusetts, USA.
| | - Han-Kyu Lee
- Department of Neurology, Tufts Medical Center, Boston, Massachusetts, USA
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Lu C, Zhao Y, Cao Y, Liu L, Wu S, Li D, Liu S, Xiao S, Wei Y, Li X. MALAT1 Regulated mTOR-Mediated Tau Hyperphosphorylation by Acting as a ceRNA of miR144 in Hippocampus Cells Exposed to High Glucose. Clin Interv Aging 2021; 16:1185-1191. [PMID: 34188461 PMCID: PMC8236260 DOI: 10.2147/cia.s304827] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 06/03/2021] [Indexed: 11/23/2022] Open
Abstract
Aim High glucose (HG)-induced activation of mTOR promotes tau phosphorylation and leads to diabetes-associated dementia. This study aimed to explore the role of metastasis associated in lung adenocarcinoma transcript 1 (MALAT1) in HG-induced neuronal cell injury. Methods Hippocampus cells were isolated from C57BL/6J mice. After 6 days of culture, the cells were incubated with 5.5 mM glucose in normal medium or 75 mM glucose for 4 days. Cells were transfected with miR-144 mimic, miR-144 inhibitor, siRNA for MALAT1 or corresponding controls. Gene expression was detected by PCR and Western blot analysis. Results HG increased the levels of MALAT1 and p-tau in hippocampal cells. Knockdown of MALAT1 partially reversed the effects of HG on mTOR activity and p-tau protein levels. MALAT1 functioned as competing endogenous RNA (ceRNA) for miR-144, and pre-treatment with MALAT1 siRNA decreased mTOR activity and p-tau protein level in HG-treated hippocampal cells, which was significantly attenuated by miR-144 mimics. Moreover, miR-144 negatively regulated the expression of mTOR and knockdown of MALAT1 suppressed mTOR, while overexpression of mTOR abrogated protective effects of MALAT1 knockdown in HG-treated hippocampal cells. Conclusion MALAT1 knockdown prevented HG-induced mTOR activation and inhibited tau phosphorylation. MALAT1 may be a therapy target for diabetes associated dementia.
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Affiliation(s)
- Chong Lu
- Department of Neurology, Heilongjiang Provincial Hospital, Harbin, People's Republic of China
| | - Yikui Zhao
- HIT Center for Life Sciences, School of Life Science and Technology, Harbin Institute of Technology, Harbin, People's Republic of China
| | - Yan Cao
- Department of Endocrinology, First Affiliated Hospital of Harbin Medical University, Harbin, People's Republic of China
| | - Li Liu
- Department of Neurology, Heilongjiang Provincial Hospital, Harbin, People's Republic of China
| | - Shanshan Wu
- Department of Neurology, Heilongjiang Provincial Hospital, Harbin, People's Republic of China
| | - Dongbin Li
- Department of Neurology, Heilongjiang Provincial Hospital, Harbin, People's Republic of China
| | - Shuang Liu
- Department of Neurology, Heilongjiang Provincial Hospital, Harbin, People's Republic of China
| | - Shuyuan Xiao
- Department of Neurology, Heilongjiang Provincial Hospital, Harbin, People's Republic of China
| | - Yafen Wei
- Department of Neurology, Heilongjiang Provincial Hospital, Harbin, People's Republic of China
| | - Xinyu Li
- Department of Endocrinology, First Affiliated Hospital of Harbin Medical University, Harbin, People's Republic of China
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Burillo J, Marqués P, Jiménez B, González-Blanco C, Benito M, Guillén C. Insulin Resistance and Diabetes Mellitus in Alzheimer's Disease. Cells 2021; 10:1236. [PMID: 34069890 PMCID: PMC8157600 DOI: 10.3390/cells10051236] [Citation(s) in RCA: 78] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 05/11/2021] [Accepted: 05/13/2021] [Indexed: 12/12/2022] Open
Abstract
Type 2 diabetes mellitus is a progressive disease that is characterized by the appearance of insulin resistance. The term insulin resistance is very wide and could affect different proteins involved in insulin signaling, as well as other mechanisms. In this review, we have analyzed the main molecular mechanisms that could be involved in the connection between type 2 diabetes and neurodegeneration, in general, and more specifically with the appearance of Alzheimer's disease. We have studied, in more detail, the different processes involved, such as inflammation, endoplasmic reticulum stress, autophagy, and mitochondrial dysfunction.
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Affiliation(s)
- Jesús Burillo
- Department of Biochemistry, Complutense University, 28040 Madrid, Spain; (J.B.); (P.M.); (B.J.); (C.G.-B.); (M.B.)
- Centro de Investigación Biomédica en Red (CIBER) de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28040 Madrid, Spain
- Mechanisms of Insulin Resistance (MOIR2), General Direction of Universities and Investigation (CCMM), 28040 Madrid, Spain
| | - Patricia Marqués
- Department of Biochemistry, Complutense University, 28040 Madrid, Spain; (J.B.); (P.M.); (B.J.); (C.G.-B.); (M.B.)
- Mechanisms of Insulin Resistance (MOIR2), General Direction of Universities and Investigation (CCMM), 28040 Madrid, Spain
| | - Beatriz Jiménez
- Department of Biochemistry, Complutense University, 28040 Madrid, Spain; (J.B.); (P.M.); (B.J.); (C.G.-B.); (M.B.)
- Centro de Investigación Biomédica en Red (CIBER) de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28040 Madrid, Spain
- Mechanisms of Insulin Resistance (MOIR2), General Direction of Universities and Investigation (CCMM), 28040 Madrid, Spain
| | - Carlos González-Blanco
- Department of Biochemistry, Complutense University, 28040 Madrid, Spain; (J.B.); (P.M.); (B.J.); (C.G.-B.); (M.B.)
- Mechanisms of Insulin Resistance (MOIR2), General Direction of Universities and Investigation (CCMM), 28040 Madrid, Spain
| | - Manuel Benito
- Department of Biochemistry, Complutense University, 28040 Madrid, Spain; (J.B.); (P.M.); (B.J.); (C.G.-B.); (M.B.)
- Centro de Investigación Biomédica en Red (CIBER) de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28040 Madrid, Spain
- Mechanisms of Insulin Resistance (MOIR2), General Direction of Universities and Investigation (CCMM), 28040 Madrid, Spain
| | - Carlos Guillén
- Department of Biochemistry, Complutense University, 28040 Madrid, Spain; (J.B.); (P.M.); (B.J.); (C.G.-B.); (M.B.)
- Centro de Investigación Biomédica en Red (CIBER) de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28040 Madrid, Spain
- Mechanisms of Insulin Resistance (MOIR2), General Direction of Universities and Investigation (CCMM), 28040 Madrid, Spain
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Ferreira ST. Brain insulin, insulin-like growth factor 1 and glucagon-like peptide 1 signalling in Alzheimer's disease. J Neuroendocrinol 2021; 33:e12959. [PMID: 33739563 DOI: 10.1111/jne.12959] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Revised: 02/07/2021] [Accepted: 02/12/2021] [Indexed: 12/13/2022]
Abstract
Although the brain was once considered an insulin-independent organ, insulin signalling is now recognised as being central to neuronal health and to the function of synapses and brain circuits. Defective brain insulin signalling, as well as related signalling by insulin-like growth factor 1 (IGF-1), is associated with neurological disorders, including Alzheimer's disease, suggesting that cognitive impairment could be related to a state of brain insulin resistance. Here, I briefly review key epidemiological/clinical evidence of the association between diabetes, cognitive decline and AD, as well as findings of reduced components of insulin signalling in AD brains, which led to the initial suggestion that AD could be a type of brain diabetes. Particular attention is given to recent studies illuminating mechanisms leading to neuronal insulin resistance as a key driver of cognitive impairment in AD. Evidence of impaired IGF-1 signalling in AD is also examined. Finally, we discuss potentials and possible limitations of recent and on-going therapeutic approaches based on our increased understanding of the roles of brain signalling by insulin, IGF-1 and glucagon-like peptide 1 in AD.
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Affiliation(s)
- Sergio T Ferreira
- Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
- Institute of Medical Biochemistry Leopoldo de Meis, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
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Dominguez-Meijide A, Vasili E, Outeiro TF. Pharmacological Modulators of Tau Aggregation and Spreading. Brain Sci 2020; 10:E858. [PMID: 33203009 PMCID: PMC7696562 DOI: 10.3390/brainsci10110858] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 11/09/2020] [Accepted: 11/11/2020] [Indexed: 12/25/2022] Open
Abstract
Tauopathies are neurodegenerative disorders characterized by the deposition of aggregates composed of abnormal tau protein in the brain. Additionally, misfolded forms of tau can propagate from cell to cell and throughout the brain. This process is thought to lead to the templated misfolding of the native forms of tau, and thereby, to the formation of newer toxic aggregates, thereby propagating the disease. Therefore, modulation of the processes that lead to tau aggregation and spreading is of utmost importance in the fight against tauopathies. In recent years, several molecules have been developed for the modulation of tau aggregation and spreading. In this review, we discuss the processes of tau aggregation and spreading and highlight selected chemicals developed for the modulation of these processes, their usefulness, and putative mechanisms of action. Ultimately, a stronger understanding of the molecular mechanisms involved, and the properties of the substances developed to modulate them, will lead to the development of safer and better strategies for the treatment of tauopathies.
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Affiliation(s)
- Antonio Dominguez-Meijide
- Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Goettingen, 37073 Goettingen, Germany; (A.D.-M.); (E.V.)
- Laboratory of Neuroanatomy and Experimental Neurology, Dept. of Morphological Sciences, CIMUS, IDIS, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Eftychia Vasili
- Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Goettingen, 37073 Goettingen, Germany; (A.D.-M.); (E.V.)
| | - Tiago Fleming Outeiro
- Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Goettingen, 37073 Goettingen, Germany; (A.D.-M.); (E.V.)
- Max Planck Institute for Experimental Medicine, 37075 Goettingen, Germany
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Framlington Place, Newcastle Upon Tyne NE2 4HH, UK
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8
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Cao Y, Liu B, Xu W, Wang L, Shi F, Li N, Lei Y, Wang J, Tian Q, Zhou X. Inhibition of mTORC1 improves STZ-induced AD-like impairments in mice. Brain Res Bull 2020; 162:166-179. [PMID: 32599128 DOI: 10.1016/j.brainresbull.2020.06.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 05/29/2020] [Accepted: 06/03/2020] [Indexed: 12/12/2022]
Abstract
Alzheimer's disease (AD) and type 2 diabetes mellitus (T2DM) share some pathological features, including tau hyperphosphorylation and deficits in insulin signaling, but the underlying mechanism and effective drugs for treating AD are unknown. The AD-like brain impairments are almost same in both of mouse type 2 DM models induced by the multiple low-dose intraperitoneal (i.p.) streptozotocin (STZ) injection and twice intracerebroventricular (i.c.v.) STZ injection. We found that memory disorders, impairment of insulin signaling, and AD-like tauopathies were exhibited in two different STZ-induced mouse models and that the level of Advanced Glycation End Products (AGEs) was increased in two STZ mouse models. Inhibition of mTORC1 with rapamycin reversed the deficits of insulin signaling associated kinases activity, decreased levels of AGEs and AD-like tau phosphorylation, and also improved memory deficit in both STZ mice. Rapamycin attenuated HG-induced tau hyperphosphorylation via the AKT/AMPK/GSK-3β pathways and p70S6K in SH-SY5Y cells. Taken together, these data demonstrated that rapamycin improved STZ-induced AD-like tauopathies and memory deficit in mice via improving p70S6K and AKT/AMPK/GSK-3β signaling and decreasing AGEs. Therefore, regulating insulin signaling via mTORC1 is a new strategy for preventing T2DM-associated AD, and mTORC1 is a potential drug target.
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Affiliation(s)
- Yun Cao
- Key Laboratory of Neurological Diseases of Education Ministry, Department of Pathophysiology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, PR China
| | - Bingjin Liu
- School of Medicine and Pharmaceutical Engineering, Taizhou Vocational and Technical College, Taizhou 318000, PR China
| | - Weiqi Xu
- Key Laboratory of Neurological Diseases of Education Ministry, Department of Pathophysiology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, PR China
| | - Lin Wang
- Key Laboratory of Neurological Diseases of Education Ministry, Department of Pathophysiology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, PR China
| | - Fangxiao Shi
- Key Laboratory of Neurological Diseases of Education Ministry, Department of Pathophysiology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, PR China
| | - Na Li
- Key Laboratory of Neurological Diseases of Education Ministry, Department of Pathophysiology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, PR China
| | - Ying Lei
- Key Laboratory of Neurological Diseases of Education Ministry, Department of Pathophysiology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, PR China
| | - Jianzhi Wang
- Key Laboratory of Neurological Diseases of Education Ministry, Department of Pathophysiology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, PR China
| | - Qing Tian
- Key Laboratory of Neurological Diseases of Education Ministry, Department of Pathophysiology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, PR China.
| | - Xinwen Zhou
- Key Laboratory of Neurological Diseases of Education Ministry, Department of Pathophysiology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, PR China.
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9
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Jiang Y, Li L, Dai CL, Zhou R, Gong CX, Iqbal K, Gu JH, Liu F. Effect of Peripheral Insulin Administration on Phosphorylation of Tau in the Brain. J Alzheimers Dis 2020; 75:1377-1390. [PMID: 32417781 DOI: 10.3233/jad-200147] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Abnormally hyperphosphorylated tau is the major protein of neurofibrillary tangles in Alzheimer's disease. Insulin activates PI3K-AKT signaling and regulates tau phosphorylation. Impaired brain insulin signaling is involved in Alzheimer's disease pathogenesis. However, the effect of peripheral insulin on tau phosphorylation is controversial. OBJECTIVE In the present study, we determined the effect of peripheral insulin administration on tau phosphorylation in brain. METHODS We intraperitoneally injected a super physiological dose of insulin to mice and analyzed PI3K-AKT signaling and tau phosphorylation in brains by western blots. RESULTS We found that peripherally administered insulin activated the PI3K-AKT signaling pathway immediately in the liver, but not in the brain. Tau phosphorylation in the mouse brain was found to be first decreased (15 min) and then increased (30 min and 60 min) after peripheral insulin administration and these changes correlated inversely with body temperature and the level of brain protein O-GlcNAcylation. Maintaining body temperature of mice post peripheral insulin administration prevented the insulin/hypoglycemia-induced tau hyperphosphorylation after peripheral insulin administration. CONCLUSION These findings suggest that peripheral insulin can induce tau hyperphosphorylation through both hypothermia and downregulation of brain protein O-GlcNAcylation during hypoglycemia.
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Affiliation(s)
- Yanli Jiang
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education of China, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu, China.,Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
| | - Longfei Li
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education of China, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu, China.,Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
| | - Chun-Ling Dai
- Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
| | - Ranran Zhou
- Department of Endocrinology, Affiliated Hospital of Nantong University, Nantong, Jiangsu, China
| | - Cheng-Xin Gong
- Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
| | - Khalid Iqbal
- Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
| | - Jin-Hua Gu
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education of China, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu, China.,Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA.,Department of Clinical Pharmacy, Affiliated Maternity & Child Health Care Hospital of Nantong University, Nantong, Jiangsu, China
| | - Fei Liu
- Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
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10
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Moon GJ, Shin M, Kim SR. Upregulation of Neuronal Rheb(S16H) for Hippocampal Protection in the Adult Brain. Int J Mol Sci 2020; 21:E2023. [PMID: 32188096 PMCID: PMC7139780 DOI: 10.3390/ijms21062023] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 03/14/2020] [Accepted: 03/16/2020] [Indexed: 12/20/2022] Open
Abstract
Ras homolog protein enriched in brain (Rheb) is a key activator of mammalian target of rapamycin complex 1 (mTORC1). The activation of mTORC1 by Rheb is associated with various processes such as protein synthesis, neuronal growth, differentiation, axonal regeneration, energy homeostasis, autophagy, and amino acid uptake. In addition, Rheb-mTORC1 signaling plays a crucial role in preventing the neurodegeneration of hippocampal neurons in the adult brain. Increasing evidence suggests that the constitutive activation of Rheb has beneficial effects against neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD). Our recent studies revealed that adeno-associated virus serotype 1 (AAV1) transduction with Rheb(S16H), a constitutively active form of Rheb, exhibits neuroprotective properties through the induction of various neurotrophic factors, promoting neurotrophic interactions between neurons and astrocytes in the hippocampus of the adult brain. This review provides compelling evidence for the therapeutic potential of AAV1-Rheb(S16H) transduction in the hippocampus of the adult brain by exploring its neuroprotective effects and mechanisms.
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Affiliation(s)
- Gyeong Joon Moon
- BK21 plus KNU Creative BioResearch Group, School of Life Sciences, Kyungpook National University, Daegu 41566, Korea;
| | - Minsang Shin
- Brain Science and Engineering Institute, Kyungpook National University, Daegu 41566, Korea;
- Department of Microbiology, School of Medicine, Kyungpook National University, Daegu 41944, Korea
| | - Sang Ryong Kim
- BK21 plus KNU Creative BioResearch Group, School of Life Sciences, Kyungpook National University, Daegu 41566, Korea;
- Brain Science and Engineering Institute, Kyungpook National University, Daegu 41566, Korea;
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Huang R, Tian S, Zhang H, Zhu W, Wang S. Chronic hyperglycemia induces tau hyperphosphorylation by downregulating OGT-involved O-GlcNAcylation in vivo and in vitro. Brain Res Bull 2020; 156:76-85. [PMID: 31931119 DOI: 10.1016/j.brainresbull.2020.01.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 12/07/2019] [Accepted: 01/03/2020] [Indexed: 01/06/2023]
Abstract
OBJECTIVE Diabetes mellitus (DM) can increase the risk of cognitive dysfunction, but its exact mechanisms remain unclear. The involvement of aberrant O-GlcNAcylation has been identified in hyperglycemia and DM, as well as the pathogenesis of Alzheimer's disease via competition with tau phosphorylation. This study was designed to investigate the role of O-GlcNAcylation in diabetes-associated cognitive dysfunction (DACD). METHODS Fifteen-week old male KK-Ay mice were used as DACD models, and advanced glycation end product (AGE)-treated HT22 cells were used as a model of high glucose toxicity. Morris water maze tests, histological staining, real-time quantitative PCR, and Western blot were also applied. RESULTS Mice with DACD exhibited evident obesity, hyperinsulinemia, hyperglycemia, and impaired learning and memory function. O-GlcNAcylation levels decreased and tau phosphorylation levels at Ser396, Ser404, Thr212, and Thr231 increased in the hippocampus of mice with DACD, as well as in AGE-treated HT22 cells. Hypoglycemic therapy improved these anomalies and elevated O-GlcNAc transferase (OGT) levels in mice with DACD. OGT plasmid transfection in HT22 cells partially reversed AGE-induced decreases in O-GlcNAcylation levels and increased tau phosphorylation levels. CONCLUSIONS Chronic hyperglycemia can induce tau hyperphosphorylation by downregulating OGT-involved O-GlcNAcylation in vivo and in vitro, which mediates DACD.
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Affiliation(s)
- Rong Huang
- Department of Endocrinology, Affiliated Zhongda Hospital of Southeast University, No. 87 DingJiaQiao Road, Nanjing, 210009, PR China; Department of Endocrinology, Nanjing First Hospital, Nanjing Medical University, No. 68 Changle Road, Nanjing, 210006, PR China
| | - Sai Tian
- Department of Endocrinology, Affiliated Zhongda Hospital of Southeast University, No. 87 DingJiaQiao Road, Nanjing, 210009, PR China
| | - Haoqiang Zhang
- Department of Endocrinology, Affiliated Zhongda Hospital of Southeast University, No. 87 DingJiaQiao Road, Nanjing, 210009, PR China
| | - Wenwen Zhu
- Department of Endocrinology, Affiliated Zhongda Hospital of Southeast University, No. 87 DingJiaQiao Road, Nanjing, 210009, PR China
| | - Shaohua Wang
- Department of Endocrinology, Affiliated Zhongda Hospital of Southeast University, No. 87 DingJiaQiao Road, Nanjing, 210009, PR China.
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12
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Kim B, Elzinga SE, Henn RE, McGinley LM, Feldman EL. The effects of insulin and insulin-like growth factor I on amyloid precursor protein phosphorylation in in vitro and in vivo models of Alzheimer's disease. Neurobiol Dis 2019; 132:104541. [PMID: 31349033 DOI: 10.1016/j.nbd.2019.104541] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 07/15/2019] [Accepted: 07/22/2019] [Indexed: 12/12/2022] Open
Abstract
Alzheimer's disease (AD) is a growing problem worldwide, and there are currently no effective treatments for this devastating disease. The neurotrophic growth factors insulin and insulin-like growth factor-I (IGF-I) are currently being investigated as potential therapeutic approaches for AD in preclinical and clinical studies. However, given that the metabolic syndrome (MetS) and diabetes are risk factors for AD, it is unknown how associated insulin resistance (IR) in the brain may impact the effectiveness of these therapies for AD. In this report, we therefore investigated the mechanisms underlying the effects of insulin and IGF-I on AD-associated pathology in the context of IR, with particular emphasis on phosphorylation of amyloid precursor protein (APP), a key step in promoting amyloid plaque formation in AD. Both insulin and IGF-I decreased APP phosphorylation in cultured primary cortical neurons, supporting their therapeutic use in AD. Induction of IR blocked the beneficial effect of insulin and reduced the effect of IGF-I on APP dephosphorylation. These effects were mediated by the phosphatidylinositol 3-kinase (PI3-K)/protein kinase B (Akt) pathway, as inhibition of this pathway during IR restored the effect of IGF-I on APP dephosphorylation. Finally, we explored the translational relevance of these results in vivo by demonstrating that high fat diet fed mice, a robust model of IR and MetS, exhibited the expected increased brain APP phosphorylation. Overall, these data suggest that the beneficial therapeutic effect of insulin and IGF-I on APP phosphorylation is negatively impacted by IR, and suggest that insulin and IGF-I alone may not be appropriate therapies for AD patients with IR, MetS, or diabetes.
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Affiliation(s)
- Bhumsoo Kim
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, United States of America
| | - Sarah E Elzinga
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, United States of America
| | - Rosemary E Henn
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, United States of America
| | - Lisa M McGinley
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, United States of America
| | - Eva L Feldman
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, United States of America.
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13
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Martini AC, Forner S, Trujillo-Estrada L, Baglietto-Vargas D, LaFerla FM. Past to Future: What Animal Models Have Taught Us About Alzheimer's Disease. J Alzheimers Dis 2019; 64:S365-S378. [PMID: 29504540 DOI: 10.3233/jad-179917] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Alzheimer's disease (AD) impairs memory and causes significant cognitive deficits. The disease course is prolonged, with a poor prognosis, and thus exacts an enormous economic and social burden. Over the past two decades, genetically engineered mouse models have proven indispensable for understanding AD pathogenesis, as well as for discovering new therapeutic targets. Here we highlight significant studies from our laboratory that have helped advance the AD field by elucidating key pathogenic processes operative in AD and exploring a variety of aspects of the disease which may yield novel therapeutic strategies for combatting this burdensome disease.
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Affiliation(s)
- Alessandra C Martini
- Institute for Memory Impairments andNeurological Disorders, University of California, Irvine, CA, USA
| | - Stefania Forner
- Institute for Memory Impairments andNeurological Disorders, University of California, Irvine, CA, USA
| | - Laura Trujillo-Estrada
- Institute for Memory Impairments andNeurological Disorders, University of California, Irvine, CA, USA
| | - David Baglietto-Vargas
- Institute for Memory Impairments andNeurological Disorders, University of California, Irvine, CA, USA
| | - Frank M LaFerla
- Institute for Memory Impairments andNeurological Disorders, University of California, Irvine, CA, USA.,Department of Neurobiology and Behavior, University of California, Irvine, CA, USA
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14
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Mechanisms Associated with Type 2 Diabetes as a Risk Factor for Alzheimer-Related Pathology. Mol Neurobiol 2019; 56:5815-5834. [PMID: 30684218 DOI: 10.1007/s12035-019-1475-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 01/10/2019] [Indexed: 12/19/2022]
Abstract
Current evidence suggests dementia and pathology in Alzheimer's Disease (AD) are both dependent and independent of amyloid processing and can be induced by multiple 'hits' on vital neuronal functions. Type 2 diabetes (T2D) poses the most important risk factor for developing AD after ageing and dysfunctional IR/PI3K/Akt signalling is a major contributor in both diseases. We developed a model of T2D, coupling subdiabetogenic doses of streptozotocin (STZ) with a human junk food (HJF) diet to more closely mimic the human condition. Over 35 weeks, this induced classic signs of T2D (hyperglycemia and insulin dysfunction) and a modest, but stable deficit in spatial recognition memory, with very little long-term modification of proteins in or associated with IR/PI3K/Akt signalling in CA1 of the hippocampus. Intracerebroventricular infusion of soluble amyloid beta 42 (Aβ42) to mimic the early preclinical rise in Aβ alone induced a more severe, but short-lasting deficits in memory and deregulation of proteins. Infusion of Aβ on the T2D phenotype exacerbated and prolonged the memory deficits over approximately 4 months, and induced more severe aberrant regulation of proteins associated with autophagy, inflammation and glucose uptake from the periphery. A mild form of environmental enrichment transiently rescued memory deficits and could reverse the regulation of some, but not all protein changes. Together, these data identify mechanisms by which T2D could create a modest dysfunctional neuronal milieu via multiple and parallel inputs that permits the development of pathological events identified in AD and memory deficits when Aβ levels are transiently effective in the brain.
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15
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Liang H, Nie J, Van Skike CE, Valentine JM, Orr ME. Mammalian Target of Rapamycin at the Crossroad Between Alzheimer's Disease and Diabetes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1128:185-225. [PMID: 31062331 DOI: 10.1007/978-981-13-3540-2_10] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Accumulating evidence suggests that Alzheimer's disease may manifest as a metabolic disorder with pathology and/or dysfunction in numerous tissues. Adults with Alzheimer's disease suffer with significantly more comorbidities than demographically matched Medicare beneficiaries (Zhao et al, BMC Health Serv Res 8:108, 2008b). Reciprocally, comorbid health conditions increase the risk of developing Alzheimer's disease (Haaksma et al, PLoS One 12(5):e0177044, 2017). Type 2 diabetes mellitus is especially notable as the disease shares many overlapping pathologies observed in patients with Alzheimer's disease, including hyperglycemia, hyperinsulinemia, insulin resistance, glucose intolerance, dyslipidemia, inflammation, and cognitive dysfunction, as described in Chap. 8 of this book (Yoshitake et al, Neurology 45(6):1161-1168, 1995; Leibson et al, Am J Epidemiol 145(4):301-308, 1997; Ott et al, Neurology 53(9):1937-1942, 1999; Voisin et al, Rev Med Interne 24(Suppl 3):288s-291s, 2003; Janson et al. Diabetes 53(2):474-481, 2004; Ristow M, J Mol Med (Berl) 82(8):510-529, 2004; Whitmer et al, BMJ 330(7504):1360, 2005, Curr Alzheimer Res 4(2):103-109, 2007; Ohara et al, Neurology 77(12):1126-1134, 2011). Although nondiabetic older adults also experience age-related cognitive decline, diabetes is uniquely associated with a twofold increased risk of Alzheimer's disease, as described in Chap. 2 of this book (Yoshitake et al, Neurology 45(6):1161-1168, 1995; Leibson et al, Am J Epidemiol 145(4):301-308, 1997; Ott et al. Neurology 53(9):1937-1942, 1999; Ohara et al, Neurology 77(12):1126-1134, 2011). Good glycemic control has been shown to improve cognitive status (Cukierman-et al, Diabetes Care 32(2):221-226, 2009), and the use of insulin sensitizers is correlated with a lower rate of cognitive decline in older adults (Morris JK, Burns JM, Curr Neurol Neurosci Rep 12(5):520-527, 2012). At the molecular level, the mechanistic/mammalian target of rapamycin (mTOR) plays a key role in maintaining energy homeostasis. Nutrient availability and cellular stress information, both extracellular and intracellular, are integrated and transduced through mTOR signaling pathways. Aberrant regulation of mTOR occurs in the brains of patients with Alzheimer's disease and in numerous tissues of individuals with type 2 diabetes (Mannaa et al, J Mol Med (Berl) 91(10):1167-1175, 2013). Moreover, modulating mTOR activity with a pharmacological inhibitor, rapamycin, provides wide-ranging health benefits, including healthy life span extension in numerous model organisms (Vellai et al, Nature 426(6967):620, 2003; Jia et al, Development 131(16):3897-3906, 2004; Kapahi et al, Curr Biol 14(10):885-890, 2004; Kaeberlein et al, Science 310(5751):1193-1196, 2005; Powers et al, Genes Dev 20(2):174-184, 2006; Harrison et al, Nature 460(7253):392-395, 2009; Selman et al, Science 326(5949):140-144, 2009; Sharp ZD, Strong R, J Gerontol A Biol Sci Med Sci 65(6):580-589, 2010), which underscores its importance to overall organismal health and longevity. In this chapter, we discuss the physiological role of mTOR signaling and the consequences of mTOR dysregulation in the brain and peripheral tissues, with emphasis on its relevance to the development of Alzheimer's disease and link to type 2 diabetes.
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Affiliation(s)
- Hanyu Liang
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Jia Nie
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Candice E Van Skike
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Joseph M Valentine
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Miranda E Orr
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
- San Antonio Geriatric Research, Education and Clinical Center, South Texas Veterans Health Care System, San Antonio, TX, USA.
- Glenn Biggs Institute for Alzheimer's & Neurodegenerative Diseases, San Antonio, TX, USA.
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16
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Sun Q, Wei LL, Zhang M, Li TX, Yang C, Deng SP, Zeng QC. Rapamycin inhibits activation of AMPK-mTOR signaling pathway-induced Alzheimer's disease lesion in hippocampus of rats with type 2 diabetes mellitus. Int J Neurosci 2018; 129:179-188. [PMID: 29962282 DOI: 10.1080/00207454.2018.1491571] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND Type 2 diabetes mellitus (T2DM) is strongly correlated with Alzheimer's disease (AD). Rapamycin has important uses in oncology, cardiology and transplantation medicine. This study aims to investigate effects of rapamycin on AD in hippocampus of T2DM rat by AMPK/mTOR signaling pathway. METHODS Morris water maze test was applied to evaluate the learning and memory abilities. The fasting plasma glucose (FBG), glycosylated haemoglobin, total cholesterol, triglyceride and serum insulin level were measured. RT-qPCR and Western blot analysis were performed to test expression of AMPK and mTOR. Immunohistochemistry was used to detect the Aβ deposition and immunoblotting to test the total tau, p-tau and Aβ precursor APP expressions. RESULTS After treated with rapamycin, T2DM rats and rats with T2DM and AD showed increased learning-memory ability, and decreased levels of FBG, glycosylated hemoglobin, total cholesterol, triglyceride and serum insulin, decreased expression of APP and p-tau, increased AMPK mRNA expression and p-AMPK and decreased Aβ deposition, mTOR mRNA expression and p-mTOR. CONCLUSION The study demonstrated that rapamycin reduces the risk of AD in T2DM rats and inhibits activation of AMPK-mTOR signaling pathway, thereby improving AD lesion in hippocampus of T2DM rats.
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Affiliation(s)
- Qin Sun
- a Department of Geratology, Center of Diabetes Mellitus, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, School of Medicine , University of Electronic Science and Technology of China , Chengdu , Sichuan Province , PR China
| | - Ling-Ling Wei
- b Department of Organ Transplantation , Center of Diabetes Mellitus, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China , Chengdu, Sichuan Province , PR China
| | - Min Zhang
- c Department of Geratology , Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital , Chengdu , PR China
| | - Ting-Xin Li
- d Department of General Medicine , Health Management Center, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital , Chengdu , PR China
| | - Chun Yang
- e Department of Gastrointestinal Surgery , Center of Diabetes Mellitus, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu , Chengdu , PR China
| | - Shao-Ping Deng
- b Department of Organ Transplantation , Center of Diabetes Mellitus, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China , Chengdu, Sichuan Province , PR China
| | - Qing-Cui Zeng
- c Department of Geratology , Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital , Chengdu , PR China
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17
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Braidy N, Essa MM, Poljak A, Selvaraju S, Al-Adawi S, Manivasagm T, Thenmozhi AJ, Ooi L, Sachdev P, Guillemin GJ. Consumption of pomegranates improves synaptic function in a transgenic mice model of Alzheimer's disease. Oncotarget 2018; 7:64589-64604. [PMID: 27486879 PMCID: PMC5323101 DOI: 10.18632/oncotarget.10905] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 06/17/2016] [Indexed: 01/18/2023] Open
Abstract
Alzheimer's Disease (AD) is a progressive neurodegenerative disorder characterized by extracellular plaques containing abnormal Amyloid Beta (Aβ) aggregates, intracellular neurofibrillary tangles containing hyperphosphorylated tau protein, microglia-dominated neuroinflammation, and impairments in synaptic plasticity underlying cognitive deficits. Therapeutic strategies for the treatment of AD are currently limited. In this study, we investigated the effects of dietary supplementation of 4% pomegranate extract to a standard chow diet on neuroinflammation, and synaptic plasticity in APPsw/Tg2576 mice brain. Treatment with a custom mixed diet (pellets) containing 4% pomegranate for 15 months ameliorated the loss of synaptic structure proteins, namely PSD-95, Munc18-1, and SNAP25, synaptophysin, phosphorylation of Calcium/Calmodulin Dependent Protein Kinase IIα (p-CaMKIIα/ CaMKIIα), and phosphorylation of Cyclic AMP-Response Element Binding Protein (pCREB/CREB), inhibited neuroinflammatory activity, and enhanced autophagy, and activation of the phophoinositide-3-kinase-Akt-mammalian target of rapamycin signaling pathway. These neuroprotective effects were associated with reduced β-site cleavage of Amyloid Precursor Protein in APPsw/Tg2576 mice. Therefore, long-term supplementation with pomegranates can attenuate AD pathology by reducing inflammation, and altering APP-dependent processes.
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Affiliation(s)
- Nady Braidy
- Centre for Healthy Brain Ageing, School of Psychiatry, Faculty of Medicine, University of New South Wales, Sydney, Australia
| | - Musthafa Mohamed Essa
- Department of Food Science and Nutrition, College of Agricultural and Marine Sciences, Sultan Qaboos University, Al Khoudh, Oman.,Ageing and Dementia Research Group, Sultan Qaboos University, Al Khoudh, Oman
| | - Anne Poljak
- Centre for Healthy Brain Ageing, School of Psychiatry, Faculty of Medicine, University of New South Wales, Sydney, Australia.,College of Medicine and Health Sciences, Sultan Qaboos University, Al Khoudh, Oman
| | - Subash Selvaraju
- Department of Food Science and Nutrition, College of Agricultural and Marine Sciences, Sultan Qaboos University, Al Khoudh, Oman.,Ageing and Dementia Research Group, Sultan Qaboos University, Al Khoudh, Oman
| | - Samir Al-Adawi
- Department of Food Science and Nutrition, College of Agricultural and Marine Sciences, Sultan Qaboos University, Al Khoudh, Oman.,College of Medicine and Health Sciences, Sultan Qaboos University, Al Khoudh, Oman
| | | | | | - Lezanne Ooi
- Illawarra Health and Medical Research Institute, University of Wollongong, NSW, Australia
| | - Perminder Sachdev
- Centre for Healthy Brain Ageing, School of Psychiatry, Faculty of Medicine, University of New South Wales, Sydney, Australia.,Neuropsychiatric Institute, The Prince of Wales Hospital, Sydney, Australia
| | - Gilles J Guillemin
- Neuroinflammation Group, MND and Neurodegenerative Diseases Research Centre, Macquarie University, NSW, Australia
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18
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Lee HK, Kwon B, Lemere CA, de la Monte S, Itamura K, Ha AY, Querfurth HW. mTORC2 (Rictor) in Alzheimer's Disease and Reversal of Amyloid-β Expression-Induced Insulin Resistance and Toxicity in Rat Primary Cortical Neurons. J Alzheimers Dis 2018; 56:1015-1036. [PMID: 28035937 DOI: 10.3233/jad-161029] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Mammalian target of rapamycin complex 1 (mTORC1), a nutrient sensor and central controller of cell growth and proliferation, is altered in various models of Alzheimer's disease (AD). Even less studied or understood in AD is mammalian target of rapamycin complex 2 (mTORC2) that influences cellular metabolism, in part through the regulations of Akt/PKB and SGK. Dysregulation of insulin/PI3K/Akt signaling is another important feature of AD pathogenesis. We found that both total mTORC1 and C2 protein levels and individual C1 and C2 enzymatic activities were decreased in human AD brain samples. In two rodent AD models, mTORC1 and C2 activities were also decreased. In a neuronal culture model of AD characterized by accumulation of cellular amyloid-β (Aβ)42, mTORC1 activity was reduced. Autophagic vesicles and markers were correspondingly increased and new protein synthesis was inhibited, consistent with mTORC1 hypofunction. Interestingly, mTORC2 activity in neural culture seemed resistant to the effects of intracellular amyloid. In various cell lines, Aβ expression provoked insulin resistance, characterized by inhibition of stimulated Akt phosphorylation, and an increase in negative mTORC1 regular, p-AMPK, itself a nutrient sensor. Rapamycin decreased phospho-mTOR and to lesser degree p-Rictor. This further suppression of mTORC1 activity protected cells from Aβ-induced toxicity and insulin resistance. More striking, Rictor over-expression fully reversed the Aβ-effects on primary neuronal cultures. Finally, using in vitro assay, Rictor protein addition completely overcame oligomeric Aβ-induced inhibition of the PDK-Akt activation step. We conclude that striking a new balance by restoring mTORC2 abundance and/or inhibition of mTORC1 has therapeutic potential in AD.
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Affiliation(s)
- Han-Kyu Lee
- Department of Neurology, Rhode Island Hospital and Brown University Warren Alpert Medical School, Providence, RI, USA
| | - Bumsup Kwon
- Department of Neurology, Rhode Island Hospital and Brown University Warren Alpert Medical School, Providence, RI, USA
| | - Cynthia A Lemere
- Ann Romney Center for Neurologic Diseases, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Suzanne de la Monte
- Department of Pathology, Rhode Island Hospital and Brown University Warren Alpert Medical School, Providence, RI, USA
| | - Kyohei Itamura
- Department of Neurology, Rhode Island Hospital and Brown University Warren Alpert Medical School, Providence, RI, USA
| | - Austin Y Ha
- Department of Neurology, Rhode Island Hospital and Brown University Warren Alpert Medical School, Providence, RI, USA
| | - Henry W Querfurth
- Department of Neurology, Rhode Island Hospital and Brown University Warren Alpert Medical School, Providence, RI, USA
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19
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Crespo MC, Tomé-Carneiro J, Pintado C, Dávalos A, Visioli F, Burgos-Ramos E. Hydroxytyrosol restores proper insulin signaling in an astrocytic model of Alzheimer's disease. Biofactors 2017; 43:540-548. [PMID: 28317262 DOI: 10.1002/biof.1356] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Revised: 01/16/2017] [Accepted: 02/08/2017] [Indexed: 12/23/2022]
Abstract
Recent epidemiological evidence demonstrated that diabetes is a risk factor for AD onset and development. Indeed, meta-analyses of longitudinal epidemiologic studies show that diabetes increases AD risk by 50-100%, being insulin resistance (IR) the main binding link between diabetes and AD. Astrocytes are the foremost cerebral macroglial cells and are responsible for converting glucose into lactate and transfer it to neurons that use it as fuel, but Aβ(1-42) impairs insulin signaling and glycogen storage. Recent prospective studies showed that the Mediterranean diet is associated with lower incidence of AD. We hypothesized that hydroxytyrosol (HT, the preeminent polyphenol of olives and olive oil) could exert beneficial effects on IR associated with AD and investigated it mechanisms of action in an astrocytic model of AD. The astrocytic cell line C6 was exposed to Aβ(25-35) and co-incubated with HT for different periods. After treatment with Aβ(25-35), astrocytes' viability was significantly decreased as compared with controls; however, both pre- and post-treatment with HT prevented this effect. Mechanistically, we found that the preventive role of HT on Aβ(25-35)- induced cytotoxicity in astrocytes is moderated by an increased HT-induced activation of Akt, which is mediated by the insulin signaling pathway. In addition, we report that HT prevented the pronounced activation of mTOR, thereby restoring proper insulin signaling. In conclusion, we demonstrate that HT protects Aβ(25-35)-treated astrocytes by improving insulin sensitivity and restoring proper insulin-signaling. These data provide some mechanistic insight on the observed inverse association between olive oil consumption and prevalence of cognitive impairment. © 2017 BioFactors, 43(4):540-548, 2017.
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Affiliation(s)
| | | | - Cristina Pintado
- Facultad de Ciencias Ambientales y Bioquímica, Universidad de Castilla-La Mancha, Toledo, Spain
| | | | - Francesco Visioli
- IMDEA-Food, CEI UAM+CSIC, Madrid, Spain
- Department of Molecular Medicine, University of Padova, Padova, Italy
| | - Emma Burgos-Ramos
- Facultad de Ciencias Ambientales y Bioquímica, Universidad de Castilla-La Mancha, Toledo, Spain
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20
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Proteomic approach to detect changes in hippocampal protein levels in an animal model of type 2 diabetes. Neurochem Int 2017; 108:246-253. [PMID: 28434974 DOI: 10.1016/j.neuint.2017.04.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Revised: 03/16/2017] [Accepted: 04/19/2017] [Indexed: 12/21/2022]
Abstract
In our previous study, we demonstrated that type 2 diabetes affects blood-brain barrier integrity and ultrastructural morphology in Zucker diabetic fatty (ZDF) rats at 40 weeks of age. In the present study, we investigated the possible candidates for diabetes-related proteins in the hippocampus of ZDF rats and their control littermates (Zucker lean control, ZLC), by using two-dimensional fluorescence difference gel electrophoresis (2D-DIGE) followed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF). Approximately 2756 protein spots were detected by 2D-DIGE, and an increase or decrease of more than 1.4-fold was observed for 13 proteins in the hippocampal homogenates of ZDF rats relative to those of ZLC rats. Among these proteins, we found four proteins whose levels were significantly lower in the hippocampi of ZDF rats than in those of ZLC rats: glial fibrillary acidic protein (GFAP), apolipoprotein A-I preprotein (apoAI-P), myelin basic protein (MBP), and rCG39881, isoform CRA_a. Among these proteins, apoAI-P protein levels were decreased most prominently in ZDF rats than in ZLC rats, based on Western blot analysis. In addition, immunohistochemical and Western blot studies demonstrated that MBP, not GFAP, immunoreactivity and protein levels were significantly decreased in the hippocampus of ZDF rats compared to ZLC rats. In addition, ultrastructural analysis showed that ZDF rats showed myelin degeneration and disarrangement in the hippocampal tissue. These results suggest that chronic type 2 diabetes affects hippocampal function via reduction of MBP and apoAI-P levels as well as disarrangement of myelin.
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21
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Shen W, Lu K, Wang J, Wu A, Yue Y. Activation of mTOR signaling leads to orthopedic surgery-induced cognitive decline in mice through β-amyloid accumulation and tau phosphorylation. Mol Med Rep 2016; 14:3925-34. [PMID: 27599409 DOI: 10.3892/mmr.2016.5700] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 07/13/2016] [Indexed: 11/05/2022] Open
Abstract
Postoperative cognitive dysfunction (POCD) is a serious complication following surgery, however, the mechanism of POCD remains to be elucidated. Previous evidence has revealed that POCD may be associated with the pathogenesis of neurodegenerative processes. The mammalian target of rapamycin (mTOR) signaling pathway has been reported to be crucial in the pathophysiology of neurodegenerative diseases. However, the implications of mTOR in POCD remains to be fully elucidated. In the present study, western blotting and enzyme‑linked immunosorbent assay were used to determine the expression of mTOR and any associated downstream targets; contextual fear conditioning was used to estimate the learning and memory ability of mice. Using an animal model of orthopedic surgery, it was found that surgical injury impaired hippocampal‑dependent memory and enhanced the levels of phosphorylated mTOR at Serine‑2448, phosphorylated 70‑kDa ribosomal protein S6 kinase (p70S6K) at Threonine‑389 with accumulation of β‑amyloid (Aβ) and hyperphosphorylated tau at Serine-396, compared with the control group. Pretreatment with rapamycin, an mTOR inhibitor, restored the abnormal mTOR/p70S6K signaling induced by surgery, attenuated the accumulation of Aβ and reduced the phosphorylation of tau protein. Rapamycin also reversed the surgery‑induced cognitive dysfunction. The results of the present study suggested that the surgical stimulus activated mTOR/p70S6K signaling excessively, and that the inhibition of mTOR signaling with rapamycin may prevent postoperative cognitive deficits, partly through attenuating the accumulation of Aβ and hyperphosphorylation of tau protein.
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Affiliation(s)
- Wenzhen Shen
- Department of Anesthesiology, Beijing Chao‑Yang Hospital, Capital Medical University, Beijing 100020, P.R. China
| | - Keliang Lu
- Department of Anesthesiology, Weifang Medical University, Weifang, Shandong 261031, P.R. China
| | - Jiawan Wang
- Department of Anesthesiology, Beijing Chao‑Yang Hospital, Capital Medical University, Beijing 100020, P.R. China
| | - Anshi Wu
- Department of Anesthesiology, Beijing Chao‑Yang Hospital, Capital Medical University, Beijing 100020, P.R. China
| | - Yun Yue
- Department of Anesthesiology, Beijing Chao‑Yang Hospital, Capital Medical University, Beijing 100020, P.R. China
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22
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Diabetes and Alzheimer’s disease crosstalk. Neurosci Biobehav Rev 2016; 64:272-87. [DOI: 10.1016/j.neubiorev.2016.03.005] [Citation(s) in RCA: 122] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Revised: 01/26/2016] [Accepted: 03/04/2016] [Indexed: 12/12/2022]
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23
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Yang Y, Ma D, Xu W, Chen F, Du T, Yue W, Shao S, Yuan G. Exendin-4 reduces tau hyperphosphorylation in type 2 diabetic rats via increasing brain insulin level. Mol Cell Neurosci 2015; 70:68-75. [PMID: 26640240 DOI: 10.1016/j.mcn.2015.10.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 08/30/2015] [Accepted: 10/15/2015] [Indexed: 12/19/2022] Open
Abstract
Type 2 diabetes (T2D) is a high risk factor for Alzheimer's disease (AD). Our previous study identified that hyperphosphorylation of tau protein, which is one of the pathophysiologic hallmarks of AD, also occurred in T2D rats' brain; while glucagon-like peptide-1 (GLP-1) mimetics, a type of drug used in T2D, could decrease the phosphorylation of tau, probably via augmenting insulin signaling pathway. The purpose of this study was to further explore the mechanisms that underlie the effect of exendin-4 (ex-4, a GLP-1 receptor agonist) in reducing tau phosphorylation. We found that peripheral ex-4 injection in T2D rats reduced hyperphosphorylation of tau protein in rat hippocampus, probably via increasing hippocampal insulin which activated insulin signaling. Furthermore, we found that ex-4 could neither activate insulin signaling, nor reduce tau phosphorylation in HT22 neuronal cells in the absence of insulin. These results suggested that insulin is required in reduction of tau hyperphosphorylation by ex-4 in brain rats with T2D.
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Affiliation(s)
- Yan Yang
- Department of Endocrinology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030. PR China
| | - Delin Ma
- Department of Endocrinology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030. PR China
| | - Weijie Xu
- Department of Endocrinology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030. PR China
| | - Fuqiong Chen
- Department of Endocrinology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030. PR China
| | - Tingting Du
- Department of Endocrinology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030. PR China
| | - Wenzhu Yue
- Department of Endocrinology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030. PR China
| | - Shiying Shao
- Department of Endocrinology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030. PR China.
| | - Gang Yuan
- Department of Endocrinology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030. PR China.
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24
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Abstract
TOR (target of rapamycin) and its mammalian ortholog mTOR have been discovered in an effort to understand the mechanisms of action of the immunosuppressant drug rapamycin extracted from a bacterium of the Easter Island (Rapa Nui) soil. mTOR is a serine/threonine kinase found in two functionally distinct complexes, mTORC1 and mTORC2, which are differentially regulated by a great number of nutrients such as glucose and amino acids, energy (oxygen and ATP/AMP content), growth factors, hormones, and neurotransmitters. mTOR controls many basic cellular functions such as protein synthesis, energy metabolism, cell size, lipid metabolism, autophagy, mitochondria, and lysosome biogenesis. In addition, mTOR-controlled signaling pathways regulate many integrated physiological functions of the nervous system including neuronal development, synaptic plasticity, memory storage, and cognition. Thus it is not surprising that deregulation of mTOR signaling is associated with many neurological and psychiatric disorders. Preclinical and preliminary clinical studies indicate that inhibition of mTORC1 can be beneficial for some pathological conditions such as epilepsy, cognitive impairment, and brain tumors, whereas stimulation of mTORC1 (direct or indirect) can be beneficial for other pathologies such as depression or axonal growth and regeneration.
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Affiliation(s)
- Joël Bockaert
- Centre National de la Recherche Scientifique, UMR-5203, Institut de Génomique Fonctionnelle, Montpellier, France; Institut National de la Santé et de la Recherche Médicale U1191, Montpellier, France; and Université de Montpellier, UMR-5203, Montpellier, France
| | - Philippe Marin
- Centre National de la Recherche Scientifique, UMR-5203, Institut de Génomique Fonctionnelle, Montpellier, France; Institut National de la Santé et de la Recherche Médicale U1191, Montpellier, France; and Université de Montpellier, UMR-5203, Montpellier, France
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25
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Liu YW, Zhang L, Li Y, Cheng YQ, Zhu X, Zhang F, Yin XX. Activation of mTOR signaling mediates the increased expression of AChE in high glucose condition: in vitro and in vivo evidences. Mol Neurobiol 2015; 53:4972-80. [PMID: 26374551 DOI: 10.1007/s12035-015-9425-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 09/03/2015] [Indexed: 12/19/2022]
Abstract
Acetylcholinesterase (AChE) is impaired in brain of diabetic animals, which may be one of the reasons for diabetes-associated cognitive decline. However, the mechanism is still unknown. The present study was designed to investigate whether the increased expression of AChE in central neurons under high glucose (HG) condition was due to activation of mammalian target of rapamycin (mTOR) signaling. It was found that more production of reactive oxygen species, and higher levels of phospho-Akt, phospho-mTOR, phospho-p70S6K, and AChE were detected in HT-22 cells in HG group than normal glucose group after culture for 24 h, which were all attenuated by an antioxidant N-acetyl-L-cysteine. A PI3K inhibitor LY294002 significantly decreased the levels of phospho-Akt, phospho-mTOR, phospho-p70S6K, and AChE protein expression in HG-cultured HT-22 cells, and an mTOR inhibitor rapamycin markedly reduced the levels of phospho-mTOR, phospho-p70S6K, and AChE expression. Furthermore, compared with normal rats, diabetic rats showed remarkable increases in levels of AChE activity and expression, malondialdehyde, phospho-mTOR, phospho-p70S6K, and a significant decrease in total superoxide dismutase activity in both hippocampus and cerebral cortex. However, much lower levels of phospho-mTOR, phospho-p70S6K, and AChE expression occurred in both brain regions of diabetic rats treated with rapamycin when compared with untreated ones. These results indicated that mTOR signaling was activated through the activation of PI3K/Akt pathway mediated by oxidative stress in HG-cultured HT-22 cells and diabetic rat brains, which contributed to the elevated protein expression of AChE in central neurons under the condition of HG.
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Affiliation(s)
- Yao-Wu Liu
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical College, No. 209, Tongshan Road, Xuzhou, 221004, Jiangsu, China
| | - Liang Zhang
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical College, No. 209, Tongshan Road, Xuzhou, 221004, Jiangsu, China.,Department of Pharmacy, the People's Hospital of Hebi, Henan, China
| | - Yu Li
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical College, No. 209, Tongshan Road, Xuzhou, 221004, Jiangsu, China
| | - Ya-Qin Cheng
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical College, No. 209, Tongshan Road, Xuzhou, 221004, Jiangsu, China
| | - Xia Zhu
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical College, No. 209, Tongshan Road, Xuzhou, 221004, Jiangsu, China
| | - Fan Zhang
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical College, No. 209, Tongshan Road, Xuzhou, 221004, Jiangsu, China
| | - Xiao-Xing Yin
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical College, No. 209, Tongshan Road, Xuzhou, 221004, Jiangsu, China.
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26
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Kim B, Feldman EL. Insulin resistance as a key link for the increased risk of cognitive impairment in the metabolic syndrome. Exp Mol Med 2015; 47:e149. [PMID: 25766618 PMCID: PMC4351418 DOI: 10.1038/emm.2015.3] [Citation(s) in RCA: 217] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 11/19/2014] [Indexed: 02/07/2023] Open
Abstract
Metabolic syndrome (MetS) is a cluster of cardiovascular risk factors that includes obesity, diabetes, and dyslipidemia. Accumulating evidence implies that MetS contributes to the development and progression of Alzheimer's disease (AD); however, the factors connecting this association have not been determined. Insulin resistance (IR) is at the core of MetS and likely represent the key link between MetS and AD. In the central nervous system, insulin plays key roles in learning and memory, and AD patients exhibit impaired insulin signaling that is similar to that observed in MetS. As we face an alarming increase in obesity and T2D in all age groups, understanding the relationship between MetS and AD is vital for the identification of potential therapeutic targets. Recently, several diabetes therapies that enhance insulin signaling are being tested for a potential therapeutic benefit in AD and dementia. In this review, we will discuss MetS as a risk factor for AD, focusing on IR and the recent progress and future directions of insulin-based therapies.
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Affiliation(s)
- Bhumsoo Kim
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Eva L Feldman
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
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27
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Abstract
Alzheimer's disease (AD) is characterized by cognitive impairment in clinical presentation, and by β-amyloid (Aβ) production and the hyper-phosphorylation of tau in basic research. More highlights demonstrate that the activation of the mammalian target of rapamycin (mTOR) enhances Aβ generation and deposition by modulating amyloid precursor protein (APP) metabolism and upregulating β- and γ-secretases. mTOR, an inhibitor of autophagy, decreases Aβ clearance by scissoring autophagy function. mTOR regulates Aβ generation or Aβ clearance by regulating several key signaling pathways, including phosphoinositide 3-kinase (PI3-K)/protein kinase B (Akt), glycogen synthase kinase 3 [GSK-3], AMP-activated protein kinase (AMPK), and insulin/insulin-like growth factor 1 (IGF-1). The activation of mTOR is also a contributor to aberrant hyperphosphorylated tau. Rapamycin, the inhibitor of mTOR, may mitigate cognitive impairment and inhibit the pathologies associated with amyloid plaques and neurofibrillary tangles by promoting autophagy. Furthermore, the upstream and downstream components of mTOR signaling are involved in the pathogenesis and progression of AD. Hence, inhibiting the activation of mTOR may be an important therapeutic target for AD.
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Affiliation(s)
- Zhiyou Cai
- Department of Neurology, Renmin Hospital, Hubei University of Medicine, Shiyan Renmin Hospital, Shiyan, Hubei Province, People's Republic of China
| | - Guanghui Chen
- Department of Neurology, Renmin Hospital, Hubei University of Medicine, Shiyan Renmin Hospital, Shiyan, Hubei Province, People's Republic of China
| | - Wenbo He
- Department of Neurology, Renmin Hospital, Hubei University of Medicine, Shiyan Renmin Hospital, Shiyan, Hubei Province, People's Republic of China
| | - Ming Xiao
- Department of Anatomy, Nanjing Medical University, Nanjing, Jiangsu, People's Republic of China
| | - Liang-Jun Yan
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, USA
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28
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Genetic reduction of mammalian target of rapamycin ameliorates Alzheimer's disease-like cognitive and pathological deficits by restoring hippocampal gene expression signature. J Neurosci 2014; 34:7988-98. [PMID: 24899720 DOI: 10.1523/jneurosci.0777-14.2014] [Citation(s) in RCA: 141] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Elevated mammalian target of rapamycin (mTOR) signaling has been found in Alzheimer's disease (AD) patients and is linked to diabetes and aging, two known risk factors for AD. However, whether hyperactive mTOR plays a role in the cognitive deficits associated with AD remains elusive. Here, we genetically reduced mTOR signaling in the brains of Tg2576 mice, a widely used animal model of AD. We found that suppression of mTOR signaling reduced amyloid-β deposits and rescued memory deficits. Mechanistically, the reduction in mTOR signaling led to an increase in autophagy induction and restored the hippocampal gene expression signature of the Tg2576 mice to wild-type levels. Our results implicate hyperactive mTOR signaling as a previous unidentified signaling pathway underlying gene-expression dysregulation and cognitive deficits in AD. Furthermore, hyperactive mTOR signaling may represent a molecular pathway by which aging contributes to the development of AD.
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29
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Liu F, Xue Z, Li N, Huang H, Ying Y, Li J, Wang L, Li W. Effects of lead exposure on the expression of amyloid β and phosphorylated tau proteins in the C57BL/6 mouse hippocampus at different life stages. J Trace Elem Med Biol 2014; 28:227-232. [PMID: 24582137 DOI: 10.1016/j.jtemb.2014.01.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Revised: 01/10/2014] [Accepted: 01/17/2014] [Indexed: 01/26/2023]
Abstract
The objective of this study was to investigate the effects of lead exposure on spatial learning and memory capacity and the expression of amyloid β and phosphorylated tau proteins in the mouse hippocampus. A total of 24 adult C57BL/6 mice (12 of each sex) were mated at a 1:1 ratio. After delivery, the litters were normalised to 6 pups per litter. During the lactation period, the pups were randomly separated into four groups: control, early exposure, late exposure, or long-term exposure. These groups were not exposed to lead, exposed to lead from birth to week 24, exposed to lead from week 24 to week 48, or exposed to lead from birth to 48 weeks of age, respectively. Lead exposure was induced by providing Pb-contaminated drinking water at a concentration of 0.1%. All of the pups were fed until 72 weeks of age, at which time their spatial learning and memory capacity was evaluated via the Morris water maze test. Then, the lead levels in their blood and hippocampus were measured via graphite furnace atomic absorption spectrometry. The protein expression of amyloid β and phosphorylated tau in the hippocampus was detected via Western blot. The results revealed that the hippocampal and blood lead levels were significantly higher in all of the groups exposed to lead than the control group (P<0.05). The spatial learning and memory performances of the lead-exposed groups were much poorer than those of the control group (P<0.05). The expression levels of amyloid β and phosphorylated tau proteins were increased in the lead-exposed groups compared to the control group (P<0.05). The enhanced expressions of amyloid β and phosphorylated tau proteins might contribute to the impairment in spatial learning and memory in the lead-exposed mice.
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Affiliation(s)
- Fangli Liu
- College of Public Health, Zhengzhou University, Zhengzhou 450001, China; Institute of Public Health, Henan University, Kaifeng 475004, China
| | - Zhenfei Xue
- College of Public Health, Zhengzhou University, Zhengzhou 450001, China
| | - Ning Li
- Food Science Technology College of Henan Agricultural University, Zhengzhou 450002, China
| | - Hui Huang
- College of Public Health, Zhengzhou University, Zhengzhou 450001, China
| | - Yanyan Ying
- College of Public Health, Zhengzhou University, Zhengzhou 450001, China
| | - Jin Li
- College of Public Health, Zhengzhou University, Zhengzhou 450001, China
| | - Lin Wang
- College of Public Health, Zhengzhou University, Zhengzhou 450001, China
| | - Wenjie Li
- College of Public Health, Zhengzhou University, Zhengzhou 450001, China.
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30
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Daulatzai MA. Neurotoxic Saboteurs: Straws that Break the Hippo’s (Hippocampus) Back Drive Cognitive Impairment and Alzheimer’s Disease. Neurotox Res 2013; 24:407-59. [DOI: 10.1007/s12640-013-9407-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 06/06/2013] [Accepted: 06/17/2013] [Indexed: 12/29/2022]
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31
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Insulin induces neurite outgrowth via SIRT1 in SH-SY5Y cells. Neuroscience 2013; 238:371-80. [PMID: 23357110 DOI: 10.1016/j.neuroscience.2013.01.034] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Revised: 01/05/2013] [Accepted: 01/07/2013] [Indexed: 01/24/2023]
Abstract
Insulin plays diverse roles, including learning and memory, in the central nervous system. SIRT1 has been reported to be involved in the processes of normal learning, memory, and synaptic plasticity. However, whether insulin is directly involved in regulating SIRT1 expression in neurons or whether it affects synapses remains largely unknown. Here, we show that insulin promotes neurite outgrowth and increases SIRT1 expression in SH-SY5Y cells. LY294002, a phosphatidylinositol 3-kinase inhibitor, inhibited the expression of insulin-induced increases in SIRT1. Conversely, the downregulation of SIRT1 using a SIRT1 inhibitor and SIRT1-siRNA resulted in a significant reduction in the length of neurite outgrowth. Taken together, these results suggest that the regulation of SIRT1 by insulin is important for the neurite outgrowth of neuroblastoma cells.
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