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Zhang SX, Wang JJ, Starr CR, Lee EJ, Park KS, Zhylkibayev A, Medina A, Lin JH, Gorbatyuk M. The endoplasmic reticulum: Homeostasis and crosstalk in retinal health and disease. Prog Retin Eye Res 2024; 98:101231. [PMID: 38092262 PMCID: PMC11056313 DOI: 10.1016/j.preteyeres.2023.101231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 12/05/2023] [Accepted: 12/06/2023] [Indexed: 12/19/2023]
Abstract
The endoplasmic reticulum (ER) is the largest intracellular organelle carrying out a broad range of important cellular functions including protein biosynthesis, folding, and trafficking, lipid and sterol biosynthesis, carbohydrate metabolism, and calcium storage and gated release. In addition, the ER makes close contact with multiple intracellular organelles such as mitochondria and the plasma membrane to actively regulate the biogenesis, remodeling, and function of these organelles. Therefore, maintaining a homeostatic and functional ER is critical for the survival and function of cells. This vital process is implemented through well-orchestrated signaling pathways of the unfolded protein response (UPR). The UPR is activated when misfolded or unfolded proteins accumulate in the ER, a condition known as ER stress, and functions to restore ER homeostasis thus promoting cell survival. However, prolonged activation or dysregulation of the UPR can lead to cell death and other detrimental events such as inflammation and oxidative stress; these processes are implicated in the pathogenesis of many human diseases including retinal disorders. In this review manuscript, we discuss the unique features of the ER and ER stress signaling in the retina and retinal neurons and describe recent advances in the research to uncover the role of ER stress signaling in neurodegenerative retinal diseases including age-related macular degeneration, inherited retinal degeneration, achromatopsia and cone diseases, and diabetic retinopathy. In some chapters, we highlight the complex interactions between the ER and other intracellular organelles focusing on mitochondria and illustrate how ER stress signaling regulates common cellular stress pathways such as autophagy. We also touch upon the integrated stress response in retinal degeneration and diabetic retinopathy. Finally, we provide an update on the current development of pharmacological agents targeting the UPR response and discuss some unresolved questions and knowledge gaps to be addressed by future research.
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Affiliation(s)
- Sarah X Zhang
- Department of Ophthalmology and Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States; Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States.
| | - Josh J Wang
- Department of Ophthalmology and Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States
| | - Christopher R Starr
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Eun-Jin Lee
- Department of Ophthalmology and Byers Eye Institute, Stanford University, Stanford, CA, United States; VA Palo Alto Healthcare System, Palo Alto, CA, United States; Department of Pathology, Stanford University, Stanford, CA, United States
| | - Karen Sophia Park
- Department of Ophthalmology and Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States
| | - Assylbek Zhylkibayev
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Andy Medina
- Department of Ophthalmology and Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States
| | - Jonathan H Lin
- Department of Ophthalmology and Byers Eye Institute, Stanford University, Stanford, CA, United States; VA Palo Alto Healthcare System, Palo Alto, CA, United States; Department of Pathology, Stanford University, Stanford, CA, United States
| | - Marina Gorbatyuk
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL, United States
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Saha D, Paul S, Gaharwar U, Priya A, Neog A, Singh A, Bk B. Cdk5-Mediated Brain Unfolded Protein Response Upregulation Associated with Cognitive Impairments in Type 2 Diabetes and Ameliorative Action of NAC. ACS Chem Neurosci 2023; 14:2761-2774. [PMID: 37468304 DOI: 10.1021/acschemneuro.3c00341] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/21/2023] Open
Abstract
The role of cyclin-dependent kinase 5 (Cdk5) in the normal functioning of the central nervous system and synaptic plasticity is well established. However, dysregulated kinase activity can have a significant impact on neurodegeneration and cognitive impairment. Cdk5 hyperactivation is linked to diabetes-associated neurodegeneration, but the underlying mechanism is not fully understood. Our study reveals that oxidative stress can lead to Cdk5 hyperactivity, which in turn is linked to neurodegeneration and cognitive impairment. Specifically, our experiments with N2A cells overexpressing Cdk5 and its activators p35 and p25 show ER stress, resulting in activation of the unfolded protein response (UPR) pathway. We identified Cdk5 as the epicenter of this regulatory process, leading to the activation of the CDK5-IRE1-XBP1 arm of UPR. Moreover, our study demonstrated that Cdk5 hyperactivation can lead to ER stress and activation of the UPR pathway, which may contribute to cognitive impairments associated with diabetes. Our findings also suggest that antioxidants such as NAC and GSH can decrease deregulated Cdk5 kinase activity and rescue cells from UPR-mediated ER stress. The accumulation of phosphorylated Tau protein in AD brain protein has been widely described earlier. Notably, we observed that oral treatment with NAC decreased Cdk5 kinase activity in the hippocampus, attenuated high levels of phospho-tau (ser396), and ameliorated memory and learning impairments in a type 2 diabetic (T2D) mouse model. Additionally, the high-fat-induced T2D model exhibits elevated phospho-tau levels, which are rescued by the NAC treatment. Taken together, these results suggest that targeting Cdk5 may be a promising therapeutic strategy for treating diabetes-associated cognitive impairments.
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Affiliation(s)
- Debarpita Saha
- CSIR Institute of Genomics and Integrative Biology, New Delhi 110025, India
| | - Sangita Paul
- CSIR Institute of Genomics and Integrative Biology, New Delhi 110025, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Utkarsh Gaharwar
- CSIR Institute of Genomics and Integrative Biology, New Delhi 110025, India
| | - Anshu Priya
- CSIR Institute of Genomics and Integrative Biology, New Delhi 110025, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Anindita Neog
- CSIR Institute of Genomics and Integrative Biology, New Delhi 110025, India
| | - Archana Singh
- CSIR Institute of Genomics and Integrative Biology, New Delhi 110025, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Binukumar Bk
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
- Principal Scientist, CSIR-Institute of Genomics and Integrative Biology (IGIB), New Delhi 110025, India
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Maly IV, Morales MJ, Pletnikov MV. Astrocyte Bioenergetics and Major Psychiatric Disorders. ADVANCES IN NEUROBIOLOGY 2021; 26:173-227. [PMID: 34888836 DOI: 10.1007/978-3-030-77375-5_9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Ongoing research continues to add new elements to the emerging picture of involvement of astrocyte energy metabolism in the pathophysiology of major psychiatric disorders, including schizophrenia, mood disorders, and addictions. This review outlines what is known about the energy metabolism in astrocytes, the most numerous cell type in the brain, and summarizes the recent work on how specific perturbations of astrocyte bioenergetics may contribute to the neuropsychiatric conditions. The role of astrocyte energy metabolism in mental health and disease is reviewed on the organism, organ, and cell level. Data arising from genomic, metabolomic, in vitro, and neurobehavioral studies is critically analyzed to suggest future directions in research and possible metabolism-focused therapeutic interventions.
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Affiliation(s)
- Ivan V Maly
- Department of Physiology and Biophysics, Jacobs School of Medicine and Biomedical Sciences, State University of New York, Buffalo, NY, USA
| | - Michael J Morales
- Department of Physiology and Biophysics, Jacobs School of Medicine and Biomedical Sciences, State University of New York, Buffalo, NY, USA
| | - Mikhail V Pletnikov
- Department of Physiology and Biophysics, Jacobs School of Medicine and Biomedical Sciences, State University of New York, Buffalo, NY, USA.
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Sovrani V, Bobermin LD, Schmitz I, Leipnitz G, Quincozes-Santos A. Potential Glioprotective Strategies Against Diabetes-Induced Brain Toxicity. Neurotox Res 2021; 39:1651-1664. [PMID: 34258694 DOI: 10.1007/s12640-021-00393-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 06/30/2021] [Accepted: 07/05/2021] [Indexed: 12/21/2022]
Abstract
Astrocytes are crucial for the maintenance of brain homeostasis by actively participating in the metabolism of glucose, which is the main energy substrate for the central nervous system (CNS), in addition to other supportive functions. More specifically, astrocytes support neurons through the metabolic coupling of synaptic activity and glucose utilization. As such, diabetes mellitus (DM) and consequent glucose metabolism disorders induce astrocyte damage, affecting CNS functionality. Glioprotective molecules can promote protection by improving glial functions and avoiding toxicity in different pathological conditions, including DM. Therefore, this review discusses specific pathomechanisms associated with DM/glucose metabolism disorder-induced gliotoxicity, namely astrocyte metabolism, redox homeostasis/mitochondrial activity, inflammation, and glial signaling pathways. Studies investigating natural products as potential glioprotective strategies against these deleterious effects of DM/glucose metabolism disorders are also reviewed herein. These products include carotenoids, catechins, isoflavones, lipoic acid, polysaccharides, resveratrol, and sulforaphane.
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Affiliation(s)
- Vanessa Sovrani
- Programa de Pós-Graduação Em Ciências Biológicas: Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal Do Rio Grande Do Sul, Porto Alegre, RS, Brazil
| | - Larissa Daniele Bobermin
- Programa de Pós-Graduação Em Ciências Biológicas: Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal Do Rio Grande Do Sul, Porto Alegre, RS, Brazil
| | - Izaviany Schmitz
- Programa de Pós-Graduação Em Ciências Biológicas: Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal Do Rio Grande Do Sul, Porto Alegre, RS, Brazil
| | - Guilhian Leipnitz
- Programa de Pós-Graduação Em Ciências Biológicas: Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal Do Rio Grande Do Sul, Porto Alegre, RS, Brazil.,Programa de Pós-Graduação Em Ciências Biológicas: Fisiologia, Instituto de Ciências Básicas da Saúde, Universidade Federal Do Rio Grande Do Sul, Porto Alegre, RS, Brazil.,Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal Do Rio Grande Do Sul, Rua Ramiro Barcelos, 2600 - Anexo, Bairro Santa Cecília, Porto Alegre, RS, 90035-003, Brazil
| | - André Quincozes-Santos
- Programa de Pós-Graduação Em Ciências Biológicas: Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal Do Rio Grande Do Sul, Porto Alegre, RS, Brazil. .,Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal Do Rio Grande Do Sul, Rua Ramiro Barcelos, 2600 - Anexo, Bairro Santa Cecília, Porto Alegre, RS, 90035-003, Brazil.
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Patrick AT, He W, Madu J, Sripathi SR, Choi S, Lee K, Samson FP, Powell FL, Bartoli M, Jee D, Gutsaeva DR, Jahng WJ. Mechanistic dissection of diabetic retinopathy using the protein-metabolite interactome. J Diabetes Metab Disord 2021; 19:829-848. [PMID: 33520806 DOI: 10.1007/s40200-020-00570-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 05/20/2020] [Accepted: 06/10/2020] [Indexed: 02/07/2023]
Abstract
Purpose The current study aims to determine the molecular mechanisms of diabetic retinopathy (DR) using the protein-protein interactome and metabolome map. We examined the protein network of novel biomarkers of DR for direct (physical) and indirect (functional) interactions using clinical target proteins in different models. Methods We used proteomic tools including 2-dimensional gel electrophoresis, mass spectrometry analysis, and database search for biomarker identification using in vivo murine and human model of diabetic retinopathy and in vitro model of oxidative stress. For the protein interactome and metabolome mapping, various bioinformatic tools that include STRING and OmicsNet were used. Results We uncovered new diabetic biomarkers including prohibitin (PHB), dynamin 1, microtubule-actin crosslinking factor 1, Toll-like receptor (TLR 7), complement activation, as well as hypothetical proteins that include a disintegrin and metalloproteinase (ADAM18), vimentin III, and calcium-binding C2 domain-containing phospholipid-binding switch (CAC2PBS) using a proteomic approach. Proteome networks of protein interactions with diabetic biomarkers were established using known DR-related proteome data. DR metabolites were interconnected to establish the metabolome map. Our results showed that mitochondrial protein interactions were changed during hyperglycemic conditions in the streptozotocin-treated murine model and diabetic human tissue. Conclusions Our interactome mapping suggests that mitochondrial dysfunction could be tightly linked to various phases of DR pathogenesis including altered visual cycle, cytoskeletal remodeling, altered lipid concentration, inflammation, PHB depletion, tubulin phosphorylation, and altered energy metabolism. The protein-metabolite interactions in the current network demonstrate the etiology of retinal degeneration and suggest the potential therapeutic approach to treat DR.
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Affiliation(s)
- Ambrose Teru Patrick
- Retina Proteomics Laboratory, Department of Petroleum Chemistry, American University of Nigeria, Yola, Nigeria
| | - Weilue He
- Department of Biomedical Engineering, Michigan Technological University, Houghton, MI USA
| | - Joshua Madu
- Retina Proteomics Laboratory, Department of Petroleum Chemistry, American University of Nigeria, Yola, Nigeria
| | - Srinivas R Sripathi
- Department of Ophthalmology, Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Seulggie Choi
- Division of Vitreous and Retina, Department of Ophthalmology, College of Medicine, St. Vincent's Hospital, The Catholic University of Korea, Suwon, Korea
| | - Kook Lee
- Division of Vitreous and Retina, Department of Ophthalmology, College of Medicine, St. Vincent's Hospital, The Catholic University of Korea, Suwon, Korea
| | - Faith Pwaniyibo Samson
- Retina Proteomics Laboratory, Department of Petroleum Chemistry, American University of Nigeria, Yola, Nigeria
| | - Folami L Powell
- Department of Biochemistry and Molecular Biology, Augusta University, Augusta, GA USA
| | - Manuela Bartoli
- Department of Ophthalmology, Augusta University, Augusta, GA USA
| | - Donghyun Jee
- Division of Vitreous and Retina, Department of Ophthalmology, College of Medicine, St. Vincent's Hospital, The Catholic University of Korea, Suwon, Korea
| | - Diana R Gutsaeva
- Department of Ophthalmology, Augusta University, Augusta, GA USA
| | - Wan Jin Jahng
- Retina Proteomics Laboratory, Department of Petroleum Chemistry, American University of Nigeria, Yola, Nigeria
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Weightman Potter PG, Washer SJ, Jeffries AR, Holley JE, Gutowski NJ, Dempster EL, Beall C. Attenuated Induction of the Unfolded Protein Response in Adult Human Primary Astrocytes in Response to Recurrent Low Glucose. Front Endocrinol (Lausanne) 2021; 12:671724. [PMID: 34122346 PMCID: PMC8187939 DOI: 10.3389/fendo.2021.671724] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 05/03/2021] [Indexed: 12/14/2022] Open
Abstract
AIMS/HYPOTHESIS Recurrent hypoglycaemia (RH) is a major side-effect of intensive insulin therapy for people with diabetes. Changes in hypoglycaemia sensing by the brain contribute to the development of impaired counterregulatory responses to and awareness of hypoglycaemia. Little is known about the intrinsic changes in human astrocytes in response to acute and recurrent low glucose (RLG) exposure. METHODS Human primary astrocytes (HPA) were exposed to zero, one, three or four bouts of low glucose (0.1 mmol/l) for three hours per day for four days to mimic RH. On the fourth day, DNA and RNA were collected. Differential gene expression and ontology analyses were performed using DESeq2 and GOseq, respectively. DNA methylation was assessed using the Infinium MethylationEPIC BeadChip platform. RESULTS 24 differentially expressed genes (DEGs) were detected (after correction for multiple comparisons). One bout of low glucose exposure had the largest effect on gene expression. Pathway analyses revealed that endoplasmic-reticulum (ER) stress-related genes such as HSPA5, XBP1, and MANF, involved in the unfolded protein response (UPR), were all significantly increased following low glucose (LG) exposure, which was diminished following RLG. There was little correlation between differentially methylated positions and changes in gene expression yet the number of bouts of LG exposure produced distinct methylation signatures. CONCLUSIONS/INTERPRETATION These data suggest that exposure of human astrocytes to transient LG triggers activation of genes involved in the UPR linked to endoplasmic reticulum (ER) stress. Following RLG, the activation of UPR related genes was diminished, suggesting attenuated ER stress. This may be a consequence of a successful metabolic adaptation, as previously reported, that better preserves intracellular energy levels and a reduced necessity for the UPR.
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Affiliation(s)
- Paul G. Weightman Potter
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Exeter, United Kingdom
| | - Sam J. Washer
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Exeter, United Kingdom
| | - Aaron R. Jeffries
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Exeter, United Kingdom
| | - Janet E. Holley
- Royal Devon and Exeter Hospital, University of Exeter Medical School and the Department of Neurology, Exeter, United Kingdom
| | - Nick J. Gutowski
- Royal Devon and Exeter Hospital, University of Exeter Medical School and the Department of Neurology, Exeter, United Kingdom
| | - Emma L. Dempster
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Exeter, United Kingdom
- *Correspondence: Emma L. Dempster, ; Craig Beall,
| | - Craig Beall
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Exeter, United Kingdom
- *Correspondence: Emma L. Dempster, ; Craig Beall,
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7
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Singh S. Updates on Versatile Role of Putative Gasotransmitter Nitric Oxide: Culprit in Neurodegenerative Disease Pathology. ACS Chem Neurosci 2020; 11:2407-2415. [PMID: 32564594 DOI: 10.1021/acschemneuro.0c00230] [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: 12/11/2022] Open
Abstract
Nitric oxide (NO) is a versatile gasotransmitter that contributes in a range of physiological and pathological mechanims depending on its cellular levels. An appropriate concentration of NO is essentially required for cellular physiology; however, its increased level triggers pathological mechanisms like altered cellular redox regulation, functional impairment of mitochondrion, and modifications in cellular proteins and DNA. Its increased levels also exhibit post-translational modifications in protein through S-nitrosylation of their thiol amino acids, which critically affect the cellular physiology. Along with such modifications, NO could also nitrosylate the endoplasmic reticulum (ER)-membrane located sensors of ER stress, which subsequently affect the cellular protein degradation capacity and lead to aggregation of misfolded/unfolded proteins. Since protein aggregation is one of the pathological hallmarks of neurodegenerative disease, NO should be taken into account during development of disease therapies. In this Review, we shed light on the diverse role of NO in both cellular physiology and pathology and discussed its involvement in various pathological events in the context of neurodegenerative diseases.
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Affiliation(s)
- Sarika Singh
- Department of Neurosciences and Ageing Biology and Division of Toxicology and Experimental Medicine, CSIR-Central Drug Research Institute, Lucknow, Uttar Pradesh 226031, India
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8
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He YX, Shen QY, Tian JH, Wu Q, Xue Q, Zhang GP, Wei W, Liu YH. Zonisamide Ameliorates Cognitive Impairment by Inhibiting ER Stress in a Mouse Model of Type 2 Diabetes Mellitus. Front Aging Neurosci 2020; 12:192. [PMID: 32754028 PMCID: PMC7367218 DOI: 10.3389/fnagi.2020.00192] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 06/02/2020] [Indexed: 01/08/2023] Open
Abstract
Type 2 diabetes mellitus (T2DM) increases the risk of Alzheimer’s disease (AD)-like dementia and pathology. Endoplasmic reticulum stress (ERS) plays a key role in the development of cognitive impairment in T2DM. Zonisamide (ZNS) was found to suppress ERS-induced neuronal cell damage in the experimental models of Parkinson’s disease (PD). However, the protective effect of Zonisamide in the treatment of diabetes-related dementia is not determined. Here, we studied whether ZNS can attenuate cognitive impairments in T2DM mice. C57BL/6J mice were fed with a high-fat diet (HFD) and received one intraperitoneal injection of streptozotocin (STZ) to develop T2DM. After the 9-week diet, the mice were orally gavaged with ZNS or vehicle for 16 consecutive weeks. We found that ZNS improved spatial learning and memory ability and slightly attenuated hyperglycemia. In addition, the expression levels of synaptic-related proteins, such as postsynaptic density 95 (PSD95) and synaptophysin, were increased along with the activation of the cyclic AMP response element-binding (CREB) protein and cAMP-dependent protein kinase (PKA) both in the hippocampus and cortex of T2DM mice. Meanwhile, ZNS attenuated Aβ deposition, Tau hyperphosphorylation at Ser-396/404, and also decreased the activity of Tau upstream kinases including extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK). Moreover, ZNS also decreased the ERS hallmark protein levels. These data suggest that ZNS can efficiently prevent cognitive impairment and improve AD-like pathologies by attenuating ERS in T2DM mice.
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Affiliation(s)
- Yong-Xiang He
- Department of Pharmacology, Key Laboratory of Molecular Target & Clinical Pharmacology, School of Pharmaceutical Sciences & the Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou, China
| | - Qi-Ying Shen
- Department of Pharmacology, Key Laboratory of Molecular Target & Clinical Pharmacology, School of Pharmaceutical Sciences & the Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou, China
| | - Jia-Hui Tian
- Department of Pharmacology, Key Laboratory of Molecular Target & Clinical Pharmacology, School of Pharmaceutical Sciences & the Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou, China
| | - Qian Wu
- Department of Pharmacology, Key Laboratory of Molecular Target & Clinical Pharmacology, School of Pharmaceutical Sciences & the Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou, China
| | - Qin Xue
- Department of Pharmacology, Key Laboratory of Molecular Target & Clinical Pharmacology, School of Pharmaceutical Sciences & the Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou, China
| | - Gui-Ping Zhang
- Department of Pharmacology, Key Laboratory of Molecular Target & Clinical Pharmacology, School of Pharmaceutical Sciences & the Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou, China
| | - Wei Wei
- Department of Pathophysiology, School of Medicine, Institute of Brain Research, Key Laboratory of State Administration of Traditional Chinese Medicine of China, Jinan University, Guangzhou, China
| | - Ying-Hua Liu
- Department of Pharmacology, Key Laboratory of Molecular Target & Clinical Pharmacology, School of Pharmaceutical Sciences & the Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou, China
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9
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Obafemi TO, Olasehinde OR, Olaoye OA, Jaiyesimi KF, Adewumi FD, Adewale OB, Afolabi BA. Metformin/Donepezil combination modulates brain antioxidant status and hippocampal endoplasmic reticulum stress in type 2 diabetic rats. J Diabetes Metab Disord 2020; 19:499-510. [PMID: 32550202 DOI: 10.1007/s40200-020-00541-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 04/26/2020] [Accepted: 05/06/2020] [Indexed: 02/07/2023]
Abstract
Purpose Diabetes mellitus is associated with perturbations in brain biochemical parameters associated with dementia. This study aimed at comparing the effect of metformin and metformin/donepezil combination on oxidative stress, endoplasmic reticulum stress and inflammation in the brain of diabetic Wistar rats. Methods Diabetes was induced by single intraperitoneal injection of 40 mg/kg streptozotocin after administration of 10% fructose for 14 days. Animals were randomly assigned to four groups of five animals each. Group 1 was the normal control and received only distilled water. Groups 2 and 3 were diabetic rats treated with metformin/donepezil combination and metformin only respectively, while group 4 was diabetic control. Treatment lasted for 21 days after confirmation of diabetes. Activities of acetylcholinesterase (AchE), butyrylcholinesterase (BchE), superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase were evaluated in the brain of diabetic rats. Enzyme-linked immunosorbent assay was used to estimate brain levels of tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6) malondialdehyde and glucose transporter-4 (GLUT4), while expression of endoplasmic reticulum stress markers - glucose regulated protein-78 (GRP78), activating transcription factor-4 (ATF4) and C/EBP homologous protein (CHOP) was determined using real-time PCR in the hippocampus of diabetic rats. Results Treatment with metformin/donepezil combination significantly reduced the activities of AchE, BchE as well as levels of malondialdehyde, TNF-α and IL-6, while the activities of SOD, GPx and catalase were significantly increased in the brain. Moreover, expression of ER stress markers was attenuated in the hippocampus. Conclusion Metformin/donepezil combination appeared more efficacious than metformin only and could be considered for managing diabetes-associated dementia.
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Affiliation(s)
- Tajudeen Olabisi Obafemi
- Biochemistry Programme, Department of Chemical Sciences, Afe Babalola University, Ado-Ekiti, PMB 5454 Nigeria
| | - Oluwaseun R Olasehinde
- Medical Biochemistry Unit, College of Health Sciences, Afe Babalola University, PMB 5454, Ado-Ekiti, Nigeria
| | - Oyindamola A Olaoye
- Biochemistry Programme, Department of Chemical Sciences, Afe Babalola University, Ado-Ekiti, PMB 5454 Nigeria
| | - Kikelomo F Jaiyesimi
- Biochemistry Programme, Department of Chemical Sciences, Afe Babalola University, Ado-Ekiti, PMB 5454 Nigeria
| | - Funmilayo D Adewumi
- Industrial Chemistry Programme, Department of Chemical Sciences, Afe Babalola University, Ado-Ekiti, PMB 5454 Nigeria
| | - Olusola B Adewale
- Biochemistry Programme, Department of Chemical Sciences, Afe Babalola University, Ado-Ekiti, PMB 5454 Nigeria
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10
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Docrat TF, Nagiah S, Naicker N, Baijnath S, Singh S, Chuturgoon AA. The protective effect of metformin on mitochondrial dysfunction and endoplasmic reticulum stress in diabetic mice brain. Eur J Pharmacol 2020; 875:173059. [PMID: 32131023 DOI: 10.1016/j.ejphar.2020.173059] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 02/23/2020] [Accepted: 02/28/2020] [Indexed: 12/26/2022]
Abstract
Diabetes is a metabolic disorder associated with mitochondrial (mt) dysfunction and oxidative stress. The molecular mechanisms involved in diabetes-associated neurological complications remain elusive. This study aims to investigate the protective effect of metformin (MF) on regulatory networks and integrated stress responses in brain tissue of Streptozotocin (STZ)-induced diabetic mice. STZ-induced diabetic mice were treated with MF (20 mg/kg BW), and whole brain tissue was harvested for further analysis. Protein carbonylation was measured as a marker of neuronal oxidative stress. Protein expression of mt chaperones, maintenance proteins, and regulators of the unfolded protein response (UPR) were measured by Western blot. Transcript levels of antioxidant enzyme GSTA4; mt biogenesis markers, ER stress regulators, and miR-132 and miR-148a were analysed using qPCR. The results showed that MF efficiently reduced protein carbonylation and oxidation. Mt function was improved by MF-treatment through upregulation of chaperone proteins (HSP60, HSP70 and LonP1). MF elicits the UPR to attenuate ER stress through a miR-132 repression mechanism. Additionally, MF was found to elevate deacetylases- Sirt1, Sirt3; and mt biogenesis marker PGC-1α through miR-148a repression. This is the first study to demonstrate the epigenetic regulation of mt maintenance by MF in diabetic C57BL/6 mouse whole brain tissue. We thus conclude that MF, beyond its anti-hyperglycaemic role, mediates neuroprotection through epigenomic and integrated stress responses in diabetic mice.
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Affiliation(s)
- Taskeen Fathima Docrat
- Discipline of Medical Biochemistry, School of Laboratory Medicine and Medical Sciences, College of Health Science, University of KwaZulu-Natal, South Africa
| | - Savania Nagiah
- Discipline of Medical Biochemistry, School of Laboratory Medicine and Medical Sciences, College of Health Science, University of KwaZulu-Natal, South Africa
| | - Nikita Naicker
- Discipline of Medical Biochemistry, School of Laboratory Medicine and Medical Sciences, College of Health Science, University of KwaZulu-Natal, South Africa
| | - Sooraj Baijnath
- Discipline of Medical Biochemistry, School of Laboratory Medicine and Medical Sciences, College of Health Science, University of KwaZulu-Natal, South Africa
| | - Sanil Singh
- Discipline of Medical Biochemistry, School of Laboratory Medicine and Medical Sciences, College of Health Science, University of KwaZulu-Natal, South Africa
| | - Anil A Chuturgoon
- Discipline of Medical Biochemistry, School of Laboratory Medicine and Medical Sciences, College of Health Science, University of KwaZulu-Natal, South Africa.
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11
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Chen Z, Guo H, Lu Z, Sun K, Jin Q. Hyperglycemia aggravates spinal cord injury through endoplasmic reticulum stress mediated neuronal apoptosis, gliosis and activation. Biomed Pharmacother 2019; 112:108672. [PMID: 30784940 DOI: 10.1016/j.biopha.2019.108672] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 01/29/2019] [Accepted: 02/05/2019] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Hyperglycemia has been shown to influence prognostic outcome of spinal cord injury (SCI). However, the corresponding mechanism is not very clear. AIM This study is expected to explore the role of endoplasmic reticulum (ER) stress in hyperglycemia aggravated SCI. METHODS Hyperglycemia was established in rats by intraperitoneal (i.p.) injection of streptozotocin. SCI was performed at the T10 of spinal cord through weight dropping. ER stress was suppressed by oral gavage of 4-PBA. ER stress, histological change of the injured spinal cords, neuronal apoptosis, demyelination, glial proliferation, inflammatory factor production, blood-spinal cord barrier (BSCB) permeability, TJ (Occludin, Claudin5) and AJ (β-catenin, P120) protein degradation, and locomotor recovery were determined using western blotting, immunohistochemistry, HE staining, Evan's Blue assay, BBB scores and inclined plane test, respectively. In vitro, rat spinal cord neurons cells (RSCNCs) and cerebral microvascular endothelial cells (RCMECs) were stimulated with high glucose (HG) and/or thapsigargin (TG). The effects of HG and/or TG on RSCNCs apoptosis, and AJ and TJ expression by RCMECs were evaluated with flow cytometry and western blotting, respectively. RESULTS Hyperglycemic rats exhibited enhanced ER stress, increased neuronal apoptosis, aggravated demyelination, increased glial proliferation and inflammatory factors secretion, more serious BSCB disruption and disturbed locomotor recovery. ER stress inhibition alleviated hyperglycemia induced adverse effect on neuronal apoptosis and BSCB permeability, whereas showed little influence on glial activation and inflammation. CONCLUSION ER stress was aggravated in hyperglycemic rats after SCI, and subsequently promoted neuronal apoptosis and BSCB disruption in rats.
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Affiliation(s)
- Zhirong Chen
- Department of Orthopedics, General Hospital of Ningxia Medical University, Yinchuan, 750004, Ningxia, China
| | - Haohui Guo
- Department of Orthopedics, General Hospital of Ningxia Medical University, Yinchuan, 750004, Ningxia, China
| | - Zhidong Lu
- Department of Orthopedics, General Hospital of Ningxia Medical University, Yinchuan, 750004, Ningxia, China
| | - Kening Sun
- Department of Orthopedics, General Hospital of Ningxia Medical University, Yinchuan, 750004, Ningxia, China
| | - Qunhua Jin
- Department of Orthopedics, General Hospital of Ningxia Medical University, Yinchuan, 750004, Ningxia, China.
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12
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Abstract
Glucose is the long-established, obligatory fuel for brain that fulfills many critical functions, including ATP production, oxidative stress management, and synthesis of neurotransmitters, neuromodulators, and structural components. Neuronal glucose oxidation exceeds that in astrocytes, but both rates increase in direct proportion to excitatory neurotransmission; signaling and metabolism are closely coupled at the local level. Exact details of neuron-astrocyte glutamate-glutamine cycling remain to be established, and the specific roles of glucose and lactate in the cellular energetics of these processes are debated. Glycolysis is preferentially upregulated during brain activation even though oxygen availability is sufficient (aerobic glycolysis). Three major pathways, glycolysis, pentose phosphate shunt, and glycogen turnover, contribute to utilization of glucose in excess of oxygen, and adrenergic regulation of aerobic glycolysis draws attention to astrocytic metabolism, particularly glycogen turnover, which has a high impact on the oxygen-carbohydrate mismatch. Aerobic glycolysis is proposed to be predominant in young children and specific brain regions, but re-evaluation of data is necessary. Shuttling of glucose- and glycogen-derived lactate from astrocytes to neurons during activation, neurotransmission, and memory consolidation are controversial topics for which alternative mechanisms are proposed. Nutritional therapy and vagus nerve stimulation are translational bridges from metabolism to clinical treatment of diverse brain disorders.
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Affiliation(s)
- Gerald A Dienel
- Department of Neurology, University of Arkansas for Medical Sciences , Little Rock, Arkansas ; and Department of Cell Biology and Physiology, University of New Mexico , Albuquerque, New Mexico
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13
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Guo T, Dakkak D, Rodriguez-Martin T, Noble W, Hanger DP. A pathogenic tau fragment compromises microtubules, disrupts insulin signaling and induces the unfolded protein response. Acta Neuropathol Commun 2019; 7:2. [PMID: 30606258 PMCID: PMC6318896 DOI: 10.1186/s40478-018-0651-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Accepted: 12/13/2018] [Indexed: 12/02/2022] Open
Abstract
Human tauopathies including Alzheimer’s disease, progressive supranuclear palsy and related disorders, are characterized by deposition of pathological forms of tau, synaptic dysfunction and neuronal loss. We have previously identified a pathogenic C-terminal tau fragment (Tau35) that is associated with human tauopathy. However, it is not known how tau fragmentation affects critical molecular processes in cells and contributes to impaired physiological function. Chinese hamster ovary (CHO) cells and new CHO cell lines stably expressing Tau35 or full-length human tau were used to compare the effects of disease-associated tau cleavage on tau function and signaling pathways. Western blots, microtubule-binding assays and immunofluorescence labeling were used to examine the effects of Tau35 on tau function and on signaling pathways in CHO cells. We show that Tau35 undergoes aberrant phosphorylation when expressed in cells. Although Tau35 contain the entire microtubule-binding region, the lack of the amino terminal half of tau results in a marked reduction in microtubule binding and defective microtubule organization in cells. Notably, Tau35 attenuates insulin-mediated activation of Akt and a selective inhibitory phosphorylation of glycogen synthase kinase-3. Moreover, Tau35 activates ribosomal protein S6 kinase beta-1 signaling and the unfolded protein response, leading to insulin resistance in cells. Tau35 has deleterious effects on signaling pathways that mediate pathological changes and insulin resistance, suggesting a mechanism through which N-terminal cleavage of tau leads to the development and progression of tau pathology in human tauopathy. Our findings highlight the importance of the N-terminal region of tau for its normal physiological function. Furthermore, we show that pathogenic tau cleavage induces tau phosphorylation, resulting in impaired microtubule binding, disruption of insulin signaling and activation of the unfolded protein response. Since insulin resistance is a feature of several tauopathies, this work suggests new potential targets for therapeutic intervention.
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14
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Liu W, Yang T, Xu Z, Xu B, Deng Y. Methyl-mercury induces apoptosis through ROS-mediated endoplasmic reticulum stress and mitochondrial apoptosis pathways activation in rat cortical neurons. Free Radic Res 2018; 53:26-44. [DOI: 10.1080/10715762.2018.1546852] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Wei Liu
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, People’s Republic of China
| | - Tianyao Yang
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, People’s Republic of China
| | - Zhaofa Xu
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, People’s Republic of China
| | - Bin Xu
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, People’s Republic of China
| | - Yu Deng
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, People’s Republic of China
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15
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Ruebsam A, Dulle JE, Myers AM, Sakrikar D, Green KM, Khan NW, Schey K, Fort PE. A specific phosphorylation regulates the protective role of αA-crystallin in diabetes. JCI Insight 2018; 3:97919. [PMID: 29467334 DOI: 10.1172/jci.insight.97919] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Accepted: 01/17/2018] [Indexed: 12/19/2022] Open
Abstract
Neurodegeneration is a central aspect of the early stages of diabetic retinopathy, the primary ocular complication associated with diabetes. While progress has been made to improve the vascular perturbations associated with diabetic retinopathy, there are still no treatment options to counteract the neuroretinal degeneration associated with diabetes. Our previous work suggested that the molecular chaperones α-crystallins could be involved in the pathophysiology of diabetic retinopathy; however, the role and regulation of α-crystallins remained unknown. In the present study, we demonstrated the neuroprotective role of αA-crystallin during diabetes and its regulation by its phosphorylation on residue 148. We further characterized the dual role of αA-crystallin in neurons and glia, its essential role for neuronal survival, and its direct dependence on phosphorylation on this residue. These findings support further evaluation of αA-crystallin as a treatment option to promote neuron survival in diabetic retinopathy and neurodegenerative diseases in general.
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Affiliation(s)
- Anne Ruebsam
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan, USA
| | - Jennifer E Dulle
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan, USA
| | - Angela M Myers
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan, USA
| | | | - Katelyn M Green
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan, USA
| | - Naheed W Khan
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan, USA
| | - Kevin Schey
- Department of Biochemistry and Ophthalmology and Visual Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Patrice E Fort
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan, USA.,Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, USA
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16
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Song Y, Zhang F, Ying C, Kumar KA, Zhou X. Inhibition of NF-κB activity by aminoguanidine alleviates neuroinflammation induced by hyperglycemia. Metab Brain Dis 2017. [PMID: 28634786 DOI: 10.1007/s11011-017-0013-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Neuroinflammation is a key feature of cerebral complication which is associated with diabetes mellitus (DM). Inducible nitric oxide synthase (iNOS) is implicated in the pathogenesis of neuroinflammation. However, how iNOS facilitates the development of inflammation in brain is still unidentified. The aim of the present study was to investigate the association of iNOS and neuroinflammation in diabetic mice, and elucidate the potential mechanisms underlying aminoguanidine (AG), the selective inhibitor of iNOS, protected neurons against inflammation in diabetic mice. In present experiment, diabetic mice model were established by a single intraperitoneal injection of streptozotocin (STZ). AG was administered to diabetic mice for ten weeks after this disease induction. Then we measured iNOS activity in the serum and brain, detected the glial fibrillary acidic protein (GFAP) and ionised calcium binding adaptor molecule-1 (Iba-1) expressions in the brain. Moreover, nuclear factor-kappa B (NF-κB) in cytoplasm and nucleus were tested by IP and WB. Results revealed that high expression of iNOS in serum and brain could be reversed by AG treatment. Furthermore, AG could also inhibit GFAP and Iba-1 expressions, and NF-κB nuclear translocation by inhibiting it from binding to iNOS in cytoplasm. Our findings indicated that iNOS can combine with NF-κB in cytoplasm and promote its nuclear transfer in diabetic mice. Furthermore, AG decreased neuroinflammation through inhibiting iNOS activity and reducing NF-κB nuclear translocation by promoting its dissociation with iNOS in cytoplasm.
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Affiliation(s)
- Yuanjian Song
- Department of Genetics, Research Facility Center for Morphology, Xuzhou Medical University, Xuzhou, Jiangsu, 221004, People's Republic of China
| | - Fang Zhang
- Department of Genetics, Research Facility Center for Morphology, Xuzhou Medical University, Xuzhou, Jiangsu, 221004, People's Republic of China
| | - Changjiang Ying
- Department of Endocrinology, Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, 221002, People's Republic of China
| | - Kiran Ashok Kumar
- Department of Clinical Medicine, Xuzhou Medical University, Xuzhou, Jiangsu, 221004, People's Republic of China
| | - Xiaoyan Zhou
- Jiangsu Key Laboratory of Brain Disease Bioinformation, Xuzhou Medical University, Xuzhou, Jiangsu, 221004, People's Republic of China.
- Laboratory of Morphology, Xuzhou Medical University, 209 Tongshan Road, Xuzhou, Jiangsu, 221004, People's Republic of China.
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17
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Li S, Zhu A, Zhu T, Zhang JZH, Tian Y. Single Biosensor for Simultaneous Quantification of Glucose and pH in a Rat Brain of Diabetic Model Using Both Current and Potential Outputs. Anal Chem 2017; 89:6656-6662. [DOI: 10.1021/acs.analchem.7b00881] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Shuai Li
- Shanghai Key Laboratory of
Green Chemistry and Chemical Processes, School of Chemistry and Molecular
Engineering, East China Normal University, Dongchuan Road 500, Shanghai 200241, People’s Republic of China
| | - Anwei Zhu
- Shanghai Key Laboratory of
Green Chemistry and Chemical Processes, School of Chemistry and Molecular
Engineering, East China Normal University, Dongchuan Road 500, Shanghai 200241, People’s Republic of China
| | - Tong Zhu
- Shanghai Key Laboratory of
Green Chemistry and Chemical Processes, School of Chemistry and Molecular
Engineering, East China Normal University, Dongchuan Road 500, Shanghai 200241, People’s Republic of China
| | - John Z. H. Zhang
- Shanghai Key Laboratory of
Green Chemistry and Chemical Processes, School of Chemistry and Molecular
Engineering, East China Normal University, Dongchuan Road 500, Shanghai 200241, People’s Republic of China
| | - Yang Tian
- Shanghai Key Laboratory of
Green Chemistry and Chemical Processes, School of Chemistry and Molecular
Engineering, East China Normal University, Dongchuan Road 500, Shanghai 200241, People’s Republic of China
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18
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Godin JD, Creppe C, Laguesse S, Nguyen L. Emerging Roles for the Unfolded Protein Response in the Developing Nervous System. Trends Neurosci 2016; 39:394-404. [PMID: 27130659 DOI: 10.1016/j.tins.2016.04.002] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Revised: 03/23/2016] [Accepted: 04/04/2016] [Indexed: 01/04/2023]
Abstract
The unfolded protein response (UPR) is a homeostatic signaling pathway triggered by protein misfolding in the endoplasmic reticulum (ER). Beyond its protective role, it plays important functions during normal development in response to elevated demand for protein folding. Several UPR effectors show dynamic temporal and spatial expression patterns that correlate with milestones of the central nervous system (CNS) development. Here, we discuss recent studies suggesting that a dynamic regulation of UPR supports generation, maturation, and maintenance of differentiated neurons in the CNS. We further highlight studies supporting a developmental vulnerability of CNS to UPR dysregulation, which underlies neurodevelopmental disorders. We believe that a better understanding of UPR functions may provide novel opportunities for therapeutic strategies to fight ER/UPR-associated human neurological disorders.
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Affiliation(s)
- Juliette D Godin
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, Illkirch, France.
| | - Catherine Creppe
- GIGA-Neurosciences, University of Liège, C.H.U. Sart Tilman, Liège 4000, Belgium; Interdisciplinary Cluster for Applied Genoproteomics (GIGA-R), University of Liège, C.H.U. Sart Tilman, Liège 4000, Belgium
| | - Sophie Laguesse
- GIGA-Neurosciences, University of Liège, C.H.U. Sart Tilman, Liège 4000, Belgium; Interdisciplinary Cluster for Applied Genoproteomics (GIGA-R), University of Liège, C.H.U. Sart Tilman, Liège 4000, Belgium
| | - Laurent Nguyen
- GIGA-Neurosciences, University of Liège, C.H.U. Sart Tilman, Liège 4000, Belgium; Interdisciplinary Cluster for Applied Genoproteomics (GIGA-R), University of Liège, C.H.U. Sart Tilman, Liège 4000, Belgium; Walloon Excellence in Lifesciences and Biotechnology (WELBIO), University of Liège, C.H.U. Sart Tilman, Liège 4000, Belgium.
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19
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Sun Y, Zhang T, Li L, Wang J. Induction of apoptosis by hypertension via endoplasmic reticulum stress. Kidney Blood Press Res 2016; 40:41-51. [PMID: 25791362 DOI: 10.1159/000368481] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/15/2015] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS Endoplasmic reticulum (ER) stress is one of the intrinsic apoptosis pathways, and cardiac apoptosis can occur in cardiovascular diseases, such as hypertension. However, the mechanisms by which ER stress leads to apoptosis remain enigmatic, particularly in the progression from cardiac hypertrophy to diastolic heart failure due to hypertension. METHODS We used spontaneously hypertensive rats (SHRs) to investigate possible signalling pathways for ER stress. RESULTS We found that cardiac protein and mRNA levels of glucoseregulated protein 78 were up-regulated. In addition, the CHOP- and caspase-12-dependent pathways, but not that of JNK, were activated in the SHR rats. CONCLUSIONS These results suggest that ER stress can contribute to myocardial apoptosis during hypertensive disease.
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20
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Lactate Transport and Receptor Actions in Retina: Potential Roles in Retinal Function and Disease. Neurochem Res 2015; 41:1229-36. [PMID: 26677077 DOI: 10.1007/s11064-015-1792-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Revised: 11/06/2015] [Accepted: 11/08/2015] [Indexed: 01/01/2023]
Abstract
In retina, like in brain, lactate equilibrates across cell membranes via monocarboxylate transporters and in the extracellular space by diffusion, forming a basis for the action of lactate as a transmitter of metabolic signals. In the present paper, we argue that the lactate receptor GPR81, also known as HCAR1, may contribute importantly to the control of retinal cell functions in health and disease. GPR81, a G-protein coupled receptor, is known to downregulate cAMP both in adipose and nervous tissue. The receptor also acts through other down-stream mechanisms to control functions, such as excitability, metabolism and inflammation. Recent publications predict effects of the lactate receptor on neurodegeneration. Neurodegenerative diseases in retina, where the retinal ganglion cells die, notably glaucoma and diabetic retinopathy, may be linked to disturbed lactate homeostasis. Pilot studies reveal high GPR81 mRNA in retina and indicate GPR81 localization in Müller cells and retinal ganglion cells. Moreover, monocarboxylate transporters are expressed in retinal cells. We envision that lactate receptors and transporters could be useful future targets of novel therapeutic strategies to protect neurons and prevent or counteract glaucoma as well as other retinal diseases.
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21
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Determination of Glucose Utilization Rates in Cultured Astrocytes and Neurons with [ 14C]deoxyglucose: Progress, Pitfalls, and Discovery of Intracellular Glucose Compartmentation. Neurochem Res 2015; 42:50-63. [PMID: 26141225 DOI: 10.1007/s11064-015-1650-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Revised: 06/12/2015] [Accepted: 06/20/2015] [Indexed: 01/08/2023]
Abstract
2-Deoxy-D-[14C]glucose ([14C]DG) is commonly used to determine local glucose utilization rates (CMRglc) in living brain and to estimate CMRglc in cultured brain cells as rates of [14C]DG phosphorylation. Phosphorylation rates of [14C]DG and its metabolizable fluorescent analog, 2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose (2-NBDG), however, do not take into account differences in the kinetics of transport and metabolism of [14C]DG or 2-NBDG and glucose in neuronal and astrocytic cells in cultures or in single cells in brain tissue, and conclusions drawn from these data may, therefore, not be correct. As a first step toward the goal of quantitative determination of CMRglc in astrocytes and neurons in cultures, the steady-state intracellular-to-extracellular concentration ratios (distribution spaces) for glucose and [14C]DG were determined in cultured striatal neurons and astrocytes as functions of extracellular glucose concentration. Unexpectedly, the glucose distribution spaces rose during extreme hypoglycemia, exceeding 1.0 in astrocytes, whereas the [14C]DG distribution space fell at the lowest glucose levels. Calculated CMRglc was greatly overestimated in hypoglycemic and normoglycemic cells because the intracellular glucose concentrations were too high. Determination of the distribution space for [14C]glucose revealed compartmentation of intracellular glucose in astrocytes, and probably, also in neurons. A smaller metabolic pool is readily accessible to hexokinase and communicates with extracellular glucose, whereas the larger pool is sequestered from hexokinase activity. A new experimental approach using double-labeled assays with DG and glucose is suggested to avoid the limitations imposed by glucose compartmentation on metabolic assays.
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22
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Dienel GA. The metabolic trinity, glucose-glycogen-lactate, links astrocytes and neurons in brain energetics, signaling, memory, and gene expression. Neurosci Lett 2015; 637:18-25. [PMID: 25725168 DOI: 10.1016/j.neulet.2015.02.052] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Accepted: 02/23/2015] [Indexed: 10/23/2022]
Abstract
Glucose, glycogen, and lactate are traditionally identified with brain energetics, ATP turnover, and pathophysiology. However, recent studies extend their roles to include involvement in astrocytic signaling, memory consolidation, and gene expression. Emerging roles for these brain fuels and a readily-diffusible by-product are linked to differential fluxes in glycolytic and oxidative pathways, astrocytic glycogen dynamics, redox shifts, neuron-astrocyte interactions, and regulation of astrocytic activities by noradrenaline released from the locus coeruleus. Disproportionate utilization of carbohydrate compared with oxygen during brain activation is influenced by catecholamines, but its physiological basis is not understood and its magnitude may be affected by technical aspects of metabolite assays. Memory consolidation and gene expression are impaired by glycogenolysis blockade, and prevention of these deficits by injection of abnormally-high concentrations of lactate was interpreted as a requirement for astrocyte-to-neuron lactate shuttling in memory and gene expression. However, lactate transport was not measured and evidence for presumed shuttling is not compelling. In fact, high levels of lactate used to preserve memory consolidation and induce gene expression are sufficient to shut down neuronal firing via the HCAR1 receptor. In contrast, low lactate levels activate a receptor in locus coeruleus that stimulates noradrenaline release that may activate astrocytes throughout brain. Physiological relevance of exogenous concentrations of lactate used to mimic and evaluate metabolic, molecular, and behavioral effects of lactate requires close correspondence with the normal lactate levels, the biochemical and cellular sources and sinks, and specificity of lactate delivery to target cells.
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Affiliation(s)
- Gerald A Dienel
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
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23
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Shin ES, Sorenson CM, Sheibani N. Diabetes and retinal vascular dysfunction. J Ophthalmic Vis Res 2015; 9:362-73. [PMID: 25667739 PMCID: PMC4307665 DOI: 10.4103/2008-322x.143378] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2013] [Accepted: 01/19/2014] [Indexed: 02/06/2023] Open
Abstract
Diabetes predominantly affects the microvascular circulation of the retina resulting in a range of structural changes unique to this tissue. These changes ultimately lead to altered permeability, hyperproliferation of endothelial cells and edema, and abnormal vascularization of the retina with resulting loss of vision. Enhanced production of inflammatory mediators and oxidative stress are primary insults with significant contribution to the pathogenesis of diabetic retinopathy (DR). We have determined the identity of the retinal vascular cells affected by hyperglycemia, and have delineated the cell autonomous impact of high glucose on function of these cells. We discuss some of the high glucose specific changes in retinal vascular cells and their contribution to retinal vascular dysfunction. This knowledge provides novel insight into the molecular and cellular defects contributing to the development and progression of diabetic retinopathy, and will aid in the development of innovative, as well as target specific therapeutic approaches for prevention and treatment of DR.
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Affiliation(s)
- Eui Seok Shin
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Christine M Sorenson
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA ; McPherson Eye Research Institute, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Nader Sheibani
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA ; McPherson Eye Research Institute, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
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24
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Wang Y, Jiang ZZ, Chen M, Wu MJ, Guo HL, Sun LX, Wang H, Zhang S, Wang T, Zhang LY. Protective effect of total flavonoid C-glycosides from Abrus mollis extract on lipopolysaccharide-induced lipotoxicity in mice. Chin J Nat Med 2015; 12:461-8. [PMID: 24969528 DOI: 10.1016/s1875-5364(14)60072-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Indexed: 01/16/2023]
Abstract
Abrus mollis is a widely used traditional Chinese medicine for treating acute and chronic hepatitis, steatosis, and fibrosis. It was found that the total flavonoid C-glycosides from Abrus mollis extract (AME) showed potent antioxidant, anti-inflammatory, and hepatoprotective activities. To further investigate the hepatoprotective effect of AME and its possible mechanisms, lipopolysaccharide (LPS)-induced liver injury models were applied in the current study. The results indicated that AME significantly attenuated LPS-induced lipid accumulation in mouse primary hepatocytes as measured by triglyceride (TG) and total cholesterol (TC) assays and Oil Red O staining. Meanwhile, AME exerted a protective effect on LPS-induced liver injury as shown by decreased liver index, serum aminotransferase levels, and hepatic lipid accumulation. Real-time PCR and immunoblot data suggested that AME reversed the LPS-mediated lipid metabolism gene expression, such as sterol regulatory element-binding protein-1 (SREBP-1), fatty acid synthase (FAS), and acetyl-CoA carboxylase 1 (ACC1). In addition, LPS-induced overexpression of activating transcription factor 4 (ATF4), X-box-binding protein-1 (XBP-1), and C/EBP homologous protein (CHOP) were dramatically reversed by AME. Furthermore, AME also decreased the expression of LPS-enhanced interleukin-6 (IL-6) and cyclooxygenase-2 (COX-2). Here, it is demonstrated for the first time that AME ameliorated LPS-induced hepatic lipid accumulation and that this effect of AME can be attributed to its modulation of hepatic de novo fatty acid synthesis. This study also suggested that the hepatoprotective effect of AME may be related to its down-regulation of unfolded protein response (UPR) activation.
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Affiliation(s)
- Yun Wang
- Jiangsu Center for Drug Screening, China Pharmaceutical University, Nanjing 210009, China
| | - Zhen-Zhou Jiang
- Jiangsu Center for Drug Screening, China Pharmaceutical University, Nanjing 210009, China; Key Laboratory of Drug Quality Control and Pharmacovigilance, China Pharmaceutical University, Nanjing 210009, China
| | - Mi Chen
- Jiangsu Center for Drug Screening, China Pharmaceutical University, Nanjing 210009, China
| | - Mei-Juan Wu
- Jiangsu Center for Drug Screening, China Pharmaceutical University, Nanjing 210009, China
| | - Hong-Li Guo
- Jiangsu Center for Drug Screening, China Pharmaceutical University, Nanjing 210009, China
| | - Li-Xin Sun
- Jiangsu Center for Drug Screening, China Pharmaceutical University, Nanjing 210009, China
| | - Hao Wang
- Department of Natural Medicinal Chemistry, China Pharmaceutical University, Nanjing 210009, China
| | - Shuang Zhang
- Jiangsu Center for Drug Screening, China Pharmaceutical University, Nanjing 210009, China
| | - Tao Wang
- Jiangsu Center for Drug Screening, China Pharmaceutical University, Nanjing 210009, China; Jiangsu Center for Pharmacodynamics Research and Evaluation, China Pharmaceutical University, Nanjing 21009, China
| | - Lu-Yong Zhang
- Jiangsu Center for Drug Screening, China Pharmaceutical University, Nanjing 210009, China; State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009, China.
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Alpha-Synuclein Oligomerization in Manganese-Induced Nerve Cell Injury in Brain Slices: A Role of NO-Mediated S-Nitrosylation of Protein Disulfide Isomerase. Mol Neurobiol 2014; 50:1098-110. [DOI: 10.1007/s12035-014-8711-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 04/09/2014] [Indexed: 12/14/2022]
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26
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Ortiz MDC, Lores-Arnaiz S, Albertoni Borghese MF, Balonga S, Lavagna A, Filipuzzi AL, Cicerchia D, Majowicz M, Bustamante J. Mitochondrial dysfunction in brain cortex mitochondria of STZ-diabetic rats: effect of l-Arginine. Neurochem Res 2013; 38:2570-80. [PMID: 24190597 DOI: 10.1007/s11064-013-1172-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Revised: 09/27/2013] [Accepted: 10/03/2013] [Indexed: 12/27/2022]
Abstract
Mitochondrial dysfunction has been implicated in many diseases, including diabetes. It is well known that oxygen free radical species are produced endogenously by mitochondria, and also nitric oxide (NO) by nitric oxide synthases (NOS) associated to mitochondrial membranes, in consequence these organelles constitute main targets for oxidative damage. The aim of this study was to analyze mitochondrial physiology and NO production in brain cortex mitochondria of streptozotocin (STZ) diabetic rats in an early stage of diabetes and the potential effect of L-arginine administration. The diabetic condition was characterized by a clear hyperglycaemic state with loose of body weight after 4 days of STZ injection. This hyperglycaemic state was associated with mitochondrial dysfunction that was evident by an impairment of the respiratory activity, increased production of superoxide anion and a clear mitochondrial depolarization. In addition, the alteration in mitochondrial physiology was associated with a significant decrease in both NO production and nitric oxide synthase type I (NOS I) expression associated to the mitochondrial membranes. An increased level of thiobarbituric acid-reactive substances (TBARS) in brain cortex homogenates from STZ-diabetic rats indicated the presence of lipid peroxidation. L-arginine treatment to diabetic rats did not change blood glucose levels but significantly ameliorated the oxidative stress evidenced by lower TBARS and a lower level of superoxide anion. This effect was paralleled by improvement of mitochondrial respiratory function and a partial mitochondrial repolarization.In addition, the administration of L-arginine to diabetic rats prevented the decrease in NO production and NOSI expression. These results could indicate that exogenously administered L-arginine may have beneficial effects on mitochondrial function, oxidative stress and NO production in brain cortex mitochondria of STZ-diabetic rats.
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Affiliation(s)
- M Del Carmen Ortiz
- Cátedra de Biología Celular y Molecular, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, C1113AAD, Buenos Aires, Argentina
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27
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Endoplasmic reticulum stress signaling involvement in manganese-induced nerve cell damage in organotypic brain slice cultures. Toxicol Lett 2013; 222:239-46. [DOI: 10.1016/j.toxlet.2013.08.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Revised: 07/31/2013] [Accepted: 08/03/2013] [Indexed: 12/17/2022]
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28
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Wong DPK, Chu JMT, Hung VKL, Lee DKM, Cheng CHK, Yung KKL, Yue KKM. Modulation of endoplasmic reticulum chaperone GRP78 by high glucose in hippocampus of streptozotocin-induced diabetic mice and C6 astrocytic cells. Neurochem Int 2013; 63:551-60. [PMID: 24056253 DOI: 10.1016/j.neuint.2013.09.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Revised: 09/09/2013] [Accepted: 09/12/2013] [Indexed: 12/15/2022]
Abstract
Diabetes mellitus is known to increase the risk of neurodegeneration, and both diseases are reported to be linked to dysfunction of endoplasmic reticulum (ER). Astrocytes are important in the defense mechanism of central nervous system (CNS), with great ability of tolerating accumulation of toxic substances and sensitivity in Ca(2+) homeostasis which are two key functions of ER. Here, we investigated the modulation of the glucose-regulated protein 78 (GRP78) in streptozotocin (STZ)-induced diabetic mice and C6 cells cultured in high glucose condition. Our results showed that more reactive astrocytes were presented in the hippocampus of STZ-induced diabetic mice. Simultaneously, decrease of GRP78 expression was found in the astrocytes of diabetic mice hippocampus. In in vitro study, C6 cells were treated with high glucose to investigate the role of high glucose in GRP78 modulation in astrocytic cells. GRP78 as well as other chaperones like GRP94, calreticulin and calnexin, transcription levels were down-regulated after high glucose treatment. Also C6 cells challenged with 48h high glucose were activated, as indicated by increased level of glial fibrillary acidic protein (GFAP). Activated C6 cells simultaneously exhibited significant decrease of GRP78 level and was followed by reduced phosphorylation of Akt. Moreover, unfolded protein response was induced as an early event, which was marked by the induction of CHOP with high glucose treatment, followed by the reduction of GRP78 after 48h. Finally, the upsurge of ROS production was found in high glucose treated C6 cells and chelation of ROS could partially restore the GRP78 expression. Taken together, these data provide evidences that high glucose induced astrocytic activation in both in vivo and in vitro diabetic models, in which modulation of GRP78 would be an important event in this activation.
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Affiliation(s)
| | - John M T Chu
- School of Chinese Medicine, Hong Kong Baptist University, Hong Kong; Department of Biology, Hong Kong Baptist University, Hong Kong
| | - Victor K L Hung
- Department of Anaestheiology, The University of Hong Kong, Hong Kong
| | - Dicky K M Lee
- School of Chinese Medicine, Hong Kong Baptist University, Hong Kong
| | | | - Ken K L Yung
- Department of Biology, Hong Kong Baptist University, Hong Kong
| | - Kevin K M Yue
- School of Chinese Medicine, Hong Kong Baptist University, Hong Kong.
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29
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Tucker BA, Mullins RF, Streb LM, Anfinson K, Eyestone ME, Kaalberg E, Riker MJ, Drack AV, Braun TA, Stone EM. Patient-specific iPSC-derived photoreceptor precursor cells as a means to investigate retinitis pigmentosa. eLife 2013; 2:e00824. [PMID: 23991284 PMCID: PMC3755341 DOI: 10.7554/elife.00824] [Citation(s) in RCA: 149] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Accepted: 07/24/2013] [Indexed: 12/11/2022] Open
Abstract
Next-generation and Sanger sequencing were combined to identify disease-causing USH2A mutations in an adult patient with autosomal recessive RP. Induced pluripotent stem cells (iPSCs), generated from the patient's keratinocytes, were differentiated into multi-layer eyecup-like structures with features of human retinal precursor cells. The inner layer of the eyecups contained photoreceptor precursor cells that expressed photoreceptor markers and exhibited axonemes and basal bodies characteristic of outer segments. Analysis of the USH2A transcripts of these cells revealed that one of the patient's mutations causes exonification of intron 40, a translation frameshift and a premature stop codon. Western blotting revealed upregulation of GRP78 and GRP94, suggesting that the patient's other USH2A variant (Arg4192His) causes disease through protein misfolding and ER stress. Transplantation into 4-day-old immunodeficient Crb1 (-/-) mice resulted in the formation of morphologically and immunohistochemically recognizable photoreceptor cells, suggesting that the mutations in this patient act via post-developmental photoreceptor degeneration. DOI:http://dx.doi.org/10.7554/eLife.00824.001.
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Affiliation(s)
- Budd A Tucker
- Department of Ophthalmology and Visual Sciences, University of Iowa Carver College of Medicine, Iowa City, United States
| | - Robert F Mullins
- Department of Ophthalmology and Visual Sciences, University of Iowa Carver College of Medicine, Iowa City, United States
| | - Luan M Streb
- Department of Ophthalmology and Visual Sciences, University of Iowa Carver College of Medicine, Iowa City, United States
| | - Kristin Anfinson
- Department of Ophthalmology and Visual Sciences, University of Iowa Carver College of Medicine, Iowa City, United States
| | - Mari E Eyestone
- Department of Ophthalmology and Visual Sciences, University of Iowa Carver College of Medicine, Iowa City, United States
| | - Emily Kaalberg
- Department of Ophthalmology and Visual Sciences, University of Iowa Carver College of Medicine, Iowa City, United States
| | - Megan J Riker
- Department of Ophthalmology and Visual Sciences, University of Iowa Carver College of Medicine, Iowa City, United States
| | - Arlene V Drack
- Department of Ophthalmology and Visual Sciences, University of Iowa Carver College of Medicine, Iowa City, United States
| | - Terry A Braun
- Department of Ophthalmology and Visual Sciences, University of Iowa Carver College of Medicine, Iowa City, United States
- Department of Biomedical Engineering, University of Iowa Carver College of Medicine, Iowa City, United States
| | - Edwin M Stone
- Department of Ophthalmology and Visual Sciences, University of Iowa Carver College of Medicine, Iowa City, United States
- Howard Hughes Medical Institute, University of Iowa, Iowa City, United States
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30
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Xu B, Wang F, Wu SW, Deng Y, Liu W, Feng S, Yang TY, Xu ZF. α-Synuclein is involved in manganese-induced ER stress via PERK signal pathway in organotypic brain slice cultures. Mol Neurobiol 2013; 49:399-412. [PMID: 23934647 DOI: 10.1007/s12035-013-8527-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2013] [Accepted: 07/31/2013] [Indexed: 12/30/2022]
Abstract
Overexposure to manganese (Mn) has been known to induce neuronal damage involving endoplasmic reticulum (ER) stress. However, the exact mechanism of Mn-induced ER stress is unclear. Increasing evidence suggested that the overexpression of alpha-synuclein played a critical role in Mn-induced neurotoxicity. To explore whether the occurrence of ER stress was associated with alpha-synuclein overexpression, we made the rat brain slices model of silencing alpha-synuclein using short-interference RNA. After non-silencing alpha-synuclein slices were treated with Mn (0-400 μM) for 24 h, there was a dose-dependent increase in apoptotic rates of cells and levels of lactate dehydrogenase in the culture medium. Moreover, there was a dose-dependent increase in the protein expression of 78, 94-kDa glucose-regulated protein (GRP78/94), C/EBP homologous protein (CHOP), and caspase-12. Moreover, PKR-like ER kinase (PERK) phosphorylation, PERK-mediated phosphorylation of eIF2a, and ATF4 expression also increased. Inositol-requiring enzyme 1 (IRE1) activation and X-box-binding protein-1 (Xbp1) mRNA splicing increased. Activating transcription factor 6 p90 levels did not change. However, after silencing alpha-synuclein slices were treated with 400 μM Mn for 24 h, there was a significant decrease in the expression of GRP78/94, CHOP, and caspase-12 compared with 400 μM Mn-treated non-silencing alpha-synuclein slices. Furthermore, PERK phosphorylation, PERK-mediated phosphorylation of eIF2a, and ATF4 mRNA expression also decreased. However, IRE1 phosphorylation and Xbp1 mRNA splicing did not change. The findings revealed that Mn induced ER stress via activation of PERK and IRE1 signaling pathways and subsequent apoptosis in cultured slices. Moreover, alpha-synuclein protein was associated with Mn-induced activation of PERK signaling pathway.
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Affiliation(s)
- Bin Xu
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, Liaoning, 110001, People's Republic of China,
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Astrocytic energetics during excitatory neurotransmission: What are contributions of glutamate oxidation and glycolysis? Neurochem Int 2013; 63:244-58. [PMID: 23838211 DOI: 10.1016/j.neuint.2013.06.015] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 06/19/2013] [Accepted: 06/24/2013] [Indexed: 12/23/2022]
Abstract
Astrocytic energetics of excitatory neurotransmission is controversial due to discrepant findings in different experimental systems in vitro and in vivo. The energy requirements of glutamate uptake are believed by some researchers to be satisfied by glycolysis coupled with shuttling of lactate to neurons for oxidation. However, astrocytes increase glycogenolysis and oxidative metabolism during sensory stimulation in vivo, indicating that other sources of energy are used by astrocytes during brain activation. Furthermore, glutamate uptake into cultured astrocytes stimulates glutamate oxidation and oxygen consumption, and glutamate maintains respiration as well as glucose. The neurotransmitter pool of glutamate is associated with the faster component of total glutamate turnover in vivo, and use of neurotransmitter glutamate to fuel its own uptake by oxidation-competent perisynaptic processes has two advantages, substrate is supplied concomitant with demand, and glutamate spares glucose for use by neurons and astrocytes. Some, but not all, perisynaptic processes of astrocytes in adult rodent brain contain mitochondria, and oxidation of only a small fraction of the neurotransmitter glutamate taken up into these structures would be sufficient to supply the ATP required for sodium extrusion and conversion of glutamate to glutamine. Glycolysis would, however, be required in perisynaptic processes lacking oxidative capacity. Three lines of evidence indicate that critical cornerstones of the astrocyte-to-neuron lactate shuttle model are not established and normal brain does not need lactate as supplemental fuel: (i) rapid onset of hemodynamic responses to activation delivers oxygen and glucose in excess of demand, (ii) total glucose utilization greatly exceeds glucose oxidation in awake rodents during activation, indicating that the lactate generated is released, not locally oxidized, and (iii) glutamate-induced glycolysis is not a robust phenotype of all astrocyte cultures. Various metabolic pathways, including glutamate oxidation and glycolysis with lactate release, contribute to cellular energy demands of excitatory neurotransmission.
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