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Cao B, Xia Y, Cai Z, Wang Z, Tang C, Song Y. Construction of a Brain-specific SLC23A2 Gene Knockout Mice Model. Neuroscience 2023; 524:137-148. [PMID: 37330196 DOI: 10.1016/j.neuroscience.2023.05.023] [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] [Received: 03/09/2023] [Revised: 05/05/2023] [Accepted: 05/27/2023] [Indexed: 06/19/2023]
Abstract
Vitamin C (VC) is a key antioxidant of the Central Nervous System (CNS) and SLC23A2 (SVCT2) is the only transporter that actively transports VC into the brain. While the existing animal models of VC deficiency are in the whole body, the essential role of VC in brain development remains elusive. In our study presented here, the CRISPR/Cas9 technology was applied for the construction of a C57BL/6J-SLC23A2 em1(flox)Smoc mouse model, which was crossed with the Glial fibrillary acidic protein-driven Cre Recombinase (GFAP-Cre) genotype mice to generate a conditional knockout model of SLC23A2(SVCT2) gene in mice brain (GFAP-Cre;SLC23A2 flox/flox) after generations of crossbreeding. Our results showed that the expression of SVCT2 in GFAP-Cre;SLC23A2 flox/flox (Cre;svct2 f/f) mice brain was significantly decreased, and consistently, the expression of Neuronal nuclei antigen (NeuN), Glial fibrillary acidic protein (GFAP), calbindin-28k, brain-derived neurotrophic factor (BDNF) was down-regulated but Ionized calcium binding adapter molecule 1 (Iba-1) was up-regulated in Cre;svct2 f/f mice brain tissues. On the other hand, the levels of Glutathione, Reduced (GSH), myeloperoxidase (MDA), 8-isoprostane, tumor necrosis factor-α (TNF-α) and interleukin-6(IL-6) were significantly increased, but the levels of VC in brain tissue of the model group were decreased in Cre;svct2 f/f mice brain tissues, indicating the protective effect of VC against oxidative stress and inflammation during pregnancy. Thus, the conditional knockout of the SLC23A2 gene in the brain of mouse was successfully established by the CRISPR/Cas9 technology in our study, providing an effective animal model for studying the role of VC in fetal brain development.
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Affiliation(s)
- Bin Cao
- Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, China
| | - Yong Xia
- Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, China
| | - Zengxuan Cai
- Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, China
| | - Ziyu Wang
- Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, China
| | - Chao Tang
- National Clinical Research Center for Child Health of the Children's Hospital, Zhejiang University School of Medicine, Hangzhou, China.
| | - Yanhua Song
- Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, China.
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Ascorbate Is a Primary Antioxidant in Mammals. Molecules 2022; 27:molecules27196187. [PMID: 36234722 PMCID: PMC9572970 DOI: 10.3390/molecules27196187] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 09/18/2022] [Accepted: 09/19/2022] [Indexed: 11/19/2022] Open
Abstract
Ascorbate (vitamin C in primates) functions as a cofactor for a number of enzymatic reactions represented by prolyl hydroxylases and as an antioxidant due to its ability to donate electrons, which is mostly accomplished through non-enzymatic reaction in mammals. Ascorbate directly reacts with radical species and is converted to ascorbyl radical followed by dehydroascorbate. Ambiguities in physiological relevance of ascorbate observed during in vivo situations could be attributed in part to presence of other redox systems and the pro-oxidant properties of ascorbate. Most mammals are able to synthesize ascorbate from glucose, which is also considered to be an obstacle to verify its action. In addition to animals with natural deficiency in the ascorbate synthesis, such as guinea pigs and ODS rats, three strains of mice with genetic removal of the responsive genes (GULO, RGN, or AKR1A) for the ascorbate synthesis have been established and are being used to investigate the physiological roles of ascorbate. Studies using these mice, along with ascorbate transporter (SVCT)-deficient mice, largely support its ability in protection against oxidative insults. While combined actions of ascorbate in regulating epigenetics and antioxidation appear to effectively prevent cancer development, pharmacological doses of ascorbate and dehydroascorbate may exert tumoricidal activity through redox-dependent mechanisms.
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Shu Y, Zou C, Cai Y, He Q, Wu X, Zhu H, Qv M, Chao Y, Xu C, Tang L, Wu X. Vitamin C deficiency induces hypoglycemia and cognitive disorder through S-nitrosylation-mediated activation of glycogen synthase kinase 3β. Redox Biol 2022; 56:102420. [PMID: 35969998 PMCID: PMC9399387 DOI: 10.1016/j.redox.2022.102420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 07/21/2022] [Indexed: 11/15/2022] Open
Abstract
Vitamin C (VC, l-ascorbic acid) is an essential nutrient that plays a key role in metabolism and functions as a potent antioxidant in regulating the S-nitrosylation and denitrosylation of target proteins. The precise function of VC deprivation in glucose homeostasis is still unknown. In the absence of L-gulono-1,4-lactone oxidoreductase, an essential enzyme for the last step of VC synthesis, VC deprivation resulted in persistent hypoglycemia and subsequent impairment of cognitive functions in female but not male mouse pups. The cognitive disorders caused by VC deprivation were largely reversed when these female pups were given glucose. VC deprivation-induced S-nitrosylation of glycogen synthase kinase 3β (GSK3β) at Cys14, which activated GSK3β and inactivated glycogen synthase to decrease glycogen synthesis and storage under the feeding condition, while VC deprivation inactivated glycogen phosphorylase to decrease glycogenolysis under the fasting condition, ultimately leading to hypoglycemia and cognitive disorders. Treatment with Nω-Nitro-l-arginine methyl ester (l-NAME), a specific inhibitor of nitric oxide synthase, on the other hand, effectively prevented S-nitrosylation and activation of GSK3β in female pups in response to the VC deprivation and reversed hypoglycemia and cognitive disorders. Overall, this research identifies S-nitrosylation of GSK3β and subsequent GSK3β activation as a previously unknown mechanism controlling glucose homeostasis in female pups in response to VC deprivation, implying that VC supplementation in the prevention of hypoglycemia and cognitive disorders should be considered in the certain groups of people, particularly young females.
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Affiliation(s)
- Yingying Shu
- Department of Endocrinology, The Children's Hospital of Zhejiang University School of Medicine, Hangzhou, 310053, China; National Clinical Research Center for Child Health, The Children's Hospital of Zhejiang University School of Medicine, Hangzhou, 310053, China
| | - Chaochun Zou
- Department of Endocrinology, The Children's Hospital of Zhejiang University School of Medicine, Hangzhou, 310053, China; National Clinical Research Center for Child Health, The Children's Hospital of Zhejiang University School of Medicine, Hangzhou, 310053, China.
| | - Yuqing Cai
- Department of Endocrinology, The Children's Hospital of Zhejiang University School of Medicine, Hangzhou, 310053, China; National Clinical Research Center for Child Health, The Children's Hospital of Zhejiang University School of Medicine, Hangzhou, 310053, China
| | - Qiangqiang He
- Department of Pharmacology, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Xiaowei Wu
- Department of Obstetrics and Gynecology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310003, China
| | - Haibin Zhu
- Department of Obstetrics and Gynecology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310003, China
| | - Meiyu Qv
- Department of Pharmacology, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Yunqi Chao
- Department of Endocrinology, The Children's Hospital of Zhejiang University School of Medicine, Hangzhou, 310053, China; National Clinical Research Center for Child Health, The Children's Hospital of Zhejiang University School of Medicine, Hangzhou, 310053, China
| | - Chengyun Xu
- National Clinical Research Center for Child Health, The Children's Hospital of Zhejiang University School of Medicine, Hangzhou, 310053, China; Department of Pharmacology, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Lanfang Tang
- National Clinical Research Center for Child Health, The Children's Hospital of Zhejiang University School of Medicine, Hangzhou, 310053, China
| | - Ximei Wu
- Department of Pharmacology, Zhejiang University School of Medicine, Hangzhou, 310058, China.
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Wang D, Yang X, Chen Y, Gong K, Yu M, Gao Y, Wu X, Hu H, Liao C, Han J, Duan Y. Ascorbic acid enhances low-density lipoprotein receptor expression by suppressing proprotein convertase subtilisin/kexin 9 expression. J Biol Chem 2020; 295:15870-15882. [PMID: 32913121 DOI: 10.1074/jbc.ra120.015623] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 09/04/2020] [Indexed: 01/30/2023] Open
Abstract
Ascorbic acid, a water-soluble antioxidant, regulates various biological processes and is thought to influence cholesterol. However, little is known about the mechanisms underpinning ascorbic acid-mediated cholesterol metabolism. Here, we determined if ascorbic acid can regulate expression of proprotein convertase subtilisin/kexin 9 (PCSK9), which binds low-density lipoprotein receptor (LDLR) leading to its intracellular degradation, to influence low-density lipoprotein (LDL) metabolism. At cellular levels, ascorbic acid inhibited PCSK9 expression in HepG2 and Huh7 cell lines. Consequently, LDLR expression and cellular LDL uptake were enhanced. Similar effects of ascorbic acid on PCSK9 and LDLR expression were observed in mouse primary hepatocytes. Mechanistically, ascorbic acid suppressed PCSK9 expression in a forkhead box O3-dependent manner. In addition, ascorbic acid increased LDLR transcription by regulating sterol regulatory element-binding protein 2. In vivo, administration of ascorbic acid reduced serum PCSK9 levels and enhanced liver LDLR expression in C57BL/6J mice. Reciprocally, lack of ascorbic acid supplementation in L-gulono-γ-lactone oxidase deficient (Gulo -/-) mice increased circulating PCSK9 and LDL levels, and decreased liver LDLR expression, whereas ascorbic acid supplementation decreased PCSK9 and increased LDLR expression, ameliorating LDL levels in Gulo -/- mice fed a high fat diet. Moreover, ascorbic acid levels were negatively correlated to PCSK9, total and LDL levels in human serum samples. Taken together, these findings suggest that ascorbic acid reduces PCSK9 expression, leading to increased LDLR expression and cellular LDL uptake. Thus, supplementation of ascorbic acid may ameliorate lipid profiles in ascorbic acid-deficient species.
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Affiliation(s)
- Dandan Wang
- Key Laboratory of Metabolism and Regulation for Major Diseases of Anhui Higher Education Institutes, School of Food and Biological Engineering, Hefei University of Technology, Hefei, China
| | - Xiaoxiao Yang
- Key Laboratory of Metabolism and Regulation for Major Diseases of Anhui Higher Education Institutes, School of Food and Biological Engineering, Hefei University of Technology, Hefei, China
| | - Yuanli Chen
- Key Laboratory of Metabolism and Regulation for Major Diseases of Anhui Higher Education Institutes, School of Food and Biological Engineering, Hefei University of Technology, Hefei, China
| | - Ke Gong
- Key Laboratory of Metabolism and Regulation for Major Diseases of Anhui Higher Education Institutes, School of Food and Biological Engineering, Hefei University of Technology, Hefei, China
| | - Maoyun Yu
- School of Biological and Pharmaceutical Engineering, West Anhui University, Lu'An, China
| | - Yongyao Gao
- Key Laboratory of Metabolism and Regulation for Major Diseases of Anhui Higher Education Institutes, School of Food and Biological Engineering, Hefei University of Technology, Hefei, China
| | - Ximei Wu
- School of Medicine, Zhejiang University, Hangzhou, China
| | - Huaqing Hu
- First Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Chenzhong Liao
- Key Laboratory of Metabolism and Regulation for Major Diseases of Anhui Higher Education Institutes, School of Food and Biological Engineering, Hefei University of Technology, Hefei, China
| | - Jihong Han
- Key Laboratory of Metabolism and Regulation for Major Diseases of Anhui Higher Education Institutes, School of Food and Biological Engineering, Hefei University of Technology, Hefei, China; College of Life Sciences, State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Bioactive Materials of Ministry of Education, Nankai University, Tianjin, China.
| | - Yajun Duan
- Key Laboratory of Metabolism and Regulation for Major Diseases of Anhui Higher Education Institutes, School of Food and Biological Engineering, Hefei University of Technology, Hefei, China.
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Ciebiera M, Ali M, Zgliczyńska M, Skrzypczak M, Al-Hendy A. Vitamins and Uterine Fibroids: Current Data on Pathophysiology and Possible Clinical Relevance. Int J Mol Sci 2020; 21:ijms21155528. [PMID: 32752274 PMCID: PMC7432695 DOI: 10.3390/ijms21155528] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 07/27/2020] [Accepted: 07/30/2020] [Indexed: 01/27/2023] Open
Abstract
Uterine fibroid (UF) is the most common benign tumor pathology of the female reproductive organs. UFs constitute the main reason for a hysterectomy and hospitalization due to gynecological conditions. UFs consist of uterine smooth muscle immersed in a large amount of extracellular matrix (ECM). Genetic studies have demonstrated that UFs are monoclonal tumors originating from the myometrial stem cells that have underwent specific molecular changes to tumor initiating stem cells which proliferate and differentiate later under the influence of steroid hormones. There is growing interest in the role of micronutrients, for example, vitamins, in UFs. This article is a comprehensive review of publications regarding the available data concerning the role of vitamins in the biology and management of UFs. In summary, the results showed that some vitamins are important in the biology and pathophysiology of UFs. For example, vitamins A and D deserve particular attention following studies of their influence on the treatment of UF tumors. Vitamins B3, C, and E have not been as widely studied as the abovementioned vitamins. However, more research could reveal their potential role in UF biology.
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Affiliation(s)
- Michał Ciebiera
- Second Department of Obstetrics and Gynecology, The Center of Postgraduate Medical Education, 01-809 Warsaw, Poland;
- Department of Surgery, University of Illinois at Chicago, Chicago, IL 60612, USA;
- Correspondence: (M.C.); (A.A.-H.); Tel.: +48-225690274 (M.C.); +1-312-996-7006 (A.A.-H.)
| | - Mohamed Ali
- Department of Surgery, University of Illinois at Chicago, Chicago, IL 60612, USA;
- Clinical Pharmacy Department, Faculty of Pharmacy, Ain Shams University, 11566 Cairo, Egypt
| | - Magdalena Zgliczyńska
- Second Department of Obstetrics and Gynecology, The Center of Postgraduate Medical Education, 01-809 Warsaw, Poland;
| | - Maciej Skrzypczak
- Second Department of Gynecology, Medical University of Lublin, 20-954 Lublin, Poland;
| | - Ayman Al-Hendy
- Department of Surgery, University of Illinois at Chicago, Chicago, IL 60612, USA;
- Correspondence: (M.C.); (A.A.-H.); Tel.: +48-225690274 (M.C.); +1-312-996-7006 (A.A.-H.)
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Chen J, Wu J, Kong D, Yang C, Yu H, Pan Q, Liu W, Ding Y, Liu H. The Effect of Antioxidant Vitamins on Patients With Diabetes and Albuminuria: A Meta-Analysis of Randomized Controlled Trials. J Ren Nutr 2019; 30:101-110. [PMID: 31466888 DOI: 10.1053/j.jrn.2019.06.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 06/22/2019] [Accepted: 06/29/2019] [Indexed: 12/21/2022] Open
Abstract
OBJECTIVE This study aimed to investigate the effect of antioxidant vitamins, including vitamins E and C, on patients with diabetes and albuminuria by conducting a meta-analysis of randomized controlled trials. DESIGN The PubMed, Embase, CENTRAL (the Cochrane Central Register of Controlled Trials at the Cochrane Library), Web of Science, OVID, and www.clinicaltrials.gov (latest search: December 10, 2018) databases were searched. This study was limited to randomized controlled trials. Patients with diabetes and albuminuria were included regardless of diabetic type, and patients must have received treatment with vitamins C or E. RESULTS Ten studies, representing 445 participants, were identified for analysis. Antioxidant vitamins had significant effects on serum creatinine levels (mean difference = -0.11 mg/dL, 95% confidence interval -0.19 to -0.03, P = .007) and systolic pressure (mean difference = -6.02 mm Hg, 95% confidence interval -9.65 to -2.40, P = .001) with low heterogeneity. Antioxidant vitamins had no effect on albuminuria or proteinuria, diastolic blood pressure, glucose, or lipid metabolism. CONCLUSION This meta-analysis indicated that antioxidant vitamins can benefit kidney function and systolic blood pressure in patients with diabetes and albuminuria. Further studies with larger sample sizes and longer follow-up are needed to completely understand the effect of antioxidant vitamins in these patients.
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Affiliation(s)
- Jinxia Chen
- Key Laboratory of Prevention and Management of Chronic Kidney Disease of Zhanjiang City, Affiliated Hospital of Guangdong Medical University, Zhanjiang, People's Republic of China
| | - Jiayuan Wu
- Department of Clinical Research, Affiliated Hospital of Guangdong Medical University, Zhanjiang, People's Republic of China
| | - Danli Kong
- Department of Epidemiology and Medical Statistics, Guangdong Medical University, Zhanjiang, People's Republic of China
| | - Chen Yang
- Key Laboratory of Prevention and Management of Chronic Kidney Disease of Zhanjiang City, Affiliated Hospital of Guangdong Medical University, Zhanjiang, People's Republic of China
| | - Haibing Yu
- Department of Epidemiology and Medical Statistics, Guangdong Medical University, Dongguan, People's Republic of China
| | - Qingjun Pan
- Key Laboratory of Prevention and Management of Chronic Kidney Disease of Zhanjiang City, Affiliated Hospital of Guangdong Medical University, Zhanjiang, People's Republic of China
| | - Weijing Liu
- Key Laboratory of Chinese Internal Medicine of Ministry of Education and Beijing, Dongzhimen Hospital Affiliated to Beijing University of Chinese Medicine, Beijing, People's Republic of China
| | - Yuanlin Ding
- Department of Epidemiology and Medical Statistics, Guangdong Medical University, Dongguan, People's Republic of China.
| | - Huafeng Liu
- Key Laboratory of Prevention and Management of Chronic Kidney Disease of Zhanjiang City, Affiliated Hospital of Guangdong Medical University, Zhanjiang, People's Republic of China.
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Tecalco-Cruz AC, Ríos-López DG, Vázquez-Victorio G, Rosales-Alvarez RE, Macías-Silva M. Transcriptional cofactors Ski and SnoN are major regulators of the TGF-β/Smad signaling pathway in health and disease. Signal Transduct Target Ther 2018; 3:15. [PMID: 29892481 PMCID: PMC5992185 DOI: 10.1038/s41392-018-0015-8] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Revised: 02/16/2018] [Accepted: 03/15/2018] [Indexed: 12/19/2022] Open
Abstract
The transforming growth factor-β (TGF-β) family plays major pleiotropic roles by regulating many physiological processes in development and tissue homeostasis. The TGF-β signaling pathway outcome relies on the control of the spatial and temporal expression of >500 genes, which depend on the functions of the Smad protein along with those of diverse modulators of this signaling pathway, such as transcriptional factors and cofactors. Ski (Sloan-Kettering Institute) and SnoN (Ski novel) are Smad-interacting proteins that negatively regulate the TGF-β signaling pathway by disrupting the formation of R-Smad/Smad4 complexes, as well as by inhibiting Smad association with the p300/CBP coactivators. The Ski and SnoN transcriptional cofactors recruit diverse corepressors and histone deacetylases to repress gene transcription. The TGF-β/Smad pathway and coregulators Ski and SnoN clearly regulate each other through several positive and negative feedback mechanisms. Thus, these cross-regulatory processes finely modify the TGF-β signaling outcome as they control the magnitude and duration of the TGF-β signals. As a result, any alteration in these regulatory mechanisms may lead to disease development. Therefore, the design of targeted therapies to exert tight control of the levels of negative modulators of the TGF-β pathway, such as Ski and SnoN, is critical to restore cell homeostasis under the specific pathological conditions in which these cofactors are deregulated, such as fibrosis and cancer. Proteins that repress molecular signaling through the transforming growth factor-beta (TGF-β) pathway offer promising targets for treating cancer and fibrosis. Marina Macías-Silva and colleagues from the National Autonomous University of Mexico in Mexico City review the ways in which a pair of proteins, called Ski and SnoN, interact with downstream mediators of TGF-β to inhibit the effects of this master growth factor. Aberrant levels of Ski and SnoN have been linked to diverse range of diseases involving cell proliferation run amok, and therapies that regulate the expression of these proteins could help normalize TGF-β signaling to healthier physiological levels. For decades, drug companies have tried to target the TGF-β pathway, with limited success. Altering the activity of these repressors instead could provide a roundabout way of remedying pathogenic TGF-β activity in fibrosis and oncology.
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Affiliation(s)
- Angeles C Tecalco-Cruz
- 1Instituto de Investigaciones Biomédicas at Universidad Nacional Autónoma de México, Mexico city, 04510 Mexico
| | - Diana G Ríos-López
- 2Instituto de Fisiología Celular at Universidad Nacional Autónoma de México, Mexico city, 04510 Mexico
| | | | - Reyna E Rosales-Alvarez
- 2Instituto de Fisiología Celular at Universidad Nacional Autónoma de México, Mexico city, 04510 Mexico
| | - Marina Macías-Silva
- 2Instituto de Fisiología Celular at Universidad Nacional Autónoma de México, Mexico city, 04510 Mexico
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Qing Z, Xiao-Hui W, Xi-Mei W, Chao-Chun Z. Vitamin C deficiency aggravates tumor necrosis factor α-induced insulin resistance. Eur J Pharmacol 2018; 829:1-11. [PMID: 29625084 DOI: 10.1016/j.ejphar.2018.03.044] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 03/26/2018] [Accepted: 03/29/2018] [Indexed: 02/06/2023]
Abstract
Chronic low-grade inflammation plays a major role in the development of insulin resistance. The potential role and underlying mechanism of vitamin C, an antioxidant and anti-inflammatory agent, was investigated in tumor necrosis factor-α (TNF-α)-induced insulin resistance. Gulonolactone oxidase knockout (Gulo-/-) mice genetically unable to synthesize vitamin C were used to induce insulin resistance by continuously pumping small doses of TNF-α for seven days, and human liver hepatocellular carcinoma cells (HepG2 cells) were used to induce insulin resistance by treatment with TNF-α. Vitamin C deficiency aggravated TNF-α-induced insulin resistance in Gulo-/- mice, resulting in worse glucose tolerance test (GTT) results, higher fasting plasma insulin level, and the inactivation of the protein kinase B (AKT)/glycogen synthase kinase-3β (GSK3β) pathway in the liver. Vitamin C deficiency also worsened liver lipid accumulation and inflammation in TNF-α-treated Gulo-/- mice. In HepG2 cells, vitamin C reversed the TNF-α-induced reduction of glucose uptake and glycogen synthesis, which were mediated by increasing GLUT2 levels and the activation of the insulin receptor substrate (IRS-1)/AKT/GSK3β pathway. Furthermore, vitamin C inhibited the TNF-α-induced activation of not only the mitogen-activated protein kinase (MAPKs), but also nuclear factor-kappa B (NF-κB) signaling. Taken together, vitamin C is essential for preventing and improving insulin resistance, and the supplementing with vitamin C may be an effective therapeutic intervention for metabolic disorders.
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Affiliation(s)
- Zhou Qing
- Department of Endocrinology of the affiliated Children's Hospital, Zhejiang University School of Medicine, China
| | - Wu Xiao-Hui
- Department of Endocrinology of the affiliated Children's Hospital, Zhejiang University School of Medicine, China
| | - Wu Xi-Mei
- Department of Pharmacology, Zhejiang University School of Medicine, China
| | - Zou Chao-Chun
- Department of Endocrinology of the affiliated Children's Hospital, Zhejiang University School of Medicine, China.
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