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Zhang SM, Fan B, Li YL, Zuo ZY, Li GY. Oxidative Stress-Involved Mitophagy of Retinal Pigment Epithelium and Retinal Degenerative Diseases. Cell Mol Neurobiol 2023; 43:3265-3276. [PMID: 37391574 PMCID: PMC10477140 DOI: 10.1007/s10571-023-01383-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 06/22/2023] [Indexed: 07/02/2023]
Abstract
The retinal pigment epithelium (RPE) is a highly specialized and polarized epithelial cell layer that plays an important role in sustaining the structural and functional integrity of photoreceptors. However, the death of RPE is a common pathological feature in various retinal diseases, especially in age-related macular degeneration (AMD) and diabetic retinopathy (DR). Mitophagy, as a programmed self-degradation of dysfunctional mitochondria, is crucial for maintaining cellular homeostasis and cell survival under stress. RPE contains a high density of mitochondria necessary for it to meet energy demands, so severe stimuli can cause mitochondrial dysfunction and the excess generation of intracellular reactive oxygen species (ROS), which can further trigger oxidative stress-involved mitophagy. In this review, we summarize the classical pathways of oxidative stress-involved mitophagy in RPE and investigate its role in the progression of retinal diseases, aiming to provide a new therapeutic strategy for treating retinal degenerative diseases. The role of mitophagy in AMD and DR. In AMD, excessive ROS production promotes mitophagy in the RPE by activating the Nrf2/p62 pathway, while in DR, ROS may suppress mitophagy by the FOXO3-PINK1/parkin signaling pathway or the TXNIP-mitochondria-lysosome-mediated mitophagy.
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Affiliation(s)
- Si-Ming Zhang
- Department of Ophthalmology, Second Norman Bethune Hospital of Jilin University, Changchun, 130000, China
| | - Bin Fan
- Department of Ophthalmology, Second Norman Bethune Hospital of Jilin University, Changchun, 130000, China
| | - Yu- Lin Li
- Department of Ophthalmology, Second Norman Bethune Hospital of Jilin University, Changchun, 130000, China
| | - Zhao-Yang Zuo
- Department of Ophthalmology, Second Norman Bethune Hospital of Jilin University, Changchun, 130000, China
| | - Guang-Yu Li
- Department of Ophthalmology, Second Norman Bethune Hospital of Jilin University, Changchun, 130000, China.
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Packer M. Fetal Reprogramming of Nutrient Surplus Signaling, O-GlcNAcylation, and the Evolution of CKD. J Am Soc Nephrol 2023; 34:1480-1491. [PMID: 37340541 PMCID: PMC10482065 DOI: 10.1681/asn.0000000000000177] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Accepted: 06/07/2023] [Indexed: 06/22/2023] Open
Abstract
ABSTRACT Fetal kidney development is characterized by increased uptake of glucose, ATP production by glycolysis, and upregulation of mammalian target of rapamycin (mTOR) and hypoxia-inducible factor-1 alpha (HIF-1 α ), which (acting in concert) promote nephrogenesis in a hypoxic low-tubular-workload environment. By contrast, the healthy adult kidney is characterized by upregulation of sirtuin-1 and adenosine monophosphate-activated protein kinase, which enhances ATP production through fatty acid oxidation to fulfill the needs of a normoxic high-tubular-workload environment. During stress or injury, the kidney reverts to a fetal signaling program, which is adaptive in the short term, but is deleterious if sustained for prolonged periods when both oxygen tension and tubular workload are heightened. Prolonged increases in glucose uptake in glomerular and proximal tubular cells lead to enhanced flux through the hexosamine biosynthesis pathway; its end product-uridine diphosphate N -acetylglucosamine-drives the rapid and reversible O-GlcNAcylation of thousands of intracellular proteins, typically those that are not membrane-bound or secreted. Both O-GlcNAcylation and phosphorylation act at serine/threonine residues, but whereas phosphorylation is regulated by hundreds of specific kinases and phosphatases, O-GlcNAcylation is regulated only by O-GlcNAc transferase and O-GlcNAcase, which adds or removes N-acetylglucosamine, respectively, from target proteins. Diabetic and nondiabetic CKD is characterized by fetal reprogramming (with upregulation of mTOR and HIF-1 α ) and increased O-GlcNAcylation, both experimentally and clinically. Augmentation of O-GlcNAcylation in the adult kidney enhances oxidative stress, cell cycle entry, apoptosis, and activation of proinflammatory and profibrotic pathways, and it inhibits megalin-mediated albumin endocytosis in glomerular mesangial and proximal tubular cells-effects that can be aggravated and attenuated by augmentation and muting of O-GlcNAcylation, respectively. In addition, drugs with known nephroprotective effects-angiotensin receptor blockers, mineralocorticoid receptor antagonists, and sodium-glucose cotransporter 2 inhibitors-are accompanied by diminished O-GlcNAcylation in the kidney, although the role of such suppression in mediating their benefits has not been explored. The available evidence supports further work on the role of uridine diphosphate N -acetylglucosamine as a critical nutrient surplus sensor (acting in concert with upregulated mTOR and HIF-1 α signaling) in the development of diabetic and nondiabetic CKD.
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Affiliation(s)
- Milton Packer
- Baylor Heart and Vascular Institute , Dallas , Texas and Imperial College , London , United Kingdom
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Liu Z, Gan S, Fu L, Xu Y, Wang S, Zhang G, Pan D, Tao L, Shen X. 1,8-Cineole ameliorates diabetic retinopathy by inhibiting retinal pigment epithelium ferroptosis via PPAR-γ/TXNIP pathways. Biomed Pharmacother 2023; 164:114978. [PMID: 37271074 DOI: 10.1016/j.biopha.2023.114978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2023] [Revised: 05/25/2023] [Accepted: 05/30/2023] [Indexed: 06/06/2023] Open
Abstract
1,8-Cineole, the main component of volatile oil in aromatic plants, has diverse pharmacological properties, including antioxidant, anti-inflammatory, and anti-cancer properties. Diabetic retinopathy (DR) is a common microvascular complication of diabetes mellitus (DM). Here, we investigated the protective effect of 1,8-cineole on DR and found that 1,8-cineole treatment could alter the expression of several genes in both high glucose (HG)-induced ARPE-19 cells and retinal tissues of DM mice, as well as inhibit ferroptosis. Subsequent investigations into the molecular mechanisms underlying this inhibition revealed that expression of thioredoxin-interacting protein (TXNIP) was significantly upregulated while that of peroxisome proliferator-activated receptor γ (PPAR-γ) was significantly downregulated in HG-induced ARPE-19 cells, and treatment with 1,8-cineole could effectively reverse these changes. Treatment with a PPAR-γ pharmacological agonist (rosiglitazone), alone or combined with 1,8-cineole, significantly inhibited the transcription of TXNIP and ferroptosis in HG-induced ARPE-19 cells. Conversely, pretreatment with GW9662, a PPAR-γ inhibitor, upregulated the transcription and expression of TXNIP in HG-induced ARPE-19 cells; 1,8-cineole failed to reverse this upregulated expression. To explore these relationships, we constructed a PPAR-γ adenovirus shRNA to elucidate the effect of 1,8-cineole on the negative regulation of TXNIP by PPAR-γ. Taken together, the present findings indicate that HG-induced ferroptosis in retinal tissue plays an essential role in the pathogenesis of DR, which can be ameliorated by 1,8-cineole.
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Affiliation(s)
- Zhangnian Liu
- The State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang, China; The Department of Pharmacology of Materia Medica (The High Efficacy Application of Natural Medicinal Resources Engineering Center of Guizhou Province and The High Educational Key Laboratory of Guizhou Province for Natural Medicinal Pharmacology and Druggability), School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang, China; The Key Laboratory of Optimal Utilization of Natural Medicine Resources (The Union Key Laboratory of Guiyang City-Guizhou Medical University), School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang, China
| | - Shiquan Gan
- The State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang, China; The Department of Pharmacology of Materia Medica (The High Efficacy Application of Natural Medicinal Resources Engineering Center of Guizhou Province and The High Educational Key Laboratory of Guizhou Province for Natural Medicinal Pharmacology and Druggability), School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang, China; The Key Laboratory of Optimal Utilization of Natural Medicine Resources (The Union Key Laboratory of Guiyang City-Guizhou Medical University), School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang, China
| | - Lingyun Fu
- The State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang, China; The Department of Pharmacology of Materia Medica (The High Efficacy Application of Natural Medicinal Resources Engineering Center of Guizhou Province and The High Educational Key Laboratory of Guizhou Province for Natural Medicinal Pharmacology and Druggability), School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang, China; The Key Laboratory of Optimal Utilization of Natural Medicine Resources (The Union Key Laboratory of Guiyang City-Guizhou Medical University), School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang, China; The Key Laboratory of Endemic and Ethnic Diseases of Ministry of Education, Guizhou Medical University, Guiyang, China
| | - Yini Xu
- The State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang, China; The Department of Pharmacology of Materia Medica (The High Efficacy Application of Natural Medicinal Resources Engineering Center of Guizhou Province and The High Educational Key Laboratory of Guizhou Province for Natural Medicinal Pharmacology and Druggability), School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang, China; The Key Laboratory of Optimal Utilization of Natural Medicine Resources (The Union Key Laboratory of Guiyang City-Guizhou Medical University), School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang, China
| | - Shengquan Wang
- The State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang, China; The Department of Pharmacology of Materia Medica (The High Efficacy Application of Natural Medicinal Resources Engineering Center of Guizhou Province and The High Educational Key Laboratory of Guizhou Province for Natural Medicinal Pharmacology and Druggability), School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang, China; The Key Laboratory of Optimal Utilization of Natural Medicine Resources (The Union Key Laboratory of Guiyang City-Guizhou Medical University), School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang, China
| | - Guangqiong Zhang
- The State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang, China; The Department of Pharmacology of Materia Medica (The High Efficacy Application of Natural Medicinal Resources Engineering Center of Guizhou Province and The High Educational Key Laboratory of Guizhou Province for Natural Medicinal Pharmacology and Druggability), School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang, China; The Key Laboratory of Optimal Utilization of Natural Medicine Resources (The Union Key Laboratory of Guiyang City-Guizhou Medical University), School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang, China
| | - Di Pan
- The State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang, China; The Department of Pharmacology of Materia Medica (The High Efficacy Application of Natural Medicinal Resources Engineering Center of Guizhou Province and The High Educational Key Laboratory of Guizhou Province for Natural Medicinal Pharmacology and Druggability), School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang, China; The Key Laboratory of Optimal Utilization of Natural Medicine Resources (The Union Key Laboratory of Guiyang City-Guizhou Medical University), School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang, China
| | - Ling Tao
- The State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang, China; The Key Laboratory of Optimal Utilization of Natural Medicine Resources (The Union Key Laboratory of Guiyang City-Guizhou Medical University), School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang, China.
| | - Xiangchun Shen
- The State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang, China; The Department of Pharmacology of Materia Medica (The High Efficacy Application of Natural Medicinal Resources Engineering Center of Guizhou Province and The High Educational Key Laboratory of Guizhou Province for Natural Medicinal Pharmacology and Druggability), School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang, China; The Key Laboratory of Optimal Utilization of Natural Medicine Resources (The Union Key Laboratory of Guiyang City-Guizhou Medical University), School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang, China; The Key Laboratory of Endemic and Ethnic Diseases of Ministry of Education, Guizhou Medical University, Guiyang, China.
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Potential Combination Drug Therapy to Prevent Redox Stress and Mitophagy Dysregulation in Retinal Müller Cells under High Glucose Conditions: Implications for Diabetic Retinopathy. Diseases 2021; 9:diseases9040091. [PMID: 34940029 PMCID: PMC8700204 DOI: 10.3390/diseases9040091] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 12/02/2021] [Accepted: 12/10/2021] [Indexed: 12/12/2022] Open
Abstract
Chronic hyperglycemia-induced thioredoxin-interacting protein (TXNIP) expression, associated oxidative/nitrosative stress (ROS/RNS), and mitochondrial dysfunction play critical roles in the etiology of diabetic retinopathy (DR). However, there is no effective drug treatment to prevent or slow down the progression of DR. The purpose of this study is to examine if a combination drug treatment targeting TXNIP and the mitochondria-lysosome pathway prevents high glucose-induced mitochondrial stress and mitophagic flux in retinal Müller glial cells in culture, relevant to DR. We show that diabetes induces TXNIP expression, redox stress, and Müller glia activation (gliosis) in rat retinas when compared to non-diabetic rat retinas. Furthermore, high glucose (HG, 25 mM versus low glucose, LG 5.5 mM) also induces TXNIP expression and mitochondrial stress in a rat retinal Müller cell line, rMC1, in in vitro cultures. Additionally, we develop a mitochondria-targeted mCherry and EGFP probe tagged with two tandem COX8a mitochondrial target sequences (adenovirus-CMV-2×mt8a-CG) to examine mitophagic flux in rMC1. A triple drug combination treatment was applied using TXNIP-IN1 (which inhibits TXNIP interaction with thioredoxin), Mito-Tempo (mitochondrial anti-oxidant), and ML-SA1 (lysosome targeted activator of transient calcium channel MCOLN1/TRPML1 and of transcription factor TFEB) to study the mitochondrial-lysosomal axis dysregulation. We found that HG induces TXNIP expression, redox stress, and mitophagic flux in rMC1 versus LG. Treatment with the triple drug combination prevents mitophagic flux and restores transcription factor TFEB and PGC1α nuclear localization under HG, which is critical for lysosome biosynthesis and mitogenesis, respectively. Our results demonstrate that 2×mt8a-CG is a suitable probe for monitoring mitophagic flux, both in live and fixed cells in in vitro experiments, which may also be applicable to in vivo animal studies, and that the triple drug combination treatment has the potential for preventing retinal injury and disease progression in diabetes.
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Aouichat S, Navarro-Alarcon M, Alarcón-Guijo P, Salagre D, Ncir M, Zourgui L, Agil A. Melatonin Improves Endoplasmic Reticulum Stress-Mediated IRE1α Pathway in Zücker Diabetic Fatty Rat. Pharmaceuticals (Basel) 2021; 14:232. [PMID: 33800157 PMCID: PMC8001258 DOI: 10.3390/ph14030232] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 03/03/2021] [Accepted: 03/04/2021] [Indexed: 12/12/2022] Open
Abstract
Obesity and diabetes are linked to an increased prevalence of kidney disease. Endoplasmic reticulum stress has recently gained growing importance in the pathogenesis of obesity and diabetes-related kidney disease. Melatonin, is an important anti-obesogenic natural bioactive compound. Previously, our research group showed that the renoprotective effect of melatonin administration was associated with restoring mitochondrial fission/fusion balance and function in a rat model of diabesity-induced kidney injury. This study was carried out to further investigate whether melatonin could suppress renal endoplasmic reticulum (ER) stress response and the downstream unfolded protein response activation under obese and diabetic conditions. Zücker diabetic fatty (ZDF) rats and lean littermates (ZL) were orally supplemented either with melatonin (10 mg/kg body weight (BW)/day) (M-ZDF and M-ZL) or vehicle (C-ZDF and C-ZL) for 17 weeks. Western blot analysis of ER stress-related markers and renal morphology were assessed. Compared to C-ZL rats, higher ER stress response associated with impaired renal morphology was observed in C-ZDF rats. Melatonin supplementation alleviated renal ER stress response in ZDF rats, by decreasing glucose-regulated protein 78 (GRP78), phosphoinositol-requiring enzyme1α (IRE1α), and ATF6 levels but had no effect on phospho-protein kinase RNA-like endoplasmic reticulum kinase (PERK) level. In addition, melatonin supplementation also restrained the ER stress-mediated apoptotic pathway, as indicated by decreased pro-apoptotic proteins phospho-c-jun amino terminal kinase (JNK), Bax, and cleaved caspase-3, as well as by upregulation of B cell lymphoma (Bcl)-2 protein. These improvements were associated with renal structural recovery. Taken together, our findings revealed that melatonin play a renoprotective role, at least in part, by suppressing ER stress and related pro-apoptotic IRE1α/JNK signaling pathway.
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Affiliation(s)
- Samira Aouichat
- Department of Pharmacology, Biohealth Institute and Neurosciences Institute, School of Medicine, University of Granada, 18016 Granada, Spain; (S.A.); (P.A.-G.); (D.S.)
- Team of Cellular and Molecular Physiopathology, Faculty of Biological Sciences, University of Sciences and Technology Houari Boumediene, El Alia, Algiers 16111, Algeria
| | - Miguel Navarro-Alarcon
- Department of Nutrition and Bromatology, School of Pharmacy, University of Granada, 18071 Granada, Spain;
| | - Pablo Alarcón-Guijo
- Department of Pharmacology, Biohealth Institute and Neurosciences Institute, School of Medicine, University of Granada, 18016 Granada, Spain; (S.A.); (P.A.-G.); (D.S.)
| | - Diego Salagre
- Department of Pharmacology, Biohealth Institute and Neurosciences Institute, School of Medicine, University of Granada, 18016 Granada, Spain; (S.A.); (P.A.-G.); (D.S.)
| | - Marwa Ncir
- Bioactive Molecule Valorization Research Unit, Higher Institute of Applied Biology of Medenine, University of Gabes, Gabes 4119, Tunisia; (M.N.); (L.Z.)
| | - Lazhar Zourgui
- Bioactive Molecule Valorization Research Unit, Higher Institute of Applied Biology of Medenine, University of Gabes, Gabes 4119, Tunisia; (M.N.); (L.Z.)
| | - Ahmad Agil
- Department of Pharmacology, Biohealth Institute and Neurosciences Institute, School of Medicine, University of Granada, 18016 Granada, Spain; (S.A.); (P.A.-G.); (D.S.)
- Biosanitary Research Institute of Granada (ibs. GRANADA), University Hospital of Granada, 18016 Granada, Spain
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Multifaceted Protective Role of Glucosamine against Osteoarthritis: Review of Its Molecular Mechanisms. Sci Pharm 2019. [DOI: 10.3390/scipharm87040034] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Osteoarthritis (OA) is a joint disease resulting from cartilage degeneration and causing joint pain and stiffness. Glucosamine exerts chondroprotective effects and effectively reduces OA pain and stiffness. This review aims to summarise the mechanism of glucosamine in protecting joint health and preventing OA by conducting a literature search on original articles. Current evidence has revealed that glucosamine exhibits anti-inflammatory effects by reducing the levels of pro-inflammatory factors (such as tumour necrosis factor-alpha, interleukin-1, and interleukin-6) and enhancing the synthesis of proteoglycans that retard cartilage degradation and improve joint function. Additionally, glucosamine improves cellular redox status, reduces OA-mediated oxidative damages, scavenges free radicals, upregulates antioxidant proteins and enzyme levels, inhibits the production of reactive oxygen species, and induces autophagy to delay OA pathogenesis. In conclusion, glucosamine prevents OA and maintains joint health by reducing inflammation, improving the redox status, and inducing autophagy in joints. Further studies are warranted to determine the synergistic effect of glucosamine with other anti-inflammatory and/or antioxidative agents on joint health in humans.
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Song S, Qiu D, Shi Y, Wang S, Zhou X, Chen N, Wei J, Wu M, Wu H, Duan H. Thioredoxin-interacting protein deficiency alleviates phenotypic alterations of podocytes via inhibition of mTOR activation in diabetic nephropathy. J Cell Physiol 2019; 234:16485-16502. [PMID: 30746698 DOI: 10.1002/jcp.28317] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 01/22/2019] [Accepted: 01/24/2019] [Indexed: 01/24/2023]
Abstract
Thioredoxin-interacting protein (TXNIP) is induced by high glucose (HG), whereupon it acts to inhibit thioredoxin, thereby promoting oxidative stress. We have found that TXNIP knockdown in human renal tubular cells helped prevent the epithelial-to-mesenchymal transition (EMT). Here, we studied the potential effect of TXNIP on podocyte phenotypic alterations in diabetic nephropathy (DN) in vivo and in vitro. In conditionally immortalized mouse podocytes under HG conditions, knocking down TXNIP disrupted EMT, reactive oxygen species (ROS) production, and mammalian target of rapamycin (mTOR) pathway activation. Further, Raptor short hairpin RNA (shRNA), Rictor shRNA, and mTOR specific inhibitor KU-0063794 were used to assess if the mTOR signal pathway is involved in HG-induced EMT in podocytes. We found that Raptor shRNA, Rictor shRNA, and KU-0063794 could all restrain HG-induced EMT and ROS production in podocytes. In addition, antioxidant Tempol or N-acetylcysteine presented a prohibitive effect on HG-induced EMT in podocytes. Streptozotocin was utilized to render equally diabetic in wild-type (WT) control and TXNIP -/- (TKO) mice. Diabetes did not increase levels of 24-hr urinary protein, serum creatinine, blood urea nitrogen, and triglyceride in TXNIP -/- mice. Podocyte phenotypic alterations and podocyte loss were detected in WT but not in TKO diabetic mice. Oxidative stress was also suppressed in diabetic TKO mice relative to WT controls. Also, TXNIP deficiency suppresses the activation of mTOR in glomeruli of streptozotocin-induced diabetic mice. Moreover, TXNIP expression, mTOR activation, Nox1, and Nox4 could be detected in renal biopsy tissues of patients with DN. This suggests that decreased TXNIP could ameliorate phenotypic alterations of podocytes via inhibition of mTOR in DN, highlighting TXNIP as a promising therapeutic target.
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Affiliation(s)
- Shan Song
- Department of Pathology, Hebei Medical University, Shijiazhuang, China
| | - Duojun Qiu
- Department of Pathology, Hebei Medical University, Shijiazhuang, China
| | - Yonghong Shi
- Department of Pathology, Hebei Medical University, Shijiazhuang, China.,Hebei Key Laboratory of Kidney Diseases, Shijiazhuang, China
| | - Shuai Wang
- Department of Pathology, Hebei Medical University, Shijiazhuang, China
| | - Xinbo Zhou
- Department of Pathology, Hebei Medical University, Shijiazhuang, China
| | - Nan Chen
- Department of Pathology, Hebei Medical University, Shijiazhuang, China
| | - Jinying Wei
- Department of Pathology, Hebei Medical University, Shijiazhuang, China.,Hebei Key Laboratory of Kidney Diseases, Shijiazhuang, China
| | - Ming Wu
- Department of Pathology, Hebei Medical University, Shijiazhuang, China
| | - Haijiang Wu
- Department of Pathology, Hebei Medical University, Shijiazhuang, China.,Hebei Key Laboratory of Kidney Diseases, Shijiazhuang, China
| | - Huijun Duan
- Department of Pathology, Hebei Medical University, Shijiazhuang, China.,Hebei Key Laboratory of Kidney Diseases, Shijiazhuang, China
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Ameliorative effect of Magnesium Isoglycyrrhizinate on hepatic encephalopathy by Epirubicin. Int Immunopharmacol 2019; 75:105774. [PMID: 31351363 DOI: 10.1016/j.intimp.2019.105774] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Revised: 06/27/2019] [Accepted: 07/18/2019] [Indexed: 02/08/2023]
Abstract
BACKGROUND The purpose of the present study was to evaluate the protective effect of Magnesium Isoglycyrrhizinate (MI) on Epirubicin (EPI)-induced hepatic encephalopathy (HE) and explore its underlying mechanism. METHODS Mice were divided randomly into groups for treatments as follows: control group, EPI group (Model group), EPI + MI (25, 50 mg/kg) group. Morris water maze test were conducted to evaluate the spatial learning and memory ability. The serum and hippocampus levels of oxidative stress or inflammation were uncovered with the detection of superoxide dismutase (SOD), malondialdehyde (MDA), and pro-inflammatory cytokines (IL-1β, IL-6, TNF-α). RESULTS As a result, treatment with MI effectively ameliorated the EPI-induced decline in the ability of spatial learning and memory. MI also significantly relieved the severity of oxidative stress or inflammation in serum and hippocampus, which was accompanied with regulating liver functional parameters. Western blot data demonstrated that administration of MI could regulate the redox-related expressions of Txnip, Trx, Nrf2, HO-1, p-IκB-α, p-NF-κB, Caspase-3, Caspase-9, Bax and Bcl-2 in EPI-stimulated hepatic encephalopathy (HE). And the potency of MI treatments on Nrf2, NF-κB expression was also confirmed with immunohistochemical analysis. CONCLUSIONS Taken together, the protective effect of Magnesium Isoglycyrrhizinate on EPI-induced hepatic encephalopathy might be mediated via the Txnip/Nrf2/NF-κB signaling pathway.
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Devi TS, Yumnamcha T, Yao F, Somayajulu M, Kowluru RA, Singh LP. TXNIP mediates high glucose-induced mitophagic flux and lysosome enlargement in human retinal pigment epithelial cells. Biol Open 2019; 8:bio.038521. [PMID: 31023645 PMCID: PMC6503994 DOI: 10.1242/bio.038521] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Thioredoxin-interacting protein (TXNIP) plays a critical role in oxidative stress, inflammation, apoptosis and the pathogenesis of diabetic retinopathy (DR). However, the role of TXNIP in high glucose-induced retinal pigment epithelium (RPE) dysfunction is still unknown. Here, we show that high glucose (HG; 25 mM,) significantly increases TXNIP expression at both the mRNA and protein levels when compared to low glucose (LG; 5.5 mM) in a human RPE cell line (ARPE-19) and primary human RPE (HRPE) cells. TXNIP upregulation is associated with mitochondrial membrane depolarization, fragmentation and mitophagic flux to lysosomes. We used confocal live-cell imaging of RPE cells expressing mt-Keima, a coral protein that emits green light in mitochondria (alkaline or neutral pH) and red light in the acidic lysosome, to measure mitophagic flux. We observed an elongated mitochondrial network of green mt-Keima under LG, which is fragmented in HG. Red mt-Keima accumulates in lysosomes as small punctate aggregations under LG in both ARPE-19 and HRPE cells, whereas they are significantly enlarged (two- to threefold) under HG. Lysosomal enlargement under HG is further illustrated by lysosomal membrane protein LAMP1-mCherry expression in both ARPE-19 and HRPE cells. Furthermore, HG causes lysosomal cathepsin L inactivation and pro-inflammatory caspase-1 activation in ARPE-19 cells. TXNIP knockdown by shRNA prevents mitochondrial fragmentation, mitophagic flux and lysosome enlargement under HG. In addition, antioxidant N-acetylcysteine (NAC) and Amlexanox (Amlx), an inhibitor of protein kinase TBK1 and of the mitophagic adaptors Optineurin (Optn) and Sequestosome 1 (p62/SQSTM1), prevent mitophagic flux and lysosome enlargement. These results suggest that TXNIP mediates several deleterious effects of high glucose on RPE, which may be implicated in the development of DR.
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Affiliation(s)
- Takhellambam S Devi
- Department of Ophthalmology, Visual and Anatomical Sciences (OVAS), Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Thangal Yumnamcha
- Department of Ophthalmology, Visual and Anatomical Sciences (OVAS), Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Fayi Yao
- Department of Ophthalmology, Visual and Anatomical Sciences (OVAS), Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Mallika Somayajulu
- Department of Ophthalmology, Visual and Anatomical Sciences (OVAS), Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Renu A Kowluru
- Department of Ophthalmology, Visual and Anatomical Sciences (OVAS), Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Lalit P Singh
- Department of Ophthalmology, Visual and Anatomical Sciences (OVAS), Wayne State University School of Medicine, Detroit, MI 48201, USA
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Mou X, Zhou DY, Liu YH, Liu K, Zhou D. Identification of potential therapeutic target genes in mouse mesangial cells associated with diabetic nephropathy using bioinformatics analysis. Exp Ther Med 2019; 17:4617-4627. [PMID: 31105790 PMCID: PMC6507521 DOI: 10.3892/etm.2019.7524] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 04/09/2019] [Indexed: 01/08/2023] Open
Abstract
The aim of the present study was to identify genes under the effect of transforming growth factor-β (TGF-β1), high glucose (HG) and glucosamine (GlcN) in MES-13 mesangial cells and elucidate the molecular mechanisms of diabetic nephropathy (DN). The gene expression datasets GSE2557 and GSE2558 were downloaded from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) were independently screened using the GEO2R online tool. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed using the Database for Annotation, Visualization, and Integrated Discovery. The protein-protein interaction (PPI) network was constructed using the Search Tool for the Retrieval of Interacting Genes and Cytoscape software. The hub genes were identified by the NetworkAnalyzer plugin. Overlapping genes were subjected to molecular docking analysis using SystemsDock. A total of 202 upregulated and 158 downregulated DEGs from the HG-treated groups, 138 upregulated and 103 downregulated DEGs from the GlcN-treated groups, and 81 upregulated and 44 downregulated DEGs from the TGF-β1-treated groups were identified. The majority of the DEGs were independently enriched in 'nucleosome assembly', 'chromatin silencing' and 'xenobiotic glucuronidation'. In addition, KEGG pathways were significantly enriched in 'systemic lupus erythematosus', 'protein processing in endoplasmic reticulum' and 'aldarate metabolism pathway', and 'TNF signaling pathway' intersected in the TGF-β1-treated and HG-treated groups. In total, eight hub genes, Jun, prostaglandin-endoperoxide synthase 2 (Ptgs2), fibronectin 1 (Fn1), cyclin-dependent kinase (Cdk)2, Fos, heat shock protein family A (Hsp70) member 5 (Hspa5), Hsp90b1 and homo sapiens hypoxia upregulated 1 (Hyou1), and three overlapping genes, Ras homolog gene family, member B (RHOB), complement factor H (CFH) and Krüppel-like factor 15 (KLF15), were selected. Valsartan with RHOB, and fosinopril with CFH and KLF15 had preferential binding activity. In conclusion, Jun, Ptgs2, Fn1, Cdk2, Fos, Hspa5, Hsp90b1, Hyou1, RHOB, CFH and KLF15 may be potential therapeutic targets for mesangial cells associated with DN, which may provide insight into DN treatment strategies.
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Affiliation(s)
- Xin Mou
- Department of Endocrinology, Zhejiang Integrated and Western Medicine Hospital, Hangzhou, Zhejiang 310003, P.R. China
| | - Di Yi Zhou
- Department of Endocrinology, Zhejiang Integrated and Western Medicine Hospital, Hangzhou, Zhejiang 310003, P.R. China
| | - Ying Hui Liu
- Department of Endocrinology, Zhejiang Integrated and Western Medicine Hospital, Hangzhou, Zhejiang 310003, P.R. China
| | - Kaiyuan Liu
- Department of Endocrinology, Zhejiang Integrated and Western Medicine Hospital, Hangzhou, Zhejiang 310003, P.R. China
| | - Danyang Zhou
- Department of Endocrinology, Zhejiang Integrated and Western Medicine Hospital, Hangzhou, Zhejiang 310003, P.R. China
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11
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Bousseau S, Vergori L, Soleti R, Lenaers G, Martinez MC, Andriantsitohaina R. Glycosylation as new pharmacological strategies for diseases associated with excessive angiogenesis. Pharmacol Ther 2018; 191:92-122. [DOI: 10.1016/j.pharmthera.2018.06.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2018] [Accepted: 06/01/2018] [Indexed: 02/07/2023]
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12
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Lalit PS, Thangal Y, Fayi Y, Takhellambam SD. Potentials of Gene Therapy for Diabetic Retinopathy: The Use of Nucleic Acid Constructs Containing a TXNIP Promoter. OPEN ACCESS JOURNAL OF OPHTHALMOLOGY 2018; 3. [PMID: 31106306 DOI: 10.23880/oajo-16000147] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Diabetic retinopathy (DR) is considered as a chronic eye disease leading to blindness. DR is associated with hyperglycemia-induced oxidative stress, chronic low-grade inflammation and premature cell death. DR affects retinal capillaries, neuroretina and the retinal pigment epithelium. Recently, the thioredoxin-interacting protein TXNIP has been shown as a pro-oxidative stress, pro-inflammatory and pro-apoptotic protein, highly induced by diabetes and high glucose in all cells examined including the retina. TXNIP's actions involve binding to and inhibition of anti-oxidant and thiol-reducing capacities of thioredoxins (Trx) causing cellular oxidative stress and apoptosis. Trx1 is found in the cytosol and nucleus while Trx2 is the mitochondrial isoform. Several studies provided evidence that knockdown of TXNIP by siRNA or chemical blockade ameliorates early abnormalities of DR including endothelial dysfunction, pericyte apoptosis, Müller cell gliosis and neurodegeneration. Therefore, TXNIP is considered a potential target for preventing or slowing down the progression of DR. We recently proposed that nucleic acid constructs containing a proximal TXNIP promoter linked to a redox gene or shRNA that reduces oxidative stress and inflammation may be used to treat DR. The TXNIP promoter is sensitive to hyperglycemia therefore can drive expression of the linked gene or shRNA under high glucose environment such as seen in diabetes while remaining unresponsive at physiological glucose levels. Such a TXNIP-promoter linked gene or shRNA construct can be delivered to the retina by using adeno-associated viral vectors including AAV2 and AAV2/8 or an appropriate carrier via the intravitreal or sub retinal delivery for long-term gene therapies in DR.
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Affiliation(s)
- P S Lalit
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, USA.,Department of Ophthalmology, Wayne State University School of Medicine, USA
| | - Y Thangal
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, USA
| | - Y Fayi
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, USA
| | - S D Takhellambam
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, USA
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13
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Kumar A, Mittal R. Mapping Txnip: Key connexions in progression of diabetic nephropathy. Pharmacol Rep 2017; 70:614-622. [PMID: 29684849 DOI: 10.1016/j.pharep.2017.12.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 11/13/2017] [Accepted: 12/19/2017] [Indexed: 02/07/2023]
Abstract
Studies demonstrates the major involvement of inflammatory and apoptotic pathway in the pathophysiology of diabetic nephropathy. The cross talk between inflammatory and apoptotic pathway suggests Txnip as a molecular connexion in progression of disease state. Txnip modulates inflammatory pathway (via ROS production and NLRP3 inflammasome activity) and apoptotic pathway (via mTOR pathway). The key contribution of Txnip in both the pathways, reflects, its crucial role in diabetic nephropathy. In the present review, we have first provided an overview of diabetic nephropathy and Txnip system, followed by the mechanistic insight of Txnip in the progression of diabetic nephropathy. This new mechanistic approach suggests to explore Txnip modulators as a promising therapeutic drug target in diabetic nephropathy.
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Affiliation(s)
- Anil Kumar
- Neuropharmacology Division, University Institute of Pharmaceutical Sciences, UGC Centre of Advanced Study, Panjab University, Chandigarh, India.
| | - Ruchika Mittal
- Neuropharmacology Division, University Institute of Pharmaceutical Sciences, UGC Centre of Advanced Study, Panjab University, Chandigarh, India
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14
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Singh LP, Devi TS, Yumnamcha T. The Role of Txnip in Mitophagy Dysregulation and Inflammasome Activation in Diabetic Retinopathy: A New Perspective. ACTA ACUST UNITED AC 2017; 4. [PMID: 29376145 PMCID: PMC5786434 DOI: 10.19080/jojo.2017.04.555643] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Mitochondria are responsible for bioenergetics, metabolism and apoptosis signals in health and disease. The retina being a part of the central nervous system consumes large amounts of glucose and oxygen to generate ATP via the mitochondrial oxidative phosphorylation for its phototransduction and visual function. During ATP generation, electrons leak from the mitochondrial electron transport chain, which is captured by molecular oxygen to produce reactive oxygen species (ROS). These mtROS damage mitochondrial proteins, mtDNA, and membrane lipids and release them in the cytosol. Mitochondrial components are recognized as danger-associated molecular patterns (DAMPS) by cytosolic pattern recognition receptors such as NOD-like receptors, NLRP3 inflammasomes. They process pro-caspase-1 to active caspase-1, which cleaves pro-inflammatory IL-1β o mature IL-1β causing inflammation and cell death by pyroptosis. To counter the damaging action of mtROS and inflammasomes in fully differentiated cells in the retina, the removal of the damaged and dysfunctional mitochondria by a double-membrane autophagic process via lysosomal degradation called mitophagy is critical for mitochondrial homeostasis and cell survival. Nonetheless, under chronic diseases including diabetic retinopathy (DR), mitophagy dysregulation and NLRP3 inflammasome activation exist, which cause premature cell death and disease progression. Recently, the thioredoxin-interacting protein TXNIP, which is strongly induced by diabetes and inhibits anti-oxidant function of thioredoxin, has been implicated in mitochondrial dysfunction, mitophagic dysregulation and NLRP3 inflammasome activation in DR. Therefore, TXNIP silencing or pharmacological inhibition may normalize mitophagic flux and NLRP3 inflammasome activation, which will prevent or slow down the progression of DR.
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Affiliation(s)
- Lalit P Singh
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, USA.,Department of Ophthalmology, Wayne State University School of Medicine, USA
| | - Takhellambam S Devi
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, USA
| | - Thangal Yumnamcha
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, USA
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15
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Oxidative stress and calcium dysregulation by palmitate in type 2 diabetes. Exp Mol Med 2017; 49:e291. [PMID: 28154371 PMCID: PMC5336562 DOI: 10.1038/emm.2016.157] [Citation(s) in RCA: 221] [Impact Index Per Article: 31.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 10/07/2016] [Accepted: 10/16/2016] [Indexed: 12/12/2022] Open
Abstract
Free fatty acids (FFAs) are important substrates for mitochondrial oxidative metabolism and ATP synthesis but also cause serious stress to various tissues, contributing to the development of metabolic diseases. CD36 is a major mediator of cellular FFA uptake. Inside the cell, saturated FFAs are able to induce the production of cytosolic and mitochondrial reactive oxygen species (ROS), which can be prevented by co-exposure to unsaturated FFAs. There are close connections between oxidative stress and organellar Ca2+ homeostasis. Highly oxidative conditions induced by palmitate trigger aberrant endoplasmic reticulum (ER) Ca2+ release and thereby deplete ER Ca2+ stores. The resulting ER Ca2+ deficiency impairs chaperones of the protein folding machinery, leading to the accumulation of misfolded proteins. This ER stress may further aggravate oxidative stress by augmenting ER ROS production. Secondary to ER Ca2+ release, cytosolic and mitochondrial matrix Ca2+ concentrations can also be altered. In addition, plasmalemmal ion channels operated by ER Ca2+ depletion mediate persistent Ca2+ influx, further impairing cytosolic and mitochondrial Ca2+ homeostasis. Mitochondrial Ca2+ overload causes superoxide production and functional impairment, culminating in apoptosis. This vicious cycle of lipotoxicity occurs in multiple tissues, resulting in β-cell failure and insulin resistance in target tissues, and further aggravates diabetic complications.
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16
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Gnudi L, Coward RJM, Long DA. Diabetic Nephropathy: Perspective on Novel Molecular Mechanisms. Trends Endocrinol Metab 2016; 27:820-830. [PMID: 27470431 DOI: 10.1016/j.tem.2016.07.002] [Citation(s) in RCA: 212] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Revised: 07/04/2016] [Accepted: 07/07/2016] [Indexed: 02/07/2023]
Abstract
Diabetes mellitus (DM) is the major cause of end-stage renal disease (ESRD) globally, and novel treatments are urgently needed. Current therapeutic approaches for diabetic nephropathy (DN) are focussing on blood pressure control with inhibitors of the renin-angiotensin-aldosterone system, on glycaemic and lipid control, and life-style changes. In this review, we highlight new molecular insights aiding our understanding of the initiation and progression of DN, including glomerular insulin resistance, dysregulation of cellular substrate utilisation, podocyte-endothelial communication, and inhibition of tubular sodium coupled glucose reabsorption. We believe that these mechanisms offer new therapeutic targets that can be exploited to develop important renoprotective treatments for DN over the next decade.
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Affiliation(s)
- Luigi Gnudi
- Cardiovascular Division, King's College London, London, SE1 9NH, UK.
| | - Richard J M Coward
- Academic Renal Unit, Dorothy Hodgkin Building, University of Bristol, Whitson Street, Bristol BS1 3NY, UK
| | - David A Long
- Developmental Biology and Cancer Programme, Institute of Child Health, University College London, London, WC1N 1EH, UK.
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Bhattacharjee N, Barma S, Konwar N, Dewanjee S, Manna P. Mechanistic insight of diabetic nephropathy and its pharmacotherapeutic targets: An update. Eur J Pharmacol 2016; 791:8-24. [PMID: 27568833 DOI: 10.1016/j.ejphar.2016.08.022] [Citation(s) in RCA: 172] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 08/03/2016] [Accepted: 08/24/2016] [Indexed: 02/09/2023]
Abstract
Diabetic nephropathy (DN), a chronic complication of diabetes, is charecterized by glomerular hypertrophy, proteinuria, decreased glomerular filtration, and renal fibrosis resulting in the loss of renal function. Although the exact cause of DN remains unclear, several mechanisms have been postulated, such as hyperglycemia-induced renal hyper filtration and renal injury, AGEs-induced increased oxidative stress, activated PKC-induced increased production of cytokines, chemokines, and different inflammatory and apoptotic signals. Among various factors, oxidative stress has been suggested to play a major role underlying the onset and propagation of DN. It triggers several signaling pathways involved in DN, like AGEs, PKC cascade, JAK/STAT signaling, MAPK, mTOR, and SMAD. Oxidative stress-induced activation of both inflammatory and apoptotic signals are two major problems in the pathogenesis of DN. The FDA approved pharmacotherapeutic agents affecting against polyol pathway principally include anti-oxidants, like α-lipoic acid, vitamin E, and vitamin C. Kremezin and benfotiamine are the FDA approved AGEs inhibitors, another therapeutic target against DN. Ruboxistaurin, telmizartan, rapamycin, fenofibrate, aliskiren, and manidipine are some FDA approved pharmacotherapeutics effective against DN via diverse mechanisms. Beside this, some therapeutic agents are still waiting for FDA approval and few drugs without FDA approval are also prescribed in some countries for the management of DN. Despite the medications available in the market to treat DN, the involvement of multiple mechanisms makes it difficult to choose an optimum therapeutic agent. Therefore, much research is required to find out new therapeutic agent/strategies for an adequate pharmacotherapy of DN.
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Affiliation(s)
- Niloy Bhattacharjee
- Advanced Pharmacognosy Research Laboratory, Department of Pharmaceutical Technology, Jadavpur University, Raja S C Mullick Road, Kolkata 700032, India
| | - Sujata Barma
- Advanced Pharmacognosy Research Laboratory, Department of Pharmaceutical Technology, Jadavpur University, Raja S C Mullick Road, Kolkata 700032, India
| | - Nandita Konwar
- Biological Science and Technology Division, CSIR-NEIST, Jorhat, Assam 785006, India
| | - Saikat Dewanjee
- Advanced Pharmacognosy Research Laboratory, Department of Pharmaceutical Technology, Jadavpur University, Raja S C Mullick Road, Kolkata 700032, India.
| | - Prasenjit Manna
- Biological Science and Technology Division, CSIR-NEIST, Jorhat, Assam 785006, India.
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Epigenomic profiling reveals an association between persistence of DNA methylation and metabolic memory in the DCCT/EDIC type 1 diabetes cohort. Proc Natl Acad Sci U S A 2016; 113:E3002-11. [PMID: 27162351 DOI: 10.1073/pnas.1603712113] [Citation(s) in RCA: 155] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
We examined whether persistence of epigenetic DNA methylation (DNA-me) alterations at specific loci over two different time points in people with diabetes are associated with metabolic memory, the prolonged beneficial effects of intensive vs. conventional therapy during the Diabetes Control and Complications Trial (DCCT) on the progression of microvascular outcomes in the long-term follow-up Epidemiology of Diabetes Interventions and Complications (EDIC) Study. We compared DNA-me profiles in genomic DNA of whole blood (WB) isolated at EDIC Study baseline from 32 cases (DCCT conventional therapy group subjects showing retinopathy or albuminuria progression by EDIC Study year 10) vs. 31 controls (DCCT intensive therapy group subjects without complication progression by EDIC year 10). DNA-me was also profiled in blood monocytes (Monos) of the same patients obtained during EDIC Study years 16-17. In WB, 153 loci depicted hypomethylation, and 225 depicted hypermethylation, whereas in Monos, 155 hypomethylated loci and 247 hypermethylated loci were found (fold change ≥1.3; P < 0.005; cases vs. controls). Twelve annotated differentially methylated loci were common in both WB and Monos, including thioredoxin-interacting protein (TXNIP), known to be associated with hyperglycemia and related complications. A set of differentially methylated loci depicted similar trends of associations with prior HbA1c in both WB and Monos. In vitro, high glucose induced similar persistent hypomethylation at TXNIP in cultured THP1 Monos. These results show that DNA-me differences during the DCCT persist at certain loci associated with glycemia for several years during the EDIC Study and support an epigenetic explanation for metabolic memory.
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Brain in situ hybridization maps as a source for reverse-engineering transcriptional regulatory networks: Alzheimer's disease insights. Gene 2016; 586:77-86. [PMID: 27050105 DOI: 10.1016/j.gene.2016.03.045] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 02/05/2016] [Accepted: 03/23/2016] [Indexed: 01/21/2023]
Abstract
Microarray data have been a valuable resource for identifying transcriptional regulatory relationships among genes. As an example, brain region-specific transcriptional regulatory events have the potential of providing etiological insights into Alzheimer Disease (AD). However, there is often a paucity of suitable brain-region specific expression data obtained via microarrays or other high throughput means. The Allen Brain Atlas in situ hybridization (ISH) data sets (Jones et al., 2009) represent a potentially valuable alternative source of high-throughput brain region-specific gene expression data for such purposes. In this study, Allen Brain Atlas mouse ISH data in the hippocampal fields were extracted, focusing on 508 genes relevant to neurodegeneration. Transcriptional regulatory networks were learned using three high-performing network inference algorithms. Only 17% of regulatory edges from a network reverse-engineered based on brain region-specific ISH data were also found in a network constructed upon gene expression correlations in mouse whole brain microarrays, thus showing the specificity of gene expression within brain sub-regions. Furthermore, the ISH data-based networks were used to identify instructive transcriptional regulatory relationships. Ncor2, Sp3 and Usf2 form a unique three-party regulatory motif, potentially affecting memory formation pathways. Nfe2l1, Egr1 and Usf2 emerge among regulators of genes involved in AD (e.g. Dhcr24, Aplp2, Tia1, Pdrx1, Vdac1, and Syn2). Further, Nfe2l1, Egr1 and Usf2 are sensitive to dietary factors and could be among links between dietary influences and genes in the AD etiology. Thus, this approach of harnessing brain region-specific ISH data represents a rare opportunity for gleaning unique etiological insights for diseases such as AD.
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Heinzel A, Mühlberger I, Stelzer G, Lancet D, Oberbauer R, Martin M, Perco P. Molecular disease presentation in diabetic nephropathy. Nephrol Dial Transplant 2016. [PMID: 26209734 DOI: 10.1093/ndt/gfv267] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Diabetic nephropathy, as the most prevalent chronic disease of the kidney, has also become the primary cause of end-stage renal disease with the incidence of kidney disease in type 2 diabetics continuously rising. As with most chronic diseases, the pathophysiology is multifactorial with a number of deregulated molecular processes contributing to disease manifestation and progression. Current therapy mainly involves interfering in the renin-angiotensin-aldosterone system using angiotensin-converting enzyme inhibitors or angiotensin-receptor blockers. Better understanding of molecular processes deregulated in the early stages and progression of disease hold the key for development of novel therapeutics addressing this complex disease. With the advent of high-throughput omics technologies, researchers set out to systematically study the disease on a molecular level. Results of the first omics studies were mainly focused on reporting the highest deregulated molecules between diseased and healthy subjects with recent attempts to integrate findings of multiple studies on the level of molecular pathways and processes. In this review, we will outline key omics studies on the genome, transcriptome, proteome and metabolome level in the context of DN. We will also provide concepts on how to integrate findings of these individual studies (i) on the level of functional processes using the gene-ontology vocabulary, (ii) on the level of molecular pathways and (iii) on the level of phenotype molecular models constructed based on protein-protein interaction data.
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Affiliation(s)
| | | | - Gil Stelzer
- Weizmann Institute of Science, Rehovot, Israel
| | | | | | - Maria Martin
- EMBL-EBI, Wellcome Trust Genome Campus, Hinxton, UK
| | - Paul Perco
- emergentec biodevelopment GmbH, Vienna, Austria
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21
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Feng H, Gu J, Gou F, Huang W, Gao C, Chen G, Long Y, Zhou X, Yang M, Liu S, Lü S, Luo Q, Xu Y. High Glucose and Lipopolysaccharide Prime NLRP3 Inflammasome via ROS/TXNIP Pathway in Mesangial Cells. J Diabetes Res 2016; 2016:6973175. [PMID: 26881256 PMCID: PMC4736396 DOI: 10.1155/2016/6973175] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 10/12/2015] [Accepted: 10/20/2015] [Indexed: 12/18/2022] Open
Abstract
While inflammation is considered a central component in the development in diabetic nephropathy, the mechanism remains unclear. The NLRP3 inflammasome acts as both a sensor and a regulator of the inflammatory response. The NLRP3 inflammasome responds to exogenous and endogenous danger signals, resulting in cleavage of procaspase-1 and activation of cytokines IL-1β, IL-18, and IL-33, ultimately triggering an inflammatory cascade reaction. This study observed the expression of NLRP3 inflammasome signaling stimulated by high glucose, lipopolysaccharide, and reactive oxygen species (ROS) inhibitor N-acetyl-L-cysteine in glomerular mesangial cells, aiming to elucidate the mechanism by which the NLRP3 inflammasome signaling pathway may contribute to diabetic nephropathy. We found that the expression of thioredoxin-interacting protein (TXNIP), NLRP3, and IL-1β was observed by immunohistochemistry in vivo. Simultaneously, the mRNA and protein levels of TXNIP, NLRP3, procaspase-1, and IL-1β were significantly induced by high glucose concentration and lipopolysaccharide in a dose-dependent and time-dependent manner in vitro. This induction by both high glucose and lipopolysaccharide was significantly inhibited by N-acetyl-L-cysteine. Our results firstly reveal that high glucose and lipopolysaccharide activate ROS/TXNIP/ NLRP3/IL-1β inflammasome signaling in glomerular mesangial cells, suggesting a mechanism by which inflammation may contribute to the development of diabetic nephropathy.
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Affiliation(s)
- Hong Feng
- Department of Endocrinology, Affiliated Hospital of Luzhou Medical College, Luzhou, Sichuan 646000, China
- Department of Internal Medicine, Nan'an District People's Hospital, Chongqing 400060, China
| | - Junling Gu
- Department of Endocrinology, The Fifth People's Hospital of Chongqing, Chongqing 400062, China
| | - Fang Gou
- Department of Endocrinology, Affiliated Hospital of Luzhou Medical College, Luzhou, Sichuan 646000, China
| | - Wei Huang
- Department of Endocrinology, Affiliated Hospital of Luzhou Medical College, Luzhou, Sichuan 646000, China
| | - Chenlin Gao
- Department of Endocrinology, Affiliated Hospital of Luzhou Medical College, Luzhou, Sichuan 646000, China
| | - Guo Chen
- Department of Endocrinology, Affiliated Hospital of Luzhou Medical College, Luzhou, Sichuan 646000, China
| | - Yang Long
- Department of Endocrinology, Affiliated Hospital of Luzhou Medical College, Luzhou, Sichuan 646000, China
| | - Xueqin Zhou
- Department of Endocrinology, Affiliated Hospital of Luzhou Medical College, Luzhou, Sichuan 646000, China
| | - Maojun Yang
- Department of Endocrinology, Affiliated Hospital of Luzhou Medical College, Luzhou, Sichuan 646000, China
| | - Shuang Liu
- Department of Endocrinology, Affiliated Hospital of Luzhou Medical College, Luzhou, Sichuan 646000, China
| | - Shishi Lü
- Department of Endocrinology, Affiliated Hospital of Luzhou Medical College, Luzhou, Sichuan 646000, China
| | - Qiaoyan Luo
- Department of Endocrinology, Affiliated Hospital of Luzhou Medical College, Luzhou, Sichuan 646000, China
| | - Yong Xu
- Department of Endocrinology, Affiliated Hospital of Luzhou Medical College, Luzhou, Sichuan 646000, China
- *Yong Xu:
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22
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Dong D, Fu N, Yang P. MiR-17 Downregulation by High Glucose Stabilizes Thioredoxin-Interacting Protein and Removes Thioredoxin Inhibition on ASK1 Leading to Apoptosis. Toxicol Sci 2015; 150:84-96. [PMID: 26660634 DOI: 10.1093/toxsci/kfv313] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Pregestational diabetes significantly increases the risk of neural tube defects (NTDs). Maternal diabetes activates an Apoptosis Signal-regulating Kinase 1 (ASK1)-initiated pathway, which triggers neural stem cell apoptosis of the developing neuroepithelium leading to NTD formation. How high glucose of diabetes activates ASK1 is still unclear. In this study, we investigated the mechanism underlying high glucose-induced ASK1 activation. High glucose suppressed miR-17 expression, which led to an increase in its target gene Txnip (Thioredoxin-interacting protein). High glucose-increased Txnip enhanced its binding to the ASK1 inhibitor, thioredoxin (Trx), and thereby sequestered Trx from the Trx-ASK1 complex. High glucose-induced ASK1 activation and consequent apoptosis were abrogated by either the miR-17 mimic or Txnip siRNA knockdown. In contrast, the miR-17 inhibitor or Txnip ectopic overexpression mimicked the stimulative effect of high glucose on ASK1 and apoptosis. Thus, our study demonstrated that miR-17 repression mediates the pro-apoptotic effect of high glucose, and revealed a new mechanism underlying ASK1 activation, in which decreased miR-17 removes Trx inhibition on ASK1 through Txnip.
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Affiliation(s)
- Daoyin Dong
- *Department of Obstetrics, Gynecology and Reproductive Sciences
| | - Noah Fu
- *Department of Obstetrics, Gynecology and Reproductive Sciences
| | - Peixin Yang
- *Department of Obstetrics, Gynecology and Reproductive Sciences; Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201
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Nephroprotective role of dipyridamole in diabetic nephropathy: Effect on inflammation and apoptosis. Life Sci 2015; 143:8-17. [DOI: 10.1016/j.lfs.2015.10.026] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 10/12/2015] [Accepted: 10/23/2015] [Indexed: 02/07/2023]
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24
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Coucha M, Elshaer SL, Eldahshan WS, Mysona BA, El-Remessy AB. Molecular mechanisms of diabetic retinopathy: potential therapeutic targets. Middle East Afr J Ophthalmol 2015; 22:135-44. [PMID: 25949069 PMCID: PMC4411608 DOI: 10.4103/0974-9233.154386] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Diabetic retinopathy (DR) is the leading cause of blindness in working-age adults in United States. Research indicates an association between oxidative stress and the development of diabetes complications. However, clinical trials with general antioxidants have failed to prove effective in diabetic patients. Mounting evidence from experimental studies that continue to elucidate the damaging effects of oxidative stress and inflammation in both vascular and neural retina suggest its critical role in the pathogenesis of DR. This review will outline the current management of DR as well as present potential experimental therapeutic interventions, focusing on molecules that link oxidative stress to inflammation to provide potential therapeutic targets for treatment or prevention of DR. Understanding the biochemical changes and the molecular events under diabetic conditions could provide new effective therapeutic tools to combat the disease.
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Affiliation(s)
- Maha Coucha
- Department of Clinical Pharmacy, Program in Clinical and Experimental Therapeutics, University of Georgia, Georgia, USA ; Culver Vision Discovery Institute, Georgia Regents University, Georgia, USA ; Research Service, Charlie Norwood VA Medical Center, Augusta 30912, Georgia, USA
| | - Sally L Elshaer
- Department of Clinical Pharmacy, Program in Clinical and Experimental Therapeutics, University of Georgia, Georgia, USA ; Culver Vision Discovery Institute, Georgia Regents University, Georgia, USA ; Research Service, Charlie Norwood VA Medical Center, Augusta 30912, Georgia, USA
| | - Wael S Eldahshan
- Department of Clinical Pharmacy, Program in Clinical and Experimental Therapeutics, University of Georgia, Georgia, USA ; Culver Vision Discovery Institute, Georgia Regents University, Georgia, USA ; Research Service, Charlie Norwood VA Medical Center, Augusta 30912, Georgia, USA
| | - Barbara A Mysona
- Department of Clinical Pharmacy, Program in Clinical and Experimental Therapeutics, University of Georgia, Georgia, USA ; Culver Vision Discovery Institute, Georgia Regents University, Georgia, USA ; Research Service, Charlie Norwood VA Medical Center, Augusta 30912, Georgia, USA
| | - Azza B El-Remessy
- Department of Clinical Pharmacy, Program in Clinical and Experimental Therapeutics, University of Georgia, Georgia, USA ; Culver Vision Discovery Institute, Georgia Regents University, Georgia, USA ; Research Service, Charlie Norwood VA Medical Center, Augusta 30912, Georgia, USA
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Shah A, Xia L, Masson EAY, Gui C, Momen A, Shikatani EA, Husain M, Quaggin S, John R, Fantus IG. Thioredoxin-Interacting Protein Deficiency Protects against Diabetic Nephropathy. J Am Soc Nephrol 2015; 26:2963-77. [PMID: 25855771 DOI: 10.1681/asn.2014050528] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 01/22/2015] [Indexed: 12/24/2022] Open
Abstract
Expression of thioredoxin-interacting protein (TxNIP), an endogenous inhibitor of the thiol oxidoreductase thioredoxin, is augmented by high glucose (HG) and promotes oxidative stress. We previously reported that TxNIP-deficient mesangial cells showed protection from HG-induced reactive oxygen species, mitogen-activated protein kinase phosphorylation, and collagen expression. Here, we investigated the potential role of TxNIP in the pathogenesis of diabetic nephropathy (DN) in vivo. Wild-type (WT) control, TxNIP(-/-), and TxNIP(+/-) mice were rendered equally diabetic with low-dose streptozotocin. In contrast to effects in WT mice, diabetes did not increase albuminuria, proteinuria, serum cystatin C, or serum creatinine levels in TxNIP(-/-) mice. Whereas morphometric studies of kidneys revealed a thickened glomerular basement membrane and effaced podocytes in the diabetic WT mice, these changes were absent in the diabetic TxNIP(-/-) mice. Immunohistochemical analysis revealed significant increases in the levels of glomerular TGF-β1, collagen IV, and fibrosis only in WT diabetic mice. Additionally, only WT diabetic mice showed significant increases in oxidative stress (nitrotyrosine, urinary 8-hydroxy-2-deoxy-guanosine) and inflammation (IL-1β mRNA, F4/80 immunohistochemistry). Expression levels of Nox4-encoded mRNA and protein increased only in the diabetic WT animals. A significant loss of podocytes, assessed by Wilms' tumor 1 and nephrin staining and urinary nephrin concentration, was found in diabetic WT but not TxNIP(-/-) mice. Furthermore, in cultured human podocytes exposed to HG, TxNIP knockdown with siRNA abolished the increased mitochondrial O2 (-) generation and apoptosis. These data indicate that TxNIP has a critical role in the progression of DN and may be a promising therapeutic target.
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Affiliation(s)
- Anu Shah
- Department of Medicine and Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto General Research Institute, University Health Network, Department of Physiology, Banting and Best Diabetes Centre, and
| | - Ling Xia
- Department of Medicine and Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto General Research Institute, University Health Network, Banting and Best Diabetes Centre, and
| | - Elodie A Y Masson
- Department of Medicine and Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Banting and Best Diabetes Centre, and
| | - Chloe Gui
- Department of Medicine and Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Banting and Best Diabetes Centre, and
| | - Abdul Momen
- Toronto General Research Institute, University Health Network
| | - Eric A Shikatani
- Toronto General Research Institute, University Health Network, Department of Pathology and Laboratory Medicine, University of Toronto, Toronto, Ontario, Canada, and
| | - Mansoor Husain
- Toronto General Research Institute, University Health Network
| | - Susan Quaggin
- Department of Medicine and Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Banting and Best Diabetes Centre, and Feinberg Cardiovascular Research Institute, Division of Medicine-Nephrology, Northwestern Feinberg School of Medicine, Chicago, Illinois
| | - Rohan John
- Toronto General Research Institute, University Health Network, Department of Pathology and Laboratory Medicine, University of Toronto, Toronto, Ontario, Canada, and
| | - I G Fantus
- Department of Medicine and Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto General Research Institute, University Health Network, Department of Physiology, Banting and Best Diabetes Centre, and
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Tan CYR, Weier Q, Zhang Y, Cox AJ, Kelly DJ, Langham RG. Thioredoxin-interacting protein: a potential therapeutic target for treatment of progressive fibrosis in diabetic nephropathy. Nephron Clin Pract 2015; 129:109-27. [PMID: 25662516 DOI: 10.1159/000368238] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Accepted: 09/04/2014] [Indexed: 11/19/2022] Open
Abstract
Thioredoxin-interacting protein (TXNIP) is an endogenous inhibitor of the antioxidant thioredoxin, and a critical agent in the in vivo regulation of glucose. The well-described induction of TXNIP by high glucose may represent an important pathogenic trigger of complications arising in the diabetic environment, with sustained overexpression of TXNIP triggering the increased production of reactive oxygen species and collagen, both major contributors to the development of diabetic nephropathy (DN). To examine a possible therapeutic role for targeted TXNIP inhibition in DN, transgenic (mRen-2)27 rats were rendered diabetic with streptozotocin and then treated with 20 μM TXNIP deoxyribozyme (DNAzyme) delivered continuously over 12 weeks by an implanted osmotic mini-pump. Renal injury was measured using biochemical parameters of kidney function along with histological markers of damage. Catalytic activity of TXNIP DNAzyme was determined by TXNIP gene and peptide expression in the rat kidneys. TXNIP DNAzyme localization was demonstrated with a fluorescent-labelled TXNIP DNAzyme. A panel of markers was used to assess the extent of oxidative stress and renal fibrosis including superoxide level, nitrotyrosine staining, TGF-β1, NLRP3 and collagen IV expression. Fluorescent-labelled TXNIP DNAzyme was localized to tubulo-epithelial cells, but was not identified in glomeruli or endothelial cells. Elevated renal cortical TXNIP gene and protein expression seen in kidneys of DN animals were significantly attenuated by TXNIP DNAzyme (p < 0.05). Downstream markers of TXNIP activity, particularly oxidative stress, inflammasome signalling, tubulo-interstitial fibrosis and collagen deposition, were also attenuated in the tubulo-interstitium of DN rats treated with TXNIP DNAzyme. Consistent with the identified site of action of the DNAzyme, the effects of the TXNIP inhibition were limited to the tubulo-interstitial compartment. This study supports the role of TXNIP as an important mediator of progressive tubulo-interstitial fibrosis in DN, and also supports the notion of TXNIP inhibition as a potential new therapeutic target for DN.
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Affiliation(s)
- Christina Y R Tan
- Department of Medicine, St. Vincent's Hospital, University of Melbourne, Fitzroy, Vic., Australia
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27
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Ganguly R, Sahu S, Chavez RJ, Raman P. Trivalent chromium inhibits TSP-1 expression, proliferation, and O-GlcNAc signaling in vascular smooth muscle cells in response to high glucose in vitro. Am J Physiol Cell Physiol 2014; 308:C111-22. [PMID: 25354527 DOI: 10.1152/ajpcell.00256.2014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Trivalent chromium (Cr(3+)) is a mineral nutrient reported to have beneficial effects in glycemic and cardiovascular health. In vitro and in vivo studies suggest that Cr(3+) supplementation reduces the atherogenic potential and lowers the risk of vascular inflammation in diabetes. However, effects of Cr(3+) in vascular cells under conditions of hyperglycemia, characteristic of diabetes, remain unknown. In the present study we show that a therapeutically relevant concentration of Cr(3+) (100 nM) significantly downregulates a potent proatherogenic matricellular protein, thrombospondin-1 (TSP-1), in human aortic smooth muscle cells (HASMC) stimulated with high glucose in vitro. Promoter-reporter assays reveal that this downregulation of TSP-1 expression by Cr(3+) occurs at the level of transcription. The inhibitory effects of Cr(3+) on TSP-1 were accompanied by significant reductions in O-glycosylation of cytoplasmic and nuclear proteins. Using Western blotting and immunofluorescence studies, we demonstrate that reduced protein O-glycosylation by Cr(3+) is mediated via inhibition of glutamine: fructose 6-phosphate amidotransferase, a rate-limiting enzyme of the hexosamine pathway, and O-linked N-acetylglucosamine (O-GlcNAc) transferase, a distal enzyme in the pathway that controls intracellular protein O-glycosylation. Additionally, we found that Cr(3+) attenuates reactive oxygen species formation in glucose-stimulated HASMC, suggesting an antioxidant effect. Finally, we report an antiproliferative effect of Cr(3+) that is specific for high glucose and conditions triggering elevated protein O-glycosylation. Taken together, these findings provide the first cellular evidence for a novel role of Cr(3+) to modulate aberrant vascular smooth muscle cell function associated with hyperglycemia-induced vascular complications.
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Affiliation(s)
- Rituparna Ganguly
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, Ohio; and School of Biomedical Sciences, Kent State University, Kent, Ohio
| | - Soumyadip Sahu
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, Ohio; and School of Biomedical Sciences, Kent State University, Kent, Ohio
| | - Ronaldo J Chavez
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, Ohio; and
| | - Priya Raman
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, Ohio; and School of Biomedical Sciences, Kent State University, Kent, Ohio
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28
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Connelly KA, Advani A, Advani SL, Zhang Y, Kim YM, Shen V, Thai K, Kelly DJ, Gilbert RE. Impaired cardiac anti-oxidant activity in diabetes: human and correlative experimental studies. Acta Diabetol 2014; 51:771-82. [PMID: 24925443 DOI: 10.1007/s00592-014-0608-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Accepted: 05/28/2014] [Indexed: 02/06/2023]
Abstract
Increased reactive oxygen species (ROS) are traditionally viewed as arising from the metabolic flux of diabetes, although reduction in the activity of anti-oxidant systems has also been implicated. Among the latter is the major thiol reducing thioredoxin system, the activity of which may be diminished by high glucose-induced expression of its endogenous inhibitor, thioredoxin interacting protein (TxnIP). We assessed TxnIP mRNA/protein expression along with thioredoxin activity in human right atrial biopsy specimens from subjects with and without diabetes undergoing coronary artery grafting. In correlative experimental studies, we examined TxnIP expression in both type 1 and type 2 rodent models of diabetic cardiomyopathy. Finally, we used in vitro gene silencing to determine the contribution of changes in TxnIP abundance to the high glucose-induced reduction in thioredoxin activity. In human right atrial biopsies, diabetes was associated with a >30-fold increase in TxnIP gene expression and a 17 % increase in TxnIP protein expression (both p < 0.05). This was associated with a 21 % reduction in thioredoxin activity when compared to human non-diabetic cardiac biopsy samples (all p < 0.05). In correlative animal studies, both type 1 and type 2 diabetic rats demonstrated a significant increase in TxnIP mRNA and reduction in thioredoxin activity when compared to non-diabetic animals (all p < 0.05). This was associated with a significant increase in ROS (p < 0.05 when compared with control). In cultured cardiac myocytes, high glucose increased ROS and TxnIP mRNA expression, in association with a reduction in thioredoxin activity (p < 0.01). These findings were abrogated by TxnIP small interfering RNA (siRNA). Scrambled siRNA had no effect upon ROS or TxnIP expression. High glucose reduces thioredoxin activity and increases ROS via TxnIP overexpression. These findings suggest that impaired thiol reductive capacity, through altered TxnIP expression, contributes to increased ROS in the diabetic heart.
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Affiliation(s)
- Kim A Connelly
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, 30 Bond St, 209 Victoria Street, Room 7-052, Toronto, ON, M5B 1W8, Canada,
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29
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Zhuang A, Forbes JM. Stress in the kidney is the road to pERdition: is endoplasmic reticulum stress a pathogenic mediator of diabetic nephropathy? J Endocrinol 2014; 222:R97-111. [PMID: 24982467 DOI: 10.1530/joe-13-0517] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The endoplasmic reticulum (ER) is an organelle that primarily functions to synthesise new proteins and degrade old proteins. Owing to the continual and variable nature of protein turnover, protein synthesis is inherently an error-prone process and is therefore tightly regulated. Fortunately, if this balance between synthesis and degradation is perturbed, an intrinsic response, the unfolded protein response (UPR) is activated to restore ER homoeostasis through the action of inositol-requiring protein 1, activating transcription factor 6 and PKR-like ER kinase transmembrane sensors. However, if the UPR is oversaturated and misfolded proteins accumulate, the ER can shift into a cytotoxic response, a physiological phenomenon known as ER stress. The mechanistic pathways of the UPR have been extensively explored; however, the role of this process in such a synthetic organ as the kidney requires further clarification. This review will focus on these aspects and will discuss the role of ER stress in specific resident kidney cells and how this may be integral in the pathogenesis and progression of diabetic nephropathy (DN). Given that diabetes is a perturbed state of protein turnover in most tissues, it is important to understand if ER stress is a secondary or tertiary response to other changes within the diabetic milieu or if it is an independent accelerator of kidney disease. Modulators of ER stress could provide a valuable tool for the treatment of DN and are under active investigation in other contexts.
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Affiliation(s)
- Aowen Zhuang
- Glycation and Diabetes GroupMater Research Institute - The University of Queensland, Translational Research Institute, 37 Kent Street, Woolloongabba, South Brisbane, Queensland, AustraliaMater Clinical SchoolThe University of Queensland, South Brisbane, Queensland, Australia
| | - Josephine M Forbes
- Glycation and Diabetes GroupMater Research Institute - The University of Queensland, Translational Research Institute, 37 Kent Street, Woolloongabba, South Brisbane, Queensland, AustraliaMater Clinical SchoolThe University of Queensland, South Brisbane, Queensland, AustraliaGlycation and Diabetes GroupMater Research Institute - The University of Queensland, Translational Research Institute, 37 Kent Street, Woolloongabba, South Brisbane, Queensland, AustraliaMater Clinical SchoolThe University of Queensland, South Brisbane, Queensland, Australia
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30
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Hsu YC, Lee PH, Lei CC, Ho C, Shih YH, Lin CL. Nitric oxide donors rescue diabetic nephropathy through oxidative-stress-and nitrosative-stress-mediated Wnt signaling pathways. J Diabetes Investig 2014; 6:24-34. [PMID: 25621130 PMCID: PMC4296700 DOI: 10.1111/jdi.12244] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2013] [Revised: 03/14/2014] [Accepted: 04/06/2014] [Indexed: 12/13/2022] Open
Abstract
AIMS/INTRODUCTION The role of the renal nitric oxide (NO) system in the pathophysiology of diabetic nephropathy constitutes a very challenging and fertile field for future investigation. The purpose of the present study was to investigate whether NO donors can attenuate diabetic renal fibrosis and apoptosis through modulating oxidative-and nitrosative-stress, and Wnt signaling using in vivo diabetic models. MATERIALS AND METHODS Diabetic rat was induced by a single intraperitoneal injection of streptozotocin. Rats in each group were intraperitoneally given 2,2'-(hydroxynitrosohydrazino)bis-ethanamine (1 U/kg/day) and vehicle for 28 and 56 consecutive days. Expression of the oxidative-and nitrosative-stress, and Wnt signaling components were examined in kidneys from diabetic animals by quantitative reverse transcription polymerase chain reaction, western blot analysis and immunohistochemical staining. RESULTS NO donor treatment significantly reduced the ratio of kidney weight to bodyweight and proteinuria. This treatment also significantly restored the suppressive effect of diabetes on urinary NO2 + NO3 levels. Immunohistochemistry showed that NO donor treatment significantly reduced transforming growth factor (TGF)-β1, fibronectin, cleaved caspase-3 and triphosphate-biotin nick end-labeling expression in the glomeruli of diabetic rats. We found that diabetes promoted 8-hydroxy-2'-deoxyguanosine, and peroxynitrite expression coincided with reduced endothelial NO synthase expression in glomeruli. Interestingly, NO donor treatment completely removed oxidative stress and nitrosative stress, and restored endothelial NO synthase expression in diabetic renal glomeruli. Immunohistomorphometry results showed that NO donor treatment significantly restored suppressed Wnt5a expression and β-catenin immunoreactivities in glomeruli. Based on laser-captured microdissection for quantitative reverse transcription polymerase chain reaction, diabetes significantly increased TGF-β1, and fibronectin expression coincided with depressed Wnt5a expression. NO donor treatment reduced TGF-β1, fibronectin activation, and the suppressing effect of diabetes on Wnt5a and β-catenin expression in renal glomeruli. CONCLUSIONS NO donor treatment alleviates extracellular matrix accumulation and apoptosis in diabetic nephropathy in vivo by not only preventing the diabetes-mediated oxidative and nitrostative stress, but also restoring downregulation of endothelial NO synthase expression and Wnt/β-catenin signaling. These findings suggest that modulation of NO is a viable alternative strategy for rescuing diabetic renal injury.
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Affiliation(s)
- Yung-Chien Hsu
- Department of Nephrology, Chang Gung Memorial Hospital Chiayi, Taiwan ; Department of Kidney and Diabetic Complications Research Team (KDCRT), Chang Gung Memorial Hospital Chiayi, Taiwan ; Chronic Kidney Disease Center, Chang Gung Memorial Hospital Chiayi, Taiwan ; Division of Endocrinology and Metabolism, Chang Gung Memorial Hospital Chiayi, Taiwan
| | - Pei-Hsien Lee
- Department of Nephrology, Chang Gung Memorial Hospital Chiayi, Taiwan ; Department of Kidney and Diabetic Complications Research Team (KDCRT), Chang Gung Memorial Hospital Chiayi, Taiwan ; Chronic Kidney Disease Center, Chang Gung Memorial Hospital Chiayi, Taiwan ; Division of Endocrinology and Metabolism, Chang Gung Memorial Hospital Chiayi, Taiwan
| | - Chen-Chou Lei
- Department of Nephrology, Chang Gung Memorial Hospital Chiayi, Taiwan ; Department of Kidney and Diabetic Complications Research Team (KDCRT), Chang Gung Memorial Hospital Chiayi, Taiwan ; Chronic Kidney Disease Center, Chang Gung Memorial Hospital Chiayi, Taiwan ; Division of Endocrinology and Metabolism, Chang Gung Memorial Hospital Chiayi, Taiwan
| | - Cheng Ho
- Division of Endocrinology and Metabolism, Chang Gung Memorial Hospital Chiayi, Taiwan
| | - Ya-Hsueh Shih
- Department of Nephrology, Chang Gung Memorial Hospital Chiayi, Taiwan ; Department of Kidney and Diabetic Complications Research Team (KDCRT), Chang Gung Memorial Hospital Chiayi, Taiwan ; Chronic Kidney Disease Center, Chang Gung Memorial Hospital Chiayi, Taiwan
| | - Chun-Liang Lin
- Department of Nephrology, Chang Gung Memorial Hospital Chiayi, Taiwan ; Department of Kidney and Diabetic Complications Research Team (KDCRT), Chang Gung Memorial Hospital Chiayi, Taiwan ; Chronic Kidney Disease Center, Chang Gung Memorial Hospital Chiayi, Taiwan ; School of Traditional Chinese Medicine, Chang Gung University College of Medicine Tao-Yuan, Taiwan
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31
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Fadini GP, Cappellari R, Mazzucato M, Agostini C, Vigili de Kreutzenberg S, Avogaro A. Monocyte-macrophage polarization balance in pre-diabetic individuals. Acta Diabetol 2013; 50:977-82. [PMID: 24085683 DOI: 10.1007/s00592-013-0517-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Accepted: 09/24/2013] [Indexed: 12/31/2022]
Abstract
Pre-diabetes is characterized by increased cardiovascular risk and chronic inflammation. The activation of monocyte-macrophages plays major roles in vascular biology. Herein, we aimed to analyze monocyte-macrophage polarization status in subjects with IFG and/or IGT compared with normal glucose tolerant (NGT) individuals. We enrolled 87 middle-aged individuals with low prevalence of cardiovascular disease. Based on OGTT, they were divided into 49 NGT and 38 pre-diabetic (IFG and/or IGT). Using flow cytometry analysis of peripheral blood cells, we quantified traditional monocyte subsets based on CD14 and CD16 expression as well as novel monocyte-macrophage pro-inflammatory CD68(+)CCR2(+) M1 and anti-inflammatory CX3CR1(+)CD163(+)/CD206(+) M2 phenotypes. The M1/M2 ratio was taken to represent the polarization balance. There were no differences in traditional classical (CD14(++)CD16(-)), intermediate (CD14(++)CD16(+)) and nonclassical (CD14(+)CD16(+)) monocytes between groups. Rather, compared to NGT, pre-diabetic subjects showed a significant increase in pro-inflammatory M1 cells and percent expression of the oxLDL scavenger receptor CD68, without changes in anti-inflammatory M2 cells. M1 levels and CD68 expression were directly correlated with HbA1c. We show for the first time that otherwise healthy pre-diabetic subjects have excess M1 inflammatory cells in peripheral blood, which may contribute to cardiovascular risk.
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Affiliation(s)
- Gian Paolo Fadini
- Department of Medicine, Policlinico Universitario, Via Giustiniani, 2, 35100, Padua, Italy,
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Devi TS, Hosoya KI, Terasaki T, Singh LP. Critical role of TXNIP in oxidative stress, DNA damage and retinal pericyte apoptosis under high glucose: implications for diabetic retinopathy. Exp Cell Res 2013; 319:1001-12. [PMID: 23353834 PMCID: PMC5658006 DOI: 10.1016/j.yexcr.2013.01.012] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 01/12/2013] [Accepted: 01/15/2013] [Indexed: 11/28/2022]
Abstract
Diabetic retinopathy (DR) is characterized by early loss of retinal capillary pericytes and microvascular dysfunction. We recently showed that pro-oxidative stress and pro-apoptotic thioredoxin interacting protein (TXNIP) is significantly up-regulated in rat retinas in experimental diabetes and mediates inflammation and apoptosis. Therefore, we hypothesize here that TXNIP up-regulation in pericyte plays a causative role in oxidative stress and apoptosis under sustained high glucose exposure in culture. We maintained a rat retinal capillary pericyte cell line (TR-rPCT1) for 5 days under low glucose (LG, 5.5mM) or high glucose (HG, 25 mM) with or without anti-oxidant N-acetylcysteine (5mM, NAC), Azaseine (2 μM, AzaS), an inhibitor of TXNIP, and TXNIP siRNA (siTXNIP3, 20 nM). The results show that HG increases TXNIP expression in TR-rPCT1, which correlates positively with ROS generation, protein S-nitrosylation, and pro-apoptotic caspase-3 activation. Furthermore, pericyte apoptosis is demonstrated by DNA fragmentation (alkaline comet assay) and a reduction in MTT survival assay. Treatment of TR-rPCT1 with NAC or an inhibition of TXNIP by AzaS or siTXNIP3 each reduces HG-induced ROS, caspase-3 activation and DNA damage demonstrating that TXNIP up-regulation under chronic hyperglycemia is critically involved in cellular oxidative stress, DNA damage and retinal pericyte apoptosis. Thus, TXNIP represents a novel gene and drug target to prevent pericyte loss and progression of DR.
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Affiliation(s)
- Takhellambam S. Devi
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Ken-Ichi Hosoya
- Department of Pharmaceutics, Graduate School of Medical and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
| | - Tetsuya Terasaki
- Department of Molecular Biopharmacy and Genetics, Tohoku University, Sendai 980-8578, Japan
| | - Lalit P. Singh
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI, USA
- Department of Ophthalmology, Wayne State University School of Medicine, Detroit, MI, USA
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Lee S, Kim SM, Lee RT. Thioredoxin and thioredoxin target proteins: from molecular mechanisms to functional significance. Antioxid Redox Signal 2013; 18:1165-207. [PMID: 22607099 PMCID: PMC3579385 DOI: 10.1089/ars.2011.4322] [Citation(s) in RCA: 268] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The thioredoxin (Trx) system is one of the central antioxidant systems in mammalian cells, maintaining a reducing environment by catalyzing electron flux from nicotinamide adenine dinucleotide phosphate through Trx reductase to Trx, which reduces its target proteins using highly conserved thiol groups. While the importance of protecting cells from the detrimental effects of reactive oxygen species is clear, decades of research in this field revealed that there is a network of redox-sensitive proteins forming redox-dependent signaling pathways that are crucial for fundamental cellular processes, including metabolism, proliferation, differentiation, migration, and apoptosis. Trx participates in signaling pathways interacting with different proteins to control their dynamic regulation of structure and function. In this review, we focus on Trx target proteins that are involved in redox-dependent signaling pathways. Specifically, Trx-dependent reductive enzymes that participate in classical redox reactions and redox-sensitive signaling molecules are discussed in greater detail. The latter are extensively discussed, as ongoing research unveils more and more details about the complex signaling networks of Trx-sensitive signaling molecules such as apoptosis signal-regulating kinase 1, Trx interacting protein, and phosphatase and tensin homolog, thus highlighting the potential direct and indirect impact of their redox-dependent interaction with Trx. Overall, the findings that are described here illustrate the importance and complexity of Trx-dependent, redox-sensitive signaling in the cell. Our increasing understanding of the components and mechanisms of these signaling pathways could lead to the identification of new potential targets for the treatment of diseases, including cancer and diabetes.
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Affiliation(s)
- Samuel Lee
- The Harvard Stem Cell Institute, Cambridge, MA, USA
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Shah A, Xia L, Goldberg H, Lee KW, Quaggin SE, Fantus IG. Thioredoxin-interacting protein mediates high glucose-induced reactive oxygen species generation by mitochondria and the NADPH oxidase, Nox4, in mesangial cells. J Biol Chem 2013; 288:6835-48. [PMID: 23329835 DOI: 10.1074/jbc.m112.419101] [Citation(s) in RCA: 124] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Thioredoxin-interacting protein (TxNIP) is up-regulated by high glucose and is associated with oxidative stress. It has been implicated in hyperglycemia-induced β-cell dysfunction and apoptosis. As high glucose and oxidative stress mediate diabetic nephropathy (DN), the contribution of TxNIP was investigated in renal mesangial cell reactive oxygen species (ROS) generation and collagen synthesis. To determine the role of TxNIP, mouse mesangial cells (MC) cultured from wild-type C3H and TxNIP-deficient Hcb-19 mice were incubated in HG. Confocal microscopy was used to measure total and mitochondrial ROS production (DCF and MitoSOX) and collagen IV. Trx and NADPH oxidase activities were assayed and NADPH oxidase isoforms, Nox2 and Nox4, and antioxidant enzymes were determined by immunoblotting. C3H MC exposed to HG elicited a significant increase in cellular and mitochondrial ROS as well as Nox4 protein expression and NADPH oxidase activation, whereas Hcb-19 MC showed no response. Trx activity was attenuated by HG only in C3H MC. These defects in Hcb-19 MC were not due to increased antioxidant enzymes or scavenging of ROS, but associated with decreased ROS generation. Adenovirus-mediated overexpression of TxNIP in Hcb-19 MC and TxNIP knockdown with siRNA in C3H confirmed the specific role of TxNIP. Collagen IV accumulation in HG was markedly reduced in Hcb-19 cells. TxNIP is a critical component of the HG-ROS signaling pathway, required for the induction of mitochondrial and total cell ROS and the NADPH oxidase isoform, Nox4. TxNIP is a potential target to prevent DN.
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Affiliation(s)
- Anu Shah
- Department of Medicine and Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario M5T 3L9, Canada
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Abstract
Chronic hyperglycemia (HG)-associated reactive oxygen/nitrogen species (ROS/RNS) stress and low grade inflammation are considered to play critical roles in the development of diabetic retinopathy (DR). Excess glucose metabolic flux through the aldose reductase/polyol pathway, advanced glycation end product (AGE) formation, elevated hexosamine biosynthesis pathway (HBP), diacyl glycerol/PKC activation, and mitochondrial ROS generation are all implicated in DR. In addition, endoplasmic reticulum stress/unfolded protein response (er-UPR) and deregulation of mitochondrial quality control by autophagy/mitophagy are observed causing cellular bioenergetic deficiency and injury. Recently, a pro-oxidant and pro-apoptotic thioredoxin interacting protein (TXNIP) was shown to be highly upregulated in DR and by HG in retinal cells in culture. TXNIP binds to thioredoxin (Trx) inhibiting its oxidant scavenging and thiolreducing capacity. Hence, prolonged overexpression of TXNIP causes ROS/RNS stress, mitochondrial dysfunction, inflammation and premature cell death in DR. Initially, DR was considered as microvascular complications of endothelial dysfunction and pericyte loss characterized by capillary basement membrane thickening, pericyte ghost, blood retinal barrier leakage, acellular capillary and neovascularization. However, it is currently acknowledged that neuro-glia are also affected by HG in diabetes and that neuronal injury, glial activation, innate immunity/sterile inflammation, and ganglion apoptosis occur early in DR. In addition, retinal pigment epithelium (RPE) becomes dysfunctional in DR. Since TXNIP is induced by HG in most cells, its effects are not restricted to a particular cell type in DR. However, depending on the metabolic activity and anti-oxidant capacity, some cells may be affected earlier by TXNIP than others. Identification of TXNIP sensitive cells and elucidating the underlying mechanism(s) will be critical for preventing pre-mature cell death and progression of DR.
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Affiliation(s)
- Lalit P Singh
- Departments of Anatomy and Cell Biology and Ophthalmology, Wayne State University School of Medicine, Detroit, MI 48201, USA
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Theophylline regulates inflammatory and neurotrophic factor signals in functional recovery after C2-hemisection in adult rats. Exp Neurol 2012; 238:79-88. [PMID: 22981449 DOI: 10.1016/j.expneurol.2012.08.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Revised: 08/09/2012] [Accepted: 08/11/2012] [Indexed: 11/24/2022]
Abstract
Recovery of respiratory activity in an upper cervical hemisection model (C2H) of spinal cord injury (SCI) can be induced by systemic theophylline administration 24-48 h after injury. The objectives in the present study are (1) to identify pro-inflammatory and neurotrophic factors expressed after C2H and (2) molecular signals involved in functional recovery. Four groups of adult female rats classified as (i) sham (SH) controls, (ii) subjected to a left C2 hemisection (C2H) only, (iii) C2H rats administered theophylline for 3 consecutive days 2 days after C2H (C2H-T day 5) and (iv) C2H rats treated with theophylline for 3 consecutive days 2 days after C2H and then weaned for 12 days (C2H-T day 17) prior to assessment of respiratory function and molecular analysis were employed. Corresponding sham controls, C2H untreated (vehicle only controls) and C2H treated (theophylline) rats were sacrificed, C3-C6 spinal cord segments quickly dissected and left (ipsilateral) hemi spinal cord and right (contralateral) hemi spinal cord were separately harvested 2 days post surgery. Sham operated and C2H untreated-controls corresponding to C2H-T day 5 and C2H-T day 17 rats, respectively, were prepared similarly. Messenger RNA levels for pro-inflammatory genes (TXNIP, IL-1β, TNF-α and iNOS) and neurotrophic and survival factors (BDNF, GDNF, and Bcl2) were analyzed by real time quantitative PCR. Gene expression pattern was unaltered in SH rats. TXNIP, iNOS, BDNF, GDNF and Bcl2 mRNA levels were significantly increased in the ipsilateral hemi spinal cord in C2H rats. BDNF, GDNF and Bcl2 levels remained elevated in the ipsilateral hemi spinal cord in C2H-T day 5 rats. In this same group, there was further enhancement in TXNIP and IL-1β while iNOS returned to basal levels. Theophylline increased DNA binding activity of transcription factors - cyclic AMP responsive element (CRE) binding protein (CREB) and pro-inflammatory NF-κB. Messenger RNA levels for all genes returned to basal levels in C2H-T day 17 rats. However, BDNF mRNA levels remained significantly elevated after weaning from the drug. Our results suggest that enhanced resolution of early inflammatory processes and expression of pro-survival factors may underlie theophylline-induced respiratory recovery. The results identify potential targets for gene and drug therapies.
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Zhang Y, Yuen DA, Advani A, Thai K, Advani SL, Kepecs D, Kabir MG, Connelly KA, Gilbert RE. Early-outgrowth bone marrow cells attenuate renal injury and dysfunction via an antioxidant effect in a mouse model of type 2 diabetes. Diabetes 2012; 61:2114-25. [PMID: 22596053 PMCID: PMC3402311 DOI: 10.2337/db11-1365] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Cell therapy has been extensively investigated in heart disease but less so in the kidney. We considered whether cell therapy also might be useful in diabetic kidney disease. Cognizant of the likely need for autologous cell therapy in humans, we sought to assess the efficacy of donor cells derived from both healthy and diabetic animals. Eight-week-old db/db mice were randomized to receive a single intravenous injection of PBS or 0.5 × 10(6) early-outgrowth cells (EOCs) from db/m or db/db mice. Effects were assessed 4 weeks after cell infusion. Untreated db/db mice developed mesangial matrix expansion and tubular epithelial cell apoptosis in association with increased reactive oxygen species (ROS) and overexpression of thioredoxin interacting protein (TxnIP). Without affecting blood glucose or blood pressure, EOCs not only attenuated mesangial and peritubular matrix expansion, as well as tubular apoptosis, but also diminished ROS and TxnIP overexpression in the kidney of db/db mice. EOCs derived from both diabetic db/db and nondiabetic db/m mice were equally effective in ameliorating kidney injury and oxidative stress. The similarly beneficial effects of cells from healthy and diabetic donors highlight the potential of autologous cell therapy in the related clinical setting.
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TXNIP links innate host defense mechanisms to oxidative stress and inflammation in retinal Muller glia under chronic hyperglycemia: implications for diabetic retinopathy. EXPERIMENTAL DIABETES RESEARCH 2012; 2012:438238. [PMID: 22474421 PMCID: PMC3313582 DOI: 10.1155/2012/438238] [Citation(s) in RCA: 158] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Accepted: 11/27/2011] [Indexed: 12/16/2022]
Abstract
Thioredoxin Interacting Protein (TXNIP) mediates retinal inflammation, gliosis, and apoptosis in experimental diabetes. Here, we investigate the temporal response of Muller glia to high glucose (HG) and TXNIP expression using a rat Muller cell line (rMC1) in culture. We examined if HG-induced TXNIP expression evokes host defense mechanisms in rMC1 in response to metabolic abnormalities. HG causes sustained up-regulation of TXNIP (2 h to 5 days), ROS generation, ATP depletion, ER stress, and inflammation. Various cellular defense mechanisms are activated by HG: (i) NLRP3 inflammasome, (ii) ER stress response (sXBP1), (iii) hypoxic-like HIF-1α induction, (iv) autophagy/mitophagy, and (v) apoptosis. We also found in vivo that streptozocin-induced diabetic rats have higher retinal TXNIP and innate immune response gene expression than normal rats. Knock down of TXNIP by intravitreal siRNA reduces inflammation (IL-1β) and gliosis (GFAP) in the diabetic retina. TXNIP ablation in vitro prevents ROS generation, restores ATP level and autophagic LC3B induction in rMC1. Thus, our results show that HG sustains TXNIP up-regulation in Muller glia and evokes a program of cellular defense/survival mechanisms that ultimately lead to oxidative stress, ER stress/inflammation, autophagy and apoptosis. TXNIP is a potential target to ameliorate blinding ocular complications of diabetic retinopathy.
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Goldberg H, Whiteside C, Fantus IG. O-linked β-N-acetylglucosamine supports p38 MAPK activation by high glucose in glomerular mesangial cells. Am J Physiol Endocrinol Metab 2011; 301:E713-26. [PMID: 21712532 DOI: 10.1152/ajpendo.00108.2011] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Hyperglycemia augments flux through the hexosamine biosynthetic pathway and subsequent O-linkage of single β-N-acetyl-d-glucosamine moieties to serine and threonine residues on cytoplasmic and nuclear proteins (O-GlcNAcylation). Perturbations in this posttranslational modification have been proposed to promote glomerular matrix accumulation in diabetic nephropathy, but clear evidence and mechanism are lacking. We tested the hypothesis that O-GlcNAcylation enhances profibrotic signaling in rat mesangial cells. An adenovirus expressing shRNA directed against O-GlcNAc transferase (OGT) markedly reduced basal and high-glucose-stimulated O-GlcNAcylation. Interestingly, O-GlcNAc depletion prevented high-glucose-induced p38 mitogen-activated protein kinase (MAPK) and c-Jun NH(2)-terminal kinase phosphorylation. Downstream of p38, O-GlcNAc controlled the expression of plasminogen activator inhibitor-1, fibronectin, and transforming growth factor-β, important factors in matrix accumulation in diabetic nephropathy. Treating mesangial cells with thiamet-G, a highly selective inhibitor of O-GlcNAc-specific hexosaminidase (O-GlcNAcase), increased O-GlcNAcylation and p38 phosphorylation. The high-glucose-stimulated kinase activity of apoptosis signal-regulating kinase 1 (ASK1), an upstream MAPK kinase kinase for p38 that is negatively regulated by Akt, was inhibited by OGT shRNA. Akt Thr(308) and Ser(473) phosphorylation were enhanced following OGT shRNA expression in high-glucose-exposed mesangial cells, but high-glucose-induced p38 phosphorylation was not attenuated by OGT shRNA in cells pretreated with the phosphatidylinositol 3-kinase inhibitor LY-294002. OGT shRNA also reduced high-glucose-stimulated reactive oxygen species (ROS) formation. In contrast, diminished O-GlcNAcylation caused elevated ERK phosphorylation and PKCδ membrane translocation. Thus, O-GlcNAcylation is coupled to profibrotic p38 MAPK signaling by high glucose in part through Akt and possibly through ROS.
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Affiliation(s)
- Howard Goldberg
- Department of Medicine, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, ON, Canada
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Ali AA, Lewis SM, Badgley HL, Allaben WT, Leakey JE. Oral glucosamine increases expression of transforming growth factor β1 (TGFβ1) and connective tissue growth factor (CTGF) mRNA in rat cartilage and kidney: Implications for human efficacy and toxicity. Arch Biochem Biophys 2011; 510:11-8. [DOI: 10.1016/j.abb.2011.03.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2011] [Revised: 03/22/2011] [Accepted: 03/25/2011] [Indexed: 02/03/2023]
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Devi TS, Singh LP, Hosoya KI, Terasaki T. GSK-3β/CREB axis mediates IGF-1-induced ECM/adhesion molecule expression, cell cycle progression and monolayer permeability in retinal capillary endothelial cells: Implications for diabetic retinopathy. Biochim Biophys Acta Mol Basis Dis 2011; 1812:1080-8. [PMID: 21549192 DOI: 10.1016/j.bbadis.2011.04.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Revised: 04/07/2011] [Accepted: 04/11/2011] [Indexed: 01/11/2023]
Abstract
Various growth factors and cytokines are implicated in endothelial dysfunction and blood-retinal barrier (BRB) breakdown in early diabetic retinopathy (DR). However, cellular and molecular mechanisms that may underlie the pathology of DR are not fully understood yet. We therefore examined the effect of insulin-like growth factor (IGF)-1 on ECM/adhesion molecule expression, cell cycle regulation and monolayer permeability in an endothelial cell line (TR-iBRB2). We investigate whether the action of IGF-1 (1) involves glycogen synthase kinase 3beta (GSK-3β) and cAMP responsive transcription factor (CREB) and (2) alters ECM/adhesion molecule gene expression. Treatment of TR-iBRB2 cell with IGF-1 (100ng/ml for 0-24h) increases phosphorylation of (i) Akt Thr308, and its substrates including GSK-3β at Ser9, which inactivates its kinase function, and (ii) CREB at Ser133 (activation). These phosphorylations correlate positively with enhanced expression of CREB targets such as ECM protein fibronectin and cell cycle progression factor cyclin D1. However, stable transfection of a mutant GSK3β(S9A) or a dominant negative K-CREB in TR-iBRB2 prevents IGF-1-induced fibronectin and cyclin D1 expression. Furthermore, IGF-1 reduces the level of intercellular adherence molecule VE-cadherin and increases monolayer permeability in TR-iBRB2 cells when measured by FITC-dextran leakage. The effect of IGF-1 on VE-cadherin and membrane permeability is absent in TR-iBRB2 cells expressing the GSK-3β(S9A). Similarly, K-CREB reverses IGF-1 down-regulation of VE-cadherin and up-regulation of fibronectin. These results indicate that GSK-3β/CREB axis alters ECM/adhesion molecule expression and cell cycle progression in retinal endothelial cells, and may potentially contribute to endothelial dysfunction and BRB leakage in DR.
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Affiliation(s)
- Takhellambam S Devi
- Departments of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI 48202, USA
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Park J, Marjani SL, Lai L, Samuel M, Wax D, Davis SR, Bruno RS, Prather RS, Yang X, Tian XC. Altered gene expression profiles in the brain, kidney, and lung of deceased neonatal cloned pigs. Cell Reprogram 2011; 12:589-97. [PMID: 20726773 DOI: 10.1089/cell.2010.0004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Limited studies have been published analyzing the gene expression patterns of cloned pigs. We compared the expression profiles of brain, kidney, and lung tissues, representing each of the three germ layers, of deceased neonatal cloned pigs with those of age-matched controls using a 13K oligonucleotide microarray. We found 42 (0.7% of total genes analyzed), 178 (2.9%), and 121 (1.9%) genes differentially expressed in the brain, kidney, and lung of clones, respectively, when compared with the corresponding organs from controls (fold change >1.5, p < 0.05, false discovery rate (FDR) = 0.05). These expression aberrations could potentially cause the following pathological anomalies in clones: diabetic nephropathy in the kidney and dysregulated surfactant homeostasis in the lung. Interestingly, upregulated expression of genes belonging to the MAPK pathway was observed in all three organs. To investigate whether the differences in levels of gene expression were caused by differential DNA methylation, the global DNA methylation level was measured by high-performance liquid chromatography. In controls, global concentration of methylated cytosine was 5.35%, whereas clones had significantly hypomethylated genomic DNA (4.57%). Bisulfite-pyrosequencing analyses of the promoter regions of differentially expressed candidate genes, c-MYC, Period 1 (PER1), Cathepsin L (CTSL), and Follistatin (FS), however, did not show any differences in the degree of DNA methylation between controls and clones. Our findings demonstrate that deceased neonatal cloned pigs have considerable gene expression abnormalities, which may have contributed to the death of the animals.
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Affiliation(s)
- Joonghoon Park
- Center for Regenerative Biology, Department of Animal Science, University of Connecticut , Storrs, USA
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Shirato K, Nakajima K, Korekane H, Takamatsu S, Gao C, Angata T, Ohtsubo K, Taniguchi N. Hypoxic regulation of glycosylation via the N-acetylglucosamine cycle. J Clin Biochem Nutr 2010; 48:20-5. [PMID: 21297907 PMCID: PMC3022058 DOI: 10.3164/jcbn.11-015fr] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Accepted: 11/12/2010] [Indexed: 11/22/2022] Open
Abstract
Glucose is an energy substrate, as well as the primary source of nucleotide sugars, which are utilized as donor substrates in protein glycosylation. Appropriate glycosylation is necessary to maintain the stability of protein, and is also important in the localization and trafficking of proteins. The dysregulation of glycosylation results in the development of a variety of disorders, such as cancer, diabetes mellitus and emphysema. Glycosylation is kinetically regulated by dynamically changing the portfolio of glycosyltransferases, nucleotide sugars, and nucleotide sugar transporters, which together form a part of what is currently referred to as the ”Glycan cycle”. An excess or a deficiency in the expression of glycosyltransferases has been shown to alter the glycosylation pattern, which subsequently leads to the onset, progression and exacerbation of a number of diseases. Furthermore, alterations in intracellular nucleotide sugar levels can also modulate glycosylation patterns. It is observed that pathological hypoxic microenvironments frequently occur in solid cancers and inflammatory foci. Hypoxic conditions dramatically change gene expression profiles, by activating hypoxia-inducible factor-1, which mediates adaptive cellular responses. Hypoxia-induced glycosyltransferases and nucleotide sugar transporters have been shown to modulate glycosylation patterns that are part of the mechanism associated with cancer metastasis. Hypoxia-inducible factor-1 also induces the expression of glucose transporters and various types of glycolytic enzymes, leading to shifts in glucose metabolic patterns. This fact strongly suggests that hypoxic conditions are an important factor in modulating various nucleotide sugar biosynthetic pathways. This review discusses some of the current thinking of how hypoxia alters glucose metabolic fluxes that can modulate cellular glycosylation patterns and consequently modify cellular functions, particularly from the standpoint of the N-acetylglucosamine cycle, a part of the ”Glycan cycle”.
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Affiliation(s)
- Ken Shirato
- Department of Disease Glycomics, Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
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Sbai O, Devi TS, Melone MAB, Feron F, Khrestchatisky M, Singh LP, Perrone L. RAGE-TXNIP axis is required for S100B-promoted Schwann cell migration, fibronectin expression and cytokine secretion. J Cell Sci 2010; 123:4332-9. [PMID: 21098642 DOI: 10.1242/jcs.074674] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
During peripheral nerve injury, Schwann cells (SCs) adopt a migratory phenotype and remodel the extracellular matrix and provide a supportive activity for neuron regeneration. SCs synthesize neurotrophic factors and cytokines that are crucial for the repair of the injured nerve. The receptor for advanced glycation end products (RAGE) and its ligand S100B, which are secreted by SCs, are required for the repair of the injured peripheral nerve in vivo. However, the precise intracellular pathways involved have not been completely elucidated. Here, we show that RAGE-induced S100B secretion involves the recruitment of S100B in lipid rafts and caveolae. Moreover, we demonstrate for the first time that RAGE induces the expression of thioredoxin interacting protein (TXNIP) in SCs and the injured sciatic nerve in vivo. TXNIP is involved in the activation of p38 MAPK, CREB and NFκB in SCs. TXNIP silencing partially inhibits RAGE-induced SC migration and completely abolishes RAGE-induced fibronectin and IL-1β expression. Our results support a model in which TXNIP mediates in part RAGE-induced SC migration and is required for the expression of provisional ECM and pro-inflammatory IL-1β. We provide new insight on the role of the SC RAGE-TXNIP axis in the repair of injured peripheral nerves.
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Affiliation(s)
- Oualid Sbai
- NICN, CNRS UMR 6184, Faculté de Médecine, Université Aix-Marseille, 13344 Marseille Cedex 15, France
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Wong NSC, Wati L, Nissom PM, Feng HT, Lee MM, Yap MGS. An investigation of intracellular glycosylation activities in CHO cells: effects of nucleotide sugar precursor feeding. Biotechnol Bioeng 2010; 107:321-36. [PMID: 20506284 DOI: 10.1002/bit.22812] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Controlling glycosylation of recombinant proteins produced by CHO cells is highly desired as it can be directed towards maintaining or increasing product quality. To further our understanding of the different factors influencing glycosylation, a glycosylation sub-array of 79 genes and a capillary electrophoresis method which simultaneously analyzes 12 nucleotides and 7 nucleotide sugars; were used to generate intracellular N-glycosylation profiles. Specifically, the effects of nucleotide sugar precursor feeding on intracellular glycosylation activities were analyzed in CHO cells producing recombinant human interferon-gamma (IFN-gamma). Galactose (+/-uridine), glucosamine (+/-uridine), and N-acetylmannosamine (ManNAc) (+/-cytidine) feeding resulted in 12%, 28%, and 32% increase in IFN-gamma sialylation as compared to the untreated control cultures. This could be directly attributed to increases in nucleotide sugar substrates, UDP-Hex ( approximately 20-fold), UDP-HexNAc (6- to 15-fold) and CMP-sialic acid (30- to 120-fold), respectively. Up-regulation of B4gal and St3gal could also have enhanced glycan addition onto the proteins, leading to more complete glycosylation (sialylation). Combined feeding of glucosamine + uridine and ManNAc + cytidine increased UDP-HexNAc and CMP-sialic acid by another two- to fourfold as compared to feeding sugar precursors alone. However, it did not lead to a synergistic increase in IFN-gamma sialylation. Other factors such as glycosyltransferase or glycan substrate levels could have become limiting. In addition, uridine feeding increased the levels of uridine- and cytidine-activated nucleotide sugars simultaneously, which could imply that uridine is one of the limiting substrates for nucleotide sugar synthesis in the study. Hence, the characterization of intracellular glycosylation activities has increased our understanding of how nucleotide sugar precursor feeding influence glycosylation of recombinant proteins produced in CHO cells. It has also led to the optimization of more effective strategies for manipulating glycan quality.
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Affiliation(s)
- Niki S C Wong
- Bioprocessing Technology Institute, Agency for Science, Technology and Research, Singapore 138668, Singapore.
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46
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Dunn LL, Buckle AM, Cooke JP, Ng MKC. The emerging role of the thioredoxin system in angiogenesis. Arterioscler Thromb Vasc Biol 2010; 30:2089-98. [PMID: 20798378 DOI: 10.1161/atvbaha.110.209643] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Although there have been a multitude of studies, the mechanisms of angiogenesis remain incompletely understood. Increasing evidence suggests that cellular redox homeostasis is an important regulator of angiogenesis. The thioredoxin (TRX) system functions as an endogenous antioxidant that can exert influence over endothelial cell function via modulation of cellular redox status. It has become apparent that the cytosolic TRX1 isoform participates in both canonical and novel angiogenic signaling pathways and may represent an avenue for therapeutic exploitation. Recent studies have further identified a role for the mitochondrial isoform TRX2 in ischemia-induced angiogenesis. TRX-interacting protein (TXNIP) is the endogenous inhibitor of TRX redox activity that has been implicated in growth factor-mediated angiogenesis. As TXNIP is strongly induced by glucose, this molecule could be of consequence to disordered angiogenesis manifest in diabetes mellitus. This review will focus on data implicating the TRX system in endothelial cell homeostasis and angiogenesis.
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Affiliation(s)
- Louise L Dunn
- Department of Cardiology, Royal Prince Alfred Hospital, Missenden Rd, Camperdown, New South Wales, Australia.
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47
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Perrone L, Devi TS, Hosoya KI, Terasaki T, Singh LP. Inhibition of TXNIP expression in vivo blocks early pathologies of diabetic retinopathy. Cell Death Dis 2010; 1:e65. [PMID: 21364670 PMCID: PMC3032527 DOI: 10.1038/cddis.2010.42] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Evidence is mounting that proinflammatory and proapoptotic thioredoxin-interacting protein (TXNIP) has a causative role in the development of diabetes. However, there are no studies investigating the role of TXNIP in diabetic retinopathy (DR). Here, we show that, in diabetic rats, TXNIP expression and hexosamine biosynthesis pathway (HBP) flux, which regulates TXNIP, are elevated in the retina and correlates well with the induction of inflammatory cyclooxygenase 2 (Cox-2) and sclerotic fibronectin (FN). We blocked the expression of TXNIP in diabetic rat retinas by: (i) inhibiting HBP flux; (ii) inducing post-transcriptional gene silencing (PTGS) for TXNIP mRNA; and (iii) performing an in vivo transcriptional gene silencing (TGS) approach for TXNIP knockdown by promoter-targeted small interfering RNAs and cell-penetrating peptides as RNA interference (RNAi) transducers. Each of these methods is efficient in downregulating TXNIP expression, resulting in blockade of its target genes, Cox-2 and FN, demonstrating that TXNIP has a causative role in aberrant gene induction in early DR. RNAi TGS of TXNIP abolishes diabetes-induced retinal gliosis and ganglion injury. Thus, TXNIP has a critical role in inflammation and retinal injury in early stages of DR. The successful employment of TXNIP TGS and amelioration of its pathological effects open the way for novel therapeutic strategies aimed to block disease onset and progression of DR.
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Affiliation(s)
- L Perrone
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI 48201, USA
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48
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Rajamani U, Essop MF. Hyperglycemia-mediated activation of the hexosamine biosynthetic pathway results in myocardial apoptosis. Am J Physiol Cell Physiol 2010; 299:C139-47. [DOI: 10.1152/ajpcell.00020.2010] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The mechanisms mediating hyperglycemia-mediated myocardial cell death are poorly defined. Since elevated flux through the hexosamine biosynthetic pathway (HBP) is closely linked with the diabetic phenotype, we hypothesized that hyperglycemia-mediated oxidative stress results in greater O-GlcNAcylation (HBP end product) of the proapoptotic peptide BAD, thereby increasing myocardial apoptosis. H9c2 cardiomyoblasts were exposed to high glucose (33 mM) ± HBP modulators ± antioxidant treatment for 5 days vs. matched controls (5.5 mM), and we subsequently evaluated apoptosis by immunoblotting, immunofluorescence staining, and caspase activity measurements. In vitro reactive oxygen species (ROS) levels were quantified by 2′,7′-dichlorodihydrofluorescein diacetate staining (fluorescence microscopy and flow cytometry). We determined total and BAD O-GlcNAcylation, respectively, by immunoblotting and immunofluorescence microscopy. The current study shows that high glucose treatment of cells significantly increased the degree of apoptosis. In parallel, overall O-GlcNAcylation, BAD O-GlcNAcylation, and ROS levels were increased. HBP inhibition and antioxidant treatment attenuated these effects, while increased end product levels exacerbated it. As BAD-Bcl-2 dimer formation enhances apoptosis, we performed immunoprecipitation analysis and colocalization and found increased dimerization in cells exposed to hyperglycemia. Our study identified a novel pathway whereby hyperglycemia results in greater oxidative stress and increased HBP activation and BAD O-GlcNAcylation in H9c2 cardiomyoblasts. Since greater BAD-Bcl-2 dimerization increases myocardial apoptosis, this pathway may play a crucial role in diabetes-related onset of heart diseases.
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Affiliation(s)
- Uthra Rajamani
- Cardiometabolic Research Group, Department of Physiological Sciences, Stellenbosch University, Stellenbosch, South Africa
| | - M. Faadiel Essop
- Cardiometabolic Research Group, Department of Physiological Sciences, Stellenbosch University, Stellenbosch, South Africa
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Shao W, Yu Z, Fantus IG, Jin T. Cyclic AMP signaling stimulates proteasome degradation of thioredoxin interacting protein (TxNIP) in pancreatic beta-cells. Cell Signal 2010; 22:1240-6. [PMID: 20385228 DOI: 10.1016/j.cellsig.2010.04.001] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2010] [Accepted: 04/05/2010] [Indexed: 01/03/2023]
Abstract
Thioredoxin interacting protein (TxNIP) functions as an effector of glucotoxicity in pancreatic beta-cells. Exendin-4 (Ex-4), a long-term effective GLP-1 receptor agonist, reduces TxNIP level in pancreatic beta-cells. Mechanisms underlying this reduction, however, remain largely unknown. We show here that Ex-4, 8-bromo-cAMP, the cAMP promoting agent forskolin, as well as activators of protein kinase A (PKA) and exchange protein activated by cAMP (Epac), all attenuated the effect of high glucose (20mM) on TxNIP level in the pancreatic beta-cell line Ins-1. Forskolin and Ex-4 also reduced TxNIP level in cultured primary rat islets. This repressive effect is at least partially mediated via stimulating proteasome-dependent TxNIP degradation, since the proteasomal inhibitor MG132, but not the lysosomal inhibitor chloroquine, significantly blocked the repressive effect of forskolin. Furthermore, forskolin enhanced TxNIP ubiquitination. Both PKA inhibition and Epac inhibition partially blocked the repressive effect of forskolin on TxNIP level. In addition, forskolin and Ex-4 protected Ins-1 cells from high glucose-induced apoptotic activity, assessed by measuring caspase 3 activity. Finally, knockdown of TxNIP expression led to reduced caspase 3 expression levels and blunted response to forskolin treatment. We suggest that proteasome-dependent TxNIP degradation is a novel mechanism by which Ex-4-cAMP signaling protects pancreatic beta cells.
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Affiliation(s)
- Weijuan Shao
- Division of Cell and Molecular Biology, Toronto General Research Institute, University Health Network, Canada; Banting and Best Diabetes Centre, Faculty of Medicine, University of Toronto, Canada; Dept of Medicine, University of Toronto, Canada
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Gong D, Chen X, Middleditch M, Huang L, Vazhoor Amarsingh G, Reddy S, Lu J, Zhang S, Ruggiero K, Phillips ARJ, Cooper GJS. Quantitative proteomic profiling identifies new renal targets of copper(II)-selective chelation in the reversal of diabetic nephropathy in rats. Proteomics 2009; 9:4309-20. [PMID: 19634143 DOI: 10.1002/pmic.200900285] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
This study aimed to identify new diabetic nephropathy (DN)-related proteins and renal targets of the copper(II)-selective chelator, triethylenetetramine (TETA) in streptozotocin-diabetic rats. We used the recently developed iTRAQ technology to compare renal protein profiles among non-diabetic, diabetic, and TETA-treated diabetic rats. In diabetic kidneys, tubulointerstitial nephritis antigen (TINag), voltage-dependent anion-selective channel (VDAC) 1, and VDAC2 were up-regulated in parallel with alterations in expression of proteins with functions in oxidative stress and oxidative phosphorylation (OxPhos) pathways. By contrast, mitochondrial HSP 60, Cu/Zn-superoxide dismutase, glutathione S-transferase alpha3 and aquaporin-1 were down-regulated in diabetic kidneys. Following TETA treatment, levels of D-amino acid oxidase-1, epoxide hydrolase-1, aquaporin-1, and a number of mitochondrial proteins were normalized, with concomitant amelioration of albuminuria. Changes in levels of TINag, collagen VIalpha1, actinin 4alpha, apoptosis-inducing factor 1, cytochrome C, histone H3, VDAC1, and aquaporin-1 were confirmed by Western blotting or immunohistochemistry. Changes in expression of proteins related to tubulointerstitial function, podocyte structure, and mitochondrial apoptosis are implicated in the mechanism of DN and their reversal by TETA. These findings are consistent with the hypothesis that this new experimental therapy may be useful for treatment of DN.
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Affiliation(s)
- Deming Gong
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
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