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Hosseinpoor Z, Soheili ZS, Davari M, Latifi-Navid H, Samiee S, Samiee D. Crosstalk between MIR-96 and IRS/PI3K/AKT/VEGF cascade in hRPE cells; A potential target for preventing diabetic retinopathy. PLoS One 2024; 19:e0310999. [PMID: 39348384 PMCID: PMC11441665 DOI: 10.1371/journal.pone.0310999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Accepted: 09/10/2024] [Indexed: 10/02/2024] Open
Abstract
Regulation of visual system function demands precise gene regulation. Dysregulation of miRNAs, as key regulators of gene expression in retinal cells, contributes to different eye disorders such as diabetic retinopathy (DR), macular edema, and glaucoma. MIR-96, a member of the MIR-183 cluster family, is widely expressed in the retina, and its alteration is associated with neovascular eye diseases. MIR-96 regulates protein cascades in inflammatory and insulin signaling pathways, but further investigation is required to understand its potential effects on related genes. For this purpose, we identified a series of key target genes for MIR-96 based on gene and protein interaction networks and utilized text-mining resources. To examine the MIR-96 impact on candidate gene expression, we overexpressed MIR-96 via adeno-associated virus (AAV)-based plasmids in human retinal pigment epithelial (RPE) cells. Based on Real-Time PCR results, the relative expression of the selected genes responded differently to overexpressed MIR-96. While the expression levels of IRS2, FOXO1, and ERK2 (MAPK1) were significantly decreased, the SERPINF1 gene exhibited high expression simultaneously. pAAV-delivered MIR-96 had no adverse effect on the viability of human RPE cells. The data showed that changes in insulin receptor substrate-2 (IRS2) expression play a role in disrupted retinal insulin signaling and contribute to the development of diabetic complications. Considered collectively, our findings suggest that altered MIR-96 and its impact on IRS/PI3K/AKT/VEGF axis regulation contribute to DR progression. Therefore, further investigation of the IRS/PI3K/AKT/VEGF axis is recommended as a potential target for DR treatment.
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Affiliation(s)
- Zeynab Hosseinpoor
- Department of Molecular Medicine, National Institute of Genetic Engineering and Biotechnology (NIGEB), Tehran, Iran
| | - Zahra-Soheila Soheili
- Department of Molecular Medicine, National Institute of Genetic Engineering and Biotechnology (NIGEB), Tehran, Iran
| | - Maliheh Davari
- Department of Molecular Medicine, National Institute of Genetic Engineering and Biotechnology (NIGEB), Tehran, Iran
| | - Hamid Latifi-Navid
- Department of Molecular Medicine, National Institute of Genetic Engineering and Biotechnology (NIGEB), Tehran, Iran
- Electrophysiology Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran
- School of Biological Sciences, Institute for Research in Fundamental Sciences (IPM), Tehran, Iran
| | - Shahram Samiee
- Blood Transfusion Research Center High Institute for Research and Education in Transfusion Medicine, Tehran, Iran
| | - Dorsa Samiee
- Department of Computer Science, Royal Holloway University of London, Egham, Surrey, United Kingdom
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2
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El Hajji S, Shiga Y, Belforte N, Solorio YC, Tastet O, D’Onofrio P, Dotigny F, Prat A, Arbour N, Fortune B, Di Polo A. Insulin restores retinal ganglion cell functional connectivity and promotes visual recovery in glaucoma. SCIENCE ADVANCES 2024; 10:eadl5722. [PMID: 39110798 PMCID: PMC11305393 DOI: 10.1126/sciadv.adl5722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2023] [Accepted: 06/28/2024] [Indexed: 08/10/2024]
Abstract
Dendrite pathology and synaptic loss result in neural circuit dysfunction, a common feature of neurodegenerative diseases. There is a lack of strategies that target dendritic and synaptic regeneration to promote neurorecovery. We show that daily human recombinant insulin eye drops stimulate retinal ganglion cell (RGC) dendrite and synapse regeneration during ocular hypertension, a risk factor to develop glaucoma. We demonstrate that the ribosomal protein p70S6 kinase (S6K) is essential for insulin-dependent dendritic regrowth. Furthermore, S6K phosphorylation of the stress-activated protein kinase-interacting protein 1 (SIN1), a link between the mammalian target of rapamycin complexes 1 and 2 (mTORC1/2), is required for insulin-induced dendritic regeneration. Using two-photon microscopy live retinal imaging, we show that insulin rescues single-RGC light-evoked calcium (Ca2+) dynamics. We further demonstrate that insulin enhances neuronal survival and retina-brain connectivity leading to improved optomotor reflex-elicited behaviors. Our data support that insulin is a compelling pro-regenerative strategy with potential clinical implications for the treatment and management of glaucoma.
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Affiliation(s)
- Sana El Hajji
- Department of Neuroscience, Université de Montréal, PO box 6128, Station centre-ville, Montreal, Quebec, Canada
- Neuroscience Division, Centre de recherche du Centre Hospitalier de l’Université de Montréal (CR-CHUM), 900 Saint Denis Street, Montreal, Quebec, Canada
| | - Yukihiro Shiga
- Department of Neuroscience, Université de Montréal, PO box 6128, Station centre-ville, Montreal, Quebec, Canada
- Neuroscience Division, Centre de recherche du Centre Hospitalier de l’Université de Montréal (CR-CHUM), 900 Saint Denis Street, Montreal, Quebec, Canada
| | - Nicolas Belforte
- Department of Neuroscience, Université de Montréal, PO box 6128, Station centre-ville, Montreal, Quebec, Canada
- Neuroscience Division, Centre de recherche du Centre Hospitalier de l’Université de Montréal (CR-CHUM), 900 Saint Denis Street, Montreal, Quebec, Canada
| | - Yves Carpentier Solorio
- Department of Neuroscience, Université de Montréal, PO box 6128, Station centre-ville, Montreal, Quebec, Canada
- Neuroscience Division, Centre de recherche du Centre Hospitalier de l’Université de Montréal (CR-CHUM), 900 Saint Denis Street, Montreal, Quebec, Canada
| | - Olivier Tastet
- Department of Neuroscience, Université de Montréal, PO box 6128, Station centre-ville, Montreal, Quebec, Canada
- Neuroscience Division, Centre de recherche du Centre Hospitalier de l’Université de Montréal (CR-CHUM), 900 Saint Denis Street, Montreal, Quebec, Canada
| | - Philippe D’Onofrio
- Department of Neuroscience, Université de Montréal, PO box 6128, Station centre-ville, Montreal, Quebec, Canada
- Neuroscience Division, Centre de recherche du Centre Hospitalier de l’Université de Montréal (CR-CHUM), 900 Saint Denis Street, Montreal, Quebec, Canada
| | - Florence Dotigny
- Department of Neuroscience, Université de Montréal, PO box 6128, Station centre-ville, Montreal, Quebec, Canada
- Neuroscience Division, Centre de recherche du Centre Hospitalier de l’Université de Montréal (CR-CHUM), 900 Saint Denis Street, Montreal, Quebec, Canada
| | - Alexandre Prat
- Department of Neuroscience, Université de Montréal, PO box 6128, Station centre-ville, Montreal, Quebec, Canada
- Neuroscience Division, Centre de recherche du Centre Hospitalier de l’Université de Montréal (CR-CHUM), 900 Saint Denis Street, Montreal, Quebec, Canada
| | - Nathalie Arbour
- Department of Neuroscience, Université de Montréal, PO box 6128, Station centre-ville, Montreal, Quebec, Canada
- Neuroscience Division, Centre de recherche du Centre Hospitalier de l’Université de Montréal (CR-CHUM), 900 Saint Denis Street, Montreal, Quebec, Canada
| | - Brad Fortune
- Discoveries in Sight Research Laboratories, Devers Eye Institute and Legacy Research Institute, Legacy Health, Portland, OR, USA
| | - Adriana Di Polo
- Department of Neuroscience, Université de Montréal, PO box 6128, Station centre-ville, Montreal, Quebec, Canada
- Neuroscience Division, Centre de recherche du Centre Hospitalier de l’Université de Montréal (CR-CHUM), 900 Saint Denis Street, Montreal, Quebec, Canada
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Yu MG, Gordin D, Fu J, Park K, Li Q, King GL. Protective Factors and the Pathogenesis of Complications in Diabetes. Endocr Rev 2024; 45:227-252. [PMID: 37638875 PMCID: PMC10911956 DOI: 10.1210/endrev/bnad030] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 06/13/2023] [Accepted: 08/24/2023] [Indexed: 08/29/2023]
Abstract
Chronic complications of diabetes are due to myriad disorders of numerous metabolic pathways that are responsible for most of the morbidity and mortality associated with the disease. Traditionally, diabetes complications are divided into those of microvascular and macrovascular origin. We suggest revising this antiquated classification into diabetes complications of vascular, parenchymal, and hybrid (both vascular and parenchymal) tissue origin, since the profile of diabetes complications ranges from those involving only vascular tissues to those involving mostly parenchymal organs. A major paradigm shift has occurred in recent years regarding the pathogenesis of diabetes complications, in which the focus has shifted from studies on risks to those on the interplay between risk and protective factors. While risk factors are clearly important for the development of chronic complications in diabetes, recent studies have established that protective factors are equally significant in modulating the development and severity of diabetes complications. These protective responses may help explain the differential severity of complications, and even the lack of pathologies, in some tissues. Nevertheless, despite the growing number of studies on this field, comprehensive reviews on protective factors and their mechanisms of action are not available. This review thus focused on the clinical, biochemical, and molecular mechanisms that support the idea of endogenous protective factors, and their roles in the initiation and progression of chronic complications in diabetes. In addition, this review also aimed to identify the main needs of this field for future studies.
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Affiliation(s)
- Marc Gregory Yu
- Research Division, Joslin Diabetes Center, Boston, MA 02215, USA
- Department of Medicine, Harvard Medical School, Boston, MA 02215, USA
| | - Daniel Gordin
- Research Division, Joslin Diabetes Center, Boston, MA 02215, USA
- Department of Medicine, Harvard Medical School, Boston, MA 02215, USA
- Department of Nephrology, University of Helsinki and Helsinki University Central Hospital, Stenbäckinkatu 9, FI-00029 Helsinki, Finland
- Minerva Foundation Institute for Medical Research, Tukholmankatu 8, 00290 Helsinki, Finland
| | - Jialin Fu
- Research Division, Joslin Diabetes Center, Boston, MA 02215, USA
- Department of Medicine, Harvard Medical School, Boston, MA 02215, USA
| | - Kyoungmin Park
- Research Division, Joslin Diabetes Center, Boston, MA 02215, USA
- Department of Medicine, Harvard Medical School, Boston, MA 02215, USA
| | - Qian Li
- Research Division, Joslin Diabetes Center, Boston, MA 02215, USA
- Department of Medicine, Harvard Medical School, Boston, MA 02215, USA
| | - George Liang King
- Research Division, Joslin Diabetes Center, Boston, MA 02215, USA
- Department of Medicine, Harvard Medical School, Boston, MA 02215, USA
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Xu YX, Pu SD, Zhang YT, Tong XW, Sun XT, Shan YY, Gao XY. Insulin resistance is associated with the presence and severity of retinopathy in patients with type 2 diabetes. Clin Exp Ophthalmol 2024; 52:63-77. [PMID: 38130181 DOI: 10.1111/ceo.14344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 10/15/2023] [Accepted: 11/28/2023] [Indexed: 12/23/2023]
Abstract
BACKGROUND To assess the relationship between novel insulin resistance (IR) indices and the presence and severity of diabetic retinopathy (DR) in patients with type 2 diabetes. METHODS This is a cross-sectional study involving 2211 patients. The study outcomes were DR events. The study exposures were IR indices including estimated glucose disposal rate (eGDR), natural logarithm of glucose disposal rate (lnGDR), metabolic insulin resistance score (METS-IR), triglyceride glucose index-body mass index (TyG-BMI), triglyceride glucose index-waist-to-hip ratio (TyG-WHR), and triglyceride/high-density lipoprotein cholesterol(TG/HDL-c ratio). We used binary and multivariate ordered logistic regression models to estimate the association between different IR indices and the presence and severity of DR. Subject work characteristic curves were used to assess the predictive power of different IR indices for DR. RESULTS DR was present in 25.4% of participants. After adjusting for all covariates, per standard deviation (SD) increases in eGDR (ratio [OR] 0.38 [95% CI 0.32-0.44]), lnGDR (0.34 [0.27-0.42]) were negatively associated with the presence of DR. In contrast, per SD increases in METS-IR (1.97 [1.70-2.28]), TyG-BMI (1.94 [1.68-2.25]), TyG-WHR (2.34 [2.01-2.72]) and TG/HDL-c ratio (1.21 [1.08-1.36]) were positively associated with the presence of DR. eGDR was strongly associated with severity of DR. Of all variables, eGDR had the strongest diagnostic value for DR (AUC = 0.757). CONCLUSIONS Of the six IR indices, eGDR was significantly associated with the presence and severity of DR in patients with type 2 diabetes. eGDR has a good predictive value for DR. Thus, eGDR maybe a stronger marker of DR.
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Affiliation(s)
- Yu-Xin Xu
- Department of Endocrinology, The First Affiliated Hospital of Harbin Medical University, Harbin, People's Republic of China
| | - Sheng-Dan Pu
- Department of Endocrinology, The First Affiliated Hospital of Harbin Medical University, Harbin, People's Republic of China
| | - Yi-Tong Zhang
- Department of Endocrinology, The First Affiliated Hospital of Harbin Medical University, Harbin, People's Republic of China
| | - Xue-Wei Tong
- Department of Endocrinology, The First Affiliated Hospital of Harbin Medical University, Harbin, People's Republic of China
| | - Xiao-Tong Sun
- Department of Endocrinology, The First Affiliated Hospital of Harbin Medical University, Harbin, People's Republic of China
| | - Yong-Yan Shan
- Department of Endocrinology, The First Affiliated Hospital of Harbin Medical University, Harbin, People's Republic of China
| | - Xin-Yuan Gao
- Department of Endocrinology, The First Affiliated Hospital of Harbin Medical University, Harbin, People's Republic of China
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5
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Starr CR, Gorbatyuk MS. Posttranslational modifications of proteins in diseased retina. Front Cell Neurosci 2023; 17:1150220. [PMID: 37066080 PMCID: PMC10097899 DOI: 10.3389/fncel.2023.1150220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 03/13/2023] [Indexed: 04/03/2023] Open
Abstract
Posttranslational modifications (PTMs) are known to constitute a key step in protein biosynthesis and in the regulation of protein functions. Recent breakthroughs in protein purification strategies and current proteome technologies make it possible to identify the proteomics of healthy and diseased retinas. Despite these advantages, the research field identifying sets of posttranslationally modified proteins (PTMomes) related to diseased retinas is significantly lagging, despite knowledge of the major retina PTMome being critical to drug development. In this review, we highlight current updates regarding the PTMomes in three retinal degenerative diseases-namely, diabetic retinopathy (DR), glaucoma, and retinitis pigmentosa (RP). A literature search reveals the necessity to expedite investigations into essential PTMomes in the diseased retina and validate their physiological roles. This knowledge would accelerate the development of treatments for retinal degenerative disorders and the prevention of blindness in affected populations.
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Affiliation(s)
| | - Marina S. Gorbatyuk
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL, United States
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6
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Liu H, Stepicheva NA, Ghosh S, Shang P, Chowdhury O, Daley RA, Yazdankhah M, Gupta U, Hose SL, Valapala M, Fitting CS, Strizhakova A, Shan Y, Feenstra D, Sahel JA, Jayagopal A, Handa JT, Zigler JS, Fort PE, Sodhi A, Sinha D. Reducing Akt2 in retinal pigment epithelial cells causes a compensatory increase in Akt1 and attenuates diabetic retinopathy. Nat Commun 2022; 13:6045. [PMID: 36229454 PMCID: PMC9561713 DOI: 10.1038/s41467-022-33773-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 10/03/2022] [Indexed: 01/14/2023] Open
Abstract
The retinal pigment epithelium (RPE) plays an important role in the development of diabetic retinopathy (DR), a leading cause of blindness worldwide. Here we set out to explore the role of Akt2 signaling-integral to both RPE homeostasis and glucose metabolism-to DR. Using human tissue and genetically manipulated mice (including RPE-specific conditional knockout (cKO) and knock-in (KI) mice), we investigate whether Akts in the RPE influences DR in models of diabetic eye disease. We found that Akt1 and Akt2 activities were reciprocally regulated in the RPE of DR donor tissue and diabetic mice. Akt2 cKO attenuated diabetes-induced retinal abnormalities through a compensatory upregulation of phospho-Akt1 leading to an inhibition of vascular injury, inflammatory cytokine release, and infiltration of immune cells mediated by the GSK3β/NF-κB signaling pathway; overexpression of Akt2 has no effect. We propose that targeting Akt1 activity in the RPE may be a novel therapy for treating DR.
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Affiliation(s)
- Haitao Liu
- grid.21925.3d0000 0004 1936 9000Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA USA
| | - Nadezda A. Stepicheva
- grid.21925.3d0000 0004 1936 9000Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA USA
| | - Sayan Ghosh
- grid.21925.3d0000 0004 1936 9000Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA USA
| | - Peng Shang
- grid.21925.3d0000 0004 1936 9000Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA USA ,grid.280881.b0000 0001 0097 5623Present Address: Doheny Eye Institute, Pasadena, CA USA
| | - Olivia Chowdhury
- grid.21925.3d0000 0004 1936 9000Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA USA
| | - Rachel A. Daley
- grid.21925.3d0000 0004 1936 9000Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA USA
| | - Meysam Yazdankhah
- grid.21925.3d0000 0004 1936 9000Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA USA ,grid.443945.b0000 0004 0566 7998Present Address: Neural Stem Cell Institute, Rensselaer, NY USA
| | - Urvi Gupta
- grid.21925.3d0000 0004 1936 9000Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA USA
| | - Stacey L. Hose
- grid.21925.3d0000 0004 1936 9000Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA USA
| | - Mallika Valapala
- grid.411377.70000 0001 0790 959XSchool of Optometry, Indiana University, Bloomington, IN USA
| | - Christopher Scott Fitting
- grid.21925.3d0000 0004 1936 9000Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA USA
| | - Anastasia Strizhakova
- grid.21925.3d0000 0004 1936 9000Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA USA
| | - Yang Shan
- grid.214458.e0000000086837370Kellogg Eye Center, University of Michigan School of Medicine, Ann Arbor, MI USA
| | - Derrick Feenstra
- grid.417570.00000 0004 0374 1269Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche, Ltd., Basel, Switzerland
| | - José-Alain Sahel
- grid.21925.3d0000 0004 1936 9000Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA USA ,grid.462844.80000 0001 2308 1657Institut de la Vision, INSERM, CNRS, Sorbonne Université, Paris, France
| | | | - James T. Handa
- grid.21107.350000 0001 2171 9311The Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - J. Samuel Zigler
- grid.21107.350000 0001 2171 9311The Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Patrice E. Fort
- grid.214458.e0000000086837370Kellogg Eye Center, University of Michigan School of Medicine, Ann Arbor, MI USA
| | - Akrit Sodhi
- grid.21107.350000 0001 2171 9311The Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Debasish Sinha
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA. .,The Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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7
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Jones MA, Jadeja RN, Flandrin O, Abdelrahman AA, Thounojam MC, Thomas S, Dai C, Xiao H, Chen JK, Smith SB, Bartoli M, Martin PM, Powell FL. Autonomous regulation of retinal insulin biosynthesis in diabetes. Neuropeptides 2022; 94:102258. [PMID: 35660758 PMCID: PMC10440820 DOI: 10.1016/j.npep.2022.102258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 05/08/2022] [Accepted: 05/15/2022] [Indexed: 10/18/2022]
Abstract
Diabetic retinopathy (DR) is a neurodegenerative disease that results as a complication of dysregulated glucose metabolism, or diabetes. The signaling of insulin is lost or dampened in diabetes, but this hormone has also been shown to be an important neurotrophic factor which supports neurons of the brain. The role of local insulin synthesis and secretion in the retina, however, is unclear. We have investigated whether changes in local insulin synthesis occur in the diabetic retina and in response to stressors known to initiate retinal neurodegenerative processes. The expression of insulin and its cleavage product, c-peptide, were examined in retinas of a Type I diabetes animal model and human postmortem donors with DR. We detected mRNAs for insulin I (Ins1), insulin II (Ins2) and human insulin (Ins) by quantitative real-time polymerase chain reaction (qRT-PCR) and in situ hybridization. Using an ex-vivo system, isolated neuroretinas and retinal pigmented epithelium (RPE) layers were exposed to glycemic, oxidative and inflammatory environments to measure insulin gene transcripts produced de novo in the retina under disease-relevant conditions. The expression of insulin in the retina was altered with the progression of diabetes in STZ mice and donors with DR. Transcription factors for insulin, were simultaneously expressed in a pattern matching insulin genes. Furthermore, de novo insulin mRNA in isolated retinas was induced by acute stress. RPE explants displayed the most pronounced changes in Ins1 and Ins2. This data reveals that the retina, like the brain, is an organ capable of producing local insulin and this synthesis is altered in diabetes.
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Affiliation(s)
- Malita A Jones
- Department of Biochemistry and Molecular Biology, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA
| | - Ravirajsinh N Jadeja
- Department of Biochemistry and Molecular Biology, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA
| | - Orneika Flandrin
- UC Berkeley School of Optometry, University of California, Berkeley, CA, USA
| | - Ammar A Abdelrahman
- Department of Pharmacology, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA; Department of Clinical Pharmacy, Faculty of Pharmacy, Cairo University, Cairo, Egypt
| | - Menaka C Thounojam
- Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA
| | - Shakera Thomas
- Department of Biochemistry and Molecular Biology, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA
| | - Caihong Dai
- Department of Cell Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA
| | - Haiyan Xiao
- Department of Cell Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA
| | - Jian-Kang Chen
- Department of Cell Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA
| | - Sylvia B Smith
- Department of Cell Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA
| | - Manuela Bartoli
- Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA
| | - Pamela M Martin
- Department of Biochemistry and Molecular Biology, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA; Department of Cell Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA; Georgia Cancer Center, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA
| | - Folami L Powell
- Department of Biochemistry and Molecular Biology, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA.
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8
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Pitale PM, Gorbatyuk MS. Diabetic Retinopathy: From Animal Models to Cellular Signaling. Int J Mol Sci 2022; 23:ijms23031487. [PMID: 35163410 PMCID: PMC8835767 DOI: 10.3390/ijms23031487] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 01/24/2022] [Accepted: 01/26/2022] [Indexed: 12/24/2022] Open
Abstract
Diabetic retinopathy (DR) is an ocular complication of diabetes mellitus (DM), a metabolic disorder characterized by elevation in blood glucose level. The pathogenesis of DR includes vascular, neuronal, and inflammatory components leading to activation of complex cellular molecular signaling. If untreated, the disease can culminate in vision loss that eventually leads to blindness. Animal models mimicking different aspects of DM complications have been developed to study the development and progression of DR. Despite the significant contribution of the developed DR models to discovering the mechanisms of DR and the recent achievements in the research field, the sequence of cellular events in diabetic retinas is still under investigation. Partially, this is due to the complexity of molecular mechanisms, although the lack of availability of models that adequately mimic all the neurovascular pathobiological features observed in patients has also contributed to the delay in determining a precise molecular trigger. In this review, we provide an update on the status of animal models of DR to help investigators choose an appropriate system to validate their hypothesis. We also discuss the key cellular and physiological events of DR in these models.
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Affiliation(s)
- Priyamvada M. Pitale
- Department of Ophthalmology, Baylor College of Medicine, Houston, TX 77030, USA;
| | - Marina S. Gorbatyuk
- Department of Optometry and Vision Science, School of Optometry, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Correspondence: ; Tel.: +1-205-934-6762; Fax: +1-205-934-3425
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Liguori F, Mascolo E, Vernì F. The Genetics of Diabetes: What We Can Learn from Drosophila. Int J Mol Sci 2021; 22:ijms222011295. [PMID: 34681954 PMCID: PMC8541427 DOI: 10.3390/ijms222011295] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 10/12/2021] [Accepted: 10/16/2021] [Indexed: 12/14/2022] Open
Abstract
Diabetes mellitus is a heterogeneous disease characterized by hyperglycemia due to impaired insulin secretion and/or action. All diabetes types have a strong genetic component. The most frequent forms, type 1 diabetes (T1D), type 2 diabetes (T2D) and gestational diabetes mellitus (GDM), are multifactorial syndromes associated with several genes’ effects together with environmental factors. Conversely, rare forms, neonatal diabetes mellitus (NDM) and maturity onset diabetes of the young (MODY), are caused by mutations in single genes. Large scale genome screenings led to the identification of hundreds of putative causative genes for multigenic diabetes, but all the loci identified so far explain only a small proportion of heritability. Nevertheless, several recent studies allowed not only the identification of some genes as causative, but also as putative targets of new drugs. Although monogenic forms of diabetes are the most suited to perform a precision approach and allow an accurate diagnosis, at least 80% of all monogenic cases remain still undiagnosed. The knowledge acquired so far addresses the future work towards a study more focused on the identification of diabetes causal variants; this aim will be reached only by combining expertise from different areas. In this perspective, model organism research is crucial. This review traces an overview of the genetics of diabetes and mainly focuses on Drosophila as a model system, describing how flies can contribute to diabetes knowledge advancement.
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Affiliation(s)
- Francesco Liguori
- Preclinical Neuroscience, IRCCS Santa Lucia Foundation, 00143 Rome, Italy;
| | - Elisa Mascolo
- Department of Biology and Biotechnology “Charles Darwin”, Sapienza University, 00185 Rome, Italy;
| | - Fiammetta Vernì
- Department of Biology and Biotechnology “Charles Darwin”, Sapienza University, 00185 Rome, Italy;
- Correspondence:
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Mudaliar S, Hupfeld C, Chao DL. SGLT2 Inhibitor-Induced Low-Grade Ketonemia Ameliorates Retinal Hypoxia in Diabetic Retinopathy-A Novel Hypothesis. J Clin Endocrinol Metab 2021; 106:1235-1244. [PMID: 33512450 DOI: 10.1210/clinem/dgab050] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Indexed: 02/03/2023]
Abstract
Diabetic retinopathy (DR) is a well-recognized microvascular complication of diabetes. Growing evidence suggests that, in addition to retinal vascular damage, there is significant damage to retinal neural tissue in DR. Studies reveal neuronal damage before clinically evident vascular lesions and DR is now classified as a neurovascular complication. Hyperglycemia causes retinal damage through complex metabolic pathways leading to oxidative stress, inflammation, vascular damage, capillary ischemia, and retinal tissue hypoxia. Retinal hypoxia is further worsened by high oxygen consumption in the rods. Persistent hypoxia results in increases in vascular endothelial growth factor (VEGF) and other pro-angiogenic factors leading to proliferative DR/macular edema and progressive visual impairment. Optimal glucose control has favorable effects in DR. Other treatments for DR include laser photocoagulation, which improves retinal oxygenation by destroying the high oxygen consuming rods and their replacement by low oxygen consuming glial tissue. Hypoxia is a potent stimulator of VEGF, and intravitreal anti-VEGF antibodies are effective in regressing macular edema and in some studies, retinal neovascularization. In this review, we highlight the complex pathophysiology of DR with a focus on retinal oxygen/fuel consumption and hypoxic damage to retinal neurons. We discuss potential mechanisms through which sodium-glucose cotransporter 2 (SGLT2) inhibitors improve retinal hypoxia-through ketone bodies, which are energetically as efficient as glucose and yield more ATP per molecule of oxygen consumed than fat, with less oxidative stress. Retinal benefits would occur through improved fuel energetics, less hypoxia and through the anti-inflammatory/oxidative stress effects of ketone bodies. Well-designed studies are needed to explore this hypothesis.
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Affiliation(s)
- Sunder Mudaliar
- Veterans Affairs Medical Center, San Diego, CA, USA
- Department of Medicine, University of California, San Diego School of Medicine, San Diego, CA, USA
| | - Christopher Hupfeld
- Veterans Affairs Medical Center, San Diego, CA, USA
- Department of Medicine, University of California, San Diego School of Medicine, San Diego, CA, USA
| | - Daniel L Chao
- Shiley Eye Institute, Viterbi Family Department of Ophthalmology, University of California, San Diego School of Medicine, San Diego, CA, USA
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11
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Lee HJ, Mariappan MM, Norton L, Bakewell T, Feliers D, Oh SB, Donati A, Rubannelsonkumar CS, Venkatachalam MA, Harris SE, Rubera I, Tauc M, Ghosh Choudhury G, Kahn CR, Sharma K, DeFronzo RA, Kasinath BS. Proximal tubular epithelial insulin receptor mediates high-fat diet-induced kidney injury. JCI Insight 2021; 6:143619. [PMID: 33400689 PMCID: PMC7934847 DOI: 10.1172/jci.insight.143619] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 12/29/2020] [Indexed: 01/04/2023] Open
Abstract
The role of insulin receptor (IR) activated by hyperinsulinemia in obesity-induced kidney injury is not well understood. We hypothesized that activation of kidney proximal tubule epithelial IR contributes to obesity-induced kidney injury. We administered normal-fat diet (NFD) or high-fat diet (HFD) to control and kidney proximal tubule IR–knockout (KPTIRKO) mice for 4 months. Renal cortical IR expression was decreased by 60% in male and female KPTIRKO mice. Baseline serum glucose, serum creatinine, and the ratio of urinary albumin to creatinine (ACR) were similar in KPTIRKO mice compared to those of controls. On HFD, weight gain and increase in serum cholesterol were similar in control and KPTIRKO mice; blood glucose did not change. HFD increased the following parameters in the male control mice: renal cortical contents of phosphorylated IR and Akt, matrix proteins, urinary ACR, urinary kidney injury molecule-1–to-creatinine ratio, and systolic blood pressure. Renal cortical generation of hydrogen sulfide was reduced in HFD-fed male control mice. All of these parameters were ameliorated in male KPTIRKO mice. Interestingly, female mice were resistant to HFD-induced kidney injury in both genotypes. We conclude that HFD-induced kidney injury requires renal proximal tubule IR activation in male mice.
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Affiliation(s)
- Hak Joo Lee
- Center for Renal Medicine, Division of Nephrology
| | | | - Luke Norton
- Division of Diabetes, Department of Medicine
| | | | | | - Sae Byeol Oh
- Center for Renal Medicine, Division of Nephrology
| | | | | | | | - Stephen E Harris
- Department of Periodontics, University of Texas Health, San Antonio, Texas, USA
| | - Isabelle Rubera
- Universite Cote d'Azur, CNRS - UMR-7370, Laboratoire de Physiomédecine Moléculaire, Nice, France
| | - Michel Tauc
- Universite Cote d'Azur, CNRS - UMR-7370, Laboratoire de Physiomédecine Moléculaire, Nice, France
| | - Goutam Ghosh Choudhury
- Center for Renal Medicine, Division of Nephrology.,VA Research and.,Geriatric Research, Education and Clinical Center, South Texas Veterans Health Care System, San Antonio, Texas, USA
| | - C Ronald Kahn
- Joslin Diabetes Center and Harvard Medical School, Boston, Massachusetts, USA
| | - Kumar Sharma
- Center for Renal Medicine, Division of Nephrology.,VA Research and
| | | | - Balakuntalam S Kasinath
- Center for Renal Medicine, Division of Nephrology.,VA Research and.,Geriatric Research, Education and Clinical Center, South Texas Veterans Health Care System, San Antonio, Texas, USA
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12
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Rudraraju M, Narayanan SP, Somanath PR. Regulation of blood-retinal barrier cell-junctions in diabetic retinopathy. Pharmacol Res 2020; 161:105115. [PMID: 32750417 PMCID: PMC7755666 DOI: 10.1016/j.phrs.2020.105115] [Citation(s) in RCA: 90] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 07/22/2020] [Accepted: 07/27/2020] [Indexed: 12/15/2022]
Abstract
Loss of the blood-retinal barrier (BRB) integrity and subsequent damage to the neurovascular unit in the retina are the underlying reasons for diabetic retinopathy (DR). Damage to BRB eventually leads to severe visual impairment in the absence of prompt intervention. Diabetic macular edema and proliferative DR are the advanced stages of the disease where BRB integrity is altered. Primary mechanisms contributing to BRB dysfunction include loss of cell-cell barrier junctions, vascular endothelial growth factor, advanced glycation end products-induced damage, and oxidative stress. Although much is known about the involvement of adherens and tight-junction proteins in the regulation of vascular permeability in various diseases, there is a significant gap in our knowledge on the junctional proteins expressed in the BRB and how BRB function is modulated in the diabetic retina. In this review article, we present our current understanding of the molecular composition of BRB, the changes in the BRB junctional protein turnover in DR, and how BRB functional modulation affects vascular permeability and macular edema in the diabetic retina.
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Affiliation(s)
- Madhuri Rudraraju
- Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia and Charlie Norwood VA Medical Center, Augusta, GA 30912, United States; James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA 30912, United States
| | - S Priya Narayanan
- Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia and Charlie Norwood VA Medical Center, Augusta, GA 30912, United States; Vascular Biology Center, Augusta University, Augusta, GA 30912, United States; James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA 30912, United States
| | - Payaningal R Somanath
- Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia and Charlie Norwood VA Medical Center, Augusta, GA 30912, United States; Vascular Biology Center, Augusta University, Augusta, GA 30912, United States; Department of Medicine, Augusta University, Augusta, GA 30912, United States.
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13
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Ramírez-Pérez G, Sánchez-Chávez G, Salceda R. Mitochondrial bound hexokinase type I in normal and streptozotocin diabetic rat retina. Mitochondrion 2020; 52:212-217. [DOI: 10.1016/j.mito.2020.04.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 02/24/2020] [Accepted: 04/07/2020] [Indexed: 12/19/2022]
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14
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Kanda A, Hirose I, Noda K, Murata M, Ishida S. Glucocorticoid-transactivated TSC22D3 attenuates hypoxia- and diabetes-induced Müller glial galectin-1 expression via HIF-1α destabilization. J Cell Mol Med 2020; 24:4589-4599. [PMID: 32150332 PMCID: PMC7176855 DOI: 10.1111/jcmm.15116] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Revised: 02/10/2020] [Accepted: 02/17/2020] [Indexed: 12/27/2022] Open
Abstract
Galectin‐1/LGALS1, a newly recognized angiogenic factor, contributes to the pathogenesis of diabetic retinopathy (DR). Recently, we demonstrated that glucocorticoids suppressed an interleukin‐1β‐driven inflammatory pathway for galectin‐1 expression in vitro and in vivo. Here, we show glucocorticoid‐mediated inhibitory mechanism against hypoxia‐inducible factor (HIF)‐1α‐involved galectin‐1 expression in human Müller glial cells and the retina of diabetic mice. Hypoxia‐induced increases in galectin‐1/LGALS1 expression and promoter activity were attenuated by dexamethasone and triamcinolone acetonide in vitro. Glucocorticoid application to hypoxia‐stimulated cells decreased HIF‐1α protein, but not mRNA, together with its DNA‐binding activity, while transactivating TSC22 domain family member (TSC22D)3 mRNA and protein expression. Co‐immunoprecipitation revealed that glucocorticoid‐transactivated TSC22D3 interacted with HIF‐1α, leading to degradation of hypoxia‐stabilized HIF‐1α via the ubiquitin‐proteasome pathway. Silencing TSC22D3 reversed glucocorticoid‐mediated ubiquitination of HIF‐1α and subsequent down‐regulation of HIF‐1α and galectin‐1/LGALS1 levels. Glucocorticoid treatment to mice significantly alleviated diabetes‐induced retinal HIF‐1α and galectin‐1/Lgals1 levels, while increasing TSC22D3 expression. Fibrovascular tissues from patients with proliferative DR demonstrated co‐localization of galectin‐1 and HIF‐1α in glial cells partially positive for TSC22D3. These results indicate that glucocorticoid‐transactivated TSC22D3 attenuates hypoxia‐ and diabetes‐induced retinal glial galectin‐1/LGALS1 expression via HIF‐1α destabilization, highlighting therapeutic implications for DR in the era of anti‐vascular endothelial growth factor treatment.
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Affiliation(s)
- Atsuhiro Kanda
- Laboratory of Ocular Cell Biology and Visual Science, Department of Ophthalmology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Ikuyo Hirose
- Laboratory of Ocular Cell Biology and Visual Science, Department of Ophthalmology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Kousuke Noda
- Laboratory of Ocular Cell Biology and Visual Science, Department of Ophthalmology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Miyuki Murata
- Laboratory of Ocular Cell Biology and Visual Science, Department of Ophthalmology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Susumu Ishida
- Laboratory of Ocular Cell Biology and Visual Science, Department of Ophthalmology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
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15
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Kristiansen SB, Pælestik KB, Johnsen J, Jespersen NR, Pryds K, Hjortbak MV, Jensen RV, Bøtker HE. Impact of hyperglycemia on myocardial ischemia-reperfusion susceptibility and ischemic preconditioning in hearts from rats with type 2 diabetes. Cardiovasc Diabetol 2019; 18:66. [PMID: 31151453 PMCID: PMC6543682 DOI: 10.1186/s12933-019-0872-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2019] [Accepted: 05/20/2019] [Indexed: 01/04/2023] Open
Abstract
Background The mechanisms underlying increased mortality in patients with diabetes and admission hyperglycemia after an acute coronary syndrome may involve reduced capacity for cardioprotection. We investigated the impact of hyperglycemia on exogenously activated cardioprotection by ischemic preconditioning (IPC) in hearts from rats with type 2 diabetes mellitus (T2DM) that were endogenously cardioprotected by an inherent mechanism, and the involvement of myocardial glucose uptake (MGU) and myocardial O-linked β-N-acetylglucosamine (O-GlcNAc). Methods and results In isolated, perfused rat hearts subjected to ischemia–reperfusion, infarct size (IS) was overall larger during hyper- ([Glucose] = 22 mmol/L]) than normoglycemia ([Glucose] = 11 mmol/L]) (p < 0.001). IS was smaller in 12-week old Zucker diabetic fatty rats with recent onset T2DM (fa/fa) than in rats without T2DM (fa/+) (n = 8 in each group) both during hyperglycemia (p < 0.05) and normoglycemia (p < 0.05). IPC (2 × 5 min cycles) reduced IS during normo- (p < 0.01 for both groups) but not during hyperglycemia independently of the presence of T2DM. During hyperglycemia, an intensified IPC stimulus (4 × 5 min cycles) reduced IS only in hearts from animals with T2DM (p < 0.05). IPC increased MGU and O-GlcNAc levels during reperfusion in animals with and without T2DM at normoglycemia (MGU: p < 0.05, O-GlcNAc: p < 0.01 for both groups) but not during hyperglycemia. Intensified IPC at hyperglycemia increased MGU (p < 0.05) and O-GlcNAc levels (p < 0.05) only in hearts from animals with T2DM. Conclusion While the effect of IPC is reduced during hyperglycemia in rats without T2DM, endogenous cardioprotection in animals with T2DM is not influenced by hyperglycemia and the capacity for exogenous cardioprotection by IPC is preserved. MGU and O-GlcNAc levels are increased by exogenously induced cardioprotection by IPC but not by endogenous cardioprotection in animals with T2DM reflecting different underlying mechanisms by exogenous and endogenous cardioprotection.
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Affiliation(s)
- Steen Buus Kristiansen
- Department of Cardiology, Aarhus University Hospital, Skejby Sygehus, Palle Juul-Jensens Boulevard 99, 8200, Aarhus N, Denmark.
| | - Kim Bolther Pælestik
- Department of Cardiology, Aarhus University Hospital, Skejby Sygehus, Palle Juul-Jensens Boulevard 99, 8200, Aarhus N, Denmark
| | - Jacob Johnsen
- Department of Cardiology, Aarhus University Hospital, Skejby Sygehus, Palle Juul-Jensens Boulevard 99, 8200, Aarhus N, Denmark
| | - Nichlas Riise Jespersen
- Department of Cardiology, Aarhus University Hospital, Skejby Sygehus, Palle Juul-Jensens Boulevard 99, 8200, Aarhus N, Denmark
| | - Kasper Pryds
- Department of Cardiology, Aarhus University Hospital, Skejby Sygehus, Palle Juul-Jensens Boulevard 99, 8200, Aarhus N, Denmark
| | - Marie Vognstoft Hjortbak
- Department of Cardiology, Aarhus University Hospital, Skejby Sygehus, Palle Juul-Jensens Boulevard 99, 8200, Aarhus N, Denmark
| | - Rebekka Vibjerg Jensen
- Department of Cardiology, Aarhus University Hospital, Skejby Sygehus, Palle Juul-Jensens Boulevard 99, 8200, Aarhus N, Denmark
| | - Hans Erik Bøtker
- Department of Cardiology, Aarhus University Hospital, Skejby Sygehus, Palle Juul-Jensens Boulevard 99, 8200, Aarhus N, Denmark
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16
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Insulin-induced exocytosis regulates the cell surface level of low-density lipoprotein-related protein-1 in Müller Glial cells. Biochem J 2018; 475:1669-1685. [PMID: 29669912 DOI: 10.1042/bcj20170891] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Revised: 04/16/2018] [Accepted: 04/17/2018] [Indexed: 02/07/2023]
Abstract
Low-density lipoprotein (LDL) receptor-related protein-1 (LRP1) is expressed in retinal Müller glial cells (MGCs) and regulates intracellular translocation to the plasma membrane (PM) of the membrane proteins involved in cellular motility and activity. Different functions of MGCs may be influenced by insulin, including the removal of extracellular glutamate in the retina. In the present work, we investigated whether insulin promotes LRP1 translocation to the PM in the Müller glial-derived cell line MIO-M1 (human retinal Müller glial cell-derived cell line). We demonstrated that LRP1 is stored in small vesicles containing an approximate size of 100 nm (mean diameter range of 100-120 nm), which were positive for sortilin and VAMP2, and also incorporated GLUT4 when it was transiently transfected. Next, we observed that LRP1 translocation to the PM was promoted by insulin-regulated exocytosis through intracellular activation of the IR/PI3K/Akt axis and Rab-GTPase proteins such as Rab8A and Rab10. In addition, these Rab-GTPases regulated both the constitutive and insulin-induced LRP1 translocation to the PM. Finally, we found that dominant-negative Rab8A and Rab10 mutants impaired insulin-induced intracellular signaling of the IR/PI3K/Akt axis, suggesting that these GTPase proteins as well as the LRP1 level at the cell surface are involved in insulin-induced IR activation.
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17
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Philbrick KA, Martin SA, Colagiovanni AR, Branscum AJ, Turner RT, Iwaniec UT. Effects of hypothalamic leptin gene therapy on osteopetrosis in leptin-deficient mice. J Endocrinol 2018; 236:57-68. [PMID: 29191939 PMCID: PMC5771473 DOI: 10.1530/joe-17-0524] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2017] [Accepted: 11/20/2017] [Indexed: 12/26/2022]
Abstract
Impaired resorption of cartilage matrix deposited during endochondral ossification is a defining feature of juvenile osteopetrosis. Growing, leptin-deficient ob/ob mice exhibit a mild form of osteopetrosis. However, the extent to which the disease is (1) self-limiting and (2) reversible by leptin treatment is unknown. We addressed the first question by performing histomorphometric analysis of femurs in rapidly growing (2-month-old), slowly growing (4-month-old) and skeletally mature (6-month-old) wild-type (WT) and ob/ob male mice. Absent by 6 months of age in WT mice, cartilage matrix persisted to varying extents in distal femur epiphysis, metaphysis and diaphysis in ob/ob mice, suggesting that the osteopetrotic phenotype is not entirely self-limiting. To address the second question, we employed hypothalamic recombinant adeno-associated virus (rAAV) gene therapy to restore leptin signaling in ob/ob mice. Two-month-old mice were randomized to one of the three groups: (1) untreated control, (2) rAAV-Leptin or (3) control vector rAAV-green fluorescent protein and vectors injected intracerebroventricularly. Seven months later, rAAV-leptin-treated mice exhibited no cartilage in the metaphysis and greatly reduced cartilage in the epiphysis and diaphysis. At the cellular level, the reduction in cartilage was associated with increased bone turnover. These findings (1) support the concept that leptin is important for normal replacement of cartilage by bone, and (2) demonstrate that osteopetrosis in ob/ob mice is bone-compartment-specific and reversible by leptin at skeletal sites capable of undergoing robust bone turnover.
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Affiliation(s)
- Kenneth A Philbrick
- Skeletal Biology LaboratorySchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USA
| | - Stephen A Martin
- Skeletal Biology LaboratorySchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USA
| | - Amy R Colagiovanni
- Skeletal Biology LaboratorySchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USA
| | - Adam J Branscum
- Biostatistics ProgramSchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USA
| | - Russell T Turner
- Skeletal Biology LaboratorySchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USA
- Center for Healthy Aging ResearchOregon State University, Corvallis, Oregon, USA
| | - Urszula T Iwaniec
- Skeletal Biology LaboratorySchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USA
- Center for Healthy Aging ResearchOregon State University, Corvallis, Oregon, USA
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18
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Gao X, Li Y, Wang H, Li C, Ding J. Inhibition of HIF-1α decreases expression of pro-inflammatory IL-6 and TNF-α in diabetic retinopathy. Acta Ophthalmol 2017; 95:e746-e750. [PMID: 27288252 DOI: 10.1111/aos.13096] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 03/17/2016] [Indexed: 01/04/2023]
Abstract
PURPOSE Recent studies demonstrate that pro-inflammatory cytokines (PICs, i.e. IL-1β, IL-6 and TNF-α) in retinal tissues are likely involved in the development of diabetic retinopathy (DR). In this report, we particularly examined contributions of hypoxia inducible factor subtype 1α (HIF-1α) to the expression of PICs and their receptors in diabetic retina. METHODS Streptozotocin (STZ) was systemically injected to induce hyperglycaemia in rats. ELISA and Western blot analysis were employed to determine the levels of HIF-1α and PICs as well as PIC receptors in retinal tissues of control rats and STZ rats. RESULTS The levels of retinal HIF-1α were significantly increased in STZ rats 4-10 weeks after induction of hyperglycaemia as compared with control animals. With increasing HIF-1α retinal PICs including IL-1β, IL-6 and TNF-α, their respective receptors, namely IL-1R, IL-6R and TNFR1, were also elevated in STZ rats. Moreover, inhibition of HIF-1α by injection of 2-methoxyestradiol (2-MET) significantly decreased the amplified expression IL-6, TNF-α, IL-6R and TNFR1 in diabetic retina, but did not modify IL-1β pathway. In addition, we examined protein expression of Caspase-3 indicating cell apoptosis in the retina of STZ rats after infusing 2-MET, demonstrating that 2-MET attenuated an increase in Caspase-3 evoked by STZ. CONCLUSION Hypoxia inducible factor subtype 1α (HIF-1α) activated in diabetic retina is likely to play a role in regulating pathophysiological process via IL-6 and TNF-α mechanism. This has pharmacological implications to target specific HIF-1α, IL-6 and TNF-α signalling pathway for dysfunction and vulnerability related to DR.
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Affiliation(s)
- Xiuhua Gao
- Department of Ophthalmology; Jining Medical University Affiliated Hospital; Jining City Shandong Province China
| | - Yonghua Li
- Department of Ophthalmology; Jining Medical University Affiliated Hospital; Jining City Shandong Province China
| | - Hongxia Wang
- Department of Ophthalmology; Jining Medical University Affiliated Hospital; Jining City Shandong Province China
| | - Chuanbao Li
- Department of Ophthalmology; Jining Medical University Affiliated Hospital; Jining City Shandong Province China
| | - Jianguang Ding
- Department of Ophthalmology; Jining Medical University Affiliated Hospital; Jining City Shandong Province China
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Blair NP, Wanek J, Felder AE, Brewer KC, Joslin CE, Shahidi M. Inner Retinal Oxygen Delivery, Metabolism, and Extraction Fraction in Ins2Akita Diabetic Mice. Invest Ophthalmol Vis Sci 2017; 57:5903-5909. [PMID: 27802520 PMCID: PMC5096417 DOI: 10.1167/iovs.16-20082] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Purpose Retinal nonperfusion and hypoxia are important factors in human diabetic retinopathy, and these presumably inhibit energy production and lead to cell death. The purpose of this study was to elucidate the effect of diabetes on inner retinal oxygen delivery and metabolism in a mouse model of diabetes. Methods Phosphorescence lifetime and blood flow imaging were performed in spontaneously diabetic Ins2Akita (n = 22) and nondiabetic (n = 22) mice at 12 and 24 weeks of age to measure retinal arterial (O2A) and venous (O2V) oxygen contents and total retinal blood flow (F). Inner retinal oxygen delivery (DO2) and metabolism (MO2) were calculated as F ∗ O2A and F ∗ (O2A − O2V), respectively. Oxygen extraction fraction (OEF), which equals MO2/DO2, was calculated. Results DO2 at 12 weeks were 112 ± 40 and 97 ± 29 nL O2/min in nondiabetic and diabetic mice, respectively (NS), and 148 ± 31 and 85 ± 37 nL O2/min at 24 weeks, respectively (P < 0.001). MO2 were 65 ± 31 and 66 ± 27 nL O2/min in nondiabetic and diabetic mice at 12 weeks, respectively, and 79 ± 14 and 54 ± 28 nL O2/min at 24 weeks, respectively (main effects = NS). At 12 weeks OEF were 0.57 ± 0.17 and 0.67 ± 0.09 in nondiabetic and diabetic mice, respectively, and 0.54 ± 0.07 and 0.63 ± 0.08 at 24 weeks, respectively (main effect of diabetes: P < 0.01). Conclusions Inner retinal MO2 was maintained in diabetic Akita mice indicating that elevation of the OEF adequately compensated for reduced DO2 and prevented oxidative metabolism from being limited by hypoxia.
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Affiliation(s)
- Norman P Blair
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, Illinois, United States
| | - Justin Wanek
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, Illinois, United States
| | - Anthony E Felder
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, Illinois, United States
| | - Katherine C Brewer
- Division of Epidemiology and Biostatistics, School of Public Health, University of Illinois at Chicago, Chicago, Illinois, United States
| | - Charlotte E Joslin
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, Illinois, United States 2Division of Epidemiology and Biostatistics, School of Public Health, University of Illinois at Chicago, Chicago, Illinois, United States 3University of Illinois Cancer Center, Population Health, Behavior, and Outcomes Program, Chicago, Illinois, United States
| | - Mahnaz Shahidi
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, Illinois, United States
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20
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Eichler TE, Becknell B, Easterling RS, Ingraham SE, Cohen DM, Schwaderer AL, Hains DS, Li B, Cohen A, Metheny J, Tridandapani S, Spencer JD. Insulin and the phosphatidylinositol 3-kinase signaling pathway regulate Ribonuclease 7 expression in the human urinary tract. Kidney Int 2016; 90:568-79. [PMID: 27401534 DOI: 10.1016/j.kint.2016.04.025] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 04/12/2016] [Accepted: 04/28/2016] [Indexed: 10/21/2022]
Abstract
Diabetes mellitus is a systemic disease associated with a deficiency of insulin production or action. Diabetic patients have an increased susceptibility to infection with the urinary tract being the most common site. Recent studies suggest that Ribonuclease 7 (RNase 7) is a potent antimicrobial peptide that plays an important role in protecting the urinary tract from bacterial insult. Because the impact of diabetes on RNase 7 expression and function are unknown, we investigated the effects of insulin on RNase 7 using human urine specimens. The urinary RNase 7 concentrations were measured in healthy control patients and insulin-deficient type 1 diabetics before and after starting insulin therapy. Compared with controls, diabetic patients had suppressed urinary RNase 7 concentrations, which increased with insulin. Using primary human urothelial cells, the mechanisms by which insulin stimulates RNase 7 synthesis were next explored. Insulin induced RNase 7 production via the phosphatidylinositide 3-kinase signaling pathway (PI3K/AKT) to shield urothelial cells from uropathogenic E. coli. In contrast, uropathogenic E. coli suppressed PI3K/AKT activity and RNase 7 production. Thus, insulin and PI3K/AKT signaling are essential for RNase 7 expression and increased infection risks in diabetic patients may be secondary to suppressed RNase 7 production. Our data may provide unique insight into novel urinary tract infection therapeutic strategies in at-risk populations.
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Affiliation(s)
- Tad E Eichler
- Center for Clinical and Translational Research, Department of Pediatrics, The Research Institute at Nationwide Children's, Columbus, Ohio, USA
| | - Brian Becknell
- Center for Clinical and Translational Research, Department of Pediatrics, The Research Institute at Nationwide Children's, Columbus, Ohio, USA; Division of Nephrology, Department of Pediatrics, Nationwide Children's, Columbus, Ohio, USA
| | - Robert S Easterling
- Center for Clinical and Translational Research, Department of Pediatrics, The Research Institute at Nationwide Children's, Columbus, Ohio, USA; University of Toledo College of Medicine and Life Sciences, Toledo, Ohio, USA
| | - Susan E Ingraham
- Center for Clinical and Translational Research, Department of Pediatrics, The Research Institute at Nationwide Children's, Columbus, Ohio, USA; Division of Nephrology, Department of Pediatrics, Nationwide Children's, Columbus, Ohio, USA
| | - Daniel M Cohen
- Division of Emergency Medicine, Department of Pediatrics, Nationwide Children's, Columbus, Ohio, USA
| | - Andrew L Schwaderer
- Center for Clinical and Translational Research, Department of Pediatrics, The Research Institute at Nationwide Children's, Columbus, Ohio, USA; Division of Nephrology, Department of Pediatrics, Nationwide Children's, Columbus, Ohio, USA
| | - David S Hains
- Innate Immunity Translational Research Center, Department of Pediatrics, Children's Foundation Research Institute at Le Bonheur Children's Hospital, Memphis, Tennessee, USA
| | - Birong Li
- Center for Clinical and Translational Research, Department of Pediatrics, The Research Institute at Nationwide Children's, Columbus, Ohio, USA
| | - Ariel Cohen
- Center for Clinical and Translational Research, Department of Pediatrics, The Research Institute at Nationwide Children's, Columbus, Ohio, USA
| | - Jackie Metheny
- Center for Clinical and Translational Research, Department of Pediatrics, The Research Institute at Nationwide Children's, Columbus, Ohio, USA
| | - Susheela Tridandapani
- Department of Internal Medicine, Comprehensive Cancer Center, The Ohio State University James Cancer Hospital and Richard J. Solove Research Institute, Columbus, Ohio, USA; Department of Molecular Virology, Immunology, and Medical Genetics, Comprehensive Cancer Center, The Ohio State University James Cancer Hospital and Richard J. Solove Research Institute, Columbus, Ohio, USA
| | - John David Spencer
- Center for Clinical and Translational Research, Department of Pediatrics, The Research Institute at Nationwide Children's, Columbus, Ohio, USA; Division of Nephrology, Department of Pediatrics, Nationwide Children's, Columbus, Ohio, USA.
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Kanda A, Noda K, Saito W, Ishida S. Aflibercept Traps Galectin-1, an Angiogenic Factor Associated with Diabetic Retinopathy. Sci Rep 2015; 5:17946. [PMID: 26648523 PMCID: PMC4673700 DOI: 10.1038/srep17946] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 11/09/2015] [Indexed: 12/15/2022] Open
Abstract
Vascular endothelial growth factor (VEGF)-A-driven angiogenesis contributes to various disorders including cancer and proliferative diabetic retinopathy (PDR). Among several VEGF-A blockers clinically used is aflibercept, a chimeric VEGFR1/VEGFR2-based decoy receptor fused to the Fc fragment of IgG1 (i.e., VEGFR1/VEGFR2-Fc). Here, we revealed a novel anti-angiogenic function for aflibercept beyond its antagonism against VEGF family members. Immunoprecipitation and mass spectrometry analyses identified galectin-1 as an aflibercept-interacting protein. Biolayer interferometry revealed aflibercept binding to galectin-1 with higher affinity than VEGFR1-Fc and VEGFR2-Fc, which was abolished by deglycosylation of aflibercept with peptide:N-glycosidase F. Retinal LGALS1/Galectin-1 mRNA expression was enhanced in vitro by hypoxic stimulation and in vivo by induction of diseases including diabetes. Galectin-1 immunoreactivity co-localized with VEGFR2 in neovascular tissues surgically excised from human eyes with PDR. Compared with non-diabetic controls, intravitreal galectin-1 protein levels were elevated in PDR eyes, showing no correlation with increased VEGF-A levels. Preoperative injection of bevacizumab, a monoclonal antibody to VEGF-A, reduced the VEGF-A, but not galectin-1, levels. Galectin-1 application to human retinal microvascular endothelial cells up-regulated VEGFR2 phosphorylation, which was eliminated by aflibercept. Our present findings demonstrated the neutralizing efficacy of aflibercept against galectin-1, an angiogenic factor associated with PDR independently of VEGF-A.
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Affiliation(s)
- Atsuhiro Kanda
- Laboratory of Ocular Cell Biology and Visual Science, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido 060-8638, Japan.,Department of Ophthalmology, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido 060-8638, Japan
| | - Kousuke Noda
- Laboratory of Ocular Cell Biology and Visual Science, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido 060-8638, Japan.,Department of Ophthalmology, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido 060-8638, Japan
| | - Wataru Saito
- Department of Ophthalmology, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido 060-8638, Japan
| | - Susumu Ishida
- Laboratory of Ocular Cell Biology and Visual Science, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido 060-8638, Japan.,Department of Ophthalmology, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido 060-8638, Japan
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22
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Jing Y, Liu W, Cao H, Zhang D, Yao X, Zhang S, Xia H, Li D, Wang YC, Yan J, Hui L, Ying H. Hepatic p38α regulates gluconeogenesis by suppressing AMPK. J Hepatol 2015; 62:1319-27. [PMID: 25595884 DOI: 10.1016/j.jhep.2014.12.032] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 11/03/2014] [Accepted: 12/23/2014] [Indexed: 12/04/2022]
Abstract
BACKGROUND & AIMS It is proposed that p38 is involved in gluconeogenesis, however, the genetic evidence is lacking and precise mechanisms remain poorly understood. We sought to delineate the role of hepatic p38α in gluconeogenesis during fasting by applying a loss-of-function genetic approach. METHODS We examined fasting glucose levels, performed pyruvate tolerance test, imaged G6Pase promoter activity, as well as determined the expression of gluconeogenic genes in mice with a targeted deletion of p38α in liver. Results were confirmed both in vivo and in vitro by using an adenoviral dominant-negative form of p38α (p38α-AF) and the constitutively active mitogen-activated protein kinase 6, respectively. Adenoviral dominant-negative form of AMP-activated protein kinase α (DN-AMPKα) was employed to test our proposed model. RESULTS Mice lacking hepatic p38α exhibited reduced fasting glucose level and impaired gluconeogenesis. Interestingly, hepatic deficiency of p38α did not result in an alteration in CREB phosphorylation, but led to an increase in AMPKα phosphorylation. Adenoviral DN-AMPKα could abolish the effect of p38α-AF on gluconeogenesis. Knockdown of up-steam transforming growth factor β-activated kinase 1 decreased the AMPKα phosphorylation induced by p38α-AF, suggesting a negative feedback loop. Consistently, inverse correlations between p38 and AMPKα phosphorylation were observed during fasting and in diabetic mouse models. Importantly, adenoviral p38α-AF treatment ameliorated hyperglycemia in diabetic mice. CONCLUSIONS Our study provides evidence that hepatic p38α functions as a negative regulator of AMPK signaling in maintaining gluconeogenesis, dysregulation of this regulatory network contributes to unrestrained gluconeogenesis in diabetes, and hepatic p38α could be a drug target for hyperglycemia.
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Affiliation(s)
- Yanyan Jing
- Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China; Key Laboratory of Food Safety Risk Assessment, Ministry of Health, Beijing 100021, China
| | - Wei Liu
- Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China; Key Laboratory of Food Safety Risk Assessment, Ministry of Health, Beijing 100021, China
| | - Hongchao Cao
- Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China
| | - Duo Zhang
- Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China
| | - Xuan Yao
- Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China
| | - Shengjie Zhang
- Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China
| | - Hongfeng Xia
- Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China
| | - Dan Li
- Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Yu-cheng Wang
- Clinical Research Center of Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China; Department of Nutrition, Shanghai Xuhui Central Hospital, Shanghai 200031, China
| | - Jun Yan
- Model Animal Research Center, and MOE Key Laboratory of Model Animals for Disease Study, Nanjing University, Nanjing 210061, China
| | - Lijian Hui
- Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Hao Ying
- Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China; Key Laboratory of Food Safety Risk Assessment, Ministry of Health, Beijing 100021, China; Clinical Research Center of Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.
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23
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Alam NM, Mills WC, Wong AA, Douglas RM, Szeto HH, Prusky GT. A mitochondrial therapeutic reverses visual decline in mouse models of diabetes. Dis Model Mech 2015; 8:701-10. [PMID: 26035391 PMCID: PMC4486862 DOI: 10.1242/dmm.020248] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 04/19/2015] [Indexed: 12/21/2022] Open
Abstract
Diabetic retinopathy is characterized by progressive vision loss and the advancement of retinal micoraneurysms, edema and angiogenesis. Unfortunately, managing glycemia or targeting vascular complications with anti-vascular endothelial growth factor agents has shown only limited efficacy in treating the deterioration of vision in diabetic retinopathy. In light of growing evidence that mitochondrial dysfunction is an independent pathophysiology of diabetes and diabetic retinopathy, we investigated whether selectively targeting and improving mitochondrial dysfunction is a viable treatment for visual decline in diabetes. Measures of spatial visual behavior, blood glucose, bodyweight and optical clarity were made in mouse models of diabetes. Treatment groups were administered MTP-131, a water-soluble tetrapeptide that selectively targets mitochondrial cardiolipin and promotes efficient electron transfer, either systemically or in eye drops. Progressive visual decline emerged in untreated animals before the overt symptoms of metabolic and ophthalmic abnormalities were manifest, but with time, visual dysfunction was accompanied by compromised glucose clearance, and elevated blood glucose and bodyweight. MTP-131 treatment reversed the visual decline without improving glycemic control or reducing bodyweight. These data provide evidence that visuomotor decline is an early complication of diabetes. They also indicate that selectively treating mitochondrial dysfunction with MTP-131 has the potential to remediate the visual dysfunction and to complement existing treatments for diabetic retinopathy. Summary: Visual decline in mouse models of diabetes is reversed, independently of treating other disease symptoms, by treatment with MTP-131, a water-soluble peptide that selectively targets cardiolipin and improves mitochondrial bioenergetics.
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Affiliation(s)
- Nazia M Alam
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY, USA Burke Medical Research Institute, White Plains, NY, USA
| | - William C Mills
- Research Program in Mitochondrial Therapeutics, Department of Pharmacology, Weill Cornell Medical College, New York, NY, USA
| | - Aimee A Wong
- Burke Medical Research Institute, White Plains, NY, USA
| | - Robert M Douglas
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Hazel H Szeto
- Research Program in Mitochondrial Therapeutics, Department of Pharmacology, Weill Cornell Medical College, New York, NY, USA
| | - Glen T Prusky
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY, USA Burke Medical Research Institute, White Plains, NY, USA
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24
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High sugar-induced repression of antioxidant and anti-apoptotic genes in lens: Reversal by pyruvate. Mol Cell Biochem 2015; 403:149-58. [DOI: 10.1007/s11010-015-2345-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 01/30/2015] [Indexed: 11/26/2022]
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25
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Ola MS, Alhomida AS. Neurodegeneration in diabetic retina and its potential drug targets. Curr Neuropharmacol 2014; 12:380-6. [PMID: 25342945 PMCID: PMC4207077 DOI: 10.2174/1570159x12666140619205024] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Revised: 04/27/2014] [Accepted: 06/19/2014] [Indexed: 12/04/2022] Open
Abstract
Diabetic retinopathy (DR) is one of the major complications of diabetes causing vision loss and blindness worldwide. DR is widely recognized as a neurodegenerative disease as evidenced from early changes at cellular and molecular levels in the neuronal component of the diabetic retina, which is further supported by various retinal functional tests indicating functional deficits in the retina soon after diabetes progression. Diabetes alters the level of a number of neurodegenerative metabolites, which increases influx through several metabolic pathways which in turn induce an increase in oxidative stress and a decrease in neurotrophic factors, thereby damage retinal neurons. Loss of neurons may implicate in vascular pathology, a clinical signs of DR observed at later stages of the disease. Here, we discuss diabetes-induced potential metabolites known to be detrimental to neuronal damage and their mechanism of action. In addition, we highlight important neurotrophic factors, whose level have been found to be dysregulated in diabetic retina and may damage neurons. Furthermore, we discuss potential drugs and strategies based on targeting diabetes-induced metabolites, metabolic pathways, oxidative stress, and neurotrophins to protect retinal neurons, which may ameliorate vision loss and vascular damage in DR.
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Affiliation(s)
- Mohammad Shamsul Ola
- Department of Biochemistry, College of Science, King Saud University, Riyadh, KSA, Saudi Arabia
| | - Abdullah S Alhomida
- Department of Biochemistry, College of Science, King Saud University, Riyadh, KSA, Saudi Arabia
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26
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Szeto HH, Birk AV. Serendipity and the discovery of novel compounds that restore mitochondrial plasticity. Clin Pharmacol Ther 2014; 96:672-83. [PMID: 25188726 DOI: 10.1038/clpt.2014.174] [Citation(s) in RCA: 124] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Accepted: 08/23/2014] [Indexed: 01/10/2023]
Abstract
The mitochondrial electron transport chain (ETC) plays a central role in energy generation in the cell. Mitochondrial dysfunctions diminish adenosine triphosphate (ATP) production and result in insufficient energy to maintain cell function. As energy output declines, the most energetic tissues are preferentially affected. To satisfy cellular energy demands, the mitochondrial ETC needs to be able to elevate its capacity to produce ATP at times of increased metabolic demand or decreased fuel supply. This mitochondrial plasticity is reduced in many age-associated diseases. In this review, we describe the serendipitous discovery of a novel class of compounds that selectively target cardiolipin on the inner mitochondrial membrane to optimize efficiency of the ETC and thereby restore cellular bioenergetics in aging and diverse disease models, without any effect on the normal healthy organism. The first of these compounds, SS-31, is currently in multiple clinical trials.
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Affiliation(s)
- H H Szeto
- Research Program in Mitochondrial Therapeutics, Department of Pharmacology, Weill Cornell Medical College, New York, New York, USA
| | - A V Birk
- Research Program in Mitochondrial Therapeutics, Department of Pharmacology, Weill Cornell Medical College, New York, New York, USA
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27
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Catrina SB. Impaired hypoxia-inducible factor (HIF) regulation by hyperglycemia. J Mol Med (Berl) 2014; 92:1025-34. [PMID: 25027070 DOI: 10.1007/s00109-014-1166-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Revised: 05/06/2014] [Accepted: 05/08/2014] [Indexed: 12/13/2022]
Abstract
The mechanisms that contribute to the development of diabetes complications remain unclear. A defective reaction of tissues to hypoxia has recently emerged as a new pathogenic mechanism and consists of a complex repression of hypoxia-inducible factor (HIF), which is the main regulator of the adaptive response to hypoxia. This paper discusses the mechanisms by which hyperglycaemia contributes to HIF repression in diabetes. Furthermore, a comprehensive analysis of the functional relevance of these new findings to the development of chronic diabetes complications is provided, along with examples from animal models and clinics.
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Affiliation(s)
- Sergiu-Bogdan Catrina
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska University Hospital, L1:01, 17176, Stockholm, Sweden,
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28
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Kim E, Tolhurst AT, Cho S. Deregulation of inflammatory response in the diabetic condition is associated with increased ischemic brain injury. J Neuroinflammation 2014; 11:83. [PMID: 24886035 PMCID: PMC4017808 DOI: 10.1186/1742-2094-11-83] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Accepted: 03/26/2014] [Indexed: 01/04/2023] Open
Abstract
Background Although elicited inflammation contributes to tissue injury, a certain level of inflammation is necessary for subsequent tissue repair/remodeling. Diabetes, a chronic low-grade inflammatory state, is a predisposing risk factor for stroke. The condition is associated with delayed wound healing, presumably due to disrupted inflammatory responses. With inclusion of the diabetic condition in an experimental animal model of stroke, this study investigates whether the condition alters inflammatory response and influences stroke-induced brain injury. Methods C57BL/6 mice were fed a diabetic diet (DD) for 8 weeks to induce an experimental diabetic condition or a normal diet (ND) for the same duration. Gene expression of inflammatory factors including monocyte chemoattractant protein-1 (MCP-1), interleukin-6 (IL-6), CCR2, and CD36 was assessed in the peripheral immune cells and brains of normal and diabetic mice before and after focal cerebral ischemia. The expression of these factors was also determined in lipopolysaccharide (LPS)-treated cultured normal and diabetic macrophages. Ischemic outcome was assessed in these mice at 3 days post-ischemia. Results DD intervention in mice resulted in obesity and elevated insulin and glucose level in the blood. The peritoneal immune cells from the diabetic mice showed higher MCP-1 mRNA levels before and after stroke. Compared to normal mice, diabetic mice showed reduced MCP-1, IL-6, and CCR2 gene expression in the brain at 6 h post-ischemia. LPS-stimulated inflammatory responses were also reduced in the diabetic macrophages. The diabetic mice showed larger infarct size and percent swelling. Conclusions These results showed that diabetic conditions deregulate acute inflammatory response and that the condition is associated with increased stroke-induced injury. The study suggests that interventions aimed at restoring appropriate inflammatory response in peripheral immune cells/macrophages may be beneficial in reducing stroke-induced brain injury in subjects with chronic inflammatory conditions.
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Affiliation(s)
| | | | - Sunghee Cho
- Burke-Cornell Medical Research Institute, White Plains, NY 10605, USA.
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29
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Ola MS. Effect of hyperglycemia on insulin receptor signaling in the cultured retinal Müller glial cells. Biochem Biophys Res Commun 2014; 444:264-9. [DOI: 10.1016/j.bbrc.2014.01.052] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Accepted: 01/15/2014] [Indexed: 12/16/2022]
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Szabadfi K, Pinter E, Reglodi D, Gabriel R. Neuropeptides, trophic factors, and other substances providing morphofunctional and metabolic protection in experimental models of diabetic retinopathy. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2014; 311:1-121. [PMID: 24952915 DOI: 10.1016/b978-0-12-800179-0.00001-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Vision is the most important sensory modality for many species, including humans. Damage to the retina results in vision loss or even blindness. One of the most serious complications of diabetes, a disease that has seen a worldwide increase in prevalence, is diabetic retinopathy. This condition stems from consequences of pathological metabolism and develops in 75% of patients with type 1 and 50% with type 2 diabetes. The development of novel protective drugs is essential. In this review we provide a description of the disease and conclude that type 1 diabetes and type 2 diabetes lead to the same retinopathy. We evaluate existing experimental models and recent developments in finding effective compounds against this disorder. In our opinion, the best models are the long-term streptozotocin-induced diabetes and Otsuka Long-Evans Tokushima Fatty and spontaneously diabetic Torii rats, while the most promising substances are topically administered somatostatin and pigment epithelium-derived factor analogs, antivasculogenic substances, and systemic antioxidants. Future drug development should focus on these.
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Affiliation(s)
- Krisztina Szabadfi
- Department of Experimental Zoology and Neurobiology, University of Pecs, Pecs, Hungary; Janos Szentagothai Research Center, University of Pecs, Pecs, Hungary.
| | - Erika Pinter
- Janos Szentagothai Research Center, University of Pecs, Pecs, Hungary; Department of Pharmacology and Pharmacotherapy, University of Pecs, Pecs, Hungary
| | - Dora Reglodi
- Department of Anatomy, PTE MTA Lendulet-PACAP Research Team, University of Pecs, Pecs, Hungary
| | - Robert Gabriel
- Department of Experimental Zoology and Neurobiology, University of Pecs, Pecs, Hungary; Janos Szentagothai Research Center, University of Pecs, Pecs, Hungary
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31
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Fajardo RJ, Karim L, Calley VI, Bouxsein ML. A review of rodent models of type 2 diabetic skeletal fragility. J Bone Miner Res 2014; 29:1025-40. [PMID: 24585709 PMCID: PMC5315418 DOI: 10.1002/jbmr.2210] [Citation(s) in RCA: 115] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 02/21/2014] [Accepted: 02/25/2014] [Indexed: 12/21/2022]
Abstract
Evidence indicating that adult type 2 diabetes (T2D) is associated with increased fracture risk continues to mount. Unlike osteoporosis, diabetic fractures are associated with obesity and normal to high bone mineral density, two factors that are typically associated with reduced fracture risk. Animal models will likely play a critical role in efforts to identify the underlying mechanisms of skeletal fragility in T2D and to develop preventative treatments. In this review we critically examine the ability of current rodent models of T2D to mimic the skeletal characteristics of human T2D. We report that although there are numerous rodent models of T2D, few have undergone thorough assessments of bone metabolism and strength. Further, we find that many of the available rodent models of T2D have limitations for studies of skeletal fragility in T2D because the onset of diabetes is often prior to skeletal maturation and bone mass is low, in contrast to what is seen in adult humans. There is an urgent need to characterize the skeletal phenotype of existing models of T2D, and to develop new models that more closely mimic the skeletal effects seen in adult-onset T2D in humans.
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Affiliation(s)
- Roberto J. Fajardo
- Department of Orthopaedics, University of Texas Health Science Center at San Antonio
| | - Lamya Karim
- Center for Advanced Orthopaedic Studies, Beth Israel Deaconess Medical Center and Harvard Medical School
| | - Virginia I. Calley
- Department of Orthopaedics, University of Texas Health Science Center at San Antonio
| | - Mary L. Bouxsein
- Center for Advanced Orthopaedic Studies, Beth Israel Deaconess Medical Center and Harvard Medical School
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32
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Sugimoto M, Cutler A, Shen B, Moss SE, Iyengar SK, Klein R, Folkman J, Anand-Apte B. Inhibition of EGF signaling protects the diabetic retina from insulin-induced vascular leakage. THE AMERICAN JOURNAL OF PATHOLOGY 2013; 183:987-95. [PMID: 23831329 DOI: 10.1016/j.ajpath.2013.05.017] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Revised: 05/02/2013] [Accepted: 05/14/2013] [Indexed: 02/03/2023]
Abstract
Diabetes mellitus is a disease with considerable morbidity and mortality worldwide. Breakdown of the blood-retinal barrier and leakage from the retinal vasculature leads to diabetic macular edema, an important cause of vision loss in patients with diabetes. Although epidemiologic studies and randomized clinical trials suggest that glycemic control plays a major role in the development of vascular complications of diabetes, insulin therapies for control of glucose metabolism cannot prevent long-term retinal complications. The phenomenon of temporary paradoxical worsening of diabetic macular edema after insulin treatment has been observed in a number of studies. In prospective studies on non-insulin-dependent (type 2) diabetes mellitus patients, a change in treatment from oral drugs to insulin was often associated with a significant increased risk of retinopathy progression and visual impairment. Although insulin therapies are critical for regulation of the metabolic disease, their role in the retina is controversial. In this study with diabetic mice, insulin treatment resulted in increased vascular leakage apparently mediated by betacellulin and signaling via the epidermal growth factor (EGF) receptor. In addition, treatment with EGF receptor inhibitors reduced retinal vascular leakage in diabetic mice on insulin. These findings provide unique insight into the role of insulin signaling in mediating retinal effects in diabetes and open new avenues for therapeutics to treat the retinal complications of diabetes mellitus.
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Affiliation(s)
- Masahiko Sugimoto
- Department of Ophthalmology, Cole Eye Institute, Cleveland Clinic Lerner College of Medicine, Cleveland Clinic, Cleveland, Ohio 44195, USA
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Ling S, Birnbaum Y, Nanhwan MK, Thomas B, Bajaj M, Li Y, Li Y, Ye Y. Dickkopf-1 (DKK1) phosphatase and tensin homolog on chromosome 10 (PTEN) crosstalk via microRNA interference in the diabetic heart. Basic Res Cardiol 2013; 108:352. [PMID: 23636253 DOI: 10.1007/s00395-013-0352-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 03/12/2013] [Accepted: 04/05/2013] [Indexed: 12/14/2022]
Abstract
Competitive endogenous RNAs (ceRNAs) regulate mRNA transcripts containing common microRNA (miRNA) recognition elements (MREs) through sequestration of shared miRNAs. Interactions of ceRNA have been demonstrated in cancerous cells. However, a paucity of information is available relative to the interactions of ceRNAs interaction in diabetes mellitus and the myocardium. The purpose of this study is to assess the potential role of DKK1 and PTEN in ceRNA regulation utilizing their common miRNAs in diabetic cardiomyocytes. The interactions' regulation between PTEN and DKK1 were determined in two diabetic models in vivo (streptozotocin-induced type-1 DM mice and db/db mice) and in vitro (human cardiomyocytes cells exposed to hyperglycemia). The levels of DKK1 and PTEN (mRNA and protein) were upregulated in parallel in all three diabetic models. DKK1 modulates PTEN protein levels in a miRNA and 3'UTR-dependent manner. RNAi-mediated DKK1 gene silencing resulted in a decreased PTEN expression and vice versa. The effect was blocked when Dicer was inhibited. Silencing either PTEN or DKK1 resulted in an increase of the availabilities of shared miRNAs. The silencing of either PTEN or DKKI resulted in a suppression end of the luciferase-PTEN 3'UTR activity. However, the over expression of DKK1 3'UTR or PTEN 3'UTR resulted in an increase in the activity. The attenuation of DKK1 increased AKT phosphorylation, improved glucose uptake and decreased apoptosis in HCMs exposed to hyperglycemia. The effects were blocked by PI3K inhibition. DKK1 and PTEN transcripts are co-upregulated in DM and hyperglycemia. DKK1 and PTEN serve as ceRNA, affecting the expression of each other via competition for miRNAs binding.
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Affiliation(s)
- Shukuan Ling
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, Heilongjiang, China
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34
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Ola MS, Nawaz MI, Khan HA, Alhomida AS. Neurodegeneration and neuroprotection in diabetic retinopathy. Int J Mol Sci 2013; 14:2559-72. [PMID: 23358247 PMCID: PMC3588002 DOI: 10.3390/ijms14022559] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2012] [Revised: 01/12/2013] [Accepted: 01/17/2013] [Indexed: 02/06/2023] Open
Abstract
Diabetic retinopathy is widely considered to be a neurovascular disease. This is in contrast to its previous identity as solely a vascular disease. Early in the disease progression of diabetes, the major cells in the neuronal component of the retina consist of retinal ganglion cells and glial cells, both of which have been found to be compromised. A number of retinal function tests also indicated a functional deficit in diabetic retina, which further supports dysfunction of neuronal cells. As an endocrinological disorder, diabetes alters metabolism both systemically and locally in several body organs, including the retina. A growing body of evidences indicates increased levels of excitotoxic metabolites, including glutamate, branched chain amino acids and homocysteine in cases of diabetic retinopathy. Also present, early in the disease, are decreased levels of folic acid and vitamin-B12, which are potential metabolites capable of damaging neurons. These altered levels of metabolites are found to activate several metabolic pathways, leading to increases in oxidative stress and decreases in the level of neurotrophic factors. As a consequence, they may damage retinal neurons in diabetic patients. In this review, we have discussed those potential excitotoxic metabolites and their implications in neuronal damage. Possible therapeutic targets to protect neurons are also discussed. However, further research is needed to understand the exact molecular mechanism of neurodegeneration so that effective neuroprotection strategies can be developed. By protecting retinal neurons early in diabetic retinopathy cases, damage of retinal vessels can be protected, thereby helping to ameliorate the progression of diabetic retinopathy, a leading cause of blindness worldwide.
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Affiliation(s)
- Mohammad Shamsul Ola
- Department of Biochemistry, Faculty of Science, King Saud University, Riyadh 11415, Saudi Arabia.
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Na J, Musselman LP, Pendse J, Baranski TJ, Bodmer R, Ocorr K, Cagan R. A Drosophila model of high sugar diet-induced cardiomyopathy. PLoS Genet 2013; 9:e1003175. [PMID: 23326243 PMCID: PMC3542070 DOI: 10.1371/journal.pgen.1003175] [Citation(s) in RCA: 175] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Accepted: 10/22/2012] [Indexed: 12/16/2022] Open
Abstract
Diets high in carbohydrates have long been linked to progressive heart dysfunction, yet the mechanisms by which chronic high sugar leads to heart failure remain poorly understood. Here we combine diet, genetics, and physiology to establish an adult Drosophila melanogaster model of chronic high sugar-induced heart disease. We demonstrate deterioration of heart function accompanied by fibrosis-like collagen accumulation, insulin signaling defects, and fat accumulation. The result was a shorter life span that was more severe in the presence of reduced insulin and P38 signaling. We provide evidence of a role for hexosamine flux, a metabolic pathway accessed by glucose. Increased hexosamine flux led to heart function defects and structural damage; conversely, cardiac-specific reduction of pathway activity prevented sugar-induced heart dysfunction. Our data establish Drosophila as a useful system for exploring specific aspects of diet-induced heart dysfunction and emphasize enzymes within the hexosamine biosynthetic pathway as candidate therapeutic targets.
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Affiliation(s)
- Jianbo Na
- Department of Developmental and Regenerative Biology, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Laura Palanker Musselman
- Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Jay Pendse
- Department of Developmental and Regenerative Biology, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Thomas J. Baranski
- Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Rolf Bodmer
- Development and Aging Program, NASCR Center, Sanford-Burnham Medical Research Institute, La Jolla, California, United States of America
| | - Karen Ocorr
- Development and Aging Program, NASCR Center, Sanford-Burnham Medical Research Institute, La Jolla, California, United States of America
- * E-mail:
| | - Ross Cagan
- Department of Developmental and Regenerative Biology, Mount Sinai School of Medicine, New York, New York, United States of America
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Marçal AC, Leonelli M, Fiamoncini J, Deschamps FC, Rodrigues MAM, Curi R, Carpinelli AR, Britto LRG, Carvalho CRO. Diet-induced obesity impairs AKT signalling in the retina and causes retinal degeneration. Cell Biochem Funct 2012; 31:65-74. [PMID: 22915345 DOI: 10.1002/cbf.2861] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2011] [Revised: 06/18/2012] [Accepted: 07/05/2012] [Indexed: 11/06/2022]
Abstract
Retinopathy, a common complication of diabetes, is characterized by an unbalanced production of nitric oxide (NO), a process regulated by nitric oxide synthase (NOS). We hypothesized that retinopathy might stem from changes in the insulin receptor substrate (IRS)/PI3K/AKT pathway and/or expression of NOS isoforms. Thus, we analysed the morphology and apoptosis index in retinas of obese rats in whom insulin resistance had been induced by a high-fat diet (HFD). Immunoblotting analysis revealed that the retinal tissue of HFD rats had lower levels of AKT(1) , eNOS and nNOS protein than those of samples taken from control animals. Furthermore, immunohistochemical analyses indicated higher levels of iNOS and 4-hydroxynonenal and a larger number of apoptotic nuclei in HFD rats. Finally, both the inner and outer retinal layers of HFD rats were thinner than those in their control counterparts. When considered alongside previous results, these patterns suggest two major ways in which HFD might impact animals: direct activity of ingested fatty acids and/or via insulin-resistance-induced changes in intracellular pathways. We discuss these possibilities in further detail and advocate the use of this animal model for further understanding relationships between retinopathy, metabolic syndrome and type 2 diabetes.
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Affiliation(s)
- Anderson C Marçal
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biomédicas (ICB), Universidade de São Paulo (USP), SP, Brazil.
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Seong HA, Jung H, Manoharan R, Ha H. PDK1 protein phosphorylation at Thr354 by murine protein serine-threonine kinase 38 contributes to negative regulation of PDK1 protein activity. J Biol Chem 2012; 287:20811-22. [PMID: 22544756 DOI: 10.1074/jbc.m111.331827] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Murine protein serine-threonine kinase 38 (MPK38) is a member of the AMP-activated protein kinase-related serine/threonine kinase family, which acts as cellular energy sensors. In this study, MPK38-induced PDK1 phosphorylation was examined to elucidate the biochemical mechanisms underlying phosphorylation-dependent regulation of 3-phosphoinositide-dependent protein kinase-1 (PDK1) activity. The results showed that MPK38 interacted with and inhibited PDK1 activity via Thr(354) phosphorylation. MPK38-PDK1 complex formation was mediated by the amino-terminal catalytic kinase domain of MPK38 and the pleckstrin homology domain of PDK1. This activity was dependent on insulin, a PI3K/PDK1 stimulator, as well as various apoptotic stimuli, including TNF-α, H(2)O(2), thapsigargin, and ionomycin. MPK38 inhibited PDK1 activity in a kinase-dependent manner and alleviated PDK1-mediated suppression of TGF-β (or ASK1) signaling, probably via the phosphorylation of PDK1 at Thr(354). In addition, MPK38-mediated inhibition of PDK1 activity was accompanied by the modulation of PDK1 binding to its positive and negative regulators, serine/threonine kinase receptor-associated protein and 14-3-3, respectively. Together, these findings suggest an important role for MPK38-mediated phosphorylation of PDK1 in the negative regulation of PDK1 activity.
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Affiliation(s)
- Hyun-A Seong
- Department of Biochemistry, School of Life Sciences, Chungbuk National University, Cheongju 361-763, Republic of Korea.
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Affiliation(s)
- David A Antonetti
- Department of Ophthalmology and Visual Sciences, University of Michigan Medical School, Ann Arbor, USA
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Walker RJ, Anderson NM, Jiang Y, Bahouth S, Steinle JJ. Role of β-adrenergic receptor regulation of TNF-α and insulin signaling in retinal Muller cells. Invest Ophthalmol Vis Sci 2011; 52:9527-33. [PMID: 22110065 DOI: 10.1167/iovs.11-8631] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE The goal of this study was to determine the relationship of TNF-α and the downregulation of insulin receptor signaling in retinal Müller cells cultured under hyperglycemic conditions and the role of β-adrenergic receptors in regulating these responses. METHODS Retinal Müller cells were cultured in normal (5 mM) or high (25 mM) glucose until 80% confluent and then were reduced to 2% serum for 18 to 24 hours. The cells were then treated with 10 μM salmeterol followed by Western blot analysis or ELISA. For TNF-α inhibitory studies, the cells were treated with 5 ng/mL of TNF-α for 30 minutes or by a 30-minute pretreatment with TNF-α followed by salmeterol for 6 hours. In the TNF-α short hairpin (sh)RNA experiments, the cells were cultured until 90% confluent, followed by transfection with TNF-α shRNA for 18 hours. RESULTS TNF-α-only treatments of Müller cells resulted in significant decreases of tyrosine phosphorylation of the insulin receptor and Akt in high-glucose conditions. Salmeterol (10 μM), a β-2-adrenergic receptor agonist, significantly increased phosphorylation of both insulin receptor and Akt. TNF-α shRNA significantly decreased phosphorylation of IRS-1(Ser307), which was further decreased after salmeterol+TNF-α shRNA. Both TNF-α shRNA and salmeterol significantly reduced death of the retinal Müller cells. CONCLUSIONS These studies demonstrate that β-adrenergic receptor agonists in vitro can restore the loss of insulin receptor activity noted in diabetes. By decreasing the levels of TNF-α and decreasing the phosphorylation of IRS-1(Ser307) while increasing tyrosine phosphorylation of insulin receptor, these results suggest a possible mechanism by which restoration of β-adrenergic receptor signaling may protect the retina against diabetes-induced damage.
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Affiliation(s)
- Robert J Walker
- Department of Ophthalmology, Hamilton Eye Institute, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA
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Lin M, Chen Y, Jin J, Hu Y, Zhou KK, Zhu M, Le YZ, Ge J, Johnson RS, Ma JX. Ischaemia-induced retinal neovascularisation and diabetic retinopathy in mice with conditional knockout of hypoxia-inducible factor-1 in retinal Müller cells. Diabetologia 2011; 54:1554-66. [PMID: 21360191 PMCID: PMC6592825 DOI: 10.1007/s00125-011-2081-0] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Accepted: 01/19/2011] [Indexed: 12/22/2022]
Abstract
AIMS/HYPOTHESIS Retinal Müller cells are known to produce inflammatory and angiogenic cytokines, which play important roles in diabetic retinopathy. Hypoxia-inducible factor (HIF)-1 has been shown to play a crucial role in retinal inflammation and neovascularisation. We sought to determine the role of Müller cell-derived HIF-1 in oxygen-induced retinopathy (OIR) and diabetic retinopathy using conditional Hif-1α (also known as Hif1a) knockout (KO) mice. METHODS Conditional Hif-1α KO mice were generated by crossing mice expressing cyclisation recombinase (cre, also known as P1_gp003) in Müller cells with floxed Hif-1α mice and used for OIR and streptozotocin-induced diabetes to induce retinal neovascularisation and inflammation, respectively. Abundance of HIF-1α and pro-angiogenic and pro-inflammatory factors was measured by immunoblotting and immunohistochemistry. Retinal neovascularisation was visualised by angiography and quantified by counting pre-retinal nuclei. Retinal inflammation was evaluated by leucostasis and vascular leakage. RESULTS While the Hif-1α KO mice showed significantly decreased HIF-1α levels in the retina, they exhibited no apparent histological or visual functional abnormalities under normal conditions. Compared with wild-type counterparts, Hif-1α KO mice with OIR demonstrated attenuated overproduction of vascular endothelial growth factor (VEGF) and intercellular adhesion molecule (ICAM)-1, reduced vascular leakage and alleviated neovascularisation in the retina. Under diabetes conditions, disruption of Hif-1α in Müller cells attenuated the increases of retinal vascular leakage and adherent leucocytes, as well as the overproduction of VEGF and ICAM-1. CONCLUSIONS/INTERPRETATION Müller cell-derived HIF-1α is a key mediator of retinal neovascularisation, vascular leakage and inflammation, the major pathological changes in diabetic retinopathy. Müller cell-derived HIF-1α is therefore a promising therapeutic target for diabetic retinopathy.
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Affiliation(s)
- M Lin
- Department of Physiology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
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Hemi R, Yochananov Y, Barhod E, Kasher-Meron M, Karasik A, Tirosh A, Kanety H. p38 mitogen-activated protein kinase-dependent transactivation of ErbB receptor family: a novel common mechanism for stress-induced IRS-1 serine phosphorylation and insulin resistance. Diabetes 2011; 60:1134-45. [PMID: 21386087 PMCID: PMC3064087 DOI: 10.2337/db09-1323] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
OBJECTIVE Stress stimuli such as tumor necrosis factor (TNF) have been shown to induce insulin receptor substrate (IRS)-1 serine phosphorylation and insulin resistance by transactivation of ErbB receptors. We aimed at elucidating the potential role of p38 mitogen-activated protein kinase (p38MAPK) in mediating stress-induced ErbB receptors activation. RESEARCH DESIGN AND METHODS p38MAPK effect on ErbBs transactivation and insulin signaling was assessed in Fao or HepG2 cells, exposed to stress stimuli, and on metabolic parameters in ob/ob and C57/BL6 mice. RESULTS High-fat diet-fed mice and ob/ob mice exhibited elevated hepatic p38MAPK activation associated with glucose intolerance and hyperinsulinemia. Liver expression of dominant-negative (DN)-p38MAPKα in ob/ob mice reduced fasting insulin levels and improved glucose tolerance, whereas C57/BL6 mice overexpressing wild-type p38MAPKα exhibited enhanced IRS-1 serine phosphorylation and reduced insulin-stimulated IRS-1 tyrosine phosphorylation. Fao or HepG2 cells exposed to TNF, anisomycin, or sphingomyelinase demonstrated rapid transactivation of ErbB receptors leading to PI3-kinase/Akt activation and IRS-1 serine phosphorylation. p38MAPK inhibition either by SB203580, by small interfering RNA, or by DN-p38MAPKα decreased ErbB receptors transactivation and IRS-1 serine phosphorylation and partially restored insulin-stimulated IRS-1 tyrosine phosphorylation. When cells were incubated with specific ErbB receptors antagonists or in cells lacking ErbB receptors, anisomycin- and TNF-induced IRS-1 serine phosphorylation was attenuated, despite intact p38MAPK activation. The stress-induced p38MAPK activation leading to ErbB receptors transactivation was associated with intracellular reactive oxygen species generation and was attenuated by treatment with antioxidants. CONCLUSIONS Hepatic p38MAPK is activated following various stress stimuli. This event is upstream to ErbB receptors transactivation and plays an important role in stress-induced IRS-1 serine phosphorylation and insulin resistance.
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Affiliation(s)
- Rina Hemi
- Institute of Endocrinology, Chaim Sheba Medical Center, Tel-Hashomer, Israel
| | - Yafit Yochananov
- Institute of Endocrinology, Chaim Sheba Medical Center, Tel-Hashomer, Israel
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Ehud Barhod
- Institute of Endocrinology, Chaim Sheba Medical Center, Tel-Hashomer, Israel
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Michal Kasher-Meron
- Institute of Endocrinology, Chaim Sheba Medical Center, Tel-Hashomer, Israel
- The Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Avraham Karasik
- Institute of Endocrinology, Chaim Sheba Medical Center, Tel-Hashomer, Israel
- The Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Amir Tirosh
- Institute of Endocrinology, Chaim Sheba Medical Center, Tel-Hashomer, Israel
| | - Hannah Kanety
- Institute of Endocrinology, Chaim Sheba Medical Center, Tel-Hashomer, Israel
- The Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- Corresponding author: Hannah Kanety,
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Wang SC, Lee SF, Wang CJ, Lee CH, Lee WC, Lee HJ. Aqueous Extract from Hibiscus sabdariffa Linnaeus Ameliorate Diabetic Nephropathy via Regulating Oxidative Status and Akt/Bad/14-3-3γ in an Experimental Animal Model. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2011; 2011:938126. [PMID: 19965962 PMCID: PMC3139510 DOI: 10.1093/ecam/nep181] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Accepted: 10/04/2009] [Indexed: 12/20/2022]
Abstract
Several studies point out that oxidative stress maybe a major culprit in diabetic nephropathy. Aqueous extract of Hibiscus sabdariffa L. (HSE) has been demonstrated as having beneficial effects on anti-oxidation and lipid-lowering in experimental studies. This study aimed at investigating the effects of Hibiscus sabdariffa L. on diabetic nephropathy in streptozotocin induced type 1 diabetic rats. Our results show that HSE is capable of reducing lipid peroxidation, increasing catalase and glutathione activities significantly in diabetic kidney, and decreasing the plasma levels of triglyceride, low-density lipoprotein (LDL) and increasing high-density lipoprotein (HDL) value. In histological examination, HSE improves hyperglycemia-caused osmotic diuresis in renal proximal convoluted tubules (defined as hydropic change) in diabetic rats. The study also reveals that up-regulation of Akt/Bad/14-3-3γ and NF-κB-mediated transcription might be involved. In conclusion, our results show that HSE possesses the potential effects to ameliorate diabetic nephropathy via improving oxidative status and regulating Akt/Bad/14-3-3γ signaling.
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Affiliation(s)
- Shou-Chieh Wang
- Institute of Medicine, Medical College, Chung Shan Medical University, Taiwan
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Gardner TW, Abcouwer SF, Barber AJ, Jackson GR. An integrated approach to diabetic retinopathy research. ARCHIVES OF OPHTHALMOLOGY (CHICAGO, ILL. : 1960) 2011; 129:230-5. [PMID: 21320973 PMCID: PMC3086099 DOI: 10.1001/archophthalmol.2010.362] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
This review discusses the pathophysiology of diabetic retinopathy related to direct effects of loss of insulin receptor action and metabolic dysregulation on the retina. The resulting sensory neuropathy can be diagnosed by structural and functional tests in patients with mild nonproliferative diabetic retinopathy. Research teams can collaborate to integrate ocular and systemic factors that impair vision and to design strategies to maintain retinal function in persons with diabetes mellitus. Evolving concepts may lead to inclusion of tests of retinal function in the detection of diabetic retinopathy and neuroprotective strategies to preserve vision for persons with diabetes.
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Wang J, Xu X, Elliott MH, Zhu M, Le YZ. Müller cell-derived VEGF is essential for diabetes-induced retinal inflammation and vascular leakage. Diabetes 2010; 59:2297-305. [PMID: 20530741 PMCID: PMC2927953 DOI: 10.2337/db09-1420] [Citation(s) in RCA: 283] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Vascular endothelial growth factor (VEGF-A or VEGF) is a major pathogenic factor and therapeutic target for diabetic retinopathy (DR). Since VEGF has been proposed as a survival factor for retinal neurons, defining the cellular origin of pathogenic VEGF is necessary for the effectiveness and safety of long-term anti-VEGF therapies for DR. To determine the significance of Müller cell-derived VEGF in DR, we disrupted VEGF in Müller cells with an inducible Cre/lox system and examined diabetes-induced retinal inflammation and vascular leakage in these conditional VEGF knockout (KO) mice. RESEARCH DESIGN AND METHODS Leukostasis was determined by counting the number of fluorescently labeled leukocytes inside retinal vasculature. Expression of biomarkers for retinal inflammation was assessed by immunoblotting of TNF-alpha, ICAM-1, and NF-kappaB. Vascular leakage was measured by immunoblotting of retinal albumin and fluorescent microscopic analysis of extravascular albumin. Diabetes-induced vascular alterations were examined by immunoblotting and immunohistochemistry for tight junctions, and by trypsin digestion assays for acellular capillaries. Retinal integrity was analyzed with morphologic and morphometric analyses. RESULTS Diabetic conditional VEGF KO mice exhibited significantly reduced leukostasis, expression of inflammatory biomarkers, depletion of tight junction proteins, numbers of acellular capillaries, and vascular leakage compared to diabetic control mice. CONCLUSIONS Müller cell-derived VEGF plays an essential and causative role in retinal inflammation, vascular lesions, and vascular leakage in DR. Therefore, Müller cells are a primary cellular target for proinflammatory signals that mediates retinal inflammation and vascular leakage in DR.
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Affiliation(s)
- Juanjuan Wang
- Department of Ophthalmology, Xiangya Hospital, Central South University, Changsha, China
- Department of Medicine Endocrinology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
- Harold Hamm Oklahoma Diabetes Center, University of Oklahoma, Oklahoma City, Oklahoma
| | - Xueliang Xu
- Department of Ophthalmology, Xiangya Hospital, Central South University, Changsha, China
| | - Michael H. Elliott
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
- Dean A. McGee Eye Institute, Oklahoma City, Oklahoma
| | - Meili Zhu
- Department of Medicine Endocrinology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
- Harold Hamm Oklahoma Diabetes Center, University of Oklahoma, Oklahoma City, Oklahoma
| | - Yun-Zheng Le
- Department of Medicine Endocrinology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
- Harold Hamm Oklahoma Diabetes Center, University of Oklahoma, Oklahoma City, Oklahoma
- Dean A. McGee Eye Institute, Oklahoma City, Oklahoma
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
- Corresponding author: Yun-Zheng Le,
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Yang J, Duh EJ, Caldwell RB, Behzadian MA. Antipermeability function of PEDF involves blockade of the MAP kinase/GSK/beta-catenin signaling pathway and uPAR expression. Invest Ophthalmol Vis Sci 2010; 51:3273-80. [PMID: 20089873 DOI: 10.1167/iovs.08-2878] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Pigment epithelium-derived factor (PEDF) is a potent inhibitor of vascular endothelial growth factor (VEGF)-induced endothelial permeability. The goal of this study was to understand the mechanism by which PEDF blocks VEGF-induced increases in vascular permeability. METHODS The paracellular permeability of bovine retinal endothelial (BRE) cells was measured by assaying transendothelial cell electrical resistance and tracer flux. Western blot analysis was used to show phosphorylation of VEGFR2, MAP kinases, and glycogen synthase kinase 3 (GSK3)-beta. Confocal imaging and Western blot analysis were used to determine subcellular distribution of beta-catenin. Real-time RT-PCR and Western blot analysis were used to quantify urokinase plasminogen activator receptor (uPAR) expression. RESULTS PEDF blocked VEGF-induced phosphorylation of extracellular signal-regulated kinase (ERK), p38 MAP kinase, the p38 substrate MAP kinase-activated protein kinase-2 (MAPKAPK-2), and GSK3-beta, but it had no effect on the phosphorylation of VEGFR2. In addition, the VEGF-induced transcriptional activation of beta-catenin and uPAR expression were blocked by PEDF and by inhibitors of p38 and MEK. Finally, the VEGF-induced increase in permeability was blocked by both PEDF and the same kinase inhibitors. CONCLUSIONS The data suggest that p38 MAP kinase and ERK act upstream of GSK/beta-catenin in VEGF-induced activation of the uPA/uPAR system and that PEDF-mediated inhibition of the VEGF-induced increase in vascular permeability involves blockade of this pathway. These findings are important for developing precise and potent therapies for treatment of diseases characterized by vascular barrier dysfunction.
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Hou J, Cui Z, Xie Z, Xue P, Wu P, Chen X, Li J, Cai T, Yang F. Phosphoproteome Analysis of Rat L6 Myotubes Using Reversed-Phase C18 Prefractionation and Titanium Dioxide Enrichment. J Proteome Res 2010; 9:777-88. [DOI: 10.1021/pr900646k] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Junjie Hou
- Proteomic Platform, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China, and Graduate University of the Chinese Academy of Sciences, Beijing, China
| | - Ziyou Cui
- Proteomic Platform, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China, and Graduate University of the Chinese Academy of Sciences, Beijing, China
| | - Zhensheng Xie
- Proteomic Platform, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China, and Graduate University of the Chinese Academy of Sciences, Beijing, China
| | - Peng Xue
- Proteomic Platform, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China, and Graduate University of the Chinese Academy of Sciences, Beijing, China
| | - Peng Wu
- Proteomic Platform, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China, and Graduate University of the Chinese Academy of Sciences, Beijing, China
| | - Xiulan Chen
- Proteomic Platform, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China, and Graduate University of the Chinese Academy of Sciences, Beijing, China
| | - Jing Li
- Proteomic Platform, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China, and Graduate University of the Chinese Academy of Sciences, Beijing, China
| | - Tanxi Cai
- Proteomic Platform, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China, and Graduate University of the Chinese Academy of Sciences, Beijing, China
| | - Fuquan Yang
- Proteomic Platform, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China, and Graduate University of the Chinese Academy of Sciences, Beijing, China
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Wright WS, McElhatten RM, Messina JE, Harris NR. Hypoxia and the expression of HIF-1alpha and HIF-2alpha in the retina of streptozotocin-injected mice and rats. Exp Eye Res 2009; 90:405-12. [PMID: 20005221 DOI: 10.1016/j.exer.2009.12.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Revised: 12/02/2009] [Accepted: 12/02/2009] [Indexed: 12/26/2022]
Abstract
Decreases in retinal blood flow in diabetics could render the retina hypoxic. In mouse and rat models of diabetes, a decrease in retinal blood flow occurs early, within 3-4 weeks of the induction of hyperglycemia, although information is scarce on whether this early decrease in flow induces hypoxia. The purpose of the current study was to determine whether hypoxia-inducible factor (HIF) levels increase following 4 and/or 12 weeks of hyperglycemia in streptozotocin (STZ)-injected mouse (C57BL/6) and rat (Wistar) retinas. Additionally, retinal tissue hypoxia was measured with pimonidazole following 12 weeks of hyperglycemia. These aims were accomplished via immunostaining of cross-sections from enucleated eyes. In mice, staining for HIF-1alpha and HIF-2alpha showed a contrasting pattern, with HIF-1alpha higher in the inner retina than outer, but HIF-2alpha higher in the outer retina than inner. However, in rats, staining for both HIF-1alpha and HIF-2alpha was more intense in the inner retina. The HIF-1alpha staining intensities and patterns were similar between diabetic animals and their non-diabetic counterparts following 4 and 12 weeks of hyperglycemia. The same was true for HIF-2alpha except for a trend toward an increase following 12 weeks of hyperglycemia in mice. Pimonidazole staining showed significant decreases throughout all layers of the central retina and most layers of the peripheral retina of rats (but not mice), following 12 weeks of hyperglycemia. In summary, despite early decreases in flow in rats and mice, retinal HIF-1alpha and HIF-2alpha were not found to be increased, and the extent of hypoxia may even decrease after 12 weeks of hyperglycemia in rats.
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Affiliation(s)
- William S Wright
- Department of Molecular and Cellular Physiology, Louisiana State University, Health Sciences Center, 1501 Kings Highway, Shreveport, LA 71130, USA
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Kasinath BS, Mariappan MM, Sataranatarajan K, Lee MJ, Ghosh Choudhury G, Feliers D. Novel mechanisms of protein synthesis in diabetic nephropathy--role of mRNA translation. Rev Endocr Metab Disord 2008; 9:255-66. [PMID: 18654857 PMCID: PMC5886780 DOI: 10.1007/s11154-008-9091-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Ambient protein levels are affected by both synthesis and degradation. Synthesis of a protein is regulated by transcription and messenger RNA (mRNA) translation. Translation has emerged as an important site of regulation of protein expression during development and disease. It is under the control of distinct factors that regulate initiation, elongation and termination phases. Regulation of translation occurs via signaling reactions, guanosine diphosphate-guanosine triphosphate binding and by participation of non-coding RNA species such as microRNA. Recent work has revealed an important role for translation in hypertrophy, matrix protein synthesis, elaboration of growth factors in in vivo and in vitro models of diabetic nephropathy. Studies of translation dysregulation in diabetic nephropathy have enabled identification of novel therapeutic targets. Translation of mRNA is a fertile field for exploration in investigation of kidney disease.
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Affiliation(s)
- B S Kasinath
- O'Brien Kidney Research Center, Department of Medicine, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA.
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Zdychová J, Kazdová L, Pelikanová T, Lindsley JN, Anderson S, Komers R. Renal activity of Akt kinase in obese Zucker rats. Exp Biol Med (Maywood) 2008; 233:1231-41. [PMID: 18641049 DOI: 10.3181/0801-rm-29] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Insulin resistance (IR) and consequent hyperinsulinemia are hallmarks of Type 2 diabetes (DM2). Akt kinase (Akt) is an important molecule in insulin signaling, implicated in regulation of glucose uptake, cell growth, cell survival, protein synthesis, and endothelial nitric oxide (NO) production. Impaired Akt activation in insulin-sensitive tissues contributes to IR. However, Akt activity in other tissues, particularly those affected by complications of DM2, has been less studied. We hypothesized that hyperinsulinemia could have an impact on activity of Akt and its effectors involved in regulation of renal morphology and function in DM2. To address this issue, renal cortical Akt was determined in obese Zucker rats (ZO), a model of DM2, and lean controls (ZL). We also studied expression and phosphorylation of the mammalian target of rapamycin (mTOR) and endothelial NO synthase (eNOS), molecules downstream of Akt in the insulin signaling cascade, and documented modulators of renal injury. Akt activity was measured by a kinase assay with GSK-3 as a substrate. Expression of phosphorylated (active) and total proteins was measured by immunoblotting and immunohistochemistry. Renal Akt activity was increased in ZO as compared to ZL rats, in parallel with progressive hyperinsulinemia. No differences in Akt were observed in the skeletal muscle. Corresponding to increases in Akt activity, ZO rats demonstrated enhanced phosphorylation of renal mTOR. Acute PI3K inhibition with wortmannin (100 mug/kg) attenuated renal Akt and mTOR activities in ZO, but not in ZL rats. In contrast to mTOR, eNOS phosphorylation was similar in ZO and ZL rats, despite higher total eNOS expression. In conclusion, ZO rats demonstrated increases in renal Akt and mTOR activity and expression. However, eNOS phosphorylation did not follow this pattern. These data suggest that DM2 is associated with selective IR in the kidney, allowing pro-growth signaling via mTOR, whereas potentially protective effects mediated by eNOS are blunted.
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Affiliation(s)
- Jana Zdychová
- Institute for Clinical and Experimental Medicine, Prague, Czech Republic
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Stentz FB, Kitabchi AE. Transcriptome and proteome expressions involved in insulin resistance in muscle and activated T-lymphocytes of patients with type 2 diabetes. GENOMICS PROTEOMICS & BIOINFORMATICS 2008; 5:216-35. [PMID: 18267303 PMCID: PMC5054231 DOI: 10.1016/s1672-0229(08)60009-1] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We analyzed the genes expressed (transcriptomes) and the proteins translated (pro- teomes) in muscle tissues and activated CD4(+) and CD8(+) T-lymphocytes (T-cells) of five Type 2 diabetes (T2DM) subjects using Affymetrix microarrays and mass spectrometry, and compared them with matched non-diabetic controls. Gene expressions of insulin receptor (INSR), vitamin D receptor, insulin degrading enzyme, Akt, insulin receptor substrate-1 (IRS-1), IRS-2, glucose transporter 4 (GLUT4), and enzymes of the glycolytic pathway were decreased at least 50% in T2DM than in controls. However, there was greater than two-fold gene upregulation of plasma cell glycoprotein-1, tumor necrosis factor alpha (TNFalpha, and gluconeogenic enzymes in T2DM than in controls. The gene silencing for INSR or TNFalpha resulted in the inhibition or stimulation of GLUT4, respectively. Proteome profiles corresponding to molecular weights of the above translated transcriptomes showed different patterns of changes between T2DM and controls. Meanwhile, changes in transcriptomes and proteomes between muscle and activated T-cells of T2DM were comparable. Activated T-cells, analogous to muscle cells, expressed insulin signaling and glucose metabolism genes and gene products. In conclusion, T-cells and muscle in T2DM exhibited differences in expression of certain genes and gene products relative to non-diabetic controls. These alterations in transcriptomes and proteomes in T2DM may be involved in insulin resistance.
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Affiliation(s)
- Frankie B Stentz
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, The University of Tennessee Health Science Center, Memphis, TN 38163, USA.
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