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Abidi M, Khan MS, Ahmad S, Kausar T, Nayeem SM, Islam S, Ali A, Alam K, Moinuddin. Biophysical and biochemical studies on glycoxidatively modified human low density lipoprotein. Arch Biochem Biophys 2018; 645:87-99. [PMID: 29524430 DOI: 10.1016/j.abb.2018.02.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Methylglyoxal (MGO), a reactive dicarbonyl metabolite is a potent arginine directed glycating agent which has implications for diabetes-related complications. Dicarbonyl metabolites are produced endogenously and in a state of misbalance, they contribute to cell and tissue dysfunction through protein and DNA modifications causing dicarbonyl stress. MGO is detoxified by glyoxalase 1 (GLO1) system in the cytoplasm. Reactive oxygen species (ROS) are known to aggravate the glycation process. Both the processes are closely linked, and their combined activity is often referred to as "glycoxidation" process. Glycoxidation of proteins has several consequences such as type 2 diabetes mellitus (T2DM), aging etc. In this study, we have investigated the glycation of low-density lipoprotein (LDL) using different concentrations of MGO for varied incubation time periods. The structural perturbations induced in LDL were analyzed by UV-Vis, fluorescence, circular dichroism spectroscopy, molecular docking studies, polyacrylamide gel electrophoresis, FTIR, thermal denaturation studies, Thioflavin T assay and isothermal titration calorimetry. The ketoamine moieties, carbonyl content and HMF content were quantitated in native and glycated LDL. Simulation studies were also done to see the effect of MGO on the secondary structure of the protein. We report structural perturbations, increased carbonyl content, ketoamine moieties and HMF content in glycated LDL as compared to native analog (native LDL). We report the structural perturbations in LDL upon modification with MGO which could obstruct its normal physiological functions and hence contribute to disease pathogenesis and associated complications.
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Sachdeva R, Schlotterer A, Schumacher D, Matka C, Mathar I, Dietrich N, Medert R, Kriebs U, Lin J, Nawroth P, Birnbaumer L, Fleming T, Hammes HP, Freichel M. TRPC proteins contribute to development of diabetic retinopathy and regulate glyoxalase 1 activity and methylglyoxal accumulation. Mol Metab 2018; 9:156-167. [PMID: 29373286 PMCID: PMC5870093 DOI: 10.1016/j.molmet.2018.01.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 12/18/2017] [Accepted: 01/02/2018] [Indexed: 12/19/2022] Open
Abstract
OBJECTIVE Diabetic retinopathy (DR) is induced by an accumulation of reactive metabolites such as ROS, RNS, and RCS species, which were reported to modulate the activity of cation channels of the TRPC family. In this study, we use Trpc1/4/5/6-/- compound knockout mice to analyze the contribution of these TRPC proteins to diabetic retinopathy. METHODS We used Nanostring- and qPCR-based analysis to determine mRNA levels of TRPC channels in control and diabetic retinae and retinal cell types. Chronic hyperglycemia was induced by Streptozotocin (STZ) treatment. To assess the development of diabetic retinopathy, vasoregression, pericyte loss, and thickness of individual retinal layers were analyzed. Plasma and cellular methylglyoxal (MG) levels, as well as Glyoxalase 1 (GLO1) enzyme activity and protein expression, were measured in WT and Trpc1/4/5/6-/- cells or tissues. MG-evoked toxicity in cells of both genotypes was compared by MTT assay. RESULTS We find that Trpc1/4/5/6-/- mice are protected from hyperglycemia-evoked vasoregression determined by the formation of acellular capillaries and pericyte drop-out. In addition, Trpc1/4/5/6-/- mice are resistant to the STZ-induced reduction in retinal layer thickness. The RCS metabolite methylglyoxal, which represents a key mediator for the development of diabetic retinopathy, was significantly reduced in plasma and red blood cells (RBCs) of STZ-treated Trpc1/4/5/6-/- mice compared to controls. GLO1 is the major MG detoxifying enzyme, and its activity and protein expression were significantly elevated in Trpc1/4/5/6-deficient cells, which led to significantly increased resistance to MG toxicity. GLO1 activity was also increased in retinal extracts from Trpc1/4/5/6-/- mice. The TRPCs investigated here are expressed at different levels in endothelial and glial cells of the retina. CONCLUSION The protective phenotype in diabetic retinopathy observed in Trpc1/4/5/6-/- mice is suggestive of a predominant action of TRPCs in Müller cells and microglia because of their central position in the retention of a proper homoeostasis of the neurovascular unit.
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Affiliation(s)
- Robin Sachdeva
- Institute of Pharmacology, Heidelberg University, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Andrea Schlotterer
- Vth Department of Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Dagmar Schumacher
- Institute of Pharmacology, Heidelberg University, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Christin Matka
- Institute of Pharmacology, Heidelberg University, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Ilka Mathar
- Institute of Pharmacology, Heidelberg University, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Nadine Dietrich
- Vth Department of Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Rebekka Medert
- Institute of Pharmacology, Heidelberg University, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Ulrich Kriebs
- Institute of Pharmacology, Heidelberg University, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Jihong Lin
- Vth Department of Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Peter Nawroth
- Department of Medicine I and Clinical Chemistry, University Hospital Heidelberg, Germany; German Center for Diabetes Research (DZD), Germany; Institute for Diabetes and Cancer IDC Helmholtz Center Munich, Neuherberg, Germany; Joint Heidelberg-IDC Translational Diabetes Program, Dept. of Medicine I, Heidelberg University Hospital, Heidelberg, Germany
| | - Lutz Birnbaumer
- Neurobiology Laboratory, National Institute of Environmental Health Sciences, North Carolina, USA; Institute for Biomedical Research (BIOMED), School of Medical sciences, Catholic University of Argentina, Buenos Aires, Argentina
| | - Thomas Fleming
- Department of Medicine I and Clinical Chemistry, University Hospital Heidelberg, Germany; German Center for Diabetes Research (DZD), Germany
| | - Hans-Peter Hammes
- Vth Department of Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Marc Freichel
- Institute of Pharmacology, Heidelberg University, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany.
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Ahmad S, Uddin M, Habib S, Shahab U, Alam K, Ali A. Autoimmune response to AGE modified human DNA: Implications in type 1 diabetes mellitus. J Clin Transl Endocrinol 2014; 1:66-72. [PMID: 29159085 PMCID: PMC5685016 DOI: 10.1016/j.jcte.2014.05.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2014] [Revised: 04/25/2014] [Accepted: 05/22/2014] [Indexed: 10/26/2022]
Abstract
Aims Non-enzymatic glycation of DNA both in vivo and in vitro results in generation of free radicals, known as glycoxidation. Glycoxidation leads to structural perturbation of DNA resulting in generation of neo-antigenic epitopes having implication in autoimmune disorders like diabetes mellitus. In this study human placental DNA was glycated with methylglyoxal (MG) and lysine (Lys) in the presence of Cu2+ and its auto-antibody binding was probed in Type 1 diabetes patients. Methods Glycation was carried out by incubating DNA with MG, Lys and Cu2+ for 24 h at 37 °C. Carboxyethyl deoxyguanosine (CEdG) formed in glycation reaction was studied by LC-MS and the pathway for Amadori formation was studied by ESI-MS techniques. Furthermore, binding characteristics of auto-antibodies in diabetes patients were assessed by direct binding, competitive ELISA and band shift assay. Results DNA glycation with MG, Lys and Cu2+ results in the formation of CEdG (marker of DNA glycation) which was confirmed by LC-MS. The intermediate stages of glycation were confirmed by ESI-MS technique. Serum from diabetes patients exhibited enhanced binding and specificity for glycated DNA as compared to native form. Conclusions Glycation of DNA has resulted in structural perturbation causing generation of neo-antigenic epitopes thus recognizing auto-antibodies in diabetes.
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Affiliation(s)
- Saheem Ahmad
- Department of Biochemistry, J.N. Medical College, Faculty of Medicine, Aligarh Muslim University, Aligarh, India.,Department of Biosciences/Biochemistry, Integral University, Lucknow, UP, India
| | - Moin Uddin
- Department of Biochemistry, J.N. Medical College, Faculty of Medicine, Aligarh Muslim University, Aligarh, India
| | - Safia Habib
- Biochemistry Section, Women's College, Aligarh Muslim University, Aligarh, India
| | - Uzma Shahab
- Department of Biochemistry, J.N. Medical College, Faculty of Medicine, Aligarh Muslim University, Aligarh, India.,Department of Biochemistry, Central Drug Research Institute, Lucknow, UP, India
| | - Khursheed Alam
- Department of Biochemistry, J.N. Medical College, Faculty of Medicine, Aligarh Muslim University, Aligarh, India
| | - Asif Ali
- Department of Biochemistry, J.N. Medical College, Faculty of Medicine, Aligarh Muslim University, Aligarh, India
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