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Wu HF, Huang CW, Art J, Liu HX, Hart GW, Zeltner N. O-GlcNAcylation is crucial for sympathetic neuron development, maintenance, functionality and contributes to peripheral neuropathy. Front Neurosci 2023; 17:1137847. [PMID: 37229433 PMCID: PMC10203903 DOI: 10.3389/fnins.2023.1137847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 04/12/2023] [Indexed: 05/27/2023] Open
Abstract
O-GlcNAcylation is a post-translational modification (PTM) that regulates a wide range of cellular functions and has been associated with multiple metabolic diseases in various organs. The sympathetic nervous system (SNS) is the efferent portion of the autonomic nervous system that regulates metabolism of almost all organs in the body. How much the development and functionality of the SNS are influenced by O-GlcNAcylation, as well as how such regulation could contribute to sympathetic neuron (symN)-related neuropathy in diseased states, remains unknown. Here, we assessed the level of protein O-GlcNAcylation at various stages of symN development, using a human pluripotent stem cell (hPSC)-based symN differentiation paradigm. We found that pharmacological disruption of O-GlcNAcylation impaired both the growth and survival of hPSC-derived symNs. In the high glucose condition that mimics hyperglycemia, hPSC-derived symNs were hyperactive, and their regenerative capacity was impaired, which resembled typical neuronal defects in patients and animal models of diabetes mellitus. Using this model of sympathetic neuropathy, we discovered that O-GlcNAcylation increased in symNs under high glucose, which lead to hyperactivity. Pharmacological inhibition of O-GlcNAcylation rescued high glucose-induced symN hyperactivity and cell stress. This framework provides the first insight into the roles of O-GlcNAcylation in both healthy and diseased human symNs and may be used as a platform for therapeutic studies.
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Affiliation(s)
- Hsueh-Fu Wu
- Center for Molecular Medicine, University of Georgia, Athens, GA, United States
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, United States
| | - Chia-Wei Huang
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, United States
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA, United States
| | - Jennifer Art
- Center for Molecular Medicine, University of Georgia, Athens, GA, United States
- Biomedical and Translational Sciences Institute, Neuroscience Program, University of Georgia, Athens, GA, United States
| | - Hong-Xiang Liu
- Regenerative Bioscience Center, Department of Animal and Dairy Science, College of Agricultural and Environmental Sciences, University of Georgia, Athens, GA, United States
| | - Gerald W. Hart
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, United States
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA, United States
| | - Nadja Zeltner
- Center for Molecular Medicine, University of Georgia, Athens, GA, United States
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, United States
- Department of Cellular Biology, University of Georgia, Athens, GA, United States
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Jo S, Pritchard S, Wong A, Avula N, Essawy A, Hanover J, Alejandro EU. Pancreatic β-cell hyper-O-GlcNAcylation leads to impaired glucose homeostasis in vivo. Front Endocrinol (Lausanne) 2022; 13:1040014. [PMID: 36387851 PMCID: PMC9644030 DOI: 10.3389/fendo.2022.1040014] [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: 09/08/2022] [Accepted: 10/10/2022] [Indexed: 11/13/2022] Open
Abstract
Protein O-GlcNAcylation is a nutrient and stress-sensitive protein post-translational modification (PTM). The addition of an O-GlcNAc molecule to proteins is catalyzed by O-GlcNAc transferase (OGT), whereas O-GlcNAcase (OGA) enzyme is responsible for removal of this PTM. Previous work showed that OGT is highly expressed in the pancreas, and we demonstrated that hypo-O-GlcNAcylation in β-cells cause severe diabetes in mice. These studies show a direct link between nutrient-sensitive OGT and β-cell health and function. In the current study, we hypothesized that hyper-O-GlcNAcylation may confer protection from β-cell failure in high-fat diet (HFD)-induced obesity. To test this hypothesis, we generated a mouse model with constitutive β-cell OGA ablation (βOGAKO) to specifically increase O-GlcNAcylation in β-cells. Under normal chow diet, young male and female βOGAKO mice exhibited normal glucose tolerance but developed glucose intolerance with aging, relative to littermate controls. No alteration in β-cell mass was observed between βOGAKO and littermate controls. Total insulin content was reduced despite an increase in pro-insulin to insulin ratio in βOGAKO islets. βOGAKO mice showed deficit in insulin secretion in vivo and in vitro. When young animals were subjected to HFD, both male and female βOGAKO mice displayed normal body weight gain and insulin tolerance but developed glucose intolerance that worsened with longer exposure to HFD. Comparable β-cell mass was found between βOGAKO and littermate controls. Taken together, these data demonstrate that the loss of OGA in β-cells reduces β-cell function, thereby perturbing glucose homeostasis. The findings reinforce the rheostat model of intracellular O-GlcNAcylation where too much (OGA loss) or too little (OGT loss) O-GlcNAcylation are both detrimental to the β-cell.
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Affiliation(s)
- Seokwon Jo
- Department of Integrative Biology & Physiology, University of Minnesota Medical School, Minneapolis, MN, United States
| | - Samantha Pritchard
- Department of Integrative Biology & Physiology, University of Minnesota Medical School, Minneapolis, MN, United States
| | - Alicia Wong
- Department of Integrative Biology & Physiology, University of Minnesota Medical School, Minneapolis, MN, United States
- Department of Genetics, Cell Biology & Development, University of Minnesota, Minneapolis, MN, United States
| | - Nandini Avula
- Department of Integrative Biology & Physiology, University of Minnesota Medical School, Minneapolis, MN, United States
| | - Ahmad Essawy
- Department of Integrative Biology & Physiology, University of Minnesota Medical School, Minneapolis, MN, United States
| | - John Hanover
- Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institutes of Health, Bethesda, MD, United States
| | - Emilyn U. Alejandro
- Department of Integrative Biology & Physiology, University of Minnesota Medical School, Minneapolis, MN, United States
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3
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Lee YA, Kim KA, Shin MH. Naegleria fowleri Induces Jurkat T Cell Death via O-deGlcNAcylation. THE KOREAN JOURNAL OF PARASITOLOGY 2021; 59:501-505. [PMID: 34724770 PMCID: PMC8561043 DOI: 10.3347/kjp.2021.59.5.501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 09/17/2021] [Indexed: 11/23/2022]
Abstract
The pathogenic free-living amoeba Naegleria fowleri causes primary amoebic meningoencephalitis, a fatal infection, by penetrating the nasal mucosa and migrating to the brain via the olfactory nerves. N. fowleri can induce host cell death via lytic necrosis. Similar to phosphorylation, O-linked β-N-acetylglucosamine (O-GlcNAc) glycosylation (O-GlcNAcylation) is involved in various cell-signaling processes, including apoptosis and proliferation, with O-GlcNAc addition and removal regulated by O-GlcNAc transferase and O-GlcNAcase (OGA), respectively. However, the detailed mechanism of host cell death induced by N. fowleri is unknown. In this study, we investigated whether N. fowleri can induce the modulation of O-GlcNAcylated proteins during cell death in Jurkat T cells. Co-incubation with live N. fowleri trophozoites increased DNA fragmentation. In addition, incubation with N. fowleri induced a dramatic reduction in O-GlcNAcylated protein levels in 30 min. Moreover, pretreatment of Jurkat T cells with the OGA inhibitor PUGNAc prevented N. fowleri-induced O-deGlcNAcylation and DNA fragmentation. These results suggest that O-deGlcNAcylation is an important signaling process that occurs during Jurkat T cell death induced by N. fowleri.
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Affiliation(s)
- Young Ah Lee
- Department of Environmental Medical Biology, Institute of Tropical Medicine, Yonsei University College of Medicine, Seoul 03722, Korea
| | - Kyeong Ah Kim
- Department of Environmental Medical Biology, Institute of Tropical Medicine, Yonsei University College of Medicine, Seoul 03722, Korea
| | - Myeong Heon Shin
- Department of Environmental Medical Biology, Institute of Tropical Medicine, Yonsei University College of Medicine, Seoul 03722, Korea
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Pancreatic β-Cell O-GlcNAc Transferase Overexpression Increases Susceptibility to Metabolic Stressors in Female Mice. Cells 2021; 10:cells10102801. [PMID: 34685781 PMCID: PMC8534823 DOI: 10.3390/cells10102801] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2021] [Revised: 10/14/2021] [Accepted: 10/14/2021] [Indexed: 01/21/2023] Open
Abstract
The nutrient-sensor O-GlcNAc transferase (Ogt), the sole enzyme that adds an O-GlcNAc-modification onto proteins, plays a critical role for pancreatic β-cell survival and insulin secretion. We hypothesized that β-cell Ogt overexpression would confer protection from β-cell failure in response to metabolic stressors, such as high-fat diet (HFD) and streptozocin (STZ). Here, we generated a β-cell-specific Ogt in overexpressing (βOgtOE) mice, where a significant increase in Ogt protein level and O-GlcNAc-modification of proteins were observed in islets under a normal chow diet. We uncovered that βOgtOE mice show normal peripheral insulin sensitivity and glucose tolerance with a regular chow diet. However, when challenged with an HFD, only female βOgtOE (homozygous) Hz mice developed a mild glucose intolerance, despite increased insulin secretion and normal β-cell mass. While female mice are normally resistant to low-dose STZ treatments, the βOgtOE Hz mice developed hyperglycemia and glucose intolerance post-STZ treatment. Transcriptome analysis between islets with loss or gain of Ogt by RNA sequencing shows common altered pathways involving pro-survival Erk and Akt and inflammatory regulators IL1β and NFkβ. Together, these data show a possible gene dosage effect of Ogt and the importance O-GlcNAc cycling in β-cell survival and function to regulate glucose homeostasis.
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5
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Wang J, Wang X, Ouyang Q, Liu W, Shan J, Tan H, Li X, Chen G. N-Nitrosation Mechanism Catalyzed by Non-heme Iron-Containing Enzyme SznF Involving Intramolecular Oxidative Rearrangement. Inorg Chem 2021; 60:7719-7731. [PMID: 34004115 DOI: 10.1021/acs.inorgchem.1c00057] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The non-heme iron-dependent enzyme SznF catalyzes a critical N-nitrosation step during the N-nitrosourea pharmacophore biosynthesis in streptozotocin. The intramolecular oxidative rearrangement process is known to proceed at the FeII-containing active site in the cupin domain of SznF, but its mechanism has not been elucidated to date. In this study, based on the density functional theory calculations, a unique mechanism was proposed for the N-nitrosation reaction catalyzed by SznF in which a four-electron oxidation process is accomplished through a series of complicated electron transferring between the iron center and substrate to bypass the high-valent FeIV═O species. In the catalytic reaction pathway, the O2 binds to the iron center and attacks on the substrate to form the peroxo bridge intermediate by obtaining two electrons from the substrate exclusively. Then, instead of cleaving the peroxo bridge, the Cε-Nω bond of the substrate is homolytically cleaved first to form a carbocation intermediate, which polarizes the peroxo bridge and promotes its heterolysis. After O-O bond cleavage, the following reaction steps proceed effortlessly so that the N-nitrosation is accomplished without NO exchange among reaction species.
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Affiliation(s)
- Junkai Wang
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Xixi Wang
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Qingwen Ouyang
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Wei Liu
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Jiankai Shan
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Hongwei Tan
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Xichen Li
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Guangju Chen
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
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6
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Morino K, Maegawa H. Role of O-linked N-acetylglucosamine in the homeostasis of metabolic organs, and its potential links with diabetes and its complications. J Diabetes Investig 2021; 12:130-136. [PMID: 32654398 PMCID: PMC7858115 DOI: 10.1111/jdi.13359] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 07/07/2020] [Accepted: 07/09/2020] [Indexed: 12/12/2022] Open
Abstract
Recent studies using genetically manipulated mouse models have shown the pivotal role of O-linked N-acetylglucosamine modification (O-GlcNAcylation) in the metabolism of multiple organs. The molecular mechanism involves the sensing of glucose flux by the hexosamine biosynthesis pathway, which leads to the adjustment of cellular metabolism to protect against changes in the environment of each organ through O-GlcNAcylation. More recently, not only glucose, but also fluxes of amino acids and fatty acids have been reported to induce O-GlcNAcylation, affecting multiple cellular processes. In this review, we discuss how O-GlcNAcylation maintains homeostasis in organs that are affected by diabetes mellitus: skeletal muscle, adipose tissue, liver and pancreatic β-cells. Furthermore, we discuss the importance of O-GlcNAcylation in the pathogenesis of diabetic complications. By elucidating the molecular mechanisms whereby cellular homeostasis is maintained, despite changes in metabolic flux, these studies might provide new targets for the treatment and prevention of diabetes and its complications.
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Affiliation(s)
- Katsutaro Morino
- Division of Diabetology, Endocrinology, and NephrologyDepartment of MedicineShiga University of Medical ScienceOtsuShigaJapan
| | - Hiroshi Maegawa
- Division of Diabetology, Endocrinology, and NephrologyDepartment of MedicineShiga University of Medical ScienceOtsuShigaJapan
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Ma J, Wu C, Hart GW. Analytical and Biochemical Perspectives of Protein O-GlcNAcylation. Chem Rev 2021; 121:1513-1581. [DOI: 10.1021/acs.chemrev.0c00884] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Junfeng Ma
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Georgetown University, Washington D.C. 20057, United States
| | - Ci Wu
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Georgetown University, Washington D.C. 20057, United States
| | - Gerald W. Hart
- Department of Biochemistry and Molecular Biology, Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602, United States
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8
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Jin MH, Shen GN, Jin YH, Sun HN, Zhen X, Zhang YQ, Lee DS, Cui YD, Yu LY, Kim JS, Kwon T, Han YH. Peroxiredoxin I deficiency increases pancreatic β‑cell apoptosis after streptozotocin stimulation via the AKT/GSK3β signaling pathway. Mol Med Rep 2020; 22:1831-1838. [PMID: 32705184 PMCID: PMC7411341 DOI: 10.3892/mmr.2020.11279] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Accepted: 05/28/2020] [Indexed: 01/11/2023] Open
Abstract
Apoptosis of pancreatic β-cells is involved in the pathogenesis of type I and II diabetes. Peroxiredoxin I (Prx I) serves an important role in regulating cellular apoptosis; however, the role of Prx I in pancreatic β-cell apoptosis is not completely understood. In the present study, the role of peroxiredoxin 1 (Prx I) during streptozotocin (STZ)-induced apoptosis of pancreatic β-cells was investigated. The expression level of Prx I was decreased by STZ treatment in a time-dependent manner, and apoptosis of Prx I knockdown MIN6 cells was increased by STZ stimulation, compared with untransduced MIN6 cells. Furthermore, an intraperitoneal injection of STZ increased pancreatic islet damage in Prx I knockout mice, compared with wild-type and Prx II knockout mice. AKT and glycogen synthase kinase (GSK)-3β phosphorylation significantly decreased following Prx I knockdown in MIN6 cells. However, phosphorylated β-catenin and p65 levels significantly increased after STZ stimulation, compared with untransduced cells. The results of the present study indicate that deletion of Prx I mediated STZ-induced pancreatic β-cell death in vivo and in vitro by regulating the AKT/GSK-3β/β-catenin signaling pathway, as well as NF-κB signaling. These findings provide a theoretical basis for treatment of pancreatic damage.
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Affiliation(s)
- Mei-Hua Jin
- Laboratory of Disease Model Research Center, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University, Daqing, Heilongjiang 163319, P.R. China
| | - Gui-Nan Shen
- Laboratory of Disease Model Research Center, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University, Daqing, Heilongjiang 163319, P.R. China
| | - Ying-Hua Jin
- Department of Library and Information Center, Library of Heilongjiang Bayi Agricultural University, Daqing, Heilongjiang 163319, P.R. China
| | - Hu-Nan Sun
- Laboratory of Disease Model Research Center, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University, Daqing, Heilongjiang 163319, P.R. China
| | - Xing Zhen
- Laboratory of Disease Model Research Center, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University, Daqing, Heilongjiang 163319, P.R. China
| | - Yong-Qing Zhang
- Laboratory of Disease Model Research Center, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University, Daqing, Heilongjiang 163319, P.R. China
| | - Dong-Seok Lee
- School of Life Sciences, KUN Creative Bioresearch Group, Kyungpook National University, Daegu, Gyeongsangbuk 702‑701, Republic of Korea
| | - Yu-Dong Cui
- Laboratory of Disease Model Research Center, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University, Daqing, Heilongjiang 163319, P.R. China
| | - Li-Yun Yu
- Laboratory of Disease Model Research Center, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University, Daqing, Heilongjiang 163319, P.R. China
| | - Ji-Su Kim
- Primate Resources Center, Korea Research Institute of Bioscience and Biotechnology, Ibam‑myeon, Jeongeup‑si, Jeonbuk 56216, Republic of Korea
| | - Taeho Kwon
- Primate Resources Center, Korea Research Institute of Bioscience and Biotechnology, Ibam‑myeon, Jeongeup‑si, Jeonbuk 56216, Republic of Korea
| | - Ying-Hao Han
- Laboratory of Disease Model Research Center, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University, Daqing, Heilongjiang 163319, P.R. China
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9
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Elbatrawy AA, Kim EJ, Nam G. O‐GlcNAcase: Emerging Mechanism, Substrate Recognition and Small‐Molecule Inhibitors. ChemMedChem 2020; 15:1244-1257. [DOI: 10.1002/cmdc.202000077] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2020] [Revised: 05/22/2020] [Indexed: 12/11/2022]
Affiliation(s)
- Ahmed A. Elbatrawy
- Center for Neuro-Medicine Brain Science Institute Korea Institutes of Science and Technology Seoul 02792 (Republic of Korea
- Division of Bio-Med KIST school Korea University of Science and Technology (UST) Gajungro 217 Youseong-gu Daejeon (Republic of Korea
| | - Eun Ju Kim
- Daegu University Department of Science Education-Chemistry Gyeongsan-si, Gyeongsangbuk-do Gyeongbuk 38453 (Republic of Korea
| | - Ghilsoo Nam
- Center for Neuro-Medicine Brain Science Institute Korea Institutes of Science and Technology Seoul 02792 (Republic of Korea
- Division of Bio-Med KIST school Korea University of Science and Technology (UST) Gajungro 217 Youseong-gu Daejeon (Republic of Korea
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Pluvinage B, Massel PM, Burak K, Boraston AB. Structural and functional analysis of four family 84 glycoside hydrolases from the opportunistic pathogen Clostridium perfringens. Glycobiology 2020; 30:49-57. [PMID: 31701135 DOI: 10.1093/glycob/cwz069] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 08/29/2019] [Accepted: 08/30/2019] [Indexed: 11/13/2022] Open
Abstract
The opportunistic pathogen Clostridium perfringens possesses the ability to colonize the protective mucin layer in the gastrointestinal tract. To assist this, the C. perfringens genome contains a battery of genes encoding glycoside hydrolases (GHs) that are likely active on mucin glycans, including four genes encoding family 84 GHs: CpGH84A (NagH), CpGH84B (NagI), CpGH84C (NagJ) and CpGH84D (NagK). To probe the potential advantage gained by the expansion of GH84 enzymes in C. perfringens, we undertook the structural and functional characterization of the CpGH84 catalytic modules. Here, we show that these four CpGH84 catalytic modules act as β-N-acetyl-D-glucosaminidases able to hydrolyze N- and O-glycan motifs. CpGH84A and CpGH84D displayed a substrate specificity restricted to terminal β-1,2- and β-1,6-linked N-acetyl-D-glucosamine (GlcNAc). CpGH84B and CpGH84C appear more promiscuous with activity on terminal β-1,2-, β-1,3- and β-1,6-linked GlcNAc; both possess some activity toward β-1,4-linked GlcNAc, but this is dependent upon which monosaccharide it is linked to. Furthermore, all the CpGH84s have different optimum pHs ranging from 5.2 to 7.0. Consistent with their β-N-acetyl-D-glucosaminidase activities, the structures of the four catalytic modules revealed similar folds with a catalytic site including a conserved -1 subsite that binds GlcNAc. However, nonconserved residues in the vicinity of the +1 subsite suggest different accommodation of the sugar preceding the terminal GlcNAc, resulting in subtly different substrate specificities. This structure-function comparison of the four GH84 catalytic modules from C. perfringens reveals their different biochemical properties, which may relate to how they are deployed in the bacterium's niche in the host.
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Affiliation(s)
- Benjamin Pluvinage
- Biochemistry and Microbiology, University of Victoria, PO Box 3055 STN CSC, Victoria, BC V8W 3P6, Canada
| | - Patricia M Massel
- Biochemistry and Microbiology, University of Victoria, PO Box 3055 STN CSC, Victoria, BC V8W 3P6, Canada
| | - Kristyn Burak
- Biochemistry and Microbiology, University of Victoria, PO Box 3055 STN CSC, Victoria, BC V8W 3P6, Canada
| | - Alisdair B Boraston
- Biochemistry and Microbiology, University of Victoria, PO Box 3055 STN CSC, Victoria, BC V8W 3P6, Canada
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Xu D, Wang W, Bian T, Yang W, Shao M, Yang H. Increased expression of O-GlcNAc transferase (OGT) is a biomarker for poor prognosis and allows tumorigenesis and invasion in colon cancer. INTERNATIONAL JOURNAL OF CLINICAL AND EXPERIMENTAL PATHOLOGY 2019; 12:1305-1314. [PMID: 31933944 PMCID: PMC6947042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/27/2019] [Accepted: 02/21/2019] [Indexed: 06/10/2023]
Abstract
Recent studies suggest that Elevated O-GlcNAcylation by increased O-GlcNAc transferase (OGT) and/or decreasing O-GlcNAcase (OGA) levels is associated with cancer initiation, progression, invasion, and metastasis. However, the function of OGT in colon cancer tumorigeneses remains unclear. Here, we showed OGT expression is elevated in human colon cancer tissue compared with adjacent normal tissue, and cases with higher OGT expression had shorter survival time. Additionally, OGT mRNA expression was positively correlated with pathologic TNM stage from TCGA public database. Finally, we found knock-down of OGT expression by RNA interference inhibits cell proliferation, migration and invasion in colon cancer cell lines. Taken together, this study imply that elevated OGT expression had an important function in colon cancer formation and progression, and OGT may be a valuable prognostic factor and therapeutic target.
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Affiliation(s)
- Daogun Xu
- Laboratory of Cellular and Molecular Radiation Oncology, Affiliated Taizhou Hospital of Wenzhou Medical UniversityTaizhou, Zhejiang Province, China
- Department of Colorectal Surgery in Wenling Traditional Chinese Medicine HospitalWenling, Taizhou, Zhejiang Province, China
| | - Wei Wang
- Laboratory of Cellular and Molecular Radiation Oncology, Affiliated Taizhou Hospital of Wenzhou Medical UniversityTaizhou, Zhejiang Province, China
- Department of Radiation Oncology, Affiliated Taizhou Hospital of Wenzhou Medical UniversityTaizhou, Zhejiang Province, China
| | - Tun Bian
- Department of Colorectal Surgery in Wenling Traditional Chinese Medicine HospitalWenling, Taizhou, Zhejiang Province, China
| | - Weifang Yang
- Laboratory of Cellular and Molecular Radiation Oncology, Affiliated Taizhou Hospital of Wenzhou Medical UniversityTaizhou, Zhejiang Province, China
- Department of Radiation Oncology, Affiliated Taizhou Hospital of Wenzhou Medical UniversityTaizhou, Zhejiang Province, China
| | - Minghai Shao
- Laboratory of Cellular and Molecular Radiation Oncology, Affiliated Taizhou Hospital of Wenzhou Medical UniversityTaizhou, Zhejiang Province, China
- Department of Radiation Oncology, Affiliated Taizhou Hospital of Wenzhou Medical UniversityTaizhou, Zhejiang Province, China
| | - Haihua Yang
- Laboratory of Cellular and Molecular Radiation Oncology, Affiliated Taizhou Hospital of Wenzhou Medical UniversityTaizhou, Zhejiang Province, China
- Department of Radiation Oncology, Affiliated Taizhou Hospital of Wenzhou Medical UniversityTaizhou, Zhejiang Province, China
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12
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Kosciow K, Deppenmeier U. Characterization of a phospholipid-regulated β-galactosidase from Akkermansia muciniphila involved in mucin degradation. Microbiologyopen 2019; 8:e00796. [PMID: 30729732 PMCID: PMC6692548 DOI: 10.1002/mbo3.796] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 12/17/2018] [Accepted: 12/18/2018] [Indexed: 12/28/2022] Open
Abstract
The gut microbe Akkermansia muciniphila is important for the human health as the occurrence of the organism is inversely correlated with different metabolic disorders. The metabolism of the organism includes the degradation of intestinal mucins. Thus, the gut health‐promoting properties are not immediately obvious and mechanisms of bacteria‐host interactions are mostly unclear. In this study, we characterized a novel extracellular β‐galactosidase (Amuc_1686) with a preference for linkages from the type Galβ1–3GalNAc. Additionally, Amuc_1686 possesses a discoidin‐like domain, which enables the interaction with anionic phospholipids. We detected a strong inhibition by phosphatidylserine, phosphatidylglycerol, phosphatidic acid, and lysophosphatidic acid while phosphatidylcholine and phosphatidylethanolamine had no influence. Amuc_1686 is the first example of a prokaryotic hydrolase that is strongly inhibited by certain phospholipids. These inhibiting phospholipids have important signal functions in immune response and cell clearance processes. Hence, Amuc_1686 might be regulated based on the health status of the large intestine and could therefore contribute to the mutualistic relationship between the microbe and the host on a molecular level. In this sense, Amuc_1686 could act as an altruistic enzyme that does not attack the mucin layer of apoptotic epithelial cells to ensure tissue regeneration, for example, in areas with inflammatory damages.
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Affiliation(s)
- Konrad Kosciow
- Institute of Microbiology and Biotechnology, University of Bonn, Bonn, Germany
| | - Uwe Deppenmeier
- Institute of Microbiology and Biotechnology, University of Bonn, Bonn, Germany
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Ng TL, Rohac R, Mitchell AJ, Boal AK, Balskus EP. An N-nitrosating metalloenzyme constructs the pharmacophore of streptozotocin. Nature 2019; 566:94-99. [PMID: 30728519 PMCID: PMC6369591 DOI: 10.1038/s41586-019-0894-z] [Citation(s) in RCA: 81] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 12/12/2018] [Indexed: 12/31/2022]
Abstract
Small molecules containing the N-nitroso group, such as the bacterial natural product streptozotocin, are prominent carcinogens1,2 and important cancer chemotherapeutics3,4. Despite the considerable importance of this functional group to human health, enzymes dedicated to the assembly of the N-nitroso unit have not been identified. Here we show that SznF, a metalloenzyme from the biosynthesis of streptozotocin, catalyses an oxidative rearrangement of the guanidine group of Nω-methyl-L-arginine to generate an N-nitrosourea product. Structural characterization and mutagenesis of SznF reveal two separate active sites that promote distinct steps in this transformation using different iron-containing metallocofactors. This biosynthetic reaction, which has little precedent in enzymology or organic synthesis, expands the catalytic capabilities of non-haem-iron-dependent enzymes to include N-N bond formation. We find that biosynthetic gene clusters that encode SznF homologues are widely distributed among bacteria-including environmental organisms, plant symbionts and human pathogens-which suggests an unexpectedly diverse and uncharacterized microbial reservoir of bioactive N-nitroso metabolites.
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Affiliation(s)
- Tai L Ng
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Roman Rohac
- Department of Chemistry, The Pennsylvania State University, University Park, PA, USA
| | - Andrew J Mitchell
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA
| | - Amie K Boal
- Department of Chemistry, The Pennsylvania State University, University Park, PA, USA.
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA.
| | - Emily P Balskus
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA.
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O-deGlcNAcylation is required for Entamoeba histolytica-induced HepG2 cell death. Microb Pathog 2018; 123:285-295. [DOI: 10.1016/j.micpath.2018.07.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 07/12/2018] [Accepted: 07/12/2018] [Indexed: 11/17/2022]
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Lagerlöf O. O-GlcNAc cycling in the developing, adult and geriatric brain. J Bioenerg Biomembr 2018; 50:241-261. [PMID: 29790000 PMCID: PMC5984647 DOI: 10.1007/s10863-018-9760-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 05/07/2018] [Indexed: 12/14/2022]
Abstract
Hundreds of proteins in the nervous system are modified by the monosaccharide O-GlcNAc. A single protein is often O-GlcNAcylated on several amino acids and the modification of a single site can play a crucial role for the function of the protein. Despite its complexity, only two enzymes add and remove O-GlcNAc from proteins, O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA). Global and local regulation of these enzymes make it possible for O-GlcNAc to coordinate multiple cellular functions at the same time as regulating specific pathways independently from each other. If O-GlcNAcylation is disrupted, metabolic disorder or intellectual disability may ensue, depending on what neurons are affected. O-GlcNAc's promise as a clinical target for developing drugs against neurodegenerative diseases has been recognized for many years. Recent literature puts O-GlcNAc in the forefront among mechanisms that can help us better understand how neuronal circuits integrate diverse incoming stimuli such as fluctuations in nutrient supply, metabolic hormones, neuronal activity and cellular stress. Here the functions of O-GlcNAc in the nervous system are reviewed.
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Affiliation(s)
- Olof Lagerlöf
- Department of Neuroscience, Karolinska Institutet, 171 77, Stockholm, Sweden.
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Feyzmand S, Shahbazi B, Marami M, Bahrami G, Fattahi A, Shokoohinia Y. Mechanistic In vitro Evaluation of Prosopis farcta Roots Potential as an Antidiabetic Folk Medicinal Plant. Pharmacogn Mag 2018; 13:S852-S859. [PMID: 29491644 PMCID: PMC5822511 DOI: 10.4103/pm.pm_162_17] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 05/17/2017] [Indexed: 02/02/2023] Open
Abstract
OBJECTIVE Prosopis farcta has been used as a traditional herbal medicine for treating Diabetes mellitus. The aim of this study is to investigate the antidiabetic mechanisms of infusion (INF) extract of P. farcta and discovering the active extract for the first time. MATERIALS AND METHODS Six different extracts of P. farcta were prepared using five different solvents (ethanol, n-hexane, acetone, ethanol:water (1:1 v/v), and water). Cytotoxicity and cell proliferation assays were performed on mouse pancreatic β-cells (β-TC3) using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium method. The effects of P. farcta on glucose metabolism (in a hepatocellular carcinoma cell line [HepG2]) and glucose diffusion across a dialysis membrane (as a model of cellular glucose absorption) were evaluated. The protective effect of various P. farcta extracts on cytotoxicity, mitochondrial membrane potential (MMP), and streptozotocin (STZ)-induced apoptosis in β-TC3 cells was investigated. RESULTS Cytotoxicity study indicated that extracts were safe on β-TC3 and HepG2 (≤0.5 mg/ml). INF protected β-TC3 cells from apoptosis induced by STZ and improved cell viability for 20% and significantly decrease depolarization of MMP (P < 0.005). The results showed that INF inhabited breaking/streaking the DNA. Proliferation study showed no significant increase in the number of cells either at single or multiple doses. In moderate hyperglycemia (11.1 mmol/l), a significant glucose-lowering effect was observed but glucose diffusion was not the probable mechanism of extracts antidiabetic effect. In conclusion, only INF, the traditionally used extract, has an antidiabetic potential by attenuating the death and apoptosis induced by STZ in β-TC3 cells and increase glucose consumption. CONCLUSION The present study demonstrates that only INF extract have an antidiabetic potential by attenuating the death and apoptosis induced by STZ in β-TC3 cells and increase glucose consumption. SUMMARY Six different extracts from P. farcta were prepared using five different solvents [ethanol, n-hexane, acetone, ethanol: water (1:1 v/v), and water]The protective effect of various P. farcta extracts on cytotoxicity, mitochondrial membrane potential (MMP), and Streptozotocin-induced apoptosis in β-TC3 cells were investigated.Infusion has an antidiabetic potential by attenuating the death and apoptosis induced by STZ in β-TC3 cells and increase glucose consumptionThe effect of infusion extract on glucose consumption in hepatocellular carcinoma cell line cells (a) and effect of infusion extract on glucose consumption in hepatocellular carcinoma cell line cells adjusted by optical density MTT (b). Significance was calculated by analysis of variance (*P ≤ 0.05). MTT: 3 (4,5 dimethylthiazol 2 yl) 2,5 diphenyltetrazolium. Abbreviations used: AC: Acetone extract; ANOVA: Analysis of variance; BSA: Bovine serum albumin; β-TC3: Mouse pancreatic β-cells; DMEM: Dulbecco modified Eagle medium; DMSO: Dimethyl sulfoxide; ETH: Ethyl acetate extract; FBS: Fetal bovine serum; HDETH: Hydroethanolic extract; HepG2: Hepatocellular carcinoma cell line; HEX: Hexane extract; INF: Infusion; KUMS: Kermanshah University of Medical Sciences; MMP: Mitochondrial membrane potential; MTT: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium; NaCl: Natrium chloride; OD: Optical density; spp: Species; STZ: Streptozotocin; Tag: T-antigen; USA: United States of America.
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Affiliation(s)
- Saba Feyzmand
- Student Research Committee, School of Pharmacy, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Behzad Shahbazi
- Pharmaceutical Sciences Research Center, School of Pharmacy, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Marzieh Marami
- Pharmaceutical Sciences Research Center, School of Pharmacy, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Gholamreza Bahrami
- Medical Biology Research Center, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Ali Fattahi
- Medical Biology Research Center, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Yalda Shokoohinia
- Pharmaceutical Sciences Research Center, School of Pharmacy, Kermanshah University of Medical Sciences, Kermanshah, Iran
- National Center for Natural Products Research, University of Mississippi, MS, USA
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Vanitha P, Senthilkumar S, Dornadula S, Anandhakumar S, Rajaguru P, Ramkumar KM. Morin activates the Nrf2-ARE pathway and reduces oxidative stress-induced DNA damage in pancreatic beta cells. Eur J Pharmacol 2017; 801:9-18. [DOI: 10.1016/j.ejphar.2017.02.026] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2017] [Revised: 02/09/2017] [Accepted: 02/15/2017] [Indexed: 11/26/2022]
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18
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Abstract
O-GlcNAcylation is the modification of serine and threonine residues with β-N-acetylglucosamine (O-GlcNAc) on intracellular proteins. This dynamic modification is attached by O-GlcNAc transferase (OGT) and removed by O-GlcNAcase (OGA) and is a critical regulator of various cellular processes. Furthermore, O-GlcNAcylation is dysregulated in many diseases, such as diabetes, cancer, and Alzheimer's disease. However, the precise role of this modification and its cycling enzymes (OGT and OGA) in normal and disease states remains elusive. This is partially due to the difficulty in studying O-GlcNAcylation with traditional genetic and biochemical techniques. In this review, we will summarize recent progress in chemical approaches to overcome these obstacles. We will cover new inhibitors of OGT and OGA, advances in metabolic labeling and cellular imaging, synthetic approaches to access homogeneous O-GlcNAcylated proteins, and cross-linking methods to identify O-GlcNAc-protein interactions. We will also discuss remaining gaps in our toolbox for studying O-GlcNAcylation and questions of high interest that are yet to be answered.
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Affiliation(s)
- Matthew Worth
- Department of Chemistry, University of Wisconsin—Madison, Madison, Wisconsin 53705, United States
| | - Hao Li
- Pharmaceutical Sciences Division, School of Pharmacy, University of Wisconsin—Madison, Madison, Wisconsin 53705, United States
| | - Jiaoyang Jiang
- Pharmaceutical Sciences Division, School of Pharmacy, University of Wisconsin—Madison, Madison, Wisconsin 53705, United States
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Wang W, Yan R, Nocek BP, Vuong TV, Di Leo R, Xu X, Cui H, Gatenholm P, Toriz G, Tenkanen M, Savchenko A, Master ER. Biochemical and Structural Characterization of a Five-domain GH115 α-Glucuronidase from the Marine Bacterium Saccharophagus degradans 2-40T. J Biol Chem 2016; 291:14120-14133. [PMID: 27129264 DOI: 10.1074/jbc.m115.702944] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Indexed: 01/01/2023] Open
Abstract
Glucuronic acid (GlcAp) and/or methylglucuronic acid (MeGlcAp) decorate the major forms of xylan in hardwood and coniferous softwoods as well as many cereal grains. Accordingly, the complete utilization of glucuronoxylans or conversion to sugar precursors requires the action of main chain xylanases as well as α-glucuronidases that release the α- (1→2)-linked (Me)GlcAp side groups. Herein, a family GH115 enzymefrom the marine bacterium Saccharophagus degradans 2-40(T), SdeAgu115A, demonstrated activity toward glucuronoxylan and oligomers thereof with preference toward MeGlcAp linked to internal xylopyranosyl residues. Unique biochemical characteristics of NaCl activation were also observed. The crystal structure of SdeAgu115A revealed a five-domain architecture, with an additional insertion C(+) domain that had significant impact on the domain arrangement of SdeAgu115A monomer and its dimerization. The participation of domain C(+) in substrate binding was supported by reduced substrate inhibition upon introducing W773A, W689A, and F696A substitutions within this domain. In addition to Asp-335, the catalytic essentiality of Glu-216 was revealed by site-specific mutagenesis. A primary sequence analysis suggested that the SdeAgu115A architecture is shared by more than half of GH115 members, thus defining a distinct archetype for GH115 enzymes.
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Affiliation(s)
- Weijun Wang
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada
| | - Ruoyu Yan
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada
| | - Boguslaw P Nocek
- Structural Biology Center, Biosciences Division, Argonne National Laboratory, Argonne, Illinois 60439
| | - Thu V Vuong
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada
| | - Rosa Di Leo
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada
| | - Xiaohui Xu
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada
| | - Hong Cui
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada
| | - Paul Gatenholm
- Department of Chemistry and Chemical Engineering, Wallenberg Wood Science Center and Biopolymer Technology, Chalmers University of Technology, Kemivägen 4, Gothenburg 412 96, Sweden
| | - Guillermo Toriz
- Department of Chemistry and Chemical Engineering, Wallenberg Wood Science Center and Biopolymer Technology, Chalmers University of Technology, Kemivägen 4, Gothenburg 412 96, Sweden,; Department of Wood, Cellulose and Paper Research, University of Guadalajara, Guadalajara 44100, Mexico
| | - Maija Tenkanen
- Department of Food and Environmental Sciences, University of Helsinki, P.O. Box 27, Helsinki 00014, Finland
| | - Alexei Savchenko
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada,.
| | - Emma R Master
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada,.
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Design, Synthesis and in Vivo Evaluation of Novel Glycosylated Sulfonylureas as Antihyperglycemic Agents. Molecules 2015; 20:20063-78. [PMID: 26561797 PMCID: PMC6331869 DOI: 10.3390/molecules201119676] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Revised: 10/20/2015] [Accepted: 10/21/2015] [Indexed: 11/29/2022] Open
Abstract
Sulphonylurea compounds have versatile activities such as antidiabetic, diuretic, herbicide, oncolytic, antimalarial, antifungal and anticancer. The present study describes the design, synthesis and in vivo testing of novel glycosylated aryl sulfonylurea compounds as antihyperglycaemic agents in streptozocine-induced diabetic mice. The rational for the introduction of the glucosamine moiety is to enhance selective drug uptake by pancreatic β-cells in order to decrease the cardiotoxic side effect commonly associated with sulfonylurea agents. 2-Deoxy-2-(4-chlorophenylsulfonylurea)-d-glucopyranose was found to be the most potent antihyperglycaemic agents among the synthesized compounds in diabetic mice. This investigation indicates the importance of this novel class as potential antihyperglycaemic agents.
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21
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Saleem Mir M, Maqbool Darzi M, Khalil Baba O, Khan HM, Kamil SA, Sofi AH, Wani SA. Streptozotocin Induced Acute Clinical Effects in Rabbits (Oryctolagus cuniculus). IRANIAN JOURNAL OF PATHOLOGY 2015; 10:206-213. [PMID: 26351486 PMCID: PMC4539772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Accepted: 06/27/2014] [Indexed: 06/05/2023]
Abstract
BACKGROUND & OBJECTIVES Streptozotocin (STZ) is used for induction of Type-1 diabetes mellitus in animal models. Its beta-cytotoxic action results in sudden release of insulin leading to severe hypoglycaemia and even mortality. However, its sensitivity varies with species. Present investigation was aimed at studying STZ induced acute clinical effects in rabbits. METHODS Streptozotocin @ 65 mg/kg b.w. was administered to thirteen New Zealand White rabbits, 1-1.5 kg body weight, as single intravenous dose in 1mL citrate buffer, pH 4.6. Blood glucose levels were recorded before drug administration and then at 20 min, 1h, and hourly up to 9 hours post-treatment followed by intravenous and oral glucose therapy. Clinical signs were noted. RESULTS STZ caused immediate hyperglycaemia up to 4 hours, and then progressively severe hypoglycaemia up to 9 hours. Hypoglycaemia caused characteristic behavioural alterations including lethargy, dullness, sitting quietly but appearing alert, followed by aesthesia and then muscular weakness with characteristic postural changes starting from drooping of head and torticollis, Rabbits recovered following glucose therapy. Marked individual variations in response vis-a-vis onset and severity of glycaemic changes were observed. CONCLUSION STZ induced a characteristic multiphasic immediate response in rabbits similar to one reported in other rodents. Behavioural changes were characteristic of hypoglycaemia warranting early management in order to avoid fatalities.
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Affiliation(s)
- Masood Saleem Mir
- Address Communications to: Dr. Masood Saleem Mir, Associate Professor-cum-Senior Scientist, Division of Veterinary Pathology, F.V.Sc. & A.H, Sher-e-Kashmir University of Agricultural Sciences and Technology of Kashmir, Shuhama, Alusteng-190 006, Kashmir (J&K) India.
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Abstract
Protein O-GlcNAcylation is an abundant, dynamic and reversible type of protein post-translational modification in animals that has been implicated in signalling processes linked to innate immunity, stress response, growth factor response, transcription, translation and proteosomal degradation. Only two enzymes, O-GlcNAc (O-linked N-acetylglucosamine) transferase and O-GlcNAcase, catalyse the reversible addition of the O-GlcNAc residue to over 1000 target proteins in the human cell. Recent advances in our understanding of the structures and mechanisms of these enzymes have resulted in the development of potent and selective inhibitors. The present review gives an overview of these inhibitors and how they have been used on cell lines, primary cells and animals to modulate O-GlcNAc levels and study the effects on signal transduction.
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Lima VV, Rigsby CS, Hardy DM, Webb RC, Tostes RC. O-GlcNAcylation: a novel post-translational mechanism to alter vascular cellular signaling in health and disease: focus on hypertension. ACTA ACUST UNITED AC 2012; 3:374-87. [PMID: 20409980 DOI: 10.1016/j.jash.2009.09.004] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Revised: 09/26/2009] [Accepted: 09/28/2009] [Indexed: 12/21/2022]
Abstract
O-Linked attachment of beta-N-acetyl-glucosamine (O-GlcNAc) on serine and threonine residues of nuclear and cytoplasmic proteins is a highly dynamic posttranslational modification that plays a key role in signal transduction pathways. Preliminary data show that O-GlcNAcylation may represent a key regulatory mechanism in the vasculature, modulating contractile and relaxant responses. Proteins with an important role in vascular function, such as endothelial nitric oxide synthase, sarcoplasmic reticulum Ca(2+)-ATPase, protein kinase C, mitogen-activated protein kinases, and proteins involved in cytoskeleton regulation and microtubule assembly are targets for O-GlcNAcylation, indicating that this posttranslational modification may play an important role in vascular reactivity. Here, we will focus on a few specific pathways that contribute to vascular function and cardiovascular disease-associated vascular dysfunction, and the implications of their modification by O-GlcNAc. New chemical tools have been developed to detect and study O-GlcNAcylation, including inhibitors of O-GlcNAc enzymes, chemoenzymatic tagging methods, and quantitative proteomics strategies; these will also be briefly addressed. An exciting challenge in the future will be to better understand the cellular dynamics of this posttranslational modification, as well as the signaling pathways and mechanisms by which O-GlcNAc is regulated on specific proteins in the vasculature in health and disease.
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Affiliation(s)
- Victor V Lima
- Department of Physiology, Medical College of Georgia, Augusta, GA, USA; Department of Pharmacology, University of Sao Paulo, Sao Paulo, SP, Brazil
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Macauley MS, He Y, Gloster TM, Stubbs KA, Davies GJ, Vocadlo DJ. Inhibition of O-GlcNAcase using a potent and cell-permeable inhibitor does not induce insulin resistance in 3T3-L1 adipocytes. ACTA ACUST UNITED AC 2011; 17:937-48. [PMID: 20851343 PMCID: PMC2954295 DOI: 10.1016/j.chembiol.2010.07.006] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2010] [Revised: 07/08/2010] [Accepted: 07/13/2010] [Indexed: 01/12/2023]
Abstract
To probe increased O-GlcNAc levels as an independent mechanism governing insulin resistance in 3T3-L1 adipocytes, a new class of O-GlcNAcase (OGA) inhibitor was studied. 6-Acetamido-6-deoxy-castanospermine (6-Ac-Cas) is a potent inhibitor of OGA. The structure of 6-Ac-Cas bound in the active site of an OGA homolog reveals structural features contributing to its potency. Treatment of 3T3-L1 adipocytes with 6-Ac-Cas increases O-GlcNAc levels in a dose-dependent manner. These increases in O-GlcNAc levels do not induce insulin resistance functionally, measured using a 2-deoxyglucose (2-DOG) uptake assay, or at the molecular level, determined by evaluating levels of phosphorylated IRS-1 and Akt. These results, and others described, provide a structural blueprint for improved inhibitors and collectively suggest that increased O-GlcNAc levels, brought about by inhibition of OGA, does not by itself cause insulin resistance in 3T3-L1 adipocytes.
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Abstract
Modification of cellular proteins with O-GlcNAc (O-linked N-acetylglucosamine) competes with protein phosphorylation and regulates a plethora of cellular processes. O-GlcNAcylation is orchestrated by two opposing enzymes, O-GlcNAc transferase and OGA (O-GlcNAcase or β-N-acetylglucosaminidase), which recognize their target proteins via as yet unidentified mechanisms. In the present study, we uncovered the first insights into the mechanism of substrate recognition by human OGA. The structure of a novel bacterial OGA orthologue reveals a putative substrate-binding groove, conserved in metazoan OGAs. Guided by this structure, conserved amino acids lining this groove in human OGA were mutated and the activity on three different substrate proteins [TAB1 (transforming growth factor-β-activated protein kinase 1-binding protein 1), FoxO1 (forkhead box O1) and CREB (cAMP-response-element-binding protein)] was tested in an in vitro deglycosylation assay. The results provide the first evidence that human OGA may possess a substrate-recognition mechanism that involves interactions with O-GlcNAcylated proteins beyond the GlcNAc-binding site, with possible implications for differential regulation of cycling of O-GlcNAc on different proteins.
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26
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Issad T, Masson E, Pagesy P. O-GlcNAc modification, insulin signaling and diabetic complications. DIABETES & METABOLISM 2010; 36:423-35. [PMID: 21074472 DOI: 10.1016/j.diabet.2010.09.001] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 06/24/2010] [Revised: 09/16/2010] [Accepted: 09/17/2010] [Indexed: 11/24/2022]
Abstract
O-GlcNAc glycosylation (O-GlcNAcylation) corresponds to the addition of N-acetylglucosamine on serine and threonine residues of cytosolic and nuclear proteins. O-GlcNAcylation is a dynamic post-translational modification, analogous to phosphorylation, that regulates the stability, the activity or the subcellular localisation of target proteins. This reversible modification depends on the availability of glucose and therefore constitutes a powerful mechanism by which cellular activities are regulated according to the nutritional environment of the cell. O-GlcNAcylation has been implicated in important human pathologies including Alzheimer disease and type-2 diabetes. Only two enzymes, OGT and O-GlcNAcase, control the O-GlcNAc level on proteins. Therefore, O-GlcNAcylations cannot organize in signaling cascades as observed for phosphorylations. O-GlcNAcylations should rather be considered as a "rheostat" that controls the intensity of the signals traveling through different pathways according to the nutritional status of the cell. Thus, OGT attenuates insulin signal by O-GlcNAcylation of proteins involved in proximal and distal steps in the PI-3 kinase signaling pathway. This negative feedback may be exacerbated when cells are chronically exposed to elevated glucose concentrations and could thereby contribute to alterations in insulin signaling observed in diabetic patients. O-GlcNAcylation also appears to contribute to the deleterious effects of hyperglycaemia on excessive glucose production by the liver and deterioration of β-cell pancreatic function, resulting in worsening of hyperglycaemia (glucotoxicity). Moreover, O-GlcNAcylations directly participate in several diabetic complications. O-GlcNAcylation of eNOS in endothelial cells have been involved in micro- and macrovascular complications. In addition, O-GlcNAcylations activate the expression of profibrotic and antifibrinolytic factors, contributing to vascular and renal dysfunctions.
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Affiliation(s)
- T Issad
- CNRS (UMR 8104), université Paris Descartes, institut Cochin, 22 rue Méchain, Paris, France.
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He Y, Bubb AK, Stubbs KA, Gloster TM, Davies GJ. Inhibition of a bacterial O-GlcNAcase homologue by lactone and lactam derivatives: structural, kinetic and thermodynamic analyses. Amino Acids 2010; 40:829-39. [PMID: 20689974 DOI: 10.1007/s00726-010-0700-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2010] [Accepted: 07/13/2010] [Indexed: 11/26/2022]
Abstract
The dynamic, intracellular, O-GlcNAc modification is of continuing interest and one whose study through targeted "chemical genetics" approaches is set to increase. Of particular importance is the inhibition of the O-GlcNAc hydrolase, O-GlcNAcase (OGA), since this provides a route to elevate cellular O-GlcNAc levels, and subsequent phenotypic evaluation. Such a small molecule approach complements other methods and potentially avoids changes in protein-protein interactions that manifest themselves in molecular biological approaches to O-GlcNAc transferase knockout or over-expression. Here we describe the kinetic, thermodynamic and three-dimensional structural analysis of a bacterial OGA analogue from Bacteroides thetaiotaomicron, BtGH84, in complex with a lactone oxime (LOGNAc) and a lactam form of N-acetylglucosamine and compare their binding signatures with that of the more potent inhibitor O-(2-acetamido-2-deoxy-D-glucopyranosylidene)amino N-phenyl carbamate (PUGNAc). We show that both LOGNAc and the N-acetyl gluconolactam are significantly poorer inhibitors than PUGNAc, which may reflect poorer mimicry of transition state geometry and steric clashes with the enzyme upon binding; drawbacks that the phenyl carbamate adornment of PUGNAc helps mitigate. Implications for the design of future generations of inhibitors are discussed.
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Affiliation(s)
- Yuan He
- York Structural Biology Laboratory, Department of Chemistry, The University of York, York, UK
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Dorfmueller HC, van Aalten DMF. Screening-based discovery of drug-like O-GlcNAcase inhibitor scaffolds. FEBS Lett 2009; 584:694-700. [PMID: 20026047 PMCID: PMC2828546 DOI: 10.1016/j.febslet.2009.12.020] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2009] [Revised: 12/01/2009] [Accepted: 12/13/2009] [Indexed: 11/26/2022]
Abstract
O-GlcNAcylation is an essential posttranslational modification in metazoa. Modulation of O-GlcNAc levels with small molecule inhibitors of O-GlcNAc hydrolase (OGA) is a useful strategy to probe the role of this modification in a range of cellular processes. Here we report the discovery of novel, low molecular weight and drug-like O-GlcNAcase inhibitor scaffolds by high-throughput screening. Kinetic and X-ray crystallographic analyses of the binding modes with human/bacterial O-GlcNAcases identify some of these as competitive inhibitors. Comparative kinetic experiments with the mechanistically related human lysosomal hexosaminidases reveal that three of the inhibitor scaffolds show selectivity towards human OGA. These scaffolds provide attractive starting points for the development of non-carbohydrate, drug-like OGA inhibitors.
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Affiliation(s)
- Helge C Dorfmueller
- Division of Molecular Microbiology, College of Life Sciences, University of Dundee, Dundee, Scotland, UK
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Macauley MS, Vocadlo DJ. Increasing O-GlcNAc levels: An overview of small-molecule inhibitors of O-GlcNAcase. Biochim Biophys Acta Gen Subj 2009; 1800:107-21. [PMID: 19664691 DOI: 10.1016/j.bbagen.2009.07.028] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2009] [Revised: 07/17/2009] [Accepted: 07/28/2009] [Indexed: 11/25/2022]
Abstract
The O-GlcNAc modification is found on many nucleocytoplasmic proteins. The dynamic nature of O-GlcNAc, which in some ways is reminiscent of phosphorylation, has enabled investigators to modulate the stoichiometry of O-GlcNAc on proteins in order to study its function. Although several genetic and pharmacological methods for manipulating O-GlcNAc levels have been described, one of the most direct approaches of increasing global O-GlcNAc levels is by using small-molecule inhibitors of O-GlcNAcase (OGA). As the interest in increasing O-GlcNAc levels has grown, so too has the number of OGA inhibitors. This review provides an overview of the available methods of increasing O-GlcNAc levels, with a special emphasis on inhibition of OGA by small molecules. Known inhibitors of OGA are discussed with particular attention on those most suitable for cell-based biological studies. Several examples in which OGA inhibitors have been used to study the functional role of the O-GlcNAc modification in biological systems are discussed, highlighting the pros and cons of different inhibitors.
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Affiliation(s)
- Matthew S Macauley
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, Canada
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30
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Hanover JA, Krause MW, Love DC. The hexosamine signaling pathway: O-GlcNAc cycling in feast or famine. Biochim Biophys Acta Gen Subj 2009; 1800:80-95. [PMID: 19647043 DOI: 10.1016/j.bbagen.2009.07.017] [Citation(s) in RCA: 258] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2009] [Revised: 07/10/2009] [Accepted: 07/18/2009] [Indexed: 12/14/2022]
Abstract
The enzymes of O-GlcNAc cycling couple the nutrient-dependent synthesis of UDP-GlcNAc to O-GlcNAc modification of Ser/Thr residues of key nuclear and cytoplasmic targets. This series of reactions culminating in O-GlcNAcylation of targets has been termed the hexosamine signaling pathway (HSP). The evolutionarily ancient enzymes of O-GlcNAc cycling have co-evolved with other signaling effecter molecules; they are recruited to their targets by many of the same mechanisms used to organize canonic kinase-dependent signaling pathways. This co-recruitment of the enzymes of O-GlcNAc cycling drives a binary switch impacting pathways of anabolism and growth (nutrient uptake) and catabolic pathways (nutrient sparing and salvage). The hexosamine signaling pathway (HSP) has thus emerged as a versatile cellular regulator modulating numerous cellular signaling cascades influencing growth, metabolism, cellular stress, circadian rhythm, and host-pathogen interactions. In mammals, the nutrient-sensing HSP has been harnessed to regulate such cell-specific functions as neutrophil migration, and activation of B-cells and T-cells. This review summarizes the diverse approaches being used to examine O-GlcNAc cycling. It will emphasize the impact O-GlcNAcylation has upon signaling pathways that may be become deregulated in diseases of the immune system, diabetes mellitus, cancer, cardiovascular disease, and neurodegenerative diseases.
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Affiliation(s)
- John A Hanover
- Laboratory of Cell Biochemistry and Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA.
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31
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Martinez-Fleites C, He Y, Davies GJ. Structural analyses of enzymes involved in the O-GlcNAc modification. Biochim Biophys Acta Gen Subj 2009; 1800:122-33. [PMID: 19647042 DOI: 10.1016/j.bbagen.2009.07.019] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2009] [Revised: 07/13/2009] [Accepted: 07/18/2009] [Indexed: 12/22/2022]
Abstract
In order to study the O-GlcNAc modification in vivo, it is evident that a range of specific small molecule inhibitors would be a valuable asset. One strategy for the design of such compounds would be to utilise 3-D structural information in tandem with knowledge of catalytic mechanism. The last few years has seen major breakthroughs in our understanding of the 3-D structure of the enzymes involved in the O-GlcNAc modification notably from the study of the tetratricopeptide repeat (TPR) domain of the human O-GlcNAc transferase, of the bacterial homologs of the O-GlcNAc hydrolase and more latterly bacterial homologs of the O-GlcNAc transferase itself. Of particular note are the bacterial O-GlcNAc hydrolase homologs that provide near identical active centres to the human enzyme. These have informed the design and/or subsequent analysis of inhibitors of this enzyme which have found great use in the chemical dissection of the O-GlcNAc in vivo, as described by Macauley and Vocadlo elsewhere in this issue.
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Affiliation(s)
- Carlos Martinez-Fleites
- York Structural Biology Laboratory, Department of Chemistry, The University of York, Heslington, York, YO10 5YW, UK
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GlcNAcstatins are nanomolar inhibitors of human O-GlcNAcase inducing cellular hyper-O-GlcNAcylation. Biochem J 2009; 420:221-7. [PMID: 19275764 PMCID: PMC2691177 DOI: 10.1042/bj20090110] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
O-GlcNAcylation is an essential, dynamic and inducible post-translational glycosylation of cytosolic proteins in metazoa and can show interplay with protein phosphorylation. Inhibition of OGA (O-GlcNAcase), the enzyme that removes O-GlcNAc from O-GlcNAcylated proteins, is a useful strategy to probe the role of this modification in a range of cellular processes. In the present study, we report the rational design and evaluation of GlcNAcstatins, a family of potent, competitive and selective inhibitors of human OGA. Kinetic experiments with recombinant human OGA reveal that the GlcNAcstatins are the most potent human OGA inhibitors reported to date, inhibiting the enzyme in the sub-nanomolar to nanomolar range. Modification of the GlcNAcstatin N-acetyl group leads to up to 160-fold selectivity against the human lysosomal hexosaminidases which employ a similar substrate-assisted catalytic mechanism. Mutagenesis studies in a bacterial OGA, guided by the structure of a GlcNAcstatin complex, provides insight into the role of conserved residues in the human OGA active site. GlcNAcstatins are cell-permeant and, at low nanomolar concentrations, effectively modulate intracellular O-GlcNAc levels through inhibition of OGA, in a range of human cell lines. Thus these compounds are potent selective tools to study the cell biology of O-GlcNAc.
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Yuan WP, Liu B, Liu CH, Wang XJ, Zhang MS, Meng XM, Xia XK. Antioxidant activity of chito-oligosaccharides on pancreatic islet cells in streptozotocin-induced diabetes in rats. World J Gastroenterol 2009; 15:1339-45. [PMID: 19294763 PMCID: PMC2658843 DOI: 10.3748/wjg.15.1339] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate the antioxidant activity of chito-oligosaccharides (COSs) on pancreatic islet cells in diabetic rats induced by streptozotocin.
METHODS: The antioxidant effect of COSs on pancreatic islet cells was detected under optical microscopy and with colorimetric assay and gel electrophoresis. The activities of glutathione peroxidase and superoxide dismutase, total antioxidant capacity, and content of malondialdehyde in serum and tissue slices of pancreas were examined after 60 d to determine the effect of COSs in streptozotocin-induced diabetes in rats.
RESULTS: COSs can prohibit the apoptosis of pancreatic islet cells. All concentrations of COSs can improve the capability of total antioxidant capacity and activity of superoxide dismutase and decrease the content of malondialdehyde drastically. Morphological investigation in the pancreas showed that COSs have resulted in the reduction of islets, loss of pancreatic cells, and nuclear pyknosis of pancreatic cells.
CONCLUSION: COSs possess various biological activities and can be used in the treatment of diabetes mellitus.
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He Y, Martinez-Fleites C, Bubb A, Gloster TM, Davies GJ. Structural insight into the mechanism of streptozotocin inhibition of O-GlcNAcase. Carbohydr Res 2008; 344:627-31. [PMID: 19217614 DOI: 10.1016/j.carres.2008.12.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2008] [Revised: 12/02/2008] [Accepted: 12/03/2008] [Indexed: 10/21/2022]
Abstract
Despite decades of its use in diabetes research, the mechanism of cytotoxicity of streptozotocin (STZ) toward pancreatic beta-islet cells has remained a topic of discussion. Although STZ toxicity is likely a function of its capacity to promote DNA alkylation, it has been proposed that STZ induces pancreatic beta-cell death through O-GlcNAcase inhibition. In this report, we explore the binding mode of STZ to a close homolog of human O-GlcNAcase, BtGH84 from Bacteroides thetaiotaomicron. Our results show that STZ binds in the enzyme active site in its intact form, without the formation of a covalent adduct, consistent with solution studies on BtGH84 and human O-GlcNAcase, as well as with structural work on a homolog from Clostridium perfringens. The active site of the BtGH84 is considerably deformed upon STZ binding and as a result the catalytic machinery is expelled from the binding cavity.
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Affiliation(s)
- Yuan He
- Department of Chemistry, Structural Biology Laboratory, The University of York, Heslington, York, YO10 5YW, UK
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Hurtado-Guerrero R, Dorfmueller HC, van Aalten DMF. Molecular mechanisms of O-GlcNAcylation. Curr Opin Struct Biol 2008; 18:551-7. [DOI: 10.1016/j.sbi.2008.09.005] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2008] [Revised: 09/08/2008] [Accepted: 09/15/2008] [Indexed: 11/29/2022]
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