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Shi JJ, Liu HF, Hu T, Gao X, Zhang YB, Li WR, Wang Q, Zhang SJ, Tang D, Chen YB. Danggui-Shaoyao-San improves cognitive impairment through inhibiting O-GlcNAc-modification of estrogen α receptor in female db/db mice. JOURNAL OF ETHNOPHARMACOLOGY 2021; 281:114562. [PMID: 34438027 DOI: 10.1016/j.jep.2021.114562] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 07/29/2021] [Accepted: 08/22/2021] [Indexed: 06/13/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE The traditional Chinese medicine formula Danggui-Shaoyao-San (DSS) has been reported to show therapeutic effect on dementia. AIM OF THE STUDY The present study aims to investigate whether DSS treatment could alleviate diabetes-induced cognitive dysfunction, and explores its neuroprotective mechanism on db/db mice. MATERIALS AND METHODS The female db/db mice were randomly divided into model group, DSS low-dose group and DSS high-dose group. Homologous female db/m mice were used as the control group. DSS was intragastric administrated for 15 weeks. Glucose tolerance, insulin tolerance, blood glucose and blood lipid levels were measured. Morris water maze was used to measure spatial learning and memory ability in mice. Nissl staining and Tunel staining were used to measure the changes of brain neurons, and ELISA kits were used to measure levels of inflammatory mediators (PGE2, TXB2 and LTB4). The kits detected oxidative stress (MDA, SOD, CAT, GSH-PX), nitrosative stress (NO, iNOS, TNOS) and glucose metabolism (LDH, PK, HK) levels. Western blot and immunofluorescence detected neurotrophic factors (PSD95, BDNF, NGF and SYN), apoptosis (Bcl-2, Bax, Bcl-xl, Caspase-3) and changes of ERα, O-GlcNAc, OGT, OGA levels. RESULTS Morris water maze results showed that DSS could improve the learning and memory abilities of female db/db mice. Nissl staining showed that DSS could relieve hippocampal neurons damage of db/db mice. In addition, the serological tests showed that DSS could improve the impaired glucose tolerance and insulin resistance, while reduce hyperlipemia in db/db mice. Besides, DSS treatment increased the activities of SOD, GSH-PX, and CAT, and reduced MDA, NO, iNOs, tNOS, PGE2, TXB2 and LTB4 levels. Western blot and immunofluorescence results of PSD95, BDNF, NGF, and SYN showed that DSS could improve the expressions of neurotrophic factors. Meanwhile, Tunel staning and Western blot (Bcl-2, Bax, Bcl-xl, Caspase-3) results indicated that DSS could reduce neuronal apoptosis. Finally, Western blot (ERα, O-GlcNAc, OGA, and OGT) and immunofluorescence (ERα and O-GlcNAc) results indicated that DSS could increase the levels of ERα and OGA, decrease the levels of O-GlcNAc and OGT. CONCLUSION DSS alleviate DE might be related to improve the abnormal O-GlcNAc-modification of ERα.
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Affiliation(s)
- Jing-Jing Shi
- Science and Technology Innovation Center, Guangzhou University of Chinese Medicine, Guangzhou, China; Institute of Clinical Pharmacology, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Hao-Fei Liu
- Science and Technology Innovation Center, Guangzhou University of Chinese Medicine, Guangzhou, China; Institute of Clinical Pharmacology, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Tian Hu
- Science and Technology Innovation Center, Guangzhou University of Chinese Medicine, Guangzhou, China; Institute of Clinical Pharmacology, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Xin Gao
- Laboratory of Experimental Animal, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Yong-Bin Zhang
- Laboratory of Experimental Animal, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Wei-Rong Li
- Science and Technology Innovation Center, Guangzhou University of Chinese Medicine, Guangzhou, China; Institute of Clinical Pharmacology, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Qi Wang
- Science and Technology Innovation Center, Guangzhou University of Chinese Medicine, Guangzhou, China; Institute of Clinical Pharmacology, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Shi-Jie Zhang
- Department of Neurology, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China; Department of Neurology, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, China; Postdoctoral Research Station of Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, China.
| | - Dan Tang
- Key Laboratory of Digital Quality Evaluation of Chinese Materia Medica of State Administration of TCM and Engineering & Technology Research Center for Chinese Materia Medica Quality of Guangdong Province, Guangdong Pharmaceutical University, Guangzhou, China.
| | - Yun-Bo Chen
- Science and Technology Innovation Center, Guangzhou University of Chinese Medicine, Guangzhou, China; Institute of Clinical Pharmacology, Guangzhou University of Chinese Medicine, Guangzhou, China.
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Mueller T, Ouyang X, Johnson MS, Qian WJ, Chatham JC, Darley-Usmar V, Zhang J. New Insights Into the Biology of Protein O-GlcNAcylation: Approaches and Observations. FRONTIERS IN AGING 2021; 1:620382. [PMID: 35822169 PMCID: PMC9261361 DOI: 10.3389/fragi.2020.620382] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 12/11/2020] [Indexed: 12/13/2022]
Abstract
O-GlcNAcylation is a protein posttranslational modification that results in the addition of O-GlcNAc to Ser/Thr residues. Since its discovery in the 1980s, it has been shown to play an important role in a broad range of cellular functions by modifying nuclear, cytosolic, and mitochondrial proteins. The addition of O-GlcNAc is catalyzed by O-GlcNAc transferase (OGT), and its removal is catalyzed by O-GlcNAcase (OGA). Levels of protein O-GlcNAcylation change in response to nutrient availability and metabolic, oxidative, and proteotoxic stress. OGT and OGA levels, activity, and target engagement are also regulated. Together, this results in adaptive and, on occasions, detrimental responses that affect cellular function and survival, which impact a broad range of pathologies and aging. Over the past several decades, approaches and tools to aid the investigation of the regulation and consequences of protein O-GlcNAcylation have been developed and enhanced. This review is divided into two sections: 1) We will first focus on current standard and advanced technical approaches for assessing enzymatic activities of OGT and OGT, assessing the global and specific protein O-GlcNAcylation and 2) we will summarize in vivo findings of functional consequences of changing protein O-GlcNAcylation, using genetic and pharmacological approaches.
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Affiliation(s)
- Toni Mueller
- Department of Pathology and Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Xiaosen Ouyang
- Department of Pathology and Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Michelle S. Johnson
- Department of Pathology and Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Wei-Jun Qian
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, United States
| | - John C. Chatham
- Department of Pathology and Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Victor Darley-Usmar
- Department of Pathology and Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Jianhua Zhang
- Department of Pathology and Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL, United States
- *Correspondence: Jianhua Zhang,
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Shin EM, Huynh VT, Neja SA, Liu CY, Raju A, Tan K, Tan NS, Gunaratne J, Bi X, Iyer LM, Aravind L, Tergaonkar V. GREB1: An evolutionarily conserved protein with a glycosyltransferase domain links ERα glycosylation and stability to cancer. SCIENCE ADVANCES 2021; 7:7/12/eabe2470. [PMID: 33731348 PMCID: PMC7968844 DOI: 10.1126/sciadv.abe2470] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Accepted: 01/29/2021] [Indexed: 05/03/2023]
Abstract
What covalent modifications control the temporal ubiquitination of ERα and hence the duration of its transcriptional activity remain poorly understood. We show that GREB1, an ERα-inducible enzyme, catalyzes O-GlcNAcylation of ERα at residues T553/S554, which stabilizes ERα protein by inhibiting association with the ubiquitin ligase ZNF598. Loss of GREB1-mediated glycosylation of ERα results in reduced cellular ERα levels and insensitivity to estrogen. Higher GREB1 expression in ERα+ve breast cancer is associated with greater survival in response to tamoxifen, an ERα agonist. Mice lacking Greb1 exhibit growth and fertility defects reminiscent of phenotypes in ERα-null mice. In summary, this study identifies GREB1, a protein with an evolutionarily conserved domain related to DNA-modifying glycosyltransferases of bacteriophages and kinetoplastids, as the first inducible and the only other (apart from OGT) O-GlcNAc glycosyltransferase in mammalian cytoplasm and ERα as its first substrate.
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Affiliation(s)
- Eun Myoung Shin
- Laboratory of NFκB Signalling, Institute of Molecular and Cell Biology (IMCB), A*STAR (Agency for Science, Technology and Research, Singapore 138673, Singapore
| | - Vinh Thang Huynh
- Laboratory of NFκB Signalling, Institute of Molecular and Cell Biology (IMCB), A*STAR (Agency for Science, Technology and Research, Singapore 138673, Singapore
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Sultan Abda Neja
- Laboratory of NFκB Signalling, Institute of Molecular and Cell Biology (IMCB), A*STAR (Agency for Science, Technology and Research, Singapore 138673, Singapore
| | - Chia Yi Liu
- Bioprocessing Technology Institute (BTI), A*STAR, Singapore, Singapore
| | - Anandhkumar Raju
- Laboratory of NFκB Signalling, Institute of Molecular and Cell Biology (IMCB), A*STAR (Agency for Science, Technology and Research, Singapore 138673, Singapore
| | - Kelly Tan
- Bioprocessing Technology Institute (BTI), A*STAR, Singapore, Singapore
| | - Nguan Soon Tan
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
- School of Biological Sciences, Nanyang Technological University Singapore, 60 Nanyang Drive,, Singapore 637551, Singapore
| | - Jayantha Gunaratne
- Laboratory of NFκB Signalling, Institute of Molecular and Cell Biology (IMCB), A*STAR (Agency for Science, Technology and Research, Singapore 138673, Singapore
- Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore (NUS), Singapore 117594, Singapore
| | - Xuezhi Bi
- Bioprocessing Technology Institute (BTI), A*STAR, Singapore, Singapore
- Duke-NUS Medical School, Singapore 169857, Singapore
| | - Lakshminarayan M Iyer
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - L Aravind
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - Vinay Tergaonkar
- Laboratory of NFκB Signalling, Institute of Molecular and Cell Biology (IMCB), A*STAR (Agency for Science, Technology and Research, Singapore 138673, Singapore.
- Department of Pathology, Yong Loo Lin School of Medicine, National University of Singapore (NUS), Singapore 117597, Singapore
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Dela Justina V, Priviero F, Dos Passos RR, Webb RC, Lima VV, Giachini FR. O-GlcNAc impairs endothelial function in uterine arteries from virgin but not pregnant rats: The role of GSK3β. Eur J Pharmacol 2020; 880:173133. [PMID: 32343970 DOI: 10.1016/j.ejphar.2020.173133] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 04/18/2020] [Accepted: 04/20/2020] [Indexed: 01/10/2023]
Abstract
Increased O-Linked β-N-acetylglucosamine (O-GlcNAc) is observed in several pathologies, and unbalanced O-GlcNAcylation levels favor endothelial dysfunction. Whether augmented O-GlcNAc impacts the uterine artery (UA) function and how it affects the UA during pregnancy remains to be elucidated. We hypothesized that glucosamine treatment increases O-GlcNAc, leading to uterine artery dysfunction and this effect is prevented by pregnancy. Pregnant (P) and non-pregnant (NP) Wistar rats were treated with glucosamine (300 mg/kg; i.p.) for 21 days. Concentration response-curves (CRC) to acetylcholine (in the presence or absence of L-NAME) and sodium nitroprusside were performed in UAs. In NP rats, glucosamine treatment increased O-GlcNAc expression in UAs accompanied by decreased endothelium-dependent relaxation, which was abolished by L-NAME. Endothelial nitric oxide synthase (eNOS) activity and total Akt expression were decreased by glucosamine-treatment in NP rats. Further, NP rats treated with glucosamine displayed increased glycogen synthase kinase 3 beta (GSK3β) activation and O-GlcNAc-transferase (OGT) expression in the UA. P rats treated with glucosamine displayed decreased O-GlcNAc in UAs and it was accompanied by improved relaxation to acetylcholine, whereas eNOS and GSK3β activity and total Akt and OGT expression were unchanged. Sodium nitroprusside-induced relaxation was not changed in all groups, indicating that glucosamine treatment led to endothelial dysfunction in NP rats. The underlying mechanism is, at least in part, dependent on Akt/GSK3β/OGT modulation. We speculate that during pregnancy, hormonal alterations play a protective role in preventing O-GlcNAcylation-induced endothelial dysfunction in the UAs.
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Affiliation(s)
- Vanessa Dela Justina
- Graduate Program in Biological Sciences, Federal University of Goiás, Goiânia, GO, Brazil
| | | | - Rinaldo Rodrigues Dos Passos
- Graduate Program in Biological Sciences, Federal University of Goiás, Goiânia, GO, Brazil; Institute of Biological Sciences and Health, Federal University of Mato Grosso, Barra do Garças, MT, Brazil
| | - R Clinton Webb
- Department of Physiology, Augusta University, Augusta, GA, USA
| | - Victor Vitorino Lima
- Institute of Biological Sciences and Health, Federal University of Mato Grosso, Barra do Garças, MT, Brazil
| | - Fernanda R Giachini
- Graduate Program in Biological Sciences, Federal University of Goiás, Goiânia, GO, Brazil; Institute of Biological Sciences and Health, Federal University of Mato Grosso, Barra do Garças, MT, Brazil.
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Singh JP, Qian K, Lee JS, Zhou J, Han X, Zhang B, Ong Q, Ni W, Jiang M, Ruan HB, Li MD, Zhang K, Ding Z, Lee P, Singh K, Wu J, Herzog RI, Kaech S, Wendel HG, Yates JR, Han W, Sherwin RS, Nie Y, Yang X. O-GlcNAcase targets pyruvate kinase M2 to regulate tumor growth. Oncogene 2020; 39:560-573. [PMID: 31501520 PMCID: PMC7107572 DOI: 10.1038/s41388-019-0975-3] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2017] [Revised: 05/12/2019] [Accepted: 06/18/2019] [Indexed: 01/24/2023]
Abstract
Cancer cells are known to adopt aerobic glycolysis in order to fuel tumor growth, but the molecular basis of this metabolic shift remains largely undefined. O-GlcNAcase (OGA) is an enzyme harboring O-linked β-N-acetylglucosamine (O-GlcNAc) hydrolase and cryptic lysine acetyltransferase activities. Here, we report that OGA is upregulated in a wide range of human cancers and drives aerobic glycolysis and tumor growth by inhibiting pyruvate kinase M2 (PKM2). PKM2 is dynamically O-GlcNAcylated in response to changes in glucose availability. Under high glucose conditions, PKM2 is a target of OGA-associated acetyltransferase activity, which facilitates O-GlcNAcylation of PKM2 by O-GlcNAc transferase (OGT). O-GlcNAcylation inhibits PKM2 catalytic activity and thereby promotes aerobic glycolysis and tumor growth. These studies define a causative role for OGA in tumor progression and reveal PKM2 O-GlcNAcylation as a metabolic rheostat that mediates exquisite control of aerobic glycolysis.
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Affiliation(s)
- Jay Prakash Singh
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06519, USA
- Department of Comparative Medicine, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06519, USA
| | - Kevin Qian
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06519, USA
- Department of Comparative Medicine, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06519, USA
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06519, USA
| | - Jeong-Sang Lee
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06519, USA
- Department of Comparative Medicine, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06519, USA
| | - Jinfeng Zhou
- State Key Laboratory of Cancer Biology, Xijing Hospital of Digestive Diseases, Fourth Military Medical University, 127 West Changle Road, Xi'an, 710032, Shaanxi, China
| | - Xuemei Han
- Department of Chemical Physiology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Bichen Zhang
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06519, USA
- Department of Comparative Medicine, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06519, USA
| | - Qunxiang Ong
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06519, USA
- Department of Comparative Medicine, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06519, USA
- Singapore Bioimaging Consortium, Singapore, Singapore
| | - Weiming Ni
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06519, USA
- Department of Comparative Medicine, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06519, USA
| | - Mingzuo Jiang
- State Key Laboratory of Cancer Biology, Xijing Hospital of Digestive Diseases, Fourth Military Medical University, 127 West Changle Road, Xi'an, 710032, Shaanxi, China
| | - Hai-Bin Ruan
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06519, USA
- Department of Comparative Medicine, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06519, USA
| | - Min-Dian Li
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06519, USA
- Department of Comparative Medicine, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06519, USA
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06519, USA
| | - Kaisi Zhang
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06519, USA
- Department of Comparative Medicine, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06519, USA
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06519, USA
| | - Zhaobing Ding
- Singapore Bioimaging Consortium, Singapore, Singapore
| | - Philip Lee
- Singapore Bioimaging Consortium, Singapore, Singapore
| | - Kamini Singh
- Cancer Biology and Genetics Program, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - Jing Wu
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06519, USA
- Department of Comparative Medicine, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06519, USA
- School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, 710049, Shaanxi, China
| | - Raimund I Herzog
- Department of Medicine, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06519, USA
| | - Susan Kaech
- Department of Immunobiology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06519, USA
| | - Hans-Guido Wendel
- Cancer Biology and Genetics Program, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - John R Yates
- Department of Chemical Physiology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Weiping Han
- Singapore Bioimaging Consortium, Singapore, Singapore
| | - Robert S Sherwin
- Department of Medicine, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06519, USA
| | - Yongzhan Nie
- State Key Laboratory of Cancer Biology, Xijing Hospital of Digestive Diseases, Fourth Military Medical University, 127 West Changle Road, Xi'an, 710032, Shaanxi, China
| | - Xiaoyong Yang
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06519, USA.
- Department of Comparative Medicine, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06519, USA.
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06519, USA.
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Nagy T, Kátai E, Fisi V, Takács TT, Stréda A, Wittmann I, Miseta A. Protein O-GlcNAc Modification Increases in White Blood Cells After a Single Bout of Physical Exercise. Front Immunol 2018; 9:970. [PMID: 29774032 PMCID: PMC5943509 DOI: 10.3389/fimmu.2018.00970] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 04/18/2018] [Indexed: 01/24/2023] Open
Abstract
Background Protein O-linked N-acetylglucosamine (O-GlcNAc) is a dynamic posttranslational modification influencing the function of many intracellular proteins. Recently it was revealed that O-GlcNAc regulation is modified under various stress states, including ischemia and oxidative stress. Aside from a few contradictory studies based on animal models, the effect of exercise on O-GlcNAc is unexplored. Purpose To evaluate O-GlcNAc levels in white blood cells (WBC) of human volunteers following physical exercise. Methods Young (age 30 ± 5.2), healthy male volunteers (n = 6) were enlisted for the study. Blood parameters including metabolites, ions, “necro”-enzymes, and cell counts were measured before and after a single bout of exercise (2-mile run). From WBC samples, we performed western blots to detect O-GlcNAc modified proteins. The distribution of O-GlcNAc in WBC subpopulations was assessed by flow cytometry. Results Elevation of serum lactic acid (increased from 1.3 ± 0.4 to 6.9 ± 1.7 mM), creatinine (from 77.5 ± 6.3 U/L to 102.2 ± 7.0 μM), and lactate dehydrogenase (from 318.5 ± 26.2 to 380.5 ± 33.2 U/L) confirmed the effect of exercise. WBC count also significantly increased (from 6.6 ± 1.0 to 8.4 ± 1.4 G/L). The level of O-GlcNAc modified proteins in WBCs showed significant elevation after exercise (85 ± 51%, p < 0.05). Flow cytometry revealed that most of this change could be attributed to lymphocytes and monocytes. Conclusion Our results indicate that short-term exercise impacts the O-GlcNAc status of WBCs. O-GlcNAc modification could be a natural process by which physical activity modulates the immune system. Further research could elucidate the role of O-GlcNAc during exercise and validate O-GlcNAc as a biomarker for fitness assessment.
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Affiliation(s)
- Tamás Nagy
- Department of Laboratory Medicine, Medical School, University of Pécs, Pécs, Hungary.,János Szentágothai Research Centre, University of Pécs, Pécs, Hungary
| | - Emese Kátai
- Department of Laboratory Medicine, Medical School, University of Pécs, Pécs, Hungary
| | - Viktória Fisi
- Department of Laboratory Medicine, Medical School, University of Pécs, Pécs, Hungary
| | - Tamás Tibor Takács
- Department of Laboratory Medicine, Medical School, University of Pécs, Pécs, Hungary
| | - Antal Stréda
- Department of Internal Medicine and Nephrology Center, Medical School, University of Pécs, Pécs, Hungary
| | - István Wittmann
- Department of Internal Medicine and Nephrology Center, Medical School, University of Pécs, Pécs, Hungary
| | - Attila Miseta
- Department of Laboratory Medicine, Medical School, University of Pécs, Pécs, Hungary
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7
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Trinca GM, Hagan CR. O-GlcNAcylation in women's cancers: breast, endometrial and ovarian. J Bioenerg Biomembr 2017; 50:199-204. [PMID: 29127647 DOI: 10.1007/s10863-017-9730-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 10/24/2017] [Indexed: 12/15/2022]
Abstract
O-GlcNAcylation is emerging as a critical regulatory post-translational modification, impacting proteins that regulate cell division, apoptosis, metabolism, cell signaling, and transcription. O-GlcNAc also affects biological homeostasis by integrating information coming from the environment, such as nutrient conditions and extracellular stimuli, with cellular response. Aberrant O-GlcNAc modulation has been linked to metabolic and neurodegenerative diseases, as well as cancers. While many studies have highlighted the significance of O-GlcNAc in cancer, a specific function for O-GlcNAc during tumorigenesis remains unclear and seems to differ according to cancer type. Herein, we review the impact of altered O-GlcNAcylation in breast, ovarian and uterine cancers.
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Affiliation(s)
- Gloria M Trinca
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, 3901 Rainbow Blvd, Kansas City, KS, 66160, USA
| | - Christy R Hagan
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, 3901 Rainbow Blvd, Kansas City, KS, 66160, USA.
- Department of Cancer Biology, University of Kansas Cancer Center, University of Kansas Medical Center, Kansas City, KS, 66160, USA.
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8
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Trinca GM, Goodman ML, Papachristou EK, D'Santos CS, Chalise P, Madan R, Slawson C, Hagan CR. O-GlcNAc-Dependent Regulation of Progesterone Receptor Function in Breast Cancer. Discov Oncol 2017; 9:12-21. [PMID: 28929346 DOI: 10.1007/s12672-017-0310-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 09/11/2017] [Indexed: 02/06/2023] Open
Abstract
Emerging clinical trial data implicate progestins in the development of breast cancer. While the role for the progesterone receptor (PR) in this process remains controversial, it is clear that PR, a steroid-activated nuclear receptor, alters the transcriptional landscape of breast cancer. PR interacts with many different types of proteins, including transcriptional co-activators and co-repressors, transcription factors, nuclear receptors, and proteins that post-translationally modify PR (i.e., kinases and phosphatases). Herein, we identify a novel interaction between PR and O-GlcNAc transferase (OGT), the enzyme that catalyzes the addition of a single N-acetylglucosamine sugar, referred to as O-GlcNAc, to acceptor serines and threonines in target proteins. This interaction between PR and OGT leads to the post-translational modification of PR by O-GlcNAc. Moreover, we show that O-GlcNAcylated PR is more transcriptionally active on PR-target genes, despite the observation that PR messenger RNA and protein levels are decreased when O-GlcNAc levels are high. O-GlcNAcylation in breast cancer is clinically relevant, as we show that O-GlcNAc levels are higher in breast cancer as compared to matched normal tissues, and PR-positive breast cancers have higher levels of OGT. These data predict that under conditions where O-GlcNAc levels are high (breast cancer), PR, through an interaction with the modifying enzyme OGT, will exhibit increased O-GlcNAcylation and potentiated transcriptional activity. Therapeutic strategies aimed at altering cellular O-GlcNAc levels may have profound effects on PR transcriptional activity in breast cancer.
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Affiliation(s)
- Gloria M Trinca
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, MS3030, 3901 Rainbow Blvd, Kansas City, KS, 66160, USA
| | - Merit L Goodman
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, MS3030, 3901 Rainbow Blvd, Kansas City, KS, 66160, USA
| | | | - Clive S D'Santos
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge, UK
| | - Prabhakar Chalise
- Department of Biostatistics, University of Kansas Medical Center, Kansas City, KS, 66160, USA
| | - Rashna Madan
- Division of Hematology/Oncology, Department of Pathology, University of Kansas Medical Center, Kansas City, KS, 66160, USA
| | - Chad Slawson
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, MS3030, 3901 Rainbow Blvd, Kansas City, KS, 66160, USA
| | - Christy R Hagan
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, MS3030, 3901 Rainbow Blvd, Kansas City, KS, 66160, USA. .,Department of Cancer Biology, and University of Kansas Cancer Center, University of Kansas Medical Center, Kansas City, KS, 66160, USA.
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10
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The amazing ubiquitin-proteasome system: structural components and implication in aging. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2014; 314:171-237. [PMID: 25619718 DOI: 10.1016/bs.ircmb.2014.09.002] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Proteome quality control (PQC) is critical for the maintenance of cellular functionality and it is assured by the curating activity of the proteostasis network (PN). PN is constituted of several complex protein machines that under conditions of proteome instability aim to, firstly identify, and then, either rescue or degrade nonnative polypeptides. Central to the PN functionality is the ubiquitin-proteasome system (UPS) which is composed from the ubiquitin-conjugating enzymes and the proteasome; the latter is a sophisticated multi-subunit molecular machine that functions in a bimodal way as it degrades both short-lived ubiquitinated normal proteins and nonfunctional polypeptides. UPS is also involved in PQC of the nucleus, the endoplasmic reticulum and the mitochondria and it also interacts with the other main cellular degradation axis, namely the autophagy-lysosome system. UPS functionality is optimum in the young organism but it is gradually compromised during aging resulting in increasing proteotoxic stress; these effects correlate not only with aging but also with most age-related diseases. Herein, we present a synopsis of the UPS components and of their functional alterations during cellular senescence or in vivo aging. We propose that mild UPS activation in the young organism will, likely, promote antiaging effects and/or suppress age-related diseases.
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11
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Berrabah W, Aumercier P, Gheeraert C, Dehondt H, Bouchaert E, Alexandre J, Ploton M, Mazuy C, Caron S, Tailleux A, Eeckhoute J, Lefebvre T, Staels B, Lefebvre P. Glucose sensing O-GlcNAcylation pathway regulates the nuclear bile acid receptor farnesoid X receptor (FXR). Hepatology 2014; 59:2022-33. [PMID: 24037988 DOI: 10.1002/hep.26710] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Accepted: 08/23/2013] [Indexed: 12/19/2022]
Abstract
UNLABELLED Bile acid metabolism is intimately linked to the control of energy homeostasis and glucose and lipid metabolism. The nuclear receptor farnesoid X receptor (FXR) plays a major role in the enterohepatic cycling of bile acids, but the impact of nutrients on bile acid homeostasis is poorly characterized. Metabolically active hepatocytes cope with increases in intracellular glucose concentrations by directing glucose into storage (glycogen) or oxidation (glycolysis) pathways, as well as to the pentose phosphate shunt and the hexosamine biosynthetic pathway. Here we studied whether the glucose nonoxidative hexosamine biosynthetic pathway modulates FXR activity. Our results show that FXR interacts with and is O-GlcNAcylated by O-GlcNAc transferase in its N-terminal AF1 domain. Increased FXR O-GlcNAcylation enhances FXR gene expression and protein stability in a cell type-specific manner. High glucose concentrations increased FXR O-GlcNAcylation, hence its protein stability and transcriptional activity by inactivating corepressor complexes, which associate in a ligand-dependent manner with FXR, and increased FXR binding to chromatin. Finally, in vivo fasting-refeeding experiments show that FXR undergoes O-GlcNAcylation in fed conditions associated with increased direct FXR target gene expression and decreased liver bile acid content. CONCLUSION FXR activity is regulated by glucose fluxes in hepatocytes through a direct posttranslational modification catalyzed by the glucose-sensing hexosamine biosynthetic pathway.
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Affiliation(s)
- Wahiba Berrabah
- European Genomic Institute for Diabetes (EGID), Lille, France; INSERM UMR1011, Lille, France; Univ Lille 2, Lille, France; Institut Pasteur de Lille, Lille, France
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12
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Wu J, Bowe DB, Sadlonova A, Whisenhunt TR, Hu Y, Rustgi AK, Nie Y, Paterson AJ, Yang X. O-GlcNAc transferase is critical for transducin-like enhancer of split (TLE)-mediated repression of canonical Wnt signaling. J Biol Chem 2014; 289:12168-12176. [PMID: 24616106 DOI: 10.1074/jbc.m114.553859] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Drosophila Groucho protein and its mammalian orthologues the transducin-like enhancers of split (TLEs) are critical transcriptional corepressors that repress Wnt and other signaling pathways. Although it is known that Groucho/TLEs are recruited to target genes by pathway-specific transcription factors, molecular events after the corepressor recruitment are largely unclear. We report that association of TLEs with O-GlcNAc transferase, an enzyme that catalyzes posttranslational modification of proteins by O-linked N-acetylglucosamine, is essential for TLE-mediated transcriptional repression. Removal of O-GlcNAc from Wnt-responsive gene promoters is critical for gene activation from Wnt-responsive promoters. Thus, these studies identify a molecular mechanism by which Groucho/TLEs repress gene transcription and provide a model whereby O-GlcNAc may control distinct intracellular signaling pathways.
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Affiliation(s)
- Jing Wu
- Center for Mitochondrial Biology and Medicine, the Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology and Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China; Section of Comparative Medicine and Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut 06519
| | - Damon B Bowe
- Division of Endocrinology and Metabolism, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Andrea Sadlonova
- Department of Pathology and Laboratory Medicine, Emory University, Atlanta, Georgia 30322
| | - Thomas R Whisenhunt
- Division of Endocrinology and Metabolism, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Yong Hu
- Division of Endocrinology and Metabolism, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Anil K Rustgi
- Department of Medicine (GI) and Genetics, Abramson Cancer Center, 600 CRB, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Yongzhan Nie
- State Key Laboratory of Cancer Biology and Xijing Hospital of Digestive Diseases, Fourth Military Medical University, 127 West Changle Road, Xi'an, Shaanxi 710032, China
| | - Andrew J Paterson
- Division of Endocrinology and Metabolism, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Xiaoyong Yang
- Section of Comparative Medicine and Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut 06519.
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13
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Hart GW. Three Decades of Research on O-GlcNAcylation - A Major Nutrient Sensor That Regulates Signaling, Transcription and Cellular Metabolism. Front Endocrinol (Lausanne) 2014; 5:183. [PMID: 25386167 PMCID: PMC4209869 DOI: 10.3389/fendo.2014.00183] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Accepted: 10/10/2014] [Indexed: 12/31/2022] Open
Abstract
Even though the dynamic modification of polypeptides by the monosaccharide, O-linked N-acetylglucosamine (O-GlcNAcylation) was discovered over 30 years ago, its physiological significance as a major nutrient sensor that regulates myriad cellular processes has only recently been more widely appreciated. O-GlcNAcylation, either on its own or by its interplay with other post-translational modifications, such as phosphorylation, ubiquitination, and others, modulates the activities of signaling proteins, regulates most components of the transcription machinery, affects cell cycle progression and regulates the targeting/turnover or functions of myriad other regulatory proteins, in response to nutrients. Acute increases in O-GlcNAcylation protect cells from stress-induced injury, while chronic deregulation of O-GlcNAc cycling contributes to the etiology of major human diseases of aging, such as diabetes, cancer, and neurodegeneration. Recent advances in tools to study O-GlcNAcylation at the individual site level and specific inhibitors of O-GlcNAc cycling have allowed more rapid progress toward elucidating the specific functions of O-GlcNAcylation in essential cellular processes.
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Affiliation(s)
- Gerald W. Hart
- Department of Biological Chemistry, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
- *Correspondence: Gerald W. Hart, Department of Biological Chemistry, School of Medicine, Johns Hopkins University, WBSB515, 725 North Wolfe Street, Baltimore, MD 21205-2185, USA e-mail:
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14
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Medford HM, Porter K, Marsh SA. Immediate effects of a single exercise bout on protein O-GlcNAcylation and chromatin regulation of cardiac hypertrophy. Am J Physiol Heart Circ Physiol 2013; 305:H114-23. [PMID: 23624624 DOI: 10.1152/ajpheart.00135.2013] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cardiac hypertrophy induced by pathological stimuli is regulated by a complex formed by the repressor element 1-silencing transcription factor (REST) and its corepressor mSin3A. We previously reported that hypertrophic signaling is blunted by O-linked attachment of β-N-acetylglucosamine (O-GlcNAc) to proteins. Regular exercise induces a physiological hypertrophic phenotype in the heart that is associated with decreased O-GlcNAc levels, but a link between O-GlcNAc, the REST complex, and initiation of exercise-induced cardiac hypertrophy is not known. Therefore, mice underwent a single 15- or 30-min bout of moderate- to high-intensity treadmill running, and hearts were harvested immediately and compared with sedentary controls. Cytosolic O-GlcNAc was lower (P < 0.05) following 15 min exercise with no differences in nuclear levels (P > 0.05). There were no differences in cytosolic or nuclear O-GlcNAc levels in hearts after 30 min exercise (P > 0.05). Cellular compartment levels of O-GlcNAc transferase (OGT, the enzyme that removes the O-GlcNAc moiety from proteins), REST, mSin3A, and histone deacetylases (HDACs) 1, 2, 3, 4, and 5 were not changed with exercise. Immunoprecipitation revealed O-GlcNAcylation of OGT and HDACs 1, 2, 4, and 5 that was not changed with acute exercise; however, exercised hearts did exhibit lower interactions between OGT and REST (P < 0.05) but not between OGT and mSin3A. These data suggest that hypertrophic signaling in the heart may be initiated by as little as 15 min of exercise via intracellular changes in protein O-GlcNAcylation distribution and reduced interactions between OGT and the REST chromatin repressor.
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Affiliation(s)
- Heidi M Medford
- Graduate Program in Nutrition and Exercise Physiology, College of Pharmacy, Washington State University, Spokane, WA 99210, USA
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15
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Post-translational protein modification by O-linked N-acetyl-glucosamine: its role in mediating the adverse effects of diabetes on the heart. Life Sci 2012; 92:621-7. [PMID: 22985933 DOI: 10.1016/j.lfs.2012.08.006] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2012] [Revised: 07/16/2012] [Accepted: 08/02/2012] [Indexed: 11/20/2022]
Abstract
The post-translation attachment of O-linked N-acetylglucosamine, or O-GlcNAc, to serine and threonine residues of nuclear and cytoplasmic proteins is increasingly recognized as a key regulator of diverse cellular processes. O-GlcNAc synthesis is essential for cell survival and it has been shown that acute activation of pathways, which increase cellular O-GlcNAc levels is cytoprotective; however, prolonged increases in O-GlcNAcylation have been implicated in a number of chronic diseases. Glucose metabolism via the hexosamine biosynthesis pathway plays a central role in regulating O-GlcNAc synthesis; consequently, sustained increases in O-GlcNAc levels have been implicated in glucose toxicity and insulin resistance. Studies on the role of O-GlcNAc in regulating cardiomyocyte function have grown rapidly over the past decade and there is growing evidence that increased O-GlcNAc levels contribute to the adverse effects of diabetes on the heart, including impaired contractility, calcium handling, and abnormal stress responses. Recent evidence also suggests that O-GlcNAc plays a role in epigenetic control of gene transcription. The goal of this review is to provide an overview of our current knowledge about the regulation of protein O-GlcNAcylation and to explore in more detail O-GlcNAc-mediated responses in the diabetic heart.
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16
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Scruggs SB, Zong NC, Wang D, Stefani E, Ping P. Post-translational modification of cardiac proteasomes: functional delineation enabled by proteomics. Am J Physiol Heart Circ Physiol 2012; 303:H9-18. [PMID: 22523251 DOI: 10.1152/ajpheart.00189.2012] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Proteasomes are ubiquitously expressed multicatalytic complexes that serve as key regulators of protein homeostasis. There are several lines of evidence indicating that proteasomes exist in heterogeneous subpopulations in cardiac muscle, differentiated, in part, by post-translational modifications (PTMs). PTMs regulate numerous facets of proteasome function, including catalytic activities, complex assembly, interactions with associating partners, subcellular localization, substrate preference, and complex turnover. Classical technologies used to identify PTMs on proteasomes have lacked the ability to determine site specificity, quantify stoichiometry, and perform large-scale, multi-PTM analysis. Recent advancements in proteomic technologies have largely overcome these limitations. We present here a discussion on the importance of PTMs in modulating proteasome function in cardiac physiology and pathophysiology, followed by the presentation of a state-of-the-art proteomic workflow for identifying and quantifying PTMs of cardiac proteasomes.
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Affiliation(s)
- Sarah B Scruggs
- Division of Cardiology, Department of Physiology, University of California, Los Angeles, USA
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17
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Altenburg JD, Bieberich AA, Terry C, Harvey KA, Vanhorn JF, Xu Z, Jo Davisson V, Siddiqui RA. A synergistic antiproliferation effect of curcumin and docosahexaenoic acid in SK-BR-3 breast cancer cells: unique signaling not explained by the effects of either compound alone. BMC Cancer 2011; 11:149. [PMID: 21510869 PMCID: PMC3111403 DOI: 10.1186/1471-2407-11-149] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2011] [Accepted: 04/21/2011] [Indexed: 12/20/2022] Open
Abstract
Background Breast cancer is a collection of diseases in which molecular phenotypes can act as both indicators and mediators of therapeutic strategy. Therefore, candidate therapeutics must be assessed in the context of multiple cell lines with known molecular phenotypes. Docosahexaenoic acid (DHA) and curcumin (CCM) are dietary compounds known to antagonize breast cancer cell proliferation. We report that these compounds in combination exert a variable antiproliferative effect across multiple breast cell lines, which is synergistic in SK-BR-3 cells and triggers cell signaling events not predicted by the activity of either compound alone. Methods Dose response curves for CCM and DHA were generated for five breast cell lines. Effects of the DHA+ CCM combination on cell proliferation were evaluated using varying concentrations, at a fixed ratio, of CCM and DHA based on their individual ED50. Detection of synergy was performed using nonlinear regression of a sigmoid dose response model and Combination Index approaches. Cell molecular network responses were investigated through whole genome microarray analysis of transcript level changes. Gene expression results were validated by RT-PCR, and western blot analysis was performed for potential signaling mediators. Cellular curcumin uptake, with and without DHA, was analyzed via flow cytometry and HPLC. Results CCM+DHA had an antiproliferative effect in SK-BR-3, MDA-MB-231, MDA-MB-361, MCF7 and MCF10AT cells. The effect was synergistic for SK-BR-3 (ER- PR- Her2+) relative to the two compounds individually. A whole genome microarray approach was used to investigate changes in gene expression for the synergistic effects of CCM+DHA in SK-BR-3 cells lines. CCM+DHA triggered transcript-level responses, in disease-relevant functional categories, that were largely non-overlapping with changes caused by CCM or DHA individually. Genes involved in cell cycle arrest, apoptosis, inhibition of metastasis, and cell adhesion were upregulated, whereas genes involved in cancer development and progression, metastasis, and cell cycle progression were downregulated. Cellular pools of PPARγ and phospho-p53 were increased by CCM+DHA relative to either compound alone. DHA enhanced cellular uptake of CCM in SK-BR-3 cells without significantly enhancing CCM uptake in other cell lines. Conclusions The combination of DHA and CCM is potentially a dietary supplemental treatment for some breast cancers, likely dependent upon molecular phenotype. DHA enhancement of cellular curcumin uptake is one potential mechanism for observed synergy in SK-BR-3 cells; however, transcriptomic data show that the antiproliferation synergy accompanies many signaling events unique to the combined presence of the two compounds.
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Affiliation(s)
- Jeffrey D Altenburg
- Cellular Biochemistry Laboratory, Methodist Research Institute, Indiana University Health, Indianapolis, Indiana, USA
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18
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Dorfmueller HC, Borodkin VS, Schimpl M, Zheng X, Kime R, Read KD, van Aalten DMF. Cell-penetrant, nanomolar O-GlcNAcase inhibitors selective against lysosomal hexosaminidases. ACTA ACUST UNITED AC 2011; 17:1250-5. [PMID: 21095575 PMCID: PMC3032886 DOI: 10.1016/j.chembiol.2010.09.014] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2010] [Revised: 08/24/2010] [Accepted: 09/01/2010] [Indexed: 11/16/2022]
Abstract
Posttranslational modification of metazoan nucleocytoplasmic proteins with N-acetylglucosamine (O-GlcNAc) is essential, dynamic, and inducible and can compete with protein phosphorylation in signal transduction. Inhibitors of O-GlcNAcase, the enzyme removing O-GlcNAc, are useful tools for studying the role of O-GlcNAc in a range of cellular processes. We report the discovery of nanomolar OGA inhibitors that are up to 900,000-fold selective over the related lysosomal hexosaminidases. When applied at nanomolar concentrations on live cells, these cell-penetrant molecules shift the O-GlcNAc equilibrium toward hyper-O-GlcNAcylation with EC₅₀ values down to 3 nM and are thus invaluable tools for the study of O-GlcNAc cell biology.
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Affiliation(s)
- Helge C Dorfmueller
- Division of Molecular Microbiology, College of Life Sciences, University of Dundee, Dundee DD15EH, Scotland
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19
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Huang P, Ho SR, Wang K, Roessler BC, Zhang F, Hu Y, Bowe DB, Kudlow JE, Paterson AJ. Muscle-specific overexpression of NCOATGK, splice variant of O-GlcNAcase, induces skeletal muscle atrophy. Am J Physiol Cell Physiol 2010; 300:C456-65. [PMID: 21178104 DOI: 10.1152/ajpcell.00124.2010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The protein O-linked β-N-acetylglucosamine (O-GlcNAc) modification plays an important role in skeletal muscle development and physiological function. In this study, bitransgenic mice were generated that overexpressed NCOAT(GK), an O-GlcNAcase-inactive spliced variant of the O-GlcNAcase gene, specifically in skeletal muscle using the muscle creatine kinase promoter. Expression of the chimeric enhanced green fluorescent protein-NCOAT(GK) transgene caused an increase of cellular O-GlcNAc levels, along with the accumulation and activation of proapoptotic factors in muscles of bitransgenic mice. The consequence of overexpressing the transgene for a 2-wk period was muscle atrophy and, in some cases, resulted in the death of male mice. Muscle atrophy is a common complication of many diseases, some of which correlate markedly with high cellular O-GlcNAc levels, such as diabetes. Our study provides direct evidence linking muscle atrophy and the disruption of O-GlcNAcase activity.
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Affiliation(s)
- Ping Huang
- Dept. of Medicine, Univ. of Alabama at Birmingham, Birmingham, AL 35294, USA
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20
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Teo CF, Wollaston-Hayden EE, Wells L. Hexosamine flux, the O-GlcNAc modification, and the development of insulin resistance in adipocytes. Mol Cell Endocrinol 2010; 318:44-53. [PMID: 19799964 PMCID: PMC2855202 DOI: 10.1016/j.mce.2009.09.022] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2009] [Revised: 09/18/2009] [Accepted: 09/21/2009] [Indexed: 01/01/2023]
Abstract
Excess flux through the hexosamine biosynthesis pathway in adipocytes is a fundamental cause of "glucose toxicity" and the development of insulin resistance that leads to type II diabetes. Adipose tissue-specific elevation in hexosamine flux in animal models recapitulates whole-body insulin-resistant phenotypes, and increased hexosamine flux in adipocyte cell culture models impairs insulin-stimulated glucose uptake. Many studies have been devoted to unveiling the molecular mechanisms in adipocytes in response to excess hexosamine flux-mediated insulin resistance. As a major downstream event consuming and incorporating the final product of the hexosamine biosynthesis pathway, dynamic and inducible O-GlcNAc modification is emerging as a modulator of insulin sensitivity in adipocytes. Given that O-GlcNAc is implicated in both insulin-mediated signal transduction and transcriptional events essential for adipocytokine secretion, direct functional studies to pinpoint the roles of O-GlcNAc in the development of insulin resistance via excess flux through hexosamine biosynthesis pathway are needed.
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Affiliation(s)
- Chin Fen Teo
- Complex Carbohydrate Research Center and Department of Biochemistry and Molecular Biology, University of Georgia, 315 Riverbend Road, Athens, GA 30602, USA
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21
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Butkinaree C, Park K, Hart GW. O-linked beta-N-acetylglucosamine (O-GlcNAc): Extensive crosstalk with phosphorylation to regulate signaling and transcription in response to nutrients and stress. BIOCHIMICA ET BIOPHYSICA ACTA 2010; 1800:96-106. [PMID: 19647786 PMCID: PMC2815129 DOI: 10.1016/j.bbagen.2009.07.018] [Citation(s) in RCA: 339] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2009] [Revised: 07/14/2009] [Accepted: 07/18/2009] [Indexed: 02/03/2023]
Abstract
BACKGROUND Since its discovery in the early 1980s, O-linked-beta-N-acetylglucosamine (O-GlcNAc), a single sugar modification on the hydroxyl group of serine or threonine residues, has changed our views of protein glycosylation. While other forms of protein glycosylation modify proteins on the cell surface or within luminal compartments of the secretory machinery, O-GlcNAc modifies myriad nucleocytoplasmic proteins. GlcNAcylated proteins are involved in transcription, ubiquitination, cell cycle, and stress responses. GlcNAcylation is similar to protein phosphorylation in terms of stoichiometry, localization and cycling. To date, only two enzymes are known to regulate GlcNAcylation in mammals: O-GlcNAc transferase (OGT), which catalyzes the addition of O-GlcNAc, and beta-N-acetylglucosaminidase (O-GlcNAcase), a neutral hexosaminidase responsible for O-GlcNAc removal. OGT and O-GlcNAcase are regulated by RNA splicing, by nutrients, and by post-translational modifications. Their specificities are controlled by many transiently associated targeting subunits. As methods for detecting O-GlcNAc have improved our understanding of O-GlcNAc's functions has grown rapidly. SCOPE OF REVIEW In this review, the functions of GlcNAcylation in regulating cellular processes, its extensive crosstalk with protein phosphorylation, and regulation of OGT and O-GlcNAcase will be explored. MAJOR CONCLUSIONS GlcNAcylation rivals phosphorylation in terms of its abundance, protein distribution and its cycling on and off of proteins. GlcNAcylation has extensive crosstalk with phosphorylation to regulate signaling, transcription and the cytoskeleton in response to nutrients and stress. GENERAL SIGNIFICANCE Abnormal crosstalk between GlcNAcylation and phosphorylation underlies dysregulation in diabetes, including glucose toxicity, and defective GlcNAcylation is involved in neurodegenerative disease and cancer and most recently in AIDS.
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Affiliation(s)
- Chutikarn Butkinaree
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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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: 92] [Impact Index Per Article: 6.1] [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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Zhang D, Popesku JT, Martyniuk CJ, Xiong H, Duarte-Guterman P, Yao L, Xia X, Trudeau VL. Profiling neuroendocrine gene expression changes following fadrozole-induced estrogen decline in the female goldfish. Physiol Genomics 2009; 38:351-61. [DOI: 10.1152/physiolgenomics.00051.2009] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Teleost fish represent unique models to study the role of neuroestrogens because of the extremely high activity of brain aromatase (AroB; the product of cyp19a1b). Aromatase respectively converts androstenedione and testosterone to estrone and 17β-estradiol (E2). Specific inhibition of aromatase activity by fadrozole has been shown to impair estrogen production and influence neuroendocrine and reproductive functions in fish, amphibians, and rodents. However, very few studies have identified the global transcriptomic response to fadrozole-induced decline of estrogens in a physiological context. In our study, sexually mature prespawning female goldfish were exposed to fadrozole (50 μg/l) in March and April when goldfish have the highest AroB activity and maximal gonadal size. Fadrozole treatment significantly decreased serum E2 levels (4.7 times lower; P = 0.027) and depressed AroB mRNA expression threefold in both the telencephalon ( P = 0.021) and the hypothalamus ( P = 0.006). Microarray expression profiling of the telencephalon identified 98 differentially expressed genes after fadrozole treatment ( q value <0.05). Some of these genes have shown previously to be estrogen responsive in either fish or other species, including rat, mouse, and human. Gene ontology analysis together with functional annotations revealed several regulatory themes for physiological estrogen action in fish brain that include the regulation of calcium signaling pathway and autoregulation of estrogen receptor action. Real-time PCR verified microarray data for decreased (activin-βA) or increased (calmodulin, ornithine decarboxylase 1) mRNA expression. These data have implications for our understanding of estrogen actions in the adult vertebrate brain.
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Affiliation(s)
- Dapeng Zhang
- Centre for Advanced Research in Environmental Genomics (CAREG), Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Jason T. Popesku
- Centre for Advanced Research in Environmental Genomics (CAREG), Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Christopher J. Martyniuk
- Centre for Advanced Research in Environmental Genomics (CAREG), Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Huiling Xiong
- Centre for Advanced Research in Environmental Genomics (CAREG), Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Paula Duarte-Guterman
- Centre for Advanced Research in Environmental Genomics (CAREG), Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Linhui Yao
- Centre for Advanced Research in Environmental Genomics (CAREG), Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Xuhua Xia
- Centre for Advanced Research in Environmental Genomics (CAREG), Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Vance L. Trudeau
- Centre for Advanced Research in Environmental Genomics (CAREG), Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
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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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25
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Wang K, Ho SR, Mao W, Huang P, Zhang F, Schwiebert EM, Kudlow JE, Paterson AJ. Increased O-GlcNAc causes disrupted lens fiber cell differentiation and cataracts. Biochem Biophys Res Commun 2009; 387:70-6. [PMID: 19577582 DOI: 10.1016/j.bbrc.2009.06.132] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Accepted: 06/22/2009] [Indexed: 10/20/2022]
Abstract
Diminished proteolytic functionality in the lens may cause cataracts. We have reported that O-GlcNAc is an endogenous inhibitor of the proteasome. We hypothesize that in the lens there is a cause-and-effect relationship between proteasome inhibition by O-GlcNAc, and cataract formation. To demonstrate this, we established novel transgenic mouse models to over-express a dominant-negative form of O-GlcNAcase, GK-NCOAT, in the lens. Expression of GK-NCOAT suppresses removal of O-GlcNAc from proteins, resulting in increased levels of O-GlcNAc in the lenses of our transgenic mice, along with decreased proteasome function. We observed that transgenic mice developed markedly larger cataracts than controls and lens fiber cell denucleation was inhibited. Our study suggests that increased O-GlcNAc in the lens could lead to cataract formation and attenuation of lens fiber cell denucleation by inhibition of proteasome function. These findings may explain why cataract formation is a common complication of diabetes since O-GlcNAc is derived from glucose.
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Affiliation(s)
- Kai Wang
- Department of Medicine, Division of Endocrinology, Diabetes and metabolism, University of Alabama at Birmingham, 1808 7th Avenue South, Birmingham, AL 35294, USA
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26
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Identification of protein O-GlcNAcylation sites using electron transfer dissociation mass spectrometry on native peptides. Proc Natl Acad Sci U S A 2009; 106:8894-9. [PMID: 19458039 DOI: 10.1073/pnas.0900288106] [Citation(s) in RCA: 194] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Protein O-GlcNAcylation occurs in all animals and plants and is implicated in modulation of a wide range of cytosolic and nuclear protein functions, including gene silencing, nutrient and stress sensing, phosphorylation signaling, and diseases such as diabetes and Alzheimer's. The limiting factor impeding rapid progress in deciphering the biological functions of protein O-GlcNAcylation has been the inability to easily identify exact residues of modification. We describe a robust, high-sensitivity strategy able to assign O-GlcNAcylation sites of native modified peptides using electron transfer dissociation mass spectrometry. We have studied the murine postsynaptic density pseudoorganelle and report the assignment of 58 modification sites from a single experiment--significantly increasing the number of sites known in the literature. Components of several repressor complexes, such as NCoR1, polyhomeotic-like protein3, and EMSY, are modified. In addition, 28 O-GlcNAc sites were found on the protein Bassoon, effectively matching the number of phosphorylation sites reported previously on this protein. This finding suggests that on certain proteins, O-GlcNAcylation may be as extensive and important as phosphorylation in regulating protein function. Three of the newly discovered O-GlcNAc sites on Bassoon have previously been reported as phosphorylation sites, highlighting the interplay of the modifications. Surprisingly, several peptides with GlcNAc modifications on asparagines within the N-X-S/T consensus sequence were also observed from membrane protein extracellular domains. This powerful strategy fulfills a long-standing need in the biological community by facilitating modification site identifications that will accelerate understanding of the biological significance of this elusive regulatory posttranslational modification.
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Lim K, Chang HI. O-GlcNAcylation of Sp1 interrupts Sp1 interaction with NF-Y. Biochem Biophys Res Commun 2009; 382:593-7. [PMID: 19302979 DOI: 10.1016/j.bbrc.2009.03.075] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2009] [Accepted: 03/12/2009] [Indexed: 11/16/2022]
Abstract
O-linked N-acetylglucosamine (O-GlcNAc), a monosaccharide N-acetylglucosamine addition on nucleocytoplasmic proteins, is abundant in transcription regulators and has been implicated in gene regulation. Sp1 transcription factor is multiply modified by O-GlcNAc within its serine/threonine-rich region and glutamine-rich transactivation domain. In the present study, we show that O-GlcNAc of Sp1 serine/threonine-rich region interrupts a physical interaction between Sp1 and NF-YA, thus inhibiting Sp1-NF-Y cooperative activation of gene transcription. Our results strengthen the notion that O-GlcNAc regulates gene transcription by modulating the protein-protein interaction network among transcription regulatory proteins.
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Affiliation(s)
- Kihong Lim
- School of Life Sciences and Biotechnology, Korea University, 5-1 Anam-dong, Seongbuk-gu, Seoul 136-701, Republic of Korea
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28
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Lim K, Chang HI. O-GlcNAc inhibits interaction between Sp1 and Elf-1 transcription factors. Biochem Biophys Res Commun 2009; 380:569-74. [PMID: 19285002 DOI: 10.1016/j.bbrc.2009.01.121] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2009] [Accepted: 01/22/2009] [Indexed: 11/24/2022]
Abstract
The novel protein modification, O-linked N-acetylglucosamine (O-GlcNAc), plays an important role in various aspects of cell regulation. Although most of nuclear transcription regulatory factors are modified by O-GlcNAc, O-GlcNAc effects on transcription remain largely undefined yet. In this study, we show that O-GlcNAc inhibits a physical interaction between Sp1 and Elf-1 transcription factors, and negatively regulates transcription of placenta and embryonic expression oncofetal protein gene (Pem). These findings suggest that O-GlcNAc inhibits Sp1-mediated gene transcription possibly by interrupting Sp1 interaction with its cooperative factor.
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Affiliation(s)
- Kihong Lim
- School of Life Sciences and Biotechnology, Korea University, 5-1 Anam-dong, Seongbuk-gu, Seoul 136-701, Republic of Korea
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29
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Lim K, Chang HI. O-GlcNAc modification of Sp1 inhibits the functional interaction between Sp1 and Oct1. FEBS Lett 2008; 583:512-20. [PMID: 19070619 DOI: 10.1016/j.febslet.2008.12.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2008] [Revised: 11/25/2008] [Accepted: 12/02/2008] [Indexed: 11/28/2022]
Abstract
Sp1 is a ubiquitous transcription factor that is modified by multiple O-linked N-acetylglucosamines (O-GlcNAc). Previously, O-GlcNAcylation of a specific site of Sp1 was shown to inhibit Sp1 transcriptional activity. Yet, how O-GlcNAc on other modification sites affects Sp1 function and how O-GlcNAcylation of Sp1 affects the transcriptional regulation of a target gene remains unknown. Here we show that O-GlcNAc within the second serine/threonine-rich region of Sp1 interrupts a known interaction between Sp1 and Oct1, and inhibits the cooperative activation of the U2 snRNA gene by Sp1 and Oct1.
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Affiliation(s)
- Kihong Lim
- School of Life Sciences and Biotechnology, Korea University, Seoul, Republic of Korea
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Kaleem A, Hoessli DC, Ahmad I, Walker-Nasir E, Nasim A, Shakoori AR. Immediate-early gene regulation by interplay between different post-translational modifications on human histone H3. J Cell Biochem 2008; 103:835-51. [PMID: 17668447 DOI: 10.1002/jcb.21454] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
In mammalian cells, induction of immediate-early (IE) gene transcription occurs concomitantly with histone H3 phosphorylation on Ser 10 and is catalyzed by mitogen-activated protein kinases (MAPKs). Histone H3 is an evolutionarily conserved protein located in the core of the nucleosome, along with histones H2A, H2B, and H4. The N-terminal tails of histones protrude outside the chromatin structure and are accessible to various enzymes for post-translational modifications (PTM). Phosphorylation, O-GlcNAc modification, and their interplay often induce functional changes, but it is very difficult to monitor dynamic structural and functional changes in vivo. To get started in this complex task, computer-assisted studies are useful to predict the range in which those dynamic structural and functional changes may occur. As an illustration, we propose blocking of phosphorylation by O-GlcNAc modification on Ser 10, which may result in gene silencing in the presence of methylated Lys 9. Thus, alternate phosphorylation and O-GlcNAc modification on Ser 10 in the histone H3 protein may provide an on/off switch to regulate expression of IE genes.
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Affiliation(s)
- Afshan Kaleem
- Institute of Molecular Sciences and Bioinformatics, Lahore, Pakistan
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31
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Dias WB, Hart GW. O-GlcNAc modification in diabetes and Alzheimer's disease. MOLECULAR BIOSYSTEMS 2007; 3:766-72. [PMID: 17940659 DOI: 10.1039/b704905f] [Citation(s) in RCA: 190] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Similar to phosphorylation, O-GlcNAcylation (or simply GlcNAcylation) is an abundant, dynamic, and inducible post-translational modification. In some cases, GlcNAcylation and phosphorylation occur at the same or adjacent sites, modulating each other. GlcNAcylated proteins are crucial in regulating virtually all cellular processes, including signaling, cell cycle, and transcription, among others. GlcNAcylation affects protein-protein interactions, activity, stability, and expression. Several GlcNAcylated proteins are involved in diabetes and Alzheimer's disease. Hyperglycemia increases GlcNAcylation of proteins within the insulin signaling pathway and contributes to insulin resistance. In addition, hyperinsulinemia and hyperlipidemia are also associated with increased GlcNAcylation, which affect and regulate several insulin signaling proteins, as well as proteins involved on the pathology of diabetes. With respect to Alzheimer's disease, several proteins involved in the etiology of the disease, including tau, neurofilaments, beta-amyloid precursor protein, and synaptosomal proteins are GlcNAcylated in normal brain. The impairment of brain glucose uptake/metabolism is a known metabolic defect in Alzheimer's neurons. Data support the hypothesis that hypoglycemia within the brain may reduce the normal GlcNAcylation of tau, exposing kinase acceptor sites, thus leading to hyperphosphorylation, which induces tangle formation and neuronal death. Alzheimer's disease and type II diabetes represent two metabolic disorders where dysfunctional protein GlcNAcylation/phosphorylation may be important for disease pathology.
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Affiliation(s)
- Wagner B Dias
- Department of Biological Chemistry, Johns Hopkins University, School of Medicine, 725 N. Wolfe St., Baltimore, MD 21205-2185
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