151
|
Schaller-Schönitz M, Barzan D, Williamson AJK, Griffiths JR, Dallmann I, Battmer K, Ganser A, Whetton AD, Scherr M, Eder M. BCR-ABL affects STAT5A and STAT5B differentially. PLoS One 2014; 9:e97243. [PMID: 24836440 PMCID: PMC4023949 DOI: 10.1371/journal.pone.0097243] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Accepted: 04/16/2014] [Indexed: 11/21/2022] Open
Abstract
Signal transducers and activators of transcription (STATs) are latent cytoplasmic transcription factors linking extracellular signals to target gene transcription. Hematopoietic cells express two highly conserved STAT5-isoforms (STAT5A/STAT5B), and STAT5 is directly activated by JAK2 downstream of several cytokine receptors and the oncogenic BCR-ABL tyrosine kinase. Using an IL-3-dependent cell line with inducible BCR-ABL-expression we compared STAT5-activation by IL-3 and BCR-ABL in a STAT5-isoform specific manner. RNAi targeting of STAT5B strongly inhibits BCR-ABL-dependent cell proliferation, and STAT5B but not STAT5A is essential for BCL-XL-expression in the presence of BCR-ABL. Although BCR-ABL induces STAT5-tyrosine phosphorylation independent of JAK2-kinase activity, BCR-ABL is less efficient in inducing active STAT5A:STAT5B-heterodimerization than IL-3, leaving constitutive STAT5A and STAT5B-homodimerization unaffected. In comparison to IL-3, nuclear accumulation of a STAT5A-eGFP fusion protein is reduced by BCR-ABL, and BCR-ABL tyrosine kinase activity induces STAT5A-eGFP translocation to the cell membrane and co-localization with the IL-3 receptor. Furthermore, BCR-ABL-dependent phosphorylation of Y682 in STAT5A was detected by mass-spectrometry. Finally, RNAi targeting STAT5B but not STAT5A sensitizes human BCR-ABL-positive cell lines to imatinib-treatment. These data demonstrate differences between IL-3 and BCR-ABL-mediated STAT5-activation and isoform-specific effects, indicating therapeutic options for isoform-specific STAT5-inhibition in BCR-ABL-positive leukemia.
Collapse
Affiliation(s)
- Michael Schaller-Schönitz
- Hannover Medical School, Department of Hematology, Hemostasis, Oncology and Stem Cell Transplantation, Hannover, Germany
| | - David Barzan
- Hannover Medical School, Department of Hematology, Hemostasis, Oncology and Stem Cell Transplantation, Hannover, Germany
| | - Andrew J. K. Williamson
- Faculty of Medical and Human Sciences, Manchester Academic Health Science Centre, University of Manchester, Wolfson Molecular Imaging Centre, Manchester, United Kingdom
| | - John R. Griffiths
- Faculty of Medical and Human Sciences, Manchester Academic Health Science Centre, University of Manchester, Wolfson Molecular Imaging Centre, Manchester, United Kingdom
| | - Iris Dallmann
- Hannover Medical School, Department of Hematology, Hemostasis, Oncology and Stem Cell Transplantation, Hannover, Germany
| | - Karin Battmer
- Hannover Medical School, Department of Hematology, Hemostasis, Oncology and Stem Cell Transplantation, Hannover, Germany
| | - Arnold Ganser
- Hannover Medical School, Department of Hematology, Hemostasis, Oncology and Stem Cell Transplantation, Hannover, Germany
| | - Anthony D. Whetton
- Faculty of Medical and Human Sciences, Manchester Academic Health Science Centre, University of Manchester, Wolfson Molecular Imaging Centre, Manchester, United Kingdom
| | - Michaela Scherr
- Hannover Medical School, Department of Hematology, Hemostasis, Oncology and Stem Cell Transplantation, Hannover, Germany
| | - Matthias Eder
- Hannover Medical School, Department of Hematology, Hemostasis, Oncology and Stem Cell Transplantation, Hannover, Germany
- * E-mail:
| |
Collapse
|
152
|
Lill JR, Wertz IE. Toward understanding ubiquitin-modifying enzymes: from pharmacological targeting to proteomics. Trends Pharmacol Sci 2014; 35:187-207. [PMID: 24717260 DOI: 10.1016/j.tips.2014.01.005] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 01/24/2014] [Accepted: 01/24/2014] [Indexed: 11/20/2022]
Abstract
Ubiquitination is a highly conserved post-translational modification that regulates protein trafficking, function, and turnover. Ubiquitin ligases (E3s) conjugate ubiquitin polypeptides on substrates, whereas deubiquitnases (DUBs) reverse ubiquitination. Engineering of chemical antagonists and inhibitors of ubiquitin ligases and DUBs has considerably aided the study of enzymes that participate in ubiquitin modification of substrates. In addition, proteomic tools have been developed to characterize the enzymes, substrates, and modifications regulated by DUBs and E3s. Here we review inhibitors and antagonists that have been developed against DUBs and E3s, focusing on enzymes that participate in ubiquitin editing or in the reciprocal ubiquitin regulation of substrates. We outline the cellular biology that is regulated by these DUBs and E3s and highlight how the inhibitory compounds have improved our understanding of these pathways. Finally, we discuss the challenges and future directions for pharmacologically targeting ubiquitin-modifying enzymes, as well as the development of proteomic methods to evaluate ubiquitin modification of substrates.
Collapse
Affiliation(s)
- Jennie R Lill
- Department of Protein Chemistry, Genentech, Inc., 1 DNA Way, M/S 413A, South San Francisco, CA 94080, USA.
| | - Ingrid E Wertz
- Department of Early Discovery Biochemistry, Genentech, Inc., 1 DNA Way, M/S 40, South San Francisco, CA 94080, USA.
| |
Collapse
|
153
|
Elbaum MB, Zondlo NJ. OGlcNAcylation and phosphorylation have similar structural effects in α-helices: post-translational modifications as inducible start and stop signals in α-helices, with greater structural effects on threonine modification. Biochemistry 2014; 53:2242-60. [PMID: 24641765 PMCID: PMC4004263 DOI: 10.1021/bi500117c] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
![]()
OGlcNAcylation
and phosphorylation are the major competing intracellular
post-translational modifications of serine and threonine residues.
The structural effects of both post-translational modifications on
serine and threonine were examined within Baldwin model α-helical
peptides (Ac-AKAAAAKAAAAKAAGY-NH2 or Ac-YGAKAAAAKAAAAKAA-NH2). At the N-terminus of an α-helix, both phosphorylation
and OGlcNAcylation stabilized the α-helix relative to the free
hydroxyls, with a larger induced structure for phosphorylation than
for OGlcNAcylation, for the dianionic phosphate than for the monoanionic
phosphate, and for modifications on threonine than for modifications
on serine. Both phosphoserine and phosphothreonine resulted in peptides
more α-helical than alanine at the N-terminus, with dianionic
phosphothreonine the most α-helix-stabilizing residue here.
In contrast, in the interior of the α-helix, both post-translational
modifications were destabilizing with respect to the α-helix,
with the greatest destabilization seen for threonine OGlcNAcylation
at residue 5 and threonine phosphorylation at residue 10, with peptides
containing either post-translational modification existing as random
coils. At the C-terminus, both OGlcNAcylation and phosphorylation
were destabilizing with respect to the α-helix, though the induced
structural changes were less than in the interior of the α-helix.
In general, the structural effects of modifications on threonine were
greater than the effects on serine, because of both the lower α-helical
propensity of Thr and the more defined induced structures upon modification
of threonine than serine, suggesting threonine residues are particularly
important loci for structural effects of post-translational modifications.
The effects of serine and threonine post-translational modifications
are analogous to the effects of proline on α-helices, with the
effects of phosphothreonine being greater than those of proline throughout
the α-helix. These results provide a basis for understanding
the context-dependent structural effects of these competing protein
post-translational modifications.
Collapse
Affiliation(s)
- Michael B Elbaum
- Department of Chemistry and Biochemistry, University of Delaware , Newark, Delaware 19716, United States
| | | |
Collapse
|
154
|
Deng RP, He X, Guo SJ, Liu WF, Tao Y, Tao SC. Global identification of O-GlcNAc transferase (OGT) interactors by a human proteome microarray and the construction of an OGT interactome. Proteomics 2014; 14:1020-30. [PMID: 24536041 DOI: 10.1002/pmic.201300144] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Revised: 01/23/2014] [Accepted: 01/29/2014] [Indexed: 11/10/2022]
Abstract
O-Linked β-N-acetylglucosamine (O-GlcNAcylation) is an important protein PTM, which is very abundant in mammalian cells. O-GlcNAcylation is catalyzed by O-GlcNAc transferase (OGT), whose substrate specificity is believed to be regulated through interactions with other proteins. There are a handful of known human OGT interactors, which is far from enough for fully elucidating the substrate specificity of OGT. To address this challenge, we used a human proteome microarray containing ~17,000 affinity-purified human proteins to globally identify OGT interactors and identified 25 OGT-binding proteins. Bioinformatics analysis showed that these interacting proteins play a variety of roles in a wide range of cellular functions and are highly enriched in intra-Golgi vesicle-mediated transport and vitamin biosynthetic processes. Combining newly identified OGT interactors with the interactors identified prior to this study, we have constructed the first OGT interactome. Bioinformatics analysis suggests that the OGT interactome plays important roles in protein transportation/localization and transcriptional regulation. The novel OGT interactors that we identified in this study could serve as a starting point for further functional analysis. Because of its high-throughput and parallel analysis capability, we strongly believe that protein microarrays could be easily applied for the global identification of regulators for other key enzymes.
Collapse
Affiliation(s)
- Rui-Ping Deng
- Key Laboratory of Systems Biomedicine (Ministry of Education), Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, P. R. China; State Key Laboratory of Oncogenes and Related Genes, Shanghai, P. R. China
| | | | | | | | | | | |
Collapse
|
155
|
Abstract
The post-translational modification of serine and threonine residues of proteins by O-linked β-N-acetylglucosamine (O-GlcNAc) is highly ubiquitous, dynamic and inducible. Protein O-GlcNAcylation serves as a key regulator of critical biological processes including transcription, translation, proteasomal degradation, signal transduction and apoptosis. Increased O-GlcNAcylation is directly linked to insulin resistance and to hyperglycemia-induced glucose toxicity, two hallmarks of diabetes and diabetic complications. In this review, we briefly summarize what is known about protein O-GlcNAcylation and nutrient metabolism, as well as discuss the commonly used tools to probe changes of O-GlcNAcylation in cultured cells and in animal models. We then focus on some key proteins modified by O-GlcNAc, which play crucial roles in the etiology and progression of diabetes and diabetic complications. Proteomic approaches are also highlighted to provide a system view of protein O-GlcNAcylation. Finally, we discuss how aberrant O-GlcNAcylation on certain proteins may be exploited to develop methods for the early diagnosis of pre-diabetes and/or diabetes.
Collapse
Affiliation(s)
- Junfeng Ma
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205-2185, USA
| | | |
Collapse
|
156
|
Ma J, Hart GW. O-GlcNAc profiling: from proteins to proteomes. Clin Proteomics 2014; 11:8. [PMID: 24593906 PMCID: PMC4015695 DOI: 10.1186/1559-0275-11-8] [Citation(s) in RCA: 201] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 02/01/2014] [Indexed: 11/16/2022] Open
Abstract
O-linked β-D-N-acetylglucosamine (O-GlcNAc) modification (O-GlcNAcylation) onto serine and threonine residues of proteins is an important post-translational modification (PTM), which is involved in many crucial biological processes including transcription, translation, proteasomal degradation, and signal transduction. Aberrant protein O-GlcNAcylation is directly linked to the pathological progression of chronic diseases including diabetes, cancer, and neurodegenerative disorders. Identification, site mapping, and quantification of O-GlcNAc proteins are a prerequisite to decipher their functions. In this review, we mainly focus on technological developments regarding O-GlcNAc protein profiling. Specifically, on one hand, we show how these techniques are being used for the comprehensive characterization of certain targeted proteins in which biologists are most interested. On the other hand, we present several newly developed approaches for O-GlcNAcomic profiling as well as how they provide us with a systems perspective to crosstalk amongst different PTMs and complicated biological events. Promising technical trends are also highlighted to evoke more efforts by diverse laboratories, which would further expand our understanding of the physiological and pathological roles of protein O-GlcNAcylation in chronic diseases.
Collapse
Affiliation(s)
| | - Gerald W Hart
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205-2185, USA.
| |
Collapse
|
157
|
Huynh K, Bernardo BC, McMullen JR, Ritchie RH. Diabetic cardiomyopathy: mechanisms and new treatment strategies targeting antioxidant signaling pathways. Pharmacol Ther 2014; 142:375-415. [PMID: 24462787 DOI: 10.1016/j.pharmthera.2014.01.003] [Citation(s) in RCA: 400] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Accepted: 01/08/2014] [Indexed: 12/14/2022]
Abstract
Cardiovascular disease is the primary cause of morbidity and mortality among the diabetic population. Both experimental and clinical evidence suggest that diabetic subjects are predisposed to a distinct cardiomyopathy, independent of concomitant macro- and microvascular disorders. 'Diabetic cardiomyopathy' is characterized by early impairments in diastolic function, accompanied by the development of cardiomyocyte hypertrophy, myocardial fibrosis and cardiomyocyte apoptosis. The pathophysiology underlying diabetes-induced cardiac damage is complex and multifactorial, with elevated oxidative stress as a key contributor. We now review the current evidence of molecular disturbances present in the diabetic heart, and their role in the development of diabetes-induced impairments in myocardial function and structure. Our focus incorporates both the contribution of increased reactive oxygen species production and reduced antioxidant defenses to diabetic cardiomyopathy, together with modulation of protein signaling pathways and the emerging role of protein O-GlcNAcylation and miRNA dysregulation in the progression of diabetic heart disease. Lastly, we discuss both conventional and novel therapeutic approaches for the treatment of left ventricular dysfunction in diabetic patients, from inhibition of the renin-angiotensin-aldosterone-system, through recent evidence favoring supplementation of endogenous antioxidants for the treatment of diabetic cardiomyopathy. Novel therapeutic strategies, such as gene therapy targeting the phosphoinositide 3-kinase PI3K(p110α) signaling pathway, and miRNA dysregulation, are also reviewed. Targeting redox stress and protective protein signaling pathways may represent a future strategy for combating the ever-increasing incidence of heart failure in the diabetic population.
Collapse
Affiliation(s)
- Karina Huynh
- Baker IDI Heart & Diabetes Institute, Melbourne, Australia; Department of Medicine, Monash University, Clayton, Victoria, Australia
| | | | - Julie R McMullen
- Baker IDI Heart & Diabetes Institute, Melbourne, Australia; Department of Medicine, Monash University, Clayton, Victoria, Australia; Department of Physiology, Monash University, Clayton, Victoria, Australia.
| | - Rebecca H Ritchie
- Baker IDI Heart & Diabetes Institute, Melbourne, Australia; Department of Medicine, Monash University, Clayton, Victoria, Australia.
| |
Collapse
|
158
|
Chaiyawat P, Netsirisawan P, Svasti J, Champattanachai V. Aberrant O-GlcNAcylated Proteins: New Perspectives in Breast and Colorectal Cancer. Front Endocrinol (Lausanne) 2014; 5:193. [PMID: 25426101 PMCID: PMC4227529 DOI: 10.3389/fendo.2014.00193] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Accepted: 10/28/2014] [Indexed: 12/21/2022] Open
Abstract
Increasing glucose consumption is thought to provide an evolutionary advantage to cancer cells. Alteration of glucose metabolism in cancer influences various important metabolic pathways including the hexosamine biosynthesis pathway (HBP), a relatively minor branch of glycolysis. Uridine diphosphate N-acetylglucosamine (UDP-GlcNAc), an end product of HBP, is a sugar substrate used for classical glycosylation and O-GlcNAcylation, a post-translational protein modification implicated in a wide range of effects on cellular functions. Emerging evidence reveals that certain cellular proteins are abnormally O-GlcNAc modified in many kinds of cancers, indicating O-GlcNAcylation is associated with malignancy. Since O-GlcNAc rapidly on and off modifies in a similar time scale as in phosphorylation and these modifications may occur on proteins at either on the same or adjacent sites, it suggests that both modifications can work to regulate the cellular signaling pathways. This review describes the metabolic shifts related to the HBP, which are commonly found in most cancers. It also describes O-GlcNAc modified proteins identified in primary breast and colorectal cancer, as well as in the related cancer cell lines. Moreover, we also discuss the potential use of aberrant O-GlcNAcylated proteins as novel biomarkers of cancer.
Collapse
Affiliation(s)
- Parunya Chaiyawat
- Applied Biological Sciences Program, Chulabhorn Graduate Institute, Bangkok, Thailand
| | | | - Jisnuson Svasti
- Applied Biological Sciences Program, Chulabhorn Graduate Institute, Bangkok, Thailand
- Laboratory of Biochemistry, Chulabhorn Research Institute, Bangkok, Thailand
| | - Voraratt Champattanachai
- Applied Biological Sciences Program, Chulabhorn Graduate Institute, Bangkok, Thailand
- Laboratory of Biochemistry, Chulabhorn Research Institute, Bangkok, Thailand
- *Correspondence: Voraratt Champattanachai, Laboratory of Biochemistry, Chulabhorn Research Institute, 54 Kamphaeng Phet 6, Laksi, Bangkok 10210, Thailand e-mail:
| |
Collapse
|
159
|
Cieniewski-Bernard C, Dupont E, Deracinois B, Lambert M, Bastide B. Multiplexed Detection of O-GlcNAcome, Phosphoproteome, and Whole Proteome within the Same Gel. Front Endocrinol (Lausanne) 2014; 5:184. [PMID: 25389416 PMCID: PMC4211549 DOI: 10.3389/fendo.2014.00184] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 10/11/2014] [Indexed: 11/18/2022] Open
Abstract
The cellular diversity of proteins results in part from their post-translational modifications. Among all of them, the O-GlcNAcylation is an atypical glycosylation, more similar to phosphorylation than classical glycosylations. Highly dynamic, reversible, and exclusively localized on cytosolic, nuclear, and mitochondrial proteins, O-GlcNAcylation is known to regulate almost all if not all cellular processes. Fundamental for the cell life, O-GlcNAcylation abnormalities are involved in the etiology of several inherited diseases. Assessing to O-GlcNAcylation pattern will permit to get relevant data about the role of O-GlcNAcylation in cell physiology. To get understanding about the role of O-GlcNAcylation, as also considering its interplay with phosphorylation, the O-GlcNAc profiling remains a real challenge for the community of proteomists/glycoproteomists. The development of multiplexed proteomics based on fluorescent detection of proteins permits to go further in the understanding of the proteome complexity. We propose herein a multiplexed proteomic strategy to detect O-GlcNAcylated proteins, phosphoproteins, and the whole proteome within the same bidimensional gel. In particular, we investigated the phosphoproteome through the ProQ Diamond staining, while the whole proteome was visualized through Sypro Ruby staining, or after the labeling of proteins with a T-Dye fluorophore. The O-GlcNAcome was revealed by the way of the Click chemistry and the azide-alkyne cycloaddition of a fluorophore on GlcNAc moieties. This method permits, after sequential image acquisition, the direct in-gel detection of O-GlcNAcome, phosphoproteome, and whole proteome.
Collapse
Affiliation(s)
- Caroline Cieniewski-Bernard
- Université Lille Nord de France, Lille, France
- EA4488, APMS (Physical activity muscle and health), URePSSS, Université de Lille 1, Villeneuve d’Ascq, France
- *Correspondence: Caroline Cieniewski-Bernard, EA4488 Laboratoire Activité Physique, Muscle et Santé, IFR114, Biology Department, Université de Lille 1, Villeneuve d’Ascq 59655, France e-mail:
| | - Erwan Dupont
- Université Lille Nord de France, Lille, France
- EA4488, APMS (Physical activity muscle and health), URePSSS, Université de Lille 1, Villeneuve d’Ascq, France
| | - Barbara Deracinois
- Université Lille Nord de France, Lille, France
- EA4488, APMS (Physical activity muscle and health), URePSSS, Université de Lille 1, Villeneuve d’Ascq, France
| | - Matthias Lambert
- Université Lille Nord de France, Lille, France
- EA4488, APMS (Physical activity muscle and health), URePSSS, Université de Lille 1, Villeneuve d’Ascq, France
| | - Bruno Bastide
- Université Lille Nord de France, Lille, France
- EA4488, APMS (Physical activity muscle and health), URePSSS, Université de Lille 1, Villeneuve d’Ascq, France
| |
Collapse
|
160
|
Martin JC, Fadda E, Ito K, Woods RJ. Defining the structural origin of the substrate sequence independence of O-GlcNAcase using a combination of molecular docking and dynamics simulation. Glycobiology 2014; 24:85-96. [PMID: 24134879 PMCID: PMC3854502 DOI: 10.1093/glycob/cwt094] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 10/05/2013] [Accepted: 10/13/2013] [Indexed: 11/13/2022] Open
Abstract
Protein glycosylation with O-linked N-acetylglucosamine (O-GlcNAc) is a post-translational modification of serine/threonine residues in nucleocytoplasmic proteins. O-GlcNAc has been shown to play a role in many different cellular processes and O-GlcNAcylation is often found at sites that are also known to be phosphorylated. Unlike phosphorylation, O-GlcNAc levels are regulated by only two enzymes, O-GlcNAc transferase (OGT) and O-GlcNAc hydrolase (O-GlcNAcase or OGA). So far, no obvious consensus sequence has been found for sites of O-GlcNAcylation. Additionally, O-GlcNAcase recognizes and cleaves all O-GlcNAcylated proteins, independent of their sequence. In this work, we generate and analyze five models of O-GlcNAcylated peptides in complex with a bacterial OGA. Each of the five glycopeptides bind to OGA in a similar fashion, with OGA-peptide interactions primarily, but not exclusively, involving the peptide backbone atoms, thus explaining the lack of sensitivity to peptide sequence. Nonetheless, differences in peptide sequences, particularly at the -1 to -4 positions, lead to variations in predicted affinity, consistent with observed experimental variations in enzyme kinetics. The potential exists, therefore, to employ the present analysis to guide the development glycopeptide-specific inhibitors, or conversely, the conversion of OGA into a reagent that could target specific O-GlcNAcylated peptide sequences.
Collapse
Affiliation(s)
- Joanne C Martin
- School of Chemistry, National University of Ireland, University Road, Galway, Ireland
| | - Elisa Fadda
- School of Chemistry, National University of Ireland, University Road, Galway, Ireland
| | - Keigo Ito
- Complex Carbohydrate Research Centre, University of Georgia, 315 Riverbend Road, Athens, GA 30602, USA
| | - Robert J Woods
- School of Chemistry, National University of Ireland, University Road, Galway, Ireland
- Complex Carbohydrate Research Centre, University of Georgia, 315 Riverbend Road, Athens, GA 30602, USA
| |
Collapse
|
161
|
Wang S, Shen DL, Lafont D, Vercoutter-Edouart AS, Mortuaire M, Shi Y, Maniti O, Girard-Egrot A, Lefebvre T, Pinto BM, Vocadlo D, Vidal S. Design of glycosyltransferase inhibitors targeting human O-GlcNAc transferase (OGT). MEDCHEMCOMM 2014. [DOI: 10.1039/c4md00063c] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Inhibition of glycosyltransferases requires the design of neutral inhibitors to allow cell permeation as mimicks of their natural dianionic substrates.
Collapse
|
162
|
Lichti CF, Wildburger NC, Emmett MR, Mostovenko E, Shavkunov AS, Strain SK, Nilsson CL. Post-translational Modifications in the Human Proteome. TRANSLATIONAL BIOINFORMATICS 2014. [DOI: 10.1007/978-94-017-9202-8_6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
|
163
|
Zhang YY, Li HX, Chen YY, Fang H, Yu YN, Liu J, Jing ZW, Wang Z, Wang YY. Convergent and divergent pathways decoding hierarchical additive mechanisms in treating cerebral ischemia-reperfusion injury. CNS Neurosci Ther 2013; 20:253-63. [PMID: 24351012 DOI: 10.1111/cns.12205] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2013] [Revised: 10/14/2013] [Accepted: 10/15/2013] [Indexed: 12/29/2022] Open
Abstract
INTRODUCTION Cerebral ischemia is considered to be a highly complex disease resulting from the complicated interplay of multiple pathways. Disappointedly, most of the previous studies were limited to a single gene or a single pathway. The extent to which all involved pathways are translated into fusing mechanisms of a combination therapy is of fundamental importance. AIMS We report an integrative strategy to reveal the additive mechanism that a combination (BJ) of compound baicalin (BA) and jasminoidin (JA) fights against cerebral ischemia based on variation of pathways and functional communities. RESULTS We identified six pathways of BJ group that shared diverse additive index from 0.09 to 1, which assembled broad cross talks from seven pathways of BA and 16 pathways of JA both at horizontal and vertical levels. Besides a total of 60 overlapping functions as a robust integration background among the three groups based on significantly differential subnetworks, additive mechanism with strong confidence by networks altered functions. CONCLUSIONS These results provide strong evidence that the additive mechanism is more complex than previously appreciated, and an integrative analysis of pathways may suggest an important paradigm for revealing pharmacological mechanisms underlying drug combinations.
Collapse
Affiliation(s)
- Ying-Ying Zhang
- Institute of Basic Research in Clinical Medicine, China Academy of Chinese Medical Sciences, Beijing, China
| | | | | | | | | | | | | | | | | |
Collapse
|
164
|
Maury JJP, Ng D, Bi X, Bardor M, Choo ABH. Multiple Reaction Monitoring Mass Spectrometry for the Discovery and Quantification of O-GlcNAc-Modified Proteins. Anal Chem 2013; 86:395-402. [DOI: 10.1021/ac401821d] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Julien Jean Pierre Maury
- Bioprocessing
Technology Institute, Agency for Science, Technology and Research (A*STAR), 20 Biopolis Way, #06-01 Centros, Singapore 138668
- Department
of Bioengineering, Faculty of Engineering, National University of Singapore, Singapore 119077
| | - Daniel Ng
- Bioprocessing
Technology Institute, Agency for Science, Technology and Research (A*STAR), 20 Biopolis Way, #06-01 Centros, Singapore 138668
| | - Xuezhi Bi
- Bioprocessing
Technology Institute, Agency for Science, Technology and Research (A*STAR), 20 Biopolis Way, #06-01 Centros, Singapore 138668
| | - Muriel Bardor
- Bioprocessing
Technology Institute, Agency for Science, Technology and Research (A*STAR), 20 Biopolis Way, #06-01 Centros, Singapore 138668
- Université de Rouen, Laboratoire Glycobiologie et Matrice
Extracellulaire Végétale (Glyco-MEV) EA 4358, Institut
de Recherche et d’Innovation Biomédicale (IRIB), Faculté
des Sciences et Techniques, 76821 Mont-Saint-Aignan Cédex, France
| | - Andre Boon-Hwa Choo
- Bioprocessing
Technology Institute, Agency for Science, Technology and Research (A*STAR), 20 Biopolis Way, #06-01 Centros, Singapore 138668
- Department
of Bioengineering, Faculty of Engineering, National University of Singapore, Singapore 119077
| |
Collapse
|
165
|
Discovery and confirmation of O-GlcNAcylated proteins in rat liver mitochondria by combination of mass spectrometry and immunological methods. PLoS One 2013; 8:e76399. [PMID: 24098488 PMCID: PMC3788734 DOI: 10.1371/journal.pone.0076399] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 08/30/2013] [Indexed: 01/08/2023] Open
Abstract
O-linked β-N-acetylglucosamine (O-GlcNAc) is an important post-translational modification (PTM) consisting of a single N-acetylglucosamine moiety attached via an O-β-glycosidic linkage to serine and threonine residues. Glycosylation with O-GlcNAc occurs on myriad nuclear and cytosolic proteins from almost all functional classes. However, with respect to O-GlcNAcylated proteins special in mitochondria, little attention has been paid. In this study, we combined mass spectrometry and immunological methods to perform global exploration of O-GlcNAcylated proteins specific in mitochondria of rat liver. First, highly purified mitochondrial proteins were obviously shown to be O-GlcNAcylated by immunoblot profiling. Then, β-elimination followed by Michael Addition with Dithiothreitol (BEMAD) treatment and LC-MS/MS were performed to enrich and identify O-GlcNAcylated mitochondrial proteins, resulting in an unambiguous assignment of 14 O-GlcNAcylation sites, mapping to 11 O-GlcNAcylated proteins. Furthermore, the identified O-GlcNAcylated mitochondrial proteins were fully validated by both electron transfer dissociation tandem mass spectrometry (ETD/MS/MS) and western blot. Thus, for the first time, our study definitely not only identified but also validated that some mitochondrial proteins in rat liver are O-GlcNAcylated. Interestingly, all of these O-GlcNAcylated mitochondrial proteins are enzymes, the majority of which are involved in a wide variety of biological processes, such as urea cycle, tricarboxylic acid cycle and lipid metabolism, indicating a role for protein O-GlcNAcylation in mitochondrial function.
Collapse
|
166
|
Streptavidin–biotin technology: improvements and innovations in chemical and biological applications. Appl Microbiol Biotechnol 2013; 97:9343-53. [DOI: 10.1007/s00253-013-5232-z] [Citation(s) in RCA: 238] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 08/29/2013] [Accepted: 09/02/2013] [Indexed: 12/25/2022]
|
167
|
Iqbal K, Gong CX, Liu F. Hyperphosphorylation-induced tau oligomers. Front Neurol 2013; 4:112. [PMID: 23966973 PMCID: PMC3744035 DOI: 10.3389/fneur.2013.00112] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Accepted: 07/23/2013] [Indexed: 11/13/2022] Open
Abstract
In normal adult brain the microtubule associated protein (MAP) tau contains 2-3 phosphates per mol of the protein and at this level of phosphorylation it is a soluble cytosolic protein. The normal brain tau interacts with tubulin and promotes its assembly into microtubules and stabilizes these fibrils. In Alzheimer disease (AD) brain tau is three to fourfold hyperphosphorylated. The abnormally hyperphosphorylated tau binds to normal tau instead of the tubulin and this binding leads to the formation of tau oligomers. The tau oligomers can be sedimented at 200,000 × g whereas the normal tau under these conditions remains in the supernatant. The abnormally hyperphosphorylated tau is capable of sequestering not only normal tau but also MAP MAP1 and MAP2 and causing disruption of the microtubule network promoted by these proteins. Unlike Aβ and prion protein (PrP) oligomers, tau oligomerization in AD and related tauopathies is hyperphosphorylation-dependent; in vitro dephosphorylation of AD P-tau with protein phosphatase 2A (PP2A) inhibits and rehyperphosphorylation of the PP2A-AD P-tau with more than one combination of tau protein kinases promotes its oligomerization. In physiological assembly conditions the AD P-tau readily self-assembles into paired helical filaments. Missense tau mutations found in frontotemporal dementia apparently lead to tau oligomerization and neurofibrillary pathology by promoting its abnormal hyperphosphorylation. Dysregulation of the alternative splicing of tau that alters the 1:1 ratio of the 3-repeat: 4-repeat taus such as in Down syndrome, Pick disease, and progressive supranuclear palsy leads to the abnormal hyperphosphorylation of tau.
Collapse
Affiliation(s)
- Khalid Iqbal
- Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities , Staten Island, NY , USA
| | | | | |
Collapse
|
168
|
Copeland RJ, Han G, Hart GW. O-GlcNAcomics--Revealing roles of O-GlcNAcylation in disease mechanisms and development of potential diagnostics. Proteomics Clin Appl 2013; 7:597-606. [PMID: 23640805 DOI: 10.1002/prca.201300001] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Accepted: 01/17/2013] [Indexed: 12/26/2022]
Abstract
O-linked-β-N-acetylglucosamine (O-GlcNAc) is a dynamic PTM of the 3'-hydroxyl groups of serine or threonine residues of nuclear, cytoplasmic, and mitochondrial proteins. The cycling of this modification is regulated in response to nutrients, stress, and other extracellular stimuli by the catalytic activities of O-GlcNAc transferase and O-GlcNAcase. O-GlcNAc is functionally similar to phosphorylation and has been demonstrated to play critical roles in numerous biological processes, including cell signaling, transcription, and disease etiology. Since its discovery nearly 30 years ago, studies have demonstrated that the O-GlcNAc is highly abundant and widespread, like phosphorylation however, the development of methodologies to study O-GlcNAc at the site level has been challenging. Recently, a number of studies have overcome these challenges and describe new tagging, enrichment, and mass spectrometric-based approaches to study O-GlcNAc in terms of its site identification, stoichiometry, and dynamics on proteins. The development of these methods are key for elucidation of O-GlcNAc's functional crosstalk with phosphorylation and other PTMs, and will serve to provide the necessary information for the development of site-specific antibodies, which will aid in the determination of a particular protein's site-specific function. In this review, we describe these methods and summarize results obtained from them demonstrating the roles of O-GlcNAc in diabetes, cancer, Alzheimer's, and in learning and memory, while also describing how these new strategies have implicated O-GlcNAc as a potential diagnostic for the screening of patients for prediabetes.
Collapse
Affiliation(s)
- Ronald J Copeland
- Department of Biological Chemistry, School of Medicine, Johns Hopkins University, Baltimore, MD 21205-2185, USA
| | - Guanghui Han
- Department of Biological Chemistry, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Gerald W Hart
- Department of Biological Chemistry, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
| |
Collapse
|
169
|
Tang C, Welty DF. A dynamic view to the modulation of phosphorylation and O-GlcNAcylation by inhibition of O-GlcNAcase. Comput Biol Chem 2013; 45:9-16. [DOI: 10.1016/j.compbiolchem.2013.03.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Revised: 03/05/2013] [Accepted: 03/11/2013] [Indexed: 12/31/2022]
|
170
|
Cecioni S, Vocadlo DJ. Tools for probing and perturbing O-GlcNAc in cells and in vivo. Curr Opin Chem Biol 2013; 17:719-28. [PMID: 23906602 DOI: 10.1016/j.cbpa.2013.06.030] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Revised: 06/20/2013] [Accepted: 06/26/2013] [Indexed: 02/06/2023]
Abstract
Intracellular glycosylation of nuclear and cytoplasmic proteins involves the addition of N-acetylglucosamine (O-GlcNAc) to serine and threonine residues. This dynamic modification occurs on hundreds of proteins and is involved in various essential biological processes. Because O-GlcNAc is substoichiometric and labile, identifying proteins and sites of modification has been challenging and generally requires proteome enrichment. Here we review recent advances on the implementation of chemical tools to perturb, to detect, and to map O-GlcNAc in living systems. Metabolic and chemoenzymatic labels along with bioorthogonal reactions and quantitative proteomics are enabling investigation of the role of O-GlcNAc in various processes including transcriptional regulation, neurodegeneration, and cell signaling.
Collapse
Affiliation(s)
- Samy Cecioni
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | | |
Collapse
|
171
|
Mihailović M, Arambašić J, Uskoković A, Dinić S, Grdović N, Marković J, Bauder J, Poznanović G, Vidaković M. β-Glucan administration to diabetic rats alleviates oxidative stress by lowering hyperglycaemia, decreasing non-enzymatic glycation and protein O-GlcNAcylation. J Funct Foods 2013. [DOI: 10.1016/j.jff.2013.04.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
|
172
|
Dennis MD, Shenberger JS, Stanley BA, Kimball SR, Jefferson LS. Hyperglycemia mediates a shift from cap-dependent to cap-independent translation via a 4E-BP1-dependent mechanism. Diabetes 2013; 62:2204-14. [PMID: 23434932 PMCID: PMC3712054 DOI: 10.2337/db12-1453] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Diabetes and its associated hyperglycemia induce multiple changes in liver function, yet we know little about the role played by translational control of gene expression in mediating the responses to these conditions. Here, we evaluate the hypothesis that hyperglycemia-induced O-GlcNAcylation of the translational regulatory protein 4E-BP1 alters hepatic gene expression through a process involving the selection of mRNA for translation. In both streptozotocin (STZ)-treated mice and cells in culture exposed to hyperglycemic conditions, expression of 4E-BP1 and its interaction with the mRNA cap-binding protein eIF4E were enhanced in conjunction with downregulation of cap-dependent and concomitant upregulation of cap-independent mRNA translation, as assessed by a bicistronic luciferase reporter assay. Phlorizin treatment of STZ-treated mice lowered blood glucose concentrations and reduced activity of the cap-independent reporter. Notably, the glucose-induced shift from cap-dependent to cap-independent mRNA translation did not occur in cells lacking 4E-BP1. The extensive nature of this shift in translational control of gene expression was revealed using pulsed stable isotope labeling by amino acids in cell culture to identify proteins that undergo altered rates of synthesis in response to hyperglycemia. Taken together, these data provide evidence for a novel mechanism whereby O-GlcNAcylation of 4E-BP1 mediates translational control of hepatic gene expression.
Collapse
Affiliation(s)
- Michael D. Dennis
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania; the
| | - Jeffrey S. Shenberger
- Department of Pediatrics, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania; and the
| | - Bruce A. Stanley
- Department of Microbiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania
| | - Scot R. Kimball
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania; the
- Corresponding author: Scot R. Kimball,
| | - Leonard S. Jefferson
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania; the
| |
Collapse
|
173
|
A correlation between altered O-GlcNAcylation, migration and with changes in E-cadherin levels in ovarian cancer cells. Exp Cell Res 2013; 319:1482-90. [DOI: 10.1016/j.yexcr.2013.03.013] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2012] [Revised: 03/05/2013] [Accepted: 03/09/2013] [Indexed: 01/17/2023]
|
174
|
Perez-Cervera Y, Dehennaut V, Aquino Gil M, Guedri K, Solórzano Mata CJ, Olivier-Van Stichelen S, Michalski JC, Foulquier F, Lefebvre T. Insulin signaling controls the expression of O-GlcNAc transferase and its interaction with lipid microdomains. FASEB J 2013; 27:3478-86. [PMID: 23689613 DOI: 10.1096/fj.12-217984] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Lipid microdomains (rafts) are cholesterol-enriched dynamic ordered lipid domains belonging to cell membranes involved in diverse cellular functions, including signal transduction, membrane trafficking, and infection. Many studies have reported relationships between insulin signaling and lipid rafts. Likewise, links between insulin signaling and O-GlcNAcylation have also been described. However, the potential connection between O-GlcNAc and raft dynamics remains unexplored. Here we show that O-GlcNAc and the enzyme that creates this modification, O-GlcNAc transferase (OGT), are localized in rafts. On insulin stimulation, we observe time-dependent increases in OGT expression and localization within rafts. We show that these processes depend on activation of the phosphatidylinositol 3-kinase (PI3K) pathway. Inhibition of OGT does not significantly affect cholesterol synthesis and raft building but decreases insulin receptor expression and PI3K and mitogen-activated protein kinase pathway activation. Taken together, these findings indicate that O-GlcNAcylation, lipid rafts, and signaling pathways are spatiotemporally coordinated to enable fundamental cellular functions.
Collapse
Affiliation(s)
- Yobana Perez-Cervera
- Centre National de la Recherche Scientifique (CNRS)–Unité Mixte de Recherche (UMR) 8576, Institut Fédératif de Recherche (IFR) 147, University of Lille 1, Villeneuve d'Ascq, France
| | | | | | | | | | | | | | | | | |
Collapse
|
175
|
Vidyalakshmi S, Ramamurthy V. Phosphoserines of the carboxy terminal domain of RNA polymerase II are involved in the interaction with transcription-associated proteins (TAPs). OMICS : A JOURNAL OF INTEGRATIVE BIOLOGY 2013; 17:130-135. [PMID: 23421907 DOI: 10.1089/omi.2012.0081] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Generation of productive transcripts of protein coding genes in eukaryotes is a complex, multistep process centrally controlled by the RNA polymerase II (Pol II) complex. The carboxy terminal domain (CTD) of the largest subunit of the enzyme is designed to be modified by differential phosphorylation, and plays a key role in orchestrating the multiple events of the process by interacting with a host of transcription-associated proteins (TAPs) at different stages. We analyzed, in silico, the role of serine phosphorylation of CTD in relation to molecular interaction between different TAPs and a representative part of the CTD repeat structure. Using molecular docking, we investigated eight different proteins involved in capping, elongation, splicing, 3' end cleavage, or polyadenylation functions during the transcription process. Among the different phosphorylated forms of CTD, the form found to have the most affinity for a particular protein was also the form that is predominant during that process, the only exception being the equally high affinity of S2PCTD to Spt4, although S5PCTD is the known active form during elongation. The unique phosphoserine of the CTD forms associated with the TAPs was an important participant in the association between both the molecules. These studies have also identified other residues of TAPs interacting with CTD which in previous studies have not been recognized as being functionally significant. These findings add to an emerging body of literature on the regulatory aspects of genomics and proteomics and thus, might catalyze future applications for discovery and translational omics science.
Collapse
|
176
|
Vella P, Scelfo A, Jammula S, Chiacchiera F, Williams K, Cuomo A, Roberto A, Christensen J, Bonaldi T, Helin K, Pasini D. Tet proteins connect the O-linked N-acetylglucosamine transferase Ogt to chromatin in embryonic stem cells. Mol Cell 2013; 49:645-56. [PMID: 23352454 DOI: 10.1016/j.molcel.2012.12.019] [Citation(s) in RCA: 258] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Revised: 11/09/2012] [Accepted: 12/20/2012] [Indexed: 01/04/2023]
Abstract
O-linked N-acetylglucosamine (O-GlcNAc) transferase (Ogt) activity is essential for embryonic stem cell (ESC) viability and mouse development. Ogt is present both in the cytoplasm and the nucleus of different cell types and catalyzes serine and threonine glycosylation. We have characterized the biochemical features of nuclear Ogt and identified the ten-eleven translocation (TET) proteins Tet1 and Tet2 as stable partners of Ogt in the nucleus of ESCs. We show at a genome-wide level that Ogt preferentially associates with Tet1 to genes promoters in close proximity of CpG-rich transcription start sites. These regions are characterized by low levels of DNA modification, suggesting a link between Tet1 and Ogt activities in regulating CpG island methylation. Finally, we show that Tet1 is required for binding of Ogt to chromatin affecting Tet1 activity. Taken together, our data characterize how O-GlcNAcylation is recruited to chromatin and interacts with the activity of 5-methylcytosine hydroxylases.
Collapse
Affiliation(s)
- Pietro Vella
- Department of Experimental Oncology, European Institute of Oncology, Via Adamello 16, 20139 Milan, Italy
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
177
|
Abstract
Carbohydrate response element binding protein (ChREBP) is a transcription factor activated by glucose that is highly expressed in liver, pancreatic β-cells, brown and white adipose tissues, and muscle. We reported that hepatic suppression of the Chrebp gene improves hepatic steatosis, glucose intolerance, and obesity in genetically obese mice. Moreover, we have studied the role of ChREBP with special reference to feedforward and feedback looping in liver and pancreatic β-cells. Recently, several groups reported that (1) glucose activates ChREBP-α transactivity and in turn ChREBP-α induces ChREBP-β on both transcriptional and translational levels in adipose tissues, and (2) ChREBP regulates glucose transporter type 4 mRNA levels, which may affect glucose uptake in adipose tissues. Moreover, in adipose tissues of obese patients, Chrebpb mRNA levels were much lower than those in lean subjects, while the levels were much higher in liver of obese patients than those in lean subjects. These findings suggest that Chrebpb mRNA levels are different in various tissues and probably in the stages of diabetes mellitus. Herein, we review recent progress in the study of ChREBP with special references to (1) the mechanisms regulating ChREBP transactivity (posttranslational modifications, intramolecular glucose sensing module, feedforward mechanism, and the feedback loop between ChREBP and its target genes), and (2) the role of ChREBP in liver, pancreatic islets and adipose tissues. Understanding the role of ChREBP in each tissue will provide important insight into the pathogenesis of metabolic syndrome.
Collapse
Affiliation(s)
- Katsumi Iizuka
- University Hospital Center for Nutritional Support and Infection Control, Gifu University, Gifu 501-1194, Japan.
| |
Collapse
|
178
|
Chen Y, Tian Z, Liang Z, Sun S, Dai CL, Lee MH, LaFerla FM, Grundke-Iqbal I, Iqbal K, Liu F, Gong CX. Brain gene expression of a sporadic (icv-STZ Mouse) and a familial mouse model (3xTg-AD mouse) of Alzheimer's disease. PLoS One 2012; 7:e51432. [PMID: 23236499 PMCID: PMC3517562 DOI: 10.1371/journal.pone.0051432] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Accepted: 11/01/2012] [Indexed: 12/28/2022] Open
Abstract
Alzheimer's disease (AD) can be divided into sporadic AD (SAD) and familial AD (FAD). Most AD cases are sporadic and may result from multiple etiologic factors, including environmental, genetic and metabolic factors, whereas FAD is caused by mutations of presenilins or amyloid-β (Aβ) precursor protein (APP). A commonly used mouse model for AD is 3xTg-AD mouse, which is generated by over-expression of mutated presenilin 1, APP and tau in the brain and thus represents a mouse model of FAD. A mouse model generated by intracerebroventricular (icv) administration of streptozocin (STZ), icv-STZ mouse, shows many aspects of SAD. Despite the wide use of these two models for AD research, differences in gene expression between them are not known. Here, we compared the expression of 84 AD-related genes in the hippocampus and the cerebral cortex between icv-STZ mice and 3xTg-AD mice using a custom-designed qPCR array. These genes are involved in APP processing, tau/cytoskeleton, synapse function, apoptosis and autophagy, AD-related protein kinases, glucose metabolism, insulin signaling, and mTOR pathway. We found altered expression of around 20 genes in both mouse models, which affected each of above categories. Many of these gene alterations were consistent with what was observed in AD brain previously. The expression of most of these altered genes was decreased or tended to be decreased in the hippocampus of both mouse models. Significant diversity in gene expression was found in the cerebral cortex between these two AD mouse models. More genes related to synaptic function were dysregulated in the 3xTg-AD mice, whereas more genes related to insulin signaling and glucose metabolism were down-regulated in the icv-STZ mice. The present study provides important fundamental knowledge of these two AD mouse models and will help guide future studies using these two mouse models for the development of AD drugs.
Collapse
Affiliation(s)
- Yanxing Chen
- Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, United States of America
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
179
|
Minguez P, Letunic I, Parca L, Bork P. PTMcode: a database of known and predicted functional associations between post-translational modifications in proteins. Nucleic Acids Res 2012. [PMID: 23193284 PMCID: PMC3531129 DOI: 10.1093/nar/gks1230] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Post-translational modifications (PTMs) are involved in the regulation and structural stabilization of eukaryotic proteins. The combination of individual PTM states is a key to modulate cellular functions as became evident in a few well-studied proteins. This combinatorial setting, dubbed the PTM code, has been proposed to be extended to whole proteomes in eukaryotes. Although we are still far from deciphering such a complex language, thousands of protein PTM sites are being mapped by high-throughput technologies, thus providing sufficient data for comparative analysis. PTMcode (http://ptmcode.embl.de) aims to compile known and predicted PTM associations to provide a framework that would enable hypothesis-driven experimental or computational analysis of various scales. In its first release, PTMcode provides PTM functional associations of 13 different PTM types within proteins in 8 eukaryotes. They are based on five evidence channels: a literature survey, residue co-evolution, structural proximity, PTMs at the same residue and location within PTM highly enriched protein regions (hotspots). PTMcode is presented as a protein-based searchable database with an interactive web interface providing the context of the co-regulation of nearly 75 000 residues in >10 000 proteins.
Collapse
Affiliation(s)
- Pablo Minguez
- European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | | | | | | |
Collapse
|
180
|
O-GlcNAcylation and oxidation of proteins: is signalling in the cardiovascular system becoming sweeter? Clin Sci (Lond) 2012; 123:473-86. [PMID: 22757958 PMCID: PMC3389386 DOI: 10.1042/cs20110638] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
O-GlcNAcylation is an unusual form of protein glycosylation, where a single-sugar [GlcNAc (N-acetylglucosamine)] is added (via β-attachment) to the hydroxyl moiety of serine and threonine residues of nuclear and cytoplasmic proteins. A complex and extensive interplay exists between O-GlcNAcylation and phosphorylation. Many phosphorylation sites are also known glycosylation sites, and this reciprocal occupancy may produce different activities or alter the stability in a target protein. The interplay between these two post-translational modifications is not always reciprocal, as some proteins can be concomitantly phosphorylated and O-GlcNAcylated, and the adjacent phosphorylation or O-GlcNAcylation can regulate the addition of either moiety. Increased cardiovascular production of ROS (reactive oxygen species), termed oxidative stress, has been consistently reported in various chronic diseases and in conditions where O-GlcNAcylation has been implicated as a contributing mechanism for the associated organ injury/protection (for example, diabetes, Alzheimer's disease, arterial hypertension, aging and ischaemia). In the present review, we will briefly comment on general aspects of O-GlcNAcylation and provide an overview of what has been reported for this post-translational modification in the cardiovascular system. We will then specifically address whether signalling molecules involved in redox signalling can be modified by O-GlcNAc (O-linked GlcNAc) and will discuss the critical interplay between O-GlcNAcylation and ROS generation. Experimental evidence indicates that the interactions between O-GlcNAcylation and oxidation of proteins are important not only for cell regulation in physiological conditions, but also under pathological states where the interplay may become dysfunctional and thereby exacerbate cellular injury.
Collapse
|
181
|
Bennett CE, Johnsen VL, Shearer J, Belke DD. Exercise training mitigates aberrant cardiac protein O-GlcNAcylation in streptozotocin-induced diabetic mice. Life Sci 2012; 92:657-63. [PMID: 23000101 DOI: 10.1016/j.lfs.2012.09.007] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2012] [Revised: 08/23/2012] [Accepted: 09/10/2012] [Indexed: 10/27/2022]
Abstract
AIMS Increased protein O-GlcNAcylation occurs in response to increased availability of glucose and fatty acids and is a hallmark of diabetes. Previous studies have demonstrated an improvement in heart function associated with decreased protein O-GlcNAcylation. Our group has recently demonstrated a capacity for exercise to decrease protein O-GlcNAcylation in the heart of normal mice; however, the impact of such training under diabetic conditions has not been examined. MAIN METHODS Diabetes was induced in mice through injection of streptozotocin. Animals either remained sedentary or were subjected to 6 weeks of swim training protocol. At the end of 6 weeks in vivo cardiac function was assessed and the hearts were harvested for gene expression and Western blotting in relation to O-GlcNAcylation KEY FINDINGS Diabetes resulted in elevated blood glucose relative to non-diabetic mice. Relative to the sedentary diabetic group, the rate of relaxation (Tau) was significantly improved in the exercised group. Western blot analysis revealed an increase in protein O-GlcNAcylation in the diabetic group which was reversed through exercise despite persistent hyperglycemia. No change in the expression of O-GlcNAc transferase (OGT) was noted between sedentary and exercised diabetic mice; however an increase in the expression and activity of O-GlcNAcase (OGA) was apparent in the exercised group. SIGNIFICANCE This study demonstrates the potential for exercise training to decrease intracellular protein O-GlcNAcylation in the heart even under conditions of persistent hyperglycemia associated with diabetes. Our results suggest the beneficial effects of regular aerobic exercise extend beyond simple regulation of blood glucose levels.
Collapse
Affiliation(s)
- Catherine E Bennett
- Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, Alberta, Canada T2N 1N4
| | | | | | | |
Collapse
|
182
|
Tvaroška I, Kozmon S, Wimmerová M, Koča J. Substrate-assisted catalytic mechanism of O-GlcNAc transferase discovered by quantum mechanics/molecular mechanics investigation. J Am Chem Soc 2012; 134:15563-71. [PMID: 22928765 DOI: 10.1021/ja307040m] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In higher eukaryotes, a variety of proteins are post-translationally modified by adding O-linked N-acetylglucosamine (GlcNAc) residue to serine or threonine residues. Misregulation of O-GlcNAcylation is linked to a wide variety of diseases, such as diabetes, cancer, and neurodegenerative diseases, including Alzheimer's disease. GlcNAc transfer is catalyzed by an inverting glycosyltransferase O-GlcNAc transferase (uridine diphospho-N-acetylglucosamine:polypeptide β-N-acetylaminyltransferase, OGT) that belongs to the GT-B superfamily. The catalytic mechanism of this metal-independent glycosyltransferase is of primary importance and is investigated here using QM(DFT)/MM methods. The structural model of the reaction site used in this paper is based on the crystal structures of OGT. The entire enzyme-substrate system was partitioned into two different subsystems: the QM subsystem containing 198 atoms, and the MM region containing 11,326 atoms. The catalytic mechanism was monitored by means of three two-dimensional potential energy maps calculated as a function of three predefined reaction coordinates at different levels of theory. These potential energy surfaces revealed the existence of a concerted S(N)2-like mechanism, in which a nucleophilic attack by O(Ser), facilitated by proton transfer to the catalytic base, and the dissociation of the leaving group occur almost simultaneously. The transition state for the proposed reaction mechanism at the MPW1K level was located at C1-O(Ser) = 1.92 Å and C1-O1 = 3.11 Å. The activation energy for this passage was estimated to be ~20 kcal mol(-1). These calculations also identified, for the first time for glycosyltransferases, the substrate-assisted mechanism in which the N-acetamino group of the donor participates in the catalytic mechanism.
Collapse
Affiliation(s)
- Igor Tvaroška
- Institute of Chemistry, Slovak Academy of Sciences, 845 38 Bratislava, Slovak Republic.
| | | | | | | |
Collapse
|
183
|
Drougat L, Olivier-Van Stichelen S, Mortuaire M, Foulquier F, Lacoste AS, Michalski JC, Lefebvre T, Vercoutter-Edouart AS. Characterization of O-GlcNAc cycling and proteomic identification of differentially O-GlcNAcylated proteins during G1/S transition. Biochim Biophys Acta Gen Subj 2012; 1820:1839-48. [PMID: 22967762 DOI: 10.1016/j.bbagen.2012.08.024] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Revised: 08/21/2012] [Accepted: 08/27/2012] [Indexed: 12/25/2022]
Abstract
BACKGROUND DNA replication represents a critical step of the cell cycle which requires highly controlled and ordered regulatory mechanisms to ensure the integrity of genome duplication. Among a plethora of elements, post-translational modifications (PTMs) ensure the spatiotemporal regulation of pivotal proteins orchestrating cell division. Despite increasing evidences showing that O-GlcNAcylation regulates mitotic events, the impact of this PTM in the early steps of the cell cycle remains poorly understood. METHODS AND RESULTS Quiescent MCF7 cells were stimulated by serum mitogens and cell cycle progression was determined by flow cytometry. The levels of O-GlcNAc modified proteins, O-GlcNAc Transferase (OGT) and O-GlcNAcase (OGA) were examined by Western blotting and OGA activity was measured during the progression of cells towards S phase. A global decrease in O-GlcNAcylation was observed at S phase entry, concomitantly to an increase in the activity of OGA. A combination of two-dimensional electrophoresis, Western blotting and mass spectrometry was then used to detect and identify cell cycle-dependent putative O-GlcNAcylated proteins. 58 cytoplasmic and nuclear proteins differentially O-GlcNAcylated through G1/S transition were identified and the O-GlcNAc variations of Cytokeratin 8, hnRNP K, Caprin-1, Minichromosome Maintenance proteins MCM3, MCM6 and MCM7 were validated by immunoprecipitation. CONCLUSIONS The dynamics of O-GlcNAc is regulated during G1/S transition and observed on key proteins involved in the cytoskeleton networks, mRNA processing, translation, protein folding and DNA replication. GENERAL SIGNIFICANCE Our results led us to propose that O-GlcNAcylation joins the PTMs that take part in the regulation of DNA replication initiation.
Collapse
Affiliation(s)
- Ludivine Drougat
- Université des Sciences et Technologies de Lille, Villeneuve d'Ascq, France
| | | | | | | | | | | | | | | |
Collapse
|
184
|
Abstract
The incidence of type 2 diabetes mellitus (T2DM) is rapidly increasing worldwide with significant consequences on individual quality of life as well as economic burden on states' healthcare costs. While origins of the pathogenesis of T2DM are poorly understood, an early defect in glucose-stimulated insulin secretion (GSIS) from pancreatic β-cells is considered a hallmark of T2DM. Upon a glucose stimulus, insulin is secreted in a biphasic manner with an early first-phase burst of insulin, which is followed by a second, more sustained phase of insulin output. First phase insulin secretion is diminished early in T2DM as well is in subjects who are at risk of developing T2DM. An effective treatment of T2DM with incretin hormone glucagon-like peptide-1 (GLP-1) or its long acting peptide analogue exendin-4 (E4), restores first-phase and augments second-phase glucose stimulated insulin secretion. This effect of incretin action occurs within minutes of GLP-1/E4 infusion in T2DM humans. An additional important consideration is that incretin hormones augment GSIS only above a certain glucose threshold, which is slightly above the normal glucose range. This ensures that incretin hormones stimulate GSIS only when glucose levels are high, while they are ineffective when insulin levels are below a certain threshold. Activation of the GLP-1 receptor, which is highly expressed on pancreatic β-cells, stimulates 2 -distinct intracellular signaling pathways: a) the cAMP-protein kinase A branch and b) the cAMP-EPAC2 (EPAC=exchange protein activated by cAMP) branch. While the EPAC2 branch is considered to mediate GLP-1 effects on first-phase GSIS, the PKA branch is necessary for the former branch to be active. However, how these 2 branches interplay and converge and how their effects on insulin secretion and insulin vesicle exocytosis are coordinated is poorly understood.Thus, at the outset of our studies we have a poorly understood intracellular interplay of cAMP-dependent signaling pathways, which - when stimulated - restore glucose-dependent first phase and augment second phase insulin secretion in the ailing β-cells of T2DM.
Collapse
Affiliation(s)
- M A Hussain
- Department of Pediatrics, Medicine and Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
| | | | | |
Collapse
|
185
|
Liu Y, Li X, Yu Y, Shi J, Liang Z, Run X, Li Y, Dai CL, Grundke-Iqbal I, Iqbal K, Liu F, Gong CX. Developmental regulation of protein O-GlcNAcylation, O-GlcNAc transferase, and O-GlcNAcase in mammalian brain. PLoS One 2012; 7:e43724. [PMID: 22928023 PMCID: PMC3425547 DOI: 10.1371/journal.pone.0043724] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Accepted: 07/24/2012] [Indexed: 12/18/2022] Open
Abstract
O-GlcNAcylation is a common posttranslational modification of nucleocytoplasmic proteins by β-N-acetylglucosamine (GlcNAc). The dynamic addition and removal of O-GlcNAc groups to and from proteins are catalyzed by O-linked N-acetylglucosamine transferase (O-GlcNAc transferase, OGT) and β-N-acetylglucosaminidase (O-GlcNAcase, OGA), respectively. O-GlcNAcylation often modulates protein phosphorylation and regulates several cellular signaling and functions, especially in the brain. However, its developmental regulation is not well known. Here, we studied protein O-GlcNAcylation, OGT, and OGA in the rat brain at various ages from embryonic day 15 to the age of 2 years. We found a gradual decline of global protein O-GlcNAcylation during developmental stages and adulthood. This decline correlated positively to the total protein phosphorylation at serine residues, but not at threonine residues. The expression of OGT and OGA isoforms was regulated differently at various ages. Immunohistochemical studies revealed ubiquitous distribution of O-GlcNAcylation at all ages. Strong immunostaining of O-GlcNAc, OGT, and OGA was observed mostly in neuronal cell bodies and processes, further suggesting the role of O-GlcNAc modification of neuronal proteins in the brain. These studies provide fundamental knowledge of age-dependent protein modification by O-GlcNAc and will help guide future studies on the role of O-GlcNAcylation in the mammalian brain.
Collapse
Affiliation(s)
- Ying Liu
- Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, United States of America
| | - Xiaojing Li
- Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, United States of America
| | - Yang Yu
- Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, United States of America
| | - Jianhua Shi
- Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, United States of America
- Jiangsu Key Laboratory of Neuroregeneration, Nantong University, Nantong, Jiangsu, China
| | - Zhihou Liang
- Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, United States of America
| | - Xiaoqin Run
- Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, United States of America
| | - Yi Li
- Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, United States of America
| | - Chun-ling Dai
- Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, United States of America
| | - Inge Grundke-Iqbal
- Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, United States of America
| | - Khalid Iqbal
- Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, United States of America
| | - Fei Liu
- Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, United States of America
- Jiangsu Key Laboratory of Neuroregeneration, Nantong University, Nantong, Jiangsu, China
| | - Cheng-Xin Gong
- Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, United States of America
- * E-mail:
| |
Collapse
|
186
|
Ruan HB, Han X, Li MD, Singh JP, Qian K, Azarhoush S, Zhao L, Bennett AM, Samuel VT, Wu J, Yates JR, Yang X. O-GlcNAc transferase/host cell factor C1 complex regulates gluconeogenesis by modulating PGC-1α stability. Cell Metab 2012; 16:226-37. [PMID: 22883232 PMCID: PMC3480732 DOI: 10.1016/j.cmet.2012.07.006] [Citation(s) in RCA: 226] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Revised: 03/21/2012] [Accepted: 07/11/2012] [Indexed: 01/01/2023]
Abstract
A major cause of hyperglycemia in diabetic patients is inappropriate hepatic gluconeogenesis. PGC-1α is a master regulator of gluconeogenesis, and its activity is controlled by various posttranslational modifications. A small portion of glucose metabolizes through the hexosamine biosynthetic pathway, which leads to O-linked β-N-acetylglucosamine (O-GlcNAc) modification of cytoplasmic and nuclear proteins. Using a proteomic approach, we identified a broad variety of proteins associated with O-GlcNAc transferase (OGT), among which host cell factor C1 (HCF-1) is highly abundant. HCF-1 recruits OGT to O-GlcNAcylate PGC-1α, and O-GlcNAcylation facilitates the binding of the deubiquitinase BAP1, thus protecting PGC-1α from degradation and promoting gluconeogenesis. Glucose availability modulates gluconeogenesis through the regulation of PGC-1α O-GlcNAcylation and stability by the OGT/HCF-1 complex. Hepatic knockdown of OGT and HCF-1 improves glucose homeostasis in diabetic mice. These findings define the OGT/HCF-1 complex as a glucose sensor and key regulator of gluconeogenesis, shedding light on new strategies for treating diabetes.
Collapse
Affiliation(s)
- 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
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
187
|
Molesini B, Pandolfini T, Pii Y, Korte A, Spena A. Arabidopsis thaliana AUCSIA-1 regulates auxin biology and physically interacts with a kinesin-related protein. PLoS One 2012; 7:e41327. [PMID: 22911780 PMCID: PMC3401106 DOI: 10.1371/journal.pone.0041327] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Accepted: 06/25/2012] [Indexed: 12/22/2022] Open
Abstract
Aucsia is a green plant gene family encoding 44–54 amino acids long miniproteins. The sequenced genomes of most land plants contain two Aucsia genes. RNA interference of both tomato (Solanum lycopersicum) Aucsia genes (SlAucsia-1 and SlAucsia-2) altered auxin sensitivity, auxin transport and distribution; it caused parthenocarpic development of the fruit and other auxin-related morphological changes. Here we present data showing that the Aucsia-1 gene of Arabidopsis thaliana alters, by itself, root auxin biology and that the AtAUCSIA-1 miniprotein physically interacts with a kinesin-related protein. The AtAucsia-1 gene is ubiquitously expressed, although its expression is higher in roots and inflorescences in comparison to stems and leaves. Two allelic mutants for AtAucsia-1 gene did not display visible root morphological alterations; however both basipetal and acropetal indole-3-acetic acid (IAA) root transport was reduced as compared with wild-type plants. The transcript steady state levels of the auxin efflux transporters ATP BINDING CASSETTE subfamily B (ABCB) ABCB1, ABCB4 and ABCB19 were reduced in ataucsia-1 plants. In ataucsia-1 mutant, lateral root growth showed an altered response to i) exogenous auxin, ii) an inhibitor of polar auxin transport and iii) ethylene. Overexpression of AtAucsia-1 inhibited primary root growth. In vitro and in vivo protein-protein interaction experiments showed that AtAUCSIA-1 interacts with a 185 amino acids long fragment belonging to a 2712 amino acids long protein of unknown function (At4g31570). Bioinformatics analysis indicates that the AtAUCSIA-1 interacting protein (AtAUCSIA-1IP) clusters with a group of CENP-E kinesin-related proteins. Gene ontology predictions for the two proteins are consistent with the hypothesis that the AtAUCSIA-1/AtAUCSIA-1IP complex is involved in the regulation of the cytoskeleton dynamics underlying auxin biology.
Collapse
Affiliation(s)
- Barbara Molesini
- Department of Biotechnology, University of Verona, Verona, Italy
| | | | - Youry Pii
- Department of Biotechnology, University of Verona, Verona, Italy
| | - Arthur Korte
- WissenschaftZentrum WeihenstephanTechnische Universitaet Muenchen, Freising, Germany
| | - Angelo Spena
- Department of Biotechnology, University of Verona, Verona, Italy
- * E-mail:
| |
Collapse
|
188
|
Hilgers RHP, Xing D, Gong K, Chen YF, Chatham JC, Oparil S. Acute O-GlcNAcylation prevents inflammation-induced vascular dysfunction. Am J Physiol Heart Circ Physiol 2012; 303:H513-22. [PMID: 22777418 DOI: 10.1152/ajpheart.01175.2011] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Acute increases in cellular protein O-linked N-acetyl-glucosamine (O-GlcNAc) modification (O-GlcNAcylation) have been shown to have protective effects in the heart and vasculature. We hypothesized that d-glucosamine (d-GlcN) and Thiamet-G, two agents that increase protein O-GlcNAcylation via different mechanisms, inhibit TNF-α-induced oxidative stress and vascular dysfunction by suppressing inducible nitric oxide (NO) synthase (iNOS) expression. Rat aortic rings were incubated for 3h at 37°C with d-GlcN or its osmotic control l-glucose (l-Glc) or with Thiamet-G or its vehicle control (H(2)O) followed by the addition of TNF-α or vehicle (H(2)O) for 21 h. After incubation, rings were mounted in a myograph to assess arterial reactivity. Twenty-four hours of incubation of aortic rings with TNF-α resulted in 1) a hypocontractility to 60 mM K(+) solution and phenylephrine, 2) blunted endothelium-dependent relaxation responses to ACh and substance P, and 3) unaltered relaxing response to the Ca(2+) ionophore A-23187 and the NO donor sodium nitroprusside compared with aortic rings cultured in the absence of TNF-α. d-GlcN and Thiamet-G pretreatment suppressed the TNF-α-induced hypocontractility and endothelial dysfunction. Total protein O-GlcNAc levels were significantly higher in aortic segments treated with d-GlcN or Thiamet-G compared with controls. Expression of iNOS protein was increased in TNF-α-treated rings, and this was attenuated by pretreatment with either d-GlcN or Thiamet-G. Dense immunostaining for nitrotyrosylated proteins was detected in the endothelium and media of the aortic wall, suggesting enhanced peroxynitrite production by iNOS. These findings demonstrate that acute increases in protein O-GlcNAcylation prevent TNF-α-induced vascular dysfunction, at least in part, via suppression of iNOS expression.
Collapse
Affiliation(s)
- Rob H P Hilgers
- Vascular Biology and Hypertension Program, Division of Cardiovascular Disease, Department of Medicine, University of Alabama, Birmingham, Alabama 35294-0007, USA
| | | | | | | | | | | |
Collapse
|
189
|
Jang H, Kim TW, Yoon S, Choi SY, Kang TW, Kim SY, Kwon YW, Cho EJ, Youn HD. O-GlcNAc regulates pluripotency and reprogramming by directly acting on core components of the pluripotency network. Cell Stem Cell 2012; 11:62-74. [PMID: 22608532 DOI: 10.1016/j.stem.2012.03.001] [Citation(s) in RCA: 240] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Revised: 01/20/2012] [Accepted: 03/01/2012] [Indexed: 01/03/2023]
Abstract
O-linked-N-acetylglucosamine (O-GlcNAc) has emerged as a critical regulator of diverse cellular processes, but its role in embryonic stem cells (ESCs) and pluripotency has not been investigated. Here we show that O-GlcNAcylation directly regulates core components of the pluripotency network. Blocking O-GlcNAcylation disrupts ESC self-renewal and reprogramming of somatic cells to induced pluripotent stem cells. The core reprogramming factors Oct4 and Sox2 are O-GlcNAcylated in ESCs, but the O-GlcNAc modification is rapidly removed upon differentiation. O-GlcNAc modification of threonine 228 in Oct4 regulates Oct4 transcriptional activity and is important for inducing many pluripotency-related genes, including Klf2, Klf5, Nr5a2, Tbx3, and Tcl1. A T228A point mutation that eliminates this O-GlcNAc modification reduces the capacity of Oct4 to maintain ESC self-renewal and reprogram somatic cells. Overall, our study makes a direct connection between O-GlcNAcylation of key regulatory transcription factors and the activity of the pluripotency network.
Collapse
Affiliation(s)
- Hyonchol Jang
- National Research Laboratory for Metabolic Checkpoint, Departments of Biomedical Sciences and Biochemistry and Molecular Biology, Seoul National University College of Medicine, Seoul 110-799, Republic of Korea
| | | | | | | | | | | | | | | | | |
Collapse
|
190
|
Miura Y, Sakurai Y, Endo T. O-GlcNAc modification affects the ATM-mediated DNA damage response. Biochim Biophys Acta Gen Subj 2012; 1820:1678-85. [PMID: 22759405 DOI: 10.1016/j.bbagen.2012.06.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Revised: 06/19/2012] [Accepted: 06/20/2012] [Indexed: 11/16/2022]
Abstract
BACKGROUND O-Linked β-N-acetylglucosamine (O-GlcNAc) is a reversible, post-translational, and regulatory modification of nuclear, mitochondrial, and cytoplasmic proteins that is responsive to cellular stress. The role of O-GlcNAcylation in the ataxia-telangiectasia mutated (ATM)-mediated DNA damage response is unknown. It is unclear whether ATM, which is an early acting and central component of the signal transduction system activated by DNA double strand breaks, is an O-GlcNAc-modified protein. METHODS The effect of O-GlcNAc modification on ATM activation was examined using two inhibitors, PUGNAc and DON that increase and decrease, respectively, levels of protein O-GlcNAcylation. To assess O-GlcNAcylation of ATM, immunoprecipitation and immunoblot analyses using anti-ATM or anti-O-GlcNAc antibody were performed in HeLa cells and primary cultured neurons. Interaction of ATM with O-GlcNAc transferase (OGT), the enzyme that adds O-GlcNAc to target proteins, was examined by immunoprecipitation and immunoblot analyses using anti-ATM. RESULTS Enhancement of protein O-GlcNAcylation increased levels of X-irradiation-induced ATM activation. However, decreases in protein O-GlcNAcylation did not affect levels of ATM activation, but these decreases did delay ATM activation and ATM recovery processes based on assessment of de-phosphorylation of phospho-ATM. Thus, activation and recovery of ATM were affected by O-GlcNAcylation. ATM was subjected to O-GlcNAcylation, and ATM interacted with OGT. The steady-state O-GlcNAc level of ATM was not significantly responsive to X-irradiation or oxidative stress. GENERAL SIGNIFICANCE ATM is an O-GlcNAc modified protein, and dynamic O-GlcNAc modification affects the ATM-mediated DNA damage response.
Collapse
Affiliation(s)
- Yuri Miura
- Research Team for Mechanism of Aging, Tokyo Metropolitan Institute of Gerontology, Tokyo 173-0015, Japan.
| | | | | |
Collapse
|
191
|
Identification of kinases regulating prostate cancer cell growth using an RNAi phenotypic screen. PLoS One 2012; 7:e38950. [PMID: 22761715 PMCID: PMC3384611 DOI: 10.1371/journal.pone.0038950] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Accepted: 05/15/2012] [Indexed: 01/10/2023] Open
Abstract
As prostate cancer progresses to castration-resistant disease, there is an increase in signal transduction activity. Most castration-resistant prostate tumors continue to express the androgen receptor (AR) as well as androgen-responsive genes, despite the near absence of circulating androgen in these patients. The AR is regulated not only by its cognate steroid hormone, but also by interactions with a constellation of co-regulatory and signaling molecules. Thus, the elevated signaling activity that occurs during progression to castration resistance can affect prostate cancer cell growth either through the AR or independent of the AR. In order to identify signaling pathways that regulate prostate cancer cell growth, we screened a panel of shRNAs targeting 673 human kinases against LNCaP prostate cancer cells grown in the presence and absence of hormone. The screen identified multiple shRNA clones against known and novel gene targets that regulate prostate cancer cell growth. Based on the magnitude of effect on growth, we selected six kinases for further study: MAP3K11, DGKD, ICK, CIT, GALK2, and PSKH1. Knockdown of these kinases decreased cell growth in both androgen-dependent and castration-resistant prostate cancer cells. However, these kinases had different effects on basal or androgen-induced transcriptional activity of AR target genes. MAP3K11 knockdown most consistently altered transcription of AR target genes, suggesting that MAP3K11 affected its growth inhibitory effect by modulating the AR transcriptional program. Consistent with MAP3K11 acting on the AR, knockdown of MAP3K11 inhibited AR Ser 650 phosphorylation, further supporting stress kinase regulation of AR phosphorylation. This study demonstrates the applicability of lentiviral-based shRNA for conducting phenotypic screens and identifies MAP3K11, DGKD, ICK, CIT, GALK2, and PSKH1 as regulators of prostate cancer cell growth. The thorough evaluation of these kinase targets will pave the way for developing more effective treatments for castration-resistant prostate cancer.
Collapse
|
192
|
Qiao Z, Dang C, Zhou B, Li S, Zhang W, Jiang J, Zhang J, Kong R, Ma Y. O-linked N-acetylglucosamine transferase (OGT) is overexpressed and promotes O-linked protein glycosylation in esophageal squamous cell carcinoma. J Biomed Res 2012; 26:268-73. [PMID: 23554759 PMCID: PMC3596743 DOI: 10.7555/jbr.26.20110121] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2011] [Revised: 11/09/2011] [Accepted: 03/24/2012] [Indexed: 11/03/2022] Open
Abstract
The aim of this present study was to explore the expression and clinical significance of O-linked N-acetylglucosamine (O-GlcNAc) transferase (OGT) and enzymatic O-linked glycosylation (O-GlcNAcation) through the addition of O-linked-β-N-acetylglucosamine in esophageal squamous cell carcinoma. OGT expression and O-GlcNAcation in 40 samples from patients with esophageal squamous cell carcinoma was detected by immunohistochemical staining with anti-OGT antib ody and O-GlcNAc-specific antibody RL2, respectively. The relationship between pathological and clinical factors of patients was analyzed. We found that the expression of OGT was higher in esophageal squamous cell carcinoma samples compared to the normal tissues. RL2 antibody level was positively correlated with OGT expression, and the metastasis of lymph node, which means the level of O-GlcNAcation was high and related to the metastasis of lymph node in esophageal squamous cell carcinoma. In conclusion, OGT activation is the main reason for promoting the level of O-GlcNAcation in esophageal squamous cell carcinoma. O-GlcNAcylation may play an important role in esophageal squamous cell carcinoma.
Collapse
Affiliation(s)
- Zhe Qiao
- Department of Thoracic Surgery, the Second Affiliated Hospital, Xi'an Jiaotong University, Xi'an, Shaanxi 710004, China
| | | | | | | | | | | | | | | | | |
Collapse
|
193
|
Yehezkel G, Cohen L, Kliger A, Manor E, Khalaila I. O-linked β-N-acetylglucosaminylation (O-GlcNAcylation) in primary and metastatic colorectal cancer clones and effect of N-acetyl-β-D-glucosaminidase silencing on cell phenotype and transcriptome. J Biol Chem 2012; 287:28755-69. [PMID: 22730328 DOI: 10.1074/jbc.m112.345546] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
O-linked β-N-acetylglucosamine (O-GlcNAc) glycosylation is a regulatory post-translational modification occurring on the serine or threonine residues of nucleocytoplasmic proteins. O-GlcNAcylation is dynamically regulated by O-GlcNAc transferase and O-GlcNAcase (OGA), which are responsible for O-GlcNAc addition and removal, respectively. Although O-GlcNAcylation was found to play a significant role in several pathologies such as type II diabetes and neurodegenerative diseases, the role of O-GlcNAcylation in the etiology and progression of cancer remains vague. Here, we followed O-GlcNAcylation and its catalytic machinery in metastatic clones of human colorectal cancer and the effect of OGA knockdown on cellular phenotype and on the transcriptome. The colorectal cancer SW620 metastatic clone exhibited increased O-GlcNAcylation and decreased OGA expression compared with its primary clone, SW480. O-GlcNAcylation elevation in SW620 cells, through RNA interference of OGA, resulted in phenotypic alterations that included acquisition of a fibroblast-like morphology, which coincides with epithelial metastatic progression and growth retardation. Microarray analysis revealed that OGA silencing altered the expression of about 1300 genes, mostly involved in cell movement and growth, and specifically affected metabolic pathways of lipids and carbohydrates. These findings support the involvement of O-GlcNAcylation in various aspects of tumor cell physiology and suggest that this modification may serve as a link between metabolic changes and cancer.
Collapse
Affiliation(s)
- Galit Yehezkel
- Faculty of Engineering Sciences, The Avram and Stella Goldstein-Goren Department of Biotechnology Engineering, Ben-Gurion University of the Negev, P. O. Box 653, Beer-Sheva 84105, Israel
| | | | | | | | | |
Collapse
|
194
|
Nakamura S, Nakano S, Nishii M, Kaneko S, Kusaka H. Localization of O-GlcNAc-modified proteins in neuromuscular diseases. Med Mol Morphol 2012; 45:86-90. [PMID: 22718293 DOI: 10.1007/s00795-011-0542-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Accepted: 02/18/2011] [Indexed: 10/28/2022]
Abstract
O-linked N-acetylglucosamine (O-GlcNAc) is a ubiquitous post-translational modification of nucleocytoplasmic proteins that induces the attachment of N-acetylglucosamine to serine or threonine residues of a protein. In contrast to other protein glycosylations, this modification is highly reversible and, similar to phosphorylation, it plays important roles in various cell signals. Here, we immunolocalized O-GlcNAc-modified proteins in muscle biopsy specimens from 40 patients with neuromuscular diseases and controls. In normal muscle fibers, O-GlcNAc was found along plasma membranes and in nuclei. Diffuse and increased cytoplasmic staining of O-GlcNAc was detected in (1) regenerating muscle fibers in muscular dystrophy, myositis, and rhabdomyolysis; (2) a proportion of atrophic fibers in myositis, such as those found in perifascicular regions in dermatomyositis; and (3) vacuolated fibers in sporadic inclusion body myositis (s-IBM) and distal myopathy with rimmed vacuoles (DMRV). Target formations in neurogenic muscular atrophy were O-GlcNAc positive. Increase of O-GlcNAc glycosylation could be associated with the stress response, as these lesions have been shown to be positive for several stress markers. Vacuolar rims in s-IBM and DMRV were sometimes sharply lined by O-GlcNAc-positive deposits, which reflects myonuclear breakdown occurring from the disease.
Collapse
Affiliation(s)
- Seika Nakamura
- Department of Neurology and Brain Medical Research Center, Kansai Medical University, Osaka, Japan
| | | | | | | | | |
Collapse
|
195
|
Diverse regulation of AKT and GSK-3β by O-GlcNAcylation in various types of cells. FEBS Lett 2012; 586:2443-50. [PMID: 22687243 DOI: 10.1016/j.febslet.2012.05.063] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Revised: 05/23/2012] [Accepted: 05/31/2012] [Indexed: 01/01/2023]
Abstract
Protein kinase B (AKT) and glycogen synthase kinase-3β (GSK-3β) are major components of insulin-AKT signaling that plays crucial roles in various types of tissue. Recent studies found that these two kinases are modified posttranslationally by O-GlcNAcylation. Here, we demonstrate that O-GlcNAcylation regulated phosphorylation/activation of AKT and GSK-3β in different manners in kidney HEK-293FT cells, but did not affect these two kinases in hepatic HepG2 cells. In neuronal cells, O-GlcNAcylation regulated phosphorylation of AKT negatively, but had no effect on GSK-3β. These results suggest protein-specific and cell type-specific regulation of AKT and GSK-3β by O-GlcNAcylation. Therefore, studies on the roles of AKT and GSK-3β O-GlcNAcylation should be done in a tissue- and cell type-specific manner.
Collapse
|
196
|
Dias WB, Cheung WD, Hart GW. O-GlcNAcylation of kinases. Biochem Biophys Res Commun 2012; 422:224-8. [PMID: 22564745 PMCID: PMC3387735 DOI: 10.1016/j.bbrc.2012.04.124] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Accepted: 04/22/2012] [Indexed: 01/17/2023]
Abstract
Recent evidence indicates that site-specific crosstalk between O-GlcNAcylation and phosphorylation and the O-GlcNAcylation of kinases play an important role in regulating cell signaling. However, relatively few kinases have been analyzed for O-GlcNAcylation. Here, we identify additional kinases that are substrates for O-GlcNAcylation using an in vitro OGT assay on a functional kinase array. Forty-two kinases were O-GlcNAcylated in vitro, representing 39% of the kinases on the array. In addition, we confirmed the in vivo O-GlcNAcylation of three identified kinases. Our results suggest that O-GlcNAcylation may directly regulate a substantial number of kinases and illustrates the increasingly complex relationship between O-GlcNAcylation and phosphorylation in cellular signaling.
Collapse
Affiliation(s)
- Wagner B Dias
- Department of Biological Chemistry, Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA.
| | | | | |
Collapse
|
197
|
Philp A, Hargreaves M, Baar K. More than a store: regulatory roles for glycogen in skeletal muscle adaptation to exercise. Am J Physiol Endocrinol Metab 2012; 302:E1343-51. [PMID: 22395109 DOI: 10.1152/ajpendo.00004.2012] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The glycogen content of muscle determines not only our capacity for exercise but also the signaling events that occur in response to exercise. The result of the shift in signaling is that frequent training in a low-glycogen state results in improved fat oxidation during steady-state submaximal exercise. This review will discuss how the amount or localization of glycogen particles can directly or indirectly result in this differential response to training. The key direct effect discussed is carbohydrate binding, whereas the indirect effects include the metabolic shift toward fat oxidation, the increase in catecholamines, and osmotic stress. Although our understanding of the role of glycogen in response to training has expanded exponentially over the past 5 years, there are still many questions remaining as to how stored carbohydrate affects the muscular adaptation to exercise.
Collapse
Affiliation(s)
- Andrew Philp
- Dept. of Neurobiology, Physiology and Behavior, University of California-Davis, 1 Shields Ave., Davis, CA 95616, USA
| | | | | |
Collapse
|
198
|
Pavic K, Köhn M. Chemical Biology Techniques Unlock the Secrets of Casein Kinase 2 Regulation by Phosphorylation and Glycosylation. Chembiochem 2012; 13:1253-5. [DOI: 10.1002/cbic.201200235] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Indexed: 01/17/2023]
|
199
|
Oliveira SM, Zhang YH, Solis RS, Isackson H, Bellahcene M, Yavari A, Pinter K, Davies JK, Ge Y, Ashrafian H, Walker JW, Carling D, Watkins H, Casadei B, Redwood C. AMP-activated protein kinase phosphorylates cardiac troponin I and alters contractility of murine ventricular myocytes. Circ Res 2012; 110:1192-201. [PMID: 22456184 DOI: 10.1161/circresaha.111.259952] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
RATIONALE AMP-activated protein kinase (AMPK) is an important regulator of energy balance and signaling in the heart. Mutations affecting the regulatory γ2 subunit have been shown to cause an essentially cardiac-restricted phenotype of hypertrophy and conduction disease, suggesting a specific role for this subunit in the heart. OBJECTIVE The γ isoforms are highly conserved at their C-termini but have unique N-terminal sequences, and we hypothesized that the N-terminus of γ2 may be involved in conferring substrate specificity or in determining intracellular localization. METHODS AND RESULTS A yeast 2-hybrid screen of a human heart cDNA library using the N-terminal 273 residues of γ2 as bait identified cardiac troponin I (cTnI) as a putative interactor. In vitro studies showed that cTnI is a good AMPK substrate and that Ser150 is the principal residue phosphorylated. Furthermore, on AMPK activation during ischemia, Ser150 is phosphorylated in whole hearts. Using phosphomimics, measurements of actomyosin ATPase in vitro and force generation in demembraneated trabeculae showed that modification at Ser150 resulted in increased Ca(2+) sensitivity of contractile regulation. Treatment of cardiomyocytes with the AMPK activator 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) resulted in increased myocyte contractility without changing the amplitude of Ca(2+) transient and prolonged relaxation despite shortening the time constant of Ca(2+) transient decay (tau). Compound C prevented the effect of AICAR on myocyte function. These results suggest that AMPK activation increases myocyte contraction and prolongs relaxation by increasing myofilament Ca(2+) sensitivity. CONCLUSIONS We conclude that cTnI phosphorylation by AMPK may represent a novel mechanism of regulation of cardiac function.
Collapse
|
200
|
Diernfellner ACR, Brunner M. O-GlcNAcylation of a circadian clock protein: dPER taking its sweet time. Genes Dev 2012; 26:415-6. [PMID: 22391445 DOI: 10.1101/gad.188524.112] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
In this issue of Genes & Development, Kim and colleagues (pp. 490-502) report that the Drosophila circadian repressor dPER undergoes O-linked GlcNAcylation (O-GlcNAc). Their data show that manipulation of the relevant O-GlcNAc transferase (OGT) regulates behavioral rhythmicity by affecting the stability and nuclear translocation of dPER.
Collapse
|