Li G, Meng F, Zhong X, Yu K, Zhang N, Zhang K, Huang H, Li W, Zhang J, Wang W, Ren Y, Liu Y.
DNA probe pulldown screening uncovers O-GlcNAcylation modulation of transcription factor DNA interactions.
Scientific reports2025
15(1)
40596516
Abstract: O-linked β-N-acetylglucosamine (O-GlcNAc), a critical post-translational modification predominantly found in the nucleus, plays a substantial role in regulating gene expression by modulating transcription factors (TFs) activity. However, quantitative analysis investigating the influence of O-GlcNAcylation on protein-DNA interactions at a proteome scale remains undone. Herein, a pulldown screening approach using a consensus TF response element (catTFRE) was employed to unravel the impact of fluctuating levels of O-GlcNAcylation on the DNA binding efficiency of endogenous TFs/co-factors. Utilizing quantitative proteomics, we identified a substantial enhancement in the binding capacity of 241 nuclear proteins (NPs) to DNA sequences due to elevated levels of O-GlcNAcylation, whereas a decrease in DNA binding was observed for 2 NPs concurrently. Intriguingly, the O-GlcNAcylation elevation significantly enhanced the binding of 146 TFs/co-factors to specific DNA sequences. We further established that the O-GlcNAcylation of several Forkhead family TFs, including FOXA1 and FOXC1, notably enhances their binding to specific DNA sequences in living cells. Our research presents an efficacious approach to assessing the impact of O-GlcNAcylation on the interactions between proteins and DNA. This significantly enhances our understanding of the role O-GlcNAcylation plays in the regulation of transcription.
Srivastava PP, Dasari A, Kumar S, Gupta I, Jain D, Minocha S.
Epigenetic co-regulator HCF-1 promotes lung cancer via O-GlcNAcylation-dependent pathways.
Molecular therapy. Oncology2025
33(4)
41018975
Abstract: The rise in the incidences of lung cancer currently poses a global health challenge, making it crucial to understand the underlying molecular and cellular mechanisms. Host cell factor-1 (HCF-1), a conserved epigenetic transcriptional co-regulator, undergoes proteolytic maturation and glycosylation by O-linked N-acetylglucosamine (O-GlcNAc) transferase (OGT). Elevated O-GlcNAc and OGT levels have been observed in lung cancer, highlighting their potential significance in disease progression. In human lung cancer tissues, we observed a significant upregulation of HCF-1, which coincides with increased OGT, O-GlcNAc, and Nkx2.1 (a diagnostic marker for non-small cell lung cancer [NSCLSC]) levels. To further explore HCF-1's role mechanistically, we utilized the NSCLC cell lines, where HCF-1 depletion resulted in reduced proliferation, O-GlcNAcylation, Nkx2.1 expression, and O-GlcNAcylated proteins upon wheat germ agglutinin (WGA) pull-down, reinforcing its role in lung cancer progression. Additionally, Nkx2.1-mediated conditional knockout of HCF-1 impaired murine lung development and cell proliferation. Interestingly, OGT inhibition with OSMI-1 also reduced HCF-1, Nkx2.1 levels, and proliferation, suggesting a role for O-GlcNAcylation in HCF-1-mediated signaling cascades. Thus, our findings elucidate the critical role of HCF-1 and O-GlcNAcylation in lung cancer pathogenesis. These insights not only deepen our understanding of lung cancer pathogenesis but also identify potential molecular targets for studies aimed at intervention.
Luna S, Malard F, Pereckas M, Aoki M, Aoki K, Olivier-Van Stichelen S.
Studying the O-GlcNAcome of human placentas using banked tissue samples.
Glycobiology2024
34(4)
38253038
Abstract: O-GlcNAcylation is a dynamic modulator of signaling pathways, equal in magnitude to the widely studied phosphorylation. With the rapid development of tools for its detection at the single protein level, the O-GlcNAc modification rapidly emerged as a novel diagnostic and therapeutic target in human diseases. Yet, mapping the human O-GlcNAcome in various tissues is essential for generating relevant biomarkers. In this study, we used human banked tissue as a sample source to identify O-GlcNAcylated protein targets relevant to human diseases. Using human term placentas, we propose (1) a method to clean frozen banked tissue of blood proteins; (2) an optimized protocol for the enrichment of O-GlcNAcylated proteins using immunoaffinity purification; and (3) a bioinformatic workflow to identify the most promising O-GlcNAc targets. As a proof-of-concept, we used 45 mg of banked placental samples from two pregnancies to generate intracellular protein extracts depleted of blood protein. Then, antibody-based O-GlcNAc enrichment on denatured samples yielded over 2000 unique HexNAc PSMs and 900 unique sites using 300 μg of protein lysate. Due to efficient sample cleanup, we also captured 82 HexNAc proteins with high placental expression. Finally, we provide a bioinformatic tool (CytOVS) to sort the HexNAc proteins based on their cellular localization and extract the most promising O-GlcNAc targets to explore further. To conclude, we provide a simple 3-step workflow to generate a manageable list of O-GlcNAc proteins from human tissue and improve our understanding of O-GlcNAcylation's role in health and diseases.
Vang S, Helton ES, Guo Y, Burpee B, Rose E, Easter M, Bollenbecker S, Hirsch MJ, Matthews EL, Jones LI, Howze PH 4th, Rajasekaran V, Denson R, Cochran P, Attah IK, Olson H, Clair G, Melkani G, Krick S, Barnes JW.
O-GlcNAc transferase regulates collagen deposition and fibrosis resolution in idiopathic pulmonary fibrosis.
Frontiers in immunology2024
15
38665916
Abstract: Idiopathic pulmonary fibrosis (IPF) is a chronic pulmonary disease that is characterized by an excessive accumulation of extracellular matrix (ECM) proteins (e.g. collagens) in the parenchyma, which ultimately leads to respiratory failure and death. While current therapies exist to slow the progression, no therapies are available to resolve fibrosis.
Hung YW, Ouyang C, Ping X, Qi Y, Wang YC, Kung HJ, Ann DK.
Extracellular arginine availability modulates eIF2α O-GlcNAcylation and heme oxygenase 1 translation for cellular homeostasis.
Journal of biomedical science2023
30(1)
37217939
Abstract: Nutrient limitations often lead to metabolic stress during cancer initiation and progression. To combat this stress, the enzyme heme oxygenase 1 (HMOX1, commonly known as HO-1) is thought to play a key role as an antioxidant. However, there is a discrepancy between the level of HO-1 mRNA and its protein, particularly in cells under stress. O-linked β-N-acetylglucosamine (O-GlcNAc) modification of proteins (O-GlcNAcylation) is a recently discovered cellular signaling mechanism that rivals phosphorylation in many proteins, including eukaryote translation initiation factors (eIFs). The mechanism by which eIF2α O-GlcNAcylation regulates translation of HO-1 during extracellular arginine shortage (ArgS) remains unclear.
Alghusen IM, Carman MS, Wilkins H, Ephrame SJ, Qiang A, Dias WB, Fedosyuk H, Denson AR, Swerdlow RH, Slawson C.
O-GlcNAc regulates the mitochondrial integrated stress response by regulating ATF4.
Frontiers in aging neuroscience2023
15
38192280
Abstract: Accumulation of mitochondrial dysfunctional is a hallmark of age-related neurodegeneration including Alzheimer's disease (AD). Impairment of mitochondrial quality control mechanisms leading to the accumulation of damaged mitochondria and increasing neuronal stress. Therefore, investigating the basic mechanisms of how mitochondrial homeostasis is regulated is essential. Herein, we investigate the role of O-GlcNAcylation, a single sugar post-translational modification, in controlling mitochondrial stress-induced transcription factor Activating Transcription Factor 4 (ATF4). Mitochondrial dysfunction triggers the integrated stress response (ISRmt), in which the phosphorylation of eukaryotic translation initiation factor 2α results in the translation of ATF4.
Wong YK, Wang J, Lim TK, Lin Q, Yap CT, Shen HM.
O-GlcNAcylation promotes fatty acid synthase activity under nutritional stress as a pro-survival mechanism in cancer cells.
Proteomics2022
22(9)
35083852
Abstract: Protein O-GlcNAcylation is a specific form of protein glycosylation that targets a wide range of proteins with important functions. O-GlcNAcylation is known to be deregulated in cancer and has been linked to multiple aspects of cancer pathology. Despite its ubiquity and importance, the current understanding of the role of O-GlcNAcylation in the stress response remains limited. In this study, we performed a quantitative chemical proteomics-based open study of the O-GlcNAcome in HeLa cells, and identified 163 differentially-glycosylated proteins under starvation, involving multiple metabolic pathways. Among them, fatty acid metabolism was found to be targeted and subsequent analysis confirmed that fatty acid synthase (FASN) is O-GlcNAcylated. O-GlcNAcylation led to enhanced de novo fatty acid synthesis (FAS) activity, and fatty acids contributed to the cytoprotective effects of O-GlcNAcylation under starvation. Moreover, dual inhibition of O-GlcNAcylation and FASN displayed a strong synergistic effect in vitro in inducing cell death in cancer cells. Together, the results from this study provide novel insights into the role of O-GlcNAcylation in the nutritional stress response and suggest the potential of combining inhibition of O-GlcNAcylation and FAS in cancer therapy.
Xie X, Wu Q, Zhang K, Liu Y, Zhang N, Chen Q, Wang L, Li W, Zhang J, Liu Y.
O-GlcNAc modification regulates MTA1 transcriptional activity during breast cancer cell genotoxic adaptation.
Biochimica et biophysica acta. General subjects2021
1865(8)
34019948
Abstract: Chromatin modifier metastasis-associated protein 1 (MTA1), closely associated with tumor angiogenesis in breast cancer, plays an important role in gene expression and cancer cell behavior. Recently, an association between O-GlcNAc transferase (OGT) and MTA1 was identified by mass spectroscopy. However, the potential relationship between MTA1 and O-GlcNAc modification has not yet explored.
Ramirez DH, Yang B, D'Souza AK, Shen D, Woo CM.
Truncation of the TPR domain of OGT alters substrate and glycosite selection.
Analytical and bioanalytical chemistry2021
413(30)
34725712
Abstract: O-GlcNAc transferase (OGT) is an essential enzyme that installs O-linked N-acetylglucosamine (O-GlcNAc) to thousands of protein substrates. OGT and its isoforms select from these substrates through the tetratricopeptide repeat (TPR) domain, yet the impact of truncations to the TPR domain on substrate and glycosite selection is unresolved. Here, we report the effects of iterative truncations to the TPR domain of OGT on substrate and glycosite selection with the model protein GFP-JunB and the surrounding O-GlcNAc proteome in U2OS cells. Iterative truncation of the TPR domain of OGT maintains glycosyltransferase activity but alters subcellular localization of OGT in cells. The glycoproteome and glycosites modified by four OGT TPR isoforms were examined on the whole proteome and a single target protein, GFP-JunB. We found the greatest changes in O-GlcNAc on proteins associated with mRNA splicing processes and that the first four TPRs of the canonical nucleocytoplasmic OGT had the broadest substrate scope. Subsequent glycosite analysis revealed that alteration to the last four TPRs corresponded to the greatest shift in the resulting O-GlcNAc consensus sequence. This dataset provides a foundation to analyze how perturbations to the TPR domain and expression of OGT isoforms affect the glycosylation of substrates, which will be critical for future efforts in protein engineering of OGT, the biology of OGT isoforms, and diseases associated with the TPR domain of OGT.
Ramirez DH, Aonbangkhen C, Wu HY, Naftaly JA, Tang S, O'Meara TR, Woo CM.
Engineering a Proximity-Directed O-GlcNAc Transferase for Selective Protein O-GlcNAcylation in Cells.
ACS chemical biology2020
15(4)
32119511
Abstract: O-Linked β-N-acetylglucosamine (O-GlcNAc) is a monosaccharide that plays an essential role in cellular signaling throughout the nucleocytoplasmic proteome of eukaryotic cells. Strategies for selectively increasing O-GlcNAc levels on a target protein in cells would accelerate studies of this essential modification. Here, we report a generalizable strategy for introducing O-GlcNAc into selected target proteins in cells using a nanobody as a proximity-directing agent fused to O-GlcNAc transferase (OGT). Fusion of a nanobody that recognizes GFP (nGFP) or a nanobody that recognizes the four-amino acid sequence EPEA (nEPEA) to OGT yielded nanobody-OGT constructs that selectively delivered O-GlcNAc to a series of tagged target proteins (e.g., JunB, cJun, and Nup62). Truncation of the tetratricopeptide repeat domain as in OGT(4) increased selectivity for the target protein through the nanobody by reducing global elevation of O-GlcNAc levels in the cell. Quantitative chemical proteomics confirmed the increase in O-GlcNAc to the target protein by nanobody-OGT(4). Glycoproteomics revealed that nanobody-OGT(4) or full-length OGT produced a similar glycosite profile on the target protein JunB and Nup62. Finally, we demonstrate the ability to selectively target endogenous α-synuclein for O-GlcNAcylation in HEK293T cells. These first proximity-directed OGT constructs provide a flexible strategy for targeting additional proteins and a template for further engineering of OGT and the O-GlcNAc proteome in the future. The use of a nanobody to redirect OGT substrate selection for glycosylation of desired proteins in cells may further constitute a generalizable strategy for controlling a broader array of post-translational modifications in cells.
Liu Y, Chen Q, Zhang N, Zhang K, Dou T, Cao Y, Liu Y, Li K, Hao X, Xie X, Li W, Ren Y, Zhang J.
Proteomic profiling and genome-wide mapping of O-GlcNAc chromatin-associated proteins reveal an O-GlcNAc-regulated genotoxic stress response.
Nature communications2020
11(1)
33214551
Abstract: O-GlcNAc modification plays critical roles in regulating the stress response program and cellular homeostasis. However, systematic and multi-omics studies on the O-GlcNAc regulated mechanism have been limited. Here, comprehensive data are obtained by a chemical reporter-based method to survey O-GlcNAc function in human breast cancer cells stimulated with the genotoxic agent adriamycin. We identify 875 genotoxic stress-induced O-GlcNAc chromatin-associated proteins (OCPs), including 88 O-GlcNAc chromatin-associated transcription factors and cofactors (OCTFs), subsequently map their genomic loci, and construct a comprehensive transcriptional reprogramming network. Notably, genotoxicity-induced O-GlcNAc enhances the genome-wide interactions of OCPs with chromatin. The dynamic binding switch of hundreds of OCPs from enhancers to promoters is identified as a crucial feature in the specific transcriptional activation of genes involved in the adaptation of cancer cells to genotoxic stress. The OCTF nuclear factor erythroid 2-related factor-1 (NRF1) is found to be a key response regulator in O-GlcNAc-modulated cellular homeostasis. These results provide a valuable clue suggesting that OCPs act as stress sensors by regulating the expression of various genes to protect cancer cells from genotoxic stress.
Phoomak C, Park D, Silsirivanit A, Sawanyawisuth K, Vaeteewoottacharn K, Detarya M, Wongkham C, Lebrilla CB, Wongkham S.
O-GlcNAc-induced nuclear translocation of hnRNP-K is associated with progression and metastasis of cholangiocarcinoma.
Molecular oncology2019
13(2)
30444036
Abstract: O-GlcNAcylation is a key post-translational modification that modifies the functions of proteins. Associations between O-GlcNAcylation, shorter survival of cholangiocarcinoma (CCA) patients, and increased migration/invasion of CCA cell lines have been reported. However, the specific O-GlcNAcylated proteins (OGPs) that participate in promotion of CCA progression are poorly understood. OGPs were isolated from human CCA cell lines, KKU-213 and KKU-214, using a click chemistry-based enzymatic labeling system, identified using LC-MS/MS, and searched against an OGP database. From the proteomic analysis, a total of 21 OGPs related to cancer progression were identified, of which 12 have not been previously reported. Among these, hnRNP-K, a multifaceted RNA- and DNA-binding protein known as a pre-mRNA-binding protein, was one of the most abundantly expressed, suggesting its involvement in CCA progression. O-GlcNAcylation of hnRNP-K was further verified by anti-OGP/anti-hnRNP-K immunoprecipitations and sWGA pull-down assays. The perpetuation of CCA by hnRNP-K was evaluated using siRNA, which revealed modulation of cyclin D1, XIAP, EMT markers, and MMP2 and MMP7 expression. In native CCA cells, hnRNP-K was primarily localized in the nucleus; however, when O-GlcNAcylation was suppressed, hnRNP-K was retained in the cytoplasm. These data signify an association between nuclear accumulation of hnRNP-K and the migratory capabilities of CCA cells. In human CCA tissues, expression of nuclear hnRNP-K was positively correlated with high O-GlcNAcylation levels, metastatic stage, and shorter survival of CCA patients. This study demonstrates the significance of O-GlcNAcylation on the nuclear translocation of hnRNP-K and its impact on the progression of CCA.
Woo CM, Lund PJ, Huang AC, Davis MM, Bertozzi CR, Pitteri SJ.
Mapping and Quantification of Over 2000 O-linked Glycopeptides in Activated Human T Cells with Isotope-Targeted Glycoproteomics (Isotag).
Molecular & cellular proteomics : MCP2018
17(4)
29351928
Abstract: Post-translational modifications (PTMs) on proteins often function to regulate signaling cascades, with the activation of T cells during an adaptive immune response being a classic example. Mounting evidence indicates that the modification of proteins by O-linked N-acetylglucosamine (O-GlcNAc), the only mammalian glycan found on nuclear and cytoplasmic proteins, helps regulate T cell activation. Yet, a mechanistic understanding of how O-GlcNAc functions in T cell activation remains elusive, partly because of the difficulties in mapping and quantifying O-GlcNAc sites. Thus, to advance insight into the role of O-GlcNAc in T cell activation, we performed glycosite mapping studies via direct glycopeptide measurement on resting and activated primary human T cells with a technique termed Isotope Targeted Glycoproteomics. This approach led to the identification of 2219 intact O-linked glycopeptides across 1045 glycoproteins. A significant proportion (>45%) of the identified O-GlcNAc sites lie near or coincide with a known phosphorylation site, supporting the potential for PTM crosstalk. Consistent with other studies, we find that O-GlcNAc sites in T cells lack a strict consensus sequence. To validate our results, we employed gel shift assays based on conjugating mass tags to O-GlcNAc groups. Notably, we observed that the transcription factors c-JUN and JUNB show higher levels of O-GlcNAc glycosylation and higher levels of expression in activated T cells. Overall, our findings provide a quantitative characterization of O-GlcNAc glycoproteins and their corresponding modification sites in primary human T cells, which will facilitate mechanistic studies into the function of O-GlcNAc in T cell activation.
Berthier A, Vinod M, Porez G, Steenackers A, Alexandre J, Yamakawa N, Gheeraert C, Ploton M, Maréchal X, Dubois-Chevalier J, Hovasse A, Schaeffer-Reiss C, Cianférani S, Rolando C, Bray F, Duez H, Eeckhoute J, Lefebvre T, Staels B, Lefebvre P.
Combinatorial regulation of hepatic cytoplasmic signaling and nuclear transcriptional events by the OGT/REV-ERBα complex.
Proceedings of the National Academy of Sciences of the United States of America2018
115(47)
30397120
Abstract: The nuclear receptor REV-ERBα integrates the circadian clock with hepatic glucose and lipid metabolism by nucleating transcriptional comodulators at genomic regulatory regions. An interactomic approach identified O-GlcNAc transferase (OGT) as a REV-ERBα-interacting protein. By shielding cytoplasmic OGT from proteasomal degradation and favoring OGT activity in the nucleus, REV-ERBα cyclically increased O-GlcNAcylation of multiple cytoplasmic and nuclear proteins as a function of its rhythmically regulated expression, while REV-ERBα ligands mostly affected cytoplasmic OGT activity. We illustrate this finding by showing that REV-ERBα controls OGT-dependent activities of the cytoplasmic protein kinase AKT, an essential relay in insulin signaling, and of ten-of-eleven translocation (TET) enzymes in the nucleus. AKT phosphorylation was inversely correlated to REV-ERBα expression. REV-ERBα enhanced TET activity and DNA hydroxymethylated cytosine (5hmC) levels in the vicinity of REV-ERBα genomic binding sites. As an example, we show that the REV-ERBα/OGT complex modulates SREBP-1c gene expression throughout the fasting/feeding periods by first repressing AKT phosphorylation and by epigenomically priming the Srebf1 promoter for a further rapid response to insulin. Conclusion: REV-ERBα regulates cytoplasmic and nuclear OGT-controlled processes that integrate at the hepatic SREBF1 locus to control basal and insulin-induced expression of the temporally and nutritionally regulated lipogenic SREBP-1c transcript.
Li S, Zhu H, Wang J, Wang X, Li X, Ma C, Wen L, Yu B, Wang Y, Li J, Wang PG.
Comparative analysis of Cu (I)-catalyzed alkyne-azide cycloaddition (CuAAC) and strain-promoted alkyne-azide cycloaddition (SPAAC) in O-GlcNAc proteomics.
Electrophoresis2016
37(11)
26853435
Abstract: O-linked β-N-acetylglucosamine (O-GlcNAc) is emerging as an essential protein post-translational modification in a range of organisms. It is involved in various cellular processes such as nutrient sensing, protein degradation, gene expression, and is associated with many human diseases. Despite its importance, identifying O-GlcNAcylated proteins is a major challenge in proteomics. Here, using peracetylated N-azidoacetylglucosamine (Ac4 GlcNAz) as a bioorthogonal chemical handle, we described a gel-based mass spectrometry method for the identification of proteins with O-GlcNAc modification in A549 cells. In addition, we made a labeling efficiency comparison between two modes of azide-alkyne bioorthogonal reactions in click chemistry: copper-catalyzed azide-alkyne cycloaddition (CuAAC) with Biotin-Diazo-Alkyne and stain-promoted azide-alkyne cycloaddition (SPAAC) with Biotin-DIBO-Alkyne. After conjugation with click chemistry in vitro and enrichment via streptavidin resin, proteins with O-GlcNAc modification were separated by SDS-PAGE and identified with mass spectrometry. Proteomics data analysis revealed that 229 putative O-GlcNAc modified proteins were identified with Biotin-Diazo-Alkyne conjugated sample and 188 proteins with Biotin-DIBO-Alkyne conjugated sample, among which 114 proteins were overlapping. Interestingly, 74 proteins identified from Biotin-Diazo-Alkyne conjugates and 46 verified proteins from Biotin-DIBO-Alkyne conjugates could be found in the O-GlcNAc modified proteins database dbOGAP (http://cbsb.lombardi.georgetown.edu/hulab/OGAP.html). These results suggested that CuAAC with Biotin-Diazo-Alkyne represented a more powerful method in proteomics with higher protein identification and better accuracy compared to SPAAC. The proteomics credibility was also confirmed by the molecular function and cell component gene ontology (GO). Together, the method we reported here combining metabolic labeling, click chemistry, affinity-based enrichment, SDS-PAGE separation, and mass spectrometry, would be adaptable for other post-translationally modified proteins in proteomics.
Hahne H, Sobotzki N, Nyberg T, Helm D, Borodkin VS, van Aalten DM, Agnew B, Kuster B.
Proteome wide purification and identification of O-GlcNAc-modified proteins using click chemistry and mass spectrometry.
Journal of proteome research2013
12(2)
23301498
Abstract: The post-translational modification of proteins with N-acetylglucosamine (O-GlcNAc) is involved in the regulation of a wide variety of cellular processes and associated with a number of chronic diseases. Despite its emerging biological significance, the systematic identification of O-GlcNAc proteins is still challenging. In the present study, we demonstrate a significantly improved O-GlcNAc protein enrichment procedure, which exploits metabolic labeling of cells by azide-modified GlcNAc and copper-mediated Click chemistry for purification of modified proteins on an alkyne-resin. On-resin proteolysis using trypsin followed by LC-MS/MS afforded the identification of around 1500 O-GlcNAc proteins from a single cell line. Subsequent elution of covalently resin bound O-GlcNAc peptides using selective β-elimination enabled the identification of 185 O-GlcNAc modification sites on 80 proteins. To demonstrate the practical utility of the developed approach, we studied the global effects of the O-GlcNAcase inhibitor GlcNAcstatin G on the level of O-GlcNAc modification of cellular proteins. About 200 proteins including several key players involved in the hexosamine signaling pathway showed significantly increased O-GlcNAcylation levels in response to the drug, which further strengthens the link of O-GlcNAc protein modification to cellular nutrient sensing and response.
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.
Biochimica et biophysica acta2012
1820(12)
22967762
Abstract: 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.
Zhao P, Viner R, Teo CF, Boons GJ, Horn D, Wells L.
Combining high-energy C-trap dissociation and electron transfer dissociation for protein O-GlcNAc modification site assignment.
Journal of proteome research2011
10(9)
21740066
Abstract: Mass spectrometry-based studies of proteins that are post-translationally modified by O-linked β-N-acetylglucosamine (O-GlcNAc) are challenged in effectively identifying the sites of modification while simultaneously sequencing the peptides. Here we tested the hypothesis that a combination of high-energy C-trap dissociation (HCD) and electron transfer dissociation (ETD) could specifically target the O-GlcNAc modified peptides and elucidate the amino acid sequence while preserving the attached GlcNAc residue for accurate site assignment. By taking advantage of the recently characterized O-GlcNAc-specific IgG monoclonal antibodies and the combination of HCD and ETD fragmentation techniques, O-GlcNAc modified proteins were enriched from HEK293T cells and subsequently characterized using the LTQ Orbitrap Velos ETD (Thermo Fisher Scientific) mass spectrometer. In our data set, 83 sites of O-GlcNAc modification are reported with high confidence confirming that the HCD/ETD combined approach is amenable to the detection and site assignment of O-GlcNAc modified peptides. Realizing HCD triggered ETD fragmentation on a linear ion trap/Orbitrap platform for more in-depth analysis and application of this technique to other post-translationally modified proteins are currently underway. Furthermore, this report illustrates that the O-GlcNAc transferase appears to demonstrate promiscuity with regards to the hydroxyl-containing amino acid modified in short stretches of primary sequence of the glycosylated polypeptides.
Fujiki R, Hashiba W, Sekine H, Yokoyama A, Chikanishi T, Ito S, Imai Y, Kim J, He HH, Igarashi K, Kanno J, Ohtake F, Kitagawa H, Roeder RG, Brown M, Kato S.
GlcNAcylation of histone H2B facilitates its monoubiquitination.
Nature2011
480(7378)
22121020
Abstract: Chromatin reorganization is governed by multiple post-translational modifications of chromosomal proteins and DNA. These histone modifications are reversible, dynamic events that can regulate DNA-driven cellular processes. However, the molecular mechanisms that coordinate histone modification patterns remain largely unknown. In metazoans, reversible protein modification by O-linked N-acetylglucosamine (GlcNAc) is catalysed by two enzymes, O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA). However, the significance of GlcNAcylation in chromatin reorganization remains elusive. Here we report that histone H2B is GlcNAcylated at residue S112 by OGT in vitro and in living cells. Histone GlcNAcylation fluctuated in response to extracellular glucose through the hexosamine biosynthesis pathway (HBP). H2B S112 GlcNAcylation promotes K120 monoubiquitination, in which the GlcNAc moiety can serve as an anchor for a histone H2B ubiquitin ligase. H2B S112 GlcNAc was localized to euchromatic areas on fly polytene chromosomes. In a genome-wide analysis, H2B S112 GlcNAcylation sites were observed widely distributed over chromosomes including transcribed gene loci, with some sites co-localizing with H2B K120 monoubiquitination. These findings suggest that H2B S112 GlcNAcylation is a histone modification that facilitates H2BK120 monoubiquitination, presumably for transcriptional activation.
Nandi A, Sprung R, Barma DK, Zhao Y, Kim SC, Falck JR, Zhao Y.
Global identification of O-GlcNAc-modified proteins.
Analytical chemistry2006
78(2)
16408927
Abstract: The O-linked N-acetylglucosamine (O-GlcNAc) modification of serine/threonine residues is an abundant posttranslational modification present in cytosolic and nuclear proteins. The functions and subproteome of O-GlcNAc modification remain largely undefined. Here we report the application of the tagging-via-substrate (TAS) approach for global identification of O-GlcNAc-modified proteins. The TAS method utilizes an O-GlcNAc azide analogue for metabolic labeling of O-GlcNAc-modified proteins, which can be chemoselectively conjugated for detection and enrichment of the proteins for proteomics studies. Our study led to the identification of 199 putative O-GlcNAc-modified proteins from HeLa cells, among which 23 were confirmed using reciprocal immunoprecipitation. Functional classification shows that proteins with diverse functions are modified by O-GlcNAc, implying that O-GlcNAc might be involved in the regulation of multiple cellular pathways.