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Physiological Reviews Apr 2021In the mid-1980s, the identification of serine and threonine residues on nuclear and cytoplasmic proteins modified by a -acetylglucosamine moiety (-GlcNAc) via an... (Review)
Review
In the mid-1980s, the identification of serine and threonine residues on nuclear and cytoplasmic proteins modified by a -acetylglucosamine moiety (-GlcNAc) via an -linkage overturned the widely held assumption that glycosylation only occurred in the endoplasmic reticulum, Golgi apparatus, and secretory pathways. In contrast to traditional glycosylation, the -GlcNAc modification does not lead to complex, branched glycan structures and is rapidly cycled on and off proteins by -GlcNAc transferase (OGT) and -GlcNAcase (OGA), respectively. Since its discovery, -GlcNAcylation has been shown to contribute to numerous cellular functions, including signaling, protein localization and stability, transcription, chromatin remodeling, mitochondrial function, and cell survival. Dysregulation in -GlcNAc cycling has been implicated in the progression of a wide range of diseases, such as diabetes, diabetic complications, cancer, cardiovascular, and neurodegenerative diseases. This review will outline our current understanding of the processes involved in regulating -GlcNAc turnover, the role of -GlcNAcylation in regulating cellular physiology, and how dysregulation in -GlcNAc cycling contributes to pathophysiological processes.
Topics: Acetylglucosamine; Animals; Cell Physiological Phenomena; Glycosylation; Humans; N-Acetylglucosaminyltransferases; Protein Processing, Post-Translational
PubMed: 32730113
DOI: 10.1152/physrev.00043.2019 -
Cell Metabolism Nov 2023Emerging studies have addressed the tumor-promoting role of fructose in different cancers. The effects and pathological mechanisms of high dietary fructose on...
Emerging studies have addressed the tumor-promoting role of fructose in different cancers. The effects and pathological mechanisms of high dietary fructose on hepatocellular carcinoma (HCC) remain unclear. Here, we examined the effects of fructose supplementation on HCC progression in wild-type C57BL/6 mice using a spontaneous and chemically induced HCC mouse model. We show that elevated uridine diphospho-N-acetylglucosamine (UDP-GlcNAc) and O-GlcNAcylation levels induced by high dietary fructose contribute to HCC progression. Non-targeted metabolomics and stable isotope tracing revealed that under fructose treatment, microbiota-derived acetate upregulates glutamine and UDP-GlcNAc levels and enhances protein O-GlcNAcylation in HCC. Global profiling of O-GlcNAcylation revealed that hyper-O-GlcNAcylation of eukaryotic elongation factor 1A1 promotes cell proliferation and tumor growth. Targeting glutamate-ammonia ligase or O-linked N-acetylglucosamine transferase (OGT) remarkably impeded HCC progression in mice with high fructose intake. We propose that high dietary fructose promotes HCC progression through microbial acetate-induced hyper-O-GlcNAcylation.
Topics: Mice; Animals; Carcinoma, Hepatocellular; Liver Neoplasms; Mice, Inbred C57BL; Cell Proliferation; Uridine Diphosphate; N-Acetylglucosaminyltransferases; Acetylglucosamine; Protein Processing, Post-Translational
PubMed: 37797623
DOI: 10.1016/j.cmet.2023.09.009 -
Cancer Letters Jul 2023O-linked β-D-N-acetylglucosamine (O-GlcNAc), as a posttranslational modification (PTM), is a reversible reaction that attaches β-N-GlcNAc to Ser/Thr residues on... (Review)
Review
O-linked β-D-N-acetylglucosamine (O-GlcNAc), as a posttranslational modification (PTM), is a reversible reaction that attaches β-N-GlcNAc to Ser/Thr residues on specific proteins by O-GlcNAc transferase (OGT). O-GlcNAcase (OGA) removes the O-GlcNAc from O-GlcNAcylated proteins. O-GlcNAcylation regulates numerous cellular processes, including signal transduction, the cell cycle, metabolism, and energy homeostasis. Dysregulation of O-GlcNAcylation contributes to the development of various diseases, including cancers. Accumulating evidence has revealed that higher expression levels of OGT and hyper-O-GlcNAcylation are detected in many cancer types and governs glucose metabolism, proliferation, metastasis, invasion, angiogenesis, migration and drug resistance. In this review, we describe the biological functions and molecular mechanisms of OGT- or O-GlcNAcylation-mediated tumorigenesis. Moreover, we discuss the potential role of O-GlcNAcylation in tumor immunotherapy. Furthermore, we highlight that compounds can target O-GlcNAcylation by regulating OGT to suppress oncogenesis. Taken together, targeting protein O-GlcNAcylation might be a promising strategy for the treatment of human malignancies.
Topics: Humans; Protein Processing, Post-Translational; Neoplasms; Proteins; Signal Transduction; Immunotherapy; N-Acetylglucosaminyltransferases; Acetylglucosamine
PubMed: 37279852
DOI: 10.1016/j.canlet.2023.216258 -
The Journal of Clinical Investigation Apr 2023Major depressive disorder is a common and devastating psychiatric disease, and the prevalence and burden are substantially increasing worldwide. Multiple studies of...
Major depressive disorder is a common and devastating psychiatric disease, and the prevalence and burden are substantially increasing worldwide. Multiple studies of depression patients have implicated glucose metabolic dysfunction in the pathophysiology of depression. However, the molecular mechanisms by which glucose and related metabolic pathways modulate depressive-like behaviors are largely uncharacterized. Uridine diphosphate N-acetylglucosamine (UDP-GlcNAc) is a glucose metabolite with pivotal functions as a donor molecule for O-GlcNAcylation. O-GlcNAc transferase (OGT), a key enzyme in protein O-GlcNAcylation, catalyzes protein posttranslational modification by O-GlcNAc and acts as a stress sensor. Here, we show that Ogt mRNA was increased in depression patients and that astroglial OGT expression was specifically upregulated in the medial prefrontal cortex (mPFC) of susceptible mice after chronic social-defeat stress. The selective deletion of astrocytic OGT resulted in antidepressant-like effects, and moreover, astrocytic OGT in the mPFC bidirectionally regulated vulnerability to social stress. Furthermore, OGT modulated glutamatergic synaptic transmission through O-GlcNAcylation of glutamate transporter-1 (GLT-1) in astrocytes. OGT astrocyte-specific knockout preserved the neuronal morphology atrophy and Ca2+ activity deficits caused by chronic stress and resulted in antidepressant effects. Our study reveals that astrocytic OGT in the mPFC regulates depressive-like behaviors through the O-GlcNAcylation of GLT-1 and could be a potential target for antidepressants.
Topics: Mice; Animals; Astrocytes; Depressive Disorder, Major; Depression; Synaptic Transmission; N-Acetylglucosaminyltransferases; Antidepressive Agents; Glucose; Acetylglucosamine
PubMed: 36757814
DOI: 10.1172/JCI160016 -
Nature Cell Biology May 2022A decline in skeletal muscle mass and low muscular strength are prognostic factors in advanced human cancers. Here we found that breast cancer suppressed O-linked...
A decline in skeletal muscle mass and low muscular strength are prognostic factors in advanced human cancers. Here we found that breast cancer suppressed O-linked N-acetylglucosamine (O-GlcNAc) protein modification in muscle through extracellular-vesicle-encapsulated miR-122, which targets O-GlcNAc transferase (OGT). Mechanistically, O-GlcNAcylation of ryanodine receptor 1 (RYR1) competed with NEK10-mediated phosphorylation and increased K48-linked ubiquitination and proteasomal degradation; the miR-122-mediated decrease in OGT resulted in increased RYR1 abundance. We further found that muscular protein O-GlcNAcylation was regulated by hypoxia and lactate through HIF1A-dependent OGT promoter activation and was elevated after exercise. Suppressed O-GlcNAcylation in the setting of cancer, through increasing RYR1, led to higher cytosolic Ca and calpain protease activation, which triggered cleavage of desmin filaments and myofibrillar destruction. This was associated with reduced skeletal muscle mass and contractility in tumour-bearing mice. Our findings link O-GlcNAcylation to muscular protein homoeostasis and contractility and reveal a mechanism of cancer-associated muscle dysregulation.
Topics: Acetylglucosamine; Animals; Humans; Mice; MicroRNAs; Muscle, Skeletal; N-Acetylglucosaminyltransferases; Neoplasms; Protein Processing, Post-Translational; Proteolysis; Ryanodine Receptor Calcium Release Channel
PubMed: 35469018
DOI: 10.1038/s41556-022-00893-0 -
Nature Chemistry Jul 2022Liquid-liquid phase separation (LLPS) of SynGAP and PSD-95, two abundant proteins that interact in the postsynaptic density (PSD) of neurons, has been implicated in...
Liquid-liquid phase separation (LLPS) of SynGAP and PSD-95, two abundant proteins that interact in the postsynaptic density (PSD) of neurons, has been implicated in modulating SynGAP PSD enrichment in excitatory synapses. However, the underlying regulatory mechanisms remain enigmatic. Here we report that O-GlcNAcylation of SynGAP acts as a suppressor of LLPS of the SynGAP/PSD-95 complex. We identified multiple O-GlcNAc modification sites for the endogenous SynGAP isolated from rat brain and the recombinantly expressed protein. Protein semisynthesis was used to generate site-specifically O-GlcNAcylated forms of SynGAP, and in vitro and cell-based LLPS assays demonstrated that T1306 O-GlcNAc of SynGAP blocks the interaction with PSD-95, thus inhibiting LLPS. Furthermore, O-GlcNAcylation suppresses SynGAP/PSD-95 LLPS in a dominant-negative manner, enabling sub-stoichiometric O-GlcNAcylation to exert effective regulation. We also showed that O-GlcNAc-dependent LLPS is reversibly regulated by O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA). These findings demonstrate that OGT- and OGA-catalysed O-GlcNAc cycling may serve as an LLPS-regulating post-translational modification.
Topics: Acetylglucosamine; Animals; Neurons; Protein Processing, Post-Translational; Rats
PubMed: 35637289
DOI: 10.1038/s41557-022-00946-9 -
Gastroenterology Jan 2023Weight loss and exercise intervention have been reported to increase the interaction between Bacteroides spp and Akkermansiamuciniphila (Am), although the underlying...
BACKGROUND & AIMS
Weight loss and exercise intervention have been reported to increase the interaction between Bacteroides spp and Akkermansiamuciniphila (Am), although the underlying mechanisms and consequences of the interaction remain unknown.
METHODS
Using a healthy Korean twin cohort (n = 582), we analyzed taxonomic associations with host body mass index. B vulgatus strains were isolated from mice and human subjects to investigate the strain-specific effect of B vulgatus SNUG 40005 (Bvul) on obesity. The mechanisms underlying Am enrichment by Bvul administration were investigated by multiple experiments: (1) in vitro cross-feeding experiments, (2) construction of Bvul mutants with the N-acetylglucosaminidase gene knocked out, and (3) in vivo validation cohorts with different metabolites. Finally, metabolite profiling in mouse and human fecal samples was performed.
RESULTS
An interaction between Bvul and Am was observed in lean subjects but was disrupted in obese subjects. The administration of Bvul to mice fed a high-fat diet decreased body weight, insulin resistance, and gut permeability. In particular, Bvul restored the abundance of Am, which decreased significantly after a long-term high-fat diet. A cross-feeding analysis of Am with cecal contents or Bvul revealed that Am enrichment was attributed to metabolites produced during mucus degradation by Bvul. The metabolome profile of mouse fecal samples identified N-acetylglucosamine as contributing to Am enrichment, which was confirmed by in vitro and in vivo experiments. Metabolite network analysis of the twin cohort found that lysine serves as a bridge between N-acetylglucosamine, Bvul, and Am.
CONCLUSIONS
Strain-specific microbe-microbe interactions modulate the mucosal environment via metabolites produced during mucin degradation in the gut.
Topics: Humans; Mice; Animals; Akkermansia; Acetylglucosamine; Bacteroides; Obesity; Diet, High-Fat
PubMed: 36240952
DOI: 10.1053/j.gastro.2022.09.040 -
Chemical Society Reviews Sep 2021The addition of -linked-β-D--acetylglucosamine (-GlcNAc) onto serine and threonine residues of nuclear and cytoplasmic proteins is an abundant, unique... (Review)
Review
The addition of -linked-β-D--acetylglucosamine (-GlcNAc) onto serine and threonine residues of nuclear and cytoplasmic proteins is an abundant, unique post-translational modification governing important biological processes. -GlcNAc dysregulation underlies several metabolic disorders leading to human diseases, including cancer, neurodegeneration and diabetes. This review provides an extensive summary of the recent progress in probing -GlcNAcylation using mainly chemical methods, with a special focus on discussing mechanistic insights and the structural role of -GlcNAc at the molecular level. We highlight key aspects of the -GlcNAc enzymes, including development of OGT and OGA small-molecule inhibitors, and describe a variety of chemoenzymatic and chemical biology approaches for the study of -GlcNAcylation. Special emphasis is placed on the power of chemistry in the form of synthetic glycopeptide and glycoprotein tools for investigating the site-specific functional consequences of the modification. Finally, we discuss in detail the conformational effects of -GlcNAc glycosylation on protein structure and stability, relevant -GlcNAc-mediated protein interactions and its molecular recognition features by biological receptors. Future research in this field will provide novel, more effective chemical strategies and probes for the molecular interrogation of -GlcNAcylation, elucidating new mechanisms and functional roles of -GlcNAc with potential therapeutic applications in human health.
Topics: Acetylglucosamine; Glycosylation; Humans; N-Acetylglucosaminyltransferases; Protein Processing, Post-Translational; Proteins
PubMed: 34338261
DOI: 10.1039/d0cs01275k -
Nature Biomedical Engineering Oct 2019Homeostatic antigen presentation by hepatic antigen-presenting cells, which results in tolerogenic T-cell education, could be exploited to induce antigen-specific...
Homeostatic antigen presentation by hepatic antigen-presenting cells, which results in tolerogenic T-cell education, could be exploited to induce antigen-specific immunological tolerance. Here we show that antigens modified with polymeric forms of either N-acetylgalactosamine or N-acetylglucosamine target hepatic antigen-presenting cells, increase their antigen presentation and induce antigen-specific tolerance, as indicated by CD4 and CD8 T-cell deletion and anergy. These synthetically glycosylated antigens also expanded functional regulatory T cells, which are necessary for the durable suppression of antigen-specific immune responses. In an adoptive-transfer mouse model of type-1 diabetes, treatment with the glycosylated autoantigens prevented T-cell-mediated diabetes, expanded antigen-specific regulatory T cells and resulted in lasting tolerance to a subsequent challenge with activated diabetogenic T cells. Glycosylated autoantigens targeted to hepatic antigen-presenting cells might enable therapies that promote immune tolerance in patients with autoimmune diseases.
Topics: Acetylgalactosamine; Acetylglucosamine; Adoptive Transfer; Animals; Antigen Presentation; Autoantigens; CD4-Positive T-Lymphocytes; CD8-Positive T-Lymphocytes; Diabetes Mellitus, Type 1; Disease Models, Animal; Female; Immune Tolerance; Liver; Mice; Mice, Inbred C57BL; Mice, Inbred NOD; Mice, SCID; Spleen; T-Lymphocytes
PubMed: 31358881
DOI: 10.1038/s41551-019-0424-1 -
Cell Jan 2023O-GlcNAc is a dynamic post-translational modification (PTM) that regulates protein functions. In studying the regulatory roles of O-GlcNAc, a major roadblock is the...
O-GlcNAc is a dynamic post-translational modification (PTM) that regulates protein functions. In studying the regulatory roles of O-GlcNAc, a major roadblock is the inability to change O-GlcNAcylation on a single protein at a time. Herein, we developed a dual RNA-aptamer-based approach that simultaneously targeted O-GlcNAc transferase (OGT) and β-catenin, the key transcription factor of the Wnt signaling pathway, to selectively increase O-GlcNAcylation of the latter without affecting other OGT substrates. Using the OGT/β-catenin dual-specificity aptamers, we found that O-GlcNAcylation of β-catenin stabilizes the protein by inhibiting its interaction with β-TrCP. O-GlcNAc also increases β-catenin's interaction with EZH2, recruits EZH2 to promoters, and dramatically alters the transcriptome. Further, by coupling riboswitches or an inducible expression system to aptamers, we enabled inducible regulation of protein-specific O-GlcNAcylation. Together, our findings demonstrate the efficacy and versatility of dual-specificity aptamers for regulating O-GlcNAcylation on individual proteins.
Topics: Aptamers, Nucleotide; beta Catenin; Protein Processing, Post-Translational; Wnt Signaling Pathway; N-Acetylglucosaminyltransferases; Acetylglucosamine
PubMed: 36626902
DOI: 10.1016/j.cell.2022.12.016