O-GlcNAcylation of Raptor transduces glucose signals to mTORC1
Ontology highlight
ABSTRACT:
INSTRUMENT(S): Orbitrap Fusion Lumos
ORGANISM(S): Homo Sapiens (human)
TISSUE(S): Cell Culture
SUBMITTER: 
Xiaoqing Pan
LAB HEAD: Xing Chen
PROVIDER: PXD039536 | Pride | 2023-08-03
REPOSITORIES: Pride
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| Lumos_iso-PTOP.raw | Raw | |||
| O-GlcNAc_sites_Heavy.txt | Txt | |||
| O-GlcNAc_sites_Light.txt | Txt | |||
| checksum.txt | Txt | |||
| evidence_Heavy.txt | Txt |
Items per page: 5 1 - 5 of 8 |
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Project description:O-linked β-N-acetylglucosaminylation (O-GlcNAcylation) is a ubiquitous posttranslational modification occurring in both animals and plants. Thousands of proteins along with their O-GlcNAcylation sites have been identified in various animal systems, yet the O-GlcNAcylated proteomes in plants remain poorly understood. Here, we report a large-scale profiling of protein O-GlcNAcylation in a site-specific manner in rice. We first established the metabolic glycan labeling strategy (MGL) with N-azidoacetylgalactosamine (GalNAz) in rice seedlings, which enabled incorporation of azides as a bioorthogonal handle into O-GlcNAc. By conjugation of the azide-incorporated O-GlcNAc with alkyne-biotin containing a cleavable linker via click chemistry, O-GlcNAcylated proteins were selectively enriched for mass spectrometry (MS) analysis. A total of 1,591 unambiguous O-GlcNAcylation sites distributed on 709 O-GlcNAcylated proteins were identified. Additionally, 102 O-GlcNAcylated proteins were identified with their O-GlcNAcylation sites located within a serine/threonine-enriched peptide, causing ambiguous site assignment. The identified O-GlcNAcylated proteins are involved in multiple biological processes such as transcription, translation and plant hormone signaling. Furthermore, we discovered two O-GlcNAc transferases (OsOGTs) in rice. By expressing OsOGTs in Escherichia coli and Nicotiana benthamiana leaves, we confirmed their OGT enzymatic activities and used them to validate the identified rice O-GlcNAcylated proteins. Our dataset provides a valuable resource for studying O-GlcNAc biology in rice, and the MGL method should facilitate the identification of O-GlcNAcylated proteins in various plants.
2023-05-10 | PXD036527 | Pride
Project description:Naïve T cells respond to antigen stimulation by exiting from quiescence into clonal expansion and functional differentiation, but the control mechanism is elusive. Here we describe that Raptor/mTORC1-dependent metabolic reprogramming is a central determinant of this transitional process. Loss of Raptor abrogates T cell priming and Th2 cell differentiation, although Raptor function is less important for continuous proliferation of actively cycling cells. mTORC1 coordinates multiple metabolic programs in T cells including glycolysis, lipid synthesis and oxidative phosphorylation to mediate antigen-triggered exit from quiescence. mTORC1 further links glucose metabolism to the initiation of Th2 differentiation by orchestrating cytokine receptor expression and cytokine responsiveness. Activation of Raptor/mTORC1 integrates T cell receptor (TCR) and CD28 co-stimulatory signals in antigen-stimulated T cells. Our studies identify a Raptor/mTORC1-dependent pathway linking signal-dependent metabolic reprogramming to quiescence exit, and this in turn coordinates lymphocyte activation and fate decisions in adaptive immunity. We used microarrays to explore the gene expression profiles differentially expressed in CD4+ T-cells from wild-type (WT) and CD4(cre) x Raptor(fl/fl) mice before and after stimulation with anti CD3/CD28 antibodies.
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Project description:We investigated the role of mTORC1 in murine hematopoiesis by conditionally deleting the Raptor gene in murine hematopoietic stem cells. We observed mutliple alterations evoked by Raptor loss in hematopoiesis and profiled gene-expression alterations induced by raptor loss in Flt3-Lin-Sca1+cKit+ hematopoietic stem and progenitor enriched cell populations, 5 weeks post Raptor deletion. Flt3-Lin-Sca1+cKit+ cells were flow sorted from mice containing homozygous floxed alleles for exon 6 of the Raptor gene in the presence (MT group) or absence (WT group) of the MxCre transgene, which was induced with injections of mice with pIpC 5 weeks before cell isolation.
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Project description:The mechanistic target of rapamycin (mTOR) pathway integrates diverse environmental inputs, including immune signals and metabolic cues, to direct T cell fate decisions1. Activation of mTOR, comprised of mTORC1 and mTORC2 complexes, delivers an obligatory signal for proper activation and differentiation of effector CD4+ T cells2,3, whereas in the regulatory T cell (Treg) compartment, the Akt-mTOR axis is widely acknowledged as a crucial negative regulator of Treg de novo differentiation4-8 and population expansion9. However, whether mTOR signaling affects the homeostasis and function of Tregs remains largely unexplored. Here we show that mTORC1 signaling is a pivotal positive determinant of Treg function. Tregs have elevated steady-state mTORC1 activity compared to naïve T cells. Signals via T cell receptor (TCR) and IL-2 provide major inputs for mTORC1 activation, which in turn programs suppressive function of Tregs. Disruption of mTORC1 through Treg-specific deletion of the essential component Raptor leads to a profound loss of Treg suppressive activity in vivo and development of a fatal early-onset inflammatory disorder. Mechanistically, Raptor/mTORC1 signaling in Tregs promotes cholesterol/lipid metabolism, with the mevalonate pathway particularly important for coordinating Treg proliferation and upregulation of suppressive molecules CTLA-4 and ICOS to establish Treg functional competency. In contrast, mTORC1 does not directly impact the expression of Foxp3 or anti- and pro-inflammatory cytokines in Tregs, suggesting a non-conventional mechanism for Treg functional regulation. Lastly, we provide evidence that mTORC1 maintains Treg function partly through inhibiting the mTORC2 pathway. Our results demonstrate that mTORC1 acts as a fundamental ‘rheostat’ in Tregs to link immunological signals from TCR and IL-2 to lipogenic pathways and functional fitness, and highlight a central role of metabolic programming of Treg suppressive activity in immune homeostasis and tolerance. We used microarrays to explore the gene expression profiles differentially expressed in regulatory T-cells from wild-type and CD4(cre) x Raptor(fl/fl) mice
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Project description:The mechanistic target of rapamycin mTORC1 is a key regulator of cell metabolism and autophagy. Despite widespread clinical use of mTOR inhibitors, the role of mTORC1 in renal tubular function and kidney homeostasis remains elusive. By utilizing constitutive and inducible deletion of conditional Raptor alleles in renal tubular epithelial cells, we discovered that mTORC1 deficiency caused a marked concentrating defect, loss of tubular cells and slowly progressive renal fibrosis. Transcriptional profiling revealed that mTORC1 maintains renal tubular homeostasis by controlling mitochondrial metabolism and biogenesis as well as transcellular transport processes involved in counter-current multiplication and urine concentration. Although mTORC2 partially compensated the loss of mTORC1, exposure to ischemia and reperfusion injury exaggerated the tubular damage in mTORC1-deficient mice, and caused pronounced apoptosis, diminished proliferation rates and delayed recovery. These findings identify mTORC1 as an essential regulator of tubular energy metabolism and as a crucial component of ischemic stress responses. Pharmacological inhibition of mTORC1 likely affects tubular homeostasis, and may be particularly deleterious if the kidney is exposed to acute injury. Furthermore, the combined inhibition of mTORC1 and mTORC2 may increase the susceptibility to renal damage. Raptor fl/fl*KspCre and Raptor fl/fl animals were sacrificed at P14 before the development of an overt functional phenotype. Kidneys were split in half and immediately snap frozen in liquid nitrogen.
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Project description:Protein post-translational modification (PTM) increases the functional diversity of the proteome and regulates numerous biological processes in eukaryotes. Two types of PTMs, O-linked-acetyl glucosamine modification (O-GlcNAc) and phosphorylation have been identified on the same amino acid, are considered as Yin-Yang modification for their antagonistic function recently. Vernalization, a prolonged cold exposure promoted flowering, is important for grain yield in temperate cereals, such as winter wheat. O-GlcNAcylation on TaGRP2 and phosphorylation on VER2 are involved in regulation of vernalization response (VRN) genes. However, less is known about how plant senses vernalization with general Yin-Yang modifications. Here we report that altering O-GlcNAc signaling by chemical inhibitors could change the vernalization response and affect flowering transition. Furthermore, we enriched O-GlcNAcylated and phosphorylated peptides from winter wheat plumules at different processing time points during vernalization by Lectin weak affinity chromatography (LWAC) and iTRAQ-TiO2, respectively. In total, about 200 O-GlcNAcylated proteins and 124 differential expressed phosphorylated proteins were identified by Mass Spectrum (MS). Based on GO enrichment, the identified O-GlcNAcylated proteins are mainly involved in response to abiotic stimulus and hormone, metabolic processing and gene expression. While dynamic phosphorylated proteins during vernalization participate in translation, transcription and metabolic processing. Of note, 31 proteins with both phosphorylation and O-GlcNAcylation modification were identified. Among them, TaGRP2 was further confirmed to participate in regulation of vernalization promoted flowering. The global modification profiles and genetic data at specific regulator suggested that the dynamic network of O-GlcNAcylation and phosphorylation on the key nodes regulate vernalization response and mediate flowering in wheat.
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Project description:O-GlcNAc is a nutritionally and metabolically relevant post-translational modification on thousands of nucleocytoplas-mic proteins. O-GlcNAcylation level dynamically responds to environmental cues in temporal and spatial dimensions, leading to discrete signaling transductions and physiological effects. Spatiotemporal regulation of O-GlcNAcylation level is essential for O-GlcNAc functional interrogation and manipulation of cell behaviors for desired outcomes, which is yet challenging owing to limited approaches. Here we achieved spatiotemporal O-GlcNAc reduction in live cells by designing a 4-hydroxytamoxifen (4-HT)-triggered O-GlcNAcase (OGA) activation strategy. After rational engineering and optimiza-tion, OGA variants bearing an intein located to different subcellular regions were generated and validated, whose deglyco-sidase activity can be turned on by 4-HT in a time- and dose-dependent manner. Finally, we demonstrated the dual func-tionality of 4-HT on breast cancer cells expressing the engineered OGA, which accelerated cell death with a lower dosage and thus mitigated the likelihood of acquiring drug resistance. Altogether, our strategy facilitates the precise regulation and functional understandings of O-GlcNAcylation in live cells.
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Project description:Naïve T cells respond to antigen stimulation by exiting from quiescence into clonal expansion and functional differentiation, but the control mechanism is elusive. Here we describe that Raptor/mTORC1-dependent metabolic reprogramming is a central determinant of this transitional process. Loss of Raptor abrogates T cell priming and Th2 cell differentiation, although Raptor function is less important for continuous proliferation of actively cycling cells. mTORC1 coordinates multiple metabolic programs in T cells including glycolysis, lipid synthesis and oxidative phosphorylation to mediate antigen-triggered exit from quiescence. mTORC1 further links glucose metabolism to the initiation of Th2 differentiation by orchestrating cytokine receptor expression and cytokine responsiveness. Activation of Raptor/mTORC1 integrates T cell receptor (TCR) and CD28 co-stimulatory signals in antigen-stimulated T cells. Our studies identify a Raptor/mTORC1-dependent pathway linking signal-dependent metabolic reprogramming to quiescence exit, and this in turn coordinates lymphocyte activation and fate decisions in adaptive immunity.
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Project description:The O-N-acetyl-β-D-glucosaminylation, termed O-GlcNAcylation, is an atypical glycosylation corresponding to the transfer of a unique saccharide, the N-acetyl-β-D-glucosamine, on the hydroxyl group of serine and threonine amino acids of nuclear, cytosolic and mitochondrial proteins. Because of its dynamism, its reversibility and the swiftness of GlcNAc moieties transfer, O-GlcNAcylation is akin to phosphorylation and it is able to respond rapidly to both extracellular and intracellular demands. This post-translational modification is highly represented on intracellular proteins (in particular cytosolic, nuclear and mitochondrial proteins), and is involved in almost if not all cellular processes. O-GlcNAcylation is nowadays clearly associated with the etiology of several acquired diseases, in particular diabetes, neuro-degenerative disorders, cardiovascular diseases or cancer. The O-GlcNAcylation rapidly emerged as a major cellular mechanism which compete with phosphorylation in terms of modified proteins and the importance in cellular physiology. The O-GlcNAcylated sites could also correspond to phosphorylated ones; many proteins are modified by both O-GlcNAc and phosphates groups, and these two post-translational modifications could compete to the same or at neighboring sites. However, despite the undeniable role of O-GlcNAcylation in the modulation of almost all cellular processes, its precise function remains still misunderstood, mainly because of the unknown position of O-GlcNAcylation on specific domains of proteins. Thus, the precise localization of O-GlcNAcylated sites remains an indispensable prerequisite for the fine understanding of its biological function. However, mapping the O-GlcNAcylated sites remains laborious, but challenging, because of (i) the low stoichiometry of O-GlcNAcylation; (ii) the ion suppression of the modified peptide by the unmodified peptide present in larger excess; and (iii) the labile β bound between serine or threonine and the O-GlcNAc moiety which is broken during the CID (Collision-Induced Dissociation) fragmentation process, leading to loss of site information. To respond to this biological demand and to overcome these difficulties, enrichment of O-GlcNAc modified proteins and the use of other fragmentation processes like ECD (Electron Capture Dissociation), ETD (Electron Transfer Dissociation), or HCD (High-energy Collisional Dissociation), able to limit the O-GlcNAc loss during the fragmentation, are crucial. Our strategy was an alternative, specific, efficient and selective purification of O-GlcNAc bearing proteins from skeletal muscle cells by the use of the Click chemistry methodology. To extensively map O-GlcNAc sites on proteins, we proposed herein an intensive fractionation of the muscle cell proteome according to solubility, hydrophobicity and isoelectric point of proteins. The method of Click chemistry was achieved on each enriched-fraction containing proteins of interest.
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Project description:The mammalian target of rapamycin complex 1 (mTORC1) is a key nutrient-sensing hub and a master regulator of cellular growth and metabolism. Activation of mTORC1 by amino acids and growth factors requires its recruitment to the lysosomes. Furthermore, lysosomal distribution has been shown to be intimately involved in the control of mTORC1, where localisation of lysosomes near plasma membrane increases mTORC1 activity. However, the underlying mechanisms by which lysosomal positioning impacts on mTORC1 signalling are not well understood. To understand better the spatial associations of mTORC1, we analysed the proximal ‘interactome’ of the constitutive component of mTORC1, Raptor, using BioID2-based proximity labelling and MS-based proteomics.
2021-09-08 | PXD012795 | Pride