Genome-wide changes in OGT-deficient mouse liver tissue
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE134993 | GEO | 2019/11/04
REPOSITORIES: GEO
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Project description:O-GlcNAcylation is a reversible post-translational modification controlled by the activity of two enzymes, O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA). In the liver, O-GlcNAcylation has emerged as an important regulatory mechanism underlying normal liver physiology and metabolic disease.To address whether OGT acts as a critical hepatic nutritional node, mice with a constitutive hepatocyte-specific deletion of OGT (OGTLKO) were generated.Analyses of 4-week-old OGTLKO mice revealed significant oxidative and endoplasmic reticulum stress, and DNA damage, together with inflammation and fibrosis, in the liver. Susceptibility to oxidative and endoplasmic reticulum stress- induced apoptosis was also elevated in OGTLKO hepatocytes. Although OGT expression was partially recovered in the liver of 8- week-old OGTLKO mice, hepatic injury and fibrosis were not rescued but rather worsened with time. Interestingly, weaning of OGTLKO mice on a ketogenic diet (low carbohydrate, high fat) fully prevented the hepatic alterations induced by OGT deletion, indicating that reduced carbohydrate intake protects an OGT-deficient liver. These findings pinpoint OGT as a key mediator of hepatocyte homeostasis and survival upon carbohydrate intake and validate OGTLKO mice as a valuable model for assessing therapeutical approaches of advanced liver fibrosis.
2024-03-12 | GSE261136 | GEO
Project description:We studied the role of the post-translational modification called O-GlcNAcylation during liver regeneration. Here we generated O-GlcNAc transferase (OGT-KO) and O-GlcNAcase (OGA-KO) hepatocyte-specific knock-out mice. 70% partial hepatectomy (PHX) was performed to induce liver regeneration. We showed that OGA-KO mice had normal liver regeneration whereas OGT-KO mice had a defect in the termination of liver regeneration.
2022-02-25 | GSE188882 | GEO
Project description:O-linked N-acetylglucosamine (O-GlcNAc ) transferase (OGT) activity is essential for embryonic stem (ES) cell viability and mouse development. OGT is present in both cytoplasm and nucleus of different cell types and mediates serine or threonine glycosylation. The Ogt gene locus resides on the X-chromosome and its activity is required for the viability of male ES cells. Using Ogt conditional knock out (KO) ES cells it was shown the failure of establishing stable KO ES clones further suggesting that Ogt activity is required for ES cell self-renewal and pluripotency. For understanding these changes, we performed global gene expression upon silencing of Ogt mediated by esiRNA in mouse Embryonic Stem Cells. Total RNA was extracted from E14 ES cells (derived from Ola129 mice) transiently transfected with Ogt specific and control esiRNA oligos 48 hrs. post-transfection.
2013-01-06 | E-GEOD-39321 | biostudies-arrayexpress
Project description:TET proteins convert 5-methylcytosine to 5-hydroxymethylcytosine, an emerging dynamic epigenetic state of DNA that can influence transcription. Evidence has linked TET1 function to epigenetic repression complexes, yet mechanistic information, especially for the TET2 and TET3 proteins, remains limited. Here, we show a direct interaction of TET2 and TET3 with O-GlcNAc transferase (OGT). OGT does not appear to influence hmC activity, rather TET2 and TET3 promote OGT activity. TET2/3-OGT co-localize on chromatin at active promoters enriched for H3K4me3 and reduction of either TET2/3 or OGT activity results in a direct decrease in H3K4me3 and concomitant decreased transcription. Further, we show that Host Cell Factor 1 (HCF1), a component of the H3K4 methyltransferase SET1/COMPASS complex, is a specific GlcNAcylation target of TET2/3-OGT, and modification of HCF1 is important for the integrity of SET1/COMPASS. Additionally, we find both TET proteins and OGT activity promote binding of the SET1/COMPASS H3K4 methyltransferase, SETD1A, to chromatin. Finally, studies in Tet2 knockout mouse bone marrow tissue extend and support the data as decreases are observed of global GlcNAcylation and also of H3K4me3, notably at several key regulators of haematopoiesis. Together, our results unveil a step-wise model, involving TET-OGT interactions, promotion of GlcNAcylation, and influence on H3K4me3 via SET1/COMPASS, highlighting a novel means by which TETs may induce transcriptional activation. ChIP-Seq experiments were performed on Illumina HiScanSQ sequencer in wild-type HEK293T cells for H3K4me3 histone marks, O-GlcNAc and HCF1, for HT-TET2, HT-TET3 and HT-OGT in HEK293T cells overexpressing those three fusion proteins and in TET2 Kd HEK293T cells for H3K4me3 histone marks. ChIP-Seqs were also performed in mouse bone marrow tissues for H3K4me3 histone marks, O-GlcNAc, endogenous Tet2 and in Tet2 Ko bone marrow tissues for H3K4me3 histone marks.
2013-02-07 | E-GEOD-36620 | biostudies-arrayexpress
Project description:OGT (O-GlcNAc transferase) is the distinctive enzyme responsible for catalyzing O-GlcNAc to the serine or threonine residues of thousands of cytoplasm and nuclear proteins that are involved in DNA damage, RNA splicing, and transcription preinitiation and initiation complex assembly. However, the molecular mechanism by OGT regulating gene transcription remains elusive. Using proximity labeling based mass spectrometry, we searched for functional partners of OGT and found that Dot1L, the conserved and unique histone methyltransferase mediated histone H3 lys79 methylation required for gene transcription, DNA damage repair, cell proliferation, and embryo development, interacts with OGT. Although this specific interaction does not regulate the enzymatic activity of Dot1L, it facilitates OGT-dependent histones O-GlcNAcylation. Moreover, OGT associates with Dot1L at transcription start sites, and depleting Dot1L decreased OGT associated with chromatin globally. Notably, downregulation of Dot1L reduces the levels of histone H2B S112 O-GlcNAcylation and histone H2B K120 ubiquitination in vivo, which are associated with gene transcription regulation. Taken together, these results reveal a Dot1L-dependent O-GlcNAcylation of chromatin.
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Project description:TET2 directly interacts with OGT, which is important for the chromatin association of OGT in vivo. Although this specific interaction does not regulate the enzymatic activity of TET2, it facilitates OGT-dependent histone O-GlcNAcylation. Moreover, OGT associates with TET2 at transcription starting sites (TSS). Down-regulation of TET2 reduces the amount of H2B S112 GlcNAc marks in vivo, which are associated with gene transcription regulation. We found that OGT interacts with TET2 tightly. Using ChIP-seq with specific antibodies, we tested the co-localization of TET2 and OGT in genome level.
2012-12-11 | E-GEOD-41720 | biostudies-arrayexpress
Project description:Nucleocytoplasmic O-linked N-acetylglucosamine (O-GlcNAc) is an essential post-translational modification that is installed to thousands of protein substrates by O-GlcNAc transferase (OGT). Substrate selection by OGT and its isoforms is primarily mediated by the tetratricopeptide repeat (TPR) domain, yet the impact of truncations to the TPR domain on substrate and glycosite selection remains unresolved. Here, we report the effects of TPR truncations on the substrate and glycosite selection of OGT against the model protein GFP-JunB and the surrounding O-GlcNAc proteome in U2OS cells. Truncation of the TPR domain of OGT maintains glycosyltransferase activity but alters subcellular localization in cells. Examination of the glycoproteome across the TPR truncations revealed the broadest substrate activity from the canonical nucleocytoplasmic OGT, with the greatest changes in O-GlcNAc occurring on proteins associated with mRNA splicing processes. Glycosite analysis revealed alterations to the O-GlcNAc consensus sequence globally and differential glycosite selectivity on GFP-JunB as a function of the OGT TPR isoform. This dataset provides a foundation to analyze how perturbations to the TPR domain and expression of OGT isoforms affects the glycosylation of substrates, which will be critical for future protein engineering of OGT, the biology of OGT isoforms, and diseases associated with the TPR domain of OGT.
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Project description:O-linked N-acetylglucosamine (O-GlcNAc ) transferase (OGT) activity is essential for embryonic stem (ES) cell viability and mouse development. OGT is present in both cytoplasm and nucleus of different cell types and mediates serine or threonine glycosylation. The Ogt gene locus resides on the X-chromosome and its activity is required for the viability of male ES cells. Using Ogt conditional knock out (KO) ES cells it was shown the failure of establishing stable KO ES clones further suggesting that Ogt activity is required for ES cell self-renewal and pluripotency. For understanding these changes, we performed global gene expression upon silencing of Ogt mediated by esiRNA in mouse Embryonic Stem Cells.
2013-01-06 | GSE39321 | GEO
Project description:Appetite control is key to combat obesity in an over-nutritious environment. Whether and how over-nutrition induces hyperphagia and obesity through the adipose-to-brain axis is unclear. O-linked beta-D-N-acetylglucosamine (O-GlcNAc) transferase (OGT) couples nutrient cues to O-GlcNAcylation of intracellular proteins at serine/threonine residues. Here we show that adipocyte OGT is essential for high fat diet-induced hyperphagia, but is dispensable for baseline food intake. Adipocyte OGT stimulates hyperphagia by transcriptional activation of de novo lipid desaturation and accumulation of anandamide (AEA), an endogenous appetite-inducing cannabinoid (CB). Pharmacological manipulation of peripheral CB1 signaling regulates hyperphagia in an adipocyte OGT-dependent manner. These findings define adipocyte OGT as a fat sensor that regulates peripheral lipid signals, and uncover an unexpected adipose-to-brain axis that induces hyperphagia and obesity.
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Project description:Ogt catalyzed O-linked N-acetylglucosamine (O-GlcNAcylation, O-GlcNAc) plays an important function in diverse biological processes and diseases. However, the roles of Ogt in regulating neurogenesis remain largely unknown. Here, we show that Ogt deficiency or depletion in adult neural stem cells (aNSCs) leads to the diminishment of aNSCs pool and the aberrant neurogenesis, and consequently impairs cognitive function of adult mice. RNA sequencing reveals that Ogt deficiency alters the transcription of genes relating to cell cycle, neurogenesis, and neuronal development. Mechanistic studies show that Ogt directly interacts with Notch1 and catalyzes the O-GlcNAc modification of Notch TM/ICD fragment. The decreased O-GlcNAc modification of TM/ICD increases the binding of E3 ubiquitin ligase Itch to TM/ICD and promotes its degradation. Itch knockdown rescues neurogenic defects in Ogt-deficient mice. OGT also regulates human cortical neurogenesis in forebrain organoids derived from induced pluripotent stem cells. Our findings reveal the essential roles and mechanisms of Ogt and O-GlcNAc modification in regulating mammalian neurogenesis and cognition.
2020-12-15 | GSE163141 | GEO