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Regulation of mitophagy by O-linked N-acetylglucosamine transferase is essential for hematopoietic stem cell maintenance

ABSTRACT: O-linked N-acetylglucosamine (O-GlcNAc) transferase (OGT) catalyzes post-translational modification of target proteins by introducing O-GlcNAc moiety on serine or threonine residues. OGT critically regulates various cellular functions in many cell types. However, its roles in hematopoietic stem and progenitor cells (HSPCs) are totally unknown. Here we report critical roles of OGT in homeostasis of HSPCs. Ogt is highly expressed in HSPCs and its disruption led to their rapid loss with increased reactive oxygen species and apoptosis. In particular, Ogt-deficient HSCs lost quiescence and showed severe defects in self-renewal and long-term repopulation capacities. Interestingly, Ogt-deficient HSCs accumulated defective mitochondria due to impaired mitophagy with decreased key mitophagy regulators, Pink1 and Bnip3, through dysregulation of host cell factor 1 (HCF1)-H3K4me3 pathway, and overexpression of Pink1 rescued impaired mitophagy and numbers of Ogt-deficient HSCs. In summary, our results revealed that OGT plays an essential role in HSC maintenance by assuring mitochondrial quality through mitophagy.

ORGANISM(S): Mus musculus

PROVIDER: GSE116433 | GEO | 2020/12/09

REPOSITORIES: GEO

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TET2 and TET3 regulate GlcNAcylation and H3K4 methylation through OGT and SET1/COMPASS

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

TET2 and TET3 regulate GlcNAcylation and H3K4 methylation through OGT and SET1/COMPASS

2013-02-07 | GSE36620 | GEO

Genome-wide changes in OGT-deficient mouse liver tissue

Project description:Over a billion people suffer from chronic liver diseases worldwide, which often leads to fibrosis and then cirrhosis. Treatments for fibrosis remain experimental, in part because no unifying mechanism has been identified that initiates liver fibrosis. O-linked β-N-acetylglucosamine (O-GlcNAc) transferase (OGT) plays a pro-survival role under stress in many tissues. Here we report that OGT protects against hepatocyte necroptosis and initiation of liver fibrosis. Decreased O-GlcNAc levels were seen in patients with alcoholic liver cirrhosis and in mice with ethanol-induced liver injury. Liver-specific O-GlcNAc transferase (OGT) knockout (OGT-LKO) mice progressed to liver fibrosis at 10 weeks of age. OGT-deficient hepatocytes underwent necroptosis. These findings identify OGT as a key suppressor of hepatocyte necroptosis and OGT-LKO mice may serve as an effective spontaneous genetic model of liver fibrosis.

2019-11-04 | GSE134993 | GEO

Ogt Controls Adult Neurogenesis through Modulating Notch Signaling Activity in Mice

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

Neuronal mitochondria transport Pink1 mRNA via Synaptojanin 2 to support local mitophagy

Project description:PTEN-induced kinase 1 (PINK1) is a very short-lived protein that is required for the removal of damaged mitochondria through Parkin translocation and mitophagy. Because the short half-life of PINK1 limits its ability to be trafficked into neurites, local translation is required for this mitophagy pathway to be active far from the soma. The Pink1 transcript is associated with and cotransported with neuronal mitochondria. In concert with translation, the mitochondrial outer membrane protein Synaptojanin 2 Binding Protein (SYNJ2BP) and Synaptojanin 2 (SYNJ2) are required for tethering Pink1 mRNA to mitochondria via an RNA-binding domain in SYNJ2. This neuron-specific adaptation for local translation of PINK1 provides distal mitochondria with a continuous supply of PINK1 for activation of mitophagy.

2022-01-14 | GSE193443 | GEO

Aspartyl-tRNA synthetase 2 orchestrates iron-sulfur metabolism in hematopoietic stem cells via fine-tuning alternative RNA splicing

Project description:Aspartyl-tRNA synthetase 2 (Dars2) is involved in the regulation of mitochondrial protein synthesis and tissue-specific mitochondrial unfolded protein response (UPRmt). The role of Dars2 in the self-renewal and differentiation of hematopoietic stem cells (HSCs) is unknown. Here we show that knockout (KO) of Dars2 significantly impairs the maintenance of HSCs and progenitor cells (HSPCs) without involving its tRNA synthetase activity. Dars2 KO results in significantly reduced expression of Srsf2/3/6 and impairs multiple events of mRNA alternative splicing (AS). Dars2 directly localizes to Srsf3 labeled spliceosomes in HSPCs and regulates the stability of Srsf3. Dars2-deficient HSPCs exhibit aberrant AS of mTOR and Slc22a17. Dars2 KO greatly suppresses the levels of labile ferrous iron and iron-sulfur cluster containing proteins, which dampens mitochondrial metabolic activity and DNA damage repair pathway in HSPCs. Our study reveals that Dars2 plays an unprecedented role in the iron-sulfur metabolism and maintenance of HSPCs by modulating RNA splicing.

2023-09-26 | PXD045562 | Pride

mTOR hyperactivation in Down Syndrome mediates deficits in autophagy induction, autophagosome formation, and mitophagy

Project description:Down syndrome (DS), a complex genetic disorder caused by chromosome 21 trisomy, is associated with mitochondrial dysfunction leading to the accumulation of damaged mitochondria. Here we report that mitophagy, a form of selective autophagy activated to clear damaged mitochondria is deficient in primary human fibroblasts derived from individuals with DS leading to accumulation of damaged mitochondria with consequent increases in oxidative stress. We identified two molecular bases for this mitophagy deficiency: PINK1/PARKIN impairment and abnormal suppression of macroautophagy. First, strongly downregulated PARKIN and the mitophagic adaptor protein SQSTM1/p62 delays PINK1 activation to impair mitophagy induction after mitochondrial depolarization by CCCP or antimycin A plus oligomycin. Secondly, mTOR is strongly hyper-activated, which globally suppresses macroautophagy induction and the transcriptional expression of proteins critical for autophagosome formation such as ATG7, ATG3 and FOXO1. Notably, inhibition of mTOR complex 1 (mTORC1) and complex 2 (mTORC2) using AZD8055 (AZD) restores autophagy flux, PARKIN/PINK initiation of mitophagy, and the clearance of damaged mitochondria by mitophagy. These results recommend mTORC1-mTORC2 inhibition as a promising candidate therapeutic strategy for Down Syndrome.

2019-06-22 | GSE126910 | GEO

RNA-Seq to evaluate detaining intron splicing upon O-GlcNAc perturbation

Project description:We report the effect of splicing upon O-GlcNAc perturbation with OGT inhibitor or OGA inhibitor. We found that splicing is acutely affected through our phosphoproteomics data when cells are treated with OGT inhibitor. By obtaining the various splicing events that are affected by OGT or OGA inhibition, we found that O-GlcNAc is a major regulator of detained introns splicing. At early time point, we observed highly specific splicing of OGT/OGA detained introns to buffer O-GlcNAc changes. At longer time point, ~80% of the total detained introns are affected by O-GlcNAc perturbation, while the rest of canonical splicing events are only minimally affected (~ 5%).

2020-04-03 | GSE138783 | GEO

Genome wide binding sites of BAP1, HCF1 and OGT

Project description:We report the genome wide binding sites of BAP1, HCF1 and OGT in bone marrow derived macrophages. De-ubiquitinating enzyme BAP1 is mutated in a hereditary cancer syndrome with increased risk of mesothelioma and uveal melanoma. Somatic BAP1 mutations occur in various malignancies. We show that mouse Bap1 gene deletion is lethal during embryogenesis, but systemic or hematopoietic-restricted deletion in adults recapitulates features of human myelodysplastic syndrome (MDS). Knockin mice expressing BAP1 with a 3xFlag tag revealed that BAP1 interacts with host cell factor–1 (HCF-1), O-linked N-acetylglucosamine transferase (OGT), and the polycomb group proteins ASXL1 and ASXL2 in vivo. OGT and HCF-1 levels were decreased by Bap1 deletion, indicating a critical role for BAP1 in stabilizing these epigenetic regulators. Human ASXL1 is mutated frequently in chronic myelomonocytic leukemia (CMML) so an ASXL/BAP1 complex may suppress CMML. A BAP1 catalytic mutation found in a MDS patient implies that BAP1 loss of function has similar consequences in mice and humans. For BAP1, bone marrow derived macrophages were used differentiated from bone marrow cells of BAP1-3X Flag Tagged KI mice we generated. For OGT and HCF1, bone marrow derived macrophages were used from BAP1 WT mice.

2012-11-07 | E-GEOD-40723 | biostudies-arrayexpress

OGT, H2B S112GlcNAc, TET2 ChIP-seq results

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

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