bims-meprid Biomed News
on Metabolic-dependent epigenetic reprogramming in differentiation and disease
Issue of 2023‒01‒15
five papers selected by
Alessandro Carrer
Veneto Institute of Molecular Medicine

  1. Reproduction. 2023 Jan 01. pii: REP-22-0302. [Epub ahead of print]
      Maternal obesity can impair offspring metabolic health, however the precise mechanism underpinning programming is unknown. Ten-Eleven translocase (TET) enzymes demethylate DNA using the TCA cycle intermediary α-ketoglutarate and may be involved in programming offspring health. Whether TETs are disrupted by maternal obesity is unknown. 5-6 week old C57Bl/6 female mice were fed a control diet (CD; 6% fat, n=175) or a high-fat diet (HFD; 21% fat, n=158) for six weeks. After superovulation oocytes were collected for metabolic assessment, or females were mated and zygotes cultured for embryo development, foetal growth, and assessment of global DNA methylation (5mC, 5hmC, 5fC and 5caC) in the 2-cell embryo. Zygotes collected from superovulated CBAF1 females were cultured in media containing α-ketoglutarate (0mM, 1.4mM, 3.5mM, or 14.0mM) or with 2-hydroxyglutarate (2HG) (0mM or 20mM), a competitive inhibitor of α-ketoglutarate, with methylation and blastocyst differentiation assessed. After HFD, oocytes showed increased pyruvate oxidation and intracellular ROS, with no changes in Tet3 expression, while 2-cell embryo global 5hmC DNA methylation was reduced and 5fC increased. Embryos cultured with 1.4 mM α-ketoglutarate had decreased 2-cell 5mC, whilst 14.0mM α-ketoglutarate increased the 5hmC:5mC ratio. In contrast supplementation with 20 mM 2HG increased 5mC and decreased the 5fC:5mC and 5caC:5mC ratios. α-ketoglutarate up to 3.5mM did not alter embryo development, whilst culturing in 14.0mM α-ketoglutarate blocked development at the 2-cell. Culture with 2HG delayed embryo development past the 4-cell and decreased blastocyst total cell number. In conclusion, disruptions in metabolic intermediates in the preimplantation embryo may provide a link between maternal obesity and programming offspring for ill health.
  2. Cell. 2022 Dec 30. pii: S0092-8674(22)01529-X. [Epub ahead of print]
      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.
    Keywords:  EZH2; O-GlcNAc; O-GlcNAc transferase; RNA; Wnt signaling; aptamer; post-translational modification; riboswitch; transcriptome; β-catenin
  3. Cell Rep. 2023 Jan 12. pii: S2211-1247(22)01891-5. [Epub ahead of print]42(1): 111987
      T cell activation, proliferation, function, and differentiation are tightly linked to proper metabolic reprogramming and regulation. By using [U-13C]glucose tracing, we reveal a critical role for GOT1 in promoting CD8+ T cell effector differentiation and function. Mechanistically, GOT1 enhances proliferation by maintaining intracellular redox balance and serine-mediated purine nucleotide biosynthesis. Further, GOT1 promotes the glycolytic programming and cytotoxic function of cytotoxic T lymphocytes via posttranslational regulation of HIF protein, potentially by regulating the levels of α-ketoglutarate. Conversely, genetic deletion of GOT1 promotes the generation of memory CD8+ T cells.
    Keywords:  CP: Metabolism; GOT1; HIF; NADH/NAD; effector and memory CD8(+) T cell; glucose; glutamate; serine
  4. Nat Rev Mol Cell Biol. 2023 Jan 12.
      Traditional views of cellular metabolism imply that it is passively adapted to meet the demands of the cell. It is becoming increasingly clear, however, that metabolites do more than simply supply the substrates for biological processes; they also provide critical signals, either through effects on metabolic pathways or via modulation of other regulatory proteins. Recent investigation has also uncovered novel roles for several metabolites that expand their signalling influence to processes outside metabolism, including nutrient sensing and storage, embryonic development, cell survival and differentiation, and immune activation and cytokine secretion. Together, these studies suggest that, in contrast to the prevailing notion, the biochemistry of a cell is frequently governed by its underlying metabolism rather than vice versa. This important shift in perspective places common metabolites as key regulators of cell phenotype and behaviour. Yet the signalling metabolites, and the cognate targets and transducers through which they signal, are only beginning to be uncovered. In this Review, we discuss the emerging links between metabolism and cellular behaviour. We hope this will inspire further dissection of the mechanisms through which metabolic pathways and intermediates modulate cell function and will suggest possible drug targets for diseases linked to metabolic deregulation.
  5. J Biol Chem. 2023 Jan 07. pii: S0021-9258(23)00019-4. [Epub ahead of print] 102887
      The O-linked N-acetylglucosamine (O-GlcNAc) transferase (OGT) mediates intracellular O-GlcNAcylation modification. O-GlcNAcylation occurs on Ser/Thr residues and is important for numerous physiological processes. OGT is essential for dividing mammalian cells, and is involved in many human diseases; however, many of its fundamental substrates during cell division remain unknown. Here we focus on the effect of OGT on polo-like kinase 1 (PLK1), a mitotic master kinase that governs DNA replication, mitotic entry, chromosome segregation, and mitotic exit. We show that PLK1 interacts with OGT and is O-GlcNAcylated. By utilizing stepped collisional energy/higher-energy collisional dissociation (sceHCD) mass spectrometry (MS), we found a peptide fragment of PLK1 that is modified by O-GlcNAc. Further mutation analysis of PLK1 shows that the T291A mutant decreases O-GlcNAcylation. Interestingly, T291N is a uterine carcinoma mutant in the TCGA database. Our biochemical assays demonstrate that T291A and T291N both increase PLK1 stability. Using stable H2B-GFP cells, we found that PLK1-T291A and -T291N mutants display chromosome segregation defects, and result in misaligned and lagging chromosomes. In mouse xenograft models, we demonstrate that the O-GlcNAc-deficient PLK1-T291A and -T291N mutants enhance uterine carcinoma in animals. Hence, we propose that OGT partially exerts its mitotic function through O-GlcNAcylation of PLK1, which might be one mechanism by which elevated levels of O-GlcNAc promote tumorigenesis.
    Keywords:  O-GlcNAc; PLK1; mitosis; ubiquitination; uterine carcinoma