bims-meprid Biomed News
on Metabolic-dependent epigenetic reprogramming in differentiation and disease
Issue of 2022‒05‒08
four papers selected by
Alessandro Carrer
Veneto Institute of Molecular Medicine

  1. Trends Endocrinol Metab. 2022 May 01. pii: S1043-2760(22)00059-5. [Epub ahead of print]
      The ability of the immune system to discriminate external stimuli from self-components - namely immune tolerance - occurs through a coordinated cascade of events involving a dense network of immune cells. Among them, CD4+CD25+ T regulatory cells are crucial to balance immune homeostasis and function. Growing evidence supports the notion that energy metabolites can dictate T cell fate and function via epigenetic modifications, which affect gene expression without altering the DNA sequence. Moreover, changes in cellular metabolism couple with activation of immune pathways and epigenetic remodeling to finely tune the balance between T cell activation and tolerance. This Review summarizes these aspects and critically evaluates novel possibilities for developing therapeutic strategies to modulate immune tolerance through metabolism via epigenetic drugs.
    Keywords:  Foxp3; T regulatory cells; epigenetic regulation; immune tolerance; metabolic flexibility
  2. Nat Commun. 2022 May 03. 13(1): 2412
      Human neurodegenerative disorders often exhibit similar pathologies, suggesting a shared aetiology. Key pathological features of Parkinson's disease (PD) are also observed in other neurodegenerative diseases. Pantothenate Kinase-Associated Neurodegeneration (PKAN) is caused by mutations in the human PANK2 gene, which catalyzes the initial step of de novo CoA synthesis. Here, we show that fumble (fbl), the human PANK2 homolog in Drosophila, interacts with PINK1 genetically. fbl and PINK1 mutants display similar mitochondrial abnormalities, and overexpression of mitochondrial Fbl rescues PINK1 loss-of-function (LOF) defects. Dietary vitamin B5 derivatives effectively rescue CoA/acetyl-CoA levels and mitochondrial function, reversing the PINK1 deficiency phenotype. Mechanistically, Fbl regulates Ref(2)P (p62/SQSTM1 homolog) by acetylation to promote mitophagy, whereas PINK1 regulates fbl translation by anchoring mRNA molecules to the outer mitochondrial membrane. In conclusion, Fbl (or PANK2) acts downstream of PINK1, regulating CoA/acetyl-CoA metabolism to promote mitophagy, uncovering a potential therapeutic intervention strategy in PD treatment.
  3. J Adv Res. 2022 03;37 119-131
      Introduction: O-linked β-D-N-acetylglucosamine (O-GlcNAc) modification is a post-translational modification in which a single O-GlcNAc is added to serine or threonine residues in nuclear, cytoplasmic, and mitochondrial proteins, and is involved in a variety of physiological processes.Objectives: In the present study, the role of O-GlcNAcylation in embryo implantation was evaluated. Furthermore, whether O-GlcNAcylation is involved in orchestrating glucose metabolism to influence endometrial cell physiological functions was investigated.
    Methods: Different endometrial tissues were detected using immunohistochemistry. Pregnant mouse models were established to verify molecular expression. O-GlcNAc transferase and aquaporin 3 (AQP3) knockdown were used to detect embryo implantation efficiency in vitro and in vivo. Western blotting and immunofluorescence were used to detect protein expression and stability. Dual luciferase reporter assay and chromatin immunoprecipitation (ChIP) were used to verify the binding transcription factor. Glycolysis was detected using bioenergy analyzer, and metabolites were analyzed using isotope 13C-labeled LC-MS. Metabolic-related genes were determined using RNA sequencing.
    Results: Activation of endometrial hexosamine biosynthetic pathway (HBP) caused elevated O-GlcNAcylation during the window of implantation, affecting endometrial cell function and embryo implantation. Specifically, elevated O-GlcNAcylation increased glucose uptake via glucose transporter 1 (GLUT1) leading to glucose metabolic flow into the pentose phosphate pathways and HBP, which regulate the metabolic reprogramming of endometrial cells. Furthermore, O-GlcNAcylation mediated the intracellular transport of glycerol to support and compensate for glycolysis through regulation of AQP3. Unexpectedly, elevated AQP3 also increased glucose uptake via GLUT1. These processes maintained higher metabolic requirements for endometrial physiology. Furthermore, the transcription factor SP1 specifically bound to the AQP3 promoter region, and O-GlcNAcylation of SP1 increased its stability and transcriptional regulation of AQP3 which is associated with O-GlcNAcylation of SP1.
    Conclusion: Overall, O-GlcNAcylation regulated glucose metabolism in endometrial cells, and AQP3-mediated compensation provides new insights into the communication between glycolysis and O-GlcNAcylation.
    Keywords:  AQP3; Glycolytic metabolism; Implantation; O-GlcNAc modification; SP1
  4. Mitochondrion. 2022 May 02. pii: S1567-7249(22)00041-1. [Epub ahead of print]
      O-GlcNAcylation, a ubiquitous post-translational modification, rapidly modulates protein activity through the reversible addition and removal of O-GlcNAc groups from serine or threonine residues in target proteins, and is involved in multiple metabolic pathways. With the discovery of enzymes and substrates for O-GlcNAc cycling in mitochondria, mitochondrial O-GlcNAc modification and its regulatory role in mitochondrial function deserve extensive attention. Adaptive regulation of the O-GlcNAc cycling in response to energy perturbations is demonstrated to be important in maintaining mitochondrial homeostasis. Dysregulation of O-GlcNAcylation in mitochondria has been associated with various mitochondrial dysfunctions, such as abnormal mitochondrial dynamics, reduced mitochondrial biosynthesis, disruption of the electron transport chain, oxidative stress and the calcium paradox, as well as activation of mitochondrial apoptosis pathways. Here, we outline the current understanding of O-GlcNAc modification in mitochondria and the key discovery of O-GlcNAcylation in regulating mitochondrial network homeostasis. This review will provide insights into targeting mitochondrial O-GlcNAcylation, as well as the mechanisms linking mitochondrial dysfunction and disease.
    Keywords:  Cellular bioenergetics; Metabolism; Mitochondrial homeostasis; Nutrient sensing; O-GlcNAcylation