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Frontiers in Immunology 2024Idiopathic pulmonary fibrosis (IPF) is a chronic pulmonary disease that is characterized by an excessive accumulation of extracellular matrix (ECM) proteins (e.g....
BACKGROUND
Idiopathic pulmonary fibrosis (IPF) is a chronic pulmonary disease that is characterized by an excessive accumulation of extracellular matrix (ECM) proteins (e.g. collagens) in the parenchyma, which ultimately leads to respiratory failure and death. While current therapies exist to slow the progression, no therapies are available to resolve fibrosis.
METHODS
We characterized the O-linked N-Acetylglucosamine (O-GlcNAc) transferase (OGT)/O-GlcNAc axis in IPF using single-cell RNA-sequencing (scRNA-seq) data and human lung sections and isolated fibroblasts from IPF and non-IPF donors. The underlying mechanism(s) of IPF were further investigated using multiple experimental models to modulate collagen expression and accumulation by genetically and pharmacologically targeting OGT. Furthermore, we hone in on the transforming growth factor-beta (TGF-β) effector molecule, Smad3, by co-expressing it with OGT to determine if it is modified and its subsequent effect on Smad3 activation.
RESULTS
We found that OGT and O-GlcNAc levels are upregulated in patients with IPF compared to non-IPF. We report that the OGT regulates collagen deposition and fibrosis resolution, which is an evolutionarily conserved process demonstrated across multiple species. Co-expression of OGT and Smad3 showed that Smad3 is O-GlcNAc modified. Blocking OGT activity resulted in decreased phosphorylation at Ser-423/425 of Smad3 attenuating the effects of TGF-β1 induced collagen expression/deposition.
CONCLUSION
OGT inhibition or knockdown successfully blocked and reversed collagen expression and accumulation, respectively. Smad3 is discovered to be a substrate of OGT and its O-GlcNAc modification(s) directly affects its phosphorylation state. These data identify OGT as a potential target in pulmonary fibrosis resolution, as well as other diseases that might have aberrant ECM/collagen accumulation.
Topics: Idiopathic Pulmonary Fibrosis; Humans; N-Acetylglucosaminyltransferases; Collagen; Animals; Mice; Smad3 Protein; Fibroblasts; Lung; Male; Cells, Cultured
PubMed: 38665916
DOI: 10.3389/fimmu.2024.1387197 -
Research Square Apr 2024GABAergic transmission is influenced by post-translational modifications, like phosphorylation, impacting channel conductance, allosteric modulator sensitivity, and...
GABAergic transmission is influenced by post-translational modifications, like phosphorylation, impacting channel conductance, allosteric modulator sensitivity, and membrane trafficking. O-GlcNAcylation is a post-translational modification involving the O-linked attachment of β-N-acetylglucosamine on serine/threonine residues. Previously we reported an acute increase in O-GlcNAcylation elicits a long-term depression of evoked GABAR inhibitory post synaptic currents (eIPSCs) onto hippocampal principal cells. Importantly, O-GlcNAcylation and phosphorylation can co-occur or compete for the same residue; whether they interact in modulating GABAergic IPSCs is unknown. We tested this by recording IPSCs from hippocampal principal cells and pharmacologically increased O-GlcNAcylation, before or after increasing serine phosphorylation using the adenylate cyclase activator, forskolin. Although forskolin had no significant effect on baseline eIPSC amplitude, we found that a prior increase in O-GlcNAcylation unmasks a forskolin-dependent increase in eIPSC amplitude, reversing the O-GlcNAc-induced eIPSC depression. Inhibition of adenylate cyclase or protein kinase A did not prevent the potentiating effect of forskolin, indicating serine phosphorylation is not the mechanism. Surprisingly, increasing O-GlcNAcylation also unmasked a potentiating effect of the neurosteroids 5α-pregnane-3α,21-diol-20-one (THDOC) and progesterone on eIPSC amplitude, mimicking forskolin. Our findings show under conditions of heightened O-GlcNAcylation, the neurosteroid site on synaptic GABARs is accessible to agonists, permitting strengthening of synaptic inhibition.
PubMed: 38659738
DOI: 10.21203/rs.3.rs-4140038/v1 -
Nature Communications Apr 2024Poly-β-(1-6)-N-acetylglucosamine (PNAG) is an important vaccine target, expressed on many pathogens. A critical hurdle in developing PNAG based vaccine is that the...
Poly-β-(1-6)-N-acetylglucosamine (PNAG) is an important vaccine target, expressed on many pathogens. A critical hurdle in developing PNAG based vaccine is that the impacts of the number and the position of free amine vs N-acetylation on its antigenicity are not well understood. In this work, a divergent strategy is developed to synthesize a comprehensive library of 32 PNAG pentasaccharides. This library enables the identification of PNAG sequences with specific patterns of free amines as epitopes for vaccines against Staphylococcus aureus (S. aureus), an important human pathogen. Active vaccination with the conjugate of discovered PNAG epitope with mutant bacteriophage Qβ as a vaccine carrier as well as passive vaccination with diluted rabbit antisera provides mice with near complete protection against infections by S. aureus including methicillin-resistant S. aureus (MRSA). Thus, the comprehensive PNAG pentasaccharide library is an exciting tool to empower the design of next generation vaccines.
Topics: Animals; Staphylococcal Infections; Mice; Staphylococcus aureus; Rabbits; Staphylococcal Vaccines; Female; Methicillin-Resistant Staphylococcus aureus; Acetylglucosamine; Humans; Epitopes; Mice, Inbred BALB C
PubMed: 38658531
DOI: 10.1038/s41467-024-47457-4 -
Cell Death & Disease Apr 2024This study aimed to elucidate the role of O-GlcNAc cycling in 6-hydroxydopamine (6-OHDA)-induced Parkinson's disease (PD)-like neurodegeneration and the underlying...
This study aimed to elucidate the role of O-GlcNAc cycling in 6-hydroxydopamine (6-OHDA)-induced Parkinson's disease (PD)-like neurodegeneration and the underlying mechanisms. We observed dose-dependent downregulation of O-GlcNAcylation, accompanied by an increase in O-GlcNAcase following 6-OHDA treatment in both mouse brain and Neuro2a cells. Interestingly, elevating O-GlcNAcylation through glucosamine (GlcN) injection provided protection against PD pathogenesis induced by 6-OHDA. At the behavioral level, GlcN mitigated motor deficits induced by 6-OHDA, as determined using the pole, cylinder, and apomorphine rotation tests. Furthermore, GlcN attenuated 6-OHDA-induced neuroinflammation and mitochondrial dysfunction. Notably, augmented O-GlcNAcylation, achieved through O-GlcNAc transferase (OGT) overexpression in mouse brain, conferred protection against 6-OHDA-induced PD pathology, encompassing neuronal cell death, motor deficits, neuroinflammation, and mitochondrial dysfunction. These collective findings suggest that O-GlcNAcylation plays a crucial role in the normal functioning of dopamine neurons. Moreover, enhancing O-GlcNAcylation through genetic and pharmacological means could effectively ameliorate neurodegeneration and motor impairment in an animal model of PD. These results propose a potential strategy for safeguarding against the deterioration of dopamine neurons implicated in PD pathogenesis.
Topics: Animals; Oxidopamine; Mice; N-Acetylglucosaminyltransferases; Parkinson Disease; Mice, Inbred C57BL; Male; Glucosamine; Dopaminergic Neurons; Mitochondria; Acetylglucosamine; Brain; beta-N-Acetylhexosaminidases; Disease Models, Animal
PubMed: 38654003
DOI: 10.1038/s41419-024-06670-1 -
Frontiers in Physiology 2024is a hypermetamorphic insect whose adults feed on oilseed rape. However, due to a shortage of effective and appropriate endogenous references, studies on molecular...
is a hypermetamorphic insect whose adults feed on oilseed rape. However, due to a shortage of effective and appropriate endogenous references, studies on molecular functional genes in , have been tremendously limited. In this study, ten internal reference genes (, , , , , , , , and ) were tested and assessed under four selected treatments including adult ages, adult tissues, temperatures, and sex by RT-qPCR based on five methods (Ct value, geNorm, NormFinder, BestKeeper and RefFinder). Our findings showed that and were the most optimal internal reference gene combination for gene expression during various adult ages and under diverse temperatures; The combination of and was recommended to test gene transcription levels under different adult tissues. and were the best reference genes in male and female adults. and were the most appropriate reference gene pair to estimate gene expression levels under four different tested backgrounds. The relative transcript levels of a uridine diphosphate (UDP)-N-acetylglucosamine-pyrophosphorylase (), varied greatly according to normalization with the two most- and least-suited reference genes. This study will lay the basis for further molecular physiology and biochemistry studies in , such as development, reproduction, sex differentiation, cold and heat resistance.
PubMed: 38651047
DOI: 10.3389/fphys.2024.1345836 -
International Journal of Endocrinology 2024To investigate the effects of acupuncture on endogenous metabolites in the liver of type 2 diabetes mellitus (T2DM) with nonalcoholic fatty liver disease (NAFLD)...
INTRODUCTION
To investigate the effects of acupuncture on endogenous metabolites in the liver of type 2 diabetes mellitus (T2DM) with nonalcoholic fatty liver disease (NAFLD) mice-based metabolomics.
METHODS
Proton nuclear magnetic resonance (H-NMR) metabolomics combined with multivariate statistical analysis and univariate analysis were used to analyze the changes of endogenous metabolites in the liver of mice in each group and to provide new clinical ideas for acupuncture in the treatment of glycolipid metabolism disorders caused by T2DM and NAFLD.
RESULTS
After 4 weeks of continuous treatment, fasting blood glucose (FBG), insulin (INS), total cholesterol (TC), and triglyceride (TG) decreased significantly in mice in the acupuncture treatment group (ATG), and the content of liver glycogen increased significantly. Based on H-NMR metabolomic analysis, a total of 47 metabolites were identified in the liver of T2DM with NAFLD mice, of which eight metabolites: UDP-N-acetylglucosamine, adenosine, glutamate, isoleucine, ATP, 3-hydroxybutyric acid, NADP, and leucine were significantly altered by acupuncture treatment. Through the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, it is found that acupuncture has an intervention effect on five metabolic pathways, mainly involving amino acid metabolism, energy metabolism, and oxidative stress.
CONCLUSION
Our study shows that acupuncture can regulate the liver metabolism mode of T2DM in NAFLD mice. It can reduce blood glucose and lipid accumulation in the liver, and these findings provide a new idea and theoretical basis for acupuncture in the treatment of diseases related to glucose and lipid metabolism.
PubMed: 38633528
DOI: 10.1155/2024/5568337 -
Nature Communications Apr 2024Malnutrition underlies almost half of all child deaths globally. Severe Acute Malnutrition (SAM) carries unacceptable mortality, particularly if accompanied by infection... (Randomized Controlled Trial)
Randomized Controlled Trial
Malnutrition underlies almost half of all child deaths globally. Severe Acute Malnutrition (SAM) carries unacceptable mortality, particularly if accompanied by infection or medical complications, including enteropathy. We evaluated four interventions for malnutrition enteropathy in a multi-centre phase II multi-arm trial in Zambia and Zimbabwe and completed in 2021. The purpose of this trial was to identify therapies which could be taken forward into phase III trials. Children of either sex were eligible for inclusion if aged 6-59 months and hospitalised with SAM (using WHO definitions: WLZ <-3, and/or MUAC <11.5 cm, and/or bilateral pedal oedema), with written, informed consent from the primary caregiver. We randomised 125 children hospitalised with complicated SAM to 14 days treatment with (i) bovine colostrum (n = 25), (ii) N-acetyl glucosamine (n = 24), (iii) subcutaneous teduglutide (n = 26), (iv) budesonide (n = 25) or (v) standard care only (n = 25). The primary endpoint was a composite of faecal biomarkers (myeloperoxidase, neopterin, α-antitrypsin). Laboratory assessments, but not treatments, were blinded. Per-protocol analysis used ANCOVA, adjusted for baseline biomarker value, sex, oedema, HIV status, diarrhoea, weight-for-length Z-score, and study site, with pre-specified significance of P < 0.10. Of 143 children screened, 125 were randomised. Teduglutide reduced the primary endpoint of biomarkers of mucosal damage (effect size -0.89 (90% CI: -1.69,-0.10) P = 0.07), while colostrum (-0.58 (-1.4, 0.23) P = 0.24), N-acetyl glucosamine (-0.20 (-1.01, 0.60) P = 0.67), and budesonide (-0.50 (-1.33, 0.33) P = 0.32) had no significant effect. All interventions proved safe. This work suggests that treatment of enteropathy may be beneficial in children with complicated malnutrition. The trial was registered at ClinicalTrials.gov with the identifier NCT03716115.
Topics: Animals; Cattle; Humans; Infant; Acetylglucosamine; Biomarkers; Budesonide; Edema; Intestinal Diseases; Malnutrition; Severe Acute Malnutrition; Zambia; Zimbabwe; Child, Preschool
PubMed: 38632262
DOI: 10.1038/s41467-024-45528-0 -
International Journal of Molecular... Mar 2024The clinical severity of multiple sclerosis (MS), an autoimmune disorder of the central nervous system, is thought to be determined by environmental and genetic factors...
The clinical severity of multiple sclerosis (MS), an autoimmune disorder of the central nervous system, is thought to be determined by environmental and genetic factors that have not yet been identified. In a recent genome-wide association study (GWAS), a single nucleotide polymorphism (SNP), rs10191329, has been associated with MS severity in two large independent cohorts of patients. Different approaches were followed by the authors to prioritize the genes that are transcriptionally regulated by such an SNP. It was concluded that the identified SNP regulates a group of proximal genes involved in brain resilience and cognitive abilities rather than immunity. Here, by conducting an alternative strategy for gene prioritization, we reached the opposite conclusion. According to our re-analysis, the main target of rs10191329 is N-Acetylglucosamine Kinase (NAGK), a metabolic gene recently shown to exert major immune functions via the regulation of the nucleotide-binding oligomerization domain-containing protein 2 (NOD2) pathway. To gain more insights into the immunometabolic functions of NAGK, we analyzed the currently known list of NAGK protein partners. We observed that NAGK integrates a dense network of human proteins that are involved in glucose metabolism and are highly expressed by classical monocytes. Our findings hold potentially major implications for the understanding of MS pathophysiology.
Topics: Humans; Multiple Sclerosis; Genome-Wide Association Study; Phosphotransferases (Alcohol Group Acceptor); Autoimmune Diseases; Acetylglucosamine
PubMed: 38612613
DOI: 10.3390/ijms25073803 -
Leukemia May 2024TNF receptor associated factor 6 (TRAF6) is an E3 ubiquitin ligase that has been implicated in myeloid malignancies. Although altered TRAF6 expression is observed in...
TNF receptor associated factor 6 (TRAF6) is an E3 ubiquitin ligase that has been implicated in myeloid malignancies. Although altered TRAF6 expression is observed in human acute myeloid leukemia (AML), its role in the AML pathogenesis remains elusive. In this study, we showed that the loss of TRAF6 in AML cells significantly impairs leukemic function in vitro and in vivo, indicating its functional importance in AML subsets. Loss of TRAF6 induces metabolic alterations, such as changes in glycolysis, TCA cycle, and nucleic acid metabolism as well as impaired mitochondrial membrane potential and respiratory capacity. In leukemic cells, TRAF6 expression shows a positive correlation with the expression of O-linked N-acetylglucosamine (O-GlcNAc) transferase (OGT), which catalyzes the addition of O-GlcNAc to target proteins involved in metabolic regulation. The restoration of growth capacity and metabolic activity in leukemic cells with TRAF6 loss, achieved through either forced expression of OGT or pharmacological inhibition of O-GlcNAcase (OGA) that removes O-GlcNAc, indicates the significant role of O-GlcNAc modification in the TRAF6-related cellular and metabolic dynamics. Our findings highlight the oncogenic function of TRAF6 in leukemia and illuminate the novel TRAF6/OGT/O-GlcNAc axis as a potential regulator of metabolic reprogramming in leukemogenesis.
Topics: Humans; Leukemia, Myeloid, Acute; Animals; Mice; Disease Progression; TNF Receptor-Associated Factor 6; N-Acetylglucosaminyltransferases; Glycolysis; Cell Line, Tumor; Metabolic Reprogramming; Intracellular Signaling Peptides and Proteins
PubMed: 38609495
DOI: 10.1038/s41375-024-02245-3 -
Targeting Fatty Acid Desaturase I Inhibits Renal Cancer Growth Via ATF3-mediated ER Stress Response.BioRxiv : the Preprint Server For... Mar 2024Monounsaturated fatty acids (MUFAs) play a pivotal role in maintaining endoplasmic reticulum (ER) homeostasis, an emerging hallmark of cancer. However, the role of...
Monounsaturated fatty acids (MUFAs) play a pivotal role in maintaining endoplasmic reticulum (ER) homeostasis, an emerging hallmark of cancer. However, the role of polyunsaturated fatty acid (PUFAs) desaturation in persistent ER stress driven by oncogenic abnormalities remains elusive. Fatty Acid Desaturase 1 (FADS1) is a rate-limiting enzyme controlling the bioproduction of long-chain PUFAs. Our previous research has demonstrated the significant role of FADS1 in cancer survival, especially in kidney cancers. We explored the underlying mechanism in this study. We found that pharmacological inhibition or knockdown of the expression of FADS1 effectively inhibits renal cancer cell proliferation and induces cell cycle arrest. The stable knockdown of FADS1 also significantly inhibits tumor formation . Mechanistically, we show that while FADS1 inhibition induces ER stress, its expression is also augmented by ER-stress inducers. Notably, FADS1-inhibition sensitized cellular response to ER stress inducers, providing evidence of FADS1's role in modulating the ER stress response in cancer cells. We show that, while FADS1 inhibition-induced ER stress leads to activation of ATF3, ATF3-knockdown rescues the FADS1 inhibition-induced ER stress and cell growth suppression. In addition, FADS1 inhibition results in the impaired biosynthesis of nucleotides and decreases the level of UPD-N-Acetylglucosamine, a critical mediator of the unfolded protein response. Our findings suggest that PUFA desaturation is crucial for rescuing cancer cells from persistent ER stress, supporting FADS1 as a new therapeutic target.
PubMed: 38586033
DOI: 10.1101/2024.03.23.586426