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Project description:Pyruvate dehydrogenase (PDH) is the central enzyme connecting glycolysis and the tricarboxylic acid (TCA) cycle. The importance of PDH function in Th17 cells is unknown. Here, we show that PDH is essential for the generation of a unique glucose-derived citrate pool needed for Th17 cell proliferation, survival and effector function. In vivo, mice harboring a T cell-specific deletion of PDH were less susceptible to developing experimental autoimmune encephalomyelitis. Mechanistically, the absence of PDH in Th17 cells increased glutaminolysis, glycolysis, and lipid uptake in an mTOR-dependent manner. However, cellular citrate remained critically low in mutant Th17 cells, which interfered with oxidative phosphorylation (OXPHOS), lipid synthesis and histone acetylation crucial for the transcription of Th17 signature genes. Increasing cellular citrate in PDH-deficient Th17 cells restored their metabolism and function, identifying a metabolic feedback loop within central carbon metabolism that may offer possibilities for therapeutically targeting Th17 cell-driven autoimmunity.
2023-03-02 | GSE222878 | GEO
Project description:Pyruvate dehydrogenase (PDH) is the central enzyme connecting glycolysis and the tricarboxylic acid (TCA) cycle. The importance of PDH function in Th17 cells is unknown. Here, we show that PDH is essential for the generation of a unique glucose-derived citrate pool needed for Th17 cell proliferation, survival and effector function. In vivo, mice harboring a T cell-specific deletion of PDH were less susceptible to developing experimental autoimmune encephalomyelitis. Mechanistically, the absence of PDH in Th17 cells increased glutaminolysis, glycolysis, and lipid uptake in an mTOR-dependent manner. However, cellular citrate remained critically low in mutant Th17 cells, which interfered with oxidative phosphorylation (OXPHOS), lipid synthesis and histone acetylation crucial for the transcription of Th17 signature genes. Increasing cellular citrate in PDH-deficient Th17 cells restored their metabolism and function, identifying a metabolic feedback loop within central carbon metabolism that may offer possibilities for therapeutically targeting Th17 cell-driven autoimmunity.
2023-03-02 | GSE222881 | GEO
Project description:Pyruvate dehydrogenase (PDH) is the central enzyme connecting glycolysis and the tricarboxylic acid (TCA) cycle. The importance of PDH function in Th17 cells is unknown. Here, we show that PDH is essential for the generation of a unique glucose-derived citrate pool needed for Th17 cell proliferation, survival and effector function. In vivo, mice harboring a T cell-specific deletion of PDH were less susceptible to developing experimental autoimmune encephalomyelitis. Mechanistically, the absence of PDH in Th17 cells increased glutaminolysis, glycolysis, and lipid uptake in an mTOR-dependent manner. However, cellular citrate remained critically low in mutant Th17 cells, which interfered with oxidative phosphorylation (OXPHOS), lipid synthesis and histone acetylation crucial for the transcription of Th17 signature genes. Increasing cellular citrate in PDH-deficient Th17 cells restored their metabolism and function, identifying a metabolic feedback loop within central carbon metabolism that may offer possibilities for therapeutically targeting Th17 cell-driven autoimmunity.
2023-03-02 | GSE222880 | GEO
Project description:Th17 cells favor glycolytic metabolism, and pyruvate dehydrogenase (PDH) is the key bifurcation enzyme, which in its active dephosphorylated form advances the oxidative phosphorylation from glycolytic pathway. The transcriptional factor, inducible cAMP early repressor/cAMP response element modulator (ICER/CREM), has been shown to be induced in Th17 cells and to be overexpressed in CD4+ T cells from the patients with systemic lupus erythematosus (SLE). We found that glycolysis and lactate production in in vitro Th17-polarized T cells was reduced and that the expression of pyruvate dehydrogenase phosphatase catalytic subunit 2 (PDP2), an enzyme that converts the inactive PDH to its active form, and PDH enzyme activity were increased in Th17 cells from ICER/CREM-deficient animals. ICER was found to bind to the Pdp2 promoter and suppress its expression. Furthermore, forced expression of PDP2 in CD4+ cells reduced the in vitro Th17 differentiation, whereas shRNA-based suppression of PDP2 expression increased in vitro Th17 differentiation and augmented experimental autoimmune encephalomyelitis. At the translational level, PDP2 expression was decreased in memory Th17 cells from patients with SLE and forced expression of PDP2 in CD4+ T cells from lupus-prone MRL/lpr mice and patients with SLE suppressed Th17 differentiation. These data demonstrate the direct control of energy production during Th17 differentiation in health and disease by the transcription factor ICER/CREM at the PDH metabolism bifurcation level.
| S-EPMC6140513 | biostudies-literature
Project description:Members of the evolutionarily conserved family of the chicken ovalbumin upstream promoter transcription factor NR2F/COUP-TF orphan receptors have been implicated in lymphocyte biology, ranging from activation to differentiation and elicitation of immune effector functions. In particular, a CD4+ T cell intrinsic and non-redundant function of NR2F6 as a potent and selective repressor of the transcription of the pro-inflammatory cytokines interleukin (Il) 2, interferon y (ifng) and consequently of T helper (Th)17 CD4+ T cell-mediated autoimmune disorders has been discovered. NR2F6 serves as an antigen receptor signaling threshold-regulated barrier against autoimmunity where NR2F6 is part of a negative feedback loop that limits inflammatory tissue damage induced by weakly immunogenic antigens such as self-antigens. Under such low affinity antigen receptor stimulation, NR2F6 appears as a prototypical repressor that functions to "lock out" harmful Th17 lineage effector transcription. Mechanistically, only sustained high affinity antigen receptor-induced protein kinase C (PKC)-mediated phosphorylation has been shown to inactivate NR2F6, thereby displacing pre-bound NR2F6 from the DNA and, subsequently, allowing for robust NFAT/AP-1- and ROR?t-mediated cytokine transcription. The NR2F6 target gene repertoire thus identifies a general anti-inflammatory gatekeeper role for this orphan receptor. Investigating these signaling pathway(s) will enable a greater knowledge of the genetic, immune, and environmental mechanisms that lead to chronic inflammation and of certain autoimmune disorders in a given individual.
| S-EPMC4066320 | biostudies-other
Project description:The mitochondrial pyruvate dehydrogenase (PDH) complex (PDC) acts as a central metabolic node that mediates pyruvate oxidation and fuels the tricarboxylic acid cycle to meet energy demand. Here, we reveal another level of regulation of the pyruvate oxidation pathway in mammals implicating the E4 transcription factor 1 (E4F1). E4F1 controls a set of four genes [dihydrolipoamide acetlytransferase (Dlat), dihydrolipoyl dehydrogenase (Dld), mitochondrial pyruvate carrier 1 (Mpc1), and solute carrier family 25 member 19 (Slc25a19)] involved in pyruvate oxidation and reported to be individually mutated in human metabolic syndromes. E4F1 dysfunction results in 80% decrease of PDH activity and alterations of pyruvate metabolism. Genetic inactivation of murine E4f1 in striated muscles results in viable animals that show low muscle PDH activity, severe endurance defects, and chronic lactic acidemia, recapitulating some clinical symptoms described in PDC-deficient patients. These phenotypes were attenuated by pharmacological stimulation of PDH or by a ketogenic diet, two treatments used for PDH deficiencies. Taken together, these data identify E4F1 as a master regulator of the PDC.
| S-EPMC5047171 | biostudies-literature
Project description:T helper 17 (TH17) lymphocytes protect mucosal barriers from infections, but also contribute to multiple chronic inflammatory diseases. Their differentiation is controlled by ROR?t, a ligand-regulated nuclear receptor. Here we identify the RNA helicase DEAD-box protein 5 (DDX5) as a ROR?t partner that coordinates transcription of selective TH17 genes, and is required for TH17-mediated inflammatory pathologies. Surprisingly, the ability of DDX5 to interact with ROR?t and coactivate its targets depends on intrinsic RNA helicase activity and binding of a conserved nuclear long noncoding RNA (lncRNA), Rmrp, which is mutated in patients with cartilage-hair hypoplasia. A targeted Rmrp gene mutation in mice, corresponding to a gene mutation in cartilage-hair hypoplasia patients, altered lncRNA chromatin occupancy, and reduced the DDX5-ROR?t interaction and ROR?t target gene transcription. Elucidation of the link between Rmrp and the DDX5-ROR?t complex reveals a role for RNA helicases and lncRNAs in tissue-specific transcriptional regulation, and provides new opportunities for therapeutic intervention in TH17-dependent diseases.
| S-EPMC4762670 | biostudies-literature
Project description:Microtubule (MT)-based transport is an evolutionary conserved processed finely tuned by posttranslational modifications. Among them, tubulin acetylation, which is catalyzed by the α-tubulin N-acetyltransferase 1, Atat1, facilitates the recruitment and processivity of molecular motors along MT tracks. However, the mechanisms that controls Atat1 activity remains poorly understood. Here we show that a pool of vesicular ATP-citrate lyase Acly acts as a rate limiting enzyme to modulate Atat1 activity by controlling availability of Acetyl-CoA. In addition, we showed that Acly expression is reduced upon loss of Elongator activity, further connecting Elongator to Atat1 in the pathway regulating -tubulin acetylation and MT-dependent transport in projection neurons across species. Remarkably, comparable defects occur in fibroblasts from Familial Dysautonomia (FD) patients bearing an autosomal recessive mutation in the gene coding for the Elongator subunit ELP1. Our data may thus shine new light on the pathophysiological mechanisms underlying FD.
2022-02-16 | PXD021186 | Pride
Project description:The protein pirin, which is involved in a variety of biological processes, is conserved from prokaryotic microorganisms, fungi, and plants to mammals. It acts as a transcriptional cofactor or an apoptosis-related protein in mammals and is involved in seed germination and seedling development in plants. In prokaryotes, while pirin is stress induced in cyanobacteria and may act as a quercetinase in Escherichia coli, the functions of pirin orthologs remain mostly uncharacterized. We show that the Serratia marcescens pirin (pirin(Sm)) gene encodes an ortholog of pirin protein. Protein pull-down and bacterial two-hybrid assays followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and electrospray ionization-tandem mass spectrometry analyses showed the pyruvate dehydrogenase (PDH) E1 subunit as a component interacting with the pirin(Sm) gene. Functional analyses showed that both PDH E1 subunit activity and PDH enzyme complex activity are inhibited by the pirin(Sm) gene in S. marcescens CH-1. The S. marcescens CH-1 pirin(Sm) gene was subsequently mutated by insertion-deletion homologous recombination. Accordingly, the PDH E1 and PDH enzyme complex activities and cellular ATP concentration increased up to 250%, 140%, and 220%, respectively, in the S. marcescens CH-1 pirin(Sm) mutant. Concomitantly, the cellular NADH/NAD(+) ratio increased in the pirin(Sm) mutant, indicating increased tricarboxylic acid (TCA) cycle activity. Our results show that the pirin(Sm) gene plays a regulatory role in the process of pyruvate catabolism to acetyl coenzyme A through interaction with the PDH E1 subunit and inhibiting PDH enzyme complex activity in S. marcescens CH-1, and they suggest that pirin(Sm) is an important protein involved in determining the direction of pyruvate metabolism towards either the TCA cycle or the fermentation pathways.
| S-EPMC1797226 | biostudies-literature
Project description:Pyruvate dehydrogenase kinase (PDK) is an important mitochondrial enzyme that blocks the production of acetyl-CoA by selectively inhibiting the activity of pyruvate dehydrogenase (PDH) through phosphorylation. PDK is an effectively therapeutic target in cancer cells, but the physiological roles of PDK in phytopathogens are largely unknown. To address these gaps, a PDK gene (FgPDK1) was isolated from Fusarium graminearum that is an economically important pathogen infecting cereals. The deletion of FgPDK1 in F. graminearum resulted in the increase in PDH activity, coinciding with several phenotypic defects, such as growth retardation, failure in perithecia and conidia production, and increase in pigment formation. The ΔFgPDK1 mutants showed enhanced sensitivity to osmotic stress and cell membrane-damaging agent. Physiological detection indicated that reactive oxygen species (ROS) accumulation and plasma membrane damage (indicated by PI staining, lipid peroxidation, and electrolyte leakage) occurred in ΔFgPDK1 mutants. The deletion of FgPDK1 also prohibited the production of deoxynivalenol (DON) and pathogenicity of F. graminearum, which may resulted from the decrease in the expression of Tri6. Taken together, this study firstly identified the vital roles of FgPDK1 in the development of phytopathogen F. graminearum, which may provide a potentially novel clue for target-directed development of agricultural fungicides.
| S-EPMC4920349 | biostudies-literature