Project description:Adipocyte differentiation has been shown to require iron, but the underlying mechanism remains elusive. Ferrous iron ion is known to function as a co-factor for alpha-ketoglutarate-dependent dioxygenases, including demethylases for histones, DNA, and RNA. Previously we reported several alpha-ketoglutarate-dependent histone demethylases as critical epigenetic regulators during adipogenesis. These lines of evidence led us to hypothesize that iron orchestrates epigenetic/epitranscriptional regulations during adipogenesis by controlling demethylation activities. In this study, we conducted genome-wide analysis on methylation landscapes of histones, DNA, and RNA in differentiation of 3T3-L1 pre-adipocytes. Using the iron chelator deferoxamine, we demonstrate here how dynamically methylation levels of histones, DNA, and RNA are regulated by iron during adipogenesis.
Project description:Adipocyte differentiation has been shown to require iron, but the underlying mechanism remains elusive. Ferrous iron ion is known to function as a co-factor for alpha-ketoglutarate-dependent dioxygenases, including demethylases for histones, DNA, and RNA. Previously we reported several alpha-ketoglutarate-dependent histone demethylases as critical epigenetic regulators during adipogenesis. These lines of evidence led us to hypothesize that iron orchestrates epigenetic/epitranscriptional regulations during adipogenesis by controlling demethylation activities. In this study, we conducted genome-wide analysis on methylation landscapes of histones, DNA, and RNA in differentiation of 3T3-L1 pre-adipocytes. Using the iron chelator deferoxamine, we demonstrate here how dynamically methylation levels of histones, DNA, and RNA are regulated by iron during adipogenesis.
Project description:Adipocyte differentiation has been shown to require iron, but the underlying mechanism remains elusive. Ferrous iron ion is known to function as a co-factor for alpha-ketoglutarate-dependent dioxygenases, including demethylases for histones, DNA, and RNA. Previously we reported several alpha-ketoglutarate-dependent histone demethylases as critical epigenetic regulators during adipogenesis. These lines of evidence led us to hypothesize that iron orchestrates epigenetic/epitranscriptional regulations during adipogenesis by controlling demethylation activities. In this study, we conducted genome-wide analysis on methylation landscapes of histones, DNA, and RNA in differentiation of 3T3-L1 pre-adipocytes. Using the iron chelator deferoxamine, we demonstrate here how dynamically methylation levels of histones, DNA, and RNA are regulated by iron during adipogenesis.
Project description:Reticuloendothelial macrophages engulf ~0.2 trillion senescent erythrocytes daily in a process called erythrophagocytosis (EP). This critical mechanism preserves systemic heme-iron homeostasis by regulating red blood cell (RBC) catabolism and iron recycling. Although extensive work has demonstrated the various effects on macrophage metabolic reprogramming by stimulation with proinflammatory cytokines, little is known about the impact of EP on the macrophage metabolome and proteome. Thus, we performed mass spectrometry-based metabolomics and proteomics analyses of bone marrow-derived macrophages (BMDMs) before and after EP of IgG-coated RBCs. Further, metabolomics was performed on BMDMs incubated with free IgG to ensure that changes to macrophage metabolism were due to opsonized RBCs and not to free IgG binding. Uniformly labeled tracing experiments were conducted on BMDMs in the presence and absence of IgG-coated RBCs to assess the flux of glucose through the pentose phosphate pathway (PPP). In this study, we demonstrate that EP significantly alters amino acid and fatty acid metabolism, the Krebs cycle, OXPHOS, and arachidonate-linoleate metabolism. Increases in levels of amino acids, lipids and oxylipins, heme products, and RBC-derived proteins are noted in BMDMs following EP. Tracing experiments with U-13C6 glucose indicated a slower flux through glycolysis and enhanced PPP activation. Notably, we show that it is fueled by glucose derived from the macrophages themselves or from the extracellular media prior to EP, but not from opsonized RBCs. The PPP-derived NADPH can then fuel the oxidative burst, leading to the generation of reactive oxygen species necessary to promote digestion of phagocytosed RBC proteins via radical attack. Results were confirmed by redox proteomics experiments, demonstrating the oxidation of Cys152 and Cys94 of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and hemoglobin-β, respectively. Significant increases in early Krebs cycle and C5-branched dibasic acid metabolites (α-ketoglutarate and 2-hydroxyglutarate, respectively) indicate that EP promotes the dysregulation of mitochondrial metabolism. Lastly, EP stimulated aminolevulinic acid (ALA) synthase and arginase activity as indicated by significant accumulations of ALA and ornithine after IgG-mediated RBC ingestion. Importantly, EP-mediated metabolic reprogramming of BMDMs does not occur following exposure to IgG alone. In conclusion, we show that EP reprograms macrophage metabolism and modifies macrophage polarization.
Project description:Cochlear hair cells are the sensory cells responsible for transduction of acoustic signals. In mammals, damaged hair cells do not regenerate, resulting in permanent hearing loss. Reprogramming of the surrounding supporting cells to functional hair cells represent a novel strategy to hearing restoration. However, cellular processes governing the efficient and functional hair cell reprogramming are not completely understood. Employing the mouse cochlear organoid system, we performed detailed metabolomic characterizations of the expanding and differentiating organoids. We found that hair cell differentiation is associated with increased mitochondrial electron transport chain (ETC) activity and reactive oxidative species generation. Transcriptome and metabolome analyses indicate reduced expression of oxidoreductases and tricyclic acid (TCA) cycle metabolites. The metabolic decoupling between ETC and TCA cycle limits the availability of the key metabolic cofactors, α-ketoglutarate and NAD+. Reduced expression of NAD+ in cochlear supporting cells by PGC1α deficiency further impairs hair cell reprogramming, while supplementation of α-ketoglutarate and NAD+ promotes hair cell reprogramming both in vitro and in vivo. Our findings reveal metabolic rewiring as a central cellular process during hair cell differentiation, and highlight the insufficiency of key metabolites as a metabolic barrier for efficient hair cell reprogramming.
Project description:During early mammalian embryogenesis, dynamic changes in cell growth and proliferation are tightly linked to the underlying genetic and metabolic regulation. However, our understanding of metabolic reprogramming and its impact on epigenetic regulation in early embryo development remains elusive. We reconstruct their metabolic landscapes from the 2-cell and blastocyst stages, as well as their transition from totipotency to pluripotency. While 2-cell embryos favor methionine, polyamine and glutathione metabolism and stay in a more reductive state, blastocyst embryos have higher mitochondrial metabolites related to the tricarboxylic acid cycle, and present a more oxidative state. Moreover, we identify a reciprocal relationship between α-ketoglutarate (α-KG) and the competitive inhibitor of α-KG-dependent dioxygenases, L-2-hydroxyglutarate (2-HG), where 2-cell embryos inherited from oocytes and 1-cell zygotes display higher L-2-HG, whereas blastocysts show higher α-KG.Supplementing 2-HG or knocking down L2hgdh, a gene encoding the 2-HG consuming enzyme L-2-hydroxyglutarate dehydrogenase impeded erasure of global histone methylation markers . Together, our data demonstrate dynamic and interconnected metabolic, transcriptional and epigenetic network remodeling during murine early embryo development.
Project description:IDH1 is the most commonly mutated metabolic gene across human cancers, with the highest mutational frequency observed in AML, glioma, chondrosarcoma, and intrahepatic cholangiocarcinoma. Mutations of the hot spot R132 codon alter the activity of the IDH1 enzyme, resulting in the NADPH-dependent conversion of alpha-ketoglutarate to (R)-2-hydroxyglutarate [(R)-2HG], which accumulates to mM levels within tumors. (R)-2HG competitively inhibits a range of enzymes that utilize alpha-ketoglutarate. Targets include the JmjC family histone demethylases and TET family DNA demethylases whose inhibition is linked to the altered epigenetic state characteristic of many mIDH tumors. To gain insight into the mechanisms underlying the anti-tumor efficacy of inhibition of mutant IDH1 we conducted RNA-sequencing (RNA-seq) analysis of purified tumor cells. For these studies, the immune-competent 2205 subcutaneous allograft model was treated with AG120 or vehicle for 6 days and non-tumor cells were removed by magnetic bead sorting (negative selection for CD45+ immune cells, CD31+ endothelial cells, TER119+ erythrocytes, and CD90.2+ fibroblasts).
Project description:Phosphoinositide-3 kinase (PI3K)/AKT signaling participates in cellular proliferation, survival, and tumorigenesis as well as cellular reprogramming including generation of induced pluripotent stem cells (iPSCs). In this study, we revealed that activation of AKT in somatic cells undergoing reprogramming enhances epigenetic reprogramming. Activated AKT in reprogramming cells triggers elevated anabolic glucose metabolism, and, accordingly, increases the level of α-ketoglutarate (αKG) which is an essential cofactor for the enzymatic activity of the 5-methylcytosine (5mC) dioxygenase TET. Additionally, the level of TET was upregulated. Consistent with upregulated KG production and TET, we observed a genome-wide increase in 5-hydorxymethylcytosine (5hmC) which is an intermediate in the DNA demethylation process. Moreover, DNA methylation level at ES-cell super-enhancers of pluripotency-related genes was significantly decreased, leading upregulation of associated genes. Taken together, our results indicate that AKT signaling is associated with epigenetic regulation by hyperactivating TET at catalytical and transcriptional levels during the somatic cell reprogramming.
Project description:Phosphoinositide-3 kinase (PI3K)/AKT signaling participates in cellular proliferation, survival, and tumorigenesis as well as cellular reprogramming including generation of induced pluripotent stem cells (iPSCs). In this study, we revealed that activation of AKT in somatic cells undergoing reprogramming enhances epigenetic reprogramming. Activated AKT in reprogramming cells triggers elevated anabolic glucose metabolism, and, accordingly, increases the level of α-ketoglutarate (αKG) which is an essential cofactor for the enzymatic activity of the 5-methylcytosine (5mC) dioxygenase TET. Additionally, the level of TET was upregulated. Consistent with upregulated KG production and TET, we observed a genome-wide increase in 5-hydorxymethylcytosine (5hmC) which is an intermediate in the DNA demethylation process. Moreover, DNA methylation level at ES-cell super-enhancers of pluripotency-related genes was significantly decreased, leading upregulation of associated genes. Taken together, our results indicate that AKT signaling is associated with epigenetic regulation by hyperactivating TET at catalytical and transcriptional levels during the somatic cell reprogramming.
Project description:Here we report that the Th2 cytokine IL-4 and the tumor microenvironment activated protein kinase RNA-like ER kinase (PERK) stress signaling cascade to promote immunosuppressive M2 activation and proliferation. PERK activation mediated the upregulation of PSAT1 and serine biosynthesis via the downstream transcription factor ATF4. We found that Increased serine biosynthesis could result in enhanced mitochondrial function and α-ketoglutarate (α-KG) production required for JMJD3-dependent epigenetic modification.