Project description:MYC is an oncoprotein transcription factor that is overexpressed in the majority cancers. Although MYC itself is considered undruggable, it may be possible to inhibit MYC by targeting the co-factors it uses to drive oncogenic gene expression patterns. Here, we use loss- and gain- of function approaches to interrogate how one MYC co-factor—Host Cell Factor (HCF)-1—contributes to MYC activity in a Burkitt lymphoma setting. We identify high-confidence direct targets of the MYC–HCF-1 interaction that are regulated through a recruitment-independent mechanism, including genes that control mitochondrial function and rate-limiting steps for ribosome biogenesis and translation. We describe how these gene expression events impact cell growth and metabolism, and demonstrate that the MYC–HCF-1 interaction is essential for tumor maintenance in vivo. This work highlights the MYC–HCF-1 interaction as a focal point for development of novel anti-cancer therapies.
Project description:MYC enhances protein synthesis by regulating genes involved in ribosome biogenesis and protein translation. Here, we show that MYC-induced protein translation is mediated by the transcription factor aryl hydrocarbon receptor (AHR), which is induced by MYC in colonic cells. AHR promotes protein synthesis by activating the transcription of genes required for ribosome biogenesis and protein translation, including OGFOD1 and NOLC1. Using surface sensing of translation (SUnSET) to measure global protein translation, we found that silencing AHR or its targets diminishes protein synthesis. Therefore, targeting AHR or its downstream pathways could provide a novel approach to limit biomass production in MYC-driven tumors.
Project description:b'MYC is an oncoprotein transcription factor that is overexpressed in the majority cancers. Although MYC itself is considered undruggable, it may be possible to inhibit MYC by targeting the co-factors it uses to drive oncogenic gene expression patterns. Here, we use loss- and gain- of function approaches to interrogate how one MYC co-factorHost Cell Factor (HCF)-1contributes to MYC activity in a Burkitt lymphoma setting. We identify high-confidence direct targets of the MYCHCF-1 interaction that are regulated through a recruitment-independent mechanism, including genes that control mitochondrial function and rate-limiting steps for ribosome biogenesis and translation. We describe how these gene expression events impact cell growth and metabolism, and demonstrate that the MYCHCF-1 interaction is essential for tumor maintenance in vivo. This work highlights the MYCHCF-1 interaction as a focal point for development of novel anti-cancer therapies.'
Project description:Regulatory T (Treg) cell activation and expansion during neonatal life and in response to inflammation are critical for immunosuppression, yet the mechanisms governing these events are incompletely understood. We report that the oncogene and transcriptional regulator c-Myc (Myc) controls immune homeostasis through regulation of Treg cell accumulation and functional activation. Myc activity is enriched in Treg cells generated during neonatal life and responding to inflammation. Myc-deficient Treg cells show cell-intrinsic defects in overall accumulation and ability to transition to an activated state during early life or acute inflammation. Consequently, loss of Myc in Treg cells results in a rapid, early-onset autoimmune disorder accompanied by uncontrolled effector CD4+ and CD8+ T cell responses. We also provide evidence that Myc regulates mitochondrial oxidative metabolism but is dispensable for fatty acid oxidation (FAO). Indeed, Treg cell-specific deletion of Cox10, which is required for oxidative phosphorylation, but not Cpt1a, the rate-limiting enzyme for FAO, results in impaired Treg cell function and maturation. Thus, Myc coordinates Treg cell accumulation, transitional activation and metabolic programming to orchestrate immune homeostasis. We used microarrays to compare the global transcription profiles of WT and Myc-null Treg cells.
Project description:Embryonic genome activation (EGA) is orchestrated by an intrinsic developmental program initiated during oocyte maturation with translation of stored maternal mRNAs. Here we show that tankyrase, a poly(ADP-ribosyl) polymerase that regulates β-catenin levels, undergoes programmed translation during oocyte maturation and serves an essential role in mouse EGA. Newly translated TNKS triggers proteasomal degradation of axin, reducing targeted destruction of β-catenin and promoting β-catenin-mediated transcription of target genes, including Myc. MYC mediates ribosomal RNA transcription in 2-cell embryos, supporting global protein synthesis. Suppression of tankyrase activity using knockdown or chemical inhibition causes loss of nuclear β-catenin and global reductions in transcription and histone H3 acetylation. Chromatin and transcriptional profiling indicate that development arrests prior to the mid-2-cell stage, mediated in part by reductions in β-catenin and MYC. These findings indicate that post-transcriptional regulation of tankyrase serves as a ligand-independent developmental mechanism for post-translational β-catenin activation and is required to complete EGA.
Project description:Mucosal associated invariant T (MAIT) cells are an abundant population of innate T cells that recognize bacterial ligands and play a key role in host protection against bacterial and viral pathogens. Upon activation, MAIT cells undergo proliferative expansion and increase their production of effector molecules such as cytokines. In this study, we found that mRNA and protein the abundance of the key metabolism regulator and transcription factor MYC was increased in stimulated MAIT cells. Using quantitative mass spectrometry, we identified the activation of two MYC controlled metabolic pathways, amino acid transport and glycolysis, both of which were necessary for MAIT cell proliferation. Finally, we showed that MAIT cells isolated from people with obesity showed decreased MYC mRNA abundance upon activation, which was associated with defective MAIT cell proliferation and functional responses. Collectively, our data uncovers the importance of MYC-regulated metabolism for MAIT cell proliferation and provides additional insight into the molecular basis for the functional defects of MAIT cells in obesity.
Project description:We descrive a joint model of transcriptional activation and mRNA accumulation, using estrogen receptor ERM-NM-1 activation in MCF-7 breast cancer cell line, which can be used for inference of transcription rate, RNA processing delay and degradation rate given data from high-throughput sequencing time course experiments. MCF-7 cells were mock treated or with 10nM 17b-E2 to nine time points (5', 10', 20', 40', 80', 160', 320', 640' and 1280'). Genome-wide identification of RNA polymerase II (RNAPII) occupancy and transcriptome profiling (RNA-seq) following E2 induction of MCF-7 cells Please note that the information in the wig.txt files is in gene-specific coordinates, not chromosomic coordinates, as this is the most sensible format for the associated project/paper.
Project description:The 12-hour clock coordinates lipid homeostasis, energy metabolism and stress rhythms via the transcriptional regulator XBP1. However, the biochemical and physiological basis for integrated control of the 12-hour clock and diverse metabolic pathways remains unclear. Here, we show that steroid receptor coactivator SRC-3 coactivates XBP1 transcription and regulates hepatic 12-hour cistrome and gene rhythmicity. Mice lacking SRC-3 show abnormal 12-hour rhythms in hepatic transcription, metabolic functions, systemic energetics, and rate-limiting lipid metabolic processes including triglyceride, phospholipid and cardiolipin pathways. Notably, 12-hour clock coactivation is not only preserved, with its cistromic activation priming ahead of the zeitgeber cue of light, but concomitant with rhythmic remodeling in the absence of food. These findings reveal that SRC-3 integrates the mammalian 12-hour clock, energy metabolism, and membrane and lipid homeostasis, and demonstrates a role for the 12-hour clock machinery as an active transcriptional mechanism in anticipating physiological and metabolic energy needs and stresses.
Project description:Cellular stress responses often require transcription-based activation of gene expression to promote cellular adaptation. Whether general mechanisms exist for stress-responsive gene down-regulation is less clear. A recently defined mechanism enables both up- and down-regulation of protein levels for distinct gene sets by the same transcription factor (TF) via coordinated induction of canonical mRNAs and long undecoded transcript isoforms (LUTIs). We analyzed parallel gene expression datasets to determine whether this mechanism contributes to the conserved Hac1-driven branch of the unfolded protein response (UPRER), indeed observing Hac1-dependent protein down-regulation accompanying the up-regulation of ER-related proteins that typifies UPRER activation. Proteins down-regulated by Hac1-driven LUTIs include those with electron transport chain (ETC) function. Abrogated ETC function improves the fitness of UPRER-activated cells, suggesting functional importance to this regulation. We conclude that the UPRER drives large-scale proteome remodeling, including coordinated up- and down-regulation of distinct protein classes, which is partly mediated by Hac1-induced LUTIs.
Project description:The MYC oncogene is a potent driver of growth and proliferation but also sensitises cells to apoptosis, which limits its oncogenic potential. MYC induces several biosynthetic programmes and primary cells overexpressing MYC are highly sensitive to glutamine withdrawal suggesting that MYC-induced sensitisation to apoptosis may be due to an imbalance of metabolic/energetic supply and demand. Here we show that MYC elevates global transcription and translation, even in the absence of glutamine, revealing metabolic demand without corresponding supply. Glutamine withdrawal from MRC-5 fibroblasts depleted key TCA cycle metabolites and, in combination with MYC activation, led to AMP accumulation and nucleotide catabolism indicative of energetic stress. Further analyses revealed that glutamine supports viability through TCA cycle energetics rather than asparagine biosynthesis and that TCA cycle inhibition confers tumour suppression on MYC- driven lymphoma in vivo. In summary, glutamine supports the viability of MYC- overexpressing cells through an energetic rather than a biosynthetic mechanism.