Project description:Ionophores are antibacterial compounds that affect bacterial growth by changing intracellular concentrations of the essential cations, sodium and potassium. They are extensively used in animal husbandry to increase productivity and reduce infectious diseases. Given their widespread usage, it is important to determine the potential negative consequences of ionophore use on human and animal health. In this study, we demonstrate that exposure to the ionophore monensin can select for resistant mutants in the human and animal pathogen Staphylococcus aureus, with a majority of the resistant mutants showing increased growth rates in vitro and/or in mice. Whole-genome sequencing and proteomics analysis of the resistant mutants show that the resistance phenotype is associated with de-repression of de novo purine synthesis, which could be achieved through mutations in different transcriptional regulators including mutations in the gene purR, the repressor of the purine de novo synthesis pathway. This study shows that mutants with reduced susceptibility to the ionophore monensin can be readily selected and highlights an unexplored link between ionophore resistance, purine metabolism and fitness in pathogenic bacteria.
Project description:Purine biosynthesis and metabolism, conserved in all living organisms, is essential for cellular energy homeostasis and nucleic acids synthesis. The de novo synthesis of purine precursors is under tight negative feedback regulation mediated by adenine and guanine nucleotides. We describe a new early-onset distinct neurodegenerative condition resulting from mutations in the adenosine monophosphate deaminase 2 gene (AMPD2). Patients have characteristic brain imaging features of pontocerebellar hypoplasia (PCH), due to loss of brainstem and cerebellar parenchyma. We found that AMPD2 plays an evolutionary conserved role in the maintenance of cellular guanine nucleotide pools by regulating the feedback inhibition of adenosine derivatives on de novo purine synthesis. AMPD2 deficiency results in defective GTP-dependent initiation of protein translation, which can be rescued by administration of purine precursors. These data suggest AMPD2-related PCH as a new potentially treatable early-onset neurodegenerative disease.
Project description:Purine biosynthesis and metabolism, conserved in all living organisms, is essential for cellular energy homeostasis and nucleic acids synthesis. The de novo synthesis of purine precursors is under tight negative feedback regulation mediated by adenine and guanine nucleotides. We describe a new early-onset distinct neurodegenerative condition resulting from mutations in the adenosine monophosphate deaminase 2 gene (AMPD2). Patients have characteristic brain imaging features of pontocerebellar hypoplasia (PCH), due to loss of brainstem and cerebellar parenchyma. We found that AMPD2 plays an evolutionary conserved role in the maintenance of cellular guanine nucleotide pools by regulating the feedback inhibition of adenosine derivatives on de novo purine synthesis. AMPD2 deficiency results in defective GTP-dependent initiation of protein translation, which can be rescued by administration of purine precursors. These data suggest AMPD2-related PCH as a new potentially treatable early-onset neurodegenerative disease. An 18 chip study, that compares iPSC derived neural progenitor cells from two individuals: a patient with pontocerebellar hypoplasia and an unaffected parent. Samples are run as either non-treated, treated with Adenosine, or treated with Adenosine and AICAr. Three replicates are included for every individuals in every treatment condition.
Project description:To investigate whether BRD4-chromatin binding is modulated by purine levels, we performed BRD4 ChIP-seq in cells with SLC nucleoside transporters knockout, or cells with de novo purine synthesis inhibitor 6-MP treatment. (+)-JQ1, an inhibitor which disrupts BRD4 and acetylated histone binding, was used as a positive control.
Project description:Cell cycle and metabolism are two major outputs controlled by circadian rhythm in many organisms. Here we show that the three processes were linked through inosine 5'-phosphate dehydrogenase (impdh), a rate-limiting enzyme in de novo purine synthesis. We using adult zebrafish as a model system,we applied a genome-wide transcriptome approach that allowed us to investigate circadian gene expression. The whole-genome transcriptome profiles of adult brain in time-series were assayed on Agilent zebrafish microarrays. We used a similar statistical method to identify zebrafish circadian genes (ZCOG) as our previous study in larval zebrafish. Three isoforms of impdh show strong circadian oscillations in different tissues of zebrafish. impdh1a contributes to the ocular development and pigment synthesis, impdh2 promotes and impdh1b delays the development. By limiting the GTP required by DNA synthesis, impdh2 contributes to the daily rhythm of S phase in cell cycle. Multiple enzymes in the de novo purine synthesis pathway show the same circadian oscillations with peaks similar to impdh2. The circadian expression of this pathway is conserved in mouse liver. In summary, we show that the circadian regulation of de novo purine synthesis that supplies crucial building blocks for DNA replication is critical for gating cell cycle in circadian rhythm. Adult zebrafish were sacrificed and dissected at 4h intervals starting at CT0 in both LD and DD conditions for 12 time points. Total RNA of individual zebrafish brain was extracted using Trizol (Invitrogen, Carlsbad, CA) according to the manufacturerM-bM-^@M-^Ys instruction. Microarrays were manufactured by Agilent Technologies (Agilent Technologies, Palo Alto, CA), containing 43,603 probes for zebrafish whole-genome transcriptional profiling.
Project description:Cell cycle and metabolism are two major outputs controlled by circadian rhythm in many organisms. Here we show that the three processes were linked through inosine 5'-phosphate dehydrogenase (impdh), a rate-limiting enzyme in de novo purine synthesis. We using adult zebrafish as a model system,we applied a genome-wide transcriptome approach that allowed us to investigate circadian gene expression. The whole-genome transcriptome profiles of adult brain in time-series were assayed on Agilent zebrafish microarrays. We used a similar statistical method to identify zebrafish circadian genes (ZCOG) as our previous study in larval zebrafish. Three isoforms of impdh show strong circadian oscillations in different tissues of zebrafish. impdh1a contributes to the ocular development and pigment synthesis, impdh2 promotes and impdh1b delays the development. By limiting the GTP required by DNA synthesis, impdh2 contributes to the daily rhythm of S phase in cell cycle. Multiple enzymes in the de novo purine synthesis pathway show the same circadian oscillations with peaks similar to impdh2. The circadian expression of this pathway is conserved in mouse liver. In summary, we show that the circadian regulation of de novo purine synthesis that supplies crucial building blocks for DNA replication is critical for gating cell cycle in circadian rhythm.
Project description:Purines serve as the building blocks for DNA and RNA, confer cellular energy and signaling. Purines are generated by de novo synthesis pathway and salvage pathway. Under purine-depleted or other cellular stresses, enzymes in the purine de novo synthesis pathway form a dynamic and reversible condensate called purinosome, but the underlying mechanism of purinosome formation is unknown. In this thesis, we found that ASB11-based Cul5 E3 ligase promotes ubiquitination of PAICS, a purine de novo synthesis enzyme. This ubiquitination does not lead to PAICS degradation, but drives purinosome assembly. We provide evidence that purinosome assembly involves a liquid-liquid phase separation (LLPS) process and identify several ubiquitin binding proteins that may bind ubiquitinated PAICS through a multivalent mode to drive LLPS and purinosome assembly. Importantly, ASB11 is upregulated under the stresses that promote purinosome assembly, thus increasing the formation of ASB11/PAICS complex. Finally, we demonstrated that melanoma cells express a high level of ASB11 to confer a constitutive purinosome formation, which support their viability. In summary, our study identifies ASB11-mediated PAICS ubiquitination as a driving mechanism for purinosome assembly, the regulation of this mechanism under stressed conditions, and the importance of this regulation in cell viability.
Project description:Purines serve as the building blocks for DNA and RNA, confer cellular energy and signaling. Purines are generated by de novo synthesis pathway and salvage pathway. Under purine-depleted or other cellular stresses, enzymes in the purine de novo synthesis pathway form a dynamic and reversible condensate called purinosome, but the underlying mechanism of purinosome formation is unknown. In this thesis, we found that ASB11-based Cul5 E3 ligase promotes ubiquitination of PAICS, a purine de novo synthesis enzyme. This ubiquitination does not lead to PAICS degradation, but drives purinosome assembly. We provide evidence that purinosome assembly involves a liquid-liquid phase separation (LLPS) process and identify several ubiquitin binding proteins that may bind ubiquitinated PAICS through a multivalent mode to drive LLPS and purinosome assembly. Importantly, ASB11 is upregulated under the stresses that promote purinosome assembly, thus increasing the formation of ASB11/PAICS complex. Finally, we demonstrated that melanoma cells express a high level of ASB11 to confer a constitutive purinosome formation, which support their viability. In summary, our study identifies ASB11-mediated PAICS ubiquitination as a driving mechanism for purinosome assembly, the regulation of this mechanism under stressed conditions, and the importance of this regulation in cell viability.
2023-10-06 | PXD038411 | Pride
Project description:De Novo Purine Synthesis Mediates Circadian Control of Cell Cycle in Zebrafish
Project description:Brain tumor initiating cells (BTICs), also known as cancer stem cells, hijack high-affinity glucose uptake normally active in brain to maintain energy demands in dynamic tumor microenvironments. Using unbiased metabolomics and genomic analyses, we discovered that de novo purine synthesis is functionally upregulated in BTICs, mediating glucose-sustained anabolic metabolism. Inhibiting purine synthesis abrogated BTIC growth, self-renewal, and in vivo tumor formation by depleting intracellular pools of purine nucleotides, supporting purine synthesis as potential therapeutic point of fragility. In contrast, differentiated brain tumor cells retained proliferative potential with targeting of purine biosynthetic enzymes, suggesting a selective dependence in BTICs. Upstream transcriptional activation of purine synthesis is mediated by MYC. Elevated expression of purine synthetic enzymes correlates with poor prognosis in glioblastoma patients. Collectively, our results suggest that a stem-like state in brain cancer is associated with metabolic reprogramming to fuel tumor hierarchy, revealing potential BTIC cancer dependencies amenable to targeted therapy.