Project description:Signaling trough cytoplasmic or nuclear action of p53 is a major response mechanism to cellular stresses. Here we perform transcriptomics after p53 re-expression on a CRISPR/Cas9 knock out background to reveal a distinct starvation-specific transcriptome response and novel nutrient-dependent p53 target genes.
Project description:Signaling trough cytoplasmic or nuclear action of p53 is a major response mechanism to cellular stresses. While p53 protein levels have been shown to increase upon nutrient stresses such as starvation, the exact signaling cascade in this context remains elusive. Here, we show in a human hepatoma cell line that nutrient withdrawal leads to robust nuclear p53 stabilization and utilize various complementary omics approaches to dissect upstream and downstream networks in the response to starvation. Using the affinity purification mass spectrometry (MS) method BioID, we determine the cytoplasmic p53 interaction network within the immediate-early starvation response and show that p53 is dissociated from several metabolic enzymes and the kinase PAK2. Direct binding of p53 DNA-binding domain and N-terminal PAK2 was confirmed with nuclear magnetic resonance (NMR) interaction studies. Furthermore, rapid immunoprecipitation MS of endogenous proteins (RIME) uncovered the nuclear interactome under prolonged starvation, where we confirmed the novel p53 interactors SORBS1, involved in insulin signaling, and UGP2, a key enzyme of glycogen synthesis. Finally, transcriptomics after p53 re-expression on a CRISPR/Cas9 knock out background revealed a distinct starvation-specific transcriptome response and suggested novel nutrient-dependent p53 target genes. Together, our complementary approaches delineate several nodes of the p53 signaling cascade in response to starvation, shedding new light on the mechanisms of p53 as a nutrient stress sensor and regulator of specific transcriptional output. Given the central role of p53 in cancer biology and the beneficial effects of fasting in cancer treatment, the identified interaction partners and networks could pinpoint novel pharmacologic targets to fine-tune p53 activity.
Project description:We report the transcriptome data produced from isogenic polymorphic p53 codon 72 iPSCs under doxorubicin treatment. By inserting BAC DNA into one allele of the heterozygous polymorphic p53 codon 72, each clone expressed a p53 protein encoding P72 or R72 from another allele in which it was not inserted. The transcriptional regulation of p53 target genes was compared between the isogenic lines under doxorubicin treatment.
Project description:Numerous mechanisms to support cells under conditions of transient nutrient starvation have been described. The tumor suppressor protein p53 can contribute to the adaptation of cells to metabolic stress through various mechanisms that may help cancer cell survival in nutrient limiting conditions. We show here that p53 helps cancer cells to survive glutamine starvation by promoting the expression of SLC1A3, an aspartate/glutamate transporter that allows the utilization of aspartate to support cells in the absence of extracellular glutamine. Under glutamine deprivation, SLC1A3 expression maintains electron transport chain and tricarboxylic acid cycle activity, promoting de novo glutamate, glutamine and nucleotide synthesis to rescue cell viability. Tumor cells with high levels of SLC1A3 expression are resistant to glutamine starvation and SLC1A3 depletion retards the growth of these cells in vitro and in vivo, suggesting a therapeutic potential for SLC1A3 inhibition.
Project description:p53 signaling is a major response mechanism to cellular stresses through cytoplasmic or nuclear action. While p53 protein levels have been shown to increase upon nutrient stresses such as starvation, the exact signaling cascade in this context remains elusive. Here, we use proximity biotinylation (BioID), to derive the cytoplasmic p53 interaction network as immediate early starvation response.
Project description:Glucose as a source of energy is centrally important to our understanding of life. We investigated the cell division-quiescence behavior of the fission yeast Schizosaccharomyces pombe under a wide range of glucose concentrations (0-111 mM). The mode of S. pombe cell division under a microfluidic perfusion system was surprisingly normal under highly diluted glucose concentrations (5.6 mM, 1/20 of the standard medium, within human blood sugar levels). Division became stochastic, accompanied by a curious division-timing inheritance, in 2.2-4.4 mM glucose. A critical transition from division to quiescence occurred within a narrow range of concentrations (2.2-1.7 mM). Under starvation (1.1 mM) conditions, cells were mostly quiescent and only a small population of cells divided. Under fasting (0 mM) conditions, division was immediately arrested with a short chronological lifespan (16 h). When cells were first glucose starved prior to fasting, they possessed a substantially extended lifespan (∼14 days). We employed a quantitative metabolomic approach for S. pombe cell extracts, and identified specific metabolites (e.g. biotin, trehalose, ergothioneine, S-adenosyl methionine and CDP-choline), which increased or decreased at different glucose concentrations, whereas nucleotide triphosphates, such as ATP, maintained high concentrations even under starvation. Under starvation, the level of S-adenosyl methionine increased sharply, accompanied by an increase in methylated amino acids and nucleotides. Under fasting, cells rapidly lost antioxidant and energy compounds, such as glutathione and ATP, but, in fasting cells after starvation, these and other metabolites ensuring longevity remained abundant. Glucose-starved cells became resistant to 40 mM H(2)O(2) as a result of the accumulation of antioxidant compounds.
Project description:To investigate mechanism of inosine promotes the survival and metabolism of MDA-MB-231 cells under starvation conditions, MDA-MB-231 cells were treated with inosine and glucose for 12h under starvation conditions. We then performed gene expression profiling analysis using data obtained from RNA-seq of MDA-MB-231 cells under three different treatments(-G-Q,Inosine,Glucose).