Transcription profiling by array of human pacreatic islets prepared for clinical transplantation
Ontology highlight
ABSTRACT: This study compared 9 human islet preparations, extracted and prepared for clinical transplantation. Human islets were isolated as, and all were of transplant quality. Unamplified RNA was extracted and hybridized to Affymetrix HGU133+2 arrays. By using gene set enrichment analysis to investigate the variability of each probeset on the array, it was clear that isolated human islets undergo varying degrees of hypoxic stress. Further to this, key glycolytic genes, all of which are under the control of hypoxia inducing factor 1a (HIF-1a) were activated, indicating a switch towards anareobic glycolysis. Glycolysis severely impairs the ability of islets to sense glucose and secrete insulin in response to elevated blood sugar. We confirmed these findings in mouse rodents, demonstrated a dependance upon HIF-1a, and showed that even after 4 weeks, hypoxic islets retained their glycolytic molecular profile.
Project description:Although hypoxia inducible factor-1a (HIF-1a) was originally identified as a transcriptional factor to adapt hypoxia, HIF-1a has also been shown to regulate metabolic pathways specific for cancer, including aerobic glycolysis, namely “Warburg effect”. However, the mechanisms by which HIF-1a mediates the metabolic pathway under normoxia are not fully understood. Here, we identified gamma-glutamylcyclotransferase (GGCT) as a novel regulator of HIF-1a. GGCT is a highly expressed protein in various cancer tissues. Knockdown of GGCT exerts anticancer effects both in vitro and in vivo; thus, it is considered a promising therapeutic target. In this study, we show that depleting GGCT downregulates the protein and mRNA expressions of HIF-1a in PC3 prostate cancer cells, and that overexpressing GGCT upregulates them in mouse fibroblast NIH3T3 cells. We also show that depleting GGCT downregulates HIF-1a downstream target genes involved in glycolysis, whereas overexpressing GGCT exhibits upregulation pattern in these genes. Furthermore, we suggest that GGCT induces the metabolic switch from citric acid cycle to glycolysis under normoxia. Additionally, we show that GGCT regulates expression of HIF-1a protein via AMPK-mTORC1-4EBP1 pathway in PC3 cells. These results indicate the GGCT plays a regulatory role in the expression of HIF-1a followed by glycolytic switch in cancer cells.
Project description:Although hypoxia inducible factor-1a (HIF-1a) was originally identified as a transcriptional factor to adapt hypoxia, HIF-1a has also been shown to regulate metabolic pathways specific for cancer, including aerobic glycolysis, namely “Warburg effect”. However, the mechanisms by which HIF-1a mediates the metabolic pathway under normoxia are not fully understood. Here, we identified gamma-glutamylcyclotransferase (GGCT) as a novel regulator of HIF-1a. GGCT is a highly expressed protein in various cancer tissues. Knockdown of GGCT exerts anticancer effects both in vitro and in vivo; thus, it is considered a promising therapeutic target. In this study, we show that depleting GGCT downregulates the protein and mRNA expressions of HIF-1a in PC3 prostate cancer cells, and that overexpressing GGCT upregulates them in mouse fibroblast NIH3T3 cells. We also show that depleting GGCT downregulates HIF-1a downstream target genes involved in glycolysis, whereas overexpressing GGCT exhibits upregulation pattern in these genes. Furthermore, we suggest that GGCT induces the metabolic switch from citric acid cycle to glycolysis under normoxia. Additionally, we show that GGCT regulates expression of HIF-1a protein via AMPK-mTORC1-4EBP1 pathway in PC3 cells. These results indicate the GGCT plays a regulatory role in the expression of HIF-1a followed by glycolytic switch in cancer cells.
Project description:The metabolic adaptation of eukaryotic cells to hypoxia involves increasing dependence upon glycolytic ATP production, an event with consequences for both cell bioenergetics and cell fate. This response is regulated at the transcriptional level by HIF-1-dependent transcriptional upregulation of all ten glycolytic enzymes. However, this response alone does not account for the levels of ATP produced in hypoxia. Here, we investigated additional mechanisms of regulating glycolysis in hypoxia. We found that both intestinal epithelial cells treated with inhibitors of transcription and translation and human platelets (which lack nuclei) maintained the capacity for hypoxia-induced glycolysis, suggesting the involvement of a non-transcriptional component to the hypoxia-induced metabolic switch to a highly glycolytic phenotype. Mass spectrometric analysis of the interactome of immunoprecipitated rate-limiting glycolytic enzymes identified hypoxia-sensitive complexes comprising multiple glycolytic enzymes and glucose transporters in intestinal epithelial cells. Surprisingly, the formation of glycolytic complexes, though not dependent upon transcription, occurs via a HIF-1?-dependent mechanism, suggesting that HIF-1? may play a moonlighting role in the formation / maintenance of glycolytic complexes. Furthermore, we provide evidence for the presence of HIF-1? in cytosolic fractions of hypoxic cells which physically associated with the glucose transporter GLUT1 and the glycolytic enzyme PFKP in a hypoxia-sensitive manner. In conclusion, we hypothesize that HIF-1? plays a role in initiation and/or maintenance of glycolytic complexes in intestinal epithelial cells under hypoxic conditions in a manner which optimizes catalytic efficiency of the pathway by facilitating substrate channeling of glycolytic intermediates between sequential pathway enzymes. In hypoxia, cells undergo a metabolic switch to increased glycolysis. This has important implications for cell behavior, phenotype, and fate in both healthy and cancerous cells. Here we describe a mechanism by which HIF-1, in addition to increasing glycolytic enzyme expression, promotes glycolysis via the formation of a metabolic complex.
Project description:The metabolic adaptation of eukaryotic cells to hypoxia involves increasing dependence upon glycolytic ATP production, an event with consequences for both cell bioenergetics and cell fate. This response is regulated at the transcriptional level by HIF-1-dependent transcriptional upregulation of all ten glycolytic enzymes. However, this response alone does not account for the levels of ATP produced in hypoxia. Here, we investigated additional mechanisms of regulating glycolysis in hypoxia. We found that both intestinal epithelial cells treated with inhibitors of transcription and translation and human platelets (which lack nuclei) maintained the capacity for hypoxia-induced glycolysis, suggesting the involvement of a non-transcriptional component to the hypoxia-induced metabolic switch to a highly glycolytic phenotype. Mass spectrometric analysis of the interactome of immunoprecipitated rate-limiting glycolytic enzymes identified hypoxia-sensitive complexes comprising multiple glycolytic enzymes and glucose transporters in intestinal epithelial cells. Surprisingly, the formation of glycolytic complexes, though not dependent upon transcription, occurs via a HIF-1?-dependent mechanism, suggesting that HIF-1? may play a moonlighting role in the formation / maintenance of glycolytic complexes. Furthermore, we provide evidence for the presence of HIF-1? in cytosolic fractions of hypoxic cells which physically associated with the glucose transporter GLUT1 and the glycolytic enzyme PFKP in a hypoxia-sensitive manner. In conclusion, we hypothesize that HIF-1? plays a role in initiation and/or maintenance of glycolytic complexes in intestinal epithelial cells under hypoxic conditions in a manner which optimizes catalytic efficiency of the pathway by facilitating substrate channeling of glycolytic intermediates between sequential pathway enzymes. In hypoxia, cells undergo a metabolic switch to increased glycolysis. This has important implications for cell behavior, phenotype, and fate in both healthy and cancerous cells. Here we describe a mechanism by which HIF-1, in addition to increasing glycolytic enzyme expression, promotes glycolysis via the formation of a metabolic complex.
Project description:The metabolic adaptation of eukaryotic cells to hypoxia involves increasing dependence upon glycolytic ATP production, an event with consequences for both cell bioenergetics and cell fate. This response is regulated at the transcriptional level by HIF-1-dependent transcriptional upregulation of all ten glycolytic enzymes. However, this response alone does not account for the levels of ATP produced in hypoxia. Here, we investigated additional mechanisms of regulating glycolysis in hypoxia. We found that both intestinal epithelial cells treated with inhibitors of transcription and translation and human platelets (which lack nuclei) maintained the capacity for hypoxia-induced glycolysis, suggesting the involvement of a non-transcriptional component to the hypoxia-induced metabolic switch to a highly glycolytic phenotype. Mass spectrometric analysis of the interactome of immunoprecipitated rate-limiting glycolytic enzymes identified hypoxia-sensitive complexes comprising multiple glycolytic enzymes and glucose transporters in intestinal epithelial cells. Surprisingly, the formation of glycolytic complexes, though not dependent upon transcription, occurs via a HIF-1?-dependent mechanism, suggesting that HIF-1? may play a moonlighting role in the formation / maintenance of glycolytic complexes. Furthermore, we provide evidence for the presence of HIF-1? in cytosolic fractions of hypoxic cells which physically associated with the glucose transporter GLUT1 and the glycolytic enzyme PFKP in a hypoxia-sensitive manner. In conclusion, we hypothesize that HIF-1? plays a role in initiation and/or maintenance of glycolytic complexes in intestinal epithelial cells under hypoxic conditions in a manner which optimizes catalytic efficiency of the pathway by facilitating substrate channeling of glycolytic intermediates between sequential pathway enzymes. In hypoxia, cells undergo a metabolic switch to increased glycolysis. This has important implications for cell behavior, phenotype, and fate in both healthy and cancerous cells. Here we describe a mechanism by which HIF-1, in addition to increasing glycolytic enzyme expression, promotes glycolysis via the formation of a metabolic complex.
Project description:<p>Natural killer (NK) cells are forced to cope with different oxygen environments even under resting conditions. The adaptation to low oxygen is regulated by oxygen-sensitive transcription factors, the hypoxia-inducible factors (HIFs). The function of HIFs for NK cell activation and metabolic rewiring remains controversial. Activated NK cells are predominantly glycolytic, but the metabolic programs that ensure the maintenance of resting NK cells are enigmatic. By combining <em>in situ</em> metabolomic and transcriptomic analyses in resting murine NK cells, our study defines HIF-1a as a regulator of tryptophan metabolism and cellular nicotinamide adenine dinucleotide (NAD+) levels. The HIF-1a/NAD+ axis prevents ROS production during oxidative phosphorylation (OxPhos) and thereby blocks DNA damage and NK cell apoptosis under steadystate conditions. In contrast, in activated NK cells under hypoxia, HIF-1a is required for glycolysis, and forced HIF-1a expression boosts glycolysis and NK cell performance <em>in vitro</em> and <em>in vivo</em>. Our data highlight two distinct pathways by which HIF-1a interferes with NK cell metabolism. While HIF-1a-driven glycolysis is essential for NK cell activation, resting NK cell homeostasis relies on HIF-1a-dependent tryptophan/NAD+ metabolism.</p><p><br></p><p><strong>Linked cross omic data sets:</strong></p><p>RNA-seq data associated with this study are available in ArrayExpress (BioStudies): accession <a href='https://www.ebi.ac.uk/biostudies/arrayexpress/studies/E-MTAB-12082' rel='noopener noreferrer' target='_blank'>E-MTAB-12082</a>.</p>
Project description:Activation of glycolytic genes by HIF-1 is considered critical for metabolic adaptation to hypoxia. We found that HIF-1 also actively suppresses glucose metabolism through the tricarboxylic acid cycle (TCA) by directly trans-activating the gene encoding pyruvate dehydrogenase kinase 1 (PDK1). PDK1 inactivates the TCA cycle enzyme, pyruvate dehydrogenase (PDH), which converts pyruvate to acetyl-CoA. Forced PDK1 expression in hypoxic HIF-1α-null cells increases ATP levels, attenuates hypoxic ROS generation and rescues these cells from hypoxia-induced apoptosis. These studies reveal a novel hypoxia-induced metabolic switch that shunts glucose metabolites from the mitochondria to glycolysis to maintain ATP production and to prevent toxic ROS production. Experiment Overall Design: We sought to determine by microarray analysis of gene expression the genes responsive to hypoxia using the human B lymphocyte cell line, P493-6. Hypoxia-responsive genes were globally assessed in cells incubated in 0.1% O2 for 29 hours at which the highest HIF-1 levels were obtained
Project description:Deubiquitylating enzymes (DUBs) play an essential role in targeted protein degradation and represent an emerging therapeutic paradigm in cancer. However, their therapeutic potential in pancreatic ductal adenocarcinoma (PDAC) has not been explored. Here, we developed a DUB discovery pipeline, combining activity-based proteomics with a loss-of-function genetic screen in patient-derived PDAC organoids and murine genetic models. This approach identified USP25 as a master regulator of PDAC growth and maintenance. Genetic and pharmacological USP25 inhibition resulted in potent growth impairment in PDAC organoids, while normal pancreatic organoids were insensitive, and caused dramatic regression of patient-derived xenografts. Mechanistically, USP25 deubiquitinated and stabilised the HIF-1a transcription factor. PDAC is characterised by a severely hypoxic microenvironment, and USP25 depletion abrogated HIF-1a transcriptional activity and impaired glycolysis, inducing PDAC cell death in the tumor hypoxic core. Thus, the USP25/HIF-1a axis is an essential mechanism of metabolic reprogramming and survival in PDAC, which can be therapeutically exploited.
Project description:beta-glucan induced glycolysis in HIF-1 depedent manner. We reported that beta-glucan injection in mice led to upregulated glycolysis. HIF-1a plays a major role in this process. Mice receives beta-glucan via ip for 4 days. Splenocytes were isolated for RNA sequencing.