Expression Of Glucose Metabolism Genes Research Articles

Metabolic status differentiates Trp53inp2 function in pressure-overload induced heart failure.

Cardiometabolic disorders encompass a broad range of cardiovascular complications associated with metabolic dysfunction. These conditions have an increasing share in the health burden worldwide due to worsening endemic of hypertension, obesity, and diabetes. Previous studies have identified Tumor Protein p53-inducible Nuclear Protein 2 (Trp53inp2) as a molecular link between hyperglycemia and cardiac hypertrophy. However, its role in cardiac pathology has never been determined in vivo. In this study, we generated a cardiac specific knockout model of Trp53inp2 (Trp53inp2-cKO) and investigated the impact of Trp53inp2 inactivation on the pathogenesis of heart failure under mechanic or/and metabolic stresses. Based on echocardiography assessment, inactivation of Trp53inp2 in heart led to accelerated onset of HFrEF in response to pressure-overload, with significantly reduced ejection fraction and elevated heart failure marker genes comparing to the control mice. In contrast, inactivation of Trp53inp2 ameliorated cardiac dysfunction induced by combined stresses of high fat diet and moderate pressure overload (Cardiometabolic Disorder Model). Moreover, Trp53inp2 inactivation led to reduced expression of glucose metabolism genes in lean, pressure-overloaded hearts. However, the same set of genes were significantly induced in the Trp53inp2-cKO hearts under both mechanical and metabolic stresses. In summary, we have demonstrated for the first time that cardiomyocyte Trp53inp2 has diametrically differential roles in the pathogenesis of heart failure and glucose regulation under mechanical vs. mechanical plus metabolic stresses. This insight suggests that Trp53inp2 may exacerbate the cardiac dysfunction during pressure overload injury but have a protective effect in cardiac diastolic function in cardiometabolic disease.

Early programming effects of a hyperglucidic diet on carbohydrate and lipid metabolism in gibel carp (Carassius gibelio)

Previous nutritional studies have shown that intermediate metabolism in early fish development is highly plastic, and thus we hypothesized that there may be an early programming effect of a hyperglucidic diet on carbohydrate utilization in gibel carp. To test our hypothesis, gibel carp CAS Ⅴ (mean body weight: 0.10 g) were fed a high-carbohydrate/low protein (HC/LP) or low carbohydrate/high protein (LC/HP) diet for three weeks, and then were fed with normal feed for 12 weeks and a hyperglucidic diet for one week. We found that early HC/LP stimulus inhibited growth performance but altered the expression of glucose metabolism genes. After long-term feeding on the normal diet, the effects of early HC/LP stimulus were eliminated; these involved plasma metabolites, hepatic cholesterol, glycogen and triglyceride content, and glucose and lipid metabolism. However, the early HC stimulus group showed a better ability to maintain plasma glucose hemostasis when again given the HC diet. The capacity of carbohydrate and lipid metabolism in juvenile gibel carp was improved in the early HC diet group, as indicated by upregulated expression of genes related to glycolysis, lipid transport (gk, akt, srebp1, acc, fas, hsl, and acly) and downregulated expression of genes involved in gluconeogenesis (fbpase). Moreover, the early HC diet significantly upregulated AKT protein expression levels. The DNA methylation levels of akt in the HC/LP group were significantly lower than those in the LC/HP group. Overall, the study suggests that early HC stimulus in juvenile gibel carp can result in better carbohydrate utilization through DNA methylation of critical elements in the insulin signaling pathway.

Abstract P3196: Voluntary Exercise Training Does Not Prevent High Phosphate Diet-induced Mitochondrial Dysfunction

Inorganic phosphate (Pi) is used extensively as a preservative and a flavor enhancer in processed foods consumed as part of a Western diet. Mice fed high-Pi diet (HP) for 12 weeks display decreased maximal exercise capacity but no change in cardiac function. Expression of fatty acid metabolism genes are decreased and expression of glucose metabolism genes are increased in skeletal muscle after HP diet. Consequently, mitochondrial function is significantly impaired in skeletal muscle from mice fed HP diet. In the current study we test the hypothesis that voluntary exercise training prevents the negative metabolic consequences of HP diet. We housed mice in voluntary wheel running cages and fed them a normal-Pi (NP) or HP diet. HP diet did not alter body weight or composition, and NP- and HP-fed mice voluntarily ran the same distance in wheel cages throughout the study. Using incline treadmill exercise tolerance tests we observed no differences in medium-intensity exercise capacity between NP- and HP-fed mice subjected to voluntary wheel running, contrary to findings in sedentary mice. Despite preserved exercise capacity, muscle mitochondrial function in mice fed HP diet was significantly decreased after 5 weeks, which continued to decline after 12 weeks of HP diet and voluntary exercise. To investigate mechanisms of HP-induced mitochondrial dysfunction we measured expression of key metabolic genes and found that fatty acid metabolism genes were significantly decreased in muscle from mice fed HP diet and subjected to voluntary exercise. These data suggest that voluntary exercise training does not prevent the negative metabolic consequences of consuming a high-phosphate diet. Thus, dietary Pi may represent a novel and modifiable target to reduce physical inactivity associated with the Western diet.

Antidiabetic effect of sciadonic acid on type 2 diabetic mice through activating the PI3K-AKT signaling pathway and altering intestinal flora.

Type 2 diabetes mellitus (T2DM) is a metabolic disease characterized by hyperglycemia. The aim of this work was to investigate the effect of sciadonic acid (SA) on disorders of glucolipid metabolism and intestinal flora imbalance and to further investigate its potential molecular mechanism of anti-diabetes. The experimental data indicated that SA could alleviate hyperlipidemia, insulin resistance, oxidative stress, the inflammatory response, repair liver function damage, and promote glycogen synthesis caused by T2DM. SA could also activate the PI3K/AKT/GLUT-2 signaling pathway, promote glucose metabolism gene expression, and maintain glucose homeostasis. Furthermore, 16S rRNA analysis revealed that SA could reduce the Firmicutes/Bacteroidota (F/B) ratio; promote norank_f__Muribaculaceae, Allobaculum, Akkermansia, and Eubacterium_siraeum_group proliferation; increase the levels of major short-chain fatty acids (SCFAs), such as acetic acid, propionic acid, and butyric acid; and maintain the homeostasis of the intestinal flora. In conclusion, these results suggested that SA could reshape the structural composition of intestinal microbes, activate the PI3K/AKT/GLUT2 pathway, improve insulin resistance, and decrease blood glucose levels.

Regulation of gene expression by glycolytic and gluconeogenic enzymes.

Gene transcription and cell metabolism are two fundamental biological processes that mutually regulate each other. Upregulated or altered expression of glucose metabolic genes in glycolysis and gluconeogenesis is a major driving force of enhanced aerobic glycolysis in tumor cells. Importantly, glycolytic and gluconeogenic enzymes in tumor cells acquire moonlighting functions and directly regulate gene expression by modulating chromatin or transcriptional complexes. The mutual regulation between cellular metabolism and gene expression in a feedback mechanism constitutes a unique feature of tumor cells and provides specific molecular and functional targets for cancer treatment.

187-OR: Declines in ß-Cell Glucose Responsiveness Correlate with Loss of Glucose Metabolism during T1D Pathogenesis

Features of type 1 diabetes (T1D) include loss of first-phase insulin secretion in response to glucose, declining c-peptide, and glucose intolerance; indicating β cell dysfunction. Here, we investigate the mechanisms of this dysfunction with the hypothesis that immune dysregulation during the early stages of T1D development impacts β cell dysfunction in pathways affecting glucose metabolism. The live pancreas tissue slice (LPTS) model is ideal for the study of T1D pathogenesis due to its preservation of the pancreatic environment. LPTS were generated from organ donors without diabetes or autoantibodies (ND, n=9) , donors positive for one or more autoantibodies without a diagnosis of T1D (AAb+, n=6) , and donors with T1D (T1D, n=4) . Imaging studies were conducted to assess the impact of T cell infiltration on β cell function through Ca2+ imaging and slice perifusion. Islets from ND and AAb+ donors had no insulitis and exhibited Ca2+ responses to both high glucose (HG) and potassium chloride (KCl) . A majority of β cell+ islets in tissue from donors with T1D had infiltrating T cells with several having insulitis. Islet HG response from donors with T1D was heterogenous (∼50% failed to respond) while all T1D islets exhibited responses to KCl. Insulin secretion was significantly higher in LPTS from ND donors than in donors with T1D (p=0.0079) . To determine the basis for this loss of function, we assessed transcriptomics of islets within these cohorts. When comparing gene expression levels in islets from ND versus T1D, significant differences were observed in genes involved in glycolysis (GAPDH, p=3.27x10-21) , the citric acid cycle components (OGDH, p=1.88x10-18) , and the electric transport chain (F1FoATP synthase, p=2.69x10-13) . The decreased expression of glucose metabolism genes during T1D development along with the loss of β cell function in LPTS demonstrates β cell dysfunction before their demise and may be a contributory mechanism towards the pathogenesis of disease. Disclosure M.Huber: None. M.Slak rupnik: None. D.M.Drotar: None. H.Hiller: None. M.Beery: None. I.Kusmartseva: None. M.A.Atkinson: None. E.Phelps: Research Support; Immunocore, Ltd. C.E.Mathews: None. Funding National Institutes of Health (5T32DK108736-03) National Institutes of Health (PO1 AI42288)

In vitro profiling of toxic effects of environmental polycyclic aromatic hydrocarbons on nuclear receptor signaling, disruption of endogenous metabolism and induction of cellular stress

Polycyclic aromatic hydrocarbons (PAHs) may interact with multiple intracellular receptors and related signaling pathways. We comprehensively evaluated the toxicity profiles of six environmentally relevant PAHs differing in structure, genotoxicity and their ability to activate the aryl hydrocarbon receptor (AhR). We focused particularly on their impact on intracellular hormone-, xenobiotic- and lipid-sensing receptors, as well as on cellular stress markers, combining a battery of human reporter gene assays and qRT-PCR evaluation of endogenous gene expression in human hepatocyte-like HepaRG cells, with LC/MS-MS analysis of cellular sphingolipids. The effects of PAHs included: activation of estrogen receptor α (in case of fluoranthene (Fla), pyrene (Pyr), benz[a]anthracene (BaA), benzo[a]pyrene (BaP)), suppression of androgen receptor activity (Fla, BaA, BaP and benzo[k]fluoranthene (BkF)), enhancement of dexamethasone-induced glucocorticoid receptor activity (chrysene (Chry), BaA, and BaP), and potentiation of triiodothyronine-induced thyroid receptor α activity (all tested PAHs). PAHs also induced transcription of endogenous gene targets of constitutive androstane receptor (Fla, Pyr), or repression of target genes of pregnane X receptor and peroxisome proliferator-activated receptor α (in case of the AhR-activating PAHs - Chry, BaA, BaP, and BkF) in HepaRG cells. In the same cell model, the AhR agonists reduced the expression of glucose metabolism genes (PCK1, G6PC and PDK4), and they up-regulated levels of glucosylceramides, together with a concomitant induction of expression of UGCG, glucosylceramide synthesis enzyme. Finally, both BaP and BkF were found to induce expression of early stress and genotoxicity markers: ATF3, EGR1, GDF15, CDKN1A/p21, and GADD45A mRNAs, while BaP alone increased levels of IL-6 mRNA. Overall, whereas low-molecular-weight PAHs exerted significant effects on nuclear receptors (with CYP2B6 induction observed already at nanomolar concentrations), the AhR activation by 4-ring and 5-ring PAHs appeared to be a key mechanism underlying their impact on nuclear receptor signaling, endogenous metabolism and induction of early stress and genotoxicity markers.

High glucose induced c-Met activation promotes aggressive phenotype and regulates expression of glucose metabolism genes in HCC cells

Hepatocellular carcinoma (HCC) is strongly associated with metabolic dysregulations/deregulations and hyperglycemia is a common metabolic disturbance in metabolic diseases. Hyperglycemia is defined to promote epithelial to mesenchymal transition (EMT) of cancer cells in various cancers but its molecular contribution to HCC progression and aggressiveness is relatively unclear. In this study, we analyzed the molecular mechanisms behind the hyperglycemia-induced EMT in HCC cell lines. Here, we report that high glucose promotes EMT through activating c-Met receptor tyrosine kinase via promoting its ligand-independent homodimerization. c-Met activation is critical for high glucose induced acquisition of mesenchymal phenotype, survival under high glucose stress and reprogramming of cellular metabolism by modulating glucose metabolism gene expression to promote aggressiveness in HCC cells. The crucial role of c-Met in high glucose induced EMT and aggressiveness may be the potential link between metabolic syndrome-related hepatocarcinogenesis and/or HCC progression. Considering c-Met inhibition in hyperglycemic patients would be an important complementary strategy for therapy that favors sensitization of HCC cells to therapeutics.

Inter- and Transgenerational Effects of Paternal Exposure to Inorganic Arsenic.

The rise of metabolic disorders in modern times is mainly attributed to the environment. However, heritable effects of environmental chemicals on mammalian offsprings' metabolic health are unclear. Inorganic arsenic (iAs) is the top chemical on the Agency for Toxic Substances and Disease Registry priority list of hazardous substances. Here, we assess cross‐generational effects of iAs in an exclusive male‐lineage transmission paradigm. The exposure of male mice to 250 ppb iAs causes glucose intolerance and hepatic insulin resistance in F1 females, but not males, without affecting body weight. Hepatic expression of glucose metabolic genes, glucose output, and insulin signaling are disrupted in F1 females. Inhibition of the glucose 6‐phosphatase complex masks the intergenerational effect of iAs, demonstrating a causative role of hepatic glucose production. F2 offspring from grandpaternal iAs exposure show temporary growth retardation at an early age, which diminishes in adults. However, reduced adiposity persists into middle age and is associated with altered gut microbiome and increased brown adipose thermogenesis. In contrast, F3 offspring of the male‐lineage iAs exposure show increased adiposity, especially on a high‐calorie diet. These findings have unveiled sex‐ and generation‐specific heritable effects of iAs on metabolic physiology, which has broad implications in understanding gene‐environment interactions.

Two-meal caloric restriction induces 12-hour rhythms and improves glucose homeostasis.

Glucose metabolism is tightly regulated and disrupting glucose homeostasis is a hallmark of many diseases. Caloric restriction (CR), periodic fasting, and circadian rhythms are interlinked with glucose metabolism. Here, we directly investigated if CR depends on periodic fasting and circadian rhythms to improve glucose metabolism. CR was implemented as two‐meals per day (2M‐CR), provided at 12‐hour intervals, and compared with one meal per day CR, mealtime (MT), and ad libitum (AL) feeding. The 2M‐CR impacted the circadian rhythms in blood glucose, metabolic signaling, circadian clock, and glucose metabolism gene expression. 2M‐CR significantly reduced around the clock blood glucose and improved glucose tolerance. Twenty‐four‐hour rhythms in mTOR signaling and gene expression observed under AL, MT, and CR, became 12‐hour rhythms in 2M‐CR. The 12‐hour rhythms in behavior, gene expression, and signaling persisted in fasted mice, implicating some internal regulation. The study highlights that the reduction in caloric intake rather than meal frequency and duration of fasting is essential for metabolic reprograming and improvement in glucose metabolism and provides evidence on food‐entrained molecular pacemaker, which can be uncoupled from the light‐entrained circadian clock and rhythms.

Identification of a novel association for the WWOX/HIF1A axis with gestational diabetes mellitus (GDM).

BackgroundAlthough the WW-domain-containing oxidoreductase (WWOX)/Hypoxia-inducible factor 1 (HIF1) pathway is a well-known regulator of cellular glucose and energy metabolism in pathophysiological processes, its role in gestational diabetes mellitus (GDM), remains elusive. We undertook this study to determine the effect of WWOX/HIF1A signaling on the expression of glucose metabolism genes in GDM patients.MethodsLeukocytes were obtained from 135 pregnant women with (n = 98) or without (n = 37) GDM and, in turn, 3 months (n = 8) and 1 year (n = 12) postpartum. Quantitative RT-PCR was performed to determine gene expression profiles of the WWOX/HIF1A-related genes, including those involved in glucose transport (SLC2A1, SLC2A4), glycolytic pathway (HK2, PKM2, PFK, LDHA), Wnt pathway (DVL2, CTNNB1), and inflammatory response (NFKB1).ResultsGDM patients displayed a significant downregulation of WWOX with simultaneous upregulation of HIF1A which resulted in approximately six times reduction in WWOX/HIF1A ratio. As a consequence, HIF1A induced genes (SLC2A1, HK2, PFK, PKM) were found to be overexpressed in GDM compared to normal pregnancy and negative correlate with WWOX/HIF1A ratio. The postpartum WWOX expression was higher than during GDM, but its level was comparable to that observed in normal pregnancy.ConclusionsThe obtained results suggest a significant contribution of the WWOX gene to glucose metabolism in patients with gestational diabetes. Decreased WWOX expression in GDM compared to normal pregnancy, and in particular reduction of WWOX/HIF1A ratio, indicate that WWOX modulates HIF1α activity in normal tissues as described in the tumor. The effect of HIF1α excessive activation is to increase the expression of genes encoding proteins directly involved in the glycolysis which may lead to pathological changes in glucose metabolism observed in gestational diabetes.

Effects of Intermittent Hypoxia on Expression of Glucose Metabolism Genes in MCF7 Breast Cancer Cell Line.

Hypoxic condition induces molecular alterations which affect the survival rate and chemo-resistant phenotype of cancer cells. The aim of this study is to investigate the influence of intermittent hypoxic conditions on the expression of glucose metabolism genes in breast cancer MCF7 cell line. The gene expression was analyzed using a polymerase chain reaction-array method. In addition, the cell resistance, survival and migration rates were examined to assure the hypoxic influence on the cells. 30 hypoxic episodes induced the Warburg effect through significant (p-value < 0.05) upregulation of the expression of PCK2, PHKG1, ALDOC, G6PC, GYS2, ALDOB, HK3, PKLR, PGK2, PDK2, ACO1 and H6PD genes that are involved in glycolysis, were obtained. Furthermore, the expression of the major gluconeogenesis enzyme genes was significantly (ANOVA, p-value < 0.05) downregulated. These molecular alterations were associated with increased MCF7 cell division and migration rate. However, molecular and phenotypic changes induced after 30 episodes were normalized in MCF7 cells exposed to 60 hypoxic episodes. It is concluded, from this study, that 30 intermitted hypoxic episodes increased the survival rate of MCF7 breast cancer cells and induced the Warburg effect through upregulation of the expression of genes involved in the glycolysis pathway. These results may increase our understanding of the molecular alterations of breast cancer cells under hypoxic conditions.

Reduced caloric intake and periodic fasting independently contribute to metabolic effects of caloric restriction.

Caloric restriction (CR) has positive effects on health and longevity. CR in mammals implements time‐restricted (TR) feeding, a short period of feeding followed by prolonged fasting. Periodic fasting, in the form of TR or mealtime, improves metabolism without reduction in caloric intake. In order to understand the relative contribution of reduced food intake and periodic fasting to the health benefits of CR, we compared physiological and metabolic changes induced by CR and TR (without reduced food intake) in mice. CR significantly reduced blood glucose and insulin around the clock, improved glucose tolerance, and increased insulin sensitivity (IS). TR reduced blood insulin and increased insulin sensitivity, but in contrast to CR, TR did not improve glucose homeostasis. Liver expression of circadian clock genes was affected by both diets while the mRNA expression of glucose metabolism genes was significantly induced by CR, and not by TR, which is in agreement with the minor effect of TR on glucose metabolism. Thus, periodic fasting contributes to some metabolic benefits of CR, but TR is metabolically different from CR. This difference might contribute to differential effects of CR and TR on longevity.

Glucose homeostasis and glucose tolerance were impaired with elevated lipid to starch ratios in practical diets for the omnivorous genetically improved farmed tilapia Oreochromis niloticus

The present study was performed to ascertain if glucose metabolism and glucose tolerance could be regulated by dietary lipid to starch ratios in the omnivorous genetically improved farmed tilapia Oreochromis niloticus. Three isonitrogenous (ca 34.5% protein) and isocaloric (ca 14.5 kJ/g) practical diets were formulated with elevated lipid at the cost of starch provision, being designated as diets L6S23 (5.55% lipid and 22.5% starch), L9S18 (8.77% lipid and 18.1% starch) and L12S13 (12.0% lipid and 13.8% starch). Tilapia juveniles (initial mean body weight: 23.0 g/fish) were allocated to 12 rectangular tanks (250 L) with 20 fish per tank, and were fed experimental diets to apparent satiation for 8 weeks. At the end of the trial, approximately 24 h after the last feeding, fish in each tank were bulk-weighed and counted. Nine fish per tank were sampled to analyze the whole-body composition (3 fish), blood chemistry (3 fish) and the expression of glucose-metabolic genes (3 fish). Thirty-six of the remaining fish per treatment were subjected to an acute glucose tolerance test. The results showed that the growth (weight gain) and feed utilization (feed and protein efficiency ratios) of tilapia were not affected by different treatments. Intraperitoneal fat ratio (1.32%) and lipid percentages in the liver (9.69%) and whole-body (10.2%) of the L12S13 fish were higher than those of the L6S23 fish (0.75%, 6.61% and 8.17%, respectively). The L9S18 (5.24 mmol/L) and L12S13 fish (5.59 mmol/L) obtained higher plasma glucose levels than the L6S23 fish (4.10 mmol/L). In the liver, the mRNA levels of representative genes involved in glycolysis (glucokinase) and glucose release (glucose-6-phosphatase catalytic subunit a2) were simultaneously up-regulated in the L12S13 fish as compared with the L6S23 fish, indicating that a futile cycle between glucose and glucose-6-phosphate was associated with elevated dietary lipid to starch ratios. In the white muscle, the mRNA levels of glucose transporter 1a (glut1a), glut4, hexokinase 1b, phosphofructokinase muscle type a (pfkma), pfkmb and glycogen synthase 1 were 0.44-, 0.71-, 0.58-, 0.51-, 0.72- and 0.53-fold lower in the L12S13 fish than in the L6S23 fish, suggesting that muscular glucose transport and utilization were depressed with elevated dietary lipid to starch ratios. Although it took similar time (3 h) to restore plasma glucose for all treatments, plasma glucose was lower in the L6S23 fish than in the L12S13 fish during 1–3 h after the glucose injection. Additionally, plasma glucose of the L9S18 and L12S13 fish decreased continually along the injection time (during 7–10 h) as compared with the L6S23 fish, which further proved that the regulatory mechanisms of glucose homeostasis were impaired in tilapia that were fed elevated lipid to starch ratios. Our data confirmed that the impairment of glucose homeostasis was also associated with high fat diet reception in the omnivorous tilapia.

Localisation of PGK1 determines metabolic phenotype to balance metastasis and proliferation in patients with SMAD4-negative pancreatic cancer

ObjectivePancreatic ductal adenocarcinoma (PDAC) is the most aggressive type of GI tumour, and it possesses deregulated cellular energetics. Although recent advances in PDAC biology have led to the discovery of...

Abstract # 3188 Spinal cord injury perturbs circadian rhythms

Spinal cord injury (SCI) can disrupt many physiological functions. The circadian system helps maintain homeostasis throughout the body by regulating daily rhythms in physiology and behavior. Circadian rhythms likely exist in all cell throughout the body, yet whether SCI alters daily rhythms remains under-studied. Here, we hypothesized that SCI in rats would disrupt several prominent circadian outputs including glucocorticoids, core temperature, activity, and circadian/inflammatory gene expression. Female and male rats received clinically relevant thoracic (T-) 8 moderate-to-severe contusion SCI (or laminectomy sham surgery). Circadian measures – including rhythms of plasma corticosterone, body temperature and activity (using small implanted transmitters), plasma glucose, and gene expression – were studied before and after surgery. First, we found that SCI disrupted intraspinal and peripheral rhythms of clock and inflammatory gene expression. Circadian rhythms in peripheral cells are entrained by “oscillatory factors”, including glucocorticoids, body temperature, and activity. SCI increased and disrupted rhythms of the major rodent glucocorticoid, corticosterone. Pre-surgery and sham rats displayed expected rhythms in activity and body temperature, whereas SCI rats had blunted daily rhythms in activity and body temperature. In parallel, SCI increased plasma glucose and liver expression of glucose metabolism genes. Our data show that moderate SCI in rats causes wide-ranging circadian dysfunction that is severe at acute time points and gradually recovers. Normalizing post-SCI circadian rhythms could enhance recovery of homeostasis and quality-of-life.

Glucose Metabolism Gene Expression Patterns and Tumor Uptake of 18F-Fluorodeoxyglucose After Radiation Treatment

To investigate whether radiation treatment influences the expression of glucose metabolism genes and compromises the potential use of (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) as a tool to monitor the early response of head and neck cancer xenografts to radiation therapy (RT). Low passage head and neck squamous cancer cells (UT14) were injected to the flanks of female nu/nu mice to generate xenografts. After tumors reached a size of 500 mm(3) they were treated with either sham RT or 15 Gy in 1 fraction. At different time points, days 3, 9, and 16 for controls and days 4, 7, 12, 21, 30, and 40 after irradiation, 2 to 3 mice were assessed with dynamic FDG-PET acquisition over 2 hours. Immediately after the FDG-PET the tumors were harvested for global gene expression analysis and immunohistochemical evaluation of GLUT1 and HK2. Different analytic parameters were used to process the dynamic PET data. Radiation had no effect on key genes involved in FDG uptake and metabolism but did alter other genes in the HIF1α and glucose transport-related pathways. In contrast to the lack of effect on gene expression, changes in the protein expression patterns of the key genes GLUT1/SLC2A1 and HK2 were observed after radiation treatment. The changes in GLUT1 protein expression showed some correlation with dynamic FDG-PET parameters, such as the kinetic index. (18)F-fluorodeoxyglucose positron emission tomography changes after RT would seem to represent an altered metabolic state and not a direct effect on the key genes regulating FDG uptake and metabolism.

Glucose Metabolism Gene Expression Patterns and Tumor Uptake of 18F-FDG Following Radiation Treatment

To investigate whether radiation treatment influences the expression of glucose metabolism genes and compromises the potential use of 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET) as a tool to monitor the early response of head neck cancer xenografts to radiation therapy (RT).

Multiple signals modulate the activity of the complex sensor kinase TodS.

The reason for the existence of complex sensor kinases is little understood but thought to lie in the capacity to respond to multiple signals. The complex, seven-domain sensor kinase TodS controls in concert with the TodT response regulator the expression of the toluene dioxygenase pathway in Pseudomonas putida F1 and DOT-T1E. We have previously shown that some aromatic hydrocarbons stimulate TodS activity whereas others behave as antagonists. We show here that TodS responds in addition to the oxidative agent menadione. Menadione but no other oxidative agent tested inhibited TodS activity in vitro and reduced PtodX expression in vivo. The menadione signal is incorporated by a cysteine-dependent mechanism. The mutation of the sole conserved cysteine of TodS (C320) rendered the protein insensitive to menadione. We evaluated the mutual opposing effects of toluene and menadione on TodS autophosphorylation. In the presence of toluene, menadione reduced TodS activity whereas toluene did not stimulate activity in the presence of menadione. It was shown by others that menadione increases expression of glucose metabolism genes. The opposing effects of menadione on glucose and toluene metabolism may be partially responsible for the interwoven regulation of both catabolic pathways. This work provides mechanistic detail on how complex sensor kinases integrate different types of signal molecules.

Zonation of nitrogen and glucose metabolism gene expression upon acute liver damage in mouse.

Zonation of metabolic activities within specific structures and cell types is a phenomenon of liver organization and ensures complementarity of variant liver functions like protein production, glucose homeostasis and detoxification. To analyze damage and regeneration of liver tissue in response to a toxic agent, expression of liver specific enzymes was analyzed by in situ hybridization in mouse over a 6 days time course following carbon tetrachloride (CCl4) injection. CCl4 mixed with mineral oil was administered to BALB/c mice by intraperitoneal injection, and mice were sacrificed at different time points post injection. Changes in the expression of albumin (Alb), arginase (Arg1), glutaminase 2 (Gls2), Glutamine synthetase (Gs), glucose-6-phosphatase (G6pc), glycogen synthase 2 (Gys2), Glycerinaldehyd-3-phosphat-Dehydrogenase (Gapdh), Cytochrom p450 2E1 (Cyp2e1) and glucagon receptor (Gcgr) genes in the liver were studied by in situ hybridization and qPCR. We observed significant changes in gene expression of enzymes involved in nitrogen and glucose metabolism and their local distribution following CCl4 injury. We also found that Cyp2e1, the primary metabolizing enzyme for CCl4, was strongly expressed in the pericentral zone during recovery. Furthermore, cells in the damaged area displayed distinct gene expression profiles during the analyzed time course and showed complete recovery with strong albumin production 6 days after CCl4 injection. Our results indicate that despite severe damage, liver cells in the damaged area do not simply die but instead display locally adjusted gene expression supporting damage response and recovery.