Home About us Contact
|
Home About us Contact | ||
|
|
||
Increased Transcription (increased + transcription)
Selected AbstractsIron availability affects mcyD expression and microcystin-LR synthesis in Microcystis aeruginosa PCC7806ENVIRONMENTAL MICROBIOLOGY, Issue 10 2008Emma Sevilla Summary Microcystins are toxins produced by cyanobacteria that entail serious health and environmental problems. They are cyclic heptapeptides synthesized via a mixed polyketide synthase/non-ribosomal peptide synthetase system called microcystin synthetase. Environmental and nutritional factors that trigger microcystin synthesis are still debated and this work deals with the study of the influence of iron nutritional status on the microcystin synthesis. The results indicate that iron deficiency could be one of the inducing factors of the microcystin synthesis. For the first time, increased transcription of an essential mcy gene and correlative microcystin synthesis has been established. Real-time PCR analysis of mcyD, and microcystin-LR synthesis were studied on Microcystis aeruginosa PCC7806 grown in iron-replete and iron-deplete media. Iron starvation causes an increase of mcyD transcription, correlative to the increase of microcystin-LR levels. Four transcription start points were identified for mcyD and two for mcyA, and they are not changed as a consequence of iron deficiency. [source] Transcriptional regulation of tumor necrosis factor-, in keratinocytes mediated by interleukin-1, and tumor necrosis factor-,EXPERIMENTAL DERMATOLOGY, Issue 6 2002S. Lisby Abstract: Irritant contact dermatitis (ICD) is an inflammatory skin reaction in which cytokines are thought to play a crucial role. In particular, tumor necrosis factor-, (TNF-,) has been implicated in the mechanism of this reaction. We report that interleukin-1, (IL-1,) that has been reported up-regulated in many inflammatory skin conditions is capable of increasing TNF-, mRNA and protein expression in murine keratinocytes. Furthermore, we show that TNF-, is capable of up-regulating itself in keratinocytes most likely in an autocrine manner. The signalling mechanisms involved in both IL-1,- and TNF-,-mediated regulation of TNF-, are critically dependent upon protein kinase C (PKC), as demonstrated by blocking studies using protein kinase inhibitors. Furthermore, the increase in TNF-, mRNA expression seen after stimulation with rTNF-, and rIL-1, involved increased transcription of TNF-, mRNA. This was demonstrated in a chloramphenicol acetyltransferase (CAT) assay using a CAT-construct containing the full-length TNF-, promoter. These observations support the notion of keratinocytes functioning as an amplifier of pro-inflammatory cytokine generation in the epidermis during ICD and other inflammatory skin conditions. [source] The Effects of Steroid Hormones on the Transcription of Genes Encoding Enzymes of Oxidative PhosphorylationEXPERIMENTAL PHYSIOLOGY, Issue 1 2003Klaus Scheller Regulation of energy metabolism is one of the major functions of steroid hormones. In this process, mitochondria, by way of oxidative phosphorylation, play a central role. Depending on the energy needs of the cell, on the tissue, on the developmental stage and on the intensity of the hormonal stimulus, the response can be an activation of pre-existing respiratory chain components, an increased transcription of nuclear-encoded and/or mitochondrial-encoded respiratory chain enzyme (OXPHOS) genes and of biosynthesis of the respective enzyme subunits or, in extreme cases of high energy needs, an increase in the number of mitochondria and mitochondrial DNA content per cell. Some of the hormonally regulated systems involving effects on nuclear and mitochondrial OXPHOS genes are reviewed in this paper. The possible molecular mechanisms of steroid hormone action on nuclear and mitochondrial gene transcription and possible ways of coordination of transcription in these two separate cell compartments involving direct interaction of steroid receptors with hormone response elements in nuclear OXPHOS genes and in mitochondria and induction/activation of nuclear-encoded regulatory factors affecting mitochondrial gene transcription are presented. [source] Hypoxia-inducible factor 1, is up-regulated by oncostatin M and participates in oncostatin M signaling,HEPATOLOGY, Issue 1 2009Stefan Vollmer The interleukin-6,type cytokine oncostatin M (OSM) acts via the Janus kinase/signal transducer and activator of transcription pathway as well as via activation of mitogen-activated protein kinases and is known to critically regulate processes such as liver development and regeneration, hematopoiesis, and angiogenesis, which are also determined by hypoxia with the hypoxia-inducible factor 1, (HIF1,) as a key component. Here we show that treatment of hepatocytes and hepatoma cells with OSM leads to an increased protein level of HIF1, under normoxic and hypoxic conditions. Furthermore, the OSM-dependent HIF1, increase is mediated via Janus kinase/signal transducer and activator of transcription 3 and mitogen-activated protein kinase kinase/extracellular signal-regulated kinase 1/2 pathways. OSM-mediated HIF1, up-regulation did not result from an increase in HIF1, protein stability but from increased transcription from the HIF1, gene. In addition, we show that the OSM-induced HIF1, gene transcription and the resulting enhanced HIF1, protein levels are important for the OSM-dependent vascular endothelial growth factor and plasminogen activator inhibitor 1 gene induction associated with several diseases. Conclusion: HIF1, levels increase significantly after treatment of hepatocytes and hepatoma cells with OSM, and HIF1, contributes to OSM downstream signaling events, pointing to a cross-talk between cytokine and hypoxia signaling in processes such as liver development and regeneration. (HEPATOLOGY 2009.) [source] Enhanced expression of MMP-7 and MMP-13 in inflammatory bowel disease: A precancerous potential?INFLAMMATORY BOWEL DISEASES, Issue 11 2006Dr. Timo Rath PhD Abstract Matrix metalloproteinases (MMPs) are responsible for the turnover and degradation of extracellular matrix. They play a crucial role in the growth and migration of colorectal carcinoma cells. Colorectal carcinomas are characterized by enhanced expression of MMP-2, MMP-9, MMP-7, and MMP-13. The aim of this study was to determine the expression levels of MMP-2, MMP-9, MMP-7, MMP-13, and MMP-14 and their specific inhibitor TIMP-1 in inflammatory bowel diseases and precancerous lesions of the colon, i.e., Crohn's disease and ulcerative colitis, and in adenomatous polyps (APs) for comparison. Biopsy samples of pathological and healthy tissue were obtained from 40 patients with inflammatory bowel disease (ulcerative colitis, n = 17; Crohn's disease, n = 23) and from 19 patients with APs. mRNA was measured by quantitative real-time polymerase chain reaction to study MMP and TIMP-1 gene expression in both pathological and normal mucosal specimens. For MMP-2, MMP-9, and TIMP-1, protein expression also was quantified with sandwich enzyme-linked immunosorbent assay. In biopsy specimens of Crohn's disease and ulcerative colitis, significantly increased levels of MMP-2, MMP-7, and MMP-13 mRNA were found. MMP-2 and MMP-9 showed enhanced secretion on the protein level. AP revealed an increased transcription of MMP-7 and MMP-13 genes. MMP-14 mRNA was decreased in APs. MMPs, especially MMP-7 and MMP-13, which are expressed primarily on the tumor cell surface, are elevated in inflammatory bowel disease, which may have more chance to evolve into malignancy than normal tissue. In APs, increased expression of MMP-7 and MMP-13 may serve as an early indicator for colorectal carcinogenesis. [source] GeneChip® analysis after acute spinal cord injury in ratJOURNAL OF NEUROCHEMISTRY, Issue 4 2001Guoqing Song Spinal cord injury (SCI) leads to induction and/or suppression of several genes, the interplay of which governs the neuronal death and subsequent loss of motor function. Using GeneChip®, the present study analyzed changes in the mRNA abundance at 3 and 24 h after SCI in adult rats. SCI was induced at T9 level by the New York University impactor by dropping a 10-g weight from a height of 25 mm. Several transcription factors, immediate early genes, heat-shock proteins, pro-inflammatory genes were up-regulated by 3 h, and persisted at 24 h, after SCI. On the other hand, some neurotransmitter receptors and transporters, ion channels, kinases and structural proteins were down-regulated by 3 h, and persisted at 24 h, after SCI. Several genes that play a role in growth/differentiation, survival and neuroprotection were up-regulated at 24 h after SCI. Using real-time quantitative PCR, the changes observed by GeneChip® were confirmed for seven up-regulated (interleukin-6, heat-shock protein-70, heme oxygenase-1, suppressor of cytokine signaling 2, suppressor of cytokine signaling 3, interferon regulatory factor-1, neuropeptide Y), two down-regulated (vesicular GABA transporter and cholecystokinin precursor) and two unchanged (Cu/Zn-superoxide dismutase and phosphatidyl inositol-3-kinase) genes. The present study shows that inflammation, neurotransmitter dysfunction, increased transcription, ionic imbalance and cytoskeletal damage starts as early as 3 h after SCI. In addition to these effects, 24 h after SCI the repair and regeneration process begins in an attempt to stabilize the injured spinal cord. [source] Characterization of thromboxane A2 receptor signaling in developing rat oligodendrocytes: Nuclear receptor localization and stimulation of myelin basic protein expressionJOURNAL OF NEUROSCIENCE RESEARCH, Issue 7 2006Santosh Ramamurthy Abstract The present work investigates the role of thromboxane A2 (TXA2) receptors in the development of oligodendrocytes (OLGs). The results demonstrate that the proteins of the TXA2 signaling pathway, i.e., cyclooxygenase (COX-1), TXA2 synthase (TS), and TXA2 receptor (TPR) are expressed in the developing rat brain during myelination. Furthermore, culture of OLG progenitor cells (OPCs) revealed that the expression levels of these proteins as well as TXA2 synthesis increase during OLG maturation. Separate studies established that activation of TPRs by the agonist U46619 increases intracellular calcium in both OPCs and OLGs as visualized by digital fluorescence imaging. Immunocytochemical staining demonstrated that TPRs are localized in the plasma membrane and perinuclear compartments in OPCs. However, during OLG differentiation, TPRs shift their localization pattern and also become associated with the nuclear compartment. This shift to nuclear localization was confirmed by biochemical analysis in cultured cells and by immunocytochemical analysis in developing rat brain. Finally, it was found that U46619 activation of TPRs in maturing OLGs resulted in enhanced myelin basic protein (MBP) expression. Alternatively, inhibition of endogenous TPR signaling led to reduced MBP expression. Furthermore, TPR-mediated MBP expression was found to be associated with increased transcription from the MBP promoter using a MBP-luciferase reporter. Collectively, these findings suggest a novel TPR signaling pathway in OLGs and a potential role for this signaling during OLG maturation and myelin production. © 2006 Wiley-Liss, Inc. [source] Phosphate availability regulates biosynthesis of two antibiotics, prodigiosin and carbapenem, in Serratia via both quorum-sensing-dependent and -independent pathwaysMOLECULAR MICROBIOLOGY, Issue 2 2003Holly Slater Summary Serratia sp. ATCC 39006 produces two secondary metabolite antibiotics, 1-carbapen-2-em-3-carboxylic acid (Car) and the red pigment, prodigiosin (Pig). We have previously reported that production of Pig and Car is controlled by N -acyl homoserine lactone (N -AHL) quorum sensing, with synthesis of N -AHLs directed by the LuxI homologue SmaI, and is also regulated by Rap, a member of the SlyA family. We now describe further characterization of the SmaI quorum-sensing system and its connection with other regulatory mechanisms. We show that the genes responsible for biosynthesis of Pig, pigA,O, are transcribed as a single polycistronic message in an N -AHL-dependent manner. The smaR gene, transcribed convergently with smaI and predicted to encode the LuxR homologue partner of SmaI, was shown to possess a negative regulatory function, which is uncommon among the LuxR-type transcriptional regulators. SmaR represses transcription of both the pig and car gene clusters in the absence of N -AHLs. Specifically, we show that SmaIR exerts its effect on car gene expression via transcriptional control of carR, encoding a pheromone-independent LuxR homologue. Transcriptional activation of the pig and car gene clusters also requires a functional Rap protein, but Rap dependency can be bypassed by secondary mutations. Transduction of these suppressor mutations into wild-type backgrounds confers a hyper-Pig phenotype. Multiple mutations cluster in a region upstream of the pigA gene, suggesting this region may represent a repressor target site. Two mutations mapped to genes encoding pstS and pstA homologues, which are parts of a high-affinity phosphate transport system (Pst) in Escherichia coli. Disruption of pstS mimicked phosphate limitation and caused concomitant hyper-production of Pig and Car, which was mediated, in part, through increased transcription of the smaI gene. The Pst and SmaIR systems define distinct, yet overlapping, regulatory circuits which form part of a complex regulatory network controlling the production of secondary metabolites in Serratia ATCC 39006. [source] Differential changes in brain-derived neurotrophic factor and extracellular signal-regulated kinase in rat primary afferent pathways with colitisNEUROGASTROENTEROLOGY & MOTILITY, Issue 8 2008L.-y. Qiao Abstract, Brain-derived neurotrophic factor (BDNF) has been postulated to participate in inflammation-induced visceral hypersensitivity by modulating the sensitivity of visceral afferents through the activation of intracellular signalling pathways such as the extracellular signal-regulated kinase (ERK) pathway. In the current study, we assessed the expression levels of BDNF and phospho-ERK in lumbosacral dorsal root ganglia (DRG) and spinal cord before and during tri-nitrobenzene sulfonic acid (TNBS)-induced colitis in rats with real-time PCR, ELISA, western blot and immunohistochemical techniques. BDNF mRNA and protein levels were increased in L1 and S1 but not L6 DRG when compared with control (L1: two- to five-fold increases, P < 0.05; S1: two- to three-fold increases, P < 0.05); however, BDNF protein but not mRNA level was increased in L1 and S1 spinal cord when compared with control. In parallel, TNBS colitis significantly induced phospho-ERK1/2 expression in L1 (four- to five-fold, P < 0.05) and S1 (two- to three-fold, P < 0.05) but not in L6 spinal cord levels. Immunohistochemistry results showed that the increase in phospho-ERK1/2 expression occurred at the region of the superficial dorsal horn and grey commisure of the spinal cord. In contrast, there was no change in phospho-ERK5 in any level of the spinal cord examined during colitis. The regional and time-specific changes in the levels of BDNF mRNA, protein and phospho-ERK with colitis may be a result of increased transcription of BDNF in DRG and anterograde transport of BDNF from DRG to spinal cord where it activates intracellular signalling molecules such as ERK1/2. [source] Knockout of major leaf ferredoxin reveals new redox-regulatory adaptations in Arabidopsis thalianaPHYSIOLOGIA PLANTARUM, Issue 3 2008Ingo Voss Ferredoxins are the major distributors for electrons to the various acceptor systems in plastids. In green tissues, ferredoxins are reduced by photosynthetic electron flow in the light, while in heterotrophic tissues, nicotinamide adenine dinucleotide (reduced) (NADPH) generated in the oxidative pentose-phosphate pathway (OPP) is the reductant. We have used a Ds -T-DNA insertion line of Arabidopsis thaliana for the gene encoding the major leaf ferredoxin (Fd2, At1g60950) to create a situation of high electron pressure in the thylakoids. Although these plants (Fd2-KO) possess only the minor fraction of leaf Fd1 (At1g10960), they grow photoautotrophically on soil, but with a lower growth rate and less chlorophyll. The more oxidized conditions in the stroma due to the formation of reactive oxygen species are causing a re-adjustment of the redox state in these plants that helps them to survive even under high light. Redox homeostasis is achieved by regulation at both, the post-translational and the transcriptional level. Over-reduction of the electron transport chain leads to increased transcription of the malate-valve enzyme NADP-malate dehydrogenase (MDH), and the oxidized stroma leads to an increased transcription of the OPP enzyme glucose-6-P dehydrogenase. In isolated spinach chloroplasts, oxidized conditions give rise to a decreased activation state of NADP-MDH and an activation of glucose-6-P dehydrogenase even in the light. In Fd2-KO plants, NADPH-requiring antioxidant systems are upregulated. These adjustments must be caused by plastid signals, and they prevent oxidative damage under rather severe conditions. [source] Temporal changes in the involvement of pyruvate dehydrogenase complex in muscle lactate accumulation during lipopolysaccharide infusion in ratsTHE JOURNAL OF PHYSIOLOGY, Issue 6 2008N. Alamdari A characteristic manifestation of sepsis is muscle lactate accumulation. This study examined any putative (causative) association between pyruvate dehydrogenase complex (PDC) inhibition and lactate accumulation in the extensor digitorum longus (EDL) muscle of rats infused with lipopolysaccharide (LPS), and explored the involvement of increased transcription of muscle-specific pyruvate dehydrogenase kinase (PDK) isoenzymes. Conscious, male Sprague,Dawley rats were infused i.v. with saline (0.4 ml h,1, control) or LPS (150 ,g kg,1 h,1) for 2 h, 6 h or 24 h (n= 6,8). Muscle lactate concentration was elevated after 2, 6 and 24 h LPS infusion. Muscle PDC activity was the same at 2 h and 6 h, but was 65% lower after 24 h of LPS infusion (P < 0.01), when there was a 47% decrease in acetylcarnitine concentration (P < 0.05), and a 24-fold increase in PDK4 mRNA expression (P < 0.001). These changes were preceded by marked increases in tumour necrosis factor-, and interleukin-6 mRNA expression at 2 h. The findings indicate that the early (2 and 6 h) elevation in muscle lactate concentration during LPS infusion was not attributable to limited muscle oxygen availability or ATP production (evidenced by unchanged ATP and phosphocreatine (PCr) concentrations) or to PDC inhibition, whereas after 24 h, muscle lactate accumulation appears to have resulted from PDC activation status limiting pyruvate flux, most probably due to cytokine-mediated up-regulation of PDK4 transcription. [source] Role of Interleukins and Transforming Growth Factor-, in Chronic Rhinosinusitis and Nasal PolyposisTHE LARYNGOSCOPE, Issue 4 2005Dewayne T. Bradley MD Abstract Objectives: To determine the role of interleukin (IL)-4, IL-4 receptor (R), IL-6, IL-8, IL-11, and transforming growth factor (TGF)-, in chronic rhinosinusitis (CRS) and chronic rhinosinusitis with nasal polyposis (CRS/NP). Methods: Sinus tissue from patients undergoing endoscopic sinus surgery for CRS and CRS/NP was collected. Sinus tissue was then analyzed using reverse-transcription polymerase chain reaction (RT-PCR) to detect transcription of IL-4R, IL-6, IL-8, and IL-11. Sinus tissue samples were also cultured in vitro, treated with IL-4 for 24 hours, and real-time PCR was used to quantify the transcription of TGF-,. Results: Twenty patients were evaluated, 9 with CRS/NP and 11 with CRS alone. The mean age was 43 (20,74) years, with 13 females and 7 males. IL-4R, IL-6, IL-8, and IL-11 were identified by RT-PCR in all 20 patients. The transcription of TGF-, was found to be 3.2 times greater in patients with CRS/NP than in patients with CRS alone (P = .047). Conclusion: IL-6, IL-8, and IL-11 are nonspecific markers of sinus inflammation being transcribed in patients with CRS and patients with CRS/NP. However, patients with CRS/NP demonstrate increased transcription of TGF-, in response to IL-4 treatment, suggesting an IL-4 mediated mechanism for stromal proliferation in the formation of nasal polyposis. [source] Bcl-2 mediated modulation of vascularization in prostate cancer xenografts,THE PROSTATE, Issue 5 2009Yoshihisa Sakai Abstract PURPOSE We previously demonstrated that Bcl-2 overexpression enhances the radiation resistance of PC-3 human prostate cancer cells and xenografts by inhibiting apoptosis, increasing proliferation, and promoting angiogenesis. To further elucidate the relationship between Bcl-2 expression and the angiogenic potential of PC-3-Bcl-2 cells, tumorigenicity, angiogenesis, and lymphangiogenesis were evaluated and compared in a Bcl-2 overexpressing clone in vitro and in vivo. EXPERIMENTAL DESIGN Human prostate cancer cells over expressing Bcl-2 were studied in vitro and in vivo to determine the angiogenic and lymphangiogenic properties of these cells. RESULTS Increased Bcl-2 expression enhanced the tumorigenicity of prostate cancer xenografts. It also enhanced the expression and secretion of key angiogenic and lymphangiogenic factors that stimulated the synthesis of CD31-positive blood vessels and LYVE-1 positive lymphatics. Specifically, the increased angiogenic and lymphangiogenic potential correlated with increased serum levels of basic fibroblast growth factor (bFGF), interleukin 8 (CXCL8), and matrix metalloproteinase (MMP 9). In vitro analysis demonstrated that Bcl-2 expressing tumor cells secreted bFGF and vascular endothelial growth factor (VEGF) into culture supernatants. Microarray analysis of Bcl-2 expressing PC-3 cells demonstrated increased transcription of genes involved in metabolism, such as interleukins, growth factors, tumor necrosis factors (TNF) family members, and peptidases. CONCLUSIONS Together, these results demonstrate that Bcl-2 can regulate tumoral angiogenesis and lymphangiogenesis and suggest that therapy targeted at Bcl-2 expression, angiogenesis, and lymphangiogenesis may synergistically modulate tumor growth and confirm that Bcl-2 is a pivotal target for cancer therapy. Prostate 69:459,470, 2009. © 2008 Wiley-Liss, Inc. [source] Genetic variants and disease-associated factors contribute to enhanced interferon regulatory factor 5 expression in blood cells of patients with systemic lupus erythematosusARTHRITIS & RHEUMATISM, Issue 2 2010Di Feng Objective Genetic variants of the interferon (IFN) regulatory factor 5 gene (IRF5) are associated with susceptibility to systemic lupus erythematosus (SLE). The contribution of these variants to IRF-5 expression in primary blood cells of SLE patients has not been addressed, nor has the role of type I IFNs. The aim of this study was to determine the association between increased IRF-5 expression and the IRF5 risk haplotype in SLE patients. Methods IRF-5 transcript and protein levels in 44 Swedish patients with SLE and 16 healthy controls were measured by quantitative real-time polymerase chain reaction, minigene assay, and flow cytometry. Single-nucleotide polymorphisms rs2004640, rs10954213, and rs10488631 and the CGGGG insertion/deletion were genotyped in these patients. Genotypes of these polymorphisms defined both a common risk haplotype and a common protective haplotype. Results IRF-5 expression and alternative splicing were significantly up-regulated in SLE patients compared with healthy donors. Enhanced transcript and protein levels were associated with the risk haplotype of IRF5; rs10488631 displayed the only significant independent association that correlated with increased transcription from the noncoding first exon 1C. Minigene experiments demonstrated an important role for rs2004640 and the CGGGG insertion/deletion, along with type I IFNs, in regulating IRF5 expression. Conclusion This study provides the first formal proof that IRF-5 expression and alternative splicing are significantly up-regulated in primary blood cells of patients with SLE. Furthermore, the risk haplotype is associated with enhanced IRF-5 transcript and protein expression in patients with SLE. [source] Differential Extracellular Signal-Regulated Kinases 1 and 2 Activation by the Angiotensin Type 1 Receptor Supports Distinct Phenotypes of Cardiac MyocytesBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 5 2007Mark Aplin The biological importance of this, however, remains obscure. Application of the modified analogue [Sar1, Ile4, Ile8]-AngII ([SII] AngII) allowed us to dissect the two pathways of ERK1/2 activation in native cardiac myocytes. Although cytosol-retained, the ,-arrestin2-bound pool of ERK1/2 represents an active signalling component that phosphorylates p90 Ribosomal S6 Kinase, a ubiquitous and versatile mediator of ERK1/2 signal transduction. Moreover, the ,-arrestin2-dependent ERK1/2 signal supports intact proliferation of cardiac myocytes. In contrast to Gq -activated ERK1/2, and in keeping with its failure to translocate to the nucleus, the ,-arrestin2-scaffolded pool of ERK1/2 does not phosphorylate the transcription factor Elk-1, induces no increased transcription of the immediate-early gene c-Fos, and does not entail myocyte hypertrophy. These results clearly demonstrate the biological significance of differential signalling by the AT1R. The opportunity to separate desirable cardiac myocyte division from detrimental hypertrophy holds promise that novel pharmacological approaches will allow targeting of pathway-specific actions. [source] Glutamine metabolism: Role in acid-base balance,BIOCHEMISTRY AND MOLECULAR BIOLOGY EDUCATION, Issue 5 2004Lynn Taylor Abstract The intent of this review is to provide a broad overview of the interorgan metabolism of glutamine and to discuss in more detail its role in acid-base balance. Muscle, adipose tissue, and the lungs are the primary sites of glutamine synthesis and release. During normal acid-base balance, the small intestine and the liver are the major sites of glutamine utilization. The periportal hepatocytes catabolize glutamine and convert ammonium and bicarbonate ions to urea. In contrast, the perivenous hepatocytes are capable of synthesizing glutamine. During metabolic acidosis, the kidney becomes the major site of glutamine extraction and catabolism. This process generates ammonium ions that are excreted in the urine to facilitate the excretion of acids and bicarbonate ions that are transported to the blood to partially compensate the acidosis. The increased renal extraction of glutamine is balanced by an increased release from muscle and liver and by a decreased utilization in the intestine. During chronic acidosis, this adaptation is sustained, in part, by increased renal expression of genes that encode various transport proteins and key enzymes of glutamine metabolism. The increased levels of phosphoenolpyruvate carboxykinase result from increased transcription, while the increase in glutaminase and glutamate dehydrogenase activities result from stabilization of their respective mRNAs. Where feasible, this review draws upon data obtained from studies in humans. Studies conducted in model animals are discussed where available data from humans is either lacking or not firmly established. Because there are quantitative differences in tissue utilization and synthesis of glutamine in different mammals, the review will focus more on common principles than on quantification. [source] Transcriptional Regulation of Caspases in Experimental Pneumococcal MeningitisBRAIN PATHOLOGY, Issue 3 2001Matthias von Mering Apoptosis and necrosis in brain account for neurological sequelae in survivors of bacterial meningitis. In meningitis, several mechanisms may trigger death pathways leading to activation of transcription factors regulating caspases mRNA synthesis. Therefore, we used a multiprobe RNA protection assay (RPA) to examine the expression of 9 caspase-mRNA in the course of experimental Streptococcus pneumoniae meningitis in mouse brain. Caspase-6, -7 and -11 mRNA were elevated 6 hours after infection. 12 hours after infection caspases-1, -2, -8 and -12 mRNA rose. Caspase-14 mRNA was elevated 18 h and caspase-3 mRNA 24 h after infection. In situ hybridization detected caspases-3, -8, -11 and -12 mRNA in neurons of the hippocampal formation and neocortex. Development of sepsis was paralleled by increased transcription of caspases mRNA in the spleen. In TNF,-deficient mice all caspases examined were less upregulated, in TNF-receptor 1/2 knockout mice caspases-1, -2, -7, -11 and -14 mRNA were increased compared to infected control animals. In caspase-1 deficient mice, caspases-11, and -12 mRNA levels did not rise in meningitis indicating the necessity of caspase-1 activating these caspases. Hippocampal formations of newborn mice incubated with heat-inactivated S. pneumoniae R6 showed upregulation of caspase-1, -3, -11 and -12 mRNA. These observations suggest a tightly regulated caspases network at the transcriptional level in addition to the known cascade at the protein level. [source] | |||||||||||||