scholarly journals Glucocorticoid hormones downregulate histidine decarboxylase mRNA and enzyme activity in rat lung

1998 ◽  
Vol 275 (2) ◽  
pp. L407-L413 ◽  
Author(s):  
Cynthia A. Zahnow ◽  
Pertti Panula ◽  
Atsushi Yamatodani ◽  
David E. Millhorn
Keyword(s):  
Gene Expression ◽  
Enzyme Activity ◽  
Adrenal Gland ◽  
Histidine Decarboxylase ◽  
Mrna Levels ◽  
Glucocorticoid Hormones ◽  
Rat Lung ◽  
Dexamethasone Treatment ◽  
Inflammatory Disorders ◽  
Corticosterone Treatment

Histidine decarboxylase (HDC) is the primary enzyme regulating histamine biosynthesis. Histamine contributes to the pathogenesis of chronic inflammatory disorders such as asthma. Because glucocorticoids are effective in the treatment of asthma, we examined the effects of 6 h of exogenously administered dexamethasone (0.5–3,000 μg/kg ip), corticosterone (0.2–200 mg/kg ip), or endogenously elevated corticosterone (via exposure of rats to 10% oxygen) on HDC expression in the rat lung. HDC transcripts were decreased ∼73% with dexamethasone treatment, 57% with corticosterone treatment, and 50% with exposure to 10% oxygen. Likewise, HDC enzyme activity was decreased 80% by treatment with dexamethasone and corticosterone and 60% by exposure to 10% oxygen. Adrenalectomy prevented the decreases in HDC mRNA and enzyme activity observed in rats exposed to 10% oxygen, suggesting that the adrenal gland is necessary for the mediation of hypoxic effects on HDC gene expression. These results demonstrate that corticosteroids initiate a process that leads to the decrease of HDC mRNA levels and enzyme activity in rat lung.

Hepatocellular expression of glucose-6-phosphatase is unaltered during hepatic regeneration

1998 ◽  
Vol 275 (4) ◽  
pp. G717-G722 ◽  
Author(s):  
Wisam F. Zakko ◽  
Carl L. Berg ◽  
John L. Gollan ◽  
Richard M. Green
Keyword(s):  
Gene Expression ◽  
Enzyme Activity ◽  
Protein Expression ◽  
Partial Hepatectomy ◽  
Initial Phase ◽  
Physiological Function ◽  
Liver Homogenate ◽  
Hepatic Regeneration ◽  
Mrna Levels ◽  
Microsomal Enzyme

Gluconeogenesis and glycogenolysis are essential hepatic functions required for glucose homeostasis. During the initial phase of hepatic regeneration, the immediate-early genes (IEG) are rapidly expressed, and the IEG RL-1 encodes for glucose-6-phosphatase (G-6- Pase). G-6- Pase is a microsomal enzyme essential for gluconeogenesis and glycogenolysis. This study employs a partial-hepatectomy model to examine the expression and activity of G-6- Pase. After partial hepatectomy, rat hepatic G-6- Pase gene expression is transcriptionally regulated, and mRNA levels are increased ≈30-fold. However, in contrast to this rapid gene induction, microsomal enzyme activity is unchanged after partial hepatectomy. Western blotting demonstrates that microsomal G-6- Pase protein expression is also unchanged after partial hepatectomy, and similar results are also noted in whole liver homogenate. Thus, despite marked induction in gene expression of the IEG G-6- Pase after partial hepatectomy, protein expression and enzyme activity remain unchanged. These data indicate that, although this hepatocyte IEG is transcriptionally regulated, the physiologically important level of regulation is posttranscriptional. This highlights the importance of correlating gene expression of IEG with protein expression and physiological function.

scholarly journals Maternal administration of dexamethasone stimulates choline-phosphate cytidylyltransferase in fetal type II cells

1987 ◽  
Vol 241 (1) ◽  
pp. 291-296 ◽  
Author(s):  
M Post
Keyword(s):  
Enzyme Activity ◽  
Specific Activity ◽  
Active Form ◽  
Type Ii Cells ◽  
Type Ii ◽  
Rat Lung ◽  
Dexamethasone Treatment ◽  
Fetal Rat ◽  
Fetal Rat Lung ◽  
Choline Phosphate

Administration of dexamethasone to pregnant rats at 19 days gestation increased phosphatidylcholine synthesis (45%) from radioactive choline in type II cells. This enhanced synthesis of phosphatidylcholine was accompanied by an increased conversion of choline phosphate into CDP-choline. Similar results were obtained by incubating organotypic cultures of 19-day-fetal rat lung with cortisol. The increased conversion of choline phosphate into CDP-choline correlated with an enhanced choline-phosphate cytidylyltransferase activity (31% after dexamethasone treatment; 47% after cortisol exposure) in the cell homogenates. A similar increase (26% after dexamethasone treatment; 39% after cortisol exposure) was found in the microsomal-associated enzyme. No differences in cytosolic enzyme activity were observed. The specific activity of the microsomal enzyme was 3-4 times that of the cytosolic enzyme. Most of the enzyme activity was located in the microsomal fraction (58-65%). The treatments had no effect on the total amount of enzyme recovered from the cell homogenates. These results, taken collectively, are interpreted to indicate that the active form of cytidylyltransferase in type II cells is the membrane-bound enzyme and that cytidylyltransferase activation in type II cells from fetal rat lung after maternal glucocorticoid administration occurs by binding of inactive cytosolic enzyme to endoplasmic reticulum.

Dexamethasone stimulates transcription of the Na+-K+-ATPase β1gene in adult rat lung epithelial cells

2003 ◽  
Vol 285 (3) ◽  
pp. L593-L601 ◽  
Author(s):  
Hong Hao ◽  
Christine H. Wendt ◽  
Gurpreet Sandhu ◽  
David H. Ingbar
Keyword(s):  
Gene Expression ◽  
Epithelial Cells ◽  
Regulatory Elements ◽  
Lung Epithelial Cells ◽  
Mrna Levels ◽  
Rat Lung ◽  
Alveolar Epithelial ◽  
Adult Rat ◽  
Atpase Gene ◽  
Lung Epithelial

Na+-K+-ATPase plays an essential role in active alveolar epithelial fluid resorption. In fetal and adult alveolar epithelial cells, glucocorticoids (GC) increase Na+-K+-ATPase activity and mRNA levels. We sought to define the mechanism of Na+-K+-ATPase gene upregulation by GC. In a rat alveolar epithelial cell line (RLE), dexamethasone (Dex) increased β1-subunit Na+-K+-ATPase mRNA expression two- to threefold within 3 h after exposure to the GC. The increased gene expression was due to increased transcription as demonstrated by nuclear run-on assays, whereas mRNA stability remained unchanged. Transient transfection of 5′ deletion mutants of a β1promoter-reporter construct demonstrated a 1.5- to 2.2-fold increase in promoter activity by Dex. All of the 5′ deletion constructs contained partial or palindromic GC regulatory elements (GRE) and responded to GC. The increased expression of promoter reporter was inhibited by RU-486, a GC receptor (GR) antagonist, suggesting the involvement of GR. The palindromic GRE at -631 demonstrated Dex induction in a heterologous promoter construct. Gel mobility shift assays using RLE nuclear extracts demonstrated specific binding to this site and the presence of GR. We conclude that GC directly stimulate transcription of Na+-K+-ATPase β1gene expression in adult rat lung epithelial cells through a GR-dependent mechanism that can act at multiple sites.

Hypoxia downregulates tropoelastin gene expression in rat lung fibroblasts by pretranslational mechanisms

1999 ◽  
Vol 277 (3) ◽  
pp. L566-L572 ◽  
Author(s):  
John L. Berk ◽  
Nima Massoomi ◽  
Christine Hatch ◽  
Ronald H. Goldstein
Keyword(s):  
Gene Expression ◽  
Gene Transcription ◽  
Actinomycin D ◽  
Lung Fibroblasts ◽  
Mrna Levels ◽  
Rat Lung ◽  
Cell Toxicity ◽  
Chromium Release ◽  
Injured Lung ◽  
Isolated Rat Lung

Elastolytic lung injury disrupts cell barriers, flooding alveoli and producing regional hypoxia. Abnormal O2 tensions may alter repair of damaged elastin fibers. To determine the effect of hypoxia on extravascular elastin formation, we isolated rat lung fibroblasts and cultured them under a variety of O2 conditions. Hypoxia downregulated tropoelastin mRNA in a dose- and time-related fashion while upregulating glyceraldehyde-3-phosphate dehydrogenase mRNA levels. The changes in tropoelastin gene expression were not due to cell toxicity as measured by chromium release and cell proliferation studies. Neither cycloheximide nor actinomycin D abrogated this effect. Hypoxia induced early decreases in tropoelastin mRNA stability; minor suppression of gene transcription occurred later. When returned to 21% O2, tropoelastin mRNA recovered to control levels in part by upregulating tropoelastin gene transcription. Taken together, these data indicate that hypoxia regulates tropoelastin gene expression and may alter repair of acutely injured lung.

scholarly journals Mitotane induces CYP3A4 expression via activation of the steroid and xenobiotic receptor

2012 ◽  
Vol 216 (3) ◽  
pp. 297-305 ◽  
Author(s):  
Akira Takeshita ◽  
Junko Igarashi-Migitaka ◽  
Noriyuki Koibuchi ◽  
Yasuhiro Takeuchi
Keyword(s):  
Gene Expression ◽  
Enzyme Activity ◽  
Drug Interactions ◽  
Luciferase Reporter ◽  
Pcr Analysis ◽  
Metabolic Clearance ◽  
Mrna Levels ◽  
Steroid And Xenobiotic Receptor ◽  
Cyp3a4 Enzyme ◽  
Xenobiotic Receptor

Adrenocortical carcinoma (ACC) is a rare disease with an extremely poor prognosis. Mitotane alone or in combination with other cytotoxic drugs is a common therapeutic option for ACC. In addition to its adrenolytic function, mitotane has been known for decades to increase the metabolic clearance of glucocorticoids. It was recently shown that the tyrosine kinase inhibitor sunitinib is also rapidly metabolized in patients treated with mitotane, indicating that mitotane engages in clinically relevant drug interactions. Although the precise mechanism of these interactions is not well understood, cytochrome P450 mono-oxygenase 3A4 (CYP3A4) is a key enzyme to inactivate both glucocorticoids and sunitinib. The nuclear receptor steroid and xenobiotic receptor (SXR (NR1I2)) is one of the key transcriptional regulators ofCYP3A4gene expression in the liver and intestine. A variety of xenobiotics bind to SXR and stimulate transcription of xenobiotic-response elements (XREs) located in theCYP3A4gene promoter. In this study, we evaluated the effects of mitotane on SXR-mediated transcriptionin vitroby luciferase reporter analysis, SXR–steroid receptor coactivator 1 (SRC1) interactions, quantitative real-time PCR analysis ofCYP3A4expression, SXR knockdown, and CYP3A4 enzyme activity assays using human hepatocyte-derived cells. We found that mitotane activated SXR-mediated transcription of the XREs. Mitotane recruited SRC1 to the ligand-binding domain of SXR. Mitotane increasedCYP3A4mRNA levels, which was attenuated by SXR knockdown. Finally, we showed that mitotane increased CYP3A4 enzyme activity. We conclude that mitotane can induceCYP3A4gene expression and suggest that mitotane is used cautiously due to its drug–drug interactions.

Glutamine synthetase gene expression in the lungs of endotoxin-treated and adrenalectomized rats

1997 ◽  
Vol 273 (6) ◽  
pp. L1182-L1190 ◽  
Author(s):  
Gregory Lukaszewicz ◽  
Steve F. Abcouwer ◽  
Brian I. Labow ◽  
Wiley W. Souba
Keyword(s):  
Glutamine Synthetase ◽  
Gene Induction ◽  
High Dose ◽  
Mrna Levels ◽  
Glucocorticoid Hormones ◽  
Rat Lung ◽  
Pulmonary Endothelial Cells ◽  
Intraperitoneal Dose ◽  
Gs Protein ◽  
Adrenalectomized Rats

During sepsis, the lung responds by exporting increased amounts of the amino acid glutamine. This response is accompanied by increased enzymatic activity of glutamine synthetase (GS), which catalyzes the synthesis of glutamine from glutamate and ammonia. It is also known that GS expression in the rat lung can be induced by glucocorticoid hormones. To determine whether the septic response and the response to glucocorticoids are related, we have characterized the induction of GS expression during lipopolysaccharide (LPS)-induced endotoxemia in normal, neutropenic, and adrenalectomized rats. Normal rats exhibited a time- and dose-dependent induction of GS mRNA levels after a single intraperitoneal dose of LPS. Responses to LPS were maximal at doses of 0.1 mg/kg body wt and above. A single 10 mg/kg body wt dose of LPS led to a rapid, transient sevenfold increase in GS mRNA ( P ≤ 0.1) and a twofold increase in GS protein level 8 h postinjection. Induction of lung GS mRNA 4 h after LPS injection was approximately fivefold in neutropenic ( P ≤ 0.1) and fourfold in nonneutropenic control rats ( P ≤ 0.1), suggesting that infiltrating neutrophils or neutrophil-derived factors are not required for GS induction. In response to high-dose, short-term endotoxemia, adrenalectomized rat lung GS mRNA increased twofold ( P ≤ 0.02) compared with sixfold in sham-operated control rats ( P ≤ 0.02). However, in response to low-dose, long-term endotoxemia, adrenalectomized rat lung GS mRNA increased threefold ( P ≤ 0.02) compared with fourfold in sham-operated control rats ( P ≤ 0.02). Adrenalectomy did not affect the elevation of lung GS mRNA levels in response to dexamethasone. In addition, GS mRNA was induced four- and sixfold in rat microvascular pulmonary endothelial cells exposed to plasma from control and septic rats, respectively. The addition of a glucocorticoid antagonist, RU-38486, completely blocked GS gene induction in the presence of control plasma but only attenuated the response to plasma from septic animals by 30%. These results suggest that GS gene induction during sepsis is only partially mediated by adrenal-derived glucocorticoid hormones.

Perinatal rat lung catalase gene expression: influence of corticosteroid and hyperoxia

1991 ◽  
Vol 260 (6) ◽  
pp. L428-L433 ◽  
Author(s):  
L. B. Clerch ◽  
J. Iqbal ◽  
D. Massaro
Keyword(s):  
Gene Expression ◽  
Gene Transcription ◽  
Mrna Stability ◽  
Catalase Activity ◽  
Half Life ◽  
Rat Lung ◽  
Dexamethasone Treatment ◽  
Catalase Gene ◽  
Mrna Concentration ◽  
Neonatal Hyperoxia

Dexamethasone accelerates the late gestational rise in rat lung catalase activity; neonatal hyperoxia elevates rat lung catalase activity. We studied the regulation of catalase gene expression in these instances. Catalase mRNA/mg DNA increased to gestation day 22 and then fell to the concentration in adult lungs. The rate of transcription of catalase mRNA was higher on gestation day 22 than gestation day 19, whereas the half-life of catalase mRNA (approximately 7 h) was the same on both days. Dexamethasone given 48 and 24 h before expected birth (gestation 22 days) increased catalase mRNA concentration at days 20 and 22 without a change in catalase mRNA stability. Early postnatal hyperoxia (greater than 95% O2, 72 h) elevated catalase mRNA/mg DNA and doubled its half-life without changing its rate of transcription. We conclude the normal late gestational elevation of catalase activity and the increase of activity during prenatal dexamethasone treatment are regulated at the level of gene transcription. By contrast, the elevation of catalase activity during neonatal hyperoxia is mediated posttranscriptionally by increased catalase mRNA stability.

Effect of blockade of mGluR5 on stress hormone release and its gene expression in the adrenal gland

2014 ◽  
Vol 92 (8) ◽  
pp. 686-692 ◽  
Author(s):  
Michal Pokusa ◽  
Barbora Prokopova ◽  
Natasa Hlavacova ◽  
Aikaterini Makatsori ◽  
Daniela Jezova
Keyword(s):  
Gene Expression ◽  
Adrenal Gland ◽  
Metabotropic Glutamate Receptor ◽  
Glutamate Release ◽  
Catecholamine Release ◽  
Male Rats ◽  
Receptor Subtype ◽  
Mrna Levels ◽  
Hormone Release ◽  
Different Strains

The aim of this study was to verify the presence of metabotropic glutamate receptor subtype 5 (mGluR5) in the adrenal gland of male rats of 2 different strains, and to test the hypothesis that treatment with mGluR5 antagonist 2-methyl-6-(phenylethynyl)-pyridine (MPEP) affects hormone release and adrenal gene expression of mGluR5 under conditions of stress. The results clearly show the gene expression of mGluR5 in the adrenal gland in both the adrenal cortex and medulla. Treatment with the glutamate release inhibitor riluzole (4 mg·(kg body mass)–1·day–1 for 2 weeks) failed to modify mRNA levels of either the mGluR5 or NR1 subunit of the NMDA receptor in the adrenal glands, as measured by real-time PCR. Blockade of mGluR5 with MPEP (1 mg·kg–1 for 4 days) increased corticosterone but not catecholamine release during restraint stress (20 min). Treatment with MPEP had no effect on mRNA levels coding for steroidogenic factors StAR and SF-1, and decreased mGluR5 gene expression in the adrenal gland. In conclusion, mGluR5 is not likely to play a significant role in stress-induced catecholamine release. Pharmacological blockade of mGluR5 has a modest influence on the hypothalamic–pituitary–adrenocortical axis, as reflected in adrenal hypertrophy and increased corticosterone concentrations.

scholarly journals Gene expression of mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase in a poorly ketogenic mammal: effect of starvation during the neonatal period of the piglet

1997 ◽  
Vol 324 (1) ◽  
pp. 65-73 ◽  
Author(s):  
Sean H. ADAMS ◽  
Clarice S. ALHO ◽  
Guillermina ASINS ◽  
Fausto G. HEGARDT ◽  
Pedro F. MARRERO
Keyword(s):  
Gene Expression ◽  
Enzyme Activity ◽  
Small Intestine ◽  
Neonatal Period ◽  
Specific Activity ◽  
Mrna Levels ◽  
Specific Expression ◽  
Order Of Magnitude ◽  
Specific Expression Pattern ◽  
Low Activity

The low ketogenic capacity of pigs correlates with a low activity of mitochondrial 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) synthase. To identify the molecular mechanism controlling such activity, we isolated the pig cDNA encoding this enzyme and analysed changes in mRNA levels and mitochondrial specific activity induced during development and starvation. Pig mitochondrial synthase showed a tissue-specific expression pattern. As with rat and human, the gene is expressed in liver and large intestine; however, the pig differs in that mRNA was not detected in testis, kidney or small intestine. During development, pig mitochondrial HMG-CoA synthase gene expression showed interesting differences from that in the rat: (1) there was a 2–3 week lag in the postnatal induction; (2) the mRNA levels remained relatively abundant through the suckling–weaning transition and at maturity, in contrast with the fall observed in rats at similar stages of development; and (3) the gene expression was highly induced by fasting during the suckling, whereas no such change in mitochondrial HMG-CoA synthase mRNA levels has been observed in rat. The enzyme activity of mitochondrial HMG-CoA synthase increased 27-fold during starvation in piglets, but remained one order of magnitude lower than rats. These results indicate that post-transcriptional mechanism(s) and/or intrinsic differences in the encoded enzyme are responsible for the low activity of pig HMG-CoA synthase observed throughout development or after fasting.

Developmental regulation of preproenkephalin (PENK) gene expression in the adrenal gland of the ovine fetus and newborn lamb: effects of hypoxemia and exogenous cortisol infusion

1997 ◽  
Vol 155 (1) ◽  
pp. 143-149 ◽  
Author(s):  
M Fraser ◽  
SG Matthews ◽  
G Braems ◽  
T Jeffray ◽  
Keyword(s):  
Gene Expression ◽  
Adrenal Gland ◽  
Plasma Cortisol ◽  
Late Gestation ◽  
Mrna Levels ◽  
Fetal Sheep ◽  
Adult Sheep ◽  
Organ Systems ◽  
Response To Stress ◽  
In Pregnancy

Development of the fetal adrenal gland is crucial not only for maturation of several fetal organ systems and the initiation of parturition, but also for the development of the fetal response to stress. The enkephalin-related peptides are present in the chromaffin cells of the fetal adrenal medulla and are secreted in response to stress and with sympathetic stimulation. However, changes in expression of preproenkephalin (PENK) with gestation and in response to stress have not been studied in detail. Therefore we examined the developmental pattern of PENK gene expression in the adrenal gland of fetal and newborn lambs, and of adult sheep. We also determined whether levels of PENK mRNA in the fetal adrenal gland changed in response to exogenous glucocorticoids in late gestation, or in response to hypoxemia. Adrenal glands were removed from fetal sheep, lambs and adult sheep at different stages of development for measurement of PENK mRNA. Cortisol was infused (5 micrograms/min) for 12, 24 or 96 h beginning on day 124-129 of gestation. Moderate hypoxemia was induced for 48 h beginning on day 126-130, or at day 134-136 of gestation, by lowering the maternal fractional inspired oxygen. At the end of the treatment periods, the ewes and fetuses were euthanized. Adrenal PENK mRNA were measured by Northern blot analysis. PENK mRNA levels in fetal adrenals were significantly higher (P < 0.05) on days 140-141 of gestation than earlier in pregnancy, and then decreased significantly with the onset of parturition (days 142-146). After cortisol infusion to the fetus for 96 h there was a significant reduction in adrenal PENK mRNA levels. Hypoxemia resulted in a significant increase in PENK mRNA levels in fetuses at day 126-130 of gestation, but not at the later time in pregnancy when endogenous plasma cortisol concentrations were higher. We conclude that there is a decrease in levels of PENK mRNA in the fetal adrenal gland before parturition at the time of the endogenous prepartum rise in plasma cortisol. Hypoxemia led to an elevation of PENK mRNA levels in fetuses at less than 130 days, but after that time, when the basal and stimulated cortisol responses had risen, there was no significant effect of hypoxemia on PENK mRNA. Cortisol infusion to the fetus at this stage of pregnancy resulted in a decrease in adrenal PENK mRNA levels. We suggest that cortisol may play an important role in the regulation of fetal adrenal PENK mRNA levels and enkephalin synthesis by the adrenal gland of the fetal sheep.

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