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Activation of SIK1 by phanginin A inhibits hepatic gluconeogenesis by increasing PDE4 activity and suppressing the cAMP signaling pathway. Mol Metab 2020; 41:101045. [PMID: 32599076 PMCID: PMC7381706 DOI: 10.1016/j.molmet.2020.101045] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 06/06/2020] [Accepted: 06/22/2020] [Indexed: 12/25/2022] Open
Abstract
Objective Salt-induced kinase 1 (SIK1) acts as a key modulator in many physiological processes. However, the effects of SIK1 on gluconeogenesis and the underlying mechanisms have not been fully elucidated. In this study, we found that a natural compound phanginin A could activate SIK1 and further inhibit gluconeogenesis. The mechanisms by which phanginin A activates SIK1 and inhibits gluconeogenesis were explored in primary mouse hepatocytes, and the effects of phanginin A on glucose homeostasis were investigated in ob/ob mice. Methods The effects of phanginin A on gluconeogenesis and SIK1 phosphorylation were examined in primary mouse hepatocytes. Pan-SIK inhibitor and siRNA-mediated knockdown were used to elucidate the involvement of SIK1 activation in phanginin A-reduced gluconeogenesis. LKB1 knockdown was used to explore how phanginin A activated SIK1. SIK1 overexpression was used to evaluate its effect on gluconeogenesis, PDE4 activity, and the cAMP pathway. The acute and chronic effects of phanginin A on metabolic abnormalities were observed in ob/ob mice. Results Phanginin A significantly increased SIK1 phosphorylation through LKB1 and further suppressed gluconeogenesis by increasing PDE4 activity and inhibiting the cAMP/PKA/CREB pathway in primary mouse hepatocytes, and this effect was blocked by pan-SIK inhibitor HG-9-91-01 or siRNA-mediated knockdown of SIK1. Overexpression of SIK1 in hepatocytes increased PDE4 activity, reduced cAMP accumulation, and thereby inhibited gluconeogenesis. Acute treatment with phanginin A reduced gluconeogenesis in vivo, accompanied by increased SIK1 phosphorylation and PDE4 activity in the liver. Long-term treatment of phanginin A profoundly reduced blood glucose levels and improved glucose tolerance and dyslipidemia in ob/ob mice. Conclusion We discovered an unrecognized effect of phanginin A in suppressing hepatic gluconeogenesis and revealed a novel mechanism that activation of SIK1 by phanginin A could inhibit gluconeogenesis by increasing PDE4 activity and suppressing the cAMP/PKA/CREB pathway in the liver. We also highlighted the potential value of phanginin A as a lead compound for treating type 2 diabetes. Phanginin A inhibits gluconeogenesis in primary mouse hepatocytes. Phanginin A increases hepatic SIK1 phosphorylation both in vitro and in vivo. Activation of SIK1 increases PDE4 activity and suppresses the cAMP signaling pathway. Activation of SIK1 inhibits gluconeogenesis by regulating the PDE4/cAMP/PKA/CREB pathway. Phanginin A improves metabolic disorders in ob/ob mice.
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Johanns M, Lai YC, Hsu MF, Jacobs R, Vertommen D, Van Sande J, Dumont JE, Woods A, Carling D, Hue L, Viollet B, Foretz M, Rider MH. AMPK antagonizes hepatic glucagon-stimulated cyclic AMP signalling via phosphorylation-induced activation of cyclic nucleotide phosphodiesterase 4B. Nat Commun 2016; 7:10856. [PMID: 26952277 PMCID: PMC4786776 DOI: 10.1038/ncomms10856] [Citation(s) in RCA: 102] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 01/27/2016] [Indexed: 11/14/2022] Open
Abstract
Biguanides such as metformin have previously been shown to antagonize hepatic glucagon-stimulated cyclic AMP (cAMP) signalling independently of AMP-activated protein kinase (AMPK) via direct inhibition of adenylate cyclase by AMP. Here we show that incubation of hepatocytes with the small-molecule AMPK activator 991 decreases glucagon-stimulated cAMP accumulation, cAMP-dependent protein kinase (PKA) activity and downstream PKA target phosphorylation. Moreover, incubation of hepatocytes with 991 increases the Vmax of cyclic nucleotide phosphodiesterase 4B (PDE4B) without affecting intracellular adenine nucleotide concentrations. The effects of 991 to decrease glucagon-stimulated cAMP concentrations and activate PDE4B are lost in hepatocytes deleted for both catalytic subunits of AMPK. PDE4B is phosphorylated by AMPK at three sites, and by site-directed mutagenesis, Ser304 phosphorylation is important for activation. In conclusion, we provide a new mechanism by which AMPK antagonizes hepatic glucagon signalling via phosphorylation-induced PDE4B activation. The diabetes drug Metformin decreases hepatic glucose production and activates AMP-activated protein kinase (AMPK). Here the authors provide evidence that AMPK activation antagonizes glucagon signalling by activating PDE4B, lowering cAMP levels and decreasing PKA activation.
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Affiliation(s)
- M Johanns
- Université catholique de Louvain and de Duve Institute, Avenue Hippocrate, 75, 1200 Brussels, Belgium
| | - Y-C Lai
- Université catholique de Louvain and de Duve Institute, Avenue Hippocrate, 75, 1200 Brussels, Belgium
| | - M-F Hsu
- Université catholique de Louvain and de Duve Institute, Avenue Hippocrate, 75, 1200 Brussels, Belgium
| | - R Jacobs
- Université catholique de Louvain and de Duve Institute, Avenue Hippocrate, 75, 1200 Brussels, Belgium
| | - D Vertommen
- Université catholique de Louvain and de Duve Institute, Avenue Hippocrate, 75, 1200 Brussels, Belgium
| | - J Van Sande
- Faculté de Médecine, Institut de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire (IRIBHM), Université Libre de Bruxelles (ULB), Route de Lennik, 808, 1070 Brussels, Belgium
| | - J E Dumont
- Faculté de Médecine, Institut de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire (IRIBHM), Université Libre de Bruxelles (ULB), Route de Lennik, 808, 1070 Brussels, Belgium
| | - A Woods
- Cellular Stress Group, MRC Clinical Sciences Centre, Imperial College London, Hammersmith Hospital, DuCane Road, London W12 0NN, UK
| | - D Carling
- Cellular Stress Group, MRC Clinical Sciences Centre, Imperial College London, Hammersmith Hospital, DuCane Road, London W12 0NN, UK
| | - L Hue
- Université catholique de Louvain and de Duve Institute, Avenue Hippocrate, 75, 1200 Brussels, Belgium
| | - B Viollet
- INSERM U1016, Institut Cochin, 75014 Paris, France.,CNRS UMR8104, 75014 Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, 75014 Paris, France
| | - M Foretz
- INSERM U1016, Institut Cochin, 75014 Paris, France.,CNRS UMR8104, 75014 Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, 75014 Paris, France
| | - M H Rider
- Université catholique de Louvain and de Duve Institute, Avenue Hippocrate, 75, 1200 Brussels, Belgium
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Wollborn J, Wunder C, Stix J, Neuhaus W, Bruno RR, Baar W, Flemming S, Roewer N, Schlegel N, Schick MA. Phosphodiesterase-4 inhibition with rolipram attenuates hepatocellular injury in hyperinflammation in vivo and in vitro without influencing inflammation and HO-1 expression. J Pharmacol Pharmacother 2015; 6:13-23. [PMID: 25709347 PMCID: PMC4319242 DOI: 10.4103/0976-500x.149138] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Revised: 07/09/2014] [Accepted: 11/17/2014] [Indexed: 02/07/2023] Open
Abstract
Objective: To investigate the impact of the phophodiesterase-4 inhibition (PD-4-I) with rolipram on hepatic integrity in lipopolysaccharide (LPS) induced hyperinflammation. Materials and Methods: Liver microcirculation in rats was obtained using intravital microscopy. Macrohemodynamic parameters, blood assays, and organs were harvested to determine organ function and injury. Hyperinflammation was induced by LPS and PD-4-I rolipram was administered intravenously one hour after LPS application. Cell viability of HepG2 cells was measured by EZ4U-kit based on the dye XTT. Experiments were carried out assessing the influence of different concentrations of tumor necrosis factor alpha (TNF-α) and LPS with or without PD-4-I. Results: Untreated LPS-induced rats showed significantly decreased liver microcirculation and increased hepatic cell death, whereas LPS + PD-4-I treatment could improve hepatic volumetric flow and cell death to control level whithout influencing the inflammatory impact. In HepG2 cells TNF-α and LPS significantly reduced cell viability. Coincubation with PD-4-I increased HepG2 viability to control levels. The heme oxygenase 1 (HO-1) pathway did not induce the protective effect of PD-4-I. Conclusion: Intravenous PD-4-I treatment was effective in improving hepatic microcirculation and hepatic integrity, while it had a direct protective effect on HepG2 viability during inflammation.
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Affiliation(s)
- Jakob Wollborn
- Department of Anaesthesia and Critical Care, University Hospital Würzburg, Germany
| | - Christian Wunder
- Department of Anaesthesia and Critical Care, University Hospital Würzburg, Germany
| | - Jana Stix
- Department of Pathology, Klinikum Nürnberg, Nürnberg, Germany
| | - Winfried Neuhaus
- Department of Anaesthesia and Critical Care, University Hospital Würzburg, Germany ; Department of Medicinal Chemistry, University of Vienna, Vienna, Austria
| | - Rapahel R Bruno
- Department of Anaesthesia and Critical Care, University Hospital Würzburg, Germany
| | - Wolfgang Baar
- Department of Anaesthesia and Critical Care, University Hospital Würzburg, Germany ; Department of Anesthesiology and Critical Care Medicine, University Medical Center, Freiburg, Germany
| | - Sven Flemming
- Department of General, Visceral, Vascular, and Paediatric Surgery (Department of Surgery I), University of Würzburg, Würzburg, Germany
| | - Norbert Roewer
- Department of Anaesthesia and Critical Care, University Hospital Würzburg, Germany
| | - Nicolas Schlegel
- Department of General, Visceral, Vascular, and Paediatric Surgery (Department of Surgery I), University of Würzburg, Würzburg, Germany
| | - Martin A Schick
- Department of Anaesthesia and Critical Care, University Hospital Würzburg, Germany
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Strahm E, Rane A, Ekström L. PDE7B is involved in nandrolone decanoate hydrolysis in liver cytosol and its transcription is up-regulated by androgens in HepG2. Front Pharmacol 2014; 5:132. [PMID: 24910615 PMCID: PMC4038775 DOI: 10.3389/fphar.2014.00132] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Accepted: 05/14/2014] [Indexed: 11/29/2022] Open
Abstract
Most androgenic drugs are available as esters for a prolonged depot action. However, the enzymes involved in the hydrolysis of the esters have not been identified. There is one study indicating that PDE7B may be involved in the activation of testosterone enanthate. The aims are to identify the cellular compartments where the hydrolysis of testosterone enanthate and nandrolone decanoate occurs, and to investigate the involvement of PDE7B in the activation. We also determined if testosterone and nandrolone affect the expression of the PDE7B gene. The hydrolysis studies were performed in isolated human liver cytosolic and microsomal preparations with and without specific PDE7B inhibitor. The gene expression was studied in human hepatoma cells (HepG2) exposed to testosterone and nandrolone. We show that PDE7B serves as a catalyst of the hydrolysis of testosterone enanthate and nandrolone decanoate in liver cytosol. The gene expression of PDE7B was significantly induced 3- and 5- fold after 2 h exposure to 1 μM testosterone enanthate and nandrolone decanoate, respectively. These results show that PDE7B is involved in the activation of esterified nandrolone and testosterone and that the gene expression of PDE7B is induced by supra-physiological concentrations of androgenic drugs.
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Affiliation(s)
- Emmanuel Strahm
- Division of Clinical Pharmaclogy, Department of Laboratory Medicine, Karolinska Institutet, Karolinska University Hospital Stockholm, Sweden
| | - Anders Rane
- Division of Clinical Pharmaclogy, Department of Laboratory Medicine, Karolinska Institutet, Karolinska University Hospital Stockholm, Sweden
| | - Lena Ekström
- Division of Clinical Pharmaclogy, Department of Laboratory Medicine, Karolinska Institutet, Karolinska University Hospital Stockholm, Sweden
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Perez M, Lakshminrusimha S, Wedgwood S, Czech L, Gugino SF, Russell JA, Farrow KN, Steinhorn RH. Hydrocortisone normalizes oxygenation and cGMP regulation in lambs with persistent pulmonary hypertension of the newborn. Am J Physiol Lung Cell Mol Physiol 2011; 302:L595-603. [PMID: 22198909 DOI: 10.1152/ajplung.00145.2011] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
In the pulmonary vasculature, cGMP levels are regulated by soluble guanylate cyclase (sGC) and phosphodiesterase 5 (PDE5). We previously reported that lambs with persistent pulmonary hypertension of the newborn (PPHN) demonstrate increased reactive oxygen species (ROS) and altered sGC and PDE5 activity, with resultant decreased cGMP. The objective of this study was to evaluate the effects of hydrocortisone on pulmonary vascular function, ROS, and cGMP in the ovine ductal ligation model of PPHN. PPHN lambs were ventilated with 100% O(2) for 24 h. Six lambs received 5 mg/kg hydrocortisone every 8 h times three doses (PPHN-hiHC), five lambs received 3 mg/kg hydrocortisone followed by 1 mg·kg(-1)·dose(-1) times two doses (PPHN-loHC), and six lambs were ventilated with O(2) alone (PPHN). All groups were compared with healthy 1-day spontaneously breathing lambs (1DSB). O(2) ventilation of PPHN lambs decreased sGC activity, increased PDE5 activity, and increased ROS vs. 1DSB lambs. Both hydrocortisone doses significantly improved arterial-to-alveolar ratios relative to PPHN lambs, decreased PDE5 activity, and increased cGMP relative to PPHN lambs. High-dose hydrocortisone also increased sGC activity, decreased PDE5 expression, decreased ROS, and increased total vascular SOD activity vs. PPHN lambs. These data suggest that hydrocortisone treatment in clinically relevant doses improves oxygenation and decreases hyperoxia-induced changes in sGC and PDE5 activity, increasing cGMP levels. Hydrocortisone reduces ROS levels in part by increasing SOD activity in PPHN lambs ventilated with 100% O(2.) We speculate that hydrocortisone increases cGMP by direct effects on sGC and PDE5 expression and by attenuating abnormalities induced by oxidant stress.
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Affiliation(s)
- Marta Perez
- Northwestern University, Chicago, Illinois, USA.
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6
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Lu Y, Zhang G, Shen C, Uygun K, Yarmush ML, Meng Q. A novel 3D liver organoid system for elucidation of hepatic glucose metabolism. Biotechnol Bioeng 2011; 109:595-604. [PMID: 22006574 DOI: 10.1002/bit.23349] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Revised: 09/26/2011] [Accepted: 09/29/2011] [Indexed: 12/12/2022]
Abstract
Hepatic glucose metabolism is a key player in diseases such as obesity and diabetes as well as in antihyperglycemic drugs screening. Hepatocytes culture in two-dimensional configurations is limited in vitro model for hepatocytes to function properly, while truly practical platforms to perform three-dimensional (3D) culture are unavailable. In this work, we present a practical organoid culture method of hepatocytes for elucidation of glucose metabolism under nominal and stress conditions. Employing this new method of culturing cells within a hollow fiber reactor, hepatocytes were observed to self-assemble into 3D spherical organoids with preservation of tight junctions and display increased liver-specific functions. Compared to both monolayer culture and sandwich culture, the hepatocyte organoids displayed higher intracellular glycogen content, glucose consumption, and gluconeogenesis and approached the in vivo values, as also confirmed by gene expression of key enzymes. Moreover, hepatocyte organoids demonstrated more realistic sensitivity to hormonal challenges with insulin, glucagon, and dexamethasone. Finally, the exposure to high glucose demonstrated toxicities including alteration of mitochondrial membrane potential, lipid accumulation, and reactive oxygen species formation, similar to the in vivo responses, which was not captured by monolayer cultures. Collectively, hepatocyte organoids mimicked the in vivo functions better than hepatocyte monolayer and sandwich cultures, suggesting suitability for applications such as antihyperglycemic drugs screening.
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Affiliation(s)
- Yanhua Lu
- Department of Chemical and Biological Engineering, Zhejiang University, 38 Zheda Road, Hangzhou, Zhejiang 310027, China
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7
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Peiró AM, Tang CM, Murray F, Zhang L, Brown LM, Chou D, Rassenti L, Kipps TJ, Kipps TA, Insel PA. Genetic variation in phosphodiesterase (PDE) 7B in chronic lymphocytic leukemia: overview of genetic variants of cyclic nucleotide PDEs in human disease. J Hum Genet 2011; 56:676-81. [PMID: 21796143 DOI: 10.1038/jhg.2011.80] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Expression of cyclic adenosine monophosphate-specific phosphodiesterase 7B (PDE7B) mRNA is increased in patients with chronic lymphocytic leukemia (CLL), thus suggesting that variation may occur in the PDE7B gene in CLL. As genetic variation in other PDE family members has been shown to associate with numerous clinical disorders (reviewed in this manuscript), we sought to identify single-nucleotide polymorphisms (SNPs) in the PDE7B gene promoter and coding region of 93 control subjects and 154 CLL patients. We found that the PDE7B gene has a 5' non-coding region SNP -347C>T that occurs with similar frequency in CLL patients (1.9%) and controls (2.7%). Tested in vitro, -347C>T has less promoter activity than a wild-type construct. The low frequency of this 5' untranslated region variant indicates that it does not explain the higher PDE7B expression in patients with CLL but it has the potential to influence other settings that involve a role for PDE7B.
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Affiliation(s)
- Ana M Peiró
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093-0636, USA
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8
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Hampson LJ, Agius L. Acetylcholine exerts additive and permissive but not synergistic effects with insulin on glycogen synthesis in hepatocytes. FEBS Lett 2007; 581:3955-60. [PMID: 17662981 DOI: 10.1016/j.febslet.2007.07.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2007] [Revised: 07/03/2007] [Accepted: 07/12/2007] [Indexed: 12/12/2022]
Abstract
Parasympathetic (cholinergic) innervation is implicated in the stimulation of hepatic glucose uptake by portal vein hyperglycaemia. We determined the direct effects of acetylcholine on hepatocytes. Acute exposure to acetylcholine mimicked insulin action on inactivation of phosphorylase, stimulation of glycogen synthesis and suppression of phosphoenolpyruvate carboxykinase mRNA levels but with lower efficacy and without synergy. Pre-exposure to acetylcholine had a permissive effect on insulin action similar to glucocorticoids and associated with increased glucokinase activity. It is concluded that acetylcholine has a permissive effect on insulin action but cannot fully account for the rapid stimulation of glucose uptake by the portal signal.
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Affiliation(s)
- Laura J Hampson
- Institute of Cellular Medicine, Division of Diabetes, Newcastle University, The Medical School, Newcastle upon Tyne NE2 4HH, UK
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9
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Lerner A, Epstein P. Cyclic nucleotide phosphodiesterases as targets for treatment of haematological malignancies. Biochem J 2006; 393:21-41. [PMID: 16336197 PMCID: PMC1383661 DOI: 10.1042/bj20051368] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The cAMP signalling pathway has emerged as a key regulator of haematopoietic cell proliferation, differentiation and apoptosis. In parallel, general understanding of the biology of cyclic nucleotide PDEs (phosphodiesterases) has advanced considerably, revealing the remarkable complexity of this enzyme system that regulates the amplitude, kinetics and location of intracellular cAMP-mediated signalling. The development of therapeutic inhibitors of specific PDE gene families has resulted in a growing appreciation of the potential therapeutic application of PDE inhibitors to the treatment of immune-mediated illnesses and haematopoietic malignancies. This review summarizes the expression and function of PDEs in normal haematopoietic cells and the evidence that family-specific inhibitors will be therapeutically useful in myeloid and lymphoid malignancies.
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Affiliation(s)
- Adam Lerner
- *Evans Department of Medicine, Section of Hematology and Oncology, Boston Medical Center, Boston, MA 02118, U.S.A
- †Department of Pathology, Boston University School of Medicine, Boston, MA 02118, U.S.A
| | - Paul M. Epstein
- ‡Department of Pharmacology, University of Connecticut Health Center, Farmington, CT 06030, U.S.A
- To whom correspondence should be addressed (email )
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Jin JY, Almon RR, DuBois DC, Jusko WJ. Modeling of corticosteroid pharmacogenomics in rat liver using gene microarrays. J Pharmacol Exp Ther 2003; 307:93-109. [PMID: 12808002 DOI: 10.1124/jpet.103.053256] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Corticosteroid (CS) pharmacogenomics was studied using gene microarrays in rat liver. Methylprednisolone (MPL) was administered intravenously at 50 mg/kg. Rats were sacrificed and liver excised at 17 time points over 72 h. RNAs from individual livers were used to query Affymetrix GeneChips that contain sequences for 8000 genes. Cluster analysis revealed six temporal patterns consisting of 197 CS-responsive probes representing 143 genes. Based on our fifth-generation model of CS pharmacokinetics/pharmacodynamics (PK/PD), mechanistic models were developed to describe the time pattern for each CS-responsive gene. Two clusters showed increased expression with different effect duration. PK/PD models assuming CS stimulation of mRNA synthesis were applied. Another two clusters showed an initial decline followed by delayed increase, suggesting two mechanisms might be involved jointly. The initial suppression was captured by CS inhibition of mRNA synthesis or stimulation of degradation. CS may also stimulate the production of a biosignal (transcription factors or other hormones), which can cause secondary induction of the target mRNA. One cluster showed a very abrupt increase in message followed by rapid decrease. These genes were lymphocytic in origin and were modeled combining the fast gene induction effect of CS in lymphoid cells and its direct lymphocyte trafficking effect. Another cluster showed reduction persisting for 18 h, which was described by CS inhibition of mRNA synthesis. Our results reveal the marked diversity of genes regulated by CS via a limited array of mechanisms. These PK/PD models provide quantitation of CS pharmacogenomics and new hypotheses regarding understanding of diverse mechanisms of CS receptor-gene mediated action.
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Affiliation(s)
- Jin Y Jin
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, 565 Hochstetter Hall, State University of New York at Buffalo, 14260, USA
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11
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Houslay MD. PDE4 cAMP-specific phosphodiesterases. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 2001; 69:249-315. [PMID: 11550796 DOI: 10.1016/s0079-6603(01)69049-4] [Citation(s) in RCA: 177] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- M D Houslay
- Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, Scotland, United Kingdom.
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12
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Abstract
Hepatothermic therapy (HT) of obesity is rooted in the observation that the liver has substantial capacities for both fatty acid oxidation and for thermogenesis. When hepatic fatty acid oxidation is optimized, the newly available free energy may be able to drive hepatic thermogenesis, such that respiratory quotient declines while basal metabolic rate increases, a circumstance evidently favorable for fat loss. Effective implementation of HT may require activation of carnitine palmitoyl transferase-1 (rate-limiting for fatty acid beta-oxidation), an increase in mitochondrial oxaloacetate production (required for optimal Krebs cycle activity), and up-regulation of hepatic thermogenic pathways. The possible utility of various natural agents and drugs for achieving these objectives is discussed. Potential components of HT regimens include EPA-rich fish oil, sesamin, hydroxycitrate, pantethine, L-carnitine, pyruvate, aspartate, chromium, coenzyme Q10, green tea polyphenols, conjugated linoleic acids, DHEA derivatives, cilostazol, diazoxide, and fibrate drugs. Aerobic exercise training and very-low-fat, low-glycemic-index, high-protein or vegan food choices may help to establish the hormonal environment conducive to effective HT. High-dose biotin and/or metformin may help to prevent an excessive increase in hepatic glucose output. Since many of the agents contemplated as components of HT regimens are nutritional or food-derived compounds likely to be health protective, HT is envisioned as an on-going lifestyle rather than as a temporary 'quick fix'. Initial clinical efforts to evaluate the potential of HT are now in progress.
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Affiliation(s)
- M F McCarty
- Pantox Laboratories, San Diego, California 92109, USA
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13
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Scheving LA, Russell WE. Insulin and heregulin-beta1 upregulate guanylyl cyclase C expression in rat hepatocytes: reversal by phosphodiesterase-3 inhibition. Cell Signal 2001; 13:665-72. [PMID: 11495724 DOI: 10.1016/s0898-6568(01)00179-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Guanylyl cyclase C (GC-C) is the receptor for the hormones guanylin and uroguanylin. Although primarily expressed in the rat intestine, GC-C is also expressed in the liver during neonatal or regenerative growth or during the acute phase response. Little is known about the hepatic regulation of GC-C expression. The influence of various hepatic growth or acute phase regulators on GC-C expression was evaluated by immunoblot analysis of protein from primary rat hepatocytes grown in a serum-free medium. Insulin and heregulin-beta1 strongly stimulated GC-C expression by 24 h of cell culture. Several different hormones and agents suppressed this action, including transforming growth factor beta (TGF-beta), as well as inhibitors of phosphatidylinositol 3-kinase (PI-3-kinase) and phosphodiesterase 3 (PDE-3, an insulin- and PI-3-kinase-dependent enzyme). The compartmental downregulation of cAMP levels by PDE-3 may be a critical step in the hormonal action that culminates in GC-C synthesis.
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Affiliation(s)
- L A Scheving
- Division of Pediatric Gastroenterology and Nutrition, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
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14
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Flores-Morales A, Ståhlberg N, Tollet-Egnell P, Lundeberg J, Malek RL, Quackenbush J, Lee NH, Norstedt G. Microarray analysis of the in vivo effects of hypophysectomy and growth hormone treatment on gene expression in the rat. Endocrinology 2001; 142:3163-76. [PMID: 11416039 DOI: 10.1210/endo.142.7.8235] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Complementary DNA microarrays containing 3000 different rat genes were used to study the consequences of severe hormonal deficiency (hypophysectomy) on the gene expression patterns in heart, liver, and kidney. Hybridization signals were seen from a majority of the arrayed complementary DNAs; nonetheless, tissue-specific expression patterns could be delineated. Hypophysectomy affected the expression of genes involved in a variety of cellular functions. Between 16-29% of the detected transcripts from each tissue changed expression level as a reaction to this condition. Chronic treatment of hypophysectomized animals with human GH also caused significant changes in gene expression patterns. The study confirms previous knowledge concerning certain gene expression changes in the above-mentioned situations and provides new information regarding hypophysectomy and chronic human GH effects in the rat. Furthermore, we have identified several new genes that respond to GH treatment. Our results represent a first step toward a more global understanding of gene expression changes in states of hormonal deficiency.
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Affiliation(s)
- A Flores-Morales
- Department of Molecular Medicine, Karolinska Institute, 17176 Stockholm, Sweden
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15
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Baus E, Van Laethem F, Andris F, Rolin S, Urbain J, Leo O. Dexamethasone increases intracellular cyclic AMP concentration in murine T lymphocyte cell lines. Steroids 2001; 66:39-47. [PMID: 11090657 DOI: 10.1016/s0039-128x(00)00137-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The effects of the synthetic glucocorticoid dexamethasone on the cAMP content of murine T lymphocyte cell lines has been investigated. Incubation of the 3B4.15 T cell hybrids with dexamethasone results in an average 5-fold increase in intracellular cyclic AMP levels after 6 h of treatment. This phenomenon is abolished in the presence of RU486 and of cycloheximide, indicating that it requires binding of the drug to the intracellular glucocorticoids receptor and de novo protein synthesis. Dexamethasone-induced elevation of intracellular cyclic AMP correlates with both an increase in adenylate cyclase activity and a decrease in phosphodiesterase activity in T cell hybrids. This modulation of cyclic AMP metabolism is independent of serum-derived factors, suggesting that it is not secondary to transmembrane receptor stimulation by an extracellular ligand. We propose that glucocorticoids interfere with the homeostatic control of intracellular cAMP concentration, leading to a sustained increase in the content of this important second messenger in murine T lymphocyte cell lines. This study suggests that elevation of cAMP levels may represent one way by which glucocorticoids modulate the immune response.
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Affiliation(s)
- E Baus
- Animal Physiology Laboratory, Free University of Brussels, Avenue des Prof. Jeener et Brachet 12, 6041, Gosselies, Belgium
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