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Shiozaki‐Takagi Y, Ozaki N, Toyoda Y. Epac2 activation mediates glucagon-induced glucogenesis in primary rat hepatocytes. J Diabetes Investig 2024; 15:429-436. [PMID: 38243676 PMCID: PMC10981141 DOI: 10.1111/jdi.14142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 12/06/2023] [Accepted: 12/21/2023] [Indexed: 01/21/2024] Open
Abstract
AIMS/INTRODUCTION Glucagon plays an essential role in hepatic glucogenesis by enhancing glycogen breakdown, inducing gluconeogenesis, and suppressing glycogenesis. Moreover, glucagon increases cyclic adenosine monophosphate (cAMP) levels, thereby activating protein kinase A (PKA) and cAMP guanine nucleotide exchange factor (also known as Epac). Although the function of PKA in the liver has been studied extensively, the function of hepatic Epac is poorly understood. The aim of this study was to elucidate the role of Epac in mediating the action of glucagon on the hepatocytes. MATERIALS AND METHODS Epac mRNA and protein expression, localization, and activity in the hepatocytes were analyzed by reverse transcription polymerase chain reaction, western blotting, immunofluorescence staining, and Rap1 activity assay, respectively. Additionally, we investigated the effects of an Epac-specific activator, 8-CPT, and an Epac-specific inhibitor, ESI-05, on glycogen metabolism in isolated rat hepatocytes. Further mechanisms of glycogen metabolism were evaluated by examining glucokinase (GK) translocation and mRNA expression of gluconeogenic enzymes. RESULTS Epac2, but not Epac1, was predominantly expressed in the liver. Moreover, 8-CPT inhibited glycogen accumulation and GK translocation and enhanced the mRNA expression of gluconeogenic enzymes. ESI-05 failed to reverse glucagon-induced suppression of glycogen storage and partially inhibited glucagon-induced GK translocation and the mRNA expression of gluconeogenic enzymes. CONCLUSIONS Epac signaling plays a role in mediating the glucogenic action of glucagon in the hepatocytes.
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Affiliation(s)
- Yusuke Shiozaki‐Takagi
- Research Center of Health, Physical Fitness and SportsNagoya UniversityNagoyaJapan
- Department of Pathobiochemistry, Faculty of PharmacyMeijo UniversityNagoyaJapan
- Present address:
Division of Cell Signaling and Molecular Medicine, Institute of Medical ScienceThe University of TokyoTokyoJapan
| | - Nobuaki Ozaki
- Research Center of Health, Physical Fitness and SportsNagoya UniversityNagoyaJapan
- Division of EndocrinologyJapanese Red Cross Aichi Medical Center Nagoya Daiichi HospitalNagoyaJapan
| | - Yukiyasu Toyoda
- Department of Pathobiochemistry, Faculty of PharmacyMeijo UniversityNagoyaJapan
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Lewis MJ, Khaliulin I, Hall K, Suleiman MS. Cardioprotection of Immature Heart by Simultaneous Activation of PKA and Epac: A Role for the Mitochondrial Permeability Transition Pore. Int J Mol Sci 2022; 23:ijms23031720. [PMID: 35163640 PMCID: PMC8836102 DOI: 10.3390/ijms23031720] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Revised: 01/25/2022] [Accepted: 01/30/2022] [Indexed: 02/04/2023] Open
Abstract
Metabolic and ionic changes during ischaemia predispose the heart to the damaging effects of reperfusion. Such changes and the resulting injury differ between immature and adult hearts. Therefore, cardioprotective strategies for adults must be tested in immature hearts. We have recently shown that the simultaneous activation of protein kinase A (PKA) and exchange protein activated by cAMP (Epac) confers marked cardioprotection in adult hearts. The aim of this study is to investigate the efficacy of this intervention in immature hearts and determine whether the mitochondrial permeability transition pore (MPTP) is involved. Isolated perfused Langendorff hearts from both adult and immature rats were exposed to global ischaemia and reperfusion injury (I/R) following control perfusion or perfusion after an equilibration period with activators of PKA and/or Epac. Functional outcome and reperfusion injury were measured and in parallel, mitochondria were isolated following 5 min of reperfusion to determine whether cardioprotective interventions involved changes in MPTP opening behaviour. Perfusion for 5 min preceding ischaemia of injury-matched adult and immature hearts with 5 µM 8-Br (8-Br-cAMP-AM), an activator of both PKA and Epac, led to significant reduction in post-reperfusion CK release and infarct size. Perfusion with this agent also led to a reduction in MPTP opening propensity in both adult and immature hearts. These data show that immature hearts are innately more resistant to I/R injury than adults, and that this is due to a reduced tendency of MPTP opening following reperfusion. Furthermore, simultaneous stimulation of PKA and Epac causes cardioprotection, which is additive to the innate resistance.
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Affiliation(s)
- Martin John Lewis
- School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol BS8 1TD, UK
- Correspondence:
| | - Igor Khaliulin
- School of Pharmacy, Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem 91120, Israel;
| | - Katie Hall
- Bristol Medical School, University of Bristol, Bristol BS8 1TH, UK; (K.H.); (M.S.S.)
| | - M. Saadeh Suleiman
- Bristol Medical School, University of Bristol, Bristol BS8 1TH, UK; (K.H.); (M.S.S.)
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3
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Wang H, Gaur U, Xiao J, Xu B, Xu J, Zheng W. Targeting phosphodiesterase 4 as a potential therapeutic strategy for enhancing neuroplasticity following ischemic stroke. Int J Biol Sci 2018; 14:1745-1754. [PMID: 30416389 PMCID: PMC6216030 DOI: 10.7150/ijbs.26230] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 06/03/2018] [Indexed: 12/11/2022] Open
Abstract
Sensorimotor recovery following ischemic stroke is highly related with structural modification and functional reorganization of residual brain tissues. Manipulations, such as treatment with small molecules, have been shown to enhance the synaptic plasticity and contribute to the recovery. Activation of the cAMP/CREB pathway is one of the pivotal approaches stimulating neuroplasticity. Phosphodiesterase 4 (PDE4) is a major enzyme controlling the hydrolysis of cAMP in the brain. Accumulating evidences have shown that inhibition of PDE4 is beneficial for the functional recovery after cerebral ischemia; i. subtype D of PDE4 (PDE4D) is viewed as a risk factor for ischemic stroke; ii. inhibition of PDE4 enhances neurological behaviors, such as learning and memory, after stroke in rodents; iii.PDE4 inhibition increases dendritic density, synaptic plasticity and neurogenesis; iv. activation of cAMP/CREB signaling by PDE4 inhibition causes an endogenous increase of BDNF, which is a potent modulator of neuroplasticity; v. PDE4 inhibition is believed to restrict neuroinflammation during ischemic stroke. Cumulatively, these findings provide a link between PDE4 inhibition and neuroplasticity after cerebral ischemia. Here, we summarized the possible roles of PDE4 inhibition in the recovery of cerebral stroke with an emphasis on neuroplasticity. We also made some recommendations for future research.
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Affiliation(s)
- Haitao Wang
- Department of Neuropharmacology and Drug Discovery, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Uma Gaur
- Faculty of Health Sciences, University of Macau, Taipa, Macau, China
| | - Jiao Xiao
- Department of Neuropharmacology and Drug Discovery, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Bingtian Xu
- Department of Neuropharmacology and Drug Discovery, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Jiangping Xu
- Department of Neuropharmacology and Drug Discovery, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Wenhua Zheng
- Faculty of Health Sciences, University of Macau, Taipa, Macau, China
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Khedr MEMS, Abdelmotelb AM, Bedwell TA, Shtaya A, Alzoubi MN, Abu Hilal M, Khakoo SI. Vasoactive intestinal peptide induces proliferation of human hepatocytes. Cell Prolif 2018; 51:e12482. [PMID: 30028555 DOI: 10.1111/cpr.12482] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 05/04/2018] [Indexed: 12/24/2022] Open
Abstract
OBJECTIVES Proliferation of hepatocytes in vitro can be stimulated by growth factors such as epidermal growth factor (EGF), but the role of vasoactive intestinal peptide (VIP) remains unclear. We have investigated the effect of VIP on maintenance and proliferation of human hepatocytes. MATERIALS AND METHODS Human hepatocytes were isolated from liver specimens obtained from patients undergoing liver surgery. Treatment with VIP or EGF was started 24 h after plating and continued for 3 or 5 d. DNA replication was investigated by Bromodeoxyuridine (BrdU) incorporation and cell viability detected by MTT assay. Cell lysate was analysed by western blotting and RT-PCR. Urea and albumin secretion into the culture supernatants were measured. RESULTS VIP increased DNA replication in hepatocytes in a dose-dependant manner, with a peak response at day 3 of treatment. VIP treatment was associated with an increase in mRNA expression of antigen identified by monoclonal antibody Ki-67 (MKI-67) and Histone Cluster 3 (H3) genes. Western blotting analysis showed that VIP can induce a PKA/B-Raf dependant phosphorylation of extracellular signal-regulated kinases (ERK). Although EGF can maintain hepatocyte functions up to day 5, no marked efffect was found with VIP. CONCLUSIONS VIP induces proliferation of human hepatocytes with little or no effect on hepatocyte differentiation. Further investigation of the role of VIP is required to determine if it may ultimately support therapeutic approaches of liver disease.
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Affiliation(s)
- M E M S Khedr
- Clinical and Experimental Sciences Academic Unit, Faculty of Medicine, University of Southampton, Southampton, UK.,Faculty of Medicine, Suez Canal University, Ismailia, Egypt
| | - A M Abdelmotelb
- Clinical and Experimental Sciences Academic Unit, Faculty of Medicine, University of Southampton, Southampton, UK.,Faculty of Medicine, Tanta University, Tanta, Egypt
| | - T A Bedwell
- Clinical and Experimental Sciences Academic Unit, Faculty of Medicine, University of Southampton, Southampton, UK
| | - A Shtaya
- St George's University of London, London, UK
| | - M N Alzoubi
- Clinical and Experimental Sciences Academic Unit, Faculty of Medicine, University of Southampton, Southampton, UK.,University of Jordan, Amman, Jordan.,Southampton University Hospitals NHS Trust, Southampton, UK
| | - M Abu Hilal
- Clinical and Experimental Sciences Academic Unit, Faculty of Medicine, University of Southampton, Southampton, UK.,Southampton University Hospitals NHS Trust, Southampton, UK
| | - S I Khakoo
- Clinical and Experimental Sciences Academic Unit, Faculty of Medicine, University of Southampton, Southampton, UK.,Southampton University Hospitals NHS Trust, Southampton, UK
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Robichaux WG, Cheng X. Intracellular cAMP Sensor EPAC: Physiology, Pathophysiology, and Therapeutics Development. Physiol Rev 2018; 98:919-1053. [PMID: 29537337 PMCID: PMC6050347 DOI: 10.1152/physrev.00025.2017] [Citation(s) in RCA: 138] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 09/05/2017] [Accepted: 09/06/2017] [Indexed: 12/13/2022] Open
Abstract
This review focuses on one family of the known cAMP receptors, the exchange proteins directly activated by cAMP (EPACs), also known as the cAMP-regulated guanine nucleotide exchange factors (cAMP-GEFs). Although EPAC proteins are fairly new additions to the growing list of cAMP effectors, and relatively "young" in the cAMP discovery timeline, the significance of an EPAC presence in different cell systems is extraordinary. The study of EPACs has considerably expanded the diversity and adaptive nature of cAMP signaling associated with numerous physiological and pathophysiological responses. This review comprehensively covers EPAC protein functions at the molecular, cellular, physiological, and pathophysiological levels; and in turn, the applications of employing EPAC-based biosensors as detection tools for dissecting cAMP signaling and the implications for targeting EPAC proteins for therapeutic development are also discussed.
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Affiliation(s)
- William G Robichaux
- Department of Integrative Biology and Pharmacology, Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center , Houston, Texas
| | - Xiaodong Cheng
- Department of Integrative Biology and Pharmacology, Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center , Houston, Texas
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Zhang B, Lakshmanan J, Du Y, Smith JW, Harbrecht BG. Cell-specific regulation of iNOS by AMP-activated protein kinase in primary rat hepatocytes. J Surg Res 2017; 221:104-112. [PMID: 29229115 DOI: 10.1016/j.jss.2017.08.028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 06/21/2017] [Accepted: 08/14/2017] [Indexed: 12/29/2022]
Abstract
BACKGROUND AMP-activated protein kinase (AMPK) regulates several metabolic pathways in hepatocytes that are critical to the hepatic response to sepsis and shock. Induction of nitric oxide synthesis is an important response to sepsis, inflammation and shock and many of the stimuli that upregulate inducible nitric oxide synthase (iNOS) also activate AMPK. AMPK inhibits nitric oxide (NO) production in skeletal and cardiac muscle cells, but the role of AMPK in regulating iNOS expression in hepatocytes has not been determined. MATERIALS AND METHODS Primary cultured rat hepatocytes were preincubated with an AMPK inhibitor, AMPK activators, or transfected with AMPK siRNA before being treated with the proinflammatory cytokines interleukin-1β (IL-1β) and interferon-γ (IFNγ). The hepatocyte cell lysate and culture supernatants were collected for Western blot analysis and Griess assay. RESULTS IL-1β and IFNγ markedly upregulated iNOS expression and AMPK phosphorylation. IL-1β + IFNγ-induced NO production and iNOS expression were significantly decreased in hepatocytes treated with the AMPK inhibitor compound C and AMPK knockdown by AMPK siRNA. Cytokine-induced iNOS expression was increased by AMPK activators 1-oxo-2-(2H-pyrrolium-1-yl)-1H-inden-3-olate, AMPK signaling activator III and AICA-riboside. Compound C upregulated Akt and c-Jun N-terminal kinase phosphorylation but decreased IκBα phosphorylation. AICA-riboside exerted opposite effects on these signaling pathways in hepatocytes. CONCLUSIONS In contrast to other cell types, AMPK increased IL-1β + IFNγ-induced NO production and iNOS expression through the Akt, c-Jun N-terminal kinase, and NF-κΒ signaling pathways in primary hepatocytes. These data suggest that AMPK-altering medications used clinically may have subsequent effects on iNOS expression and proinflammatory signaling pathways.
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Affiliation(s)
- Baochun Zhang
- Department of Surgery and Price Institute of Surgical Research, University of Louisville, Louisville, Kentucky.
| | - Jaganathan Lakshmanan
- Department of Surgery and Price Institute of Surgical Research, University of Louisville, Louisville, Kentucky
| | - Yibo Du
- Department of Surgery and Price Institute of Surgical Research, University of Louisville, Louisville, Kentucky
| | - Jason W Smith
- Department of Surgery and Price Institute of Surgical Research, University of Louisville, Louisville, Kentucky
| | - Brian G Harbrecht
- Department of Surgery and Price Institute of Surgical Research, University of Louisville, Louisville, Kentucky
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Guinzberg R, Díaz-Cruz A, Acosta-Trujillo C, Vilchis-Landeros MM, Vázquez-Meza H, Lozano-Flores C, Chiquete-Felix N, Varela-Echavarría A, Uribe-Carvajal S, Riveros-Rosas H, Piña E. Newly synthesized cAMP is integrated at a membrane protein complex signalosome to ensure receptor response specificity. FEBS J 2016; 284:258-276. [PMID: 27865066 DOI: 10.1111/febs.13969] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 10/11/2016] [Accepted: 11/17/2016] [Indexed: 01/21/2023]
Abstract
Spatiotemporal regulation of cAMP within the cell is required to achieve receptor-specific responses. The mechanism through which the cell selects a specific response to newly synthesized cAMP is not fully understood. In hepatocyte plasma membranes, we identified two functional and independent cAMP-responsive signaling protein macrocomplexes that produce, use, degrade, and regulate their own nondiffusible (sequestered) cAMP pool to achieve their specific responses. Each complex responds to the stimulation of an adenosine G protein-coupled receptor (Ado-GPCR), bound to either A2A or A2B , but not simultaneously to both. Each isoprotein involved in each signaling cascade was identified by measuring changes in cAMP levels after receptor activation, and its participation was confirmed by antibody-mediated inactivation. A2A -Ado-GPCR selective stimulation activates adenylyl cyclase 6 (AC6), which is bound to AKAP79/150, to synthesize cAMP which is used by two other AKAP79/150-tethered proteins: protein kinase A (PKA) and phosphodiesterase 3A (PDE3A). In contrast, A2B -Ado-GPCR stimulation activates D-AKAP2-attached AC5 to generate cAMP, which is channeled to two other D-AKAP2-tethered proteins: guanine-nucleotide exchange factor 2 (Epac2) and PDE3B. In both cases, prior activation of PKA or Epac2 with selective cAMP analogs prevents de novo cAMP synthesis. In addition, we show that cAMP does not diffuse between these protein macrocomplexes or 'signalosomes'. Evidence of coimmunoprecipitation and colocalization of some proteins belonging to each signalosome is presented. Each signalosome constitutes a minimal functional signaling unit with its own machinery to synthesize and regulate a sequestered cAMP pool. Thus, each signalosome is devoted to ensure the transmission of a unique and unequivocal message through the cell.
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Affiliation(s)
- Raquel Guinzberg
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), Ciudad de México, Mexico
| | - Antonio Díaz-Cruz
- Departamento de Nutrición Animal y Bioquímica, Facultad de Medicina Veterinaria y Zootécnia, Universidad Nacional Autónoma de México (UNAM), Ciudad de México, Mexico
| | - Carlos Acosta-Trujillo
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), Ciudad de México, Mexico
| | | | - Héctor Vázquez-Meza
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), Ciudad de México, Mexico
| | - Carlos Lozano-Flores
- Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
| | - Natalia Chiquete-Felix
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México (UNAM), Ciudad de México, Mexico
| | | | - Salvador Uribe-Carvajal
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México (UNAM), Ciudad de México, Mexico
| | - Héctor Riveros-Rosas
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), Ciudad de México, Mexico
| | - Enrique Piña
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), Ciudad de México, Mexico
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8
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Lewis AE, Aesoy R, Bakke M. Role of EPAC in cAMP-Mediated Actions in Adrenocortical Cells. Front Endocrinol (Lausanne) 2016; 7:63. [PMID: 27379015 PMCID: PMC4904129 DOI: 10.3389/fendo.2016.00063] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Accepted: 05/30/2016] [Indexed: 12/31/2022] Open
Abstract
Adrenocorticotropic hormone regulates adrenal steroidogenesis mainly via the intracellular signaling molecule cAMP. The effects of cAMP are principally relayed by activating protein kinase A (PKA) and the more recently discovered exchange proteins directly activated by cAMP 1 and 2 (EPAC1 and EPAC2). While the intracellular roles of PKA have been extensively studied in steroidogenic tissues, those of EPACs are only emerging. EPAC1 and EPAC2 are encoded by the genes RAPGEF3 and RAPGEF4, respectively. Whereas EPAC1 is ubiquitously expressed, the expression of EPAC2 is more restricted, and typically found in endocrine tissues. Alternative promoter usage of RAPGEF4 gives rise to three different isoforms of EPAC2 that vary in their N-termini (EPAC2A, EPAC2B, and EPAC2C) and that exhibit distinct expression patterns. EPAC2A is expressed in the brain and pancreas, EPAC2B in steroidogenic cells of the adrenal gland and testis, and EPAC2C has until now only been found in the liver. In this review, we discuss current knowledge on EPAC expression and function with focus on the known roles of EPAC in adrenal gland physiology.
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Affiliation(s)
- Aurélia E. Lewis
- Department of Molecular Biology, University of Bergen, Bergen, Norway
- *Correspondence: Aurélia E. Lewis,
| | - Reidun Aesoy
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Marit Bakke
- Department of Biomedicine, University of Bergen, Bergen, Norway
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Kimbrough CW, Lakshmanan J, Matheson PJ, Woeste M, Gentile A, Benns MV, Zhang B, Smith JW, Harbrecht BG. Resveratrol decreases nitric oxide production by hepatocytes during inflammation. Surgery 2015; 158:1095-101; discussion 1101. [PMID: 26283207 DOI: 10.1016/j.surg.2015.07.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Revised: 06/19/2015] [Accepted: 07/15/2015] [Indexed: 12/31/2022]
Abstract
INTRODUCTION The production of excessive amounts of nitric oxide (NO) through inducible nitric oxide synthase (iNOS) contributes to organ injury, inflammation, and mortality after shock. Resveratrol (RSV) is a natural polyphenol that decreases shock-induced hepatic injury and inflammation. We hypothesized that RSV would mediate these effects by decreasing hepatocyte iNOS production. METHODS Rat hepatocytes were isolated, cultured with varying concentrations of RSV, and then stimulated to induce iNOS with interleukin-1 and interferon. Induction of iNOS protein was measured by Western blot, iNOS mRNA by polymerase chain reaction, and NO production was measured by culture supernatant nitrite. Activation of intracellular signaling pathways involving Akt, c-Jun N-terminal kinase (JNK), and nuclear factor κB (NF-κB) were measured by Western blot using isoform-specific antibodies. RESULTS RSV decreased the expression of iNOS mRNA, protein, and supernatant nitrite in a dose-dependent manner. Our previous work demonstrated that Akt and JNK both inhibit hepatic iNOS production, whereas NF-κB increases iNOS expression. Analysis of signaling pathways in this study demonstrated that RSV increased JNK phosphorylation but decreased Akt phosphorylation and increased NF-κB activation. CONCLUSION RSV decreases cytokine-induced hepatocyte iNOS expression, possibly through up-regulation of the JNK signaling pathway. RSV merits further investigation to determine its mechanism as a compound that can decrease inflammation after shock.
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Affiliation(s)
- Charles W Kimbrough
- The Hiram C. Polk Jr., MD Department of Surgery and Price Institute of Surgical Research, University of Louisville School of Medicine, Louisville, KY
| | - Jaganathan Lakshmanan
- The Hiram C. Polk Jr., MD Department of Surgery and Price Institute of Surgical Research, University of Louisville School of Medicine, Louisville, KY
| | - Paul J Matheson
- The Hiram C. Polk Jr., MD Department of Surgery and Price Institute of Surgical Research, University of Louisville School of Medicine, Louisville, KY
| | - Matthew Woeste
- The Hiram C. Polk Jr., MD Department of Surgery and Price Institute of Surgical Research, University of Louisville School of Medicine, Louisville, KY
| | - Andrea Gentile
- The Hiram C. Polk Jr., MD Department of Surgery and Price Institute of Surgical Research, University of Louisville School of Medicine, Louisville, KY
| | - Matthew V Benns
- The Hiram C. Polk Jr., MD Department of Surgery and Price Institute of Surgical Research, University of Louisville School of Medicine, Louisville, KY
| | - Baochun Zhang
- The Hiram C. Polk Jr., MD Department of Surgery and Price Institute of Surgical Research, University of Louisville School of Medicine, Louisville, KY
| | - Jason W Smith
- The Hiram C. Polk Jr., MD Department of Surgery and Price Institute of Surgical Research, University of Louisville School of Medicine, Louisville, KY
| | - Brian G Harbrecht
- The Hiram C. Polk Jr., MD Department of Surgery and Price Institute of Surgical Research, University of Louisville School of Medicine, Louisville, KY.
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10
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Zhang B, Crankshaw W, Nesemeier R, Patel J, Nweze I, Lakshmanan J, Harbrecht BG. Calcium-mediated signaling and calmodulin-dependent kinase regulate hepatocyte-inducible nitric oxide synthase expression. J Surg Res 2014; 193:795-801. [PMID: 25150084 DOI: 10.1016/j.jss.2014.07.042] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 07/14/2014] [Accepted: 07/18/2014] [Indexed: 02/07/2023]
Abstract
BACKGROUND Induced nitric oxide synthase (iNOS) is induced in hepatocytes by shock and inflammatory stimuli. Excessive NO from iNOS mediates shock-induced hepatic injury and death, so understanding the regulation of iNOS will help elucidate the pathophysiology of septic shock. In vitro, cytokines induce iNOS expression through activation of signaling pathways including mitogen-activated protein kinases and nuclear factor κB. Cytokines also induce calcium (Ca(2+)) mobilization and activate calcium-mediated intracellular signaling pathways, typically through activation of calmodulin-dependent kinases (CaMK). Calcium regulates NO production in macrophages but the role of calcium and calcium-mediated signaling in hepatocyte iNOS expression has not been defined. MATERIALS AND METHODS Primary rat hepatocytes were isolated, cultured, and induced to produce NO with proinflammatory cytokines. Calcium mobilization and Ca(2+)-mediated signaling were altered with ionophore, Ca(2+) channel blockers, and inhibitors of CaMK. RESULTS The Ca(2+) ionophore A23187 suppressed cytokine-stimulated NO production, whereas Ethylene glycol tetraacetic acid and nifedipine increased NO production, iNOS messenger RNA, and iNOS protein expression. Inhibition of CaMK with KN93 and CBD increased NO production but the calcineurin inhibitor FK 506 decreased iNOS expression. CONCLUSIONS These data demonstrate that calcium-mediated signaling regulates hepatocyte iNOS expression and does so through a mechanism independent of calcineurin. Changes in intracellular calcium levels may regulate iNOS expression during hepatic inflammation induced by proinflammatory cytokines.
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Affiliation(s)
- Baochun Zhang
- The Hiram C. Polk, Jr. MD Department of Surgery, the Price Institute for Surgical Research, University of Louisville, Louisville, Kentucky
| | - Will Crankshaw
- The Hiram C. Polk, Jr. MD Department of Surgery, the Price Institute for Surgical Research, University of Louisville, Louisville, Kentucky
| | - Ryan Nesemeier
- The Hiram C. Polk, Jr. MD Department of Surgery, the Price Institute for Surgical Research, University of Louisville, Louisville, Kentucky
| | - Jay Patel
- The Hiram C. Polk, Jr. MD Department of Surgery, the Price Institute for Surgical Research, University of Louisville, Louisville, Kentucky
| | - Ikenna Nweze
- The Hiram C. Polk, Jr. MD Department of Surgery, the Price Institute for Surgical Research, University of Louisville, Louisville, Kentucky
| | - Jaganathan Lakshmanan
- The Hiram C. Polk, Jr. MD Department of Surgery, the Price Institute for Surgical Research, University of Louisville, Louisville, Kentucky
| | - Brian G Harbrecht
- The Hiram C. Polk, Jr. MD Department of Surgery, the Price Institute for Surgical Research, University of Louisville, Louisville, Kentucky.
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11
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Cholecystokinin inhibits inducible nitric oxide synthase expression by lipopolysaccharide-stimulated peritoneal macrophages. Mediators Inflamm 2014; 2014:896029. [PMID: 25125801 PMCID: PMC4122025 DOI: 10.1155/2014/896029] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 05/26/2014] [Accepted: 06/23/2014] [Indexed: 01/10/2023] Open
Abstract
Cholecystokinin (CCK) was first described as a gastrointestinal hormone. However, apart from its gastrointestinal effects, studies have described that CCK also plays immunoregulatory roles. Taking in account the involvement of inducible nitric oxide synthase- (iNOS-) derived NO in the sepsis context, the present study was undertaken to investigate the role of CCK on iNOS expression in LPS-activated peritoneal macrophages. Our results revealed that CCK reduces NO production and attenuates the iNOS mRNA expression and protein formation. Furthermore, CCK inhibited the nuclear factor- (NF-) κB pathway reducing IκBα degradation and minor p65-dependent translocation to the nucleus. Moreover, CCK restored the intracellular cAMP content activating the protein kinase A (PKA) pathway, which resulted in a negative modulatory role on iNOS expression. In peritoneal macrophages, the CCK-1R expression, but not CCK-2R, was predominant and upregulated by LPS. The pharmacological studies confirmed that CCK-1R subtype is the major receptor responsible for the biological effects of CCK. These data suggest an anti-inflammatory role for the peptide CCK in modulating iNOS-derived NO synthesis, possibly controlling the macrophage activation through NF-κB, cAMP-PKA, and CCK-1R pathways. Based on these findings, CCK could be used as an adjuvant agent to modulate the inflammatory response and prevent systemic complications commonly found during sepsis.
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12
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WHAT’S NEW IN SHOCK, JANUARY 2013? Shock 2013; 39:1-2. [DOI: 10.1097/shk.0b013e31827e8dd1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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