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Dos Santos ML, França A, Lima Filho ACM, Florentino RM, Diniz PH, Oliveira Lemos F, Gonçalves CAX, Coelho VL, Lima CX, Foureaux G, Nathanson MH, Vidigal PVT, Leite MF. Inositol 1,4,5-trisphosphate receptor type 3 is involved in resistance to apoptosis and maintenance of human hepatocellular carcinoma. Oncol Lett 2022; 23:32. [PMID: 34966448 PMCID: PMC8669656 DOI: 10.3892/ol.2021.13150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 09/24/2021] [Indexed: 11/06/2022] Open
Abstract
The expression of the inositol 1,4,5-trisphosphate receptor type 3 (ITRP3) in hepatocytes is a common event in the pathogenesis of hepatocellular carcinoma (HCC), regardless of the type of underlying liver disease. However, it is not known whether ITPR3 expression in hepatocytes is involved in tumor maintenance. The aim of the present study was to determine whether there is an association between ITPR3 expression and clinical and morphological parameters using HCC samples obtained from liver explants from patients (n=53) with different etiologies of underlying chronic liver disease (CLD). ITPR3 expression, mitosis and apoptosis were analyzed in human liver samples by immunohistochemistry. Clinical and event-free survival data were combined to assess the relationship between ITPR3 and liver cancer growth in patients. RNA sequencing analysis was performed to identify apoptotic genes altered by ITPR3 expression in a liver tumor cell line. ITPR3 was highly expressed in HCC tumor cells relative to adjacent CLD tissue and healthy livers. There was an inverse correlation between ITPR3 expression and mitotic and apoptotic indices in HCC, suggesting that ITPR3 contributed to the maintenance of HCC by promoting resistance to apoptosis. This was confirmed by the upregulation of CTSB, CHOP and GADD45, genes involved in the apoptotic pathway in HCC. The expression of ITPR3 in the liver may be a promising prognostic marker of HCC.
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Affiliation(s)
- Marcone Loiola Dos Santos
- Department of Morphology, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais 31270-901, Brazil
- Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais 31270-901, Brazil
| | - Andressa França
- Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais 31270-901, Brazil
| | - Antônio Carlos Melo Lima Filho
- Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais 31270-901, Brazil
| | - Rodrigo M. Florentino
- Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais 31270-901, Brazil
| | - Paulo Henrique Diniz
- Department of Internal Medicine, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais 31270-901, Brazil
| | - Fernanda Oliveira Lemos
- Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais 31270-901, Brazil
| | - Carlos Alberto Xavier Gonçalves
- Coordination of Biotechnology, SENAI's Innovation Institute for Biosynthetics and Fibers, SENAI CETIQT, Rio de Janeiro 20961-020, Brazil
| | - Vitor Lima Coelho
- Coordination of Biotechnology, SENAI's Innovation Institute for Biosynthetics and Fibers, SENAI CETIQT, Rio de Janeiro 20961-020, Brazil
| | - Cristiano Xavier Lima
- Department of Surgery, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais 30 130-100, Brazil
| | - Giselle Foureaux
- Department of Morphology, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais 31270-901, Brazil
| | - Michael H. Nathanson
- Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520-8056, USA
| | - Paula Vieira Teixeira Vidigal
- Department of Pathological Anatomy and Forensic Medicine of Hospital das Clínicas, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais 30 130-100, Brazil
| | - M. Fátima Leite
- Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais 31270-901, Brazil
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Lemos FDO, França A, Lima Filho ACM, Florentino RM, Santos ML, Missiaggia DG, Rodrigues GOL, Dias FF, Souza Passos IB, Teixeira MM, Andrade AMDF, Lima CX, Vidigal PVT, Costa VV, Fonseca MC, Nathanson MH, Leite MF. Molecular Mechanism for Protection Against Liver Failure in Human Yellow Fever Infection. Hepatol Commun 2020; 4:657-669. [PMID: 32363317 PMCID: PMC7193135 DOI: 10.1002/hep4.1504] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 02/18/2020] [Accepted: 02/20/2020] [Indexed: 12/18/2022] Open
Abstract
Yellow fever (YF) is a viral hemorrhagic fever that typically involves the liver. Brazil recently experienced its largest recorded YF outbreak, and the disease was fatal in more than a third of affected individuals, mostly because of acute liver failure. Affected individuals are generally treated only supportively, but during the recent Brazilian outbreak, selected patients were treated with liver transplant. We took advantage of this clinical experience to better characterize the clinical and pathological features of YF-induced liver failure and to examine the mechanism of hepatocellular injury in YF, to identify targets that would be amenable to therapeutic intervention in preventing progression to liver failure and death. Patients with YF liver failure rapidly developed massive transaminase elevations, with jaundice, coagulopathy, thrombocytopenia, and usually hepatic encephalopathy, along with pathological findings that included microvesicular steatosis and lytic necrosis. Hepatocytes began to express the type 3 isoform of the inositol trisphosphate receptor (ITPR3), an intracellular calcium (Ca2+) channel that is not normally expressed in hepatocytes. Experiments in an animal model, isolated hepatocytes, and liver-derived cell lines showed that this new expression of ITPR3 was associated with increased nuclear Ca2+ signaling and hepatocyte proliferation, and reduced steatosis and cell death induced by the YF virus. Conclusion: Yellow fever often induces liver failure characterized by massive hepatocellular damage plus steatosis. New expression of ITPR3 also occurs in YF-infected hepatocytes, which may represent an endogenous protective mechanism that could suggest approaches to treat affected individuals before they progress to liver failure, thereby decreasing the mortality of this disease in a way that does not rely on the costly and limited resource of liver transplantation.
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Affiliation(s)
| | - Andressa França
- Department of Physiology and BiophysicsUniversidade Federal de Minas GeraisBelo HorizonteBrazil
| | | | - Rodrigo M. Florentino
- Department of Physiology and BiophysicsUniversidade Federal de Minas GeraisBelo HorizonteBrazil
| | - Marcone Loiola Santos
- Department of Physiology and BiophysicsUniversidade Federal de Minas GeraisBelo HorizonteBrazil
| | - Dabny G. Missiaggia
- Department of Physiology and BiophysicsUniversidade Federal de Minas GeraisBelo HorizonteBrazil
| | | | - Felipe Ferraz Dias
- Center of MicroscopyUniversidade Federal de Minas GeraisBelo HorizonteBrazil
| | | | - Mauro M. Teixeira
- Department of Biochemistry and ImmunologyUniversidade Federal de Minas GeraisBelo HorizonteBrazil
| | | | - Cristiano Xavier Lima
- Hepatic Transplant ServiceHospital Felício RochoBelo HorizonteBrazil
- SurgeryUniversidade Federal de Minas GeraisBelo HorizonteBrazil
| | | | | | - Matheus Castro Fonseca
- Brazilian Biosciences National Laboratory (LNBio)Brazilian Center for Research in Energy and MaterialsRua Giuseppe Máximo ScolfaroCampinasBrazil
| | - Michael H. Nathanson
- Section of Digestive DiseasesDepartment of Internal MedicineYale University School of MedicineNew HavenCT
| | - M. Fatima Leite
- Department of Physiology and BiophysicsUniversidade Federal de Minas GeraisBelo HorizonteBrazil
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3
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Casciano JC, Duchemin NJ, Lamontagne RJ, Steel LF, Bouchard MJ. Hepatitis B virus modulates store-operated calcium entry to enhance viral replication in primary hepatocytes. PLoS One 2017; 12:e0168328. [PMID: 28151934 PMCID: PMC5289456 DOI: 10.1371/journal.pone.0168328] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 11/30/2016] [Indexed: 12/13/2022] Open
Abstract
Many viruses modulate calcium (Ca2+) signaling to create a cellular environment that is more permissive to viral replication, but for most viruses that regulate Ca2+ signaling, the mechanism underlying this regulation is not well understood. The hepatitis B virus (HBV) HBx protein modulates cytosolic Ca2+ levels to stimulate HBV replication in some liver cell lines. A chronic HBV infection is associated with life-threatening liver diseases, including hepatocellular carcinoma (HCC), and HBx modulation of cytosolic Ca2+ levels could have an important role in HBV pathogenesis. Whether HBx affects cytosolic Ca2+ in a normal hepatocyte, the natural site of an HBV infection, has not been addressed. Here, we report that HBx alters cytosolic Ca2+ signaling in cultured primary hepatocytes. We used single cell Ca2+ imaging of cultured primary rat hepatocytes to demonstrate that HBx elevates the cytosolic Ca2+ level in hepatocytes following an IP3-linked Ca2+ response; HBx effects were similar when expressed alone or in the context of replicating HBV. HBx elevation of the cytosolic Ca2+ level required extracellular Ca2+ influx and store-operated Ca2+ (SOC) entry and stimulated HBV replication in hepatocytes. We used both targeted RT-qPCR and transcriptome-wide RNAseq analyses to compare levels of SOC channel components and other Ca2+ signaling regulators in HBV-expressing and control hepatocytes and show that the transcript levels of these various proteins are not affected by HBV. We also show that HBx regulation of SOC-regulated Ca2+ accumulation is likely the consequence of HBV modulation of a SOC channel regulatory mechanism. In support of this, we link HBx enhancement of SOC-regulated Ca2+ accumulation to Ca2+ uptake by mitochondria and demonstrate that HBx stimulates mitochondrial Ca2+ uptake in primary hepatocytes. The results of our study may provide insights into viral mechanisms that affect Ca2+ signaling to regulate viral replication and virus-associated diseases.
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Affiliation(s)
- Jessica C. Casciano
- Program in Molecular and Cellular Biology and Genetics, Graduate School of Biomedical Sciences and Professional Studies, Drexel University College of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Nicholas J. Duchemin
- Program in Molecular and Cellular Biology and Genetics, Graduate School of Biomedical Sciences and Professional Studies, Drexel University College of Medicine, Philadelphia, Pennsylvania, United States of America
| | - R. Jason Lamontagne
- Program in Microbiology and Immunology, Graduate School of Biomedical Sciences and Professional Studies, Drexel University College of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Laura F. Steel
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Michael J. Bouchard
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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Oliveira AG, Andrade VA, Guimarães ES, Florentino RM, Sousa PA, Marques PE, Melo FM, Ortega MJ, Menezes GB, Leite MF. Calcium signalling from the type I inositol 1,4,5-trisphosphate receptor is required at early phase of liver regeneration. Liver Int 2015; 35:1162-71. [PMID: 24814243 DOI: 10.1111/liv.12587] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Accepted: 04/30/2014] [Indexed: 12/15/2022]
Abstract
BACKGROUND & AIMS Liver regeneration is a multistage process that unfolds gradually, with different mediators acting at different stages of regeneration. Calcium (Ca(2+) ) signalling is essential for liver regeneration. In hepatocytes, Ca(2+) signalling results from the activation of inositol 1,4,5-trisphosphate receptors (InsP3 R) of which two of the three known isoforms are expressed (InsP3 R-I and InsP3 R-II). Here, we investigated the role of the InsP3 R-I-dependent Ca(2+) signals in hepatic proliferation during liver regeneration. METHODS Partial hepatectomy (HX) in combination with knockdown of InsP3 R-I (AdsiRNA-I) was used to evaluate the role of InsP3 R-I on liver regeneration and hepatocyte proliferation, as assessed by liver to body mass ratio, PCNA expression, immunoblots and measurements of intracellular Ca(2+) signalling. RESULTS AdsiRNA-I efficiently infected the liver as demonstrated by the expression of β-galactosidase throughout the liver lobules. Moreover, this construct selectively and efficiently reduced the expression of InsP3 R-I, as evaluated by immunoblots. Expression of AdsiRNA-I in liver decreased peak Ca(2+) amplitude induced by vasopressin in isolated hepatocytes 2 days after HX. Reduced InsP3 R-I expression prior to HX also delayed liver regeneration, as measured by liver to body weight ratio, and reduced hepatocyte proliferation, as evaluated by PCNA staining, at the same time point. At later stages of regeneration, control hepatocytes showed a decreased expression of InsP3 R, as well as reduced InsP3 R-mediated Ca(2+) signalling, events that did not affect liver growth. CONCLUSION Together, these results show that InsP3 R-I-dependent Ca(2+) signalling is an early triggering pathway required for liver regeneration.
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Affiliation(s)
- André G Oliveira
- Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
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5
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Feriod CN, Nguyen L, Jurczak MJ, Kruglov EA, Nathanson MH, Shulman GI, Bennett AM, Ehrlich BE. Inositol 1,4,5-trisphosphate receptor type II (InsP3R-II) is reduced in obese mice, but metabolic homeostasis is preserved in mice lacking InsP3R-II. Am J Physiol Endocrinol Metab 2014; 307:E1057-64. [PMID: 25315698 PMCID: PMC4254986 DOI: 10.1152/ajpendo.00236.2014] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Inositol 1,4,5-trisphosphate receptor type II (InsP3R-II) is the most prevalent isoform of the InsP3R in hepatocytes and is concentrated under the canalicular membrane, where it plays an important role in bile secretion. We hypothesized that altered calcium (Ca(2+)) signaling may be involved in metabolic dysfunction, as InsP3R-mediated Ca(2+) signals have been implicated in the regulation of hepatic glucose homeostasis. Here, we find that InsP3R-II, but not InsP3R-I, is reduced in the livers of obese mice. In our investigation of the functional consequences of InsP3R-II deficiency, we found that organic anion secretion at the canalicular membrane and Ca(2+) signals were impaired. However, mice lacking InsP3R-II showed no deficits in energy balance, glucose production, glucose tolerance, or susceptibility to hepatic steatosis. Thus, our results suggest that reduced InsP3R-II expression is not sufficient to account for any disruptions in metabolic homeostasis that are observed in mouse models of obesity. We conclude that metabolic homeostasis is maintained independently of InsP3R-II. Loss of InsP3R-II does impair secretion of bile components; therefore, we suggest that conditions of obesity would lead to a decrease in this Ca(2+)-sensitive process.
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Affiliation(s)
- Colleen N Feriod
- Department of Cellular and Molecular Physiology, Yale University School of Medicine New Haven, Connecticut
| | - Lily Nguyen
- Department of Pharmacology, Yale University School of Medicine New Haven, Connecticut
| | - Michael J Jurczak
- Department of Internal Medicine, Yale University School of Medicine New Haven, Connecticut
| | - Emma A Kruglov
- Section of Digestive Diseases, Yale University School of Medicine New Haven, Connecticut
| | - Michael H Nathanson
- Section of Digestive Diseases, Yale University School of Medicine New Haven, Connecticut
| | - Gerald I Shulman
- Department of Cellular and Molecular Physiology, Yale University School of Medicine New Haven, Connecticut; Department of Internal Medicine, Yale University School of Medicine New Haven, Connecticut; Howard Hughes Medical Institute, Chevy Chase, Maryland
| | - Anton M Bennett
- Department of Pharmacology, Yale University School of Medicine New Haven, Connecticut; Program in Integrative Cell Signaling and Neurobiology of Metabolism, Yale University School of Medicine New Haven, Connecticut; and
| | - Barbara E Ehrlich
- Department of Cellular and Molecular Physiology, Yale University School of Medicine New Haven, Connecticut; Department of Pharmacology, Yale University School of Medicine New Haven, Connecticut;
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6
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Abstract
Intracellular free Ca(2+) ([Ca(2+)]i) is a highly versatile second messenger that regulates a wide range of functions in every type of cell and tissue. To achieve this versatility, the Ca(2+) signaling system operates in a variety of ways to regulate cellular processes that function over a wide dynamic range. This is particularly well exemplified for Ca(2+) signals in the liver, which modulate diverse and specialized functions such as bile secretion, glucose metabolism, cell proliferation, and apoptosis. These Ca(2+) signals are organized to control distinct cellular processes through tight spatial and temporal coordination of [Ca(2+)]i signals, both within and between cells. This article will review the machinery responsible for the formation of Ca(2+) signals in the liver, the types of subcellular, cellular, and intercellular signals that occur, the physiological role of Ca(2+) signaling in the liver, and the role of Ca(2+) signaling in liver disease.
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Affiliation(s)
- Maria Jimena Amaya
- Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
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7
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Mutti E, Magnaghi V, Veber D, Faroni A, Pece S, Di Fiore PP, Scalabrino G. Cobalamin deficiency-induced changes of epidermal growth factor (EGF)-receptor expression and EGF levels in rat spinal cord. Brain Res 2011; 1376:23-30. [DOI: 10.1016/j.brainres.2010.12.056] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Revised: 12/15/2010] [Accepted: 12/16/2010] [Indexed: 12/19/2022]
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8
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Abstract
The correct functioning of the liver is ensured by the setting and the maintenance of hepatocyte polarity. The complex polarity of the hepatocyte is characterized by the existence of several basolateral and apical poles per cell. Many in vitro models are available for studying hepatocyte polarity, but which are the more suitable? To answer this question, we aimed to identify criteria which determine the typical hepatocyte polarity. Therefore, we compiled a range of protein markers of membrane domains in rat hepatocytes and investigated their involvement in hepatocytic functions. Then, we focused on the relationship between hepatic functions and the cytoskeleton, Golgi apparatus and endoplasmic reticulum. Subsequently, we compared different cell lines expressing hepatocyte polarity. Finally, to demonstrate the usefulness of some of these lines, we presented new data on endoplasmic reticulum organization in relation to polarity.
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9
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Semela D, Piguet AC, Kolev M, Schmitter K, Hlushchuk R, Djonov V, Stoupis C, Dufour JF. Vascular remodeling and antitumoral effects of mTOR inhibition in a rat model of hepatocellular carcinoma. J Hepatol 2007; 46:840-8. [PMID: 17321636 DOI: 10.1016/j.jhep.2006.11.021] [Citation(s) in RCA: 167] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2006] [Revised: 09/26/2006] [Accepted: 11/02/2006] [Indexed: 12/11/2022]
Abstract
BACKGROUND/AIMS Hepatocellular carcinoma (HCC) is amenable to only few treatments. Inhibitors of the kinase mTOR are a new class of immunosuppressors already in use after liver transplantation. Their antiproliferative and antiangiogenic properties suggest that these drugs could be considered to treat HCC. We investigated the antitumoral effects of mTOR inhibition in a HCC model. METHODS Hepatoma cells were implanted into livers of syngeneic rats. Animals were treated with the mTOR inhibitor sirolimus for 4 weeks. Tumor growth was monitored by MR imaging. Antiangiogenic effects were assessed in vivo by microvessel density and corrosion casts and in vitro by cell proliferation, tube formation and aortic ring assays. RESULTS Treated rats had significantly longer survival and developed smaller tumors, fewer extrahepatic metastases and less ascites than controls. Sirolimus decreased intratumoral microvessel density resulting in extensive necrosis. Endothelial cell proliferation was inhibited at lower drug concentrations than hepatoma cells. Tube formation and vascular sprouting of aortic rings were significantly impaired by mTOR inhibition. Casts revealed that in tumors treated with sirolimus vascular sprouting was absent, whereas intussusception was observed. CONCLUSIONS mTOR inhibition significantly reduces HCC growth and improves survival primarily via antiangiogenic effects. Inhibitors of mTOR may have a role in HCC treatment.
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MESH Headings
- Angiogenesis Inhibitors/pharmacology
- Animals
- Antibiotics, Antineoplastic/pharmacology
- Capillaries/drug effects
- Carcinoma, Hepatocellular/blood supply
- Carcinoma, Hepatocellular/drug therapy
- Carcinoma, Hepatocellular/enzymology
- Cell Line, Tumor
- Cell Proliferation/drug effects
- Enzyme Inhibitors/pharmacology
- Liver Neoplasms, Experimental/blood supply
- Liver Neoplasms, Experimental/drug therapy
- Liver Neoplasms, Experimental/enzymology
- Neoplasm Transplantation
- Neovascularization, Pathologic/drug therapy
- Neovascularization, Pathologic/enzymology
- Phosphorylation/drug effects
- Protein Kinases/drug effects
- Protein Kinases/metabolism
- Rats
- Regional Blood Flow/drug effects
- Sirolimus/pharmacology
- TOR Serine-Threonine Kinases
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Affiliation(s)
- David Semela
- Institute of Clinical Pharmacology, University of Berne, Murtenstrasse 35, CH-3010 Berne, Switzerland
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10
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De Gottardi A, Biecker E, Koshy A, Bohler D, Shaw S, Sägesser H, Reichen J. Sensitivity to endothelin-1 is decreased in isolated livers of endothelial constitutive nitric oxide synthase knockout mice. COMPARATIVE HEPATOLOGY 2006; 5:9. [PMID: 17147823 PMCID: PMC1697821 DOI: 10.1186/1476-5926-5-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/06/2006] [Accepted: 12/05/2006] [Indexed: 11/10/2022]
Abstract
Background Hepatic sinusoidal resistance is regulated by vasoactive factors including endothelin-1 (ET-1) and nitric oxide (NO). In the absence of NO, vasoconstrictor response to endothelin is expected to predominate. Therefore, we hypothesized sensitivity to endothelin to be increased in mice lacking the endothelial cell NO synthase gene. Response of vascular resistance to endothelin was assessed in the in situ perfused liver of endothelial constitutive nitric oxide synthase (ecNOS) knockout and wild type mice. Livers were also harvested for RNA and protein isolation for quantitative PCR and Western blotting, respectively. The expression of endothelin receptors, isoenzymes of NO synthase, heme-oxygenase and adrenomedullin was quantified. Results Endothelin increased hepatic vascular resistance in a dose-dependent manner in both strains; however, this increase was significantly less in ecNOS knockout mice at physiologic concentrations. Expression of heme-oxygenases and adrenomedullin was similar in both groups, whereas inducible nitric oxide synthase (iNOS) protein was not detectable in either strain. mRNA levels of pre-pro-endothelin-1 and ETB receptor were comparable in both strains, while mRNA for ETA receptor was decreased in ecNOS knockouts. Conclusion Livers of ecNOS knockout mice have a decreased sensitivity to endothelin at physiologic concentrations; this is associated with a decreased expression of ETA receptors, but not with other factors, such as iNOS, ETB receptors, adrenomedullin or heme-oxygenase. Further studies targeting adaptive changes in ETA receptor distribution and/or intracellular signaling downstream of the receptor are indicated.
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Affiliation(s)
- Andrea De Gottardi
- Department of Clinical Pharmacology, University of Berne, Murtenstrasse 35, 3010 Berne, Switzerland
- Division of Gastroenterology and Hepatology, University Hospital of Geneva, Rue Micheli-du-Crest 24, 1211 Geneva 14, Switzerland
| | - Erwin Biecker
- Department of Clinical Pharmacology, University of Berne, Murtenstrasse 35, 3010 Berne, Switzerland
| | - Abraham Koshy
- Department of Clinical Pharmacology, University of Berne, Murtenstrasse 35, 3010 Berne, Switzerland
| | - Dieter Bohler
- Department of Clinical Pharmacology, University of Berne, Murtenstrasse 35, 3010 Berne, Switzerland
| | - Sidney Shaw
- Department of Clinical Pharmacology, University of Berne, Murtenstrasse 35, 3010 Berne, Switzerland
| | - Hans Sägesser
- Department of Clinical Pharmacology, University of Berne, Murtenstrasse 35, 3010 Berne, Switzerland
| | - Jürg Reichen
- Department of Clinical Pharmacology, University of Berne, Murtenstrasse 35, 3010 Berne, Switzerland
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11
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Abstract
BACKGROUND Cirrhosis is a gradually developing, chronic disease which involves the whole liver. Here, we have shown that CD38 undergoes altered expression upon thioacetamide-induced cirrhosis in rats. CD38 is a type II transmembrane glycoprotein that exhibits ADP-ribosyl cyclase and cADPR hydrolase activities. In this study, the gene and protein expressions of CD38 were investigated in a thioacetamide-induced rat model of cirrhosis. METHODS CD38 expression was studied by using real-time RT-PCR, immunohistochemistry, and immunoblotting. cADPR content in liver was measured using cycling assay. RESULTS There was a significant increase in CD38 mRNA and protein expressions as well as ADP-ribosyl cyclase activity in cirrhotic liver compared to the control liver. cADPR level was found to be modestly but significantly augmented in cirrhotic liver. CONCLUSIONS These results raised the possibility that altered CD38 expression and a concomitant elevation of the enzymatic activity as well as cADPR may be involved in the pathogenesis of liver cirrhosis.
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Affiliation(s)
- Bong Hwa Gan
- Department of Biochemistry, Faculty of Medicine, National University of Singapore, 8, Medical Drive, Singapore 117597, Singapore
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12
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Koshy A, De Gottardi A, Ledermann M, Saegesser H, Shaw SG, Zimmermann A, Reichen J. Endothelial nitric oxide synthase is not essential for the development of fibrosis and portal hypertension in bile duct ligated mice. Liver Int 2005; 25:1044-52. [PMID: 16162165 DOI: 10.1111/j.1478-3231.2005.01146.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
BACKGROUND/AIMS It is postulated that nitric oxide (NO) is responsible for the hyperdynamic circulation of portal hypertension. Therefore, we investigated induction of fibrosis and hyperdynamic circulation in endothelial NO synthase knock-out (KO) mice. METHODS Fibrosis was induced by bile duct ligation. Hemodynamic studies were performed after portal vein ligation. All studies were performed in wild-type (WT) and KO mice. RESULTS Three to 4 weeks after bile duct ligation (BDL), both WT and KO groups had similar degrees of portal hypertension, 12 (9-14) and 11(8-15) mmHg, median (range), and liver function. Fibrosis increased from 0.0% in sham operated to 1.0 and 1.1% in WT and KO mice, respectively. Cardiac output was similar after portal vein ligation (20 and 17 ml/min in WT and KO mice, respectively). There was no difference in liver of mRNA for endothelin 1, inducible NO synthase (iNOS) and hem-oxygenase 1 (HO1); proteins of iNOS, HO1 and HO2; nor in endothelin A and B (EtA and EtB) receptor density between WT and KO mice after BDL. CONCLUSIONS These results suggest that endothelial NO synthase is neither essential for the development of fibrosis and portal hypertension in bile duct ligated mice, nor for the hyperdynamic circulation associated with portal hypertension in the portal vein ligated mice.
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Affiliation(s)
- Abraham Koshy
- Institute for Clinical Pharmacology, University of Bern, Murtenstrasse 35, 3010 Bern, Switzerland
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13
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Mendes CCP, Gomes DA, Thompson M, Souto NC, Goes TS, Goes AM, Rodrigues MA, Gomez MV, Nathanson MH, Leite MF. The type III inositol 1,4,5-trisphosphate receptor preferentially transmits apoptotic Ca2+ signals into mitochondria. J Biol Chem 2005; 280:40892-900. [PMID: 16192275 DOI: 10.1074/jbc.m506623200] [Citation(s) in RCA: 225] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
There are three isoforms of the inositol 1,4,5- trisphosphate receptor (InsP(3)R), each of which has a distinct effect on Ca(2+) signaling. However, it is not known whether each isoform similarly plays a distinct role in the activation of Ca(2+)-mediated events. To investigate this question, we examined the effects of each InsP(3)R isoform on transmission of Ca(2+) signals to mitochondria and induction of apoptosis. Each isoform was selectively silenced using isoform-specific small interfering RNA in Chinese hamster ovary cells, which express all three InsP(3)R isoforms. ATP-induced cytosolic Ca(2+) signaling patterns were altered, regardless of which isoform was silenced, but in a different fashion depending on the isoform. ATP also induced Ca(2+) signals in mitochondria, which were inhibited more effectively by silencing the type III InsP(3)R than by silencing either the type I or type II isoform. The type III isoform also co-localized most strongly with mitochondria. When apoptosis was induced by activation of either the extrinsic or intrinsic apoptotic pathway, induction was reduced most effectively by silencing the type III InsP(3)R. These findings provide evidence that the type III isoform of the InsP(3)R plays a special role in induction of apoptosis by preferentially transmitting Ca(2+) signals into mitochondria.
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Affiliation(s)
- Carolina C P Mendes
- Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, MG, 31270-901, Brazil
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14
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Maya-Mendoza A, Hernández-Muñoz R, Gariglio P, Aranda-Anzaldo A. Gene positional changes relative to the nuclear substructure during carbon tetrachloride-induced hepatic fibrosis in rats. J Cell Biochem 2005; 93:1084-98. [PMID: 15449316 DOI: 10.1002/jcb.20264] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
In the interphase nucleus the DNA of higher eukaryotes is organized in loops anchored to a substructure known as the nuclear matrix (NM). The topological relationship between gene sequences located in the DNA loops and the NM appears to be very important for nuclear physiology because processes such as replication, transcription, and processing of primary transcripts occur at macromolecular complexes located at discrete sites upon the NM. Mammalian hepatocytes rarely divide but preserve a proliferating capacity that is displayed in vivo after specific stimulus. We have previously shown that transient changes in the relative position of specific genes to the NM occur during the process of liver regeneration after partial ablation of the liver, but also that such changes correlate with the replicating status of the cells. Moreover, since chronic exposure to carbon tetrachloride (CCl4) leads to bouts of hepatocyte damage and regeneration, and eventually to non-reversible liver fibrosis in the rat, we used this animal model in order to explore if genes that show differential activity in the liver change or modify their relative position to the NM during the process of liver fibrosis induction. We found that changes in the relative position of specific genes to the NM occur during the chronic administration of CCl4, but also that such changes correlate with the proliferating status of the hepatocytes that goes from quiescence to regeneration to replicative senescence along the course of CCl4-induced liver fibrosis, indicating that specific configurations in the higher-order DNA structure underlie the stages of progression towards liver fibrosis.
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Affiliation(s)
- Apolinar Maya-Mendoza
- Laboratorio de Biología Molecular, Facultad de Medicina, Universidad Autónoma del Estado de México, Apdo. Postal 428, C.P. 50000, Toluca, Edo. Méx., México
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15
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Pusl T, Nathanson MH. The role of inositol 1,4,5-trisphosphate receptors in the regulation of bile secretion in health and disease. Biochem Biophys Res Commun 2004; 322:1318-25. [PMID: 15336978 DOI: 10.1016/j.bbrc.2004.08.036] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2004] [Indexed: 01/05/2023]
Abstract
Ca2+ signaling via the inositol 1,4,5-trisphosphate receptor (InsP3R) is a ubiquitous mechanism for regulation of cell function, yet very little is known about the role of the InsP3R in specific disease states. Converging lines of evidence suggest that the liver may provide a model for the role of the InsP3R in health and disease. Ca2+ signaling is mediated entirely by the InsP3R in hepatocytes and cholangiocytes, the two types of epithelia in the liver. Here we review the role of specific InsP3R isoforms and the physiological effects of InsP3R-mediated Ca2+ signals in both of these types of epithelia. In addition, we review evidence that the InsP3R is lost from cholangiocytes in cholestatic forms of liver disease, and discuss this as a possible final common pathway for cholestasis.
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Affiliation(s)
- Thomas Pusl
- Department of Medicine II, Klinikum of the University of Munich-Grosshadern, 81377 Munich, Germany
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16
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Biecker E, Sägesser H, Reichen J. Vasodilator mRNA levels are increased in the livers of portal hypertensive NO-synthase 3-deficient mice. Eur J Clin Invest 2004; 34:283-9. [PMID: 15086360 DOI: 10.1111/j.1365-2362.2004.01331.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND/AIMS Nitric oxide synthase (NOS) 3-deficient (NOS-3 KO) mice have an increased systemic arterial pressure but develop portal hypertension to the same extent as wildtype (WT) mice. We hypothesized that other vasodilators in the portal circulation compensate for the lack in NOS-3 activity. We used quantitative PCR as a screening method to identify mediators that possibly compensate for NOS-3 in NOS-3 KO mice. METHODS Mean arterial pressure (MAP) and portal venous pressure (PVP) were measured in the anaesthetized animal. mRNA levels in whole liver tissue were determined by quantitative RT-PCR. RESULTS NOS-3 KO mice had a significantly higher mean arterial pressure than WT mice, but portal venous pressure did not differ. Bile duct ligation (BDL) induced a drop in MAP and a rise in PVP in both groups. Bile duct ligation induced a significant increase in mRNA levels of the cannabinoid receptor (CB)-1, adrenomedullin and NOS-2 in the liver of NOS-3 KO and WT mice. Nitric oxide synthase-1 and NOS-3 mRNA levels were elevated in BDL WT mice compared with sham-operated WT mice. Higher mRNA levels of CB-1, NOS-1 and the adrenomedullin receptor were found in sham-operated NOS-3 KO mice compared with sham-operated WT mice. CONCLUSIONS We used quantitative PCR as a screening method to identify vasodilative mediators that might be involved in the compensation for the lack of NOS-3 activity in NOS-3 KO mice. Elevated mRNA levels in sham-operated NOS-3 KO mice compared with sham-operated WT mice were demonstrated for CB-1, NOS-1 and the adrenomedullin receptor.
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Affiliation(s)
- E Biecker
- Department of Clinical Pharmacology, University of Berne, Berne, Switzerland.
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17
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Redaelli CA, Semela D, Carrick FE, Ledermann M, Candinas D, Sauter B, Dufour JF. Effect of vascular endothelial growth factor on functional recovery after hepatectomy in lean and obese mice. J Hepatol 2004; 40:305-12. [PMID: 14739103 DOI: 10.1016/j.jhep.2003.10.027] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
BACKGROUND/AIMS Liver regeneration is dependent upon coordinated proliferation of hepatocytes and endothelial cells. Vascular endothelial growth factor (VEGF) promotes angiogenesis. Hepatic steatosis delays regeneration and increases liver resection morbidity. We hypothesized that VEGF overexpression stimulates hepatic regeneration. METHODS Recombinant adenovirus expressing human VEGF165 or adenovirus control-vector (LacZ) were administered before 2/3 hepatectomy in lean and ob/ob mice. Galactose elimination capacity, a quantitative liver function test, was repeatedly measured before and after hepatectomy. Expression of VEGF receptors (flt1, flk1), endoglin and hypoxia inducible factor-1alpha (HIF-1alpha) was assessed by quantitative RT-PCR and for endoglin also by immunohistochemistry. RESULTS After 2/3 hepatectomy, VEGF gene transfer increased galactose elimination capacity in lean and ob/ob mice. HIF-1alpha, endoglin and VEGF receptor mRNA increased during regeneration in lean but not in obese mice. Staining of endothelial cells by endoglin immunohistochemistry returned to baseline reactivity in lean mice by day 6 and remained decreased in ob/ob mice. VEGF treatment decreased HIF-1alpha and increased flk1 response in lean mice. CONCLUSIONS Hepatic resection elicits an angiogenic response in the remnant liver, which is impaired in case of steatosis. Adenovirus-mediated transfer of VEGF hastens functional hepatic recovery in lean, and more importantly also, in obese mice after partial hepatectomy.
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Affiliation(s)
- Claudio A Redaelli
- Department of Visceral and Transplantation Surgery, Inselspital, University of Bern, Bern, Switzerland
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18
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Abstract
BACKGROUND & AIMS Cholestasis is one of the principal manifestations of liver disease and often results from disorders involving bile duct epithelia rather than hepatocytes. A range of disorders affects biliary epithelia, and no unifying pathophysiologic event in these cells has been identified as the cause of cholestasis. Here we examined the role of the inositol 1,4,5-trisphosphate receptor (InsP3R)/Ca(2+) release channel in Ca(2+) signaling and ductular secretion in animal models of cholestasis and in patients with cholestatic disorders. METHODS The expression and distribution of the InsP3R and related proteins were examined in rat cholangiocytes before and after bile duct ligation or treatment with endotoxin. Ca(2+) signaling was examined in isolated bile ducts from these animals, whereas ductular bicarbonate secretion was examined in isolated perfused livers. Confocal immunofluorescence was used to examine cholangiocyte InsP3R expression in human liver biopsy specimens. RESULTS Expression of the InsP3R was selectively lost from biliary epithelia after bile duct ligation or endotoxin treatment. As a result, Ca(2+) signaling and Ca(2+)-mediated bicarbonate secretion were lost as well, although other components of the Ca(2+) signaling pathway and adenosine 3',5'-cyclic monophosphate (cAMP)-mediated bicarbonate secretion both were preserved. Examination of human liver biopsy specimens showed that InsP3Rs also were lost from bile duct epithelia in a range of human cholestatic disorders, although InsP3R expression was intact in noncholestatic liver disease. CONCLUSIONS InsP3R-mediated Ca(2+) signaling in bile duct epithelia appears to be important for normal bile secretion in the liver, and loss of InsP3Rs may be a final common pathway for cholestasis.
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Affiliation(s)
- Juliette Martin
- Department of Clinical Pharmacology University of Bern Bern, Switzerland
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19
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Clair C, Tran D, Boucherie S, Claret M, Tordjmann T, Combettes L. Hormone receptor gradients supporting directional Ca2+ signals: direct evidence in rat hepatocytes. J Hepatol 2003; 39:489-95. [PMID: 12971956 DOI: 10.1016/s0168-8278(03)00289-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
BACKGROUND/AIMS In the liver, InsP(3)-dependent agonists such as vasopressin and noradrenaline induce tightly coordinated sequences of intracellular Ca(2+) increases, leading to apparent unidirectional Ca(2+) waves. In previous works, we have postulated that cell-to-cell differences in hormone receptor density create a cellular sensitivity gradient that determines which cell initiates the intercellular Ca(2+) wave and the direction of propagation of the Ca(2+) signal. The aim of this study was to test directly this hypothesis. METHODS Lobular distribution of V1a vasopressin receptors and alpha1 adrenergic receptors were observed by autoradiography in rat liver sections. Cell-to-cell differences in the number of these receptors were evaluated on hepatocyte multiplets using specific fluorescent probes. RESULTS The relative amount of fluorescence associated with the V1a receptor differed significantly between cells within multiplets. The 'cell-after-cell' Ca(2+) increase induced by vasopressin was correlated with the number of V1a receptors. These observations may be more general, as autoradiography revealed similar lobular distributions of V1a receptors and alpha1 adrenergic receptors; the amounts of both were greatest in hepatocytes surrounding central veins. CONCLUSIONS These data confirm that a fine gradient along liver cell plates contributes to the molecular basis of the unidirectional hormone-induced Ca(2+) signalling observed in the liver lobule.
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Affiliation(s)
- Caroline Clair
- Institut National de la Santé et de la Recherche Médicale Unité U442, Université de Paris-Sud, Bât 443, 91405 Orsay, France
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Colosetti P, Tunwell REA, Cruttwell C, Arsanto JP, Mauger JP, Cassio D. The type 3 inositol 1,4,5-trisphosphate receptor is concentrated at the tight junction level in polarized MDCK cells. J Cell Sci 2003; 116:2791-803. [PMID: 12759372 DOI: 10.1242/jcs.00482] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The subcellular localization of inositol 1,4,5-trisphosphate (InsP3)-induced Ca2+ signals is important for the activation of many physiological functions. In epithelial cells the spatial distribution of InsP3 receptor is restricted to specific areas, but little is known about the relationship between the receptor's distribution and cell polarity. To investigate this relationship, the best known polarized cell model, MDCK, was examined. This cell line is characterized by a strong expression of the type 3 InsP3 receptor and the subcellular localization of this receptor was followed during cell polarization using immunofluorescence and confocal analysis. In non-polarized cells, including ras transformed f3 MDCK cells, the type 3 InsP3 receptor was found to co-localize with markers of the endoplasmic reticulum in the cytoplasm. In contrast, in polarized cells, this receptor was mostly distributed at the apex of the lateral plasma membrane with the markers of tight junctions, ZO-1 and occludin. The localization of the type 3 InsP3 receptor in the vicinity of tight junctions was confirmed by immunogold electron microscopy. The culture of MDCK cells in calcium-deprived medium, led to disruption of cell polarity and receptor redistribution in the cytoplasm. Addition of calcium to these deprived cells induced the restoration of polarity and the relocalization of the receptor to the plasma membrane. MDCK cells were stably transfected with a plasmid coding the full-length mouse type 1 InsP3 receptor tagged with EGFP at the C-terminus. The EGFP-tagged type 1 receptor and the endogenous type 3 co-localized in the cytoplasm of non-polarized cells and at the tight junction level of polarized cells. Thus, the localization of InsP3 receptor in MDCK depends on polarity.
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Affiliation(s)
- Pascal Colosetti
- INSERM U-442, Signalisation cellulaire et calcium, Bât 443, Université Paris-Sud, 91405 Orsay Cedex, France
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21
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Bode HP, Wang L, Cassio D, Leite MF, St-Pierre MV, Hirata K, Okazaki K, Sears ML, Meda P, Nathanson MH, Dufour JF. Expression and regulation of gap junctions in rat cholangiocytes. Hepatology 2002; 36:631-40. [PMID: 12198655 DOI: 10.1053/jhep.2002.35274] [Citation(s) in RCA: 60] [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: 02/08/2023]
Abstract
Hepatocytes and other digestive epithelia exchange second messengers and coordinate their functions by communicating through gap junctions. However, little is known about intercellular communication in cholangiocytes. The aim of this study was to examine expression and regulation of gap junctions in cholangiocytes. Connexin expression was determined by confocal immunofluorescence in rat bile ducts and in normal rat cholangiocyte (NRC) cells, a polarized cholangiocyte cell line. Intercellular Ca(2+) signaling was monitored by fluorescent microscopy. Microinjection studies assessed regulation of gap junction permeability in NRC cells and in SKHep1 cells, a liver-derived cell line engineered to express connexin 43. Immunochemistry showed that cholangiocytes from normal rat liver as well as the NRC cells express connexin 43. Localization of apical, basolateral, and tight junction proteins confirmed that NRC cells are well polarized. Apical exposure to ATP induced Ca(2+) oscillations that were coordinated among neighboring NRC cells, and inhibition of gap junction conductance desynchronized the Ca(2+) oscillations. NRC cells transfected with a connexin 43 antisense were significantly less coupled. Transcellular dye spreading was inhibited by activation of protein kinase A or protein kinase C. The same was observed in transfected SKHep1 cells, which expressed only connexin 43. Rat cholangiocytes and NRC cells express connexin 43, which permits synchronization of Ca(2+) signals among cells. Permeability of connexin 43-gap junctions is negatively regulated by protein kinases A and C. In conclusion, cholangiocytes have the capacity for intercellular communication of second messenger signals via gap junctions in a fashion that is under hormonal control.
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Affiliation(s)
- Hans-Peter Bode
- Department of Gastroenterology, University of Bern, Bern, Switzerland
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22
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Hirata K, Dufour JF, Shibao K, Knickelbein R, O'Neill AF, Bode HP, Cassio D, St-Pierre MV, LaRusso NF, Leite MF, Nathanson MH. Regulation of Ca(2+) signaling in rat bile duct epithelia by inositol 1,4,5-trisphosphate receptor isoforms. Hepatology 2002; 36:284-96. [PMID: 12143036 PMCID: PMC2987686 DOI: 10.1053/jhep.2002.34432] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Cytosolic Ca(2+) (Ca(i)(2+)) regulates secretion of bicarbonate and other ions in the cholangiocyte. In other cell types, this second messenger acts through Ca(2+) waves, Ca(2+) oscillations, and other subcellular Ca(2+) signaling patterns, but little is known about the subcellular organization of Ca(2+) signaling in cholangiocytes. Therefore, we examined Ca(2+) signaling and the subcellular distribution of Ca(2+) release channels in cholangiocytes and in a model cholangiocyte cell line. The expression and subcellular distribution of inositol 1,4,5-trisphosphate (InsP(3)) receptor (InsP(3)R) isoforms and the ryanodine receptor (RyR) were determined in cholangiocytes from normal rat liver and in the normal rat cholangiocyte (NRC) polarized bile duct cell line. Subcellular Ca(2+) signaling in cholangiocytes was examined by confocal microscopy. All 3 InsP(3)R isoforms were expressed in cholangiocytes, whereas RyR was not expressed. The type III InsP(3)R was the most heavily expressed isoform at the protein level and was concentrated apically, whereas the type I and type II isoforms were expressed more uniformly. The type III InsP(3)R was expressed even more heavily in NRC cells but was concentrated apically in these cells as well. Adenosine triphosphate (ATP), which increases Ca(2+) via InsP(3) in cholangiocytes, induced Ca(2+) oscillations in both cholangiocytes and NRC cells. Acetylcholine (ACh) induced apical-to-basal Ca(2+) waves. In conclusion, Ca(2+) signaling in cholangiocytes occurs as polarized Ca(2+) waves that begin in the region of the type III InsP(3)R. Differential subcellular localization of InsP(3)R isoforms may be an important molecular mechanism for the formation of Ca(2+) waves and oscillations in cholangiocytes. Because Ca(i)(2+) is in part responsible for regulating ductular secretion, these findings also may have implications for the molecular basis of cholestatic disorders.
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Affiliation(s)
- Keiji Hirata
- Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
| | | | - Kazunori Shibao
- Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
| | - Roy Knickelbein
- Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
| | - Allison F. O'Neill
- Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
| | - Hans-Peter Bode
- Department of Gastroenterology, University of Bern, Bern, Switzerland
| | | | - Marie V. St-Pierre
- Department of Clinical Pharmacology, University of Zürich, Zürich, Switzerland
| | | | - M. Fatima Leite
- Department of Physiology and Biophysics, UFMG, Belo Horizonte, Brazil
| | - Michael H. Nathanson
- Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
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Leite MF, Hirata K, Pusl T, Burgstahler AD, Okazaki K, Ortega JM, Goes AM, Prado MAM, Spray DC, Nathanson MH. Molecular basis for pacemaker cells in epithelia. J Biol Chem 2002; 277:16313-23. [PMID: 11850419 DOI: 10.1074/jbc.m109207200] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Intercellular signaling is highly coordinated in excitable tissues such as heart, but the organization of intercellular signaling in epithelia is less clear. We examined Ca(2+) signaling in hepatoma cells expressing the hepatocyte gap junction protein connexin32 (cx32) or the cardiac gap junction protein cx43, plus a fluorescently tagged V(1a) vasopressin receptor (V(1a)R). Release of inositol 1,4,5-trisphosphate (InsP(3)) in wild type cells increased Ca(2+) in the injected cell but not in neighboring cells, while the Ca(2+) signal spread to neighbors when gap junctions were expressed. Photorelease of caged Ca(2+) rather than InsP(3) resulted in a small increase in Ca(2+) that did not spread to neighbors with or without gap junctions. However, photorelease of Ca(2+) in cells stimulated with low concentrations of vasopressin resulted in a much larger increase in Ca(2+), which spread to neighbors via gap junctions. Cells expressing tagged V(1a)R similarly had increased sensitivity to vasopressin, and could signal to neighbors via gap junctions. Higher concentrations of vasopressin elicited Ca(2+) signals in all cells. In cx32 or cx43 but not in wild type cells, this signaling was synchronized and began in cells expressing the tagged V(1a)R. Thus, intercellular Ca(2+) signals in epithelia are organized by three factors: 1) InsP(3) must be generated in each cell to support a Ca(2+) signal in that cell; 2) gap junctions are necessary to synchronize Ca(2+) signals among cells; and 3) cells with relatively increased expression of hormone receptor will initiate Ca(2+) signals and thus serve as pacemakers for their neighbors. Together, these factors may allow epithelia to act in an integrated, organ-level fashion rather than as a collection of isolated cells.
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Affiliation(s)
- M Fatima Leite
- Department of Physiology and Biophysics, Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte, Brazil
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Hirata K, Pusl T, O'Neill AF, Dranoff JA, Nathanson MH. The type II inositol 1,4,5-trisphosphate receptor can trigger Ca2+ waves in rat hepatocytes. Gastroenterology 2002; 122:1088-100. [PMID: 11910359 DOI: 10.1053/gast.2002.32363] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND & AIMS Ca2+ regulates cell functions through signaling patterns such as Ca2+ oscillations and Ca2+ waves. The type I inositol 1,4,5-trisphosphate receptor is thought to support Ca2+ oscillations, whereas the type III inositol 1,4,5-trisphosphate receptor is thought to initiate Ca2+ waves. The role of the type II inositol 1,4,5-trisphosphate receptor is less clear, because it behaves like the type III inositol 1,4,5-trisphosphate receptor at the single-channel level but can support Ca2+ oscillations in intact cells. Because the type II inositol 1,4,5-trisphosphate receptor is the predominant isoform in liver, we examined whether this isoform can trigger Ca2+ waves in hepatocytes. METHODS The expression and distribution of inositol 1,4,5-trisphosphate receptor isoforms was examined in rat liver by immunoblot and confocal immunofluorescence. The effects of inositol 1,4,5-trisphosphate on Ca2+ signaling were examined in isolated rat hepatocyte couplets by using flash photolysis and time-lapse confocal microscopy. RESULTS The type II inositol 1,4,5-trisphosphate receptor was concentrated near the canalicular pole in hepatocytes, whereas the type I inositol 1,4,5-trisphosphate receptor was found elsewhere. Stimulation of hepatocytes with vasopressin or directly with inositol 1,4,5-trisphosphate induced Ca2+ waves that began in the canalicular region and then spread to the rest of the cell. Inositol 1,4,5-Trisphosphate-induced Ca2+ signals also increased more rapidly in the canalicular region. Hepatocytes did not express the ryanodine receptor, and cyclic adenosine diphosphate-ribose had no effect on Ca2+ signaling in these cells. CONCLUSIONS The type II inositol 1,4,5-trisphosphate receptor establishes a pericanalicular trigger zone from which Ca2+ waves originate in hepatocytes.
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Affiliation(s)
- Keiji Hirata
- Department of Medicine, Yale University School of Medicine, New Haven, Connecticut 06520-8019, USA
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25
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Magnino F, Schmidt K, Mery L, Dufour JF. Rat inositol 1,4,5-trisphosphate receptor isoform 2 interacts with itself in its C-terminal portion and upstream of the first transmembrane domain. EUROPEAN JOURNAL OF BIOCHEMISTRY 2001; 268:5981-8. [PMID: 11722588 DOI: 10.1046/j.0014-2956.2001.02559.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In response to stimulation at the plasma membrane, hepatocellular Ca(2+) signals are fast and precise and lead to rapid local changes in cytoplasmic free Ca(2+) concentration. These changes result from the opening of the inositol 1,4,5-trisphosphate receptor (InsP(3)R), which is a four-subunit intracellular InsP(3)-gated channel that releases Ca(2+) from the stores. To investigate the molecular mechanism underlying interactions between the InsP(3)R subunits, we cloned the predominant hepatocellular isoform, InsP(3)R isoform 2 (InsP(3)R2), and screened for interactions using the yeast two-hybrid assay. We found that the C-terminal domain of rat InsP(3)R2 interacts with itself, and that the cytoplasmic part preceding the first transmembrane domain, a region near a Ca(2+)-binding site, also interacts with itself. These interactions were confirmed by pull-down experiments. The C-terminal domain of InsP(3)R2 is also able to interact with the C-termini of rat InsP(3)R1 and InsP(3)R3. These results advance our understanding of the molecular mechanisms that underlie the oligomerization and interactions of the InsP(3)R subunits during the opening/closing of the Ca(2+) channel.
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Affiliation(s)
- F Magnino
- Department of Clinical Pharmacology, University of Bern, Switzerland
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26
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Gersting JA, Bidasee KR, Besch HR. Determination of complement of mRNA encoding inositol 1,4,5-trisphosphate receptor isoforms in rat tissues using relative-polymerase chain reaction. Anal Biochem 2001; 294:188-90. [PMID: 11444817 DOI: 10.1006/abio.2001.5174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- J A Gersting
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, 635 Barnhill Drive, MS A417, Indianapolis, Indiana 46202-5120, USA
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Ezelle HJ, Balachandran S, Sicheri F, Polyak SJ, Barber GN. Analyzing the mechanisms of interferon-induced apoptosis using CrmA and hepatitis C virus NS5A. Virology 2001; 281:124-37. [PMID: 11222103 DOI: 10.1006/viro.2001.0815] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The dsRNA-dependent protein kinase, PKR, is a key component of interferon (IFN)-mediated anti-viral action and is frequently inhibited by many viruses following infection of the cell. Recently, we have demonstrated that IFN and PKR can sensitize cells to apoptosis predominantly through the FADD/caspase-8 pathway (S. Balachandran, P. C. Roberts, T. Kipperman, K. N. Bhalla, R. W. Compans, D. R. Archer, and G. N. Barber. (2000b) J. Virol. 74, 1513-1523). Given these findings, it is thus plausible that rather than specifically target IFN-inducible genes such as PKR, viruses could also subvert the mechanisms of IFN action, in part, at locations that could block the apoptotic cascade. To explore this possibility, we analyzed whether the poxvirus caspase-8 inhibitor, CrmA, was able to inhibit IFN or PKR/dsRNA-mediated apoptosis. Our findings indicated that CrmA could indeed inhibit apoptosis induced by both viral infection and dsRNA without blocking PKR activity or inhibiting IFN signaling. In contrast HCV-encoded NS5A, a putative inhibitor of PKR, did not appear to inhibit cell death mediated by a number of apoptotic stimuli, including IFN, TRAIL, and etoposide. Our data imply that viral-encoded inhibitors of apoptosis, such as CrmA, can block the innate arms of the immune response, including IFN-mediated apoptosis, and therefore potentially constitute an alternative family of inhibitors of IFN action in the cell.
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Affiliation(s)
- H J Ezelle
- Department of Microbiology and Immunology, University of Miami School of Medicine, Miami, Florida 33136, USA
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Lang C, Schäfer M, Serra D, Hegardt FG, Krähenbühl L, Krähenbühl S. Impaired hepatic fatty acid oxidation in rats with short-term cholestasis: characterization and mechanism. J Lipid Res 2001. [DOI: 10.1016/s0022-2275(20)32332-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Boehning D, Joseph SK. Functional properties of recombinant type I and type III inositol 1, 4,5-trisphosphate receptor isoforms expressed in COS-7 cells. J Biol Chem 2000; 275:21492-9. [PMID: 10764774 DOI: 10.1074/jbc.m001724200] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Inositol 1,4,5-trisphosphate receptors (IP(3)Rs) are ubiquitous intracellular Ca(2+) release channels whose functional characterization by transfection has proved difficult due to the background contribution of endogenous channels. In order to develop a functional assay to measure recombinant channels, we transiently transfected the rat type I IP(3)R into COS-7 cells. Saponin-permeabilized COS cells transfected with type I IP(3)R showed a 50% increase in inositol 1,4,5-trisphosphate (IP(3))-mediated Ca(2+) release at saturating [IP(3)] (10 micrometer) but no enhancement at subsaturating [IP(3)] (300 nm). However, cotransfection of the IP(3)R and human sarco/endoplasmic reticulum ATPase (SERCA)-2b ATPase cDNA resulted in 60 and 110% increases in Ca(2+) release at subsaturating and saturating doses of IP(3), respectively. IP(3) or adenophostin A failed to release (45)Ca(2+) from microsomal vesicles prepared from cells expressing either type I IP(3)R or SERCA cDNAs alone. However, microsomal vesicles prepared from cells doubly transfected with IP(3)R and SERCA cDNAs released 33.0 +/- 0.04% of the A23187-sensitive pool within 30 s of 1 micrometer adenophostin A addition. Similarly, the initial rate of (45)Ca(2+) influx into oxalate-loaded microsomal vesicles was inhibited by IP(3) only when the microsomes were prepared from COS cells doubly transfected with SERCA-2b and IP(3)R DNA. The absence of a functional contribution from endogenous IP(3)Rs has enabled the use of this assay to measure the Ca(2+) sensitivities of IP(3)-mediated (45)Ca(2+) fluxes through recombinant neuronal type I (SII(+)), peripheral type I (SII(-)), and type III IP(3)Rs. All three channels displayed a biphasic dependence upon [Ca(2+)](cyt). Introduction of mutations D2550A and D2550N in the putative pore-forming region of the type I IP(3)R inhibited IP(3)-mediated (45)Ca(2+) fluxes, whereas the conservative substitution D2550E was without effect. This assay therefore provides a useful tool for studying the regulatory properties of individual IP(3)R isoforms as well as for screening pore mutations prior to more detailed electrophysiological analyses.
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MESH Headings
- Adenosine/analogs & derivatives
- Adenosine/pharmacology
- Amino Acid Substitution
- Animals
- COS Cells
- Calcimycin/pharmacology
- Calcium/metabolism
- Calcium Channels/drug effects
- Calcium Channels/genetics
- Calcium Channels/metabolism
- Calcium-Transporting ATPases/genetics
- Calcium-Transporting ATPases/metabolism
- Cell Membrane Permeability
- Humans
- Inositol 1,4,5-Trisphosphate/metabolism
- Inositol 1,4,5-Trisphosphate/pharmacology
- Inositol 1,4,5-Trisphosphate Receptors
- Kinetics
- Microsomes/drug effects
- Microsomes/metabolism
- Mutagenesis, Site-Directed
- Neurons/physiology
- Protein Isoforms/drug effects
- Protein Isoforms/genetics
- Protein Isoforms/metabolism
- Rats
- Receptors, Cytoplasmic and Nuclear/drug effects
- Receptors, Cytoplasmic and Nuclear/genetics
- Receptors, Cytoplasmic and Nuclear/metabolism
- Recombinant Proteins/metabolism
- Transfection
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Affiliation(s)
- D Boehning
- Department of Pathology and Cell Biology, Thomas Jefferson University School of Medicine, Philadelphia, Pennsylvania 19107, USA
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Magnino F, St-Pierre M, Lüthi M, Hilly M, Mauger JP, Dufour JF. Expression of intracellular calcium channels and pumps after partial hepatectomy in rat. MOLECULAR CELL BIOLOGY RESEARCH COMMUNICATIONS : MCBRC 2000; 3:374-9. [PMID: 11032760 DOI: 10.1006/mcbr.2000.0242] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ca(2+) signals regulate many cellular functions, including proliferation. They are governed by the inositol 1,4,5-trisphosphate receptor (IP(3)R), the only intracellular hepatic Ca(2+) channel and by the endoplasmic reticulum Ca(2+) pumps, SERCA. To characterise their role in regeneration, expression of their isoforms was studied after 2/3 hepatectomy by real-time quantitative PCR, Western blot and binding studies. We found an early increase in the expression of the IP(3)R isoform 1 which contrasted with the decrease of the expression of the IP(3)R isoforms 2 and 3 and of SERCA3. This results in a transient switch between IP(3)R isoforms 1 and 2, IP(3)R isoform 1 becoming predominant before the first round of mitosis. Binding studies detected a 30% diminution of the IP(3)R population at 24 h. In conclusion, the Ca(2+) signalling machinery is regulated, after hepatectomy, by changes in expression of the IP(3)R and SERCA isoforms to adapt Ca(2+) signals to the regenerative state.
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Affiliation(s)
- F Magnino
- Department of Clinical Pharmacology, University of Bern, Bern, Switzerland
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