1
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Ennequin G, Caillaud K, Chavanelle V, Teixeira A, Etienne M, Li X, Boisseau N, Sirvent P. Neuregulin 1 treatment improves glucose tolerance in diabetic db/db mice, but not in healthy mice. Arch Physiol Biochem 2020; 126:320-325. [PMID: 30449185 DOI: 10.1080/13813455.2018.1534243] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Context: Neuregulin 1 (NRG1) and ErbB receptors are involved in glucose homeostasis. However, the effects of the neuregulin 1-ErbB pathway activation on glucose metabolism in liver are controversial.Objective: Assess NRG1 and ErbB signalling in liver and the effects of 8-week treatment with NRG1 on glucose homeostasis in diabetic db/db mice and in control healthy mice.Results: NRG1 improved glucose, insulin and insulin sensitivity index during OGTT in db/db mice, but not in control mice. Compared with healthy mice, phosphorylation of p38, ErbB-1 and ErbB-3 was increased in diabetic mice, and neuregulin 1 treatment increased phosphorylation of p38 and ErbB-4. Conversely, the AKT/FOXO1 pathway was not affected by the 8-week treatment with NRG1.Conclusion: Diabetic mice showed altered NRG1-ErbB pathway in the liver compared with healthy mice. Moreover, chronic NRG1 treatment increased p38 phosphorylation in liver and improved glucose tolerance in diabetic mice, but not in control mice.
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Affiliation(s)
- Gaël Ennequin
- Clermont Auvergne University, EA 3533, Laboratory of the Metabolic Adaptations to Exercise under Physiological and Pathological Conditions (AME2P), Clermont-Ferrand, France
- PEPITE EA4267, and Exercise Performance Health Innovation Platform Univ. Bourgogne Franche-Comté, Besançon, France
| | - Kevin Caillaud
- Clermont Auvergne University, EA 3533, Laboratory of the Metabolic Adaptations to Exercise under Physiological and Pathological Conditions (AME2P), Clermont-Ferrand, France
| | - Vivien Chavanelle
- Clermont Auvergne University, EA 3533, Laboratory of the Metabolic Adaptations to Exercise under Physiological and Pathological Conditions (AME2P), Clermont-Ferrand, France
| | - Allison Teixeira
- Clermont Auvergne University, EA 3533, Laboratory of the Metabolic Adaptations to Exercise under Physiological and Pathological Conditions (AME2P), Clermont-Ferrand, France
| | - Monique Etienne
- Clermont Auvergne University, EA 3533, Laboratory of the Metabolic Adaptations to Exercise under Physiological and Pathological Conditions (AME2P), Clermont-Ferrand, France
| | - Xinyan Li
- Zensun Sci & Tech Ltd, Shanghai, China
| | - Nathalie Boisseau
- Clermont Auvergne University, EA 3533, Laboratory of the Metabolic Adaptations to Exercise under Physiological and Pathological Conditions (AME2P), Clermont-Ferrand, France
| | - Pascal Sirvent
- Clermont Auvergne University, EA 3533, Laboratory of the Metabolic Adaptations to Exercise under Physiological and Pathological Conditions (AME2P), Clermont-Ferrand, France
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Abstract
Neuregulin-1 (NRG1) has been shown to be associated with the regulation of inflammation and ovulation. The aim of this study was to investigate the relationship between serum NRG1 levels and various clinical and metabolic parameters in women with polycystic ovary syndrome (PCOS). This case-controlled study included 38 women with PCOS and 46 age and body mass index (BMI)-matched controls without PCOS. The serum NRG1 levels of the women with PCOS were found to be significantly lower compared to the control group. The high sensitivity C-reactive protein (hs-CRP) levels of the PCOS subjects were significantly higher than in the control group. The circulating NRG1 levels were negatively correlated with a homeostasis model assessment of insulin resistance (HOMA-IR) and the hs-CRP in the PCOS group. There is no significant correlation between the circulating NRG1 levels and the serum insulin in the PCOS group. There was a trend toward high NRG1 levels in the PCOS subjects with high BMI, but the difference failed to reach a statistical significance. Decreased NRG1 levels in PCOS subjects may be associated with insulin resistance and a low-grade chronic inflammation. Impact statement What is already known on this subject? Although there have been many studies related to NRG1, we could not find any study explaining the relationship between NRG1 and PCOS. This study provides first and novel insights into the relationship between serum NRG1 levels and the insulin resistance in women with PCOS. What do the results of this study add? A decline in the NRG1 levels in PCOS may be associated with insulin resistance and a low-grade chronic inflammation. What are the implications of these findings for clinical practice and/or further research? Decreased NRG1 levels may play an important role in the reproductive and endocrine properties of PCOS. We think that NRG1 research may be contribute to the clarification of PCOS pathophysiology. Future research investigating NRG1 levels in obese and non-obese cases, as well as in ovulatory and anovulatory PCOS patients, will make a significant contribution to the resolution of the mystery under PCOS aetiology.
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Affiliation(s)
- Haldun Arpacı
- a Department of Obstetrics and Gynecology, School of Medicine , Kafkas University , Kars , Turkey
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3
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Scheving LA, Zhang X, Threadgill DW, Russell WE. Hepatocyte ERBB3 and EGFR are required for maximal CCl4-induced liver fibrosis. Am J Physiol Gastrointest Liver Physiol 2016; 311:G807-G816. [PMID: 27586651 PMCID: PMC5130544 DOI: 10.1152/ajpgi.00423.2015] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 08/18/2016] [Indexed: 01/31/2023]
Abstract
Epidermal growth factor receptor (EGFR) and its ligands have been implicated in liver fibrosis. However, it has not been directly shown that hepatocellular genetic ablation of either this receptor tyrosine kinase or ERBB3, its interactive signaling partner, affects hepatic fibrosis. Carbon tetrachloride (CCl4)-induced liver fibrosis in hepatocyte-specific (HS) mouse models of EGFR and ERBB3 ablation was evaluated in both single gene knockouts and an HS-EGFR-ERBB3 double knockout (DKO). Loss of hepatocellular EGFR or ERBB3 did not impact cytochrome P450-2E1 expression, the extent of centrilobular injury, or the initial regenerative response, but it did diminish liver fibrosis induced by chronic intraperitoneal administration of CCl4 The reduction of liver fibrosis correlated with reduced α-smooth muscle actin expression. Maximal impact to fibrogenesis occurred in the ERBB3 and EGFR-ERBB3 DKO models, suggesting that EGFR-ERBB3 heterodimeric signaling in damaged hepatocytes may play a more important role in liver fibrosis than EGFR-EGFR homodimeric signaling. Immunohistochemical analyses of phospho-EGFR and phospho-ERBB3 isoforms revealed clear staining in hepatocytes, activated stellate cells, and macrophages. Our results support a role for the hepatocellular ERBB tyrosine kinases in fibrogenesis and suggest that pharmacologic inhibition of EGFR-ERBB3 signaling may reverse or retard hepatic fibrosis.
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Affiliation(s)
- Lawrence A. Scheving
- 1Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee;
| | - Xiuqi Zhang
- 1Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee;
| | - David W. Threadgill
- 6Department of Veterinary Pathobiology, Texas A&M University, College Station, Texas; and ,7Department of Molecular and Cellular Medicine, Texas A&M University, College Station, Texas
| | - William E. Russell
- 1Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee; ,2Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee; ,3Digestive Disease Research Center, Vanderbilt University Medical Center, Nashville, Tennessee; ,4Vanderbilt Diabetes Center, Vanderbilt University Medical Center, Nashville, Tennessee; ,5Vanderbilt Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee;
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4
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Caillaud K, Boisseau N, Ennequin G, Chavanelle V, Etienne M, Li X, Denis P, Dardevet D, Lacampagne A, Sirvent P. Neuregulin 1 improves glucose tolerance in adult and old rats. DIABETES & METABOLISM 2016; 42:96-104. [DOI: 10.1016/j.diabet.2015.08.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 07/30/2015] [Accepted: 08/19/2015] [Indexed: 12/29/2022]
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5
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López-Soldado I, Niisuke K, Veiga C, Adrover A, Manzano A, Martínez-Redondo V, Camps M, Bartrons R, Zorzano A, Gumà A. Neuregulin improves response to glucose tolerance test in control and diabetic rats. Am J Physiol Endocrinol Metab 2016; 310:E440-51. [PMID: 26714846 DOI: 10.1152/ajpendo.00226.2015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 12/20/2015] [Indexed: 12/31/2022]
Abstract
Neuregulin (NRG) is an EGF-related growth factor that binds to the tyrosine kinase receptors ErbB3 and ErbB4, thus inducing tissue development and muscle glucose utilization during contraction. Here, we analyzed whether NRG has systemic effects regulating glycemia in control and type 2 diabetic rats. To this end, recombinant NRG (rNRG) was injected into Zucker diabetic fatty (ZDF) rats and their respective lean littermates 15 min before a glucose tolerance test (GTT) was performed. rNRG enhanced glucose tolerance without promoting the activation of the insulin receptor (IR) or insulin receptor substrates (IRS) in muscle and liver. However, in control rats, rNRG induced the phosphorylation of protein kinase B (PKB) and glycogen synthase kinase-3 (GSK-3) in liver but not in muscle. In liver, rNRG increased ErbB3 tyrosine phosphorylation and its binding to phosphatidylinositol 3-kinase (PI3K), thus indicating that rNRG activates the ErbB3/PI3K/PKB signaling pathway. rNRG increased glycogen content in liver but not in muscle. rNRG also increased the content of fructose-2,6-bisphosphate (Fru-2,6-P2), an activator of hepatic glycolysis, and lactate in liver but not in muscle. Increases in lactate were abrogated by wortmannin, a PI3K inhibitor, in incubated hepatocytes. The liver of ZDF rats showed a reduced content of ErbB3 receptors, entailing a minor stimulation of the rNRG-induced PKB/GSK-3 cascade and resulting in unaltered hepatic glycogen content. Nonetheless, rNRG increased hepatic Fru-2,6-P2 and augmented lactate both in liver and in plasma of diabetic rats. As a whole, rNRG improved response to the GTT in both control and diabetic rats by enhancing hepatic glucose utilization.
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Affiliation(s)
- Iliana López-Soldado
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Barcelona, Barcelona, Spain; Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain; Center for Biomedical Investigation in Net of Diabetes and Associated Metabolic Pathologies, Madrid, Spain
| | - Katrin Niisuke
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Barcelona, Barcelona, Spain
| | - Catarina Veiga
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Barcelona, Barcelona, Spain
| | - Anna Adrover
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Anna Manzano
- Department of Physiological Sciences II, Faculty of Medicine, University of Barcelona-IDIBELL: Bellvitge Institute for Biomedical Research, Barcelona, Spain; and
| | - Vicente Martínez-Redondo
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Barcelona, Barcelona, Spain
| | - Marta Camps
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Barcelona, Barcelona, Spain; Center for Biomedical Investigation in Net of Diabetes and Associated Metabolic Pathologies, Madrid, Spain; Institute of Biomedicine from the University of Barcelona, Barcelona, Spain
| | - Ramon Bartrons
- Department of Physiological Sciences II, Faculty of Medicine, University of Barcelona-IDIBELL: Bellvitge Institute for Biomedical Research, Barcelona, Spain; and
| | - Antonio Zorzano
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Barcelona, Barcelona, Spain; Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain; Center for Biomedical Investigation in Net of Diabetes and Associated Metabolic Pathologies, Madrid, Spain
| | - Anna Gumà
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Barcelona, Barcelona, Spain; Center for Biomedical Investigation in Net of Diabetes and Associated Metabolic Pathologies, Madrid, Spain; Institute of Biomedicine from the University of Barcelona, Barcelona, Spain
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6
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Ennequin G, Boisseau N, Caillaud K, Chavanelle V, Etienne M, Li X, Sirvent P. Neuregulin 1 Improves Glucose Tolerance in db/db Mice. PLoS One 2015; 10:e0130568. [PMID: 26230680 PMCID: PMC4521942 DOI: 10.1371/journal.pone.0130568] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Accepted: 05/21/2015] [Indexed: 01/14/2023] Open
Abstract
In vitro experiments using rodent skeletal muscle cells suggest that neuregulin 1 (NRG1) is involved in glucose metabolism regulation, although no study has evaluated the role of NRG1 in systemic glucose homeostasis. The purpose of this study was to investigate the effect of chronic and acute NRG1 treatment on glucose homeostasis in db/db mice. To this aim, glucose tolerance tests were performed in 8-week-old male db/db mice after treatment with NRG1 (50μg.kg-1) or saline 3 times per week for 8 weeks. In other experiments, glucose tolerance and pyruvate tolerance tests were performed in db/db mice 15 minutes after a single NRG1 (50μg.kg-1) or saline injection. Liver, adipose tissue, hypothalamus and skeletal muscle were also collected 30 minutes after acute NRG1 (50μg.kg-1) or saline treatment, and the phosphorylation status of the ERBB receptors, AKT (on Ser473) and FOXO1 (on Ser256) was assessed by western blotting. Chronic treatment (8 weeks) with NRG1 improved glucose tolerance in db/db mice. Acute treatment also lowered glycemia and insulinemia during glucose or pyruvate tolerance tests. NRG1 acute injection induced activation of ERBB3 receptors and phosphorylation of AKT and FOXO1 only in liver. Altogether, this study shows that acute and chronic NRG1 treatments improve glucose tolerance in db/db mice. This effect could be mediated through inhibition of hepatic gluconeogenesis.
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Affiliation(s)
- Gaël Ennequin
- Université Clermont Auvergne, Université Blaise Pascal, EA 3533, Laboratoire des Adaptations Métaboliques à l’Exercice en Conditions Physiologiques et Pathologiques (AME2P), BP 80026, F-63171, Aubière Cedex, France
- CRNH-Auvergne, Clermont-Ferrand, F-63001, France
| | - Nathalie Boisseau
- Université Clermont Auvergne, Université Blaise Pascal, EA 3533, Laboratoire des Adaptations Métaboliques à l’Exercice en Conditions Physiologiques et Pathologiques (AME2P), BP 80026, F-63171, Aubière Cedex, France
- CRNH-Auvergne, Clermont-Ferrand, F-63001, France
| | - Kevin Caillaud
- Université Clermont Auvergne, Université Blaise Pascal, EA 3533, Laboratoire des Adaptations Métaboliques à l’Exercice en Conditions Physiologiques et Pathologiques (AME2P), BP 80026, F-63171, Aubière Cedex, France
- CRNH-Auvergne, Clermont-Ferrand, F-63001, France
| | - Vivien Chavanelle
- Université Clermont Auvergne, Université Blaise Pascal, EA 3533, Laboratoire des Adaptations Métaboliques à l’Exercice en Conditions Physiologiques et Pathologiques (AME2P), BP 80026, F-63171, Aubière Cedex, France
- CRNH-Auvergne, Clermont-Ferrand, F-63001, France
| | - Monique Etienne
- Université Clermont Auvergne, Université Blaise Pascal, EA 3533, Laboratoire des Adaptations Métaboliques à l’Exercice en Conditions Physiologiques et Pathologiques (AME2P), BP 80026, F-63171, Aubière Cedex, France
- CRNH-Auvergne, Clermont-Ferrand, F-63001, France
| | - Xinyan Li
- Zensun Sci & Tech Ltd., Shanghai, China
| | - Pascal Sirvent
- Université Clermont Auvergne, Université Blaise Pascal, EA 3533, Laboratoire des Adaptations Métaboliques à l’Exercice en Conditions Physiologiques et Pathologiques (AME2P), BP 80026, F-63171, Aubière Cedex, France
- CRNH-Auvergne, Clermont-Ferrand, F-63001, France
- * E-mail:
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7
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Scheving LA, Zhang X, Stevenson MC, Threadgill DW, Russell WE. Loss of hepatocyte EGFR has no effect alone but exacerbates carbon tetrachloride-induced liver injury and impairs regeneration in hepatocyte Met-deficient mice. Am J Physiol Gastrointest Liver Physiol 2015; 308:G364-77. [PMID: 25414100 PMCID: PMC4346751 DOI: 10.1152/ajpgi.00364.2014] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The role(s) of the epidermal growth factor receptor (EGFR) in hepatocytes is unknown. We generated a murine hepatocyte specific-EGFR knockout (KO) model to evaluate how loss of hepatocellular EGFR expression affects processes such as EGF clearance, circulating EGF concentrations, and liver regeneration following 70% resection or CCl4-induced centrilobular injury. We were able to disrupt EGFR expression effectively in hepatocytes and showed that the ability of EGF and heregulin (HRG) to phosphorylate EGFR and ERBB3, respectively, required EGFR. Loss of hepatocellular EGFR impaired clearance of exogenous EGF from the portal circulation but paradoxically resulted in reduced circulating levels of endogenous EGF. This was associated with decreased submandibular salivary gland production of EGF. EGFR disruption did not result in increased expression of other ERBB proteins or Met, except in neonatal mice. Liver regeneration following 70% hepatectomy revealed a mild phenotype, with no change in cyclin D1 expression and slight differences in cyclin A expression compared with controls. Peak 5-bromo-2'-deoxyuridine labeling was shifted from 36 to 48 h. Centrilobular damage and regenerative response induced by carbon tetrachloride (CCl4) were identical in the KO and wild-type mice. In contrast, loss of Met increased CCl4-induced necrosis and delayed regeneration. Although loss of hepatocellular EGFR alone did not have an effect in this model, EGFR-Met double KOs displayed enhanced necrosis and delayed liver regeneration compared with Met KOs alone. This suggests that EGFR and Met may partially compensate for the loss of the other, although other compensatory mechanisms can be envisioned.
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Affiliation(s)
- Lawrence A. Scheving
- 1Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee; ,3Digestive Disease Research Center, Vanderbilt University Medical Center, Nashville, Tennessee;
| | - Xiuqi Zhang
- 1Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee;
| | - Mary C. Stevenson
- 1Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee;
| | - David W. Threadgill
- 6Department of Veterinary Pathobiology, Texas A&M University, College Station, Texas; and ,7Department of Molecular and Cellular Medicine, Texas A&M University, College Station, Texas
| | - William E. Russell
- 1Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee; ,2Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee; ,3Digestive Disease Research Center, Vanderbilt University Medical Center, Nashville, Tennessee; ,4Vanderbilt Diabetes Center, Vanderbilt University Medical Center, Nashville, Tennessee; ,5Vanderbilt Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee;
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8
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Scheving LA, Zhang X, Garcia OA, Wang RF, Stevenson MC, Threadgill DW, Russell WE. Epidermal growth factor receptor plays a role in the regulation of liver and plasma lipid levels in adult male mice. Am J Physiol Gastrointest Liver Physiol 2014; 306:G370-81. [PMID: 24407590 PMCID: PMC3949019 DOI: 10.1152/ajpgi.00116.2013] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Dsk5 mice have a gain of function in the epidermal growth factor receptor (EGFR), caused by a point mutation in the kinase domain. We analyzed the effect of this mutation on liver size, histology, and composition. We found that the livers of 12-wk-old male Dsk5 heterozygotes (+/Dsk5) were 62% heavier compared with those of wild-type controls (+/+). The livers of the +/Dsk5 mice compared with +/+ mice had larger hepatocytes with prominent, polyploid nuclei and showed modestly increased cell proliferation indices in both hepatocytes and nonparenchymal cells. An analysis of total protein, DNA, and RNA (expressed relative to liver weight) revealed no differences between the mutant and wild-type mice. However, the livers of the +/Dsk5 mice had more cholesterol but less phospholipid and fatty acid. Circulating cholesterol levels were twice as high in adult male +/Dsk5 mice but not in postweaned young male or female mice. The elevated total plasma cholesterol resulted mainly from an increase in low-density lipoprotein (LDL). The +/Dsk5 adult mouse liver expressed markedly reduced protein levels of LDL receptor, no change in proprotein convertase subtilisin/kexin type 9, and a markedly increased fatty acid synthase and 3-hydroxy-3-methyl-glutaryl-CoA reductase. Increased expression of transcription factors associated with enhanced cholesterol synthesis was also observed. Together, these findings suggest that the EGFR may play a regulatory role in hepatocyte proliferation and lipid metabolism in adult male mice, explaining why elevated levels of EGF or EGF-like peptides have been positively correlated to increased cholesterol levels in human studies.
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Affiliation(s)
| | | | | | | | | | - David W. Threadgill
- 6Department of Genetics, North Carolina State University, Raleigh, North Carolina
| | - William E. Russell
- 1Departments of Pediatrics, ,2Cell and Developmental Biology, ,3Digestive Disease Research Center, ,4Vanderbilt Diabetes Center, ,5Vanderbilt Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee;
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9
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Cervelli V, Scioli MG, Gentile P, Doldo E, Bonanno E, Spagnoli LG, Orlandi A. Platelet-rich plasma greatly potentiates insulin-induced adipogenic differentiation of human adipose-derived stem cells through a serine/threonine kinase Akt-dependent mechanism and promotes clinical fat graft maintenance. Stem Cells Transl Med 2012. [PMID: 23197780 DOI: 10.5966/sctm.2011-0052] [Citation(s) in RCA: 122] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The potential plasticity and therapeutic utility in tissue regeneration of human adipose-derived stem cells (ASCs) isolated from adult adipose tissue have recently been highlighted. The use of autologous platelet-rich plasma (PRP) represents an alternative strategy in regenerative medicine for the local release of multiple endogenous growth factors. Here we investigated the signaling pathways and effects of PRP and human recombinant insulin on proliferation and adipogenic differentiation of ASCs in vitro. PRP stimulated proliferation (EC(50) = 15.3 ± 1.3% vol/vol), whereas insulin's effect was the opposite (IC(50) = 3.0 ± 0.5 μM). Although PRP alone did not increase adipogenesis, in association with insulin it prevented ASC proliferative arrest, greatly enhanced intracytoplasmic lipid accumulation, strongly increased serine/threonine kinase Akt phosphorylation and mouse monoclonal anti-sterol regulatory element binding protein-1 accumulation, and downregulated Erk-1 activity; adipogenic effects were markedly prevented by the Akt inhibitor wortmannin. PRP with insulin synergistically upregulated fibroblast growth factor receptor (FGFR) and downregulated epidermal growth factor receptor (ErbB) expression; moreover, PRP in association prevented insulin-induced insulin-like growth factor-1 receptor and insulin receptor downregulation. The inhibition of FGFR-1, epidermal growth factor receptor (EGFR), and epidermal growth factor receptor-2 (ErbB2) activity reduced ASC proliferation, but only that of FGFR-1 reduced adipogenesis and Akt phosphorylation, whereas the ErbB2 inhibition effects were the opposite. However, EGFR activity was needed for ErbB2-mediated inhibition of ASC adipogenesis. Clinically, the injection of insulin further ameliorated patients' 1-year PRP-induced fat graft volume maintenance and contour restoring. Our results ascertain that PRP in association with insulin greatly potentiates adipogenesis in human ASCs through a FGFR-1 and ErbB2-regulated Akt mechanism. The ameliorated clinical fat graft maintenance suggests additional useful translational applications of combined PRP-insulin treatment in regenerative medicine.
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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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11
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Hsieh SY, He JR, Hsu CY, Chen WJ, Bera R, Lin KY, Shih TC, Yu MC, Lin YJ, Chang CJ, Weng WH, Huang SF. Neuregulin/erythroblastic leukemia viral oncogene homolog 3 autocrine loop contributes to invasion and early recurrence of human hepatoma. Hepatology 2011; 53:504-16. [PMID: 21246584 DOI: 10.1002/hep.24083] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2010] [Accepted: 11/09/2010] [Indexed: 12/22/2022]
Abstract
UNLABELLED Intrahepatic metastasis is the primary cause of the high recurrence and poor prognosis of human hepatocellular carcinoma (HCC). However, neither its molecular mechanisms nor markers for its prediction before hepatectomy have been identified. We recently revealed up-regulation of erythroblastic leukemia viral oncogene homolog 3 (ERBB3) in human HCC. Here we examined the clinical and biological significance of ERBB3 in HCC. Up-regulation of ERBB3 in HCC was strongly associated with male gender (P < 0.001), chronic hepatitis B (P = 0.002), microscopic vascular invasion (P = 0.034), early recurrence (P = 0.003), and worse prognosis (P = 0.004). Phosphorylated ERBB3 and its ligands [neuregulins (NRGs)] were detected in both HCC tissues and cells. Phosphorylation of ERBB3 could be induced by conditioned media of HCC cells and abolished by the pretreatment of conditioned media with anti-NRG antibodies or by the silencing of the endogenous NRG expression of the donor HCC cells. Human epidermal growth factor receptor 2 was required for ERBB3 phosphorylation. The downstream phosphoinositide 3-kinase/v-akt murine thymoma viral oncogene homolog pathways were primarily elicited by NRG1/ERBB3 signaling, whereas the mitogen-activated protein kinase/extracellular signal-regulated kinase pathways were elicited by both epidermal growth factor/epidermal growth factor receptor and NRG1/ERBB3 signaling. The activation and silencing of ERBB3-dependent signaling had potent effects on both the migration and invasion of HCC cells, but neither had significant effects on the proliferation of HCC cells, tumor formation, or tumor growth in vitro and in vivo. CONCLUSION The constitutive activation of ERBB3-dependent signaling via the NRG1/ERBB3 autocrine loop plays a crucial role in the regulation of cell motility and invasion, which contribute to intrahepatic metastasis and early recurrence of HCC. ERBB3 is a marker for the prediction of intrahepatic metastasis and early recurrence. ERBB3-dependent signaling is a candidate target for the treatment of microscopic vascular invasion and for the prevention of HCC recurrence.
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Affiliation(s)
- Sen-Yung Hsieh
- Liver Research Unit, Chang Gung Memorial Hospital, Taoyuan, Taiwan.
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Gupte RS, Floyd BC, Kozicky M, George S, Ungvari ZI, Neito V, Wolin MS, Gupte SA. Synergistic activation of glucose-6-phosphate dehydrogenase and NAD(P)H oxidase by Src kinase elevates superoxide in type 2 diabetic, Zucker fa/fa, rat liver. Free Radic Biol Med 2009; 47:219-28. [PMID: 19230846 PMCID: PMC2700195 DOI: 10.1016/j.freeradbiomed.2009.01.028] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2008] [Revised: 01/02/2009] [Accepted: 01/18/2009] [Indexed: 10/21/2022]
Abstract
Glucose metabolism through the glycolysis and hexosamine pathway has been shown to be altered in type 2 diabetes. However, the fate of glucose through the pentose phosphate pathway (PPP) is currently unclear. In this study, we determined whether the activity of glucose-6-phosphate dehydrogenase (G6PD), the rate-limiting enzyme in the PPP, is modulated in the liver of Zucker obese fa/fa rats (9-11 weeks of age). We found that G6PD expression and activity, NADPH levels, and 6-phosphogluconate generation were significantly increased in the liver of fa/fa rats. Inhibition of PI3 kinase and Src kinases decreased (p < 0.05) G6PD activity in the fa/fa but not in the lean rat liver, suggesting that G6PD activity is regulated by PI3/Src kinase signaling pathways. G6PD-derived NADPH increased (p < 0.05) superoxide anion levels by 70-90% in fa/fa vs lean rat liver, which was inhibited by the NADPH oxidase inhibitor gp91(ds-tat) (50 microM) and G6PD inhibitors 6-aminonicotinamide (1 mM) and dehydroepiandrosterone (100 microM), therefore indicating that elevated G6PD activity may be responsible for mediating superoxide generation. Interestingly, we also found a positive correlation between liver hypertrophy/increased G6PD activity (r2 = 0.77; p = 0.0009) and liver hypertrophy/superoxide production (r2 = 0.51; p = 0.0091) in fa/fa rats. Increased G6PD and NADPH oxidase expression and activity, in young hyperglycemic and hyperinsulinemic rats before the development of diabetes, seems to be a contributing factor in the induction of oxidative stress. Because inhibition of G6PD activity decreases oxidative stress, we conclude that G6PD behaves as a pro-oxidant in the fa/fa rat liver in type 2 diabetes.
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Affiliation(s)
- Rakhee S. Gupte
- Department of Biochemistry & Molecular Biology, University of South Alabama, Mobile, AL 36688
- Department of Physiology, New York Medical College, Valhalla, NY 10595
| | - Beverly C. Floyd
- Department of Physiology, New York Medical College, Valhalla, NY 10595
| | - Mark Kozicky
- Department of Physiology, New York Medical College, Valhalla, NY 10595
| | - Shimran George
- Department of Physiology, New York Medical College, Valhalla, NY 10595
| | - Zoltan I. Ungvari
- Department of Physiology, New York Medical College, Valhalla, NY 10595
| | - Vanessa Neito
- Department of Physiology, New York Medical College, Valhalla, NY 10595
| | - Michael S. Wolin
- Department of Physiology, New York Medical College, Valhalla, NY 10595
| | - Sachin A Gupte
- Department of Biochemistry & Molecular Biology, University of South Alabama, Mobile, AL 36688
- Department of Physiology, New York Medical College, Valhalla, NY 10595
- Address Correspondence to: Sachin A Gupte, MD, PhD, Department of Biochemistry & Molecular Biology, University of South Alabama, College of Medicine, 307 University Blvd N., Mobile, AL 36688, USA, Tel: (251) 460-6402; Fax: (251) 460-6850,
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Scheving LA, Stevenson MC, Zhang X, Russell WE. Cultured rat hepatocytes upregulate Akt and ERK in an ErbB-2-dependent manner. Am J Physiol Gastrointest Liver Physiol 2008; 295:G322-31. [PMID: 18535289 PMCID: PMC2519852 DOI: 10.1152/ajpgi.00597.2007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Epidermal growth factor (EGF) stimulates freshly plated adult hepatocytes to synthesize DNA, but only after they pass through a lag phase of 40 h following EGF exposure. The longer the cells are maintained, they become more responsive to EGF and the lag phase shortens. Maximal EGF-mediated stimulation of DNA synthesis requires the induction of ErbB2, which is not normally expressed in adult hepatocytes. We used immunological methods to demonstrate increased expression during culture of two gene families required for EGF to stimulate hepatocyte DNA synthesis: Akt and ERK 1/2. Both families showed hyperexpression in culture particularly when cells were exposed to insulin and EGF. Unlike CDK-2 and cyclin D1, integral mediators of the G1/S phase transition, ERK 1/2 and Akt appeared in the absence of EGF, particularly when insulin was present. This hyperexpression, which high concentrations of dexamethasone reversed, increased basal and growth factor-stimulated phosphorylation of Akt and ERK 1/2. Pharmacological blockade of phosphatidylinositol kinase suppressed the Akt increase whereas pharmacological blockade or small interfering RNA downregulation of ErbB2 inhibited both Akt and ERK 1/2 expression. All three Akt isoforms contributed to the increase in total Akt. EGF but not insulin specifically upregulated Akt 2 and 3. Since Akt and ERK 1/2 are also hyperexpressed in poorly differentiated hepatomas, their dysregulation in cancer may involve transcriptional mechanisms normally operative in cultured hepatocytes. We hypothesize that the induction and activation of ErbB2 increases the expression of these kinases, enhancing the responsiveness of hepatocytes to EGF as they adapt to culture.
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Affiliation(s)
- Lawrence A. Scheving
- Departments of Pediatrics, Division of Endocrinology and Cell and Developmental Biology, the Digestive Disease Research Center, the Vanderbilt Diabetes Center, and the Vanderbilt Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Mary C. Stevenson
- Departments of Pediatrics, Division of Endocrinology and Cell and Developmental Biology, the Digestive Disease Research Center, the Vanderbilt Diabetes Center, and the Vanderbilt Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Xiuqi Zhang
- Departments of Pediatrics, Division of Endocrinology and Cell and Developmental Biology, the Digestive Disease Research Center, the Vanderbilt Diabetes Center, and the Vanderbilt Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee
| | - William E. Russell
- Departments of Pediatrics, Division of Endocrinology and Cell and Developmental Biology, the Digestive Disease Research Center, the Vanderbilt Diabetes Center, and the Vanderbilt Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee
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14
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Sithanandam G, Anderson LM. The ERBB3 receptor in cancer and cancer gene therapy. Cancer Gene Ther 2008; 15:413-48. [PMID: 18404164 DOI: 10.1038/cgt.2008.15] [Citation(s) in RCA: 180] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
ERBB3, a member of the epidermal growth factor receptor (EGFR) family, is unique in that its tyrosine kinase domain is functionally defective. It is activated by neuregulins, by other ERBB and nonERBB receptors as well as by other kinases, and by novel mechanisms. Downstream it interacts prominently with the phosphoinositol 3-kinase/AKT survival/mitogenic pathway, but also with GRB, SHC, SRC, ABL, rasGAP, SYK and the transcription regulator EBP1. There are likely important but poorly understood roles for nuclear localization and for secreted isoforms. Studies of ERBB3 expression in primary cancers and of its mechanistic contributions in cultured cells have implicated it, with varying degrees of certainty, with causation or sustenance of cancers of the breast, ovary, prostate, certain brain cells, retina, melanocytes, colon, pancreas, stomach, oral cavity and lung. Recent results link high ERBB3 activity with escape from therapy targeting other ERBBs in lung and breast cancers. Thus a wide and centrally important role for ERBB3 in cancer is becoming increasingly apparent. Several approaches for targeting ERBB3 in cancers have been tested or proposed. Small inhibitory RNA (siRNA) to ERBB3 or AKT is showing promise as a therapeutic approach to treatment of lung adenocarcinoma.
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15
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Scheving LA, Buchanan R, Krause MA, Zhang X, Stevenson MC, Russell WE. Dexamethasone modulates ErbB tyrosine kinase expression and signaling through multiple and redundant mechanisms in cultured rat hepatocytes. Am J Physiol Gastrointest Liver Physiol 2007; 293:G552-9. [PMID: 17585012 DOI: 10.1152/ajpgi.00140.2007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Glucocorticoids paradoxically exert both stimulatory and inhibitory effects on the proliferation of cultured rat hepatocytes. We studied the effects of dexamethasone, a synthetic glucocorticoid, on the proliferation of cultured rat hepatocytes. The timing of growth factor addition modified the action of high-dose dexamethasone (10(-6) M) on DNA synthesis. When we added transforming growth factor-alpha at the time of plating, 10(-6) M dexamethasone weakly stimulated DNA synthesis by 26% relative to cells cultured in dexamethasone-free media. When we delayed growth factor addition until 24-48 h after plating, 10(-6) M dexamethasone inhibited DNA synthesis by 50%. Using immunological methods, we analyzed the expression and signaling patterns of the ErbB kinases in dexamethasone-treated cells. High-dose dexamethasone stabilized the expression of epidermal growth factor receptor (EGFr) and ErbB3, and it suppressed the de novo expression of ErbB2 that occurs during the third and fourth day of culture in 10(-8) M dexamethasone. High-dose dexamethasone by 72 h suppressed basal and EGF-associated phosphorylation of ERK and Akt. The reduction in ERK1/2 phosphorylation correlated with suppression of a culture-dependent increase in Son-of sevenless 1 (Sos1) and ERK1/2 expression. High-dose dexamethasone in hepatocytes stabilized or upregulated several inhibitory effectors of EGFr/ErbB2 and ERK, including receptor-associated late transducer (RALT) and MKP-1, respectively. Thus 10(-6) M dexamethasone exerts a time-dependent and redundant inhibitory effect on EGFr-mediated proliferative signaling in hepatocytes, targeting not only the ErbB proteins but also their various positive and negative effectors.
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Affiliation(s)
- Lawrence A Scheving
- Division of Pediatric Endocrinology, 1055 Medical Research Bldg. 4, Vanderbilt University Medical Center, Nashville, TN 37232-0710, USA.
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Dorsey WC, Tchounwou PB, Ford BD. Neuregulin 1-Beta cytoprotective role in AML 12 mouse hepatocytes exposed to pentachlorophenol. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2007; 3:11-22. [PMID: 16823072 PMCID: PMC3785675 DOI: 10.3390/ijerph2006030002] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Neuregulins are a family of growth factor domain proteins that are structurally related to the epidermal growth factor. Accumulating evidence has shown that neuregulins have cyto- and neuroprotective properties in various cell types. In particular, the neuregulin-1 Beta (NRG1-Beta) isoform is well documented for its antiinflammatory properties in rat brain after acute stroke episodes. Pentachlorophenol (PCP) is an organochlorine compound that has been widely used as a biocide in several industrial, agricultural, and domestic applications. Previous investigations from our laboratory have demonstrated that PCP exerts both cytotoxic and mitogenic effects in human liver carcinoma (HepG2) cells, primary catfish hepatocytes and AML 12 mouse hepatocytes. We have also shown that in HepG2 cells, PCP has the ability to induce stress genes that may play a role in the molecular events leading to toxicity and tumorigenesis. In the present study, we hypothesize that NRG1-Beta will exert its cytoprotective effects in PCP-treated AML 12 mouse hepatocytes by its ability to suppress the toxic effects of PCP. To test this hypothesis, we performed the MTT-cell respiration assay to assess cell viability, and Western-blot analysis to assess stress-related proteins as a consequence of PCP exposure. Data obtained from 48 h-viability studies demonstrated a biphasic response; showing a dose-dependent increase in cell viability within the range of 0 to 3.87 microg/mL, and a gradual decrease within the concentration range of 7.75 to 31.0 microg/mL in concomitant treatments of NRG1-Beta+PCP and PCP. Cell viability percentages indicated that NRG1-Beta+PCPtreated cells were not significantly impaired, while PCP-treated cells were appreciably affected; suggesting that NRG1-Beta has the ability to suppress the toxic effects of PCP. Western Blot analysis demonstrated the potential of PCP to induce oxidative stress and inflammatory response (c-fos), growth arrest and DNA damage (GADD153), proteotoxic effects (HSP70), cell cycle arrest as consequence of DNA damage (p53), mitogenic response (cyclin- D1), and apoptosis (caspase-3). NRG1-Beta exposure attenuated stress-related protein expression in PCP-treated AML 12 mouse hepatocytes. Here we provide clear evidence that NRG1-Beta exerts cytoprotective effects in AML 12 mouse hepatocytes exposed to PCP.
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Affiliation(s)
- Waneene C. Dorsey
- Molecular Toxicology Research Laboratory, Grambling State University, Grambling, LA,
USA
| | - Paul B. Tchounwou
- Molecular Toxicology Research Laboratory, NIH-Center for Environmental Health, College of Science, Engineering, and Technology, Jackson State University, Jackson, MS,
USA
- Correspondence to Dr. Paul B. Tchounwou.
| | - Byron D. Ford
- Department of Anatomy and Neurobiology, Morehouse School of Medicine, Atlanta, GA,
USA
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17
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Scheving LA, Zhang L, Stevenson MC, Kwak ES, Russell WE. The emergence of ErbB2 expression in cultured rat hepatocytes correlates with enhanced and diversified EGF-mediated signaling. Am J Physiol Gastrointest Liver Physiol 2006; 291:G16-25. [PMID: 16769812 DOI: 10.1152/ajpgi.00328.2005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The proliferative effects of EGF in liver have been extensively investigated in cultured hepatocytes. We studied the effects of EGF, insulin, and other growth regulators on the expression, interaction, and signaling of ErbB receptors in primary cultures of adult rat hepatocytes. Using immunological methods and ErbB tyrosine kinase inhibitors, we analyzed the expression and signaling patterns of the ErbB kinases over 120 h of culture. Basal and EGF-stimulated protein tyrosine phosphorylation increased as cells adapted in vitro. EGF receptor (EGFr) expression declined in the first 24 h, whereas ErbB3 expression rose. Although ErbB2 was not present in freshly isolated hepatocytes, EGF and insulin independently induced ErbB2 while suppressing ErbB3 expression. Low concentrations of EGF and insulin synergistically stimulated ErbB2 expression and DNA synthesis. The greatest increase in ErbB2, which is normally expressed by fetal and neonatal hepatocytes, occurred shortly before the onset of DNA synthesis (> 40 h). EGF promoted EGFr and ErbB2 coassociation, stimulating tyrosine phosphorylation of both proteins. In contrast, heregulin beta1 (HRG-beta1) did not promote ErbB2 and ErbB3 coassociation. A selective tyrphostin inhibitor of ErbB2 suppressed EGF-stimulated DNA synthesis, but maximum suppression required the blockade of the EGFr kinase as well. Maximal EGF stimulation of DNA synthesis in vitro depends on the induction of ErbB2 and involves an EGFr-ErbB2 heterodimer. The ability of insulin to induce ErbB2 suggests both a mechanism for the synergy between insulin and EGF and a possible metabolic control of ErbB2 in vivo.
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Affiliation(s)
- Lawrence A Scheving
- Division of Endocrinology, Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232-0710, USA.
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18
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Neo SY, Leow CK, Vega VB, Long PM, Islam AFM, Lai PBS, Liu ET, Ren EC. Identification of discriminators of hepatoma by gene expression profiling using a minimal dataset approach. Hepatology 2004; 39:944-53. [PMID: 15057898 DOI: 10.1002/hep.20105] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The severity of hepatocellular carcinoma (HCC) and the lack of good diagnostic markers and treatment strategies have rendered the disease a major challenge. Previous microarray analyses of HCC were restricted to the selected tissue sample sets without validation on an independent series of tissue samples. We describe an approach to the identification of a composite discriminator cassette by intersecting different microarray datasets. We studied the global transcriptional profiles of matched HCC tumor and nontumor liver samples from 37 patients using cDNA (cDNA) microarrays. Application of nonparametric Wilcoxon statistical analyses (P < 1 x 10(-6)) and the criteria of 1.5-fold differential gene expression change resulted in the identification of 218 genes, including BMI-1, ERBB3, and those involved in the ubiquitin-proteasome pathway. Elevated ERBB2 and epidermal growth factor receptor (EGFR) expression levels were detected in ERBB3-expressing tumors, suggesting the presence of ERBB3 cognate partners. Comparison of our dataset with an earlier study of approximately 150 tissue sets identified multiple overlapping discriminator markers, suggesting good concordance of data despite differences in patient populations and technology platforms. These overlapping discriminator markers could distinguish HCC tumor from nontumor liver samples with reasonable precision and the features were unlikely to appear by chance, as measured by Monte Carlo simulations. More significantly, validation of the discriminator cassettes on an independent set of 58 liver biopsy specimens yielded greater than 93% prediction accuracy. In conclusion, these data indicate the robustness of expression profiling in marker discovery using limited patient tissue specimens as well as identify novel genes that are highly likely to be excellent markers for HCC diagnosis and treatment.
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Carver RS, Stevenson MC, Scheving LA, Russell WE. Diverse expression of ErbB receptor proteins during rat liver development and regeneration. Gastroenterology 2002; 123:2017-27. [PMID: 12454858 DOI: 10.1053/gast.2002.37060] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
BACKGROUND & AIMS The protein expression and interactions of the ErbB receptors were examined in different liver proliferation models in vivo and in vitro, including ontogeny and regeneration following partial hepatectomy. METHODS Expression and tyrosine phosphorylation status of specific ErbB proteins were studied by immunologic methods. RESULTS The epidermal growth factor receptor, ErbB2, and ErbB3 were the only ErbB proteins detected in the liver parenchyma on embryonic day 19. ErbB2 disappeared by the third week after birth and could not be appreciably induced in the adult animal by partial hepatectomy. ErbB2 was also detected in multipotent stem (RLE) and hepatoma (H4IIe) cell lines as well as in fetal, but not adult, hepatocyte cultures. Only epidermal growth factor receptor and ErbB3 were detected in adult liver, and both showed circadian variation in protein expression. ErbB4 was not detected in any model. Patterns of ligand-induced ErbB phosphorylation differed between fetal and adult hepatocytes. CONCLUSIONS Complex and independent programs regulate the ErbB receptors, with implications for differential cell signaling in hepatic development and regeneration.
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Affiliation(s)
- Robert S Carver
- Department of Cell Biology, the Digestive Disease Research Center, Nashville, Tennessee, USA
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20
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Insights into the pathobiology of hepatitis C virus-associated cirrhosis: analysis of intrahepatic differential gene expression. THE AMERICAN JOURNAL OF PATHOLOGY 2002; 160:641-54. [PMID: 11839585 PMCID: PMC1850631 DOI: 10.1016/s0002-9440(10)64884-5] [Citation(s) in RCA: 142] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The pathogenesis of hepatitis C virus (HCV)-associated liver injury involves many genes from multiple pathogenic pathways. cDNA array analysis, which examines the expression of many genes simultaneously, was used to achieve new insights into HCV liver injury. Membrane-based cDNA arrays of 874 genes compared HCV-associated cirrhosis with autoimmune hepatitis-associated cirrhosis as an inflammatory and cirrhotic control, and with nondiseased liver tissue. Array analysis identified many differentially expressed genes that are important in inflammation, fibrosis, proliferation, signaling, apoptosis, and oxidative stress. Genes up-regulated in HCV-associated cirrhosis were predominantly associated with a Th1 immune response, fibrosis, cellular proliferation, and apoptosis. Novel observations of differential gene expression included increased expression of secreted apoptosis-related protein 3, a Wnt pathway gene possibly involved in cellular apoptosis. EMMPRIN (CD147) and discoidin domain receptor 1 (CD167) were also shown to be increased and are likely to play a role in liver fibrosis. Real-time quantitative reverse transcriptase-polymerase chain reaction confirmed the increased expression of 15 genes. The comparison of HCV cirrhosis with autoimmune hepatitis cirrhosis showed a marked difference in the apoptosis-associated gene profile with HCV cirrhosis characterized by increased proapoptotic gene expression whereas autoimmune hepatitis was characterized by increased expression of both antiapoptotic and proapoptotic genes. Furthermore, expression of beta-catenin and the fibrosis-associated protein EMMPRIN were localized by immunohistochemistry to the plasma membranes of hepatocytes and biliary epithelium. In conclusion, HCV-associated cirrhosis was characterized by a proinflammatory, profibrotic, and proapoptotic gene expression profile.
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21
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Scheving LA, Stevenson MC, Taylormoore JM, Traxler P, Russell WE. Integral role of the EGF receptor in HGF-mediated hepatocyte proliferation. Biochem Biophys Res Commun 2002; 290:197-203. [PMID: 11779153 DOI: 10.1006/bbrc.2001.6157] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Hepatocyte growth factor (HGF), insulin, and TGF-alpha stimulate DNA synthesis in cultured hepatocytes. Each ligand activates a distinct tyrosine kinase receptor, although receptor cross-talk modulates signaling. In rat hepatocytes, HGF can stimulate TGF-alpha production while TGF-alpha antibodies or antisense oligonucleotides suppress HGF-stimulated DNA synthesis. We report that the epidermal growth factor receptor (EGFR) kinase inhibitor PKI166 blocked both basal and ligand-induced tyrosine phosphorylation of the EGFR (IC(50) = 60 nM), but not of the insulin receptor or c-met. Pharmacologic inhibition of the EGFR kinase abolished the proliferative actions of HGF and EGF, but not insulin, whereas PI-3 kinase inhibition blocked both EGF and insulin actions. We conclude that in cultured hepatocytes (i) PI-3 kinase is required for EGF- and insulin-induced proliferation and (ii) EGFR mediates both the basal rate of DNA synthesis and that induced by EGF and HGF, but not insulin. The mitogenic effect of HGF may be secondary to increased synthesis or processing of EGFR ligands such as TGF-alpha.
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Affiliation(s)
- Lawrence A Scheving
- Department of Pediatrics, Medical Center, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
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22
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Scheving LA, Russell WE. Insulin and heregulin-beta1 upregulate guanylyl cyclase C expression in rat hepatocytes: reversal by phosphodiesterase-3 inhibition. Cell Signal 2001; 13:665-72. [PMID: 11495724 DOI: 10.1016/s0898-6568(01)00179-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Guanylyl cyclase C (GC-C) is the receptor for the hormones guanylin and uroguanylin. Although primarily expressed in the rat intestine, GC-C is also expressed in the liver during neonatal or regenerative growth or during the acute phase response. Little is known about the hepatic regulation of GC-C expression. The influence of various hepatic growth or acute phase regulators on GC-C expression was evaluated by immunoblot analysis of protein from primary rat hepatocytes grown in a serum-free medium. Insulin and heregulin-beta1 strongly stimulated GC-C expression by 24 h of cell culture. Several different hormones and agents suppressed this action, including transforming growth factor beta (TGF-beta), as well as inhibitors of phosphatidylinositol 3-kinase (PI-3-kinase) and phosphodiesterase 3 (PDE-3, an insulin- and PI-3-kinase-dependent enzyme). The compartmental downregulation of cAMP levels by PDE-3 may be a critical step in the hormonal action that culminates in GC-C synthesis.
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Affiliation(s)
- L A Scheving
- Division of Pediatric Gastroenterology and Nutrition, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
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23
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Kong M, Mounier C, Wu J, Posner BI. Epidermal growth factor-induced phosphatidylinositol 3-kinase activation and DNA synthesis. Identification of Grb2-associated binder 2 as the major mediator in rat hepatocytes. J Biol Chem 2000; 275:36035-42. [PMID: 10973965 DOI: 10.1074/jbc.m005621200] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In previous work we showed that the phosphatidylinositol 3-kinase (PI3-kinase), not the mitogen-activated protein kinase, pathway is necessary and sufficient to account for insulin- and epidermal growth factor (EGF)-induced DNA synthesis in rat hepatocytes. Here, using a dominant-negative p85, we confirmed the key role of EGF-induced PI3-kinase activation and sought to identify the mechanism by which this is effected. Our results show that EGF activates PI3-kinase with a time course similar to that of the association of p85 with three principal phosphotyrosine proteins (i. e. PY180, PY105, and PY52). We demonstrated that each formed a distinct p85-associated complex. PY180 and PY52 each constituted about 10% of EGF-activated PI3-kinase, whereas PY105 was responsible for 80%. PY105 associated with Grb2 and SHP-2, and although it behaved like Gab1, none of the latter was detected in rat liver. We therefore cloned a cDNA from rat liver, which was found to be 95% homologous to the mouse Grb2-associated binder 2 (Gab2) cDNA sequence. Using a specific Gab2 antibody, we demonstrated its expression in and association with p85, SHP-2, and Grb2 upon EGF treatment of rat hepatocytes. Gab2 accounted for most if not all of the PY105 species, since immunoprecipitation of Gab2 with specific antibodies demonstrated parallel immunodepletion of Gab2 and PY105 from the residual supernatants. We also found that the PI3-kinase activity associated with Gab2 was totally abolished by dominant negative p85. Thus, Gab2 appears to be the principal EGF-induced PY protein recruiting and activating PI3-kinase and mitogenesis.
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Affiliation(s)
- M Kong
- Polypeptide Hormone Laboratory, Faculty of Medicine, McGill University, Montreal, Quebec H3A 2B2, Canada
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24
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Noguchi H, Sakamoto C, Wada K, Akamatsu T, Uchida T, Tatsuguchi A, Matsui H, Fukui H, Fujimori T, Kasuga M. Expression of heregulin alpha, erbB2, and erbB3 and their influences on proliferation of gastric epithelial cells. Gastroenterology 1999; 117:1119-27. [PMID: 10535875 DOI: 10.1016/s0016-5085(99)70397-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND & AIMS Heregulins (HRGs) regulate the proliferation and differentiation of various cell types. However, very little is known about their function in the gastrointestinal tract. The aim of this study was to investigate the role of HRGs on gastrointestinal cells. METHODS We examined the expression of erbB receptors and HRG-alpha in human gastric cancer cell lines, rat gastrointestinal epithelial cells, and human gastric fibroblasts by Western blot analysis or reverse-transcription polymerase chain reaction. Receptor phosphorylation and heterodimerization induced by HRG-alpha were detected by Western blot analysis. We also evaluated the in vitro effects of HRG-alpha on cell proliferation and restitution. RESULTS Cancer cell lines and rat epithelial cells expressed erbB2 and erbB3, but protein expression of erbB4 was not detected. HRG-alpha was detected only in gastric fibroblasts. HRG-alpha activated tyrosine phosphorylation of epidermal growth factor receptor (EGFR), erbB2, and erbB3 and induced not only erbB3/erbB2 but also erbB3/EGFR and erbB2/EGFR heterodimer formation in MKN-28 cancer cells. Simultaneous cultivation of MKN-28 cells with gastric fibroblasts resulted in tyrosine phosphorylation of erbB3 in MKN-28 cells. HRG-alpha also stimulated proliferation of MKN-28 cells and gastric epithelial cells. CONCLUSIONS The data suggest that HRG-alpha may affect epithelial cell proliferation through mesenchymal-epithelial interaction in the gastric mucosa.
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Affiliation(s)
- H Noguchi
- Second Department of Internal Medicine, Kobe University School of Medicine, Kobe, Japan
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25
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Canoll PD, Kraemer R, Teng KK, Marchionni MA, Salzer JL. GGF/neuregulin induces a phenotypic reversion of oligodendrocytes. Mol Cell Neurosci 1999; 13:79-94. [PMID: 10192767 DOI: 10.1006/mcne.1998.0733] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
We have previously shown that glial growth factor (GGF), a member of the neuregulin (NRG) family of growth factors, is a mitogen and survival factor for oligodendrocyte progenitors in cell culture and blocks their differentiation at the pro-oligodendrocyte stage (P. D. Canoll et al., 1996, Neuron 17, 229-243). We now show that GGF is able to induce differentiated oligodendrocytes to undergo a phenotypic reversion characterized by loss of MBP expression, reexpression of the intermediate filament protein nestin, reorganization of the actin cytoskeleton, and a dramatic reduction in the number of processes per cell. TUNEL analysis demonstrates that GGF is not cytotoxic for mature oligodendrocytes, but rather enhances their survival. GGF also induces the rapid activation of the PI 3-kinase and MAP kinase signaling pathways. These results further support a role for the NRGs in promoting the proliferation and survival of and inhibiting the differentiation of cells in the oligodendrocyte lineage and demonstrate that oligodendrocytes that differentiate in culture retain a substantial degree of phenotypic plasticity.
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Affiliation(s)
- P D Canoll
- Department of Pharmacology, New York University Medical School, 550 First Avenue, New York, New York 10016, USA
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Krymskaya VP, Hoffman R, Eszterhas A, Kane S, Ciocca V, Panettieri RA. EGF activates ErbB-2 and stimulates phosphatidylinositol 3-kinase in human airway smooth muscle cells. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:L246-55. [PMID: 9950886 DOI: 10.1152/ajplung.1999.276.2.l246] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The epidermal growth factor (EGF)-receptor (EGFR) family includes four homologous transmembrane receptor protein tyrosine kinases, EGFR, ErbB-2, ErbB-3, and ErbB-4. This receptor family plays a pivotal role in regulating cell proliferation, differentiation, and transformation. Ligand-induced activation of these receptors results in formation of homo- and heterodimers, which undergo transphosphorylation and transactivation. The aim of this study was to characterize the role of EGFR family members in signaling EGF-induced human airway smooth muscle (HASM) cell proliferation. Here, we show that EGF stimulates activation of EGFR and transactivation of ErbB-2 in quiescent HASM cells. Phosphatidylinositol (PI) 3-kinase, a critical signaling enzyme that modulates HASM cell growth, is preferentially associated with ErbB-2, and EGF-stimulated transactivation of ErbB-2 induces PI 3-kinase activation. ErbB-3 and ErbB-4 are present in HASM cells; however, EGF has no effect on their activation. Betacellulin, a ligand for EGFR, ErbB-3, and ErbB-4, induced DNA synthesis of HASM cells and stimulated signaling through the activation of EGFR and ErbB-2 but not of ErbB-3 and ErbB-4. Heregulin, a specific ligand for ErbB-3 and ErbB-4, did not effect DNA synthesis and did not activate its specific receptors. These data suggest that EGF imparts signals that involve activation of ErbB-2 and are associated with ErbB-2 PI 3-kinase activation. Despite the mRNA and protein expression of all members of the EGFR family, ligand-stimulated signaling induced activation of EGFR and ErbB-2 but not of ErbB-3 and ErbB-4.
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Affiliation(s)
- V P Krymskaya
- Pulmonary and Critical Care Division, Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
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Kataoka H, Joh T, Kasugai K, Okayama N, Moriyama A, Asai K, Kato T. Expression of mRNA for heregulin and its receptor, ErbB-3 and ErbB-4, in human upper gastrointestinal mucosa. Life Sci 1998; 63:553-64. [PMID: 9718081 DOI: 10.1016/s0024-3205(98)00306-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Expression of mRNA for heregulin (HRG), a member of the epidermal growth factor (EGF) family and its receptors, ErbB-3 and ErbB-4, were evaluated in human upper gastrointestinal (GI) mucosa. Multi-target reverse-transcriptase polymerase chain reaction (RT-PCR) analysis using capillary electrophoresis and laser-induced fluorescence allowed us to quantify the minute amounts of mRNA from one biopsy specimen with high sensitivity. HRG, ErbB-3 and ErbB-4 mRNA were detected in esophagus, stomach and duodenum and the highest expression was found in duodenum. In gastric cancer, mRNA for ErbB-4 was significantly overexpressed. Immunoreactivity of ErbB-4 in carcinoma cell membrane was also confirmed. These findings suggest that HRG and its receptors, ErbB-3 and ErbB-4 may be physiologically significant in the human upper GI mucosa, especially in duodenum, and that ErbB-4 may contribute to the growth of gastric cancer.
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Affiliation(s)
- H Kataoka
- First Department of Internal Medicine, Nagoya City University Medical School, Japan
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Lenferink AE, Pinkas-Kramarski R, van de Poll ML, van Vugt MJ, Klapper LN, Tzahar E, Waterman H, Sela M, van Zoelen EJ, Yarden Y. Differential endocytic routing of homo- and hetero-dimeric ErbB tyrosine kinases confers signaling superiority to receptor heterodimers. EMBO J 1998; 17:3385-97. [PMID: 9628875 PMCID: PMC1170676 DOI: 10.1093/emboj/17.12.3385] [Citation(s) in RCA: 297] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Both homo- and hetero-dimers of ErbB receptor tyrosine kinases mediate signaling by a large group of epidermal growth factor (EGF)-like ligands. However, some ligands are more potent than others, although they bind to the same direct receptor. In addition, signaling by receptor heterodimers is superior to homodimers. We addressed the mechanism underlying these two features of signal tuning by using three ligands: EGF; transforming growth factor alpha (TGFalpha); and their chimera, denoted E4T, which act on cells singly expressing ErbB-1 as a weak, a strong, and a very strong agonist, respectively. Co-expression of ErbB-2, a developmentally important co-receptor whose expression is frequently elevated in human cancers, specifically potentiated EGF signaling to the level achieved by TGFalpha, an effect that was partially mimicked by ErbB-3. Analysis of the mechanism underlying this trans-potentiation implied that EGF-driven homodimers of ErbB-1 are destined for intracellular degradation, whereas the corresponding heterodimers with ErbB-2 or with ErbB-3, dissociate in the early endosome. As a consequence, in the presence of either co-receptor, ErbB-1 is recycled to the cell surface and its signaling is enhanced. This latter route is followed by TGFalpha-driven homodimers of ErbB-1, and also by E4T-bound receptors, whose signaling is further enhanced by repeated cycles of binding and dissociation from the receptors. We conclude that alternative endocytic routes of homo- and hetero-dimeric receptor complexes may contribute to tuning and diversification of signal transduction. In addition, the ability of ErbB-2 to shunt ligand-activated receptors to recycling may explain, in part, its oncogenic potential.
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Affiliation(s)
- A E Lenferink
- Department of Cell Biology, University of Nijmegen, Nijmegen, The Netherlands
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29
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Thoresen GH, Guren TK, Sandnes D, Peak M, Agius L, Christoffersen T. Response to transforming growth factor alpha (TGFalpha) and epidermal growth factor (EGF) in hepatocytes: lower EGF receptor affinity of TGFalpha is associated with more sustained activation of p42/p44 mitogen-activated protein kinase and greater efficacy in stimulation of DNA synthesis. J Cell Physiol 1998; 175:10-8. [PMID: 9491776 DOI: 10.1002/(sici)1097-4652(199804)175:1<10::aid-jcp2>3.0.co;2-f] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The epidermal growth factor (EGF) receptor mediates the effects of both EGF and transforming growth factor alpha (TGFalpha). Recent data suggested that EGF acts as a partial agonist/antagonist in hepatocytes, TGFalpha exerting a larger maximal stimulation of DNA synthesis than EGF. To further study the mechanisms involved in mediating the different effects of EGF and TGFalpha, we have examined receptor binding of the two growth factors and their action on the p42/p44 mitogen-activated protein (MAP) kinase activity in hepatocytes. Single-ligand concentration curves and competition experiments showed that the binding affinity to a common population of surface binding sites was about 20-fold lower for TGFalpha than for EGF. MAP kinase activity responded to EGF and TGFalpha with different kinetics. While the two agents produced almost identical acute (5 min) stimulation (peak about fivefold), TGFalpha produced a more sustained MAP kinase activity than EGF. The difference between EGF and TGFalpha was still detectable 24 h after growth factor addition. The results show that in hepatocytes a lower receptor affinity of TGFalpha, as compared to EGF, is associated with a more sustained activation of the MAP kinase and a greater efficacy in the stimulation of DNA synthesis. This suggests that differential interaction of these two agents with the EGF receptor results in differences in the downstream events elicited at a given level of receptor occupancy. The data also are compatible with a role of a prolonged MAP kinase activity in the mitogenic effects of EGF and TGFalpha.
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Affiliation(s)
- G H Thoresen
- Department of Pharmacology, Faculty of Medicine, University of Oslo, Norway.
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Emkey R, Kahn CR. Cross-talk between phorbol ester-mediated signaling and tyrosine kinase proto-oncogenes. II. Comparison of phorbol ester and sphingomyelinase-induced phosphorylation of ErbB2 and ErbB3. J Biol Chem 1997; 272:31182-9. [PMID: 9388272 DOI: 10.1074/jbc.272.49.31182] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
In the accompanying paper (Emkey, R., and Kahn, C. R. (1997) J. Biol. Chem. 272, 31172-31181), we demonstrated that phorbol 12-myristate 13-acetate (PMA) treatment of Fao cells induces tyrosine phosphorylation of several proteins including ErbB2 and ErbB3. In the present study we show that sphingomyelinase also results in the enhanced tyrosine phosphorylation of ErbB2 and ErbB3 in these cells. In contrast to activation by PMA, the sphingomyelinase-induced phosphorylation of these proteins is independent of protein kinase C. However, both agents stimulate tyrosine phosphorylation of the kinase Pyk2 suggesting that it may be involved in the PMA and sphingomyelinase activation of these ErbB proto-oncogenes. Insulin plays a negative regulatory role in the ligand and non-ligand-induced phosphorylation of the ErbB proto-oncogenes via two mechanisms. Prolonged insulin treatment resulted in decreased expression of both ErbB2 and ErbB3. Insulin also appears to negatively regulate the protein tyrosine kinase responsible for phosphorylating ErbB2 in PMA-stimulated cells. The former effect of insulin was relieved by treatment with inhibitors of phosphatidylinositol 3-kinase. The similarities in PMA and sphingomyelinase-induced effects and the negative regulatory role of insulin suggest a mechanism by which multiple ligands can synergize with or protect against the tumorigenic effects of phorbol esters.
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Affiliation(s)
- R Emkey
- Research Division, Joslin Diabetes Center, and Department of Medicine, Harvard Medical School, Boston, Massachusetts 02215, USA
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Carver RS, Mathew PM, Russell WE. Hepatic expression of ErbB3 is repressed by insulin in a pathway sensitive to PI-3 kinase inhibitors. Endocrinology 1997; 138:5195-201. [PMID: 9389501 DOI: 10.1210/endo.138.12.5601] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
ErbB3 is an epidermal growth factor receptor-related type I tyrosine kinase receptor capable, in conjunction with ErbB2 or epidermal growth factor receptor, of transmitting proliferative and differentiative signals in a variety of cell types. We previously showed that ErbB3 messenger RNA and protein increase in cultured hepatocytes during the first 12 h in culture, as does the binding of heregulin beta1, a ligand for ErbB3. Insulin inhibits the increase in heregulin beta1 binding, as well as the increase in ErbB3 messenger RNA and protein. Two models of insulin deficiency in vivo (diabetes and fasting) demonstrated elevated levels of hepatic ErbB3 protein, strengthening the relevance of our observations in vitro. Using chemical activators or antagonists, we sought to identify the signaling pathways that link insulin to ErbB3 expression. The PI-3 kinase inhibitors, wortmannin and LY294002, completely blocked the inhibition of ErbB3 protein expression by insulin, suggesting a role for PI-3 kinase in the regulation of this growth factor receptor. Rapamycin, an inhibitor of p70 S6 kinase, an enzyme downstream of PI-3 kinase, failed to block the effect of insulin on ErbB3 expression. These results suggest a complex regulatory paradign for ErbB3 that includes PI-3 kinase and may be linked, via insulin, to the metabolic status of the animal.
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Affiliation(s)
- R S Carver
- Department of Cell Biology, Vanderbilt University, Nashville, Tennessee 37232, USA
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Affiliation(s)
- E D Adamson
- Burnham Institute, La Jolla Cancer Research Center, California 92037, USA
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