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Ioannidis M, Mahata SK, van den Bogaart G. The immunomodulatory functions of chromogranin A-derived peptide pancreastatin. Peptides 2022; 158:170893. [PMID: 36244579 PMCID: PMC10760928 DOI: 10.1016/j.peptides.2022.170893] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2022] [Revised: 10/08/2022] [Accepted: 10/10/2022] [Indexed: 11/06/2022]
Abstract
Chromogranin A (CgA) is a 439 amino acid protein secreted by neuroendocrine cells. Proteolytic processing of CgA results in the production of different bioactive peptides. These peptides have been associated with inflammatory bowel disease, diabetes, and cancer. One of the chromogranin A-derived peptides is ∼52 amino acid long Pancreastatin (PST: human (h)CgA250-301, murine (m)CgA263-314). PST is a glycogenolytic peptide that inhibits glucose-induced insulin secretion from pancreatic islet β-cells. In addition to this metabolic role, evidence is emerging that PST also has inflammatory properties. This review will discuss the immunomodulatory properties of PST and its possible mechanisms of action and regulation. Moreover, this review will discuss the potential translation to humans and how PST may be an interesting therapeutic target for treating inflammatory diseases.
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Affiliation(s)
- Melina Ioannidis
- Department of Molecular Immunology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, the Netherlands
| | - Sushil K Mahata
- VA San Diego Healthcare System, San Diego, CA, USA; Department of Medicine, University of California San Diego, La Jolla, CA, USA.
| | - Geert van den Bogaart
- Department of Molecular Immunology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, the Netherlands; Department of Medical Biology and Pathology, University Medical Center Groningen, Groningen, the Netherlands.
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Troger J, Theurl M, Kirchmair R, Pasqua T, Tota B, Angelone T, Cerra MC, Nowosielski Y, Mätzler R, Troger J, Gayen JR, Trudeau V, Corti A, Helle KB. Granin-derived peptides. Prog Neurobiol 2017; 154:37-61. [PMID: 28442394 DOI: 10.1016/j.pneurobio.2017.04.003] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Revised: 04/10/2017] [Accepted: 04/16/2017] [Indexed: 12/14/2022]
Abstract
The granin family comprises altogether 7 different proteins originating from the diffuse neuroendocrine system and elements of the central and peripheral nervous systems. The family is dominated by three uniquely acidic members, namely chromogranin A (CgA), chromogranin B (CgB) and secretogranin II (SgII). Since the late 1980s it has become evident that these proteins are proteolytically processed, intragranularly and/or extracellularly into a range of biologically active peptides; a number of them with regulatory properties of physiological and/or pathophysiological significance. The aim of this comprehensive overview is to provide an up-to-date insight into the distribution and properties of the well established granin-derived peptides and their putative roles in homeostatic regulations. Hence, focus is directed to peptides derived from the three main granins, e.g. to the chromogranin A derived vasostatins, betagranins, pancreastatin and catestatins, the chromogranin B-derived secretolytin and the secretogranin II-derived secretoneurin (SN). In addition, the distribution and properties of the chromogranin A-derived peptides prochromacin, chromofungin, WE14, parastatin, GE-25 and serpinins, the CgB-peptide PE-11 and the SgII-peptides EM66 and manserin will also be commented on. Finally, the opposing effects of the CgA-derived vasostatin-I and catestatin and the SgII-derived peptide SN on the integrity of the vasculature, myocardial contractility, angiogenesis in wound healing, inflammatory conditions and tumors will be discussed.
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Affiliation(s)
- Josef Troger
- Department of Ophthalmology, Medical University of Innsbruck, Innsbruck, Austria.
| | - Markus Theurl
- Department of Internal Medicine, Medical University of Innsbruck, Innsbruck, Austria
| | - Rudolf Kirchmair
- Department of Internal Medicine, Medical University of Innsbruck, Innsbruck, Austria
| | - Teresa Pasqua
- Department of Biology, Ecology and Earth Sciences, University of Calabria, Arcavacata di Rende, Italy
| | - Bruno Tota
- Department of Biology, Ecology and Earth Sciences, University of Calabria, Arcavacata di Rende, Italy
| | - Tommaso Angelone
- Department of Biology, Ecology and Earth Sciences, University of Calabria, Arcavacata di Rende, Italy
| | - Maria C Cerra
- Department of Biology, Ecology and Earth Sciences, University of Calabria, Arcavacata di Rende, Italy
| | - Yvonne Nowosielski
- Department of Ophthalmology, Medical University of Innsbruck, Innsbruck, Austria
| | - Raphaela Mätzler
- Department of Ophthalmology, Medical University of Innsbruck, Innsbruck, Austria
| | - Jasmin Troger
- Department of Ophthalmology, Medical University of Innsbruck, Innsbruck, Austria
| | | | - Vance Trudeau
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Angelo Corti
- Vita-Salute San Raffaele University and Division of Experimental Oncology, San Raffaele Scientific Institute, Milan, Italy
| | - Karen B Helle
- Department of Biomedicine, University of Bergen, Norway
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Discovery of a novel target for the dysglycemic chromogranin A fragment pancreastatin: interaction with the chaperone GRP78 to influence metabolism. PLoS One 2014; 9:e84132. [PMID: 24465394 PMCID: PMC3896336 DOI: 10.1371/journal.pone.0084132] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2013] [Accepted: 11/12/2013] [Indexed: 11/19/2022] Open
Abstract
RATIONALE The chromogranin A-derived peptide pancreastatin (PST) is a dysglycemic, counter-regulatory peptide for insulin action, especially in liver. Although previous evidence for a PST binding protein has been reported, such a receptor has not been identified or sequenced. METHODS AND RESULTS We used ligand affinity to purify the PST target, with biotinylated human PST (hCHGA273-301-amide) as "bait" and mouse liver homogenate as "prey", and identified GRP78 (a.k.a. "78 kDa Glucose Regulated Protein", HSPA5, BIP) as a major interacting partner of PST. GRP78 belongs to the family of heat shock proteins (chaperones), involved in several cellular processes including protein folding and glucose metabolism. We analyzed expression of GRP78 in the absence of PST in a mouse knockout model lacking its precursor CHGA: hepatic transcriptome data revealed global over-expression of not only GRP78 but also other heat shock transcripts (of the "adaptive UPR") in CHGA(-/-) mice compared to wild-type (+/+). By contrast, we found a global decline in expression of hepatic pro-apoptotic transcripts in CHGA(-/-) mice. GRP78's ATPase enzymatic activity was dose-dependently inhibited by PST (IC50∼5.2 µM). PST also inhibited the up-regulation of GRP78 expression during UPR activation (by tunicamycin) in hepatocytes. PST inhibited insulin-stimulated glucose uptake in adipocytes, and increased hepatic expression of G6Pase (the final step in gluconeogenesis/glycogenolysis). In hepatocytes not only PST but also other GRP78-ATPase inhibitors (VER-155008 or ADP) increased G6Pase expression. GRP78 over-expression inhibited G6Pase expression in hepatocytes, with partial restoration by GRP78-ATPase inhibitors PST, VER-155008, or ADP. CONCLUSIONS Our results indicate that an unexpected major hepatic target of PST is the adaptive UPR chaperone GRP78. PST not only binds to GRP78 (in pH-dependent fashion), but also inhibits GRP78's ATPase enzymatic activity, and impairs its biosynthetic response to UPR activation. PST decreases insulin-stimulated cellular glucose uptake, and PST as well as other chaperone ATPase activity inhibitors augment expression of G6Pase; GRP78 over-expression antagonizes this PST action. Analysis of the novel PST/GRP78 interaction may provide a new avenue of investigation into cellular glycemic control as well as dysglycemia.
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Valicherla GR, Hossain Z, Mahata SK, Gayen JR. Pancreastatin is an endogenous peptide that regulates glucose homeostasis. Physiol Genomics 2013; 45:1060-71. [PMID: 24064537 DOI: 10.1152/physiolgenomics.00131.2013] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Pancreastatin (PST) is a regulatory peptide containing 49 amino acids, first isolated from porcine pancreas. Intracellular and extracellular processing of the prohormone Chromogranin A (Chga) results various bioactive peptides of which PST has dysglycemic activity. PST regulates glucose, lipid, and protein metabolism in liver and adipose tissues. It also regulates the secretion of leptin and expression of leptin and uncoupling protein 2 in adipose tissue. In Chga knockout mice, PST induces gluconeogenesis in the liver. PST reduces glucose uptake in mice hepatocytes and adipocytes. In rat hepatocytes, PST induces glycogenolysis and glycolysis and inhibits glycogen synthesis. In rat adipocytes, PST inhibits lactate production and lipogenesis. These metabolic effects are confirmed in humans. In the dual signaling mechanism of PST receptor, mostly PST activates Gαq/11 protein leads to the activation of phospholipase C β3-isoform, therefore increasing cytoplasmic free calcium and stimulating protein kinase C. PST inhibits the cell growth in rat HTC hepatoma cells, mediated by nitric oxide and cyclic GMP production. Elevated levels of PST correlating with catecholamines have been found in gestational diabetes and essential hypertension. Rise in the blood PST level in Type 2 diabetes suggests that PST is a negative regulator of insulin sensitivity and glucose homeostasis.
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Affiliation(s)
- Guru Raghavendra Valicherla
- Pharmacokinetics and Metabolism Division, Council of Scientific and Industrial Research-Central Drug Research Institute, Lucknow, India
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El-Haibi CP, Sharma P, Singh R, Gupta P, Taub DD, Singh S, Lillard JW. Differential G protein subunit expression by prostate cancer cells and their interaction with CXCR5. Mol Cancer 2013; 12:64. [PMID: 23773523 PMCID: PMC3720210 DOI: 10.1186/1476-4598-12-64] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Accepted: 06/05/2013] [Indexed: 11/16/2022] Open
Abstract
Background Prostate cancer (PCa) cell lines and tissues differentially express CXCR5, which positively correlate with PCa progression, and mediate PCa cell migration and invasion following interaction with CXCL13. However, the differential expression of G protein α, β, and γ subunits by PCa cell lines and the precise combination of these proteins with CXCR5 has not been elucidated. Methods We examined differences in G protein expression of normal prostate (RWPE-1) and PCa cell lines (LNCaP, C4-2B, and PC3) by western blot analysis. Further, we immunoprecipitated CXCR5 with different G protein subunits, and CXCR4, following CXCL13 stimulation. To investigate constitutive coupling of CXCR5 with CXCR4 and PAR-1 we performed invasion assay in PCa cells transfected with Gαq/i2 or Gα13 siRNA, following CXCL13 treatment. We also investigated Rac and RhoA activity by G-LISA activation assay in PCa cells following CXCL13/thrombin stimulation. Result Of the 22 G proteins studied, Gαi1-3, Gβ1-4, Gγ5, Gγ7, and Gγ10 were expressed by both normal and PCa cell lines. Gαs was moderately expressed in C4-2B and PC3 cell lines, Gαq/11 was only present in RWPE-1 and LNCaP cell lines, while Gα12 and Gα13 were expressed in C4-2B and PC3 cell lines. Gγ9 was expressed only in PCa cell lines. Gα16, Gβ5, Gγ1-4, and Gγ13 were not detected in any of the cell lines studied. Surprisingly, CXCR4 co-immunoprecipitated with CXCR5 in PCa cell lines irrespective of CXCL13 treatment. We also identified specific G protein isoforms coupled to CXCR5 in its resting and active states. Gαq/11/Gβ3/Gγ9 in LNCaP and Gαi2/Gβ3/Gγ9 in C4-2B and PC3 cell lines, were coupled to CXCR5 and disassociated following CXCL13 stimulation. Interestingly, Gα13 co-immunoprecipitated with CXCR5 in CXCL13-treated, but not in untreated PCa cell lines. Inhibition of Gαq/i2 significantly decreased the ability of cells to invade, whereas silencing Gα13 did not affect CXCL13-dependent cell invasion. Finally, CXCL13 treatment significantly increased Rac activity in Gαq/i2 dependent manner, but not RhoA activity, in PCa cell lines. Conclusions These findings offer insight into molecular mechanisms of PCa progression and can help to design some therapeutic strategies involving CXCR5 and/or CXCL13 blockade and specific G protein inhibition to abrogate PCa metastasis.
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Yao J, Liang LH, Zhang Y, Ding J, Tian Q, Li JJ, He XH. GNAI1 Suppresses Tumor Cell Migration and Invasion and is Post-Transcriptionally Regulated by Mir-320a/c/d in Hepatocellular Carcinoma. Cancer Biol Med 2013; 9:234-41. [PMID: 23691483 PMCID: PMC3643671 DOI: 10.7497/j.issn.2095-3941.2012.04.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Accepted: 11/07/2012] [Indexed: 12/31/2022] Open
Abstract
Objective To explore the role and regulation of guanine nucleotide-binding protein G(i), α-1 subunit (GNAI1) in hepatocellular carcinoma (HCC). Methods Expression of GNAI1 in HCC samples was determined by qRT–PCR and immunohistochemical (IHC) staining. Huh-7 and SNU-387 cells stably expressing GNAI1 were established by the infection of lentivirus transducing unit containing GNAI1. siRNA against GNAI1 was transfected into SMMC-7721 cells to knock down the GNAI1 expression in HCC cells. Mir-320a/c/d mimics were transfected into SMMC-7721 and SK-Hep-1 cells and the expression of GNAI1 was determined by Western blot. The migration and invasion of Huh-7, SNU-387, SK-Hep-1 and SMMC-7721 cells were investigated by Transwell assays. Results The GNAI1 protein was significantly downregulated in HCC samples without changes in its mRNA levels. GNAI1 could inhibit the migration and invasion of HCC cells in vitro. Further investigations indicated that GNAI1 was a target of miR-320a/c/d in HCC cells. Transwell assays demonstrated that these microRNAs could promote the migratory ability and invasivesess of HCC cells in vitro. Conclusions GNAI1 is downregulated in HCC and inhibits the migration and invasion of HCC cells. This study is the first to investigate the role of GNAI1 in cancer. Regulation of GNAI1 by miR-320a/c/d indicates new therapeutic avenues for targeting HCC metastasis.
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Affiliation(s)
- Jian Yao
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200032, China ; State Key Laboratory for Diagnosis and Treatment for Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou 310003, China
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Sánchez-Margalet V, González-Yanes C, Najib S, Santos-Álvarez J. Reprint of: Metabolic effects and mechanism of action of the chromogranin A-derived peptide pancreastatin. ACTA ACUST UNITED AC 2010; 165:71-7. [PMID: 20934461 DOI: 10.1016/j.regpep.2010.10.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2009] [Revised: 02/09/2010] [Accepted: 02/11/2010] [Indexed: 01/12/2023]
Abstract
Pancreastatin is one of the regulatory peptides derived from intracellular and/or extracellular processing of chromogranin A, the soluble acidic protein present in the secretory granules of the neuroendocrine system. While the intracellular functions of chromogranin A include formation and maturation of the secretory granule, the major extracellular functions are generation of biologically active peptides with demonstrated autocrine, paracrine or endocrine activities. In this review, we will focus on the metabolic function of one of these peptides, pancreastatin, and the mechanisms underlying its effects. Many different reported effects have implicated PST in the modulation of energy metabolism, with a general counterregulatory effect to that of insulin. Pancreastatin induces glycogenolysis in liver and lipolysis in adipocytes. Metabolic effects have been confirmed in humans. Moreover, naturally occurring human variants have been found, one of which (Gly297Ser) occurs in the functionally important carboxy-terminus of the peptide, and substantially increases the peptide's potency to inhibit cellular glucose uptake. Thus, qualitative hereditary alterations in pancreastatin's primary structure may give rise to interindividual differences in glucose and lipid metabolism. Pancreastatin activates a receptor signaling system that belongs to the seven-spanning transmembrane receptor coupled to a Gq-PLCβ-calcium-PKC signaling pathway. Increased pancreastatin plasma levels, correlating with catecholamines levels, have been found in insulin resistance states, such as gestational diabetes or essential hypertension. Pancreastatin plays important physiological role in potentiating the metabolic effects of catecholamines, and may also play a pathophysiological role in insulin resistance states with increased sympathetic activity.
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Affiliation(s)
- Víctor Sánchez-Margalet
- Department of Medical Biochemistry and Molecular Biology, School of Medicine, Virgen Macarena University Hospital, University of Seville, Spain.
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Sánchez-Margalet V, González-Yanes C, Najib S, Santos-Alvarez J. Metabolic effects and mechanism of action of the chromogranin A-derived peptide pancreastatin. ACTA ACUST UNITED AC 2010; 161:8-14. [PMID: 20184923 DOI: 10.1016/j.regpep.2010.02.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2009] [Revised: 02/09/2010] [Accepted: 02/11/2010] [Indexed: 12/20/2022]
Abstract
Pancreastatin is one of the regulatory peptides derived from intracellular and/or extracellular processing of chromogranin A, the soluble acidic protein present in the secretory granules of the neuroendocrine system. While the intracellular functions of chromogranin A include formation and maturation of the secretory granule, the major extracellular functions are generation of biologically active peptides with demonstrated autocrine, paracrine or endocrine activities. In this review, we will focus on the metabolic function of one of these peptides, pancreastatin, and the mechanisms underlying its effects. Many different reported effects have implicated PST in the modulation of energy metabolism, with a general counterregulatory effect to that of insulin. Pancreastatin induces glycogenolysis in liver and lipolysis in adipocytes. Metabolic effects have been confirmed in humans. Moreover, naturally occurring human variants have been found, one of which (Gly297Ser) occurs in the functionally important carboxy-terminus of the peptide, and substantially increases the peptide's potency to inhibit cellular glucose uptake. Thus, qualitative hereditary alterations in pancreastatin's primary structure may give rise to interindividual differences in glucose and lipid metabolism. Pancreastatin activates a receptor signaling system that belongs to the seven-spanning transmembrane receptor coupled to a Gq-PLCbeta-calcium-PKC signaling pathway. Increased pancreastatin plasma levels, correlating with catecholamines levels, have been found in insulin resistance states, such as gestational diabetes or essential hypertension. Pancreastatin plays important physiological role in potentiating the metabolic effects of catecholamines, and may also play a pathophysiological role in insulin resistance states with increased sympathetic activity.
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Affiliation(s)
- Víctor Sánchez-Margalet
- Department of Medical Biochemistry and Molecular Biology, School of Medicine, Virgen Macarena University Hospital, University of Seville, Spain.
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Hermans E. Biochemical and pharmacological control of the multiplicity of coupling at G-protein-coupled receptors. Pharmacol Ther 2003; 99:25-44. [PMID: 12804697 DOI: 10.1016/s0163-7258(03)00051-2] [Citation(s) in RCA: 221] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
For decades, it has been generally proposed that a given receptor always interacts with a particular GTP-binding protein (G-protein) or with multiple G-proteins within one family. However, for several G-protein-coupled receptors (GPCR), it now becomes generally accepted that simultaneous functional coupling with distinct unrelated G-proteins can be observed, leading to the activation of multiple intracellular effectors with distinct efficacies and/or potencies. Multiplicity in G-protein coupling is frequently observed in artificial expression systems where high densities of receptors are obtained, raising the question of whether such complex signalling reveals artefactual promiscuous coupling or is a genuine property of GPCRs. Multiple biochemical and pharmacological evidence in favour of an intrinsic property of GPCRs were obtained in recent studies. Thus, there are now many examples showing that the coupling to multiple signalling pathways is dependent on the agonist used (agonist trafficking of receptor signals). In addition, the different couplings were demonstrated to involve distinct molecular determinants of the receptor and to show distinct desensitisation kinetics. Such multiplicity of signalling at the level of G-protein coupling leads to a further complexity in the functional response to agonist stimulation of one of the most elaborate cellular transmission systems. Indeed, the physiological relevance of such versatility in signalling associated with a single receptor requires the existence of critical mechanisms of dynamic regulation of the expression, the compartmentalisation, and the activity of the signalling partners. This review aims at summarising the different studies that support the concept of multiplicity of G-protein coupling. The physiological and pharmacological relevance of this coupling promiscuity will be discussed.
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Affiliation(s)
- Emmanuel Hermans
- Laboratoire de Pharmacologie Expérimentale, Université Catholique de Louvain, FARL 54.10, Avenue Hippocrate 54, B-1200 Brussels, Belgium.
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Liu D, Dillon JS. Dehydroepiandrosterone activates endothelial cell nitric-oxide synthase by a specific plasma membrane receptor coupled to Galpha(i2,3). J Biol Chem 2002; 277:21379-88. [PMID: 11934890 DOI: 10.1074/jbc.m200491200] [Citation(s) in RCA: 219] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The adrenal steroid dehydroepiandrosterone (DHEA) has no known cellular receptor or unifying mechanism of action, despite evidence suggesting beneficial vascular effects in humans. Based on previous data from our laboratory, we hypothesized that DHEA binds to specific cell-surface receptors to activate intracellular G-proteins and endothelial nitric-oxide synthase (eNOS). We now pharmacologically characterize a putative plasma membrane DHEA receptor and define its associated G-proteins. The [3H]DHEA binding to isolated plasma membranes from bovine aortic endothelial cells was of high affinity (K(d) = 48.7 pm) and saturable (B(max) = 500 fmol/mg protein). Structurally related steroids failed to compete with DHEA for binding. The putative DHEA receptor was functionally coupled to G-proteins, because guanosine 5'-O-(3-thio)triphosphate (GTPgammaS) inhibited [3H]DHEA binding to plasma membranes by 69%, and DHEA increased [35S]GTPgammaS binding by 157%. DHEA stimulated [35S]GTPgammaS binding to Galpha(i2) and Galpha(i3), but not to Galpha(i1) or Galpha(o). Pretreatment of plasma membranes with antibody to Galpha(i2) or Galpha(i3), but not to Galpha(i1), inhibited the DHEA activation of eNOS. Thus, DHEA receptors are expressed on endothelial cell plasma membranes and are coupled to eNOS activity through Galpha(i2) and Galpha(i3). These novel findings should allow us to isolate the putative receptor and reevaluate the physiological role of DHEA activity.
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Affiliation(s)
- Dongmin Liu
- Division of Endocrinology, Department of Internal Medicine, University of Iowa College of Medicine and Veterans Administration Medical Center, Iowa City, Iowa 52246, USA
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Sánchez-Margalet V, González-Yanes C, Santos-Alvarez J, Najib S. Pancreastatin. Biological effects and mechanisms of action. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2001; 482:247-62. [PMID: 11192586 DOI: 10.1007/0-306-46837-9_20] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Affiliation(s)
- V Sánchez-Margalet
- Department of Medical Biochemistry and Molecular Biology, School of Medicine, and Investigation Unit, University Hospital Virgen Macarena, Seville, Spain
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González-Yanes C, Santos-Alvarez J, Sánchez-Margalet V. Pancreastatin, a chromogranin A-derived peptide, activates Galpha(16) and phospholipase C-beta(2) by interacting with specific receptors in rat heart membranes. Cell Signal 2001; 13:43-9. [PMID: 11257446 DOI: 10.1016/s0898-6568(00)00127-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Pancreastatin (PST) is one of the chromogranin A (CGA)-derived peptides with known biological activity. It has a general inhibitory effect on secretion in many exocrine and endocrine systems including the heart atrium. Besides, a role of PST as a counter-regulatory peptide of insulin action has been proposed in the light of its effects on glucose and lipid metabolism in the liver and adipose tissue, where receptors and signaling have been described. Galpha(q/11) pathway seems to mediate PST action. Since PST has been shown to function as a typical calcium-dependent hormone, and increased plasma levels have been found in essential hypertension correlating with catecholamines, we sought to study its possible interaction and signaling in heart membranes. Here, we are characterizing specific PST binding sites and signaling in rat heart membranes. We have found that PST receptor has a K(d) of 0.5 nM and a B(max) of 34 fmol/mg of protein. The PST binding is inhibited by guanine nucleotides, suggesting the functional coupling of the receptor with GTP binding proteins (G proteins). Moreover, PST dose-dependently increases GTP binding to rat heart membranes. Finally, we have studied PST signaling-effector system by measuring phospholipase C (PLC) activity using blocking antibodies against different G proteins and PLC isoforms. We have found that PST stimulates PLCbeta(2)>PLCbeta(1)>PLCbeta(3) by activating Galpha(16) in rat heart membranes. These data suggest that PST may modulate the cardiac function.
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Affiliation(s)
- C González-Yanes
- Department of Medical Biochemistry and Molecular Biology, School of Medicine, University Hospital Virgen Macarena, Av. Sanchez Pizjuan 4, 41009, Seville, Spain
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Sánchez-Margalet V, González-Yanes C, Santos-Alvarez J, Najib S. Characterization of pancreastatin receptor and signaling in rat HTC hepatoma cells. Eur J Pharmacol 2000; 397:229-35. [PMID: 10844119 DOI: 10.1016/s0014-2999(00)00253-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Pancreastatin, a chromogranin A-derived peptide widely distributed throughout the neuroendocrine system, has a general inhibitory effect on endocrine secretion and a counterregulatory effect on insulin action. We have recently described the cross-talk of pancreastatin with insulin signaling in rat hepatoma cells (HTC), where it inhibits insulin action and signaling through the serine phosphorylation of the insulin receptor, thereby impairing tyrosine kinase activity. Here, we have characterized pancreastatin receptors and signaling in HTC cells. The pancreastatin effector systems were studied by determining phospholipase C activity in HTC membranes and mitogen-activated protein kinase (MAPK) phosphorylation activity in HTC cells. Binding studies with radiolabeled pancreastatin showed a population of high affinity binding sites, with a B(max) of 8 fmol/mg protein and a K(d) of 0.6 nM. Moreover, we assessed the coupling of the receptor with a G protein system by inhibiting the binding with guanine nucleotide and by measuring the GTP binding to HTC membranes. We found that pancreastatin receptor was coupled with a G alpha(q/11) protein which activates phospholipase C-beta(1) and phospholipase C-beta(3), in addition to MAPK via both beta gamma and alpha(q/11).
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Affiliation(s)
- V Sánchez-Margalet
- Departamento de Bioquímica Médica y Biología Molecular, Facultad de Medicina, Unidad de Investigación, Hospital Universitario Virgen Macarena, Universidad de Sevilla, Av. Sánchez Pizjuan 4, 41009, Sevilla, Spain.
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Santos-Alvarez J, Sánchez-Margalet V. Affinity purification of pancreastatin receptor-Gq/11 protein complex from rat liver membranes. Arch Biochem Biophys 2000; 378:151-6. [PMID: 10871055 DOI: 10.1006/abbi.2000.1789] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Pancreastatin, a chromogranin A derived peptide, exerts a glycogenolytic effect on the hepatocyte. This effect is initiated by binding to membrane receptors which are coupled to pertussis toxin insensitive G proteins belonging to the Gq/11 family. We have recently solubilized active pancreastatin receptors from rat liver membranes still functionally coupled to G proteins. Here, we have purified pancreastatin receptors by a two-step procedure. First, pancreastatin receptors with their associated Gq/11 regulatory proteins were purified from liver membranes by lectin absorption chromatography on wheat germ agglutinin immobilized on agarose. A biotinylated rat pancreastatin analog was tested for binding to liver membranes before using it for affinity purification. Unlabeled biotinylated rat pancreastatin competed for 125I-labeled [Tyr0]PST binding to solubilized receptors with a Kd = 0.27 nM, comparable to that of native pancreastatin. The biotinylated analog was immobilized on streptavidin-coated Sepharose beads and used to further affinity purify wheat germ agglutinin eluted receptor material. Specific elution at low pH showed that the receptor protein was purified as an 80-kDa protein in association with a G protein of the q/11 family, as demonstrated by specific immunoblot analysis. The specificity of the receptor band was assessed by chemical cross-linking of the purified material followed by SDS-PAGE and autoradiography. In conclusion, we have purified pancreastatin receptor as a glycoprotein of 80 kDa physically associated with a Gq/11 protein.
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Affiliation(s)
- J Santos-Alvarez
- Department of Medical Biochemistry and Molecular Biology, School of Medicine, Virgen Macarena University Hospital, Seville, Spain
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González-Yanes C, Santos-Alvarez J, Sánchez-Margalet V. Characterization of pancreastatin receptors and signaling in adipocyte membranes. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1451:153-62. [PMID: 10446397 DOI: 10.1016/s0167-4889(99)00084-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Pancreastatin (PST), a chromogranin A derived peptide with an array of effects in different tissues, has a role as a counterregulatory hormone of insulin action in hepatocytes and adipocytes, regulating glucose, lipid and protein metabolism. We have previously characterized PST receptors and signaling in rat hepatocytes, in which PST functions as a calcium-mobilizing hormone. In the present work we have studied PST receptors as well as the signal transduction pathways generated upon PST binding in adipocyte membranes. First, we have characterized PST receptors using radiolabeled PST as a ligand. Analysis of binding data indicated the existence of one class of binding sites, with a B(max) of 5 fmol/mg of protein and a K(d) of 1 nM. In addition, we have studied the G protein system that couples the PST receptor by gamma-(35)S-GTP binding studies. We have found that two G protein systems are involved, pertussis toxin-sensitive and -insensitive respectively. Specific anti-G protein alpha subtype sera were used to block the effect of pancreastatin receptor activation. Galpha(q/11) and to a lesser extent Galpha(i1,2) are activated by PST in rat adipocyte membranes. On the other hand, adenylate cyclase activity was not affected by PST. Finally, we have studied the specific phospholipase C isoform that is activated in response to PST. We have found that PST receptor is coupled to PLC-beta(3) via Galpha(q/11) activation in adipocyte membranes.
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Affiliation(s)
- C González-Yanes
- Departamento de Bioquímica Médica y Biología Molecular, Facultad de Medicina, Unidad de Investigación del Hospital Universitario Virgen Macarena, Av. Sánchez Pizjuan 4, Sevilla 41009, Spain
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