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Weinberg DS, Foster NR, Della'Zanna G, McMurray RP, Kraft WK, Pallotto A, Kastenberg DM, Katz LC, Henry CH, Moleski SM, Limburg PJ, Waldman SA. Phase I double-blind, placebo-controlled trial of dolcanatide (SP-333) 27 mg to explore colorectal bioactivity in healthy volunteers. Cancer Biol Ther 2021; 22:544-553. [PMID: 34632925 DOI: 10.1080/15384047.2021.1967036] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Guanylyl cyclase C (GUCY2C) is a tumor-suppressing receptor silenced by loss of expression of the luminocrine hormones guanylin and uroguanylin early in colorectal carcinogenesis. This observation suggests oral replacement with a GUCY2C agonist may be an effective targeted chemoprevention agent. Previous studies revealed that linaclotide, an oral GUCY2C agonist formulated for gastric release, did not persist to activate guanylyl cyclase signaling in the distal rectum. Dolcanatide is an investigational oral uroguanylin analog, substituted with select D amino acids, for enhanced stability and extended persistence to activate GUCY2C in small and large intestine. However, the ability of oral dolcanatide to induce a pharmacodynamic (PD) response by activating GUCY2C in epithelial cells of the colorectum in humans remains undefined. Here, we demonstrate that administration of oral dolcanatide 27 mg daily for 7 d to healthy volunteers did not activate GUCY2C, quantified as accumulation of its product cyclic GMP, in epithelial cells of the distal rectum. These data reveal that the enhanced stability of dolcanatide, with persistence along the rostral-caudal axis of the small and large intestine, is inadequate to regulate GUCY2C across the colorectum to prevent tumorigenesis. These results highlight the importance of developing a GUCY2C agonist for cancer prevention formulated for release and activity targeted to the colorectum.
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Affiliation(s)
- David S Weinberg
- Department of Medicine, Fox Chase Cancer Center, Philadelphia, PA, USA
| | - Nathan R Foster
- Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, MN, USA
| | | | - Ryan P McMurray
- Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, MN, USA
| | - Walter K Kraft
- Department of Pharmacology and Experimental Therapeutics and Division of Gastroenterology and Hepatology, Thomas Jefferson University, Philadelphia, PA, USa
| | - Angela Pallotto
- Department of Pharmacology and Experimental Therapeutics and Division of Gastroenterology and Hepatology, Thomas Jefferson University, Philadelphia, PA, USa
| | - David M Kastenberg
- Department of Medicine, Thomas Jefferson University, Philadelphia, PA, USa
| | - Leo C Katz
- Department of Medicine, Thomas Jefferson University, Philadelphia, PA, USa
| | | | | | - Paul J Limburg
- Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, MN, USA
| | - Scott A Waldman
- Department of Medicine, Thomas Jefferson University, Philadelphia, PA, USa
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Waldman SA, Tenenbaum R, Foehl HC, Winkle P, Griffin P. Blunted Evoked Prouroguanylin Endocrine Secretion in Chronic Constipation. Clin Transl Gastroenterol 2019; 10:e00016. [PMID: 31318728 PMCID: PMC6708669 DOI: 10.14309/ctg.0000000000000016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 01/16/2019] [Indexed: 02/07/2023] Open
Abstract
OBJECTIVES Prouroguanylin (ProUGN) in the intestine is cleaved to form uroguanylin (UGN), which stimulates guanylate cyclase C (GUCY2C), inducing cyclic guanosine monophosphate signaling. Paracrine release regulates fluid secretion, contributing to bowel function, whereas endocrine secretion evoked by eating forms a gut-brain axis, controlling appetite. Whereas hormone insufficiency contributes to hyperphagia in obesity, its contribution to the pathophysiology of constipation syndromes remains unexplored. Here, we compared circulating ProUGN and UGN in healthy subjects and in patients with chronic idiopathic constipation (CIC) and patients with irritable bowel syndrome with constipation (IBS-C). METHODS Circulating ProUGN and UGN levels were measured in 60 healthy subjects, 53 patients with CIC, and 54 patients with IBS-C. After an overnight fast, the participants ingested a standardized meal; blood samples were drawn at fasting and at 30, 60, and 90 minutes thereafter, and hormone levels were quantified by enzyme-linked immunosorbent assay. RESULTS Fasting ProUGN levels were >30% lower in patients with CIC and those with IBS-C compared with healthy subjects regardless of age, sex, or disease state. After eating, ProUGN levels increased compared with fasting levels, although the rate of change was slower and maximum levels were lower in patients with CIC and those with IBS-C. Similarly, fasting UGN levels were lower in patients with CIC and those with IBS-C compared with healthy subjects. However, unlike ProUGN levels, UGN levels did not increase after eating. DISCUSSION These observations support a novel pathophysiologic model in which CIC and IBS-C reflect a contribution of ProUGN insufficiency dysregulating intestinal fluid and electrolyte secretion. TRANSLATIONAL IMPACT This study suggests that CIC and IBS-C can be treated by oral GUCY2C hormone replacement. Indeed, these observations provide a mechanistic framework for the clinical utility of oral GUCY2C ligands like plecanatide (Trulance) and linaclotide (Linzess) to treat CIC and IBS-C.
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Affiliation(s)
- Scott A. Waldman
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | | | - Henry C. Foehl
- Foehl Statistics & Analysis LLC, Philadelphia, Pennsylvania, USA
| | - Peter Winkle
- Anaheim Clinical Trials, Anaheim, California, USA
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Cid LP, Jentsch TJ, Sepúlveda FV. Reply from L. P. Cid, T. J. Jentsch and F. V. Sepúlveda: intestinal electrolyte and fluid secretion - a model in trouble? J Physiol 2018; 596:2465-2466. [PMID: 29663391 DOI: 10.1113/jp276139] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- L P Cid
- Centro de Estudios Científicos (CECs), Avenida Arturo Prat 514, Valdivia, Chile
| | - T J Jentsch
- Leibniz-Institut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), Berlin, Germany
| | - F V Sepúlveda
- Centro de Estudios Científicos (CECs), Avenida Arturo Prat 514, Valdivia, Chile
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4
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Weinberg DS, Lin JE, Foster NR, Della'Zanna G, Umar A, Seisler D, Kraft WK, Kastenberg DM, Katz LC, Limburg PJ, Waldman SA. Bioactivity of Oral Linaclotide in Human Colorectum for Cancer Chemoprevention. Cancer Prev Res (Phila) 2017; 10:345-354. [PMID: 28396341 PMCID: PMC5758862 DOI: 10.1158/1940-6207.capr-16-0286] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 01/31/2017] [Accepted: 04/03/2017] [Indexed: 12/21/2022]
Abstract
Guanylate cyclase C (GUCY2C) is a tumor-suppressing receptor silenced by loss of expression of its luminocrine hormones guanylin and uroguanylin early in colorectal carcinogenesis. This observation suggests oral replacement with a GUCY2C agonist may be an effective targeted chemoprevention agent. Linaclotide is an FDA-approved oral GUCY2C agonist formulated for gastric release, inducing fluid secretion into the small bowel to treat chronic idiopathic constipation. The ability of oral linaclotide to induce a pharmacodynamic response in epithelial cells of the colorectum in humans remains undefined. Here, we demonstrate that administration of 0.87 mg of oral linaclotide daily for 7 days to healthy volunteers, after oral colon preparation with polyethylene glycol solution (MoviPrep), activates GUCY2C, resulting in accumulation of its product cyclic (c)GMP in epithelial cells of the cecum, transverse colon, and distal rectum. GUCY2C activation by oral linaclotide was associated with homeostatic signaling, including phosphorylation of vasodilator-stimulated phosphoprotein and inhibition of proliferation quantified by reduced Ki67-positive epithelial cells. In the absence of the complete oral colonoscopy preparation, linaclotide did not alter cGMP production in epithelial cells of the colorectum, demonstrating that there was an effect related to the laxative preparation. These data show that the current FDA-approved formulation of oral linaclotide developed for small-bowel delivery to treat chronic idiopathic constipation is inadequate for reliably regulating GUCY2C in the colorectum to prevent tumorigenesis. The study results highlight the importance of developing a novel GUCY2C agonist formulated for release and activity targeted to the large intestine for colorectal cancer prevention. Cancer Prev Res; 10(6); 345-54. ©2017 AACR.
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Affiliation(s)
- David S Weinberg
- Department of Medicine, Fox Chase Cancer Center, Philadelphia, Pennsylvania
| | - Jieru E Lin
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Nathan R Foster
- Mayo Foundation for Medical Education and Research, Mayo Clinic, Rochester, Minnesota
| | | | - Asad Umar
- Division of Cancer Prevention, NCI, NIH, Bethesda, Maryland
| | - Drew Seisler
- Mayo Foundation for Medical Education and Research, Mayo Clinic, Rochester, Minnesota
| | - Walter K Kraft
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - David M Kastenberg
- Division of Gastroenterology, Department of Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Leo C Katz
- Division of Gastroenterology, Department of Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Paul J Limburg
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota
| | - Scott A Waldman
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, Pennsylvania.
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5
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Affiliation(s)
- Pamela J Hornby
- Janssen Research & Development, Cardiovascular and Metabolic Disease, Janssen Pharmaceutical Companies of Johnson and Johnson, SH42-2508-A, 1400 McKean Road, Spring House, PA 19477, USA
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Nausea, Vomiting, and Noninflammatory Diarrhea. MANDELL, DOUGLAS, AND BENNETT'S PRINCIPLES AND PRACTICE OF INFECTIOUS DISEASES 2015. [PMCID: PMC7173487 DOI: 10.1016/b978-1-4557-4801-3.00100-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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Marszalowicz GP, Snook AE, Magee MS, Merlino D, Lisa DBB, Waldman SA. GUCY2C lysosomotropic endocytosis delivers immunotoxin therapy to metastatic colorectal cancer. Oncotarget 2014; 5:9460-71. [PMID: 25294806 PMCID: PMC4253446 DOI: 10.18632/oncotarget.2455] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 09/07/2014] [Indexed: 02/06/2023] Open
Abstract
The emergence of targeted cancer therapy has been limited by the paucity of determinants which are tumor-specific and generally associated with disease, and have cell dynamics which effectively deploy cytotoxic payloads. Guanylyl cyclase C (GUCY2C) may be ideal for targeting because it is normally expressed only in insulated barrier compartments, including intestine and brain, but over-expressed by systemic metastatic colorectal tumors. Here, we reveal that GUCY2C rapidly internalizes from the cell surface to lysosomes in intestinal and colorectal cancer cells. Endocytosis is independent of ligand binding and receptor activation, and is mediated by clathrin. This mechanism suggests a design for immunotoxins comprising a GUCY2C-directed monoclonal antibody conjugated through a reducible disulfide linkage to ricin A chain, which is activated to a potent cytotoxin in lysosomes. Indeed, this immunotoxin specifically killed GUCY2C-expressing colorectal cancer cells in a lysosomal- and clathrin-dependent fashion. Moreover, this immunotoxin reduced pulmonary tumors>80% (p<0.001), and improved survival 25% (p<0.001), in mice with established colorectal cancer metastases. Further, therapeutic efficacy was achieved without histologic evidence of toxicity in normal tissues. These observations support GUCY2C-targeted immunotoxins as novel therapeutics for metastatic tumors originating in the GI tract, including colorectum, stomach, esophagus, and pancreas.
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Affiliation(s)
- Glen P. Marszalowicz
- School of Biomedical Engineering, Science, and Health Systems, Drexel University, Philadelphia, PA, USA
| | - Adam E. Snook
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, PA, USA
| | - Michael S. Magee
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, PA, USA
| | - Dante Merlino
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, PA, USA
| | | | - Scott A. Waldman
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, PA, USA
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8
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What is next in nitric oxide research? From cardiovascular system to cancer biology. Nitric Oxide 2014; 43:3-7. [PMID: 25153032 DOI: 10.1016/j.niox.2014.08.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Revised: 08/07/2014] [Accepted: 08/14/2014] [Indexed: 11/21/2022]
Abstract
The broad role of nitric oxide (NO) and cyclic GMP in biochemistry and biology as important messenger molecules is evident from the numerous publications in this research field. NO and cGMP have been known as components of the key signaling pathway in regulating numerous processes such as vascular dilation, blood pressure, neurotransmission, cardiovascular function, and renal function. In spite of almost 150,000 publications with nitric oxide and cyclic GMP, there are few publications regarding the effects of these messenger molecules on gene regulation, cell differentiation and cell proliferation. Our research data with embryonic stem cells and several cancer cell lines suggest that nitric oxide, its receptor soluble guanylyl cyclase (sGC) and sGC's product cyclic GMP can regulate the processes of proliferation and differentiation. Furthermore, we have found that undifferentiated stem cells and some malignant tumors such as human glioma have decreased levels of sGC and translocation of the sGCβ1 subunit to the nucleus. We propose that sGC and cyclic GMP function as tumor suppressors. An understanding of the mechanisms of the translocation of the sGCβ1 subunit into the nucleus and the possible regulation of gene expression of NO and/or cyclic CMP could lead to novel and innovative approaches to cancer therapy and stem cell proliferation and differentiation.
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9
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Lima AAM, Fonteles MC. From Escherichia coli heat-stable enterotoxin to mammalian endogenous guanylin hormones. ACTA ACUST UNITED AC 2014; 47:179-91. [PMID: 24652326 PMCID: PMC3982939 DOI: 10.1590/1414-431x20133063] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Accepted: 10/15/2013] [Indexed: 12/16/2022]
Abstract
The isolation of heat-stable enterotoxin (STa) from Escherichia coli and cholera toxin from Vibrio cholerae has increased our knowledge of specific mechanisms of action that could be used as pharmacological tools to understand the guanylyl cyclase-C and the adenylyl cyclase enzymatic systems. These discoveries have also been instrumental in increasing our understanding of the basic mechanisms that control the electrolyte and water balance in the gut, kidney, and urinary tracts under normal conditions and in disease. Herein, we review the evolution of genes of the guanylin family and STa genes from bacteria to fish and mammals. We also describe new developments and perspectives regarding these novel bacterial compounds and peptide hormones that act in electrolyte and water balance. The available data point toward new therapeutic perspectives for pathological features such as functional gastrointestinal disorders associated with constipation, colorectal cancer, cystic fibrosis, asthma, hypertension, gastrointestinal barrier function damage associated with enteropathy, enteric infection, malnutrition, satiety, food preferences, obesity, metabolic syndrome, and effects on behavior and brain disorders such as attention deficit, hyperactivity disorder, and schizophrenia.
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Affiliation(s)
- A A M Lima
- Unidade de Pesquisas Clinicas, Instituto de Biomedicina, Departamento de Fisiologia e Farmacologia, Escola de Medicina, Universidade Federal do Ceara, Fortaleza, CE, Brasil
| | - M C Fonteles
- Unidade de Pesquisas Clinicas, Instituto de Biomedicina, Departamento de Fisiologia e Farmacologia, Escola de Medicina, Universidade Federal do Ceara, Fortaleza, CE, Brasil
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10
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Blomain ES, Lin JE, Kraft CL, Trela UT, Rock JM, Aing AS, Snook AE, Waldman SA. Translating colorectal cancer prevention through the guanylyl cyclase C signaling axis. Expert Rev Clin Pharmacol 2013; 6:557-64. [PMID: 23971873 PMCID: PMC4048542 DOI: 10.1586/17512433.2013.827406] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Colorectal cancer (CRC) is a major public health concern, ranking among the leading causes of cancer death in both men and women. Because of this continued burden there is a clear need for improved treatment, and more importantly prevention of this disease. In recent years there is significant evidence to support the hypothesis that guanylyl cyclase C (GCY2C) is a tumor suppressor in the intestine, and that the loss of hormone ligands for this receptor is an important step in the disease process. Thus, ligand replacement therapy has been proposed as a strategy to prevent CRC. Until recently this strategy was not clinically plausible; however, the recent regulatory approval of linaclotide (LINZESS™, Forest Laboratories and Ironwood Pharmaceuticals, Inc.), an oral GUCY2C ligand, has raised the possibility of utilizing this strategy clinically to prevent CRC.
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Affiliation(s)
- Erik Scott Blomain
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Jieru Egeria Lin
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Crystal Lynn Kraft
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Urszula Teresa Trela
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Justin Michael Rock
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Amanda Sue Aing
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Adam Eugene Snook
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Scott Arthur Waldman
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, Pennsylvania
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11
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Pitari GM. Pharmacology and clinical potential of guanylyl cyclase C agonists in the treatment of ulcerative colitis. DRUG DESIGN DEVELOPMENT AND THERAPY 2013; 7:351-60. [PMID: 23637522 PMCID: PMC3634396 DOI: 10.2147/dddt.s32252] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Agonists of the transmembrane intestinal receptor guanylyl cyclase C (GCC) have recently attracted interest as promising human therapeutics. Peptide ligands that can specifically induce GCC signaling in the intestine include endogenous hormones guanylin and uroguanylin, diarrheagenic bacterial enterotoxins (ST), and synthetic drugs linaclotide, plecanatide, and SP-333. These agonists bind to GCC at intestinal epithelial surfaces and activate the receptor’s intracellular catalytic domain, an event initiating discrete biological responses upon conversion of guanosine-5′-triphosphate to cyclic guanosine monophosphate. A principal action of GCC agonists in the colon is the promotion of mucosal homeostasis and its dependent barrier function. Herein, GCC agonists are being developed as new medications to treat inflammatory bowel diseases, pathological conditions characterized by mucosal barrier hyperpermeability, abnormal immune reactions, and chronic local inflammation. This review will present important concepts underlying the pharmacology and therapeutic utility of GCC agonists for patients with ulcerative colitis, one of the most prevalent inflammatory bowel disease disorders.
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Affiliation(s)
- Giovanni M Pitari
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, PA 19107, USA.
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12
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Gong JP, Schulz S, Hyslop T, Waldman SA. GUCY2C molecular staging personalizes colorectal cancer patient management. Biomark Med 2012; 6:339-48. [PMID: 22731908 PMCID: PMC3477399 DOI: 10.2217/bmm.12.24] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
While the most significant prognostic and predictive marker in the management of colorectal cancer patients is cancer cells in regional lymph nodes, approximately 30% of patients whose lymph nodes are ostensibly free of tumor cells by histopathology ultimately develop recurrent disease reflecting occult metastases. Molecular techniques utilizing highly specific markers and ultra-sensitive detection technologies have emerged as powerful staging platforms to establish prognosis and predict responsiveness to chemotherapy in colorectal cancer patients. This review describes the evolution of the tumor suppressor GUCY2C as a prognostic and predictive molecular biomarker that quantifies occult tumor burden in regional lymph nodes for staging patients with colorectal cancer.
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Affiliation(s)
- Jian P Gong
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, PA, USA
- Center for Drug Evaluation and Research, Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring, MD 20993-0002, USA
| | - Stephanie Schulz
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, PA, USA
| | - Terry Hyslop
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, PA, USA
| | - Scott A Waldman
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, PA, USA
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13
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Mejia A, Schulz S, Hyslop T, Weinberg DS, Waldman SA. Molecular staging individualizing cancer management. J Surg Oncol 2012; 105:468-74. [PMID: 22441898 PMCID: PMC3312802 DOI: 10.1002/jso.21858] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Although the most important prognostic and predictive marker in colorectal cancer is tumor cells in lymph nodes, approximately 30% of patients who are node-negative die from occult metastases. Molecular staging employing specific markers and sensitive detection technologies has emerged as a powerful platform to assess prognosis in node-negative colon cancer. Integrating molecular staging into algorithms that individualize patient management will require validation and the definition of relationships between occult tumor cells, prognosis, and responses to chemotherapy.
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Affiliation(s)
- Alex Mejia
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson Unviersity,
| | - Stephanie Schulz
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson Unviersity,
| | - Terry Hyslop
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson Unviersity,
| | | | - Scott A. Waldman
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson Unviersity,
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14
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Fonteles MC, do Nascimento NRF. Guanylin peptide family: history, interactions with ANP, and new pharmacological perspectives. Can J Physiol Pharmacol 2011; 89:575-85. [PMID: 21815750 DOI: 10.1139/y11-050] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The guanylin family of peptides has 3 subclasses of peptides containing either 3 intramolecular disulfide bonds found in bacterial heat-stable enterotoxins (ST), or 2 disulfides observed in guanylin and uroguanylin, or a single disulfide exemplified by lymphoguanylin. These peptides bind to and activate cell-surface receptors that have intrinsic guanylate cyclase (GC) activity. These hormones are synthesized in the intestine and released both luminally and into the circulation, and are also produced within the kidney. Stimulation of renal target cells by guanylin peptides in vivo or ex vivo elicits a long-lived diuresis, natriuresis, and kaliuresis by both cGMP-dependent and independent mechanisms. Uroguanylin may act as a hormone in a novel endocrine axis linking the digestive system and kidney as well as a paracrine system intrarenally to increase sodium excretion in the postprandial period. This highly integrated and redundant mechanism allows the organism to maintain sodium balance by eliminating excess sodium in the urine. In addition, small concentrations of the atrial natriuretic peptide (ANP) can synergize with low concentrations of both guanylin or uroguanylin, which do not induce natriuresis per se, to promote significant natriuresis. Interestingly, the activation of the particulate guanylate cyclase receptors by natriuretic peptides can promote relaxation of animal and human penile erectile tissue and increase intracavernosal pressure to induce penile erection. These peptides can be prototypes for new drugs to treat erectile dysfunction, especially in patients with endothelial and nitrergic dysfunction, such as in diabetes.
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Affiliation(s)
- Manassés Claudino Fonteles
- Instituto Superior de Ciências Biomédicas (ISCB), Laboratório de Farmacologia - Universidade Estadual do Ceará (UECE), Avenida Paranjana 1700, Campus do Itaperi, CEP 60740-000, Fortaleza-CE, Brazil.
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15
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Lack of Restoration in Vivo by K-Channel Modulators of Jejunal Fluid Absorption after Heat Stable Escherichia coli Enterotoxin (STa) Challenge. J Trop Med 2011; 2011:853686. [PMID: 21760812 PMCID: PMC3134271 DOI: 10.1155/2011/853686] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2010] [Revised: 02/25/2011] [Accepted: 04/07/2011] [Indexed: 11/24/2022] Open
Abstract
Enhanced potassium ion permeability at the enterocyte basolateral membrane is assumed to facilitate sustained chloride ion and fluid secretion into the intestinal lumen during episodes of secretory diarrhoeal disease. To examine this concept in vivo, two potassium ion channel blockers and a channel opener were coperfused with E. coli heat stable STa enterotoxin to determine whether such compounds improved or worsened the inhibited fluid absorption. In the STa (80 ng/mL) challenged jejunal loop, the fluid absorption rate of 28.6 ± 5.8 (14) μL/cm/hr was significantly below (P < .001) the normal rate of 98.8 ± 6.2 (17) μL/cm/hr. Intraluminal (300 uM) glibenclamide added to STa perfused loops failed to improve the inhibited fluid absorption rate, which was 7.4 ± 3.2 (6) μL/cm/hr on coperfusion with STa. Similarly, on coperfusion with 30 uM clotrimazole, the fluid absorption rate with STa present remained inhibited at 11.4 ± 7.0 (4) μL/cm/hr. On coperfusion with intraluminal 1 uM cromakalim, STa reduced fluid absorption significantly (P < .02) to 24.7 ± 8.0 (10) μL/cm/hr, no different from STa challenge in the absence of cromakalim. Infusion i.v. with these agents also failed to restore fluid absorption after STa challenge. These observations do not support the proposed potassium ion permeability event as a necessary corollary of enterotoxin-mediated secretion. This makes it unlikely that modulators of such permeability prevent enterocyte secretion in diarrhoeal disease.
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16
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Mathias JR, Clench MH. Alterations of small intestine motility by bacteria and their enterotoxins. Compr Physiol 2011. [DOI: 10.1002/cphy.cp060131] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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17
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Bacterial heat-stable enterotoxins: translation of pathogenic peptides into novel targeted diagnostics and therapeutics. Toxins (Basel) 2010; 2:2028-54. [PMID: 22069671 PMCID: PMC3153287 DOI: 10.3390/toxins2082028] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2010] [Accepted: 08/03/2010] [Indexed: 12/13/2022] Open
Abstract
Heat-stable toxins (STs) produced by enterotoxigenic bacteria cause endemic and traveler’s diarrhea by binding to and activating the intestinal receptor guanylyl cyclase C (GC-C). Advances in understanding the biology of GC-C have extended ST from a diarrheagenic peptide to a novel therapeutic agent. Here, we summarize the physiological and pathophysiological role of GC-C in fluid-electrolyte regulation and intestinal crypt-villus homeostasis, as well as describe translational opportunities offered by STs, reflecting the unique characteristics of GC-C, in treating irritable bowel syndrome and chronic constipation, and in preventing and treating colorectal cancer.
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Mejia A, Schulz S, Hyslop T, Weinberg DS, Waldman SA. Molecular staging estimates occult tumor burden in colorectal cancer. Adv Clin Chem 2010; 52:19-39. [PMID: 21275338 PMCID: PMC7012399 DOI: 10.1016/s0065-2423(10)52007-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Tumor cells in regional lymph nodes are a key prognostic marker of survival and predictive marker of response to adjuvant chemotherapy in colorectal cancer. However, clinicopathologic techniques to detect lymph node metastases remain imperfect, and approximately 30% of patients with lymph nodes negative by histology (pN0) develop recurrent disease, reflecting occult metastases that escape detection. These observations underscore an unmet clinical need for accurate approaches to identify occult nodal metastases in colorectal cancer patients. GUCY2C is a receptor whose expression normally is restricted to intestinal epithelial cells, but is universally overexpressed by colorectal cancer cells. A prospective, multicenter, blinded clinical trial established the prognostic utility of GUCY2C qRT-PCR to detect occult nodal metastases in pN0 colorectal cancer patients. Molecular staging revealed that approximately 13% of pN0 patients were free of cancer cells, while approximately 87% had GUCY2C results that suggested occult metastases. The presence of occult nodal metastases was the most powerful independent predictor of time to recurrence and disease-free survival. These observations establish the utility of molecular detection of occult nodal metastases for assessing prognostic risk in pN0 colorectal cancer patients. Advancing GUCY2C into staging paradigms in clinical laboratories will require validation in independent patient populations, definition of the relationship between the quantity of occult tumor metastases and risk, and determination of the utility of GUCY2C qRT-PCR to identify pN0 patients who might benefit from adjuvant chemotherapy.
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Affiliation(s)
- Alex Mejia
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Stephanie Schulz
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Terry Hyslop
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - David S. Weinberg
- Department of Medicine, Fox Chase Cancer Center, Philadelphia, Pennsylvania, USA
| | - Scott A. Waldman
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
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Mejia A, Schulz S, Hyslop T, Weinberg DS, Waldman SA. GUCY2C reverse transcriptase PCR to stage pN0 colorectal cancer patients. Expert Rev Mol Diagn 2009; 9:777-85. [PMID: 19895223 PMCID: PMC2810399 DOI: 10.1586/erm.09.67] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The most important prognostic marker of survival and predictive marker of response to adjuvant chemotherapy in colon cancer patients is tumor cells in regional lymph nodes. Despite their importance, standard techniques to assess nodal metastases remain imperfect, as approximately 30% of patients with histology-negative lymph nodes (pN0) die of recurrent disease, reflecting occult metastases that escape detection. These observations highlight the clinical need for novel, accurate approaches to detect occult lymph node metastases in patients with colon cancer. GUCY2C is a biomarker whose expression normally is restricted to intestinal cells, but is near universally overexpressed by colorectal cancer cells. Recently, a prospective, multicenter, blinded clinical trial demonstrated for the first time that the prognostic utility of GUCY2C quantitative reverse transcriptase (qRT)-PCR to detect occult lymph node metastases in pN0 colorectal cancer patients. Molecular staging revealed that approximately 13% of pN0 patients were free of tumor cells, while approximately 87% had GUCY2C results that suggested occult metastases. The presence of occult lymph node metastases was the strongest independent predictor of time to recurrence and disease-free survival. These observations establish the utility of molecular detection of occult lymph node metastases for estimating prognostic risk in pN0 colorectal cancer patients. Advancing this molecular diagnostic into staging paradigms in clinical laboratories will require validation in independent patient populations, definition of the relationship between the quantity of occult tumor metastases and risk, and determination of the utility of GUCY2C qRT-PCR to identify pN0 patients who might benefit from adjuvant chemotherapy.
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Affiliation(s)
- Alex Mejia
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, 132 South 10th Street, 1170 Main, Philadelphia, PA 19107, USA
| | - Stephanie Schulz
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, 132 South 10th Street, 1170 Main, Philadelphia, PA 19107, USA
| | - Terry Hyslop
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, 132 South 10th Street, 1170 Main, Philadelphia, PA 19107, USA
| | - David S Weinberg
- Department of Medicine, Fox Chase Cancer Center, Philadelphia, PA, USA
| | - Scott A Waldman
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, 132 South 10th Street, 1170 Main, Philadelphia, PA 19107, USA, Tel.: +1 215 955 6086
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Guerrant RL. Microbial toxins and diarrhoeal diseases: introduction and overview. CIBA FOUNDATION SYMPOSIUM 2008; 112:1-13. [PMID: 3891253 DOI: 10.1002/9780470720936.ch1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Without question, diarrhoeal diseases constitute one of the greatest causes of morbidity and death on a global scale. To an increasingly recognized extent, they are caused by an expanding array of microbial products or "toxins'. The symposium focuses on microbial products that alter normal bowel function either by augmenting secretory pathways or by selectively destroying mucosal cells or pathways, thus leading to an imbalance in the concert of normal absorptive function that results in diarrhoea. An understanding of normal intestinal physiology is thus the key to unraveling the specific actions of microbial toxins. In many instances, the microbial toxins are themselves providing unique pharmacological tools with which to dissect normal intestinal function. Specifically, families of enterotoxins are reviewed that appear to cause secretion through the recognized second messengers of cyclic AMP and cyclic GMP as well as cyclic nucleotide-independent and calcium-dependent pathways. Potential "third messengers' such as the protein kinases, through which one or more of the second messengers may act, are also considered. We examine cytotoxins that alter the orchestrated function of specialized regions of intact intestinal mucosa by selectively impeding or killing certain cells, so leading to small intestinal or colonic pathology and contributing to diarrhoea. We also consider a wide range of recognized bacterial and parasitic agents and their enterotoxic products. In some instances, these toxins may strikingly resemble our own endogenous humoral regulators or hormones. At this point, the possible roles of viruses or other transmissible genome products in this area await further clarification. Finally, we examine pharmacological and immunological approaches to attacking the toxins themselves or the deranged physiology they cause, in order to approach the control of the potentially devastating diseases of diarrhoea.
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Weikel CS, Guerrant RL. STb enterotoxin of Escherichia coli: cyclic nucleotide-independent secretion. CIBA FOUNDATION SYMPOSIUM 2008; 112:94-115. [PMID: 2988879 DOI: 10.1002/9780470720936.ch6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Escherichia coli may produce a heat-labile enterotoxin (LT) or two heat-stable enterotoxins (STa, STb). Experimentally, STb is consistently active only in 5 h-weaned pig intestinal loops (WPIL), an effect that is largely removable by rinsing. At least three mechanisms initiate small intestinal secretion: cyclic AMP (LT), cyclic GMP (STa) and calcium (A23187). All three increase short-circuit current (SCC) in Ussing chambers by stimulating net Cl- secretion. STb significantly increases SCC within 2-5 minutes in Ussing chambers and is independent of cyclic AMP and cyclic GMP. When compared to crude culture filtrates of a non-toxigenic strain of E. coli, crude culture filtrates of STb did not alter Na+ or Cl- undirectional or net fluxes. However, the calculated residual ion flux (JRnet) increased significantly in STb-treated tissues and appeared to largely account for the STb-induced increase in SCC. Furosemide applied serosally (10(-3) M), the removal of extracellular calcium, and lanthanum chloride (10(-3) M) did not inhibit the effect of STb on SCC. Chlorpromazine (0.4 mM) completely inhibited STb-induced secretion in porcine loops. This inhibition was a non-specific reversal of the STb effect because in Ussing chambers, chlorpromazine simply induced an equal and opposite effect on SCC. These results indicate that STb initiates intestinal secretion in porcine jejunum in vitro by stimulating primarily non-chloride anion secretion in the absence of extracellular calcium. We postulate that STb causes bicarbonate secretion by a mechanism distinct from those of previously studied enterotoxins.
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Rao MC. Toxins which activate guanylate cyclase: heat-stable enterotoxins. CIBA FOUNDATION SYMPOSIUM 2008; 112:74-93. [PMID: 2861070 DOI: 10.1002/9780470720936.ch5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Certain enteropathogenic bacteria, including strains of Escherichia coli, Klebsiella pneumoniae and Yersinia enterocolitica, elicit their diarrhoeagenic effects by elaborating small molecular weight, heat-stable enterotoxins (STs). Structural and functional characteristics indicate that ST peptides are heterogeneous and two major subtypes, STa and STb, have been identified. Molecules of STa, unlike those of STb, are methanol-soluble and elicit their pathogenic effects by activating host cell guanylate cyclase activity and thereby increasing tissue cyclic GMP content: this increase in cyclic GMP causes fluid secretion. STa binds to specific proteinaceous receptors on intestinal cells but the nature of STa-receptor coupling to guanylate cyclase is poorly understood. The actions of STa, including binding to its receptor, activation of guanylate cyclase and stimulation of electrolyte transport, are rapid, reversible and tissue-specific. STa activates only particulate and not soluble guanylate cyclase. It alters the Vmax but not the apparent Km of this enzyme for Mg-GTP or Mn-GTP. At concentrations above 0.5-1 mM, calcium inhibits the STa activation of guanylate cyclase. The effects of calmodulin antagonists such as chlorpromazine on the activation of guanylate cyclase by STa are less clear. Inhibitors of phospholipid and arachidonic acid cascade pathways interfere with both basal and STa-stimulated guanylate cyclase. Membrane integrity is essential for STa activation of guanylate cyclase and the STa-receptor complex may activate the enzyme by intramembrane protein-protein interactions and/or perturbations. Interference with membrane phospholipid could alter such coupling.
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Browning DD. Protein kinase G as a therapeutic target for the treatment of metastatic colorectal cancer. Expert Opin Ther Targets 2008; 12:367-76. [PMID: 18269345 DOI: 10.1517/14728222.12.3.367] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Colorectal cancer is a leading cause of cancer-related death in the world and there is an urgent need for new strategies to combat this disease. Findings from several independent laboratories have converged on cGMP signaling as an exciting new therapeutic target, but the mechanisms remain controversial. A key intracellular effector of cGMP is protein kinase G (PKG). This article reviews the scientific literature concerning PKG effects on tumor development and progression, and discusses possible strategies for its exploitation in future cancer therapies. Studies from several independent laboratories have described novel anti-tumor effects of PKG in colon cancer cells that include inhibition of tumor growth and angiogenesis. While more preclinical research is warranted to better understand signaling mechanisms, these properties support the notion that PKG is a novel cancer target.
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Affiliation(s)
- Darren D Browning
- Medical College of Georgia, Department of Biochemistry and Molecular Biology, 1120 15th Street, CB2605, Augusta, GA 30912-2100, USA.
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Lucas ML, Thom MMM, Bradley JM, O'Reilly NF, McIlvenny TJ, Nelson YB. Escherichia coli Heat Stable (STa) Enterotoxin and the Upper Small Intestine: Lack of Evidence in Vivo for Net Fluid Secretion. J Membr Biol 2005; 206:29-42. [PMID: 16440179 DOI: 10.1007/s00232-005-0771-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2005] [Indexed: 10/25/2022]
Abstract
Heat stable (STa) enterotoxin from E. coli reduced fluid absorption in vivo in the perfused jejunum of the anaesthetized rat in Krebs-phosphate buffer containing lactate and glucose (nutrient buffer), in glucose saline and in glucose free saline. Bicarbonate ion enhanced fluid absorption of 98 +/- 7 (6) microl/cm/h was very significantly (P < 0.0001) reduced by STa to 19 +/- 4 (6) microl/cm/h, but net secretion was not found. When impermeant MES substituted for bicarbonate ion, net fluid absorption of 29 +/- 3 (6) microl/cm/h was less (P < 0.01) than the values for phosphate buffer and bicarbonate buffer. With STa in MES buffer, fluid absorption of 3 +/- 2 (6) microl/cm/h was less than (P < 0.001) that in the absence of STa and not significantly different from zero net fluid absorption. E. coli STa did not cause net fluid secretion in vivo under any of the above circumstances. Neither bumetanide nor NPPB when co-perfused with STa restored the rate of fluid absorption. In experiments with zero sodium ion-containing perfusates, STa further reduced fluid absorption modestly by 20 microl/cm/h. Perfusion of ethyl-isopropyl-amiloride (EIPA) with STa in zero sodium ion buffers prevented the small increment in fluid entry into the lumen caused by STa, indicating that the STa effect was attributable to residual sodium ion and fluid uptake that zero sodium-ion perfusates did not eradicate. These experiments, using a technique that directly measures mass transport of fluid into and out of the in vivo proximal jejunum, do not support the concept that E. coli STa acts by stimulating a secretory response.
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Affiliation(s)
- M L Lucas
- Laboratory of Gastrointestinal Physiology, Division of Neuroscience & Biomedical Systems, Institute of Biological & Medical Science, Glasgow University, Glasgow, G12 8QQ, Scotland, Great Britain.
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Fava TA, Desnoyers R, Schulz S, Park J, Weinberg D, Mitchell E, Waldman SA. Ectopic expression of guanylyl cyclase C in CD34+ progenitor cells in peripheral blood. J Clin Oncol 2001; 19:3951-9. [PMID: 11579116 DOI: 10.1200/jco.2001.19.19.3951] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
PURPOSE To examine the utility of guanylyl cyclase C (GC-C)-specific nested reverse transcriptase polymerase chain reaction (RT-PCR) to detect circulating tumor cells in patients with colorectal cancer. PATIENTS AND METHODS Peripheral-blood mononuclear cells from 24 patients with Dukes' stage D colorectal cancer were analyzed by GC-C-specific nested RT-PCR using 1 microg of total RNA. Peripheral-blood mononuclear cells from 20 healthy volunteers served as controls. Additionally, peripheral-blood CD34+ progenitor cells were assayed for the expression of both GC-C and other epithelial cell-specific markers. RESULTS GC-C mRNA was detected in blood mononuclear cells from all 24 patients with colorectal cancer and all healthy volunteers. These unexpected positive results reflected low-level ectopic transcription of GC-C in CD34+ progenitor cells. Moreover, CD34+ progenitor cells expressed other epithelial cell-specific markers, including prostate-specific antigen, prostate-specific membrane antigen, carcinoembryonic antigen, CK-19, CK-20, mucin 1, and GA733.2. Limiting the quantity of mononuclear cell total RNA analyzed to < or = 0.8 microg eliminated detection of GC-C and other tissue-specific transcripts in blood of healthy volunteers. However, under the same conditions, GC-C mRNA was detected in mononuclear cells from all 24 patients with metastatic colorectal cancer. Using 0.5 microg of total RNA and GC-C-specific primers, nested RT-PCR detected a single human colon carcinoma cell (approximately 20 to 200 GC-C transcripts/cell) in 10(6) to 10(7) mononuclear blood cells. CONCLUSION These data suggest that GC-C may be useful for detecting circulating colorectal cancer cells. They also demonstrate that CD34+ cells are a source of ectopically expressed epithelial cell-specific markers and that CD34+ cells may contribute to the high false-positive rate generally observed when those markers are used to detect rare circulating metastatic cancer cells by RT-PCR.
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MESH Headings
- Adult
- Aged
- Antigens, CD34/blood
- Biomarkers, Tumor/blood
- Biomarkers, Tumor/genetics
- Carcinoembryonic Antigen/blood
- Colorectal Neoplasms/blood
- Colorectal Neoplasms/enzymology
- Colorectal Neoplasms/pathology
- Epithelial Cells/enzymology
- Female
- Granulocyte Colony-Stimulating Factor/therapeutic use
- Guanylate Cyclase/biosynthesis
- Guanylate Cyclase/blood
- Guanylate Cyclase/genetics
- Hematopoietic Stem Cells/enzymology
- Humans
- Leukocytes, Mononuclear/enzymology
- Male
- Middle Aged
- Neoplasm Metastasis
- Neoplasm Staging
- Neoplastic Cells, Circulating/metabolism
- RNA, Messenger/blood
- Receptors, Enterotoxin
- Receptors, Guanylate Cyclase-Coupled
- Receptors, Peptide/biosynthesis
- Receptors, Peptide/blood
- Receptors, Peptide/genetics
- Reverse Transcriptase Polymerase Chain Reaction
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Affiliation(s)
- T A Fava
- Division of Clinical Pharmacology, and Department of Medicine, Thomas Jefferson University, Philadelphia, PA, USA
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Pitari GM, Di Guglielmo MD, Park J, Schulz S, Waldman SA. Guanylyl cyclase C agonists regulate progression through the cell cycle of human colon carcinoma cells. Proc Natl Acad Sci U S A 2001; 98:7846-51. [PMID: 11438734 PMCID: PMC35430 DOI: 10.1073/pnas.141124698] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The effects of Escherichia coli heat-stable enterotoxin (ST) and uroguanylin were examined on the proliferation of T84 and Caco2 human colon carcinoma cells that express guanylyl cyclase C (GC-C) and SW480 human colon carcinoma cells that do not express this receptor. ST or uroguanylin inhibited proliferation of T84 and Caco2 cells, but not SW480 cells, in a concentration-dependent fashion, assessed by quantifying cell number, cell protein, and [(3)H]thymidine incorporation into DNA. These agonists did not inhibit proliferation by induction of apoptosis, assessed by TUNEL (terminal deoxynucleotidyl transferase-mediated dNTP-biotin nick end labeling of DNA fragments) assay and DNA laddering, or necrosis, assessed by trypan blue exclusion and lactate dehydrogenase release. Rather, ST prolonged the cell cycle, assessed by flow cytometry and [(3)H]thymidine incorporation into DNA. The cytostatic effects of GC-C agonists were associated with accumulation of intracellular cGMP, mimicked by the cell-permeant analog 8-Br-cGMP, and reproduced and potentiated by the cGMP-specific phosphodiesterase inhibitor zaprinast but not the inactive ST analog TJU 1-103. Thus, GC-C agonists regulate the proliferation of intestinal cells through cGMP-dependent mechanisms by delaying progression of the cell cycle. These data suggest that endogenous agonists of GC-C, such as uroguanylin, may play a role in regulating the balance between epithelial proliferation and differentiation in normal intestinal physiology. Therefore, GC-C ligands may be novel therapeutic agents for the treatment of patients with colorectal cancer.
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Affiliation(s)
- G M Pitari
- Division of Clinical Pharmacology, Department of Medicine, Thomas Jefferson University, 132 South 10th Street, 1170 Main, Philadelphia, PA 19107, USA.
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Al-Majali AM, Asem EK, Lamar CH, Robinson JP, Freeman MJ, Saeed AM. Studies on the mechanism of diarrhoea induced by Escherichia coli heat-stable enterotoxin (STa) in newborn calves. Vet Res Commun 2000; 24:327-38. [PMID: 10868550 DOI: 10.1023/a:1006444105846] [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: 11/12/2022]
Abstract
Enterotoxigenic Escherichia coli (ETEC) produces a heat-stable enterotoxin (STa) that binds to and activates a putative intestinal receptor, guanylate cyclase, causing an increase in the intracellular levels of cyclic guanosine monophosphate (cGMP). Using flow cytometry and 125I-STa binding assays, we studied the distribution of STa-receptors on enterocytes isolated from different segments of the newborn calf's intestinal tract. We also investigated the effect of STa on the intracellular levels of cGMP and ion transport to the intestinal lumen. More STa-receptors were found on enterocytes prepared from the ileum than on enterocytes obtained from the other segments of the intestinal tract. Guanylate cyclase activity was higher in the ileum of STa-challenged calves than in the ileum of control calves. No changes were observed in the guanylate cyclase activity of the other intestinal segments of the STa-challenged and control calves. Na+ levels, as measured by atomic absorption spectroscopy, were significantly increased in the luminal contents of the ileum of STa-challenged calves, whereas serum Cl- levels were significantly lower in the STa-challenged calves than in control calves. This study supports previous observations on the role of guanylate cyclase in the initiation of STa-induced secretory diarrhoea and suggests that Na+/Cl- coupling may be the major mechanism for the loss of ions in the diarrhoeal response that is mostly induced in the ileum of newborn calves.
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Affiliation(s)
- A M Al-Majali
- Department of Veterinary Pathobiology, School of Veterinary Medicine, Purdue University, West Lafayette, Indiana 47907, USA
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Guerrant RL, Lima AA, Barboza M, Young S, Silva T, Barrett L, Bao Y, Fox J, Moore S. Mechanisms and impact of enteric infections. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2000; 473:103-12. [PMID: 10659347 DOI: 10.1007/978-1-4615-4143-1_8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
The increased recognition of both old and new enteric pathogens and their potential impact requires an improved understanding of pathogenesis and effective interventions. While the overwhelming mortality (> 3 million children per year) due to diarrheal diseases is well-recognized, the potential long-term impacts of enteric infections and early childhood diarrhea morbidity are just beginning to be appreciated. Furthermore, several enteric infections are now being recognized as causes of growth shortfalls with or without diarrhea; i.e., malnutrition may be one of the greatest yet of the "emerging infectious diseases." The increased appreciation of this extended impact calls for further quantification and improved understanding of the deranged physiology. In particular, persistent diarrheal illnesses exhibit common themes of blunted villi, disruption of intestinal barrier function and varying degrees of sub-mucosal inflammation for which lactulose/mannitol permeability and fecal lactoferrin provide respective quantification. Finally, such improved understanding will allow targeted interventions among those most vulnerable, which will enable further documentation of cost effectiveness and the potential for improved human development which is critical to reducing the widening disparity and population overgrowth which increasingly threaten our global security.
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Affiliation(s)
- R L Guerrant
- Division of Geographic and International Medicine, University of Virginia, Charlottesville, USA
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al-Majali AM, Robinson JP, Asem EK, Lamar C, Freeman MJ, Saeed AM. Age-dependent variation in the density and affinity of Escherichia coli heat-stable enterotoxin receptors in mice. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2000; 473:137-45. [PMID: 10659351 DOI: 10.1007/978-1-4615-4143-1_12] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
Enterotoxigenic strains of Escherichia coli that produce heat-stable enterotoxin (STa), are a major cause of diarrheal disease worldwide. Resistance to diarrheal disease in human infants and newborn animals has been attributed to a gradual turnover in the intestinal brush border membrane receptors to bacterial pili. In this study, we demonstrated age-dependent variation in the density and affinity of the mouse enterocyte receptors specific for STa. Flow cytometry and radiolabeled-STa (125I-STa) assays were used as more reliable quantitative measures for the characterization of STa-enterocyte receptor interaction. These assays indicated a stronger interaction of STa with its putative receptor on the enterocytes of the 2-day-old suckling mice than with enterocytes from 1-week, 2-week and 2-month-old mice. Scatchard plot analysis of 125I-STa-receptor interaction suggested that STa-receptors exist at a higher number on enterocytes from the 2-day-old mice than enterocytes of the older mice. Additionally, receptors from the 2-day-old mice had a greater affinity for STa ligand than receptors from the older mice. Density of STa receptors on enterocytes and their affinity to STa may determine the extent of binding and severity of secretory response. This may further explain the increased susceptibility of newborn animals and human infants to STa-mediated diarrheal disease.
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Affiliation(s)
- A M al-Majali
- Department of Veterinary Pathobiology, School of Veterinary Medicine, Purdue University, West Lafayette, Indiana 47907, USA
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Batisson I, der Vartanian M. Extracellular DsbA-insensitive folding of Escherichia coli heat-stable enterotoxin STa in vitro. J Biol Chem 2000; 275:10582-9. [PMID: 10744753 DOI: 10.1074/jbc.275.14.10582] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To study the folding of human Escherichia coli heat-stable enterotoxin STh, we used the major protein subunit of CS31A fimbriae (ClpG) as a marker of STh secretion and a provider of a signal peptide. We established that STh genetically fused to the N or C terminus of ClpG was able to mobilize ClpG to the culture supernatant while still retaining full enterotoxicity. These features indicate that the STh activity was not altered by the chimeric structure and suggest that spatial conformation of STh in the fusion is close to that of the native toxin, thus permitting recognition and activation of the intestinal STh receptor in vivo. In contrast to other studies, we showed that disulfide bond formation did not occur in the periplasm through the DsbA pathway and that there was no correlation between DsbA and secretion, folding, or activity. This discrepancy was not attributable to the chimeric nature of STh since there was no effect of dsbA or dsbB mutations on secretion and activity of recombinant STh from which ClpG had been deleted. Periplasmic and lysate fractions of dsbA(+) and dsbA(-) cells did not have any STh activity. In addition, the STh chimera was exclusively found in an inactive reduced form intracellularly and in an active oxidized form extracellularly, irrespective of the dsbA background. Subsequently, a time course experiment in regard to the secretion of STh from both dsbA(+) and dsbA(-) cells indicated that the enterotoxin activity (proper folding) in the extracellular milieu increased with time. Overall, these findings provide evidence that STa toxins can be cell-released in an unfolded state before being completely disulfide-bonded outside the cell.
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Affiliation(s)
- I Batisson
- Laboratoire de Microbiologie, Institut National de la Recherche Agronomique, Centre de Recherches de Clermont-Ferrand-Theix, 63122 Saint-Genès-Champanelle, France
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London RM, Eber SL, Visweswariah SS, Krause WJ, Forte LR. Structure and activity of OK-GC: a kidney receptor guanylate cyclase activated by guanylin peptides. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:F882-91. [PMID: 10362777 DOI: 10.1152/ajprenal.1999.276.6.f882] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Uroguanylin, guanylin, and lymphoguanylin are small peptides that activate renal and intestinal receptor guanylate cyclases (GC). They are structurally similar to bacterial heat-stable enterotoxins (ST) that cause secretory diarrhea. Uroguanylin, guanylin, and ST elicit natriuresis, kaliuresis, and diuresis by direct actions on kidney GC receptors. A 3,762-bp cDNA characterizing a uroguanylin/guanylin/ST receptor was isolated from opossum kidney (OK) cell RNA/cDNA. This kidney cDNA (OK-GC) encodes a mature protein containing 1,049 residues sharing 72.4-75.8% identity with rat, human, and porcine forms of intestinal GC-C receptors. COS or HEK-293 cells expressing OK-GC receptor protein were activated by uroguanylin, guanylin, or ST13 peptides. The 3.8-kb OK-GC mRNA transcript is most abundant in the kidney cortex and intestinal mucosa, with lower mRNA levels observed in urinary bladder, adrenal gland, and myocardium and with no detectable transcripts in skin or stomach mucosa. We propose that OK-GC receptor GC participates in a renal mechanism of action for uroguanylin and/or guanylin in the physiological regulation of urinary sodium, potassium, and water excretion. This renal tubular receptor GC may be a target for circulating uroguanylin in an endocrine link between the intestine and kidney and/or participate in an intrarenal paracrine mechanism for regulation of kidney function via the intracellular second messenger, cGMP.
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Affiliation(s)
- R M London
- Department of Pharmacology, School of Medicine, Missouri University, Columbia, Missouri 65212, USA.
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Forte LR. Guanylin regulatory peptides: structures, biological activities mediated by cyclic GMP and pathobiology. REGULATORY PEPTIDES 1999; 81:25-39. [PMID: 10395405 DOI: 10.1016/s0167-0115(99)00033-6] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The guanylin family of bioactive peptides consists of three endogenous peptides, including guanylin, uroguanylin and lymphoguanylin, and one exogenous peptide toxin produced by enteric bacteria. These small cysteine-rich peptides activate cell-surface receptors, which have intrinsic guanylate cyclase activity, thus modulating cellular function via the intracellular second messenger, cyclic GMP. Membrane guanylate cyclase-C is an intestinal receptor for guanylin and uroguanylin that is responsible for stimulation of Cl- and HCO3- secretion into the intestinal lumen. Guanylin and uroguanylin are produced within the intestinal mucosa to serve in a paracrine mechanism for regulation of intestinal fluid and electrolyte secretion. Enteric bacteria secrete peptide toxin mimics of uroguanylin and guanylin that activate the intestinal receptors in an uncontrolled fashion to produce secretory diarrhea. Opossum kidney guanylate cyclase is a key receptor in the kidney that may be responsible for the diuretic and natriuretic actions of uroguanylin in vivo. Uroguanylin serves in an endocrine axis linking the intestine and kidney where its natriuretic and diuretic actions contribute to the maintenance of Na+ balance following oral ingestion of NaCl. Lymphoguanylin is highly expressed in the kidney and myocardium where this unique peptide may act locally to regulate cyclic GMP levels in target cells. Lymphoguanylin is also produced in cells of the lymphoid-immune system where other physiological functions may be influenced by intracellular cyclic GMP. Observations of nature are providing insights into cellular mechanisms involving guanylin peptides in intestinal diseases such as colon cancer and diarrhea and in chronic renal diseases or cardiac disorders such as congestive heart failure where guanylin and/or uroguanylin levels in the circulation and/or urine are pathologically elevated. Guanylin peptides are clearly involved in the regulation of salt and water homeostasis, but new findings indicate that these novel peptides have diverse physiological roles in addition to those previously documented for control of intestinal and renal function.
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Affiliation(s)
- L R Forte
- The Harry S. Truman Memorial V.A. Hospital, Columbia, MO 65212, USA.
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Rousset E, Harel J, Dubreuil JD. Binding characteristics of Escherichia coli enterotoxin b (STb) to the pig jejunum and partial characterization of the molecule involved. Microb Pathog 1998; 24:277-88. [PMID: 9600860 DOI: 10.1006/mpat.1997.0193] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Escherichia coli heat-stable enterotoxin b (STb) causes severe diarrhoea in weaning piglets. STb most probably has to bind to intestinal epithelial cells in order to achieve its effect. Using biotinylated biologically active STb, we developed a semi-quantitative binding assay using indirect fluorescence microscopy. We demonstrated the attachment of the biotinylated toxin to microvilli of the pig jejunum. However, binding was abolished when biotinylated STb was either boiled or treated with 2-mercaptoethanol, treatments known to abolish biological activity. Different characteristics of STb attachment to the pig small intestine were determined. The reaction was rapid and reached maximum intensity after approximately 10 min. The binding was pH dependent showing an optimum at pH 5.8. Incubation at either 4 degrees C, 25 degrees C or 37 degrees C did not affect the binding. No competition was observed with non-biotinylated STb. However, preincubation of biotinylated STb with streptavidin conjugated to horseradish peroxidase completely abolished the binding. Pig tissues other than jejunum demonstrated binding towards STb including duodenum, ileum, caecum, colon, liver, lung, spleen and kidney. The molecule involved was then partially characterized. Metaperiodate treatment of the jejunum sections abrogated binding but protease treatment had no effect. Enzymatic treatments of jejunal sections demonstrated that N- and O-glycosidases, and several exoglycosidases did not affect binding, whereas reduced binding was observed with ceramide glycanase and alpha-glucosidase, and was completely abolished following neuraminidase treatment. Overall, our results suggest that in vitro STb binding was rapid, pH dependent, temperature independent, not restricted to jejunum and involves a molecule that seems to be composed of a ceramide moiety, terminal neuraminic acid and/or alpha-linked terminal glucose residue(s).
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Affiliation(s)
- E Rousset
- Groupe de recherche sur les malades infectieuses du porc (GREMIP), Département de pathologie et microbiologie, Faculté de médecine vétérinaire, Université de Montréal, C. P. 5000, Saint-Hyacinthe, Québec, J2S 7C6, Canada
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Affiliation(s)
- G B Nair
- National Institute of Cholera and Enteric Diseases, P-33, CIT Road, Scheme XM, Beliaghata, Box-177, Calcutta-700010, India
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Schulz S, Lopez MJ, Kuhn M, Garbers DL. Disruption of the guanylyl cyclase-C gene leads to a paradoxical phenotype of viable but heat-stable enterotoxin-resistant mice. J Clin Invest 1997; 100:1590-5. [PMID: 9294128 PMCID: PMC508341 DOI: 10.1172/jci119683] [Citation(s) in RCA: 126] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Heat-stable enterotoxins (STa), which cause an acute secretory diarrhea, have been suggested to mediate their actions through the guanylyl cyclase-C (GC-C) receptor. The GC-C gene was disrupted by insertion of neo into exon 1 and subsequent homologous recombination. GC-C null mice contained no detectable GC-C protein. Intestine mucosal guanylyl cyclase activity was approximately 16-fold higher in wild-type mice than in the GC-C null mice, and STa-stimulable guanylyl cyclase activity was absent in the null animals. Thus, GC-C is the major cyclase activity present in the intestine, and also completely accounts for the STa-induced elevations of cGMP. Gavage with STa resulted in marked fluid accumulation within the intestine of wild-type and heterozygous suckling mice, but GC-C null animals were resistant. In addition, infection with enterotoxigenic bacteria that produce STa led to diarrhea and death in wild-type and heterozygous mice, while the null mice were protected. Cholera toxin, in contrast, continued to cause diarrhea in GC-C null mice, demonstrating that the cAMP signaling pathway remained intact. Markedly different diets (high carbohydrate, fat, or protein) or the inclusion of high salt (K+, Na+) in the drinking water or diet also did not severely affect the null animals. Given that GC-C is a major intestinal receptor in all mammals, the pressure to retain a functional GC-C in the face of diarrhea-inflicted mortality remains unexplained. Therefore, GC-C likely provides a protective effect against stressors not yet tested, possibly pathogens other than noninvasive enterotoxigenic bacteria.
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MESH Headings
- Animals
- Animals, Newborn
- Blotting, Southern
- Blotting, Western
- Body Weight/drug effects
- Cells, Cultured
- Cholera Toxin/pharmacology
- Enterotoxins/pharmacology
- Escherichia coli/pathogenicity
- Food, Formulated
- Guanylate Cyclase/genetics
- Guanylate Cyclase/metabolism
- Guanylate Cyclase/physiology
- Intestinal Mucosa/enzymology
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Receptors, Enterotoxin
- Receptors, Guanylate Cyclase-Coupled
- Receptors, Peptide/genetics
- Receptors, Peptide/physiology
- Sodium Chloride, Dietary/pharmacology
- Survival Rate
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Affiliation(s)
- S Schulz
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas 75235-9050, USA
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38
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Carrithers SL, Barber MT, Biswas S, Parkinson SJ, Park PK, Goldstein SD, Waldman SA. Guanylyl cyclase C is a selective marker for metastatic colorectal tumors in human extraintestinal tissues. Proc Natl Acad Sci U S A 1996; 93:14827-32. [PMID: 8962140 PMCID: PMC26221 DOI: 10.1073/pnas.93.25.14827] [Citation(s) in RCA: 159] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Guanylyl cyclase C (GCC) has been detected only in intestinal mucosa and colon carcinoma cells of placental mammals. However, this receptor has been identified in several tissues in marsupials, and its expression has been suggested in tissues other than intestine in placental mammals. Selective expression of GCC by colorectal tumor cells in extraintestinal tissues would permit this receptor to be employed as a selective marker for metastatic disease. Thus, expression of GCC was examined in human tissues and tumors, correlating receptor function with detection by PCR. GCC was detected by ligand binding and catalytic activation in normal intestine and primary and metastatic colorectal tumors, but not in extraintestinal tissues or tumors. Similarly, PCR yielded GCC-specific amplification products with specimens from normal intestine and primary and metastatic colorectal tumors, but not from extraintestinal tissues or tumors. Northern blot analysis employing GCC-specific probes revealed an approximately 4-kb transcript, corresponding to recombinant GCC, in normal intestine and primary and metastatic colorectal tumors, but not in extraintestinal tissues. Thus, GCC is selectively expressed in intestine and colorectal tumors in humans and appears to be a relatively specific marker for metastatic cancer cells in normal tissues. Indeed, PCR of GCC detected tumor cells in blood from some patients with Dukes B colorectal cancer and all patients examined with Dukes C and D colorectal cancer, but not in that from normal subjects or patients with Dukes A colon carcinoma or other nonmalignant intestinal pathologies.
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Affiliation(s)
- S L Carrithers
- Department of Medicine, Thomas Jefferson University, Philadelphia, PA 19107, USA
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39
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Parkinson SJ, Waldman SA. An intracellular adenine nucleotide binding site inhibits guanyly cyclase C by a guanine nucleotide-dependent mechanism. Biochemistry 1996; 35:3213-21. [PMID: 8605156 DOI: 10.1021/bi9524326] [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: 01/31/2023]
Abstract
Guanylyl cyclase C (GCC), the receptor for the Escherichia coli heat-stable enterotoxin (ST), is inhibited by 2-substituted adenine nucleotides in an allosteric fashion. In confluent cultures of Caco-2 intestinal epithelial cells, extracellular 2-methylthioadenosine triphosphate (2MeSATP) had no effect on basal or ST-stimulated cyclic GMP (cGMP) accumulation. However, this nucleotide inhibited cGMP accumulation in digitonin-permeabilized Caco-2 human colon carcinoma cells, demonstrating that allosteric inhibition of GCC by adenine nucleotides is mediated by an intracellular adenine nucleotide binding site rather than purinergic receptors. The role of guanine nucleotides in the regulation of GCC by adenine nucleotides was examined. Increasing GTP concentrations from 5 to 100 microM increased the potency of 2MeSATP inhibition of GCC 20-fold, with a shift in the Ki from 447 to 22 microM, respectively. Also, the hydrolysis-resistant analogue, guanosine 5'-O-(3-thiotriphosphate) (GTPgammaS), supported 2MeSATP inhibition of GCC with a potency which was 10-fold greater than GTP. In addition, GTP alone, in the absence of adenine nucleotides and at concentrations greater than 1 mM, inhibited GCC through a mechanism convergent with 2MeSATP. Guanine nucleotides supported adenine nucleotide inhibition of GCC at low concentrations and directly inhibited this enzyme at high concentrations when these studies were conducted with receptors expressed in Caco-2 cells, native rat intestine, or cloned rat GCC heterologously expressed in 293 monkey kidney cells. These observations demonstrate that adenine nucleotide inhibition of GCC is mediated through an intracellular mechanism which is guanine nucleotide-dependent.
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Affiliation(s)
- S J Parkinson
- Department of Medicine, Division of Clinical Pharmacology, Thomas Jefferson University, Phildelphia, Pennsylvania 19107, USA
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40
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Carrithers SL, Parkinson SJ, Goldstein SD, Park PK, Urbanski RW, Waldman SA. Escherichia coli heat-stable enterotoxin receptors. A novel marker for colorectal tumors. Dis Colon Rectum 1996; 39:171-81. [PMID: 8620784 DOI: 10.1007/bf02068072] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
PURPOSE Receptors for Escherichia coli heat-stable toxin (ST) are selectively expressed in membranes of intestinal mucosa cells and colon carcinoma cells in vitro, suggesting their use as a marker for colorectal tumors in vivo. The present studies examined the expression and function of ST receptors in normal human tissues and primary and metastatic colorectal tumors obtained from patients at surgery. METHODS Surgical specimens were obtained as follows: from normal colon; from primary adenocarcinomas from all anatomic divisions of the colon and rectum; from gallbladder, kidney, liver, lung, lymph node, ovary, peritoneum, stomach; and from colon carcinomas metastatic to liver, lung, lymph node, ovary, and peritoneum. Membranes prepared from these specimens were assessed for the presence and functional characteristics of ST receptors. RESULTS ST bound specifically to membranes from each division of normal colon and rectum and all primary and metastatic colorectal tumors examined. The affinity and density of ST receptors were similar in tumors of different grades and from various metastatic sites. ST-receptor interaction was coupled to activation of guanylyl cyclase in all normal samples of colon and rectum and all primary and metastatic colorectal tumors examined. In contrast, neither ST binding nor ST activation of guanylyl cyclase was detected in any extraintestinal tissues examined. CONCLUSIONS Functional ST receptors are expressed in normal colonic tissue and primary and metastatic colorectal tumors but not by extraintestinal tissues in humans. Expression of ST receptors does not vary as a function of the metastatic site or grade of these tumors. Receptors expressed by colorectal tumors retain their characteristic function, with binding of ST coupled to activation of guanylyl cyclase. These studies support the suggestion that ST receptors represent a specific marker for human colorectal tumors that may have use as a target for directing diagnostics and therapeutics to these tumors in vivo.
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Affiliation(s)
- S L Carrithers
- Department of Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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41
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Arriaga YL, Harville BA, Dreyfus LA. Contribution of individual disulfide bonds to biological action of Escherichia coli heat-stable enterotoxin B. Infect Immun 1995; 63:4715-20. [PMID: 7591127 PMCID: PMC173676 DOI: 10.1128/iai.63.12.4715-4720.1995] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Heat-stable enterotoxins (STs) of Escherichia coli are peptides which alter normal gut physiology by stimulating the loss of water and electrolytes. The action of heat-stable toxin B (STb) is associated with an increase in levels of lumenal 5-hydroxytryptamine and prostaglandin E2, known mediators of intestinal secretion. In addition, the toxin is responsible for elevation of cytosolic calcium ion levels in cultured cells. STb is a 48-amino-acid basic peptide containing four cysteine residues and two disulfide bonds. Previous work indicates that disulfide bonds are required for intestinal secretory activity, and yet the relative contribution of the two bonds to toxin stability and action is presently unclear. Site-directed mutagenesis was used to alter the cysteine residues of STb to assess the role of the individual disulfide bonds in toxin activity. Our results indicate that loss of a single disulfide bond was sufficient to abolish the intestinal secretory and G protein-coupled calcium ion influx activities associated with STb toxicity. Loss of toxin action was not a function of increased sensitivity of STb mutants to proteolysis, since mutant toxins displayed proteolytic decay rates equivalent to that of wild-type STb. Circular dichroism spectroscopy of mutant STb toxins indicated that single-disulfide-bond elimination did not apparently affect the toxin secondary structure of one mutant, STbC33S,C71S. In contrast, the alpha-helical content of the other disulfide bond mutant, STbC44S,C59G, was significantly altered, as was that of reduced and alkylated authentic STb. Since both Cys-Cys mutant STbs were completely nontoxic, the absence of biological activity cannot be explained by dramatic secondary structural changes alone; keys to the conformational requirements for STb toxicity undoubtedly reside in the three-dimensional structure of this peptide.
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Affiliation(s)
- Y L Arriaga
- Division of Cell Biology and Biophysics, School of Biological Sciences, University of Missouri, Kansas City 64110, USA
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42
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Klimpel GR, Chopra AK, Langley KE, Wypych J, Annable CA, Kaiserlian D, Ernst PB, Peterson JW. A role for stem cell factor and c-kit in the murine intestinal tract secretory response to cholera toxin. J Exp Med 1995; 182:1931-42. [PMID: 7500039 PMCID: PMC2192260 DOI: 10.1084/jem.182.6.1931] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The role of stem cell factor (SCF) and its receptor (c-kit) in the intestinal secretory response to cholera toxin (CT) was investigated using a ligated intestinal loop model in mice having mutations in the dominant white spotting (W) locus and the steel (Sl) locus. W/Wv mice, which express an aberrant form of the c-kit protein, failed to give an intestinal secretory response after luminal CT challenge. In contrast, W/Wv mice and their control littermates had equivalent intestinal secretory responses to Escherichia coli heat-stable enterotoxin (STa). Sl/Sld mice, which express only a soluble truncated form of SCF, also gave a significantly reduced intestinal secretory response to CT when compared to the secretory response of their littermate controls. The unresponsiveness of W/Wv mice to CT was restricted to the intestinal tract since these mice had foot pad swelling responses to CT challenge that were equivalent to their littermate controls. Restoration of mast cells in W/Wv mice by bone marrow transplantation of control littermate bone marrow did not reverse the CT-unresponsiveness of the intestinal tract. Histological evaluation of the gastrointestinal tract from W/Wv mice showed a normal distribution of enterochromaffin cells (ECC). CT challenge of either ligated intestinal loops from C57B1/6 mice or a mouse intestinal epithelial cell line (MODE-K) resulted in elevated levels of mRNA for SCF. MODE-K cells exposed to CT also had enhanced expression of c-kit. Finally, fluid obtained from CT-challenged ligated intestinal loops from C57B1/6 mice contained significant levels of SCF. Taken together, the above results suggest that CT-induced intestinal secretory responses are dependent upon SCF-c-kit interactions. These interactions appear to be induced as a consequence of CT stimulation of the intestinal tract and may also play a role in the development or functionality of the enteric nervous system.
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Affiliation(s)
- G R Klimpel
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston 77555-1019, USA
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Li Z, Taylor-Blake B, Light AR, Goy MF. Guanylin, an endogenous ligand for C-type guanylate cyclase, is produced by goblet cells in the rat intestine. Gastroenterology 1995; 109:1863-75. [PMID: 7498651 DOI: 10.1016/0016-5085(95)90753-x] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
BACKGROUND & AIMS Guanylin activates an intestinal guanylate cyclase (GCC) and stimulates electrolyte movement across the gut epithelium. Cells expressing guanylin messenger RNA have been localized to the epithelial cell layer of the intestine; however, the identity of the guanylin-producing cells has not been determined. The aim of this study was to identify cells that express guanylin in the rat intestine. METHODS Antibodies were raised against defined proguanylin epitopes, evaluated by Western blotting, and used for immunoperoxidase histochemistry. RESULTS Guanylin-like immunoreactivity was localized to a subset of goblet cells. In the small intestine, most, perhaps all, goblet cells in the villi were immunopositive, as were some goblet cells in upper crypts; however, goblet cells deep within crypts were unlabeled. In the colon, goblet cells clustered in the necks and around the openings of crypts were immunopositive, whereas (as in the small intestine) goblet cells in deeper crypt regions were unlabeled. In some animals, immunoreactive columnar epithelial cells were also observed in the colon (although such cells were not apparent in the small intestine). Relative labeling of columnar cells varied from animal to animal. CONCLUSIONS Guanylin is expressed in mature goblet cells. If secreted in conjunction with mucin, it could play a role in the hydration of mucus.
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Affiliation(s)
- Z Li
- Department of Physiology, University of North Carolina, Chapel Hill, USA
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Sukumar M, Rizo J, Wall M, Dreyfus LA, Kupersztoch YM, Gierasch LM. The structure of Escherichia coli heat-stable enterotoxin b by nuclear magnetic resonance and circular dichroism. Protein Sci 1995; 4:1718-29. [PMID: 8528070 PMCID: PMC2143221 DOI: 10.1002/pro.5560040907] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The heat-stable enterotoxin b (STb) is secreted by enterotoxigenic Escherichia coli that cause secretory diarrhea in animals and humans. It is a 48-amino acid peptide containing two disulfide bridges, between residues 10 and 48 and 21 and 36, which are crucial for its biological activity. Here, we report the solution structure of STb determined by two- and three-dimensional NMR methods. Approximate interproton distances derived from NOE data were used to construct structures of STb using distance-geometry and simulated annealing procedures. The NMR-derived structure shows that STb is helical between residues 10 and 22 and residues 38 and 44. The helical structure in the region 10-22 is amphipathic and exposes several polar residues to the solvent, some of which have been shown to be important in determining the toxicity of STb. The hydrophobic residues on the opposite face of this helix make contacts with the hydrophobic residues of the C-terminal helix. The loop region between residues 21 and 36 has another cluster of hydrophobic residues and exposes Arg 29 and Asp 30, which have been shown to be important for intestinal secretory activity. CD studies show that reduction of disulfide bridges results in a dramatic loss of structure, which correlates with loss of function. Reduced STb adopts a predominantly random-coil conformation. Chromatographic measurements of concentrations of native, fully reduced, and single-disulfide species in equilibrium mixtures of STb in redox buffers indicate that the formation of the two disulfide bonds in STb is only moderately cooperative. Similar measurements in the presence of 8 M urea suggest that the native secondary structure significantly stabilizes the disulfide bonds.
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Affiliation(s)
- M Sukumar
- Department of Chemistry, University of Massachusetts, Amherst 01003, USA
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Carrithers SL, Parkinson SJ, Goldstein S, Park P, Robertson DC, Waldman SA. Escherichia coli heat-stable toxin receptors in human colonic tumors. Gastroenterology 1994; 107:1653-61. [PMID: 7958675 DOI: 10.1016/0016-5085(94)90804-4] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
BACKGROUND/AIMS Escherichia coli heat-stable enterotoxins (ST) are small peptides of 18 or 19 amino acids that bind to specific cell surface receptors located on the intestinal brush border and activate guanylate cyclase, resulting in an increase in the intracellular cyclic guanosine 3',5'-monophosphate content of the cell. The present study examined whether receptors for ST are expressed by primary and metastatic human colonic tumors in vivo. METHODS Plasma membranes prepared from surgical tissue samples from normal colon, liver and lung, primary colonic adenocarcinomas, and colon carcinomas metastatic to lung and liver were analyzed for the structural and functional characteristics of constituent ST receptors. RESULTS All primary and metastatic colonic tumors examined bound ST, showing receptors of high (pmol/L) and low (nmol/L) affinity with densities that were similar to those in normal colon. Also, affinity cross-linking of labeled ST to membranes showed similar binding proteins in primary and metastatic tumors and normal colon. ST binding and affinity-labeled proteins were not detected in normal extraintestinal tissues. Guanylate cyclase was activated by ST in membranes from all colonic tumors studied, with efficacies and potencies that were similar to those in normal colon. ST did not activate this enzyme in normal extraintestinal tissues. CONCLUSIONS Receptors for ST are expressed by primary and metastatic human colonic tumors in vivo, with structural and functional characteristics that are similar to those in normal human colon.
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Affiliation(s)
- S L Carrithers
- Department of Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania
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46
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Opposing adenine nucleotide-dependent pathways regulate guanylyl cyclase C in rat intestine. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)31700-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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47
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Chao AC, de Sauvage FJ, Dong YJ, Wagner JA, Goeddel DV, Gardner P. Activation of intestinal CFTR Cl- channel by heat-stable enterotoxin and guanylin via cAMP-dependent protein kinase. EMBO J 1994; 13:1065-72. [PMID: 7510634 PMCID: PMC394914 DOI: 10.1002/j.1460-2075.1994.tb06355.x] [Citation(s) in RCA: 182] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Heat-stable enterotoxins (STa) produced by pathogenic bacteria induce profound salt and water secretion in the gut, leading to diarrhea. Recently, guanylin, an endogenous peptide with properties similar to STa, was identified. While STa and guanylin bind to the same receptor guanylyl cyclase and raise cell cGMP, the signaling mechanism distal to cGMP remains controversial. Here we show that STa, guanylin and cGMP each activate intestinal Cl- secretion, and that this is abolished by inhibitors of cAMP-dependent protein kinase (PKA), suggesting that PKA is a major mediator of this effect. These agents induce Cl- secretion only in cells expressing the wild-type CFTR, indicating that this molecule is the final common effector of the signaling pathway. The involvement of CFTR suggests a possible cystic fibrosis heterozygote advantage against STa-induced diarrhea.
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Affiliation(s)
- A C Chao
- Department of Molecular Pharmacology, Falk Cardiovascular Research Center, Digestive Disease Center, Stanford University School of Medicine, CA 94305-5246
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48
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Nakane M, Murad F. Cloning of guanylyl cyclase isoforms. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 1994; 26:7-18. [PMID: 7913620 DOI: 10.1016/s1054-3589(08)60048-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The cloning of particulate and soluble guanylyl cyclases is summarized in Table I. With respect to transmembrane signal transduction systems, guanylyl and adenylyl cyclases can be grouped together with some protein tyrosine kinases and protein tyrosine phosphatases to form a diverse protein family with various structural and functional similarities (Garbers, 1989, 1991, 1992; Koesling et al., 1991; Chinkers and Garbers, 1991; Fig. 1). Particulate guanylyl cyclase contains a single transmembrane domain, and the peptide-binding portion (ligand receptor) is on the exterior surface and the catalytic region on the interior, similar to the protein tyrosine kinase/receptor and the protein tyrosine phosphatase/receptor families (Yarden et al., 1986; Charbonneau et al., 1988; Tonks et al., 1988). Protein tyrosine kinases and phosphatases are also activated by ligand binding to the extracellular domain, which in turn results in phosphorylation or dephosphorylation. On the other hand, soluble guanylyl cyclase exists as a heterodimer with two putative catalytic domains, and both subunits are essential for enzyme activity and activation by nitric oxide. It is thus particularly interesting that adenylyl cyclase also contains two catalytic domains, which are both necessary for catalytic activity (Tang et al., 1991). It is possible that particulate guanylyl cyclase may also dimerize on hormonal stimulation and two catalytic domains from two monomers form a functional catalytic center capable of forming cyclic GMP. The catalytic core of GC-A expressed in bacteria was shown to form a homodimer with positively cooperative kinetics (Thorpe et al., 1991). The physiological significance of the existence of multiple forms of soluble guanylyl cyclase subunits remains unclear. Future studies should reveal the differences in tissue distribution and activation by nitrovasodilators in various heterodimers of soluble guanylyl cyclase.
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Affiliation(s)
- M Nakane
- Pharmaceutical Products Division Abbott Laboratories, Abbott Park, Illinois 60064
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49
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Vaandrager AB, De Jonge HR. Effect of cyclic GMP on intestinal transport. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 1994; 26:253-83. [PMID: 8038106 DOI: 10.1016/s1054-3589(08)60057-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- A B Vaandrager
- Department of Biochemistry, School of Medicine, Erasmus University, Rotterdam, The Netherlands
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50
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Hakki S, Robertson DC, Waldman SA. A 56 kDa binding protein for Escherichia coli heat-stable enterotoxin isolated from the cytoskeleton of rat intestinal membrane does not possess guanylate cyclase activity. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1152:1-8. [PMID: 8104484 DOI: 10.1016/0005-2736(93)90224-n] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Proteins binding Escherichia coli heat-stable enterotoxin were isolated from the cytoskeleton of intestinal membranes using an affinity matrix of biotinylated ST immobilized on monomeric avidin-agarose. ST binding proteins were purified 343-fold using this affinity technique, with 7% of the initial binding activity recovered in these preparations. ST binding proteins isolated by affinity chromatography possessed a native and subunit molecular mass of 56 kDa. These preparations exhibited both high- and low-affinity binding sites for ST. Guanylate cyclase in extracts of the intestinal membrane cytoskeleton was completely recovered in fractions which did not associate with the affinity matrix. In addition, ST binding proteins isolated by affinity chromatography were devoid of guanylate cyclase activity. These data, taken together with those obtained previously with crude and partially purified receptors, suggest that ST binds to different proteins in intestinal membranes, some of which do not possess guanylate cyclase activity.
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Affiliation(s)
- S Hakki
- Department of Medicine, Thomas Jefferson University, Philadelphia, PA 19107
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