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Bhargava A. Unraveling corticotropin-releasing factor family-orchestrated signaling and function in both sexes. VITAMINS AND HORMONES 2023; 123:27-65. [PMID: 37717988 DOI: 10.1016/bs.vh.2023.01.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Stress responses to physical, psychological, environmental, or cellular stressors, has two arms: initiation and recovery. Corticotropin-releasing factor (CRF) is primarily responsible for regulating and/or initiating stress responses via, whereas urocortins (UCNs) are involved in the recovery response to stress via feedback inhibition. Stress is a loaded, polysemous word and is experienced in a myriad of ways. Some stressors are good for an individual, in fact essential, whereas other stressors are associated with bad outcomes. Perceived stress, like beauty, lies in the eye of the beholder, and hence the same stressor can result in individual-specific outcomes. In mammals, there are two main biological sexes with reproduction as primary function. Reproduction and nutrition can also be viewed as stressors; based on a body of work from my laboratory, we propose that the functions of all other organs have co-evolved to optimize and facilitate an individual's nutritional and reproductive functions. Hence, sex differences in physiologically relevant outcomes are innate and occur at all levels- molecular, endocrine, immune, and (patho)physiological. CRF and three UCNs are peptide hormones that mediate their physiological effects by binding to two known G protein-coupled receptors (GPCRs), CRF1 and CRF2. Expression and function of CRF family of hormones and their receptors is likely to be sexually dimorphic in all organs. In this chapter, based on the large body of work from others and my laboratory, an overview of the CRF family with special emphasis on sex-specific actions of peripherally expressed CRF2 receptor in health and disease is provided.
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Affiliation(s)
- Aditi Bhargava
- Center for Reproductive Sciences, Department of Obstetrics and Gynecology, University of California San Francisco, San Francisco, CA, United States.
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2
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Hasdemir B, Mahajan S, Oses-Prieto J, Chand S, Woolley M, Burlingame A, Grammatopoulos DK, Bhargava A. Actin cytoskeleton-dependent regulation of corticotropin-releasing factor receptor heteromers. Mol Biol Cell 2017; 28:2386-2399. [PMID: 28701349 PMCID: PMC5576902 DOI: 10.1091/mbc.e16-11-0778] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 06/30/2017] [Accepted: 07/07/2017] [Indexed: 01/02/2023] Open
Abstract
A physical interaction is shown between CRF1R and CRF2R, two class B G protein–coupled receptors that mediate stress and immune responses. Trafficking of CRF2R but not CRF1R is actin dependent, and coexpression of the two receptors alters actin-independent trafficking. Receptor cross-talk alters agonist binding and signaling. Stress responses are highly nuanced and variable, but how this diversity is achieved by modulating receptor function is largely unknown. Corticotropin-releasing factor receptors (CRFRs), class B G protein–coupled receptors, are pivotal in mediating stress responses. Here we show that the two known CRFRs interact to form heteromeric complexes in HEK293 cells coexpressing both CRFRs and in vivo in mouse pancreas. Coimmunoprecipitation and mass spectrometry confirmed the presence of both CRF1R and CRF2βR, along with actin in these heteromeric complexes. Inhibition of actin filament polymerization prevented the transport of CRF2βR to the cell surface but had no effect on CRF1R. Transport of CRF1R when coexpressed with CRF2βR became actin dependent. Simultaneous stimulation of cells coexpressing CRF1R+CRF2βR with their respective high-affinity agonists, CRF+urocortin2, resulted in approximately twofold increases in peak Ca2+ responses, whereas stimulation with urocortin1 that binds both receptors with 10-fold higher affinity did not. The ability of CRFRs to form heteromeric complexes in association with regulatory proteins is one mechanism to achieve diverse and nuanced function.
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Affiliation(s)
- Burcu Hasdemir
- Osher Center for Integrative Medicine, University of California, San Francisco, San Francisco, CA 94143.,Department of Obstetrics & Gynecology, University of California, San Francisco, San Francisco, CA 94143
| | - Shilpi Mahajan
- Department of Surgery, University of California, San Francisco, San Francisco, CA 94143
| | - Juan Oses-Prieto
- Departments of Pediatrics, Pharmacology, and Chemistry, University of California, San Francisco, San Francisco, CA 94143
| | - Shreya Chand
- Departments of Pediatrics, Pharmacology, and Chemistry, University of California, San Francisco, San Francisco, CA 94143
| | - Michael Woolley
- Translational and Systems Medicine, Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK
| | - Alma Burlingame
- Departments of Pediatrics, Pharmacology, and Chemistry, University of California, San Francisco, San Francisco, CA 94143
| | - Dimitris K Grammatopoulos
- Translational and Systems Medicine, Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK
| | - Aditi Bhargava
- Osher Center for Integrative Medicine, University of California, San Francisco, San Francisco, CA 94143 .,Department of Surgery, University of California, San Francisco, San Francisco, CA 94143.,Department of Obstetrics & Gynecology, University of California, San Francisco, San Francisco, CA 94143
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3
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Patel K, Durgampudi C, Noel P, Trivedi RN, de Oliveira C, Singh VP. Fatty Acid Ethyl Esters Are Less Toxic Than Their Parent Fatty Acids Generated during Acute Pancreatitis. THE AMERICAN JOURNAL OF PATHOLOGY 2016; 186:874-84. [PMID: 26878214 DOI: 10.1016/j.ajpath.2015.11.022] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Revised: 10/19/2015] [Accepted: 11/19/2015] [Indexed: 12/18/2022]
Abstract
Although ethanol causes acute pancreatitis (AP) and lipolytic fatty acid (FA) generation worsens AP, the contribution of ethanol metabolites of FAs, ie, FA ethyl esters (FAEEs), to AP outcomes is unclear. Previously, pancreata of dying alcoholics and pancreatic necrosis in severe AP, respectively, showed high FAEEs and FAs, with oleic acid (OA) and its ethyl esters being the most abundant. We thus compared the toxicities of FAEEs and their parent FAs in severe AP. Pancreatic acini and peripheral blood mononuclear cells were exposed to FAs or FAEEs in vitro. The triglyceride of OA (i.e., glyceryl tri-oleate) or OAEE was injected into the pancreatic ducts of rats, and local and systemic severities were studied. Unsaturated FAs at equimolar concentrations to FAEEs induced a larger increase in cytosolic calcium, mitochondrial depolarization, and necro-apoptotic cell death. Glyceryl tri-oleate but not OAEE resulted in 70% mortality with increased serum OA, a severe inflammatory response, worse pancreatic necrosis, and multisystem organ failure. Our data show that FAs are more likely to worsen AP than FAEEs. Our observations correlate well with the high pancreatic FAEE concentrations in alcoholics without pancreatitis and high FA concentrations in pancreatic necrosis. Thus, conversion of FAs to FAEE may ameliorate AP in alcoholics.
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Affiliation(s)
- Krutika Patel
- Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Scottsdale, Arizona
| | - Chandra Durgampudi
- Department of Medicine, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
| | - Pawan Noel
- Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Scottsdale, Arizona
| | - Ram N Trivedi
- Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Scottsdale, Arizona
| | - Cristiane de Oliveira
- Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Scottsdale, Arizona
| | - Vijay P Singh
- Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Scottsdale, Arizona.
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Noel P, Patel K, Durgampudi C, Trivedi RN, de Oliveira C, Crowell MD, Pannala R, Lee K, Brand R, Chennat J, Slivka A, Papachristou GI, Khalid A, Whitcomb DC, DeLany JP, Cline RA, Acharya C, Jaligama D, Murad FM, Yadav D, Navina S, Singh VP. Peripancreatic fat necrosis worsens acute pancreatitis independent of pancreatic necrosis via unsaturated fatty acids increased in human pancreatic necrosis collections. Gut 2016; 65:100-11. [PMID: 25500204 PMCID: PMC4869971 DOI: 10.1136/gutjnl-2014-308043] [Citation(s) in RCA: 103] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 11/17/2014] [Indexed: 02/06/2023]
Abstract
BACKGROUND AND AIMS Peripancreatic fat necrosis occurs frequently in necrotising pancreatitis. Distinguishing markers from mediators of severe acute pancreatitis (SAP) is important since targeting mediators may improve outcomes. We evaluated potential agents in human pancreatic necrotic collections (NCs), pseudocysts (PCs) and pancreatic cystic neoplasms and used pancreatic acini, peripheral blood mononuclear cells (PBMC) and an acute pancreatitis (AP) model to determine SAP mediators. METHODS We measured acinar and PBMC injury induced by agents increased in NCs and PCs. Outcomes of caerulein pancreatitis were studied in lean rats coadministered interleukin (IL)-1β and keratinocyte chemoattractant/growth-regulated oncogene, triolein alone or with the lipase inhibitor orlistat. RESULTS NCs had higher fatty acids, IL-8 and IL-1β versus other fluids. Lipolysis of unsaturated triglyceride and resulting unsaturated fatty acids (UFA) oleic and linoleic acids induced necro-apoptosis at less than half the concentration in NCs but other agents did not do so at more than two times these concentrations. Cytokine coadministration resulted in higher pancreatic and lung inflammation than caerulein alone, but only triolein coadministration caused peripancreatic fat stranding, higher cytokines, UFAs, multisystem organ failure (MSOF) and mortality in 97% animals, which were prevented by orlistat. CONCLUSIONS UFAs, IL-1β and IL-8 are elevated in NCs. However, UFAs generated via peripancreatic fat lipolysis causes worse inflammation and MSOF, converting mild AP to SAP.
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Affiliation(s)
- Pawan Noel
- Departments of Medicine, Mayo Clinic, Scottsdale, Arizona, USA
| | - Krutika Patel
- Departments of Medicine, Mayo Clinic, Scottsdale, Arizona, USA
| | - Chandra Durgampudi
- Departments of Medicine, University of Pittsburgh Medical Center, Pasavant, Pennsylvania, USA
| | - Ram N Trivedi
- Departments of Medicine, Mayo Clinic, Scottsdale, Arizona, USA
| | | | | | - Rahul Pannala
- Departments of Medicine, Mayo Clinic, Scottsdale, Arizona, USA
| | - Kenneth Lee
- Departments of Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA
| | - Randall Brand
- Departments of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Jennifer Chennat
- Departments of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Adam Slivka
- Departments of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | | | - Asif Khalid
- Departments of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - David C Whitcomb
- Departments of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - James P DeLany
- Departments of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Rachel A Cline
- Departments of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Chathur Acharya
- Departments of Medicine, University of Pittsburgh Medical Center, Pasavant, Pennsylvania, USA
| | - Deepthi Jaligama
- Departments of Medicine, University of Pittsburgh Medical Center, Pasavant, Pennsylvania, USA
| | - Faris M Murad
- Departments of Medicine, Washington University, Saint Louis, Missouri, USA
| | - Dhiraj Yadav
- Departments of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Sarah Navina
- Departments of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Vijay P Singh
- Departments of Medicine, Mayo Clinic, Scottsdale, Arizona, USA
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5
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Durgampudi C, Noel P, Patel K, Cline R, Trivedi RN, DeLany JP, Yadav D, Papachristou GI, Lee K, Acharya C, Jaligama D, Navina S, Murad F, Singh VP. Acute lipotoxicity regulates severity of biliary acute pancreatitis without affecting its initiation. THE AMERICAN JOURNAL OF PATHOLOGY 2014; 184:1773-84. [PMID: 24854864 DOI: 10.1016/j.ajpath.2014.02.015] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Revised: 02/07/2014] [Accepted: 02/27/2014] [Indexed: 02/07/2023]
Abstract
Obese patients have worse outcomes during acute pancreatitis (AP). Previous animal models of AP have found worse outcomes in obese rodents who may have a baseline proinflammatory state. Our aim was to study the role of acute lipolytic generation of fatty acids on local severity and systemic complications of AP. Human postpancreatitis necrotic collections were analyzed for unsaturated fatty acids (UFAs) and saturated fatty acids. A model of biliary AP was designed to replicate the human variables by intraductal injection of the triglyceride glyceryl trilinoleate alone or with the chemically distinct lipase inhibitors orlistat or cetilistat. Parameters of AP etiology and outcomes of local and systemic severity were measured. Patients with postpancreatitis necrotic collections were obese, and 13 of 15 had biliary AP. Postpancreatitis necrotic collections were enriched in UFAs. Intraductal glyceryl trilinoleate with or without the lipase inhibitors resulted in oil red O-positive areas, resembling intrapancreatic fat. Both lipase inhibitors reduced the glyceryl trilinoleate-induced increase in serum lipase, UFAs, pancreatic necrosis, serum inflammatory markers, systemic injury, and mortality but not serum alanine aminotransferase, bilirubin, or amylase. We conclude that UFAs are enriched in human necrotic collections and acute UFA generation via lipolysis worsens pancreatic necrosis, systemic inflammation, and injury associated with severe AP. Inhibition of lipolysis reduces UFA generation and improves these outcomes of AP without interfering with its induction.
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Affiliation(s)
- Chandra Durgampudi
- Department of Medicine, University of Pittsburgh Medical Center Pasavant, Pittsburgh, Pennsylvania
| | - Pawan Noel
- Department of Medicine, Mayo Clinic, Scottsdale, Arizona
| | - Krutika Patel
- Department of Medicine, Mayo Clinic, Scottsdale, Arizona
| | - Rachel Cline
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Ram N Trivedi
- Department of Medicine, Mayo Clinic, Scottsdale, Arizona
| | - James P DeLany
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Dhiraj Yadav
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | | | - Kenneth Lee
- Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Chathur Acharya
- Department of Medicine, University of Pittsburgh Medical Center Pasavant, Pittsburgh, Pennsylvania
| | - Deepthi Jaligama
- Department of Medicine, University of Pittsburgh Medical Center Pasavant, Pittsburgh, Pennsylvania
| | - Sarah Navina
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Faris Murad
- Department of Medicine, Washington University, St. Louis, Missouri
| | - Vijay P Singh
- Department of Medicine, Mayo Clinic, Scottsdale, Arizona.
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6
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Hypothermia slows sequential and parallel steps initiated during caerulein pancreatitis. Pancreatology 2014; 14:459-64. [PMID: 25459565 DOI: 10.1016/j.pan.2014.06.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Revised: 06/17/2014] [Accepted: 06/23/2014] [Indexed: 12/11/2022]
Abstract
BACKGROUND AND OBJECTIVES Multiple deleterious signaling cascades are simultaneously activated in acute pancreatitis (AP), which may limit the success of pharmacologic approaches targeting a single step. We explored whether cooling acinar cells slows distinct steps initiated from a stimulus causing pancreatitis simultaneously, and the temperature range over which inhibition of such deleterious signaling occurs. METHODS Caerulein (100 nM) induced trypsinogen activation (TGA), CXCL1, CXCL2 mRNA levels, cell injury were studied at 37 °C, 34 °C, 31 °C, 29 °C and 25 °C in acinar cells. Trypsin, cathepsin B activities and cathepsin B mediated TGA were studied at 37 °C, 23 °C and 4 °C. RESULTS There was >80% reduction in TGA, CXCL1 and CXCL2 mRNA levels at 29 °C, and in cell injury at 34 °C, compared to those at 37 °C. Trypsin activity, cathepsin B activity and cathepsin B mediated TGA at 23 °C were respectively, 53%, 64% and 26% of that at 37 °C. Acinar cooling to 31 °C reduced LDH leakage even when cooling was initiated an hour after caerulein stimulation at 37 °C. CONCLUSIONS Hypothermia synergistically and simultaneously slows parallel and distinct signaling steps initiated by caerulein, thereby reducing TGA, upregulation of inflammatory mediators and acinar injury.
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Mishra V, Cline R, Noel P, Karlsson J, Baty CJ, Orlichenko L, Patel K, Trivedi RN, Husain SZ, Acharya C, Durgampudi C, Stolz DB, Navina S, Singh VP. Src Dependent Pancreatic Acinar Injury Can Be Initiated Independent of an Increase in Cytosolic Calcium. PLoS One 2013; 8:e66471. [PMID: 23824669 PMCID: PMC3688910 DOI: 10.1371/journal.pone.0066471] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 05/07/2013] [Indexed: 12/12/2022] Open
Abstract
Several deleterious intra-acinar phenomena are simultaneously triggered on initiating acute pancreatitis. These culminate in acinar injury or inflammatory mediator generation in vitro and parenchymal damage in vivo. Supraphysiologic caerulein is one such initiator which simultaneously activates numerous signaling pathways including non-receptor tyrosine kinases such as of the Src family. It also causes a sustained increase in cytosolic calcium- a player thought to be crucial in regulating deleterious phenomena. We have shown Src to be involved in caerulein induced actin remodeling, and caerulein induced changes in the Golgi and post-Golgi trafficking to be involved in trypsinogen activation, which initiates acinar cell injury. However, it remains unclear whether an increase in cytosolic calcium is necessary to initiate acinar injury or if injury can be initiated at basal cytosolic calcium levels by an alternate pathway. To study the interplay between tyrosine kinase signaling and calcium, we treated mouse pancreatic acinar cells with the tyrosine phosphatase inhibitor pervanadate. We studied the effect of the clinically used Src inhibitor Dasatinib (BMS-354825) on pervanadate or caerulein induced changes in Src activation, trypsinogen activation, cell injury, upstream cytosolic calcium, actin and Golgi morphology. Pervanadate, like supraphysiologic caerulein, induced Src activation, redistribution of the F-actin from its normal location in the sub-apical area to the basolateral areas, and caused antegrade fragmentation of the Golgi. These changes, like those induced by supraphysiologic caerulein, were associated with trypsinogen activation and acinar injury, all of which were prevented by Dasatinib. Interestingly, however, pervanadate did not cause an increase in cytosolic calcium, and the caerulein induced increase in cytosolic calcium was not affected by Dasatinib. These findings suggest that intra-acinar deleterious phenomena may be initiated independent of an increase in cytosolic calcium. Other players resulting in acinar injury along with the Src family of tyrosine kinases remain to be explored.
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Affiliation(s)
- Vivek Mishra
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Rachel Cline
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Pawan Noel
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Jenny Karlsson
- Department of Cell Biology and Physiology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Catherine J. Baty
- Department of Cell Biology and Physiology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Lidiya Orlichenko
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Krutika Patel
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Ram Narayan Trivedi
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Sohail Z. Husain
- Department of Pediatrics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Chathur Acharya
- Department of Medicine, University of Pittsburgh Medical Center, Passavant, Pennsylvania, United States of America
| | - Chandra Durgampudi
- Department of Medicine, University of Pittsburgh Medical Center, Passavant, Pennsylvania, United States of America
| | - Donna B. Stolz
- Department of Cell Biology and Physiology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Sarah Navina
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Vijay P. Singh
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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Zhang L, Zhang J, Shea K, Xu L, Tobin G, Knapton A, Sharron S, Rouse R. Autophagy in pancreatic acinar cells in caerulein-treated mice: immunolocalization of related proteins and their potential as markers of pancreatitis. Toxicol Pathol 2013; 42:435-57. [PMID: 23640381 DOI: 10.1177/0192623313486967] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Drug-induced pancreatitis (DIP) is an underdiagnosed condition that lacks sensitive and specific biomarkers. To better understand the mechanisms of DIP and to identify potential tissue biomarkers, we studied experimental pancreatitis induced in male C57BL/6 mice by intraperitoneal injection of caerulein (10 or 50 μg/kg) at 1-hr intervals for a total of 7 injections. Pancreata from caerulein-treated mice exhibited consistent acinar cell autophagy and apoptosis with infrequent necrosis. Kinetic assays for serum amylase and lipase also showed a dose-dependent increase. Terminal deoxynucleotidyl transferase-mediated biotin-dNTP nick labeling (TUNEL) detected dose-dependent acinar cell apoptosis. By light microscopy, autophagy was characterized by the formation of autophagosomes and autolysosomes (ALs) within the cytoplasm of acinar cells. Immunohistochemical studies with specific antibodies for proteins related to autophagy and pancreatic stress were conducted to evaluate these proteins as potential biomarkers of pancreatitis. Western blots were used to confirm immunohistochemical results using pancreatic lysates from control and treated animals. Autophagy was identified as a contributing process in caerulein-induced pancreatitis and proteins previously associated with autophagy were upregulated following caerulein treatment. Autophagosomes and ALs were found to be a common pathway, in which cathepsins, lysosome-associated membrane protein 2, vacuole membrane protein 1, microtubule-associated protein 1 light chain 3 (LC3), autophagy-related protein 9, Beclin1, and pancreatitis-associated proteins were simultaneously involved in response to caerulein stimulus. Regenerating islet-derived 3 gamma (Reg3γ), a pancreatic acute response protein, was dose-dependently induced in caerulein-treated mice and colocalized with the autophagosomal marker, LC3. This finding supports Reg3γ as a candidate biomarker for pancreatic injury.
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Affiliation(s)
- Leshuai Zhang
- 1Division of Drug Safety Research, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, Maryland, USA
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Navina S, Acharya C, DeLany JP, Orlichenko LS, Baty CJ, Shiva SS, Durgampudi C, Karlsson JM, Lee K, Bae KT, Furlan A, Behari J, Liu S, McHale T, Nichols L, Papachristou GI, Yadav D, Singh VP. Lipotoxicity causes multisystem organ failure and exacerbates acute pancreatitis in obesity. Sci Transl Med 2012; 3:107ra110. [PMID: 22049070 DOI: 10.1126/scitranslmed.3002573] [Citation(s) in RCA: 286] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Obesity increases the risk of adverse outcomes during acute critical illnesses such as burns, severe trauma, and acute pancreatitis. Although individuals with more body fat and higher serum cytokines and lipase are more likely to experience problems, the roles that these characteristics play are not clear. We used severe acute pancreatitis as a representative disease to investigate the effects of obesity on local organ function and systemic processes. In obese humans, we found that an increase in the volume of intrapancreatic adipocytes was associated with more extensive pancreatic necrosis during acute pancreatitis and that acute pancreatitis was associated with multisystem organ failure in obese individuals. In vitro studies of pancreatic acinar cells showed that unsaturated fatty acids were proinflammatory, releasing intracellular calcium, inhibiting mitochondrial complexes I and V, and causing necrosis. Saturated fatty acids had no such effects. Inhibition of lipolysis in obese (ob/ob) mice with induced pancreatitis prevented a rise in serum unsaturated fatty acids and prevented renal injury, lung injury, systemic inflammation, hypocalcemia, reduced pancreatic necrosis, and mortality. Thus, therapeutic approaches that target unsaturated fatty acid-mediated lipotoxicity may reduce adverse outcomes in obese patients with critical illnesses such as severe acute pancreatitis.
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Affiliation(s)
- Sarah Navina
- Department of Pathology, University of Pittsburgh, 200 Lothrop Street, Pittsburgh, PA 15213, USA
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Yang SJ, Chen HM, Hsieh CH, Hsu JT, Yeh CN, Yeh TS, Hwang TL, Jan YY, Chen MF. Akt pathway is required for oestrogen-mediated attenuation of lung injury in a rodent model of cerulein-induced acute pancreatitis. Injury 2011; 42:638-42. [PMID: 20709317 DOI: 10.1016/j.injury.2010.07.242] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2010] [Revised: 07/01/2010] [Accepted: 07/12/2010] [Indexed: 02/08/2023]
Abstract
BACKGROUND The phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) is known to be an endogenous negative feedback or compensatory mechanism that serves to limit pro-inflammatory and chemotactic events in response to injury. The aim of this study is to elucidate whether Akt plays any role in 17β-estradiol (E2)-mediated attenuation of lung injury after acute pancreatitis (AP). MATERIALS AND METHODS Male Sprague-Dawley rats underwent cerulein-induced AP. Rats were treated with vehicle (cyclodextrin), E2 (1 mg/kg body weight [BW]), or E2 plus PI3K/Akt inhibitor Wortmannin (100 μg/kg BW) 1h after the onset of AP. At 8 h after sham operation or AP, various parameters were measured. RESULTS AP led to a significant decrease in lung Akt phosphorylation, which was associated with increased lung tissue myeloperoxidase (MPO) activity, wet-to-dry weight ratios, interleukin (IL)-6, tumor necrosis factor (TNF)-α, cytokine-induced neutrophil chemoattractant (CINC)-1, and CINC-3 levels. Administration of E2 after AP restored the AP-induced decrease in Akt phosphorylation and attenuated the increase in lung injury markers (MPO activity and wet-to dry weight ratios) and pro-inflammatory mediator production. The effects of E2 on the lung were abolished by co-administration of Wortmannin. CONCLUSIONS These results collectively suggest evidences that the Akt pathway seems to be required for E2-mediated protection of lung injury after AP.
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Affiliation(s)
- Shang-Ju Yang
- Department of Surgery, Chang Gung Memorial Hospital at Linkou, Chang Gung University College of Medicine, 5, Fushing Street, Kweishan Shiang, Taoyuan 333, Taiwan
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11
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Orlichenko LS, Behari J, Yeh TH, Liu S, Stolz DB, Saluja AK, Singh VP. Transcriptional regulation of CXC-ELR chemokines KC and MIP-2 in mouse pancreatic acini. Am J Physiol Gastrointest Liver Physiol 2010; 299:G867-76. [PMID: 20671197 PMCID: PMC2957341 DOI: 10.1152/ajpgi.00177.2010] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Neutrophils and their chemoattractants, the CXC-ELR chemokines keratinocyte cytokine (KC) and macrophage inflammatory protein-2 (MIP-2), play a critical role in pancreatitis. While acute pancreatitis is initiated in acinar cells, it is unclear if these are a source of CXC-ELR chemokines. KC and MIP-2 have NF-κB, activator protein-1 (AP-1) sites in their promoter regions. However, previous studies have shown increased basal and reduced caerulein-induced AP-1 activation in harvested pancreatic tissue in vitro, which limits interpreting the caerulein-induced response. Moreover, recent studies suggest that NF-κB silencing in acinar cells alone may not be sufficient to reduce inflammation in acute pancreatitis. Thus the aim of this study was to determine whether acinar cells are a source of KC and MIP-2 and to understand their transcriptional regulation. Primary overnight-cultured murine pancreatic acini were used after confirming their ability to replicate physiological and pathological acinar cell responses. Upstream signaling resulting in KC, MIP-2 upregulation was studied along with activation of the transcription factors NF-κB and AP-1. Cultured acini replicated critical responses to physiological and pathological caerulein concentrations. KC and MIP-2 mRNA levels increased in response to supramaximal but not to physiological caerulein doses. This upregulation was calcium and protein kinase C (PKC), but not cAMP, dependent. NF-κB inhibition completely prevented upregulation of KC but not MIP-2. Complete suppression of MIP-2 upregulation required dual inhibition of NF-κB and AP-1. Acinar cells are a likely source of KC and MIP-2 upregulation during pancreatitis. This upregulation is dependent on calcium and PKC. MIP-2 upregulation requires both NF-κB and AP-1 in these cells. Thus dual inhibition of NF-κB and AP-1 may be a more successful strategy to reduce inflammation in pancreatitis than targeting NF-κB alone.
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Affiliation(s)
| | | | | | | | - Donna B. Stolz
- 2Cell Biology and Physiology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania; and
| | - Ashok K. Saluja
- 3Department of Surgery, University of Minnesota, Minneapolis, Minnesota
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Relationship between carbachol hyperstimulation-induced pancreatic intracellular trypsinogen and NF-kappa B activation in rats in vitro. ACTA ACUST UNITED AC 2008; 28:69-72. [PMID: 18278461 DOI: 10.1007/s11596-008-0117-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2007] [Indexed: 10/19/2022]
Abstract
The relationship between intracellular trypsinogen activation and NF-kappa B activation in rat pancreatic acinar cells induced by M3 cholinergic receptor agonist (carbachol) hyperstimulation was studied. Rat pancreatic acinar cells were isolated, cultured and treated with carbachol, the active protease inhibitor (pefabloc) and NF-kappa B inhibitor (PDTC) in vitro. Intracellular trypsin activity was measured by using a fluorogenic substrate. The activity of NF-kappa B was monitored by using electrophoretic mobility shift assay. The results showed that after pretreatment with 2 mmol/L pefabloc, the activities of trypsin and NF-kappa B in pancreatic acinar cells treated with high concentrations of carbachol (10(-3) mol/L) in vitro was significantly decreased as compared with control group (P<0.01). The addition of 10(-2) mol/L PDTC resulted in a significant decrease of NF-kappa B activities in pancreatic acinar cells after treated with high concentrations of carbachol (10(-3) mol/L) in vitro, but the intracellular trypsinogen activity was not obviously inhibited (P>0.05). It was concluded that intracellular trypsinogen activation is likely involved in the regulation of high concentrations of carbachol-induced NF-kappa B activation in pancreatic acinar cells in vitro. NF-kappa B activation is likely not necessary for high concentrations of carbachol-induced trypsinogen activation in pancreatic acinar cells in vitro.
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Abstract
Pancreatitis and Calcium Signalling was an international research workshop organized by the authors and held at the Liverpool Medical Institution, Liverpool, United Kingdom, from Sunday 12th to Tuesday 14th November 2006. The overall goal of the workshop was to review progress and explore new opportunities for understanding the mechanisms of acute pancreatitis with an emphasis on the role of pathological calcium signaling. The participants included those with significant interest and expertise in pancreatitis research and others who are in fields outside gastroenterology but with significant expertise in areas of cell biology relevant to pancreatitis. The workshop was designed to enhance interchange of ideas and collaborations, to engage and encourage younger researchers in the field, and promote biomedical research through the participating and supporting organizations and societies. The workshop was divided into 8 topic-oriented sessions. The sessions were: (1) Physiology and pathophysiology of calcium signaling; (2) Interacting signaling mechanisms; (3) Premature digestive enzyme activation; (4) Physiology Society Lecture: Aberrant Ca2+ signaling, bicarbonate secretion, and pancreatitis; (5) NFkappaB, cytokines, and immune mechanisms; (6) Mitochondrial injury; (7) Cell death pathways; and (8) Overview of areas for future research. In each session, speakers presented work appropriate to the topic followed by discussion of the material presented by the group. The publication of these proceedings is intended to provide a platform for enhancing research and therapeutic development for acute pancreatitis.
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Van Acker GJD, Weiss E, Steer ML, Perides G. Cause-effect relationships between zymogen activation and other early events in secretagogue-induced acute pancreatitis. Am J Physiol Gastrointest Liver Physiol 2007; 292:G1738-46. [PMID: 17332471 DOI: 10.1152/ajpgi.00543.2006] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We have hypothesized that the colocalization of digestive zymogens with lysosomal hydrolases, which occurs during the early stages of every experimental pancreatitis model, facilitates activation of those zymogens by lysosomal hydrolases such as cathepsin B and that this activation triggers acute pancreatitis by leading to acinar cell injury. Some, however, have argued that the colocalization phenomenon may be the result, rather than the cause, of zymogen activation during pancreatitis. To resolve this controversy and explore the causal relationships between zymogen activation and other early pancreatitis events, we induced pancreatitis in mice by repeated supramaximal secretagogue stimulation with caerulein. Some animals were pretreated with the cathepsin B inhibitor CA-074 me to inhibit cathepsin B, prevent intrapancreatic activation of digestive zymogens, and reduce the severity of pancreatitis. We show that inhibition of cathepsin B by pretreatment with CA-074 me prevents intrapancreatic zymogen activation and reduces organellar fragility, but it does not alter the caerulein-induced colocalization phenomenon or subcellular F-actin redistribution or prevent caerulein-induced activation of NF-kappaB, ERK1/2, and JNK or upregulated expression of cytochemokines. We conclude 1) that the colocalization phenomenon, F-actin redistribution, activation of proinflammatory transcription factors, and upregulated expression of cytochemokines are not the results of zymogen activation, and 2) that these early events in pancreatitis are not dependent on cathepsin B activity. In contrast, zymogen activation and increased subcellular organellar fragility during caerulein-induced pancreatitis are dependent on cathepsin B activity.
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Affiliation(s)
- Gijs J D Van Acker
- Dept. of Surgery, Tufts-New England Medical Center, 860 Washington St., Boston, MA 02111, USA
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15
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Chaudhuri A, Husain SZ, Kolodecik TR, Grant WM, Gorelick FS. Cyclic AMP-dependent protein kinase and Epac mediate cyclic AMP responses in pancreatic acini. Am J Physiol Gastrointest Liver Physiol 2007; 292:G1403-10. [PMID: 17234888 PMCID: PMC2975017 DOI: 10.1152/ajpgi.00478.2005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The pancreatic acinar cell has several phenotypic responses to cAMP agonists. At physiological concentrations of the muscarinic agonist carbachol (1 microM) or the CCK analog caerulein (100 pM), ligands that increase cytosolic Ca(2+), cAMP acts synergistically to enhance secretion. Supraphysiological concentrations of carbachol (1 mM) or caerulein (100 nM) suppress secretion and cause intracellular zymogen activation; cAMP enhances both zymogen activation and reverses the suppression of secretion. In addition to stimulating cAMP-dependent protein kinase (PKA), recent studies using cAMP analogs that lack a PKA response have shown that cAMP can also act through the cAMP-binding protein, Epac (exchange protein directly activated by cyclic AMP). The roles of PKA and Epac in cAMP responses were examined in isolated pancreatic acini. The activation of both cAMP-dependent pathways or the selective activation of Epac was found to enhance amylase secretion induced by physiological and supraphysiological concentrations of the muscarinic agonist carbachol. Similarly, activation of both PKA or the specific activation of Epac enhanced carbachol-induced activation of trypsinogen and chymotrypsinogen. Disorganization of the apical actin cytoskeleton has been linked to the decreased secretion observed with supraphysiological concentrations of carbachol and caerulein. Although stimulation of PKA and Epac or Epac alone could largely overcome the decreased secretion observed with either supraphysiological carbachol or caerulein, stimulation of cAMP pathways did not reduce the disorganization of the apical cytoskeleton. These studies demonstrate that PKA and Epac pathways are coupled to both secretion and zymogen activation in the pancreatic acinar cell.
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Affiliation(s)
- Anamika Chaudhuri
- Veterans Affairs Connecticut Healthcare and Yale University School of Medicine, New Haven, Connecticut, USA
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Wijayanti N, Kietzmann T, Immenschuh S. Heme Oxygenase-1 Gene Activation by the NAD(P)H Oxidase Inhibitor 4-(2-Aminoethyl) Benzenesulfonyl Fluoride via a Protein Kinase B, p38-dependent Signaling Pathway in Monocytes. J Biol Chem 2005; 280:21820-9. [PMID: 15833736 DOI: 10.1074/jbc.m502943200] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Heme oxygenase (HO)-1 is the inducible isoform of the rate-limiting enzyme of heme degradation and modulates the inflammatory immune response. Because HO-1 is up-regulated by NAD(P)H oxidase activators such as lipopolysaccharide and 12-O-tetradecanoylphorbol-13-acetate in monocytic cells, we investigated the gene regulation of HO-1 by the chemical NAD(P)H oxidase inhibitor 4-(2-aminoethyl) benzenesulfonyl fluoride (AEBSF). Unexpectedly, AEBSF induced endogenous gene expression and promoter activity of HO-1 in cell cultures of human and mouse monocytes. Inhibition of the phosphatidylinositol 3-kinase/protein kinase B (PKB) pathway by pharmacological inhibitors and cotransfection of an expression vector for a dominant negative mutant of PKB reduced the AEBSF-dependent induction of HO-1 gene transcription. Accordingly, overexpressed constitutively active PKB markedly up-regulated HO-1 promoter activity. AEBSF activated the mitogen-activated protein kinases (MAPK) JNK and p38. Inhibition of p38alpha and p38beta, but not that of JNK or p38gamma and p38delta, prevented the induction of HO-1 gene expression by AEBSF. p38 was stimulated by AEBSF in a PKB-dependent manner as demonstrated by a luciferase assay with a Gal4-CHOP fusion protein. Finally, AEBSF- and PKB-dependent induction of HO-1 promoter activity was reduced by simultaneous mutation of an E-box motif (-47/-42) and a cAMP response element/AP-1 element (-664/-657) of the proximal HO-1 gene promoter. Overexpression of the basic helix-loop-helix transcription factor USF2 and coactivator p300 enhanced the AEBSF-dependent response of the HO-1 promoter. The data suggest that the transcriptional induction of HO-1 gene expression by AEBSF is mediated via activation of a PKB, p38 MAPK signaling pathway.
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Affiliation(s)
- Nastiti Wijayanti
- Institut für Klinische Immunologie und Transfusionsmedizin, Justus-Liebig-Universität Giessen, Langhanstrasse 7, D-35392 Giessen, Germany
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Chaudhuri A, Kolodecik TR, Gorelick FS. Effects of increased intracellular cAMP on carbachol-stimulated zymogen activation, secretion, and injury in the pancreatic acinar cell. Am J Physiol Gastrointest Liver Physiol 2005; 288:G235-43. [PMID: 15458924 PMCID: PMC2975016 DOI: 10.1152/ajpgi.00334.2004] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A characteristic of acute pancreatitis is the premature activation and retention of enzymes within the pancreatic acinar cell. Because ligands linked to cAMP production may prevent some forms of pancreatitis, we evaluated the effects of increased intracellular cAMP in the rat pancreatic acinar cell. Specifically, this study examined the effects of the cholinergic agonist carbachol and agents that increase cAMP [secretin and 8-bromoadenosine 3',5'-cyclic monophosphate (8-Br-cAMP)] on zymogen activation (trypsin and chymotrypsin), enzyme secretion, and cellular injury in isolated pancreatic acini. Although cAMP agonists affected the responses to physiological concentrations of carbachol (1 microM), their most prominent effects were observed with supraphysiological concentrations (1 mM). When secretin was added to 1 mM carbachol, there was a slight increase in zymogen activation, but no change in the secretion of amylase or chymotrypsin. Furthermore, coaddition of secretin increased parameters of cell injury (trypan blue exclusion, lactic dehydrogenase release, and morphological markers) compared with carbachol (1 mM) alone. Although directly increasing cellular cAMP by 8-Br-cAMP caused much greater zymogen activation than carbachol (1 mM) alone or with secretin, 8-Br-cAMP cotreatment reduced all parameters of injury to the level of unstimulated acini. Furthermore, 8-Br-cAMP dramatically enhanced the secretion of amylase and chymotrypsin from the acinar cell. This study demonstrates that increasing acinar cell cAMP can overcome the inhibition of enzyme secretion caused by high concentrations of carbachol and eliminate acinar cell injury.
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Affiliation(s)
- A Chaudhuri
- Gastrointestinal Research Laboratory, Veterans Affairs Healthcare Connecticut, West Haven, CT 06516, USA
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19
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Abstract
Continuing progress is being made in understanding the regulation of pancreatic acinar cell function by receptor-activated intracellular signaling mechanisms. Knowledge of how ligands interact at the molecular level with their receptors and activate heterotrimeric G proteins is increasing. In addition to inositol trisphosphate, intracellular messengers include cyclic ADP ribose, nicotinic acid adenine dinucleotide phosphate, arachidonic acid, and diacylglycerol. Ca signaling involves the interaction of inositol trisphosphate, cyclic ADP ribose, and nicotinic acid adenine dinucleotide phosphate with distinct subcellular Ca stores. Ca signals ultimately induce exocytosis of zymogen granules and identification of the proteins involved on the granule and plasma membrane, and understanding of their roles is continuing. Other receptor-activated signaling pathways primarily regulate nonsecretory events. Considerable progress has been made in understanding how the mammalian target of rapamycin pathway regulates protein synthesis through translation factors and ribosomal proteins. Other pathways in acinar cells include the mitogen-activated protein kinases, the tyrosine kinases, and the transforming growth factor-beta-Smad pathways.
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Affiliation(s)
- John A Williams
- Department of Physiology, University of Michigan, Ann Arbor, Michigan 48109-0622, USA.
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20
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Blackstone MO. Serine protease inhibitors and F-actin redistribution. Gastroenterology 2002; 122:591-3. [PMID: 11845807 DOI: 10.1053/gast.2002.31601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
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21
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Singh VP, Saluja AK, Bhagat L, van Acker GJ, Song AM, Soltoff SP, Cantley LC, Steer ML. Phosphatidylinositol 3-kinase-dependent activation of trypsinogen modulates the severity of acute pancreatitis. J Clin Invest 2001; 108:1387-95. [PMID: 11696584 PMCID: PMC209439 DOI: 10.1172/jci12874] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2001] [Accepted: 09/10/2001] [Indexed: 12/11/2022] Open
Abstract
Intra-acinar cell activation of digestive enzyme zymogens including trypsinogen is generally believed to be an early and critical event in acute pancreatitis. We have found that the phosphatidylinositol 3-kinase inhibitor wortmannin can reduce the intrapancreatic activation of trypsinogen that occurs during two dissimilar experimental models of rodent acute pancreatitis, secretagogue- and duct injection-induced pancreatitis. The severity of both models was also reduced by wortmannin administration. In contrast, the NF-kappa B activation that occurs during the early stages of secretagogue-induced pancreatitis is not altered by administration of wortmannin. Ex vivo, caerulein-induced trypsinogen activation is inhibited by wortmannin and LY294002. However, the cytoskeletal changes induced by caerulein were not affected by wortmannin. Concentrations of caerulein that induced ex vivo trypsinogen activation do not significantly increase phosphatidylinositol-3,4-bisphosphate or phosphatidylinositol 3,4,5-trisphosphate levels or induce phosphorylation of Akt/PKB, suggesting that class I phosphatidylinositol 3-kinases are not involved. The concentration of wortmannin that inhibits trypsinogen activation causes a 75% decrease in phosphatidylinositol 3-phosphate, which is implicated in vesicle trafficking and fusion. We conclude that a wortmannin-inhibitable phosphatidylinositol 3-kinase is necessary for intrapancreatic activation of trypsinogen and regulating the severity of acute pancreatitis. Our observations suggest that phosphatidylinositol 3-kinase inhibition might be of benefit in preventing acute pancreatitis.
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Affiliation(s)
- V P Singh
- Department of Surgery, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02215, USA
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