Cyclic AMP-dependent protein kinase and Epac mediate cyclic AMP responses in pancreatic acini
| Autor: | Thomas R. Kolodecik, Anamika Chaudhuri, Fred S. Gorelick, Sohail Z. Husain, Wayne M. Grant |
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| Rok vydání: | 2007 |
| Předmět: |
Male
medicine.medical_specialty Indoles Carbachol Physiology Carbazoles 8-Bromo Cyclic Adenosine Monophosphate Biology digestive system Muscarinic agonist Article Rats Sprague-Dawley Physiology (medical) Zymogen Internal medicine Cyclic AMP medicine Acinar cell Animals Guanine Nucleotide Exchange Factors Pyrroles Secretion Protein kinase A Protein Kinase Inhibitors Enzyme Precursors Hepatology Gastroenterology Actin cytoskeleton Cyclic AMP-Dependent Protein Kinases Pancreas Exocrine Rats Enzyme Activation Endocrinology Zymogen activation medicine.drug |
| Zdroj: | American Journal of Physiology-Gastrointestinal and Liver Physiology. 292:G1403-G1410 |
| ISSN: | 1522-1547 0193-1857 |
| Popis: | The pancreatic acinar cell has several phenotypic responses to cAMP agonists. At physiological concentrations of the muscarinic agonist carbachol (1 μM) or the CCK analog caerulein (100 pM), ligands that increase cytosolic Ca2+, 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. |
| Databáze: | OpenAIRE |
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