The purpose of this MERIT award renewal is to define the roles and mechanisms by which gastrin, somatostatin, and gastrin releasing peptide (GRP) regulate gastric acid secretion and mucosal proliferation. The primary hypothesis is that secretory and trophic functions of the histamine-secretin enterochromaffin-like (ECL) cell are stimulated by circulating gastrin acting on CCK-B/gastrin receptors and inhibited by oxyntic D cell somatostatin acting by local gastric paracrine/capillary delivery on type 2 somatostatin receptors. The secondary hypothesis is that secretion and growth of the antral gastrin (G) cell are stimulated by chemosensory stimulatory reflexes involving GRP acting directly upon the G cell and inhibited by chemosensory inhibitory reflexes involving VIP or CGRP acting upon antral D cells to stimulate somatostatin release. The ECL cell, D cell, and G cell therefore are responsible for endocrine and paracrine regulation of gastric acid secretion. We will define the actions of gastrin and somatostatin in regulation of ECL cells by a) determining how the ECL cell gastrin receptors that regulate histamine secretion and ECL cell proliferation differ from the parietal cell/brain CCK-B receptor, b) determining mechanisms for regulation of gastrin/CCK-B receptor signal transduction in ECL cells and in cells transfected with this receptor, and c) determining the mechanisms by which gastrin regulates proliferation of fibroblasts stably transfected with CCK-B receptors. We also will describe regulation of oxyntic and antral D cells and define their targets by a) determining how isolated oxyntic and antral D cells differ in their responses to neuropeptides and defining physiological reflexes in stimulation of somatostatin synthesis and release in oxyntic and antral glands and b) determining which of the five known somatostatin receptor subtypes are produced in the stomach and their cellular distribution. Finally, we will define the actions of somatostatin and GRP in regulation of G cells by a) characterizing the mechanisms by which somatostatin inhibits gastrin release and G cell proliferation, b) determining the distribution of GRP receptor subtypes and the role of local neural release of GRP in regulating of G cells, and c) defining pathways for desensitization, internalization, and resensitization of GRP receptors. These studies have important physiological implications for mechanisms for control of gastrointestinal mucosal secretion and growth by locally released peptides interacting with hormones and neurotransmitters.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK017294-24
Application #
2391304
Study Section
General Medicine A Subcommittee 2 (GMA)
Project Start
1977-02-15
Project End
2000-03-31
Budget Start
1997-04-01
Budget End
1998-03-31
Support Year
24
Fiscal Year
1997
Total Cost
Indirect Cost
Name
University of California Los Angeles
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
119132785
City
Los Angeles
State
CA
Country
United States
Zip Code
90095
Wu, S Vincent; Chen, Monica C; Rozengurt, Enrique (2005) Genomic organization, expression, and function of bitter taste receptors (T2R) in mouse and rat. Physiol Genomics 22:139-49
Slice, Lee W; Chiu, Terence; Rozengurt, Enrique (2005) Angiotensin II and epidermal growth factor induce cyclooxygenase-2 expression in intestinal epithelial cells through small GTPases using distinct signaling pathways. J Biol Chem 280:1582-93
Shin, Jai Moo; Grundler, Gerhard; Senn-Bilfinger, Jorg et al. (2005) Functional consequences of the oligomeric form of the membrane-bound gastric H,K-ATPase. Biochemistry 44:16321-32
Vagin, Olga; Turdikulova, Shahlo; Sachs, George (2004) The H,K-ATPase beta subunit as a model to study the role of N-glycosylation in membrane trafficking and apical sorting. J Biol Chem 279:39026-34
Hunger-Glaser, Isabel; Fan, Robert S; Perez-Salazar, Eduardo et al. (2004) PDGF and FGF induce focal adhesion kinase (FAK) phosphorylation at Ser-910: dissociation from Tyr-397 phosphorylation and requirement for ERK activation. J Cell Physiol 200:213-22
Kim, Nayoung; Marcus, Elizabeth A; Wen, Yi et al. (2004) Genes of Helicobacter pylori regulated by attachment to AGS cells. Infect Immun 72:2358-68
Vagin, O; Denevich, S; Sachs, G (2003) Plasma membrane delivery of the gastric H,K-ATPase: the role of beta-subunit glycosylation. Am J Physiol Cell Physiol 285:C968-76
Slice, Lee W; Hodikian, Raffi; Zhukova, Elena (2003) Gastrin and EGF synergistically induce cyclooxygenase-2 expression in Swiss 3T3 fibroblasts that express the CCK2 receptor. J Cell Physiol 196:454-63
Rey, Osvaldo; Zhukova, Elena; Sinnett-Smith, James et al. (2003) Vasopressin-induced intracellular redistribution of protein kinase D in intestinal epithelial cells. J Cell Physiol 196:483-92
Salazar, Eduardo Perez; Hunger-Glaser, Isabel; Rozengurt, Enrique (2003) Dissociation of focal adhesion kinase and paxillin tyrosine phosphorylation induced by bombesin and lysophosphatidic acid from epidermal growth factor receptor transactivation in Swiss 3T3 cells. J Cell Physiol 194:314-24

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