|
|
||||||||
AJP - Gastrointestinal and Liver Physiology, Vol 259, Issue 4 626-G630, Copyright © 1990 by American Physiological Society
ARTICLES |
A. P. Majumdar
Research Service, Veterans Administration Medical Center, Allen Park, Michigan 48101.
An organ culture system was utilized to evaluate the role of tyrosine kinases (Tyr-k) and tyrosine-specific phosphorylation of proteins in gastrin regulation of ornithine decarboxylase (ODC) activity in colonic mucosa. Exposure of colonic mucosal explants to gastrin (50-100 ng G-17 I/ml) resulted in a profound stimulation of both Tyr-k and ODC activities compared with the corresponding basal levels. Whereas the maximal stimulation (ranging between 70 and 150%) of Tyr-k occurred within 10-15 min of exposure to gastrin, ODC activity was significantly stimulated (180%) 2 h after exposure to the hormone, and at 4 h it was found to be 750% above the corresponding basal level. Difluoromethylornithine (DFMO; 2 mM), an irreversible inhibitor of ODC, completely abolished the gastrin-mediated stimulation of ODC but not Tyr-k activity. On the other hand, genistein (100 micrograms/ml), a specific inhibitor of Tyr-k, caused a total suppression of the gastrin-induced stimulation of both Tyr-k and ODC. Gastrin also stimulated tyrosyl phosphorylation of a colonic mucosal membrane protein with molecular mass of 57 kDa, and genistein greatly attenuated this effect. We conclude that gastrin stimulates colonic mucosal ODC in vitro, and Tyr-k may be required for the regulation of this process.
This article has been cited by other articles:
![]() |
H. Wu, A. Owlia, and P. Singh Precursor peptide progastrin1-80 reduces apoptosis of intestinal epithelial cells and upregulates cytochrome c oxidase Vb levels and synthesis of ATP Am J Physiol Gastrointest Liver Physiol, December 1, 2003; 285(6): G1097 - G1110. [Abstract] [Full Text] [PDF] |
||||
![]() |
P. Singh, X. Lu, S. Cobb, B. T. Miller, N. Tarasova, A. Varro, and A. Owlia Progastrin1-80 stimulates growth of intestinal epithelial cells in vitro via high-affinity binding sites Am J Physiol Gastrointest Liver Physiol, February 1, 2003; 284(2): G328 - G339. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. G Busby, A R. Jeffcoat, L. T Bloedon, M. A Koch, T. Black, K. J Dix, W. D Heizer, B. F Thomas, J. M Hill, J. A Crowell, et al. Clinical characteristics and pharmacokinetics of purified soy isoflavones: single-dose administration to healthy men Am. J. Clinical Nutrition, January 1, 2002; 75(1): 126 - 136. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Kidd, L. H. Tang, S. W. Schmid, K. Miu, and I. M. Modlin A polyamine pathway-mediated mitogenic mechanism in enterochromaffin-like cells of Mastomys Am J Physiol Gastrointest Liver Physiol, August 1, 1998; 275(2): G370 - G376. [Abstract] [Full Text] [PDF] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |