1 CURE/Division of Digestive Diseases and 2 Molecular Biology Institute, Department of Medicine, School of Medicine, University of California Los Angeles and The Medical and Research Services, Greater Los Angeles Veterans Affairs Health Care System, Los Angeles, California 70073
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ABSTRACT |
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Previous studies found that epidermal growth factor (EGF) decreased paracellular permeability in gastric mucosa, but the other physiological regulators and the molecular mechanisms mediating these responses remain undefined. We investigated the role of secretin and Src in regulating paracellular permeability because secretin regulates gastric chief cell function and Src mediates events involving the cytoskeletal-membrane interface, respectively. Confluent monolayers were formed from canine gastric epithelial cells in short-term culture on Transwell filter inserts. Resistance was monitored in the presence of secretin with or without specific kinase inhibitors. Tyrosine phosphorylation of Src at Tyr416 was measured with a site-specific phosphotyrosine antibody. Basolateral, but not apical, secretin at concentrations from 1 to 100 nM dose dependently increased resistance; this response was rapid and sustained over hours. PP2 (10 µM), a selective Src tyrosine kinase inhibitor, but not the inactive isomer PP3, abolished the increase in resistance by secretin but only modestly attenuated apical EGF effects. AG-1478 (100 nM), a specific EGF receptor tyrosine kinase inhibitor, attenuated the resistance increase to EGF but not secretin. Secretin, but not EGF, induced tyrosine phosphorylation of Src at Tyr416 in a dose-dependent fashion, with the maximal response observed at 1 min. PP2, but not PP3, dramatically inhibited this tyrosine phosphorylation. Secretin increases paracellular resistance in gastric mucosa through a Src-mediated pathway, while the effect of EGF is Src independent. Src appears to mediate the physiological effects of this Gs-coupled receptor in primary epithelial cells.
secretin receptors; epidermal growth factor receptors; gastric mucosal defense; paracellular pathway; regulation of paracellular pathway; apical epidermal growth factor receptors; PP2; tyrosine kinases
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INTRODUCTION |
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THE GASTRIC
MUCOSA has a remarkable ability to defend itself against injury
from the acid/peptic activity of gastric juice and to undergo rapid
repair when injury does occur. Mucosal defense and repair mechanisms
are multifactorial. Primary lines of defense involve the preepithelial
mucous and bicarbonate barrier, epithelial cell mechanisms, and
subepithelial blood flow, while critical repair mechanisms include
restitution (lateral migration of cells), replication, and wound
healing (1, 9, 21, 27, 36). Three categories of epithelial
cell function are involved in mucosal defense: 1) the apical
membrane, which is a component of the gastric barrier to acid diffusion
(3, 4, 26); 2) basolateral
Na+/H+ and
Cl/HCO
In studies with primary canine gastric monolayers, we also found that apical junctional permeability was regulated by epidermal growth factor (EGF; Ref. 4) and that this regulation had a major impact on the resistance of gastric monolayers to apical H+ (M. C. Chen and A. H. Soll, unpublished observations). These findings suggest that regulation of paracellular permeability is critical for maintenance of mucosal integrity in the face of luminal acid and pepsin. We also found consistent evidence that EGF increases transepithelial resistance (TER) by activating apical as well as basolateral receptors (4).
Secretin has well-defined effects on chief cells, stimulating pepsinogen secretion by canine chief cells, rat gastric glands, and purified guinea pig chief cells in vitro (20, 25, 28). Because chief cells are the major component of canine gastric epithelial monolayer cultures (3) and secretin induces pepsinogen release from these cultures (25), secretin is a candidate to regulate other actions in these gastric cells.
Numerous lines of evidence indicate that the paracellular pathway is
regulated (16, 33). However, despite exciting recent progress in the molecular structure of the junction (2, 14, 35), the physiology, pathophysiology, and molecular mechanisms of the regulatory process governing paracellular permeability remain
largely undefined. In particular, a role for Src in regulation of the
apical junctional complex has not been defined. However, Src has been
localized to the adherens junction [the zonula adherens (ZA)] of the
apical junctional complex of epithelial cells (31). Furthermore, Src has been found to induce the tyrosine phosphorylation of -catenin and p120 (8), two members of the ZA.
Therefore, the Src-family kinases are candidates that warrant investigation.
The rapid regulation of paracellular permeability by several chemotransmitters that we have found in our canine gastric monolayers provides a useful model for studying the molecular mechanisms underlying the regulation of paracellular permeability. In the studies presented here, we examined the effects and mechanism of action of secretin on paracellular permeability in cultured gastric mucosal cell monolayers. To define the molecular mechanisms mediating the action of secretin on paracellular permeability, we also studied the role of Src both using PP2, the highly selective inhibitor of the Src kinase family, and assessing auto-tyrosine-phosphorylation of Src kinase at Tyr416. We now report that secretin increases the resistance of the paracellular pathway of canine gastric cell monolayers in a fashion that is dependent on Src kinase family activity.
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METHODS |
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Tissue dispersion, cell separation, and culture. Enzyme-dispersed canine oxyntic mucosal cells were separated by elutriation and cultured on collagen-coated Transwell filter inserts (6 or 12 wells, Costar), as described previously (3, 4). The composition of the epithelial cells was about 70% chief cells and 20% parietal cells, with <10% surface and mucous neck cells (4, 10). Cells were cultured in DMEM-Ham's F-12 (1:1) plus 20 mM HEPES, 100 µg/ml amikacin, 100 U/ml penicillin, 100 µg/ml streptomycin, and 2% calf serum. Cultures were fed with the same medium every 48 h until confluent (~72 h). Monolayers were switched to serum-free medium (R0) for 6-16 h before experiments were performed.
Measurement of TER and mannitol flux. Resistance was monitored using an epithelial voltohmmeter (EVOM) with chopstick electrodes. This technique allows repeated measurements of monolayer resistance under sterile conditions. In all experiments, resistance data are calculated as the mean of 3 or 4 separate Transwell inserts and are expressed as a percent increase over the basal resistance. Apical-to-basolateral mannitol flux was determined by adding [3H]mannitol to the apical solution as previously described (3).
Western blot analysis. Monolayers were treated with or without various concentrations of kinase inhibitor for 15 min and followed by stimulation with growth factor or secretin. Cells were washed with ice-cold PBS containing PMSF (1 mM) and sodium vanadate (100 µM). Cells were lysed in 2× SDS-PAGE sample buffer (200 mM Tris · HCl, pH 6.8, 1 mM EDTA, 6% SDS, 2 mM EDTA, 4% 2-mercaptoethanol, 10% glycerol), followed by boiling for 10 min, and resolved by SDS-PAGE. After SDS-PAGE, proteins were transferred to Immobilon membranes. After transfer, membranes were blocked using 5% nonfat dried milk in PBS, pH 7.2, and incubated for 2 h at room temperature with rabbit anti- Src(P)Tyr416 Ab. The membranes were washed three times with PBS, pH 7.2, 0.1% Tween 20, and then incubated with secondary antibodies (horseradish peroxidase-conjugated donkey antibody to rabbit, NA 934) (1:5,000) for 1 h at room temperature. After washing three times with PBS, pH 7.2, 0.1% Tween 20, the immunoreactive bands were visualized using enhanced chemiluminescence (ECL) detection reagents. Autoradiograms were scanned, the labeled bands were quantified using the NIH Image program, and the intensities of specific bands were expressed in density units (% of basal).
Materials. Materials for cell cultures were obtained from sources outlined previously (4, 5). Transwell inserts were from Costar (Cambridge, MA), and human recombinant EGF was from R&D Systems (Minneapolis, MN). Rat secretin was obtained from the University of California Los Angeles Peptide Synthesis Core Facility. The EVOM Millicell-ERS was from Millipore (Bedford, MA). ECL reagents were from Amersham Pharmacia Biotech. Rabbit anti-Src(P)Tyr416 Ab was from Biosource (Camarillo, CA). AG-1478, Genestein, wortmannin, PP2, and PP3 were obtained from Calbiochem. Other chemicals were from Sigma Chemical (St. Louis, MO).
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RESULTS |
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Secretin increases TER of gastric monolayers.
Dispersed gastric mucosal cells plated in Transwell inserts form
monolayers after 72 h of incubation. Baseline TER of these monolayers, monitored with chopstick electrodes positioned
using a derrick, was 1,635 ± 425 · cm2
(mean ± SE; n = 8 separate preparations).
Increases in resistance are a reliable measure of decreased
paracellular permeability, as reflected by decreases in the flux of
mannitol (4). Because secretin regulates gastric chief
cell function and since these monolayers have a predominant chief cell
population, we investigated the effect of secretin on the TER of these monolayers.
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Src mediates secretin but not EGF actions on TER.
Src tyrosine kinase family is known to modulate interactions at the
cytoskeletal-membrane interface. Recently, Gs has been shown to promote Src activation (12). Given that the
secretin receptor couples to Gs, we examined whether PP2, a
specific inhibitor of Src-family tyrosine kinases, prevented the
increase in TER induced by secretin. In initial studies, PP2 alone at a
concentration of 10 µM caused up to a 20% transient decrease in
resistance compared with untreated controls. However, concentrations of
5 µM and below had no significant effect on baseline resistance (data
not shown, P > 0.2; n = 4). Subsequent
studies were performed using these lower concentrations. PP2 caused a
dose-dependent inhibition of secretin effects on TER (Fig.
2A). Inhibition by PP2 was
detectable at 0.1 µM and reached maximal at 5 µM. PP2 at 5 µM
decreased secretin-stimulated TER from 24 ± 2.5 to 1.7 ± 2%, n = 4, at t = 2 h. Inhibition
was comparable when PP2 was added to either the apical or basolateral solutions (P > 0.2; n = 3; data not
illustrated). A 5 µM concentration of PP3, a structurally related but
biologically inactive isomer, did not prevent the increase in TER
induced by secretin (Fig. 2B).
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Secretin induces autophosphorylation of Src at Tyr416.
A site-specific anti-phosphotyrosine antibody to Tyr416 of
Src was used to assess the activation of Src via this known
autophosphorylation event. Western blots, performed on lysates run on
PAGE and probed with antibody to Src(P)Tyr416, revealed two
bands at estimated molecular masses of 62 and 58 kDa (Fig.
4). PP2, in concentrations under 5 µM,
selectively blocked Src(P)Tyr416 phosphorylation of the
58-kDa band (Fig. 4B). Quantification of this band using
scanning densitometry demonstrated that PP2 inhibited the
phosphorylation of Tyr416 of Src in a dose-dependent
fashion (Fig. 4D). Half-maximal effect was obtained at a
concentration of ~1 µM. The results indicate the expression and
phosphorylation at Tyr416 of PP2-sensitive Src-family
kinases in canine gastric mucosa.
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DISCUSSION |
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The findings presented in this study establish three points: 1) secretin at nanomolar concentrations increases TER in canine gastric monolayer cultures; 2) the specific Src inhibitor PP2 blocks the increase in TER induced by secretin; and 3) secretin induces rapid autophosphorylation of a Src kinase, and PP2 attenuates this activation. These findings indicate that secretin regulates paracellular permeability and that Src kinase plays a critical role in mediating this effect. These results not only throw light on a potential physiological action of secretin in regulating mucosal resistance to injury, but they also highlight potential physiological roles for the Src kinase family both in the action of a receptor coupled to Gs and in regulating paracellular permeability.
Similar to EGF, basolateral secretin caused rapid, concentration-dependent increases in TER in our mixed-epithelial cell model of the gastric mucosa. Secretin increased TER within 5 min of treatment. However, the effects of secretin and EGF on TER differed in several ways. Secretin was effective only when applied to the basolateral surface of the epithelial monolayer, while EGF increased TER, acting at both apical and basolateral receptors. The action of secretin was blocked by the Src kinase inhibitor PP2, but not by the specific EGFR tyrosine kinase inhibitor AG-1478. In contrast, we found that the action of EGF on TER was blocked by AG-1478, but not PP2. We have also found that combined treatment with secretin and EGF produces a potentiating effect wherein the combined response is greater than the sum of the individual responses, a further indication that secretin and EGF act via different mechanisms to increase TER (Chen, Solomon, and Soll, unpublished observations).
Secretin has been reported by Rotoli et al. (22) to also modulate paracellular permeability in CAPAN-1 pancreatic cancer cells grown to confluence. However, in this system secretin was only studied at very high concentrations (1 µM) and produced opposite effects, decreasing TER and increasing paracellular permeability. It is unclear whether the opposite effects in this system reflect tissue differences (stomach vs. pancreas), neoplastic vs. normal cells, or the much higher concentrations studied.
The potency of secretin for altering TER in these gastric epithelial monolayers indicates activation at a specific secretin receptor. Indirect evidence supports the existence of functional secretin receptors on gastric chief and mucous cells, but not parietal cells (11, 20, 25, 28). To date, only one secretin receptor has been cloned and characterized (34). It is a G protein-coupled receptor (GPCR) with a very long amino terminal extracellular region, a structural characteristic that has been used to define a large subfamily of GPCRs. This receptor appears to be widely distributed in many organs (including the stomach), based on Northern blot analysis of tissue extracts (34). However, the specific cell types expressing the receptor have only been defined in the pancreas and liver.
The secretin receptor is generally considered to be coupled to Gs and thus to activate cells via adenylyl cyclase and protein kinase A (PKA). In every secretin-responsive cell type that has been studied, secretin has been found to activate adenylyl cyclase and/or increase cellular cAMP concentration (34). However, at high concentrations, secretin also increases cellular Ca2+ levels (18, 30), indicating that coupling to Gq can occur under certain circumstances. At the concentrations used in our experiments, we anticipate that secretin receptor action is primarily coupled to Gs.
Several lines of evidence indicate that Src kinase plays a physiological role in secretin action in this model system. First, secretin autophosphorylation of Src was demonstrated using site-specific antibodies for Tyr416. Second, autophosphorylation of Src was rapid (peak at 1 min) and occurred over the same nanomolar concentration range in which secretin regulated TER. Third, secretin action on both TER and autophosphorylation of Tyr416 was inhibited by the same low micromolar concentration range of PP2, whereas the inactive analog PP3 was without effect. PP2 in these concentrations is highly specific for the Src kinase family. Our observations that secretin acts in a Src-dependent fashion are novel.
Src kinases are an important family of nonreceptor protein tyrosine
kinases that transduce multiple upstream signals into numerous
downstream actions on cell growth, differentiation, migration, structure, and secretion (29). Although linked to the
actions of growth factors such as EGF, Src kinases also participate in the actions of GPCRs. Most of the available evidence regarding GPCRs
indicates Src activation by Gq-coupled receptors (13, 19, 23). However, recent studies with primary cultures of mouse
brown adipocytes indicated that PP2 partially inhibited vascular
endothelial growth factor gene expression in response to the
Gs-coupled 3-adrenergic receptor
(7). Our findings that secretin induces the
autophosphorylation of Src and that PP2 completely inhibits secretin
action indicate that Src-family kinases can mediate
Gs-coupled receptor action.
The mechanism by which secretin activates Src kinases is unknown.
Assuming that it involves primarily a Gs-coupled initiation site, there are at least two potential subsequent steps. The first would be the well-defined adenylyl cyclase-cAMP-PKA pathway initiated by Gs activation. Src has potential sites of PKA
serine/threonine phosphorylation (29), but it is not known
if such phosphorylation occurs or if it alters Src function. This
mechanism is supported by the work of Fredriksson et al.
(7) who found the action of 3-receptor
activation was completely blocked by the PKA inhibitor H89 and, as
described above, partially by the Src kinase inhibitor PP2. One
interpretation of this pattern is the sequential activation of PKA and
Src kinase. Another possible pathway has recently been described by Ma
et al. (12), who demonstrated that both activated Gs and Gi, but not Gq or
G12, bound to and activated Src. Furthermore, tyrosine
phosphorylation in response to constitutively active Gs was
markedly reduced in fibroblasts from knockout strains deficient in Src,
Fyn, and Yes (12). Taken together, these studies support a
link between Gs-coupled receptors and Src, although there
is disagreement regarding whether PKA is involved in activating Src. The identity of the 58-kDa Src-family kinase involved in the dramatic secretin activation in our system is not resolved in the current study.
Our preliminary data suspect that the Src family member may be Fyn, not
Yes, but we have not yet been able to firmly establish this point.
The manner in which Src activation leads to changes in TER is not
known. Src activates a variety of proteins involved in
cytoskeletal-membrane function, such as FAK, paxillin, and Pyk2
(24, 32). Src has been localized to the ZA
(31) and induces the tyrosine phosphorylation of
-catenin and p120 (8), but no role in the function or
structure of the apical junctional complex has been defined. It is
likely that changes in the architecture and ionic characteristics of the apical junctional region are of paramount importance to controlling permeability, but these changes have not yet been defined.
Our model appears well suited to sort out both the physiological relevance and molecular mechanisms linking Gs-coupled receptors to Src and governing regulation of the paracellular permeability.
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ACKNOWLEDGEMENTS |
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This research was supported by National Institute of Diabetes and Digestive and Kidney Diseases Grant DK-19984, the Gonzales Foundation, and the Medical and Research Services of the Department of Veterans Affairs.
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FOOTNOTES |
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Address for reprint requests and other correspondence: A. H. Soll, VA Wadsworth Hospital Center, Bldg. 115, Rm. 215, 11301 Wilshire Blvd., Los Angeles, CA 90073 (E-mail: asoll{at}ucla.edu).
The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
July 3, 2002;10.1152/ajpgi.00429.2001
Received 5 October 2001; accepted in final form 7 June 2002.
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REFERENCES |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
1.
Allen, A,
Flemstrom G,
Garner A,
and
Kivilaakso E.
Gastroduodenal mucosal protection.
Physiol Rev
73:
823-857,
1993
2.
Anderson, JM.
Molecular structure of tight junctions and their role in epithelial transport.
News Physiol Sci
16:
126-130,
2001
3.
Chen, MC,
Chang A,
Buhl T,
Tanner M,
and
Soll AH.
Apical acidification induces paracellular injury in canine gastric mucosal monolayers.
Am J Physiol Gastrointest Liver Physiol
267:
G1012-G1020,
1994
4.
Chen, MC,
Goliger J,
Bunnett N,
and
Soll AH.
Apical and basolateral EGF receptors regulate gastric mucosal paracellular permeability.
Am J Physiol Gastrointest Liver Physiol
280:
G264-G272,
2001
5.
Chen, MC,
Lee AT,
and
Soll AH.
Mitogenic response of canine fundic epithelial cells in short-term culture to transforming growth factor- and insulin-like growth factor 1.
J Clin Invest
87:
1716-1723,
1991[ISI][Medline].
6.
Chu, S,
Tanaka S,
Kaunitz JD,
and
Montrose MH.
Dynamic regulation of gastric surface pH by luminal pH.
J Clin Invest
103:
605-612,
1999
7.
Fredriksson, JM,
Lindquist JM,
Bronnikov GE,
and
Nedergaard J.
Norepinephrine induces vascular endothelial growth factor gene expression in brown adipocytes through a -adrenoreceptor/cAMP/protein kinase A pathway involving Src but independently of Erk1/2.
J Biol Chem
275:
13802-13811,
2000
8.
Gomez, S,
Mont Llosas M,
Verdu J,
Roura S,
Lloreta J,
Fabre M,
and
Garcia de Herreros A.
Independent regulation of adherens and tight junctions by tyrosine phosphorylation in Caco-2 cells.
Biochim Biophys Acta
1452:
121-132,
1999[ISI][Medline].
9.
Jones, MK,
Tomikawa M,
Mohajer B,
and
Tarnawski AS.
Gastrointestinal mucosal regeneration: role of growth factors.
Front Biosci
4:
D303-D309,
1999[Medline].
10.
Kato, K,
Chen MC,
Nguyen M,
Lehmann FS,
Podolsky DK,
and
Soll AH.
Effects Of growth factors and trefoil peptides on migration and replication in primary oxyntic cultures.
Am J Physiol Gastrointest Liver Physiol
276:
G1105-G1116,
1999
11.
Keates, AC,
and
Hanson PJ.
Regulation of mucus secretion by cells isolated from the rat gastric mucosa.
J Physiol
423:
397-409,
1990[Abstract].
12.
Ma, YC,
Huang J,
Ali S,
Lowry W,
and
Huang XY.
Src tyrosine kinase is a novel direct effector of G proteins.
Cell
102:
635-646,
2000[ISI][Medline].
13.
Miller, WE,
and
Lefkowitz RJ.
Expanding roles for beta-arrestins as scaffolds and adapters in GPCR signaling and trafficking.
Curr Opin Cell Biol
13:
139-145,
2001[ISI][Medline].
14.
Mitic, LL,
and
Anderson JM.
Molecular architecture of tight junctions.
Annu Rev Physiol
60:
121-142,
1998[ISI][Medline].
15.
Nakamura, K,
Rokutan K,
Marui N,
Niki S,
Aoike A,
and
Kawai K.
Induction of heat shock proteins and their implication in protection against ethanol-induced damage in cultured guinea pig gastric mucosal cells.
Gastroenterology
101:
161-166,
1991[ISI][Medline].
16.
Nusrat, A,
Turner JR,
and
Madara JL.
Molecular physiology and pathophysiology of tight junctions. IV. Regulation of tight junctions by extracellular stimuli: nutrients, cytokines, and immune cells.
Am J Physiol Gastrointest Liver Physiol
279:
G851-G857,
2000
17.
Olson, CE.
Glutathione modulates toxic oxygen metabolite injury of canine chief cell monolayers in primary culture.
Am J Physiol Gastrointest Liver Physiol
254:
G49-G56,
1988
18.
Patel, DR,
Kong Y,
and
Sreedharan SP.
Molecular cloning and expression of a human secretin receptor.
Mol Pharmacol
47:
467-473,
1995[Abstract].
19.
Ram, PT,
and
Iyengar R.
G protein coupled receptor signaling through the Src and Stat3 pathway: role in proliferation and transformation.
Oncogene
20:
1601-1606,
2001[ISI][Medline].
20.
Raufman, JP,
Kasbekar DK,
Jensen RT,
and
Gardner JD.
Potentiation of pepsinogen secretion from dispersed glands from rat stomach.
Am J Physiol Gastrointest Liver Physiol
245:
G525-G530,
1983
21.
Romano, M,
Kraus ER,
Boland CR,
and
Coffey RJ.
Comparison between transforming growth factor alpha and epidermal growth factor in the protection of rat gastric mucosa against drug-induced injury.
Ital J Gastroenterol
26:
223-228,
1994[ISI][Medline].
22.
Rotoli, BM,
Bussolati O,
Dall'Asta V,
Orlandini G,
Gatti R,
and
Gazzola GC.
Secretin increases the paracellular permeability of CAPAN-1 pancreatic duct cells.
Cell Physiol Biochem
10:
13-25,
2000[ISI][Medline].
23.
Rozengurt, E,
and
Walsh JH.
Gastrin, CCK, signaling, and cancer.
Annu Rev Physiol
63:
49-76,
2001[ISI][Medline].
24.
Salazar, EP,
and
Rozengurt E.
Src family kinases are required for integrin-mediated but not for G protein-coupled receptor stimulation of focal adhesion kinase autophosphorylation at Tyr-397.
J Biol Chem
276:
17788-17795,
2001
25.
Sanders, MJ,
Amirian DA,
Ayalon A,
and
Soll AH.
Regulation of pepsinogen release from canine chief cells in primary monolayer culture.
Am J Physiol Gastrointest Liver Physiol
245:
G641-G646,
1983
26.
Sanders, MJ,
Ayalon A,
Roll M,
and
Soll AH.
The apical surface of canine chief cell monolayers resists H+ back-diffusion.
Nature
313:
52-54,
1985[ISI][Medline].
27.
Soll, AH.
Gastric, duodenal, and stress ulcer.
In: Gastrointestinal Disease, edited by Sleisenger M,
and Fordtran J.. Philadelphia, PA: Saunders, 1993, p. 580-679.
28.
Tanaka, T,
and
Tani S.
Interaction among secretagogues on pepsinogen secretion from rat gastric chief cells.
Biol Pharm Bull
18:
859-865,
1995[ISI][Medline].
29.
Thomas, SM,
and
Brugge JS.
Cellular functions regulated by Src family kinases.
Annu Rev Cell Dev Biol
13:
513-609,
1997[ISI][Medline].
30.
Trimble, ER,
Bruzzone R,
Biden TJ,
and
Farese RV.
Secretin induces rapid increases in inositol trisphosphate, cytosolic Ca2+ and diacylglycerol as well as cyclic AMP in rat pancreatic acini.
Biochem J
239:
257-261,
1986[ISI][Medline].
31.
Tsukita, S,
Oishi K,
Akiyama T,
Yamanashi Y,
Yamamoto T,
and
Tsukita S.
Specific proto-oncogenic tyrosine kinases of src family are enriched in cell-to-cell adherens junctions where the level of tyrosine phosphorylation is elevated.
J Cell Biol
113:
867-879,
1991[Abstract].
32.
Turner, CE.
Paxillin and focal adhesion signalling.
Nature Cell Biology
2:
E231-E236,
2000[ISI][Medline].
33.
Turner, JR.
"Putting the squeeze" on the tight junction: understanding cytoskeletal regulation.
Semin Cell Dev Biol
11:
301-308,
2000[ISI][Medline].
34.
Ulrich, CD,
Holtmann M,
and
Miller LJ.
Secretin and vasoactive intestinal peptide receptors: members of a unique family of G protein-coupled receptors.
Gastroenterology
114:
382-397,
1998[ISI][Medline].
35.
Van Itallie, C,
Rahner C,
and
Anderson JM.
Regulated expression of claudin-4 decreases paracellular conductance through a selective decrease in sodium permeability.
J Clin Invest
107:
1319-1327,
2001
36.
Wallace, JL,
and
Granger DN.
The cellular and molecular basis of gastric mucosal defense.
FASEB J
10:
731-740,
1996
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