scholarly journals Polarized Distribution of IQGAP Proteins in Gastric Parietal Cells and Their Roles in Regulated Epithelial Cell Secretion

2003 ◽  
Vol 14 (3) ◽  
pp. 1097-1108 ◽  
Author(s):  
Rihong Zhou ◽  
Zhen Guo ◽  
Charles Watson ◽  
Emily Chen ◽  
Rong Kong ◽  
...  
Keyword(s):  
Epithelial Cell ◽  
Actin Cytoskeleton ◽  
Acid Secretion ◽  
Rho Gtpase ◽  
Apical Membrane ◽  
Basolateral Membrane ◽  
Parietal Cells ◽  
Actin Dynamics ◽  
Cell Secretion ◽  
Gastric Parietal Cells

Actin cytoskeleton plays an important role in the establishment of epithelial cell polarity. Cdc42, a member of Rho GTPase family, modulates actin dynamics via its regulators, such as IQGAP proteins. Gastric parietal cells are polarized epithelial cells in which regulated acid secretion occurs in the apical membrane upon stimulation. We have previously shown that actin isoforms are polarized to different membrane domains and that the integrity of the actin cytoskeleton is essential for acid secretion. Herein, we show that Cdc42 is preferentially distributed to the apical membrane of gastric parietal cells. In addition, we revealed that two Cdc42 regulators, IQGAP1 and IQGAP2, are present in gastric parietal cells. Interestingly, IQGAP2 is polarized to the apical membrane of the parietal cells, whereas IQGAP1 is mainly distributed to the basolateral membrane. An IQGAP peptide that competes with full-length IQGAP proteins for Cdc42-binding in vitro also inhibits acid secretion in streptolysin-O-permeabilized gastric glands. Furthermore, this peptide disrupts the association of IQGAP and Cdc42 with the apical actin cytoskeleton and prevents the apical membrane remodeling upon stimulation. We propose that IQGAP2 forms a link that associates Cdc42 with the apical cytoskeleton and thus allows for activation of polarized secretion in gastric parietal cells.

Immunological localization of an 80-kDa phosphoprotein to the apical membrane of gastric parietal cells

1989 ◽  
Vol 256 (6) ◽  
pp. G1082-G1089 ◽  
Author(s):  
D. K. Hanzel ◽  
T. Urushidani ◽  
W. R. Usinger ◽  
A. Smolka ◽  
J. G. Forte
Keyword(s):  
Monoclonal Antibodies ◽  
Acid Secretion ◽  
Parietal Cell ◽  
Blood Cells ◽  
Apical Membrane ◽  
Staining Pattern ◽  
Parietal Cells ◽  
Entire Cell ◽  
Gastric Parietal Cells ◽  
Stimulation Of

Monoclonal antibodies were raised against an 80-kDa phosphoprotein (80K) that is phosphorylated upon stimulation of gastric acid secretion and that copurifies with the acid-forming H+-K+-ATPase isolated from stimulated tissue. These antibodies were used to demonstrate that in the gastric mucosa 80K is limited to parietal cells and not found in surface, mucous neck, or chief cells. 80K was also found in other transporting epithelia, including intestine and kidney, but was not found in brain, liver, red blood cells, or colon. Immunohistological localization of 80K in resting glands revealed a fine network, projecting from the gland lumen and anastomosing throughout the parietal cell. This network is quite similar to the staining pattern for F-actin contained in microvilli that line the apical membrane of parietal cells. Stimulation of acid secretion rearranges 80K to a more rugose pattern filling the entire cell. In stimulated cells the distribution pattern of 80K is indistinguishable from that stained with antibodies against the H+-K+-ATPase. These data strongly suggest that 80K is an apical membrane protein of the parietal cell.

scholarly journals Acid secretion-associated translocation of KCNJ15 in gastric parietal cells

2011 ◽  
Vol 301 (4) ◽  
pp. G591-G600 ◽  
Author(s):  
Wenjun He ◽  
Wensheng Liu ◽  
Catherine S. Chew ◽  
Susan S. Baker ◽  
Robert D. Baker ◽  
...  
Keyword(s):  
Gastric Mucosa ◽  
Western Blot ◽  
Acid Secretion ◽  
Blot Analysis ◽  
Western Blot Analysis ◽  
Apical Membrane ◽  
Parietal Cells ◽  
Immunofluorescence Staining ◽  
Gastric Glands ◽  
Gastric Parietal Cells

Potassium ions are required for gastric acid secretion. Several potassium channels have been implicated in providing K+ at the apical membrane of parietal cells. In examining the mRNA expression levels between gastric mucosa and liver tissue, KCNJ15 stood out as the most highly specific K+ channel in the gastric mucosa. Western blot analysis confirmed that KCNJ15 is abundant in the stomach. Immunofluorescence staining of isolated gastric glands indicated that KCNJ15 was expressed in parietal cells and chief cells, but not in mucous neck cells. In resting parietal cells, KCNJ15 was mainly found in puncta throughout the cytoplasm but was distinct from H+-K+-ATPase. Upon stimulation, KCNJ15 and H+-K+-ATPase become colocalized on the apical membranes, as suggested by immunofluorescence staining. Western blot analysis of the resting and the stimulated membrane fractions confirmed this observation. From nonsecreting preparations, KCNJ15-containing vesicles sedimented after a 4-h centrifugation at 100,000 g, but not after a 30-min spin, which did sediment most of the H+-K+-ATPase-containing tubulovesicles. Most of the KCNJ15 containing small vesicle population was depleted upon stimulation of parietal cells, as indicated by the fact that the KCNJ15 signal was shifted to a large membrane fraction that sedimented at 4,000 g. Our results demonstrate that, in nonsecreting parietal cells, KCNJ15 is stored in vesicles distinct from the H+-K+-ATPase-enriched tubulovesicles. Furthermore, upon stimulation, KCNJ15 and H+-K+-ATPase both translocate to the apical membrane for active acid secretion. Thus KCNJ15 can be added to the family of apical K+ channels in gastric parietal cells.

State of actin in gastric parietal cells

1998 ◽  
Vol 274 (1) ◽  
pp. C97-C104 ◽  
Author(s):  
John G. Forte ◽  
Bernice Ly ◽  
Qinfen Rong ◽  
Shoji Ogihara ◽  
Marlon Ramilo ◽  
...  
Keyword(s):  
Acid Secretion ◽  
Parietal Cell ◽  
Parietal Cells ◽  
Secretory Process ◽  
Cell Protein ◽  
Cell Secretion ◽  
Gastric Glands ◽  
Western Blot Assay ◽  
Deoxyribonuclease I ◽  
Gastric Parietal Cells

Remodeling of the apical membrane-cytoskeleton has been suggested to occur when gastric parietal cells are stimulated to secrete HCl. The present experiments assayed the relative amounts of F-actin and G-actin in gastric glands and parietal cells, as well as the changes in the state of actin on stimulation. Glands and cells were treated with a Nonidet P-40 extraction buffer for separation into detergent-soluble (supernatant) and detergent-insoluble (pellet) pools. Two actin assays were used to quantitate actin: the deoxyribonuclease I binding assay to measure G-actin and F-actin content in the two pools and a simple Western blot assay to quantitate the relative amounts of actin in the pools. Functional secretory responsiveness was assayed by aminopyrine accumulation. About 5% of the total parietal cell protein is actin, with about 90% of the actin present as F-actin. Stimulation of acid secretion resulted in no measurable change in the relative amounts of G-actin and cytoskeletal F-actin. Treatment of gastric glands with cytochalasin D inhibited acid secretion and resulted in a decrease in F-actin and an increase in G-actin. No inhibition of parietal cell secretion was observed when phalloidin was used to stabilize actin filaments. These data are consistent with the hypothesis that microfilamentous actin is essential for membrane recruitment underlying parietal cell secretion. Although the experiments do not eliminate the importance of rapid exchange between G- and F-actin for the secretory process, the parietal cell maintains actin in a highly polymerized state, and no measurable changes in the steady-state ratio of G-actin to F-actin are associated with stimulation to secrete acid.

Identification of a basolateral Cl−/HCO 3 − exchanger specific to gastric parietal cells

2003 ◽  
Vol 284 (6) ◽  
pp. G1093-G1103 ◽  
Author(s):  
Snezana Petrovic ◽  
Xie Ju ◽  
Sharon Barone ◽  
Ursula Seidler ◽  
Seth L. Alper ◽  
...  
Keyword(s):  
Acid Secretion ◽  
Gastric Acid Secretion ◽  
Gastric Acid ◽  
Basolateral Membrane ◽  
Parietal Cells ◽  
Rt Pcr ◽  
Functional Studies ◽  
Distribution Studies ◽  
Immunofluorescence Labeling ◽  
Gastric Parietal Cells

The basolateral Cl−/HCO[Formula: see text] exchanger in parietal cells plays an essential role in gastric acid secretion mediated via the apical gastric H+-K+-ATPase. Here, we report the identification of a new Cl−/HCO[Formula: see text]exchanger, which shows exclusive expression in mouse stomach and kidney, with expression in the stomach limited to the basolateral membrane of gastric parietal cells. Tissue distribution studies by RT-PCR and Northern hybridizations demonstrated the exclusive expression of this transporter, also known as SLC26A7, to stomach and kidney, with the stomach expression significantly more abundant. No expression was detected in the intestine. Cellular distribution studies by RT-PCR and Northern hybridizations demonstrated predominant localization of SLC26A7 in gastric parietal cells. Immunofluorescence labeling localized this exchanger exclusively to the basolateral membrane of gastric parietal cells, and functional studies in oocytes indicated that SLC26A7 is a DIDS-sensitive Cl−/HCO[Formula: see text] exchanger that is active in both acidic and alkaline pHi. On the basis of its unique expression pattern and function, we propose that SLC26A7 is a basolateral Cl−/HCO[Formula: see text] exchanger in gastric parietal cells and plays a major role in gastric acid secretion.

Myosin II is present in gastric parietal cells and required for lamellipodial dynamics associated with cell activation

2003 ◽  
Vol 285 (3) ◽  
pp. C662-C673 ◽  
Author(s):  
Rihong Zhou ◽  
Charles Watson ◽  
Chuanhai Fu ◽  
Xuebiao Yao ◽  
John G. Forte
Keyword(s):  
Cell Activation ◽  
Apical Membrane ◽  
Basolateral Membrane ◽  
Myosin Ii ◽  
Parietal Cells ◽  
Immunofluorescent Staining ◽  
Nonmuscle Myosin ◽  
Nonmuscle Myosin Ii ◽  
Myosin Iia ◽  
Gastric Parietal Cells

Nonmuscle myosin II has been shown to participate in organizing the actin cytoskeleton in polarized epithelial cells. Vectorial acid secretion in cultured parietal cells involves translocation of proton pumps from cytoplasmic vesicular membranes to the apical plasma membrane vacuole with coordinated lamellipodial dynamics at the basolateral membrane. Here we identify nonmuscle myosin II in rabbit gastric parietal cells. Western blots with isoform-specific antibodies indicate that myosin IIA is present in both cytosolic and particulate membrane fractions whereas the IIB isoform is associated only with particulate fractions. Immunofluorescent staining demonstrates that myosin IIA is diffusely located throughout the cytoplasm of resting parietal cells. However, after stimulation, myosin IIA is rapidly redistributed to lamellipodial extensions at the cell periphery; virtually all the cytoplasmic myosin IIA joins the newly formed basolateral membrane extensions. 2,3-Butanedione monoximine (BDM), a myosin-ATPase inhibitor, greatly diminishes the lamellipodial dynamics elicited by stimulation and retains the pattern of myosin IIA cytoplasmic staining. However, BDM had no apparent effect on the stimulation associated redistribution of H,K-ATPase from a cytoplasmic membrane compartment to apical membrane vacuoles. The myosin light chain kinase inhibitor 1-(5-iodonaphthalene-1-sulfonyl)-1 H-hexahydro-1,4-diazepine (ML-7) also did not alter the stimulation-associated recruitment of H,K-ATPase to apical membrane vacuoles, but unlike BDM it had relatively minor inhibitory effects on lamellipodial dynamics. We conclude that specific disruption of the basolateral actomyosin cytoskeleton has no demonstrable effect on recruitment of H,K-ATPase-rich vesicles into the apical secretory membrane. However, myosin II plays an important role in regulating lamellipodial dynamics and cortical actomyosin associated with parietal cell activation.

scholarly journals Modeling acute ethanol-induced impairment with gastric organoids

2021 ◽  
Author(s):  
Wanjuan Wang ◽  
Ying Zhao ◽  
Zeqi Su ◽  
Fuhao Chu ◽  
Tao Li ◽  
...  
Keyword(s):  
Gastric Carcinoma ◽  
Molecular Mechanisms ◽  
Apical Membrane ◽  
Parietal Cells ◽  
Basic Medium ◽  
Cell Physiology ◽  
Membrane Cytoskeleton ◽  
Acute Ethanol ◽  
Functional Consequences ◽  
Gastric Parietal Cells

Abstract Background: Ethanol has been linked to atrophic gastritis and gastric carcinoma. Although it is well known that ethanol can result in hypochlorhydria, the molecular mechanisms underlying this phenomenon remain poorly understood.Results: Here we used gastric organoids to show that ethanol permeabilized the apical membrane of gastric parietal cells and induced ezrin hypochlorhydria. The functional consequences of ethanol on parietal cell physiology were studied using organoids. Gastric organoids were pre-incubated in the basic medium or with EGTA or E64 , and incubated at 37℃ in either medium alone, or medium containing 6% ethanol. We assessed ezrin proteolysis. Ethanol permeabilization induced activation of calpainⅠand subsequent proteolysis of ezrin, which resulted in the liberation of ezrin from the apical membrane of the parietal cells. Significantly, expression of calpain-resistant ezrin restored the functional activity of parietal cells in the presence of ethanol.Conclusion: Taken together, our data indicated that ethanol disrupted the apical membrane-cytoskeleton interactions in gastric parietal cells and thereby caused hypochlorhydria.

Potassium channel KCNJ15 is required for histamine-stimulated gastric acid secretion

2015 ◽  
Vol 309 (4) ◽  
pp. C264-C270 ◽  
Author(s):  
Jianye Yuan ◽  
Wensheng Liu ◽  
Serhan Karvar ◽  
Susan S. Baker ◽  
Wenjun He ◽  
...  
Keyword(s):  
Acid Secretion ◽  
Gastric Acid Secretion ◽  
Gastric Acid ◽  
Apical Membrane ◽  
Imaging System ◽  
Parietal Cells ◽  
Live Cells ◽  
Protein Levels ◽  
Endogenous Protein ◽  
Luminal Side

Gastric acid secretion is mediated by the K+-dependent proton pump (H+,K+-ATPase), which requires a continuous supply of K+ at the luminal side of the apical membrane. Several K+ channels are implicated in gastric acid secretion. However, the identity of the K+ channel(s) responsible for apical K+ supply is still elusive. Our previous studies have shown the translocation of KCNJ15 from cytoplasmic vesicles to the apical membrane on stimulation, indicating its involvement in gastric acid secretion. In this study, the stimulation associated trafficking of KCNJ15 was observed in a more native context with a live cell imaging system. KCNJ15 molecules in resting live cells were scattered in cytoplasm but exhibited apical localization after stimulation. Furthermore, knocking down KCNJ15 expression with a short hairpin RNA adenoviral construct abolished histamine-stimulated acid secretion in rabbit primary parietal cells. Moreover, KCNJ15, like H+,K+-ATPase, was detected in all of the parietal cells by immunofluorescence staining, whereas only about half of the parietal cells were positive for KCNQ1 under the same condition. Consistently, the endogenous protein levels of KCNJ15, analyzed by Western blotting, were higher than those of KCNQ1 in the gastric mucosa of human, mouse, and rabbit. These results provide evidence for a major role of KCNJ15 in apical K+ supply during stimulated acid secretion.

Effect of Histamine H2-Receptor Antagonists on Vitamin B12 Absorption

1992 ◽  
Vol 26 (10) ◽  
pp. 1283-1286 ◽  
Author(s):  
Rex W. Force ◽  
Milap C. Nahata
Keyword(s):  
Acid Secretion ◽  
Healthcare Providers ◽  
Intrinsic Factor ◽  
Parietal Cells ◽  
Data Sources ◽  
Vitamin B ◽  
Receptor Antagonists ◽  
Histamine H2 Receptor ◽  
Medline Search ◽  
Gastric Parietal Cells

OBJECTIVE: To discuss the potential of histamine H2-receptor antagonists (H2RAs) to cause malabsorption of vitamin B12 (cyanocobalamin). DATA SOURCES: Pertinent literature was identified via a MEDLINE search. Journals and references cited in published articles also were used as data sources. STUDY SELECTION: Studies evaluating the effect of H2RAs on vitamin B12 absorption were reviewed. DATA SYNTHESIS: H2RAs decrease acid secretion by the gastric parietal cells. Gastric acid and pepsin produced by these cells are required for the cleavage of vitamin B12 from dietary sources. Intrinsic factor (IF), also produced by gastric parietal cells, is required for vitamin B12 absorption from the gastrointestinal tract. Although H2RAs have not conclusively been shown to decrease IF secretion, studies have demonstrated a significant reduction in food-bound vitamin B12 absorption secondary to decreased acid secretion in patients taking these drugs. CONCLUSIONS: H2RAs have the potential to cause vitamin B12 deficiency. This may be important in patients with inadequate stores of vitamin B12 (e.g., poor diet), particularly those receiving H2RA therapy continuously for more than two years. Healthcare providers should be aware of this potential adverse effect.

scholarly journals Inhibition of Acid Secretion in Gastric Parietal Cells by the Ca2+/ Calmodulin-Dependent Protein Kinase II Inhibitor KN-93.

1994 ◽  
Vol 64 ◽  
pp. 90
Author(s):  
NAOTO MAMIYA ◽  
JAMES R. GOLDENRING ◽  
YASUHIRO TSUNODA ◽  
IRVIN M. MODLIN ◽  
KIYOSHI YASUI ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Acid Secretion ◽  
Parietal Cells ◽  
Dependent Protein Kinase ◽  
Protein Kinase Ii ◽  
Dependent Protein ◽  
Gastric Parietal Cells
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