Modeling acute ethanol-induced impairment with gastric organoids

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.

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Modeling Acute Ethanol-Induced Impairment with Gastric Organoids

10.21203/rs.3.rs-42294/v1 ◽

2020 ◽

Author(s):

Wanjuan Wang ◽

Ying Zhao ◽

Zeqi Su ◽

Fuhao Chu ◽

Tao Li ◽

...

Keyword(s):

Gastric Carcinoma ◽

Functional Activity ◽

Molecular Mechanisms ◽

Apical Membrane ◽

Parietal Cells ◽

Basic Medium ◽

Cell Physiology ◽

Acute Ethanol ◽

Functional Consequences ◽

Gastric Parietal Cells

Abstract Background: Ethanol have 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-cytoskeletal interactions in gastric parietal cells and thereby caused hypochlorhydria.

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

Molecular Biology of the Cell ◽

10.1091/mbc.e02-07-0425 ◽

2003 ◽

Vol 14 (3) ◽

pp. 1097-1108 ◽

Cited By ~ 25

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.

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

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1989.256.6.g1082 ◽

1989 ◽

Vol 256 (6) ◽

pp. G1082-G1089 ◽

Cited By ~ 17

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.

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Acid secretion-associated translocation of KCNJ15 in gastric parietal cells

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00460.2010 ◽

2011 ◽

Vol 301 (4) ◽

pp. G591-G600 ◽

Cited By ~ 16

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.

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Molecular mechanisms of H+ and Cl− secretion in gastric parietal cells

Folia Pharmacologica Japonica ◽

10.1254/fpj.138.51 ◽

2011 ◽

Vol 138 (2) ◽

pp. 51-55

Author(s):

Takuto Fujii ◽

Magotoshi Morii ◽

Noriaki Takeguchi ◽

Hideki Sakai

Keyword(s):

Molecular Mechanisms ◽

Parietal Cells ◽

Cl Secretion ◽

Gastric Parietal Cells

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Gastric parietal cell H(+)-K(+)-ATPase microsomes are associated with isoforms of ankyrin and spectrin

AJP Cell Physiology ◽

10.1152/ajpcell.1993.264.1.c63 ◽

1993 ◽

Vol 264 (1) ◽

pp. C63-C70 ◽

Cited By ~ 42

Author(s):

P. R. Smith ◽

A. L. Bradford ◽

E. H. Joe ◽

K. J. Angelides ◽

D. J. Benos ◽

...

Keyword(s):

Apical Membrane ◽

Immunoblot Analysis ◽

Cytoskeletal Proteins ◽

Parietal Cells ◽

Apical Surface ◽

Gastric Parietal Cell ◽

Apical Domain ◽

Hcl Secretion ◽

Gastric Parietal Cells ◽

Stimulation Of

Stimulation of HCl secretion by gastric parietal cells requires the fusion of cytoplasmic H(+)-K(+)-ATPase-bearing tubulovesicles with the apical membrane. This insertion of membrane results in a dramatic increase in apical surface area through the formation of microvilli. To elucidate the elements that may stabilize the newly inserted H(+)-K(+)-ATPase within the apical membrane, we searched for specific cytoskeletal proteins associating with the gastric enzyme. We document by immunoblot analysis that ankyrin, spectrin, and actin copurify with H(+)-K(+)-ATPase microsomes prepared from gastric parietal cells. Coprecipitation of 125I-labeled native erythrocyte ankyrin with the H(+)-K(+)-ATPase from gastric microsomes using anti-H(+)-K(+)-ATPase antibodies suggests that ankyrin associates with the H(+)-K(+)-ATPase. Indirect immunofluorescence and confocal microscopy show that ankyrin and H(+)-K(+)-ATPase cosegregate within resting and secreting parietal cells. Taken together, these data suggest that the association of the gastric H(+)-K(+)-ATPase with spectrin and actin is mediated by ankyrin and that this interaction contributes to the maintenance of the polarized distribution of the enzyme to the apical domain of gastric parietal cells during acid secretion.

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Carbachol activates ERK2 in isolated gastric parietal cells via multiple signaling pathways

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1999.276.6.g1484 ◽

1999 ◽

Vol 276 (6) ◽

pp. G1484-G1492 ◽

Cited By ~ 8

Author(s):

Yoshiaki Takeuchi ◽

Nonthalee Pausawasdi ◽

Andrea Todisco

Keyword(s):

Molecular Mechanisms ◽

Parietal Cells ◽

Dominant Negative ◽

Guanine Nucleotide ◽

Nucleotide Exchange ◽

Guanine Nucleotide Exchange ◽

Ras Activation ◽

Gastric Parietal Cells ◽

Tyrosyl Phosphorylation

We previously reported that both carbachol and epidermal growth factor (EGF) are potent inducers of the extracellular signal-regulated protein kinases (ERKs) in isolated gastric canine parietal cells and that induction of these kinases leads to acute inhibitory and chronic stimulatory effects on gastric acid secretion. In this study we investigated the molecular mechanisms responsible for these effects. Both carbachol (100 μM) and EGF (10 nM) induced Ras activation. The role of Ras in ERK2 induction was examined by transfecting parietal cells with a vector expressing hemoagglutinin (HA)-tagged ERK2 (HA-ERK2) together with a dominantly expressed mutant (inactive) ras gene. HA-ERK2 activity was quantitated by in-gel kinase assays. Dominant negative Ras reduced carbachol induction of HA-ERK2 activity by 60% and completely inhibited the stimulatory effect of EGF. Since Ras activation requires the assembly of a multiprotein complex, we examined the effect of carbachol and EGF on tyrosyl phosphorylation of Shc and its association with Grb2 and the guanine nucleotide exchange factor Sos. Western blot analysis of anti-Shc immunoprecipitates with an anti-phosphotyrosine antibody demonstrated that both carbachol and EGF induced tyrosyl phosphorylation of a major 52-kDa shc isoform. Grb2 association with Shc was demonstrated by blotting Grb2 immunoprecipitates with an anti-Shc antibody. Probing of anti-Sos immunoprecipitates with an anti-Grb2 antibody revealed that Sos was constitutively bound to Grb2. To examine the functional role of Sos in ERK2 activation, we transfected parietal cells with the HA-ERK2 vector together with a dominantly expressed mutant (inactive) sos gene. Dominant negative Sos did not affect carbachol stimulation of HA-ERK2 but inhibited the stimulatory effect of EGF by 60%. We then investigated the role of βγ-subunits in carbachol induction of HA-ERK2. Parietal cells were transfected with the HA-ERK2 vector together with a vector expressing the carboxy terminus of the β-adrenergic receptor kinase 1, known to block signaling mediated by βγ-subunits. In the presence of this vector, carbachol induction of HA-ERK2 was inhibited by 40%. Together these data suggest that, in the gastric parietal cells, carbachol activates the ERKs through Ras- and βγ-dependent mechanisms that require guanine nucleotide exchange factors other than Sos.

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