scholarly journals Achlorhydria by ezrin knockdown

2005 ◽  
Vol 169 (1) ◽  
pp. 21-28 ◽  
Author(s):  
Atsushi Tamura ◽  
Shojiro Kikuchi ◽  
Masaki Hata ◽  
Tatsuya Katsuno ◽  
Takeshi Matsui ◽  
...  
Keyword(s):  
Acid Secretion ◽  
Gastric Acid Secretion ◽  
Gastric Acid ◽  
Parietal Cells ◽  
Protein Levels ◽  
Acid Secreting ◽  
Apical Membranes ◽  
Gastric Parietal Cells ◽  
Neomycin Resistance

Loss of gastric acid secretion is pathologically known as achlorhydria. Acid-secreting parietal cells are characterized by abundant expression of ezrin (Vil2), one of ezrin/radixin/moesin proteins, which generally cross-link actin filaments with plasma membrane proteins. Here, we show the direct in vivo involvement of ezrin in gastric acid secretion. Ezrin knockout (Vil2−/−) mice did not survive >1.5 wk after birth, making difficult to examine gastric acid secretion. We then generated ezrin knockdown (Vil2kd/kd) mice by introducing a neomycin resistance cassette between exons 2 and 3. Vil2kd/kd mice born at the expected Mendelian ratio exhibited growth retardation and a high mortality. Approximately 7% of Vil2kd/kd mice survived to adulthood. Ezrin protein levels in Vil2kd/kd stomachs decreased to <5% of the wild-type levels without compensatory up-regulation of radixin or moesin. Adult Vil2kd/kd mice suffered from severe achlorhydria. Immunofluorescence and electron microscopy revealed that this achlorhydria was caused by defects in the formation/expansion of canalicular apical membranes in gastric parietal cells.

scholarly journals Metabolism and gastric acid secretion. Substrate-dependency of aminopyrine accumulation in isolated rat parietal cells

1985 ◽  
Vol 227 (1) ◽  
pp. 223-229 ◽  
Author(s):  
G P Shaw ◽  
N G Anderson ◽  
P J Hanson
Keyword(s):  
Acid Secretion ◽  
Gastric Acid Secretion ◽  
Gastric Acid ◽  
Parietal Cell ◽  
Parietal Cells ◽  
Intestinal Epithelial ◽  
Acid Secreting ◽  
High Concentrations ◽  
Isolated Rat

The substrate-dependency of gastric acid secretion was investigated in isolated rat parietal cells by using the accumulation of the weak base aminopyrine as an index of acid secretion. Exogenous substrates enhanced accumulation of aminopyrine in rat parietal cells stimulated by secretagogues, and this effect was probably directly related to the provision of energy for acid secretion. At physiological concentrations, certain of the substrates (glucose, oleate, lactate, D-3-hydroxybutyrate, L-isoleucine, L-valine and acetoacetate) could support acid secretion, with glucose being the most effective. L-Leucine and acetate were only effective stimulators of parietal-cell aminopyrine accumulation at high concentrations (5mM). L-Glutamine was unable to stimulate aminopyrine accumulation even at high concentrations, and glutaminase activity in parietal cells was estimated to be low by comparison with small-intestinal epithelial cells. Variation in the concentrations of D-3-hydroxybutyrate and L-isoleucine, but not of glucose, within the physiological range affected their ability to support aminopyrine accumulation. The presence of 5 mM-L-isoleucine, 5 mM-lactate and combinations of certain substrates at physiological concentrations produced aminopyrine accumulation in stimulated parietal cells that was greater than that obtained in cells incubated with 5 mM-glucose alone. In conclusion, fulfillment of the metabolic requirements of the acid-secreting parietal cell under physiological circumstances requires a combination of substrates, and integration of the results with previous data [Anderson & Hanson (1983) Biochem. J. 210, 451-455; 212, 875-879] suggests that after overnight starvation in vivo metabolism of glucose, D-3-hydroxybutyrate and L-isoleucine may be of particular importance.

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.

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.

Independent trafficking of the KCNQ1 K+ channel and H+-K+-ATPase in gastric parietal cells from mice

2013 ◽  
Vol 304 (2) ◽  
pp. G157-G166 ◽  
Author(s):  
Nhung Nguyen ◽  
Noga Kozer-Gorevich ◽  
Briony L. Gliddon ◽  
Adam J. Smolka ◽  
Andrew H. Clayton ◽  
...  
Keyword(s):  
Acid Secretion ◽  
Gastric Acid Secretion ◽  
Gastric Acid ◽  
Three Dimensional ◽  
Resonance Energy ◽  
Parietal Cells ◽  
K Channel ◽  
Apical Surface ◽  
Intracytoplasmic Membrane

Gastric acid secretion by the H+-K+-ATPase at the apical surface of activated parietal cells requires luminal K+ provided by the KCNQ1/KCNE2 K+ channel. However, little is known about the trafficking and relative spatial distribution of KCNQ1 and H+-K+-ATPase in resting and activated parietal cells and the capacity of KCNQ1 to control acid secretion. Here we show that inhibition of KCNQ1 activity quickly curtails gastric acid secretion in vivo, even when the H+-K+-ATPase is permanently anchored in the apical membrane, demonstrating a key role of the K+ channel in controlling acid secretion. Three-dimensional imaging analysis of isolated mouse gastric units revealed that the majority of KCNQ1 resides in an intracytoplasmic, Rab11-positive compartment in resting parietal cells, distinct from H+-K+-ATPase-enriched tubulovesicles. Upon activation, there was a significant redistribution of H+-K+-ATPase and KCNQ1 from intracytoplasmic compartments to the apical secretory canaliculi. Significantly, high Förster resonance energy transfer was detected between H+-K+-ATPase and KCNQ1 in activated, but not resting, parietal cells. These findings demonstrate that H+-K+-ATPase and KCNQ1 reside in independent intracytoplasmic membrane compartments, or membrane domains, and upon activation of parietal cells, both membrane proteins are transported, possibly via Rab11-positive recycling endosomes, to apical membranes, where the two molecules are closely physically opposed. In addition, these studies indicate that acid secretion is regulated by independent trafficking of KCNQ1 and H+-K+-ATPase.

Regulation and function of p38 protein kinase in isolated canine gastric parietal cells

2000 ◽  
Vol 278 (1) ◽  
pp. G24-G31 ◽  
Author(s):  
N. Pausawasdi ◽  
S. Ramamoorthy ◽  
V. Stepan ◽  
J. del Valle ◽  
A. Todisco
Keyword(s):  
Acid Secretion ◽  
Gastric Acid Secretion ◽  
Gastric Acid ◽  
Kinase Activity ◽  
Parietal Cells ◽  
Kinase Assay ◽  
P38 Kinase ◽  
Gastric Parietal Cells ◽  
Sb 203580

We examined the regulation and functional role of p38 kinase in gastric acid secretion. p38 kinase was immunoprecipitated from cell lysates of highly purified gastric parietal cells in primary culture, and its activity was quantitated by in vitro kinase assay. Carbachol effects were dose- and time-dependent, with a maximal 10-fold stimulatory effect detected after 30 min of incubation. SB-203580, a highly selective inhibitor of p38 kinase, blocked carbachol induction of p38 kinase activity, with maximal inhibition at 10 μM. Stimulation by carbachol was unaffected by preincubation of parietal cells with the intracellular Ca2+chelator BAPTA-AM, but incubation of cells in Ca2+-free medium led to a 50% inhibition of carbachol induction of p38 kinase activity. Because some of the effects of carbachol are mediated by the small GTP-binding protein Rho, we examined the role of Rho in carbachol induction of p38 kinase activity. We tested the effect of exoenzyme C3 from Clostridium botulinum (C3), a toxin known to ADP-ribosylate and specifically inactivate Rho. C3 led to complete ADP-ribosylation of Rho, and it inhibited carbachol induction of p38 kinase by 50%. We then tested the effect of SB-203580 and C3 on carbachol-stimulated uptake of [14C]aminopyrine (AP). Inhibition of p38 kinase by SB-203580 led to a dose-dependent increase in AP uptake induced by carbachol, with maximal (threefold) effect at 10 μM SB-203580. Similarly, preincubation of parietal cells with C3 led to a twofold increase in AP uptake induced by carbachol. Thus carbachol induces a cascade of events in parietal cells that results in activation of p38 kinase through signaling pathways that are at least in part dependent on Rho activation and on the presence of extracellular Ca2+. p38 kinase appears to inhibit gastric acid secretion.

scholarly journals CORRELATION OF THE FINE STRUCTURE OF THE GASTRIC PARIETAL CELL (DOG) WITH FUNCTIONAL ACTIVITY OF THE STOMACH

1961 ◽  
Vol 11 (2) ◽  
pp. 349-363 ◽  
Author(s):  
A. W. Sedar ◽  
M. H. F. Friedman
Keyword(s):  
Fine Structure ◽  
Acid Secretion ◽  
Gastric Acid Secretion ◽  
Gastric Acid ◽  
Parietal Cell ◽  
Parietal Cells ◽  
Gastric Glands ◽  
Secretory Cycle ◽  
Thin Sections ◽  
Acid Secreting

The fine structure of the parietal (oxyntic) cell in the gastric glands (corpus of the stomach) of the dog was examined under conditions of active gastric acid secretion and compared with cellular structure in the non-acid-secretory (basal) state. Animals, in both acute and chronic experiments, were equipped with gastric fistulae so that gastric juice could be collected for analysis of total acidity, free acidity, volume, and pH prior to biopsy of the gastric mucosa. The specimens of mucosa were fixed in buffered OsO4 and embedded in n-butyl methacrylate and the thin sections were stained with lead hydroxide before examination in the electron microscope. A majority of parietal cells showed an alteration of fine structure during stimulation of gastric acid secretion by a number of different techniques (electrical vagal stimulation, histamine administration, or insulin injection). The changes in fine structure affected mainly the smooth surfaced vesicular elements and the intracellular canaliculi in the cytoplasm of the cell. The mitochondria also appeared to be involved to some extent. During acid secretion a greater concentration of smooth surface profiles is found adjacent to the walls of the intracellular canaliculi; other parietal cells exhibited a marked decrease in number of smooth surfaced elements. Intracellular canaliculi, always present in non-acid-secreting oxyntic cells, develop more extensively in cells of acid-secreting gastric glands. The surface area of these canaliculi is greatly increased by the elaboration of a large number of closely approximated and elongated microvilli. Still other parietal cells apparently in a different stage of the secretory cycle exhibit non-patent canaliculi lacking prominence; such cells have very few smooth surfaced vesicular elements. These morphological findings correlated with the acid-secretory state of the stomach provide evidence that the parietal cell participates in the process of acid secretion.

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