Colocalization of the apical Cl−/HCO 3 − exchanger PAT1 and gastric H-K-ATPase in stomach parietal cells

2002 ◽  
Vol 283 (5) ◽  
pp. G1207-G1216 ◽  
Author(s):  
Snezana Petrovic ◽  
Zhaohui Wang ◽  
Liyun Ma ◽  
Ursula Seidler ◽  
John G. Forte ◽  
...  
Keyword(s):  
Resting State ◽  
Parietal Cells ◽  
Immunocytochemical Staining ◽  
Cell Distribution ◽  
Sharp Reduction ◽  
Anion Transporter ◽  
Membrane Location ◽  
Immunofluorescence Labeling ◽  
Apical Membranes ◽  
Gastric Parietal Cells

The apical Cl−/HCO[Formula: see text] exchanger called the putative anion transporter (PAT1; SLC26A6) is expressed on apical membranes of villus cells in the duodenum, but its location in the stomach remains unknown. Here we examined the cell distribution and membrane location of PAT1 in mouse stomach. Immunofluorescence labeling studies with anti-PAT1 antibodies and Dolichos biflorusagglutinin indicated the exclusive expression of PAT1 in gastric parietal cells. Double immunocytochemical staining revealed colocalization of PAT1 with the gastric H-K-ATPase, consistent with expression in tubulovesicles and/or the secretory canaliculus. Radiolabeled 36Cl flux studies demonstrated the functional presence of Cl−/HCO[Formula: see text] exchange in purified tubulovesicles of parietal cells. The expression of PAT1 was significantly decreased in parietal cells of gastric H-K-ATPase-null mice, which exhibit a sharp reduction in tubulovesicle membranes. These data indicate that the Cl−/HCO[Formula: see text]exchanger PAT1 is localized on tubulovesicular membranes, and they are consistent with the hypothesis that it functions in the maintenance of intravesicular ion concentrations in the resting state and dehydration of vesicles derived from the secretory membranes following the transition from the stimulated to the resting state.

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.

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.

Intracellular Ca2+ shift and signal transduction from the tubulovesicular portion of gastric parietal cells during gastrin stimulation or Ca2+ ionophore treatment: comparison between luminescent and fluorescent probes, and electron probe X-ray microanalyzer

1988 ◽  
Vol 66 (4) ◽  
pp. 279-287 ◽  
Author(s):  
Yasuhiro Tsunoda ◽  
Hiroshi Takeda ◽  
Toshihiro Otaki ◽  
Masahiro Asaka ◽  
Ikuko Nakagaki ◽  
...  
Keyword(s):  
Resting State ◽  
Electron Probe ◽  
Physiological Saline ◽  
Parietal Cells ◽  
X Ray ◽  
Fura 2 ◽  
Treatment Comparison ◽  
Apical Cytoplasm ◽  
Intracellular Ca ◽  
Gastric Parietal Cells

In gastrin-stimulated, aequorin-loaded parietal cells from guinea pig gastric mucosa, a rapid but transient increase in the cytosolic free Ca2+ concentration ([Ca2+]i), owing to Ca2+ released from the store(s), and a more prolonged Ca2+ entry from outside the cells were observed. However, there was a little increase in [Ca2+]i when similar measurements were assessed by quin 2 or fura-2 in physiological saline. However, depletion or elimination of Na+ from the incubation medium caused a significant increase in the [Ca2+]; response to gastrin as measured by quin 2. These findings suggest that aequorin and quin 2 (or fura-2) provide information about different aspects of Ca2+ homeostasis and that there is an inhomogeneity of [Ca2+]i in the cytoplasm during gastrin stimulation. By the gastrin stimulation, the intracellular Ca2+ gradients were shifted from the unidentified portion(s) to the restricted apical cytoplasm, as determined by electron probe X-ray microanalysis. Therefore, localization and identification of the source of intracellular Ca2+ as a pool were determined by an X-ray microanalyzer. In the resting state, the tubulovesicle had high Ca2+ concentration compared with the level in the apical cytoplasm. Cells treated with the Ca2+ ionophore ionomycin had a decreased tubulovesicular Ca2+ level, followed by a reciprocal increase in area of the canalicular membrane. The secretory canaliculus in stimulated cells had lower Ca2+ or higher K+ and Cl− concentrations than that of tubulovesicles or cytoplasm in the resting state, respectively. These findings suggest that the Ca2+ pool of the parietal cell is in the tubulovesicles and (or) luminal cell membrane and that the Ca2+ released from the store(s) may mediate a flow of K+ or Cl− into the secretory canaliculus.

scholarly journals Deletion of the chloride transporter Slc26a9 causes loss of tubulovesicles in parietal cells and impairs acid secretion in the stomach

2008 ◽  
Vol 105 (46) ◽  
pp. 17955-17960 ◽  
Author(s):  
Jie Xu ◽  
Penghong Song ◽  
Marian L. Miller ◽  
Frank Borgese ◽  
Sharon Barone ◽  
...  
Keyword(s):  
Acid Secretion ◽  
Gastric Acid Secretion ◽  
Gastric Acid ◽  
Cultured Cells ◽  
Normal Growth ◽  
Chloride Secretion ◽  
Parietal Cells ◽  
Gastric Glands ◽  
Anion Transporter ◽  
Immunofluorescence Labeling

Slc26a9 is a recently identified anion transporter that is abundantly expressed in gastric epithelial cells. To study its role in stomach physiology, gene targeting was used to prepare mice lacking Slc26a9. Homozygous mutant (Slc26a9−/−) mice appeared healthy and displayed normal growth. Slc26a9 deletion resulted in the loss of gastric acid secretion and a moderate reduction in the number of parietal cells in mutant mice at 5 weeks of age. Immunofluorescence labeling detected the H-K-ATPase exclusively on the apical pole of gastric parietal cells in Slc26a9−/− mice, in contrast to the predominant cytoplasmic localization in Slc26a9+/+ mice. Light microscopy indicated that gastric glands were dilated, and electron micrographs displayed a distinct and striking absence of tubulovesicles in parietal cells and reductions in the numbers of parietal and zymogen cells in Slc26a9−/− stomach. Expression studies indicated that Slc26a9 can function as a chloride conductive pathway in oocytes as well as a Cl−/HCO3− exchanger in cultured cells, and localization studies in parietal cells detected its presence in tubulovesicles. We propose that Slc26a9 plays an essential role in gastric acid secretion via effects on the viability of tubulovesicles/secretory canaliculi and by regulating chloride secretion in parietal cells.

scholarly journals Heterogenous distribution of free calcium and propagation of calcium transient in gastric parietal cells revealed by digital imaging microscopy.

1989 ◽  
Vol 37 (7) ◽  
pp. 999-1005 ◽  
Author(s):  
Y Tsunoda ◽  
S Yodozawa ◽  
Y Tashiro
Keyword(s):  
Digital Imaging ◽  
Resting State ◽  
Calcium Concentration ◽  
Gastric Gland ◽  
Calcium Transient ◽  
Parietal Cells ◽  
Free Calcium ◽  
Marked Contrast ◽  
Free Calcium Concentration ◽  
Gastric Parietal Cells

Spatial and temporal changes of cytoplasmic free calcium concentration ([Ca2+]i) in single parietal cells of guinea pig were investigated with a digital imaging microscope equipped with a microspectrofluorometer, using a Ca2+-sensitive dye, fura-2. Intracellular distribution of [Ca2+]i was not homogeneous, but there were two kinds of [Ca2+]i gradient in the resting parietal cells, one a continuous gradient increasing towards the plasma membrane and a second discontinuous gradient (Ca2+ plateau) in some restricted regions of the cytoplasm. When treated with gastrin, only about 40% of parietal cells in the gastric gland responded with an almost twofold increase in the average resting [Ca2+]i of 52.4 +/- 7.1 nM. In the responding cells, the discontinuous plateaus transiently enlarged to the entire cytoplasm. In marked contrast, all of these cells responded to Ca2+ ionophore ionomycin. We also found that when provoked by gastrin Ca2+ transient in the parietal cells in the gastric gland often propagated to some adjacent cells, and occasionally spontaneous Ca2+ transient and oscillation were observed even in the resting state.

La3+ and pH sensitivity of Ca2+ entry and intracellular store filling in gastric parietal cells

1995 ◽  
Vol 269 (5) ◽  
pp. G770-G778 ◽  
Author(s):  
P. A. Negulescu ◽  
T. E. Machen
Keyword(s):  
Positive Feedback ◽  
Low Ph ◽  
Parietal Cells ◽  
Additional Increase ◽  
Cholinergic Agonist ◽  
Intracellular Store ◽  
Entry Pathway ◽  
Signaling Function ◽  
Previously Treated ◽  
Gastric Parietal Cells

The fluorescent Ca2+ indicator fura 2 was used to measure cytosolic free [Ca2+] ([Ca2+]i) in order to obtain information about relative rates of Ca2+ influx into parietal cells during treatment with carbachol (a cholinergic agonist) or thapsigargin (TG, a Ca(2+)-mobilizing agent) or during reloading of the internal Ca2+ stores. In Ca(2+)-containing solutions, carbachol-, TG-, and reloading-stimulated Ca2+ entry exhibited nearly identical sensitivity to La3+ [inhibition constant (Ki) approximately 10 microM] or low pH (pKi approximately 7.0). In experiments in which carbachol and TG were used, there was no additional increase in [Ca2+]i when TG was added to carbachol-treated cells or when carbachol was added to cells previously treated with TG. Thus it is likely that a single Ca2+ entry pathway serves a signaling function as well as a role in refilling the Ca2+ store during reloading. Because the Ca2+ pathway is exquisitely sensitive to pH and serosal pH increases during stimulant-induced H+ secretion (which is activated by increases in [Ca2+]i), this mechanism will exert positive feedback on parietal cells in the intact stomach. When parietal cells were pretreated with carbachol in Ca(2+)-free solutions, reloading was independent of pH and La3+, suggesting that Ca(2+)-containing solutions should be used to determine the properties of the influx pathway.

scholarly journals Receptor-operated Ca2+ channels in gastric parietal cells: gastrin and carbachol induce Ca2+ influx in depleting intracellular Ca2+ stores

1993 ◽  
Vol 289 (1) ◽  
pp. 117-124 ◽  
Author(s):  
S Roche ◽  
J P Bali ◽  
R Magous
Keyword(s):  
Steady State ◽  
Receptor Activation ◽  
Parietal Cells ◽  
The Other ◽  
Bivalent Cation ◽  
Gtp Binding ◽  
Gastric Parietal Cells ◽  
Type Receptor ◽  
Ca2 Channels ◽  
Stimulation Of

The mechanism whereby gastrin-type receptor and muscarinic M3-type receptor regulate free intracellular Ca2+ concentration ([Ca2+]i) was studied in rabbit gastric parietal cells stimulated by either gastrin or carbachol. Both agonists induced a biphasic [Ca2+]i response: a transient [Ca2+]i rise, followed by a sustained steady state depending on extracellular Ca2+. Gastrin and carbachol also caused a rapid and transient increase in Mn2+ influx (a tracer for bivalent-cation entry). Pre-stimulation of cells with one agonist drastically decreased both [Ca2+]i increase and Mn2+ influx induced by the other. Neither diltiazem nor pertussistoxin treatment had any effect on agonist-stimulated Mn2+ entry. Thapsigargin, a Ca(2+)-pump inhibitor, induced a biphasic [Ca2+]i increase, and enhanced the rate of Mn2+ entry. Preincubation of cells with thapsigargin inhibits the [Ca2+]i increase as well as Mn2+ entry stimulated by gastrin or by carbachol. Thapsigargin induced a weak but significant increase in Ins(1,4,5)P3 content, but this agent had no effect on the agonist-evoked Ins(1,4,5)P3 response. In permeabilized parietal cells, Ins(1,4,5)P3 and caffeine caused an immediate Ca2+ release from intracellular pools, followed by a reloading of Ca2+ pools which can be prevented in the presence of thapsigargin. We conclude that (i) gastrin and carbachol mobilize common Ca2+ intracellular stores, (ii) Ca2+ permeability secondary to receptor activation involves neither a voltage-sensitive Ca2+ channel nor a GTP-binding protein from the G1 family, and (iii) agonists regulate common Ca2+ channels in depleting intracellular Ca2+ stores.

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