Functional characterization of Cl-/HCO3- exchange in villous cells of the mouse ileum

Uchiyama, Hisakazu; Hayashi, Hideharu; Suzuki, Yuichi

doi:10.2220/biomedres.27.265

Cited by 7 publications

(6 citation statements)

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“…The inhibition of Cl − -dependent HCO 3 − secretion by a carbonic anhydrase inhibitor has been previously reported in the jejunum (22). HCO 3 − secretion through the Cl − -independent pathway and that through the cAMP-activated pathway exhibited different inhibitor-sensitivity profiles, although both occurred in the absence of mucosal (11,18,20,25,26,29,30,32,33). The present result showing that mucosal SO 4 2− could activate HCO 3 − secretion (Fig.…”

Section: Discussionsupporting

confidence: 77%

pH stat studies on bicarbonate secretion in the isolated mouse ileum

et al. 2007

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Bicarbonate secretion occurs in almost all segments of the gastrointestinal tract. This study examined HCO 3 − secretion in the ileum, since it is less understood than HCO 3 − secretion in other intestinal segments. Mouse ileal mucosa was mounted in vitro in Ussing chambers, and the mucosal alkalinization rate (J OH ) was determined by pH stat titration, while the mucosal side was bathed with a buffer-free solution (100% O 2 ) and the serosal side with a HCO 3 − /CO 2 -buffered solution. The transmural potential difference (PD) was recorded. The mucosal alkalinization rate (J OH ) was higher in the presence of mucosal Cl − than in its absence. Forskolin, an activator of adenylate cyclase, enhanced J OH and PD in both the presence and absence of mucosal Cl − . Mucosal SO 4 2− also caused an increase in J OH , although the magnitude was smaller than that induced by Cl − . Mucosal Cl − -dependent J OH was partially inhibited by acetazolamide, 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB), tenidap and probably also by niflumic acid, but not by glibenclamide, DIDS or bumetanide. The forskolin-induced J OH value and PD were both inhibited by NPPB and probably also by tenidap. It is concluded that HCO 3 − secretion in the ileum follows a mucosal Cl −

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Section: Discussionsupporting

confidence: 77%

pH stat studies on bicarbonate secretion in the isolated mouse ileum

et al. 2007

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“…Tenidap may inhibit HCO 3 Ϫ efflux by inhibiting NBCe1, suggesting the importance of NBCe1 for acinar cell HCO 3 Ϫ secretion. The major mechanism for Cl Ϫ efflux is basolateral AE2, which is partially tenidap sensitive (40,42,48,51,70,87). Thus tenidap may inhibit I sc by blocking NBCe1 and partially inhibiting AE2.…”

Section: a And B Top And Bottom)mentioning

confidence: 99%

PKCαβγ- and PKCδ-dependent endocytosis of NBCe1-A and NBCe1-B in salivary parotid acinar cells

Perry¹,

Baker

Reyland

et al. 2009

American Journal of Physiology-Cell Physiology

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We examined membrane trafficking of NBCe1-A and NBCe1-B variants of the electrogenic Na(+)-HCO(3)(-) cotransporter (NBCe1) encoded by the SLC4A4 gene, using confocal fluorescent microscopy in rat parotid acinar cells (ParC5 and ParC10). We showed that yellow fluorescent protein (YFP)-tagged NBCe1-A and green fluorescent protein (GFP)-tagged NBCe1-B are colocalized with E-cadherin in the basolateral membrane (BLM) but not with the apical membrane marker zona occludens 1 (ZO-1). We inhibited constitutive recycling with monensin and W13 and detected that NBCe1-A and NBCe1-B accumulated in vesicles marked with the early endosomal marker early endosome antigen-1 (EEA1), with a parallel loss from the BLM. We observed that NBCe1-A and NBCe1-B undergo massive carbachol (CCh)-stimulated redistribution from the BLM into early endosomes. We showed that internalization of NBCe1-A and NBCe1-B was prevented by the general PKC inhibitor GF-109203X, the PKCalphabetagamma-specific inhibitor Gö-6976, and the PKCdelta-specific inhibitor rottlerin. We verified the involvement of PKCdelta by blocking CCh-induced internalization of NBCe1-A-cyan fluorescent protein (CFP) in cells transfected with dominant-negative kinase-dead (Lys376Arg) PKCdelta-GFP. Our data suggest that NBCe1-A and NBCe1-B undergo constitutive and CCh-stimulated endocytosis regulated by conventional PKCs (PKCalphabetagamma) and by novel PKCdelta in rat epithelial cells. To help develop a more complete model of the role of NBCe1 in parotid acinar cells we also investigated the initial phase of the secretory response to cholinergic agonist. In an Ussing chamber study we showed that inhibition of basolateral NBCe1 with 5-chloro-2,3-dihydro-3-(hydroxy-2-thienylmethylene)-2-oxo-1H-indole-1-carboxamide (tenidap) significantly decreases an initial phase of luminal anion secretion measured as a transient short-circuit current (I(sc)) across ParC10 cell monolayers. Using trafficking and functional data we propose a model that describes a physiological role of NBC in salivary acinar cell secretion.

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“…In equilibrium with CO 2 , H 2 CO 2 and CO 3 2- , depending on pH, temperature, and CO 2 pressure, bicarbonate does not diffuse freely across the membrane and needs specific transporters [12]. In the stomach, HCO 3 - is secreted by the surface mucus cells, where it gets trapped in the mucus and forms part of the mucus-HCO 3 - barrier, thereby maintaining a pH gradient of pH 2 in the lumen to pH 7 at the mucosal epithelium interface.…”

Section: Introductionmentioning

confidence: 99%

Bicarbonate enhances expression of the endocarditis and biofilm associated pilus locus, ebpR-ebpABC, in Enterococcus faecalis

Bourgogne¹,

Thomson²,

Murray

2010

BMC Microbiol

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BackgroundWe previously identified ebpR, encoding a potential member of the AtxA/Mga transcriptional regulator family, and showed that it is important for transcriptional activation of the Enterococcus faecalis endocarditis and biofilm associated pilus operon, ebpABC. Although ebpR is not absolutely essential for ebpABC expression (100-fold reduction), its deletion led to phenotypes similar to those of an ebpABC mutant such as absence of pili at the cell surface and, consequently, reduced biofilm formation. A non-piliated ebpABC mutant has been shown to be attenuated in a rat model of endocarditis and in a murine urinary tract infection model, indicating an important participation of the ebpR-ebpABC locus in virulence. However, there is no report relating to the environmental conditions that affect expression of the ebpR-ebpABC locus.ResultsIn this study, we examined the effect of CO2/HCO3-, pH, and the Fsr system on the ebpR-ebpABC locus expression. The presence of 5% CO2/0.1 M HCO3- increased ebpR-ebpABC expression, while the Fsr system was confirmed to be a weak repressor of this locus. The mechanism by which the Fsr system repressed the ebpR-ebpABC locus expression appears independent of the effects of CO2- bicarbonate. Furthermore, by using an ebpA::lacZ fusion as a reporter, we showed that addition of 0.1 M sodium bicarbonate to TSBG (buffered at pH 7.5), but not the presence of 5% CO2, induced ebpA expression in TSBG broth. In addition, using microarray analysis, we found 73 genes affected by the presence of sodium bicarbonate (abs(fold) > 2, P < 0.05), the majority of which belong to the PTS system and ABC transporter families. Finally, pilus production correlated with ebpA mRNA levels under the conditions tested.ConclusionsThis study reports that the ebp locus expression is enhanced by the presence of bicarbonate with a consequential increase in the number of cells producing pili. Although the molecular basis of the bicarbonate effect remains unclear, the pathway is independent of the Fsr system. In conclusion, E. faecalis joins the growing family of pathogens that regulates virulence gene expression in response to bicarbonate and/or CO2.

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Functional characterization of Cl-/HCO3- exchange in villous cells of the mouse ileum

Abstract: At least three kinds of Cl − /HCO 3 − exchangers, SLC26A3, SLC26A6 and AE2, have been demonstrated to be expressed in the intestinal epithelial cell. To examine the functional expression of these exchangers in the native enterocyte, we studied the Cl

Cited by 7 publications

References 36 publications

pH stat studies on bicarbonate secretion in the isolated mouse ileum

pH stat studies on bicarbonate secretion in the isolated mouse ileum

PKCαβγ- and PKCδ-dependent endocytosis of NBCe1-A and NBCe1-B in salivary parotid acinar cells

Bicarbonate enhances expression of the endocarditis and biofilm associated pilus locus, ebpR-ebpABC, in Enterococcus faecalis

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