scholarly journals Infection by Toxoplasma gondii, a severe parasite in neonates and AIDS patients, causes impaired anion secretion in airway epithelia

2015 ◽  
Vol 112 (14) ◽  
pp. 4435-4440 ◽  
Author(s):  
Hong-Mei Guo ◽  
Jiang-Mei Gao ◽  
Yu-Li Luo ◽  
Yan-Zi Wen ◽  
Yi-Lin Zhang ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Toxoplasma Gondii ◽  
Infected Mouse ◽  
Inflammatory Responses ◽  
Short Circuit ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
Airway Epithelia ◽  
Anion Secretion ◽  
Cystic Fibrosis Transmembrane

The airway epithelia initiate and modulate the inflammatory responses to various pathogens. The cystic fibrosis transmembrane conductance regulator-mediated Cl− secretion system plays a key role in mucociliary clearance of inhaled pathogens. We have explored the effects of Toxoplasma gondii, an opportunistic intracellular protozoan parasite, on Cl− secretion of the mouse tracheal epithelia. In this study, ATP-induced Cl− secretion indicated the presence of a biphasic short-circuit current (Isc) response, which was mediated by a Ca2+-activated Cl− channel (CaCC) and the cystic fibrosis transmembrane conductance regulator. However, the ATP-evoked Cl− secretion in T. gondii-infected mouse tracheal epithelia and the elevation of [Ca2+]i in T. gondii-infected human airway epithelial cells were suppressed. Quantitative reverse transcription–PCR revealed that the mRNA expression level of the P2Y2 receptor (P2Y2-R) increased significantly in T. gondii-infected mouse tracheal cells. This revealed the influence that pathological changes in P2Y2-R had on the downstream signal, suggesting that P2Y2-R was involved in the mechanism underlying T. gondii infection in airways. These results link T. gondii infection as well as other pathogen infections to Cl− secretion, via P2Y2-R, which may provide new insights for the treatment of pneumonia caused by pathogens including T. gondii.

cAMP- but not Ca(2+)-regulated Cl- conductance is lacking in cystic fibrosis mice epididymides and seminal vesicles

1996 ◽  
Vol 271 (1) ◽  
pp. C188-C193 ◽  
Author(s):  
A. Y. Leung ◽  
P. Y. Wong ◽  
J. R. Yankaskas ◽  
R. C. Boucher
Keyword(s):  
Cystic Fibrosis ◽  
Secretory Pathway ◽  
Short Circuit ◽  
Primary Cultures ◽  
Seminal Vesicles ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
Cl Secretion ◽  
Induced Changes ◽  
Cystic Fibrosis Transmembrane

Cystic fibrosis (CF) reflects the loss of adenosine 3',5'-cyclic monophosphate (cAMP)-regulated Cl- secretion consequent to mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. In humans, but not mice, with CF, the disease is associated with male infertility. The present study investigated the relative magnitudes of the cAMP pathways and an alternative Ca(2+)-regulated Cl- secretory pathway in primary cultures of the epididymides and the seminal vesicles of normal and CF mice. The basal equivalent short-circuit currents (Ieq) of cultures derived from the epididymides and the seminal vesicles from the CF mice were lower (6.0 +/- 0.6 and 4.0 +/- 1.0 muA/cm2, respectively) than those from normal mice (11.1 +/- 1.0 and 6.6 +/- 0.6 muA/cm2, respectively). Forskolin induced significant Ieq responses in both the epididymis (8.0 +/- 0.7 muA/cm2) and seminal vesicles (4.0 +/- 0.5 muA/cm2) from normal mice, whereas forskolin-induced changes in Ieq in CF mouse epididymis and seminal vesicles were absent, consistent with defective cAMP-CFTR-mediated Cl- secretion in CF mice. Ieq responses to agonists (ionomycin, ATP) that raise intracellular Ca2+ (Ca2+i) were larger than forskolin responses in normal animals (6.6 +/- 0.9 and 13.4 +/- 1.8 muA/cm2, respectively) and were preserved in CF (6.5 +/- 0.9 and 17.1 +/- 1.0 muA/cm2, respectively). We speculate that the fertility of male CF mice is maintained by persistent expression of the predominant alternative Ca(2+)-mediated Cl- transport system in the epididymides and seminal vesicles.

scholarly journals Huqi San-Evoked Rat Colonic Anion Secretion through Increasing CFTR Expression

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Xiaowei Xue ◽  
Zhengming Shi ◽  
Wen Wang ◽  
Xiaotong Yu ◽  
Ping Feng ◽  
...  
Keyword(s):  
Protein Content ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Distal Colon ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
Anion Secretion ◽  
Mrna Transcripts ◽  
And Function ◽  
Cystic Fibrosis Transmembrane

Huqi San (HQS) is a Chinese herbal preparation of eight medicinal herbs that promote diuresis, detoxification, blood circulation, and cholestasis. Defects in transporter expression and function can cause cholestasis and jaundice. However, the mechanism of the cholestasis underlying HQS effects, especially on the gastrointestinal tract ion secretion, has not been elucidated. Real-time RT-PCR and Western blotting were used to study the expression and localization of cystic fibrosis transmembrane conductance regulator (CFTR) andα-ENaC in rat alimentary tract, and then the effect of HQS on the ion transport in rat distal colon mucosa was investigated using the short-circuit current (ISC) technique. The results showed that pretreatment with HQS significantly enhanced mRNA transcripts and protein content of CFTR in liver and distal colon but notα-ENaC in alimentary organs. HQS increasesISCand decreases the transepithelial resistance. Pretreatment with epithelial Na+channel blocker did not affect theISCresponses elicited by HQS, but removal of extracellular Cl−or pretreatment with Cl−channel or Na+-K+-2Cl−cotransporter blocker inhibited HQS-elicitedISCresponses. These findings demonstrated that HQS, RA, and RP can stimulate Cl−secretion in the distal colon by increasing the mRNA transcripts and protein content of CFTR in liver and distal colon.

cAMP regulation of Cl− and HCO 3 − secretion across rat fetal distal lung epithelial cells

2002 ◽  
Vol 282 (4) ◽  
pp. L650-L658 ◽  
Author(s):  
Ahmed Lazrak ◽  
Ulrich Thome ◽  
Carpantanto Myles ◽  
Janice Ware ◽  
Lan Chen ◽  
...  
Keyword(s):  
Short Circuit ◽  
Lung Epithelial Cells ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
Anion Secretion ◽  
Ussing Chambers ◽  
Lung Epithelial ◽  
Cftr Protein ◽  
Distal Lung ◽  
Cystic Fibrosis Transmembrane

We isolated and cultured fetal distal lung epithelial (FDLE) cells from 17- to 19-day rat fetuses and assayed for anion secretion in Ussing chambers. With symmetrical Ringer solutions, basal short-circuit currents ( I sc) and transepithelial resistances were 7.9 ± 0.5 μA/cm2 and 1,018 ± 73 Ω · cm2, respectively (means ± SE; n = 12). Apical amiloride (10 μM) inhibited basal I sc by ∼50%. Subsequent addition of forskolin (10 μM) increased I sc from 3.9 ± 0.63 μA/cm2 to 7.51 ± 0.2 μA/cm2( n = 12). Basolateral bumetanide (100 μM) decreased forskolin-stimulated I sc from 7.51 ± 0.2 μA/cm2 to 5.62 ± 0.53, whereas basolateral 4,4′-dinitrostilbene-2,2′-disulfonate (5 mM), an inhibitor of HCO[Formula: see text] secretion, blocked the remaining I sc. Forskolin addition evoked currents of similar fractional magnitudes in symmetrical Cl−- or HCO[Formula: see text]-free solutions; however, no response was seen using HCO[Formula: see text]- and Cl−-free solutions. The forskolin-stimulated I sc was inhibited by glibenclamide but not apical DIDS. Glibenclamide also blocked forskolin-induced I sc across monolayers having nystatin-permeablized basolateral membranes. Immunolocalization studies were consistent with the expression of cystic fibrosis transmembrane conductance regulator (CFTR) protein in FDLE cells. In aggregate, these findings indicate the presence of cAMP-activated Cl− and HCO[Formula: see text] secretion across rat FDLE cells mediated via CFTR.

scholarly journals Rab11b Regulates the Apical Recycling of the Cystic Fibrosis Transmembrane Conductance Regulator in Polarized Intestinal Epithelial Cells

2009 ◽  
Vol 20 (8) ◽  
pp. 2337-2350 ◽  
Author(s):  
Mark R. Silvis ◽  
Carol A. Bertrand ◽  
Nadia Ameen ◽  
Franca Golin-Bisello ◽  
Michael B. Butterworth ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Epithelial Cells ◽  
Apical Membrane ◽  
Expression System ◽  
Anion Channel ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
T84 Cells ◽  
Anion Secretion ◽  
Cystic Fibrosis Transmembrane

The cystic fibrosis transmembrane conductance regulator (CFTR), a cAMP/PKA-activated anion channel, undergoes efficient apical recycling in polarized epithelia. The regulatory mechanisms underlying CFTR recycling are understood poorly, yet this process is required for proper channel copy number at the apical membrane, and it is defective in the common CFTR mutant, ΔF508. Herein, we investigated the function of Rab11 isoforms in regulating CFTR trafficking in T84 cells, a colonic epithelial line that expresses CFTR endogenously. Western blotting of immunoisolated Rab11a or Rab11b vesicles revealed localization of endogenous CFTR within both compartments. CFTR function assays performed on T84 cells expressing the Rab11a or Rab11b GDP-locked S25N mutants demonstrated that only the Rab11b mutant inhibited 80% of the cAMP-activated halide efflux and that only the constitutively active Rab11b-Q70L increased the rate constant for stimulated halide efflux. Similarly, RNAi knockdown of Rab11b, but not Rab11a, reduced by 50% the CFTR-mediated anion conductance response. In polarized T84 monolayers, adenoviral expression of Rab11b-S25N resulted in a 70% inhibition of forskolin-stimulated transepithelial anion secretion and a 50% decrease in apical membrane CFTR as assessed by cell surface biotinylation. Biotin protection assays revealed a robust inhibition of CFTR recycling in polarized T84 cells expressing Rab11b-S25N, demonstrating the selective requirement for the Rab11b isoform. This is the first report detailing apical CFTR recycling in a native expression system and to demonstrate that Rab11b regulates apical recycling in polarized epithelial cells.

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