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SLC26A9 is a constitutively active, CFTR-regulated anion conductance in human bronchial epithelia
Human bronchial epithelial (HBE) cells exhibit constitutive anion secretion that is absent in cells from cystic fibrosis (CF) patients. The identity of this conductance is unknown, but SLC26A9, a member of the SLC26 family of CF transmembrane conductance regulator (CFTR)-interacting transporters, is...
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Formato: | Texto |
Lenguaje: | English |
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The Rockefeller University Press
2009
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2664976/ https://www.ncbi.nlm.nih.gov/pubmed/19289574 http://dx.doi.org/10.1085/jgp.200810097 |
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author | Bertrand, Carol A. Zhang, Ruilin Pilewski, Joseph M. Frizzell, Raymond A. |
author_facet | Bertrand, Carol A. Zhang, Ruilin Pilewski, Joseph M. Frizzell, Raymond A. |
author_sort | Bertrand, Carol A. |
collection | PubMed |
description | Human bronchial epithelial (HBE) cells exhibit constitutive anion secretion that is absent in cells from cystic fibrosis (CF) patients. The identity of this conductance is unknown, but SLC26A9, a member of the SLC26 family of CF transmembrane conductance regulator (CFTR)-interacting transporters, is found in the human airway and exhibits chloride channel behavior. We sought differences in the properties of SLC26A9 and CFTR expressed in HEK 293 (HEK) cells as a fingerprint to identify HBE apical anion conductances. HEK cells expressing SLC26A9 displayed a constitutive chloride current that was inhibited by the CFTR blocker GlyH-101 (71 ± 4%, 50 µM) and exhibited a near-linear current–voltage (I-V) relation during block, while GlyH-101–inhibited wild-type (wt)CFTR exhibited a strong inward-rectified (IR) I-V relation. We tested polarized HBE cells endogenously expressing either wt or ΔF508-CFTR for similar activity. After electrical isolation of the apical membrane using basolateral α-toxin permeabilization, wtCFTR monolayers displayed constitutive chloride currents that were inhibited by GlyH-101 (68 ± 6%) while maintaining a near-linear I-V relation. In the absence of blocker, the addition of forskolin stimulated a current increase having a linear I-V; GlyH-101 blocked 69 ± 7% of the current and shifted the I-V relation IR, consistent with CFTR activation. HEK cells coexpressing SLC26A9 and wtCFTR displayed similar properties, as well as forskolin-stimulated currents that exceeded the sum of those in cells separately expressing SLC26A9 or wtCFTR, and an I-V relation during GlyH-101 inhibition that was moderately IR, indicating that SLC26A9 contributed to the stimulated current. HBE cells from CF patients expressed SLC26A9 mRNA, but no constitutive chloride currents. HEK cells coexpressing SLC26A9 with ΔF508-CFTR also failed to exhibit SLC26A9 current. We conclude that SLC26A9 functions as an anion conductance in the apical membranes of HBE cells, it contributes to transepithelial chloride currents under basal and cAMP/protein kinase A–stimulated conditions, and its activity in HBE cells requires functional CFTR. |
format | Text |
id | pubmed-2664976 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2009 |
publisher | The Rockefeller University Press |
record_format | MEDLINE/PubMed |
spelling | pubmed-26649762009-10-01 SLC26A9 is a constitutively active, CFTR-regulated anion conductance in human bronchial epithelia Bertrand, Carol A. Zhang, Ruilin Pilewski, Joseph M. Frizzell, Raymond A. J Gen Physiol Article Human bronchial epithelial (HBE) cells exhibit constitutive anion secretion that is absent in cells from cystic fibrosis (CF) patients. The identity of this conductance is unknown, but SLC26A9, a member of the SLC26 family of CF transmembrane conductance regulator (CFTR)-interacting transporters, is found in the human airway and exhibits chloride channel behavior. We sought differences in the properties of SLC26A9 and CFTR expressed in HEK 293 (HEK) cells as a fingerprint to identify HBE apical anion conductances. HEK cells expressing SLC26A9 displayed a constitutive chloride current that was inhibited by the CFTR blocker GlyH-101 (71 ± 4%, 50 µM) and exhibited a near-linear current–voltage (I-V) relation during block, while GlyH-101–inhibited wild-type (wt)CFTR exhibited a strong inward-rectified (IR) I-V relation. We tested polarized HBE cells endogenously expressing either wt or ΔF508-CFTR for similar activity. After electrical isolation of the apical membrane using basolateral α-toxin permeabilization, wtCFTR monolayers displayed constitutive chloride currents that were inhibited by GlyH-101 (68 ± 6%) while maintaining a near-linear I-V relation. In the absence of blocker, the addition of forskolin stimulated a current increase having a linear I-V; GlyH-101 blocked 69 ± 7% of the current and shifted the I-V relation IR, consistent with CFTR activation. HEK cells coexpressing SLC26A9 and wtCFTR displayed similar properties, as well as forskolin-stimulated currents that exceeded the sum of those in cells separately expressing SLC26A9 or wtCFTR, and an I-V relation during GlyH-101 inhibition that was moderately IR, indicating that SLC26A9 contributed to the stimulated current. HBE cells from CF patients expressed SLC26A9 mRNA, but no constitutive chloride currents. HEK cells coexpressing SLC26A9 with ΔF508-CFTR also failed to exhibit SLC26A9 current. We conclude that SLC26A9 functions as an anion conductance in the apical membranes of HBE cells, it contributes to transepithelial chloride currents under basal and cAMP/protein kinase A–stimulated conditions, and its activity in HBE cells requires functional CFTR. The Rockefeller University Press 2009-04 /pmc/articles/PMC2664976/ /pubmed/19289574 http://dx.doi.org/10.1085/jgp.200810097 Text en ©2009 Bertrand et al. This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.jgp.org/misc/terms.shtml). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/). |
spellingShingle | Article Bertrand, Carol A. Zhang, Ruilin Pilewski, Joseph M. Frizzell, Raymond A. SLC26A9 is a constitutively active, CFTR-regulated anion conductance in human bronchial epithelia |
title | SLC26A9 is a constitutively active, CFTR-regulated anion conductance in human bronchial epithelia |
title_full | SLC26A9 is a constitutively active, CFTR-regulated anion conductance in human bronchial epithelia |
title_fullStr | SLC26A9 is a constitutively active, CFTR-regulated anion conductance in human bronchial epithelia |
title_full_unstemmed | SLC26A9 is a constitutively active, CFTR-regulated anion conductance in human bronchial epithelia |
title_short | SLC26A9 is a constitutively active, CFTR-regulated anion conductance in human bronchial epithelia |
title_sort | slc26a9 is a constitutively active, cftr-regulated anion conductance in human bronchial epithelia |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2664976/ https://www.ncbi.nlm.nih.gov/pubmed/19289574 http://dx.doi.org/10.1085/jgp.200810097 |
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