Short-Term Regulation of Murine Colonic NBCe1-B (Electrogenic Na+/HCO3− Cotransporter) Membrane Expression and Activity by Protein Kinase C

The colonic mucosa actively secretes HCO.sub.3 .sup.-, and several lines of evidence point to an important role of Na.sup.+ /HCO.sub.3 .sup.- cotransport (NBC) as a basolateral HCO.sub.3 .sup.- import pathway. We could recently demonstrate that the predominant NBC isoform in murine colonic crypts is...

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Bibliographic Details
Published in:PloS one 2014-03, Vol.9 (3), p.e92275
Main Authors: May, Oliver, Yu, Haoyang, Riederer, Brigitte, Manns, Michael P, Seidler, Ursula, Bachmann, Oliver
Format: Article
Language:English
Subjects:
Abundance
Activation
Biology and life sciences
Biotinylation
Carbachol
Cell surface
Colon
Crypts
Endocrinology
Exocytosis
Experiments
Forskolin
Gastroenterology
Hepatology
Ion transport
Kinases
Medical schools
Medicine and Health Sciences
Mucosa
Phosphorylation
Protein kinase C
Protein kinases
Proteins
Proton flux
Research and Analysis Methods
Rodents
Signal transduction
Stimulation
Translocation
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Summary:The colonic mucosa actively secretes HCO.sub.3 .sup.-, and several lines of evidence point to an important role of Na.sup.+ /HCO.sub.3 .sup.- cotransport (NBC) as a basolateral HCO.sub.3 .sup.- import pathway. We could recently demonstrate that the predominant NBC isoform in murine colonic crypts is electrogenic NBCe1-B, and that secretagogues cause NBCe1 exocytosis, which likely represents a component of NBC activation. Since protein kinase C (PKC) plays a key role in the regulation of ion transport by trafficking events, we asked whether it is also involved in the observed NBC activity increase. Crypts were isolated from murine proximal colon to assess PKC activation as well as NBC function and membrane abundance using fluorometric pH.sub.i measurements and cell surface biotinylation, respectively. PKC isoform translocation and phosphorylation occurred in response to PMA-, as well as secretagogue stimulation. The conventional and novel PKC inhibitors Gö6976 or Gö6850 did not alter NBC function or surface expression by themselves, but stimulation with forskolin (10.sup.-5 M) or carbachol (10.sup.-4 M) in their presence led to a significant decrease in NBC-mediated proton flux, and biotinylated NBCe1. Our data thus indicate that secretagogues lead to PKC translocation and phosphorylation in murine colonic crypts, and that PKC is necessary for the increase in NBC transport rate and membrane abundance caused by cholinergic and cAMP-dependent stimuli.
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0092275