Linked Life Data

19255496

Source:http://linkedlifedata.com/resource/pubmed/id/19255496

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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1-3
pubmed:dateCreated
2009-3-3
pubmed:abstractText
The expression of the epithelial Na+ channel (ENaC) is tissue-specific and dependent on a variety of mediators and interacting proteins. Here we examined the role of intracellular Na+ ([Na+](i)) as a modulator of the expression of rat ENaC in Xenopus laevis oocytes. We manipulated [Na+](i) of ENaC-expressing oocytes in the range of 0-20 mM by incubating in extracellular solutions of different [Na+](o). Electrophysiological, protein biochemical and fluorescence optical methods were used to determine the effects of different [Na+]i on ENaC expression and membrane abundance. In voltage-clamp experiments we found that amiloride-sensitive ENaC current (Iami) and conductance (Gami) peak at a [Na+](i) of approximately 10 mM Na+, but were significantly reduced in 5 mM and 20 mM [Na+](i). Fluorescence intensity of EGFP-ENaC-expressing oocytes also followed a bell-shaped curve with a maximum at approximately 10 mM [Na+](i). In Western blot experiments with specific anti-ENaC antibodies the highest protein expression was found in ENaC-expressing oocytes with [Na+](i) of 10-15 mM. Since ENaC is also highly permeable for Li+, we incubated ENaC-expressing oocytes in different Li+ concentrations and found a peak of Iami and Gami with 5 mM Li+. The influence of [Na+](i) on the expression is not ENaC-specific, since expression of a Cl(-) channel (CFTR) and a Na+/glucose cotransporter (SGLT1) showed the same dependence on [Na+](i). We conclude that specific concentrations of Na+ and Li+ influence the expression and abundance of ENaC and other transport proteins in the plasma membrane in Xenopus laevis oocytes. Furthermore, we suggest the existence of a general mechanism dependent on monovalent cations that optimizes the expression of membrane proteins.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
1421-9778
pubmed:author
pubmed:copyrightInfo
2009 S. Karger AG, Basel.
pubmed:issnType
Electronic
pubmed:volume
23
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
9-24
pubmed:meshHeading
pubmed:year
2009
pubmed:articleTitle
Expression of ENaC and other transport proteins in Xenopus oocytes is modulated by intracellular Na+.
pubmed:affiliation
Institute of Animal Physiology, Westphalian Wilhelms-University Muenster, Germany.
pubmed:publicationType
Journal Article