Expression of ENaC and other transport proteins in Xenopus oocytes is modulated by intracellular Na +

Kristina Kusche-Vihrog, Andrei Segal, Ryszard Grygorczyk, Nadine Bangel-Ruland, Willy Van Driessche, Wolf Michael Weber*

*Korrespondierende/r Autor/-in für diese Arbeit
9 Zitate (Scopus)


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 (I ami ) and conductance (G ami ) peak at a [Na + ] i of ∼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 ∼ 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 I ami and G ami 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.

ZeitschriftCellular Physiology and Biochemistry
Seiten (von - bis)9-24
PublikationsstatusVeröffentlicht - 2009

Strategische Forschungsbereiche und Zentren

  • Forschungsschwerpunkt: Gehirn, Hormone, Verhalten - Center for Brain, Behavior and Metabolism (CBBM)


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