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Serum and glucocorticoid inducible kinases functionally regulate ClC-2 channels
Monica Palmada1, Michael Dieter, Christoph Boehmer
1Physiologisches Institut, Universität Tübingen, Gmelinstr. 5, D-72076 Tübingen, Germany.
Biochemical and Biophysical Research Communications
|September 11, 2004
Summary
Serum and glucocorticoid inducible kinases (SGK1-3) and Nedd4-2 regulate the chloride channel ClC-2. These kinases and Nedd4-2 modulate ClC-2 membrane abundance, impacting neuronal excitability and chloride secretion.
Area of Science:
- Molecular biology
- Cell physiology
- Ion channel function
Background:
- Chloride channel 2 (ClC-2) is crucial for neuronal excitability, chloride secretion, and cell volume regulation.
- ClC-2 possesses a phosphorylation site (Ser82) targeted by serum and glucocorticoid inducible kinases (SGK1-3).
Purpose of the Study:
- To investigate the regulatory role of SGK1-3 and protein kinase B (PKB) on ClC-2 function.
- To explore the involvement of the ubiquitin ligase Nedd4-2 in ClC-2 modulation by SGKs.
Main Methods:
- Xenopus oocyte expression system to study ClC-2 currents.
- Site-directed mutagenesis to disrupt the SGK phosphorylation site on ClC-2.
- Chemiluminescence assays to assess ClC-2 membrane abundance.
Main Results:
- Coexpression of SGK1-3 or PKB with ClC-2 enhanced inwardly rectifying currents.
- This stimulatory effect persisted even when the SGK phosphorylation site was disrupted.
- Nedd4-2 coexpression decreased ClC-2 activity, an effect reversed by SGKs.
- SGKs increased ClC-2 membrane abundance, while Nedd4-2 diminished it.
Conclusions:
- SGK1-3 and Nedd4-2 regulate ClC-2 activity.
- This regulation occurs, at least in part, by modulating ClC-2 abundance at the plasma membrane.