Serum and glucocorticoid inducible kinases functionally regulate ClC-2 channels.
ClC-2 participates in the regulation of neuronal excitability, chloride secretion, and cell volume. The ClC-2 sequence contains a consensus site (Ser82) for phosphorylation by the serum and glucocorticoid inducible kinase isoforms SGK1-3. Thus, the present study explored whether ClC-2 is regulated by those kinases. ClC-2 expression in Xenopus oocytes induced inwardly rectifying currents that increased upon coexpression of SGK1-3 and the related kinase PKB. The stimulatory effect was still present upon disruption of the SGK phosphorylation site. SGKs can phosphorylate the ubiquitin ligase Nedd4-2 and prevent Nedd4-2 from binding to its target. Therefore, the role of Nedd4-2 in ClC-2 modulation was investigated. ClC-2 activity decreased upon Nedd4-2 coexpression, an effect reversed by the kinases. According to chemiluminescence ClC-2 membrane abundance was enhanced by SGKs and diminished by Nedd4-2. These observations suggest that SGK1-3 and Nedd4-2 regulate ClC-2 at least in part by modulating ClC-2 abundance at the plasma membrane.
Palmada
Monica
M
Physiologisches Institut, Universität Tübingen, Gmelinstr. 5, D-72076 Tübingen, Germany.
Dieter
Michael
M
Boehmer
Christoph
C
Waldegger
Siegfried
S
Lang
Florian
F
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002462:Cell Membrane / Q000378:metabolism; D018118:Chloride Channels / Q000235:genetics / Q000378:metabolism*; D017931:DNA Primers / Q000235:genetics; D056827:Endosomal Sorting Complexes Required for Transport; D005260:Female; D017874:Immediate-Early Proteins; D066298:In Vitro Techniques; D008564:Membrane Potentials; D016297:Mutagenesis, Site-Directed; D000075702:Nedd4 Ubiquitin Protein Ligases; D009687:Nuclear Proteins; D009865:Oocytes / Q000378:metabolism; D018408:Patch-Clamp Techniques; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism; D029867:Xenopus Proteins; D014982:Xenopus laevis; D000099184:Serum-Glucocorticoid Regulated Kinases
D018118:Chloride Channels; D017931:DNA Primers; D056827:Endosomal Sorting Complexes Required for Transport; D017874:Immediate-Early Proteins; D000075702:Nedd4 Ubiquitin Protein Ligases; D009687:Nuclear Proteins; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D011994:Recombinant Proteins; D044767:Ubiquitin-Protein Ligases; D029867:Xenopus Proteins; D000099184:Serum-Glucocorticoid Regulated Kinases; C000618482:Nedd4 protein, Xenopus; C000618460:nedd4l protein, Xenopus