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cAMP-dependent kinase does not modulate the Slack sodium-activated potassium channel
Megan O Nuwer1, Kelly E Picchione, Arin Bhattacharjee
1Program in Neuroscience, The State University of New York, Buffalo, NY 14214, USA.
Neuropharmacology
|June 23, 2009
Summary
Protein kinase A (PKA) does not acutely regulate Slack channels, a key sodium-activated potassium channel in neurons. Experiments show PKA activation or inhibition does not alter Slack channel function or gating kinetics.
Area of Science:
- Neuroscience
- Molecular Biology
- Ion Channel Physiology
Background:
- The Slack gene encodes a Na(+)-activated K(+) channel crucial for neuronal function.
- Slack channels possess structural similarities to prokaryotic channels and contain phosphorylation sites for protein kinases.
- While protein kinase C (PKC) modulates Slack, the effect of protein kinase A (PKA) remains undetermined.
Purpose of the Study:
- To investigate whether PKA directly regulates the function and gating of Slack channels.
Main Methods:
- Whole-cell patch-clamp recordings in HEK-293 cells stably expressing Slack channels.
- Application of forskolin, 1,9-dideoxyforskolin, and 8-bromo-cAMP to assess PKA pathway involvement.
- Excised inside-out patch recordings with direct application of PKA catalytic subunit and phosphatase 2B.
- Mutagenesis of a putative PKA phosphorylation site.
Main Results:
- Forskolin and its inactive analog inhibited Slack currents, suggesting a non-PKA-mediated effect.
- 8-bromo-cAMP and direct PKA catalytic subunit application did not alter Slack channel activity.
- Mutating the putative phosphorylation site did not affect channel kinetics.
Conclusions:
- PKA phosphorylation does not acutely modulate the function or gating kinetics of Slack channels.
- The observed inhibition by forskolin is likely mediated by a PKA-independent pathway.
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