Tonic PKA Activity Regulates SK Channel Nanoclustering and Somatodendritic Distribution

Small-conductance calcium-activated potassium (SK) channels mediate a potassium conductance in the brain and are involved in synaptic plasticity, learning, and memory. SK channels show a distinct subcellular localization that is crucial for their neuronal functions. However, the mechanisms that cont...

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Bibliographic Details
Published in:Journal of molecular biology 2016-06, Vol.428 (11), p.2521-2537
Main Authors: Abiraman, Krithika, Sah, Megha, Walikonis, Randall S., Lykotrafitis, George, Tzingounis, Anastasios V.
Format: Article
Language:English
Subjects:
Animals
Apamin - metabolism
Brain - metabolism
Calcium - metabolism
Cell Line
Cyclic AMP - metabolism
Cyclic AMP-Dependent Protein Kinases - metabolism
dual-color fluorescence
Electrophysiology - methods
HEK293 Cells
Humans
Patch-Clamp Techniques - methods
potassium channels
Pyramidal Cells - metabolism
Rats
second messengers
single-molecule atomic force microscopy
Small-Conductance Calcium-Activated Potassium Channels - metabolism
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Summary:Small-conductance calcium-activated potassium (SK) channels mediate a potassium conductance in the brain and are involved in synaptic plasticity, learning, and memory. SK channels show a distinct subcellular localization that is crucial for their neuronal functions. However, the mechanisms that control this spatial distribution are unknown. We imaged SK channels labeled with fluorophore-tagged apamin and monitored SK channel nanoclustering at the single molecule level by combining atomic force microscopy and toxin (i.e., apamin) pharmacology. Using these two complementary approaches, we found that native SK channel distribution in pyramidal neurons, across the somatodendritic domain, depends on ongoing cyclic adenosine monophosphate (cAMP)-protein kinase A (PKA) levels, strongly limiting SK channel expression at the pyramidal neuron soma. Furthermore, tonic cAMP-PKA levels also controlled whether SK channels were expressed in nanodomains as single entities or as a group of multiple channels. Our study reveals a new level of regulation of SK channels by cAMP-PKA and suggests that ion channel topography and nanoclustering might be under the control of second messenger cascades. [Display omitted] •Tonic PKA activity regulates the cell-surface expression of SK channels in neurons.•Tonic PKA activity determines the somatodendritic distribution and nanoclustering of SK channels in neurons.•Cell-surface expression and nanoclustering of SK2 channel isoforms, SK2-S and SK2-L, are under the control of tonic PKA activity.
ISSN:0022-2836
1089-8638
DOI:10.1016/j.jmb.2016.04.014