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 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.
Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06269, USA.
Krithika
K
Abiraman
Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT 06269, USA.
Megha
M
Sah
Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT 06269, USA.
Randall S
RS
Walikonis
Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06269, USA; Department of Mechanical Engineering, University of Connecticut, Storrs, CT 06269, USA. Electronic address: gelyko@engr.uconn.edu.
George
G
Lykotrafitis
Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06269, USA; Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT 06269, USA. Electronic address: anastasios.tzingounis@uconn.edu.
Anastasios V
AV
Tzingounis
D000818:Animals; D001030:Apamin / Q000378:metabolism; D001921:Brain / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004594:Electrophysiology / Q000379:methods; D057809:HEK293 Cells; D006801:Humans; D018408:Patch-Clamp Techniques / Q000379:methods; D017966:Pyramidal Cells / Q000378:metabolism*; D051381:Rats; D051640:Small-Conductance Calcium-Activated Potassium Channels / Q000378:metabolism*
D051640:Small-Conductance Calcium-Activated Potassium Channels; D001030:Apamin; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D002118:Calcium
dual-color fluorescence; potassium channels; second messengers; single-molecule atomic force microscopy