Neurotransmitter modulation of small-conductance Ca2+-activated K+ channels by regulation of Ca2+ gating

作者：Maingret Francois; Coste Bertrand; Hao Jizhe; Giamarchi Aurelie; Allen Duane; Crest Marcel; Litchfield David W; Adelman John P; Delmas Patrick^*

来源：Neuron, 2008, 59(3): 439-449.

DOI：10.1016/j.neuron.2008.05.026

Small-conductance Ca2+-activated K+ (SK) channels are widely expressed in neuronal tissues where they underlie postspike hyperpolarizations, regulate spike-frequency adaptation, and shape synaptic responses. SK channels constitutively interact with calmodulin (CaM), which serves as Ca2+ sensor, and with protein kinase CK2 and protein phosphatase 2A, which modulate their Ca2+ gating. By recording coupled activities of Ca2+ and SK2 channels, we showed that SK2 channels can be inhibited by neurotransmitters independently of changes in the activity of the priming Ca2+ channels. This inhibition involves SK2-associated CK2 and results from a 3-fold reduction in the Ca2+ sensitivity of channel gating. CK2 phosphorylated SK2-bound CaM but not KCNQ2-bound CaM, thereby selectively regulating SK2 channels. We extended these observations to sensory neurons by showing that noradrenaline inhibits SK current and increases neuronal excitability in a CK2-dependent fashion. Hence, neurotransmitter-initiated signaling cascades can dynamically regulate Ca2+ sensitivity of SK channels and directly influence somatic excitability.

• 出版日期2008-8-14