Neuron
Volume 71, Issue 6, 22 September 2011, Pages 1102-1115
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Article
DPP6 Establishes the A-Type K+ Current Gradient Critical for the Regulation of Dendritic Excitability in CA1 Hippocampal Neurons

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Summary

Subthreshold-activating A-type K+ currents are essential for the proper functioning of the brain, where they act to delay excitation and regulate firing frequency. In CA1 hippocampal pyramidal neuron dendrites, the density of A-type K+ current increases with distance from the soma, playing an important role in synaptic integration and plasticity. The mechanism underlying this gradient has, however, remained elusive. Here, dendritic recordings from mice lacking the Kv4 transmembrane auxiliary subunit DPP6 revealed that this protein is critical for generating the A-current gradient. Loss of DPP6 led to a decrease in A-type current, specifically in distal dendrites. Decreased current density was accompanied by a depolarizing shift in the voltage dependence of channel activation. Together these changes resulted in hyperexcitable dendrites with enhanced dendritic AP back-propagation, calcium electrogenesis, and induction of synaptic long-term potentiation. Despite enhanced dendritic excitability, firing behavior evoked by somatic current injection was mainly unaffected in DPP6-KO recordings, indicating compartmentalized regulation of neuronal excitability.

Highlights

► Mice were created lacking the autism-associated Kv4 auxiliary subunit gene, DPP6 ► DPP6-KO mice lack the normal dendritic A-type K+ current gradient ► DPP6-KO dendrites are hyperexcitable, displaying boosted AP propagation ► Synaptic plasticity is more readily induced in DPP6-KO mice

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