Targeted deletion of Kcne2 impairs HCN channel function in mouse thalamocortical circuits.

TitleTargeted deletion of Kcne2 impairs HCN channel function in mouse thalamocortical circuits.
Publication TypeJournal Article
Year of Publication2012
AuthorsYing S-W, Kanda VA, Hu Z, Purtell K, King EC, Abbott GW, Goldstein PA
JournalPLoS One
Date Published2012
Keywords4-Aminopyridine, Animals, Cerebral Cortex, Cyclic Nucleotide-Gated Cation Channels, Down-Regulation, Female, Gene Deletion, Gene Targeting, Glutamates, Ion Channel Gating, Ion Channels, Male, Mice, Mice, Inbred C57BL, Nerve Net, Neurons, Potassium Channels, Potassium Channels, Voltage-Gated, Pyramidal Cells, Pyrimidines, Somatosensory Cortex, Thalamus

BACKGROUND: Hyperpolarization-activated, cyclic nucleotide-gated (HCN) channels generate the pacemaking current, I(h), which regulates neuronal excitability, burst firing activity, rhythmogenesis, and synaptic integration. The physiological consequence of HCN activation depends on regulation of channel gating by endogenous modulators and stabilization of the channel complex formed by principal and ancillary subunits. KCNE2 is a voltage-gated potassium channel ancillary subunit that also regulates heterologously expressed HCN channels; whether KCNE2 regulates neuronal HCN channel function is unknown.

METHODOLOGY/PRINCIPAL FINDINGS: We investigated the effects of Kcne2 gene deletion on I(h) properties and excitability in ventrobasal (VB) and cortical layer 6 pyramidal neurons using brain slices prepared from Kcne2(+/+) and Kcne2(-/-) mice. Kcne2 deletion shifted the voltage-dependence of I(h) activation to more hyperpolarized potentials, slowed gating kinetics, and decreased I(h) density. Kcne2 deletion was associated with a reduction in whole-brain expression of both HCN1 and HCN2 (but not HCN4), although co-immunoprecipitation from whole-brain lysates failed to detect interaction of KCNE2 with HCN1 or 2. Kcne2 deletion also increased input resistance and temporal summation of subthreshold voltage responses; this increased intrinsic excitability enhanced burst firing in response to 4-aminopyridine. Burst duration increased in corticothalamic, but not thalamocortical, neurons, suggesting enhanced cortical excitatory input to the thalamus; such augmented excitability did not result from changes in glutamate release machinery since miniature EPSC frequency was unaltered in Kcne2(-/-) neurons.

CONCLUSIONS/SIGNIFICANCE: Loss of KCNE2 leads to downregulation of HCN channel function associated with increased excitability in neurons in the cortico-thalamo-cortical loop. Such findings further our understanding of the normal physiology of brain circuitry critically involved in cognition and have implications for our understanding of various disorders of consciousness.

Alternate JournalPLoS ONE
PubMed ID22880098
PubMed Central IDPMC3411840
Grant ListR01 HL079275 / HL / NHLBI NIH HHS / United States
R01 HL079275 / HL / NHLBI NIH HHS / United States
R01HL101190 / HL / NHLBI NIH HHS / United States