Hyperpolarization-activated cyclic nucleotide–gated (HCN) channels are dually gated channels that are operated by voltage and by neurotransmitters via the cAMP system. cAMP-dependent HCN regulation has been proposed to play a key role in regulating circuit behavior in the thalamus. By analyzing a knockin mouse model (HCN2EA), in which binding of cAMP to HCN2 was abolished by 2 amino acid exchanges (R591E, T592A), we found that cAMP gating of HCN2 is essential for regulating the transition between the burst and tonic modes of firing in thalamic dorsal-lateral geniculate (dLGN) and ventrobasal (VB) nuclei. HCN2EA mice display impaired visual learning, generalized seizures of thalamic origin, and altered NREM sleep properties. VB-specific deletion of HCN2, but not of HCN4, also induced these generalized seizures of the absence type, corroborating a key role of HCN2 in this particular nucleus for controlling consciousness. Together, our data define distinct pathological phenotypes resulting from the loss of cAMP-mediated gating of a neuronal HCN channel.
Verena Hammelmann, Marc Sebastian Stieglitz, Henrik Hülle, Karim Le Meur, Jennifer Kass, Manuela Brümmer, Christian Gruner, René Dominik Rötzer, Stefanie Fenske, Jana Hartmann, Benedikt Zott, Anita Lüthi, Saskia Spahn, Markus Moser, Dirk Isbrandt, Andreas Ludwig, Arthur Konnerth, Christian Wahl-Schott, Martin Biel
Impaired modulation of Ih by cAMP in thalamocortical neurons expressing HCN2EA.