Hyperpolarization-activated cyclic nucleotide-gated potassium channel 2 (HCN2)

Hyperpolarization-activated cyclic nucleotide-gated potassium channel 2 (HCN2) is a tetrameric membrane ion channel encoded by the HCN2 gene, primarily permeable to sodium and potassium ions but with a lower selectivity for potassium compared to classic K+ channels. HCN2 is widely expressed, especially in the central nervous system and heart, where it contributes to spontaneous electrical activity, pacing, and neuron excitability by carrying the I(h) current. Activation of HCN2 is regulated both by membrane potential (hyperpolarization) and the binding of cyclic nucleotides (cAMP, cGMP, cCMP) at its cyclic nucleotide-binding domain. HCN2 plays critical roles in pacemaker activity, neuronal rhythmicity, and pain signal transmission; loss- or gain-of-function can contribute to disease states such as chronic pain, epilepsy, and cardiac arrhythmia. Selective small molecule blockers (such as ivabradine and zatebradine) and genetic modulation of HCN2 are being explored for therapeutic purposes, primarily for pain and cardiac pacing disorders.

Other names

HCN2HAC1BCNG2ih2Hyperpolarization-activated cyclic nucleotide-gated channel 2Potassium/sodium hyperpolarization-activated cyclic nucleotide-gated ion channel 2

Direct blockade of hyperpolarization-activated current (Ih) to reduce excitability in target neurons or cardiac cells Allosteric modulation via cyclic nucleotide interaction (i.e., drugs may alter cAMP/cGMP/cCMP binding and channel activation/kinetics) Altering channel voltage dependence by changing local cyclic nucleotide or membrane potential