Affinage

HCN2

Potassium/sodium hyperpolarization-activated cyclic nucleotide-gated channel 2 · UniProt Q9UL51

Length
889 aa
Mass
97.0 kDa
Annotated
2026-04-28
100 papers in source corpus 38 papers cited in narrative 37 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

HCN2 is a hyperpolarization-activated, cyclic nucleotide-gated cation channel that generates the Ih current underlying cardiac pacemaking, neuronal rhythmicity, nociceptive sensitization, and mood regulation. The channel forms homotetramers or heteromers with HCN1 or HCN4, with voltage-dependent gating driven by charged S4 residues and modulated by direct cAMP binding to the C-terminal CNBD/C-linker domain — where intersubunit salt bridges stabilize the closed state and cAMP-induced conformational changes promote opening with as few as two of four subunits liganded (PMID:15572346, PMID:20624593, PMID:10962006). Channel activity is further tuned by phosphorylation at S641 (cGKII, inhibitory) and S861 (Akt, facilitatory), by the β-subunit KCNE2/MiRP1, by cytoskeletal mechanosensitivity, and by upstream transcriptional (Sp1) and post-transcriptional (miR-1, miR-133) regulation (PMID:21347269, PMID:33240105, PMID:15292247, PMID:18458081). Loss-of-function and gain-of-function HCN2 variants cause epileptic encephalopathy and febrile seizure susceptibility, while conditional deletion in nociceptors abolishes cAMP-dependent inflammatory and migraine-like pain (PMID:22131395, PMID:24525276, PMID:36658457, PMID:37746765).

Mechanistic history

Synthesis pass · year-by-year structured walk · 19 steps
  1. 2000 High

    Establishing the structural basis of voltage sensing: mutagenesis of the S4 domain identified which charged residues confer hyperpolarization-dependent gating versus channel folding, resolving how HCN2 senses membrane potential.

    Evidence Site-directed mutagenesis of S2–S4 residues with two-electrode voltage clamp and surface-expression assay in Xenopus oocytes

    PMID:10962006

    Open questions at the time
    • No structural model of S4 movement during gating transitions
    • Role of S4 charges in heteromeric channel gating not tested
  2. 2001 High

    Demonstrating functional heteromerization: HCN1–HCN2 coassembly produces channels with intermediate kinetics and cAMP sensitivity that cannot arise from independent homomeric populations, establishing heteromeric assembly as a physiological mechanism for Ih diversity.

    Evidence Two-electrode voltage clamp and cell-free patches in Xenopus oocytes (PMID:11331358); tandem-dimer constructs (PMID:11133998)

    PMID:11133998 PMID:11331358

    Open questions at the time
    • Stoichiometry of heteromeric assemblies not determined
    • In vivo subunit composition not resolved at single-channel level
  3. 2001 Medium

    Linking GPCR signaling to HCN2: both Gi- and Gs-coupled receptors enhance HCN2 current through cAMP generated via distinct G-protein pathways, independent of PKA, showing that HCN2 is a direct downstream integrator of neuromodulatory signals.

    Evidence Coexpression of mu-opioid and 5-HT4a receptors with HCN channels in Xenopus oocytes; pharmacological dissection with AC inhibitor

    PMID:11680627

    Open questions at the time
    • No confirmation in native neurons
    • Relative contributions of Gα versus Gβγ pathways not quantified in vivo
  4. 2003 High

    Mapping determinants of isoform-specific kinetics: chimera and point-mutation analysis between HCN2 and HCN4 pinpointed single residues in S1 and S2 that account for the kinetic differences between these cardiac isoforms.

    Evidence HCN2/HCN4 chimeras and point mutants with electrophysiology

    PMID:12813043

    Open questions at the time
    • Structural basis of how S1/S2 residues couple to activation gate unknown
  5. 2004 High

    Resolving the cAMP gating mechanism at the C-linker: salt bridges between neighboring C-linkers and between C-linker and CNBD stabilize the closed state; cAMP binding disrupts these, lowering the energetic barrier to opening — a mechanism confirmed by charge-reversal rescue.

    Evidence Site-directed mutagenesis with charge-reversal double mutants; electrophysiology in oocytes

    PMID:15572346

    Open questions at the time
    • Dynamic rearrangement of salt bridges not tracked in real time
    • Coupling pathway from C-linker to pore gate not structurally resolved
  6. 2004 High

    Identifying KCNE2 as a cardiac β-subunit: KCNE2/MiRP1 coassembles with HCN2 in ventricular myocytes and increases maximal conductance ~4-fold without shifting voltage dependence, establishing auxiliary subunit modulation of cardiac Ih.

    Evidence Reciprocal co-immunoprecipitation of endogenous and expressed proteins; patch-clamp in neonatal rat ventricular myocytes

    PMID:15292247

    Open questions at the time
    • Binding interface not mapped
    • In vivo significance of KCNE2–HCN2 interaction not confirmed by genetic studies
  7. 2007 High

    Defining HCN2 as the principal dendritic Ih isoform in thalamic reticular neurons: HCN2 knockout abolished Ih and cAMP responsiveness, increased EPSP summation, and enhanced downstream GABAergic output, demonstrating that HCN2 constrains excitability at a specific thalamocortical circuit node.

    Evidence HCN2 knockout mice; patch-clamp; immunofluorescence colocalization with GluR4 in dendritic spines

    PMID:17687049

    Open questions at the time
    • Contribution of HCN2 to oscillatory thalamic rhythms not directly measured
    • Compensatory changes by other HCN isoforms not excluded
  8. 2008 High

    Establishing post-transcriptional control by microRNAs: miR-1 and miR-133 directly repress HCN2 protein via 3′UTR targeting; their downregulation in cardiac hypertrophy (driven by reduced SRF) leads to HCN2 re-expression and increased arrhythmogenic If.

    Evidence miRNA mimics, antisense oligonucleotides, SRF siRNA; rat cardiac hypertrophy model

    PMID:18458081

    Open questions at the time
    • Quantitative contribution of miRNA derepression versus transcriptional upregulation not separated
    • In vivo arrhythmia rescue by miR-1/133 restoration not shown
  9. 2009 High

    Revealing proteolytic processing of cardiac HCN2: endogenous cardiac HCN2 is C-terminally truncated to ~60 kDa, lacking the CNBD; truncated HCN2 coassembles with full-length HCN4, and cAMP sensitivity of native If derives from HCN4, revising the model of cardiac Ih composition.

    Evidence Western blotting with domain-specific antibodies; immunoprecipitation from adult mouse heart; reconstitution of truncated HCN2/HCN4 heteromers in HEK293 cells

    PMID:19574228

    Open questions at the time
    • Protease responsible for C-terminal cleavage not identified
    • Whether processing is regulated or constitutive unknown
  10. 2010 High

    Quantifying ligand–gating coupling stoichiometry: patch-clamp fluorometry showed that only two of four cAMP molecules suffice for full channel activation and that voltage sensor conformation reciprocally influences cAMP binding affinity, establishing a bidirectional allosteric coupling model.

    Evidence Patch-clamp fluorometry with fluorescent cAMP analog; kinetic modeling

    PMID:20624593

    Open questions at the time
    • Structural basis of subunit asymmetry in partial liganding not determined
    • Whether the same stoichiometry applies in heteromeric channels unknown
  11. 2011 High

    Identifying inhibitory phosphorylation by cGKII: cGKII binds HCN2's proximal C-terminus and phosphorylates S641, shifting activation negatively and opposing the direct stimulatory effect of cGMP on the CNBD — revealing a dual, antagonistic cGMP signaling mode.

    Evidence Co-IP from mouse brain; immunohistochemistry; S641A mutagenesis; electrophysiology

    PMID:21347269

    Open questions at the time
    • Physiological context where cGKII phosphorylation dominates over direct cGMP binding not defined
    • Phosphatase that reverses S641 phosphorylation unknown
  12. 2011 High

    Linking HCN2 mutations to human epilepsy: the homozygous E515K C-linker mutation causes a loss-of-function shift that increases cortical neuron excitability, directly connecting HCN2 dysfunction to epileptic encephalopathy.

    Evidence Patient mutation identification; voltage clamp in oocytes; current-clamp in neonatal rat cortical neurons

    PMID:22131395

    Open questions at the time
    • Patient cohort small; genotype–phenotype correlation across larger populations lacking
    • Whether dominant-negative effects occur with endogenous HCN1 not tested
  13. 2012 High

    Demonstrating allosteric coupling from pore to CNBD: S6 inner-pore residues modulate state-dependent cAMP binding, and ZD7288 block reduces ligand binding, proving that conformational information flows bidirectionally between pore and CNBD.

    Evidence Patch-clamp fluorometry; alanine scanning of S6; biochemical cAMP binding assay

    PMID:22689828

    Open questions at the time
    • Structural pathway connecting S6 to CNBD not visualized
    • Whether this coupling differs in heteromeric channels untested
  14. 2014 High

    Dissecting peripheral versus central HCN2 roles in pain: sensory neuron-specific HCN2 knockout eliminates mechanical but not heat hyperalgesia in chronic inflammation, while global knockout also eliminates thermal hyperalgesia, separating peripheral and central contributions to inflammatory pain.

    Evidence Conditional and global HCN2 knockout mice; behavioral testing; single-fiber recordings

    PMID:24525276

    Open questions at the time
    • Identity of central HCN2-expressing neurons mediating thermal hyperalgesia not determined
    • Interaction with other HCN isoforms in central pain circuits not resolved
  15. 2017 High

    Establishing the HCN2–PKA axis in nociception: gain-of-function HCN2 variants shift activation positively, and Cre/loxP deletion shows that both HCN2 and PKA are required for cAMP-mediated inflammatory pain sensitization in nociceptors.

    Evidence Voltage clamp of variants in oocytes; conditional knockout in nociceptors; Ca2+ imaging in DRG neurons; in vivo pain assays

    PMID:28767511 PMID:29064616

    Open questions at the time
    • Specific PKA phosphorylation site(s) on HCN2 mediating nociceptor sensitization not identified
    • Contribution of HCN2 heteromers in nociceptors not addressed
  16. 2019 High

    Linking HCN2 to mood regulation: HCN2 expression and Ih are reduced in nucleus accumbens cholinergic interneurons of depressed mice; viral HCN2 overexpression in these neurons rescues firing rate and reverses depressive behavior, establishing a cell-type-specific role in affective circuits.

    Evidence Viral HCN2 overexpression; chemogenetics; brain-slice electrophysiology; behavioral assays in chronic stress models

    PMID:30638901

    Open questions at the time
    • Upstream mechanism causing HCN2 downregulation in depression not identified
    • Whether pharmacological HCN2 activation is sufficient for antidepressant effect unknown
  17. 2020 High

    Identifying Akt-mediated facilitatory phosphorylation: PI3K/Akt phosphorylates HCN2 at S861, and S861A mutation fully occludes PI3K inhibitor effects, establishing a second kinase pathway (complementing cGKII at S641) that tunes HCN2 gating.

    Evidence PI3K/Akt inhibitors; active Akt perfusion; S861A mutagenesis; patch-clamp in HEK293 cells

    PMID:33240105

    Open questions at the time
    • In vivo relevance of Akt–HCN2 signaling in specific tissues not demonstrated
    • Interplay between S641 and S861 phosphorylation not studied
  18. 2022 High

    Defining HCN2 as a mediator of migraine-like pain: NO/cGMP signaling depolarizes HCN2 activation in trigeminal neurons, and HCN2 conditional knockout or pharmacological block abolishes migraine-like behavior in three rodent models, positioning HCN2 as a therapeutic target for migraine.

    Evidence Conditional HCN2 knockout; pharmacological HCN2 blockade; in vivo cGMP measurement; single-unit TG recordings; three rodent migraine models

    PMID:36658457

    Open questions at the time
    • Whether cGMP acts via direct CNBD binding or via cGKII phosphorylation in trigeminal neurons not distinguished
    • Human genetic evidence linking HCN2 variants to migraine not established
  19. 2025 Medium

    Expanding the pathogenic variant spectrum: multiple HCN2 missense variants cause either loss-of-function (dominant-negative, trafficking impairment) or gain-of-function (increased conductance), demonstrating bidirectional pathogenicity and establishing membrane trafficking as a disease-relevant regulatory step.

    Evidence Voltage clamp in oocytes; confocal imaging of membrane trafficking in HEK cells; 3D structural analysis

    PMID:40468825

    Open questions at the time
    • Genotype–phenotype correlations across patient cohorts not systematically assessed
    • Rescue strategies for trafficking-deficient variants not explored

Open questions

Synthesis pass · forward-looking unresolved questions
  • Key unresolved questions include: the full-length structure of HCN2 captured in multiple gating states, the identity of the protease cleaving cardiac HCN2, the interplay between multiple phosphorylation sites (S641, S861, and putative PKA sites) in native cells, and whether pharmacological HCN2 modulation can be harnessed therapeutically for pain, epilepsy, or depression.
  • No full-length cryo-EM structure of HCN2 in multiple states
  • Protease for cardiac C-terminal cleavage unidentified
  • Combinatorial phosphorylation logic not studied
  • No clinical trial data for HCN2-selective modulators

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0005215 transporter activity 7 GO:0140299 molecular sensor activity 3
Localization
GO:0005886 plasma membrane 4 GO:0005829 cytosol 1
Pathway
R-HSA-1643685 Disease 4 R-HSA-162582 Signal Transduction 3 R-HSA-382551 Transport of small molecules 3 R-HSA-112316 Neuronal System 2
Partners
AKT1HCN1HCN4KCNE2MINT2PRKG2S-SCAMTAMALIN
Complex memberships
HCN1–HCN2 heteromeric channelHCN2–HCN4 heteromeric channelHCN2–KCNE2 channel complex

Evidence

Reading pass · 37 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2001 HCN1 and HCN2 subunits coassemble to form heteromultimeric channels with novel properties intermediate between homomers; heteromeric channels show pronounced cAMP sensitivity (+14 mV shift) and kinetics that cannot be explained by linear summation of independent homomeric populations. Basal cAMP in intact oocytes tonically modulates Ih. Two-electrode voltage clamp in Xenopus oocytes; cell-free patch recordings; coexpression of HCN1 and HCN2 The Journal of general physiology High 11331358
2000 HCN1 and HCN2 channels form functional heteromers demonstrated using concatenated tandem-dimer constructs; heteromeric channels activate faster than HCN2 alone with voltage dependence similar to HCN2 and intermediate cAMP sensitivity. Concatenated cDNA construct (tandem dimer) expressed in Xenopus oocytes; two-electrode voltage clamp The Journal of biological chemistry High 11133998
2000 Charged residues in the S4 voltage-sensing domain of HCN2 (K291, R294, R297, R300 contributing to voltage dependence; K303 and S306 essential for gating; R312 for folding) are critical determinants of hyperpolarization-activated gating. Site-directed mutagenesis of S2, S3, S4 residues; two-electrode voltage clamp in Xenopus oocytes; chemiluminescence surface expression assay The Journal of biological chemistry High 10962006
2004 Salt bridges in the C-linker region of HCN2 — an intersubunit interaction between neighboring C-linkers and an intrasubunit interaction between C-linker and CNBD — stabilize the closed channel conformation; disrupting these bridges by mutation increases channel opening favorability, and swapping charged residues rescues wild-type behavior. Site-directed mutagenesis of salt-bridge residues; electrophysiology in Xenopus oocytes; rescue by charge-reversal double mutants The Journal of general physiology High 15572346
2004 KCNE2 (MiRP1) co-assembles with HCN2 in ventricular myocytes (shown by co-immunoprecipitation of both expressed and endogenous proteins) and acts as a beta subunit, increasing maximal HCN2 conductance ~4-fold and accelerating activation/deactivation kinetics without shifting voltage dependence. Co-immunoprecipitation; adenoviral overexpression in neonatal rat ventricular myocytes; patch-clamp electrophysiology The Journal of biological chemistry High 15292247
2003 Single amino acid residues in transmembrane segments S1 and S2 and the S1-S2 linker of HCN2/HCN4 determine the difference in activation kinetics between the two isoforms; F221 in S1 of HCN2 (corresponding to L272 in HCN4) is a major determinant of fast activation, and I308M in S2 abolishes cAMP-dependent acceleration of activation. HCN2/HCN4 chimeras and point mutants; electrophysiology in heterologous expression system The Journal of biological chemistry High 12813043
2010 Using patch-clamp fluorometry with a fluorescent cAMP analog, full ligand-induced activation of HCN2 channels is achieved with only two of four ligands bound; kinetic analysis shows direct interaction between the voltage sensor and the CNBD, and proves reciprocity between ligand binding affinity and conformational state of the channel. Patch-clamp fluorometry with fluorescent cAMP analog; kinetic modeling Neuron High 20624593
2004 HCN2 forms a protein complex with neuronal scaffold proteins tamalin, S-SCAM, and Mint2 through distinct interaction modes: tamalin PDZ domain binds both the PDZ-binding motif and internal C-terminal tail of HCN2; S-SCAM PDZ domain binds the CNBD and downstream sequence; Mint2 MID domain binds the CNBD-downstream sequence. Co-immunoprecipitation from rat brain and heterologous cells; GST pull-down assays Genes to cells Medium 15265006
2009 In the adult mouse heart, HCN2 undergoes proteolytic processing to a ~60 kDa form lacking the C-terminus (including the cAMP-binding domain); this C-terminally truncated HCN2 co-assembles with full-length HCN4 to form heteromeric channels that activate faster than either homomer and display properties similar to native cardiac If. The cAMP sensitivity of cardiac If is therefore conferred by the HCN4 subunit. Western blotting with C- and N-terminal antibodies; immunoprecipitation of endogenous cardiac channels; electrophysiology of heteromeric channels in HEK293 cells The Journal of biological chemistry High 19574228
2001 Gi-coupled (mu-opioid) and Gs-coupled (5-HT4a) receptors both enhance HCN2 but not HCN1 currents through upregulation of cAMP via Gbetagamma-activation of adenylyl cyclase (for Gi) or Galphas (for Gs), causing a ~15 mV positive shift in activation voltage; the effect is independent of PKA/PKC and is blocked by AC inhibitor SQ22536. Two-electrode voltage clamp in Xenopus oocytes coexpressing receptors and HCN channels; pharmacological dissection Pflugers Archiv Medium 11680627
2006 cAMP modulation of the HCN2 C-linker/CNBD causes large-scale quaternary oscillations of the domain that are absent in the apo-form; loss of cAMP leads to increased CNBD flexibility that exerts an inhibitory effect on gating, while cAMP-induced oscillation of C-linker may couple to pore opening. Molecular dynamics simulation of HCN2 CNBD/C-linker crystal structure in presence and absence of cAMP Biophysical journal Low 16500960
2011 cGMP-dependent protein kinase II (cGKII) physically interacts with HCN2 via the proximal C-terminus and phosphorylates HCN2 at serine 641, shifting voltage dependence of activation ~2-5 mV negative and counteracting the direct stimulatory effect of cGMP binding to the CNBD. This inhibitory phosphorylation is abolished by S641 mutation or catalytically inactive cGKII. Co-immunoprecipitation; immunohistochemistry in mouse brain; site-directed mutagenesis; electrophysiology in heterologous cells PloS one High 21347269
2012 The inner pore region (S6) contributes to state-dependent cAMP binding in HCN2: ZD7288 (open channel blocker interacting with inner pore) reduces activity-dependent cAMP binding; alanine scanning of S6 residues T426-A435 identifies T426, M430, H434 (enhanced binding) and F431, I432 (reduced binding) as modulators of ligand-channel interaction. Patch-clamp fluorometry; alanine scanning mutagenesis of S6; biochemical cAMP binding assay with isolated CNBD The Journal of general physiology High 22689828
2009 Niflumic acid (NFA) alters HCN2 gating by interacting with the extracellular end of the S4 voltage sensor; NFA preferentially acts on closed channels, causing hyperpolarizing shift of activation and slowed kinetics; neutralization of any three of the four outer S4 basic residues (by Q mutation) abolishes the NFA-induced shift. Site-directed mutagenesis; two-electrode voltage clamp in Xenopus oocytes; state-dependent drug application Molecular pharmacology High 19218366
2012 Ca2+-activated adenylyl cyclase 1 (AC1) physically and functionally interacts with HCN2 in cardiac myocytes: AC1 (but not AC6) increases intracellular cAMP, shifts HCN2 activation ~10 mV positive, and introduces Ca2+-dependence to beta-adrenergic modulation of HCN2 current (BAPTA abolishes isoproterenol response in AC1- but not AC6-expressing cells). Co-expression of AC1/AC6 with HCN2 in neonatal rat ventricular myocytes; electrophysiology; cAMP measurement; Ca2+ chelation Journal of molecular and cellular cardiology Medium 22484253
2009 HCN2-expressing non-myocyte cells (mesenchymal stem cells, HEK293, Cx43-transfected HeLa) electrically coupled to ventricular myocytes via gap junctions (connexin43) form a two-cell pacing unit; HCN2 current transfers to the myocyte proportional to junctional conductance, triggering spontaneous action potentials that are abolished by gap junction blocker carbenoxolone or HCN blocker THA. Co-culture patch-clamp; gap junction conductance measurement; pharmacological blockers The Journal of physiology High 19736302
2010 HCN2 can function as a non-channel regulatory protein for L-type calcium channels (LTCC): the N-terminus of HCN2 interacts with the IQ motif of the alpha1C subunit of LTCC, inducing alpha1C inactivation. In the absence of alpha2delta, this interaction requires calmodulin; with alpha2delta, calmodulin is not required. HCN2-induced fast inactivation of LTCC is confirmed in hippocampal neurons by overexpression of wild-type vs. N-terminus-deleted HCN2. Co-expression in HEK cells; electrophysiology; overexpression in hippocampal neurons; N-terminal deletion mutagenesis American journal of physiology. Cell physiology Medium 20164379
2011 HCN2 channels in the renal collecting duct transport ammonium (NH4+): HCN2 cRNA-injected Xenopus oocytes conduct K+ > NH4+ >> Na+; ZD7288 selectively blocks the acidification rate in intercalated cells (not principal cells) of microperfused outer medullary collecting duct; HCN2 protein in kidney is N-glycosylated. Xenopus oocyte electrophysiology; microperfusion of collecting duct; pharmacological inhibition with ZD7288; western blot glycosylation analysis Kidney international Medium 21796099
2014 Singlet oxygen (1O2) modifies HCN2 channel function in a state-dependent manner at histidine H434 in the S6 segment near the activation gate: 1O2 applied to open channels slows deactivation and generates instantaneous current (Iinst), whereas application to closed channels reduces Ih amplitude; H434A mutation abolishes deactivation delay and Iinst generation. Photodynamic approach with fluorescein-conjugated cAMP or HCN2-SOG fusion protein; state-dependent laser pulses; H434A mutagenesis; patch-clamp electrophysiology The Journal of general physiology High 24733837
2015 Using patch-clamp fluorometry with fluorescent cAMP, ligand binding to non-voltage-activated (resting) HCN2 channels induces a conformational flip intermediate state; kinetic analysis reveals modest cooperativity among subunits during this conformational change, less than that seen in channels preactivated by hyperpolarization. Patch-clamp fluorometry with fluorescent cAMP analog; global kinetic fitting Biophysical journal Medium 26636938
2018 Voltage-dependent activation of HCN2 is governed by two separable voltage-dependent steps followed by voltage-independent pore opening; cAMP binding exerts multiple effects: stabilizing the open pore, reducing total gating charge from ~8 to ~5, making an additional closed state accessible, and strongly accelerating ON-gating but not OFF-gating. Global fitting of hidden Markovian models to complex patch-clamp data sets; macroscopic current analysis PLoS computational biology Medium 29565972
2007 HCN2 is the primary functional isoform underlying Ih in mouse reticular thalamic nucleus (RTN) neurons, localized to dendritic spines where it colocalizes with GluR4 (AMPA receptor subunit); HCN2 knockout abolishes Ih and cAMP sensitivity in RTN neurons, increases EPSP temporal summation, and enhances GABAergic output to relay neurons, demonstrating that dendritic HCN2 constrains glutamate-driven excitability. HCN2 knockout mice; whole-cell patch-clamp; immunofluorescence colocalization; IPSC frequency recording in relay neurons The Journal of neuroscience High 17687049
2011 A homozygous loss-of-function point mutation E515K in the HCN2 C-linker causes a large negative shift of the activation range and slowed kinetics, effectively abolishing HCN2 contribution; homomeric but not heteromeric mutant/WT channels lower the threshold for action potential firing and strongly increase excitability and firing frequency of cortical neurons. Patient mutation screening; Xenopus oocyte voltage clamp; transfection into acutely isolated neonatal rat cortical neurons; current-clamp recordings The Journal of neuroscience High 22131395
2013 Novel HCN2 mutation S126L causes temperature-dependent kinetic shifts: mutant channels display faster activation kinetics at higher temperatures without altering voltage dependence or cAMP sensitivity, increasing Ih availability during hyperthermia and thereby contributing to febrile seizure susceptibility. Whole-cell patch-clamp electrophysiology of mutant vs. WT HCN2 at different temperatures PloS one Medium 24324597
2017 HCN2 gain-of-function variants S632W and V246M cause a depolarizing shift in voltage dependence of activation; using Cre/loxP-based selective disruption in nociceptors, HCN2 and PKA are both required for cAMP-mediated inflammatory pain sensitization, and PKA-dependent phosphorylation facilitates Ih in nociceptive neurons. Two-electrode voltage clamp in Xenopus oocytes (variants); Cre/loxP conditional knockout in nociceptors; calcium imaging in DRG neurons; in vivo behavioral pain assays Human mutation / Pain High 28767511 29064616
2008 miR-1 and miR-133 directly repress HCN2 protein expression (miR-1 targets HCN2 and HCN4; miR-133 targets HCN2 only) by acting on 3'UTR target sites; in cardiac hypertrophy, downregulation of miR-1/miR-133 driven by reduced serum response factor (SRF) leads to re-expression of HCN2/HCN4 protein and increased If contributing to arrhythmogenesis. Transfection of miRNA mimics and antisense oligonucleotides; Western blot; siRNA knockdown of SRF; rat cardiac hypertrophy model The Journal of biological chemistry High 18458081
2009 The transcription factor Sp1 acts as a common transactivator of HCN2 and HCN4 genes; Sp1 binds core promoter regions identified by 5'RACE and luciferase reporter assays; siRNA silencing of Sp1 prevents overexpression of HCN2/HCN4 in hypertrophic cardiomyocytes. 5'RACE; luciferase reporter assay; siRNA knockdown; real-time RT-PCR; Western blot in rat hypertrophy model Cellular physiology and biochemistry Medium 19471099
2014 HCN2 channels in sensory neuron-specific knockout mice contribute to mechanical but not heat hyperalgesia during chronic (CFA) inflammation; central HCN2 channels (revealed by global knockout) additionally mediate thermal hyperalgesia under chronic inflammatory conditions. Conditional sensory neuron-specific and inducible global HCN2 knockout mice; behavioral pain testing; single-fiber recordings; conduction velocity measurement Pain High 24525276
2016 HCN2 physically associates with gamma-secretase (shown by proximity ligation assay and co-immunoprecipitation from rat brain); silencing or pharmacological inhibition of HCN2 reduces secreted Abeta, sAPP, and APP-CTF levels, indicating that HCN2 affects APP maturation or beta-secretase processing rather than gamma-secretase activity directly. Pull-down/co-immunoprecipitation from rat brain; proximity ligation assay; siRNA knockdown; ZD7288 treatment; Western blot for APP processing intermediates Biochemical and biophysical research communications Medium 28017718
2020 PI3K/Akt signaling regulates HCN2 current: PI3K inhibition causes negative shift in activation voltage and reduced current magnitude; Akt phosphorylates HCN2 at serine 861; S861A mutation mimics Akt inhibition, and Akt inhibitor has no further effect on S861A mutant, demonstrating that Akt phosphorylation of S861 accounts for PI3K effects on HCN2. PI3K/Akt inhibitors in HEK293 cells expressing HCN2; active Akt protein perfusion; S861A site-directed mutagenesis; whole-cell patch-clamp Frontiers in physiology High 33240105
2022 NO donor GTN increases cGMP in trigeminal ganglion (TG) in vivo and causes a rightward (depolarizing) shift in the voltage dependence of HCN currents in isolated TG neurons, increasing neuronal excitability; pharmacological block or genetic deletion of HCN2 abolishes migraine-like pain in rodent models and suppresses C-FOS induction in the trigeminocervical complex. HCN2 conditional knockout; pharmacological HCN2 blockade; in vivo cGMP measurement; single-unit recording of TG neurons; C-FOS immunohistochemistry; three rodent migraine models The Journal of neuroscience High 36658457
2005 Cell swelling (hypoosmotic challenge) activates HCN2 channels, increasing current amplitude by ~30% without altering kinetics; this requires an intact F-actin cytoskeleton (abolished by cytochalasin D), indicating mechanosensitive regulation of HCN2 via the cytoskeleton. Co-expression of HCN2 with aquaporin1 in Xenopus oocytes; two-electrode voltage clamp during hypoosmotic challenge; cytochalasin D treatment Biophysical journal Medium 15980171
2023 A novel de novo HCN2 loss-of-function variant G460D causes dominant-negative reduction of HCN2 current in HEK293 cells, with mutant channels retained intracellularly and failing to reach the membrane; heteromeric HCN1-HCN2 G460D channels also show reduced Ih, and ketogenic diet treatment in vitro does not directly rescue HCN2 G460D activity. Whole-cell patch-clamp in transfected HEK293 cells; immunofluorescence membrane trafficking assay; neonatal rat cortical neuron transfection Epilepsia Medium 37746765
2025 Multiple pathogenic HCN2 missense variants cause either loss-of-function (dominant negative or trafficking impairment to membrane) or gain-of-function (increased conductance); p.Leu377His, p.Pro493Leu, and p.Gly587Asp render channels electrophysiologically silent and impair membrane trafficking, while p.Arg324His strongly increases HCN2 conductance. Two-electrode voltage clamp in Xenopus oocytes; confocal imaging of membrane trafficking in HEK cells; 3D structural analysis Annals of neurology Medium 40468825
2019 HCN2 channels in cholinergic interneurons (ChIs) of nucleus accumbens shell regulate tonic firing rate; HCN2 expression and function are decreased in depressed mice; viral overexpression of HCN2 in NAc ChIs rescues cell firing and reverses depressive phenotypes in chronic stress models. Chemogenetics; viral HCN2 overexpression; whole-cell patch-clamp in brain slices; behavioral assays Neuron High 30638901
2014 cAMP binding to the HCN2 gating ring accelerates Mg2+ block kinetics in a manner that is not a secondary consequence of enhanced channel opening, demonstrating loose (non-obligate) coupling between the cyclic nucleotide-binding gating ring and the open state of the pore. Electrophysiology combined with simulation studies; analysis of Mg2+ block kinetics with and without cAMP PloS one Medium 24983358
2012 HCN1 in cochlear hair cells forms two mutually exclusive complexes: one with protocadherin 15 CD3 and filamin A (without HCN2), and another with HCN2 (without protocadherin 15 CD3); the interaction of HCN1 with protocadherin 15 CD3 is Ca2+-dependent and mediated by HCN1-specific N-terminal sequence not replicated by HCN2 or HCN4 peptides. Immunoprecipitation from cochlear tissue; confocal and EM immunogold localization in hair cell stereocilia; peptide binding assays The Journal of biological chemistry Medium 22948144

Source papers

Stage 0 corpus · 100 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2001 Properties of hyperpolarization-activated pacemaker current defined by coassembly of HCN1 and HCN2 subunits and basal modulation by cyclic nucleotide. The Journal of general physiology 336 11331358
2000 Functional heteromerization of HCN1 and HCN2 pacemaker channels. The Journal of biological chemistry 175 11133998
1999 HAC-1, a Drosophila homolog of APAF-1 and CED-4 functions in developmental and radiation-induced apoptosis. Molecular cell 173 10619022
2007 Novel approaches for gene-specific interference via manipulating actions of microRNAs: examination on the pacemaker channel genes HCN2 and HCN4. Journal of cellular physiology 149 17516552
2008 Down-regulation of miR-1/miR-133 contributes to re-expression of pacemaker channel genes HCN2 and HCN4 in hypertrophic heart. The Journal of biological chemistry 147 18458081
2004 HCN2 and HCN1 channels govern the regularity of autonomous pacemaking and synaptic resetting in globus pallidus neurons. The Journal of neuroscience : the official journal of the Society for Neuroscience 144 15525777
2004 Salt bridges and gating in the COOH-terminal region of HCN2 and CNGA1 channels. The Journal of general physiology 119 15572346
2004 MiRP1 modulates HCN2 channel expression and gating in cardiac myocytes. The Journal of biological chemistry 104 15292247
2010 Interdependence of receptor activation and ligand binding in HCN2 pacemaker channels. Neuron 96 20624593
2006 Membrane resting potential of thalamocortical relay neurons is shaped by the interaction among TASK3 and HCN2 channels. Journal of neurophysiology 95 16760342
2019 HCN2 Channels in Cholinergic Interneurons of Nucleus Accumbens Shell Regulate Depressive Behaviors. Neuron 90 30638901
2011 Recessive loss-of-function mutation in the pacemaker HCN2 channel causing increased neuronal excitability in a patient with idiopathic generalized epilepsy. The Journal of neuroscience : the official journal of the Society for Neuroscience 76 22131395
2000 Functional roles of charged residues in the putative voltage sensor of the HCN2 pacemaker channel. The Journal of biological chemistry 71 10962006
2012 HCN1 and HCN2 in Rat DRG neurons: levels in nociceptors and non-nociceptors, NT3-dependence and influence of CFA-induced skin inflammation on HCN2 and NT3 expression. PloS one 69 23236374
2008 Absence epilepsy in apathetic, a spontaneous mutant mouse lacking the h channel subunit, HCN2. Neurobiology of disease 65 19150498
1999 Thyroid hormone regulates hyperpolarization-activated cyclic nucleotide-gated channel (HCN2) mRNA in the rat heart. Circulation research 65 10488052
2018 HCN2 Rescues brain defects by enforcing endogenous voltage pre-patterns. Nature communications 60 29519998
2014 HCN2 channels account for mechanical (but not heat) hyperalgesia during long-standing inflammation. Pain 58 24525276
1999 The human gene coding for HCN2, a pacemaker channel of the heart. Biochimica et biophysica acta 56 10524219
2007 Mutation analysis of the hyperpolarization-activated cyclic nucleotide-gated channels HCN1 and HCN2 in idiopathic generalized epilepsy. Neurobiology of disease 53 17931874
2013 HCN2/SkM1 gene transfer into canine left bundle branch induces stable, autonomically responsive biological pacing at physiological heart rates. Journal of the American College of Cardiology 52 23395072
2018 Selective Blockade of HCN1/HCN2 Channels as a Potential Pharmacological Strategy Against Pain. Frontiers in pharmacology 50 30467478
2003 Molecular basis for the different activation kinetics of the pacemaker channels HCN2 and HCN4. The Journal of biological chemistry 48 12813043
2013 Novel HCN2 mutation contributes to febrile seizures by shifting the channel's kinetics in a temperature-dependent manner. PloS one 47 24324597
2007 Dendritic HCN2 channels constrain glutamate-driven excitability in reticular thalamic neurons. The Journal of neuroscience : the official journal of the Society for Neuroscience 47 17687049
2004 Hyperpolarization-activated, cyclic nucleotide-gated HCN2 cation channel forms a protein assembly with multiple neuronal scaffold proteins in distinct modes of protein-protein interaction. Genes to cells : devoted to molecular & cellular mechanisms 44 15265006
2012 Ca(2+)-stimulated adenylyl cyclase AC1 generates efficient biological pacing as single gene therapy and in combination with HCN2. Circulation 42 22753192
2015 Increased expression of HCN2 channel protein in L4 dorsal root ganglion neurons following axotomy of L5- and inflammation of L4-spinal nerves in rats. Neuroscience 39 25813712
2014 Activation of GABAB receptors ameliorates cognitive impairment via restoring the balance of HCN1/HCN2 surface expression in the hippocampal CA1 area in rats with chronic cerebral hypoperfusion. Molecular neurobiology 39 24838625
2020 HCN2 Channel-Induced Rescue of Brain Teratogenesis via Local and Long-Range Bioelectric Repair. Frontiers in cellular neuroscience 36 32528251
2015 The bZIP Transcription Factor HAC-1 Is Involved in the Unfolded Protein Response and Is Necessary for Growth on Cellulose in Neurospora crassa. PloS one 31 26132395
2009 Coupling an HCN2-expressing cell to a myocyte creates a two-cell pacing unit. The Journal of physiology 30 19736302
2018 HCN2 contributes to oxaliplatin-induced neuropathic pain through activation of the CaMKII/CREB cascade in spinal neurons. Molecular pain 28 29806529
2017 Gain-of-function HCN2 variants in genetic epilepsy. Human mutation 27 29064616
2012 HCN1 and HCN2 proteins are expressed in cochlear hair cells: HCN1 can form a ternary complex with protocadherin 15 CD3 and F-actin-binding filamin A or can interact with HCN2. The Journal of biological chemistry 27 22948144
2015 Long-lasting spatial learning and memory impairments caused by chronic cerebral hypoperfusion associate with a dynamic change of HCN1/HCN2 expression in hippocampal CA1 region. Neurobiology of learning and memory 26 26021557
2010 Dynamic changes in HCN2, HCN4, KCNE1, and KCNE2 expression in ventricular cells from acute myocardial infarction rat hearts. Biochemical and biophysical research communications 25 20381460
2003 Proteomic characterization of the human cortical neuronal cell line HCN-2. Journal of chemical neuroanatomy 25 14615026
2017 The change of HCN1/HCN2 mRNA expression in peripheral nerve after chronic constriction injury induced neuropathy followed by pulsed electromagnetic field therapy. Oncotarget 23 27901476
2016 Baclofen ameliorates spatial working memory impairments induced by chronic cerebral hypoperfusion via up-regulation of HCN2 expression in the PFC in rats. Behavioural brain research 23 27085590
2014 Imbalance of HCN1 and HCN2 expression in hippocampal CA1 area impairs spatial learning and memory in rats with chronic morphine exposure. Progress in neuro-psychopharmacology & biological psychiatry 23 25301101
2011 The hyperpolarization-activated cyclic nucleotide-gated HCN2 channel transports ammonium in the distal nephron. Kidney international 21 21796099
2009 Proteolytic processing of HCN2 and co-assembly with HCN4 in the generation of cardiac pacemaker channels. The Journal of biological chemistry 21 19574228
2017 Protein kinase A regulates inflammatory pain sensitization by modulating HCN2 channel activity in nociceptive sensory neurons. Pain 20 28767511
2009 Transcriptional control of pacemaker channel genes HCN2 and HCN4 by Sp1 and implications in re-expression of these genes in hypertrophied myocytes. Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology 20 19471099
2023 Activation of CB1R alleviates central sensitization by regulating HCN2-pNR2B signaling in a chronic migraine rat model. The journal of headache and pain 19 37085778
2020 Blockade of HCN2 Channels Provides Neuroprotection Against Ischemic Injury via Accelerating Autophagic Degradation in Hippocampal Neurons. Neuroscience bulletin 19 32519067
2009 Niflumic acid alters gating of HCN2 pacemaker channels by interaction with the outer region of S4 voltage sensing domains. Molecular pharmacology 19 19218366
2012 Ca2+-activated adenylyl cyclase 1 introduces Ca2+-dependence to beta-adrenergic stimulation of HCN2 current. Journal of molecular and cellular cardiology 17 22484253
2006 cAMP Modulation of the cytoplasmic domain in the HCN2 channel investigated by molecular simulations. Biophysical journal 17 16500960
2001 Gi- and Gs-coupled receptors up-regulate the cAMP cascade to modulate HCN2, but not HCN1 pacemaker channels. Pflugers Archiv : European journal of physiology 17 11680627
2022 HCN2 channel-induced rescue of brain, eye, heart and gut teratogenesis caused by nicotine, ethanol and aberrant notch signalling. Wound repair and regeneration : official publication of the Wound Healing Society [and] the European Tissue Repair Society 16 35662339
2015 Conformational Flip of Nonactivated HCN2 Channel Subunits Evoked by Cyclic Nucleotides. Biophysical journal 16 26636938
2012 Inner activation gate in S6 contributes to the state-dependent binding of cAMP in full-length HCN2 channel. The Journal of general physiology 16 22689828
2022 PEX5R/Trip8b-HCN2 channel regulating neuroinflammation involved in perioperative neurocognitive disorders. Cell & bioscience 15 36104739
2021 Transcriptomic Analysis of HCN-2 Cells Suggests Connection among Oxidative Stress, Senescence, and Neuron Death after SARS-CoV-2 Infection. Cells 15 34571838
2018 Activation gating in HCN2 channels. PLoS computational biology 15 29565972
2016 Relevance of HCN2-expressing human mesenchymal stem cells for the generation of biological pacemakers. Stem cell research & therapy 15 27137910
2005 Hypoosmotic cell swelling as a novel mechanism for modulation of cloned HCN2 channels. Biophysical journal 15 15980171
2022 Up-regulation of HCN2 channels in a thalamocortical circuit mediates allodynia in mice. National science review 14 36846300
2012 Unraveling subunit cooperativity in homotetrameric HCN2 channels. Biophysical journal 14 23199914
2006 Evaluation of HCN2 abnormalities as a cause of juvenile audiogenic seizures in Black Swiss mice. Brain research 14 16542642
2021 Changes in peripheral HCN2 channels during persistent inflammation. Channels (Austin, Tex.) 12 33423595
2015 Fluoxetine ameliorates cognitive impairments induced by chronic cerebral hypoperfusion via down-regulation of HCN2 surface expression in the hippocampal CA1 area in rats. Pharmacology, biochemistry, and behavior 12 26549214
2007 Mesenchymal stem cells transfected with HCN2 genes by LentiV can be modified to be cardiac pacemaker cells. Medical hypotheses 12 17449188
2020 HCN2 and TBX3 Reprogram Human-Induced Pluripotent Stem Cells-Derived Cardiomyocytes into Pacemaker-Like Cells. DNA and cell biology 11 31916853
2018 Loss of HCN2 leads to delayed gastrointestinal motility and reduced energy intake in mice. PloS one 10 29466436
2016 Maturation and processing of the amyloid precursor protein is regulated by the potassium/sodium hyperpolarization-activated cyclic nucleotide-gated ion channel 2 (HCN2). Biochemical and biophysical research communications 10 28017718
2015 Decreased HCN2 expression in STN contributes to abnormal high-voltage spindles in the cortex and globus pallidus of freely moving rats. Brain research 10 25998542
2011 The cGMP-dependent protein kinase II Is an inhibitory modulator of the hyperpolarization-activated HCN2 channel. PloS one 10 21347269
2021 Isolated downregulation of HCN2 in ventricles of rats with streptozotocin-induced diabetic cardiomyopathy. BMC cardiovascular disorders 9 33653265
2019 Protein and surface expression of HCN2 and HCN4 subunits in mesocorticolimbic areas after cocaine sensitization. Neurochemistry international 9 30794847
2019 Decreased HCN2 channel expression attenuates neuropathic pain by inhibiting pro-inflammatory reactions and NF-κB activation in mice. International journal of clinical and experimental pathology 9 31933729
2024 Upregulation of HCN2 in ventral tegmental area is involved in morphine-induced conditioned place preference in rats. FEBS open bio 8 39267158
2015 The expression of hyperpolarization-activated cyclic nucleotide-gated channel 1 (HCN1) and HCN2 in the rat trigeminal ganglion, sensory root, and dental pulp. Neuroscience 8 25659346
2014 State-dependent and site-directed photodynamic transformation of HCN2 channel by singlet oxygen. The Journal of general physiology 8 24733837
2005 Functional significance of HCN2/3-mediated I(h) in striatal cells at early developmental stages. Journal of neuroscience research 8 16175581
2002 Nicotinamide protects HCN2 cells from the free radical generating toxin, tertiary butylhydroperoxide (t-BuOOH). Neurotoxicity research 8 12709297
2023 A novel de novo HCN2 loss-of-function variant causing developmental and epileptic encephalopathy treated with a ketogenic diet. Epilepsia 7 37746765
2022 HCN2 Ion Channels Drive Pain in Rodent Models of Migraine. The Journal of neuroscience : the official journal of the Society for Neuroscience 7 36658457
2021 Inhibition of the pesticide rotenone-induced Ca2+ signaling, cytotoxicity and oxidative stress in HCN-2 neuronal cells by the phenolic compound hydroxytyrosol. Pesticide biochemistry and physiology 7 34802529
2013 Ischemia-induced cell depolarization: does the hyperpolarization-activated cation channel HCN2 affect the outcome after stroke in mice? Experimental & translational stroke medicine 7 24373160
2021 Toward Biological Pacing by Cellular Delivery of Hcn2/SkM1. Frontiers in physiology 6 33488393
2020 Heightened reward response is associated with HCN2 overexpression in the ventral tegmental area in morphine-sensitized rats. Behavioural pharmacology 6 32040017
2020 HCN2 contributes to oxaliplatin-induced neuropathic pain by inducing spinal long-term potentiation via activation of NMDA receptor-mediated CaMKII signaling. Brain research bulletin 6 32165274
2010 Inactivation of L-type calcium channel modulated by HCN2 channel. American journal of physiology. Cell physiology 6 20164379
2024 Chronic but not acute nicotine treatment ameliorates acute inflammation-induced working memory impairment by increasing CRTC1 and HCN2 in adult male mice. CNS neuroscience & therapeutics 5 38353058
2017 The Proinflammatory Cytokine GITRL Contributes to TRAIL-mediated Neurotoxicity in the HCN-2 Human Neuronal Cell Line. Current Alzheimer research 5 28524007
2008 Age-dependent differences in the inhibition of HCN2 current in rat ventricular myocytes by the tyrosine kinase inhibitor erbstatin. Pflugers Archiv : European journal of physiology 5 18696104
2025 HCN2 deficiency correlates with memory deficits and hyperexcitability of dCA1 pyramidal neurons in Alzheimer's disease. Alzheimer's research & therapy 4 40016780
2025 HCN2-Associated Neurodevelopmental Disorders: Data from Patients and Xenopus Cell Models. Annals of neurology 4 40468825
2022 Gene knockdown of HCN2 ion channels in the ventral tegmental area reduces ethanol consumption in alcohol preferring rats. The American journal of drug and alcohol abuse 4 35377277
2022 Thyroid-stimulating hormone regulates cardiac function through modulating HCN2 via targeting microRNA-1a. FASEB journal : official publication of the Federation of American Societies for Experimental Biology 4 36125044
2021 Promotion of Differentiating Bone Marrow Mesenchymal Stromal Cells (BMSCs) into Cardiomyocytes via HCN2 and HCN4 Cotransfection. BioMed research international 4 34095298
2020 Regulation of HCN2 Current by PI3K/Akt Signaling. Frontiers in physiology 4 33240105
2019 Overexpression of the medium‑conductance calcium‑activated potassium channel (SK4) and the HCN2 channel to generate a biological pacemaker. Molecular medicine reports 4 31432175
2019 Effects of HCN2 Mutations on Dendritic Excitability and Synaptic Plasticity: A Computational Study. Neuroscience 4 31682955
2013 Hyperpolarization-activated cyclic nucleotide-gated 2 (HCN2) polymorphism is associated with chronic inflammatory periodontitis. A cross-sectional study. Journal of basic and clinical physiology and pharmacology 4 23907424
2022 Role of hyperpolarization-activated cyclic nucleotide-gated channel HCN2 in embryonic neural stem cell proliferation and differentiation. Neurochemistry international 3 35835292
2014 cAMP control of HCN2 channel Mg2+ block reveals loose coupling between the cyclic nucleotide-gating ring and the pore. PloS one 3 24983358