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The HCN domain is required for HCN channel cell-surface expression and couples voltage- and cAMP-dependent gating mechanisms.
J Biol Chem. 2020 06 12; 295(24):8164-8173.JB

Abstract

Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are major regulators of synaptic plasticity and rhythmic activity in the heart and brain. Opening of HCN channels requires membrane hyperpolarization and is further facilitated by intracellular cyclic nucleotides (cNMPs). In HCN channels, membrane hyperpolarization is sensed by the membrane-spanning voltage sensor domain (VSD), and the cNMP-dependent gating is mediated by the intracellular cyclic nucleotide-binding domain (CNBD) connected to the pore-forming S6 transmembrane segment via the C-linker. Previous functional analysis of HCN channels has suggested a direct or allosteric coupling between the voltage- and cNMP-dependent activation mechanisms. However, the specifics of this coupling remain unclear. The first cryo-EM structure of an HCN1 channel revealed that a novel structural element, dubbed the HCN domain (HCND), forms a direct structural link between the VSD and C-linker-CNBD. In this study, we investigated the functional significance of the HCND. Deletion of the HCND prevented surface expression of HCN2 channels. Based on the HCN1 structure analysis, we identified Arg237 and Gly239 residues on the S2 of the VSD that form direct interactions with Ile135 on the HCND. Disrupting these interactions abolished HCN2 currents. We also identified three residues on the C-linker-CNBD (Glu478, Gln482, and His559) that form direct interactions with residues Arg154 and Ser158 on the HCND. Disrupting these interactions affected both voltage- and cAMP-dependent gating of HCN2 channels. These findings indicate that the HCND is necessary for the cell-surface expression of HCN channels and provides a functional link between voltage- and cAMP-dependent mechanisms of HCN channel gating.

Authors+Show Affiliations

Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, D. C., USA.Interdisciplinary Program in Neuroscience, Georgetown University Medical Center, Washington, D. C., USA.Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, D. C., USA.Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, D. C., USA tib5@georgetown.edu. Interdisciplinary Program in Neuroscience, Georgetown University Medical Center, Washington, D. C., USA.

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural

Language

eng

PubMed ID

32341127

Citation

Wang, Ze-Jun, et al. "The HCN Domain Is Required for HCN Channel Cell-surface Expression and Couples Voltage- and cAMP-dependent Gating Mechanisms." The Journal of Biological Chemistry, vol. 295, no. 24, 2020, pp. 8164-8173.
Wang ZJ, Blanco I, Hayoz S, et al. The HCN domain is required for HCN channel cell-surface expression and couples voltage- and cAMP-dependent gating mechanisms. J Biol Chem. 2020;295(24):8164-8173.
Wang, Z. J., Blanco, I., Hayoz, S., & Brelidze, T. I. (2020). The HCN domain is required for HCN channel cell-surface expression and couples voltage- and cAMP-dependent gating mechanisms. The Journal of Biological Chemistry, 295(24), 8164-8173. https://doi.org/10.1074/jbc.RA120.013281
Wang ZJ, et al. The HCN Domain Is Required for HCN Channel Cell-surface Expression and Couples Voltage- and cAMP-dependent Gating Mechanisms. J Biol Chem. 2020 06 12;295(24):8164-8173. PubMed PMID: 32341127.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The HCN domain is required for HCN channel cell-surface expression and couples voltage- and cAMP-dependent gating mechanisms. AU - Wang,Ze-Jun, AU - Blanco,Ismary, AU - Hayoz,Sebastien, AU - Brelidze,Tinatin I, Y1 - 2020/04/27/ PY - 2020/03/01/received PY - 2020/04/23/revised PY - 2020/4/29/pubmed PY - 2020/12/31/medline PY - 2020/4/29/entrez KW - HCN2 KW - HCND KW - cyclic AMP (cAMP) KW - cyclic nucleotide KW - cyclic nucleotide binding domain KW - gating KW - hyperpolarization-activated cyclic nucleotide-gated channel 1 (HCN1) KW - ion channel KW - ligand-binding protein KW - membrane trafficking SP - 8164 EP - 8173 JF - The Journal of biological chemistry JO - J Biol Chem VL - 295 IS - 24 N2 - Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are major regulators of synaptic plasticity and rhythmic activity in the heart and brain. Opening of HCN channels requires membrane hyperpolarization and is further facilitated by intracellular cyclic nucleotides (cNMPs). In HCN channels, membrane hyperpolarization is sensed by the membrane-spanning voltage sensor domain (VSD), and the cNMP-dependent gating is mediated by the intracellular cyclic nucleotide-binding domain (CNBD) connected to the pore-forming S6 transmembrane segment via the C-linker. Previous functional analysis of HCN channels has suggested a direct or allosteric coupling between the voltage- and cNMP-dependent activation mechanisms. However, the specifics of this coupling remain unclear. The first cryo-EM structure of an HCN1 channel revealed that a novel structural element, dubbed the HCN domain (HCND), forms a direct structural link between the VSD and C-linker-CNBD. In this study, we investigated the functional significance of the HCND. Deletion of the HCND prevented surface expression of HCN2 channels. Based on the HCN1 structure analysis, we identified Arg237 and Gly239 residues on the S2 of the VSD that form direct interactions with Ile135 on the HCND. Disrupting these interactions abolished HCN2 currents. We also identified three residues on the C-linker-CNBD (Glu478, Gln482, and His559) that form direct interactions with residues Arg154 and Ser158 on the HCND. Disrupting these interactions affected both voltage- and cAMP-dependent gating of HCN2 channels. These findings indicate that the HCND is necessary for the cell-surface expression of HCN channels and provides a functional link between voltage- and cAMP-dependent mechanisms of HCN channel gating. SN - 1083-351X UR - https://www.unboundmedicine.com/medline/citation/32341127/The_HCN_domain_is_required_for_HCN_channel_cell_surface_expression_and_couples_voltage__and_cAMP_dependent_gating_mechanisms_ DB - PRIME DP - Unbound Medicine ER -