Cyclic dinucleotides bind the C-linker of HCN4 to control channel cAMP responsiveness

Nat Chem Biol. 2014 Jun;10(6):457-62. doi: 10.1038/nchembio.1521. Epub 2014 Apr 28.

Abstract

cAMP mediates autonomic regulation of heart rate by means of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, which underlie the pacemaker current If. cAMP binding to the C-terminal cyclic nucleotide binding domain enhances HCN open probability through a conformational change that reaches the pore via the C-linker. Using structural and functional analysis, we identified a binding pocket in the C-linker of HCN4. Cyclic dinucleotides, an emerging class of second messengers in mammals, bind the C-linker pocket (CLP) and antagonize cAMP regulation of the channel. Accordingly, cyclic dinucleotides prevent cAMP regulation of If in sinoatrial node myocytes, reducing heart rate by 30%. Occupancy of the CLP hence constitutes an efficient mechanism to hinder β-adrenergic stimulation on If. Our results highlight the regulative role of the C-linker and identify a potential drug target in HCN4. Furthermore, these data extend the signaling scope of cyclic dinucleotides in mammals beyond their first reported role in innate immune system.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Binding Sites
  • Blotting, Western
  • Crystallography, X-Ray
  • Cyclic AMP / metabolism*
  • Cyclic GMP / analogs & derivatives*
  • Cyclic GMP / chemistry
  • Cyclic GMP / metabolism
  • Dinucleoside Phosphates / chemistry
  • Dinucleoside Phosphates / metabolism*
  • HEK293 Cells
  • High-Throughput Screening Assays
  • Humans
  • Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels / genetics
  • Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels / metabolism*
  • Ion Channel Gating / drug effects
  • Ion Channel Gating / physiology*
  • Ligands
  • Mice
  • Mice, Inbred C57BL
  • Molecular Docking Simulation
  • Molecular Structure
  • Muscle Proteins / genetics
  • Muscle Proteins / metabolism*
  • Myocytes, Cardiac / drug effects
  • Myocytes, Cardiac / metabolism
  • Patch-Clamp Techniques
  • Potassium Channels / genetics
  • Potassium Channels / metabolism*
  • Sinoatrial Node / cytology
  • Sinoatrial Node / drug effects
  • Sinoatrial Node / metabolism
  • Small Molecule Libraries / chemistry
  • Small Molecule Libraries / pharmacology
  • Transfection

Substances

  • Dinucleoside Phosphates
  • HCN4 protein, human
  • Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels
  • Ligands
  • Muscle Proteins
  • Potassium Channels
  • Small Molecule Libraries
  • cyclic diadenosine phosphate
  • bis(3',5')-cyclic diguanylic acid
  • Cyclic AMP
  • Cyclic GMP

Associated data

  • PDB/4KL1
  • PubChem-Substance/175441889
  • PubChem-Substance/175441890
  • PubChem-Substance/175441891
  • PubChem-Substance/175441892
  • PubChem-Substance/175441893
  • PubChem-Substance/175441894
  • PubChem-Substance/175441895
  • PubChem-Substance/175441896
  • PubChem-Substance/175441897
  • PubChem-Substance/175441898
  • PubChem-Substance/175441899