Abstract
β(1)- and β(2)-adrenergic receptors utilize different signaling mechanisms to control cardiac function. Recent studies demonstrated that β(2)-adrenergic receptors (β(2)ARs) colocalize with some ion channels that are critical for proper cardiac function. Here, we demonstrate that β(2)ARs form protein complexes with the pacemaker HCN4 channel, as well as with other subtypes of HCN channels. The adrenergic receptor-binding site was identified at a proximal region of the N-terminal tail of the HCN4 channel. A synthetic peptide derived from the β(2)AR-binding domain of the HCN4 channel disrupted interaction between HCN4 and β(2)AR. In addition, treatment with this peptide prevented adrenergic augmentation of pacemaker currents and spontaneous contraction rates but did not affect adrenergic regulation of voltage-gated calcium currents. These results suggest that the ion channel-receptor complex is a critical mechanism in ion channel regulation.
Publication types
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Research Support, N.I.H., Extramural
MeSH terms
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Adrenergic beta-Agonists / pharmacology
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Amino Acid Sequence
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Animals
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Animals, Newborn
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Cells, Cultured
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Cyclic Nucleotide-Gated Cation Channels / genetics
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Cyclic Nucleotide-Gated Cation Channels / metabolism*
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HEK293 Cells
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HeLa Cells
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Humans
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Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels
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Immunoblotting
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Ion Channel Gating / physiology*
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Isoproterenol / pharmacology
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Membrane Potentials / drug effects
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Membrane Potentials / physiology
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Molecular Sequence Data
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Multiprotein Complexes / metabolism*
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Muscle Proteins / genetics
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Muscle Proteins / metabolism*
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Myocytes, Cardiac / drug effects
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Myocytes, Cardiac / metabolism
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Myocytes, Cardiac / physiology
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Patch-Clamp Techniques
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Peptides / pharmacology
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Potassium Channels
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Protein Binding / drug effects
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Protein Isoforms / genetics
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Protein Isoforms / metabolism
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Pyrimidines / pharmacology
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Rats
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Receptors, Adrenergic, beta-2 / genetics
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Receptors, Adrenergic, beta-2 / metabolism*
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Sequence Homology, Amino Acid
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Sinoatrial Node / cytology
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Sinoatrial Node / drug effects
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Sinoatrial Node / physiology
Substances
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Adrenergic beta-Agonists
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Cyclic Nucleotide-Gated Cation Channels
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HCN4 protein, human
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Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels
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Multiprotein Complexes
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Muscle Proteins
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Peptides
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Potassium Channels
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Protein Isoforms
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Pyrimidines
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Receptors, Adrenergic, beta-2
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ICI D2788
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Isoproterenol