Interuniversity Consortium for Magnetic Resonance of Metalloproteins, Sesto Fiorentino, Italy
Chiara Donadoni
Department of Biosciences, University of Milan, Milan, Italy
Bianca Introini
Department of Biosciences, University of Milan, Milan, Italy
Pietro Mesirca
Institut de Génomique Fonctionnelle, CNRS, INSERM F-34094, Université de Montpellier, Montpellier, France; Laboratory of Excellence Ion Channels Science and Therapeutics, Valbonne, France
Institut de Génomique Fonctionnelle, CNRS, INSERM F-34094, Université de Montpellier, Montpellier, France; Laboratory of Excellence Ion Channels Science and Therapeutics, Valbonne, France
Gerhard Thiel
Department of Biology, TU-Darmstadt, Darmstadt, Germany
Lucia Banci
Department of Chemistry, University of Florence, Florence, Italy; Magnetic Resonance Center, University of Florence, Florence, Italy; Interuniversity Consortium for Magnetic Resonance of Metalloproteins, Sesto Fiorentino, Italy; Institute of Neurosciences, Consiglio Nazionale delle Ricerche, Florence, Italy
Binding of TRIP8b to the cyclic nucleotide binding domain (CNBD) of mammalian hyperpolarization-activated cyclic nucleotide-gated (HCN) channels prevents their regulation by cAMP. Since TRIP8b is expressed exclusively in the brain, we envisage that it can be used for orthogonal control of HCN channels beyond the central nervous system. To this end, we have identified by rational design a 40-aa long peptide (TRIP8bnano) that recapitulates affinity and gating effects of TRIP8b in HCN isoforms (hHCN1, mHCN2, rbHCN4) and in the cardiac current If in rabbit and mouse sinoatrial node cardiomyocytes. Guided by an NMR-derived structural model that identifies the key molecular interactions between TRIP8bnano and the HCN CNBD, we further designed a cell-penetrating peptide (TAT-TRIP8bnano) which successfully prevented β-adrenergic activation of mouse If leaving the stimulation of the L-type calcium current (ICaL) unaffected. TRIP8bnano represents a novel approach to selectively control HCN activation, which yields the promise of a more targeted pharmacology compared to pore blockers.
