title: A new cell-penetrating peptide that blocks the autoinhibitory XIP domain of NCX1 and enhances antiporter activity.
abstract: The plasma membrane Na(+)/Ca(2+) exchanger (NCX) is a high-capacity ionic transporter that exchanges 3Na(+) ions for 1Ca(2+) ion. The first 20 amino acids of the f-loop, named exchanger inhibitory peptide (XIP(NCX1)), represent an autoinhibitory region involved in the Na(+)-dependent inactivation of the exchanger. Previous research has shown that an exogenous peptide having the same amino acid sequence as the XIP(NCX1) region exerts an inhibitory effect on NCX activity. In this study, we identified another regulatory peptide, named P1, which corresponds to the 562-688aa region of the exchanger. Patch-clamp analysis revealed that P1 increased the activity of the exchanger, whereas the XIP inhibited it. Furthermore, P1 colocalized with NCX1 thus suggesting a direct binding interaction. In addition, site-directed mutagenesis experiments revealed that the binding and the stimulatory effect of P1 requires a functional XIP(NCX1) domain on NCX1 thereby suggesting that P1 increases the exchanger activity by counteracting the action of this autoinhibitory sequence. Taken together, these results open a new strategy for developing peptidomimetic compounds that, by mimicking the functional pharmacophore of P1, might increase NCX1 activity and thus exert a therapeutic action in those diseases in which an increase in NCX1 activity might be helpful.
authors.affiliation: Division of Pharmacology, Department of Neuroscience, Reproductive and Odontostomatologic Sciences, School of Medicine, "Federico II" University of Naples, Naples, Italy.
authors.forename: Pasquale
authors.initials: P
authors.lastname: Molinaro
authors.affiliation: Division of Pharmacology, Department of Neuroscience, Reproductive and Odontostomatologic Sciences, School of Medicine, "Federico II" University of Naples, Naples, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Pannaccione
authors.affiliation: Division of Pharmacology, Department of Neuroscience, Reproductive and Odontostomatologic Sciences, School of Medicine, "Federico II" University of Naples, Naples, Italy.
authors.forename: Maria José
authors.initials: MJ
authors.lastname: Sisalli
authors.affiliation: Division of Pharmacology, Department of Neuroscience, Reproductive and Odontostomatologic Sciences, School of Medicine, "Federico II" University of Naples, Naples, Italy.
authors.forename: Agnese
authors.initials: A
authors.lastname: Secondo
authors.affiliation: Division of Pharmacology, Department of Neuroscience, Reproductive and Odontostomatologic Sciences, School of Medicine, "Federico II" University of Naples, Naples, Italy.
authors.forename: Ornella
authors.initials: O
authors.lastname: Cuomo
authors.affiliation: Istituto di Ricovero e Cura a Carattere Scientifico SDN, Naples, Italy.
authors.forename: Rossana
authors.initials: R
authors.lastname: Sirabella
authors.affiliation: Division of Pharmacology, Department of Neuroscience, Reproductive and Odontostomatologic Sciences, School of Medicine, "Federico II" University of Naples, Naples, Italy.
authors.forename: Maria
authors.initials: M
authors.lastname: Cantile
authors.affiliation: Division of Pharmacology, Department of Neuroscience, Reproductive and Odontostomatologic Sciences, School of Medicine, "Federico II" University of Naples, Naples, Italy.
authors.forename: Roselia
authors.initials: R
authors.lastname: Ciccone
authors.affiliation: Division of Pharmacology, Department of Neuroscience, Reproductive and Odontostomatologic Sciences, School of Medicine, "Federico II" University of Naples, Naples, Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: Scorziello
authors.affiliation: Division of Pharmacology, Department of Neuroscience, Reproductive and Odontostomatologic Sciences, School of Medicine, "Federico II" University of Naples, Naples, Italy.
authors.forename: Gianfranco
authors.initials: G
authors.lastname: di Renzo
authors.affiliation: 1] Division of Pharmacology, Department of Neuroscience, Reproductive and Odontostomatologic Sciences, School of Medicine, "Federico II" University of Naples, Naples, Italy [2] Istituto di Ricovero e Cura a Carattere Scientifico SDN, Naples, Italy.
authors.forename: Lucio
authors.initials: L
authors.lastname: Annunziato
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D057846:Cell-Penetrating Peptides / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D006224:Cricetinae; D015870:Gene Expression; D017136:Ion Transport; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009206:Myocardium / Q000378:metabolism; D018408:Patch-Clamp Techniques; D010455:Peptides / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D017434:Protein Structure, Tertiary; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D019831:Sodium-Calcium Exchanger / Q000819:agonists / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D057846:Cell-Penetrating Peptides; D010455:Peptides; D011993:Recombinant Fusion Proteins; C110927:Slc8a2 protein, rat; C491102:Slc8a3 protein, rat; D019831:Sodium-Calcium Exchanger; C110374:sodium-calcium exchanger 1; C066745:exchanger inhibitory peptide; D012964:Sodium; D002118:Calcium