title: Development of a potent and selective GPR7 (NPBW1) agonist: a systematic structure-activity study of neuropeptide B.
abstract: Neuropeptide B (NPB) has been recently identified as an endogenous ligand for GPR7 (NPBW1) and GPR8 (NPBW2) and has been shown to possess a relatively high selectivity for GPR7. In order to identify useful experimental tools to address physiological roles of GPR7, we synthesized a series of NPB analogs based on modification of an unbrominated form of 23 amino acids with amidated C-terminal, Br(-)NPB-23-NH(2). We confirmed that truncation of the N-terminal Trp residue resulted in almost complete loss of the binding affinity of NPB for GPR7 and GPR8, supporting the special importance of this residue for binding. Br(-)NPB-23-NH2 analogs in which each amino acid in positions 4, 5, 7, 8, 9, 10, 12 and 21 was replaced with alanine or glycine exhibited potent binding affinity comparable to the parent peptide. In contrast, replacement of Tyr(11) with alanine reduced the binding affinity for both GPR7 and GPR8 four fold. Of particular interest, several NPB analogs in which the consecutive amino acids from Pro4 to Val(13) were replaced with several units of 5-aminovaleric acid (Ava) linkers retained their potent affinity for GPR7. Furthermore, these Ava-substituted NPB analogs exhibited potent agonistic activities for GPR7 expressed in HEK293 cells. Among the Ava-substituted NPB analogs, analog 15 (Ava-5) and 17 (Ava-3) exhibited potency comparable to the parent peptide for GPR7 with significantly reduced activity for GPR8, resulting in high selectivity for GPR7. These highly potent and selective NPB analogs may be useful pharmacological tools to investigate the physiological and pharmacological roles of GPR7.
authors.affiliation: Department of Metabolic Disorder Research, Tsukuba Research Institute, Banyu Pharmaceutical Co., Ltd., Okubo 3, Tsukuba, Ibaraki 300-2611, Japan.
authors.forename: Maki
authors.initials: M
authors.lastname: Kanesaka
authors.forename: Masao
authors.initials: M
authors.lastname: Matsuda
authors.forename: Atsushi
authors.initials: A
authors.lastname: Hirano
authors.forename: Kenichi
authors.initials: K
authors.lastname: Tanaka
authors.forename: Akio
authors.initials: A
authors.lastname: Kanatani
authors.forename: Shigeru
authors.initials: S
authors.lastname: Tokita
mesh_terms: D000595:Amino Acid Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D006801:Humans; D008969:Molecular Sequence Data; D009479:Neuropeptides / Q000737:chemistry* / Q000494:pharmacology*; D011869:Radioligand Assay; D043562:Receptors, G-Protein-Coupled / Q000819:agonists* / Q000235:genetics; D018013:Receptors, Neuropeptide / Q000819:agonists* / Q000235:genetics; D013329:Structure-Activity Relationship
chemical_list: C485722:NPBWR1 protein, human; D009479:Neuropeptides; D043562:Receptors, G-Protein-Coupled; D018013:Receptors, Neuropeptide; C495188:neuropeptide B