Ac His1 [D-Phe2, K15, R16, L27] VIP (3-7)/GRF (8-27) - a VPAC1 receptor antagonist: is an inverse agonist on two constitutively active truncated VPAC1 receptors

• Published in: Peptides (New York, N.Y. : 1980) N.Y. : 1980), 2004-11, Vol.25 (11), p.1943-1949
• Main Authors: VERTONGEN, Pascale, LANGLET, Christelle, LANGER, Ingrid, GASPARD, Nathalie, ROBBERECHT, Patrick
• Format: Article
• Language: English
• Subjects: Adenylyl Cyclases - metabolism; Amino Acid Sequence; Animals; Binding, Competitive; Biological and medical sciences; Cell receptors; Cell structures and functions; CHO Cells; Clone Cells; Cricetinae; Cricetulus; Fundamental and applied biological sciences. Psychology; Humans; Inhibitory Concentration 50; Iodine Radioisotopes; Ligands; Molecular and cellular biology; Molecular Sequence Data; Neuropeptide receptors; Peptides, Cyclic - pharmacology; Protein Conformation; Receptors, Vasoactive Intestinal Peptide - chemistry; Receptors, Vasoactive Intestinal Peptide - metabolism; Receptors, Vasoactive Intestinal Polypeptide, Type I; Recombinant Proteins - chemistry; Recombinant Proteins - metabolism; Transfection; Vasoactive Intestinal Peptide - chemical synthesis; Vasoactive Intestinal Peptide - chemistry; Vasoactive Intestinal Peptide - isolation & purification; Vasoactive Intestinal Peptide - pharmacology
• ISSN: 0196-9781; 1873-5169
• DOI: 10.1016/j.peptides.2004.06.001

C-terminally truncated human VPAC(1) receptors were constructed and stably transfected in Chinese hamster ovary (CHO) cells. Selected clones expressing comparable receptor densities were studied for ligand's binding properties, basal and stimulated adenylate cyclase activity. The wild-type (1-457) receptor served as reference. The binding properties of all the constructions were preserved. As judged by the intrinsic activity of the partial agonist Q(3)-VIP, the shortest receptors have a moderate impairment of the coupling efficacy to G(alpha s) protein. Cells expressing the VPAC(1) (1-436) and (1-441) truncated receptors had a two- to three-fold higher basal adenylate cyclase activity than those expressing the wild-type or the VPAC(1) (1-444), (1-433), (1-429), (1-421) and (1-398) receptor. The stimulatory effect of VIP and other agonist was preserved. This suggested that VPAC(1) (1-436) and (1-441) receptors had a constitutive activity. The selective VPAC(1) receptor antagonist Ac His(1) [D-Phe(2), K(15), R(16), L(27)] VIP (3-7)/GRF (8-27) reduced by 60% the basal activity with an EC(50) value of 3 nM comparable to its IC(50) value for binding. This agonist behaved thus like an inverse agonist on the constitutively active VPAC(1) receptors generated by C-terminal truncation and expressed in CHO cells.