RT Journal Article
SR Electronic
T1 Elucidation of Vasoactive Intestinal Peptide Pharmacophore for VPAC<sub>1</sub> Receptors in Human, Rat, and Guinea Pig
JF Journal of Pharmacology and Experimental Therapeutics
JO J Pharmacol Exp Ther
FD American Society for Pharmacology and Experimental Therapeutics
SP 37
OP 50
DO 10.1124/jpet.301.1.37
VO 301
IS 1
A1 Igarashi, Hisato
A1 Ito, Tetsuhide
A1 Hou, Wei
A1 Mantey, Samuel A.
A1 Pradhan, Tapas K.
A1 Ulrich, Charles D.
A1 Hocart, Simon J.
A1 Coy, David H.
A1 Jensen, Robert T.
YR 2002
UL http://jpet.aspetjournals.org/content/301/1/37.abstract
AB Vasoactive intestinal peptide (VIP) is a neurotransmitter involved in a number of pathological and physiological processes. VIP is rapidly degraded and simplified stable analogs are needed. VIP's action was extensively studied in rat and guinea pig. However, it is largely unknown whether its pharmacophore in these species resembles human. To address this issue we investigated the VIP pharmacophore for VPAC1 (the predominant receptor subtype in cancers and widely distributed in normal tissues) by using alanine andd-amino acid scanning. Interaction with rat, guinea pig, and human VPAC1 was assessed using transfected Chinese hamster ovary (CHO) and PANC1 cells and cells possessing native VPAC1. Important species differences existed in the VIP pharmacophore. The human VPAC1 expressed in CHO cells, which were used almost exclusively in previous studies, differed markedly from the native VPAC1 in T47D cells. The most important amino acids for determining affinity are His1, Asp3, Phe6, Arg12, Arg14, and Leu23. Ser2, Asp8, Asn9, Thr11, Val19, Asn24, Ser25, Leu27, and Asn28 are not essential for high-affinity interaction/activation. [Ala2,8,9,11,19,24,25,27,28]VIP, which contained 11 alanines, was synthesized and it was equipotent to VIP at VPAC1 receptors in all species and was metabolically stable. Our results show in any design of simplified VIP analogs for VPAC1 it will be important to consider species differences and it is essential to use transfected systems that reflect the native receptor's pharmacophore. Last, with our results a simplified, metabolically stable VIP analog was identified that should be useful as a prototype for design of selective agonists/antagonists that could be useful therapeutically. U.S. Government