Analysis of mechanism of functions mediated by receptors of arachodonate cascade

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In order to clarify the molecular actions of prostaglandins, it needs to clone their receptor cDNAs and studied the structures and functions of their receptors in expressed cells, and to examine the phenotypic appearance of their receptor knock-out mice. In this project, we have obtained the following results ; (1) we cloned at least 6 kinds (EP1, EP2, EP3, EP4, FP,IP) of mouse PG receptor cDNAs. (2) In expressed CHO cells, we examined the functional domains of PG receptor for binding sites and signaling via G protein coupling. (3) In EP3 receptor, we showed the hydrogen bonding interation of carbonyl residue of EP3 agonists and residue 309 arginine in 7th transmembrane domain of EP3 receptor is sufficient for the functional activation. (4) This interaction is essential for the activation of Gs and Gq but not Gi in EP3D receptor. (5) we have prepared some knock-out mice which are deficient in PGF (FP) receptor and EP2/EP4 receptors. (6) FP knock-out mice revealed the loss of delivery of growing fetus. The mechanism is supposed to be involved in the deficient of PGF action in the regression of corpus luteum. (7) We have been making EP2 and EP4 knock-out mice. EP4 knock-out mice has a severe phenotypic appearance, since they die during 1-2 days after birth because of the deficient function of vascular circulation.