Bombyx mori prothoracicostatic peptide receptor is allosterically activated via a G{alpha}i/o protein-biased signaling cascade by Drosophila sex peptide

In insects, molting and metamorphosis are strictly regulated by ecdysteroids. Ecdysteroid synthesis is positively or negatively controlled by several neuropeptides. The prothoracicostatic peptide BmPTSP, isolated from the larval brain of Bombyx mori, has been demonstrated to inhibit ecdysteroid synthesis in the prothoracic glands. More recently, the newly recognized B. mori receptor for Drosophila melanogaster sex peptide has been identified as a receptor for BmPTSP. However, details on the signaling pathways and physiological functions of this receptor have remained elusive. Here, we report the functional characterization of the BmPTSPR/SPR using both mammalian and insect cells. Synthetic DmSP shows the potential to inhibit forskolin or AKH-induced CRE-driven luciferase activity in a manner comparable to synthetic BmPTSP1. However, DmSP displayed a much lower activity in triggering Ca2+ mobilization and internalization than did BmPTSP1. Additionally, FAM fluorophore-labeled DmSP and BmPTSP3 were found to bind specifically to BmPTSPR/SPR. The binding of FAM-DmSP was displaced by unlabeled DmSP, but not by unlabeled BmPTSP1 and, vice versa, the binding of FAM-BmPTSP3 was blocked by unlabeled BmPTSP3, but not by unlabeled DmSP. Moreover, internalization assays demonstrated that BmPTSP1, but not DmSP, evoked recruitment of the Bombyx nonvisual arrestin, Kurtz, to the activated BmPTSPR/SPR in the plasma membrane. This was followed by induction of internalization. This sugg...

Source: BJ Signal - November 25, 2014 Category: Biochemistry Authors: X He, J Zang, H Yang, H Huang, Y Shi, C Zhu, N Zhou Tags: BJ Signal Source Type: research