Functional characterization of five different PRXamide receptors of the red flour beetle Tribolium castaneum with peptidomimetics and identification of agonists and antagonists

Abstract

The neuropeptidergic system in insects is an excellent target for pest control strategies. One promising biorational approach is the use of peptidomimetics modified from endogenous ligands to enhance biostability and bioavailability. In this study, we functionally characterized five different G protein-coupled receptors in a phylogenetic cluster, containing receptors for PRXamide in the red flour beetle Tribolium castaneum, by evaluating a series of 70 different peptides and peptidomimetics. Three pyrokinin receptors (TcPKr-A, -B, and –C), cardioacceleratory peptide receptor (TcCAPAr) and ecdysis triggering hormone receptor (TcETHr) were included in the study. Strong agonistic or antagonistic peptidomimetics were identified, and included beta-proline (β3P) modification of the core amino acid residue proline and also a cyclo-peptide. It is common for a ligand to act on multiple receptors. In a number of cases, a ligand acting as an agonist on one receptor was an efficient antagonist on another receptor, suggesting complex outcomes of a peptidomimetic in a biological system. Interestingly, TcPK-A was highly promiscuous with a high number of agonists, while TcPK-C and TcCAPAr had a lower number of agonists, but a higher number of compounds acting as an antagonist. This observation suggests that a target GPCR with more promiscuity will provide better success for peptidomimetic approaches. This study is the first description of peptidomimetics on a CAPA receptor and resulted in the identification of peptidomimetic analogs that demonstrate antagonism of CAPA ligands. The PRXamide receptor assays with peptidomimetics provide useful insights into the biochemical properties of receptors.

Characterization of a β-Adrenergic-Like Octopamine Receptor in the Oriental Fruit Fly, Bactrocera dorsalis (Hendel)

“…At the same time, the empty pcDNA3.1 vector was transfected in HEK-293 cells as a negative control. The methods for transient expression of BdOctβR1 in HEK-293 cells and procedures for the assays were followed as previously described [41,42,43,44]. Thirty hours after the transfection, the cells were collected and preincubated with 1% GloSensor substrate in HEK-293 cells (Invitrogen) before the test.…”

Assessment of neuropeptide binding sites and the impact of biostable kinin and CAP2b analogue treatment on aphid (Myzus persicae and Macrosiphum rosae) stress tolerance

“…The GPCRs of this ligand group form a homologous cluster, suggesting co‐evolution of ancestrally related ligand‐receptor partners. As a result, some cross activity by analogues of the ligand sub‐groups with respective, recombinant receptors has been observed . For this reason, certain PK analogues that have previously demonstrated cross activity on recombinant CAPA receptors of Tribolium castaneum have been included in this study.…”

Agonist-mediated activation of Bombyx mori diapause hormone receptor signals to extracellular signal-regulated kinases 1 and 2 through Gq-PLC-PKC-dependent cascade

“…The DH receptor (DHR) exhibits a high level of similarity to the receptors of mammalian neuromedin U and other insect FXPRLa peptides (Homma et al, 2006). Subsequently, the DHRs were cloned from the corn earworm, Helicoverpa zea and the red flour beetle, Tribolium castaneum (Jiang et al, 2014b(Jiang et al, , 2015Zhang et al, 2014). The DHR has been found to be abundantly expressed in the ovaries during the pupal-adult development of B. mori.…”