Identification and characterization of GPCRs for Pyrokinin and CAPA peptides in the brown marmorated stink bug, Halyomorpha halys (Hemiptera: Pentatomidae)

Authors: AHN, SEUNG-JOON - Mississippi State University; Corcoran, Jacob; Vander Meer, Robert - Bob; Choi, Man-Yeon

Submitted to: Frontiers in Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/24/2020
Publication Date: 5/29/2020
Citation: Ahn, S., Corcoran, J., Vander Meer, R.K., Choi, M.Y. 2020. Identification and characterization of GPCRs for Pyrokinin and CAPA peptides in the brown marmorated stink bug, Halyomorpha halys (Hemiptera: Pentatomidae). Frontiers in Physiology. 11:559. https://doi.org/10.3389/fphys.2020.00559.
DOI: https://doi.org/10.3389/fphys.2020.00559

Interpretive Summary: The brown marmorated sink bug (BMSB), is an invasive pest from Asia and is currently found in most of the U.S. attacking ~170 hosts. Areas infested with BMSB have been growing steadily. BMSB causes severe damage in peach, apple, tomato, pepper, sweet corn, and row crops. Currently, the major control tool for BMSB management is chemical insecticides; there is a need for biological alternative approaches. Recent research has focused on finding unique physiological aspects of BMSB, that could be good targets to develop new control approaches. This study identified six G-protein coupled receptors (GPCRs), membrane bound receptors, and classified three GPCR types using functional expression, and their binding responsiveness to various neuropeptides from BMSB. Protein expression levels of each GPCRs were determined by two quantitative PCR methods in the central nervous system, midgut, Malpighian tubules like kidney, female ovary and male testis, and all life stages. Results provide critical evidence of insect ligand and receptor coevolution and paves the way to investigate biological functions of these neuropeptides in BMSB, which may serve as biological targets.

Technical Abstract: The brown marmorated stink bug, Halyomorpha halys, is an invasive hemipteran that causes significant economic losses to various agricultural commodities worldwide. Recently, the pyrokinin and capa genes and their corresponding neuropeptides were described in this species. Here we identified four GPCRs, two of which have two splice variants, and evaluated their responsiveness to neuropeptides in cell-based assays and expression levels by RT-PCR. Functional studies revealed that the H. halys pyrokinin receptor1 (HalhaPK-R1), especially the b variant, responded to the three pyrokinin 2 (PK2) type peptides (PK2-1, PK2-2 and PK2-3). RT-PCR experiments revealed that these receptors had little to no expression in any tissues tested including the whole body, central nervous system, midgut, Malpighian tubules, or reproductive organs of both males and females, suggesting that HalhaPK-R1s might lose their biological function in this organism. HalhaPK-R2 showed the strongest response to PK2 peptides and some response to pyrokinin 1 (PK1) type peptide (=DH, diapause hormone), and was expressed in all the tissues tested. HalhaPK-R3a & b responded broadly to both PK1 (=DH) and PK2 peptides, HalhaPK-R3b showed the strongest response to PK1 among six GPCRs. Their gene expression was restricted mostly to the central nervous system and Malpighian tubules. All PK receptors were dominantly expressed in the fifth nymph. HalhaCAPA-R responded specifically to CAPA-PVK peptides (PVK-1 and PVK-2) and was highly expressed in the Malpighian tubules with some expression in other tissues, and life stages. Our experiments deorphaned six GPCRs to the following peptide ligands: HalhaPK-R1a&b and HalhaPK-R2 for PK2 peptides, HalhaPK-R3a &b for PK1 (=DH) peptides, and HalhaCAPA-R for PVK peptides.