Identification and characterization of adipokinetic hormone and its receptor in bumble bee queens, Bombus lantschouensis

Abstract

Adipokinetic hormone (AKH) and its receptor (AKHR) are crucial for energy homeostasis in insects, while their identification and functional characterization are controversial in bee species since the transition of energy storage from the solitary to the eusocial groups. As the primitively eusocial bee species, the bumble bee is an ideal organism for the evolution analysis of AKH and AKHR. In this current study, the identification and characterization of AKH of Bombus lantschouensis (Bomla_AKH) and its receptor (Bomla_AKHR) in queens exhibit that both Bomla_AKH and Bomla_AKHR are highly conserved with their counterparts in Bombus terrestris and Bombus impatiens. Notably, the alternative splicing that takes place with Bomla_akhr results in two putative proteins representing the amino and carboxyl fragments of Bomla_AKHR, respectively. Furthermore, the Bomla_akh expresses in the brain (with corpora cardiaca and corpora allata), while the Bomla_akhr expresses in the fat body and/or ovary depending on the specific development phase. Although the detailed mechanisms remain to be clarified, we can infer that the two putative proteins encoded by the splice mutant might participate in the functional regulation of Bomla_akhr in response to diverse demands in different tissues. The functional characterization and subcellular localization shows that the activation of Bomla_AKHR is AKH dose-dependent. Unfortunately, the response is too weak to do further signaling analysis, which might be due to the poor cytomembrane localization. Meanwhile, the activation mechanisms of Bomla_AKHR might be different from AKHRs of other insect species.

Keywords:

• Adipokinetic hormone
• Adipokinetic hormone receptor
• Bombus lantschouensis
• bumble bee queen
• alternative splicing
• G protein-coupled receptor

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work is supported financially by Beijing Natural Science Foundation (6174051), Agricultural Science and Technology Innovation Program (CAAS-ASTIP-2015-IAR) and the China Agriculture Research System (CARS-45).