|Bravo Castillo, Paula|
|Nachman, Ronald - Ron|
Submitted to: General and Comparative Endocrinology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/6/2013
Publication Date: 12/1/2013
Citation: Yang, Y., Bajracharya, P., Bravo Castillo, P., Nachman, R.J., Pietrantonio, P. 2013. Molecular and functional characterization of the first tick CAP2b (periviscerokinin) receptor from Rhipicephalus (Boophilus) microplus. General and Comparative Endocrinology. 194:142-151. Interpretive Summary: Insect pests have developed resistance to several conventional pesticides, and new approaches are needed for pest management. Although neuropeptides (short chains of amino acids) serve as potent messengers in insects to regulate vital functions, the neutopeptides hold little promise as pest control agents because they can be degraded in the target pest. New, selective control agents may be developed by designing mimics of these neuropeptides that resist degradation and either inhibit or over-stimulate critical neuropeptide-regulated life functions. Research was conducted that, for the first time, characterized the active site of the CAP2b neuropeptide in a tick, specifically an important disease vector known as the cattle fever tick. Neuropeptides of the CAP2b class regulate the critical process of water balance in insects, and this research will aid in the discovery of the precise physiological role they play in ticks. The discoveries revealed in this paper will eventually aid in the design of neuropeptide-like compounds capable of disrupting critical life functions regulated by CAP2b neuropeptides in tick pests. The work brings us one step closer to the development of practical neuropeptide-like substances that will be effective in controlling tick pests in an environmentally-friendly fashion.
Technical Abstract: The cDNA of the receptor for CAP2b/periviscerokinin (PVK) neuropeptides, designated Rhimi-CAP2b-R, was cloned from synganglia of tick Rhipicephalus (Boophilus) microplus. This receptor is the ortholog of the insect CAP2b/PVK receptor, as concluded from analyses of the predicted protein sequence, phylogenetics and functional expression. Expression analyses of synganglion and ovary revealed Rhimi-CAP2b-R transcripts. The expression in mammalian cells of the open reading frame of Rhimi-CAP2b-R cDNA fused with a hemagglutinin tag at the receptor N-terminus was confirmed by immunocytochemistry. In a calcium bioluminescence assay the recombinant receptor was activated by the tick Ixodes scapularis CAP2b/PVK and a PVK analog with EC50s of 64 nM and 249 nM, respectively. Tick pyrokinins were not active. This is the first report on the functional characterization of the CAP2b/PVK receptor from any tick species which will now permit the discovery of the physiological roles of these neuropeptides in ticks, as neurohormones, neuromodulators and/or neurotransmitters.