|Nachman, Ronald - Ron|
Submitted to: Insect Molecular Biology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/7/2004
Publication Date: 1/21/2005
Citation: Pietrantonio, P.V., Jagge, C., Taneja-Bageshwar, S., Nachman, R.J., Barhoumi, R. 2005. The mosquito Aedes aegypti (L.) leucokinin receptor is a multiligand receptor for the three Aedes kinins. Insect Molecular Biology. 14:55-67. Interpretive Summary: Because of problems with the development of resistance to conventional pesticides, there is a critical need for new concepts and alternative approaches in controlling insect pests. The basic premise of this research is that neuropeptides (short chains of amino acids) serve as potent messengers in insects to regulate vital functions. Nevertheless, these neuropeptides in and of themselves hold little promise as pest control agents because of susceptibility to being degraded in the target pest, and inability to pass through the outside skin (cuticle) and/or digestive tract. We must design neuropeptide mimics that resist degradation by enzymes in the digestive tract and blood of pest insects and interact with the active site within the agricultural pest in such a way as to either over-activate or block critical, neuropeptide-regulated life functions. We report on the first isolation, identification and characterization of the active site for the myokinin class of neuropeptides from a mosquito; specifically Aedes aegypti, which is a carrier of disease in man and livestock. In mosquitoes the myokinins regulate water balance and digestion, critical life functions. This discovery will aid in the design of neuropeptide-like compounds capable of disrupting water balance and digestion in mosquitoes. The work brings us one step closer to the development of practical neuropeptide-like substances that will be effective in controlling pest insects in an environmentally friendly fashion.
Technical Abstract: A cDNA cloned from Aedes aegypti (L.) (Aedae) female Malpighian tubule (AY596453) encodes a 584 amino acid residue protein (65.2 kDa) predicted as a G protein coupled receptor and orthologue of the drosokinin receptor from Drosophila melanogaster and highly similar to the tick Boophilus microplus myokinin receptor (AF228521). Based on the similarity to this Aedes sequence, we also propose a correction for the Anopheles gambiae protein sequence EAA05450. When expressed in CHO-K1 cells, the Aedes receptor behaved as a multiligand receptor and functionally responded to concentrations = 1 nM of Aedae kinins 1'3, respectively, as determined by a calcium ioluminescence plate assay and single cell intracellular calcium measurements by confocal fluorescence cytometry. Estimates of EC50 values by the plate assay were 16.04 nM for Aedae-K-3, 26.6 nM for Aedae-K-2 and 48.8 nM for Aedae-K-1 and were statistically significantly different. These results suggest that the observed differences in physiologica responses to the three Aedes kinins in the Aedes isolated Malpighian tubule reported elsewhere could now be explained by differences in intracellular signaling events triggered by the different peptides on the same receptor and not necessarily due to the existence of various receptors for the three Aedes kinins.