Hillyer Lab News
Hillyer Lab News
Article characterizing the biology of Anopheles gambiae Kir1 is published in IBMB
Thursday, May 22, 2014
Inward rectifier potassium (Kir) channels play essential roles in regulating diverse physiological processes. In the yellow fever mosquito, Aedes aegypti, pharmacologically inhibiting Kir1 using a small-molecule antagonist reduces urine output, disrupts K+ homeostasis and leads to a flightless or dead phenotype within 24 h of treatment, suggesting that Kir1 is essential for proper Malpighian tubule physiology. However, the biology of Kir channels in the African malaria mosquito, Anopheles gambiae, remained unexplored.
In this study we identified the members of the Anopheles gambiae Kir gene family and began to explore their expression, function, pharmacology, and integrative physiology. Most notably, we found that expression of A. gambiae Kir1 is enriched in the ovaries and that RNAi-mediated knockdown of Kir1 decreases the number of eggs laid by female mosquitoes. Specifically, in this paper we:
1.Sequence the full length Anopheles gambiae Kir1 mRNA and show that it encodes a functional inward rectifier potassium channel.
2.Identify other members of the A. gambiae Kir gene family and perform a phylogenetic analysis.
3.Determine that A. gambiae Kir1 expression peaks during the pupal stage and is enriched in adult ovaries.
4.Show by means of RNA interference that silencing A. gambiae Kir1 does not impact mosquito survival after a blood meal but decreases mosquito fecundity.
This work is the product of a collaboration between the laboratories of Julián Hillyer (Department of Biological Sciences, Vanderbilt University), Jerod Denton (Department of Anesthesiology, Vanderbilt University) and Peter Piermarini (Department of Entomology, Ohio State University).
ARTICLE CITATION:
Raphemot, R., T.Y. Estévez-Lao, M.F. Rouhier, P.M. Piermarini, J.S. Denton, and J.F. Hillyer. 2014. Molecular and functional characterization of Anopheles gambiae inward rectifier potassium (Kir1) channels: A novel role in egg production. Insect Biochemistry and Molecular Biology. 51:10-19.
(PubMed) (See it in IBMB) (Email me for a pdf copy)
GRAPHICAL ABSTRACT:
ARTICLE ABSTRACT:
Inward rectifier potassium (Kir) channels play essential roles in regulating diverse physiological processes. Although Kir channels are encoded in mosquito genomes, their functions remain largely unknown. In this study, we identified the members of the Anopheles gambiae Kir gene family and began to investigate their function. Notably, we sequenced the A. gambiae Kir1 (AgKir1) gene and showed that it encodes all the canonical features of a Kir channel: an ion pore that is composed of a pore helix and a selectivity filter, two transmembrane domains that flank the ion pore, and the so-called G-loop. Heterologous expression of AgKir1 in Xenopus oocytes revealed that this gene encodes a functional, barium-sensitive Kir channel. Quantitative RT-PCR experiments then showed that relative AgKir1 mRNA levels are highest in the pupal stage, and that AgKir1 mRNA is enriched in the adult ovaries. Gene silencing of AgKir1 by RNA interference did not affect the survival of female mosquitoes following a blood meal, but decreased their egg output. These data provide evidence for a new role of Kir channels in mosquito fecundity, and further validates them as promising molecular targets for the development of a new class of mosquitocides to be used in vector control.
“Insect Biochemistry and Molecular Biology publishes original contributions and mini-reviews in the fields of insect biochemistry and insect molecular biology. Main interests areas are neurochemistry, hormone and pheromone biochemistry, enzymes and metabolism, hormone action and gene regulation, gene characterization and structure, pharmacology, immunology and cell and tissue culture.”