The molecular physiology of gap junctions (innexins) in the mosquito Aedes aegypti: Integrating pharmacology and functional genetics

Gap junctions are intercellular channels that allow for direct communication between cells. These channels are made up of one of two evolutionarily distinct families of proteins, connexins in vertebrates or innexins in invertebrates. Connexins and innexins serve similar functions in embryogenesis and connexins have been implicated in many roles of tissue connectivity in adult vertebrates. The roles of innexins in adult invertebrates however are less well understood. Our previous work has demonstrated tissue dependent expression of innexins in Aedes aegypti that may be indicative of function. Here we examine physiological roles of innexins in the yellow fever mosquito, Aedes aegypti, via pharmacological and functional genetic approaches. Using three commercially available inhibitors of gap junctions, we find potent dose-dependent toxic effects when injected into the hemolymph of adult female mosquitoes, suggesting a general critical role of gap junctions in mosquito physiology. Moreover, these compounds inhibit the capacity of mosquitoes to excrete urine at diuretic rates, suggesting an important functional role in the excretory system. Using RNA interference, we will focus on the determining the functions of 1) innexin 3, which can be found in most tissues throughout the mosquito and 2) innexin 4, for which expression is restricted to the carcass (tissues including the cuticle, fat body and flight muscles) and ovaries of adult females. We hypothesize that the knockdown of innexin 3 will disrupt the excretory capacity and survival of adult female mosquitoes; and we hypothesize that the knockdown of innexin 4 will inhibit the fecundity of adult female mosquitoes.