Gap junctions in the yellow fever mosquito, Aedes aegypti

Gap junctions (GJ) mediate direct intercellular communication by forming channels through which small molecules and/or ions can pass. Connexins, the proteins forming vertebrate GJ, are well studied and known to contribute to neuronal, muscular and epithelial physiology. Innexins, the GJ proteins of insects, have received substantially less investigative attention. The goal of this study was to characterize the molecular expression of the six innexin genes in the yellow fever mosquito Aedes aegypti; a vector of several medically important arboviruses. We first used RT-PCR to determine if the expression of innexins is dependent on the life stage of the mosquito.  All life stages express innexins 1, 2, 3, and 7.  Interestingly, the innexin gene ‘passover’ is expressed only in larval and pupal stages, and innexin 4 is expressed only in adult females.  We next used RT-PCR to determine if the expression of innexins is tissue dependent in adult female mosquitoes. Notably we found that 1) innexin 4 is expressed primarily in ovaries and the thoracic and abdominal body walls, and 2) innexin 7 is highly expressed in the gut. Lastly, we developed an antibody against innexin 3 to reveal its localization. We found that in the Malpighian tubules and hindgut, innexin 3 immunoreactivity localizes to intercellular boundaries of the epithelial cells. Our findings suggest that innexins have the potential to perform life-stage and/or tissue-specific functions in mosquitoes, which remain to be elucidated.  Supported by NIH R03DK090186.