Expression of transcripts encoding gap junctional proteins (innexins) in the yellow fever mosquito, Aedes aegypti

Gap junctions mediate direct intercellular communication by forming channels through which small molecules and/or ions can pass. Connexins, the proteins that form vertebrate gap junctions, are well studied and are known to contribute to neuronal, muscular and epithelial physiology. Innexins, the gap junctional 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; hereafter Aedes). This mosquito is of particular interest because it is a vector of several important arboviruses (e.g., yellow, dengue, and chikungunya fevers). Previous work in Aedes has found evidence for the expression of four innexin genes (innexins 1, 2, 3, and 7) in the Malpighian tubules of adult females. In the present study, we cloned the full-length cDNAs of these four innexins. Each transcript encodes a putative innexin consisting of four transmembrane segments flanked by intracellular NH₂-terminal and COOH-terminal domains. We also performed semi-quantitative PCR on adult Aedes females to characterize innexin gene expression in the head, thoracic and abdominal body walls, midgut, Malpighian tubules, and hindgut. Notably, we found that the expression of innexin 4 is limited to the thoracic and abdominal body walls, and the expression of innexin 7 is highly enriched in the midgut, which suggests that these genes may perform tissue-specific functions. Supported by NIH R03DK090186 to PMP.