A mosquito entomoglyceroporin, Aedes aegypti AQP5, participates in water transport across the Malpighian tubules of larvae.

The mosquito Aedes aegypti is the primary vector for arboviral diseases such as Zika fever, dengue fever, chikungunya and yellow fever. The larvae reside in hypo-osmotic freshwater habitats, where they face dilution of their body fluids from osmotic influx of water. The Malpighian tubules help maintain ionic and osmotic homeostasis by removing excess water from the hemolymph; however, the transcellular pathway for this movement remains unresolved. Aquaporins are transmembrane channels thought to permit transcellular transport of water from the hemolymph into the Malpighian tubule lumen. Immunolocalization of A.aegypti aquaporin 5 (AaAQP5) revealed expression by Malpighian tubule principal cells of the larvae, with localization to both the apical and basolateral membranes. Knockdown of AaAQP5 with double-stranded RNA decreased larval survival, reduced rates of fluid, K+ and Na+ secretion by the Malpighian tubules, and reduced Cl- concentrations in the hemolymph. These findings indicate that AaAQP5 participates in transcellular water transport across the Malpighian tubules of larval Aaegypti where global AaAQP5 expression is important for larval survival.