Submitted to: Molecular and Cellular Endocrinology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/21/2013
Publication Date: 5/28/2013
Citation: Choi, M.Y., Estep, A., Sanscrainte, N.D., Becnel, J.J., Vander Meer, R.K. 2013. Identification and expression of PBAN/diapause hormone and receptors from Aedes aegypti. Molecular and Cellular Endocrinology. 375: 113-120. Interpretive Summary: Aedes aegypti is the most important vector of the arboviruses that cause dengue hemorrhagic fever, yellow fever and chikungunya primarily because of its preference for obtaining blood meals from humans. As reported by the World Health Organization (WHO) the global incidence of dengue has grown dramatically in recent decades. Over 40% of the world’s population is at risk for dengue and there may be 50 – 100 million dengue infections worldwide every year. Control for Ae. aegypti has relied primarily on conventional insecticides but development of resistance to commonly used insecticides has resulted in a significant loss of efficacy. There is a need to develop new strategies for mosquito control using novel modes of action. One new strategy is the process of RNA interference (RNAi) to selectively silence critical gene transcripts in order to debilitate the mosquito and thus prevent disease transmission. The active ingredient is a double-stranded RNA (dsRNA) construct designed to silence genes that code critical proteins. One family of such proteins are the PBAN/pyrokinin peptides, which are known to be involved in critical physiological functions in all insects. Scientists from the Imported Fire Ant and Household Insects, and Mosquito and Fly Units at the Center for Medical, Agricultural and Veterinary Entomology, USDA, ARS, Gainesville, FL, have for the first time identified and characterized PBAN/pyrokinin peptides and their corresponding receptors from Ae. aegypti. These are key first steps needed to determine the physiological function(s) of PBAN/pyrokinin peptides in mosquitoes and to ultimately develop novel biologically-based mosquito suppression methods.
Technical Abstract: Neuropeptides control various physiological functions and constitute more than 90% of insect hormones. The pheromone biosynthesis activating neuropeptide (PBAN)/pyrokinin family is a major group of insect neuropeptides and is well conserved in Insecta. This family of peptides has at least two closely related G-protein-coupled receptors (GPCRs) activated by PBAN and diapause hormone (DH). They control multiple biological activities including pheromone production and diapause induction in moths. Beyond some moth species, the biological function(s) of PBAN/pyrokinin peptides are largely unknown although these peptides are found in all insects. In this study we identified and characterized PBAN/pyrokinin peptides and corresponding GPCRs from the mosquito, Aedes aegypti. Ae. aegypti PBAN mRNA encodes four putative peptides including PBAN and DH, and is expressed in female and male adults during all life stages. PBAN receptor (PBAN-R) and the DH receptor (DH-R) were functionally expressed and confirmed through binding assays with PBAN and DH peptides. These receptors are differentially expressed from eggs to adults with the relative gene expression of the PBAN-R strongly suppressed during the 4th instar larval (L4) and pupal (P1 – P2) stages despite a high PBAN mRNA expression in these stages. However, DH-R expression level is 4 - 10 times higher than the PBAN-R in the same period. These results suggest that DH-R is upregulated but PBAN-R is downregulated from the late larval stages through the pupal stage. Therefore, during these stages, the DH-R could be activated by DH action rather than PBAN since both peptides are produced from the same gene. This study provides the first step in determining the function(s) of the PBAN/pyrokinin peptides in mosquitoes and establishes data critical to the development of methods for disruption of these hormone actions as a novel strategy for mosquito control.