Insulin-like peptides as multitaskers for successful reproduction in Rhodnius prolixus, a vector of Chagas disease

LEYRIA JIMENA

Queretaro

Conferencia; Biennial North American Society for Comparative Endocrinology; 2023

The blood-sucking hemipteran Rhodnius prolixus is one of the main vectors of Chagas disease, a neglected tropical disease that affects several million people worldwide. Consuming a blood meal is an event with a high epidemiological impact since after each feed, mated females can lay eggs that result in hundreds of offspring. Insulin-like peptides (ILPs) are peptide hormones that mediate metabolism, growth, lifespan and reproduction in vertebrates and invertebrates. We have used a combination of hormone treatments, gene expression analyses, hormone measurements, RNA interference (RNAi) and ex vivo experiments to investigate how insulin signaling is particularly important in defining the overall hormonal environment for egg production in R. prolixus. The results show that after a blood meal, insulin signaling interprets and responds to nutrient levels to coordinate egg production. The insulin tyrosine kinase pathway is activated to modulate the synthesis of yolk protein precursors (YPPs) in the fat body (the principal organ of intermediate metabolism in insects). In addition, the insulin signaling pathway modulates juvenile hormone (JH) synthesis and release from the corpus allatum, which stimulates egg growth, in part via YPPs and ecdysteroids, synthesised and released from the ovaries, and involved in egg laying as well. Recently, a new ILP named gonadulin was found to be highly expressed in the reproductive system of R. prolixus, particularly in the calyx, through which eggs move into the lateral oviducts at ovulation. Interestingly, we found that gonadulin works through a signaling pathway mediated by LGR3, a leucine-rich repeat-containing G protein-coupled receptors (LGRs) subfamily of G protein-coupled receptors, modulating movements of mature eggs through the calyx; thus, promoting ovulation. This study highlights the ability of ILPs to use different signaling pathways to promote a successful reproductive cycle, coordinating oogenesis, ovulation and oviposition. Understanding the physiological processes involved in reproduction in R. prolixus sheds light on potential targets for effective production of biopesticides by translational research, thereby controlling insect populations and transmission of the disease.