O papel do receptor de lipoforina na fisiologia do barbeiro Rhodnius prolixus

Abstract

Lipids are essential for living organisms, primarily acting as structural molecules in cell membranes and as a source of energy. Insects can acquire lipids through feeding or de novo synthesis. Lipophorin is a lipoprotein present in insects and is responsible for transporting diverse lipids between organs through the hemolymph. The mechanisms regulating this transport still need to be better understood. However, lipophorin receptors (LpR) have been identified in various insect species and are present in the plasma membrane of several organs belonging to the low-density lipoprotein receptor superfamily. In this study, the kissing bug Rhodnius prolixus was used as a model to investigate the role of the RpLpR gene in its physiology. The RpLpR gene had been previously annotated in the kissing bug genome, and phylogenetic analyses showed that the kissing bug has only one copy of this gene. The RpLpR gene was expressed in all insect organs, and its expression significantly decreased in the fat body after blood meal. Adult females were injected with different doses of dsRNA to assess the efficacy of RpLpR gene knockdown in R. prolixus. There was a significant decrease in gene expression with the 0.1 μg dose. Gene knockdown did not affect insect survival or weight. However, a significant decrease in hatching rate and severe deformations in the few nymphs that hatched were observed. Furthermore, a decrease in vitellogenin expression was also observed after gene knockdown, demonstrating the importance of the LpR in insect reproduction. On the other hand, the results indicate that there was no change in the amount and composition of fat stored in organs, and no changes were found in the transfer of fatty acids from lipophorin to tissues, indicating that RpLpR may not be the main responsible of lipid transfer from lipophorin to organs. Phylogenetic analysis revealed other genes similar to LDL receptors in R. prolixus, possibly involved in this mechanism. These findings underscore the importance of the lipophorin receptor in insect physiology and pave the way for further investigations into how lipophorin delivers lipids to the tissues of the kissing bug.