Juvenile hormone mediates lipid storage in the oocytes of Dipetalogaster maxima. (June 2021)

• Record Type: Journal Article
• Authors: Ramos, Fabian O.; Leyria, Jimena; Nouzova, Marcela; Fruttero, Leonardo L.; Noriega, Fernando G.; Canavoso, Lilian E.
• Is Part Of: Insect biochemistry and molecular biology. Volume 133(2021)
• Publication Date: 2021-06
• Subjects: Lipophorin -- Triatomine -- Oogenesis -- Juvenile hormone -- Lipid metabolism -- Endocytic receptors; Insect biochemistry -- Periodicals; Insects -- Physiology -- Periodicals; Insects -- Molecular aspects -- Periodicals; Biochemistry -- Periodicals; Insectes -- Biochimie -- Périodiques; Insectes -- Composition -- Périodiques; Insectes -- Physiologie -- Périodiques; Insectes -- Aspect moléculaire -- Périodiques; Biochimie -- Périodiques; Biochemistry; Insect biochemistry; Insects -- Molecular aspects; Insects -- Physiology; Periodicals; 572.8157
• DOI: 10.1016/j.ibmb.2020.103499
• Languages: English
• ISSNs: 0965-1748

Abstract

Abstract: Triatomines are vectors of Chagas disease and important model organisms in insect physiology. "Kissing bugs" are obligatory hematophagous insects. A blood meal is required to successfully complete oogenesis, a process primarily controlled by juvenile hormone (JH). We used Dipetalogaster maxima as an experimental model to further understand the roles of JH in the regulation of vitellogenesis and oogenesis. A particular focus was set on the role of JH controlling lipid and protein recruitment by the oocytes. The hemolymph titer of JH III skipped bisepoxide increased after a blood meal. Following a blood meal there were increased levels of mRNAs in the fat body for the yolk protein precursors, vitellogenin (Vg) and lipophorin (Lp), as well as of their protein products in the hemolymph; mRNAs of the Vg and Lp receptors (VgR and LpR) were concomitantly up-regulated in the ovaries. Topical administration of JH induced the expression of Lp/LpR and Vg/VgR genes, and prompted the uptake of Lp and Vg in pre-vitellogenic females. Knockdown of the expression of LpR by RNA interference in fed females did not impair the Lp-mediated lipid transfer to oocytes, suggesting that the bulk of lipid acquisition by oocytes occurred by other pathways rather than by the endocytic Lp/LpR pathway. In conclusion, our results strongly suggest that JH signaling is critical for lipid storage in oocytes, by regulating Vg and Lp gene expression in the fat body as well as by modulating the expression of LpR and VgR genes in ovaries. Graphical abstract: Image 1 Highlights: The titer of JH III skipped bisepoxide increased after a blood meal in D. maxima. Levels of Lp/LpR and Vg/VgR positively correlated with JH titers during oogenesis. JH treatment stimulated Vg/VgR and Lp/LpR expression in unfed females. Precocene II decreased JH titer and impaired Vg expression. Knockdown of LpR decreased Lp uptake but did not impair lipid transfer to oocytes.