期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2015
卷号：112
期号：15
页码：E1871-E1879
DOI：10.1073/pnas.1423204112
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：SignificanceJuvenile hormone (JH) controls many key processes during insect life cycles. Some of the effects of JH are mediated by a membrane-associated mechanism. In other circumstances, an intracellular JH receptor, methoprene-tolerant protein (MET), is activated upon binding of JH and directly regulates the expression of JH target genes. Here we use adult female mosquitoes as an example to demonstrate that both mechanisms are interconnected to coordinate hormonal responses. Our results indicate that the phospholipase C pathway is activated shortly after hormone exposure. Activation of this pathway induces phosphorylation of MET and profoundly increases the ability of MET to bind to JH target. This study establishes the link between the membrane-initiated JH signaling and the MET-mediated genomic action of JH. Juvenile hormone (JH) is a key regulator of a wide diversity of developmental and physiological events in insects. Although the intracellular JH receptor methoprene-tolerant protein (MET) functions in the nucleus as a transcriptional activator for specific JH-regulated genes, some JH responses are mediated by signaling pathways that are initiated by proteins associated with plasma membrane. It is unknown whether the JH-regulated gene expression depends on the membrane-mediated signal transduction. In Aedes aegypti mosquitoes, we found that JH activated the phospholipase C (PLC) pathway and quickly increased the levels of inositol 1,4,5-trisphosphate, diacylglycerol, and intracellular calcium, leading to activation and autophosphorylation of calcium/calmodulin-dependent protein kinase II (CaMKII). When abdomens from newly emerged mosquitoes were cultured in vitro, the JH-activated gene expression was repressed substantially if specific inhibitors of PLC or CaMKII were added to the medium together with JH. In newly emerged female mosquitoes, RNAi-mediated depletion of PLC or CaMKII considerably reduced the expression of JH-responsive genes, including the Kruppel homolog 1 gene (AaKr-h1) and the early trypsin gene (AaET). JH-induced loading of MET to the promoters of AaKr-h1 and AaET was weakened drastically when either PLC or CaMKII was inactivated in the cultured tissues. Therefore, the results suggest that the membrane-initiated signaling pathway modifies the DNA-binding activity of MET via phosphorylation and thus facilitates the genomic responses to JH. In summary, this study reveals an interplay of genomic and nongenomic signaling mechanisms of JH.
关键词：insect hormone ; development ; phospholipase C ; protein kinase ; transcription
