Activation of the TOR Signalling Pathway by Glutamine Regulates Insect Fecundity

Abstract

The target of rapamycin (TOR) positively controls cell growth in response to nutrients such as amino acids. However, research on the specific nutrients sensed by TOR is limited. Glutamine (Gln), a particularly important amino acid involved in metabolism in organisms, is synthesised and catalysed exclusively by glutamine synthetase (GS), and our previous studies have shown that Gln may regulate fecundity in vivo levels of the brown planthopper (BPH) Nilaparvata lugens. Until now, it has remained unclear whether Gln activates or inhibits the TOR signalling pathway. Here, we performed the combined analyses of iTRAQ (isobaric tags for relative and absolute quantification) and DGE (tag-based digital gene expression) data in N.lugens at the protein and transcript levels after GS RNAi, and we found that 52 pathways overlap, including the TOR pathway. We further experimentally demonstrate that Gln activates the TOR pathway by promoting the serine/threonine protein kinase AKT and inhibiting the 5′AMP-activated protein kinase AMPK phosphorylation activity in the pest. Furthermore, TOR regulates the fecundity of N. lugens probably by mediating vitellogenin (Vg) expression. This work is the first report that Gln activates the TOR pathway in vivo.

Discovery and functional identification of fecundity‐related genes in the brown planthopper by large‐scale RNA interference

“…In Ni. lugens , promotion of AKT phosphorylation/activation activates the TOR signalling pathway, which regulates fecundity, probably by mediating Vg expression (Zhai et al ., ). Further careful analysis and correlation of Akt and CtBP expression in Ni.…”

“…In the second round of identifications, we confirmed that 12 of the annotated genes are fecundity‐related genes and identified three novel genes in the BPH (Figs . Three genes, fzy , Sxl and GS , have previously been reported to influence insect reproduction and fecundity (Hashiyama et al ., ; Van Doren, ; Zhai et al ., ; Sun et al ., ), consistent with the results of the present study. We also found that four annotated fecundity‐related genes, PK , StKR‐associated protein , Car and a Sox gene, regulate female fecundity in Ni.…”

Hemolymph protein profiles of subterranean termite Reticulitermes flavipes challenged with methicillin resistant Staphylococcus aureus or Pseudomonas aeruginosa

“…5B). The first principal component (PC1) differentiated P. aeruginosa -challenged and naïve termite hemolymph samples, and the second principal component (PC2) is a measure of enzymes involved in metabolism (glutamine synthetase 2) 26 , detoxification (glutathione S-transferase) 20 , cell migration (filamin A) 27 , and antibacterial defenses (c-type lysozyme 2) 28 .

Figure 5Hierarchical clustering analysis ( A ) and principle component analysis ( B ) based on 40 proteins significantly changed in abundances between P. aeruginosa -challenged and naïve termites within the dataset. ( A ) Both samples and proteins were clustered using Ward’s method, and with Pearson correlation as similarity metric.

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RNA Interference in Insect Vectors for Plant Viruses

“…In the same insect, RNAi of Bicaudal-C suggested its role in oogenesis and oocyte maturation [118]. In another study, silencing acyl-coenzyme A oxidase ( ACO ) [119,120] and glutamine synthetase ( GS ) [121] decreased the reproduction and population growth in BPH females, while knockdown of NIHsp90 by dsRNA injection reduced the survival and verified its role in thermotolerance [122]. Another study demonstrated the importance of β- N-acetylhexosaminidase gene family in BPH and the silencing of this gene caused molting failure and death [123].…”