Integrated Transcriptomic and Proteomic Analyses Suggest the Participation of Endogenous Protease Inhibitors in the Regulation of Protease Gene Expression in Helicoverpa armigera

Abstract

Insects adapt to plant protease inhibitors (PIs) present in their diet by differentially regulating multiple digestive proteases. However, mechanisms regulating protease gene expression in insects are largely enigmatic. Ingestion of multi-domain recombinant protease inhibitor-7 (CanPI-7) arrests growth and development of (Lepidoptera: Noctuidae). Using RNA sequencing and proteomic analysis, we examined the response of larvae fed on recombinant CanPI-7 at different time intervals. Here, we present evidence supporting a dynamic transition in protease expression on CanPI-7 feeding with general down-regulation of protease genes at early time points (0.5 to 6 h) and significant up-regulation of specific trypsin, chymotrypsin and aminopeptidase genes at later time points (12 to 48 h). Further, coexpression of endogenous PIs with several digestive protease genes were apparent. In addition to the differential expression of endogenous PIs, we also observed a distinct novel isoform of endogenous PI in CanPI-7 fed larvae. Based on present and earlier studies, we propose potential mechanism of protease regulation in and subsequent adaptation strategy to cope with anti-nutritional components of plants.

A spatiotemporal atlas of the lepidopteran pest Helicoverpa armigera midgut provides insights into nutrient processing and pH regulation

“…Similar results were found for trypsins and chymotrypsins, which showed individual members of each family being up to > 25 fold up or downregulated depending on the gene in question. A similar transcription pattern in trypsins and chymotrypsins was previously [ 31 ] found following feeding with protein inhibitors. While not a primary focus of this study, a more detailed functional investigation of these digestive enzymes would be useful in order to ascertain whether these changes are adaptive.…”

“…GO term overrepresentation analysis (Table S6) showed that genes commonly overexpressed in the midgut of all larval stages are related to digestive functions such as lipid metabolism (GO:0006629) and proteolysis (GO:0006508). This finding was also observed in the stink bug N. viridula, and is commonplace among insects as it has been proven that they play an important role in the breakdown of proteins in the ingested food [17,30,31].…”

Expression of Cocculus hirsutus trypsin inhibitor promotes endogenous defensive response against Helicoverpa armigera and enhanced levels of antioxidants

“…Serine like proteinases expressed in early stages of larval growth is predominantly sensitive to PIs than the once expressed in the later stages of growth. Therefore, the larval growth and mortality rates depend on the stage of the larval growth and the effectiveness of the PIs resulting in delay of mortality rate of H. armigera (Bhattacharjee et al, 2010;Lomate et al, 2018;Chikate et al, 2013). These findings indicated that ingestion of transgenic leaves expressing ChTI at early stages of larval growth could control the lepidopteran population effectively.…”

Intestinal proteolytic profile changes during larval development of Anticarsia gemmatalis caterpillars

“…Thus, serine protease was the main protease class expressed in the fifth instar. High cysteine protease activities have already been detected in studies involving young larvae of Lepidoptera (Liu et al, ; Senthil‐Nathan, ) as well as the control of the gene expression of these enzymes, showing that there is an increase in the synthesis of serine proteases rather than the decrease of cysteine proteases in Tribolium castaneum (Lomate et al, ).…”