An insect trypsin-like serine protease as a target of microRNA: Utilization of microRNA mimics and inhibitors by oral feeding

• Published in: Insect biochemistry and molecular biology 2013-04, Vol.43 (4), p.398-406
• Main Authors: Jayachandran, Balachandran, Hussain, Mazhar, Asgari, Sassan
• Format: Article
• Language: English
• Subjects: Animals; Base Sequence; Feeding Behavior; Female; Helicoverpa armigera; Inhibitor; Insect Proteins - genetics; Insect Proteins - metabolism; Larva - enzymology; Larva - genetics; Larva - physiology; Male; MicroRNA; MicroRNAs - genetics; MicroRNAs - metabolism; Mimic; Molecular Sequence Data; Moths - enzymology; Moths - genetics; Moths - growth & development; Moths - physiology; Pest Control, Biological - methods; RNA Interference; Serine Endopeptidases - genetics; Serine Endopeptidases - metabolism; Trypsin-like serine protease
• ISSN: 0965-1748; 1879-0240
• DOI: 10.1016/j.ibmb.2012.10.004

MicroRNAs (miRNAs) are non-coding small RNAs (18–25 nt) that play crucial roles in various biological processes, including development, as gene regulators. In this study, we identified a miRNA, har-miR-2002b, that is specifically expressed during larval stages of Helicoverpa armigera (cotton bollworm). For the first time, we explored the possibility of utilizing synthetic inhibitor and mimic of a miRNA by oral feeding and confirmed that the inhibitor and mimic can successfully inhibit/oversupply har-miR-2002b in H. armigera larvae. Bioassays by oral feeding indicated 70% reduction in fecundity and 40% larval mortality in the presence of har-miR-2002b mimic. In addition, a large proportion of those larvae that made it to the pupal stage were deformed and only few moths emerged from them. This implied an important role of har-miR-2002b in larval development and adult fecundity. A trypsin-like serine protease (Ha-TLP) was identified as a target of har-miR-2002b. In vivo and in vitro studies revealed that in the presence of the miRNA mimic Ha-TLP transcript/protein levels and enzyme activity were significantly reduced. In contrast, inhibition of har-miR-2002b led to significant up-regulation of Ha-TLP transcript levels. This is the first study which shows the potential of utilization of miRNA mimics and inhibitors in pest control by targeting specific insect genes. [Display omitted] ► An insect microRNA (miRNA) targets a trypsin-like serine protease. ► Oral feeding of the synthetic miRNA mimic reduced survival, growth and fecundity. ► miRNA mimics/inhibitors remained functional through oral feeding and reduced/increased the serine protease transcript levels. ► miRNA mimics/inhibitors can be utilized by oral feeding to study miRNA-target interactions.