Clathrin-dependent endocytosis is associated with RNAi response in the western corn rootworm, Diabrotica virgifera virgifera LeConte

The cellular uptake of dsRNA after dietary exposure is critical for RNAi efficiency; however, the mechanism of its uptake in many insects remains to be understood. In this study, we evaluated the roles of the endocytic pathway genes Clathrin heavy chain (Chc), Clathrin adaptor protein AP50, ADP ribosylation factor-like 1 (Arf72A), Vacuolar H(+) ATPase 16 kDa subunit (Vha16), and small GTPase Rab7 and putative sid-1-like genes (silA and silC) in RNAi response in western corn rootworm (WCR) using a two-stage dsRNA exposure bioassay. Silencing of Chc, Vha16, and AP50 led to a significant decrease in the effects of laccase2 dsRNA reporter, indicating that these genes are involved in RNAi response. However, the knockdown of either Arf72A or Rab7 did not suppress the response to laccase2 dsRNA. The silencing of the silC gene did not lead to a significant reduction in mortality or increase in the expression of V-ATPase A reporter. While the silencing of the silA gene significantly decreased insect mortality, significant changes in V-ATPase A expression were not detected. These results suggest that clathrin-dependent endocytosis is a biological mechanism that plays an important role during RNAi response in WCR adults. The fact that no definitive support for the roles of silA or silC in RNAi response was obtained support the idea that RNAi response varies greatly in different insect species, demanding additional studies focused on elucidating their involvement in this mechanism.