Molecular characterization and RNA interference analysis of vitellogenin receptor from Nilaparvata lugens (Stal)

Vitellogenin receptors (VgRs), members of the low-density lipoprotein receptor (LDLR) superfamily, are responsible for taking vitellogenin (Vg) into developing oocytes. Here the first full-length VgR cDNA from a hemipteran insect, the brown planthopper (Nilaparvata lugens), was cloned and sequenced. The complete mRNA sequence was 6174 bp in length with an open reading frame (ORF) of 5796 bp encoding 1931 amino acid residues. N. lugens VgR (NIVgR) contained two ligand-binding domains with five LDLR Class A cysteine-rich repeats in the first domain and eight in the second domain, which was similar to other insect VgRs. NIVgR was specifically expressed in the ovary, and the mRNA level started to increase after adult female emergence, with a peak on day 7 in the adult stage, and then declined. Western blot analysis of NIVgR protein revealed an ovary-specific expression pattern, which was consistent with NIVgR transcript detection. Injection with NIVgR double-stranded RNA (dsRNA) significantly disturbed NIVgR, which led to a decrease in NIVg protein content in the ovaries, an accumulation of NIVg protein in the hemolymph, the arrested development of ovaries, and the failure of insects to reproduce. Besides, NIVgR expression was significantly upregulated after the topical application of juvenile hormone (JH) III. These results suggest that VgR is critical for Vg uptaking of oocytes and it plays an important role in insect fecundity. (C) 2015 Elsevier Ltd. All rights reserved.