Niemann-Pick type C1 regulates cholesterol transport and metamorphosis in silkworm, Bombyx mori (Dazao)

NPC1 is a large glycoprotein with 13 transmembrane-spanning domains, which plays a crucial biological role in cholesterol transport and metamorphosis of animals. However, the physiological functions of this gene have rarely been elucidated in insects. Here, we isolated the NPC1 gene from Bombyx mori (BmNPC1), sequenced and evaluated its physiological functions. BmNPC1 comprised of 3702 bp open reading frame, encoding a protein of 1233 amino acid residues. The recombinant protein was expressed, and anti-BmNPC1 antibodies were synthesized. Immunofluorescence assay revealed that BmNPC1 protein localized in the cytoplasm of the cells. The qRT-PCR analysis showed that BmNPC1 expression was most significant in the testis, followed by the malpighian tubules, hemocytes, and ovary. The knockdown of BmNPC1 by double-stranded RNA caused the accumulation of cholesterol in the cells. Furthermore, suppression of this gene influenced the expression of ecdysone-responsive genes and also prevented the molting in B. mori (Dazao) larvae. Overall, BmNPC1 may have different biological roles in the physiology of silkworm, B. mori (Dazao), since it regulates the cholesterol transport and molting process.