Basic helix-loop-helix (bHLH) domain of Methoprene-tolerant (Met) is required for juvenile hormone action in Aag-2 cell line

Juvenile hormone (JH) plays important roles in regulating the development and reproduction in insects. However, molecular mechanisms of JH action are not well understood. In the current study, we analyzed JH action through a candidate JH receptor Methoprene-tolerant (Met) in the yellow fever mosquito (Aedes aegypti) cell line Aag-2. The mRNA levels of JH-response genes AaKr-h1 are induced by JH III in these cells. RNA interference-aided knock-down in the expression of AaMet, reduced JH III induction of Aakr-h1 gene expression. In contrast over-expression of full length AaMet increased JH III induced expression of Aakr-h1 genes. Interestingly, AaMet lacking bHLH domain or a mutant AaMet with a single amino acid change in the DNA-binding domain fail to support JH III induction of Aakr-h1 expression. These data suggest that DNA-binding by AaMet is a key step in JH III induction of Aakr-h1 gene in Aag-2 cells.