Establishment of a versatile cell line for juvenile hormone signaling analysis in Tribolium castaneum

The red flour beetle, Tribolium castaneum, has been widely used as a laboratory model for analyzing gene function. In this study, we established a novel cell line (Tc81) from T. castaneum embryos and validated the utility of this cell line by analyzing the juvenile hormone (JH) signaling pathway. In Tc81 cells, the Kruppel homolog 1 gene (Kr-h1), which is a JH-dependent repressor of insect metamorphosis, was rapidly induced by subnanomolar levels of JHs. Bioinformatics analysis and reporter assays identified 2 JH response elements (kJHREs) located in the region upstream of the transcription start site and in the first intron of Kr-h1. Furthermore, methoprene tolerant (Met) and steroid receptor co-activator (SRC) RNAi reduced JH-dependent induction of Kr-h1 transcripts and kJHRE-reporter activities. Thus, this novel Tc81 cell line is useful for the elucidation of JH signaling and is a promising tool for the functional analysis of genes by RNAi and reporter assays.