Genome-wide identification of target genes for transcription factor BR-C in the silkworm,Bombyx mori

Transcription factor Broad Complex(BR-C)is an ecdysone primary response gene in insects and participates in the regulation of insect growth and development.In this study,we performed a genome-wide identification of BR-C target genes in silkworm(Bombyx mori)using chromatin immunoprecipitation followed by high-throughput sequencing(ChIP-seq).As a result,a total of 1006 BR-C ChIP peaks were identified,and 15%of peaks were located in the promoter regions of 133 protein-coding genes.Functional annotation revealed that these ChIP peak-associated genes,as potential BR-C targets,were enriched in pathways related to biosynthetic process,metabolic process,and development.Transcriptome analysis and quantitative real-time polymerase chain reaction(PCR)examination revealed that developmental changes in expression patterns of a portion of potential BR-C targets,including HR96 and GC-otl,were similar to those of BR-C.ChIP-PCR examination confirmed that BR-C could directly bind to the promoters of potential targets.Further,dual luciferase assays demonstrated that HR96 promoter activity was significantly upregulated following BR-C overexpression,and this upregu-lation was abolished when the binding motif in the promoter was truncated.This study will be helpful for deciphering the regulatory roles of BR-C during insect growth and development.