title: The homeodomain transcription factors antennapedia and POU-M2 regulate the transcription of the steroidogenic enzyme gene Phantom in the silkworm.
abstract: The steroid hormone ecdysone, which controls insect molting and metamorphosis, is synthesized in the prothoracic gland (PG), and several steroidogenic enzymes that are expressed specifically in the PG are involved in ecdysteroidogenesis. In this study, we identified new regulators that are involved in the transcriptional control of the silkworm steroidogenic enzyme genes. In silico analysis predicted several potential cis-regulatory elements (CREs) for the homeodomain transcription factors Antennapedia (Antp) and POU-M2 in the proximal promoters of steroidogenic enzyme genes. Antp and POU-M2 are expressed dynamically in the PG during larval development, and their overexpression in silkworm embryo-derived (BmE) cells induced the expression of steroidogenic enzyme genes. Importantly, luciferase reporter analyses, electrophoretic mobility shift assays, and chromatin immunoprecipitation assays revealed that Antp and POU-M2 promote the transcription of the silkworm steroidogenic enzyme gene Phantom (Phm) by binding directly to specific motifs within overlapping CREs in the Phm promoter. Mutations of these CREs in the Phm promoter suppressed the transcriptional activities of both Antp and POU-M2 in BmE cells and decreased the activities of mutated Phm promoters in the silkworm PG. In addition, pulldown and co-immunoprecipitation assays demonstrated that Antp can interact with POU-M2. Moreover, RNA interference-mediated down-regulation of either Antp or POU-M2 during silkworm wandering not only decreased the ecdysone titer but also led to the failure of metamorphosis. In summary, our results suggest that Antp and POU-M2 coordinate the transcription of the silkworm Phm gene directly, indicating new roles for homeodomain proteins in regulating insect ecdysteroidogenesis.
authors.affiliation: From the State Key Laboratory of Silkworm Genome Biology and the Key Sericultural Laboratory of the Ministry of Agriculture, College of Biotechnology, Southwest University, Chongqing 400715, China.
authors.forename: Meng
authors.initials: M
authors.lastname: Meng
authors.affiliation: From the State Key Laboratory of Silkworm Genome Biology and the Key Sericultural Laboratory of the Ministry of Agriculture, College of Biotechnology, Southwest University, Chongqing 400715, China chengdj@swu.edu.cn.
authors.forename: Dao-Jun
authors.initials: DJ
authors.lastname: Cheng
authors.affiliation: From the State Key Laboratory of Silkworm Genome Biology and the Key Sericultural Laboratory of the Ministry of Agriculture, College of Biotechnology, Southwest University, Chongqing 400715, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Peng
authors.affiliation: From the State Key Laboratory of Silkworm Genome Biology and the Key Sericultural Laboratory of the Ministry of Agriculture, College of Biotechnology, Southwest University, Chongqing 400715, China.
authors.forename: Wen-Liang
authors.initials: WL
authors.lastname: Qian
authors.affiliation: From the State Key Laboratory of Silkworm Genome Biology and the Key Sericultural Laboratory of the Ministry of Agriculture, College of Biotechnology, Southwest University, Chongqing 400715, China.
authors.forename: Jia-Rui
authors.initials: JR
authors.lastname: Li
authors.affiliation: From the State Key Laboratory of Silkworm Genome Biology and the Key Sericultural Laboratory of the Ministry of Agriculture, College of Biotechnology, Southwest University, Chongqing 400715, China.
authors.forename: Dan-Dan
authors.initials: DD
authors.lastname: Dai
authors.affiliation: From the State Key Laboratory of Silkworm Genome Biology and the Key Sericultural Laboratory of the Ministry of Agriculture, College of Biotechnology, Southwest University, Chongqing 400715, China.
authors.forename: Tian-Lei
authors.initials: TL
authors.lastname: Zhang
authors.affiliation: From the State Key Laboratory of Silkworm Genome Biology and the Key Sericultural Laboratory of the Ministry of Agriculture, College of Biotechnology, Southwest University, Chongqing 400715, China xiaqy@swu.edu.cn.
authors.forename: Qing-You
authors.initials: QY
authors.lastname: Xia
mesh_terms: D000818:Animals; D051943:Antennapedia Homeodomain Protein / Q000235:genetics / Q000378:metabolism*; D012831:Bombyx; D019295:Computational Biology; D004440:Ecdysone / Q000737:chemistry; D018507:Gene Expression Regulation, Developmental; D015801:Helminth Proteins / Q000235:genetics / Q000378:metabolism*; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism*; D008675:Metamorphosis, Biological; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism*; D018978:Molting; D009154:Mutation; D017924:Nucleopolyhedroviruses / Q000235:genetics; D050809:POU Domain Factors / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D034622:RNA Interference; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D051943:Antennapedia Homeodomain Protein; D015801:Helminth Proteins; D018398:Homeodomain Proteins; D019476:Insect Proteins; D050809:POU Domain Factors; D014157:Transcription Factors; D004440:Ecdysone; D006899:Mixed Function Oxygenases
keywords: homeobox; phantom; protein-protein interaction; silkworm; steroidogenesis; steroidogenic enzyme; transcription regulation