Homeodomain Protein Scr Regulates the Transcription of Genes Involved in Juvenile Hormone Biosynthesis in the Silkworm

• Published in: International journal of molecular sciences Vol. 16; no. 11; pp. 26166 - 26185
• Main Authors: Meng, Meng, Liu, Chun, Peng, Jian, Qian, Wenliang, Qian, Heying, Tian, Ling, Li, Jiarui, Dai, Dandan, Xu, Anying, Li, Sheng, Xia, Qingyou, Cheng, Daojun
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 02.11.2015; MDPI
• Subjects: Animals; Biosynthesis; Bombyx - genetics; Bombyx - metabolism; Bombyx mori; Chromosome Mapping; Gene Expression Regulation; Genes; Hormones; juvenile hormone; Juvenile Hormones - biosynthesis; Mutation; Phenotype; Promoter Regions, Genetic; Protein Binding; Proteins; Quantitative Trait Loci; sex combs reduced; silkworm; src-Family Kinases - genetics; src-Family Kinases - metabolism; Transcription, Genetic; transcriptional regulation; Worms; juvenile hormone; silkworm; transcriptional regulation; biosynthesis; sex combs reduced
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms161125945

The silkworm Dominant trimolting (Moltinism, M³) mutant undergoes three larval molts and exhibits precocious metamorphosis. In this study, we found that compared with the wild-type (WT) that undergoes four larval molts, both the juvenile hormone (JH) concentration and the expression of the JH-responsive gene Krüppel homolog 1 (Kr-h1) began to be greater in the second instar of the M³ mutant. A positional cloning analysis revealed that only the homeodomain transcription factor gene Sex combs reduced (Scr) is located in the genomic region that is tightly linked to the M³ locus. The expression level of the Scr gene in the brain-corpora cardiaca-corpora allata (Br-CC-CA) complex, which controls the synthesis of JH, was very low in the final larval instar of both the M³ and WT larvae, and exhibited a positive correlation with JH titer changes. Importantly, luciferase reporter analysis and electrophoretic mobility shift assay (EMSA) demonstrated that the Scr protein could promote the transcription of genes involved in JH biosynthesis by directly binding to the cis-regulatory elements (CREs) of homeodomain protein on their promoters. These results conclude that the homeodomain protein Scr is transcriptionally involved in the regulation of JH biosynthesis in the silkworm.