title: A juvenile hormone transcription factor Bmdimm-fibroin H chain pathway is involved in the synthesis of silk protein in silkworm, Bombyx mori.
abstract: The genes responsible for silk biosynthesis are switched on and off at particular times in the silk glands of Bombyx mori. This switch appears to be under the control of endogenous and exogenous hormones. However, the molecular mechanisms by which silk protein synthesis is regulated by the juvenile hormone (JH) are largely unknown. Here, we report a basic helix-loop-helix transcription factor, Bmdimm, its silk gland-specific expression, and its direct involvement in the regulation of fibroin H-chain (fib-H) by binding to an E-box (CAAATG) element of the fib-H gene promoter. Far-Western blots, enzyme-linked immunosorbent assays, and co-immunoprecipitation assays revealed that Bmdimm protein interacted with another basic helix-loop-helix transcription factor, Bmsage. Immunostaining revealed that Bmdimm and Bmsage proteins are co-localized in nuclei. Bmdimm expression was induced in larval silk glands in vivo, in silk glands cultured in vitro, and in B. mori cell lines after treatment with a JH analog. The JH effect on Bmdimm was mediated by the JH-Met-Kr-h1 signaling pathway, and Bmdimm expression did not respond to JH by RNA interference with double-stranded BmKr-h1 RNA. These data suggest that the JH regulatory pathway, the transcription factor Bmdimm, and the targeted fib-H gene contribute to the synthesis of fibroin H-chain protein in B. mori.
authors.affiliation: From the State Key Laboratory of Silkworm Genome Biology and Key Sericultural Laboratory of the Ministry of Agriculture, College of Bio-Technology, Southwest University, Chongqing 400716 and the Research Institute of Applied Biology, Shanxi University, Taiyuan, Shanxi 030006, China.
authors.forename: Xiao-Ming
authors.initials: XM
authors.lastname: Zhao
authors.affiliation: From the State Key Laboratory of Silkworm Genome Biology and Key Sericultural Laboratory of the Ministry of Agriculture, College of Bio-Technology, Southwest University, Chongqing 400716 and mlliuchun@163.com.
authors.forename: Chun
authors.initials: C
authors.lastname: Liu
authors.affiliation: From the State Key Laboratory of Silkworm Genome Biology and Key Sericultural Laboratory of the Ministry of Agriculture, College of Bio-Technology, Southwest University, Chongqing 400716 and.
authors.forename: Li-Jun
authors.initials: LJ
authors.lastname: Jiang
authors.affiliation: From the State Key Laboratory of Silkworm Genome Biology and Key Sericultural Laboratory of the Ministry of Agriculture, College of Bio-Technology, Southwest University, Chongqing 400716 and.
authors.forename: Qiong-Yan
authors.initials: QY
authors.lastname: Li
authors.affiliation: From the State Key Laboratory of Silkworm Genome Biology and Key Sericultural Laboratory of the Ministry of Agriculture, College of Bio-Technology, Southwest University, Chongqing 400716 and.
authors.forename: Meng-Ting
authors.initials: MT
authors.lastname: Zhou
authors.affiliation: From the State Key Laboratory of Silkworm Genome Biology and Key Sericultural Laboratory of the Ministry of Agriculture, College of Bio-Technology, Southwest University, Chongqing 400716 and.
authors.forename: Ting-Cai
authors.initials: TC
authors.lastname: Cheng
authors.affiliation: From the State Key Laboratory of Silkworm Genome Biology and.
authors.forename: Kazuei
authors.initials: K
authors.lastname: Mita
authors.affiliation: From the State Key Laboratory of Silkworm Genome Biology and Key Sericultural Laboratory of the Ministry of Agriculture, College of Bio-Technology, Southwest University, Chongqing 400716 and xiaqy@swu.edu.cn.
authors.forename: Qing-You
authors.initials: QY
authors.lastname: Xia
mesh_terms: D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000096:biosynthesis / Q000235:genetics*; D012831:Bombyx / Q000235:genetics; D005349:Fibroins / Q000235:genetics* / Q000378:metabolism; D019476:Insect Proteins / Q000096:biosynthesis / Q000235:genetics*; D007605:Juvenile Hormones / Q000235:genetics* / Q000378:metabolism; D007814:Larva; D011401:Promoter Regions, Genetic / Q000235:genetics; D047030:Sericins / Q000096:biosynthesis / Q000235:genetics; D047011:Silk / Q000096:biosynthesis*
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D005349:Fibroins; D019476:Insect Proteins; D007605:Juvenile Hormones; D047030:Sericins; D047011:Silk
keywords: Basic Helix-Loop-Helix (bHLH) Transcription Factor; Bmdimm; Bombyx mori; Fibroin H-chain; Gene Expression; Gene Regulation; Juvenile Hormone; Molecular Biology; Silk Gland; Transcription Factor