title: Novel enhancer and promoter elements indispensable for the tissue-specific expression of the sericin-1 gene of the silkworm Bombyx mori.
abstract: Sericins are glue proteins produced specifically in the middle silk gland (MSG) of the silkworm Bombyx mori, while the silk fiber protein, fibroin, is produced in the posterior silk gland (PSG). These silk proteins are expected to be useful biomaterials in medical technology as well as biotechnology. In this study, we analyzed promoter elements of the sericin-1 gene (ser1) in vivo by introducing reporter constructs into silk glands via gene gun technology. The region from -1602 to +47 was sufficient to induce MSG-specific expression. The 5' deletion mutants showed a three-step decrease in promoter activity with the key sequences located between -1362 and -1250, -201 and -116, and -115 and -37. We detected a tissue- and stage-specific factor complex (MSG-intermolt-specific complex: MIC) bound to the sequence elements around the -1350, -320, -180, and -70 regions. A mutation in the -70 region, which inhibits MIC-binding, diminished almost all promoter activity, while another mutation that did not inhibit MIC-binding showed no effect on promoter activity. The results suggest that the binding of MIC to the above elements is intrinsic for the spatiotemporal specificity of ser1 in vivo.
authors.affiliation: Division of Biological Sciences and Center for Genome Dynamics, Faculty of Science, Hokkaido University, North 10, West 8, Kita-ku, Sapporo 060-0810, Japan. takiya@sci.hokudai.ac.jp
authors.forename: Shigeharu
authors.initials: S
authors.lastname: Takiya
authors.forename: Hiroshige
authors.initials: H
authors.lastname: Inoue
authors.forename: Mai
authors.initials: M
authors.lastname: Kimoto
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D019470:Biolistics; D012831:Bombyx / Q000235:genetics* / Q000378:metabolism; D004742:Enhancer Elements, Genetic; D005349:Fibroins / Q000235:genetics / Q000378:metabolism; D017930:Genes, Reporter / Q000235:genetics; D019476:Insect Proteins / Q000235:genetics* / Q000378:metabolism; D007814:Larva / Q000235:genetics* / Q000378:metabolism; D008156:Luciferases / Q000032:analysis; D008969:Molecular Sequence Data; D009154:Mutation; D009928:Organ Specificity; D010957:Plasmids; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D047030:Sericins / Q000235:genetics* / Q000378:metabolism; D047011:Silk / Q000096:biosynthesis; D014158:Transcription, Genetic
chemical_list: D019476:Insect Proteins; D047030:Sericins; D047011:Silk; D005349:Fibroins; D008156:Luciferases