Structure and function of 5′-flanking regions of Bombyx mori fibroin heavy chain gene: Identification of a novel transcription enhancing element with a homeodomain protein-binding motif

βFTZ-F1 and Broad-Complex positively regulate the transcription of the wing cuticle protein gene, BMWCP5, in wing discs of Bombyx mori

“…These results confirmed that the gene gun system worked well for the promoter assay of wing discs and wing tissues. Plasmid DNA with coated gold particles was transferred well to wing discs, and the present reporter assay system was effective after the culture of wing discs (Nita et al, 2009), as reported using silk glands of B. mori (Takahashi et al, 2003;Shimizu et al, 2007). The contrasted expressions and transcriptional activity of BMWCP5 between P0 and P5 are suggested to reflect different mechanisms controlling the promoter region at around pupation and during the mid-pupal stage, as described below.…”

Silk Gland Factor-2, Involved in Fibroin Gene Transcription, Consists of LIM Homeodomain, LIM-interacting, and Single-stranded DNA-binding Proteins

“…In this scenario, the potential sequencespecific single-stranded DNA binding activity, interaction activity with Ldb proteins, and self-oligomerization activity of the SSDP/Lcaf protein family could facilitate enhancer-promoter communication by gathering together sequence-and structure-specific cis-elements scattered throughout certain gene loci and by organizing transcriptional regulatory elements on chromatin to form particular higher order structures that support transcriptional regulation. From this point of view, it is important to stress that besides the En I region of the fibroin gene, a key region in the farther upstream enhancer element from Ϫ1659 to Ϫ1590 detected in vivo and localized near a DNase-hypersensitive site, also possesses an SGF-2-binding sequence (11). The mouse Ldb protein was found to occupy numerous DNase I-hypersensitive sites on chromatin across a region of ϳ130 kb in the mouse ␣-globin locus (40).…”

“…1A). Recently, Shimizu et al (11) demonstrated that additional enhancer elements further upstream, which contain similar sequences of the E site, are also necessary for full activation of the fibroin gene in vivo.…”

Transgenic silkworms that weave recombinant proteins into silk cocoons

“…Thus, the synthesized fusion protein might be integrated into the fibroin complex through an association with endogenous fibroin H-chains and the fibroin L-chain regions of the fusion protein, allowing it to be efficiently secreted from the cells into the cocoon. After this success, several improvements were reported for the promoter and fusion partner to efficiently express recombinant proteins in the PSG (Kojima et al 2007;Shimizu et al 2007;Zhao et al 2010). These studies offered experimental evidence for the production of cocoons containing recombinant proteins using the transgenic silkworm.…”