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カイコセリシン-１遺伝子の制御に関わるＰＯＵドメインを持つ転写因子のクローニング Molecular cloning of a POU domain transcriptionfactor involved in regulation of Bombyxsericin-1 gene 福田, 雅一フクタ, マサカズ FUKUTA, Masakazu The POU domain is a DNA-binding regionconsisting of 75-82 amino acids POU-specific domain, a short variable linker region and a POU-homeodomain of 60 amino acids (for a review,seeRuvkin and Finny, 1991). It was originarry found in three mammalian transcription factors, the pituitary-specific Pit-1/GHF-1,the ubiquitous Oct-1 and the predominantly B cell specific Oct-2, and the product of the cell lineage control gene Unc-86 of Caenorhadbitis elegans (Herr et al.,1988 and references therein). By means of sequence similarity, several other mammalian POU domain genes have also been identified (He et al., 1989; Monouki et al., 1990; Okamoto et al., 1990; Rosner et al., 1990 Scholer et al., 1990; Suzuki et al., 1990). All of them were shown to interact with an octamer-like sequence and to activate transcription via an octamer motif near the TATA box.The Drosophila Cfl-a protein,which interants with a DNA element required for expression of the dopa decarboxylase gene in selected dopaminergic neurons (Johnson and Hirsh,1990), was also found to posses a POU domain similar to those of the mouse Oct-6 (Suzuki et al.,1990) and the humann Brn-1 and Brn-2 (He et al.,1898) proteins. These POU domain genes are likely regulatory genes controlling transcription of distinct sets of genes during develop- ment. The finding that two dwarf mutations in mice are null mutations in the Pit-1/GHF-1 gene (Li et al., 1990) provide further support on the roles of POU transcription factors in development. Recently, the mternally expressed POU transcription factor, the Oct-3/4 protein (Okamoto et al., 1990; Scholer et al., 1990), has also been shown to be required for the first embryonic cell division in mice (Rosner et al., 1990). 　　　Suzuki and his colleagues have been studying the developmental regulation of the silk protein genes in Bonbyx mori (Suzuki et al., 1990). Among them, the siricin-1 gene is expressed exclusively in the middle silk gland while the fibroin gene is specific to the posterior silk gland. Both genes are actively expressed during the intermolt but repressed during the molting stages. Several silk gland protins have been identified as putative regulatoly factors involved in the transcriptioal control of the fibroin and scrin-1 genes ( Hui et al., 1990; Matsuno et al., 1989,1990). One of these proeins , SGF-3, was found to bind with high affinity to the SC region of the sericin-1 gene and the distal upstream reion of the fibroin gene (Hui et al., 1990). These regions are known to be important for an efficient transcription in the silk gland extracts. Amultimer of the SC region gave transcriptional enhancement in extracts prepared from the middle silk gland where the sericin-1 gene is specifically epressed but that of a mutant SC region giving a reduced affinity for SGF-3 did not (Matsuno et al., 1990). Mobility shift assay revealed that SGF-3 is far more abundant in the silk gland of the 2-day-old fifth-instar larvae than in the pasterior silk gland (Hui et al., 1990; Matsuno et al., 1990; Y. Suzuki, unpublised). These obaervations suggest that the SGF-3 is a key regulatory factor in the transcription control ol the sericin-1 gene. 　　　The SGF-3 was supposed as an octamer binding protein (Hui et al., 1990). Since high affnitiy SGF-3 binding sites, such as the SC and fibroin distal upstream regions, also contain octamer-like sequences, it has been speculated that SGF-3 might possess a POU domain similar to the mammalian octamer-binding proteins. This repoort presents here the isolation and characterization of a POU domain containg cDNA (POU-M1) from the middle silk gland. It encodes a protein with a POU domain identical to that of the Drosophila Cfl-a protein. By mobility shift assay and nuclease protection assay, the POU-M1 protein and the putative silk gland factor SGF-3 were found to interact in an indistinguishable manner with the SC region of the sericin-1 gene, which is a key cis-acting element involved in the stimulation of sercin-1 gene transcription through the interaction with SGF-3. Antibodies raised against the synthetic oligopeptides correponding to the two regions of putative POU-M1 protein reacted specifically to both the POU-M1 protein and SGF-3. Northern blot hybridization and Western blotting revealed that the POU-M1 expression is regulated both temporally and spatially during the silk gland development. It is concluded that the POU-M1 proein is identical to the SGF-3 and proposed that the differential expression of the POU-M1 gene is probably involved in the transcriptional regulation of the silk protein genes. application/pdf 総研大甲第26号 eng thesis https://ir.soken.ac.jp/records/1296 博士（理学） 1992-03-16 総合研究大学院大学 https://ir.soken.ac.jp/record/1296/files/甲26_要旨.pdf application/pdf 275.2 kB 2016-02-17 https://ir.soken.ac.jp/record/1296/files/甲26_本文.pdf application/pdf 1.5 MB 2016-02-17