title: Characterization of a novel class II bHLH transcription factor from the black widow spider, Latrodectus hesperus, with silk-gland restricted patterns of expression.
abstract: Members of the basic helix-loop-helix (bHLH) family are required for a number of different developmental pathways, including lymphopoiesis, myogenesis, neurogenesis, and sex determination. Screening a cDNA library prepared from silk-producing glands of the black widow spider, we have identified a new bHLH transcription factor named SGSF. Within the bHLH region, SGSF showed considerable conservation with other HLH proteins, including Drosophila melanogaster achaete and scute, as well as three HLH proteins identified by gene prediction programs. The expression pattern of SGSF was restricted to a subset of silk-producing glands, which include the tubuliform and major ampullate glands. SGSF was capable of binding an E-box element as a heterodimer with the E protein, E47, but was unable to bind this motif as a homodimer. SGSF was demonstrated to be a nuclear transcription factor capable of attenuating the transactivation of E47 homodimers in mammalian cells. SGSF represents the first example of a silk gland-restricted bHLH protein, and its expression pattern suggests that SGSF plays a role in regulating differentiation of cells in the spider that control silk gland formation or egg case silk gene expression.
authors.affiliation: Department of Biology, University of the Pacific, Stockton, California 95211, USA.
authors.forename: Kristin
authors.initials: K
authors.lastname: Kohler
authors.forename: William
authors.initials: W
authors.lastname: Thayer
authors.forename: Trang
authors.initials: T
authors.lastname: Le
authors.forename: Amardeep
authors.initials: A
authors.lastname: Sembhi
authors.forename: Keshav
authors.initials: K
authors.lastname: Vasanthavada
authors.forename: Anne M F
authors.initials: AM
authors.lastname: Moore
authors.forename: Craig A
authors.initials: CA
authors.lastname: Vierra
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins; D001740:Black Widow Spider / Q000235:genetics* / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D019281:Dimerization; D005088:Exocrine Glands / Q000378:metabolism*; D015870:Gene Expression / Q000235:genetics; D024002:HMGB Proteins / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D011485:Protein Binding; D021381:Protein Transport; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D047011:Silk; D051820:TCF Transcription Factors; D058125:Transcription Factor 7-Like 1 Protein; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D015533:Transcriptional Activation; D014162:Transfection
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D004247:DNA; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D024002:HMGB Proteins; D047011:Silk; D051820:TCF Transcription Factors; D058125:Transcription Factor 7-Like 1 Protein; D014157:Transcription Factors; C544912:TCF7L1 protein, human