title: Isolation and characterization of the activated B-cell factor 1 homolog in Caenorhabditis elegans.
abstract: Members of the basic helix-loop-helix (bHLH) family of transcription factors regulate a wide array of developmental processes in many cell types, including cell fate specification, differentiation and morphogenesis. Our studies describe the cloning of a gene from the nematode Caenorhabditis elegans that is closely related to the vertebrate-activated B-cell factor (ABF) gene. The nematode gene product CeABF-1 was detected by northern blot analysis from RNA isolated from pooled nematodes representing different developmental stages. The developmental expression profile of CeABF-1 was shown by RT-PCR analysis to be predominantly expressed in the larval stages L3 and L4, with lower levels observed in the L2 larval stage and adult. We also show that CeABF-1 is capable of forming heterodimers with E2A proteins and binding E-box target sites. Mammalian cells transfected with CeABF-1 expression plasmids were capable of blocking E2A-mediated gene transcription, but full repression activity required the presence of two conserved amino acid residues found within the first helix of the CeABF-1 bHLH domain. These results suggest a conserved mechanism of gene repression between certain class II bHLH and class I bHLH proteins found in vertebrates and invertebrates.
authors.affiliation: Department of Biology, University of the Pacific, Stockton, CA 95211, USA.
authors.forename: L
authors.initials: L
authors.lastname: Nguyen
authors.forename: J
authors.initials: J
authors.lastname: Round
authors.forename: R
authors.initials: R
authors.lastname: O'Connell
authors.forename: P
authors.initials: P
authors.lastname: Geurts
authors.forename: M
authors.initials: M
authors.lastname: Funes-Duran
authors.forename: J
authors.initials: J
authors.lastname: Wong
authors.forename: G
authors.initials: G
authors.lastname: Jongeward
authors.forename: C A
authors.initials: CA
authors.lastname: Vierra
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins; D017173:Caenorhabditis elegans / Q000235:genetics* / Q000254:growth & development; D029742:Caenorhabditis elegans Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D003001:Cloning, Molecular; D017124:Conserved Sequence; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins; D019281:Dimerization; D024721:E-Box Elements / Q000235:genetics; D024202:Electrophoretic Mobility Shift Assay; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D006367:HeLa Cells; D018257:Helix-Loop-Helix Motifs; D006801:Humans; D008969:Molecular Sequence Data; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D016415:Sequence Alignment; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D014158:Transcription, Genetic / Q000235:genetics
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D029742:Caenorhabditis elegans Proteins; D004247:DNA; D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D012097:Repressor Proteins; D014157:Transcription Factors; C112467:MSC protein, human; C407909:TCF3 protein, human; C486396:abf-1 protein, C elegans