title: GCF2: expression and molecular analysis of repression.
abstract: GC-binding factor 2 (GCF2) is a transcriptional repressor that decreases activity of the epidermal growth factor receptor (EGFR) and other genes. We have mapped the gene for GCF2 by fluorescence in situ hybridization (FISH) to chromosome 2q37. Sequence analysis of the GCF2 gene and cDNA showed that the gene consists of eight exons and introns and spans 73 kbp of DNA. Northern blot analysis showed that GCF2 mRNA was differentially expressed in many human tissues and cell lines. GCF2 mRNA was expressed as a 4.2 kb mRNA in most human tissues with the highest expression level in peripheral blood leukocytes and lowest expression in brain and testis. Additional transcripts of 6.6, 2.9 and 2.4 kb were found in some tissues but the only transcript detected in cancer cell lines was 4.2 kb with high levels found in seven Burkitts' lymphoma cell lines. Western blot analysis showed that GCF2 protein is present at high levels in Burkitts' lymphoma and several other cancer cell lines. GCF2 was found in both nuclear and cytoplasmic compartments in cells. Deletion mutants of GCF2 revealed that amino acids 429-528 are required for both DNA binding and repression of the EGFR promoter. Furthermore, GCF2 was able to substantially decrease activator protein 2 (AP2) enhancement of the EGFR promoter. Thus, GCF2 is a transcriptional repressor overexpressed in cancer cell lines with a role in regulating expression of the EGFR.
authors.affiliation: Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Room 5002, Building 37, 37 Convent Drive MSC-4264, Bethesda, MD 20892-4264, USA.
authors.forename: Toshiki
authors.initials: T
authors.lastname: Rikiyama
authors.forename: Joseph
authors.initials: J
authors.lastname: Curtis
authors.forename: Masaya
authors.initials: M
authors.lastname: Oikawa
authors.forename: Drazen B
authors.initials: DB
authors.lastname: Zimonjic
authors.forename: Nicholas
authors.initials: N
authors.lastname: Popescu
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Murphy
authors.forename: Melissa A
authors.initials: MA
authors.lastname: Wilson
authors.forename: Alfred C
authors.initials: AC
authors.lastname: Johnson
mesh_terms: D033962:Adaptor Protein Complex 2 / Q000037:antagonists & inhibitors; D015153:Blotting, Western; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D066246:ErbB Receptors / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D009154:Mutation; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins; D012097:Repressor Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: D033962:Adaptor Protein Complex 2; C114370:LRRFIP1 protein, human; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D012097:Repressor Proteins; D066246:ErbB Receptors