title: Induction of truncated form of tenascin-X (XB-S) through dissociation of HDAC1 from SP-1/HDAC1 complex in response to hypoxic conditions.
abstract: XB-S is an amino-terminal truncated protein of tenascin-X (TNX) in humans. The levels of the XB-S transcript, but not those of TNX transcripts, were increased upon hypoxia. We identified a critical hypoxia-responsive element (HRE) localized to a GT-rich element positioned from -1410 to -1368 in the XB-S promoter. Using an electrophoretic mobility shift assay (EMSA), we found that the HRE forms a DNA-protein complex with Sp1 and that GG positioned in -1379 and -1378 is essential for the binding of the nuclear complex. Transfection experiments in SL2 cells, an Sp1-deficient model system, with an Sp1 expression vector demonstrated that the region from -1380 to -1371, an HRE, is sufficient for efficient activation of the XB-S promoter upon hypoxia. The EMSA and a chromatin immunoprecipitation (ChIP) assay showed that Sp1 together with the transcriptional repressor histone deacetylase 1 (HDAC1) binds to the HRE of the XB-S promoter under normoxia and that hypoxia causes dissociation of HDAC1 from the Sp1/HDAC1 complex. The HRE promoter activity was induced in the presence of a histone deacetylase inhibitor, trichostatin A, even under normoxia. Our results indicate that the hypoxia-induced activation of the XB-S promoter is regulated through dissociation of HDAC1 from an Sp1-binding HRE site.
authors.affiliation: Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita 12, Nishi 6, Kita-ku, Sapporo 060-0812, Japan.
authors.forename: Akari
authors.initials: A
authors.lastname: Kato
authors.forename: Toshiya
authors.initials: T
authors.lastname: Endo
authors.forename: Shun
authors.initials: S
authors.lastname: Abiko
authors.forename: Hiroyoshi
authors.initials: H
authors.lastname: Ariga
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Matsumoto
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D001943:Breast Neoplasms / Q000201:enzymology / Q000235:genetics; D015687:Cell Hypoxia / Q000187:drug effects; D045744:Cell Line, Tumor; D004330:Drosophila; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D056284:Histone Deacetylase 1; D006655:Histone Deacetylases / Q000378:metabolism*; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D008969:Molecular Sequence Data; D011485:Protein Binding / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020218:Response Elements / Q000235:genetics; D016329:Sp1 Transcription Factor / Q000378:metabolism*; D019063:Tenascin / Q000235:genetics*; D015533:Transcriptional Activation / Q000187:drug effects
chemical_list: C497442:HIF1A protein, human; D006877:Hydroxamic Acids; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D012333:RNA, Messenger; D016329:Sp1 Transcription Factor; D019063:Tenascin; C081865:tenascin X; C012589:trichostatin A; C110550:HDAC1 protein, human; D056284:Histone Deacetylase 1; D006655:Histone Deacetylases