title: TGFbeta and BMP-2 activation of the OPN promoter: roles of smad- and hox-binding elements.
abstract: Members of the transforming growth factor superfamily are known to transduce signals via the activation of Smad proteins. Ligand binding to transmembrane cell surface receptors triggers the phosphorylation of pathway-specific Smads. These Smads then complex with Smad 4 and are translocated to the nucleus where they effect gene transcription. Smads 1 and 4 were recently demonstrated to mediate BMP activation of the OPN promoter by inhibiting the interaction of Hoxc-8 protein with a Hox-binding element. While previous studies have indicated that specific DNA sequences are recognized by Smad complexes in several promoters, the role of Smad-binding elements (SBEs) in activation of the OPN promoter by members of the TGFbeta superfamily has not been previously evaluated. In this study we tested the hypothesis that a putative Smad-binding region containing the sequence AGACTGTCTGGAC is involved in the activation of the OPN promoter by members of the TGFbeta superfamily. Functional analyses demonstrated that the both the HBE- and Smad-binding region were involved in BMP-2-induced activation of the promoter, whereas, the HBE appeared to be the primary region involved in activation by TGFbeta. Deletion of the first 9 bases in the Smad-binding region substantially reduced BMP-2-mediated activation of the promoter. These results strongly suggest that both the Hox- and the Smad-binding regions play a role in BMP-2-induced activation of the OPN promoter.
authors: Cardiovascular Therapeutics, Pfizer Inc., Ann Arbor, Michigan, 48105, USA.
authors: T G
authors: TG
authors: Hullinger
authors: Q
authors: Q
authors: Pan
authors: H L
authors: HL
authors: Viswanathan
authors: M J
authors: MJ
authors: Somerman
mesh_terms: D016475:3T3 Cells; D000818:Animals; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D018398:Homeodomain Proteins / Q000378:metabolism*; D051379:Mice; D053495:Osteopontin; D011401:Promoter Regions, Genetic; D012045:Regulatory Sequences, Nucleic Acid; D012795:Sialoglycoproteins / Q000235:genetics*; D051785:Smad Proteins; D051901:Smad4 Protein; D015534:Trans-Activators / Q000378:metabolism*; D015533:Transcriptional Activation; D016212:Transforming Growth Factor beta / Q000378:metabolism*
chemical_list: C525719:Bmp2 protein, mouse; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D004268:DNA-Binding Proteins; C489815:HOXC8 protein, human; D018398:Homeodomain Proteins; C489816:Hoxc8 protein, mouse; C506895:SPP1 protein, human; D012795:Sialoglycoproteins; D051785:Smad Proteins; D051901:Smad4 Protein; C490810:Smad4 protein, mouse; C506896:Spp1 protein, mouse; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; D053495:Osteopontin