title: Species-specific mechanisms control the activity of the Pit1/PIT1 phosphate transporter gene promoter in mouse and human.
abstract: The Pit1 phosphate transporter is involved in regulated phosphate handling in bone forming cells. In this study, we compared the structure of the murine and human Pit1/PIT1 promoters and characterized cis-acting elements controlling Pit1/PIT1 expression. The Pit1/PIT1 promoter sequence and its location relative to the first transcribed exon are conserved and similar transcription factor binding sites are found at identical positions in mouse and human. Luciferase reporter gene assays in transiently transfected mouse ATDC5 chondrocytes and human SaOS-2 osteoblasts indicated that the activity of the mouse Pit1 promoter depends on several cis-acting elements, including ATF/CREB, Sp1 and AP-1 sites, an E-box and a TATA box. In contrast, the activity of the human promoter essentially requires a TATA-like sequence and one single Sp1 site. This Sp1 site binds Sp1, Sp3, as well as unidentified proteins present in SaOS-2 nuclear extracts and co-transfection experiments in SL2 cells indicate that Sp1 and Sp3 activate transcription from the human PIT1 promoter. These data suggest that, despite similarities in promoter structure, changes in the relative importance of conserved transcription factor binding sites cause species-dependent differences in Pit1 promoter function, which allow Sp1-related proteins to play a particularly important role in human.
authors.affiliation: Division of Bone Diseases, WHO Collaborating Center for Osteoporosis and Bone Diseases, Department of Internal Medicine, University Hospital of Geneva, 24 rue Micheli-du-Crest, CH-1211 14, Geneva, Switzerland.
authors.forename: G
authors.initials: G
authors.lastname: Palmer
authors.forename: D
authors.initials: D
authors.lastname: Manen
authors.forename: J P
authors.initials: JP
authors.lastname: Bonjour
authors.forename: J
authors.initials: J
authors.lastname: Caverzasio
mesh_terms: D024506:5' Flanking Region / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D001667:Binding, Competitive; D002352:Carrier Proteins / Q000235:genetics*; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002474:Cell-Free System / Q000378:metabolism; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D005786:Gene Expression Regulation; D006801:Humans; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins; D051379:Mice; D008969:Molecular Sequence Data; D049294:Phospholipid Transfer Proteins; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D016329:Sp1 Transcription Factor / Q000235:genetics / Q000378:metabolism; D051705:Sp3 Transcription Factor; D013045:Species Specificity; D016385:TATA Box / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D024363:Transcription Initiation Site; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D008565:Membrane Proteins; D049294:Phospholipid Transfer Proteins; D011993:Recombinant Fusion Proteins; C497121:SP3 protein, human; D016329:Sp1 Transcription Factor; C497122:Sp3 protein, mouse; D014157:Transcription Factors; D051705:Sp3 Transcription Factor; D004247:DNA; D008156:Luciferases