title: Ptx1 regulates SF-1 activity by an interaction that mimics the role of the ligand-binding domain.
abstract: Ptx1 (Pitx1) is a bicoid-related homeobox transcription factor expressed from the onset of pituitary development. It was shown to cooperate with cell-restricted factors, such as Pit1, NeuroD1/PanI and steroidogenic factor 1 (SF-1), to establish a combinatorial code conferring lineage- and promoter-specific gene transcription in the pituitary. Transcriptional synergism between Ptx1 and SF-1 on two SF-1 target genes, pituitary luteinizing hormone beta and Müllerian-inhibiting substance (MIS), requires SF-1 binding to DNA and appears to result from direct physical interaction between these two proteins. The interaction between the C-terminus of Ptx1 and the N-terminal half of SF-1 results in transcriptional enhancement that equals the activity of a constitutively active SF-1 mutant and that may mimic the effect of a still unidentified SF-1 ligand. Thus, the unmasking of SF-1 activity by Ptx1 may represent a developmental mechanism to alleviate the need for SF-1 ligand in transcription and, possibly, at critical times during organogenesis.
authors.affiliation: Laboratoire de Génétique Moléculaire, Institut de Recherches Cliniques de Montréal, 110 des Pins Ouest, Montréal, Québec, Canada H2W 1R7.
authors.forename: J J
authors.initials: JJ
authors.lastname: Tremblay
authors.forename: A
authors.initials: A
authors.lastname: Marcil
authors.forename: Y
authors.initials: Y
authors.lastname: Gauthier
authors.forename: J
authors.initials: J
authors.lastname: Drouin
mesh_terms: D000818:Animals; D054304:Anti-Mullerian Hormone; D001665:Binding Sites; D002460:Cell Line; D002522:Chlorocebus aethiops; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D051717:Fushi Tarazu Transcription Factors; D006023:Glycoproteins; D006131:Growth Inhibitors / Q000235:genetics; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D007739:L Cells; D008024:Ligands; D007986:Luteinizing Hormone / Q000235:genetics; D051379:Mice; D008957:Models, Genetic; D051761:Paired Box Transcription Factors; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D018160:Receptors, Cytoplasmic and Nuclear; D020218:Response Elements / Q000235:genetics; D017384:Sequence Deletion; D054339:Steroidogenic Factor 1; D013735:Testicular Hormones / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation; D014162:Transfection
chemical_list: D004268:DNA-Binding Proteins; D051717:Fushi Tarazu Transcription Factors; D006023:Glycoproteins; D006131:Growth Inhibitors; D018398:Homeodomain Proteins; D008024:Ligands; D051761:Paired Box Transcription Factors; D018160:Receptors, Cytoplasmic and Nuclear; D054339:Steroidogenic Factor 1; D013735:Testicular Hormones; D014157:Transcription Factors; C101485:homeobox protein PITX1; C515058:steroidogenic factor 1, mouse; D054304:Anti-Mullerian Hormone; D007986:Luteinizing Hormone; D004247:DNA