title: Specific protein-protein interaction between basic helix-loop-helix transcription factors and homeoproteins of the Pitx family.
abstract: Homeoproteins and basic helix-loop-helix (bHLH) transcription factors are known for their critical role in development and cellular differentiation. The pituitary pro-opiomelanocortin (POMC) gene is a target for factors of both families. Indeed, pituitary-specific transcription of POMC depends on the action of the homeodomain-containing transcription factor Pitx1 and of bHLH heterodimers containing NeuroD1. We now show lineage-restricted expression of NeuroD1 in pituitary corticotroph cells and a direct physical interaction between bHLH heterodimers and Pitx1 that results in transcriptional synergism. The interaction between the bHLH and homeodomains is restricted to ubiquitous (class A) bHLH and to the Pitx subfamily. Since bHLH heterodimers interact with Pitx factors through their ubiquitous moiety, this mechanism may be implicated in other developmental processes involving bHLH factors, such as neurogenesis and myogenesis.
authors.affiliation: Laboratoire de Génétique Moléculaire, Institut de Recherches Cliniques de Montréal, Montréal, Québec H2W 1R7, Canada.
authors.forename: G
authors.initials: G
authors.lastname: Poulin
authors.forename: M
authors.initials: M
authors.lastname: Lebel
authors.forename: M
authors.initials: M
authors.lastname: Chamberland
authors.forename: F W
authors.initials: FW
authors.lastname: Paradis
authors.forename: J
authors.initials: J
authors.lastname: Drouin
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins; D001665:Binding Sites; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D018257:Helix-Loop-Helix Motifs; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D009154:Mutation; D051761:Paired Box Transcription Factors; D010902:Pituitary Gland / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D011333:Pro-Opiomelanocortin / Q000235:genetics / Q000378:metabolism; D051820:TCF Transcription Factors; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism*; D058125:Transcription Factor 7-Like 1 Protein; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D051761:Paired Box Transcription Factors; D011333:Pro-Opiomelanocortin; D051820:TCF Transcription Factors; D015534:Trans-Activators; D058125:Transcription Factor 7-Like 1 Protein; D014157:Transcription Factors; C501008:Neurod1 protein, mouse; C544913:Tcf7l1 protein, mouse; C101485:homeobox protein PITX1