title: The orphan nuclear receptor NOR-1 interacts with the homeobox containing protein Six3.
abstract: Neuron-derived orphan receptor 1 (NOR-1) is a member of the NGFI-B subfamily within the nuclear receptor superfamily. In order to identify cofactors that associate with NOR-1 in the fetal forebrain, we tested a yeast two-hybrid system with the NOR-1 cDNA fragment lacking a transactivating domain as a bait. By screening of the rat fetal brain embryonic day 17 library, a rat homologue of Six3 was identified as an associated protein. We demonstrated that NOR-1 interacted with Six3 in yeast and in vitro, and the association was required for the DNA binding and AF2 domains of NOR-1. Regarding the other members of the family (NGFI-B and RNR-1), association with Six3 was not observed in yeast. In addition, cotransfection experiments with Six3 and NOR-1 indicated that Six3 had a negative activity against the transactivation by NOR-1 through the NBRE response element in a dose-dependent manner. The overlap in expression of NOR-1 and Six3 was mainly detected in the rat fetal forebrain on embryonic day 18. Thereafter, the expression of both genes diminished rapidly. These results suggest that a dimer consisting of a homeobox containing protein Six3 and transcriptional factor NOR-1 might regulate gene expression during the late stage of the fetal forebrain development. This study provides, after the association of Ftz and Ftz-F1 in Drosophila, another example of a dimer formation of a homeobox protein and an orphan nuclear receptor.
authors.affiliation: Growth Factor Division, National Cancer Center Research Institute, Tokyo, Japan. nohkura@gan2.ncc.go.jp
authors.forename: N
authors.initials: N
authors.lastname: Ohkura
authors.forename: T
authors.initials: T
authors.lastname: Ohkubo
authors.forename: K
authors.initials: K
authors.lastname: Maruyama
authors.forename: T
authors.initials: T
authors.lastname: Tsukada
authors.forename: K
authors.initials: K
authors.lastname: Yamaguchi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D005136:Eye Proteins; D018507:Gene Expression Regulation, Developmental; D005801:Genes, Homeobox / Q000235:genetics*; D018398:Homeodomain Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D016548:Prosencephalon / Q000196:embryology / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D018160:Receptors, Cytoplasmic and Nuclear; D011987:Receptors, Steroid; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D000097607:Homeobox Protein SIX3
chemical_list: D004268:DNA-Binding Proteins; D005136:Eye Proteins; D018398:Homeodomain Proteins; D009419:Nerve Tissue Proteins; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D011987:Receptors, Steroid; D014157:Transcription Factors; D000097607:Homeobox Protein SIX3; C539820:Nr4a1 protein, rat; C091333:Nr4a3 protein, rat