Functional interactions between Dlx2 and lymphoid enhancer factor regulate Msx2.
Dlx2, Lymphoid Enhancer Factor (Lef-1) and Msx2 transcription factors are required for several developmental processes. To understand the control of gene expression by these factors, chromatin immunoprecipitation (ChIP) assays identified Msx2 as a downstream target of Dlx2 and Lef-1. Dlx2 activates the Msx2 promoter in several cell lines and binds DNA as a monomer and dimer. A Lef-1 beta-catenin-dependent isoform minimally activates the Msx2 promoter and a Lef-1 beta-catenin-independent isoform is inactive, however co-expression of Dlx2 and both Lef-1 isoforms synergistically activate the Msx2 promoter. Co-immunoprecipitation and protein pull-down experiments demonstrate Lef-1 physically interacts with Dlx2. Deletion analyses of the Lef-1 protein reveal specific regions required for synergism with Dlx2. The Lef-1 beta-catenin binding domain (betaDB) is not required for its interaction with Dlx2. Msx2 can auto-regulate its promoter and repress Dlx2 activation. Msx2 repression of Dlx2 activation is dose-specific and both bind a common DNA-binding element. These transcriptional mechanisms correlate with the temporal and spatial expression of these factors and may provide a mechanism for the control of several developmental processes. We demonstrate new transcriptional activities for Dlx2, Msx2 and Lef-1 through protein interactions and identification of downstream targets.
Diamond
Evan
E
Center for Environmental and Genetic Medicine, Institute of Biosciences and Genetic Medicine Texas A&M Health Science Center, 2121 W. Holcombe Boulevard, Houston, TX 77030, USA.
Amen
Melanie
M
Hu
Qiaoyan
Q
Espinoza
Herbert M
HM
Amendt
Brad A
BA
D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D047369:Chromatin Immunoprecipitation; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism*; D051821:Lymphoid Enhancer-Binding Factor 1 / Q000737:chemistry / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D014157:Transcription Factors / Q000378:metabolism*; D015533:Transcriptional Activation
D004268:DNA-Binding Proteins; C088334:Distal-less homeobox proteins; D018398:Homeodomain Proteins; D051821:Lymphoid Enhancer-Binding Factor 1; C084119:MSX2 protein; D014157:Transcription Factors