Spatially specific expression of Hoxb4 is dependent on the ubiquitous transcription factor NFY.
Understanding how boundaries and domains of Hox gene expression are determined is critical to elucidating the means by which the embryo is patterned along the anteroposterior axis. We have performed a detailed analysis of the mouse Hoxb4 intron enhancer to identify upstream transcriptional regulators. In the context of an heterologous promoter, this enhancer can establish the appropriate anterior boundary of mesodermal expression but is unable to maintain it, showing that a specific interaction with its own promoter is important for maintenance. Enhancer function depends on a motif that contains overlapping binding sites for the transcription factors NFY and YY1. Specific mutations that either abolish or reduce NFY binding show that it is crucial for enhancer activity. The NFY/YY1 motif is reiterated in the Hoxb4 promoter and is known to be required for its activity. As these two factors are able to mediate opposing transcriptional effects by reorganizing the local chromatin environment, the relative levels of NFY and YY1 binding could represent a mechanism for balancing activation and repression of Hoxb4 through the same site.
Division of Eukaryotic Molecular Genetics, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK.
Jonathan
J
Gilthorpe
Marie
M
Vandromme
Tim
T
Brend
Alejandro
A
Gutman
Dennis
D
Summerbell
Nick
N
Totty
Peter W J
PW
Rigby
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D023081:CCAAT-Binding Factor / Q000378:metabolism*; D017124:Conserved Sequence; D004247:DNA / Q000235:genetics / Q000378:metabolism; D005314:Embryonic and Fetal Development / Q000235:genetics; D004742:Enhancer Elements, Genetic; D050981:Erythroid-Specific DNA-Binding Factors; D018507:Gene Expression Regulation, Developmental; D005801:Genes, Homeobox; D018398:Homeodomain Proteins / Q000235:genetics*; D007438:Introns; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D009154:Mutation; D011401:Promoter Regions, Genetic; D012689:Sequence Homology, Nucleic Acid; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*; D050986:YY1 Transcription Factor
D023081:CCAAT-Binding Factor; D050981:Erythroid-Specific DNA-Binding Factors; D018398:Homeodomain Proteins; C513262:Hoxb4 protein, mouse; D014157:Transcription Factors; D050986:YY1 Transcription Factor; C494699:Yy1 protein, mouse; C402244:nuclear factor Y; D004247:DNA