An enhancer element in the EphA2 (Eck) gene sufficient for rhombomere-specific expression is activated by HOXA1 and HOXB1 homeobox proteins.
In the hindbrain of the mouse embryo, there is often coincident rhombomere-restricted expression of Eph receptor tyrosine kinases and Hox homeobox genes, raising the possibility of regulatory interactions. In this paper, we have identified cis-acting regulatory sequences of the EphA2 (Eck) gene, which direct node and hindbrain-specific expression in transgenic embryos. An 8-kilobase region of mouse genomic DNA element was sufficient to drive rhombomere 4 (r4)-specific expression while conferring patchy expression in the node. Further analysis localized the rhombomere-specific enhancer to a 0.9-kilobase sequence. This element contains multiple Hox-Pbx consensus binding sites that bind to both HOXA1/Pbx1 and HOXB1/Pbx1 proteins in vitro. Co-expression of either HOXA1 or HOXB1 with Pbx1 transactivated EphA2 enhancer-dependent reporter gene expression. These results, together with observations of reduced EphA2 expression in hoxa1 and hoxb1 double mutant mice, suggest that expression of EphA2 gene in rhombomere 4 is directly regulated by Hoxa1 and Hoxb1 homeobox transcription factors.
Chen
J
J
Departments of Medicine (Rheumatology) and Cell Biology, Vanderbilt University, Nashville, Tennessee 37232, USA. Jin.Chen@mcmail.vanderbilt.edu
Ruley
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D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D019556:COS Cells; D002460:Cell Line; D016384:Consensus Sequence; D017931:DNA Primers; D005314:Embryonic and Fetal Development; D004742:Enhancer Elements, Genetic; D005260:Female; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012091:Repetitive Sequences, Nucleic Acid; D012249:Rhombencephalon / Q000196:embryology* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D000099261:Homeobox A1 Protein
D017931:DNA Primers; D018398:Homeodomain Proteins; D014157:Transcription Factors; D000099261:Homeobox A1 Protein