An Enhancer Element in the EphA2 (Eck) Gene Sufficient for Rhombomere-specific Expression Is Activated by HOXA1 and HOXB1 Homeobox Proteins*
- From the ‡Departments of Medicine (Rheumatology) and Cell Biology and the ¶Department of Microbiology/Immunology, Vanderbilt University, Nashville, Tennessee 37232
Abstract
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 andhoxb1 double mutant mice, suggest that expression ofEphA2 gene in rhombomere 4 is directly regulated by Hoxa1 and Hoxb1 homeobox transcription factors.
Footnotes
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↵* This work was supported by grants from the American Heart Association (Scientist Development Award to J. C.), the Vanderbilt Cancer Center (ACS institutional research grant to J. C. and Cancer Center “Core” Grant P30 CA68485 to E. R.), National Institutes of Health (F32 GM17003 to J. C. and RO1 HG00684 to E. R.), and the Kleberg Foundation (to E. R.).The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵§ To whom correspondence should be addressed: Dept. of Medicine (Rheumatology), A4323 Medical Center North, Vanderbilt University School of Medicine, Nashville, TN 37232. Tel.: 615-343-3819; Fax: 615-343-7392; E-mail: Jin.Chen{at}mcmail.vanderbilt.edu.
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↵2 J. C. Ruiz and E. J. Robertson, personal communication.
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↵3 M. Rossel and M. Capecchi, personal communication.
- Abbreviations:
- RTK
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receptor tyrosine kinase
- kb
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kilobase(s)
- EMSA
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electrophoretic mobility shift assay
- LTR
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long-terminal repeat
- ARE
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autoregulatory element.
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- Received June 2, 1998.
- The American Society for Biochemistry and Molecular Biology, Inc.
