Determination of the Consensus Binding Site for MEF2 Expressed in Muscle and Brain Reveals Tissue-specific Sequence Constraints (*)
- From the Department of Cardiology, Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115
- § Recipient of a research fellowship from the American Heart Association (Massachusetts Affiliate). To whom correspondence should be addressed: Division of Cardiovascular Research, St. Elizabeth's Medical Center, 736 Cambridge St., Boston, MA m02135. Tel.: 617-562-7509; Fax: 617-562-7506.
Abstract
The myocyte-specific enhancer factor-2 (MEF2) proteins are expressed in the three major types of muscle (skeletal, cardiac, and smooth) and function as transcriptional activators of muscle-specific and growth factor-regulated genes through binding to a canonical A/T-rich cis-element. Although MEF2 proteins are also expressed in brain, MEF2-regulated muscle-specific gene products are not detected in this tissue. To gain insight into the regulation of MEF2 function in vivo, we have selected its optimal DNA targets from a library of degenerate oligonucleotides using anti-MEF2A antibodies and cell extracts from skeletal muscle, heart, and brain. The consensus binding site in these three tissues contains an indistinguishable core motif, 5′-CT(A/t)(a/t)AAATAG-3′. However, the optimal target for MEF2 expressed in the brain shows additional sequence constraints (5′-TGTTACT(A/t)(a/t)AAATAGA(A/t)-3′) that are not observed in the sequences selected with skeletal and cardiac muscle extracts. Thus, differences in DNA binding preferences of MEF2 proteins in muscle and brain may contribute to tissue-specific gene expression during myogenesis and neurogenesis.
Footnotes
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↵¶ Recipient of support from the Spanish Ministerio de Educación y Ciencia. On sabbatical from Departamento de Bioquímica, Facultad de Medicina, Universidad Autónoma, Madrid, Spain.
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↵* This work was supported in part by National Institutes of Health Grants ROIHL35576 and ROIHL45425 (to V. M.) and by Children's Hospital. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵1 The abbreviations used are:
- bHLH
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basic helix-loop-helix
- MEF2
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myocyte-specific enhancer factor-2
- PCR
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polymerase chain reaction
- RSRF
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related to serum response factor
- CASTing
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C yclic Amplification and Selection of Targets.
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- Received July 17, 1995.
- Revision received August 2, 1995.
- © 1995 by The American Society for Biochemistry and Molecular Biology, Inc.
