Context-dependent Transcriptional Cooperation Mediated by Cardiac Transcription Factors Csx/Nkx-2.5 and GATA-4*
- Ichiro Shiojima‡,
- Issei Komuro§,
- Toru Oka,
- Yukio Hiroi,
- Takehiko Mizuno,
- Eiki Takimoto,
- Koshiro Monzen,
- Ryuichi Aikawa,
- Hiroshi Akazawa,
- Tsutomu Yamazaki,
- Sumiyo Kudoh and
- Yoshio Yazaki
- From the Department of Cardiovascular Medicine, University of Tokyo Graduate School of Medicine, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan
Abstract
Although the cardiac homeobox geneCsx/Nkx-2.5 is essential for normal heart development, little is known about its regulatory mechanisms. In a search for the downstream target genes of Csx/Nkx-2.5, we found that the atrial natriuretic peptide (ANP) gene promoter was strongly transactivated by Csx/Nkx-2.5. Deletion and mutational analyses of the ANP promoter revealed that the Csx/Nkx-2.5-binding element (NKE2) located at −240 was required for high level transactivation by Csx/Nkx-2.5. We also found that Csx/Nkx-2.5 and GATA-4 displayed synergistic transcriptional activation of the ANP promoter, and in contrast to previous reports (Durocher, D., Charron, F., Warren, R., Schwartz, R. J., and Nemer, M. (1997) EMBO J. 16, 5687–5696; Lee, Y., Shioi, T., Kasahara, H., Jobe, S. M., Wiese, R. J., Markham, B., and Izumo, S (1998) Mol. Cell. Biol. 18, 3120–3129), this synergism was dependent on binding of Csx/Nkx-2.5 to NKE2, but not on GATA-4-DNA interactions. Although GATA-4 also potentiated the Csx/Nkx-2.5-induced transactivation of the artificial promoter that contains multimerized Csx/Nkx-2.5-binding sites, Csx/Nkx-2.5 reduced the GATA-4-induced transactivation of the GATA-4-dependent promoters. These findings indicate that the cooperative transcriptional regulation mediated by Csx/Nkx-2.5 and GATA-4 is promoter context-dependent and suggest that the complexcis-trans interactions may fine-tune gene expression in cardiac myocytes.
Footnotes
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↵* This work was supported in part by grants from the Japanese Ministry of Education, Science, and Culture; the Japan Heart Foundation; Yamanouchi Pharmaceuticals; and Tanabe Medical Frontier Conference.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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↵‡ Supported by the Sankyo Foundation of Life Science.
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↵§ To whom correspondence should be addressed. Tel.: 81-3-3815-5411; Fax: 81-3-3818-6673; E-mail: komuro-tky{at}umin.ac.jp.
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↵2 E. Takimoto, I. Komuro, I. Shiojima, and T. Mizuno, unpublished observations.
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↵3 Y. Hiroi, S. Kudoh, I. Shiojima, and I. Komuro, unpublished observations.
- Abbreviations:
- ANP
-
atrial natriuretic peptide
- bp
-
base pair(s)
- IL-5
-
interleukin-5
- GST
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glutathione S-transferase
- PCR
-
polymerase chain reaction
- EMSA
-
electrophoretic mobility shift assay
- HA
-
hemagglutinin
- PAGE
-
polyacrylamide gel electrophoresis
- SRF
-
serum response factor
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- Received November 5, 1998.
- Revision received December 10, 1998.
- The American Society for Biochemistry and Molecular Biology, Inc.
