Regulation of NF-E2 Activity in Erythroleukemia Cell Differentiation*
- Tadashi Nagai‡,
- Kazuhiko Igarashi§,
- Jun-etsu Akasaka¶,
- Kazumichi Furuyama¶,
- Hiroyoshi Fujita¶,
- Norio Hayashi¶,
- Masayuki Yamamoto§ and
- Shigeru Sassa‡‖
- From the ‡Rockefeller University, New York, New York 10021, the §Center for Tsukuba Advanced Research Alliance and the Institute of Basic Medical Sciences, University of Tsukuba, Tsukuba 305, Japan, and the ¶Tohoku University School of Medicine, Sendai 980, Japan
Abstract
The erythroid transcription factor NF-E2 is an obligate heterodimer composed of two different subunits (p45 and p18), each containing a basic region-leucine zipper DNA binding domain, and it plays a critical role in erythroid differentiation as an enhancer-binding protein for expression of the β-globingene. We show here that dimethyl sulfoxide treatment of wild-type murine erythroleukemia cells, but not a mutant clone of dimethyl sulfoxide-resistant cells, increases NF-E2 activity significantly, which involves both up-regulation of DNA binding and transactivation activities. Both activities were reduced markedly by treatment of cells with 2-aminopurine but not by genistein. Activation of the Ras-Raf-MAP kinase signaling cascade increased NF-E2 activity significantly, but this was suppressed when MafK was overexpressed. Domain analysis revealed an activation domain in the NH2-terminal region of p45 and a suppression domain in the basic region-leucine zipper of MafK. These findings indicate that induction of NF-E2 activity is essential for erythroid differentiation of murine erythroleukemia cells, and serine/threonine phosphorylation may be involved in this process. In addition, they also suggest that a MafK homodimer can suppress transcription, not only by competition for the DNA binding site, but also by direct inhibition of transcription. Hence, MafK may function as an active transcription repressor.
Footnotes
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↵* This work was supported in part by United States Public Health Service Grant DK32890 (to S. S.), a grant from the Yamanouchi Molecular Medicine Research Fund (to K. F.), and by grants-in-aid from the Ministry of Education, Science, and Culture of Japan (to K. I., M. Y., and H. F.).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. Fax: 212-327-8872.
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↵1 The abbreviations used are: b-zip, basic region-leucine zipper; MEL, murine erythroleukemia; Me2SO, dimethyl sulfoxide; DS, Me2SO-sensitive; DR, Me2SO-resistant; MAPK, mitogen-activated protein kinase; MAPKK, MAPK kinase; 2-AP, 2-aminopurine; ALAS-E, erythroid-specific δ-aminolevulinate synthase; ALAS-N, nonspecific δ-aminolevulinate synthase.
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↵2 MafK is a protein, while mafKrepresents its gene.
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- Received June 11, 1997.
- Revision received September 22, 1997.
- The American Society for Biochemistry and Molecular Biology, Inc.
