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Vol. 18, Issue 9, 3533-3544, September 2007
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EF1 Proteins in Epithelial–Mesenchymal Transition Induced by TGF-
Department of Molecular Pathology, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
Submitted March 16, 2007;
Revised June 18, 2007;
Accepted June 25, 2007
Monitoring Editor: Carl-Henrik Heldin
Epithelial–mesenchymal transition (EMT), a crucial event in cancer progression and embryonic development, is induced by transforming growth factor (TGF)-
in mouse mammary NMuMG epithelial cells. Id proteins have previously been reported to inhibit major features of TGF-
–induced EMT. In this study, we show that expression of the
EF1 family proteins,
EF1 (ZEB1) and SIP1, is gradually increased by TGF-
with expression profiles reciprocal to that of E-cadherin. SIP1 and
EF1 each dramatically down-regulated the transcription of E-cadherin in NMuMG cells through direct binding to the E-cadherin promoter. Silencing of the expression of both SIP1 and
EF1, but not either alone, completely abolished TGF-
–induced E-cadherin repression. However, expression of mesenchymal markers, including fibronectin, N-cadherin, and vimentin, was not affected by knockdown of SIP1 and
EF1. TGF-
–induced the expression of Ets1, which in turn activated
EF1 promoter activity. Moreover, up-regulation of SIP1 and
EF1 expression by TGF-
was suppressed by knockdown of Ets1 expression. In addition, Id2 suppressed the TGF-
– and Ets1-induced up-regulation of
EF1. Taken together, these findings suggest that the
EF1 family proteins, SIP1 and
EF1, are necessary, but not sufficient, for TGF-
–induced EMT and that Ets1 induced by TGF-
may function as an upstream transcriptional regulator of SIP1 and
EF1.
The online version of this article contains supplemental material at MBC Online (http://www.molbiolcell.org).
Address correspondence to: Kohei Miyazono (miyazono-ind{at}umin.ac.jp).
Abbreviations used: TGF-
, transforming growth factor-
; HLH, helix-loop-helix; EMT, epithelial-mesenchymal transition; SIP1, Smad-interacting protein1;
EF1 (ZEB1), delta-crystallin/E2-box factor 1.
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