ZNF418, a novel human KRAB/C2H2 zinc finger protein, suppresses MAPK signaling pathway Yongqing Li Æ Dan Yang Æ Yan Bai Æ Xiaoyang Mo Æ Wen Huang Æ Wuzhou Yuan Æ Zhaochu Yin Æ Yun Deng Æ Oleg Murashko Æ Yuequn Wang Æ Xiongwei Fan Æ Chuanbing Zhu Æ Karen Ocorr Æ Rolf Bodmer Æ Xiushan Wu Received: 27 August 2007 / Accepted: 22 November 2007 / Published online: 15 December 2007 Ó Springer Science+Business Media, LLC. 2007 Abstract Cardiac differentiation involves a cascade of coordinated gene expression that regulates cell proliferation and matrix protein formation in a defined temporal-spatial manner. Zinc finger-containing transcription factors have been implicated as critical regulators of multiple cardiac- expressed genes, and are thought to be important for human heart development and diseases. Here, we have identified and characterized a novel zinc finger gene named ZNF418 from a human embryo heart cDNA library. The gene spans 13.5 kb on chromosome 19q13.43 encompassing six exons, and transcribes a 3.7-kb mRNA that encodes a protein with 676 amino acid residues. The predicted protein contains a KRAB- A box and 17 tandem C2H2 type zinc finger motifs. Northern blot analysis indicates that ZNF418 is expressed in multiple fetal and adult tissues, but is expressed at higher levels in the heart. Reporter gene assays show that ZNF418 is a tran- scriptional repressor, and the KRAB motif of ZNF418 represents the basal repressive domain. Overexpression of ZNF418 in COS-7 cells inhibits the transcriptional activity of SRE and AP-1 which may be silenced by siRNA. These results suggest that ZNF418 is a member of the zincfinger transcription factor family and may act as a negative regulator in MAPK signaling pathway. Keywords C2H2 zinc finger protein Á KRAB box Á ZNF418 Á MAPK signaling pathway Introduction During cell differentiation and development, transcription factors, which are generally composed of a DNA-binding domain and one or more separable effector domains, play an important role in the specific activation or repression of gene expression through sequence-specific binding to their cognate DNA recognition site [1, 2]. The Cys2His2 (C2H2, or Kru ¨ppel) type zinc finger pro- teins (ZFPs) are a class of well-defined eukaryotic DNA- binding proteins and constitute the single largest class of transcription factors [3, 4]. There are about 700 genes in the human genome encoding C2H2 motifs [5], in which an individual zinc finger unit is composed of 21 amino acids with a consensus sequence of CX2CX3FX5LX2HX3H, where X is any amino acid. In C2H2 type zinc finger proteins, there is a highly conserved consensus sequence TGE (K/R)P(Y/F)X, often referred to as the H/C link, between adjacent zinc finger motifs [6]. Each zinc finger specifically binds three to five base pair subsites in the major groove of the DNA and makes non-specific interactions in the minor groove [7]. The H/C link sequences also have a significant effect on DNA binding [8]. Roles for C2H2 zinc finger genes have been suggested in the regulation of normal cell growth, differentiation, embryogenesis, and tumorigenesis [9]. In addition to zinc finger regions, approximately one- third of these transcription factors also contain a regulatory domain, the Kru ¨ppel-associated box (KRAB). The KRAB Yongqing Li and Dan Yang contributed equally to the work. Y. Li Á D. Yang Á Y. Bai Á X. Mo Á W. Huang Á W. Yuan Á Z. Yin Á Y. Deng Á O. Murashko Á Y. Wang Á X. Fan Á C. Zhu Á K. Ocorr (&) Á R. Bodmer (&) Á X. Wu (&) The Center for Heart Development, Key Lab of MOE for Development Biology and Protein Chemistry, College of Life Sciences, Hunan Normal University, Hunan, Changsha 410081, P.R. China e-mail: kocorr@burmham.org R. Bodmer e-mail: rolf@burmham.org X. Wu e-mail: xiushanwu2003@yahoo.com.cn 123 Mol Cell Biochem (2008) 310:141–151 DOI 10.1007/s11010-007-9674-4