1: J Biol Chem. 2004 Jun 4;279(23):24530-9. Epub 2004 Mar 29. Regulation of tissue inhibitor of metalloproteinase 1 gene transcription by RUNX1 and RUNX2. Bertrand-Philippe M, Ruddell RG, Arthur MJ, Thomas J, Mungalsingh N, Mann DA. Liver Group, Division of Infection, Inflammation, and Repair, University of Southampton Medical School, Southampton General Hospital, Southampton SO16 6YD, United Kingdom. Tissue inhibitor of metalloproteinase 1 (TIMP1) is a contributory factor to fibrosis of a variety of organs including the liver. UTE-1 is a regulatory DNA motif essential for TIMP1 promoter activity in a variety of cell types including hepatic stellate cells (HSC), the key profibrogenic cells of the liver. In this study we identify RUNX1 and RUNX2 as UTE-1-binding proteins that are induced at the post-transcriptional level during activation of HSC. RUNX1 is expressed in at least two major isoforms, RUNX1B and RUNX1A. Overexpression of full-length RUNX1B isoform in HSC repressed TIMP1 promoter activity, whereas the truncated RUNX1A isoform and RUNX2 functioned as stimulators. To gain further understanding of the way in which RUNX1 isoforms differentially regulate TIMP1 transcription, we investigated the relationship between the UTE-1 site and its adjacent upstream serum-response element (SRE) in the promoter. The UTE-1 and SRE sites cooperate in a synergistic fashion to stimulate transcription of a heterologous minimal active promoter providing that they are in close proximity. The key regulatory sequence within the SRE is an AP-1 site that in HSC directs high level transcription via its interaction with JunD. RUNX1A was shown to interact directly with JunD, and by contrast RUNX1B failed to interact with JunD. Co-expression studies showed that RUNX1B can repress JunD-stimulated TIMP1 promoter activity. From these observations we propose that JunD and RUNX factors assemble at the adjacent SRE and UTE-1 sites in the TIMP1 promoter and form functional interactions that stimulate transcription. However, RUNX1B is unable to interact with JunD, and as such its occupancy at the UTE-1 site disrupts the optimal assembly of transcriptional activators required for directing high level TIMP1 promoter function. PMID: 15051730 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 2: Curr Opin Struct Biol. 2003 Feb;13(1):40-8. Erratum in: Curr Opin Struct Biol. 2003 Apr;13(2):262. Tahirov Tahir [corrected to Tahirov Tahir H]. Eukaryotic transcriptional regulatory complexes: cooperativity from near and afar. Ogata K, Sato K, Tahirov TH. Department of Biochemistry, Yokohama City University School of Medicine, 3-9 Fukuura, Kanazawa-ku, Yokohama 236-0004, Japan. ogata@med.yokohama-cu.ac.jp It is characteristic of eukaryotic transcription that a unique combination of multiple transcriptional regulatory proteins bound to promoter DNA specifically activate or repress downstream target genes; this is referred to as combinatorial gene regulation. Recently determined structures have revealed different modes of protein-protein interaction on the promoter DNA from near (e.g. the Runx1-CBFbeta-DNA, NFAT-Fos-Jun-DNA, GABPalpha-GABPbeta-DNA, Ets-1-Pax-5-DNA and PU.1-IRF-4-DNA complexes) and afar with DNA looping (e.g. the c-Myb-C/EBPbeta-DNA complex), and their regulatory mechanisms. Publication Types: Review Review, Tutorial PMID: 12581658 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 3: Oncogene. 2002 Oct 17;21(47):7156-63. Both the Smad and p38 MAPK pathways play a crucial role in Runx2 expression following induction by transforming growth factor-beta and bone morphogenetic protein. Lee KS, Hong SH, Bae SC. Department of Biochemistry, School of Medicine, Chungbuk National University, Cheongju, 361-763, South Korea. The Runx family of transcription factors plays pivotal roles during normal development and in neoplasias. In mammals, Runx family genes are composed of Runx1 (Pebp2alphaB/Cbfa2/Aml1), Runx2 (Pebp2alphaA/Cbfa1/Aml3) and Runx3 (Pebp2alphaC/Cbfa3/Aml2). Runx1 and Runx3 are known to be involved in leukemogenesis and gastric carcinogenesis, respectively. Runx2, on the other hand, is a common target of transforming growth factor-beta1 (TGF-beta1) and bone morphogenetic protein-2 (BMP-2) and plays an essential role in osteoblast differentiation. Runx2 is induced by the receptor-activated Smad; Runx2 mediates the blockage of myogenic differentiation and induces osteoblast differentiation in C2C12 pluripotent mesenchymal precursor cells. However, Smad does not directly induce Runx2 expression; an additional step of de novo protein synthesis is required. Here we report that Smad-induced junB functions as an upstream activator of Runx2 expression. Furthermore, not only the Smad pathway but also the mitogen-activated protein kinase (MAPK) cascades are involved in the induction of Runx2 by TGF-beta1 and BMP-2. Our results demonstrate that following TGF-beta and BMP induction, both the Smad and p38 MAPK pathways converge at the Runx2 gene to control mesenchymal precursor cell differentiation. PMID: 12370805 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 4: Oncogene. 1999 Mar 4;18(9):1701-10. The t(8;21) fusion protein, AML1/ETO, transforms NIH3T3 cells and activates AP-1. Frank RC, Sun X, Berguido FJ, Jakubowiak A, Nimer SD. Sloan Kettering Institute, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY 10021, USA. The 8;21 translocation is the most common cytogenetic abnormality in human acute myelogenous leukemia, joining the AML1 gene on chromosome 21, to the ETO gene on chromosome 8, forming the AML1/ETO fusion gene. The AMLI/ETO fusion protein has been shown to function mainly as a transcriptional repressor of AML1 target genes and to block AML1 function in vitro and in vivo. However, AML1/ETO can also activate the BCL-2 promoter and cause enhanced hematopoietic progenitor self-renewal in vitro, suggesting gain-of-functions unique to the fusion protein. We used NIH3T3 cells to determine the transforming capacity of AML1/ETO, and to further characterize its mechanism of action. Expression of AML1/ETO in NIH3T3 cells caused cell-type specific cell death, and cellular transformation, characterized by phenotypic changes, anchorage-independent growth, and tumor formation in nude mice. In contrast, neither expression of AML1A, AML1B or ETO altered the normal growth pattern of the cells. To investigate the mechanism of transformation by AML1/ETO, we analysed the levels of activated, phosphorylated c-Jun (ser63) and other constituents of the AP-1 complex, in the presence of various AML1/ETO related proteins. Expression of AML1/ETO increased the level of c-Jun-P (ser63), and activated AP-1 dependent transcription, which was inhibited by expression of a dominant-negative c-Jun protein. Mutational analysis revealed that the runt homology domain (RHD) and a C-terminal transcriptional repression domain in AML1/ETO are required for transformation, activation of c-Jun and increased AP-1 activity. These results establish the transforming potential of the t(8;21) fusion protein and link this gain-of-function property to modulation of AP-1 activity. PMID: 10208431 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 5: Oncogene. 1995 Sep 7;11(5):833-40. The AML1/Evi-1 fusion protein in the t(3;21) translocation exhibits transforming activity on Rat1 fibroblasts with dependence on the Evi-1 sequence. Kurokawa M, Ogawa S, Tanaka T, Mitani K, Yazaki Y, Witte ON, Hirai H. Third Department of Internal Medicine, Faculty of Medicine, University of Tokyo, Japan. The t(3;21) (q26;q22) chromosomal translocation associated with blastic crisis of chronic myelogenous leukemia (CML) results in the formation of a chimeric protein fusing the amino-terminal DNA-binding domain encoded by the AML1 gene to the carboxyl-terminal-encoding portion of the Evi-1 gene. In order to evaluate transforming activity of this protein, AML1/Evi-1 was introduced into Rat1 fibroblasts. Cells expressing the fusion product formed macroscopic colonies in soft agar, indicating that AML1/Evi-1 is a transforming gene. It was also demonstrated that introduction of AML1/Evi-1 into the Rat1 clones harboring BCR/ABL also conferred enhanced capacity for anchorage independent growth. Analyses of deletion mutants of AML1/Evi-1 revealed that removal of the second zinc finger domain within the Evi-1 sequence totally abrogated the ability of AML1/Evi-1 to transform Rat1 cells. We showed that the transforming effect is correlated with the AP-1 activation induced by AML1/Evi-1. Furthermore, we demonstrated that c-jun is transcriptionally activated in Rat1 cells transformed by AML1/Evi-1, suggesting that c-jun expression is under control of AML1/Evi-1. These results indicate that the oncogenic effect of the t(3;21) translocation is caused by the generation of a chimeric transcriptional factor and that AML1/Evi-1 could perform a pivotal role in leukemic progression of CML. PMID: 7675444 [PubMed - indexed for MEDLINE] ---------------------------------------------------------------