title: AML1 enhances the expression of leukotriene B4 type-1 receptor in leukocytes.
abstract: Leukotriene B(4) type-1 receptor (BLT1), which plays a role in various inflammatory diseases, is exclusively expressed in peripheral leukocytes, which suggests that its expression is stringently regulated. However, the precise mechanism of BLT1 expression is not fully understood. Here we report that acute myeloid leukemia 1 (AML1/Runx1) is involved in the enhancement of BLT1 expression in leukocytes. In retinoic acid (RA)-stimulated human promyelocytic leukemia (HL-60) cells, the transcription of the BLT1 gene was found to be significantly activated. RA did not directly modulate the BLT1 promoter, suggesting enhancers in other loci. DNase I-hypersensitivity analyses revealed an activated region, termed AE-BLex, at the intron-I:exon-II boundary. AE-BLex acts as an enhancer for the BLT1 promoter and possesses 2 AML1 recognition sites. The importance of AML1 was determined using electrophoretic mobility shift assays, reporter assays, and knockdown experiments. We demonstrated that the enhancement of BLT1 expression during the RA-induced differentiation of HL-60 cells is due to a loosening of the chromatin structure around AE-BLex, which leads to the incremental binding of AML1. The AML1/AE-BLex complex was confirmed in other BLT1- expressing leukemia cell lines and human peripheral leukocytes. Thus, AML1 enhances BLT1 expression by binding to AE-BLex, which is accessible in leukocytes.
authors.affiliation: Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Tomomi
authors.initials: T
authors.lastname: Hashidate
authors.forename: Naoka
authors.initials: N
authors.lastname: Murakami
authors.forename: Masahiro
authors.initials: M
authors.lastname: Nakagawa
authors.forename: Motoshi
authors.initials: M
authors.lastname: Ichikawa
authors.forename: Mineo
authors.initials: M
authors.lastname: Kurokawa
authors.forename: Takao
authors.initials: T
authors.lastname: Shimizu
authors.forename: Motonao
authors.initials: M
authors.lastname: Nakamura
mesh_terms: D001483:Base Sequence; D015153:Blotting, Western; D002460:Cell Line; D002478:Cells, Cultured; D042002:Chromatin Assembly and Disassembly; D047369:Chromatin Immunoprecipitation; D050676:Core Binding Factor Alpha 2 Subunit / Q000235:genetics / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D004742:Enhancer Elements, Genetic / Q000235:genetics; D018922:HL-60 Cells; D006801:Humans; D007962:Leukocytes / Q000378:metabolism*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011485:Protein Binding / Q000235:genetics / Q000502:physiology; D034622:RNA Interference; D018102:Receptors, Leukotriene B4 / Q000235:genetics / Q000378:metabolism*; D012689:Sequence Homology, Nucleic Acid
chemical_list: D050676:Core Binding Factor Alpha 2 Subunit; C513240:LTB4R protein, human; C493728:RUNX1 protein, human; D018102:Receptors, Leukotriene B4