title: A Bacterial Artificial Chromosome Reporter System for Expression of the HumanFOXP3Gene in Mouse Regulatory T-Cells.
abstract: The transcription factor FOXP3 plays key roles in the development and function of regulatory T cells (Treg) capable of preventing and correcting immunopathology. There has been much interest in exploiting Treg as adoptive cell therapy in man, but issues of lack of nominal antigen-specificity and stability of FoxP3 expression in the face of pro-inflammatory cytokines have been a concern. In order to enable fundamental studies of humanFOXP3(hFOXP3) gene regulation and to provide preclinical tools to guide the selection of drugs that might modulate hFOXP3 expression for therapeutic purposes, we generated hFOXP3/AmCyan bacterial artificial chromosome (BAC) transgenic mice and transfectants, wherein hFOXP3 expression was read out as AmCyan expression. Using the transgenic mice, one can now investigatehFOXP3gene expression under defined experimental conditions used for mouse Foxp3 (mFoxp3) studies. Here, we demonstrate thathFOXP3gene expression in BAC transgenic mice is solely restricted to CD4+T-cells, as formFoxp3gene expression, showing that hFOXP3 expression in Treg cells depends on fundamentally similar processes to mFoxp3 expression in these cells. Similarly, hFOXP3 expression could be observed in mouse T-cells through TCR stimulation in the presence of TGF-β. These data suggest that, at least in part, cell type-specific human and mousefoxp3gene expression is regulated by common regulatory regions which for the human, are located within the 110-kb human FOXP3 BAC DNA. To investigatehFOXP3gene expression further and to screen potential therapeutics in modulatinghFOXP3gene expressionin vitro, we also generated hFOXP3/AmCyan expression reporter cell lines. Using the reporter cells and transcription factor inhibitors, we showed that, just as for mFoxp3 expression, inhibitors of NF-κB, AP1, STAT5, Smad3, and NFAT also block hFOXP3 expression. hFOXP3 induction in the reporter cells was also TGF-β dependent, and substantially enhanced by an mTOR inhibitor, Torin1. In both the reporter transgenic mice and cell lines, histone H4 molecules in the hFOXP3 promoter and enhancers located in human CNS1 and CNS2 regions were highly acetylated in natural Treg and TCR/TGF-β-induced Treg, indicatinghFOXP3gene expression is regulated by mechanisms similar to those previously identified for themFoxp3gene.
authors.affiliation: Department of Biomedical Sciences, Cedars-Sinai Medical Center , Los Angeles, CA , USA.
authors.forename: Masato
authors.initials: M
authors.lastname: Tsuda
authors.affiliation: Department of Biomedical Sciences, Cedars-Sinai Medical Center , Los Angeles, CA , USA.
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Tone
authors.affiliation: Department of Biomedical Sciences, Cedars-Sinai Medical Center , Los Angeles, CA , USA.
authors.forename: Chihiro
authors.initials: C
authors.lastname: Ogawa
authors.affiliation: Department of Biomedical Sciences, Cedars-Sinai Medical Center , Los Angeles, CA , USA.
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Nagaoka
authors.affiliation: Department of Biomedical Sciences, Cedars-Sinai Medical Center , Los Angeles, CA , USA.
authors.forename: Makoto
authors.initials: M
authors.lastname: Katsumata
authors.affiliation: Sir William Dunn School of Pathology, University of Oxford , Oxford , UK.
authors.forename: Andra
authors.initials: A
authors.lastname: Necula
authors.affiliation: Sir William Dunn School of Pathology, University of Oxford , Oxford , UK.
authors.forename: Duncan
authors.initials: D
authors.lastname: Howie
authors.affiliation: Rigel Pharmaceuticals , South San Francisco, CA , USA.
authors.forename: Esteban
authors.initials: E
authors.lastname: Masuda
authors.affiliation: Sir William Dunn School of Pathology, University of Oxford , Oxford , UK.
authors.forename: Herman
authors.initials: H
authors.lastname: Waldmann
authors.affiliation: Department of Biomedical Sciences, Cedars-Sinai Medical Center , Los Angeles, CA , USA.
authors.forename: Masahide
authors.initials: M
authors.lastname: Tone
keywords: FOXP3; bacterial artificial chromosome; gene expression; regulatory T cells; transcription factor