title: The Third Intron of the Interferon Regulatory Factor-8 Is an Initiator of Repressed Chromatin Restricting Its Expression in Non-Immune Cells.
abstract: Interferon Regulatory Factor-8 (IRF-8) serves as a key factor in the hierarchical differentiation towards monocyte/dendritic cell lineages. While much insight has been accumulated into the mechanisms essential for its hematopoietic specific expression, the mode of restricting IRF-8 expression in non-hematopoietic cells is still unknown. Here we show that the repression of IRF-8 expression in restrictive cells is mediated by its 3rd intron. Removal of this intron alleviates the repression of Bacterial Artificial Chromosome (BAC) IRF-8 reporter gene in these cells. Fine deletion analysis points to conserved regions within this intron mediating its restricted expression. Further, the intron alone selectively initiates gene silencing only in expression-restrictive cells. Characterization of this intron's properties points to its role as an initiator of sustainable gene silencing inducing chromatin condensation with suppressive histone modifications. This intronic element cannot silence episomal transgene expression underlining a strict chromatin-dependent silencing mechanism. We validated this chromatin-state specificity of IRF-8 intron upon in-vitro differentiation of induced pluripotent stem cells (iPSCs) into cardiomyocytes. Taken together, the IRF-8 3rd intron is sufficient and necessary to initiate gene silencing in non-hematopoietic cells, highlighting its role as a nucleation core for repressed chromatin during differentiation.
authors.affiliation: Department of Biotechnology and Food Engineering, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: Mamduh
authors.initials: M
authors.lastname: Khateb
authors.affiliation: Department of Biotechnology and Food Engineering, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: Nitsan
authors.initials: N
authors.lastname: Fourier
authors.affiliation: Department of Biotechnology and Food Engineering, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: Ofer
authors.initials: O
authors.lastname: Barnea-Yizhar
authors.affiliation: Department of Biotechnology and Food Engineering, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: Sigal
authors.initials: S
authors.lastname: Ram
authors.affiliation: Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Kovalev
authors.affiliation: Department of Biotechnology and Food Engineering, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: Aviva
authors.initials: A
authors.lastname: Azriel
authors.affiliation: Department of Gene Regulation and Differentiation, Helmholtz Centre for Infection Research, Braunschweig, Germany.
authors.forename: Ulfert
authors.initials: U
authors.lastname: Rand
authors.affiliation: Department of Technology Development, Kazusa DNA Research Institute, Kazusa-Kamatari, Kazusa, Japan.
authors.forename: Manabu
authors.initials: M
authors.lastname: Nakayama
authors.affiliation: Department of Gene Regulation and Differentiation, Helmholtz Centre for Infection Research, Braunschweig, Germany.
authors.forename: Hansjörg
authors.initials: H
authors.lastname: Hauser
authors.affiliation: Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: Lior
authors.initials: L
authors.lastname: Gepstein
authors.affiliation: Department of Biotechnology and Food Engineering, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: Ben-Zion
authors.initials: BZ
authors.lastname: Levi
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology; D002460:Cell Line; D002478:Cells, Cultured; D002843:Chromatin / Q000378:metabolism*; D047369:Chromatin Immunoprecipitation; D005434:Flow Cytometry; D006801:Humans; D050835:Interferon Regulatory Factors / Q000235:genetics / Q000378:metabolism*; D007438:Introns / Q000235:genetics*; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008856:Microscopy, Fluorescence; D032383:Myocytes, Cardiac / Q000378:metabolism; D041681:NIH 3T3 Cells; D000067996:RAW 264.7 Cells; D060888:Real-Time Polymerase Chain Reaction; D000099185:Interferon Regulatory Factor-8
chemical_list: D002843:Chromatin; D050835:Interferon Regulatory Factors; D000099185:Interferon Regulatory Factor-8