The Third Intron of the Interferon Regulatory Factor-8 Is an Initiator of Repressed Chromatin Restricting Its Expression in Non-Immune Cells

Overview

Journal PLoS One

Specialties General Medicine
Science

Date 2016 Jun 4

PMID 27257682

Authors

Mamduh Khateb

Nitsan Fourier

Ofer Barnea-Yizhar

Sigal Ram

Ekaterina Kovalev

Aviva Azriel

Ulfert Rand

Manabu Nakayama

Hansjorg Hauser

Lior Gepstein

Ben-Zion Levi

Affiliations

Soon will be listed here.

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.

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