Start Date

16-3-2018 1:15 PM

End Date

16-3-2018 2:30 PM

Abstract Text

Background: IL-1b is a potent inflammatory cytokine promptly expressed in activated myeloid immune cells. Among various transcription factors, PU.1 and CCAAT/enhancer-binding protein alpha (C/EBPa) play a key role in the lineage commitment of myeloid cells. To date, however, the exact mechanisms by which these lineage-determining transcription factors employ to regulate the expression of myeloid-specific genes remains elusive; thus, this study explores the role of PU.1 and C/EBPa in remodelling the chromatin conformation that allows ample production of IL-1b.

Methods: To examine the mechanism of these lineage-determining transcription factors, production of IL-1b and enhancer-promoter interactions were analyzed in non-myeloid B16-BL6 cells that were ectopically expressed with PU.1 and C/EBPa.

Results: Overexpression of PU.1 and C/EBPa rendered B16-BL6 cells response to the bacterial component lipopolysaccharide (LPS) and expressed IL-1b. These cells also expressed a putative enhancer RNA, located ~10 kbs upstream of the IL-1b transcription start site, in response to LPS. Knocking out the enhancer region reduced IL-1b mRNA expression, suggesting that the genomic region is an enhancer. Based on the chromatin conformation capture-qPCR analysis, IL-1b enhancer-promoter interactions were established upon overexpression of PU.1 and C/EBPa, which was further enhanced by LPS.

Discussion & Conclusion: These results suggest that PU.1 and C/EBPa are pioneering transcription factors that establish chromatin looping between IL-1b regulatory elements and induce the generation of enhancer RNA, resulting in the production of IL-1b in non-myeloid cells.

Interdisciplinary Reflection: Our system that investigates how transcription factors can remodel the chromatin landscape will further expand our understanding of gene regulation.

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Mar 16th, 1:15 PM Mar 16th, 2:30 PM

Role of PU.1 and C/EBPα in Remodelling the Interleukin (IL)-1β Enhancer-Promoter Interaction

Background: IL-1b is a potent inflammatory cytokine promptly expressed in activated myeloid immune cells. Among various transcription factors, PU.1 and CCAAT/enhancer-binding protein alpha (C/EBPa) play a key role in the lineage commitment of myeloid cells. To date, however, the exact mechanisms by which these lineage-determining transcription factors employ to regulate the expression of myeloid-specific genes remains elusive; thus, this study explores the role of PU.1 and C/EBPa in remodelling the chromatin conformation that allows ample production of IL-1b.

Methods: To examine the mechanism of these lineage-determining transcription factors, production of IL-1b and enhancer-promoter interactions were analyzed in non-myeloid B16-BL6 cells that were ectopically expressed with PU.1 and C/EBPa.

Results: Overexpression of PU.1 and C/EBPa rendered B16-BL6 cells response to the bacterial component lipopolysaccharide (LPS) and expressed IL-1b. These cells also expressed a putative enhancer RNA, located ~10 kbs upstream of the IL-1b transcription start site, in response to LPS. Knocking out the enhancer region reduced IL-1b mRNA expression, suggesting that the genomic region is an enhancer. Based on the chromatin conformation capture-qPCR analysis, IL-1b enhancer-promoter interactions were established upon overexpression of PU.1 and C/EBPa, which was further enhanced by LPS.

Discussion & Conclusion: These results suggest that PU.1 and C/EBPa are pioneering transcription factors that establish chromatin looping between IL-1b regulatory elements and induce the generation of enhancer RNA, resulting in the production of IL-1b in non-myeloid cells.

Interdisciplinary Reflection: Our system that investigates how transcription factors can remodel the chromatin landscape will further expand our understanding of gene regulation.