Physical and functional interaction among Irf8 enhancers during dendritic cell differentiation

Area of Science:

• Immunology
• Developmental Biology
• Molecular Genetics

Background:

• Type 1 conventional dendritic cells (cDC1s) are crucial immune cells.
• cDC1 production relies on high expression of the IRF8 transcription factor.
• The regulatory mechanisms of Irf8 gene expression during cDC1 differentiation are not fully understood.

Purpose of the Study:

• To investigate the physical and functional interactions of three enhancers in the Irf8 3' region.
• To elucidate the roles of these enhancers in regulating Irf8 expression during cDC1 differentiation.

Main Methods:

• Analysis of enhancer interactions using genetic manipulation in mice.
• Assessment of cDC1 development in enhancer-deleted mouse models.
• Investigation of transcription factor programs regulating enhancer activity.

Main Results:

• The Irf8 3' enhancers physically interact with each other and the Irf8 gene body during cDC1 differentiation.
• The +56 kb enhancer activates other 3' enhancers in trans via an IRF8-dependent program.
• The +32 kb enhancer acts in cis to maintain high Irf8 expression in committed cDC1s.
• Compound heterozygous deletion of +56 and +32 kb enhancers prevents cDC1 generation.

Conclusions:

• Multiple enhancers cooperate dynamically to control Irf8 gene induction during cDC1 differentiation.
• This cooperative enhancer action ensures proper cDC1 development.
• The findings provide insights into the complex regulation of lineage-determining transcription factors.