Ablation of cDC2 development by triple mutations within the Zeb2 enhancer

Area of Science:

• Immunology
• Developmental Biology
• Transcriptional Regulation

Background:

• The differentiation pathways of common dendritic cell progenitors (CDPs) into cDC1 and cDC2 lineages are not fully understood.
• While transcription factors like BATF3 are known to stabilize later stages of cDC1 commitment, the initial mechanisms driving CDP divergence remain elusive.

Purpose of the Study:

• To elucidate the transcriptional mechanisms governing the divergence of common dendritic cell progenitors (CDPs).
• To identify the initial requirements for the specification of pre-cDC2 cells.

Main Methods:

• Analysis of NFIL3 reporter mice to track NFIL3 expression dynamics.
• CUT&RUN and ChIP-seq to identify endogenous NFIL3 binding sites.
• CRISPR-Cas9 mediated in vivo mutational analysis of identified regulatory elements.
• Assessment of dendritic cell development and T helper 2 cell responses in mutant mice.

Main Results:

• NFIL3 transiently binds to the Zeb2 enhancer, where it competes with C/EBPα and C/EBPβ.
• NFIL3 acts as a repressor, while C/EBPs act as supporters of Zeb2 expression at these sites.
• Disruption of NFIL3-C/EBP binding sites leads to loss of Zeb2 expression in myeloid progenitors.
• This results in a complete failure of pre-cDC2 specification and mature cDC2 development, impairing T helper 2 responses.

Conclusions:

• CDP divergence into cDC1 and cDC2 lineages is regulated by a competitive mechanism at the Zeb2 enhancer involving NFIL3 and C/EBPs.
• This regulatory axis is essential for the development of cDC2s and their function in orchestrating T helper 2 immune responses.