ID2 secures cDC1 specification by antagonizing E proteins at a pleiotropic Zeb2 enhancer.

Area of Science:

• Immunology
• Developmental Biology
• Transcriptional Regulation

Background:

• Type 1 classical dendritic cells (cDC1s) are vital immune cells, with their specification depending on the transcriptional regulator ID2.
• The precise mechanism by which ID2 controls cDC1 development has been unclear.
• The Zeb2 -165-kb enhancer is critical for hematopoiesis and is influenced by CEBP and NFIL3 during myeloid dendritic cell differentiation.

Purpose of the Study:

• To elucidate the mechanism by which ID2 regulates cDC1 specification.
• To investigate the role of E proteins in myelopoiesis and their interaction with ID2 at the Zeb2 enhancer.
• To understand how distinct transcription factor motifs within a single enhancer contribute to diverse cell fate determination.

Main Methods:

• Analysis of the Zeb2 -165-kb enhancer and its regulatory elements, including E-boxes.
• Genetic manipulation, specifically deletion of E-boxes within the Zeb2 enhancer.
• Assessment of hematopoietic cell development, including cDC1, B cells, and plasmacytoid dendritic cells (pDCs), in wild-type and Id2-deficient mice with modified Zeb2 enhancer.

Main Results:

• ID2 promotes cDC1 development by inhibiting E protein activity at E-boxes within the Zeb2 enhancer.
• Deletion of these E-boxes disrupts B cell and pDC development, while promoting cDC1 differentiation.
• E-box deletion in the Zeb2 enhancer rescues cDC1 development in Id2-deficient mice.
• A two-step model for cDC1 specification involving NFIL3 repression of Zeb2 followed by ID2-mediated E protein inhibition is proposed.

Conclusions:

• ID2 plays a critical role in cDC1 specification by antagonizing E protein activity at the Zeb2 enhancer.
• The Zeb2 enhancer exhibits site-specific pleiotropy, with distinct motifs directing different cell fates.
• This study reveals a novel mechanism for immune cell development and provides insights into enhancer function.