Transcriptional reprogramming of CD11b+Esam(hi) dendritic cell identity and function by loss of Runx3

Area of Science:

• Immunology
• Cell Biology
• Transcriptional Regulation

Background:

• Classical dendritic cells (cDC) are vital antigen-presenting cells that regulate immune responses and tolerance.
• cDC development and function are orchestrated by complex transcriptional factor networks.
• Runx3 is a known transcription factor involved in cell-fate determination.

Purpose of the Study:

• To investigate the role of the transcription factor Runx3 in the development, identity, and function of splenic classical dendritic cells (cDCs).
• To elucidate the molecular mechanisms by which Runx3 regulates cDC homeostasis and antigen presentation.

Main Methods:

• In vivo cell-specific targeting of Runx3 in dendritic cell progenitors.
• Analysis of splenic dendritic cell populations using flow cytometry (e.g., CD4, CD11b, Esam expression).
• Chromatin immunoprecipitation sequencing (ChIP-seq) and gene expression analysis of purified DC subsets.

Main Results:

• Runx3 is essential for the identity, homeostasis, and function of splenic CD11b(+)Esam(hi) dendritic cells.
• Ablation of Runx3 in DC progenitors significantly reduced the number of splenic CD4(+)/CD11b(+) DCs.
• Runx3 acts as a key regulator of gene expression, specifying CD11b(+)Esam(hi) DC identity and maintaining their homeostasis.
• Loss of Runx3 reprogrammed Esam(hi) DC gene expression towards an Esam(low) DC signature, impairing phagocytosis and T cell priming capacity.

Conclusions:

• Runx3 plays a critical role in specifying the identity and function of CD11b(+)Esam(hi) classical dendritic cells.
• Runx3-mediated transcriptional control is vital for maintaining cDC homeostasis and immune surveillance.
• Dysregulation of Runx3 impacts cDC function, potentially affecting adaptive immune responses.