Dendritic cell-specific Mgat2 knockout mice show antigen presentation defects but reveal an unexpected CD11c...

Area of Science:

• Immunology
• Glycobiology
• Molecular Biology

Background:

• Zwitterionic polysaccharide antigens like PSA activate CD4+ T cells via MHCII presentation.
• N-glycans on MHCII are crucial for high-affinity binding and T cell recognition.
• Previous myeloid-specific Mgat2 knockout mice (M-cKO) showed PSA response defects but also immunodeficiency.

Purpose of the Study:

• To develop a specific murine model (DC-cKO) to study Mgat2 ablation in dendritic cells (DCs) for PSA presentation.
• To assess the role of Mgat2 in DCs for PSA presentation and T cell activation in vivo.
• To evaluate the specificity of the CD11c-CRE driver for targeting DCs.

Main Methods:

• Generated a novel murine model (DC-cKO) using CD11c-CRE-GFP to ablate Mgat2 specifically in DCs.
• Assessed PSA presentation and T cell activation in vitro using Mgat2-deficient DCs.
• Analyzed gene deletion patterns and reporter gene expression in hematopoietic lineages.

Main Results:

• Mgat2-deficient DCs from DC-cKO mice exhibited impaired PSA presentation and reduced T cell activation in vitro.
• The CD11c promoter showed unexpected activity, causing Mgat2 deletion in multiple hematopoietic lineages.
• Poor penetrance of Mgat2 deletion in native DC populations and minimal GFP signal were observed.

Conclusions:

• The CD11c promoter is not strictly DC-specific, leading to off-target gene deletion.
• Caution is advised when interpreting data from mice generated using the CD11c-CRE model.
• The study underscores the complexity of genetic targeting in vivo and the importance of validating Cre driver specificity.