Interleukin-12p40 variant form reduces Interleukin-12p80 secretion

Area of Science:

• Immunology
• Molecular Biology
• Cell Biology

Background:

• Interleukin-12 (IL-12) is crucial for differentiating CD4+ T cells into type 1 helper T cells.
• IL-12 (IL-12p70) is a heterodimer of p40 and p35 subunits, primarily secreted by antigen-presenting cells like macrophages and dendritic cells (DCs).

Purpose of the Study:

• To investigate the production and function of a newly identified p40 splice variant in activated mouse bone marrow-derived dendritic cells (BMDCs).

Main Methods:

• Analysis of mRNA from activated BMDCs to identify alternative splicing.
• Expression of the p40 variant in HEK-293T cells.
• Co-expression studies with p40 and p35 subunits to assess effects on IL-12 secretion and function.

Main Results:

• Activated BMDCs produce a p40 splice variant mRNA via alternative splicing in exon 5, leading to a truncated protein with novel amino acids.
• The p40 variant is not secreted and does not affect IL-12p40 or IL-12p70 secretion or function.
• Expression of the p40 variant significantly decreased the secretion of IL-12p80, a homodimer of p40.

Conclusions:

• A novel p40 splice variant of IL-12 exists and is produced by activated dendritic cells.
• This p40 variant does not impact IL-12p70 but negatively regulates IL-12p80 secretion, suggesting a role in fine-tuning IL-12 signaling pathways.