MCPIP1 Endoribonuclease Activity Negatively Regulates Interleukin-17-Mediated Signaling and Inflammation

Area of Science:

• Immunology
• Molecular Biology
• Cell Signaling

Background:

• Interleukin-17 (IL-17) signaling is critical in host defense but also implicated in autoimmune diseases.
• Regulation of the IL-17 pathway is essential for preventing excessive inflammation and pathology.
• MCPIP1 (also known as Regnase-1) is a signaling intermediate with poorly understood roles in IL-17 transduction.

Purpose of the Study:

• To investigate the role of MCPIP1 as a feedback inhibitor in IL-17 receptor signaling.
• To elucidate the molecular mechanisms by which MCPIP1 regulates IL-17-mediated responses.
• To assess the in vivo relevance of MCPIP1 in IL-17-driven pathologies and infections.

Main Methods:

• MCPIP1 knockdown experiments to assess IL-17 signaling.
• Analysis of MCPIP1 haploinsufficient mice in models of infection (Candida albicans) and autoimmune inflammation (EAE, pulmonary inflammation).
• mRNA degradation assays and promoter activity studies to identify MCPIP1 targets (Il6, Nfkbiz, Il17ra, Il17rc).

Main Results:

• MCPIP1 knockdown potentiated IL-17 signaling, dependent on its endoribonuclease activity.
• MCPIP1 haploinsufficiency exacerbated IL-17-dependent pathology in EAE and pulmonary inflammation models.
• MCPIP1 directly degrades Il6 mRNA and regulates Nfkbiz mRNA stability, impacting IL-6 and IκBζ expression.
• MCPIP1 was found to degrade Il17ra and Il17rc mRNA, suggesting a direct negative feedback on IL-17 receptor components.

Conclusions:

• MCPIP1 functions as a critical negative regulator of IL-17 receptor signaling through multiple mechanisms.
• MCPIP1's regulation of IL-6, IκBζ, and IL-17 receptor subunits contributes to biologically relevant inhibition of IL-17 responses.
• Targeting MCPIP1 may offer therapeutic strategies for modulating IL-17-driven diseases.