RORC2 is involved in T cell polarization through interaction with the FOXP3 promoter

Area of Science:

• Immunology
• Molecular Biology
• Cellular Biology

Background:

• T helper (Th) cell differentiation is crucial for balancing immunity against pathogens and tolerance to self or harmless antigens.
• Understanding the molecular mechanisms governing Th cell polarization is key to controlling immune responses.
• Regulatory T cells (Tregs) and effector Th cells represent distinct lineages with opposing functions.

Purpose of the Study:

• To investigate the role of retinoic acid receptor-related orphan receptor C2 (RORC2) in regulating T cell differentiation.
• To elucidate the impact of RORC2 on the expression of FOXP3, a key marker for regulatory T cells.
• To explore the mechanisms by which RORC2 influences the balance between immune tolerance and effector responses.

Main Methods:

• Overexpression and knockdown (small interfering RNA) of RORC2 in human naive T cells.
• Quantitative analysis of FOXP3 expression levels.
• Chromatin immunoprecipitation assays to assess RORC2 binding to the FOXP3 promoter.
• Measurement of proinflammatory cytokine expression (IL-1β, IL-6, IL-17A, IFN-γ, TNF-α).

Main Results:

• RORC2 overexpression significantly reduced FOXP3 expression in human T cells.
• RORC2 knockdown led to enhanced FOXP3 expression.
• RORC2 directly binds to the FOXP3 promoter, inhibiting its transcription.
• RORC2 knockdown promoted Treg-associated gene expression and suppressed proinflammatory cytokine production.

Conclusions:

• RORC2 acts as a critical inhibitor of FOXP3 expression, thereby suppressing regulatory T cell programs.
• RORC2 plays a dual role in T cell differentiation: promoting Th17 effector functions while suppressing Treg pathways.
• These findings highlight RORC2 as a key regulator in the transcriptional cross-talk governing immune homeostasis and disease.