The transcription factor Sox4 is required for thymic tuft cell development

Area of Science:

• Immunology
• Developmental Biology
• Cell Biology

Background:

• Medullary thymic epithelial cells (mTECs) are vital for T-cell development and self-tolerance.
• mTECs express peripheral tissue-restricted antigens (TRAs) to eliminate autoreactive T cells.
• Some mTECs differentiate into specialized subsets, like thymic tuft cells, to expand TRA diversity.

Purpose of the Study:

• To investigate the role of transcription factor SRY-box transcription factor 4 (Sox4) in mTEC differentiation.
• To elucidate the mechanism behind thymic tuft cell development and its relation to peripheral epithelial cells.

Main Methods:

• Utilized genetically modified mice lacking Sox4 specifically in thymic epithelial cells (TECs).
• Analyzed mTEC subsets, including Aire+ and Ccl21a+ mTECs, and thymic tuft cells.
• Investigated the impact of lymphotoxin β receptor (LTβR) deficiency on Sox4 expression in TECs.

Main Results:

• Sox4 is highly expressed in mTECs and is essential for thymic tuft cell development.
• Mice lacking Sox4 in TECs showed a significant reduction in thymic tuft cells, without affecting other mTEC subsets.
• Sox4 expression was reduced in LTβR-deficient mice, suggesting an LTβR-Sox4 pathway in tuft cell differentiation.

Conclusions:

• Sox4 plays a critical role in the differentiation of thymic tuft cells.
• The findings suggest that mTECs utilize similar transcriptional programs as peripheral epithelial cells.
• This mechanism contributes to the diversification of peripheral antigen expression in the thymus, crucial for establishing immunological self.