The transcription factor E2A activates multiple enhancers that drive Rag expression in developing T and B cells

Area of Science:

• Immunology
• Molecular Biology
• Genetics

Background:

• Cell type-specific gene expression is regulated by transcription factors and cis-regulatory elements.
• Adaptive immunity depends on RAG-mediated assembly of T cell receptor (TCR) and immunoglobulin (Ig) genes.
• Regulation of RAG gene expression in a cell lineage-specific manner remains unclear.

Purpose of the Study:

• To identify and characterize cis-regulatory elements controlling RAG gene expression in T and B cells.
• To investigate the role of the transcription factor E2A in RAG gene regulation.
• To elucidate the mechanisms underlying cell lineage-specific RAG gene expression.

Main Methods:

• Identification of three distinct cis-regulatory elements: R-TEn (T cell), R1B (B cell), and R2B (B cell).
• Generation of knockout mice lacking R-TEn or R1B and R2B.
• Generation of a mouse strain with a mutated E2A binding site in R-TEn.
• Mapping of cis-regulatory elements and analysis of chromatin conformation changes.

Main Results:

• Distinct sets of regulatory elements (R-TEn for T cells, R1B/R2B for B cells) drive RAG gene expression in developing lymphocytes.
• These elements bind the transcription factor E2A.
• E2A recruitment to R-TEn is essential for chromatin changes that drive T cell RAG gene expression.

Conclusions:

• RAG gene expression in developing T and B cells is driven by distinct sets of E2A-dependent cis-regulatory modules.
• This finding clarifies the cell lineage-specific regulation of RAG genes, crucial for adaptive immunity.