Genome-wide CRISPR screen identifies FAM49B as a key regulator of actin dynamics and T cell activation

Area of Science:

• Immunology
• Molecular Biology
• Cell Biology

Background:

• T cell activation mechanisms are incompletely understood, hindering effective immune cancer therapies.
• Identifying novel regulators of T cell signaling is crucial for advancing T cell-based treatments.

Purpose of the Study:

• To identify novel genes regulating T cell activation using a genome-wide CRISPR screen.
• To characterize the function of a newly discovered regulator, FAM49B, in T cell activation.

Main Methods:

• Genome-wide CRISPR screening in T cells.
• Analysis of T cell activation markers (CD69 induction, PAK phosphorylation, actin assembly).
• Co-immunoprecipitation to assess protein interactions (FAM49B-Rac).

Main Results:

• The screen identified known T cell signaling regulators and the novel gene FAM49B.
• FAM49B deficiency resulted in hyperactivated Jurkat T cells upon stimulation.
• FAM49B interacts with active Rac GTPase, and this interaction is essential for its function.

Conclusions:

• FAM49B acts as an inhibitor of T cell activation.
• FAM49B functions by repressing Rac activity and regulating cytoskeleton reorganization.
• FAM49B is a potential therapeutic target for modulating T cell responses in cancer immunotherapy.