T cell receptor-triggered nuclear actin network formation drives CD4⁺ T cell effector functions

Area of Science:

• Immunology
• Cell Biology
• Molecular Biology

Background:

• T cell antigen receptor (TCR) signaling is critical for adaptive immunity, controlling T cell proliferation, differentiation, and cytokine production.
• The precise nuclear mechanisms governing specific cytokine gene expression following T cell activation remain largely uncharacterized.

Purpose of the Study:

• To investigate the role of nuclear signaling events in regulating cytokine expression upon T cell activation.
• To uncover the function of nuclear actin dynamics in CD4+ T lymphocyte effector responses.

Main Methods:

• Utilized advanced microscopy and molecular biology techniques to visualize and manipulate nuclear actin dynamics.
• Investigated the impact of interfering with nuclear actin formation on cytokine production and antibody generation in CD4+ T cells.
• Assessed the role of calcium (Ca2+) levels, Arp2/3 complex, N-Wasp, and NIK in TCR-induced nuclear actin polymerization.

Main Results:

• Discovered the formation of a dynamic nuclear actin filament network regulated by TCR signaling.
• Demonstrated that TCR engagement rapidly induces nuclear actin polymerization via the Arp2/3 complex, modulated by nuclear Ca2+, N-Wasp, and NIK.
• Showed that inhibiting nuclear actin formation specifically impairs effector cytokine production and antibody generation without affecting immune synapse formation or proliferation.

Conclusions:

• Nuclear actin polymerization is a key regulator of effector cytokine expression in CD4+ T cells.
• This Ca2+-dependent mechanism allows for the rapid translation of TCR signals into T cell help and effector functions.
• Highlights a novel pathway linking nuclear actin dynamics to adaptive immune responses.