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Updated: Jul 24, 2025
A TIRF Microscopy Technique for Real-time, Simultaneous Imaging of the TCR and its Associated Signaling Proteins
Published on: March 22, 2012
Self-programmed dynamics of T cell receptor condensation
Abstract:
A common event upon receptor-ligand engagement is the formation of receptor clusters on the cell surface, in which signaling molecules are specifically recruited or excluded to form signaling hubs to regulate cellular events. These clusters are often transient and can be disassembled to terminate signaling. Despite the general relevance of dynamic receptor clustering in cell signaling, the regulatory mechanism underlying the dynamics is still poorly understood. As a major antigen receptor in the immune system, T cell receptors (TCR) form spatiotemporally dynamic clusters to mediate robust yet temporal signaling to induce adaptive immune responses. Here we identify a phase separation mechanism controlling dynamic TCR clustering and signaling. The TCR signaling component CD3ε chain can condensate with Lck kinase through phase separation to form TCR signalosomes for active antigen signaling. Lck-mediated CD3ε phosphorylation, however, switched its binding preference to Csk, a functional suppressor of Lck, to cause the dissolvement of TCR signalosomes. Modulating TCR/Lck condensation by targeting CD3ε interactions with Lck or Csk directly affects T cell activation and function, highlighting the importance of the phase separation mechanism. The self-programmed condensation and dissolvement is thus a built-in mechanism of TCR signaling and might be relevant to other receptors.
Insights
Dynamic T cell receptor (TCR) clustering, crucial for immune responses, is controlled by phase separation. This mechanism involves condensation and dissolution of TCR signalosomes, regulating T cell activation.
Area of Science:
- Immunology
- Cell Biology
- Biophysics
Background:
- Receptor-ligand engagement triggers cell surface receptor clustering, forming signaling hubs that regulate cellular events.
- These dynamic clusters are often transient, disassembling to terminate signaling, but the regulatory mechanisms remain unclear.
- T cell receptors (TCRs) form dynamic clusters for robust yet temporal signaling essential for adaptive immunity.
Purpose of the Study:
- To investigate the mechanism controlling dynamic T cell receptor (TCR) clustering and signaling.
- To identify the role of phase separation in the formation and dissolution of TCR signaling hubs.
Main Methods:
- Investigated the phase separation mechanism of TCR clustering using biochemical and biophysical approaches.
- Analyzed the role of CD3ε chain condensation with Lck kinase in TCR signalosome formation.
- Examined the effect of Lck-mediated phosphorylation on CD3ε binding preference and signalosome dissolution.
Main Results:
- Identified phase separation as a key mechanism regulating dynamic TCR clustering and signaling.
- Demonstrated that the CD3ε chain condenses with Lck kinase to form TCR signalosomes for antigen signaling.
- Showed that Lck-mediated CD3ε phosphorylation promotes Csk binding, leading to signalosome dissolution and termination of signaling.
- Found that modulating TCR/Lck condensation impacts T cell activation and function.
Conclusions:
- Phase separation governs the dynamic assembly and disassembly of TCR signalosomes, acting as a built-in regulatory mechanism for T cell signaling.
- This self-programmed condensation and dissolution process is critical for controlling T cell activation and function.
- The identified phase separation mechanism may be relevant to the signaling dynamics of other cell surface receptors.
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