T cell protrusions enable fast, localised initiation of CAR signalling

Area of Science:

• Immunology
• Cell Biology
• Biophysics

Background:

• T cell membrane protrusions are known for cell migration.
• Emerging evidence highlights their role in antigen surveillance and initiating immune signaling.
• Understanding the dynamics of these structures in immune signaling is crucial.

Purpose of the Study:

• To investigate how T cell membrane protrusions initiate and contribute to immune signaling.
• To analyze the dynamic rearrangement of signaling proteins during T cell-target cell interactions.
• To provide a quantitative framework for signaling protein reorganization in protrusions.

Main Methods:

• Live-cell imaging of endogenously tagged signaling proteins in T cells.
• Utilized HER2-CAR-expressing T cells targeting HER2+ breast cancer cells.
• Employed super-resolution stimulated emission depletion (STED) microscopy for high-resolution imaging.

Main Results:

• Signaling proteins (Lck, CD45, LAT) showed no enrichment in protrusions before activation.
• Upon T cell-target cell contact, rapid protein rearrangement occurred within protrusions.
• HER2-CAR clustering and ZAP-70/LAT recruitment were enhanced in protrusions, with CD45 exclusion.

Conclusions:

• T cell membrane protrusions facilitate rapid and efficient initiation of immune signaling.
• Protrusions serve as specialized sites for enhanced signaling protein reorganization and clustering.
• Dynamic protein rearrangement within protrusions is key for CAR-mediated T cell activation.