Dynein Separately Partners with NDE1 and Dynactin To Orchestrate T Cell Focused Secretion

Area of Science:

• Immunology
• Cell Biology
• Molecular Motors

Background:

• T cells utilize focused secretion for targeted immune responses.
• Microtubule organizing center (MTOC) translocation and vesicle transport are critical for T cell effector functions.
• Dynein motor proteins are involved in intracellular transport, but their specific roles in T cell secretion are not fully elucidated.

Purpose of the Study:

• To investigate the distinct roles of dynein-binding proteins NDE1 and dynactin in T cell-focused secretion.
• To determine how these complexes contribute to MTOC translocation and vesicle trafficking to the immunological synapse.
• To elucidate their impact on cytotoxic T lymphocyte (CTL)-mediated killing.

Main Methods:

• Utilized Jurkat cells and primary murine CTLs.
• Employed dominant-negative NDE1 expression and NDE1/p150(Glued) knockdown.
• Analyzed protein complex formation, subcellular localization, MTOC translocation, and CTL-mediated cytotoxicity.
• Studied the transport of CTLA4 and granzyme B vesicles.

Main Results:

• NDE1 and dynactin form mutually exclusive complexes with dynein.
• NDE1 is essential for dynein accumulation at the immunological synapse and MTOC translocation.
• Dynactin (p150(Glued)) mediates the transport of CTLA4 and granzyme B vesicles to the immunological synapse.
• NDE1 knockdown inhibits MTOC translocation and CTL killing; dynactin knockdown impairs vesicle trafficking and CTL lysis.

Conclusions:

• The NDE1/Lissencephaly 1 complex is crucial for MTOC translocation during T cell-focused secretion.
• The dynactin complex is essential for lytic granule and CTLA4 vesicle transport to the immunological synapse.
• These two complexes independently mediate distinct, critical steps in T cell effector function, highlighting a dual mechanism for focused secretion.