c-IAP ubiquitin protein ligase activity is required for 4-1BB signaling and CD8(+) memory T-cell survival

Area of Science:

• Immunology
• Molecular Biology
• Cellular Biology

Background:

• Cellular inhibitor of apoptosis proteins (c-IAP) 1 and 2 are ubiquitin ligases regulating T-cell costimulation.
• 4-1BB, a TNF receptor, signals through TRAF and c-IAPs to activate NF-κB and ERK, impacting memory T-cell survival.

Purpose of the Study:

• To investigate the role of c-IAP E3 ligase activity in 4-1BB signaling and T-cell memory.
• To determine if impaired c-IAP2 function affects T-cell responses during viral infection.

Main Methods:

• Utilized mice expressing a dominant-negative E3-inactive c-IAP2 (c-IAP2(H570A)).
• Infected mice with lymphocytic choriomeningitis virus and analyzed T-cell responses.
• Performed T-cell adoptive transfer experiments to assess memory cell maintenance.

Main Results:

• Effector and memory T cells from c-IAP2(H570A) mice showed impaired 4-1BB signaling.
• Primary T-cell responses to viral infection were normal in c-IAP2(H570A) mice.
• Antigen-specific CD8(+) T-cell numbers declined more rapidly in c-IAP2(H570A) mice, indicating T-cell intrinsic defects in memory maintenance.

Conclusions:

• c-IAP E3 ligase activity is essential for effective 4-1BB coreceptor signaling.
• This activity is required for the long-term maintenance of CD8(+) T-cell memory.
• c-IAP2's E3 ligase function plays a critical role in CD8(+) T-cell memory persistence.