PP2A catalytic subunit alpha is critically required for CD8⁺ T-cell homeostasis and antibacterial responses

Area of Science:

• Immunology
• Cell Biology
• Molecular Biology

Background:

• Serine/threonine phosphatases, particularly Protein Phosphatase 2A (PP2A), are vital in T-cell development and function.
• While tyrosine phosphatases are well-studied in T cells, the role of serine/threonine phosphatases remains less understood.

Purpose of the Study:

• To investigate the role of the catalytic subunit alpha isoform of PP2A (PP2A Cα) in CD8+ T-cell homeostasis and effector functions.
• To elucidate the mechanisms by which PP2A Cα regulates CD8+ T-cell biology.

Main Methods:

• Utilized a genetic model with T-cell-specific deletion of PP2A Cα.
• Assessed CD8+ T-cell homeostasis in secondary lymphoid organs and intestinal mucosa.
• Evaluated T-cell proliferation, survival, and antibacterial responses.
• Performed proteomics and phosphoproteomics analyses to identify PP2A Cα targets.

Main Results:

• T-cell-intrinsic PP2A Cα is essential for CD8+ T-cell homeostasis in both lymphoid organs and the gut.
• PP2A Cα deficiency leads to reduced CD8+ T-cell proliferation and survival.
• CD8+ T-cell antibacterial responses are critically dependent on PP2A Cα.
• Bcl2 expression partially rescues homeostasis in spleens but not gut or antibacterial function.
• Potential targets of PP2A Cα include mTORC1 and AKT.

Conclusions:

• PP2A Cα is a key regulator of CD8+ T-cell homeostasis and effector functions.
• The findings highlight the critical role of serine/threonine phosphatases in adaptive immunity.
• PP2A Cα influences T-cell function through pathways involving mTORC1 and AKT.