AKT activity orchestrates marginal zone B cell development in mice and humans

Area of Science:

• Immunology
• Cell Biology
• Molecular Biology

Background:

• The developmental pathways for marginal zone (MZ) and follicular (FO) B cells are not fully understood.
• Identifying key signaling molecules is crucial for understanding B cell subset differentiation.

Purpose of the Study:

• To investigate the role of AKT signaling in the development of MZ B cells.
• To explore the conservation of AKT-mediated B cell development between mice and humans.

Main Methods:

• Utilized genetic models in mice to manipulate AKT signaling and FoxO transcription factors.
• Analyzed human splenic B cell subsets (IgD+CD27+, IgD+CD27-, IgD-CD27+) for AKT signaling levels.
• Performed in vitro differentiation assays using human B cell precursors.
• Quantified CD148 expression as a marker for AKT signaling in B cells.

Main Results:

• The AKT-FoxO signaling axis functions as a critical regulator, acting as an on-off switch for MZ B cell formation in mice.
• Human splenic IgD+CD27+ B cells, analogous to MZ B cells, exhibit heightened AKT signaling compared to naive and memory B cells.
• Human B cell precursors develop into MZ B cell equivalents in an AKT-dependent manner in vitro.
• CD148 receptor expression is higher in MZ B cells than FO B cells in both mice and humans, correlating with AKT signaling levels.

Conclusions:

• The AKT-FoxO pathway is a conserved mechanism orchestrating MZ B cell development in mammals.
• AKT signaling plays a pivotal role in differentiating MZ B cells from their precursors.
• CD148 serves as a reliable cell surface marker for assessing AKT signaling activity in B cells.