Stepwise progression of β-selection during T cell development involves histone deacetylation.

Area of Science:

• Immunology
• Cell Biology
• Molecular Biology

Background:

• T cell receptor (TCR) development is essential for adaptive immunity.
• The β-selection checkpoint is a critical quality control step during T cell development.
• The precise mechanisms governing cell fate decisions at the β-selection checkpoint remain unclear.

Purpose of the Study:

• To elucidate the molecular mechanisms coordinating cell fate determination during T cell β-selection.
• To investigate the role of histone deacetylase 6 (HDAC6) inhibition in T cell development.
• To identify novel stages and signaling pathways involved in the β-selection checkpoint.

Main Methods:

• Utilized ACY1215, a selective inhibitor of histone deacetylase 6 (HDAC6).
• Analyzed T cell development and characterized gene expression profiles.
• Investigated the role of TCR co-receptors (CD28, CD2) and signaling molecules (CD5, Lef1).

Main Results:

• ACY1215 disrupted the β-selection checkpoint, revealing a previously uncharacterized stage (DN3b^Pre).
• This stage is characterized by the sequential upregulation of TCR co-receptors CD28 and CD2.
• Upregulation of CD5 and Lef1 within DN3b^Pre correlates with pre-TCR signaling strength and cell proliferation.

Conclusions:

• A refined model of β-selection is proposed, highlighting a critical DN3b^Pre stage.
• Coordinated expression of pre-TCR, CD28, CD5, and Lef1 modulates TCR signaling strength.
• Successful progression through this stage, marked by CD2 expression, is necessary for exiting the β-selection checkpoint and cell survival.