Figure 2.

Key transcription factors enforce quiescence of naïve T cells. The transcription factors TCF-1, BACH2, FOXO1, and KLF2 are strongly expressed in naïve CD8⁺ T cells, where they exert crucial regulatory functions to uphold the naïve state. BACH2, for example, binds to enhancers, limiting the availability of AP-1-binding sites and repressing the expression of T cell receptor (TCR)-responsive genes. Upon activation, BACH2 is phosphorylated, leading to its functional inactivation, as well as being transcriptionally repressed. Removal of BACH2 releases the molecular brake on TCR-driven effector programs.