Reciprocal control of G1-phase progression is required for Th-POK/Runx3-mediated CD4/8 thymocyte cell fate decision.

After receiving a TCR-mediated differentiation signal, CD4 and CD8 double-positive thymocytes diverge into CD4 or CD8 single-positive T cells, for which Th-POK and Runx3 have been identified as pivotal transcription factors, respectively. The cross-antagonistic regulation of Th-POK and Runx3 seems to be essential for CD4/8 thymocyte lineage commitment. However, the process for determining which pivotal factor acts dominantly has not been established.

IκBL, a novel member of the nuclear IκB family, inhibits inflammatory cytokine expression.

We previously reported that IκBL prevents experimental autoimmune arthritis. The molecular mechanism, however, still remains unclear. In contrast to four splicing-isoforms of IκBL in human, two isoforms were identified in mouse.