Tipping the Balance in T Cell Decisions

Science Signaling  12 Feb 2008:
Vol. 1, Issue 6, pp. ec57
DOI: 10.1126/stke.16ec57

In the thymus, key developmental decisions are made that have far-reaching consequences for the immune system, perhaps most notable the commitment of thymocytes to becoming CD4 (helper) or CD8 (cytotoxic) T cells. The transcriptional factor Th-POK commits thymocytes that still express both CD4 and CD8 co-receptors to becoming CD4 T cells, but how is the alternate developmental option generated? Setoguchi et al. find that cells that would otherwise be destined to become CD8+ T cells can be redirected to the CD4 lineage by loss of members of another transcription factor family, Runx. It seems that under normal circumstances, the Runx complex represses Th-POK expression and allows CD8 T cells to emerge.

R. Setoguchi, M. Tachibana, Y. Naoe, S. Muroi, K. Akiyama, C. Tezuka, T. Okuda, I. Taniuchi, Repression of the transcription factor Th-POK by Runx complexes in cytotoxic T cell development. Science 319, 822-825 (2008). [Abstract] [Full Text]