Transcriptional regulation in helper versus cytotoxic-lineage decision.

The mechanism underlying the lineage decision made by CD4(+)CD8(+) double-positive (DP) thymocytes that give rise to two T lymphocyte subset with distinct functionalities, that is, helper and cytotoxic T cells, remains a major issue in immunology. The lineage decision process involves several phases and terminates when cells loose their developmental plasticity to become the alternate lineage. A detailed picture of the transcription factor network governing helper versus cytotoxic-lineage decision has recently emerged. Studies published only past year provided new insights into how the expression of ThPOK, a central transcription factor for helper T cell development, is regulated. It has now become evident that an antagonistic interplay between ThPOK and Runx transcription factor complexes plays an essential role in thwarting an alternate fate during the commitment process.