The RhoA transcriptional program in pre-T cells

The GTPase RhoA is essential for the development of pre‐T cells in the thymus. To investigate the mechanisms used by RhoA to control thymocyte development we have used Affymetrix gene profiling to identify RhoA regulated genes in T cell progenitors. The data show that RhoA plays a specific and essential role in pre‐T cells because it is required for the expression of transcription factors of the Egr‐1 and AP‐1 families that have critical functions in thymocyte development. Loss of RhoA function in T cell progenitors causes a developmental block that pheno‐copies the consequence of losing pre‐TCR expression in Recombinase gene 2 (Rag2) null mice. Transcriptional profiling reveals both common and unique gene targets for RhoA and the pre‐TCR indicating that RhoA participates in the pre‐TCR induced transcriptional program but also mediates pre‐TCR independent gene transcription.