Genome-wide Analysis and Mechanism of T-Box action in Lymphocyte Reprogramming – GAMBLER

Cellular immunity relies on NK and T cell subsets producing cytokines such as IFN-g and TNF-a and is essential for the defense against intracellular pathogens and in the immunosurveillance of tumors. A network of transcription factors (TFs) shared between NK and T cells regulates the acquisition of specific effector functions, such as cytotoxicity and cytokine secretion. Among them, T-box TFs T-bet and Eomes are essential for this differentiation, in part by promoting the response to different cytokines involved in this pathway such as IL-12 and IL-15. The T-box that characterizes this TF family and binds to a consensus sequence shared between the different members, is highly homolog between T-bet and Eomes. This suggests redundancy between both TF that are often co-expressed in NK and T cells. However, a closer look of the expression pattern of these two TFs shows that Eomes often precedes the expression of T-bet. This is the case of conventional NK cells that first express Eomes in the bone marrow before acquiring T-bet expression at the periphery. Our unpublished data also suggest that Eomes precedes T-bet in developing Th1 cells. We hypothesize that Eomes, while promoting commitment to NK or Th1 lineage may allow self renewal while T-bet would favor terminal differentiation. In this model, relative Eomes and T-bet dosages are therefore likely essential to control plasticity versus specialization of lymphocyte subsets. To address this question we propose i) to identify T-bet and Eomes target genes by a combination of Chipseq and RNAseq experiments; ii) to identify TF interacting partners and to characterize the molecular complexes they form using a mass spectrometry approach. Both tasks will take advantage of novel transgenic mouse models where T-bet and Eomes are tagged with affinity purification tags; (iii) to analyze the respective roles of Tbet and Eomes in NK and T cell effector functions and polarization during virus infection or in a model of experimental autoimmune encephalomyelitis, respectively. Altogether, this project should provide new insight into the control of lineage-specific transcriptional programmes, and on the balance between closely related TFs that may operate in a cooperative or antagonistic manner depending on the context. This knowledge may pave the way for the development of novel therapeutic strategies to target cellular immunity in patients with cancer or autoimmunity. Indeed targeting TFs may be very efficient as highlighted by the clinical success of nuclear hormone receptors in the treatment of certain malignancies.