Identification of Novel Epigenetic Regulators of lymphocyte Development

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Project Summary/Abstract T cells play a central role in immunity and are of great therapeutic importance. Studies on T cell development provide direct insights into the pathophysiology of a wide variety of diseases and can facilitate adoptive T cell immunotherapies. Though a large effort has been made to identify pathways that regulate T cell differentiation, these studies have mostly focused on secreted proteins, cell surface receptors, and transcription factors known to directly drive developmental processes. Recently, we discovered that manipulation of an epigenetic regulator of lymphoid potential promotes the generation of mature, functional T cells from human induced pluripotent stem cells (iPSCs), demonstrating an important role for epigenetic modulators in T cell development and function. To date, the epigenetic regulation of T cell development remains elusive. In this application, we propose to test the hypothesis that iPSCs provide a platform to identify novel mechanisms regulating T cell development, and new insights into epigenetic regulations of T cell differentiation can be used to facilitate the generation of more robust iPSC-T cells for adoptive T cell immunotherapy. Previously, we have established a stroma-free differentiation system that faithfully recapitulates T cell development in culture. In Aim 1, we will perform small molecule screens at different stages of iPSC- T cell differentiation to discover new epigenetic regulators that can affect lymphoid specification and T cell maturation. We have provided a proof-of-concept by conducting a pilot screen using a library of small molecules that modulate the activity of epigenetic modification enzymes. The screen identified several epigenetic modulators, such as histone methyltransferase G9a, that promote T cell fate commitment. In Aim 2, we will transition our study to mechanistically examine how epigenetic regulations govern lymphocyte fate decisions via modulating chromatin structure. The impact of epigenetic modulators, including G9a, on lymphopoiesis will be probed in both iPSC-derived blood cells and zebrafish models. Lastly, Aim 3 will focus on using small molecule-mediate epigenetic modulation to facilitate the production of mature iPSC-T cells with enhanced function. Success in the proposed study will not only improve our understanding of the molecular mechanisms underlying the formation of immune cells but also open new avenues for stem cell-based immunotherapies. The career development award will allow me to develop new skills necessary to fulfill the proposed goals and foster my development into an independent investigator.