The role of BCL11B in T lineage fate during human thymopoiesis and pluripotent stem cell differentiation

摘要/总结 使用患者源性（自体）产品进行过继性T细胞移植的功能限制和后勤挑战 细胞疗法促使人们探索从自体产生的“现成”T细胞的通用来源， 更新PSC，其可以容易地进行基因工程以增强功能并无限制地扩增。 然而，目前的PSC分化系统的特征在于低T细胞输出和同时产生 先天性淋巴样细胞（ILC）。我们的初步研究表明，T细胞特化的最早阶段 在PSC分化过程中观察到的分化和定型不能完全概括正常人胸腺生成或 使用永久性造血干细胞和祖细胞（HSPC）启动T细胞发育的体外模型。 这项计划的目的是了解正常人和正常人之间的细胞和分子差异。 PSC衍生的T细胞发育，重点是转录因子BCL 11B的作用。T细胞 来自微环境的notch信号触发一系列转录后， 启动HSPC中T细胞系程序的事件;这些事件首先产生早期胸腺祖细胞（ETP） （T谱系特化），然后在多能ETP（T谱系）中消除替代（非T）谱系程序 承诺）。BCL 11B是这两个过程的关键调节剂。我们公布的初步数据显示 与小鼠模型相反，BCL 11 B在人胸腺生成过程中对T细胞特化至关重要， 启动几种T细胞基因的表达。此外，当BCL 11B在脐带血HSPC中过表达时， 即使在没有notch信号传导的情况下，T细胞程序也更快速和有效地启动。人惊讶 关于T细胞谱系是如何从PSC产生的知之甚少。通过scRNA-Seq分析， 鉴定的候选ETP和它们的直接后代，因为它们从PSC衍生的造血中出现。我们 假设启动T细胞程序的罕见PSC衍生的ETP在功能上和 在转录上不同于胸腺中的ETP，并且这些内在差异是有害的。 用于从PSC产生常规T细胞。此外，我们提出，染色质重塑诱导 通过BCL 11B介导T谱系特化和常规T细胞与 先天淋巴途径具体来说，我们将：1。定义PSC期间产生的最早T谱系祖细胞 差异化; 2.确定PSC-ATO和原发性肿瘤中T细胞特化的表观遗传基础 胸腺生成;和3.定义BCL 11B如何影响传统T和先天谱系命运选择。这些研究 将产生关于T细胞分化的新的机制见解，这对PSC衍生的 T细胞免疫疗法

ABSTRACT/SUMMARY The functional limitations and logistical challenges of using patient-derived (autologous) products for adoptive T cell therapy has prompted the exploration of a universal source of “off-the-shelf” T cells generated from self- renewing PSCs which can be readily genetically engineered to enhance function and expanded without limit. However current PSC differentiation systems are characterized by low T cell output and concurrent production of innate lymphoid cells (ILCs). Our preliminary studies suggest that the earliest stages of T cell specification and commitment seen during PSC differentiation do not fully recapitulate either normal human thymopoiesis or in vitro models that use definitive hematopoietic stem and progenitor cells (HSPC) to initiate T cell development. The goal of this proposal is to understand the cellular and molecular differences between normal and PSC-derived T cell development, with a focus on the role of the transcription factor BCL11B. T cells are generated in the thymus after notch signaling from the microenvironment triggers a series of transcriptional events that initiate the T-lineage program in HSPCs; these events first produce early thymic progenitors (ETPs) (T lineage specification) and then extinguish alternative (non-T) lineage programs in multipotent ETPs (T lineage commitment). BCL11B is a critical regulator of both of these processes. Our published and preliminary data show that, in contrast to the mouse model, BCL11B is essential for T cell specification during human thymopoiesis and initiates the expression of several T-cell genes. Moreover, when BCL11B is overexpressed in cord blood HSPCs, the T cell program is launched more rapidly and efficiently, even in the absence of notch signaling. Surprisingly little is known about how the T cell lineage is generated from PSCs. Through scRNA-Seq analysis we have identified candidate ETPs and their immediate progeny as they emerge from PSC-derived hematopoiesis. We hypothesize that the rare PSC-derived ETPs in which the T cell program is launched are functionally and transcriptionally different from ETPs in the thymus, and that these intrinsic differences are detrimental for the generation of conventional T cells from PSCs. Further, we propose that chromatin remodeling induced by BCL11B mediates both T lineage specification and the fate decisions between the conventional T cell and innate lymphoid pathways. Specifically we will: 1. Define the earliest T lineage progenitors generated during PSC differentiation; 2. Determine the epigenetic underpinnings of T-cell specification in PSC-ATOs and in primary thymopoiesis; and 3. Define how BCL11B affects conventional T and innate lineage fate choices. These studies will yield new mechanistic insights about T-cell differentiation that are critical for the development of PSC-derived T-cell immunotherapies.