TFE3 and TFEB in CD40L Dependent Murine Autoimmunity and Human Lupus

描述（申请人提供）：CD40L （CD154; gp39）是活化T细胞的关键效应分子，是B细胞产生同型转换抗体和亲和成熟抗体，以及巨噬细胞和树突状细胞活化所必需的。T细胞和B细胞异常表达CD40L被认为驱动多种人类免疫和炎症性疾病，其中系统性红斑狼疮（lupus， SLE）和类风湿性关节炎最为突出。因此，鉴定调节CD40L的因子对于更好地了解这些疾病的病因并可能开发新的治疗策略是必要的。申请人目前的研究表明，相关转录因子TFE3和TFEB是T细胞中CD40L基因表达的生理和直接激活因子。小鼠T细胞中TFE3和TFEB同时失活导致免疫缺陷，类似于由CD40L缺乏症引起的人类超IgM综合征，其特征是对胸腺(T)依赖性抗原的体液免疫反应缺陷，生发中心形成不良，但T非依赖性体液反应正常。来自这些小鼠的T细胞表现出CD40L表达受损。这一发现是通过表达一种转显性阴性（TON）抑制蛋白，通过转基因同时阻断T细胞中的TFE3和TFEB活性而实现的。这是必要的，因为遗传性TFEB缺乏会导致早期胚胎死亡，而且TFE3和TFEB相对于CD40L在功能上是冗余的。拟议研究的目的是进一步确定TFE3和TFEB如何主要通过调控淋巴细胞中CD40L的表达来促进免疫功能和自身免疫性疾病SLE。Aim 1的实验将从分子上确定TFE3和TFEB在小鼠和人T细胞中响应T细胞刺激控制CD40L表达的条件和方法。在Aim 2中，我们将评估TFE3-和tfeb依赖性CD40L表达对狼疮易发MRL/lpr小鼠自身免疫性疾病发展的贡献。在Aim 3中，与负责纽约州立大学-下州狼疮队列的E. Ginzler博士的合作研究将评估TFE3和TFEB在SLE患者淋巴细胞中CD40L异常表达的状态和贡献。这些信息对于充分了解这种免疫病理的分子基础，设计新的治疗策略，并可能确定新的预后标志物非常重要。

DESCRIPTION (provided by applicant): CD40L (CD154; gp39) is a critical effector molecule of activated T cells, necessary for production of isotype switched and affinity matured antibodies by B cells, and macrophage and dendritic cell activation. Abnormal CD40L expression by T and B cells is thought to drive multiple human immunological and inflammatory diseases of which systemic lupus erythematosus (Lupus, SLE) and rheumatoid arthritis are most prominent. Consequently, identification of factors that regulate CD40L is necessary to better understand the etiology of these diseases and possibly develop new treatment strategies. Studies from the applicant now show that the related transcription factors TFE3 and TFEB are physiological and direct activators of CD40L gene expression in T cells. Simultaneous inactivation of TFE3 and TFEB exclusively in T cells in mice resulted in an immune deficiency resembling human Hyper IgM syndrome caused by CD40L deficiency, characterized by defective humoral immune responses to thymus (T)-dependent antigens, poor germinal center formation, but normal T-independent humoral responses. T cells from such mice exhibited impaired CD40L expression. This discovery was possible by expressing a transdominant-negative (TON) inhibitory protein that simultaneously blocked TFE3 and TFEB activity in T cells via transgenesis. This was necessary because genetic TFEB-deficiency causes early embryonic death and TFE3 and TFEB are functionally redundant with respect to CD40L. The purpose of the proposed studies is to further define how TFE3 and TFEB contribute to immune function and the autoimmune disease SLE primarily via their role in governing CD40L expression in lymphocytes. Experiments in Aim 1 will molecularly define the conditions and means by which TFE3 and TFEB control CD40L expression in response to T cell stimulation in mouse and human T cells. In Aim 2, we will evaluate the contribution of TFE3- and TFEB-dependent CD40L expression to the development of autoimmune disease in the Lupus-prone MRL/lpr mouse. In Aim 3, collaborative studies with Dr. E. Ginzler, who runs the SUNY-Downstate Lupus Cohort, will evaluate the status and contribution of TFE3 and TFEB to abnormal CD40L expression in lymphocytes from patients with SLE. Such information is important to fully understand the molecular basis of this immune pathology, to devise new treatment strategies, and possibly identify new prognostic markers.