Molecular function of the T-box transcription factors TBX2 and TBX3 in the development and maintenance of the epithelial lining of the urinary tract in the mouse

上尿路系统、肾脏和输尿管，以及下尿路系统、膀胱和尿路的组成部分，通过胚胎发育过程中高度整合的图案化、增殖和分化程序，从不同的上皮和间充质组织原基发育而来。尽管在人类新生儿中经常发生先天性器官系统异常(CAKUT)，但我们只知道调控正常发育的一小部分基因和突变时导致形态异常的基因。我们在第一个资助期的工作确定了密切相关的T-box转录因子TBX2和TBX3是小鼠上尿路和下尿路上皮原基发育的新的和必要的调节因子：Tbx2和TBX3在肾管、输尿管芽、输尿管和集合管系统的上皮中共同表达。在这些组织中，Tbx2或Tbx3的条件性缺失与部分输尿管和巨输尿管相关，这两个基因的联合缺失导致了一系列CAKUT样变化，包括巨输尿管、输尿管/肾发育不全和出生时肾发育不良/发育不良伴囊性扩张。我们检测到输尿管上皮和集合管系统的细胞分化完全丧失，并发现分子变化表明输尿管中的集合管程序过早和异位激活。Tbx2和TBX3在发育和成熟的膀胱上皮细胞中也共同表达，是分层和尿路上皮分化所必需的。在第二个资助期，我们希望结合组织特异性基因打靶和体内错误表达研究，以及小规模和大规模的转录和蛋白质组分析，破译上尿路和下尿路上皮衬里中TBX2/TBX3在发育和动态平衡中的分子功能和调控。具体地说，我们希望-定义与这些组织和发育环境中Tbx2/TBX3功能的丧失和获得相关的分子变化-确定它们转录活性的直接靶点，并表征这些基因对观察到的表型变化的功能贡献-表征这两个因子在其中发挥作用的调节模块，以及-识别和表征对TBX2和TBX3转录抑制活性重要的蛋白质相互作用伙伴。我们期待从这些实验中对上、下尿路尿路上皮发育和动态平衡的分子控制、两个重要转录调节因子的分子功能以及在人类患者中观察到的先天性尿路异常的病因学有新的见解。

The components of the upper urinary system, the kidneys and the ureters, and of the lower urinary system, the bladder and the urethra, develop from distinct epithelial and mesenchymal tissue primordia through highly integrated programs of patterning, proliferation and differentiation during embryogenesis. Despite the frequent occurrence of congenital anomalies in this organ system (CAKUT) in human newborns, we know only a fraction of the genes that regulate normal development and account for morphological anomalies when mutated, respectively. Our work in the first funding period characterized the closely related T-box transcription factors TBX2 and TBX3 as novel and essential regulators of the development of the epithelial primordia of both the murine upper and lower urinary tract: Tbx2 and Tbx3 are coexpressed in the epithelium of the nephric duct, the ureteric bud, the ureter and collecting duct system. Conditional deletion of Tbx2 or Tbx3 in these tissues is associated with partial hydroureter and megaureter, combined deletion of both genes results in a fully penetrant spectrum of CAKUT-like changes including megaureter, ureter/kidney agenesis and renal hypo/dysplasia with cystic dilations at birth. We detected a complete loss of cyto-differentiation of the epithelium of the ureter and collecting duct system, and found molecular changes indicating a premature and ectopic activation of a collecting duct program in the ureter. Tbx2 and Tbx3 are also coexpressed in the epithelium of the developing and mature bladder, and are required therein for stratification and urothelial differentiation.In a second funding period we want to decipher the molecular function and regulation of TBX2/TBX3 in the epithelial lining of the upper and lower urinary tract both in development and homeostasis using a combination of tissue-specific gene targeting and misexpression studies in vivo, and small and large-scale transcriptomic and proteomic assays. Specifically, we wish to- define the molecular changes associated with loss and gain of Tbx2/Tbx3 function in these tissues and developmental contexts- identify the direct targets of their transcriptional activity and characterize the functional contribution of these genes to the observed phenotypic changes- characterize the regulatory module in which the two factors act and- identify and characterize protein interaction partners important for the transcriptional repression activity of TBX2 and TBX3. We expect from these experiments new insight into the molecular control of upper and lower urinary tract urothelial development and homeostasis, into the molecular function of two important transcriptional regulators, and into the etiology of congenital anomalies of the urinary tract observed in human patients.