Adressing the function of the Wilms tumor gene 1 (Wt1) by conditional inactivation in the mouse

Wilms肿瘤蛋白WT1是肾脏发育的重要因素。在人类中，WT1的突变导致肾母细胞瘤，一种儿科肾癌以及影响泌尿生殖道的发育异常。Wt1基因的失活可导致小鼠多器官缺陷，包括性腺、心脏、脾脏、视网膜、嗅觉系统和肾脏发育不全。Wt1基因敲除胚胎的早期致死性阻碍了对Wt1在不同发育阶段的功能特性的深入了解。因此，我们产生了一个条件Wt1等位基因，允许Wt1在时间和空间可控的方式失活。在这里，我们提出了两个不同的实验。首先，我们想探讨WT1影响足细胞发育、分化和维持的分子机制。后者是高度特化的细胞，形成肾小球中血液过滤的基础。Wt1基因在足细胞中特异性缺失，无论是在胚胎发育后期，还是在成年期的不同阶段以可诱导的方式缺失。第二，初步数据表明，WT1在非常早期的发展中发挥了新的作用。我们假设，“母亲”WT 1是必需的，以提供一个环境，为发展中的胚胎执行第一次卵裂。这一假设将通过不同的实验策略进行测试，包括微阵列和利用条件性Wt1基因敲除小鼠。

The Wilms tumor protein WT1 is an essential factor for kidney development. In humans, mutations in WT1 lead to Wilms tumor, a pediatric kidney cancer as well as to developmental anomalies affecting the urogenital tract. Inactivation of Wt1 in mice causes multiple organ defects including anomalies of gonads, heart, spleen, retina, the olfactory system and agenesis of the kidneys. Deeper insights into the functional properties of WT1 during the different phases of development are hampered by the early lethality of Wt1 knockout embryos. We have therefore generated a conditional Wt1 allele that allows the inactivation of Wt1 in a temporally and spatially controllable manner. Here we propose two different experiments. First we want to explore the molecular mechanism by which WT1 affects development, differentiation and maintenance of podocytes. The latter are highly specialized cells that form the basis for blood filtration in the glomerulus of the kidney. Wt1 will be deleted specifically in podocytes either in late embryonic development or in an inducible manner in different stages of adulthood. Second, preliminary data suggest a novel role for WT1 in very early development. We hypothesize that “maternal” WT1 is required in order to provide an environment for the developing embryo to execute the first cleavages. This hypothesis will be tested by different experimental strategies including microarrays and utilization of the conditional Wt1 knockout mouse.