Davies R, Moore A, Schedl A, Bratt E, Miyahawa K, Ladomery M, Miles C, Menke A, van Heyningen V, Hastie N
Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh, United Kingdom.
Cancer Res. 1999 Apr 1;59(7 Suppl):1747s-1750s; discussion 1751s.
Wilms' tumor is a childhood kidney tumor that is a striking example of the way that cancer may arise through development gone awry. A proportion of these tumors develop as a result of the loss of function mutations in the Wilms' tumor suppressor gene, WT1. Inherited mutations in the WT1 gene can lead to childhood kidney cancer, severe gonadal dysplasia, and life-threatening hypertension. Knockouts show that the gene is essential for the early stages of kidney and gonad formation. These tissues are completely absent in null mice. The WT1 gene encodes numerous protein isoforms, all of which share four zinc fingers. There is a large body of evidence supporting the notion that WT1 is a transcription factor, particularly a transcriptional repressor. Recently, however, we obtained evidence that WT1 colocalizes and is physically associated with splice factors. What is more, one alternative splice isoform of WT1 containing three amino acids, Lys-Thr-Ser (KTS; inserted between zinc fingers 3 and 4) is preferentially associated with splice factors, whereas the other alternative splice version, lacking these three amino acids, preferentially associates with the transcriptional apparatus. Both genetic and evolutionary considerations suggest that these two different forms of the protein have different functions. We will discuss recent evidence to further implicate WT1 in splicing. Our results raise the possibility that regulation of splicing is a crucial factor in the development of the genitourinary system, and that tumors may arise through aberrant splicing. To pursue the regulation and function of WT1 in whole animals, we have been introducing the human gene and large flanking regions cloned in yeast artificial chromosomes directly into mice. These studies have allowed us to dissect the function of WT1 at late as well as at early stages in organogenesis and to identify new sites and surprising new potential functions for the gene.
肾母细胞瘤是一种儿童期肾脏肿瘤，它是癌症可能因发育异常而产生的一个典型例子。这些肿瘤中有一部分是由于肾母细胞瘤抑癌基因WT1功能丧失性突变而发生的。WT1基因的遗传性突变可导致儿童期肾癌、严重的性腺发育不全和危及生命的高血压。基因敲除实验表明，该基因对肾脏和性腺形成的早期阶段至关重要。在基因敲除小鼠中，这些组织完全缺失。WT1基因编码多种蛋白质异构体，它们都共有四个锌指结构。有大量证据支持WT1是一种转录因子，尤其是转录抑制因子这一观点。然而，最近我们获得的证据表明，WT1与剪接因子共定位且存在物理关联。此外，WT1的一种包含三个氨基酸（赖氨酸 - 苏氨酸 - 丝氨酸，即KTS；插入在锌指3和4之间）的可变剪接异构体优先与剪接因子相关联，而另一种缺少这三个氨基酸的可变剪接版本则优先与转录装置相关联。遗传学和进化方面的考虑都表明，这两种不同形式的蛋白质具有不同的功能。我们将讨论最近的证据，以进一步证明WT1与剪接有关。我们的研究结果提出了一种可能性，即剪接调控是泌尿生殖系统发育的关键因素，并且肿瘤可能通过异常剪接产生。为了研究WT1在整个动物体内的调控和功能，我们一直将克隆在酵母人工染色体中的人类基因及其大片侧翼区域直接导入小鼠体内。这些研究使我们能够剖析WT1在器官发生后期以及早期阶段的功能，并确定该基因的新位点和令人惊讶的新潜在功能。
