Functional analysis of WT1 mutation in acute myeloid leukemia

Wilms肿瘤基因WT1最初是作为儿童Wilms肿瘤的抑癌基因分离出来的。该基因在造血祖细胞和白血病中表达。探讨WT1在白血病发生中的作用。我们对白血病进行了突变分析。WT1突变在急性髓系白血病中发现，而在其他类型的白血病中未发现。此外。WT1突变与预后不良相关，提示WT1功能障碍可能导致白血病的进展。一些证据表明WT1可能是一个转录调节因子。目前已有20多个基因被认为是WT1的转录靶点。我们制备了WT1突变纯合子胚胎干细胞，并利用DNA阵列技术比较了野生型和双敲除型胚胎干细胞的表达模式。我们无法检测到WT1候选靶点表达模式的变化。这一发现表明，这些靶点在体内可能不受WT1的转录调节。这些基因是通过不反映生理相互作用的人工方法鉴定的。由于已经确定WT1在体内是物理上相关的剪接因子，因此很可能WT1的功能是由其转录后表达控制介导的。

Wilms' tumor gene WT1 was originally isolated as a tumor suppressor for childhood Wilms' tumor. The gene is expressed in hematopoietic progenitor cells and leukemia. To investigate the role for WT1 in leukemogenesis. we performed mutation analysis in leukemia. WT1 mutation was found in acute myeloid leukemia but not in other types of leukemia. Furthermore. WT1 mutation was associated with poor prognosis, suggesting that WT1 dysfunction may lead to the progression of leukemia.Several lines of evidence suggest that WT1 may be a transcriptional regulator. More than 20 genes have been proposed as transcriptional targets for WT1. We generated ES cells homozygous for WT1 mutation and compared expression pattern between wild-type and double-knockout ES cells using the DNA array technique. We could not detect the change of the expression pattern of the candidate targets for WT1. This finding suggests that the proposed targets may not be transcriptionally regulated by WT1 in vivo. These genes were identified by artificial methods that did not reflect physiological interactions. Since it is well established that WT1 is physically associated splice factors in vivo, it is highly likely that WT1 function is mediated by its, posttranscriptional expression control.