The Wilms tumor suppressor Wt1 promotes cell adhesion through transcriptional activation of the α4integrin gene
The Wilms tumor suppressor Wt1 promotes cell adhesion through transcriptional activation of the α4integrin gene
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DOI：
10.1074/jbc.m602668200
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发表时间：
2006-10-20
影响因子：
4.8
通讯作者：
Scholz, Holger
中科院分区：
文献类型：
--
作者：
Kirschner, Karin M.;Wagner, Nicole;Scholz, Holger
通过特异性粘附分子的细胞-基质相互作用是器官发育过程中的关键步骤。此外，细胞粘附受体的下调可能促进肿瘤的侵袭和转移。我们在这里表明，肾母细胞瘤抑制因子Wt 1，这是必要的心外膜，冠状血管，泌尿生殖系统和其他组织的正常发育，激活α 4整合素基因的转录。通过电泳迁移率变动分析和染色质免疫沉淀证实了转录活性的Wt 1（-KTS）形式与近端α 4整合素启动子的结合。通过瞬时共转染Wt 1（-KTS）表达质粒，可显著激活含有类似于1.9kb人α 4整合素基因启动子的报告基因构建体。在α 4整合素基因近端启动子中的两个确定的Wt 1（-KTS）结合基序中引入突变消除了这种刺激作用。在稳定表达Wt 1（-KTS）蛋白的人胚肾293细胞中，内源性α 4整合素转录物增加了3倍以上。Wt 1过表达细胞表现出增强的粘附α 4整合素配体血管细胞粘附分子-1后，废除与抑制性α 4整合素抗体孵育。免疫荧光双标显示Wt 1和α 4整合素在小鼠胚胎心外膜共定位。在具有纯合Wt 1缺陷（Wt 1（-/-））的胚胎中，α 4整合素的心脏表达显著降低。这些结果表明，Wt 1可以通过增强α 4整合素的表达来支持细胞粘附。Wt 1（-KTS）对α 4整合素基因的转录激活可能有助于发育中胚胎心外膜和其他组织的正常形成。
Cell-matrix interaction through specific adhesion molecules is a critical step during organ development. In addition, down-regulation of cell adhesion receptors may promote tumor invasion and metastasis. We show here that the Wilms tumor suppressor Wt1, which is necessary for normal development of the epicardium, coronary vessels, genitourinary system, and other tissues, activates transcription of the alpha 4integrin gene. Binding of the Wt1(-KTS) form, which is transcriptionally active, to the proximal alpha 4integrin promoter was demonstrated by electrophoretic mobility shift assay and chromatin immunoprecipitation. A reporter construct harboring similar to 1.9 kb of the human alpha 4integrin gene promoter was activated significantly by transient co-transfection of a Wt1(-KTS) expression plasmid. Introducing mutations in two identified Wt1(-KTS) binding motifs in the proximal promoter of the alpha 4integrin gene abrogated this stimulatory effect. Endogenous alpha 4integrin transcripts were increased more than 3-fold in human embryonic kidney 293 cells with stable expression of the Wt1(-KTS) protein. Wt1-overexpressing cells showed augmented adhesion to the alpha 4integrin ligand vascular cell adhesion molecule-1 that was abolished upon incubation with an inhibitory alpha 4integrin antibody. Double immunofluorescent staining revealed co-localization of Wt1 and alpha 4integrin in the developing epicardium of mouse embryos. Cardiac expression of alpha 4integrin was reduced significantly in embryos with a homozygous Wt1 defect (Wt1(-/-)). These findings demonstrate that Wt1 can support cell adhesion through enhanced expression of alpha 4integrin. This transcriptional activation of the alpha 4integrin gene by Wt1(-KTS) might contribute to normal formation of the epicardium and other tissues in the developing embryo.