GLI3-dependent transcriptional repression of Gli1, Gli2 and kidney patterning genes disrupts renal morphogenesis
GLI3-dependent transcriptional repression of Gli1, Gli2 and kidney patterning genes disrupts renal morphogenesis
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DOI：
10.1242/dev.02220
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发表时间：
2006-02-01
期刊：
影响因子：
4.6
通讯作者：
Rosenblum, ND
中科院分区：
文献类型：
--
作者：
Hu, MC;Mo, R;Rosenblum, ND
SHH-SMO-GLI信号通路中的细胞内效应物Gli 3中的截短突变导致人类和小鼠的肾发育不全/发育不良。然而，致病机制尚未明确。在这里，我们报告了SHH-SMO信号转导减少对肾脏形态发生、SHH靶基因表达和GLI结合Shh靶基因的影响。Shh缺乏或环巴明介导的SMO抑制破坏肾器官形成，降低GLI 1和GL 12蛋白的表达，但增加GLI 3抑制剂相对于GLI 3激活剂的表达。Shh缺乏降低了肾模式基因（Pax 2和Sall 1）和细胞周期调节因子（细胞周期蛋白D1和MYCN）的表达。在Shh（-/-）小鼠中消除Gli 3挽救了肾畸形并恢复了Pax 2、Sall 1、细胞周期蛋白D1、MYCN、Gli 1和Gli 2的表达。为了确定SHH-SMO信号传导控制基因表达的机制，我们使用染色质免疫沉淀法测定了GLI蛋白与Shh靶基因中含有GLI共有结合序列的5'侧翼区的结合。在正常胚胎肾组织中，GLI 1和/或GL 12与每个靶基因结合。相比之下，用环巴胺处理胚胎肾外植体降低GLI 1和/或GL 12结合，并诱导GLI 3结合。然而，环巴胺未能降低Gli 1和Gli 2的表达和分支形态发生在Gli 3缺陷的胚胎肾组织。总之，这些结果表明，SHH-SMO信号通过GLI，肾模式和细胞周期调节基因的转录控制，以GLI 3相反的方式控制肾形态发生。
Truncating mutations in Gli3, an intracellular effector in the SHH-SMO-GLI signaling pathway, cause renal aplasia/dysplasia in humans and mice. Yet, the pathogenic mechanisms are undefined. Here, we report the effect of decreased SHH-SMO signaling on renal morphogenesis, the expression of SHH target genes and GLI binding to Shh target genes. Shh deficiency or cyclopamine-mediated SMO inhibition disrupted renal organogenesis, decreased expression of GLI1 and GL12 proteins, but increased expression of GLI3 repressor relative to GLI3 activator. Shh deficiency decreased expression of kidney patterning genes (Pax2 and Sall1) and cell cycle regulators (cyclin D1 and MYCN). Elimination of Gli3 in Shh(-/-) mice rescued kidney malformation and restored expression of Pax2, Sall1, cyclin D1, MYCN, Gli1 and Gli2. To define mechanisms by which SHH-SMO signaling controls gene expression, we determined the binding of GLI proteins to 5' flanking regions containing GLI consensus binding sequences in Shh target genes using chromatin immunoprecipitation. In normal embryonic kidney tissue, GLI1 and/or GL12 were bound to each target gene. By contrast, treatment of embryonic kidney explants with cyclopamine decreased GLI1 and/or GL12 binding, and induced binding of GLI3. However, cyclopamine failed to decrease Gli1 and Gli2 expression and branching morphogenesis in Gli3-deficient embryonic kidney tissue. Together, these results demonstrate that SHH-SMO signaling controls renal morphogenesis via transcriptional control of Gli, renal patterning and cell cycle regulator genes in a manner that is opposed by GLI3.