Ptch2 mediates the Shh response in Ptch1-/- cells
Ptch2 mediates the Shh response in Ptch1-/- cells
复制标题
DOI：
10.1242/dev.110056
复制
发表时间：
2014-09-01
期刊：
影响因子：
4.6
通讯作者：
Roelink, Henk
中科院分区：
文献类型：
--
作者：
Alfaro, Astrid C.;Roberts, Brock;Roelink, Henk
Hedgehog (Hh) 信号转导反应由三个关键成分的相互作用调节，包括声波刺猬 (Shh) 配体、其受体 patched 1 (Ptch1) 和通路激活剂 smoothened (Smo)。在Shh通路激活的普遍模型下，Shh与Ptch1（关键Shh受体）的结合导致Ptch1介导的Smo抑制的释放，从而导致Smo激活和随后的Shh反应的细胞自主激活。与该模型一致，Ptch1(-/-)细胞显示出Shh反应的强烈上调。我们发现这种反应可以被Shh 阻断抗体5E1 抑制，这表明Ptch1(-/-) 细胞中的Shh 反应仍然依赖于配体。此外，我们发现Shh在Ptch1(-/-)中引起强烈的反应； Shh(-/-)细胞和Ptch1(-/-)成纤维细胞保留了向Shh迁移的能力，表明Ptch1(-/-)细胞仍然对Shh敏感。发育中的雏鸡神经管中显性失活的 Ptch1 突变体的表达对 Shh 介导的模式没有影响，但 patched 2 (Ptch2) 的显性失活形式的表达引起了 Shh 反应的激活。这表明，在早期发育阶段，Ptch2 发挥抑制 Shh 信号传导的作用。我们发现 Ptch1(-/-); Ptch2(-/-)细胞不能进一步激活Shh反应，表明Ptch2在Ptch1不存在的情况下介导对Shh的反应。
The Hedgehog (Hh) signaling response is regulated by the interaction of three key components that include the sonic hedgehog (Shh) ligand, its receptor patched 1 (Ptch1) and the pathway activator smoothened (Smo). Under the prevailing model of Shh pathway activation, the binding of Shh to Ptch1 (the key Shh receptor) results in the release of Ptch1-mediated inhibition of Smo, leading to Smo activation and subsequent cell-autonomous activation of the Shh response. Consistent with this model, Ptch1(-/-) cells show a strong upregulation of the Shh response. Our finding that this response can be inhibited by the Shh-blocking antibody 5E1 indicates that the Shh response in Ptch1(-/-) cells remains ligand dependent. Furthermore, we find that Shh induces a strong response in Ptch1(-/-); Shh(-/-) cells, and that Ptch1(-/-) fibroblasts retain their ability to migrate towards Shh, demonstrating that Ptch1(-/-) cells remain sensitive to Shh. Expression of a dominant-negative Ptch1 mutant in the developing chick neural tube had no effect on Shh-mediated patterning, but expression of a dominant-negative form of patched 2 (Ptch2) caused an activation of the Shh response. This indicates that, at early developmental stages, Ptch2 functions to suppress Shh signaling. We found that Ptch1(-/-); Ptch2(-/-) cells cannot further activate the Shh response, demonstrating that Ptch2 mediates the response to Shh in the absence of Ptch1.