Hedgehog (Hh) induces signaling by promoting the reciprocal trafficking of its receptor Patched (Ptc) and the signal transducer Smoothened (Smo), which is inhibited by Ptc, at the cell surface. We identified Smurf family E3 ubiquitin ligases as essential for Smo ubiquitylation and cell surface clearance and demonstrated that Smurf family members mediate the reciprocal trafficking of Ptc and Smo in Drosophila melanogaster. G protein–coupled receptor kinase 2 (Gprk2)–mediated phosphorylation of Smurf promoted Smo ubiquitylation by increasing the recruitment of Smurf to Smo, whereas protein kinase A (PKA)–mediated phosphorylation of Smo caused Smurf to dissociate from Smo, thereby inhibiting Smo ubiquitylation. Smo and Ptc competed for the same pool of Smurf family E3 ubiquitin ligases, and Hh promoted Ptc ubiquitylation and degradation by disrupting the association of Smurf family E3 ubiquitin ligases with Smo and stimulating their binding to Ptc. Our study identifies the E3 ubiquitin ligases that target Smo and provides insight into how Hh regulates the reciprocal trafficking of its receptor and signal transducer.

刺猬（Hh）通过在细胞表面促进其受体Patched（Ptc）和受Ptc抑制的信号转导子Smoothened（Smo）的相互运输来诱导信号传导。我们确定蓝精灵家族E3泛素连接酶是Smo泛素化和细胞表面清除所必需的，并证明了蓝精灵家族成员介导果蝇黑腹果蝇Ptc和Smo的相互贩运。G蛋白偶联受体激酶2（Gprk2）介导的Smurf磷酸化通过增加Smurf对Smo的募集而促进Smo泛素化，而蛋白激酶A（PKA）介导的Smo磷酸化导致Smurf与Smo分离，从而抑制Smo泛素化。 。Smo和Ptc竞争相同的Smurf家族E3泛素连接酶库，Hh通过破坏Smurf家族E3泛素连接酶与Smo的结合并刺激它们与Ptc的结合来促进Ptc泛素化和降解。我们的研究鉴定了靶向Smo的E3泛素连接酶，并提供了有关Hh如何调节其受体和信号转导子的相互运输的见解。