Dual Phosphorylation of Suppressor of Fused (Sufu) by PKA and GSK3β Regulates Its Stability and Localization in the Primary Cilium
Dual Phosphorylation of Suppressor of Fused (Sufu) by PKA and GSK3β Regulates Its Stability and Localization in the Primary Cilium
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DOI：
10.1074/jbc.m110.217604
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发表时间：
2011-04-15
影响因子：
4.8
通讯作者：
Cheng, Steven Y.
中科院分区：
文献类型：
--
作者：
Chen, Yan;Yue, Shen;Cheng, Steven Y.
融合抑制因子(Sufu)是Sonic Hedgehog(Shh)通路的重要负调控因子，但对Sufu本身的正常调控知之甚少。在这里，我们报道了Sufu在Ser-342和Ser-346分别被GSK3β和cAMP依赖的蛋白激酶A(PKA)磷酸化，在这个双重位置的磷酸化稳定了Sufu对抗Shh信号诱导的降解。我们进一步证明，Sufu在初级纤毛中的定位是由Shh信号诱导的，并且是磷酸化的Sufu和总Sufu的周转所必需的。用PKA抑制剂干扰Sufu的磷酸化，或用丙氨酸取代Ser-346，用天冬氨酸取代Ser-342和Ser-346，延长了Sufu在纤毛中的停留时间。最后，Gli2/3的纤毛定位也需要Smo，并且类似地受到PKA活性的扰动或双重Sufu磷酸化位点突变的影响。因此，Shh可能在与Gli2/3的复合体中诱导磷酸化Sufu进入初级纤毛，而去磷酸化触发逆行输出，使Sufu被泛素-蛋白酶体系统降解。
Suppressor of fused (Sufu) is an essential negative regulator of the sonic hedgehog (Shh) pathway, but little is known about how Sufu itself is normally regulated. Here, we report that Sufu is phosphorylated at Ser-342 and Ser-346 by GSK3 beta and cAMP-dependent protein kinase A (PKA), respectively, and phosphorylation at this dual site stabilizes Sufu against Shh signaling-induced degradation. We further show that localization of Sufu in the primary cilium is induced by Shh signaling and is required for the turnover of both phosphorylated and total Sufu. Perturbing Sufu phosphorylation with PKA inhibitors or replacing Ser-346 with alanine reduced the stay and replacing Ser-342 and Ser-346 with aspartic acid prolonged the stay of Sufu in the cilia. Finally, ciliary localization of Gli2/3 also required Smo and was similarly influenced by perturbations of PKA activity or mutations at the dual Sufu phosphorylation site. Thus, Shh likely induced trafficking of phospho-Sufu into the primary cilium in a complex with Gli2/3, and dephosphorylation triggered a retrograde export, allowing Sufu to be degraded by the ubiquitin-proteasome system.