Regulation of Smoothened by Drosophila G-protein-coupled receptor kinases
Regulation of Smoothened by Drosophila G-protein-coupled receptor kinases
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DOI：
10.1016/j.ydbio.2009.10.014
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发表时间：
2010-01-01
影响因子：
2.7
通讯作者：
Hipfner, David R.
中科院分区：
文献类型：
--
作者：
Cheng, Shuofei;Maier, Dominic;Hipfner, David R.
Hedgehog(HH)信号通路在调节多种组织的发育和动态平衡方面起着保守和重要的作用。胞质信号转导是由G蛋白偶联受体(GPCR)家族成员Smoothens(Smo)启动的，其水平和活性受HH受体补丁(PTC)调节。当HH与PTC结合后，PTC介导的Smo抑制被解除，导致Smo激活、表面积聚和下游信号转导。我们发现，果蝇Smo蛋白在HH反应的视盘细胞中的下调依赖于G蛋白偶联受体激酶2(Gprk2)的活性。通过分析功能缺失和缺失的表型，我们提供了Gprk2在激活后促进Smo内化的证据，很可能是通过直接磷酸化。在gprk2突变体中，依赖PTC的Smo积累调节是正常的，这表明Gprk2和PTC通过不同的机制下调Smo。最后，我们发现果蝇G蛋白偶联受体激酶同源基因Gprk1和Gprk2都以部分冗余的方式促进HH信号转导。我们的结果表明，Smo在体内受到不同的PTC依赖和Gprk2依赖的转运机制的调节，类似于GPCRs的结构性和活性依赖性调节。G蛋白偶联受体激酶的活性对于有效的下游信号也很重要。(C)2009 Elsevier Inc.保留所有权利。
The Hedgehog (Hh) signaling pathway plays a conserved and essential role in regulating development and homeostasis of numerous tissues. Cytoplasmic signaling is initiated by Smoothened (Smo), a G-protein-coupled receptor (GPCR) family member, whose levels and activity are regulated by the Hh receptor Patched (Ptc). in response to Hh binding to Ptc, Ptc-mediated repression of Smo is relieved, leading to Smo activation, surface accumulation, and downstream signaling. We find that downregulation of Drosophila Smo protein in Hh-responding imaginal disc cells is dependent on the activity of G-protei n-coupled receptor kinase 2 (Gprk2). By analyzing gain- and null loss-of-function phenotypes, we provide evidence that Gprk2 promotes Smo internalization subsequent to its activation, most likely by direct phosphorylation. Ptc-dependent regulation of Smo accumulation is normal in gprk2 mutants, indicating that Gprk2 and Ptc downregulate Smo by different mechanisms. Finally, we show that both Drosophila G-protein-coupled receptor kinase orthologues, Gprk1 and Gprk2, act in a partially redundant manner to promote Hh signaling. Our results suggest that Smo is regulated by distinct Ptc-dependent and Gprk2-dependent trafficking mechanisms in vivo, analogous to constitutive and activity-dependent regulation of GPCRs. G-protein-coupled receptor kinase activity is also important for efficient downstream signaling. (C) 2009 Elsevier Inc. All rights reserved.