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首页> 外文期刊>EMBO reports >An essential role for Grk2 in Hedgehog signalling downstream of Smoothened
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An essential role for Grk2 in Hedgehog signalling downstream of Smoothened

机译:Grk2在平滑化下游的刺猬信号中的重要作用

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摘要

The G-protein-coupled receptor kinase 2 (adrbk2/GRK2) has been implicated in vertebrate Hedgehog (Hh) signalling based on the effects of its transient knock-down in mammalian cells and zebrafish embryos. Here, we show that the response to Hh signalling is effectively abolished in the absence of Grk2 activity. Zebrafish embryos lacking all Grk2 activity are refractory to both Sonic hedgehog (Shh) and oncogenic Smoothened (Smo) activity, but remain responsive to inhibition of cAMP-dependent protein kinase (PKA) activity. Mutation of the kinase domain abrogates the rescuing activity of grk2 mRNA, suggesting that Grk2 acts in a kinase-dependent manner to regulate the response to Hh. Previous studies have suggested that Grk2 potentiates Smo activity by phosphorylating its C-terminal tail (CTT). In the zebrafish embryo, however, phosphomimetic Smo does not display constitutive activity, whereas phospho-null mutants retain activity, implying phosphorylation is neither sufficient nor necessary for Smo function. Since Grk2 rescuing activity requires the integrity of domains essential for its interaction with GPCRs, we speculate that Grk2 may regulate Hh pathway activity by downregulation of a GPCR.
机译:G蛋白偶联受体激酶2(adrbk2 / GRK2)已基于其在哺乳动物细胞和斑马鱼胚胎中的瞬时敲低效应而参与了脊椎动物的刺猬(Hh)信号传导。在这里,我们显示了在没有Grk2活性的情况下,对Hh信号的反应已被有效消除。缺乏所有Grk2活性的斑马鱼胚胎对Sonic Hedgehog(Shh)和致癌性Smoothened(Smo)活性均不敏感,但仍对抑制cAMP依赖性蛋白激酶(PKA)活性有反应。激酶结构域的突变消除了grk2 mRNA的抢救活性,表明Grk2以激酶依赖性方式调节对Hh的应答。先前的研究表明,Grk2通过磷酸化其C末端尾巴(CTT)来增强Smo活性。然而,在斑马鱼的胚胎中,拟磷酸化的Smo没有显示本构活性,而磷酸无效突变体保留了活性,这意味着磷酸化对于Smo功能既不充分也不是必需的。由于Grk2的抢救活动需要其与GPCR相互作用必不可少的域的完整性,我们推测Grk2可能通过下调GPCR来调节Hh途径的活性。

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