Anchoring of both PKA and 14-3-3 inhibits the Rho-GEF activity of the AKAP-Lbc signaling complex
Anchoring of both PKA and 14-3-3 inhibits the Rho-GEF activity of the AKAP-Lbc signaling complex
复制标题
DOI：
10.1038/sj.emboj.7600287
复制
发表时间：
2004-07-21
期刊：
影响因子：
11.4
通讯作者：
Pansier, L
中科院分区：
文献类型：
--
作者：
Diviani, D;Abuin, L;Pansier, L
A-激酶锚定蛋白(AKAPs)将cAMP调节的蛋白激酶(PKA)靶向其生理底物。我们最近发现了一种新的锚定蛋白，称为AKAP-LBC，它既可以作为PKA靶向蛋白，也可以作为RhoA的鸟嘌呤核苷酸交换因子(Gef)。我们证明了异源三聚体G蛋白G12的α亚基对AKAP-LBC Rho-Global的活性有刺激作用。在此，我们鉴定了14-3-3是一个与AKAP-LBC相互作用的新的调节蛋白。CAMP细胞浓度的升高激活了锚定在AKAP-LBC上的PKA全酶，使丝氨酸1565上的锚定蛋白磷酸化。这种磷酸化事件诱导了14-3-3的募集，从而抑制了AKAP-LBC的Rho-Global活性。与野生型蛋白相比，不能与PKA或14-3-3相互作用的AKAP-LBC突变体表现出更高的基础Rho-gef活性。这表明，在基础条件下，14-3-3使AKAP-LBC处于失活状态。因此，虽然已知Galpha12可以刺激AKAP-LBC的活性，但在本研究中，我们证明了PKA和14-3-3的锚定都抑制了它的活性。
A-kinase anchoring proteins (AKAPs) target the cAMP-regulated protein kinase (PKA) to its physiological substrates. We recently identified a novel anchoring protein, called AKAP-Lbc, which functions as a PKA-targeting protein as well as a guanine nucleotide exchange factor (GEF) for RhoA. We demonstrated that AKAP-Lbc Rho-GEF activity is stimulated by the alpha subunit of the heterotrimeric G protein G12. Here, we identified 14-3-3 as a novel regulatory protein interacting with AKAP-Lbc. Elevation of the cellular concentration of cAMP activates the PKA holoenzyme anchored to AKAP-Lbc, which phosphorylates the anchoring protein on the serine 1565. This phosphorylation event induces the recruitment of 14-3-3, which inhibits the Rho-GEF activity of AKAP-Lbc. AKAP-Lbc mutants that fail to interact with PKA or with 14-3-3 show a higher basal Rho-GEF activity as compared to the wild-type protein. This suggests that, under basal conditions, 14-3-3 maintains AKAP-Lbc in an inactive state. Therefore, while it is known that AKAP-Lbc activity can be stimulated by Galpha12, in this study we demonstrated that it is inhibited by the anchoring of both PKA and 14-3-3.