Epac1 interacts with importin β1 and controls neurite outgrowth independently of cAMP and Rap1
Epac1 interacts with importin β1 and controls neurite outgrowth independently of cAMP and Rap1
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DOI：
10.1038/srep36370
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发表时间：
2016-11-03
影响因子：
4.6
通讯作者：
Kavelaars, Annemieke
中科院分区：
文献类型：
--
作者：
Baameur, Faiza;Singhmar, Pooja;Kavelaars, Annemieke
由cAMP-1直接激活的交换蛋白（Epac1）是一种cAMP传感器，调节多种细胞功能，包括细胞迁移、增殖和分化。传统上，Epac1被认为是通过与cAMP结合而发挥作用，导致Epac1的构象改变，并在质膜（PM）上积累，从而激活Rap1。为了寻找Epac1活性的调节因子，我们在这里表明，导入β 1 （imp β 1）是Epac1的结合伙伴，可以阻止Epac1的PM积累。我们证明，在缺乏imp β 1的情况下，内源性和过表达的Epac1在PM积聚。此外，激动剂诱导的Epac1的PM易位导致Epac1与imp β 1分离。在没有imp β 1的情况下，Epac1在PM的定位需要其DEP结构域的残基R82。值得注意的是，在缺乏imp β 1的情况下，Epac1的PM积累不需要cAMP与Epac1结合，也不会导致Rap1激活。功能上，Epac1的PM积累，缺乏cAMP结合的Epac1突变体，或连接到PM的Epac1突变体，足以抑制神经突的生长。综上所述，我们发现Epac1在PM处具有与camp无关的功能，并证明imp β 1控制Epac1的亚细胞定位。
Exchange protein directly activated by cAMP-1 (Epac1) is a cAMP sensor that regulates multiple cellular functions including cellular migration, proliferation and differentiation. Classically, Epac1 is thought to exert its effects through binding of cAMP leading to a conformational change in Epac1 and its accumulation at the plasma membrane (PM) where it activates Rap1. In search for regulators of Epac1 activity, we show here that importin beta 1 (imp beta 1) is an Epac1 binding partner that prevents PM accumulation of Epac1. We demonstrate that in the absence of imp beta 1, endogenous as well as overexpressed Epac1 accumulate at the PM. Moreover, agonist-induced PM translocation of Epac1 leads to dissociation of Epac1 from imp beta 1. Localization of Epac1 at the PM in the absence of imp beta 1, requires residue R82 in its DEP domain. Notably, the PM accumulation of Epac1 in the absence of imp beta 1 does not require binding of cAMP to Epac1 and does not result in Rap1 activation. Functionally, PM accumulation of Epac1, an Epac1 mutant deficient in cAMP binding, or an Epac1 mutant tethered to the PM, is sufficient to inhibit neurite outgrowth. In conclusion, we uncover a cAMP-independent function of Epac1 at the PM and demonstrate that imp beta 1 controls subcellular localization of Epac1.