Physical interaction between neurofibromin and serotonin 5-HT6 receptor promotes receptor constitutive activity
Physical interaction between neurofibromin and serotonin 5-HT6 receptor promotes receptor constitutive activity
复制标题
DOI：
10.1073/pnas.1600914113
复制
发表时间：
2016-10-25
影响因子：
11.1
通讯作者：
Morisset-Lopez, Severine
中科院分区：
文献类型：
--
作者：
Nadim, Wissem Deraredj;Chaumont-Dubel, Severine;Morisset-Lopez, Severine
活性G蛋白偶联受体（GPCR）构象不仅由激动剂促进，而且在它们不存在时也发生，导致组成性活性。GPCR与细胞内蛋白质伴侣的结合可能是GPCR组成性活性的机制之一。在这里，我们表明，5-羟色胺6（5-HT 6）受体组成型激活Gs/腺苷酸环化酶途径在各种类型的细胞，包括神经元。组成型活性通过沉默Ras-GT3激活蛋白（Ras-GAP）神经纤维蛋白（5-HT 6受体伴侣）的表达而强烈降低。神经纤维蛋白是由NF 1基因编码的多结构域蛋白，其突变导致1型神经纤维瘤病（NF 1），这是一种以多种良性和恶性神经系统肿瘤和认知缺陷为特征的遗传性疾病。破坏5-HT 6受体与神经纤维蛋白普列克底物蛋白同源（PH）结构域的缔合也抑制受体组成性活性，并且PH结构域表达拯救神经纤维蛋白缺陷细胞中5-HT 6受体操作的cAMP信号传导。此外，携带突变的PH结构域在NF 1患者中鉴定，防止与5-HT 6受体的相互作用，不能拯救神经纤维蛋白耗尽细胞中的受体组成型活性。与WT小鼠相比，Nf 1（+/-）小鼠前额叶皮层cAMP反应元件结合蛋白（CREB）的磷酸化强烈降低，这进一步支持了神经纤维蛋白在天然受体引发的激动剂非依赖性Gs信号传导中的作用。此外，全身给予5-HT 6受体反向激动剂可降低WT小鼠前额叶皮质中CREB的磷酸化，但Nf 1（+/-）小鼠则不然。总的来说，这些研究结果表明，破坏5-HT 6受体-神经纤维蛋白相互作用，防止激动剂非依赖性5-HT 6受体操作的cAMP信号在前额叶皮层，一个影响，可能是神经纤维瘤患者神经元异常的基础。
Active G protein-coupled receptor (GPCR) conformations not only are promoted by agonists but also occur in their absence, leading to constitutive activity. Association of GPCRs with intracellular protein partners might be one of the mechanisms underlying GPCR constitutive activity. Here, we show that serotonin 5 hydroxytryptamine 6 (5-HT6) receptor constitutively activates the Gs/adenylyl cyclase pathway in various cell types, including neurons. Constitutive activity is strongly reduced by silencing expression of the Ras-GTPase activating protein (Ras-GAP) neurofibromin, a 5-HT6 receptor partner. Neurofibromin is a multidomain protein encoded by the NF1 gene, the mutation of which causes Neurofibromatosis type 1 (NF1), a genetic disorder characterized by multiple benign and malignant nervous system tumors and cognitive deficits. Disrupting association of 5-HT6 receptor with neurofibromin Pleckstrin Homology (PH) domain also inhibits receptor constitutive activity, and PH domain expression rescues 5-HT6 receptor-operated cAMP signaling in neurofibromin-deficient cells. Furthermore, PH domains carrying mutations identified in NF1 patients that prevent interaction with the 5-HT6 receptor fail to rescue receptor constitutive activity in neurofibromin-depleted cells. Further supporting a role of neurofibromin in agonist-independent Gs signaling elicited by native receptors, the phosphorylation of cAMP-responsive element-binding protein (CREB) is strongly decreased in prefrontal cortex of Nf1(+/-) mice compared with WT mice. Moreover, systemic administration of a 5-HT6 receptor inverse agonist reduces CREB phosphorylation in prefrontal cortex of WT mice but not Nf1(+/-) mice. Collectively, these findings suggest that disrupting 5-HT6 receptor-neurofibromin interaction prevents agonist-independent 5-HT6 receptor-operated cAMP signaling in prefrontal cortex, an effect that might underlie neuronal abnormalities in NF1 patients.