Wang Chen, Niu Mengxi, Zhou Zehua, Zheng Xiaoyuan, Zhang Lingzhi, Tian Ye, Yu Xiaojun, Bu Guojun, Xu Huaxi, Ma Qilin, Zhang Yun-Wu
Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Collaborative Innovation Center for Brain Science, College of Medicine, Xiamen University, Xiamen, Fujian, China; Department of Neurology, The First Affiliated Hospital of Xiamen University, Xiamen, Fujian, China.
Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Collaborative Innovation Center for Brain Science, College of Medicine, Xiamen University, Xiamen, Fujian, China.
Neurobiol Aging. 2016 Oct;46:22-31. doi: 10.1016/j.neurobiolaging.2016.05.016. Epub 2016 May 21.
Vacuolar protein sorting 35 (VPS35) is a retromer complex component regulating membrane protein trafficking and retrieval. Mutations or dysfunction of VPS35 have been linked to Parkinson's disease (PD), which is pathologically characterized by the loss of dopamine neurons in brain substantia nigra region. Dopamine plays a key role in regulating various brain physiological functions by binding to its receptors and triggering their endocytosis and signaling pathways. However, it is unclear whether there is a link between VPS35 and dopamine signaling in PD. Herein, we found that VPS35 interacted with dopamine receptor D1 (DRD1). Notably, overexpression and downregulation of VPS35 increased and decreased steady-state cell surface levels of DRD1 and phosphorylation of cAMP-response element binding protein (CREB) and extracellular regulated protein kinases (ERK) that are important dopamine signaling effectors, respectively. In addition, overexpression of VPS35 promoted cell surface recycling of endocytic DRD1. Furthermore, downregulation of VPS35 abolished dopamine-induced CREB/ERK phosphorylation. More importantly, although the PD-associated VPS35 mutant VPS35 (D620N) still interacted with DRD1, its expression did not affect cell surface recycling of DRD1 and phosphorylation of CREB/ERK nor rescue the reduction of CREB/ERK phosphorylation caused by VPS35 downregulation. These results demonstrate that VPS35 regulates DRD1 trafficking and DRD1-mediated dopamine signaling pathway, and that the PD-associated VPS35 (D620N) mutant loses such functions, providing a novel molecular mechanism underlying PD pathogenesis.
液泡蛋白分选35（VPS35）是一种参与调节膜蛋白运输和回收的逆转录复合物成分。VPS35的突变或功能障碍与帕金森病（PD）相关，PD的病理特征是脑黑质区域多巴胺能神经元的丧失。多巴胺通过与其受体结合并触发其胞吞作用和信号通路，在调节各种脑生理功能中起关键作用。然而，尚不清楚VPS35与PD中的多巴胺信号传导之间是否存在联系。在此，我们发现VPS35与多巴胺受体D1（DRD1）相互作用。值得注意的是，VPS35的过表达和下调分别增加和降低了DRD1的稳态细胞表面水平以及环磷酸腺苷反应元件结合蛋白（CREB）和细胞外调节蛋白激酶（ERK）的磷酸化，而CREB和ERK是重要的多巴胺信号效应器。此外，VPS35的过表达促进了内吞DRD1的细胞表面再循环。此外，VPS35的下调消除了多巴胺诱导的CREB/ERK磷酸化。更重要的是，虽然与PD相关的VPS35突变体VPS35（D620N）仍与DRD1相互作用，但其表达不影响DRD1的细胞表面再循环和CREB/ERK的磷酸化，也不能挽救由VPS35下调引起的CREB/ERK磷酸化的减少。这些结果表明，VPS35调节DRD1的运输和DRD1介导的多巴胺信号通路，并且与PD相关的VPS35（D620N）突变体丧失了这些功能，这为PD发病机制提供了一种新的分子机制。
