CREB去磷酸化介导多巴胺能神经元死亡的作用及机制

Selective loss of dopaminergic neurons within the substantia nigra pars compacta is the main pathological characteristic of Parkinson disease (PD). We have observed that CREB was dephosphorylated in dopaminergic neurons selectively while ATF2 phosphorylation increased. Substantia nigra pars compacta is more vulnerable to CREB dephosphorylation than ventral tegmental area. The role and regulatory mechanism of CREB dephosphorylation in dopaminergic neuron loss are unknown. This proposal will achieve the following goals: 1)to determine the role of CREB dephosphorylation in dopaminergic neuron loss; 2)to identify which upstream kinase(s) or phosphatase (s) is responsible for CREB dephosphorylation; 3)to determine the downstream target genes of CREB/ATF2 that mediate dopaminergic neuron loss. Through the methods of genetically engineered mice, adeno-associated virus, and so on, we propose to clarify the mechanism(s) underlying selective vulnerability of dopaminergic neurons regulated by CREB dephosphorylation, providing scientific evidence for establishment of therapeutic target for PD.

黑质多巴胺能神经元(DA神经元)选择性死亡是帕金森病(Parkinson disease, PD)主要的病理特征。我们首次发现：在MPTP诱导的PD小鼠模型中，CREB磷酸化选择性的在DA神经元内下调，且黑质致密部比腹侧背盖区更敏感，并伴随着ATF/CRE家族的另一个转录因子ATF2在DA神经元内上调。然而，CREB磷酸化下调对DA神经元死亡的作用及调控机制尚不明确。结合文献复习，我们拟进一步：揭示CREB磷酸化下调在"DA神经元死亡"中的关键作用和机制；明确CREB磷酸化下调是由激酶失活还是磷酸酶激活所介导；寻找和鉴定CREB/ATF2促死靶基因。本项目拟采用基因工程小鼠、腺相关病毒等工具, 阐明CREB下调对DA神经元死亡的作用和调控机制，为确立PD 治疗新靶标提供科学依据。

黑质多巴胺能神经元(DA神经元)选择性死亡是帕金森病(Parkinson disease, PD)主要的病理特征，发病机制不清。环磷腺苷效应元件结合蛋白CREB(cAMP-response element binding protein)是促神经元存活重要转录因子，Ser133是其活化最关键磷酸化位点，以往研究证明其既参与调节突触可塑性过程，也参与神经退行性疾病的发生发展。然而，CREB磷酸化对DA神经元存活的作用及调控机制和靶基因尚不明确。我们首次发现：在MPTP诱导的PD小鼠模型中，CREB磷酸化选择性的在DA神经元内下调。进一步采用染色质免疫共沉淀（ChIP）发现CREB组成性结合在Nurr1启动子CRE位点，MPTP模型中Nurr1蛋白和mRNA水平下调。MPTP诱导HDAC1-PP1γ复合物与CREB相互作用增加，介导CREB去磷酸化以及Nurr1下调。腺相关病毒或HDAC1抑制剂TSA干扰CREB和HDAC1相互作用，恢复CREB磷酸化以及Nurr1表达，保护MPTP诱导的DA神经元死亡。这些结果说明p-CREB下调在DA神经元死亡和PD发生中发挥重要作用，为以CREB为靶治疗PD提供科学依据。