Ann Romney Center for Neurologic Diseases, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA.
Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02115, USA; Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
Cell Rep. 2021 Jul 6;36(1):109333. doi: 10.1016/j.celrep.2021.109333.
While misfolding of alpha-synuclein (αSyn) is central to the pathogenesis of Parkinson's disease (PD), fundamental questions about its structure and function at the synapse remain unanswered. We examine synaptosomes from non-transgenic and transgenic mice expressing wild-type human αSyn, the E46K fPD-causing mutation, or an amplified form of E46K ("3K"). Synaptosomes from mice expressing the 3K mutant show reduced Ca-dependent vesicle exocytosis, altered synaptic vesicle ultrastructure, decreased SNARE complexes, and abnormal levels of certain synaptic proteins. With our intra-synaptosomal nuclear magnetic resonance (NMR) method, we reveal that WT αSyn participates in heterogeneous interactions with synaptic components dependent on endogenous αSyn and synaptosomal integrity. The 3K mutation markedly alters these interactions. The synaptic microenvironment is necessary for αSyn to reach its native conformations and establish a physiological interaction network. Its inability to populate diverse conformational ensembles likely represents an early step in αSyn dysfunction that contributes to the synaptotoxicity observed in synucleinopathies.
虽然α-突触核蛋白（αSyn）的错误折叠是帕金森病（PD）发病机制的核心，但突触中关于其结构和功能的基本问题仍未得到解答。我们研究了表达野生型人αSyn、E46K 致 PD 突变或扩增形式的 E46K（“3K”）的非转基因和转基因小鼠的突触体。表达 3K 突变体的小鼠突触体显示 Ca 依赖性囊泡胞吐减少、突触囊泡超微结构改变、SNARE 复合物减少以及某些突触蛋白异常。通过我们的突触体内磁共振（NMR）方法，我们揭示了 WT αSyn 与依赖于内源性 αSyn 和突触体完整性的突触成分参与异质相互作用。3K 突变显著改变了这些相互作用。突触微环境对于 αSyn 达到其天然构象并建立生理相互作用网络是必需的。其无法形成多种构象集合可能代表了 αSyn 功能障碍的早期步骤，导致在突触核蛋白病中观察到的突触毒性。
