新蛋白合成调控视觉行为可塑性机制New protein synthesis regulates visual behavior plasticity

突触可塑性依赖于局部蛋白质的新合成，但在活体动物大脑中鉴定与学习相关的新生蛋白质一直是技术瓶颈。2014年，杭州师范大学沈万华实验室与美国 Scripps 研究所 Cline HT 实验室合作，利用 BONCAT + MudPIT 蛋白质组学平台，首次在爪蟾蝌蚪活体中鉴定了视觉经验诱导合成的新生蛋白质，发现 CPEB（胞质多腺苷酸化元件结合蛋白）的急性合成是视觉行为可塑性的关键机制。Synaptic plasticity requires local de novo protein synthesis, but identifying experience-induced nascent proteins in a living brain had been technically intractable. In 2014, the Shen WH lab (Hangzhou Normal University) and Cline HT lab (Scripps Research) used BONCAT + MudPIT proteomics to identify experience-dependent newly synthesized proteins in tadpole brain in vivo, revealing that acute CPEB (cytoplasmic polyadenylation element-binding protein) synthesis is required for visual behavior plasticity.

技术创新：BONCAT + MudPIT 活体新生蛋白标记Technical innovation: BONCAT + MudPIT in-vivo labeling

BONCAT（bio-orthogonal non-canonical amino acid tagging）利用非天然氨基酸 L-azidohomoalanine（AHA）替代甲硫氨酸，仅标记新合成蛋白质；随后通过 Click Chemistry 连接生物素亲和柄，结合 MudPIT（多维蛋白鉴定技术）质谱分析，对全脑新生蛋白质组进行无偏鉴定。BONCAT uses the non-canonical amino acid L-azidohomoalanine (AHA) as a methionine surrogate, labeling only newly synthesized proteins. Biotin affinity handles are attached via click chemistry, and MudPIT mass spectrometry performs unbiased identification of the de-novo proteome across the entire brain.

主要研究结果Key results

• 视觉训练（光暗运动刺激）在 1 小时内即诱导蝌蚪视顶盖特异性新生蛋白质谱的显著变化，共鉴定出数十种经验依赖性上调蛋白；Visual training (moving light–dark stimuli) induced significant changes in the tectal de-novo proteome within 1 hour; dozens of experience-upregulated proteins were identified;
• CPEB 是上调最显著的蛋白之一，其 mRNA 水平在视觉刺激后并无显著变化，表明调控发生在翻译层面而非转录层面；CPEB was among the most significantly upregulated proteins; its mRNA level did not change after stimulation, indicating translational rather than transcriptional regulation;
• 利用 Morpholino 急性敲低 CPEB 后，蝌蚪的视觉回避学习（visual avoidance learning）显著受损，而对基础视觉反应无明显影响；Acute Morpholino knockdown of CPEB significantly impaired visual avoidance learning without affecting baseline visual responses;
• CPEB 作为 RNA 结合蛋白，通过促进下游靶 mRNA 的多腺苷酸化与翻译，级联扩大新蛋白合成信号，是突触可塑性的重要调控节点。CPEB, as an RNA-binding protein, amplifies de-novo synthesis signals by promoting polyadenylation and translation of downstream target mRNAs — a critical regulatory node for synaptic plasticity.

科学意义Significance

该研究首次在活体发育中脑内实现对视觉经验诱导的新生蛋白质组的系统鉴定，将翻译调控确立为快速行为可塑性的核心机制。CPEB 作为突触局部翻译的关键调控因子，其急性合成形成一个正反馈环路，为记忆相关蛋白的级联放大提供了分子基础。这一研究范式也为将爪蟾蝌蚪用于系统蛋白质组学研究提供了重要示范。This work established the first systematic in-vivo de-novo proteomics of visual experience in a developing brain, identifying translational regulation as a core mechanism of rapid behavioral plasticity. CPEB-mediated positive feedback amplifies the cascade of plasticity-related protein synthesis, providing a molecular basis for memory consolidation. The study also demonstrates Xenopus tadpole as a powerful system for in-vivo proteomics.

研究单位：杭州师范大学生命科学学院沈万华实验室；美国 Scripps 研究所 Cline HT 实验室Affiliations: Shen WH lab, Hangzhou Normal University; Cline HT lab, The Scripps Research Institute

参考文献References

1. Shen WH et al. (2014) Experience-dependent regulation of the brain proteome and plasticity of visual behavior in Xenopus tadpoles. Cell Rep 6(5):851–865.
2. Dieck ST, Kochen L, Hanus C, et al. (2015) Direct visualization of newly synthesized target proteins in situ. Nat Methods 12(5):411–414.
3. Sutton MA & Schuman EM. (2006) Dendritic protein synthesis, synaptic plasticity, and memory. Cell 127(1):49–58.