ABSTRACT

An increase in protein synthesis following learning is a fundamental and evolutionarily conserved mechanism of long-term memory. To maintain homeostasis, this protein synthesis must be counterbalanced by mechanisms such as protein degradation. Recent studies reported that macroautophagy/autophagy, a major protein degradation mechanism, is required for long-term memory formation. However, how learning regulates autophagy and recruits it into long-term memory formation remains to be established. Here, we show that inhibitory avoidance in rats significantly increases the levels of autophagy and lysosomal degradation proteins, including BECN1/beclin 1, LC3-II, SQSTM1/p62 and LAMP1, as well as autophagic flux in the hippocampus. Moreover, pharmacological inhibition or targeted molecular disruption of the learning-induced autophagy impairs long-term memory, leaving short-term memory intact. The increase in autophagy proteins results from active translation of their mRNA and not from changes in their total mRNA levels. Additionally, the induction of autophagy requires the immediate early gene Arc/Arg3.1. Finally, in contrast to classical regulation of autophagy in other systems, we found that the increase in autophagy upon learning is dispensable for the increase in protein synthesis. We conclude that coupling between learning-induced translation and autophagy, rather than translation per se, is an essential mechanism of long-term memory.

Abbreviations: AAV: adeno-associated virus; ARC/ARG3.1: activity regulated cytoskeletal-associated protein; ATG: autophagy related; DG: dentate gyrus; GFP: green fluorescent protein; IA: inhibitory avoidance; LAMP1: lysosomal-associated membrane protein 1; MAP1LC3B/LC3B: microtubule-associated protein 1 light chain 3 beta; ODN: oligodeoxynucleotide; qPCR: quantitative polymerase chain reaction; SBI: SBI0206965; SQSTM1/p62: sequestosome 1; SUnSET: surface sensing of translation; TRAP: translating ribosome affinity purification; ULK1: unc-51 like kinase 1

 抽象的

学习后蛋白质合成的增加是长期记忆的基本且进化上保守的机制。为了维持体内平衡，这种蛋白质合成必须通过蛋白质降解等机制来平衡。最近的研究报道，巨自噬/自噬是一种主要的蛋白质降解机制，是长期记忆形成所必需的。然而，学习如何调节自噬并将其招募到长期记忆形成中仍有待确定。在这里，我们发现大鼠的抑制性回避显着增加了自噬和溶酶体降解蛋白的水平，包括 BECN1/beclin 1、LC3-II、SQSTM1/p62 和 LAMP1，以及海马中的自噬通量。此外，学习诱导的自噬的药理抑制或靶向分子破坏会损害长期记忆，而短期记忆却完好无损。自噬蛋白的增加是由于其 mRNA 的活跃翻译所致，而不是由于其总 mRNA 水平的变化。此外，自噬的诱导需要立即早期基因Arc / Arg3.1 。最后，与其他系统中自噬的经典调节相反，我们发现学习时自噬的增加对于蛋白质合成的增加是可有可无的。我们得出的结论是，学习诱导的翻译和自噬之间的耦合，而不是翻译本身，是长期记忆的重要机制。

缩写： AAV：腺相关病毒； ARC/ARG3.1：活性调节的细胞骨架相关蛋白； ATG：自噬相关； DG：齿状回； GFP：绿色荧光蛋白； IA：抑制性回避； LAMP1：溶酶体相关膜蛋白1； MAP1LC3B/LC3B：微管相关蛋白1轻链3β； ODN：寡脱氧核苷酸； qPCR：定量聚合酶链式反应； SBI：SBI0206965； SQSTM1/p62: 隔离体 1; SUnSET：平移的表面传感； TRAP：翻译核糖体亲和纯化； ULK1：unc-51 样激酶 1