Distinct Proteomic Brain States Underlying Long-Term Memory Formation in Aversive Operant Conditioning

Long-term memory (LTM) formation relies on de
novo protein synthesis; however, the full complement of proteins
crucial
to LTM formation remains unknown in any system. Using an aversive
operant conditioning model of aerial respiratory behavior in the pond
snail mollusk, Lymnaea stagnalis (L. stagnalis), we conducted a transcriptome-guided proteomic analysis on the
central nervous system (CNS) of LTM, no LTM, and control animals.
We identified 366 differentially expressed proteins linked to LTM
formation, with 88 upregulated and 36 downregulated in LTM compared
to both no LTM and controls. Functional annotation highlighted the
importance of balancing protein synthesis and degradation for LTM,
as indicated by the upregulation of proteins involved in proteasome
activity and translation initiation, including EIF2D, mRNA levels
of which were confirmed to be upregulated by conditioning and implicated
nuclear factor Y as a potential regulator of LTM-related transcription
in this model. This study represents the first transcriptome-guided
proteomic analysis of LTM formation ability in this model and lays
the groundwork for discovering orthologous proteins critical to LTM
in mammals.

长期记忆（Long-term memory, LTM）的形成依赖于蛋白质从头合成；然而，目前在任何生物系统中，与LTM形成相关的全套关键蛋白质仍未被完全探明。本研究以静水椎实螺（Lymnaea stagnalis, L. stagnalis）的空中呼吸行为厌恶性操作性条件反射模型为研究对象，对具备LTM、不具备LTM以及对照组动物的中枢神经系统（central nervous system, CNS）开展了转录组引导的蛋白质组学分析。我们共鉴定出366种与LTM形成相关的差异表达蛋白，相较于不具备LTM的动物与对照组，LTM形成组中有88种蛋白表达上调、36种蛋白表达下调。功能注释结果显示，维持蛋白质合成与降解的平衡对LTM形成至关重要——这一点可通过蛋白酶体活性与翻译起始相关蛋白的上调得到佐证，其中包括真核翻译起始因子2D（EIF2D）；实验证实，该因子的mRNA水平可因条件反射训练而上调，同时研究提示核因子Y（nuclear factor Y）可能是该模型中LTM相关转录过程的潜在调控因子。本研究是首个针对该模型中LTM形成能力开展的转录组引导蛋白质组学分析，为后续发掘哺乳动物中关键LTM相关同源蛋白奠定了研究基础。