SRC-1介导Wnt/β-catenin信号通路在恐惧记忆再巩固中的作用及机制研究

Reconsolidation after retrieval of fear memory is one of the important reasons to maintain the core symptoms in post-traumatic stress disorder (PTSD) of not easy to extinction. Intervening the key molecules in reconsolidation of fear memory is the effective way for the treatment of PTSD. It is reported that Wnt/β-catenin signaling pathway play an important role in reconsolidation of fear memories, and SRC-1 is a key coactivator of Wnt/β-catenin signaling pathways regulating target gene transcription. Our recent studies have found that inhibition of SRC-1 would block the fear memory reconsolidation and the level of the target gene BDNF significantly reduced, implying SRC-1 may play an important role in reconsolidation of fear memory. However, the specific mechanism is unclear. We speculate that SRC-1, as acetyltransferase, could combine with β-catenin, regulating acetylation of BDNF at H3K9/K14 site, promoting its expression and enhance reconsolidation of fear memory. The project is proposed on the basis of our earlier researches, using some experimental methods, such as virus transfection, electrophysiological recording, chromatin immune coprecipitation, exploring the epigenetic regulation mechanism of SRC-1 mediated Wnt/β-catenin signaling pathway to BDNF, the target genes, in reconsolidation of fear memory, providing a new therapy target for treatment of PTSD.

恐惧记忆激活后的再巩固（reconsolidation）是创伤后应激障碍（PTSD）症状不易消退的重要原因，干预恐惧记忆再巩固的关键分子是治疗PTSD的主要途径。研究发现，Wnt/β-catenin信号通路在恐惧记忆再巩固中发挥重要作用，SRC-1是该通路调节靶基因转录必要的辅助活化因子。我们的近期研究表明抑制SRC-1会阻断恐惧记忆的再巩固且靶基因BDNF的水平显著降低，提示SRC-1在恐惧记忆再巩固中可能发挥重要作用，但具体机制未明。我们推测SRC-1可能通过与β-catenin结合，调节BDNF启动子Ⅰ/Ⅳ区组蛋白H3K9/K14的乙酰化水平，促进BDNF的表达并增强恐惧记忆再巩固。本项目拟在已有研究的基础上利用病毒转染、电生理记录、染色质免疫共沉淀等方法，探讨SRC-1介导Wnt/β-catenin信号通路对靶基因BDNF的表观遗传学调节机制，为治疗PTSD症状探索新的药物靶点。

情景依赖的恐惧记忆再巩固是PTSD症状不易消退的重要原因，恐惧记忆再巩固的神经分子机制尚不明确。研究表明Wnt/β-catenin信号通路在恐惧记忆再巩固中发挥重要作用，該通路调节靶基因转录的辅活化因子SRC-1在其中的作用机制尚待阐明。因此在本项目中我们利用形态学、分子生物学、行为学和电生理学等方法首先研究了海马SRC-1在对突触可塑性和学习记忆的调节和机制；其次研究了SRC-1在恐惧记忆巩固与再巩固中的作用机制；最后研究了Wnt/β-catenin信号通路对恐惧记忆再巩固的调节机制。.主要有以下结果：.1) 抑制海马SRC-1会损害海马的突触可塑性及空间学习记忆行为; .2) 情景条件恐惧后海马SRC-1表达显著升高，抑制海马SRC-1会干扰情景恐惧记忆的巩固, 而对原发恐惧没有影响；.3) 恐惧记忆激活后海马SRC-1表达显著升高，抑制海马SRC-1会破坏情景恐惧记忆的再巩固；.4) 恐惧记忆激活会活化Wnt/β-catenin信号通路，抑制Wnt/β-catenin信号通路会破坏恐惧记忆再巩固；.5) Wnt/β-catenin信号通路是通过调控靶基因BNDF启动子区组蛋白的磷酸化和乙酰化修饰来调节恐惧记忆再巩固.本项目阐明了SRC-1对海马学习记忆以及恐惧记忆巩固和再巩固的作用，并探讨了Wnt/β-catenin信号通路调控BDNF组蛋白乙酰化增强情景性恐惧记忆再巩固的作用及分子机制，为治疗PTSD症状探索新的药物干预靶点。