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miR-34a敲除对小鼠大脑发育和行为的影响

叶亚龙, 朱莉芳, 高林辉, 龚玲, 何苗

复旦大学脑科学研究院，上海 200032

摘要

miR-34a是一种进化保守并在脑中高表达的miRNA，已有研究显示其可能参与调控神经干细胞增殖和分化、神经元成熟和凋亡、恐惧记忆巩固等脑发育和功能的多个重要方面，但内源性miR-34a缺失是否显著影响脑正常发育和功能尚属未知。在本研究中，我们对miR-34a全敲除小鼠模型进行检测，发现miR-34a的缺失不影响成年鼠脑的重量、基本结构、大脑皮层的分层及其中几类主要类型的兴奋性和抑制性神经元的数量和分布，也不影响恐惧记忆的巩固及焦虑和抑郁样行为，但对小鼠的运动协调能力有一定影响。由于miR-34a在大脑皮层小清蛋白(parvalbumin, PV)亚型抑制性神经元中特异高表达，我们利用PV-Cre对miR-34a进行了条件敲除，但并未观察到这类神经元数量与分布的改变。我们的研究证明，miR-34a虽然参与调控小鼠大脑发育和行为的特定方面，但并非是调控大脑结构分区与皮层分层形成、皮层主要神经元类型产生与维持、恐惧记忆形成与巩固所必需的关键因子。

关键词： miR-34a; 敲除 ; 大脑发育 ; 恐惧记忆 ; 运动协调

分类号：Q189

Analysis of miR-34a function in brain development and behavior using knockout mouse model

YE Ya-Long, ZHU Li-Fang, GAO Lin-Hui, GONG Ling, HE Miao

Institutes of Brain Science, Fudan University, Shanghai 200032, China

Abstract

miR-34a is a conserved microRNA highly expressed in the brain. It is thought to play critical roles in regulating many aspects of brain development and function, such as neural stem cell proliferation and differentiation, neuronal migration and apoptosis, fear memory consolidation, etc. However, the assessment of its function was mainly conducted through vector-mediated overexpression and miRNA sponge or antagomir-mediated functional suppression, therefore may suffer from nonspecific off-target effects or incomplete inactivation. We thus analyzed mouse model with a targeted deletion of miR-34a which completely abolishes its expression. To our surprise, loss of miR-34a led to neither an obvious change in brain size, morphology or cortical lamination, nor impaired marker gene expression in major excitatory and inhibitory neuron types in the neocortex. In addition, miR-34a ablation did not affect fear memory formation or consolidation, as well as the anxiety or depression related behavior. However, the performance of mice in rotarod assay was significantly affected, suggesting a defect in motor activity in miR-34a deficient mice. As neocortical parvalbumin (PV) neurons are known for high level miR-34a expression, we also tested the effect of PV-Cre-mediated conditional miR-34a deletion. Similar as germline deletion, PV neuron specific miR-34a deletion did not affect cortical lamination or PV expression in the neocortex. Our studies suggest that, although miR-34a may be involved in regulating certain aspects of brain development or function, such as motor activity, it does not play a significant role in regulating brain morphogenesis, cortical lamination or neocortical neuron subtype specification, and it is also dispensable for fear memory formation, expression and consolidation.

Key words: miR-34a; knockout ; brain development ; fear memory ; motor coordination

收稿日期：2017-04-01　　录用日期：2017-05-23

通讯作者：何苗　　E-mail: hem@fudan.edu.cn

引用本文：

叶亚龙, 朱莉芳, 高林辉, 龚玲, 何苗. miR-34a敲除对小鼠大脑发育和行为的影响[J]. 生理学报 2017; 69 (4): 452-460.

YE Ya-Long, ZHU Li-Fang, GAO Lin-Hui, GONG Ling, HE Miao. Analysis of miR-34a function in brain development and behavior using knockout mouse model. Acta Physiol Sin 2017; 69 (4): 452-460 (in Chinese with English abstract).