光激活背侧海马星形胶质细胞Rac1抑制小鼠关联性记忆的形成

发布时间：2019-06-04 03:14

【摘要】：Rac1属于小G蛋白Rho GTPases家族的一员,通过调控细胞骨架及形态影响细胞迁移、轴突导向等生理过程,在脑内发挥重要作用。但Rac1的动态激活过程对脑内的生理学功能的影响尚不明确。近期报道可通过Rac1的光活化形式(photoactivatable Rac1,PA-Rac1)实现对Rac1活性的时空特异性操控。因此,我们构建并包装了由小鼠胶质原纤维酸性蛋白(mouse glial fibrillary acidic protein,m GFAP)启动子驱动的PA-Rac1及其光脱敏(light-insensitive)突变体PA-Rac1-C450A的腺相关病毒(adenoassociated virus,AAV),拟通过光刺激实时操控星形胶质细胞内Rac1的活性。我们将AAV-PA-Rac1及AAV-PA-Rac1-C450A感染原代星形胶质细胞。荧光实时成像实验结果显示光刺激表达PA-Rac1的原代星形胶质细胞时,在光刺激点附近表现出细胞膜的突起,而光刺激表达PA-Rac1-C450A的原代星形胶质细胞时,其细胞膜形态无明显改变。为进一步探究Rac1激活对小鼠关联性学习的影响,我们在小鼠背侧海马脑区注射AAV-PA-Rac1及AAV-PA-Rac1-C450A,在条件恐惧性记忆的训练过程中光激活背侧海马的Rac1。结果显示,表达PA-Rac1的小鼠在训练过程中的学习曲线显著低于对照组,而表达其突变体PA-Rac1-C450A组小鼠学习曲线和对照组相比无显著差异,表明光激活海马星形胶质细胞Rac1抑制了小鼠条件性恐惧记忆的形成。以上结果提示,背侧海马星形胶质细胞Rac1的激活参与小鼠的场景关联性学习过程。
[Abstract]:Rac1, a member of the small G protein Rho GTPases family, plays an important role in the brain by regulating the cytoskeleton and morphology affecting cell migration, axonal guidance and other physiological processes. However, the effect of dynamic activation of Rac1 on the physiological function of brain is not clear. Recently, it has been reported that the space-time specific manipulation of Rac1 activity can be realized by the photoactivation form (photoactivatable Rac1,PA-Rac1) of Rac1. Therefore, we constructed and packaged the adeno-associated virus (adenoassociated virus,AAV) of PA-Rac1 and its photodesensitized (light-insensitive) mutant PA-Rac1-C450A driven by mouse glial fibrillar acidic protein (mouse glial fibrillary acidic protein,m GFAP promoter. The activity of Rac1 in astrocytes was controlled in real time by light stimulation. We infected primary astrocytes with AAV-PA-Rac1 and AAV-PA-Rac1-C450A. The results of fluorescence real-time imaging showed that when primary astrocytes expressing PA-Rac1 were stimulated by light, the protrusions of cell membrane were observed near the photostimulation point, while the primary astrocytes expressing PA-Rac1-C450A were stimulated by light. There was no significant change in the morphology of the cell membrane. In order to further investigate the effect of Rac1 activation on related learning in mice, we injected AAV-PA-Rac1 and AAV-PA-Rac1-C450A, into the dorsal hippocampal region of mice during the training of conditional phobia memory. The Rac1. of dorsal hippocampus was activated by light. The results showed that the learning curve of the mice expressing PA-Rac1 was significantly lower than that of the control group during training, but there was no significant difference between the mutant PA-Rac1-C450A group and the control group. The results showed that light activation of hippocampal astrocytes Rac1 inhibited the formation of conditioned fear memory in mice. These results suggest that the activation of Rac1 in dorsal hippocampal astrocytes is involved in the scene correlation learning process in mice.
【作者单位】：复旦大学基础医学院医学神经生物学国家重点实验室药理研究中心;
【基金】：supported by the Major Research Plan of National Natural Science Foundation of China(No.91632307)
【分类号】：R338

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