Objective: To investigate the role of RNA m6A reader YTHDF2 in neurodegeneration of the aged mice. Methods: Eighteen 18-month-old control C57BL/6 mice and 22 Ythdf2 conditional knockout (cKO) mice of the same age (that exhibited significant aging characteristics) were used. Five pairs of mice were used for morphological analysis. Thirteen control mice and 17 cKO mice were used for behavioral experiments. Immunofluorescence analysis was performed to detect the expression of YTHDF2 in the brains of 18-month-old C57BL/6 mice. After establishing the neural progenitor cell-specific knockout mice of Ythdf2, their phenotypes were analyzed through comparison of body weight, brain weight and H&E staining. Subsequently, immunohistochemistry and immunofluorescence analyses were used to detect the expression of various neural cell-specific markers in the aged control mice and Ythdf2 cKO mice. Finally, behavioral tests, including the open field test, new object recognition, and water maze, were used to assess the levels of anxiety, depression, learning and memory abilities. Results: Immunofluorescence staining showed that YTHDF2 was mainly expressed in the neurons. Compared with the age-matched control mice, there was no significant change in the body weight of the Ythdf2 cKO mice, but the brain weight decreased significantly (P<0.05). The immunostaining showed that Ythdf2 cKO mice had fewer neurons, fewer astrocytes with defective morphology, more microglia and activation of microglia (P<0.05). Behavioral tests showed that the aged Ythdf2 cKO mice exhibited impaired movement, learning and memory abilities (P<0.05). Conclusions: YTHDF2 is mainly expressed in the neurons of the aged brain. Conditional knockout of Ythdf2 causes quantitative and structural abnormalities in hippocampal neuronal cells, and impairs motor ability and learning and memory of the aged mice, suggesting that YTHDF2 plays an important role in neurodegeneration of the aged mice.
目的： 探讨RNA m6A识别蛋白YTHDF2在老年小鼠神经退行过程中的作用。 方法： 使用表现出明显衰老特征的18月龄正常对照C57BL/6小鼠18只以及同月龄Ythdf2条件性敲除（cKO）小鼠22只，其中5对小鼠用于形态学分析，13只对照小鼠和17只Ythdf2 cKO小鼠用于行为学实验。首先通过免疫荧光实验检测18月龄C57BL/6正常对照小鼠脑组织中YTHDF2的表达；随后构建神经前体细胞特异性敲除Ythdf2的小鼠模型；通过体重、脑重以及HE染色初步分析老年小鼠大脑的变化；利用免疫组织化学和免疫荧光检测老年正常对照小鼠和Ythdf2 cKO小鼠中不同神经细胞特异性标志物的表达情况；最后通过行为学实验（旷场实验、新物体识别、水迷宫）检测小鼠的运动能力及学习记忆能力。 结果： 免疫荧光染色显示YTHDF2主要在神经元中表达；与正常对照小鼠相比，Ythdf2 cKO小鼠的体重无明显变化，脑重显著下降（P<0.05）；免疫染色结果显示，Ythdf2 cKO老年小鼠的海马神经元数量减少、星形胶质细胞数量减少且形态缺陷、小胶质细胞增多和活化（P<0.05）；行为学测试显示Ythdf2 cKO老年小鼠的运动能力下降、学习记忆能力受损（P<0.05）。 结论： 老年小鼠脑组织中YTHDF2主要在神经元中表达，Ythdf2缺失会造成小鼠海马神经细胞的数量与结构异常，并损害其运动能力和学习记忆，这提示YTHDF2在老年小鼠的神经退行过程中发挥重要作用。.