[Role of RNA m6A reader YTHDF2 in neurodegeneration of the aged mice]

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.