Introduction: Down syndrome (DS) is a common genetic disorder caused by full or partial trisomy of human chromosome 21. DS individuals usually have poor neurological development with neuropsychiatric manifestations. Repressor element-1 silencing transcription factor (REST) is the key regulator for epigenetic neuronal gene expression. REST nuclear translocation is crucial to exert repression on target genes transcriptionally. A comprehensive spatiotemporal profiling of Rest expression was performed on the Ts1Cje mouse brain to reveal its association with DS neuropathology development. Methods: Over-representation analysis of Ts1Cje differentially expressed genes (DEGs) with mouse REST targets was performed. The cerebral cortex, hippocampus and cerebellum of Ts1Cje and wildtype (WT) mice were procured at postnatal - P1, P15, P30, and P84 and embryonic - E14 and P1.5 development timepoints[User1] . RNAs from the brain tissues and cultured neurospheres were analysed with qPCR to determine the spatiotemporal profile of Rest expression. Western blot and immunohistochemistry (IHC) staining were performed to determine the level of REST expression and nuclear localisation. Results: Over-representation analysis showed the Ts1Cje DEGs are significantly overlapped with mouse REST target genes. QPCR and Western blot analysis revealed a significant downregulation of Rest in neurospheres and protein expression in Ts1Cje compared to WT. Furthermore, IHC staining showed a consistent perinuclear marginalisation of REST, indicating impaired nuclear translocation in the Ts1Cje brain. Conclusion:DEGs in the Ts1Cje tissues are potentially caused by the loss of REST functions. Dysregulated Rest expression at the early neurodevelopmental stage may cause premature neurodifferentiation, neural stem cell pool depletion, and disrupt early cell fate determination. The loss of nuclear REST function may cause neuroprotection and stress resilience deficits.