TET2-mediated Cdkn2A DNA hydroxymethylation in midbrain dopaminergic neurons injury of Parkinson's disease.

It has been reported that abnormal epigenetic modification is associated with the occurrence of Parkinson's disease (PD). Here, we found that a Ten-Eleven Translocation 2 (TET2), a staff of the DNA hydroxylases family, was increased in dopaminergic neurons in vitro and in vivo. Genome-wide mapping of DNA 5-hmC-sequencing has revealed an aberrant epigenome 5-hydroxymethylcytosine (5-hmC) landscape in 1-Methyl-4-phenylpyridinium iodide (MPP+)-induced SH-SY5Y cells. The TET family of DNA hydroxylases could reverse DNA methylation by oxidization of 5-methylcytosine (5-mC) to 5-hmC. However, the relationship between modification of DNA hydroxymethylation and the pathogenesis of PD is not clear. According to the results of 5-hmC-sequencing studies, 5-hmC was associated with gene-rich regions in the genomes related to cell cycle, especially gene cyclin dependent kinase inhibitor 2A (Cdkn2A). Downregulation of TET2 expression could significantly rescue MPP+-stimulated SH-SY5Y cell damage and cell cycle arrest. Meanwhile, knockdown of Tet2 expression in the substantia nigra pars compacta of MPTP-induced PD mice, resulted in attenuated MPTP-induced motor deficits and dopaminergic neuronal injury via p16 suppression. In this study, we demonstrated a critical function of TET2 in PD development via the CDKN2A activity-dependent epigenetic pathway, suggesting a potential new strategy for epigenetic therapy.