In contrast to the normal mouse which exhibits normal cognitive ability (left panel), developmental arsenic exposure induces Dnmt3a degradation through direct arsenic-Dnmt3a interaction, by which downregulates genome-wide DNA methylation and dysregulates ECM-related genes (middle panel). MET combination treatment normalizes global DNA methylation level and ECM-related gene expression in the mouse hippocampus, by which ameliorates the arsenic-induced cognitive impairment in mouse (right panel). 