Probing DNA damage in Rett syndrome neurons uncovers a role for MECP2 regulation of PARP1.

Methyl-CpG-binding protein 2 (MECP2)/Rett syndrome is characterized by a postnatal loss of neurophysiological function and regression of childhood development. While Rett neurons have been described as showing elevated senescence and P53 activity, here we show that molecular and physiological dysfunction in neurons lacking MECP2 is triggered by elevated DNA damage. Using human induced pluripotent stem cell (hiPSC)-derived isogenic lines, we find that MECP2 directly interacts with members of the DNA repair machinery, including PARP1. Here, we present evidence that MECP2 also regulates PARP1 activity, and restoration of PARP1 activity in MECP2-null neurons can reverse DNA damage, senescence, dendritic branching defects, and metabolic dysfunction. These data from a human disease-in-a-dish model system support the notion that dysfunction in Rett syndrome neurons could be caused by changes in PARP activity.