MeCP2 is required for global heterochromatic and nucleolar changes during activity-dependent neuronal maturation

► During neuronal maturation, nuclear and nucleolar chromatin changes are observed. ► Neuronal chromatin is globally altered as a result of MeCP2 deficiency. ► Neuronal nucleolar enlargement in early postnatal life requires MeCP2. ► Activity-induced changes to neuronal heterochromatic chromocenters require MeCP2. ► A Rett MBD mutation affects nucleolar enlargement during neuronal maturation.