Expression of methyl CpG binding protein 2 (Mecp2) during the postnatal development of the mouse brainstem

Methyl CpG binding protein 2 (MeCP2) is a member of the methylated DNA binding protein family able to modulate the transcription of target genes. Mutations in MECP2 lead to a wide range of neurological phenotypes and the better known of these diseases is Rett Syndrome. All patients having a mutation in MECP2 are mentally retarded and most of them exhibit dysfunctions in autonomic processes that are controlled by the brainstem. Previous studies have shown that Mecp2 is developmentally and spatially regulated throughout the rodent brain but none of them investigated the brainstem. In the present study, we have quantified the levels of expression of the Mecp2 mRNA by real time PCR and MeCP2 protein by immunoquantifications, in different areas of the mouse brainstem during the postnatal development (P0, P7, P21, P35 and P55). We focused on regions of the pons and the medulla oblongata directly involved in the regulation of autonomic functions. Our results show that the expression of MeCP2 is heterogeneously expressed throughout the postnatal mouse brainstem. MeCP2 expression in each area studied is restricted to neurones. The developmental pattern is mainly characterized by a postnatal decrease of the Mecp2 mRNA and an increase of the MeCP2 protein staining level in spite of the local variability. However, we were not able to correlate the developmental expression of MeCP2 in a given area of the brainstem with autonomic dysfunctions occurring in the presence of a mutation in Mecp2.