Identification of autism-related MECP2 mutations by whole-exome sequencing and functional validation

Abstract

BackgroundMethyl-CpG-binding protein-2 (MeCP2) is a critical regulator for neural development. Either loss- or gain-of-function leads to severe neurodevelopmental disorders, such as Rett syndrome (RTT) and autism spectrum disorder (ASD). We set out to screen for MECP2 mutations in patients of ASD and determine whether these autism-related mutations may compromise the proper function of MeCP2.MethodsWhole-exome sequencing was performed to screen MECP2 and other ASD candidate genes for 120 patients diagnosed with ASD. The parents of patients who were identified with MECP2 mutation were selected for further Sanger sequencing. Each patient accomplished the case report form including general information and clinical scales applied to assess their clinical features. Mouse cortical neurons and HEK-293 cells were cultured and transfected with MeCP2 wild-type (WT) or mutant to examine the function of autism-associated MeCP2 mutants. HEK-293 cells were used to examine the expression of MeCP2 mutant constructs with Western blot. Mouse cortical neurons were used to analyze neurites and axon outgrowth by immunofluorescence experiments.ResultsWe identified three missense mutations of MECP2 from three autism patients by whole-exome sequencing: p.P152L (c.455C>T), p.P376S (c.1162C>T), and p.R294X (c.880C>T). Among these mutations, p.P152L and p.R294X were de novo mutations, whereas p.P376S was inherited maternally. The diagnosis of RTT was excluded in all three autism patients. Abnormalities of dendritic and axonal growth were found after autism-related MeCP2 mutants were expressed in mouse cortical neurons; suggesting that autism-related MECP2 mutations impair the proper development of neurons.ConclusionsOur study identified genetic mutations of the MECP2 gene in autism patients, which were previously considered to be associated primarily with RTT. This finding suggests that loss-of-function mutations of MECP2 may also lead to autism spectrum disorders.Electronic supplementary materialThe online version of this article (doi:10.1186/s13229-017-0157-5) contains supplementary material, which is available to authorized users.

Nested oscillatory dynamics in cortical organoids model early human brain network development

“…Mutations in the Methyl-CpG-binding protein 2 (MECP2) gene lead to a severe disruption in cortical development that account for many symptoms of Rett syndrome, autism, schizophrenia and other neurological disorders (Amir et al, 1999;Cohen et al, 2002;Du et al, 2016;Liu et al, 2016;Wen et al, 2017). MECP2 is involved on the epigenetic regulation of target genes by binding to methylated CpG dinucleotides promoter regions, acting as a transcriptional modulator ( Figure 4A).…”

Locus-specific DNA methylation of Mecp2 promoter leads to autism-like phenotypes in mice

“…Loss of MECP2 results in Rett syndrome (RTT) 11 , and patients with RTT exhibit a broad range of impairment in social behaviors, cognition, and coordination. Recently, mutations in MECP2 have also been identified in sporadic ASD patients 12 . Furthermore, increased MECP2 promotor methylation and decreased MECP2 expression were observed in the brain of ASD patients 7,8 , but their causative role in the ASD pathogenesis remains to be clarified.…”

Cyclin-dependent-like kinase 5 is required for pain signalling in both human neurons and mouse models

“…Recently, genes such as MeCP2 and Ca2+/calmodulin-dependent protein kinase IIα (CaMKIIα), which have been implicated in the pathogenesis of ASD (48)(49)(50), and that are highly expressed in the CNS, have also been localized to the peripheral nervous system where they regulate sensory modalities (51,52). However, a role in nociception had not been described so far.…”