Apoptotic Activity of MeCP2 Is Enhanced by C-Terminal Truncating Mutations

Area of Science:

• Neuroscience
• Genetics
• Molecular Biology

Background:

• Methyl-CpG binding protein 2 (MeCP2) is crucial for neuronal function, with mutations linked to Rett syndrome and related disorders.
• C-terminal mutations in MECP2 are common, but their functional consequences, particularly on the MeCP2 C-terminus, remain poorly understood.

Purpose of the Study:

• To investigate the function of the MeCP2 C-terminus and the impact of specific mutations on neuronal survival.
• To identify the critical region within MeCP2 responsible for inducing neuronal apoptosis in vivo.
• To explore the conserved mechanisms, such as phosphorylation and transcription factor interactions, underlying MeCP2-induced apoptosis.

Main Methods:

• Utilized Drosophila melanogaster as a model organism for genetic studies of MeCP2 function.
• Employed HEK293T cells for in vitro validation of findings.
• Investigated the role of serine 80 (S80) phosphorylation and forkhead domain transcription factors (like FoxG1) in MeCP2-mediated apoptosis.

Main Results:

• Demonstrated that the human MECP2 R294X mutant allele, truncating the MeCP2 C-terminus, promotes apoptosis of neurons in Drosophila.
• Confirmed this pro-apoptotic effect in HEK293T cells.
• Mapped a small C-terminal sequence critical for inducing neuronal apoptosis.
• Validated the involvement of S80 phosphorylation and forkhead transcription factors in MeCP2-induced apoptosis, showing mechanistic conservation between flies and mammals.

Conclusions:

• The C-terminal domain of MeCP2 plays a vital role in neuronal survival.
• Specific C-terminal truncations, like R294X, can lead to neurodevelopmental defects through apoptosis.
• Interactions between the C- and N-termini of MeCP2 are essential for its healthy function, with conserved regulatory mechanisms across species.