The methyl-CpG-binding domain (MBD) is crucial for MeCP2's dysfunction-induced defects in adult newborn neurons

Area of Science:

• Neuroscience
• Genetics
• Molecular Biology

Background:

• Mutations in the MECP2 gene cause Rett syndrome (RTT), a neurodevelopmental disorder.
• Most RTT-associated MECP2 mutations are located within the methyl-CpG-binding domain (MBD).

Purpose of the Study:

• To investigate the role of the MBD in MECP2 function and RTT pathogenesis.
• To determine if an intact MBD is required for MECP2 to rescue neuronal deficits.

Main Methods:

• Generated MeCP2 mutant constructs: MeCP2-ΔMBD (MBD deletion) and MeCP2-T158M (mimicking an RTT mutation).
• Utilized MeCP2 knockdown in cultured hippocampal neurons and in vivo models (adult newborn dentate gyrus neurons).
• Assessed neuronal morphology (dendrite length, branching, synapse number) and spontaneous Ca(2+) oscillations.

Main Results:

• MeCP2 knockdown impaired neuronal morphology and Ca(2+) oscillations.
• Full-length hMeCP2 rescued these deficits.
• MeCP2-ΔMBD failed to rescue neuronal morphology and Ca(2+) oscillations.
• MeCP2-T158M partially rescued dendrite length and branching but not Ca(2+) oscillations.
• In vivo, hMeCP2-FL rescued deficits, while hMeCP2-ΔMBD did not.

Conclusions:

• An intact and functional MBD is critical for MECP2's role in cultured hippocampal and adult newborn neurons.
• The MBD is essential for MECP2 to regulate neuronal morphology and activity, suggesting its importance in RTT pathogenesis.