Methyl-CpG Binding Protein 2 (Mecp2) Regulates Sensory Function Through Sema5b and Robo2

Area of Science:

• Neuroscience
• Developmental Biology
• Genetics

Background:

• Mutations in the MECP2 gene cause Rett syndrome, a neurodevelopmental disorder.
• Previous studies on MeCP2 deficiency primarily focused on motor impairments, leaving sensory defects poorly understood.
• Rodent models exhibit phenotypic differences compared to human Rett syndrome, necessitating alternative models like zebrafish.

Purpose of the Study:

• To investigate the role of Mecp2 in sensory neuron development using a zebrafish model.
• To elucidate the molecular mechanisms underlying Mecp2-associated sensory deficits.

Main Methods:

• Mecp2 expression was silenced in zebrafish embryos using two independent methods: mecp2-null mutation and morpholino-mediated knockdown.
• Peripheral innervation and sensory function of trigeminal ganglion neurons were assessed.
• Gene expression analysis (Sema5b, Robo2), chromatin immunoprecipitation (ChIP) assays, and cell-specific expression studies were performed.

Main Results:

• Mecp2 deficiency in zebrafish led to impaired peripheral innervation and sensory function of trigeminal neurons.
• These defects were dependent on Sema5b and Robo2, both of which were downregulated upon Mecp2 silencing.
• Mecp2 directly interacts with the promoters of Sema5b and Robo2, and Mecp2's function in these neurons is cell-autonomous.

Conclusions:

• Mecp2 plays a critical, cell-autonomous role in the development and function of trigeminal sensory neurons.
• The identified molecular pathway involving Sema5b and Robo2 provides new insights into Mecp2-mediated neurodevelopment.
• Zebrafish serve as a valuable model for studying sensory deficits in Rett syndrome, complementing findings from rodent models.