Neuronal network activity and connectivity are impaired in a conditional knockout mouse model with PCDH19 mosaic...

Area of Science:

• Neuroscience
• Genetics
• Molecular Biology

Background:

• Mutations in the PCDH19 gene cause Developmental and Epileptic Encephalopathy 9 (DEE9).
• Mosaic loss of protocadherin-19 (PCDH19) expression in neurons is implicated in DEE9, but its network effects are unclear.

Purpose of the Study:

• To investigate how PCDH19 mosaic expression affects neuronal network activity and circuits.
• To elucidate the mechanisms underlying DEE9 pathogenesis.

Main Methods:

• Utilized Pcdh19 mosaic mice models.
• Performed electrophysiological recordings and network activity analysis in vivo and in vitro.
• Examined hippocampal and limbic system structures and functions.

Main Results:

• Pcdh19 mosaic mouse hippocampus exhibits structural and functional synaptic defects.
• PCDH19-negative neurons show hyperexcitability.
• Reduced network firing rates and increased neuronal synchronization were observed in limbic areas.
• Decreased excitatory/inhibitory ratio and functional hyperconnectivity were found in Pcdh19 mosaic mice.

Conclusions:

• Altered PCDH19 expression significantly impacts neuronal circuit wiring and function.
• These findings provide insights into the pathogenesis of DEE9.
• PCDH19's role in network integrity is crucial for preventing epileptic encephalopathy.