Disordered breathing in a Pitt-Hopkins syndrome model involves Phox2b-expressing parafacial neurons and aberrant...

Area of Science:

• Neuroscience
• Genetics
• Respiratory Medicine

Background:

• Pitt-Hopkins syndrome (PTHS) is a rare neurodevelopmental disorder.
• It is characterized by intellectual disability, developmental delays, and abnormal breathing patterns.
• The genetic cause is haploinsufficiency of the Transcription Factor 4 (Tcf4) gene.

Purpose of the Study:

• To investigate the underlying mechanisms of behavioral abnormalities in PTHS.
• To identify potential therapeutic targets for respiratory dysfunction in PTHS.

Main Methods:

• Utilized a Tcf4 truncation (Tcf4^tr/+) mouse model exhibiting PTHS-like symptoms.
• Examined neuronal loss in the expiratory parafacial region and retrotrapezoid nucleus.
• Assessed the function of neurons regulating breathing in response to CO₂/H⁺.
• Investigated the therapeutic potential of targeting central Nav1.8 channels.

Main Results:

• Tcf4^tr/+ mice displayed breathing problems analogous to human PTHS patients.
• A selective loss of expiratory parafacial neurons was observed.
• Compromised function of CO₂/H⁺-sensitive neurons in the retrotrapezoid nucleus was identified.
• Pharmacological targeting of central Nav1.8 channels improved respiratory function in Tcf4^tr/+ mice at cellular and behavioral levels.

Conclusions:

• Loss of Tcf4 function leads to specific neuronal deficits contributing to PTHS respiratory abnormalities.
• Central Nav1.8 channels represent a promising therapeutic target for improving respiratory function in Pitt-Hopkins syndrome.