A Carboxy-terminal Smarcb1 Point Mutation Induces Hydrocephalus Formation and Affects AP-1 and Neuronal Signalling...

Area of Science:

• Neuroscience
• Genetics
• Developmental Biology

Background:

• The BRG1/BRM-associated factor (BAF) chromatin remodelling complex is crucial for neuronal differentiation.
• Mutations in the SMARCB1 subunit are linked to rhabdoid tumors and neurodevelopmental disorders.
• The effects of specific non-truncating SMARCB1 mutations on brain development are not well understood.

Purpose of the Study:

• To establish and analyze a novel mouse model for the SMARCB1 c.1148del point mutation.
• To investigate the impact of this mutation on brain development using advanced imaging and molecular techniques.
• To understand the consequences of elongated SMARCB1 protein synthesis on neuronal function.

Main Methods:

• Generation of a new mouse model with the Smarcb1 c.1148del mutation.
• Magnetic resonance imaging (MRI) and histology for anatomical analysis.
• Single-cell RNA sequencing (scRNA-seq) to assess gene expression in newborn brains.

Main Results:

• Smarc b1^{1148del/1148del} mice exhibited hydrocephalus and enlarged ventricles during adolescence.
• No anatomical or histological differences were observed in embryonic and neonatal mutant brains compared to controls.
• scRNA-seq revealed normal brain cell composition but downregulated neuronal signaling genes (AP-1 family, neurite outgrowth) in newborns.

Conclusions:

• SMARCB1 plays a critical role in normal neurodevelopment.
• The c.1148del mutation leads to specific brain abnormalities and disturbed neuronal signaling.
• This mouse model provides new insights into the diverse phenotypes associated with SMARCB1 mutations.