Microexon in action: How tiny fragments in a protein tune function, drive disease

Area of Science:

• Biochemistry
• Molecular Biology
• Neuroscience

Background:

• Intrinsically disordered regions (IDRs) are crucial for protein function, often mediating interactions through liquid-liquid phase separation.
• Aberrant protein condensation is implicated in various neurological disorders, including autism spectrum disorder (ASD).

Purpose of the Study:

• To investigate how alternative splicing of a microexon within the CPEB4 intrinsically disordered region affects its phase separation properties.
• To explore the potential link between CPEB4 microexon inclusion and the molecular mechanisms of autism spectrum disorder.

Main Methods:

• Utilized in vitro biochemical assays to analyze the condensation behavior of CPEB4 variants with and without the microexon.
• Employed biophysical techniques to characterize the structural and dynamic properties of the protein condensates.

Main Results:

• The inclusion or exclusion of the microexon significantly altered the phase separation and condensation dynamics of the CPEB4 IDR.
• Differential condensation properties were observed, suggesting a direct impact of alternative splicing on protein behavior.

Conclusions:

• Alternative splicing of microexons within IDRs can finely tune protein phase separation, providing a regulatory mechanism for protein function.
• CPEB4 microexon splicing represents a potential molecular contributor to the pathogenesis of autism spectrum disorder.