Continuous negative autoregulation fine-tunes dosage-sensitive transcription factor expression to maintain...

Area of Science:

• Neuroscience
• Molecular Biology
• Genetics

Background:

• Maintaining precise transcription factor (TF) levels is vital for post-mitotic neuron identity.
• The prevailing model suggests positive autoregulation maintains TF levels, but this is challenged here.

Purpose of the Study:

• To investigate the regulatory mechanisms of UNC-3 (Collier/EBF1-4) TF levels in *C. elegans* motor neurons.
• To determine if UNC-3 self-regulates its expression and the functional significance of this regulation.

Main Methods:

• Utilized genetics, biochemistry, and inducible protein depletion in *C. elegans*.
• Employed CRISPR/Cas9 for gene disruption and AlphaFold2 for protein interaction prediction.
• Investigated the role of the UNC-3 DNA-binding domain and interactions with chromatin factors.

Main Results:

• Demonstrated that UNC-3 negatively autoregulates its own transcription, a process essential for motor neuron identity and locomotion.
• Identified a dynamic balance between UNC-3 self-repression and positive input from CEH-20/PBX.
• Showed that disease-associated variants in the *EBF3* ortholog disrupt this self-repression, linking it to neurodevelopmental disorders.

Conclusions:

• Negative autoregulation, counterbalanced by positive input, is a key principle for stabilizing dosage-sensitive TF expression in post-mitotic neurons.
• This regulatory mechanism is critical for maintaining cell identity and has implications for understanding neurodevelopmental syndromes.