A conserved Arf-GEF modulates axonal integrity through RAB-35 by altering neuron-epidermal attachment

Area of Science:

• Neuroscience
• Cell Biology
• Genetics

Background:

• Sensory neurons in the skin are exposed to mechanical strain, requiring mechanisms to maintain axonal integrity.
• In C. elegans, UNC-70/β-spectrin and RAB-35 stabilize neuron-epidermal attachments against mechanical stress.
• The molecular pathway regulating these specialized attachments was previously elusive.

Purpose of the Study:

• To identify novel molecular components regulating axonal integrity of mechanosensitive neurons in the skin.
• To elucidate the mechanism by which AGEF-1 maintains neuron-epidermal attachment stability.

Main Methods:

• Unbiased genetic screen to identify factors impacting axonal maintenance.
• Functional characterization of AGEF-1 in C. elegans skin.
• Biochemical assays to determine AGEF-1 interaction with RAB-35.
• Cross-species conservation analysis using human ortholog BIG2.

Main Results:

• Identification of AGEF-1, a guanine nucleotide exchange factor (GEF), as crucial for axonal maintenance.
• AGEF-1 functions selectively in the skin to regulate the integrity of mechanosensitive neurons.
• AGEF-1 binds to and regulates the activity of epidermal RAB-35, stabilizing neuron-epidermal attachments.
• The human ortholog BIG2 can functionally replace AGEF-1, indicating high conservation.

Conclusions:

• AGEF-1 is a key regulator of neuron-epidermal attachment stability and axonal integrity.
• The AGEF-1/RAB-35 pathway represents a conserved mechanism for maintaining sensory neuron function under mechanical stress.
• This study reveals the molecular machinery fine-tuning these attachments throughout life.