Reverse Signaling by Semaphorin-6A Regulates Cellular Aggregation and Neuronal Morphology

Area of Science:

• Molecular and Cellular Neuroscience
• Cell Signaling Pathways
• Developmental Biology

Background:

• Transmembrane semaphorin 6A (Sema6A) is crucial for axon guidance, cell migration, and neuronal connectivity.
• Sema6A functions through context-dependent interactions with plexin receptors, PlxnA2 and PlxnA4.

Purpose of the Study:

• To investigate the cell-autonomous signaling capabilities of Sema6A.
• To elucidate the molecular mechanisms underlying Sema6A activation and its downstream effects.
• To understand the intricate interplay between Sema6A and its plexin receptors.

Main Methods:

• Investigated Sema6A signaling in both constitutive and clustering-dependent modes.
• Analyzed the recruitment and phosphorylation of Abl kinase upon Sema6A activation.
• Examined the effects of Sema6A reverse signaling on non-neuronal cells and primary neurons in vitro.
• Studied the cis-interaction between Sema6A and PlxnA2 and its impact on trans-binding.

Main Results:

• Sema6A exhibits cell-autonomous signaling through constitutive and clustering-dependent mechanisms.
• Sema6A activation leads to Abl recruitment and phosphorylation, impacting cytoskeletal regulators.
• Sema6A reverse signaling modulates cell surface area, complexity, and neuronal aggregation/neurite formation.
• Sema6A-PlxnA2 cis-interaction inhibits PlxnA2 binding of trans-Sema6A.

Conclusions:

• Sema6A possesses complex biochemical functions beyond canonical axon guidance.
• The interaction dynamics between Sema6A and plexins are highly context-dependent.
• Revealed novel insights into the molecular logic governing Sema6A signaling pathways.