Molecular regulation of the axon–myelin interface in development and repair

Accurate myelination of neuronal circuits is essential for the efficient function of the vertebrate nervous system, as the exact amount of myelin ensheathing an axon influences the timing and energy efficiency of neurotransmission. Its importance becomes evident in multiple sclerosis (MS), when myelin damage disrupts conduction and ultimately causes long-term neuronal loss. Although remyelination occurs, regenerated sheaths remain abnormally thin and short, failing to fully restore function. Promoting efficient myelin formation and repair is therefore a critical therapeutic target - yet the molecular mechanisms regulating accurate sheath growth in development and regeneration remain poorly understood. I propose that dynamic regulation of proteins along the axon-myelin interface—the direct contact site between axons and myelin—is critical for accurate myelin formation and repair. In particular, paranodes, specialised adhesion domains at this interface, are among the first structures disrupted in MS; and mutations in paranodal proteins cause severe developmental myelin growth defects reminiscent of MS pathology. However, the molecular organisation and dynamic regulation of paranodes remain largely unknown, due to technical limitations in profiling this subdomain in vivo. To address this, I will combine zebrafish models with newly developed tools for in vivo proximity proteomics and endogenous protein reporters. This approach enables the first in vivo proteomic screen to specifically profile the paranodal proteome during myelin growth and repair. Candidate regulators will be validated using CRISPR-based gene targeting in zebrafish and tested for conservation in mammalian systems. By integrating sub-cellular proteomics with advanced live-imaging and careful cross-species validation, this project will identify key-regulators of paranodal dynamics; and provide valuable insights into the mechanism underlying efficient myelin formation and regeneration after damage.