Characterization of peripheral myelin protein 22 in zebrafish (zPMP22) suggests an early role in the development of the peripheral nervous system.

Peripheral myelin protein 22 (PMP22) is a component of compact myelin of the peripheral nervous system (PNS). Mutations affecting PMP22 are associated with hereditary neuropathies in humans and rodents. Although mammalian PMP22 is expressed in several tissues, the disease pathology is restricted to the PNS. We describe the characterization of a PMP22-related cDNA from zebrafish and the distribution of its cognate mRNA. Phylogenetic considerations and mRNA expression in cranial nerves are consistent with the interpretation that the encoded protein is the orthologue of mammalian PMP22. In situ hybridization analysis during development showed zebrafish PMP22 expression in embryonic sclerotome cells, in neural crest cells, and in migratory derivatives of both populations. Based on this specific expression pattern prior to the onset of myelination, we hypothesize that zebrafish PMP22 may play a role in early PNS development and that disturbance of such functions may contribute to the PNS-restricted defects caused by mutations in the mammalian PMP22 gene.