The regulation of motor neuron migration by differential expression of chondroitin sulfotransferase in rat hindbrain development

Abstract

Chondroitin sulfate (CS) moieties of proteoglycans are extracellular matrix components that have been implicated in the timing and patterning of axon fasciculation during embryonic brain development. It, nonetheless, remains unclear if these moieties can also control neuronal soma migration in the developmental process. We hypothesized that the cranial motor neuron migration in the hindbrain is modulated by varying sulfation patterns of the chondroitins between the migrating and ready-to-migrate neurons. In this project, hindbrain explants of E11.5 Sprague Dawley rats were maintained in culture. In control cultures, time lapse video microscopy revealed advancement of neuronal cell bodies in the direction of the leading process away from the explant core. In test cultures treated with chondroitinase ABC, the neuronal cell bodies lost the directional movement but not the motility. Immunocytochemistry confirmed the presence of CS56 epitopes among Tuj-1-positive neurons not only in the explant core and those advancing beyond the core, but also in the environment surrounding the migrating neuronal cell bodies. In situ hybridization revealed the relatively abundant expression of chondroitin-4-sulfotransferase 2 (C4ST2) mRNA among cells heading away from the explant core. Taken together, the present results showed that CS moieties expressed by migrating neurons differ in sulfation pattern from those in the vicinity of non-migrating neurons.