Expression and influence of versican chondroitin sulfate proteoglycan on early chicken ear development.

摘要

It is well documented that the extracellular matrix (ECM) plays an important role in tissue development and function. A major component of the ECM, the proteoglycans which vary in core protein and in type and size of glycosaminoglycan (GAG) chains have recently received much attention. This study investigated the distribution of chondroitin sulfate proteoglycans (CSPGs) and their influence on vesicularization of the chicken ear. The results identified a morphological role for versican, while other CSPGs that included aggrecan, neurocan, and phosphacan did not play a role in otocyst development.; Versican showed abundant distribution in matrices of tissues that have been implicated in otic morphogenesis, including the otic epithelium, neural tube, and mesenchyme. Microinjection of either antibodies against chondroitin sulfate GAGs, or core protein to versican, perturbed folding of the otic placode which this abnormal development of the ear altered the structure of neighboring tissues. For example, the anti-versican antibody formed a shallow otic pit and delayed rostral and dorsal migration of neural crest cells (NCC) around the otic vesicle. These changes suggest that versican plays an important role as a guiding cue to the collective migration of the NCC. Observations of NCC migration after anti-versican injection showed either an arrest in movement or only sporadic movement.; Another perturbation resulting from anti-versican injection was loose adhesion of the otic epithelium to the neural tube, which prevented dorsal fold formation. Expression of versican in this epithelial junction suggest that versican can function as an anti-adhesive molecule. In addition, the mesenchyme appeared loosely arranged and more fibrous. At stage 11, an increase in mesenchyme was observed, but at stage 13, a reduction was observed. Preventing proper mesenchyme expansion and ECM deposition was associated to the delay in ventral folding.; Messenger RNA distribution showed that versican transcripts exist in the neural tube, otic epithelium, notochord, and mesenchyme. This ubiquitous distribution suggests that changes in otocyst development do not derive from a unique source.