Slug in the outgrowth & EMT during maxillary process development

Slug is a zinc-finger transcription factor and is involved in several important developmental processes, like the formation of mesoderm, the regulation of cell migration, the control of morphogenesis and the formation of pre-migratory and migratory neural crest cell populations. Especially, it is reportedly participated in the inducing of epithelial-mesenchymal transitions (EMTs) which convert epithelial cells into migratory mesenchymal cells. During the early face forming stage, the maxilla and lip are formed by the fusion and confluence of facial primordia called the maxillary, the lateral nasal and the frontonasal process. Although Slug is expressed in this region, the function of this gene in facial development is not clearly understood. Objectives: To test that Slug is related to the development of the maxillary process and the cell migration for formation of maxilla. Methods: We induced the overexpression of Slug at the maxillary process by the microinjection of constructed Slug virus. Slug expressing cells were traced by DiI labelling to the distal edge of maxillary process. In addition, we showed the change of skeletal morphology by skeletal staining. The section indicated histological morphology by the H&E staining, and subjected to E-cadherin immunohistochemistry and PCNA to confirm the cell proliferation. Results: It resulted in the acceleration of proximo-distal growth of the maxillary process and the change of the fusion point of maxillary and lateral nasal process. In the epithelial region, E-cadherin expression was down-regulated by Slug. Conclusion: From these results, we could confirm that Slug is involved in the control of outgrowth of maxillary process and the fusion with lateral nasal process. Moreover, we could understand roles of Slug and underlying mechanisms for the proximo-distal patterning as well as the fusion of facial processes for the developmental patterning of maxilla and upper lip.