|dc.description.abstract||Understanding the molecular events in palate development is a prerequisite to more effective treatments of cleft palate. The secondary palate in humans and mice forms from shelves of mesenchyme covered with medial edge epithelium (MEE). These shelves adhere to form the midline epithelial seam (MES). MES cells then proceed through epithelial to mesenchymal transition (EMT) and/or apoptosis to yield a fused palate. Adhesion of opposing MEE is a crucial event whose alteration causes cleft palate. Previous studies showed that chondroitin sulphate proteoglycans (CSPG) on the apical surfaces of MEE was an important factor in palatal shelf adhesion. In this study we investigated decorin and biglycan, being expressed in numerous craniofacial tissues, as potential proteoglycans involved in palatal shelf adhesion.
We used a laser capture microdissection (LCM) technique to collect MEE cells and real-time polymerase chain reaction, to determine mRNA levels of decorin and biglycan that correctly reflect changes in gene expression during various stages of palatal shelf fusion (Embryonic days 13.5, 14.0 and 14.5). Both decorin and biglycan were expressed on the apical surface as well as between the MEE cells. We found that biglycan protein and mRNA levels peaked as the palatal shelves adhered. Decorin on the other hand was less abundant on the surface and had reduced mRNA levels that might be due to the regulatory effects of TGFβ. Nevertheless, the temporal expression of both decorin and biglycan on the apical surface of MEE was suggestive of an important role in palatal adhesion.||