Characterization of desmosomal component expression during palatogenesis

Adhesion of the opposing palatal shelves is a critical first step in the me chanism for palatal fusion. Formation of desmosomal junctions between the t wo medial edge epithelia provides a mechanism for palatal shelf adhesion, R T-PCR and immunohistochemistry were used to determine the pattern of expres sion of desmosomal components during palatogenesis. Desmosomal expression w as specifically upregulated in the medial edge epithelia (MEE) at the early stages of palatal fusion as detected by both immunohistochemistry and elec tron microscopy. RT-PCR characterization of the desmosomal components detec ted all known elements, except desmocollin 1 (DSC1), Desmocollin 2 (DSC2) w as expressed as both the DSC2a and DSC2b variants. The two variants are exp ressed at the same level. Western analysis of desmoglein expression paralle led the RT-PCR result. The temporal and spatial upregulation of desmosomal gene expression is evidence that the MEE induce new gene expression require d to accomplish palatal shelf adhesion and initiate the first stage of pala tal fusion.