Immunocytochemical detection of emerin within the nuclear matrix.

Emerin, the protein whose production is altered in the X-linked form of Emery-Dreifuss muscular distrophy, has been hypothesized to be associated with the nuclear matrix on the basis of biochemical studies. In addition, immunocytochemical data reported its localization at the nuclear periphery, on the nuclear lamina, in sections of several normal tissues. We investigated the association of emerin with the nuclear matrix, by using cultured cells (SaOS-2, MG63 and HeLa-S3) and their in situ extracted matrix as a model, and immunocytochemical methods, both at the light and electron microscope level. Our results show a normal presence of emerin in the cultured cells and the specific persistence of emerin on the lamina of the in situ extracted nuclear matrix. This suggests a tight binding between emerin and the nuclear lamina independently from the interactions between the C-terminal hydrophobic domain of the protein and the inner nuclear membrane.