Characterization of the DNA binding property of emerin

Abstract

Emerin is an inner nuclear membrane protein, which is the gene product responsible for X-linked Emery-Dreifuss muscular dystrophy (X-EDMD). In this study we extracted emerin from mammalian cells and examined the DNA binding property by in vitro binding assay with double-strand DNA cellulose. We prepared emerins from two sources; the native emerin in HeLa cells and the recombinant human emerin produced in COS7. These samples were incubated with DNA cellulose, and the bound proteins were directly eluted with salt-containing buffers. These elutants were subsequently analyzed by SDS-PAGE and western blotting. The results showed that 1) both HeLa cell emerin and recombinant COS7 emerin were recovered in the elutants of the binding assays, and 2) several other nuclear proteins were always co-isolated in the purification procedure of recombinant COS7 emerin. These results suggest that emerin is tightly integrated in some protein "complex" with other nuclear components and binds DNA as a protein complex. In this study we demonstrated that emerin directly or indirectly binds to DNA.