Chicken Dead End Homologue Protein is a Nucleoprotein of Germ Cells Including Primordial Germ Cells

The dead end gene, coding an RNA binding protein, is predominantly expressed in the germ cells of vertebrates. Recently, we cloned chicken dead end homologue (CDH) and showed that expression of CDH mRNA is highly specific to primordial germ cells (PGCs) at early embryonic stages. To date, the subcelluler localization of Dead end protein in germ cell has been largely unknown due to lack of an antibody. Here, we raised a polyclonal antibody against chicken dead end homologue (CDH) to elucidate its subcellular localization in the germ cells. For comparative studies with CDH, a polyclonal antibody against chicken vasa homologue (CVH), a well-known germ cell marker, was also raised. Immunoblotting analysis for CDH protein showed a single band with a molecular size of approximately 60 kDa in the ovarian and testicular proteins. Immunofluorescence studies revealed that CDH protein was exclusively localized in the nuclei of primordial germ cells (PGCs) and germ cells at later stages, while CVH was localized in the cytoplasm. Interestingly, the germ cells distributed at the basal sides of seminiferous epithelia, such as spermatogonia, were strongly positive to CDH protein. The current study provides novel evidence that CDH is a nucleoprotein of germ cells, including PGCs.