Analysis of the biological role of prion-related Shadoo protein on early mouse embryogenesis

Abstract: The prion family comprises of Prion, Shadoo and Doppel proteins, encoded by Prnp, Sprn and Prnd, respectively.Expression pattern of these genes in early mouse embryogenesis was investigated using RT-PCR experiments on FVB/N mice embryosand by in situ hybridization (HIS) at 3 early developmental stages. They were found to be expressed at all stages, in both placenta and embryo.Ubiquitous hybridization was observed for the three lociby HIS. These results are compatible with potential biological overlapping roles of these proteins during mouse embryogenesis. We also analyzed the transmission of an LS1.06 transgenic mice line, characterized by a 70% downregulationofSprngene expression.Only 5% of offspring from FVB/N LSI.06+/--Prnp+/-with FVB/N Prnp-/-crosses were of a FVB/N LSI.06+/--Prnp-/- genotype, suggestive ofa lethal-associated embryonic phenotype. However, crossing FVB/N LSI.06+/--Prnp-/-with Prnp-/- showed a Mendelian transmission rate. This suggested a physical linkage between the transgene integration site and Prnp locus. Indeed, the transgene integration site was found to be located within an intron of the mouse Api5 gene, at 37.5 Mbof thePrnp locus. It thus likely explains the observed transmission rates.