Placental defects revealed by modelling Prader-Willi syndrome in mice.

The neurodevelopmental disorder Prader-Willi syndrome (PWS) is caused by paternally derived loss of gene expression from the imprinted interval on chromosome 15q11-q13. Recently, it has been suggested that the abnormal feeding-related behaviours characteristic of PWS can, in part, be developmentally programmed in utero via abnormal placental function. Here, we report that several PWS-associated genes were expressed in mouse placenta with three PWS-associated RNA transcripts, i.e. genes Magel2 and Necdin, and the lncRNA Sngh14, colocalised to the Kdr-positive (Kdr+) foetal endothelial cells of the labyrinth zone central to nutrient transport. In a novel PWS mouse model (Large+/-) we found markedly reduced expression of PWS-associated genes in the placenta and an associated ∼25% reduction in Kdr+ foetal endothelial cells. Although this did not directly translate into a significant reduction in foetal growth late in gestation, these data suggest that placental function and nutrient transfer from mother to foetus could be compromised in PWS contributing to later post-natal phenotypes.