Knockdown of NLRP5 arrests early embryogenesis in sows.

NLRP (NLR family, Pyrin domain containing) genes have both immunization- and reproduction-related clades in mammals. Nlrp5 is a reproduction-related gene, originally identified in the mouse, which plays a key role in mouse early embryogenesis. Previous studies estimated that the porcine NLRP5 gene is assigned to the long arm of chromosome 6 and expressed in oocytes. However, the expression pattern of the NLRP5 gene in the porcine reproductive tract, and the localization and function of NLRP5 protein in porcine preimplantation embryos are still unknown. Here, we show that NLRP5 transcripts and protein are detected exclusively in the ovary in the porcine reproductive tract. Furthermore, the transcripts display a sharp decline in porcine preimplantation embryos before zygotic genome activation, but the protein remains present through to the blastocyst stage, localize in the cytoplasm and close to the subcortex of porcine oocytes and preimplantation embryos. Moreover, the knockdown of NLRP5 expression in zygotes using RNA interference arrested early embryonic development. These results provide the first evidence that the NLRP5 gene is required for early embryogenesis in sows, suggesting that this gene might play an essential role in zygotic genome activation.