Maternal depletion of NLRP5 blocks early embryogenesis in rhesus macaque monkeys (Macaca mulatta).

BACKGROUND Genetic defects in the oocyte can lead to female infertility due to failures in early embryogenesis. NLRP5 (NLR family, Pyrin domain containing 5) is a maternal effect factor required for early embryo development beyond the 2-cell stage in mice. The NLRP5 gene is conserved in mammals. Applying RNA interference (RNAi) technique in the macaque oocyte, we studied the in vitro effect of NLRP5 in preimplantation embryo development in rhesus macaques. METHODS Macaque MII oocytes were collected and subjected to NLRP5 long double-stranded (ds) RNA microinjection, followed by intracytoplasmic sperm injection and in vitro embryo culture. NLRP5 mRNA and protein expression were examined, and the progress of preimplantation embryo development was monitored until the blastocyst stage. RESULT While 46.7 and 41.4% of embryos derived from uninjected and EGFP (Enhanced Green Fluorescence Protein) dsRNA-injected oocytes (control) reached the blastocyst stage within 10 days of culture, respectively, only 7.0% of the NLRP5 knockdown embryos developed to term. The majority of NLRP5 knockdown embryos were arrested between the 8-cell and the 16-cell stages. CONCLUSIONS The work provides the first evidence that long dsRNA-mediated RNAi can be applied to specific gene silencing in rhesus macaque oocytes, and demonstrates that maternal NLRP5 plays an important role in preimplantation embryogenesis in non-human primates.