Nlrp5, also known as NLR family pyrin domain-containing 5, is a maternal-effect gene. It is crucial for normal pre-implantation and embryonic development. Nlrp5 is part of the subcortical maternal complex (SCMC), and its function is associated with the transition from oocyte to embryo, playing a role in maintaining the normal development of early embryos [1,2,3,4,7].

In mouse models, Nlrp5 hypomorph embryos fail to develop beyond the two-cell stage. Ovulated oocytes lacking Nlrp5 have abnormal mitochondrial localization, increased mitochondrial activity, leading to an accumulation of reactive oxygen species, mitochondrial depletion, and ultimately embryo demise. In sows, knockdown of NLRP5 expression in zygotes using RNA interference arrests early embryonic development, suggesting its essential role in zygotic genome activation [5,6]. In humans, mutations in NLRP5 are associated with female infertility, characterized by oocyte maturation abnormality and early embryonic arrest. Six novel NLRP5 variants were identified in four patients with arrested and severely fragmented embryos. Also, a novel homozygous frameshift variant in NLRP5 was found in a patient with primary infertility [2,4].

In conclusion, Nlrp5 is essential for early embryogenesis, mediating mitochondrial function in oocytes and embryos. Studies using gene-knockout models in mice and knockdown experiments in sows have revealed its critical role. In humans, Nlrp5 mutations are linked to infertility-related conditions, highlighting the importance of understanding Nlrp5 function for reproductive medicine [2,4,5,6].