Kanzaki Satoko, Tamura Shiori, Ito Toshiaki, Wakabayashi Mizuki, Saito Koji, Kato Shigeki, Ohta Yasutaka, Sekita Yoichi, Kimura Tohru
Laboratory of Stem Cell Biology, Department of Biosciences, Kitasato University School of Science, Kanagawa, Japan.
Research and Development Department, Prima Meat Packers Ltd Ibaraki Research Center, Ibaraki, Japan.
Reproduction. 2020 Aug;160(2):181-191. doi: 10.1530/REP-19-0516.
Nucleotide-binding oligomerization domain, leucine-rich repeat and pyrin domain-containing proteins (NRLPs) are central components of the inflammasome. Accumulating evidence has shown that a reproductive clade of NRLPs is predominantly expressed in oocyte to cleavage stage embryos and participates in mammalian preimplantation development as a component of a multiprotein complex known as the subcortical maternal complex (SCMC). Nlrp9s belong to the reproductive class of NLRPs; Nlrp9b is unique in acting as an inflammasome against rotavirus in intestines. Here we generated mice carrying mutations in all three members of the Nlrp9a/b/c gene (Nlrp9 triple mutant (TMut) mice). When crossed with WT males, the Nlrp9 TMut females were fertile, but deliveries with fewer pups were increased in the mutants. Consistent with this, blastocyst development was retarded and lethality to the preimplantation embryos increased in the Nlrp9 TMut females in vivo. Under in vitro culture conditions, the fertilized eggs from the Nlrp9 TMut females exhibited developmental arrest at the two-cell stage, accompanied by asymmetric cell division. By contrast, double-mutant (DMut) oocytes (any genetic combination) did not exhibit the two-cell block in vitro, showing the functional redundancy of Nlrp9a/b/c. Finally, Nlrp9 could bind to components of the SCMC. These results show that Nlrp9 functions as an immune or reproductive NLRP in a cell-type-dependent manner.
核苷酸结合寡聚化结构域、富含亮氨酸重复序列和吡啉结构域的蛋白（NRLPs）是炎性小体的核心组成部分。越来越多的证据表明，NRLPs的一个生殖相关分支主要在卵母细胞到卵裂期胚胎中表达，并作为一种称为皮质下母体复合体（SCMC）的多蛋白复合体的组成部分参与哺乳动物的植入前发育。Nlrp9s属于NLRPs的生殖相关类别；Nlrp9b在肠道中作为针对轮状病毒的炎性小体发挥作用，具有独特性。在此，我们培育了Nlrp9a/b/c基因的所有三个成员均发生突变的小鼠（Nlrp9三突变（TMut）小鼠）。当与野生型雄性小鼠杂交时，Nlrp9 TMut雌性小鼠具有生育能力，但突变体中出生幼崽数量减少的分娩情况有所增加。与此一致的是，在体内，Nlrp9 TMut雌性小鼠的囊胚发育受阻，植入前胚胎的致死率增加。在体外培养条件下，来自Nlrp9 TMut雌性小鼠的受精卵在二细胞阶段出现发育停滞，并伴有不对称细胞分裂。相比之下，双突变（DMut）卵母细胞（任何基因组合）在体外未表现出二细胞阻滞，显示出Nlrp9a/b/c的功能冗余。最后，Nlrp9可与SCMC的组分结合。这些结果表明，Nlrp9以细胞类型依赖的方式作为免疫或生殖NLRP发挥作用。
