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Comment |
Maternally contributed Nlrp9b expressed in human and mouse ovarian follicles contributes to early murine preimplantation development. Amoushahi M et al. (2020) The aim of the study is to investigate presence and role of the gene encoding the maternally contributed nucleotide-binding oligomerization domain (NOD)-like receptors with a pyrin domain (PYD)-containing protein 9 (NLRP9) in human and mouse ovaries, respectively, and in preimplantation mouse embryo development by knocking down Nlrp9b. Expression levels of NLRP9 mRNA in human follicles were extracted from RNA sequencing data from previous studies. In this study, we performed a qPCR analysis of Nlpr9b mRNA in mouse oocytes and found it present. Intracellular ovarian distribution of NLRP9B protein was accomplished using immunohistochemistry. The distribution of NLRP9B was explored using a reporter gene approach, fusing NLRP9B to green fluorescent protein and microinjection of in vitro-generated mRNA. Nlrp9b mRNA function was knocked down by microinjection of short interference (si) RNA targeting Nlrp9b, into mouse pronuclear zygotes. Knockdown of the Nlrp9b mRNA transcript was confirmed by qPCR. We found that the human NLRP9 gene and its corresponding protein are highly expressed in human primordial and primary follicles. The NLRP9B protein is localized to the cytoplasm in the blastomeres of a 2-cell embryo in mice. SiRNA-mediated knockdown of Nlrp9b caused rapid elimination of endogenous Nlrp9b mRNA and premature embryo arrest at the 2- to 4-cell stages compared with that of the siRNA-scrambled control group. These results suggest that mouse Nlrp9b, as a maternal effect gene, could contribute to mouse preimplantation embryo development. It remains to investigate whether NLRP9 have a crucial role in human preimplantation embryo and infertility.//////////////////
NLRP9B protein is dispensable for oocyte maturation and early embryonic development in the mouse. Peng H et al. (2015) Nlrp9a, Nlrp9b and Nlrp9c are preferentially expressed in oocytes and early embryos in the mouse. Simultaneous genetic ablation of Nlrp9a and Nlrp9c does not affect early embryonic development, but the function of Nlrp9b in the process of oocyte maturation and embryonic development has not been elucidated. Here we show that both Nlrp9b mRNA and its protein are expressed in ovaries and the small intestine. Moreover, the NLRP9B protein was restricted to oocytes in the ovary and declined with oocyte aging. After ovulation and fertilization, NLRP9B protein was found in preimplantation embryos. Confocal microscopy demonstrated that it was mainly localized in the cytoplasm in the oocytes and blastomeres. Thus, this protein might play a role in oocyte maturation and early embryonic development. However, knockdown of Nlrp9b expression in GV-stage oocytes using RNA interference did not affect oocyte maturation or subsequent parthenogenetic development after Nlrp9b-deficient oocytes were activated. Furthermore, Nlrp9b knockdown zygotes could reach the blastocyst stage after being cultured for 3.5 d in vitro. These results provide the first evidence that the NLRP9B protein is dispensable for oocyte maturation and early embryonic development in the mouse.//////////////////
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Mutations |
1 mutations
Species: mouse
Mutation name:
type: null mutation
fertility: fertile
Comment: Five multicopy gene family genes expressed during the maternal-to-zygotic transition are not essential for mouse development. Wakabayashi M et al. (2020) Upon fertilization, oocytes transform into totipotent and pluripotent cleavage stage cells through the maternal-to-zygotic transition (MZT), which is regulated by maternal factors and zygotic genome activation (ZGA). Here, we investigated the in vivo function of 16 genes expressed with strong biases in oocytes and cleavage stage embryos by generating knockout (KO) mice. These MZT-associated genes are conserved across many mammalian species and include five multicopy gene family genes: the Nlrp9, Khdc1, Rfpl4, Trim43, and Zscan5 genes. Intercrosses between female KO and male KO mice, including Nlrp9a/b/c triple KO (TKO), Khdc1a/b/c TKO, Rfpl4a/b double KO (DKO), Trim43a/b/c TKO, and Zscan5b KO mice led to the birth to healthy offspring that in turn produced healthy offspring. Our study not only demonstrated that these MZT-associated genes are not essential for mouse development, but also provides valuable resources for analyzing the functions of these genes in other genetic backgrounds, in the presence of stressors, and under pathogenic conditions.//////////////////
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