Nop2 is required for mammalian preimplantation development

Abstract

SUMMARY Nucleolar protein 2 (NOP2) is evolutionarily conserved from yeast to human, and has been found to play an important role in accelerating cell proliferation, cell-cycle progression, and tumor aggressiveness. The expression pattern and function of Nop2 during early mammalian embryo development, however, has not been investigated. We identified Nop2 as an essential gene for development to the blastocyst stage while performing an RNA interference (RNAi)-based screen in mouse preimplantation embryos. Nop2 is expressed throughout preimplantation development, with highest mRNA and protein accumulation at the 8-cell and morula stages, respectively. RNAi-mediated knockdown of Nop2 results in embryos that arrest as morula. NOP2-deficient embryos exhibit reduced blastomere numbers, greatly increased apoptosis, and impaired cell-lineage specification. Furthermore, knockdown of Nop2 results in global reduction of all RNA species, including rRNA, small nuclear RNA, small nucleolar RNA, and mRNA. Taken together, our results demonstrate that Nop2 is an essential gene for blastocyst formation, and is required for RNA processing and/or stability in vivo during preimplantation embryo development in the mouse.

Towards Functional Annotation of the Preimplantation Transcriptome: An RNAi Screen in Mammalian Embryos

“…S6). Additionally, our previous experiments using dsRNA resistant mRNA22 and different siRNAs targeting separate locations of same mRNA21 also support the specificity of dsRNA mediated RNAi as a screening tool. Importantly, recent reports of gene knockout phenotypes are consistent with our screen induced phenotypes ( Actl6a 65, Bcor 66, Ctr9 53, Gabpa 67, Pbrm1 68, Rtn4 69, Supt6 70 and Ube2a 71).…”

“…Under our conditions, control embryos after microinjection and culture show precisely the same morphological and developmental progression as embryos in utero (Fig. 1A) and the rate of blastocyst formation is greater than 90%2122.…”

“…In order to determine if the transcriptional profile of each gene might correlate with the observed phenotype, we characterized the normal expression pattern of each gene during preimplantation (Fig. 5B, and refs 21, 22, 27, 28, 41). Overall, we found no correlation of expression profile and phenotype.…”

The nucleolar protein NOP2 is required for nucleolar maturation and ribosome biogenesis during preimplantation development in mammals

“…It has been previously shown that NOP2 is localized in the nucleolus in cancer cells . However, immunostaining assay revealed a nonspecific distribution of NOP2 in mouse preimplantation embryos . The discrepancy prompted us to examine the NOP2 localization in early embryos with an alternative antibody (sc‐398884).…”

Identification of a novel embryo‐prevalent gene, Gm11545 , involved in preimplantation embryogenesis in mice

“…Because Gm11545 is specifically expressed in oocytes and preimplantation embryos, it is possible that the protein performs a function unique to embryonic development. To investigate whether Gm11545 is necessary for preimplantation development, we performed knockdown analysis by microinjecting Gm11545-derived dsRNA (dsRNA-Gm11545) into mouse zygotes at the pronuclear stage (21)(22)(23)(24) and confirmed knockdown of the target gene in embryos. Real-time qPCR measurement of mRNA showed that Gm11545 expression is reduced by 76 and 79%, compared with control, at 2-cell and morula stages, respectively (Fig.…”