Rhox6 regulates the expression of distinct target genes to mediate mouse PGCLC formation and ESC self-renewal

BACKGROUND

Mouse embryonic stem cells (mESCs) not only retain the property of self-renewal but also have the ability to develop into primordial germ cell-like cells (PGCLCs). However, knowledge about the mechanisms of transcriptional regulation is still limited. Rhox6, a member of the homeobox family that is located on the X chromosome, is highly expressed within PGCLCs in vivo and in vitro. However, the detailed effects of Rhox6 on PGCLC specification and mESC maintenance remain unclear.

RESULTS

In this study, we found that overexpression of Rhox6 favors the formation of PGCLCs, while depletion of Rhox6 inhibits the generation of PGCLCs. Mechanistically, Rhox6 directly induces the expression of Nanos3 during the specification of PGCLCs. Subsequently, downregulation of Nanos3 expression is sufficient to decrease the ability of Rhox6 to induce PGCLC formation. Moreover, we found that depletion of Rhox6 expression facilitates the self-renewal of mESCs. High-throughput sequencing revealed that suppression of Rhox6 transcription significantly increases the expression of pluripotency genes. Functional studies further demonstrated that Rhox6 directly represses the transcription of Tbx3. Therefore, knockdown of the expression of the latter impairs the self-renewal of mESCs promoted by Rhox6 downregulation.

CONCLUSIONS

Our study reveals that overexpression of Rhox6 is beneficial for PGCLC generation through induction of Nanos3, while downregulation of Rhox6 contributes to mESC self-renewal by increasing Tbx3. These findings help elucidate the early development of mouse embryos.

NANOS3 suppresses premature spermatogonial differentiation to expand progenitors and fine-tunes spermatogenesis in mice

In the mouse testis, sperm originate from spermatogonial stem cells (SSCs). SSCs give rise to spermatogonial progenitors, which expand their population until entering the differentiation process that is precisely regulated by a fixed time-scaled program called the seminiferous cycle. Although this expansion process of progenitors is highly important, its regulatory mechanisms remain unclear. NANOS3 is an RNA-binding protein expressed in the progenitor population. We demonstrated that the conditional deletion of Nanos3 at a later embryonic stage results in the reduction of spermatogonial progenitors in the postnatal testis. This reduction was associated with the premature differentiation of progenitors. Furthermore, this premature differentiation caused seminiferous stage disagreement between adjacent spermatogenic cells, which influenced spermatogenic epithelial cycles, leading to disruption of the later differentiation pathway. Our study suggests that NANOS3 plays an important role in timing progenitor expansion to adjust to the proper differentiation timing by blocking the retinoic acid (RA) signaling pathway.

Association of miR-181c/d gene locus rs8108402 C/T polymorphism with susceptibility to Kawasaki disease in Chinese children

BACKGROUND

Kawasaki disease (KD) is an acute systemic vasculitis of unknown etiology. The rs8108402 C/T single nucleotide polymorphism (SNP) is located in the promoter region of miR-181-c/d gene and the intron of Nanos3 gene. The miR-181 family contributes to the pathogenesis of cardiovascular and inflammatory disorders, while Nanos3 is involved in DNA transcription regulation and cell proliferation. However, no studies have examined the association between miR-181c/d and Nanos3 polymorphisms and the susceptibility and progression of KD.

OBJECTIVE

The purpose of our study is to examine the association of miR-181c/miR-181d/Nanos3 gene locus rs8108402 C/T polymorphism with KD susceptibility, intravenous immunoglobulin (IVIG) responsiveness, and the development of coronary artery lesions (CAL).

METHODS

Peripheral blood specimens from 100 children with KD and 100 healthy children were collected. The polymorphism of rs8108402 C/T was detected using polymerase chain reaction-sequencing-based typing technique.

RESULTS

There were statistically significant differences in C and T allele frequency distributions between the KD group and healthy controls for the polymorphic site rs8108402 C/T (P = 0.002). The distribution of the genotypes CC, CT, and TT also presented statistical significant difference between the KD and control groups (P = 0.003). Compared to the rs8108402 C allele, the T allele was associated with increased KD susceptibility (OR = 2.080, 95% CI = 1.317∼3.283). However, there were no significant associations discovered between the rs8108402 C/T polymorphism and CAL formation or IVIG unresponsiveness in the study.

CONCLUSION

SNP rs8108402 C/T located in the miR-181c/d promoter and Nanos3 intronic region is associated with susceptibility to Kawasaki disease but not with the development of coronary artery lesions or IVIG unresponsiveness in Chinese children.

Generation of chimeric mice with spermatozoa fully derived from embryonic stem cells using a triple-target CRISPR method for Nanos3†

Conditional knockout (cKO) mice have contributed greatly to understanding the tissue- or stage-specific functions of genes in vivo. However, the current cKO method requires considerable time and effort because of the need to generate two gene-modified mouse strains (Cre transgenic and loxP knockin) for crossing. Here, we examined whether we could analyze the germ cell-related functions of embryonic lethal genes in F0 chimeric mice by restricting the origin of germ cells to mutant embryonic stem cells (ESCs). We confirmed that the full ESC origin of spermatozoa in fertile chimeric mice was achieved by the CRISPR/Cas9 system using three guide RNAs targeting Nanos3, which induced germ cell depletion in the host blastocyst-derived tissues. Among these fertile chimeric mice, those from male ESCs with a Dnmt3b mutation, which normally causes embryo death, also produced F1 mice derived exclusively from the mutant ESCs. Thus, our new chimeric strategy readily revealed that Dnmt3b is dispensable for male germ cell development, in agreement with a previous cKO study. Our new approach enables us to analyze the germ cell functions of embryonic lethal genes in the F0 generation without using the current cKO method.

Nanos3, a cancer-germline gene, promotes cell proliferation, migration, chemoresistance, and invasion of human glioblastoma

Background

Radiotherapy, chemotherapy, and surgery have made crucial strides in glioblastoma treatment, yet they often fail; thus, new treatment and new detection methods are needed. Aberrant expression of Nanos3 has been functionally associated with various cancers. Here, we sought to identify the clinical significance and potential mechanisms of Nanos3 in human glioblastoma.

Methods

Nanos3 expression was studied in nude mouse glioblastoma tissues and glioblastoma cell lines by immunohistochemistry, Western blot, and RT-PCR. Clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 gene editing assay was performed to generate the Nanos3 knockdown glioblastoma cell lines. The effects of Nanos3 on glioblastoma cells proliferation, migration, invasion, chemoresistance, germ cell characteristics, and tumor formation were analyzed by CCK8, transwell, cell survival experiments and alkaline phosphatase staining in vitro and in nude mouse models in vivo. Correlation between the expression of stemness proteins and the expression of Nanos3 was evaluated by Western blot.

Results

We found that Nanos3 was strongly expressed in both glioblastoma cell lines and tissues. Western blot and sequencing assays showed that the Nanos3 knockdown glioblastoma cell lines were established successfully, and we discovered that Nanos3 deletion reduced the proliferation, migration, and invasion of glioblastoma cells in vitro (P < 0.05). Nanos3 knockdown enhanced the sensitivity of glioblastoma cells to doxorubicin (DOX) and temozolomide (TMZ) (P < 0.05), and Nanos3^+/- glioblastoma cell lines did not show the characteristics of the germline cells. In addition, Nanos3 deletion inhibited subcutaneous xenograft tumor growth in vivo (P < 0.001). Moreover, the oncogenesis germline protein levels of CD133, Oct4, Ki67, and Dazl decreased significantly in glioblastoma cells following Nanos3 knockdown.

Conclusions

Both in vitro and in vivo assays suggest that Nanos3, which is a cancer-germline gene, initiates the tumorigenesis of glioblastoma via acquiring the oncogenesis germline traits. These data demonstrate that ectopic germline traits are necessary for glioblastoma growth.

Nanos3 of the frog Rana rugosa: Molecular cloning and characterization

Nanos is expressed in the primordial germ cells (PGCs) and also the germ cells of a variety of organisms as diverse as Drosophila, medaka fish, Xenopus and mouse. In Nanos3-deficient mice, PGCs fail to incorporate into the gonad and the size of the testis and ovary is thereby dramatically reduced. To elucidate the role of Nanos in an amphibian species, we cloned Nanos3 cDNA from the testis of the R. rugosa frog. RT-PCR analysis showed strong expression of Nanos3 mRNA in the testis of adult R. rugosa frogs, but expression was not sexually dimorphic during gonadal differentiation. In Nanos3-knockdown tadpoles produced by the CRISPR/Cas9 system, the number of germ cells decreased dramatically in the gonads of both male and female tadpoles before sex determination and thereafter. This was confirmed by three dimensional imaging of wild-type and Nanos3 knockdown gonads using serial sections immunostained for Vasa, a marker specific to germ cells. Taken together, these results suggest that Nanos3 protein function is conserved between R. rugosa and mouse.

Knockdown of the germ cell factor Dead end induces multiple transcriptional changes in Atlantic cod (Gadus morhua) hatchlings

The RNA binding protein Dead end (DnD) is essential for maintaining viable germ cells in vertebrates and silencing of the gene has been demonstrated to cause sterility in several mammalian and fish species. Here we investigated transcriptome changes in hatched larvae of Atlantic cod induced by DnD knockdown using morpholino oligonucleotides (MO) injected in two-cell embryos. Whereas no fluorescently labeled germ cells were shown in embryos coinjected with dnd MO and nanos3 3'UTR coupled to green fluorescent protein, DnD knockdown had no visible effect on the number and location of Vasa protein positive cells in larvae. However, quantitative real-time RT-PCR (qPCR) revealed decreased vasa, nanos3 and tudor domain containing protein 7 mRNA expression and genome-wide oligonucleotide microarray analyses indicated profound suppression of genes involved in development and regulation of the reproductive system. DnD morphants showed lowered expression of genes encoding proteins involved in lipid, retinoid, cholesterol and steroid metabolism, including those with roles in sex hormone metabolism. Biotransformation of lipophilic compounds appeared suppressed too, as evidenced by down-regulation of several key genes from the phases 1 and 2 detoxification pathways. Effects of DnD silencing were highly pleiotropic and consisted of endocrine and metabolic changes, massive induction of histones and suppression of diverse developmental processes, including erythropoiesis and formation of extracellular matrix. While transient inhibition of dnd mRNA translation did not block development of primordial germ cells until hatch, results suggested that ablation of DnD might have major indirect consequences, including suppression of reproductive functions.