Single-cell analysis of nonhuman primate preimplantation development in comparison to humans and mice.

BACKGROUND: Genetic programs underlying preimplantation development and early lineage segregation are highly conserved across mammals. It has been suggested that nonhuman primates would be better model organisms for human embryogenesis, but a limited number of studies have investigated the monkey preimplantation development. In this study, we collect single cells from cynomolgus monkey preimplantation embryos for transcriptome profiling and compare with single-cell RNA-seq data derived from human and mouse embryos. RESULTS: By weighted gene-coexpression network analysis, we found that cynomolgus gene networks have greater conservation with human embryos including a greater number of conserved hub genes than that of mouse embryos. Consistently, we found that early ICM/TE lineage-segregating genes in monkeys exhibit greater similarity with human when compared to mouse, so are the genes in signaling pathways such as LRP1 and TCF7 involving in WNT pathway. Last, we tested the role of one conserved pre-EGA hub gene, SIN3A, using a morpholino knockdown of maternal RNA transcripts in monkey embryos followed by single-cell RNA-seq. We found that SIN3A knockdown disrupts the gene-silencing program during the embryonic genome activation transition and results in developmental delay of cynomolgus embryos. CONCLUSION: Taken together, our study provided new insight into evolutionarily conserved and divergent transcriptome dynamics during mammalian preimplantation development.

[High-level androgen enhances the differentiation of hESCs into male primordial germ cells].

OBJECTIVE: To observe the effects of different concentrations of testosterone on the differentiation of human embryonic stem cells (hESCs) into early male germ cells and investigate the potential impact of high-level androgen exposure in early pregnancy in women with polycystic ovary syndrome (PCOS) on the fertility and primordial germ cell reserve of the male offspring in adulthood. METHODS: We used 2 µmol/L retinoic acid to induce the differentiation of hESCs (46, XY) into male germ cells in vitro and meanwhile treated them with testosterone (T) at 0 mol/L, 3×10－7 mol/L, 5×10－7 mol/L, 15×10－7 mol/L, 45×10－7 mol/L, and 135×10－7 mol/L, respectively. We collected the cell samples at 0, 4, 7 and 14 days to determine the expressions of the specific genes and compare the differentiation process and efficiency of the male germ cells in different stages. RESULTS: There was no difference in the morphology of the hESCs treated with different concentrations of testosterone in the same differentiation stage. The expression of the marker gene DAZL in the primordial germ cells peaked on the 4th day of differentiation, significantly higher in the 15×10－7, 45×10－7 and 135×10－7 mol/L groups than in the 3×10－7 mol/L group (P < 0.05), and that of the specific gene SCP3 in the early-meiosis germ cells began to increase on the same day, more significantly in the 45×10－7mol/L than in the 3×10－7 mol/L and 5×10－7 mol/L groups (P < 0.01), and peaked on the 7th day, dramatically higher in the 15×10－7, 45×10－7 and 135×10－7 mol/L groups than in the 3×10－7 mol/L group (P < 0.01). Immunofluorescence staining and flow cytometry showed a T concentration-dependent increase in the expression of DAZL at 4 days and those of SCP3 and VASA at 7 days. Moreover, the expression of the androgen receptor (AR) in the hESCs began to rise on the 4th day and kept going up till the 14th day, higher in the high-concentration than in the low-concentration T groups in the same stage of differentiation, though with no statistically significant difference (P > 0.05). CONCLUSIONS: Exposure to high-level androgen during the differentiation of hESCs into early male germ cells can induce earlier expression of AR and earlier differentiation of hESCs into early male germ cells, which may result in insufficient reserve of male primary germ cells in the male offspring of PCOS women and affect their fertility after adulthood. hESCs can be used as an in vitro model to study the effects of intrauterine hyperandrogen on the reproductive development of male offspring in PCOS patients, which is also contributive to researches on the etiology of male infertility.

[Differentiation of embryonic stem cells from the embryos of the couples with male asthenozoospermia and Robertsonian translocation into germ cells].

OBJECTIVE: To assess the risk of male infertility in the offspring conceived through assisted reproductive technology (ART) byin vitroinductionof the differentiation of embryonic stem cells (ESCs) derived from the embryos of the couples with male asthenozoospermia and Robertsonian translocation (RT) into germ cells. METHODS: We established a CCRM16ESC line with the karyotype of 46, XY, +14, rob(13; 14) (q10; q10) from the embryo donated by a patientwithasthenozoospermiaand RT and his wife by isolation of the inner cell mass of blastula, culturing, passaging, and amplification,followed by in vitro induction and differentiationof the ESCs into germ cells with ratinoic acid(RA) at 2 mol/L. Then, we analyzed the process of differentiation and the expressions of its related genes and compared them with those in the normal CCRM23ESCs. RESULTS: CCRM16 showed the typical characteristics of ESCs, expressing the pluripotency makers of NANOG, OCT4, TRA-1-181 and SSEA4, forming embryoid bodies, and differentiating into three germlayer tissues in vitro and in vivo. Intervention with 2 mol/LRAinduced direct differentiation of the ESCs into germ cells. The expressions of the primordial germ cell marker geneDAZLand the meiosis marker geneSCP3were markedly decreased in the CCRM16 as compared with those in the normal CCRM23 ESCs. CONCLUSIONS: The CCRM16ESC linewith the karyotype of46, XY, +14, rob(13; 14) (q10; q10) has thetypical characteristics of ESCs but an abnormal process of differentiation into germ cells in the early stage. In vitroinductionof the differentiation of ESCs into germ cells can be used for assessing the risk of male infertility in the offspring conceived through ART for asthenozoospermia patients.

[Differentiation of pluripotent stem cells into male germ cells: An update].

Pluripotent stem cells (PSCs), including embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), have the potential of differentiating into all types of adult cells. Today, mature functional sperm can be derived from mouse PSCs in vitro, and meanwhile primordial germ cells (PGCs) and meiotic prophase sperm cells can be generated from human ESCs/iPSCs (hESCs/hiPSCs). It is proposed that non-genetic azoospermia might be cured if functional sperm could be obtained from human PSCs (hPSCs) in vitro. It is also possible that healthy functional sperm could be derived from the patient with genetic factor-induced azoospermia by combining iPSCs and gene editing technology. IPSC-derived functional sperm have a higher clinical value for the avoidance of the sperm source and the issue of medical ethics. This article summarizes recent advances in the differentiation of PSCs into male germ cells in vitro, aiming to provide some reference for the treatment of male infertility with PSCs.

Promoter-dependent EGFP expression during embryonic stem cell propagation and differentiation.

Genetic modification is an important tool in embryonic stem (ES) cell research and requires efficient promoter systems. Here, we have compared the transcriptional activities of three ubiquitous promoters, elongation factor-1alpha (EF1alpha), phosphoglycerate kinase-1 (PGK), and cytomegalovirus (CMV), during propagation and differentiation of mouse (m) ES cells by using stable mES cell lines expressing enhanced green fluorescent protein (EGFP) under each of these promoters. In undifferentiated ES cells, the EGFP expression driven by the EF1alpha was most stable, followed by the PGK, whereas the down-regulation of EGFP expression driven by the CMV promoter was most significant during propagation up to passage 35. A similar pattern for the activities of these promoters was observed in embryoid bodies (EBs) during 14 days of differentiation, with brighter EGFP signals driven by the EF1alpha promoter versus the other two. Moreover, the EF1alpha and PGK promoters, but not CMV, were effective in almost all mES cell-differentiated neuronal cells, cardiomyocytes, and visceral endoderm cells, with the fluorescent signal intensity higher for EF1alpha and even for PGK. The CMV promoter yielded a weak fluorescent signal in about 60-80% of these differentiated cells, while a few differentiated cells with the CMV promoter showed bright EGFP expression like that with the EF1alpha promoter. These results extend previous observations for the activities of these promoters in mES cells and provide new information for choosing appropriate promoters to facilitate genetic modification of mES cells.

Cloning of LjCYC1 gene and nuclear localization of LjCYC1 protein in Lotus japonicus.

The LjCYC1 (Lotus japonicus Cycloidea-like 1) gene, a homolog of CYC (Cycloidea) belonging to the TCP [TB1(teosinte branched 1), CYC, PCFs (PCF1 and PCF2)] gene family and encoding a predicted transcription factor and being proposed controlling different aspects of plant development, was isolated from the papilionaceous plant Lotus japonicus by screening the genomic DNA library, in order to test the functional conservation and divarication of CYC-like genes in legume. Sequence analyses indicate that LjCYC1 gene contains two exons and one intron and encodes a 370-AA peptide LjCYC1. The putative protein, LjCYC1, contains a TCP domain and an R domain, being a member of the CYC/TB1 subfamily of TCP family, and has 39.0% identity with and 42.6% similarity to CYC. LjCYC1-cDNA was cloned through RT-PCR. Different regions of the LjCYC1-cDNA were fused with the report gene GUS and then the fused constructs were transiently expressed in the onion epidermal cells through particle bombardment. Results of GUS and DAPI staining showed that the chimeric proteins with TCP domain were localized within the nucleus, confirming that LjCYC1 may act as a transcription factor. But the TCP domain itself could not confer the nuclear localization because the chimeric proteins with TCP domain alone were dispersed all over the transformed cells.