MicroRNA-34c expression in donor cells influences the early development of somatic cell nuclear transfer bovine embryos

Transmission of reduced levels of miR-34/449 from sperm to preimplantation embryos is a key step in the transgenerational epigenetic inheritance of the effects of paternal chronic social instability stress

The transgenerational effects of exposing male mice to chronic social instability (CSI) stress are associated with decreased sperm levels of multiple members of the miR-34/449 family that persist after their mating through preimplantation embryo (PIE) development. Here we demonstrate the importance of these miRNA changes by showing that restoring miR-34c levels in PIEs derived from CSI stressed males prevents elevated anxiety and defective sociability normally found specifically in their adult female offspring. It also restores, at least partially, levels of sperm miR-34/449 normally reduced in their male offspring who transmit these sex-specific traits to their offspring. Strikingly, these experiments also revealed that inducing miR-34c levels in PIEs enhances the expression of its own gene and that of miR-449 in these cells. The same induction of embryo miR-34/449 gene expression likely occurs after sperm-derived miR-34c is introduced into oocytes upon fertilization. Thus, suppression of this miRNA amplification system when sperm miR-34c levels are reduced in CSI stressed mice can explain how a comparable fold-suppression of miR-34/449 levels can be found in PIEs derived from them, despite sperm containing ~50-fold lower levels of these miRNAs than those already present in PIEs. We previously found that men exposed to early life trauma also display reduced sperm levels of miR-34/449. And here we show that miR-34c can also increase the expression of its own gene, and that of miR-449 in human embryonic stem cells, suggesting that human PIEs derived from men with low sperm miR-34/449 levels may also contain this potentially harmful defect.

From follicle to blastocyst: microRNA-34c from follicular fluid-derived extracellular vesicles modulates blastocyst quality

BACKGROUND

Within the follicular fluid, extracellular vesicles (EVs) guide oocyte growth through their cargo microRNAs (miRNAs). Here, we investigated the role of EVs and their cargo miRNAs by linking the miRNAs found in EVs, derived from the fluid of an individual follicle, to the ability of its oocyte to become a blastocyst (competent) or not (non-competent).

METHODS

Bovine antral follicles were dissected, categorized as small (2-4 mm) or large (5-8 mm) and the corresponding oocytes were subjected to individual maturation, fertilization and embryo culture to the blastocyst stage. Follicular fluid was pooled in 4 groups (4 replicates) based on follicle size and competence of the corresponding oocyte to produce a blastocyst. Follicular fluid-derived EVs were isolated, characterized, and subjected to miRNA-sequencing (Illumina Miseq) to assess differential expression (DE) in the 4 groups. Functional validation of the effect of miR-34c on embryo development was performed by supplementation of mimics and inhibitors during in vitro maturation (IVM).

RESULTS

We identified 16 DE miRNAs linked to oocyte competence when follicular size was not considered. Within the large and small follicles, 46 DE miRNAs were driving blastocyst formation in each group. Comparison of EVs from competent small and large follicles revealed 90 DE miRNAs. Cell regulation, cell differentiation, cell cycle, and metabolic process regulation were the most enriched pathways targeted by the DE miRNAs from competent oocytes. We identified bta-miR-34c as the most abundant in follicular fluid containing competent oocytes. Supplementation of miR-34c mimic and inhibitor during IVM did not affect embryo development. However, blastocyst quality, as evidenced by higher cell numbers, was significantly improved following oocyte IVM in the presence of miR-34c mimics, while miR-34c inhibitors resulted in the opposite effect.

CONCLUSION

This study demonstrates the regulatory effect of miRNAs from follicular fluid-derived EVs on oocyte competence acquisition, providing a further basis for understanding the significance of miRNAs in oocyte maturation and embryonic development. Up-regulation of miR-34c in EVs from follicular fluid containing competent oocytes and the positive impact of miR-34c mimics added during IVM on the resulting blastocysts indicate its pivotal role in oocyte competence.

Preimplantation Embryos Amplify Stress-Induced Changes in Sperm-Derived miRNA Content to Mediate Transgenerational Epigenetic Inheritance

Chronically stressing male mice can alter the behavior of their offspring across generations. This effect is thought to be mediated by stress-induced changes in the content of specific sperm miRNAs that modify embryo development after their delivery to oocytes at fertilization. A major problem with this hypothesis is that the levels of mouse sperm miRNAs are much lower than those present in preimplantation embryos. This makes it unclear how embryos could be significantly impacted without an amplification system to magnify changes in sperm miRNA content, like those present in lower organisms where transgenerational epigenetic inheritance is well established. Here, we describe such a system for Chronic Social Instability (CSI) stress that can explain how it reduces the levels of the miR-34b,c/449a,b family of miRNAs not only in sperm of exposed males but also in preimplantation embryos ( PIEs ) derived from their mating, as well as in sperm of male offspring. Sperm-derived miR-34c normally positively regulates expression of its own gene and that of miR-449 in PIEs. This feed forward, auto-amplification process is suppressed when CSI stress reduces sperm miR-34c levels. Its suppression is important for the transmission of traits to offspring because restoring miR-34c levels in PIEs from CSI stressed males, which also restores levels of miR-449 in them, suppresses elements of elevated anxiety and defective sociability normally found specifically in their female offspring, as well as reduced sperm miR-34 and miR-449 levels normally found in male offspring, who pass on these traits to their offspring. We previously published that the content of sperm miR-34/449 is also reduced in men raised in highly abusive and/or dysfunctional families. We show here that a similar miRNA auto-amplification system functions in human embryonic stem cells. This raises the possibility that PIEs in offspring of these men also display reduced levels of miR-34/449, enhancing the potential translational significance of these studies.

Sperm-borne microRNA-34c regulates maternal mRNA degradation and preimplantation embryonic development in mice

BACKGROUND

Studies have shown that sperm-borne microRNAs (miRNAs) are involved in mammalian preimplantation embryonic development. In humans, spermatozoan miR-34c levels are correlated with in vitro fertilization outcomes, such as embryo quality and the clinical pregnancy and live birth rates. In rabbits and cows, miR-34c improves the developmental competence of embryos generated by somatic cell nuclear transfer. However, the mechanisms underlying the regulation of embryonic development by miR-34c remain unknown.

METHODS

Female C57BL/6 mice (6-8 weeks old) were superovulated, and pronucleated zygotes were collected and microinjected with an miR-34c inhibitor or a negative-control RNA. The embryonic development of the microinjected zygotes was evaluated, and the messenger RNA (mRNA) expression profiles of the embryos at the two-cell, four-cell and blastocyst stages (five embryos per group) were determined by RNA sequencing analysis. Gene expression levels were verified by reverse transcription-quantitative polymerase chain reaction. Cluster analysis and heat map visualization were performed to detect differentially expressed mRNAs. Pathway and process enrichment analyses were performed using ontology resources. Differentially expressed mRNAs were systematically analyzed using the Search Tool for the Retrieval of Interacting Genes/Proteins database to determine their biological functions.

RESULTS

Embryonic developmental potential was significantly reduced in zygotes microinjected with the miR-34c inhibitor compared with those microinjected with a negative-control RNA. Two-cell stage embryos microinjected with an miR-34c inhibitor presented altered transcriptomic profiles, with upregulated expression of maternal miR-34c target mRNAs and classical maternal mRNAs. Differentially expressed transcripts were mainly of genes associated with lipid metabolism and cellular membrane function at the two-cell stage, with cell-cycle phase transition and energy metabolism at the four-cell stage; and with vesicle organization, lipid biosynthetic process and endomembrane system organization at the blastocyst stage. We also showed that genes related to preimplantation embryonic development, including Alkbh4, Sp1, Mapk14, Sin3a, Sdc1 and Laptm4b, were significantly downregulated after microinjection of an miR-34c inhibitor.

CONCLUSIONS

Sperm-borne miR-34c may regulate preimplantation embryonic development by affecting multiple biological processes, such as maternal mRNA degradation, cellular metabolism, cell proliferation and blastocyst implantation. Our data demonstrate the importance of sperm-derived miRNAs in the development of preimplantation embryos.

Differentially expressed microRNAs in biochemically characterized FrieswalTM crossbred bull semen

In addition to the transmission of paternal genome, spermatozoa also carry coding as well as noncoding microRNAs (miRNAs) into the female oocyte during the process of biological fertilization. Based on RNA deep sequencing, a total 28 number of differentially expressed miRNAs were cataloged in categorized Frieswal^TM crossbred (Holstein Friesian X Sahiwal) bull semen on the basis of conception rate (CR) in field progeny testing program. Validation of selected miRNAs viz. bta-mir-182, bta-let-7b, bta-mir-34c and bta-mir-20a revealed that, superior bull semen having comparatively (p < .05) lower level of all the miRNAs in contrast to inferior bull semen. Additionally, it was illustrated that, bta-mir-20a and bta-mir-34c miRNAs are negatively (p < .01) correlated with seminal plasma catalase (CAT) activity and glutathione peroxidase (GPx) level. Interactome studies identified that bta-mir-140, bta-mir-342, bta-mir-1306 and bta-mir-217 can target few of the important solute carrier (SLC) proteins viz. SLC30A3, SLC39A9, SLC31A1 and SLC38A2, respectively. Interestingly, it was noticed that all the SLCs were significantly (p < .05) expressed at higher level in superior quality bull semen and they are negatively correlated (p < .01) with their corresponding miRNAs as mentioned. This study may reflect the role of miRNAs in regulating few of the candidate genes and thus may influence the bull semen quality traits.

Correlation between Sperm Micro Ribonucleic Acid-34b and -34c Levels and Clinical Outcomes of Intracytoplasmic Sperm Injection in Men with Male Factor Infertility

Few studies have examined the correlation between sperm miRNA levels and clinical outcomes of intracytoplasmic sperm injection (ICSI). In this study, we aimed to assess the correlation of sperm miR-34b, miR-34c, miR-122, and miR-429 levels with ICSI outcomes in men with teratozoospermia and asthenozoospermia. TaqMan microRNA quantitative polymerase chain reaction was used to evaluate the relative expression of miRNAs in sperm. The relative miRNA levels quantified using a comparative method found that the four miRNAs were not associated with fertilization rate and early embryo development. However, revels of miR-34b and miR-34c in teratozoospermia sperm of the live birth group were significantly higher than those in the non-live birth group. Receiver operating characteristic curve analysis revealed that the optimal cut-off delta cycle threshold values of miR-34b and miR-34c were 8.630 and 7.883, respectively. Statistical analysis found that the levels of miR-34b and the miR-34c in teratozoospermic and asthenozoospermic sperm above the thresholds were not associated with the fertilization rate and the high-quality embryo rate above 50%; however, they were more likely to exhibit higher implantation, pregnancy, and live birth rates. miR-34b and miR-34c were significantly associated with ICSI clinical outcomes in male factor infertility, especially teratozoospermia. Further validation is required before it becomes a clinically valid reference indicator.

MiR-34b/c play a role in early sex differentiation of Amur sturgeon, Acipenser schrenckii

Background

Sex differentiation can be viewed as a controlled regulatory balance between sex differentiation-related mRNAs and post-transcriptional mechanisms mediated by non-coding RNAs. In mammals, increasing evidence has been reported regarding the importance of gonad-specific microRNAs (miRNAs) in sex differentiation. Although many fishes express a large number of gonadal miRNAs, the effects of these sex-biased miRNAs on sex differentiation in teleost fish remain unknown. Previous studies have shown the exclusive and sexually dimorphic expression of miR-34b/c in the gonads of the Amur sturgeon (Acipenser schrenckii), suggesting its potential role in the sex differentiation process.

Results

Using quantitative real-time PCR (qPCR), we observed that miR-34b/c showed consistent spatiotemporal expression patterns; the expression levels significantly increased during early sex differentiation. Using in situ hybridization, miR-34c was found to be located in the germ cells. In primary germ cells in vitro, the group subjected to overexpression and inhibition of miR-34c showed significantly higher proliferation ability and lower apoptosis, respectively, compared to the corresponding control group. Luciferase reporter assays using the ar-3′UTR-psiCHECK-2 luciferase vector suggested a targeted regulatory interaction between miR-34b/c and the 3′UTR of the androgen receptor (ar) mRNA. Furthermore, miR-34b/c and ar showed negative expression patterns during early sex differentiation. Additionally, a negative feedback regulation pattern was observed between foxl2 expression in the ovaries and amh and sox9 expression in the testes during early sex differentiation.

Conclusions

This study sheds new light on the roles of miR-34b/c in gonad development of Amur sturgeon, and provides the first comprehensive evidence that the gonad-predominant microRNAs may have a major role in sex differentiation in teleost fish.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12983-022-00469-6.

New Wenshen Shengjing Decoction Improves Early Embryonic Development by Maintaining Low Levels of H3K4me3 in Sperm

Background

New Wenshen Shengjing Decoction (NWSSJD), a traditional Chinese compound medicine, has significant effect on spermatogenesis disorder and can significantly improve sperm quality. Many components in NWSSJD can induce epigenetic modifications of different types of cells. It is not yet known whether they can cause epigenetic modifications in sperm or early embryos.

Objective

This study investigated the effect of NWSSJD on mouse early embryonic development and its regulation of H3K4me3 in mouse sperm and early embryos.

Methods

Spermatogenesis disorder was induced in male mice with CPA (cyclophosphamide). NWSSJD was administrated for 30 days. Then, the male mice were mated with the female mice with superovulation, and the embryo degeneration rate of each stage was calculated. Immunofluorescence staining was used to detect the expression of H3K4me3 in sperm and embryos at various stages. Western blotting was performed to detect methyltransferase SETD1B expression. The expressions of development-related genes (OCT-4, NANOG, and CDX2) and apoptosis-related genes (BCL-2 and p53) were measured with qRT-PCR.

Results

Compared with the CPA group, NWSSJD significantly reduced the H3K4me3 level in sperms, significantly increased the number of normal early embryos (2-cell embryos, 3-4-cell embryos, 8-16-cell embryos, and blastocysts) per mouse, and reduced the degeneration rate of the embryos. The expression levels of H3K4me3 and methyltransferase SETD1B in early embryos were significantly elevated by NWSSJD. Additionally, NWSSJD significantly promoted BCL-2 expression, while reducing p53 expression, thus inhibiting embryonic cell apoptosis. Moreover, the expressions of development-related genes OCT-4 and CDX2 were significantly increased by NWSSJD, but NANOG expression had no significant difference.

Conclusion

NWSSJD may promote early embryonic development possibly by maintaining low H3K4me3 levels in sperms and normal H3K4me3 modification in early embryos and by inhibiting embryonic cell apoptosis.

Association of microRNAs With Embryo Development and Fertilization in Women Undergoing Subfertility Treatments: A Pilot Study

Objective: Small non-coding RNAs, known as microRNAs (miRNAs), have emerging regulatory functions within the ovary that have been related to fertility. This study was undertaken to determine if circulating miRNAs reflect the changes associated with the parameters of embryo development and fertilization.

Methods: In this cross-sectional pilot study. Plasma miRNAs were collected from 48 sequentially presenting women in the follicular phase prior to commencing in vitro fertilization (IVF). Circulating miRNAs were measured using locked nucleic acid (LNA)-based quantitative PCR (qPCR), while an updated miRNA data set was used to determine their level of expression.

Results: Body mass index and weight were associated with the miRNAs let7b-3p and miR-375, respectively (p &lt; 0.05), with the same relationship being found between endometrium thickness at oocyte retrieval and miR-885-5p and miR-34a-5p (p &lt; 0.05). In contrast, miR-1260a was found to be inversely associated with anti-Mullerian hormone (AMH; p = 0.007), while miR-365a-3p, miR122-5p, and miR-34a-5p correlated with embryo fertilization rates (p &lt; 0.05). However, when omitting cases of male infertility (n = 15), miR122-5p remained significant (p &lt; 0.05), while miR-365a-3p and miR-34a-5p no longer differed; interestingly, however, miR1260a and mir93.3p became significant (p = 0.0087/0.02, respectively). Furthermore, age was negatively associated with miR-335-3p, miR-28-5p, miR-155-5p, miR-501-3p, and miR-497-5p (p &lt; 0.05). Live birth rate was negatively associated with miR-335-3p, miR-100-5p, miR-497-5p, let-7d, and miR-574-3p (p &lt; 0.05), but these were not significant when age was accounted for.However, with the exclusion of male factor infertility, all those miRNAs were no longer significant, though miR.150.5p emerged as significant (p = 0.042). A beta-regression model identified miR-1260a, miR-486-5p, and miR-132-3p (p &lt; 0.03, p = 0.0003, p &lt; 0.00001, respectively) as the most predictive for fertilization rate. Notably, changes in detectable miRNAs were not linked to cleavage rate, top quality embryos (G3D3), and blastocyst or antral follicle count. An ingenuity pathway analysis showed that miRNAs associated with age were also associated with the variables found in reproductive system diseases.

Conclusion: Plasma miRNAs prior to the IVF cycle were associated with differing demographic and IVF parameters, including age, and may be predictive biomarkers of fertilization rate.

Decreased miR-149 expression in sperm is correlated with the quality of early embryonic development in conventional in vitro fertilization

miRNAs play a critical role in the regulation of highly orchestrated gene expression profiles during spermatogenesis and early human embryonic development. However, there is much less information available on the effects of sperm-borne miRNAs on human embryonic development than on spermatogenesis. This study was designed to assess the relationship between two sperm-borne miRNAs (miR-34c and miR-149) and preimplantation embryo development in conventional in vitro fertilization treatment. A positive correlation was seen between a decreased level of miR-149 and a higher percentage of good-quality embryos on day 3 in conventional in vitro fertilization treatment (P < 0.0001), but no correlation was seen between miR-34c and a higher percentage of good-quality embryos (P = 0.1084). Receiver-operating characteristic curve analysis and logistic regression analysis showed that sperm-borne miR-149 with decreased expression was significantly associated with a high rate of good-quality embryos (area under the curve 0.781) (odds ratio: 0.078, 95 % confidence interval: 0.024-0.259, P < 0.0001). Our results demonstrate that the expression profile of miR-149 with significantly decreased expression could be used as a first indication of early embryonic development and may provide novel insight into the biological background of idiopathic infertile males.

Sperm-borne miR-202 targets SEPT7 and regulates first cleavage of bovine embryos via cytoskeletal remodeling

In mammals, sperm-borne regulators can be transferred to oocytes during fertilization and have different effects on the formation of pronuclei, the first cleavage of zygotes, the development of preimplantation embryos and even the metabolism of individuals after birth. The regulatory role of sperm microRNAs (miRNAs) in the development of bovine preimplantation embryos has not been reported in detail. By constructing and screening miRNA expression libraries, we found that miR-202 was highly enriched in bovine sperm. As a target gene of miR-202, co-injection of SEPT7 siRNA can partially reverse the accelerated first cleavage of bovine embryos caused by miR-202 inhibitor. In addition, both a miR-202 mimic and SEPT7 siRNA delayed the first cleavage of somatic cell nuclear transfer (SCNT) embryos, suggesting that miR-202-SEPT7 mediates the delay of first cleavage of bovine embryos. By further exploring the relationship between miR-202/SEPT7, HDAC6 and acetylated α-tubulin during embryonic development, we investigated how sperm-borne miR-202 regulates the first cleavage process of bovine embryos by SEPT7 and demonstrate the potential of sperm-borne miRNAs to improve the efficiency of SCNT.

The Role of the Epididymis and the Contribution of Epididymosomes to Mammalian Reproduction

It is well-established that testicular spermatozoa are immature and acquire motility and fertilization capabilities during transit throughout the epididymis. The epididymis is a duct-like organ that connects the testis to the vas deferens and is comprised of four anatomical regions: the initial segment, caput, corpus, and cauda. Sperm maturation occurs during epididymal transit by the interaction of sperm cells with the unique luminal environment of each epididymal region. In this review we discuss the epididymis as an essential reproductive organ responsible for sperm concentration, maturation (including sperm motility acquisition and fertilizing ability), protection and storage. Importantly, we also discuss specific characteristics and roles of epididymal-derived exosomes (epididymosomes) in establishing sperm competency within the intricate process of reproduction. This review suggests that an increasing body of evidence is working to develop a complete picture of the role of the epididymis in male reproduction, offspring health, and disease susceptibility.

Sperm-borne small RNAs regulate α-tubulin acetylation and epigenetic modification of early bovine somatic cell nuclear transfer embryos

Accumulated evidence indicates that sperm-borne small RNA plays a crucial role in embryonic development, especially the absence of the sperm-borne small RNA might be a major cause of the abnormal development of cloned embryos. In this study, we found that sperm-borne small RNA can affect abnormal pronuclear-like structures, postpone the timing of first embryo cleavage and enhance developmental competence of bovine somatic cell nuclear transfer (SCNT) embryos. In addition, the supplementation of sperm-borne small RNA can significantly increase live birth rates and decrease the birth weights of cloned offspring. To investigate the underlying mechanisms, the levels of α-tubulin K40 acetylation (Ac α-tubulin K40) and histone H3 lysine 9 trimethylation (H3K9me3) during early embryo development were investigated in SCNT embryos with sperm-borne small RNA supplementation (termed as T-NT), compared to those normal SCNT embryos and embryos obtained from standard IVF. The results showed that sperm-borne small RNA can significantly decrease the H3K9me3 levels at the pronuclear and two-cell stages, while significantly increase Ac α-tubulin K40 levels at anaphase and telophase of bovine SCNT embryos during the first cleavage. Collectively, our study for the first time demonstrates that sperm-borne small RNA plays a crucial role in the developmental competence of SCNT embryos by regulating H3K9me3 and Ac α-tubulin K40. Further studies will be required to determine how sperm small RNA regulate the H3K9me3 and Acα-tubulin K40. Our study suggests that the supplementation of sperm-borne small RNA is a potential application to improve the cloning efficiency.

MicroRNA expression profile analysis in sperm reveals hsa-mir-191 as an auspicious omen of in vitro fertilization

BACKGROUND

MicroRNAs (miRNAs) are a class of noncoding small RNAs that play important roles in many physiological processes by regulating gene expression. Previous studies have shown that the expression levels of total miRNAs increase during mouse embryonic development, and some miRNAs control the regulatory network in development progression. However, few studies have focused on the effects of miRNAs on early human embryonic development. The relationship between miRNAs and early human embryogenesis is still unknown.

RESULTS

In this study, RNA-seq data collected from sperm samples from 102 patients with a normal sperm index but treated with assisted reproductive technology (ART) were analyzed for the relationships between differentially expressed small RNAs and the fertilization rate (FR), blastocyst rate and high-quality embryo rate (HQER). The sperm samples with high hsa-mir-191 expression had a higher FR, effective embryo rate (EER) and HQER. hsa-mir-191 was used as a single indicator to predict the HQER. The receiver operating characteristic (ROC) curve had an area under the ROC curve (AUC) of 0.686. We also found that hsa-mir-191 expression is correlated with an abnormal sperm rate (cor = 0.29, p < 0.01). We also evaluated the relationship between hsa-mir-34c and early human embryo development in these 102 sperm samples and obtained negative results.

CONCLUSIONS

These findings suggest that high hsa-mir-191-5p expression in sperm is associated with early human embryonic quality and that hsa-mir-191-5p could be used as a potential marker to screen high-quality sperm to improve the success rates of in vitro fertilization (IVF).

Sperm-borne miR-449b influences cleavage, epigenetic reprogramming and apoptosis of SCNT embryos in bovine

Accumulating evidence indicates the absence of paternally derived miRNAs, piwiRNAs, and proteins may be one important factor contributing to developmental failure in somatic cell cloned embryos. In the present study, we found microRNA-449b (miR-449b) was highly expressed in sperm. Target gene predictions and experimental verification indicate that several embryonic development-related genes, including CDK6, c-MYC, HDAC1 and BCL-2, are targets of miR-449b. We therefore investigated the role of miR-449b using somatic cell nuclear transfer (SCNT) embryo model. Bovine fetal fibroblasts, expressing miR-449b through a doxycycline (dox) induced expression system were used as nuclear donor cells for SCNT. The results showed that miR-449b expression in SCNT embryos significantly enhanced the cleavage rate at 48 h after activation and the levels of H3K9 acetylation at the 2-cell to 8-cell stages, meanwhile, significantly decreased the apoptosis index of blastocysts. In addition, we verified miR-449b could regulate the expression levels of CDK6, c-MYC, HDAC1 and BCL-2. In conclusion, the present study shows that miR-449b expression improves the first cleavage division, epigenetic reprogramming and apoptotic status of bovine preimplantation cloned embryos.