A link between the interleukin-6/Stat3 anti-apoptotic pathway and microRNA-21 in preimplantation mouse embryos

Zona pellucida removal modifies the expression and release of specific microRNAs in domestic cat blastocysts

The in vitro culture of domestic cat embryos without the zona pellucida affects their implantation capacity. MicroRNAs (miRNAs) have an important role in embryo-maternal communication and implantation. The objective of this study was to evaluate the expression of specific miRNAs in domestic cat blastocysts cultured without the zona pellucida. Two experimental groups were done: (1) domestic cat embryos cultured with the zona pellucida (zona intact control group, ZI); and (2) cultured without the zona pellucida (zona free group, ZF). The cleavage, morula and blastocyst rates were evaluated. The blastocysts and their spent medium were used for miRNA expression analysis using RT-qPCR (miR-21, miR-24, mi25, miR-29, miR-96, miR-98, miR-103, miR-191, miR-196, miR-199, miR-130, miR-155 and miR-302). The pre-mature microRNAs (pre-miRNAs) and miRNAs were evaluated in the blastocysts and only miRNAs were evaluated in the spent medium. No differences were observed in the cleavage, morula and blastocyst rates between the ZF and ZI groups (P > 0.05). For miRNAs analysis, miR-103 and miR-191 had the most stable expression and were selected as internal controls. ZF blastocysts had a higher expression of miR-21, miR-25, miR-29 and miR-199 and a lower expression of miR-96 than their ZI counterparts (P < 0.05). Furthermore, higher levels of miR-21, miR-25 and miR-98 were detected in the spent medium of ZF blastocysts (P < 0.05). In conclusion, in vitro culture of domestic cat embryos without the zona pellucida modifies the expression of miR-21, miR-25, miR-29, miR-199 and miR-96 at the blastocyst stage and the release of miR-21, miR-25 and miR-98.

Follicular Fluid Growth Factors and Interleukin Profiling as Potential Predictors of IVF Outcomes

Growth hormone (GH) has gained attention as an anti-aging compound enhancing oocyte quality. In fact, GH is known to activate intrafollicular metabolic events for oocyte maturation. Insulin growth factor I (IGF1) is another ovarian growth factor that mediates the FSH and GH actions. Cytokines could also increase IVF outcomes. Indeed, IL-6 is a pleiotropic cytokine with multiple cellular effects that can vary based on the physiological environment. IL-6 may also play an important role in follicular development (Yang et al., J Assist Reprod Genet, 2020, 37 (5), 1171–1176). Clinical studies have been performed to explore the potential role of IL-6 in human oocyte maturation and subsequent embryonic development. To date, the answers are not conclusive. During peri-implantation, many cytokines balances are regulated like pro-inflammatory and anti-inflammatory interleukins. The pro-inflammatory properties of IL-17 and its impact on the tumor microenvironment or autoimmune diseases are characterized, but new dimensions of IL-17 activity that promotes embryo implantation are not well explored. In the search for answers, our study compared concentrations of growth factors IGF1, GH, and interleukins IL-6 and IL-17 in the follicular fluid (FF) from 140 women divided into two groups depending on bad (G1) or good prognosis (G2) and investigated the relationships between these FF components’ levels and the main parameters of IVF. GH, IGF1, and IL-6 were significantly higher for G2. For GH, it was negatively correlated to patient age and positively correlated to maturity rate and IGF1. Moreover, GH and IGF1 were correlated to the top embryo rate and cumulative pregnancy rate. Regarding IL-6, it was correlated to IGF1 level, endometrium thickness, and implantation rate. As for IL-17, it was only correlated to IL-6. Consequently, all these FF components were predictive of oocyte quality except IL-17. GH seemed to be the best biomarker of this quality.

Linoleic acid reduces apoptosis via NF-κB during the in vitro development of induced parthenogenic porcine embryos

Fatty acid has a various role in preimplantation embryo development. Especially, Linoleic acid, polyunsaturated fatty acid, has been reported to affect the apoptosis pathway via nuclear transcription factor-kappa B. But to date, the function of NF-κB has not been demonstrated in porcine preimplantation embryos. We demonstrated that linoleic acid had a positive effect on embryo development at a certain concentration(25 μM), but developmental failure was observed at higher concentration. Furthermore, the expression level of NF-κB increased, unlike that of IL-6, as the concentration of linoleic acid increased. Interestingly, the concentration of NF-κB was found to increase even at the concentration of linoleic acid at which embryo development decreased. We found that pro-apoptotic gene expression was downregulated in the linoleic acid-treated group. It was also found that MCL-1, an anti-apoptotic gene known to be unaffected by IL-6, was found to be increased at the mRNA level in the linoleic acid-treated group. As the concentration of NF-kB increased, the nuclear translocation of C-JUN gradually increased dependent on the linoleic acid concentration. It was confirmed that NF-κB is an important factor in porcine embryos by treated ammonium pyrrolidinedithiocarbamate (APDC 0.1 μM, an inhibitor of NF-κB) affected NF-κB protein expression, IL-6 expression, and blastocyst production. These data supported porcine embryos can use exogenous linoleic acid as a metabolic energy source via NF-κB.

Cytokines That Serve as Embryokines in Cattle

Simple Summary

This review will explore how some cytokines also influence early embryonic development. We term these types of molecules as embryokines. Understanding how cytokines serve as embryokines could offer new opportunities to improve embryo development and the overall health of the embryo so that pregnancies will be retained after embryo transfer and so that viable offspring are produced. At least two cytokines may offer these benefits to bovine embryos produced in vitro. Additional cytokines also are identified in this review that may contain beneficial activities on bovine embryos.

Abstract

The term “embryokine” has been used to denote molecules produced by the endometrium, oviduct, or by embryo itself that will influence embryo development. Several cytokines have been identified as embryokines in cattle and other mammals. This review will describe how these cytokines function as embryokines, with special emphasis being placed on their actions on in vitro produced (IVP) bovine embryos. Embryokines are being explored for their ability to overcome the poor development rates of IVP embryos and to limit post-transfer pregnancy retention efficiencies that exist in IVP embryos. This review will focus on describing two of the best-characterized cytokines, colony-stimulating factor 2 and interleukin 6, for their ability to modify bovine embryo quality and confirmation, promote normal fetal development, and generate healthy calves. Additional cytokines will also be discussed for their potential to serve as embryokines.

Effects of treatment with a microRNA mimic or inhibitor on the developmental competence, quality, epigenetic status and gene expression of buffalo (Bubalus bubalis) somatic cell nuclear transfer embryos

Expression levels of 13 microRNAs (miRNAs) were compared between buffalo blastocysts produced by somatic cell nuclear transfer through hand-made cloning and IVF to improve cloning efficiency. Expression of miR-22, miR-145, miR-374a and miR-30c was higher, whereas that of miR-29b, miR-101, miR-302b, miR-34a, miR-21 and miR-25 was lower, in nuclear transferred (NT) than IVF embryos; the expression of miR-200b, miR-26a and miR-128 was similar between the two groups. Based on these, miR-145, which is involved in the regulation of pluripotency, was selected for further investigation of NT embryos. miR-145 expression was lowest at the 2-cell stage, increased through the 4-cell stage and was highest at the 8-cell or morula stage in a pattern that was similar between NT and IVF embryos. miR-145 expression was higher in NT than IVF embryos at all stages examined. Treatment of reconstructed embryos 1h after electrofusion with an inhibitor of miR-145 for 1h decreased the apoptotic index and increased the blastocyst rate, total cell number, ratio of cells in the inner cell mass to trophectoderm, global levels of acetylation of histone 3 at lysine 18 and expression of Krueppel-like factor 4 (KLF4), octamer-binding transcription factor 4 (OCT4) and SRY (sex determining region Y)-box 2 (SOX2) in blastocysts. Treatment with an miR-145 mimic had the opposite effects. In conclusion, treatment of NT embryos with an miR-145 inhibitor improves the developmental competence and quality, and increases histone acetylation and expression of pluripotency-related genes.

The Complicated Effects of Extracellular Vesicles and Their Cargos on Embryo Implantation

As a rate-limiting step in pregnancy, embryo implantation is highly dependent on intercellular communication. Extracellular vesicles (EVs) are newly identified to be important in the course of intercellular communication. EVs have been isolated from a wide variety of biofluids and tissues, including plasma, liver, uterine, semen, embryo, etc. The present and future use of EVs not only as biomarkers, but also as targeting drug delivery system, is promisingly pave the way for advanced comprehension of implantation failure in reproductive diseases. However, as the precise mechanisms of EVs in embryo implantation has not been elucidated yet. Herein, we summarize the current knowledge on the diverse effects of EVs from various sources and their cargos such as microRNA, long non-coding RNA, protein, etc. on embryo implantation, and the potential mechanisms of EVs in reproductive diseases such as recurrent implantation failure, polycystic ovary syndrome and endometriosis. It is essential to note that many of the biologically plausible functions of EVs in embryo implantation discussed in present literatures still need further research in vivo.

Interleukin 6 in follicular fluid reduces embryo fragmentation and improves the clinical pregnancy rate

PURPOSE

The aim of this study was to evaluate the role of interleukin 6 in embryo development in the in vitro fertilization cycles.

METHODS

This was a retrospective cohort study. One hundred and three women undergoing in vitro fertilization and embryo transfer due to a tubal factor were included in the study. The follicular fluid IL-6 levels on oocyte retrieval day from each patient were determined by ELISA. The relationships between follicular fluid IL-6 levels and IVF cycle parameters were investigated.

RESULTS

The levels of follicular fluid IL-6 were not affected by the use of drugs for superovulation or by estrogen. In addition, follicular fluid IL-6 levels did not affect the number of oocytes retrieved or the MII oocyte rate. High levels of follicular fluid IL-6 correlated with a significant increase in the rates of clinical pregnancy. Follicular fluid IL-6 levels did not affect the cell number or the blastomere symmetry of day 3 embryos, but it did significantly reduce the embryo fragmentation rate.

CONCLUSIONS

High levels of follicular fluid IL-6 improved the rates of clinical pregnancy and reduce embryo fragmentation.

The Female Response to Seminal Fluid

Seminal fluid is often assumed to have just one function in mammalian reproduction, delivering sperm to fertilize oocytes. But seminal fluid also transmits signaling agents that interact with female reproductive tissues to facilitate conception and .pregnancy. Upon seminal fluid contact, female tissues initiate a controlled inflammatory response that affects several aspects of reproductive function to ultimately maximize the chances of a male producing healthy offspring. This effect is best characterized in mice, where the female response involves several steps. Initially, seminal fluid factors cause leukocytes to infiltrate the female reproductive tract, and to selectively target and eliminate excess sperm. Other signals stimulate ovulation, induce an altered transcriptional program in female tract tissues that modulates embryo developmental programming, and initiate immune adaptations to promote receptivity to implantation and placental development. A key result is expansion of the pool of regulatory T cells that assist implantation by suppressing inflammation, mediating tolerance to male transplantation antigens, and promoting uterine vascular adaptation and placental development. Principal signaling agents in seminal fluid include prostaglandins and transforming growth factor-β. The balance of male signals affects the nature of the female response, providing a mechanism of ‟cryptic female choiceˮ that influences female reproductive investment. Male-female seminal fluid signaling is evident in all mammalian species investigated including human, and effects of seminal fluid in invertebrates indicate evolutionarily conserved mechanisms. Understanding the female response to seminal fluid will shed new light on infertility and pregnancy disorders and is critical to defining how events at conception influence offspring health.

MiR-21 in extracellular vesicles contributes to the growth of fertilized eggs and embryo development in mice

Human preimplantation embryo development is susceptible to high rates of early embryo wastage. We determined the miR-21 expression of extracellular vesicles (EVs) in fertilized eggs and embryos of varying stages and their response to miR-21 microinjection. Sexually mature female and male mice were mated. Next, the expression and immunohistochemistry intensity of surface markers (CD9 and CD63) of EVs were detected in pregnant and non-pregnant mice. Exosomes were co-cultured with embryos for detection of blastocyst formation rate, and embryo apoptosis. Moreover, the expressions of Bcl-2 associated X protein (Bax), B cell lymphoma 2 (Bcl-2), and octamer-binding transcription factor-4 (Oct4) were determined. Finally, we detected miR-21 expression in EVs of uterus in pregnant mice, in embryos after embryo implantation and after embryo co-cultured with exosomes in uterine luminal fluid. MiR-21 was up-regulated in EVs of uterus, and higher immunohistochemistry intensity of CD9 and CD63, suggesting more EVs secreted in uterine luminal fluid in pregnant mice. After microinjection, miR-21 inhibitor suppresses embryo development of mice. Moreover, embryos co-cultured with exosomes display higher blastocyst formation rate, reduced apoptotic rate of embryos in pregnant mice. In addition, miR-21 was down-regulated with the development of embryos after embryo implantation, while miR-21 expression in embryos was up-regulated by exosomes in uterine luminal fluid in the pregnant mice. Increased miR-21 expression in EVs of uterus and increased miR-21 expression after implantation, which indicate the key role in the growth of fertilized eggs and embryo development in mice.

Interleukin-6 regulates expression of Fos and Jun genes to affect the development of mouse preimplantation embryos

Aim

We investigated whether recombinant mouse interleukin‐6 (IL‐6) affects the development of preimplantation embryos and induces the ‐signal transducers and activators of transcription (JAK–STAT) signaling pathway by binding IL‐6 signal transducer (IL‐6st) and regulating Fos and Jun gene expression, thereby accounting for the negative effect of superovulation on embryo development.

Methods

We compared rates of blastocyst formation from embryos cultured with different concentrations of IL‐6 or/and anti‐interleukin 6 receptor antibody (anti‐IL‐6RAb) in superovulated experimental and normal control groups. IL‐6 expression in preimplantation embryos was determined by immunofluorescence identification. Fos, Jun and IL‐6st messenger RNA expression was detected by PCR and microarray experiments.

Results

Rates of blastocyst formation significantly decreased in superovulated embryos, whether or not they were incubated in 0.1, 1, 25 or 50 pg/mL IL‐6, (P < 0.01) compared to embryos from naturally ovulated controls, whereas incubation in 5 and 10 pg/mL IL‐6 reversed the negative effects of superovulation. The addition of anti‐IL‐6RAb to naturally ovulated embryos reduced blastocyst rates to those of superovulated embryos. Gene chip analysis indicated that the JAK–STAT signaling pathway contained differentially expressed IL‐6, IL‐6st, Jun and Fos genes. Both anti‐IL‐6RAb or ovarian stimulation downregulated IL‐6st, Jun, and Fos messenger RNA expression, but expression of the same three genes increased in 5 pg/mL IL‐6.

Conclusion

Ovarian stimulation negatively impacts the development of preimplantation embryos by reducing IL‐6 release. IL‐6 affects the rate of development of zygotes to blastocyst by regulating IL‐6st, Fos and Jun expression in the JAK–STAT signaling pathway.

Different co-culture systems have the same impact on bovine embryo transcriptome

During the last few years, several co-culture systems using either BOEC or VERO feeder cells have been developed to improve bovine embryo development and these systems give better results at high oxygen concentration (20%). In parallel, the SOF medium, used at 5% O2, has been developed to mimic the oviduct fluid. Since 2010s, the SOF medium has become popular in improving bovine embryo development and authors have started to associate this medium to co-culture systems. Nevertheless, little is known about the putative benefit of this association on early development. To address this question, we have compared embryo transcriptomes in four different culture conditions: SOF with BOEC or VERO at 20% O2, and SOF without feeders at 5% or 20% O2. Embryos have been analyzed at 16-cell and blastocyst stages. Co-culture systems did not improve the developmental rate when compared to 5% O2. Direct comparison of the two co-culture systems failed to highlight major differences in embryo transcriptome at both developmental stages. Both feeder cell types appear to regulate the same cytokines and growth factors pathways, and thus to influence embryo physiology in the same way. In blastocysts, when compared to culture in SOF at 5% O2, BOEC or VERO seems to reduce cell survival and differentiation by, at least, negatively regulating STAT3 and STAT5 pathways. Collectively, in SOF medium both blastocysts rate and embryo transcriptome suggest no influence of feeder origin on bovine early development and no beneficial impact of co-culture systems when compared to 5% O2.

Addition of interleukin-6 to mouse embryo culture increases blastocyst cell number and influences the inner cell mass to trophectoderm ratio

Objective

In vitro culture of preimplantation embryos is improved by grouping embryos together in a drop of media. Individually cultured embryos are deprived of paracrine factors; with this in mind, we investigated whether the addition of a single embryo-secreted factor, interleukin-6 (IL-6), could improve the development of individually cultured embryos.

Methods

Mouse embryos were cultured individually in 2 µL of G1/G2 media in 5% oxygen and supplemented with a range of doses of recombinant mouse or human IL-6.

Results

Mouse IL-6 increased hatching at doses of 0.01 and 10 ng/mL compared to the control (93% and 93% vs. 78%, p<0.05) and increased the total number of cells at a dose of 0.1 ng/mL compared to the control (101.95±3.36 vs. 91.31±3.33, p<0.05). In contrast, the highest dose of 100 ng/mL reduced the total number of cells (79.86±3.29, p<0.05). Supplementation with human IL-6 had a different effect, with no change in hatching or total cell numbers, but an increase in the percentage of inner cell mass per embryo at doses of 0.1, 1, and 100 ng/mL compared to the control (22.9%±1.1%, 23.3%±1.1%, and 23.1%±1.1% vs. 19.5%±1.0%, p<0.05).

Conclusion

These data show that IL-6 improved mouse embryo development when cultured individually in complex media; however, an excess of IL-6 may be detrimental. Additionally, these data indicate that there is some cross-species benefit of human IL-6 for mouse embryos, but possibly through a different mechanism than for mouse IL-6.

Hypoxia-inhibited DUSP2 expression promotes IL-6/STAT3 signaling in endometriosis

PROBLEM

How does hypoxia-mediated downregulation of dual-specificity phosphatase-2 (DUSP2) promote the development of endometriotic lesions?

METHOD OF STUDY

The levels of IL-6 and DUSP2 were assessed in eutopic stromal cells with DUSP2 knockdown or hypoxia treatment. Bromodeoxyuridine (BrdU) incorporation was applied for evaluating cell proliferation. The protein levels of DUSP2, cleaved caspase-3, phosphorylated STAT3, and STAT3 were analyzed using immunoblot.

RESULTS

The genomewide analysis of cells with DUSP2 overexpression indicated IL-6 regulates multiple pathways related to inflammation, proliferation, and apoptosis. DUSP2 overexpression significantly suppressed IL-6 expression, while DUSP2 knockdown promoted IL-6 expression. The hypoxia-treated eutopic stromal cells expressed higher levels of IL-6, recapitulating the elevated levels of IL-6 in ectopic stromal cells. The treatment with IL-6 elicited the phosphorylation of STAT3, mimicking the elevated levels of phosphorylated STAT3 in the ectopic stromal cells. The IL-6-treated eutopic stromal cells showed more BrdU incorporation and less cleaved caspase-3, which can be reversed by STAT3 inhibitor.

CONCLUSION

Hypoxia-induced IL-6 production in endometriotic lesions is mediated via downregulation of DUSP2, which causes aberrant activation of STAT3 signaling pathway and helps the endometriotic cells survive under the ectopic environment.

A role for seminal plasma in modulating pregnancy outcomes in domestic species

Seminal plasma is a complex fluid produced by the accessory glands of the male reproductive tract. Seminal plasma acts primarily as a transport medium for sperm on its arduous journey through the male and then female reproductive tract following ejaculation. This spermatozoan expedition will hopefully result in the meeting of and resultant fertilization of an oocyte, perpetuating the genetic lineage of both sexes. Whereas seminal plasma has historically been perceived as only a transport medium providing a nutrient-rich fluid environment for sperm during this exchange of genetic material, new insights into a complex communication pathway between males and females has been unraveled in the past 30 years. This new research suggests seminal plasma as a method to promote early pregnancy success by modulating cellular and molecular adaptions of the maternal environment required to facilitate healthy, successful pregnancy outcomes. Whereas much work on this exciting new communication process has focused on mice and translation to human reproduction, here we review the current evidence in domestic species where artificial insemination in the absence of seminal plasma is routine. Improving artificial insemination in domestic species to optimize offspring health and productivity could have far-reaching impacts on agriculturally relevant species such as cattle, sheep, pigs and horses.

STATs: An Old Story, Yet Mesmerizing

Signal transducers and activators of transcription (STATs) are cytoplasmic transcription factors that have a key role in cell fate. STATs, a protein family comprised of seven members, are proteins which are latent cytoplasmic transcription factors that convey signals from the cell surface to the nucleus through activation by cytokines and growth factors. The signaling pathways have diverse biological functions that include roles in cell differentiation, proliferation, development, apoptosis, and inflammation which place them at the center of a very active area of research. In this review we explain Janus kinase (JAK)/STAT signaling and focus on STAT3, which is transient from cytoplasm to nucleus after phosphorylation. This procedure controls fundamental biological processes by regulating nuclear genes controlling cell proliferation, survival, and development. In some hematopoietic disorders and cancers, overexpression and activation of STAT3 result in high proliferation, suppression of cell differentiation and inhibition of cell maturation. This article focuses on STAT3 and its role in malignancy, in addition to the role of microRNAs (miRNAs) on STAT3 activation in certain cancers.

The Anti-Apoptotic Role of Berberine in Preimplantation Embryo In Vitro Development through Regulation of miRNA-21

Traditional Chinese medicinal herbs containing berberine have been historically used to prevent miscarriage. Here, we investigated whether the anti-apoptotic effects of berberine on pre-implantation embryonic development are regulated by miRNA-21. Mouse pronuclear embryos were cultured in medium with or without berberine, and some were then microinjected with a miRNA-21 inhibitor. The in vitro developmental rates of 2- and 4-cell embryos and blastocysts, blastocyst cell numbers, apoptotic rates, and apoptotic cell numbers were measured in each group. Furthermore, we examined the transcription levels of miRNA-21 and its target genes (caspase-3, PTEN, and Bcl-2) and their translation levels. Comparisons were made with in vivo-developed and untreated embryos. We found that berberine significantly increased the developmental rates and cell numbers of mouse blastocysts and decreased apoptotic cell rates in vitro. Berberine also significantly increased miRNA-21 and Bcl-2 transcription levels and significantly decreased caspase-3 and PTEN transcription levels. In embryos treated with a miRNA-21 inhibitor, the results followed the opposite trend; PTEN and caspase-3 transcription levels increased significantly, while the transcription level of Bcl-2 decreased significantly. Additionally, berberine treatment significantly increased the Bcl-2 protein level and significantly decreased the caspase-3 and PTEN protein levels in blastocysts, but there were no significant differences observed in the levels of these proteins in 2- and 4-cell embryos. This study revealed that miRNA-21 is important for pre-implantation embryonic development, especially blastocyst development in vitro. Berberine elevates miRNA-21 expression, decreases PTEN and caspase-3 levels, increases Bcl-2 levels, and exerts anti-apoptotic and pro-growth effects.

Female tract cytokines and developmental programming in embryos

In the physiological situation, cytokines are pivotal mediators of communication between the maternal tract and the embryo. Compelling evidence shows that cytokines emanating from the oviduct and uterus confer a sophisticated mechanism for 'fine-tuning' of embryo development, influencing a range of cellular events from cell survival and metabolism, through division and differentiation, and potentially exerting long-term impact through epigenetic remodelling. The balance between survival agents, including GM-CSF, CSF1, LIF, HB-EGF and IGFII, against apoptosis-inducing factors such as TNFα, TRAIL and IFNg, influence the course of preimplantation development, causing embryos to develop normally, adapt to varying maternal environments, or in some cases to arrest and undergo demise. Maternal cytokine-mediated pathways help mediate the biological effects of embryo programming, embryo plasticity and adaptation, and maternal tract quality control. Thus maternal cytokines exert influence not only on fertility and pregnancy progression but on the developmental trajectory and health of offspring. Defining a clear understanding of the biology of cytokine networks influencing the embryo is essential to support optimal outcomes in natural and assisted conception.

MicroRNAs: New Players in Anesthetic-Induced Developmental Neurotoxicity

Growing evidence demonstrates that prolonged exposure to general anesthetics during brain development induces widespread neuronal cell death followed by long-term memory and learning disabilities in animal models. These studies have raised serious concerns about the safety of anesthetic use in pregnant women and young children. However, the underlying mechanisms of anesthetic-induced neurotoxicity are complex and are not well understood. MicroRNAs are endogenous, small, non-coding RNAs that have been implicated to play important roles in many different disease processes by negatively regulating target gene expression. A possible role for microRNAs in anesthetic-induced developmental neurotoxicity has recently been identified, suggesting that microRNA-based signaling might be a novel target for preventing the neurotoxicity. Here we provide an overview of anesthetic-induced developmental neurotoxicity and focus on the role of microRNAs in the neurotoxicity observed in both human stem cell-derived neuron and animal models. Aberrant expression of some microRNAs has been shown to be involved in anesthetic-induced developmental neurotoxicity, revealing the potential of microRNAs as therapeutic or preventive targets against the toxicity.

Seminal Fluid Signalling in the Female Reproductive Tract: Implications for Reproductive Success and Offspring Health

Carriage of sperm is not the only function of seminal fluid in mammals. Studies in mice show that at conception, seminal fluid interacts with the female reproductive tract to induce responses which influence whether or not pregnancy will occur, and to set in train effects that help shape subsequent fetal development. In particular, seminal fluid initiates female immune adaptation processes required to tolerate male transplantation antigens present in seminal fluid and inherited by the conceptus. A tolerogenic immune environment to facilitate pregnancy depends on regulatory T cells (Treg cells), which recognise male antigens and function to suppress inflammation and immune rejection responses. The female response to seminal fluid stimulates the generation of Treg cells that protect the conceptus from inflammatory damage, to support implantation and placental development. Seminal fluid also elicits molecular and cellular changes in the oviduct and endometrium that directly promote embryo development and implantation competence. The plasma fraction of seminal fluid plays a key role in this process with soluble factors, including TGFB, prostaglandin-E, and TLR4 ligands, demonstrated to contribute to the peri-conception immune environment. Recent studies show that conception in the absence of seminal plasma in mice impairs embryo development and alters fetal development to impact the phenotype of offspring, with adverse effects on adult metabolic function particularly in males. This review summarises our current understanding of the molecular responses to seminal fluid and how this contributes to the establishment of pregnancy, generation of an immune-regulatory environment and programming long-term offspring health.

Down-regulation of microRNA-21 is involved in the propofol-induced neurotoxicity observed in human stem cell-derived neurons

BACKGROUND

Recent studies in various animal models have suggested that anesthetics such as propofol, when administered early in life, can lead to neurotoxicity. These studies have raised significant safety concerns regarding the use of anesthetics in the pediatric population and highlight the need for a better model to study anesthetic-induced neurotoxicity in humans. Human embryonic stem cells are capable of differentiating into any cell type and represent a promising model to study mechanisms governing anesthetic-induced neurotoxicity.

METHODS

Cell death in human embryonic stem cell-derived neurons was assessed using terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate in situ nick end labeling staining, and microRNA expression was assessed using quantitative reverse transcription polymerase chain reaction. miR-21 was overexpressed and knocked down using an miR-21 mimic and antagomir, respectively. Sprouty 2 was knocked down using a small interfering RNA, and the expression of the miR-21 targets of interest was assessed by Western blot.

RESULTS

Propofol dose and exposure time dependently induced significant cell death (n = 3) in the neurons and down-regulated several microRNAs, including miR-21. Overexpression of miR-21 and knockdown of Sprouty 2 attenuated the increase in terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate in situ nick end labeling-positive cells following propofol exposure. In addition, miR-21 knockdown increased the number of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate in situ nick end labeling-positive cells by 30% (n = 5). Finally, activated signal transducer and activator of transcription 3 and protein kinase B (Akt) were down-regulated, and Sprouty 2 was up-regulated following propofol exposure (n = 3).

CONCLUSIONS

These data suggest that (1) human embryonic stem cell-derived neurons represent a promising in vitro human model for studying anesthetic-induced neurotoxicity, (2) propofol induces cell death in human embryonic stem cell-derived neurons, and (3) the propofol-induced cell death may occur via a signal transducer and activator of transcription 3/miR-21/Sprouty 2-dependent mechanism.

Identification of sites of STAT3 action in the female reproductive tract through conditional gene deletion

The STAT3 transcription factor is a pleiotropic transducer of signalling by hormones, growth factors and cytokines that has been identified in the female reproductive tract from oocytes and granulosa cells of the ovary to uterine epithelial and stromal cells. In the present study we used transgenic models to investigate the importance of STAT3 for reproductive performance in these different tissues. The Cre-LoxP system was used to delete STAT3 in oocytes by crossing Stat3fl/fl with Zp3-cre+ mice, or in ovarian granulosa cells and uterine stroma by crossing with Amhr2-Cre+ mice. Surprisingly, deletion of STAT3 in oocytes had no effect on fertility indicating that the abundance of STAT3 protein in maturing oocytes and fertilized zygotes is not essential to these developmental stages. In Stat3fl/fl;Amhr2-cre+ females impaired fertility was observed through significantly fewer litters and smaller litter size. Ovulation rate, oocyte fertilization and development to blastocyst were unaffected in this line; however, poor recombination efficiency in granulosa cells had yielded no net change in STAT3 protein abundance. In contrast, uteri from these mice showed STAT3 protein depletion selectively from the stomal compartment. A significant reduction in number of viable fetuses on gestational day 18, increased fetal resorptions and disrupted placental morphology were evident causes of the reduced fertility. In conclusion, this study defines an important role for STAT3 in uterine stromal cells during embryo implantation and the development of a functional placenta.

MiR-21 is under control of STAT5 but is dispensable for mammary development and lactation

Development of mammary alveolar epithelium during pregnancy is controlled by prolactin, through the transcription factors STAT5A/B that activate specific sets of target genes. Here we asked whether some of STAT5's functions are mediated by microRNAs. The miR-21 promoter sequence contains a bona-fide STAT5 binding site and miR-21 levels increased in HC11 mammary cells upon prolactin treatment. In vivo miR-21 was abundantly expressed in mammary epithelium at day 6 of pregnancy. Analysis of mice lacking miR-21 revealed that their mammary tissue developed normally during pregnancy and dams were able to nurse their pups. Our study demonstrated that although expression of miR-21 is under prolactin control through the transcription factors STAT5A/B its presence is dispensable for mammary development and lactation.

Maternal tract factors contribute to paternal seminal fluid impact on metabolic phenotype in offspring

Paternal characteristics and exposures influence physiology and disease risks in progeny, but the mechanisms are mostly unknown. Seminal fluid, which affects female reproductive tract gene expression as well as sperm survival and integrity, provides one potential pathway. We evaluated in mice the consequences for offspring of ablating the plasma fraction of seminal fluid by surgical excision of the seminal vesicle gland. Conception was substantially impaired and, when pregnancy did occur, placental hypertrophy was evident in late gestation. After birth, the growth trajectory and metabolic parameters of progeny were altered, most profoundly in males, which exhibited obesity, distorted metabolic hormones, reduced glucose tolerance, and hypertension. Altered offspring phenotype was partly attributable to sperm damage and partly to an effect of seminal fluid deficiency on the female tract, because increased adiposity was also evident in adult male progeny when normal two-cell embryos were transferred to females mated with seminal vesicle-excised males. Moreover, embryos developed in female tracts not exposed to seminal plasma were abnormal from the early cleavage stages, but culture in vitro partly alleviated this. Absence of seminal plasma was accompanied by down-regulation of the embryotrophic factors Lif, Csf2, Il6, and Egf and up-regulation of the apoptosis-inducing factor Trail in the oviduct. These findings show that paternal seminal fluid composition affects the growth and health of male offspring, and reveal that its impact on the periconception environment involves not only sperm protection but also indirect effects on preimplantation embryos via oviduct expression of embryotrophic cytokines.

MicroRNA-21 is induced by rapamycin in a model of tuberous sclerosis (TSC) and lymphangioleiomyomatosis (LAM)

Lymphangioleiomyomatosis (LAM), a multisystem disease of women, is manifest by the proliferation of smooth muscle-like cells in the lung resulting in cystic lung destruction. Women with LAM can also develop renal angiomyolipomas. LAM is caused by mutations in the tuberous sclerosis complex genes (TSC1 or TSC2), resulting in hyperactive mammalian Target of Rapamycin (mTOR) signaling. The mTOR inhibitor, Rapamycin, stabilizes lung function in LAM and decreases the volume of renal angiomyolipomas, but lung function declines and angiomyolipomas regrow when treatment is discontinued, suggesting that factors induced by mTORC1 inhibition may promote the survival of TSC2-deficient cells. Whether microRNA (miRNA, miR) signaling is involved in the response of LAM to mTORC1 inhibition is unknown. We identified Rapamycin-dependent miRNA in LAM patient angiomyolipoma-derived cells using two separate screens. First, we assayed 132 miRNA of known significance to tumor biology. Using a cut-off of >1.5-fold change, 48 microRNA were Rapamycin-induced, while 4 miRs were downregulated. In a second screen encompassing 946 miRNA, 18 miRs were upregulated by Rapamycin, while eight were downregulated. Dysregulation of miRs 29b, 21, 24, 221, 106a and 199a were common to both platforms and were classified as candidate “RapamiRs.” Validation by qRT-PCR confirmed that these microRNA were increased. miR-21, a pro-survival miR, was the most significantly increased by mTOR-inhibition (p<0.01). The regulation of miR-21 by Rapamycin is cell type independent. mTOR inhibition promotes the processing of the miR-21 transcript (pri-miR-21) to a premature form (pre-miR-21). In conclusion, our findings demonstrate that Rapamycin upregulates multiple miRs, including pro-survival miRs, in TSC2-deficient patient-derived cells. The induction of miRs may contribute to the response of LAM and TSC patients to Rapamycin therapy.

Interleukin-6 in pregnancy and gestational disorders

IL6 is a multifunctional cytokine with pivotal roles in the inflammatory response and in directing T cell differentiation in adaptive immunity. IL6 is widely expressed in the female reproductive tract and gestational tissues, and exerts regulatory functions in embryo implantation and placental development, as well as the immune adaptations required to tolerate pregnancy. Here, we summarise the current understanding of how membrane-bound and soluble receptors mediate IL6 signalling to regulate leukocytes and non-haemopoietic cells. We review the published literature regarding the expression and actions of IL6 in the uterus, decidua and placenta, and studies implicating this cytokine in pregnancy disorders. Elevated IL6 is frequently evident in the altered cytokine profiles characteristic of unexplained infertility, recurrent miscarriage, preeclampsia and preterm delivery. Notably, there is compelling evidence indicating altered systemic IL6 trans-signalling in women prone to recurrent miscarriage, with excessive IL6 bioavailability potentially inhibiting generation of CD4+ T regulatory cells required for pregnancy tolerance. Insufficient local IL6 may also contribute to fetal loss, since IL6 expression is reduced in the endometrium of women with recurrent miscarriage, and in the fetal-placental tissue of CBA×DBA/2 mice. Consistent with the role of IL6 in key reproductive events, Il6 null mutant mice exhibit elevated fetal resorption and delayed parturition. Investigation of the association between IL6 signalling components and T cell responses in pregnant women, as well as detailed analysis of the maternal immune response in IL6-deficient mice, is now required to define the mechanisms by which this cytokine exerts influence on reproductive success.

Ovarian stimulation reduces IL-6 release from mouse and human pre-implantation embryos

PROBLEM

In our previous study, ovarian stimulation retarded post-implantation development and caused 92 genes, including interleukin-6 (IL-6), to be differentially expressed in mouse blastocysts. None of them had been tested at protein level, In this study, we confirm the level change of IL-6 mRNA in mouse blastocysts and IL-6 protein release to the culture medium from mouse and human pre-implantation embryos.

METHOD OF STUDY

IL-6 mRNA were measured by PCR and IL-6 release to the culture medium were measured by ELISA.

RESULTS

Superovulation caused a 1.95-fold reduction in IL-6 mRNA in mouse blastocysts and reduced IL-6 secretion into the culture medium in mouse zygotes which were developed to the blastocyst stage (6.397 ± 0.635 versus 4.799 ± 0.312 pg/mL). Ovarian stimulation also significantly reduced IL-6 release into the culture medium in human zygotes which were cultured for 2 days (4.713 ± 0.945 versus 4.543 ± 0.796 pg/mL).

CONCLUSION

Our findings indicate that IL-6 might serve as a candidate marker for evaluating embryo developmental competence.

Interleukin-6 enhances porcine parthenote development in vitro, through the IL-6/Stat3 signaling pathway

Signal transducer and activator of transcription-3 (Stat3) plays a central role in interleukin-6 (IL-6)-mediated cell proliferation by inhibiting apoptosis in a variety of cell types. The Stat3 pathway is essential for embryonic development. The aim of this study was to determine the effects of recombinant IL-6 on the viability and development of porcine diploid parthenotes cultured in vitro. Four-cell parthenotes, derived in vitro, were cultured to the blastocyst stage, with or without recombinant IL-6. The addition of 10 or 100 ng/ml of recombinant swine IL-6 into PZM3 medium increased the development rate of parthenotes to the blastocyst stage (P<0.05). When supplemented with 10 ng/ml of recombinant swine IL-6, the number of parthenotes at the blastocyst stage increased (P<0.05) and apoptosis decreased (P<0.05). Real-time RT-PCR experiments revealed that the addition of recombinant swine IL-6 decreased the mRNA expression of the pro-apoptotic gene Caspase3 (P<0.01) but increased the expression levels of the anti-apoptotic genes Bcl2l1 and Survivin. IL-6 receptors and Stat3 mRNA expression were upregulated after treatment with 10 ng/ml recombinant swine IL-6. Immunoblots and fluorescence labeling experiments showed that the levels of phosphorylated Stat3 were upregulated. These results suggest that recombinant swine IL-6 prevents apoptosis of porcine parthenotes and enhances porcine embryo viability through the IL-6/Stat3 signaling pathway in vitro.

Epigenetic regulation of cell life and death decisions and deregulation in cancer

For every cell, there is a time to live and a time to die. It is apparent that cell life and death decisions are taken by individual cells based on their interpretation of physiological or non-physiological stimuli, or their own self-assessment of internal damage or changes in their environment. Apoptosis or programmed cell death is a key regulator of physiological growth control and regulation of tissue homoeostasis. One of the most important advances in cancer research in recent years is the recognition that cell death, mostly by apoptosis, is crucially involved in the regulation of tumour formation and also critically determines treatment response. The initiation and progression of cancer, traditionally seen as a genetic disease, is now realized to involve epigenetic abnormalities along with genetic alterations. The study of epigenetic mechanisms in cancer, such as DNA methylation, histone modifications and microRNA expression, has revealed a plethora of events that contribute to the neoplastic phenotype through stable changes in the expression of genes critical to cell death pathways. A better understanding of the epigenetic molecular events that regulate apoptosis, together with the reversible nature of epigenetic aberrations, should contribute to the emergence of the promising field of epigenetic therapy.

MicroRNA and aging: a novel modulator in regulating the aging network

miRNAs are a group of noncoding small RNA that are capable of modulating the expression of hundreds of genes via a near-perfect or partial complementary to target mRNA. The ability to regulate multiple targets simultaneously makes miRNA a crucial regulator in many physiological conditions, especially in the aging network and process. The tremendous capability of miRNA supports its ability in regulating ageing, which is a complex process involving multiple interconnected signaling pathways. Even though the relationship between miRNA and ageing is not fully understood, studies have provided evidence showing that miRNAs participate in regulating cell cycle progression, proliferation, stemness gene expression, and stress-induced responses. Molecular studies of ageing and miRNAs would provide a more comprehensive understanding of the mechanisms of ageing and, subsequently, help to ameliorate this universal process compromising our quality of life. In this review article, we focus our attention on miRNA targets in conserved pathways involved in organism aging and aging networks, as well as cellular senescence.

MicroRNA-21 is a key determinant in IL-11/Stat3 anti-apoptotic signalling pathway in preconditioning of skeletal myoblasts

AIMS

We have previously shown that preconditioning of stem and progenitor cells promotes their survival post-engraftment in the infarcted heart. The present study was designed to (i) delineate the role of microRNA-21 (miR-21) in interleukin-11 (IL-11) signalling during preconditioning of skeletal myoblasts (MY) and (ii) study the long-term fate of preconditioned MY ((PC)MY) post-transplantation in the infarcted heart.

METHODS AND RESULTS

We report that pharmacological preconditioning of MY with diazoxide showed robust expression of IL-11 and activation of extracellular signal-regulated kinase 1/2 (Erk1/2) and signal transducers and activators of transcription-3 (Stat3) with concomitantly increased miR-21. These molecular events improved cytoprotection of (PC)MY under oxidant stress in vitro which was compromised by pre-treatment of (PC)MY with IL-11-specific siRNA, Erk1/2 blocker, or anti-miR-21. In vivo studies for sry-gene detection in a female rat heart model of acute myocardial infarction showed two-fold higher survival of male donor (PC)MY 4 and 7 days post-engraftment. Long-term fate of the engrafted cells was determined at 4 months after transplantation. Immunohistological studies revealed that in comparison with (non-PC)MY, (PC)MY improved angiogenic response in the heart which was evident from a higher number of blood vessels per surface area (0.155 mm(2)) and myogenic differentiation of (PC)MY in the heart. Indices of myocardial contractility including ejection fraction and fractional shortening showed significant improvement in (PC)MY-treated animals.

CONCLUSION

miR-21 is a key regulator of Erk1/2-Stat3 signalling downstream of IL-11 during preconditioning of MY. The therapeutic benefits of (PC)MY were stable and persisted until 4 months of observation.

Gemcitabine sensitivity can be induced in pancreatic cancer cells through modulation of miR-200 and miR-21 expression by curcumin or its analogue CDF

Curcumin induces cancer cell growth arrest and apoptosis in vitro, but its poor bioavailability in vivo limits its antitumor efficacy. We have previously evaluated the bioavailability of novel analogues of curcumin compared with curcumin, and we found that the analogue CDF exhibited greater systemic and pancreatic tissue bioavailability. In this study, we evaluated the effects of CDF or curcumin alone or in combination with gemcitabine on cell viability and apoptosis in gemcitabine-sensitive and gemcitabine-resistant pancreatic cancer (PC) cell lines. Mechanistic investigations revealed a significant reduction in cell viability in CDF-treated cells compared with curcumin-treated cells, which were also associated with the induction of apoptosis, and these results were consistent with the downregulation of Akt, cyclooxygenase-2, prostaglandin E(2), vascular endothelial growth factor, and NF-kappaB DNA binding activity. We have also documented attenuated expression of miR-200 and increased expression of miR-21 (a signature of tumor aggressiveness) in gemcitabine-resistant cells relative to gemcitabine-sensitive cells. Interestingly, CDF treatment upregulated miR-200 expression and downregulated the expression of miR-21, and the downregulation of miR-21 resulted in the induction of PTEN. These results prompt further interest in CDF as a drug modality to improve treatment outcome of patients diagnosed with PC as a result of its greater bioavailability in pancreatic tissue.

Identification of microRNAs controlling human ovarian cell proliferation and apoptosis

Previous studies have shown that microRNAs (miRNAs) can control steroidogenesis in cultured granulosa cells. In this study we wanted to determine if miRNAs can also affect proliferation and apoptosis in human ovarian cells. The effect of transfection of cultured primary ovarian granulosa cells with 80 different constructs encoding human pre-miRNAs on the expression of the proliferation marker, PCNA, and the apoptosis marker, Bax was evaluated by immunocytochemistry. Eleven out of 80 tested miRNA constructs resulted in stimulation, and 53 miRNAs inhibited expression of PCNA. Furthermore, 11 of the 80 miRNAs tested promoted accumulation of Bax, while 46 miRNAs caused a reduction in Bax in human ovarian cells. In addition, two selected antisense constructs that block the corresponding miRNAs mir-15a and mir-188 were evaluated for their effects on expression of PCNA. An antisense construct inhibiting mir-15a (which precursor suppressed PCNA) increased PCNA, whereas an antisense construct for mir-188 (which precursor did not change PCNA) did not affect PCNA expression. Verification of effects of selected pre-mir-10a, mir-105, and mir-182 by using other markers of proliferation (cyclin B1) and apoptosis (TdT and caspase 3) confirmed specificity of miRNAs effects on these processes. This is the first direct demonstration of the involvement of miRNAs in controlling both proliferation and apoptosis by ovarian granulose cells, as well as the identification of miRNAs promoting and suppressing these processes utilizing a genome-wide miRNA screen.