Regulatory microRNA network identification in bovine blastocyst development

Paraspeckles / CARM1 mediates the regulation of OEVs on cell differentiation during in vitro embryonic development of yak

Mammalian embryos produced in vitro have poor embryo quality and low developmental ability compared with in vivo embryos. The main manifestations are the low number of blastocysts, the low ratio of the number of inner cell mass cells to the number of trophoblastic cells, and the high apoptosis rate of blastocysts, resulting in low embryo implantation rate. Therefore, optimizing in vitro culture conditions has become a key technology to im-prove the quality of preimplantation embryos. Oviduct Epithelial cells exosomes (OEVs) can be absorbed and internalized by embryos to improve the blastocyst rate and blastocyst quality of embryos in vitro. As a special nuclear structure, Paraspeckles are involved in the fate determination of mammalian early embryonic mammalian cells. However, the regulation of embryonic cell differentiation by OEVs remains unknown. We aimed to investigate the effects of OEVs on paraspeckle formation and cell fate determination in yak in vitro fertilization (IVF) of em-bryos. To simulate the in vivo oviduct environment after ovulation, we used follicular fluid exosomes (FEVs) to stimulate yak oviduct epithelial cells and collect OEVs. OEVs were added to the yak IVF embryo culture system. Paraspeckle formation, cell differentiation, and blastocyst quality in yak embryos were determined. Our results show that, development of yak embryos is unique compared to other bovine species, and OEVs can be used as a supplement to the in vitro culture system of yak embryos to improve embryonic development and blas-tocyst quality. And also Paraspeckles/CARM1 mediated the regulation of OEVs on cell differentiation during in vitro yak embryo production. These results provide new insights into the study of yak embryonic development and the role of OEVs in embryonic development.

Sperm fertilizing ability in vitro influences bovine blastocyst miRNA content

MicroRNAs (miRNAs) are small highly conserved non-coding RNA molecules that orchestrate a wide range of biological processes through post-transcriptional regulation of gene expression. During development, miRNAs play a key role in driving embryo patterning and morphogenesis in a specific and stage-dependent manner. Here, we investigated whether sperm from bulls with different fertilizing ability in vitro influence blastocyst quality and miRNA content. Results demonstrate that blastocysts obtained using sperm from high fertility sires (H group) display significantly greater cleavage and blastocyst development as well as greater transcript abundance in blastocysts for the developmental competence markers CDX2, KRT8, NANOG, OCT4, PLAC8, PTGS2, SOX17, and SOX2, compared to blastocysts generated using sperm from low fertility sires (L group). In parallel, high throughput deep sequencing and differential expression studies revealed that H blastocysts exhibit a greater miRNA content compared to L blastocysts, with hsa-miR-4755-5p and hsa-miR-548d-3p uniquely detected in the H group, and greater abundance of hsa-miR-1225-3p in the H group. Gene ontology (GO) and KEGG pathway analyses indicated that the 3 differentially expressed miRNAs identified are involved in the regulation of many biological mechanisms with a key role in aspects of early embryo development, including transcriptional regulation, cellular biosynthesis, nucleic acid metabolism, cellular differentiation, apoptosis, cytoskeleton remodeling, cell-to-cell interactions, and endocytosis. Overall, our results indicate that sperm fertilizing ability influences blastocyst developmental ability and miRNA content. In addition, we demonstrate an association between blastocyst quality and miRNA content, thus suggesting the possibility to score miRNA expression as biomarkers for improved routine embryo selection technologies to support assisted reproductive efforts.

Selection and application of small non-coding RNAs for normalizing RT-qPCR data of bovine preimplantation embryo conditioned medium

Small non-coding RNAs (sncRNAs) present in the conditioned medium (CM) of bovine preimplantation embryos are potential noninvasive biomarkers for assessing embryo quality. Accurate quantification of sncRNA levels in the spent CM is of utmost importance in this regard. RT-qPCR is considered as the gold standard for quantifying RNA. In order to standardize RT-qPCR data in the sample type under investigation, the use of suitable stable sncRNAs is essential. Here, we selected 10 sncRNAs from small RNA sequencing of CM samples derived from both bovine blastocysts and degenerate embryos, and evaluated their expression stability together with that of cel-miR-39 as a spike and the often-used U6 small nuclear RNA at different embryo developmental stages. In CM of 2-cell embryos, rsRNA-1044 showed the most stable expression, while tDR-1:32-Gly-CCC-1 was the most stable expressed sncRNA in CM of the stages beyond the 2-cell stage. Next, tDR-1:32-Gly-CCC-1 was used for normalizing the RT-qPCR data from the CM of blastocysts and degenerate embryos. Bta-miR-155 and tDR-39:75-Arg-CCG-2 were found to be significantly up-regulated in the CM of blastocysts compared to that of the degenerated embryos (P = 0.028 and P = 0.017, respectively), suggesting their expression levels are related to embryo development stage. In conclusion, tDR-1:32-Gly-CCC-1 can serve as a suitable reference sncRNA for normalization of RT-qPCR data of the CM from bovine blastocysts.

In vitro developmental competence of bovine demi-embryos generated by blastomere separation and blastocyst bisection

The efficiency of bovine in vitro embryo production can be significantly improved by splitting embryos at different stages. However, the blastocyst quality of in vitro-produced demi-embryos remains unexplored. The objective of this research was to compare embryo developmental rates and quality of bovine demi-embryos produced by two different strategies: (a) embryo bisection (BSEC) and (b) 2-cell blastomere separation (BSEP). To determine demi-embryos quality, we evaluated total blastocyst cell number and proportion of SOX2+ cells. Additionally, the expression of SOX2, NANOG, OCT4, CDX2, IFNT, BAX and BCL genes and let-7a and miRNA-30c Micro RNAs was analysed. BSEP resulted in improved blastocyst development, higher ICM cells and a significantly higher expression of IFNΤ than demi-embryos produced by BSEC. Let-7a, which is associated with low pregnancy establishment was detected in BSEC, while miRNA-30c expression was observed in all treatments. In conclusion, BSEP of 2-cell embryos is more efficient to improve in vitro bovine embryo development and to produce good quality demi-embryos based on ICM cell number and the expression pattern of the genes explored compared to BSEC.

Characterization of agouti-signaling protein (ASIP) in the bovine ovary and throughout early embryogenesis

The oocyte expresses certain genes during folliculogenesis to regulate the acquisition of oocyte competence. Oocyte competence, or oocyte quality, is directly related to the ability of the oocyte to result in a successful pregnancy following fertilization. Presently, approximately 40 % of bovine embryos will develop to the blastocyst stage in vitro. Characterization of factors regulating these processes is crucial to improve the efficiency of bovine in vitro embryo production. We demonstrated that the secreted protein, agouti-signaling protein (ASIP) is highly abundant in the bovine oocyte and aimed to characterize its spatiotemporal expression profile in the ovary and throughout early embryonic development. In addition to oocyte expression, ASIP was detected in granulosa, cumulus, and theca cells isolated from antral follicles. Both gene expression data and immunofluorescent staining indicated ASIP declines with oocyte maturation which may indicate a potential role for ASIP in the attainment of oocyte competence. Microinjection of zygotes using small interfering RNA targeting ASIP led to a 16 % reduction in the rate of development to the blastocyst stage. Additionally, we examined potential ASIP signaling mechanisms through which ASIP may function to establish oocyte developmental competence. The expression of melanocortin receptor 3 and 4 and the coreceptor attractin was detected in the oocyte and follicular cells. The addition of cortisol during in vitro maturation was found to increase significantly oocyte ASIP levels. In conclusion, these results suggest a functional role for ASIP in promoting oocyte maturation and subsequent embryonic development, potentially through signaling mechanisms involving cortisol.

Sexual dimorphic miRNA-mediated response of bovine elongated embryos to the maternal microenvironment

A skewed male-to-female ratio in cattle is believed to be due to the biased embryo losses during pregnancy. The changes in biochemical secretion such as miRNAs by the embryo due to altered maternal environment could cause a sex biased selective implantation resulting in a skewed male to female ratio at birth. Nevertheless, it is still not clear whether the male and female embryos could modify their miRNA expression patterns differently in response to altered physiological developmental conditions. Therefore, this study was focused on identifying sex specific miRNA expression patterns induced in the embryo during the elongation period in response to the maternal environment. For this, in vitro produced day female and male embryos were transferred to Holsteins Frisian cows and heifers. The elongated female and male embryos were then recovered at day 13 of the gestation period. Total RNA including the miRNAs was isolated from each group of elongated embryo samples were subjected to the next generation miRNA sequencing. Sequence alignment, identification and quantification of miRNAs were done using the miRDeep2 software package and differential miRNA expression analyses were performed using the edgeR bioconductor package. The recovery rate of viable elongating embryos at day 13 of the gestation period was 26.6%. In cows, 2.8 more viable elongating male embryos were recovered than female embryos, while in heifers the sex ratio of the recovered elongating embryos was close to one (1.05). The miRNA analysis showed that 254 miRNAs were detected in both male and female elongated embryos developed either in cows or heifers, of which 14 miRNAs including bta-miR-10b, bta-miR-148a, bta-miR-26a, and bta-miR-30d were highly expressed. Moreover, the expression level of 32 miRNAs including bta-let-7c, bta-let-7b, bta-let-7g, bta-let-7d and bta-let-7e was significantly different between the male and female embryos developed in cows, but the expression level of only 4 miRNAs (bta-miR-10, bta-mR-100, bta-miR-155 and bta-miR-6119-5p) was different between the male and female embryos that were developed in heifers. Furthermore, 19 miRNAs including those involved in cellular energy homeostasis pathways were differentially expressed between the male embryos developed in cows and heifers, but no significantly differentially expressed miRNAs were detected between the female embryos of cows and heifers. Thus, this study revealed that the sex ratio skewed towards males in embryos developed in cows was accompanied by increased embryonic sexual dimorphic miRNA expression divergence in embryos developed in cows compared to those developed in heifers. Moreover, male embryos are more sensitive to respond to the maternal reproductive microenvironment by modulating their miRNA expression.

MiR-145 is upregulated in the retarded preimplantation embryos and modulates cholesterol levels in mice preimplantation embryos through targeting Abca1

BACKGROUND

Preimplantation embryonic lethality is a driver of female infertility. Certain microRNAs (miRNAs) have previously been demonstrated to play important roles in the regulation of embryogenesis.

METHODS

Normally developing blastocysts and arrested embryos were collected from patients undergoing intracytoplasmic sperm injection (ICSI), and the expression of specific miRNAs therein was evaluated by qPCR. The overexpression of target molecule miR-145 in early mice embryos was achieved via oocyte microinjection, enabling the subsequent monitoring of how such overexpression impacted embryonic development. Bioinformatics approaches were utilized to identify putative miR-145 target mRNAs, and luciferase reporter assessments were implemented to confirm the ability of miR-145 to regulate Abca1 in HEK293T cells. The functional relationship between miR-145 and Abca1 in the mice's embryonic development was then confirmed through rescue assays.

RESULTS

Abnormally increased miR-145 expression was observed in patients' arrested embryos, and the exogenous overexpression of this miRNA significantly suppressed mural blastocyst formation. Mechanistically, miR-145 was found to bind to the 3'-untranslated area of the Abca1 mRNA in HK293T cells, thus suppressing its expression and increasing embryonic cholesterol levels. In line with the importance of these cholesterol levels to embryogenesis, the upregulation of Abca1 was sufficient to rescue the observed change in cholesterol levels and the associated retardation of mice embryonic development that occurred in response to the overexpression of miR-145.

CONCLUSION

The regulatory dynamics of the miR-145/Abca1 axis play an important role in shaping normal embryonic development.

Embryonic microRNAs are essential for bovine preimplantation embryo development

MicroRNAs (miRNAs) are small, noncoding RNAs that regulate gene expression after transcription. miRNAs are present in transcriptionally quiescent full-grown oocytes and preimplantation embryos that display a low level of transcription prior to embryonic genome activation. The role of miRNAs, if any, in preimplantation development is not known. The temporal pattern of expression of miRNAs during bovine preimplantation development was determined by small RNA-sequencing using eggs and preimplantation embryos (1-cell, 2-cell, 4-cell, 8-cell, 16-cell, morula, and blastocyst). Embryos cultured in the presence of α-amanitin, which permitted the distinguishing of maternal miRNAs from embryonic miRNAs, indicated that embryonic miRNA expression was first detected at the two-cell stage but dramatically increased during the morula and blastocyst stages. Targeting DGCR8 by a small-interfering RNA/morpholino approach revealed a role for miRNAs in the morula-to-blastocyst transition. Knockdown of DGCR8 not only inhibited expression of embryonically expressed miRNAs but also inhibited the morula-to-blastocyst transition. In addition, RNA-sequencing identified an increased relative abundance of messenger RNAs potentially targeted by embryonic miRNAs in DGCR8-knockdown embryos when compared with controls. Results from these experiments implicate an essential role for miRNAs in bovine preimplantation embryo development.

The non-coding genome in early human development - Recent advancements

Not that long ago, the human genome was discovered to be mainly non-coding, that is comprised of DNA sequences that do not code for proteins. The initial paradigm that non-coding is also non-functional was soon overturned and today the work to uncover the functions of non-coding DNA and RNA in human early embryogenesis has commenced. Early human development is characterized by large-scale changes in genomic activity and the transcriptome that are partly driven by the coordinated activation and repression of repetitive DNA elements scattered across the genome. Here we provide examples of recent novel discoveries of non-coding DNA and RNA interactions and mechanisms that ensure accurate non-coding activity during human maternal-to-zygotic transition and lineage segregation. These include studies on small and long non-coding RNAs, transposable element regulation, and RNA tailing in human oocytes and early embryos. High-throughput approaches to dissect the non-coding regulatory networks governing early human development are a foundation for functional studies of specific genomic elements and molecules that has only begun and will provide a wider understanding of early human embryogenesis and causes of infertility.

Next-generation sequencing analysis reveals segmental patterns of microRNA expression in yak epididymis

MicroRNAs (miRNAs) have emerged as potent regulators of gene expression and are widely expressed in biological systems. In reproduction, they have been shown to have a significant role in the acquisition and maintenance of male fertility, whereby deletion of Dicer in mouse germ cells leads to infertility. Evidence indicates that this role of miRNAs extends from the testis into the epididymis, controlling gene expression and contributing to regional variations in gene expression. In this study, RNA sequencing technology was used to investigate miRNA expression patterns in the yak epididymis. Region-specific miRNA expression was found in the yak epididymis. In all, 683 differentially expressed known miRNAs were obtained; 190, 186 and 307 differentially expressed miRNAs were identified for caput versus corpus, corpus versus cauda and caput versus cauda region pairs respectively. Kyoto Encyclopedia of Genes and Genomes results showed endocytosis as the most enriched pathway across region pairs, followed by protein processing in the endoplasmic reticulum, phagosome, spliceosome and biosynthesis of amino acids in region pair-specific hierarchical order. Gene ontology results showed varied enrichment in terms including cell, biogenesis, localisation, binding and locomotion across region pairs. In addition, significantly higher miR-34c expression was seen in the yak caput epididymidis relative to the corpus and cauda epididymidis.

microRNAs (miR 9, 124, 155 and 224) transdifferentiate mouse macrophages to neurons

Development is an irreversible process of differentiating the undifferentiated cells to functional cells. Brain development involves generation of cells with varied phenotype and functions, which is limited during adulthood, stress, damage/degeneration. Cellular reprogramming makes differentiation reversible process with reprogramming somatic/stem cells to alternative fate with/without stem cells. Exogenously expressed transcription factors or small molecule inhibitors have driven reprogramming of stem/somatic cells to neurons providing alternative approach for pre-clinical/clinical testing and therapeutics. Here in, we report a novel approach of microRNA (miR)- induced trans-differentiation of macrophages (CD11b high) to induced neuronal cells (iNCs) (neuronal markershigh- Nestin, Nurr1, Map2, NSE, Tubb3 and Mash1) without exogenous use of transcription factors. miR 9, 124, 155 and 224 successfully transdifferentiated macrophages to neurons with transient stem cell-like phenotype. We report trans differentiation efficacy 18% and 21% with miR 124 and miR 155. in silico(String 10.0, miR gator, mESAdb, TargetScan 7.0) and experimental analysis indicate that the reprogramming involves alteration of pluripotencygenes like Oct4, Sox2, Klf4, Nanog and pluripotency miR, miR 302. iNCs also shifted to G0 phase indicating manipulation of cell cycle by these miRs. Further, CD133+ intermediate cells obtained during current protocol could be differentiated to iNCs using miRs. The syanpsin⁺ neurons were functionally active and displayed intracellular Ca⁺² evoke on activation. miRs could also transdifferentiate bone marrow-derived macrophages and peripheral blood mononuclear cells to neuronal cells. The current protocol could be employed for direct in vivo reprogramming of macrophages to neurons without teratoma formation for transplantation and clinical studies.

Interspecific Variation in One-Carbon Metabolism within the Ovarian Follicle, Oocyte, and Preimplantation Embryo: Consequences for Epigenetic Programming of DNA Methylation

One-carbon (1C) metabolism provides methyl groups for the synthesis and/or methylation of purines and pyrimidines, biogenic amines, proteins, and phospholipids. Our understanding of how 1C pathways operate, however, pertains mostly to the (rat) liver. Here we report that transcripts for all bar two genes (i.e., BHMT, MAT1A) encoding enzymes in the linked methionine-folate cycles are expressed in all cell types within the ovarian follicle, oocyte, and blastocyst in the cow, sheep, and pig; as well as in rat granulosa cells (GCs) and human KGN cells (a granulosa-like tumor cell line). Betaine-homocysteine methyltransferase (BHMT) protein was absent in bovine theca and GCs, as was activity of this enzyme in GCs. Mathematical modeling predicted that absence of this enzyme would lead to more volatile S-adenosylmethionine-mediated transmethylation in response to 1C substrate (e.g., methionine) or cofactor provision. We tested the sensitivity of bovine GCs to reduced methionine (from 50 to 10 µM) and observed a diminished flux of 1C units through the methionine cycle. We then used reduced-representation bisulfite sequencing to demonstrate that this reduction in methionine during bovine embryo culture leads to genome-wide alterations to DNA methylation in >1600 genes, including a cohort of imprinted genes linked to an abnormal fetal-overgrowth phenotype. Bovine ovarian and embryonic cells are acutely sensitive to methionine, but further experimentation is required to determine the significance of interspecific variation in BHMT expression.

Identification and Profiling of MicroRNAs During Embryogenesis in the Red Claw Crayfish Cherax quadricarinatus

MicroRNAs (miRNAs) are endogenous small non-coding RNAs that constitute a broad layer of gene regulation at both transcriptional and post-transcriptional levels from prokaryotes to eukaryotes. In embryonic development, they regulate the complex gene expression associated with the complexity of embryogenesis. There is little information about miRNAs in the red claw crayfish (Cherax quadricarinatus), an important commercial species and a potential biological model. In the present study, miRNAs and their target genes were identified during three embryonic developmental stages of C. quadricarinatus. Nineteen known miRNAs and 331 novel ones belonging to 50 miRNA families were obtained. A total of 113 differentially expressed miRNAs were identified, and 2,575 target genes were predicted, of which 1,257 were annotated. Additionally, 63 target genes of 9 miRNAs in C. quadricarinatus were found to be related to embryonic development. For example, miR-10 and its target genes may regulate the nervous system development and body segmentation and miR-2788 may regulate cell proliferation to impact embryonic development. Moreover, miR-28 (target gene tutl), miR-50 (target gene fbx5), and miR-1260b (target gene sif) may co-regulate eye development of embryonic C. quadricarinatus. These miRNAs together with their target genes constitute a network for regulating the development of tissues and organs in the embryo of C. quadricarinatus. Our results lay a foundation for further study on the fundamental molecular and developmental mechanism of crustacean embryogenesis.

Transient exposure to miR-203 enhances the differentiation capacity of established pluripotent stem cells

Full differentiation potential along with self-renewal capacity is a major property of pluripotent stem cells (PSCs). However, the differentiation capacity frequently decreases during expansion of PSCs in vitro. We show here that transient exposure to a single microRNA, expressed at early stages during normal development, improves the differentiation capacity of already-established murine and human PSCs. Short exposure to miR-203 in PSCs (miPSCs) induces a transient expression of 2C markers that later results in expanded differentiation potency to multiple lineages, as well as improved efficiency in tetraploid complementation and human-mouse interspecies chimerism assays. Mechanistically, these effects are at least partially mediated by direct repression of de novo DNA methyltransferases Dnmt3a and Dnmt3b, leading to transient and reversible erasure of DNA methylation. These data support the use of transient exposure to miR-203 as a versatile method to reset the epigenetic memory in PSCs, and improve their effectiveness in regenerative medicine.

Extracellular vesicles: Multi-signal messengers in the gametes/embryo-oviduct cross-talk

Extracellular vesicles (EVs) have emerged as novel cell-to-cell communication mediators in physiological and pathological scenarios. Their ability to transfer their molecular cargo (RNAs, proteins and lipids) from one cell to another, in the vicinity or far from the cell of origin, together with their capacity of exerting a functional impact on the target cell make them valuable diagnostic tools as well as therapeutic vectors in a variety of diseases. In the reproductive field, there is a growing interest in the role of EVs in gamete/embryo-maternal communication and their potential implications in the reproductive success. In this review, we provide current knowledge of EVs secreted by the oviduct (oEVs) and embryos (eEVs), since both have been proposed as key players in the crucial two-way dialogue between the oviduct (lining epithelium and secretions) and the embryo that ensures successful pregnancy. Both oEVs and eEVs molecular cargos and their potential role as multi-signal messengers in the gametes/embryo-oviduct cross-talk and in the embryo-to-embryo communication in different species are also addressed. Eventually, a comparative analysis between oEVs and eEVs has been performed to shed some light on common and specific cargos responsible for their functions supporting the early reproductive events and as prime candidate molecules for improving fertility and assisted reproductive technologies outcomes.

MiRNA-155 regulates cumulus cells function, oocyte maturation, and blastocyst formation

Numerous oocytes are retrieved during in vitro fertilization from patients with polycystic ovary syndrome (PCOS). The poor quality of these oocytes leads to lower fertilization and decreases in cleavage and implantation. MiR-155 is one of the microRNA (miRNA) that is increased in serum and granulosa cells of PCOS patients. In this study, we investigate the effects of miR-155 expression and its target genes on oocyte maturation and embryo development. We used the calcium phosphate protocol to transfect vectors that contained miR-155 or miR-off 155 and alone eGFP into cumulus oophorus complex (COCs) of B6D2F1 female mice for in vitro maturation. Cumulus expansion, nuclear, and cytoplasmic maturation, as well as cleavage rates were determined in groups transfected and compared with the control groups. Quantitative real-time polymerase chain reaction was performed to analyze expression levels of miR-155 and the target genes in the cumulus cells, oocytes, and blastocysts. MiR-155 overexpression in COCs suppressed cumulus expansion, oocyte maturation, and inhibition of endogenous miR-155 by miR-off 155 improved cumulus expansion and oocyte maturation by downregulation and expression increase of the Smad2 and Bcl2 genes. On the other hand, overexpression and downregulation of miR-155 in the COCs led to increase and decrease in cleavage rates by changes in expressions of the Mecp2, Jarid2, and Notch1 genes, respectively (P < 0.05). These results suggested that miR-155 overexpression in granulosa cells of PCOS patients can negatively affect nuclear and cytoplasmic maturation, but this miRNA expression has a positive impact on embryo development.

The maternal-to-zygotic transition in bovine in vitro-fertilized embryos is associated with marked changes in small non-coding RNAs†

In mammals, small non-coding RNAs (sncRNAs) have been reported to be important during early embryo development. However, a comprehensive assessment of the inventory of sncRNAs during the maternal-to-zygotic transition (MZT) has not been performed in an animal model that better represents the sncRNA biogenesis pathway in human oocytes and embryos. The objective of this study was to examine dynamic changes in expression of sncRNAs during the MZT in bovine embryos produced by in vitro fertilization (IVF), which occurs at the 8-cell stage. An unbiased, discovery-based approach was employed using small RNAseq to profile sncRNAs in bovine oocytes, 8-cell stage embryos and blastocyst stage embryos followed by network and ontology analyses to explore the functional relevance of differentially expressed micro-RNAS (miRNAs). The relative abundance of miRNAs was markedly higher in 8-cell stage embryos compared to oocytes or blastocyst stage embryos. This shift in miRNA population was largely associated with upregulation of miRNAs predicted to target genes involved in the biological processes of cell development, cell division, Wnt signaling, and pluripotency, among others. Distinct populations of piwi-interacting-like RNAs (pilRNAs) were identified in bovine oocytes and blastocyst stage embryos, though pilRNAs were nearly absent in 8-cell stage embryos. Also, small nucleolar RNAs were highly expressed in 8-cell stage embryos. Overall, these data reveal a strong dynamic shift in the relative abundance of sncRNAs associated with the MZT in bovine oocytes and embryos, suggesting that these molecules may play important roles in the shift from maternal to zygotic control of gene expression.

Association of miR-27aA>G, miR-423C>a, miR-449bA>G, and miR-604A>G Polymorphisms with Risk of Recurrent Implantation Failure

Recurrent implantation failure (RIF) is defined when pregnancy failure occurs after two consecutive in vitro fertilization-embryo transfers to the endometrium using at least four high-quality embryos in women. MicroRNAs are well-known function modulators and are involved in many diseases. Recently, studies on microRNA and recurrent pregnancy loss (RPL) have been actively carried out; however, single nucleotide polymorphisms of miRNA in RPL are not well known. Therefore, we set the aim of this study to identify whether polymorphisms in miRNAs that miR-27aA>G, miR-423C>A, miR-449bA>G, and miR-604A>G are risk factors for idiopathic recurrent implantation failure (RIF) in Korean women. Genotyping was assessed with a polymerase chain reaction-restriction fragment length polymorphism assay. We examined polymorphisms in four miRNA genes: miR-27aA>G, miR-423C>A, miR-449bA>G, and miR-604A>G. We found that the miR-27aA>G, miR-449bA>G, and miR-604A>G polymorphisms were significantly associated with a risk of RIF. In addition, the miR-27aA>G and miR-449bA>G polymorphisms were associated with the frequency of implantation failures. Specifically, the miR-449bAG+GG genotype was associated with RIF prevalence (total RIF: adjusted odd ratio [AOR] = 1.584, 95% CI = 1.008-2.490, P = 0.046; IF ≥ 3 group: AOR = 1.747, 95% CI = 1.088-2.803, P = 0.021; IF ≥ 4: AOR = 1.932, 95% CI = 1.122-3.327, P = 0.018). Based on these results, the miR-449b A>G may be a predisposing factor to RIF susceptibility. However, the mechanism underlying the function of miR-449b A>G in RIF remains to be determined and further studies are needed to improve understanding of the roles of miR-449b A>G, using a larger and more heterogeneous cohort.

The Role of MicroRNAs in Mammalian Fertility: From Gametogenesis to Embryo Implantation

The genetic codes inscribed during two key developmental processes, namely gametogenesis and embryogenesis, are believed to determine subsequent development and survival of adult life. Once the embryo is formed, its further development mainly depends on its intrinsic characteristics, maternal environment (the endometrial receptivity), and the embryo–maternal interactions established during each phase of development. These developmental processes are under strict genetic regulation that could be manifested temporally and spatially depending on the physiological and developmental status of the cell. MicroRNAs (miRNAs), one of the small non-coding classes of RNAs, approximately 19–22 nucleotides in length, are one of the candidates for post-transcriptional developmental regulators. These tiny non-coding RNAs are expressed in ovarian tissue, granulosa cells, testis, oocytes, follicular fluid, and embryos and are implicated in diverse biological processes such as cell-to-cell communication. Moreover, accumulated evidences have also highlighted that miRNAs can be released into the extracellular environment through different mechanisms facilitating intercellular communication. Therefore, understanding miRNAs mediated regulatory mechanisms during gametogenesis and embryogenesis provides further insights about the molecular mechanisms underlying oocyte/sperm formation, early embryo development, and implantation. Thus, this review highlights the role of miRNAs in mammalian gametogenesis and embryogenesis and summarizes recent findings about miRNA-mediated post-transcriptional regulatory mechanisms occurring during early mammalian development.

Amniotic microvesicles impact hatching and pregnancy percentages of in vitro bovine embryos and blastocyst microRNA expression versus in vivo controls

Embryo development and implantation are dynamic processes, responsive to external signals, and can potentially be influenced by many environmental factors. The aims of this study were to evaluate the effects of a culture medium supplemented with amniotic-derived microvesicles (MVs) on in vitro embryo hatching after cryopreservation, and pregnancy rate following embryo transfer. In addition, miRNA profiling of blastocysts produced in vitro, with or without (control; CTR) amniotic MV supplementation, was also evaluated using blastocysts produced in vivo. In vitro embryos were cultured with and without amniotic MV supplementation. In vivo blastocysts were obtained from superovulated cows. Samples for RNA isolation were obtained from three pools of 10 embryos each (in vivo, in vitro-CTR and in vitro + MVs). Our results show that the hatching percentage of cryopreserved in vitro + MVs embryos is higher (P < 0.05) than in vitro-CTR embryos and the pregnancy rate with fresh and cryopreserved in vitro + MVs embryos is higher than in vitro-CTR embryos. In addition, the analysis of differently expressed (DE) microRNAs showed that embryos produced in vivo are clearly different from those produced in vitro. Moreover, in vitro-CTR and in vitro + MVs embryos differ significantly for expression of two miRNAs that were found in higher concentrations in in vitro-CTR embryos. Interestingly, these two miRNAs were also reported in degenerated bovine embryos compared to good quality blastocysts. In conclusion, MV addition during in vitro production of embryos seems to counteract the adverse effect of in vitro culture and partially modulate the expression of specific miRNAs involved in successful embryo implantation.

Bta-miR-10b Secreted by Bovine Embryos Negatively Impacts Preimplantation Embryo Quality

In a previous study, we found miR-10b to be more abundant in a conditioned culture medium of degenerate embryos compared to that of blastocysts. Here, we show that miR-10b mimics added to the culture medium can be taken up by embryos. This uptake results in an increase in embryonic cell apoptosis and aberrant expression of DNA methyltransferases (DNMTs). Using several algorithms, Homeobox A1 (HOXA1) was identified as one of the potential miR-10b target genes and dual-luciferase assay confirmed HOXA1 as a direct target of miR-10b. Microinjection of si-HOXA1 into embryos also resulted in an increase in embryonic cell apoptosis and downregulation of DNMTs. Cell progression analysis using Madin–Darby bovine kidney cells (MDBKs) showed that miR-10b overexpression and HOXA1 knockdown results in suppressed cell cycle progression and decreased cell viability. Overall, this work demonstrates that miR-10b negatively influences embryo quality and might do this through targeting HOXA1 and/or influencing DNA methylation.

Bovine Embryo-Secreted microRNA-30c Is a Potential Non-invasive Biomarker for Hampered Preimplantation Developmental Competence

Recently, secreted microRNAs (miRNAs) have received a lot of attention since they may act as autocrine factors. However, how secreted miRNAs influence embryonic development is still poorly understood. We identified 294 miRNAs, 114 known, and 180 novel, in the conditioned medium of individually cultured bovine embryos. Of these miRNAs, miR-30c and miR-10b were much more abundant in conditioned medium of slow cleaving embryos compared to intermediate cleaving ones. MiR-10b, miR-novel-44, and miR-novel-45 were higher expressed in the conditioned medium of degenerate embryos compared to blastocysts, while the reverse was observed for miR-novel-113 and miR-novel-139. Supplementation of miR-30c mimics into the culture medium confirmed the uptake of miR-30c mimics by embryos and resulted in increased cell apoptosis, as also shown after delivery of miR-30c mimics in Madin-Darby bovine kidney cells (MDBKs). We also demonstrated that miR-30c directly targets Cyclin-dependent kinase 12 (CDK12) through its 3′ untranslated region (3′-UTR) and inhibits its expression. Overexpression and downregulation of CDK12 revealed the opposite results of the delivery of miRNA-30c mimics and inhibitor. The significant down-regulation of several tested DNA damage response (DDR) genes, after increasing miR-30c or reducing CDK12 expression, suggests a possible role for miR-30c in regulating embryo development through DDR pathways.

MicroRNA expression in bovine preimplantation embryos

We profiled 98 mature microRNAs (miRNAs) using a stem-loop reverse transcription polymerase chain reaction assay array based on human miRNAs. We demonstrated that one, but not two, base-pair changes in the miRNA recognition sequence at the 3' end only marginally affected copy number estimates. Absolute levels of miRNAs were measured in matured cattle oocytes, eight-cell embryos and normal and parthenogenetic blastocysts and Day-14 trophoblast. Most miRNA concentrations were below the expected functional threshold required for effective repression of moderately to highly abundant target RNA. In oocytes and peri-embryonic genome activation embryos, miRNA 320, a member of the Dgcr8/Drosha-independent class of miRNAs, was expressed at greater than 1000 copies per embryo. miRNAs were more abundant at the eight-cell than the oocyte stage. miRNA concentrations per cell increased from the eight-cell to the blastocyst stage. Both the number of miRNA species and their expression levels were reduced in trophoblast tissue at Day 14. The parthenogenetic samples were more related in their miRNA expression profiles to each other than to their wild-type (in vitro-produced cultured) counterparts. miRNAs 299 and 323, which have been shown to be maternally expressed in other species, were also more than 4-fold overexpressed in the cattle parthenogenetic samples.

Extracellular Vesicles: Decoding a New Language for Cellular Communication in Early Embryonic Development

The blastocyst inner cell mass (ICM) that gives rise to a whole embryo in vivo can be derived and cultured in vitro as embryonic stem cells (ESCs), which retain full developmental potential. ICM cells receive, from diverse sources, complex molecular and spatiotemporal signals that orchestrate the finely-tuned processes associated with embryogenesis. Those instructions come, continuously, from themselves and from surrounding cells, such as those present in the trophectoderm and primitive endoderm (PrE). A key component of the ICM niche are the extracellular vesicles (EVs), produced by distinct cell types, that carry and transfer key molecules that regulate target cells and modulate cell renewal or cell fate. A growing number of studies have demonstrated the extracellular circulation of morphogens, a group of classical regulators of embryo development, are carried by EVs. miRNAs are also an important cargo of the EVs that have been implicated in tissue morphogenesis and have gained special attention due to their ability to regulate protein expression through post-transcriptional modulation, thereby influencing cell phenotype. This review explores the emerging evidence supporting the role of EVs as an additional mode of intercellular communication in early embryonic and ESCs differentiation.

Profiling bovine blastocyst microRNAs using deep sequencing

MicroRNAs (miRNAs) are known to control several reproductive functions, including oocyte maturation, implantation and early embryonic development. Recent advances in deep sequencing have allowed the analysis of all miRNAs of a sample. However, when working with embryos, due to the low RNA content, miRNA profiling is challenging because of the relatively large amount of total RNA required for library preparation protocols. In the present study we compared three different procedures for RNA extraction and prepared libraries using pools of 30 bovine blastocysts. In total, 14 of the 15 most abundantly expressed miRNAs were common to all three procedures. Furthermore, using miRDeep discovery and annotation software (Max Delbrück Center), we identified 1363 miRNA sequences, of which bta-miR-10b and bta-miR-378 were the most abundant. Most of the 179 genes identified as experimentally validated (86.6%) or predicted targets (13.4%) were associated with cancer canonical pathways. We conclude that reliable analysis of bovine blastocyst miRNAs can be achieved using the procedures described herein. The repeatability of the results across different procedures and independent replicates, as well as their consistency with results obtained in other species, support the biological relevance of these miRNAs and of the gene pathways they modulate in early embryogenesis.

The impact of infertility diagnosis on embryo-endometrial dialogue

Initial stages of implantation involve bi-directional molecular crosstalk between the blastocyst and endometrium. This study investigated an association between infertility etiologies, specifically advanced maternal age (AMA) and endometriosis, on the embryo-endometrial molecular dialogue prior to implantation. Co-culture experiments were performed with endometrial epithelial cells (EEC) and cryopreserved day 5 blastocysts (n = 41 ≥ Grade 3BB) donated from patients presenting with AMA or endometriosis, compared to fertile donor oocyte controls. Extracellular vesicles isolated from co-culture supernatant were analyzed for miRNA expression and revealed significant alterations correlating to AMA or endometriosis. Specifically, AMA resulted in 16 miRNAs with increased expression (P ≤ 0.05) and strong evidence for negative regulation toward 206 target genes. VEGFA, a known activator of cell adhesion, displayed decreased expression (P ≤ 0.05), validating negative regulation by 4 of these increased miRNAs: miR-126; 150; 29a; 29b (P ≤ 0.05). In endometriosis patients, a total of 10 significantly altered miRNAs displayed increased expression compared to controls (miR-7b; 9; 24; 34b; 106a; 191; 200b; 200c; 342-3p; 484) (P ≤ 0.05), targeting 1014 strong evidence-based genes. Three target genes of miR-106a (CDKN1A, E2F1 and RUNX1) were independently validated. Functional annotation analysis of miRNA-target genes revealed enriched pathways for both infertility etiologies, including disrupted cell cycle regulation and proliferation (P ≤ 0.05). These extracellular vesicle-bound secreted miRNAs are key transcriptional regulators in embryo-endometrial dialogue and may be prospective biomarkers of implantation success. One of the limitations of this study is that it was a stimulated, in vitro model and therefore may not accurately reflect the in-vivo environment.

Identification of potential early biomarkers of preeclampsia

INTRODUCTION

It is thought that poor placental perfusion caused by inadequate remodelling of the maternal spiral arteries leads to preeclampsia (PE). To identify novel signalling pathways that contribute to PE pathogenesis and to create prerequisites for the non-invasive diagnosis of PE before clinical manifestations of the disease, this study aimed to evaluate miRNA expression levels in the placenta and blood plasma of pregnant women.

METHODS

miRNA deep sequencing followed by real-time quantitative RT-PCR was applied to compare miRNA expression profiles in the placenta and blood plasma from women with early- and late-onset PE relative to the control group.

RESULTS

A more than two-fold decrease in miR-532-5p, -423-5p, -127-3p, -539-5p, -519a-3p, and -629-5p and let-7c-5p expression levels was observed in the placenta, while a more than two-fold increase in miR-423-5p, 519a-3p, and -629-5p and let-7c-5p was observed in the blood plasma of pregnant women with PE. The above-listed miRNAs are associated with PE for the first time in this study, except for miR-519a-3p, whose role in PE has already been postulated. Using a logistic regression, plasma samples were classified into the early-onset PE group (probability p = 0.01, 80% specificity, 87.5% sensitivity and 87.5% precision) and showed increased miR-423-5p expression levels that were confirmed by the 9.8-fold up-regulation (р = 0.0002498) of miR-423-5p expression observed in the blood plasma at 11-13 GW by RT-PCR in a group of pregnant women manifesting severe PE clinical signs at 28-33 GW.

CONCLUSIONS

miR-423-5p may be considered a potential candidate for the early diagnosis of PE during the targeted management of high-risk pregnancies.

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.

MicroRNA Signaling in Embryo Development

Expression of microRNAs (miRNAs) is essential for embryonic development and serves important roles in gametogenesis. miRNAs are secreted into the extracellular environment by the embryo during the preimplantation stage of development. Several cell types secrete miRNAs into biological fluids in the extracellular environment. These fluid-derived miRNAs have been shown to circulate the body. Stable transport is dependent on proper packaging of the miRNAs into extracellular vesicles (EVs), including exosomes. These vesicles, which also contain RNA, DNA and proteins, are on the forefront of research on cell-to-cell communication. Interestingly, EVs have been identified in many reproductive fluids, such as uterine fluid, where their miRNA content is proposed to serve as a mechanism of crosstalk between the mother and conceptus. Here, we review the role of miRNAs in molecular signaling and discuss their transport during early embryo development and implantation.

Potential role of microRNAs in mammalian female fertility

Since the first evidence for the involvement of microRNAs (miRNAs) in various reproductive processes through conditional knockout of DICER, several studies have been conducted to investigate the expression pattern and role of miRNAs in ovarian follicular development, oocyte maturation, embryo development, embryo-maternal communication, pregnancy establishment and various reproductive diseases. Although advances in sequencing technology have fuelled miRNA studies in mammalian species, the presence of extracellular miRNAs in various biological fluids, including follicular fluid, blood plasma, urine and milk among others, has opened a new door in miRNA research for their use as diagnostic markers. This review presents data related to the identification and expression analysis of cellular miRNA in mammalian female fertility associated with ovarian folliculogenesis, oocyte maturation, preimplantation embryo development and embryo implantation. In addition, the relevance of miRNAs to female reproductive disorders, including polycystic ovary syndrome (PCOS), endometritis and abnormal pregnancies, is discussed for various mammalian species. Most importantly, the mechanism of release and the role of extracellular miRNAs in cell-cell communication and their potential role as non-invasive markers in female fertility are discussed in detail. Understanding this layer of regulation in female reproduction processes will pave the way to understanding the genetic regulation of female fertility in mammalian species.

MicroRNA-130b is involved in bovine granulosa and cumulus cells function, oocyte maturation and blastocyst formation

Background

Oocyte maturation and preimplantation embryo development are controlled by array of genes that are post-transcriptionally regulated by microRNAs. With respect to this, previously, we identified altered expression of microRNA-130b (miR-130b) during oocyte maturation. Here, we aimed to investigate the role of miR-130b in bovine granulosa and cumulus cell function, oocyte maturation and preimplantation embryo development using gain- and loss-of- function approach.

Methods

For this study, the granulosa cells, cumulus cells and the oocytes were collected from ovaries obtained from slaughterhouse. The genes targeted by miR-130b were identified using dual-luciferase reporter assay. The role of miR-130b in granulosa and cumulus cell function was investigated by increasing and inhibiting its expression in in vitro cultured cells using miR-130b precursor and inhibitor, respectively while the role of miR-130b on oocyte development, immature oocytes were microinjected with miR-130b precursor and inhibitor and the polar body extrusion, the proportion of oocytes reaching to metaphase II stage and the mitochondrial were determined in each oocyte group 22 h after microinjection. Moreover, to investigate the role of miR-130b during preimplantation embryo development, zygote stage embryos were microinjected with miR-130b precursor or inhibitor and the cleavage rate, morula and blastocyst formation was analyzed in embryos derived from each zygote group after in vitro culture.

Results

The luciferase assay showed that SMAD5 and MSK1 genes were identified as the direct targets of miR-130b. Overexpression of miR-130b increased the granulosa and cumulus cell proliferation, while inhibition showed the opposite phenotype. Apart from these, modulation of miR-130b altered the lactate production and cholesterol biosynthesis in cumulus cells. Furthermore, inhibition of miR-130b expression during oocyte in vitro maturation reduced the first polar body extrusion, the proportion of oocytes reaching to metaphase II stage and the mitochondrial activity, while inhibition of miR-130b during preimplantation embryo development significantly reduced morula and blastocyst formation.

Conclusion

This study demonstrated that in vitro functional modulation of miR-130b affected granulosa and cumulus cell proliferation and survival, oocyte maturation, morula and blastocyst formation suggesting that miR-130b is involved in bovine oocyte maturation and preimplantation embryo development.

Electronic supplementary material

The online version of this article (doi:10.1186/s13048-017-0336-1) contains supplementary material, which is available to authorized users.

miR-27a and miR-449b polymorphisms associated with a risk of idiopathic recurrent pregnancy loss

Objective

MicroRNAs (miRNAs) regulate gene expression during the peri-implantation period. The purpose of this study was to investigate whether genetic polymorphisms in the four miRNAs associated with fetal or placental development play roles in the development of idiopathic recurrent pregnancy loss (RPL) in Korean females.

Study design

A case-control study involving 225 controls and 387 women with at least two consecutively recurrent pregnancy losses between 1999 and 2012 was performed. The genotypes of the four miRNA polymorphisms, including miR-27a rs895819, miR-423 rs6505162, miR-449b rs10061133, and miR-605 rs2043556, were analyzed by the polymerase chain reaction-restriction fragment length polymorphism assay. Odds ratios and 95% confidence intervals were estimated using multivariate analyses after maternal age adjustments. The relationships between each of the four microRNA genotypes and each of the six clinical parameters of the RPL patients (plasma homocysteine and folate levels, natural killer cell number, platelet count, prothrombin time, and, activated partial thromboplastin time) were analyzed using multiple linear regression analyses.

Results

Our results suggest that weak associations between decreased RPL risk and the genotypes of miR-27a (AG and AG+GG), combination genotype of miR-27a/miR-423 (AG/GC), and haplotypes of miR-27a/miR-423/miR-449b/miR-605 (G-C-A-G) and miR-27a/miR-449b/miR-605 (G-A-G), whereas weak associations between increased RPL risk and genotypes of miR-449b (GG and AG+GG), combination genotypes of miR-423/miR-449b (CC/GG and CA/AG), miR-449b/miR-605 (AG/AG), haplotypes of miR-27a/miR-423/miR-449b/miR-605 (A-C-G-A, A-A-A-G, and G-C-G-G), miR-27a/miR-423/miR-449b (A-C-G), miR-27a/miR-449b/miR-605 (A-A-G, A-G-A, and G-G-G), miR-423/miR-449b/miR-605 (C-G-G and A-A-G), and miR-423/miR-449b (C-G and A-A). The genotypes of miR-27a (AG and AG+GG) also showed significant contributions to the prediction of folate levels in RPL patients.

Conclusions

The study showed associations between miRNA polymorphisms (miR-27a rs895819 and miR-449b rs10061133) and RPL development, and between the miRNA polymorphism (miR-27a rs895819) and plasma folate levels.

Human Embryos Created by Embryo Splitting Secrete Significantly Lower Levels of miRNA-30c

Studies reporting term pregnancy and the production of genetically identical offspring from isolated blastomeres of early stage embryos have been carried out in small and large animals. However, very little is known about the effects of embryo splitting on the development and reproductive competency of human embryos. In this study, we investigated the effects of embryo splitting on profile of microRNAs (miRNAs) detected in their spent blastocyst medium (SBM) by comparative analysis of miRNA profiles in SBM of human twin embryos created by blastomere biopsy and SBM of blastocysts that resulted in a healthy pregnancy and live birth following embryo transfer. The profile of miRNA secretion in in vitro culture media consistently distinguishes twin from control embryos. We found that six miRNAs are significantly more abundant in SBM from twin embryos, while nine are significantly more abundant in SBM from euploid implanted blastocysts. These nine include miRNA-30c, a previously reported marker of blastocyst implantation potential. Furthermore, 22.9% of miRNAs secreted by twin embryos were never detected in SBM from normal reproductively competent blastocysts, or from trophectoderm (TE) samples from normal blastocysts donated for the research. The miRNA profile, unique to twin blastocysts, might be a result of differential lineage commitment in these embryos.

Autocrine embryotropins revisited: how do embryos communicate with each other in vitro when cultured in groups?

In the absence of the maternal genital tract, preimplantation embryos can develop in vitro in culture medium where all communication with the oviduct or uterus is absent. In several mammalian species, it has been observed that embryos cultured in groups thrive better than those cultured singly. Here we argue that group-cultured embryos are able to promote their own development in vitro by the production of autocrine embryotropins that putatively serve as a communication tool. The concept of effective communication implies an origin, a signalling agent, and finally a recipient that is able to decode the message. We illustrate this concept by demonstrating that preimplantation embryos are able to secrete autocrine factors in several ways, including active secretion, passive outflow, or as messengers bound to a molecular vehicle or transported within extracellular vesicles. Likewise, we broaden the traditional view that inter-embryo communication is dictated mainly by growth factors, by discussing a wide range of other biochemical messengers including proteins, lipids, neurotransmitters, saccharides, and microRNAs, all of which can be exchanged among embryos cultured in a group. Finally, we describe how different classes of messenger molecules are decoded by the embryo and influence embryo development by triggering different pathways. When autocrine embryotropins such as insulin-like growth factor-I (IGF-I) or platelet activating factor (PAF) bind to their appropriate receptor, the phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) pathway will be activated which is important for embryo survival. On the other hand, the mitogen-activated protein kinase (MAPK) pathway is activated when compounds such as hyaluronic acid and serotonin bind to their respective receptors, thereby acting as growth factors. By activating the peroxisome-proliferator-activated receptor family (PPAR) pathway, lipophilic autocrine factors such as prostaglandins or fatty acids have both survival and anti-apoptotic functions. In conclusion, considering different types of messenger molecules simultaneously will be crucial to understanding more comprehensively how embryos communicate with each other in group-culture systems. This approach will assist in the development of novel media for single-embryo culture.

Identification of serum microRNA signatures for diagnosis of mild traumatic brain injury in a closed head injury model

Wars in Iraq and Afghanistan have highlighted the problems of diagnosis and treatment of mild traumatic brain injury (mTBI). MTBI is a heterogeneous injury that may lead to the development of neurological and behavioral disorders. In the absence of specific diagnostic markers, mTBI is often unnoticed or misdiagnosed. In this study, mice were induced with increasing levels of mTBI and microRNA (miRNA) changes in the serum were determined. MTBI was induced by varying weight and fall height of the impactor rod resulting in four different severity grades of the mTBI. Injuries were characterized as mild by assessing with the neurobehavioral severity scale-revised (NSS-R) at day 1 post injury. Open field locomotion and acoustic startle response showed behavioral and sensory motor deficits in 3 of the 4 injury groups at day 1 post injury. All of the animals recovered after day 1 with no significant neurobehavioral alteration by day 30 post injury. Serum microRNA (miRNA) profiles clearly differentiated injured from uninjured animals. Overall, the number of miRNAs that were significantly modulated in injured animals over the sham controls increased with the severity of the injury. Thirteen miRNAs were found to identify mTBI regardless of its severity within the mild spectrum of injury. Bioinformatics analyses revealed that the more severe brain injuries were associated with a greater number of miRNAs involved in brain related functions. The evaluation of serum miRNA may help to identify the severity of brain injury and the risk of developing adverse effects after TBI.

ADAM9 up-regulates N-cadherin via miR-218 suppression in lung adenocarcinoma cells

Lung cancer is the leading cause of cancer death worldwide, and brain metastasis is a major cause of morbidity and mortality in lung cancer. CDH2 (N-cadherin, a mesenchymal marker of the epithelial-mesenchymal transition) and ADAM9 (a type I transmembrane protein) are related to lung cancer brain metastasis; however, it is unclear how they interact to mediate this metastasis. Because microRNAs regulate many biological functions and disease processes (e.g., cancer) by down-regulating their target genes, microRNA microarrays were used to identify ADAM9-regulated miRNAs that target CDH2 in aggressive lung cancer cells. Luciferase assays and western blot analysis showed that CDH2 is a target gene of miR-218. MiR-218 was generated from pri-mir-218-1, which is located in SLIT2, in non-invasive lung adenocarcinoma cells, whereas its expression was inhibited in aggressive lung adenocarcinoma. The down-regulation of ADAM9 up-regulated SLIT2 and miR-218, thus down-regulating CDH2 expression. This study revealed that ADAM9 activates CDH2 through the release of miR-218 inhibition on CDH2 in lung adenocarcinoma.

MicroRNA in situ hybridization on whole-mount preimplantation embryos

Whole-mount in situ hybridization (WISH) using antisense probes is widely used to visualize RNA sequences in embryos and to determine the precise site of expression in the different cells or tissues. The target sequence is hybridized with an antisense RNA probe, followed by visual or fluorescence detection to measure the site and level of expression. However, the detection of short RNA molecules is hampered by the reduced stringency of the probes for short transcripts. Here, we describe a procedure for WISH detection of short RNA molecules, like miRNAs, in mammalian preimplantation embryos using LNA-modified probes with high sensitivity and specificity.

MicroRNAs in domestic livestock

microRNAs (miRNAs) are a class of small noncoding RNA that bind to complementary sequences in the untranslated regions of multiple target mRNAs resulting in posttranscriptional regulation of gene expression. The recent discovery and expression-profiling studies of miRNAs in domestic livestock have revealed both their tissue-specific and temporal expression pattern. In addition, breed-dependent expression patterns as well as single nucleotide polymorphisms in either the miRNA or in the target mRNA binding site have revealed associations with traits of economic importance and highlight the potential use of miRNAs in future genomic selection programs.