Identification and profiling of microRNAs in goat endometrium during embryo implantation

Plasma extracellular vesicles microRNA-208b-3p and microRNA-143-3p as novel biomarkers for sudden cardiac death prediction in acute coronary syndrome

Acute coronary syndrome (ACS) occurs as a result of myocardial ischemia that can give rise to a variety of acute cardiovascular events, including arrhythmia, heart failure and sudden cardiac death (SCD). Currently, there are challenges and insufficient innovations regarding early diagnosis and therapeutic approaches within ACS patients experiencing SCD. Plasma extracellular vesicles (EVs) might serve as biomarkers of many diseases depending on the biological molecules of their cargo, such as miRNAs. This study aims to identify the plasma EVs containing miRNAs as novel biomarkers for the prediction of SCD in ACS patients. A total of 39 ACS patients experiencing SCD and 39 healthy control individuals (HC) were enrolled, among which 9 samples in each group were randomly selected as testing groups for miRNA sequencing in plasma EVs, and the remaining samples were assigned to the validation group. The top 10 significant expression miRNAs were verified by the real-time quantitative polymerase chain reaction. Upregulation of miR-208b-3p, miR-143-3p, miR-145-3p and miR-152-3p, and down-regulation of miR-183-5p were further validated in the validation group. Spearman's correlation analysis and the receiver operating characteristic (ROC) curve showed that both miR-208b-3p and miR-143-3p levels were positively correlated with myoglobin (MYO), and their predictive power for SCD was confirmed. In conclusion, our findings indicate that plasma EVs miR-208b-3p and miR-143-3p may serve as promising biomarkers in predicting SCD in patients with ACS, as well as postmortem forensic diagnosis of the cause of death due to ACS.

miRNA profiling in intrauterine exosomes of pregnant cattle on day 7

Intrauterine exosomes have been identified to be involved in the embryo development and implantation. The aim of this study was to explore the role of miRNAs in intrauterine exosomes in bovine pregnancy. Intrauterine exosomes were collected from uterine flushing fluids of three donor and three recipient Xianan cows 7 days after fertilization. Intrauterine exosomes miRNAs were extracted and the exosomal miRNAs expression levels were analyzed. Sixty miRNAs differed significantly in their amounts between donors and recipients (p-value < 0.05, |log2(FoldChange)| > 1). Twenty-two miRNAs were upregulated and 38 downregulated in the group of donor cows. The bta-miR-184 was the most significant (P _{Benjamini-Hochberg} < 0.001). A total of 9,775 target genes were predicted using the 60 miRNAs. GO and KEGG analysis showed that the target genes were enriched in several biological processes or pathways associated with embryo implantation and endometrial development, such as cell adhesion, cell junction, focal adhesion, and Rap1 signaling pathway. Our findings suggest that, in cattle early pregnancy stage, these differently expressed miRNAs in intrauterine exosomes involved in embryo implantation and endometrial development, which may exert a significant effect and influence the uterine microenvironment for embryo implantation. These results could provide reference for screening and exploring the intrauterine exosomal miRNA affecting embryo implantation.

Circulating miRNAs in maternal plasma as potential biomarkers of early pregnancy in sheep

MicroRNA (miRNA) plays an important role in the control of gene expression and is implied in many biological functions, including embryo implantation and development. The aim was to assess plasma miRNA profiles during the peri-implantation and ascertain potential candidate miRNA markers for early pregnancy diagnosis in ovine plasma. The plasma samples were obtained from a total of 24 ewes on days 12 (pre-implantation; P12, n = 4), 16 (implantation; P16, n = 4) and 22 (post-implantation; P22, n = 4) after mating, and on their corresponding days of 12 (Pre-C; C12, n = 4), 16 (Imp-C; C16, n = 4) and 22 (Post-C; C22, n = 4) of the estrous cycle. The miRNA profiles in plasma were assessed by microarray technology. We detected the presence of 60 ovine-specific miRNAs in plasma samples. Of these miRNAs, 22 demonstrated a differential expression pattern, especially between the estrous cycle and early pregnancy, and targeted 521 genes. Two miRNAs (oar-miR-218a and oar-miR-1185-3p) were confirmed using RT-qPCR in the ovine plasma samples. Protein-protein interaction (PPI) network of target genes established six functional modules, of which modules 1 and 3 were enriched in the common GO terms, such as inflammatory response, defense response, and regulation of immune response. In contrast, module 2 was enriched in the developmental process involved in reproduction, embryo development, embryonic morphogenesis, and regulation of the developmental process. The results indicate that miRNAs profiles of plasma seemed to be modulated during the peri-implantation stage of pregnancy in ewes. Circulating miRNAs could be promising candidates for diagnosis in early ovine pregnancy.

Effect of MiR-100-5p on proliferation and apoptosis of goat endometrial stromal cell in vitro and embryo implantation in vivo

The growth of endometrial stromal cells (ESCs) at implantation sites may be a potential factor affecting the success rate of embryo implantation. Incremental proofs demonstrated that ncRNAs (e.g. miRNAs, lncRNAs and circRNAs) were involved in various biological procedures, including proliferation and apoptosis. In this study, the role of miR‐100‐5p on proliferation and apoptosis of goat ESCs in vitro and embryo implantation in vivo was determined. The mRNA expression of miR‐100‐5p was significantly inhibited in the receptive phase (RE) rather than in the pre‐receptive phase (PE). Overexpression of miR‐100‐5p suppressed ESCs proliferation and induced apoptosis. The molecular target of MiR‐100‐5p, HOXA1, was confirmed by 3′‐UTR assays. Meanwhile, the product of HOXA1 mRNA RT‐PCR increased in the RE more than that in the PE. The HOXA1‐siRNA exerted significant negative effects on growth arrest. Instead, incubation of ESCs with miR‐100‐5p inhibitor or overexpressed HOXA1 promoted the cell proliferation. In addition, Circ‐9110 which acted as a sponge for miR‐100‐5p reversed the relevant biological effects of miR‐100‐5p. The intrinsic apoptosis pathway was suppressed in ESCs, revealing a crosstalk between Circ‐9110/miR‐100‐5p/HOXA1 axis, PI3K/AKT/mTOR, and ERK1/2 pathways. To further evaluate the progress in study on embryo implantation regulating mechanism of miR‐100‐5p in vivo, the pinopodes of two phases were observed and analysed, suggesting that, as similar as in situ, miR‐100‐5p was involved in significantly regulating embryo implantation in vivo. Mechanistically, miR‐100‐5p performed its embryo implantation function through regulation of PI3K/AKT/mTOR and ERK1/2 pathways by targeting Circ‐9110/miR‐100‐5p/HOXA1 axis in vivo.

Establishment of Repertoire of Placentome-Associated MicroRNAs and Their Appearance in Blood Plasma Could Identify Early Establishment of Pregnancy in Buffalo (Bubalus bubalis)

Precise early pregnancy diagnosis in dairy animals is of utmost importance for an efficient dairy production system. Not detecting a dairy animal pregnant sufficiently early after the breeding results to extending the unproductive time of their milk production cycle and causes substantial economic loss for a dairy producer. At present, the most conventional and authentic pregnancy confirmation practice in cows and buffaloes is rectal palpation of the reproductive organs at Days 35–40 after insemination, which sometime leads to considering an animal as false pregnant. Other alternative methods available for early pregnancy diagnosis lack either accuracy or reproducibility or require elaborate instrumentation and laboratory setup not feasible to practice at farmers’ doorstep. The present study was aimed at establishment of the microRNA (miRNA) repertoire of the placentome in buffaloes, which could capture the event of the cross talk between a growing embryo and a dam, through fetal cotyledons and maternal caruncles, and thus could hint at the early pregnancy establishment event in ruminants. Total RNA was isolated from buffalo placentome tissues during early stages of pregnancy (at Day < 25 and Days 30–35), and global small RNA analysis was performed by using Illumina single-end read chemistry and Bubalus bubalis genome. A total of 2,199 miRNAs comprising 1,620 conserved and 579 non-conserved miRNAs were identified. Stringent functional miRNA selection criteria could predict 20 miRNAs worth evaluating for their abundance in the plasma of pregnant, non-pregnant, cyclic non-bred, and non-cyclic prepubertal animals. Eight of them (viz., miR-195-5p, miR-708-3p, miR-379-5p, miR-XX1, miR-XX2, miR-130a-3p, miR-200a-3p, and miR-27) displayed typical abundance patterns in the plasma samples of the animals on Day 19 as well as Day 25 post-insemination, thus making them ambiguous candidates for early pregnancy detection. Similarly, higher abundance of miR-200a-3p and miR130a-3p in non-pregnant animals was indicative of their utility for detecting the animals as not pregnant. Most interestingly, miR-XX1 and miR-XX2 were very characteristically abundant only in pregnant animals. In silico target prediction analysis confirmed that these two miRNAs are important regulators of cyclooxygenase-2 (COX-2) and cell adhesion molecule-2 (CADM-2), both of which play a significant role in the implantation process during feto-maternal cross talk. We interpret that circulatory miR-XX1 and miR-XX2 in blood plasma could be the potential biomarkers for early pregnancy detection in buffaloes.

Differentially Expressed MiRNAs of Goat Submandibular Glands Among Three Developmental Stages Are Involved in Immune Functions

Submandibular glands (SMGs) are one of the primary components of salivary glands in goats. The proteins and biologically active substances secreted by the SMGs change with growth and development. Our previous studies showed that most of the differentially expressed genes in the SMGs of goats at different developmental stages are involved in immune-related signaling pathways, but the miRNA expression patterns in the same tissues are unknown. The aim of this study was to reveal the expression profile of miRNAs at three different developmental stages, detect differentially expressed miRNAs (DE miRNAs) and predict disease-related DE miRNAs. SMG tissue samples were collected from groups of 1-month-old kids, 12-month-old maiden goats and 24-month-old adult goats (three samples from each group), and high-throughout transcriptome sequencing was conducted. A total of 178, 241 and 7 DE miRNAs were discovered between 1-month-old kids and 12-month-old maiden goats, between 1-month-old kids and 24-month-old adult goats, and between 12-month-old maiden goats and 24-month-old adult goats, respectively. Among these DE miRNAs, 88 DE miRNAs with medium or high expression levels (TPM ≥50) were classified into five expression pattern clusters. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses indicated that some of the predicted target genes of the DE miRNAs in the five clusters were enriched in disease-related GO terms and pathways. MiRNA target genes in significant pathways were significantly enriched in Hepatitis B (FDR = 9.03E-10) and Pathways in cancer (FDR = 4.2E-10). Further analysis was performed with a PPI network, and 10 miRNAs were predicted to play an important role in the occurrence and prevention of diseases during the growth and development of goats.

Essential Role of CRIM1 on Endometrial Receptivity in Goat

In domestic ruminants, endometrial receptivity is related to successful pregnancy and economic efficiency. Despite several molecules having been reported in the past regarding endometrial receptivity regulation, much regarding the mechanism of endometrial receptivity regulation remains unknown due to the complex nature of the trait. In this work, we demonstrated that the cysteine-rich transmembrane bone morphogenetic protein (BMP) regulator 1 (CRIM1) served as a novel regulator in the regulation of goat endometrial receptivity in vitro. Our results showed that hormones and IFN-τ increased the expression of CRIM1 in goat endometrial epithelial cells (EECs). Knockdown of CRIM1 via specific shRNA hindered cell proliferation, cell adhesion and prostaglandins (PGs) secretion and thus derailed normal endometrial receptivity. We further confirmed that receptivity defect phenotypes due to CRIM1 interference were restored by ATG7 overexpression in EECs while a loss of ATG7 further impaired receptivity phenotypes. Moreover, our results showed that changing the expression of ATG7 affected the reactive oxygen species (ROS) production. Moreover, mR-143-5p was shown to be a potential upstream factor of CRIM1-regulated endometrial receptivity in EECs. Overall, these results suggest that CRIM1, as the downstream target of miR-143-5p, has effects on ATG7-dependent autophagy, regulating cell proliferation, cell adhesion and PG secretion, and provides a new target for the diagnosis and treatment of early pregnancy failure and for improving the success rates of artificial reproduction.

Interferon-τ regulates the expression and function of bovine leukocyte antigen by downregulating bta-miR-204

IFN-τ is a pregnancy recognition factor that regulates embryo implantation in ruminants. IFN-τ has been suggested to be involved in the expression of microRNA (miRNA/miR) and bovine leukocyte antigen (BoLA), which is an analog of the human major histocompatibility complex class I. However, little is known about whether the miRNAs are involved in the expression of BoLA in ruminants. The present study firstly verified that bta-miR-204 was downregulated and that BoLA was upregulated in the uterine tissues of dairy cows during early pregnancy. Subsequently, luciferase reporter assays, reverse transcription-quantitative PCR and western blot analysis were used to validate BoLA as the target gene of bta-miR-204. Moreover, BoLA was markedly upregulated and bta-miR-204 was downregulated in bovine endometrial epithelial cells (bEECs) treated with IFN-τ. In addition, the results indicated that when the expression level of BoLA was increased by IFN-τ, the expression level of programmed death-ligand 1 (PD-L1) and programmed death-ligand 2 (PD-L2) was also increased. Furthermore, when BoLA was silenced in bEECs by small interfering RNA, the expression of PD-L1 and PD-L2 was not affected by IFN-τ. The expression level of PD-L1 and PD-L2 was also increased in the uterine tissues of pregnant dairy cattle. In conclusion, IFN-τ may function by suppressing the expression of bta-miR-204 to increase the expression of BoLA during the embryo implantation period in cattle. IFN-τ may induce PD-L1 and PD-L2 transcription by regulating BoLA, which may influence the T cell immune response, thereby regulating pregnant cattle immunization.

MicroRNAs from Extracellular Vesicles Secreted by Bovine Embryos as Early Biomarkers of Developmental Competence

During early development, embryos secrete extracellular vesicles (EVs) that participate in embryo–maternal communication. Among other molecules, EVs carry microRNAs (miRNAs) that interfere with gene expression in target cells; miRNAs participate in embryo–maternal communication. Embryo selection based on secreted miRNAs may have an impact on bovine breeding programs. This research aimed to evaluate the size, concentration, and miRNA content of EVs secreted by bovine embryos with different developmental potential, during the compaction period (days 3.5–5). Individual culture media from in vitro–produced embryos were collected at day 5, while embryos were further cultured and classified at day 7, as G1 (conditioned-culture media by embryos arrested in the 8–16-cells stage) and G2 (conditioned-culture media by embryos that reached blastocyst stages at day 7). Collected nanoparticles from embryo conditioned culture media were cataloged as EVs by their morphology and the presence of classical molecular markers. Size and concentration of EVs from G1 were higher than EVs secreted by G2. We identified 95 miRNAs; bta-miR-103, bta-miR-502a, bta-miR-100, and bta-miR-1 were upregulated in G1, whereas bta-miR-92a, bta-miR-140, bta-miR-2285a, and bta-miR-222 were downregulated. The most significant upregulated pathways were fatty acid biosynthesis and metabolism, lysine degradation, gap junction, and signaling pathways regulating pluripotency of stem cells. The characteristics of EVs secreted by bovine embryos during the compaction period vary according to embryo competence. Embryos that reach the blastocyst stage secrete fewer and smaller vesicles. Furthermore, the loading of specific miRNAs into the EVs depends on embryo developmental competence.

Biogenesis and functions of circular RNAs and their role in diseases of the female reproductive system

A member of the newly discovered RNA family, circular RNA (circRNA) is considered as the intermediate product of by-product splicing or abnormal RNA splicing. With the development of RNA sequencing, circRNA has recently drawn research interest. CircRNA exhibits stability, species conservatism, and tissue cell specificity. It acts as a miRNA sponge in the circRNA-microRNA (miRNA-mRNA axis, which can regulate gene transcription and protein translation. Studies have confirmed that circRNA is ubiquitous in eukaryotic cells, which play an important role in the regulation of human gene expression and participate in the occurrence and development of various human diseases. CircRNA may be closely related to the occurrence and development of female reproductive system diseases. By analyzing the biological functions and mechanism of circRNA, we find that circRNA has certain development prospects as biomarkers of the female reproductive system diseases. The production and degradation of circRNA, biological functions, and their association with the occurrence of diseases of female reproductive system are reviewed in this article.

MiR-184 Combined with STC2 Promotes Endometrial Epithelial Cell Apoptosis in Dairy Goats via RAS/RAF/MEK/ERK Pathway

The endometrium undergoes a series of complex changes to form a receptive endometrium (RE) that allows the embryo to be implanted. The inability to establish endometrial receptivity of livestock causes embryo implantation failure and considerable losses to animal husbandry. MicroRNAs (miRNAs) are a class of noncoding RNAs. Studies have found that miRNAs can regulate many critical physiological processes, including the establishment of RE during embryo implantation. miR-184 is highly expressed in the endometrial receptive period of dairy goats. This study aimed to explore the effect of miR-184 on endometrial epithelial cell (EEC) apoptosis and RE establishment. Stanniocalcin2 (STC2) is a direct target of miR-184, and miR-184 decreases the expression of STC2 in dairy goat EECs. miR-184 can activate EECs apoptosis through the RAS/RAF/MEK/ERK pathway. Additionally, miR-184 increases the expression levels of RE marker genes, such as forkhead box M1 (FOXM1) and vascular endothelial growth factor (VEGF). These findings indicate that miR-184 promotes the apoptosis of endometrial epithelial cells in dairy goats by downregulating STC2 via the RAS/RAF/MEK/ERK pathway, and that it may also regulate the establishment of RE in dairy goats.

miR-34a/c induce caprine endometrial epithelial cell apoptosis by regulating circ-8073/CEP55 via the RAS/RAF/MEK/ERK and PI3K/AKT/mTOR pathways

microRNAs (miRNAs) and circular RNAs (circRNAs) are important for endometrial receptivity establishment and embryo implantation in mammals. miR-34a and miR-34c are highly expressed in caprine receptive endometrium (RE). Herein, the functions and mechanisms of miR-34a/c in caprine endometrial epithelial cell (CEEC) apoptosis and RE establishment were investigated. miR-34a/c downregulated the expression level of centrosomal protein 55 (CEP55) and were sponged by circRNA8073 (circ-8073), thereby exhibiting a negative interaction in CEEC. miR-34a/c induced CEEC apoptosis by targeting circ-8073/CEP55 through the regulation of the RAS/RAF/MEK/ERK and phosphoitide 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathways. Positive and negative feedback loops and cross-talk were documented between the RAS/RAF/MEK/ERK and PI3K/AKT/mTOR pathways. miR-34a/c regulated the levels of RE marker genes, including forkhead box M1, vascular endothelial growth factor, and osteopontin (OPN). These results suggest that miR-34a/c not only induce CEEC apoptosis by binding to circ-8073 and CEP55 via the RAS/RAF/MEK/ERK and PI3K/AKT/mTOR pathways, but may also regulate RE establishment in dairy goats.

An update on the progress of transcriptomic profiles of human endometrial receptivity

Despite advances in our understanding of fertility, implantation failure remains a significant problem for both spontaneous and assisted pregnancies. Most research efforts concerning the process of implantation are embryo-centric, with a dearth of studies on endometrial factors. Currently, there are no practical and effective diagnostic tools available to precisely predict endometrial receptivity. Transcriptomics, a field based on microarray technology, has a number of procedures for clinical applications, although the functional relevance of most identified genes remains unclear. Importantly, RNA sequencing will further improve the precision and broaden the clinical use of the transcriptome by detecting previously undiscovered genes, which could be used to further our understanding of endometrial receptivity. In this review, potential biomarkers based on endometrium gene expression profiles of human endometrial receptivity were described and compared in natural and stimulated cycles toward discovering future prospects for personalized medical approaches. The intent of this synthesis is to provide researchers, doctors, and clinicians in the field with a better understanding of endometrium receptivity, promote further study in the transcriptome in embryo implantation, and ultimately, improve pregnancy outcome.

Circular RNAs in gynecological disease: promising biomarkers and diagnostic targets

Circular RNAs (circRNAs) are a category of RNA molecules with covalently closed circles lacking both a 5′ cap and a 3′ tail. In recent years, circRNAs have attracted much attention and become a research hotspot of the RNA field following miRNAs and lncRNAs. CircRNAs exhibit tissue specificity, structural stability, and evolutionary conservation. Although the biological effects of circRNAs are still underestimated, many studies have shown that circRNAs have functions including regulation of transcription, translation into proteins and miRNA sponges. In this review, we briefly described the biogenesis and function of circRNAs and present circular transcripts in gynecological disease.

Analyses of circRNA profiling during the development from pre-receptive to receptive phases in the goat endometrium

BACKGROUND

Recent studies have revealed that noncoding RNAs play important regulatory roles in the formation of endometrial receptivity. Circular RNAs (circRNAs) are a universally expressed noncoding RNA species that have been recently proposed to act as miRNA sponges that directly regulate expression of target genes or parental genes.

RESULTS

We used Illumina Solexa technology to analyze the expression profiles of circRNAs in the endometrium from three goats at gestational day 5 (pre-receptive endometrium, PE) and three goats at gestational day 15 (receptive endometrium, RE). Overall, 21,813 circRNAs were identified, of which 5,925 circRNAs were specific to the RE and 9,078 were specific to the PE, which suggested high stage-specificity. Further analysis found 334 differentially expressed circRNAs in the RE compared with PE (P < 0.05). The analysis of the circRNA-miRNA interaction network further supported the idea that circRNAs act as miRNA sponges to regulate gene expression. Moreover, some circRNAs were regulated by estrogen (E2)/progesterone (P4) in endometrial epithelium cell lines (EECs) and endometrial stromal cell line (ESCs), and each circRNA molecule exhibited unique regulation characteristics with respect to E2 and P4.

CONCLUSIONS

These data provide an endometrium circRNA expression atlas corresponding to the biology of the goat receptive endometrium during embryo implantation.

Endometrial Epithelial Cell Apoptosis Is Inhibited by a ciR8073-miR181a-Neurotensis Pathway during Embryo Implantation

Development of the receptive endometrium (RE) from the pre-receptive endometrium (PE) is essential for embryo implantation, but its molecular mechanisms have not been fully understood. In this study, lncRNA-miRNA-mRNA and circRNA-miRNA-mRNA networks were constructed to explore the functions of potential competing endogenous RNAs (ceRNA) during the development of RE in dairy goats. We observed that circRNA8073 (ciR8073) decreased the levels of miR-181a by acting as a miRNA sponge. This effect indirectly increased the expression of neurotensin in endometrial epithelial cells (EECs). Neurotensin then inhibited EEC apoptosis by increasing the expression of BCL-2/BAX in favor of BCL-2 via the MAPK pathway and also induced increased expression of leukemia-inhibitory factor, cyclo-oxygenase 2, vascular endothelial growth factor A, and homeobox A10. We have thus identified a ciR8073-miR181a-neurotensin pathway in the endometrium of dairy goats. Through this pathway, ciR8073 functions as a ceRNA that sequesters miR-181a, thereby protecting neurotensin transcripts from miR-181a-mediated suppression in EECs.

Distribution of ncRNAs expression across hypothalamic-pituitary-gonadal axis in Capra hircus

Background

Molecular regulation of the hypothalamic-pituitary-gonadal (HPG) axis plays an essential role in the fine tuning of seasonal estrus in Capra hircus. Noncoding RNAs (ncRNAs) are emerging as key regulators in sexual development and mammalian reproduction. In order to identify ncRNAs and to assess their expression patterns, along the HPG axis, we sequenced ncRNA libraries from hypothalamus, pituitary and ovary of three goats.

Results

Among the medium length noncoding RNAs (mncRNAs) identified, small nucleolar RNAs (snoRNAs) and transfer RNAs (tRNAs) were found to be more abundant in ovary and hypothalamus, respectively. The observed GC content was representative for different classes of ncRNAs, allowing the identification of a tRNA-derived RNA fragments (tRFs) subclass, which had a peak distribution around 32–38% GC content in the hypothalamus. Differences observed among organs confirmed the specificity of microRNA (miRNA) profiles for each organ system.

Conclusions

Data on ncRNAs in organs constituting the HPG axis will contribute to understanding their role in the physiological regulation of reproduction in goats.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-4767-x) contains supplementary material, which is available to authorized users.

Testin was regulated by circRNA3175-miR182 and inhibited endometrial epithelial cell apoptosis in pre-receptive endometrium of dairy goats

Circular RNAs (circRNAs) in various tissues and cell types from mammalian sources have been studied. However, present knowledge on circRNAs in the development of pre-receptive endometrium (PE) in dairy goats is limited. In the pre-receptive endometrium of dairy goats, higher circRNA3175 (ciR3175) levels, lower miR-182 levels and higher Testin (TES) levels were detected. And ciR3175 could decreased the miR-182 levels by acting as a miRNA sponge, and miR-182 could down-regulated the expression level of TES via the predicted target site in endometrial epithelial cells (EECs) in vitro. Via this way, ciR3175 functioned as a competing endogenous RNAs (ceRNA) that sequestered miR-182, thereby protecting TES transcripts from miR-182-mediated suppression in EECs in vitro. Further, TES inhibited EECs apoptosis by decreasing the expression level of BCL-2/BAX via the MAPK pathway. Thus, a ciR3175-miR182-TES pathway in the endometrium was identified in EECs, and the modulation of which could emerge as a potential target in regulating the pre-receptive endometrium development in dairy goats.

miR-26a promoted endometrial epithelium cells (EECs) proliferation and induced stromal cells (ESCs) apoptosis via the PTEN-PI3K/AKT pathway in dairy goats

Changes in endometrial cell morphology and function are absolutely necessary for successful embryo implantation. In this study, miR-26a was widely expressed in dairy goats, and was found to be regulated by β-estradiol (E2) and progesterone (P4) in endometrial epithelium cells (EECs) as well as stromal cells (ESCs). Furthermore, miR-26a played a role in the regulation of cells proliferation and apoptosis by directly regulating PTEN and indirectly regulating the PI3K/AKT pathway in EECs but not in ESCs of dairy goats in vitro. In addition, miR-26a regulated the expression of osteopontin (OPN), vascular endothelial growth factor (VEGF), Cyclooxygenase-2 (COX-2), and prolactin (PRL) in endometrial cells. Therefore, we could get a conclusion that miR-26a had very complex and diverse functions in the endometrial cells during the development of endometrial receptivity in dairy goats. This study provided an efficient platform for studying the regulatory effect of miR-26a on endometrial cells during the development of endometrial receptivity in dairy goats.

CircRNA-9119 regulates the expression of prostaglandin-endoperoxide synthase 2 (PTGS2) by sponging miR-26a in the endometrial epithelial cells of dairy goat

Circular RNAs (circRNAs) have been found to play important functional roles in epigenetic regulation under certain physiological and pathological conditions. However, knowledge of circRNAs during the development of receptive endometrium (RE) from pre-RE is limited. In the RE of dairy goats, higher circRNA-9119 levels, with lower miR-26a and higher prostaglandin-endoperoxide synthase 2 (PTGS2) levels, were detected. Further study showed that circRNA-9119 decreased levels of miR-26a by acting as a microRNA sponge, and that miR-26a downregulated the expression of PTGS2 via the predicted target site in endometrial epithelial cells (EECs) of dairy goats in vitro. In this way, circRNA-9119 functioned as a competing endogenous RNAs (ceRNA) that sequestered miR-26a, thereby protecting PTGS2 transcripts from miR-26a-mediated suppression in dairy goat EECs in vitro. Furthermore, PTGS2 participated in the regulation of some protein markers for endometrial receptivity in dairy goat EECs in vitro. Thus, a circRNA-9119–miR-26a–PTGS2 pathway in the endometrium was identified, and modulation of circRNA-9119–miR-26a–PTGS2 expression in EECs may emerge as a potential target to regulate the development of RE.

Genome-wide identification of microRNAs responsive to Ectropis oblique feeding in tea plant (Camellia sinensis L.)

The tea plant (Camellia sinensis L.) is vulnerable to the geometrid Ectropis oblique; although microRNAs (miRNAs) are important for plant growth, development and stress response, the function of miRNAs in the response of C. sinensis to stress from E. oblique is unclear. To identify E. oblique stress-responsive miRNAs and their target genes in tea plant, three small RNA libraries were constructed from leaves subjected to mechanical wounding (MW), geometrid attack (GA) and from healthy control (CK) leaves. Using high-throughput sequencing, 130 known miRNAs and 512 novel miRNAs were identified; of these, differential expression under GA stress was observed for 36 known and 139 novel miRNAs. Furthermore, 169 GA-responsive and 173 MW-responsive miRNAs were detected by miRNA microarray. The expression patterns of six GA-responsive miRNAs were validated by qRT-PCR. Several target genes for these miRNAs encode various transcription factors, including ethylene-responsive transcription factors and squamosa promoter-binding-like proteins, which suggests that these miRNAs may regulate stress-responsive transcriptional processes in tea plant. The present findings provide novel insights into miRNA-mediated regulatory mechanisms underlying the response to GA stress, and also offer valuable information for development of pest resistance using RNA interference-based strategies in tea plants.

MiR-449a regulates caprine endometrial stromal cell apoptosis and endometrial receptivity

In this study, an RT-qPCR analysis showed that the expression levels of miR-449a in the pre-receptive endometrium were lower compared to the receptive endometrium, which is consistent with previous sequencing data (previous investigations). To detect the role of miR-449a in endometrial receptivity, we transfected caprine endometrial stromal cells (ESCs) cultured in vitro with miR-449a mimics. The results revealed that miR-449a decreased the mRNA and protein levels of LGR4 by targeting its 3′-untranslated region. The miR-449a mimics significantly reduced the G₁ cell population from 52.56% (mimic NC) to 42.19% with a concordant increase in the G₂ and S cell populations from 47.44% (mimic NC) to 57.81%, suggesting that miR-449a caused ESC cell cycle arrest. In addition, the number of apoptotic cells was significantly higher in ESCs transfected with miR-449a mimics (P < 0.05) than in ESCs transfected with mimic NC. In vivo, rich pinopodes were observed on the endometrial surface in the miR-449a agomir group compared with the miR-449a antagomir group. The results of hematoxylin-eosin staining showed that endometrial thickness was significantly increased in the miR-449a agomir group compared with the miR-449a antagomir group. These results suggest that miR-449a could enhance endometrial receptivity.

miR-182 aids in receptive endometrium development in dairy goats by down-regulating PTN expression

Increasing evidence has shown that miRNAs play important roles in endometrium development during the menstrual cycle in humans and many other animals. Our previous data indicated that miR-182 levels increase 15.55-fold and pleiotrophin (PTN) levels decrease 20.97-fold in the receptive endometrium (RE, D15) compared with the pre-receptive endometrium (PE, D5) in dairy goats. The present study shows that miR-182 is widely expressed in different tissues of dairy goats and that its expression levels are regulated by E2 and P4 in endometrial epithelium cells (EECs). We confirmed that PTN is a target of miR-182 and that miR-182 regulates the protein levels of AKT, Bcl-2, FAS, MAPK, Caspase-3 and SP1 in EECs. Furthermore, miR-182 up-regulates or maintains the expression levels of osteopontin (OPN), cyclooxygenase-2 (COX-2) and prolactin receptor (PRLR) in EECs, suggesting that miR-182 is an important regulatory factor in the construction of endometrial receptivity in dairy goats. In conclusion, miR-182 participates in the development of endometrial receptivity by down-regulating PTN and affecting the expression of select apoptosis-related genes and increasing or maintaining the expression levels of OPN, COX-2 and PRLR in the EECs of dairy goats.

Effect of dietary Astragalus Polysaccharide supplements on testicular miRNA expression profiles and enzymatic changes of breeder cocks

Astragalus Polysaccharide (APS) is an important feed additive due to its immunomodulatory functions. Previous studies have proven that miRNAs play important roles in posttranscriptional gene regulation. Our goals were to identify differentially expressed miRNAs in testes in responses to APS dietary supplements and to find the effects of APS on breeder cock testes. We measured several enzymatic activities in testes and sperm samples and further generated miRNA expression profiles of testes from breeder cocks fed with control diets and extra APS. As a result, we found APS could increase testicular functional activities of marker enzymes. Meanwhile, there were 16 up-regulated and 17 down-regulated miRNAs in APS group, compared with the control group meeting the criteria of P-values < 0.05. Meanwhile, twelve differentially expressed miRNAs were validated by Mir-XTM miRNA RT-qPCR. Further GO and KEGG analyses of target genes for differentially expressed miRNAs revealed that some miRNAs may be involved in testicular nutrient metabolisms and NK cell mediated cytotoxicity pathway. Moreover, the effect of dietary APS supplements on NK cell mediated cytotoxicity pathway was also validated by RT-qPCR. Our results provided a novel insight into the effect of dietary APS supplements on testicular miRNA expression profiles and enzymatic changes of breeder cocks.

Systematic Identification and Bioinformatic Analysis of MicroRNAs in Response to Infections of Coxsackievirus A16 and Enterovirus 71

Hand, foot, and mouth disease (HFMD), mainly caused by coxsackievirus A16 (CVA16) and enterovirus 71 (EV71) infections, remains a serious public health issue with thousands of newly diagnostic cases each year since 2008 in China. The mechanisms underlying viral infection, however, are elusive to date. In the present study, we systematically investigated the host cellular microRNA (miRNA) expression patterns in response to CVA16 and EV71 infections. Through microarray examination, 27 miRNAs (15 upregulated and 12 downregulated) were found to be coassociated with the replication process of two viruses, while the expression levels of 15 and 5 miRNAs were significantly changed in CVA16- and EV71-infected cells, respectively. A great number of target genes of 27 common differentially expressed miRNAs were predicted by combined use of two computational target prediction algorithms, TargetScan and MiRanda. Comprehensive bioinformatic analysis of target genes in GO categories and KEGG pathways indicated the involvement of diverse biological functions and signaling pathways during viral infection. These results provide an overview of the roles of miRNAs in virus-host interaction, which will contribute to further understanding of HFMD pathological mechanisms.

Identification and Characterization of Liver MicroRNAs of the Chinese Tree Shrew via Deep Sequencing

BACKGROUND

Chinese tree shrew (Tupaia belangeri chinensis) is a small animal that possess many features, which are valuable in biomedical research, as experimental models. Currently, there are numerous attempts to utilize tree shrews as models for hepatitis C virus (HCV) infection.

OBJECTIVES

This study aimed to construct a liver microRNA (miRNA) data of the tree shrew.

MATERIALS AND METHODS

Three second filial generation tree shrews were used in this study. Total RNA was extracted from each liver of the tree shrew and equal quality mixed, then reverse-transcribed to complementary DNA (cDNA). The cDNAs were amplified by polymerase chain reaction and subjected to high-throughput sequencing.

RESULTS

A total of 2060 conserved miRNAs were identified through alignment with the mature miRNAs in miRBase 20.0 database. The gene ontology and Kyoto encyclopedia of genes and genomes analyses of the target genes of the miRNAs revealed several candidate miRNAs, genes and pathways that may involve in the process of HCV infection. The abundance of miR-122 and Let-7 families and their other characteristics provided us more evidences for the utilization of this animal, as a potential model for HCV infection and other related biomedical research. Moreover, 80 novel microRNAs were predicted using the software Mireap. The top 3 abundant miRNAs were validated in other tree samples, based on stem-loop quantitative reverse transcription-polymerase chain reaction.

CONCLUSIONS

According to the liver microRNA data of Chinese tree shrew, characteristics of the miR-122 and Let-7 families further highlight the suitability of tree shrew as the animal model in HCV research.