SOX9 regulates microRNA miR-202-5p/3p expression during mouse testis differentiation

MicroRNA as Biomarkers for Physiological and Stress Processing in the Livestock

Several microRNAs (miRNAs) have been identified as potential biomarkers widely dispersed in animals since 1993, and they have become a significant molecular biology research area. Because of their ability to activate extracellular molecules, stabilise bodily tissues, control cell-to-cell signals, and be easily extracted, miRNAs are outstandingly nominated as biomarkers. However, there is growing interest in targeting miRNAs to monitor physiological reproductive performance, including reproductive system development, embryo development, fertilisation, endocrinology, and animal welfare in stressful conditions. Moreover, miRNAs play significant roles in gene expression regulation; single miRNAs may have overlapping roles, and on a broader scale, multiple mRNAs govern a single function. Also, miRNAs serve as an intermediary messenger between the environment and reproductive performance, making them a vital component of miRNAs as performance biomarkers under environmental conditions like heat stress. This makes describing a unique miRNA's consequences and functions exceptionally challenging, which may confound many researchers. Also, enhancing our comprehension of miRNAs in response to testicular heat stress could potentially aid in preventing and treating spermatogenesis disorders. Therefore, the present review highlights miRNA's regulatory mechanisms on reproductive performance under heat stress to employ these findings in improving reproduction physiology research.

Decoding the epigenetic mechanism of mammalian sex determination

Sex determination embodies a dynamic and intricate developmental process wielding significant influence over the destiny of bipotential gonads, steering them towards male or female gonads. Gonadal differentiation and the postnatal manifestation of the gonadal phenotype involve a sophisticated interplay of transcription factors such as SOX9 and FOXL2. Central to this interplay are chromatin modifiers regulating the mutual antagonism during this interplay. In this review, the key findings and knowledge gaps in DNA methylation, histone modification, and non-coding RNA-mediated control throughout mammalian gonadal development are covered. Furthermore, it explores the role of the developing brain in playing a pivotal role in the initiation of gonadogenesis and the subsequent involvement of gonadal hormone/hormone receptor in fine-tuning sexual differentiation. Based on promising facts, the role of the developing brain through the hypothalamic pituitary gonadal axis is explained and suggested as a novel hypothesis. The article also discusses the potential impact of ecological factors on the human epigenome in relation to sex determination and trans-generational epigenetics in uncovering novel genes and mechanisms involved in sex determination and gonadal differentiation. We have subtly emphasized the disruptions in epigenetic regulations contributing to sexual disorders, which further allows us to raise certain questions, decipher approaches for handling these questions and setting up the direction of future research.

A medaka gonad-specific lncRNA may act as pri-miR-202 to regulate testicular endocrine homeostasis and spermatogenesis

A large number of long non-coding RNAs (lncRNAs) are expressed in animal gonads, but their functions are poorly understood. In this study, a gonad-specific lncRNA, termed lnc4, was identified and characterized in the model fish medaka (Oryzias latipes). The expression pattern and in vitro functional analyses indicated that lnc4 was likely to be a primary transcript of miR-202 (pri-miR-202). Results of single-molecule fluorescence in situ hybridization demonstrated that the precursor miR-202 (pre-miR-202) was highly expressed in the nuclei of testicular somatic cells, including Leydig and Sertoli cells, whereas only a small amount of lnc4 molecules could be detected co-expressed with pre-miR-202 in Sertoli cells due to its low expression level. Deletion of the lnc4 locus led to a significant reduction in testis size and a dramatic decrease in the number of male germ cells, as well as a reduction in sperm viability. Moreover, lnc4 knockout resulted in enhanced synthesis and secretion of testicular somatic cells and accelerated differentiation of immature male germ cells. Taken together, functional studies of lnc4 and its mature transcript miR-202 will contribute to the understanding of the important role of non-coding RNAs in animal or human reproductive disorders.

MiR-202-5p Regulates Geese Follicular Selection by Targeting BTBD10 to Regulate Granulosa Cell Proliferation and Apoptosis

The regulation of granulosa cells (GCs) proliferation and apoptosis is the key step in follicular selection which determines the egg production performance of poultry. miR-202-5p has been reported to be involved in regulating the proliferation and apoptosis of mammalian ovarian GCs. However, its role in regulating the proliferation and apoptosis of goose GCs is still unknown. In the present study, the GCs of pre-hierarchical follicles (phGCs, 8-10 mm) and those of hierarchical follicles (hGCs, F2-F4) were used to investigate the role of miR-202-5p in cell proliferation and apoptosis during follicle selection. In phGCs and hGCs cultured in vitro, miR-202-5p was found to negatively regulate cell proliferation and positively regulate cell apoptosis. The results of RNA-seq showed that BTB Domain Containing 10 (BTBD10) is predicted to be a key target gene for miR-202-5p to regulate the proliferation and apoptosis of GCs. Furthermore, it is confirmed that miR-202-5p can inhibit BTBD10 expression by targeting its 3'UTR region, and BTBD10 was revealed to promote the proliferation and inhibit the apoptosis of phGCs and hGCs. Additionally, co-transfection with BTBD10 effectively prevented miR-202-5p mimic-induced cell apoptosis and the inhibition of cell proliferation. Meanwhile, miR-202-5p also remarkably inhibited the expression of Phosphatidylinositol-4,5-Bisphosphate 3-Kinase Catalytic Subunit Beta (PIK3CB) and AKT Serine/Threonine Kinase 1 (AKT1), while it was significantly restored by BTBD10. Overall, miR-202-5p suppresses the proliferation and promotes the apoptosis of GCs through the downregulation of PIK3CB/AKT1 signaling by targeting BTBD10 during follicular selection. Our study provides a theoretical reference for understanding the molecular mechanism of goose follicular selection, as well as a candidate gene for molecular marker-assisted breeding to improve the geese' egg production performance.

Circulating microRNAs as promising testicular translatable safety biomarkers: current state and future perspectives

Drug-induced testicular injury (DITI) is one of the often-observed and challenging safety issues seen during drug development. Semen analysis and circulating hormones currently utilized have significant gaps in their ability to detect testicular damage accurately. In addition, no biomarkers enable a mechanistic understanding of the damage to the different regions of the testis, such as seminiferous tubules, Sertoli, and Leydig cells. MicroRNAs (miRNAs) are a class of non-coding RNAs that modulate gene expression post-transcriptionally and have been indicated to regulate a wide range of biological pathways. Circulating miRNAs can be measured in the body fluids due to tissue-specific cell injury/damage or toxicant exposure. Therefore, these circulating miRNAs have become attractive and promising non-invasive biomarkers for assessing drug-induced testicular injury, with several reports on their use as safety biomarkers for monitoring testicular damage in preclinical species. Leveraging emerging tools such as 'organs-on-chips' that can emulate the human organ's physiological environment and function is starting to enable biomarker discovery, validation, and clinical translation for regulatory qualification and implementation in drug development.

miR-450-5p and miR-202-5p Synergistically Regulate Follicle Development in Black Goat

Follicle maturation is a complex biological process governed by numerous factors, and researchers have observed follicle development by studying the proliferation and apoptosis of follicular granulosa cells (GCs). However, the regulatory mechanisms of GCs proliferation and death during follicle development are largely unknown. To investigate the regulatory mechanisms of lncRNAs, mRNAs, and microRNAs, RNA sequencing (RNA-seq) and small RNA-seq were performed on large (>10 mm) and small follicles (<3 mm) of Leizhou black goat during estrus. We discovered two microRNAs, miR-450-5p and miR-202-5p, which can target GCs in goats and may be involved in follicle maturation, and the effects of miR-450-5p and miR-202-5p on ovarian granulosa cell lines were investigated (KGN). Using cell counting kit-8 (CCK-8) assays, 5-Ethynyl-2’-deoxyuridine (EdU) assay and flow cytometry, miR-202-5p overexpression could suppress the proliferation and induce apoptosis of GCs, whereas miR-450-5p overexpression induced the opposite effects. The dual-luciferase reporter assay confirmed that miR-450-5p could directly target the BMF gene (a BCL2 modifying factor), and miR-202-5p targeted the BCL2 gene. A considerable rise in phosphorylated Akt (p-AKT) protein was observed following the downregulation of BMF by miR-450-5p mimics. After BMF gene RNAi therapy, a notable elevation in p-AKT was detected. Mimics of miR-202-5p inhibited BCL2 protein expression, significantly decreasing p-AMPK protein expression. These results imply that during the follicular development in black goats, the miR-450-5p-BMF axis favored GC proliferation on a wide scale, while the miR-202-5p-BCL2 axis triggered GC apoptosis.

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

Background

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

Results

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

Conclusions

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

Supplementary Information

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

Localisation and in silico based functional analysis of miR-202 in bull testis

Bull fertility is pivotal to the prosperity of the cattle industry worldwide. miR‐202 has been shown to be gonad specific and to have key roles in gonad function in different species. To further understand the involvement of miR‐202 in bull reproduction, this study aimed to establish its localization in bovine testicular tissue and to identify putative biological functions using bioinformatics approaches. We assessed the miR‐202 expression in paraffin‐embedded tissue samples collected form an abattoir using in situ hybridization. miR‐202 was present in Sertoli cells and in germ cells at different stages of development. Using available databases, a total of 466 predicted gene targets of miR‐202 were identified. Functional annotation revealed that miR‐202 target genes were mainly associated with protein modification and phosphorylation processes as well as longevity regulating pathway. Moreover, genes in the longevity regulating pathway mapped to PI3K/Akt/mTOR pathway which is involved in promoting proliferation of testicular cells and spermatogenesis. These findings suggest that miR‐202 plays important roles in regulating proliferation and viability of testicular cells including somatic and germ cells.

Integrated analysis of the miRNA and mRNA expression profiles in Leiocassis longirostris at gonadal maturation

Leiocassis longirostris is a commercially important fish species that shows a sexually dimorphic growth pattern. A lack of molecular data from the gonads of this species has hindered research and selective breeding efforts. In this study, we conducted a comprehensive analysis of the expression profile of miRNA and mRNA to explore their regulatory roles in the gonadal maturation stage of L. longirostris. We identified 60 differentially expressed miRNAs and 20,752 differentially expressed genes by sequencing. A total of 90 miRNAs and 21 target genes involved in gonad development and sex determination were identified. Overall, the results of this study enhance our understanding of the molecular mechanisms underlying sex determination and differentiation and provide valuable genomic information for the selective breeding of L. longirostris.

Coding and regulatory transcriptome comparisons between fertile and infertile spermatozoa identify RNA signatures of male infertility

The aim of the present study was to identify RNA-based signatures of male infertility by sperm transcriptome analysis. In this study, deep sequencing analyses of coding (mRNA) and regulatory (miRNA) transcriptomes were performed by pooling 15 oligo/oligoasthenozoospermic infertile sperm and 9 normozoospermic fertile sperm samples. Furthermore, interesting candidates were selected for validation by real-time PCR. The comparison of miRNAs between cases and controls identified 94 differentially expressed miRNAs, of which at least 38 have known functions in spermatogenesis. In transcriptome (mRNA) data, a total of 60,505 transcripts were obtained. The comparison of coding RNAs between cases and controls revealed 11,688 differentially expressed genes. miRNA-mRNA paired analysis revealed that 94 differentially expressed miRNAs could potentially target 13,573 genes, of which 6419 transcripts were actually differentially expressed in our data. Out of these, 3303 transcripts showed inverse correlation with their corresponding regulatory miRNAs. Moreover, we found that most of the genes of miRNA-mRNA pairs were involved in male germ cell differentiation, apoptosis, meiosis, spermiogenesis and male infertility. In conclusion, we found that a number of sperm transcripts (miRNAs and mRNAs) have a very high potential of serving as infertility/sperm quality markers.

Non-Epithelial Ovarian Cancers: How Much Do We Really Know?

Non-epithelial ovarian cancers (NEOC) are a group of uncommon malignancies that mainly includes germ cell tumours (GCT), sex cord-stromal tumours (SCST), and some extremely rare tumours, such as small cell carcinomas and sarcomas. Each of these classifications encompasses multiple histologic subtypes. The aetiology and molecular origins of each sub-group of NEOC require further investigation, and our understanding on the genetic changes should be optimised. In this article, we provide an update on the clinical presentation, pathology, genetics, treatment and survival of the main histological subtypes of the GCT and the SCST, as well as of ovarian small cell carcinomas. We also discuss miRNA expression profiles of NEOC and report the currently active clinical trials that include NEOC.

Comparison of MicroRNA Profiles in Extracellular Vesicles from Small and Large Goat Follicular Fluid

Simple Summary

Ovarian follicular development is associated with ovulation and is further related to litter size in goats. Extracellular vesicles (EVs) derived from miRNAs within follicular fluid undergo dynamic changes, and, together with follicle growth, may be considered as potential regulators of follicular development. However, the function and changes in EVs remain ambiguous. Here, we identified miRNA changes in EVs from small to large goat follicular fluid. Using bioinformatics tools, we demonstrated the existence of differentially expressed miRNAs in EVs from follicles of different sizes that are responsible for an altered biological effect. This study contributes to a better understanding of follicular development in goats.

Abstract

Extracellular vesicles (EVs), which exist in the follicular fluid of ruminant ovaries, are considered as cargo carriers for the transfer of biomolecules to recipient cells. However, the functions and changes in EVs in antral follicles remain ambiguous. In the present study, we isolated and characterized EVs from goat follicular fluid by means of differential ultracentrifugation and Western blotting of marker proteins. Bioinformatics tools were used to detect miRNA expression levels in EVs. Different miRNA expression patterns of EVs exist in small to large follicles. Thirteen differentially expressed miRNAs (seven upregulated and six downregulated) were identified and used for analysis. A total of 1948 predicted target genes of 13 miRNAs were mapped to signaling pathways, and three significantly enriched pathways (FoxO, MAPK, and PI3K-AKT signaling pathways) were involved in follicular development, as revealed by KEGG enrichment analysis. Our findings suggest that EVs in follicular fluid play biofunctional roles during follicular development in goats.

Proper Balance of Small GTPase rab10 Is Critical for PGC Migration in Zebrafish

MicroRNAs (miRNAs) play important roles in post-transcriptional repression in nearly every biological process including germ cell development. Previously, we have identified a zebrafish germ plasm-specific miRNA miR-202-5p, which regulates PGC migration through targeting cdc42se1 to protect cdc42 expression. However, knockdown of cdc42se1 could not significantly rescue PGC migration in maternal miR-202 mutant (MmiR-202) embryos, indicating that there are other target genes of miR-202-5p required for the regulation of PGC migration. Herein, we revealed the transcriptional profiles of wild type and MmiR-202 PGCs and obtained 129 differentially expressed genes (DEGs), of which 42 DEGs were enriched cell migration-related signaling pathways. From these DEGs, we identified two novel miR-202-5p target genes prdm12b and rab10. Furthermore, we found that disruption of rab10 expression led to significantly migratory defects of PGC by overexpression of rab10 siRNA, or WT, inactive as well as active forms of rab10 mRNA, and WT rab10 overexpression mediated migratory defects could be partially but significantly rescued by overexpression of miR-202-5p, demonstrating that rab10 is an important factor involved miR-202-5p mediated regulation of PGC migration. Taken together, the present results provide significant information for understanding the molecular mechanism by which miR-202-5p regulates PGC migration in zebrafish.

Non-Coding RNAs: lncRNAs, miRNAs, and piRNAs in Sexual Development

Non-coding RNAs (ncRNAs) are a group of RNAs that do not encode functional proteins, including long non-coding RNAs (lncRNAs), microRNAs (miRNAs), PIWI-interacting RNAs (piRNAs), and short interfering RNAs (siRNAs). In the last 2 decades an effort has been made to uncover the role of ncRNAs during development and disease, and nowadays it is clear that these molecules have a regulatory function in many of the developmental and physiological processes where they have been studied. In this review, we provide an overview of the role of ncRNAs during gonad determination and development, focusing mainly on mammals, although we also provide information from other species, in particular when there is not much information on the function of particular types of ncRNAs during mammalian sexual development.

GH Overexpression Alters Spermatic Cells MicroRNAome Profile in Transgenic Zebrafish

Overexpression of growth hormone (GH) in gh-transgenic zebrafish of a highly studied lineage F0104 has earlier been reported to cause increased muscle growth. In addition to this, GH affects a broad range of cellular processes in transgenic fish, such as morphology, physiology, and behavior. Reports show changes such as decreased sperm quality and reduced reproductive performance in transgenic males. It is hypothesized that microRNAs are directly involved in the regulation of fertility potential during spermatogenesis. The primary aim of our study was to verify whether gh overexpression disturbs the sperm miRNA profile and influences the sperm quality in transgenic zebrafish. We report a significant increase in body weight of gh-transgenic males along with associated reduced sperm motility and other kinetic parameters in comparison to the non-transgenic group. MicroRNA transcriptome sequencing of gh-transgenic zebrafish sperms revealed expressions of 186 miRNAs, among which six miRNA were up-regulated (miR-146b, miR-200a-5p, miR-146a, miR-726, miR-184, and miR-738) and sixteen were down-regulated (miR-19d-3p, miR-126a-5p, miR-126b-5p, miR-22a-5p, miR-16c-5p, miR-20a-5p, miR-126b-3p, miR-107a-3p, miR-93, miR-2189, miR-202–5p, miR-221–3p, miR-125a, miR-125b-5p, miR-126a-3p, and miR-30c-5p) in comparison to non-transgenic zebrafish. Some of the dysregulated miRNAs were previously reported to be related to abnormalities in sperm quality and reduced reproduction ability in other species. In this study, an average of 134 differentially expressed miRNAs-targeted genes were predicted using the in silico approach. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis demonstrated that the genes of affected pathways were primarily related to spermatogenesis, sperm motility, and cell apoptosis. Our results suggested that excess GH caused a detrimental effect on sperm microRNAome, consequently reducing the sperm quality and reproductive potential of zebrafish males.

Evolution after Whole-Genome Duplication: Teleost MicroRNAs

MicroRNAs (miRNAs) are important gene expression regulators implicated in many biological processes, but we lack a global understanding of how miRNA genes evolve and contribute to developmental canalization and phenotypic diversification. Whole-genome duplication events likely provide a substrate for species divergence and phenotypic change by increasing gene numbers and relaxing evolutionary pressures. To understand the consequences of genome duplication on miRNA evolution, we studied miRNA genes following the teleost genome duplication (TGD). Analysis of miRNA genes in four teleosts and in spotted gar, whose lineage diverged before the TGD, revealed that miRNA genes were retained in ohnologous pairs more frequently than protein-coding genes, and that gene losses occurred rapidly after the TGD. Genomic context influenced retention rates, with clustered miRNA genes retained more often than nonclustered miRNA genes and intergenic miRNA genes retained more frequently than intragenic miRNA genes, which often shared the evolutionary fate of their protein-coding host. Expression analyses revealed both conserved and divergent expression patterns across species in line with miRNA functions in phenotypic canalization and diversification, respectively. Finally, major strands of miRNA genes experienced stronger purifying selection, especially in their seeds and 3'-complementary regions, compared with minor strands, which nonetheless also displayed evolutionary features compatible with constrained function. This study provides the first genome-wide, multispecies analysis of the mechanisms influencing metazoan miRNA evolution after whole-genome duplication.

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

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

MicroRNA expression profiles in the seminal plasma of nonobstructive azoospermia patients with different histopathologic patterns

OBJECTIVE

To investigate microRNA (miRNA) expression profiles in the seminal plasma of nonobstructive azoospermia (NOA) patients with different histopathologic patterns and evaluate potential noninvasive diagnostic biomarkers of NOA.

DESIGN

Sequencing and validation using quantitative reverse transcription polymerase chain reaction (qRT-PCR).

SETTING

Reproductive center and research institute.

PATIENT(S)

Thirteen patients with NOA (7 Sertoli cell-only syndrome [SCOS] and 6 hypospermatogenesis to spermatogenesis arrest [SA]) and 7 normal fertile controls for sequencing, six samples per group for validation; 54 patients with NOA (27 SCOS and 27 SA) and 19 normal fertile controls for large-sample qRT-PCR analysis.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

MicroRNA expression profiles in the seminal plasma of patients with NOA with different histopathologic patterns were assessed using high-throughput sequencing and validated using qRT-PCR.

RESULT(S)

There were 78 overexpressed and 132 underexpressed miRNAs in patients with SCOS and 32 up-regulated and 90 down-regulated miRNAs in patients with SA compared with fertile men with normozoospermia. Two down-regulated and one up-regulated miRNA were validated using qRT-PCR, which indicated that the qRT-PCR and sequencing results were basically consistent. Hsa-miR-34c-5p expression was significantly lower in the seminal plasma of patients with NOA than normal fertile controls. The area under the receiver operating characteristic curve(AUC) for hsa-miR-34c-5p was 0.979 and 0.987 in the seminal plasma of patients with SA and patients with SCOS, respectively, compared with normal fertile controls. The AUC was 0.799 for hsa-miR-34c-5p in the seminal plasma between patients with SA and patients with SCOS. Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis of differentially expressed miRNA target genes revealed that the Notch signaling pathway was one of the most abundant signaling pathways. The expression of Hes5, an effector of the Notch signaling pathway, was significantly higher in the seminal plasma of patients with NOA than normal fertile controls.

CONCLUSION(S)

MicroRNA expression profiles in seminal plasma were altered in patients with NOA compared with normal fertile controls. The profiles differed in patients with NOA with different pathologic patterns. We speculate that miR-34c-5p in seminal plasma could be a potential noninvasive biomarker to diagnose patients with NOA and distinguish different pathologic types of NOA. The Notch signaling pathway may be involved in the pathogenesis of NOA.

Integrated mRNA and miRNA expression profile analysis of female and male gonads in Hyriopsis cumingii

Hyriopsis cumingii is an important species for freshwater pearl cultivation in China. In terms of pearl production, males have larger pearls and better glossiness than females, but there are few reports focusing on the sex of H. cumingii. In this study, six mRNA and six microRNA (miRNA) libraries were prepared from ovaries and testes. Additionally, 28,502 differentially expressed genes (DEGs) and 32 differentially expressed miRNAs (DEMs) were identified. Compared with testis, 14,360 mRNAs and 20 miRNAs were up-regulated in ovary, 14,142 mRNAs and 12 miRNAs were down-regulated. In DEGs, the known genes related to sex determinism and/or differentiation were also identified, such as DMRT1, SOX9, SF1 for males, FOXL2 for females, and other potentially significant candidate genes. Three sex-related pathways have also been identified, which are Wnt, Notch, and TGF-beta. In 32 DEMs, the three miRNAs (miR-9-5p, miR-92, miR-184) were paid more attention, they predicted 28 target genes, which may also be candidates for sex-related miRNAs and genes. Differential miRNAs target genes analysis reveals the pathway associated with oocyte meiosis and spermatogenesis. Overall, the findings of the study provide significant insights to enhance our understanding of sex differentiation and/or sex determination mechanisms for H. cumingii.

Profiling of miRNAs in porcine Sertoli cells

Background

Sertoli cells (SCs) create a specialized environment to support and dictate spermatogenesis. MicroRNAs (miRNAs), a kind of ~ 22 nt small noncoding RNAs, have been reported to be highly abundant in mouse SCs and play critical roles in spermatogenesis. However, the miRNAs of porcine SCs remain largely unknown.

Methods

We isolated porcine SCs and conducted small RNA sequencing. By comparing miRNAs in germ cells, we systematically analyzed the miRNA expression pattern of porcine SCs. We screened the highly enriched SC miRNAs and predicted their functions by Gene Ontology analysis. The dual luciferase assay was used to elucidate the regulation of tumor necrosis factor receptor (TNFR)-associated factor 3 (TRAF3) by ssc-miR-149.

Results

The analysis showed that 18 miRNAs were highly expressed in SCs and 15 miRNAs were highly expressed in germ cells. These miRNAs were predicted to mediate SC and germ cell functions. In addition, ssc-miR-149 played critical roles in SCs by targeting TRAF3.

Conclusion

Our findings provide novel insights into the miRNA expression pattern and their regulatory roles of porcine SCs.

Maternal miR-202-5p is required for zebrafish primordial germ cell migration by protecting small GTPase Cdc42

In many lower animals, germ cell formation, migration, and maintenance depend on maternally provided determinants in germ plasm. In zebrafish, these processes have been extensively studied in terms of RNA-binding proteins and other coding genes. The role of small non-coding RNAs in the regulation of primordial germ cell (PGC) development remains largely unknown and poorly investigated, even though growing interests for the importance of miRNAs involved in a wide variety of biological processes. Here, we reported the role and mechanism of the germ plasm-specific miRNA miR-202-5p in PGC migration: (i) both maternal loss and knockdown of miR-202-5p impaired PGC migration indicated by the mislocalization and reduced number of PGCs; (ii) cdc42se1 was a direct target gene of miR-202-5p, and overexpression of Cdc42se1 in PGCs caused PGC migration defects similar to those observed in loss of miR-202-5p mutants; (iii) Cdc42se1 not only interacted with Cdc42 but also inhibited cdc42 transcription, and overexpression of Cdc42 could rescue PGC migration defects in Cdc42se1 overexpressed embryos. Thus, miR-202-5p regulates PGC migration by directly targeting and repressing Cdc42se1 to protect the expression of Cdc42, which interacts with actin to direct PGC migration.

An integrated analysis of testis miRNA and mRNA transcriptome reveals important functional miRNA-targets in reproduction traits of roosters

The reproductive efficiency of roosters is an important trait in poultry production; however, the molecular mechanisms underlying this trait are not clearly understood. Here, we compared the mRNA and microRNA (miRNA) transcriptomes of testis from roosters with divergent sperm motility. A total of 302 differentially expressed genes (DEGs), including 182 upregulated genes and 120 downregulated genes, were identified in high sperm motility groups compared with low sperm motility groups. A subset of these DEGs related to steroid hormone biosynthesis and thus could be important for spermatogenesis. Additionally, we detected 13 differentially expressed miRNAs (DEMs) between two groups, and target gene prediction indicated seven of these could be associated with spermatogenesis. Based on a comprehensive analysis of these transcriptomes, miRNA-mRNA interaction networks were constructed. Six DEGs were predicted to be regulated by DEMs. Subsequently, we validated the negative regulation of family with sequence similarity 84, member A (FAM84A) by miR-215 using a dual-luciferase reporter system. These results provide new insights into the molecular profile of the testis and identify genes that may determine sperm motility in chickens.

Blood microRNA 202-3p associates with the risk of essential hypertension by targeting soluble ST2

MicroRNA (miR)-202-3p has attracted a great deal of attention in the fields of oncology, gynecology, and metabolic disorders. However, its role in cardiovascular diseases remains to be clarified. We previously found that disruption of miR-202-3p mediated regulation of expression of soluble (s)ST2, a decoy receptor for interleukin (IL)-33, promotes essential hypertension (EH). In the present study, we first measured miR-202-3p expression levels in the blood of 182 EH cases and 159 healthy controls using TaqMan assays. miR-202-3p levels were shown to be significantly higher in EH cases than controls (fold change = 3.58, P<0.001). Logistic regression analysis revealed that higher miR-202-3p expression was associated with an increased occurrence of EH (adjusted odds ratio (OR): 1.57; 95% confidence interval (CI), 1.36-1.82; P<0.001). Addition of miR-202-3p to traditional risk factors showed an additive prediction value for EH. Further functional experiments indicated that miR-202-3p could be induced by angiotensin II (Ang II) and inhibited by Ang II-triggered soluble ST2 (sST2) expression in a negative feedback manner. Moreover, blood miR-202-3p levels were negatively correlated with sST2 expression in vivo. Our study shows that blood miR-202-3p levels were significantly associated with the occurrence of EH. These findings indicate that miR-202-3p exerts a protective role against EH by antagonizing the induction of sST2 by Ang II.

Heterogenic Origin of Micro RNAs in Atlantic Salmon (Salmo salar) Seminal Plasma

The origin and contribution of seminal plasma RNAs into the whole semen RNA repertoire are poorly known, frequently being overlooked or neglected. In this study, we used high-throughput sequencing and RT-qPCR to profile microRNA (miRNA) constituents in the whole semen, as well as in fractionated spermatozoa and seminal plasma of Atlantic salmon (Salmo salar). We found 85 differentially accumulated miRNAs between spermatozoa and the seminal plasma. We identified a number of seminal plasma-enriched and spermatozoa-enriched miRNAs. We localized the expression of some miRNAs in juvenile and mature testes. Two abundant miRNAs, miR-92a-3p and miR-202-5p, localized to both spermatogonia and somatic supporting cells in immature testis, and they were also highly abundant in somatic cells in mature testis. miR-15c-5p, miR-30d-5p, miR-93a-5p, and miR-730-5p were detected only in mature testis. miRs 92a-3p, 202-5p, 15c-5p, and 30d-5p were also detected in a juvenile ovary. The RT-qPCR experiment demonstrated lack of correlation in miRNA transcript levels in seminal plasma versus blood plasma. Our results indicate that salmon semen is rich in miRNAs, which are present in both spermatozoa and seminal plasma. Testicular-supporting somatic cells are likely the source of seminal plasma enrichment, whereas blood plasma is unlikely to contribute to the seminal plasma miRNA repertoire.

MiR-202-5p Inhibits RIG-I-Dependent Innate Immune Responses to RGNNV Infection by Targeting TRIM25 to Mediate RIG-I Ubiquitination

The RIG-I-like receptors (RLRs) signaling pathway is essential for inducing type I interferon (IFN) responses to viral infections. Meanwhile, it is also tightly regulated to prevent uncontrolled immune responses. Numerous studies have shown that microRNAs (miRNAs) are essential for the regulation of immune processes, however, the detailed molecular mechanism of miRNA regulating the RLRs signaling pathway remains to be elucidated. Here, our results showed that miR-202-5p was induced by red spotted grouper nervous necrosis virus (RGNNV) infection in zebrafish. Overexpression of miR-202-5p led to reduced expression of IFN 1 and its downstream antiviral genes, thus facilitating viral replication in vitro. In comparison, significantly enhanced levels of IFN 1 and antiviral genes and significantly low viral burden were observed in the miR-202-5p^-/- zebrafish compared to wild type zebrafish. Subsequently, zebrafish tripartite motif-containing protein 25 (zbTRIM25) was identified as a target of miR-202-5p in both zebrafish and humans. Ectopic expression of miR-202-5p suppressed zbTRIM25-mediated RLRs signaling pathway. Furthermore, we showed that miR-202-5p inhibited zbTRIM25-mediated zbRIG-I ubiquitination and activation of IFN production. In conclusion, we demonstrate that RGNNV-inducible miR-202-5p acts as a negative regulator of zbRIG-I-triggered antiviral innate response by targeting zbTRIM25. Our study reveals a novel mechanism for the evasion of the innate immune response controlled by RGNNV.

Transactivation of miR-202-5p by Steroidogenic Factor 1 (SF1) Induces Apoptosis in Goat Granulosa Cells by Targeting TGFβR2

MicroRNAs play key roles during ovary development, with emerging evidence suggesting that miR-202-5p is specifically expressed in female animal gonads. Granulosa cells (GCs) are somatic cells that are closely related to the development of female gametes in mammalian ovaries. However, the biological roles of miR-202-5p in GCs remain unknown. Here, we show that miR-202-5p is specifically expressed in GCs and accumulates in extracellular vesicles (EVs) from large growth follicles in goat ovaries. In vitro assays showed that miR-202-5p induced apoptosis and suppressed the proliferation of goat GCs. We further revealed that miR-202-5p is a functional miRNA that targets the transforming growth factor-beta type II receptor (TGFβR2). MiR-202-5p attenuated TGF-β/SMAD signaling through the degradation of TGFβR2 at both the mRNA and protein level, decreasing p-SMAD3 levels in GCs. Moreover, we verified that steroidogenic factor 1 (SF1) is a transcriptional factor that binds to the promoters of miR-202 and cytochrome P450 family 19 subfamily A member 1 (CYP19A1) through luciferase reporter and chromatin immunoprecipitation (ChIP) assays. That contributed to positive correlation between miR-202-5p and CYP19A1 expression and estradiol (E2) release. Furthermore, SF1 repressed TGFβR2 and p-SMAD3 levels in GCs through the transactivation of miR-202-5p. Taken together, these results suggest a mechanism by which miR-202-5p regulates canonical TGF-β/SMAD signaling through targeting TGFβR2 in GCs. This provides insight into the transcriptional regulation of miR-202 and CYP19A1 during goat ovarian follicular development.

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.

Functions and mechanism of noncoding RNA in the somatic cells of the testis

ncRNAs are involved in numerous biological processes by regulating gene expression and cell stability. Studies have shown that ncRNAs also contribute to spermatogenesis. Leydig cells (LCs) and Sertoli cells (SCs) are somatic cells of the testis that support spermatogenesis and are vital to male fertility. In this review, we summarized the findings from studies on ncRNAs in SCs and LCs. In SCs, ncRNAs play key roles in phagocytosis, immunoprotection and development of SCs. In LCs, ncRNAs are involved in steroidogenesis, in particular production of testosterone as well as development of LCs. Here, we discuss the possible target genes and functions of ncRNAs in both types of cells. These ncRNAs regulate the expression of target genes or mRNA coding sequence regions, resulting in a chain reaction that influences cell function. In addition, microRNAs, lncRNAs, piRNA-like RNAs (pilRNAs) and natural antisense transcripts (NATs) are discussed in this review. In summary, we suggest that these ncRNAs might act in coordination to control spermatogenesis and maintain the environmental homeostasis of the testis.

Identification and characterization of a specific 13-miRNA expression signature during follicle activation in the zebrafish ovary

Ovarian folliculogenesis is always of great interest in reproductive biology. However, the molecular mechanisms that control follicle development, particularly the early phase of follicle activation or recruitment, still remain poorly understood. In an attempt to decipher the gene networks and signaling pathways involved in such transition, we conducted a transcriptomic analysis (RNA-seq) on zebrafish primary growth (PG, stage I; inactive) and previtellogenic (PV, stage II; activated) follicles. A total of 118 unique microRNAs (miRNAs) (11 downregulated and 83 upregulated during PG/PV transition) and 56711 unique messenger RNAs (mRNAs) (1839 downregulated and 7243 upregulated during PG/PV transition) were identified. Real-time quantitative polymerase chain reaction analysis confirmed differential expression of 46 miRNAs from 66 candidates (66.67%). Among which, we chose to focus on 13 miRNAs (let-7a, -7b, -7c-5p, -7d-5p, -7h, -7i; miR-21, -23a-3p, -27c-3p, -107a-3p, -125b-5p, -145-3p, and -202-5p) that exhibited significant differential expression between PG and PV follicles (P ≤ 0.045*). With this 13-miRNA expression signature alone, PG follicles can be well differentiated from PV follicles by hierarchical clustering, suggesting their functional relevance during PG-to-PV transition. By overlaying predicted target genes and the differentially expressed mRNAs revealed by the RNA-seq analysis, especially those showing reciprocal miRNA-mRNA expression patterns, we shortlisted a panel of miRNA downstream targets for luciferase reporter validation. The reporter assay confirmed the interactions of let-7i:: atg4a (P = 0.01*), miR-202-5p::c23h20orf24 (P = 0.0004***), and miR-144-5p::ybx1 (P = 0.003**), implicating these potential miRNA-mRNA gene pairs in follicle activation during folliculogenesis. Our transcriptomic data analyses suggest that miRNA-mediated post-transcriptional control may represent an important mechanism underlying follicle activation.

Integrated mRNA and miRNA expression profile analyses reveal the potential roles of sex-biased miRNA-mRNA pairs in gonad tissues of the Chinese concave-eared torrent frog (Odorrana tormota)

The Chinese concave-eared torrent frog (Odorrana tormota) is typically sexually dimorphic. Females are significantly less common than males in the wild. Until now, the molecular mechanisms of reproduction and sex differentiation of frogs remain unclear. Here, we integrated mRNA and microRNA (miRNA) expression profiles to reveal the molecular mechanisms of reproduction and sex differentiation in O. tormota. We identified 234 differentially expressed miRNAs (DEMs) and 18,551 differentially expressed transcripts. Of these, 12,053 mRNAs and 64 miRNAs were upregulated in testes, and 6,498 mRNAs and 170 miRNAs were upregulated in ovaries. Integrated analysis of the miRNA and mRNA expression profiles predicted 75,602 potential miRNA-mRNA interaction sites, with 42,065 negative miRNA-mRNA interactions. We found 36 differentially expressed genes (DEGs) related to reproduction and sex differentiation, of which 15 DEGs formed 92 negative miRNA-mRNA interactions with 34 known DEMs. Thus, miRNAs may play other important roles in O. tormota. Furthermore, Gene Ontology enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analyses showed reproductive-related processes, such as the gonadotropinreleasing hormone signaling pathway and ovarian steroidogenesis. Based on functional annotation and the literature, the retinoic acid signaling pathway, the SOX9-AMH pathway, and the process of spermatogenesis may be involved in the molecular mechanisms of reproduction and sex differentiation in O. tormota, and may be regulated by miRNAs. The miRNA-mRNA pairs described may provide further understanding of the regulatory mechanisms associated with reproduction and sex differentiation, and the molecular mechanism of reproduction in O. tormota.

Upregulated lncRNA Gm2044 inhibits male germ cell development by acting as miR-202 host gene

Long non-coding RNAs (lncRNAs) have been found to participate in the regulation of human spermatogenic cell development. However, little is known about the abnormal expression of lncRNAs associated with spermatogenic failure and their molecular mechanisms. Using lncRNA microarray of testicular tissue for male infertility and bioinformatics methods, we identified the relatively conserved lncRNA Gm2044 which may play important roles in non-obstructive azoospermia. The UCSC Genome Browser showed that lncRNA Gm2044 is the miR-202 host gene. This study revealed that lncRNA Gm2044 and miR-202 were significantly increased in non-obstructive azoospermia of spermatogonial arrest. The mRNA and protein levels of Rbfox2, a known direct target gene of miR-202, were regulated by lncRNA Gm2044. Furthermore, the miR-202-Rbfox2 signalling pathway was shown to mediate the suppressive effects of lncRNA Gm2044 on the proliferation of human testicular embryonic carcinoma cells. Understanding of the molecular signalling pathways for lncRNA-regulated spermatogenesis will provide new clues into the pathogenesis and treatment of patients with male infertility.

miRNA analysis with Prost! reveals evolutionary conservation of organ-enriched expression and post-transcriptional modifications in three-spined stickleback and zebrafish

MicroRNAs (miRNAs) can have organ-specific expression and functions; they can originate from dedicated miRNA genes, from non-canonical miRNA genes, or from mirror-miRNA genes and can also experience post-transcriptional variation. It remains unclear, however, which mechanisms of miRNA production or modification are organ-specific and the extent of their evolutionary conservation. To address these issues, we developed the software Prost! (PRocessing Of Short Transcripts), which, among other features, helps quantify mature miRNAs, accounts for post-transcriptional processing, such as nucleotide editing, and identifies mirror-miRNAs. Here, we applied Prost! to annotate and analyze miRNAs in three-spined stickleback (Gasterosteus aculeatus), a model fish for evolutionary biology reported to have a miRNome larger than most teleost fish. Zebrafish (Danio rerio), a distantly related teleost with a well-known miRNome, served as comparator. Our results provided evidence for the existence of 286 miRNA genes and 382 unique mature miRNAs (excluding mir430 gene duplicates and the vaultRNA-derived mir733), which doesn't represent a miRNAome larger than other teleost miRNomes. In addition, small RNA sequencing data from brain, heart, testis, and ovary in both stickleback and zebrafish identified suites of mature miRNAs that display organ-specific enrichment, many of which are evolutionarily-conserved in the brain and heart in both species. These data also supported the hypothesis that evolutionarily-conserved, organ-specific mechanisms may regulate post-transcriptional variations in miRNA sequence. In both stickleback and zebrafish, miR2188-5p was edited frequently with similar nucleotide changes in the seed sequence with organ specific editing rates, highest in the brain. In summary, Prost! is a new tool to identify and understand small RNAs, to help clarify a species' miRNA biology as shown here for an important model for the evolution of developmental mechanisms, and to provide insight into organ-enriched expression and the evolutionary conservation of miRNA post-transcriptional modifications.

Augmentation of miR-202 in varicose veins modulates phenotypic transition of vascular smooth muscle cells by targeting proliferator-activated receptor-γ coactivator-1α

In varicose veins, vascular smooth muscle cells (VSMCs) often show abnormal proliferative and migratory rates and phenotypic transition. This study aimed to investigate whether microRNA (miR)-202 and its potential target, peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), were involved in VSMC phenotypic transition. miR-202 expression was analyzed in varicose veins and in VSMCs conditioned with platelet-derived growth factor. The effect of miR-202 on cell proliferation and migration was assessed. Furthermore, contractile marker SM-22α, synthetic markers vimentin and collagen I, and PGC-1α were analyzed by Western blot analysis. The modulation of PGC-1α expression by miR-202 was also evaluated. In varicose veins and proliferative VSMCs, miR-202 expression was upregulated, with decreased SM-22α expression and increased vimentin and collagen I expression. Transfection with a miR-202 mimic induced VSMC proliferation and migration, whereas a miR-202 inhibitor reduced cell proliferation and migration. miR-202 mimic constrained luciferase activity in HEK293 cells that were cotransfected with the PGC-1α 3'-untranslated region (3'-UTR) but not those with mutated 3'-UTR. miR-202 suppressed PGC-1α protein expression, with no influence on its messenger RNA expression. PGC-1α mediated VSMC phenotypic transition and was correlated with reactive oxygen species production. In conclusion, miR-202 affects VSMC phenotypic transition by targeting PGC-1α expression, providing a novel target for varicose vein therapy.

MiR-202 controls female fecundity by regulating medaka oogenesis

Female gamete production relies on coordinated molecular and cellular processes that occur in the ovary throughout oogenesis. In fish, as in other vertebrates, these processes have been extensively studied both in terms of endocrine/paracrine regulation and protein expression and activity. The role of small non-coding RNAs in the regulation of animal reproduction remains however largely unknown and poorly investigated, despite a growing interest for the importance of miRNAs in a wide variety of biological processes. Here, we analyzed the role of miR-202, a miRNA predominantly expressed in male and female gonads in several vertebrate species. We studied its expression in the medaka ovary and generated a mutant line (using CRISPR/Cas9 genome editing) to determine its importance for reproductive success with special interest for egg production. Our results show that miR-202-5p is the most abundant mature form of the miRNA and that it is expressed in granulosa cells and in the unfertilized egg. The knock out (KO) of mir-202 gene resulted in a strong phenotype both in terms of number and quality of eggs produced. Mutant females exhibited either no egg production or produced a dramatically reduced number of eggs that could not be fertilized, ultimately leading to no reproductive success. We quantified the size distribution of the oocytes in the ovary of KO females and performed a large-scale transcriptomic analysis approach to identified dysregulated molecular pathways. Together, cellular and molecular analyses indicate that the lack of miR-202 impairs the early steps of oogenesis/folliculogenesis and decreases the number of large (i.e. vitellogenic) follicles, ultimately leading to dramatically reduced female fecundity. This study sheds new light on the regulatory mechanisms that control the early steps of follicular development, including possible targets of miR-202-5p, and provides the first in vivo functional evidence that a gonad-predominant microRNA may have a major role in female reproduction.

The role of small non-coding RNAs in the regulation of animal reproduction remains poorly investigated, despite a growing interest for the importance of miRNAs in a wide variety of biological processes. Here, we analyzed the role of miR-202, a miRNA predominantly expressed in gonads in vertebrate. We studied its expression in the medaka ovary and knocked out the mir-202 gene to study its importance for reproductive success. We showed that the lack of miR-202 results in the sterility of both females and males. In particular, it led to a drastic reduction of both the number and the quality of eggs produced by females. Mutant females exhibited either no egg production or produced a drastically reduced number of eggs that could not be fertilized, ultimately leading to no reproductive success. Quantitative histological and molecular analyses indicated that mir-202 KO impairs oocyte development and is also associated with the dysregulation of many genes that are critical for reproduction. This study sheds new light on the regulatory mechanisms that control oogenesis, including possible targets of miR-202-5p, and provides the first in vivo functional evidence that a gonad-predominant microRNA may have a major role in female reproduction.

Roles of microRNAs in mammalian reproduction: from the commitment of germ cells to peri-implantation embryos

MicroRNAs (miRNAs) are active regulators of numerous biological and physiological processes including most of the events of mammalian reproduction. Understanding the biological functions of miRNAs in the context of mammalian reproduction will allow a better and comparative understanding of fertility and sterility in male and female mammals. Herein, we summarize recent progress in miRNA‐mediated regulation of mammalian reproduction and highlight the significance of miRNAs in different aspects of mammalian reproduction including the biogenesis of germ cells, the functionality of reproductive organs, and the development of early embryos. Furthermore, we focus on the gene expression regulatory feedback loops involving hormones and miRNA expression to increase our understanding of germ cell commitment and the functioning of reproductive organs. Finally, we discuss the influence of miRNAs on male and female reproductive failure, and provide perspectives for future studies on this topic.

Identification and differential expression of microRNAs in testis and ovary of Amur sturgeon (Acipenser schrenckii)

BACKGROUND

MicroRNAs (miRNAs) cooperate with sex-related genes in post-transcriptional regulation and play extremely important roles in the establishment of sexually dimorphic traits in animals. However, the gonad miRNAs and expression patterns of miRNAs in sturgeon have not been investigated.

METHODS

In the present study, we used high-throughput small RNA sequencing (RNA-Seq) to discover gonad miRNAs from the ovaries and testes of Amur sturgeons (Acipenser schrenckii). Further, microarray and real-time PCR assays were performed to identify the expression patterns of gonad miRNAs.

RESULTS

As a result, a total of 679 conserved and 51 novel miRNAs were successfully discovered in the gonads of A. schrenckii. Moreover, we found wide sequence variations (isomiRs) in gonad miRNAs, including 5' and 3' isomiRs. Our microarray analysis further characterized the 730 miRNAs expression profiles, which indicated that 117 differentially expressed miRNAs were detected with sex-biased patterns: 71 testis-biased and 46 ovary-biased miRNAs. Based on bioinformatics prediction, we found that there were functional differences between the testis-biased and ovary-biased miRNA targets involved in reproductive-related GO and KEGG pathways. Further, the association of the differentially expressed miRNAs and sex-related target mRNAs was uncovered. Finally, the expression patterns of 11 sex-biased miRNAs and 7 sex-related targets were validated in testes and ovaries using real-time PCR. Putative, negatively expressed miRNA-mRNA relationships were confirmed, such as Dmrt1 and asc-miR-2779, AR and asc-miR-203b-3p, foxl2 and asc-miR-30d.

CONCLUSION

This study provides information regarding the gonad miRNAs in sturgeon. The differential expression miRNAs in the gonads will help us to further understand the role of miRNA-mediated post-transcriptional regulation in the ovary and testis of sturgeon.

MicroRNA dynamics at the onset of primordial germ and somatic cell sex differentiation during mouse embryonic gonad development

In mammals, commitment and specification of germ cell lines involves complex programs that include sex differentiation, control of proliferation, and meiotic initiation. Regulation of these processes is genetically controlled by fine-tuned mechanisms of gene regulation in which microRNAs (miRNAs) are involved. We have characterized, by small-RNA-seq and bioinformatics analyses, the miRNA expression patterns of male and female mouse primordial germ cells (PGCs) and gonadal somatic cells at embryonic stages E11.5, E12.5, and E13.5. Differential expression analyses revealed differences in the regulation of key miRNA clusters such as miR-199-214, miR-182-183-96, and miR-34c-5p, whose targets have defined roles during gonadal sexual determination in both germ and somatic cells. Extensive analyses of miRNA sequences revealed an increase in noncanonical isoforms on PGCs at E12.5 and dramatic changes of 3' isomiR expression and 3' nontemplate nucleotide additions in female PGCs at E13.5. Additionally, RT-qPCR analyses of genes encoding proteins involved in miRNA biogenesis and 3' nucleotide addition uncovered sexually and developmentally specific expression, characterized by the decay of Drosha, Dgcr8, and Xpo5 expression along gonadal development. These results demonstrate that miRNAs, their isomiRs, and miRNA machinery are differentially regulated and participate actively in gonadal sexual differentiation in both PGCs and gonadal somatic cells.

SOX9/miR-130a/CTR1 axis modulates DDP-resistance of cervical cancer cell

Cisplatin (DDP) -based chemotherapy is a standard strategy for cervical cancer, while chemoresistance remains a huge challenge. Copper transporter protein 1 (CTR1), a copper influx transporter required for high affinity copper (probably reduced Cu I) transport into the cell, reportedly promotes a significant fraction of DDP internalization in tumor cells. In the present study, we evaluated the function of CTR1 in the cell proliferation of cervical cancer upon DDP treatment. MicroRNAs (miRNAs) have been regarded as essential regulators of cell proliferation, apoptosis, migration, as well as chemoresistance. By using online tools, we screened for candidate miRNAs potentially regulate CTR1, among which miR-130a has been proved to promote cervical cancer cell proliferation through targeting PTEN in our previous study. In the present study, we investigated the role of miR-130a in cervical cancer chemoresistance to DDP, and confirmed the binding of miR-130a to CTR1. SOX9 also reportedly act on cancer chemoresistance. In the present study, we revealed that SOX9 inversely regulated miR-130a through direct targeting the promoter of miR-130a. Consistent with previous studies, SOX9 could affect cervical cancer chemoresistance to DDP. Taken together, we demonstrated a SOX9/miR-130a/CTR1 axis which modulated the chemoresistance of cervical cancer cell to DDP, and provided promising targets for dealing with the chemoresistance of cervical cancer.

Identification and expression analysis of microRNAs in medaka gonads

Gonad development is a highly regulated, coordinated biological process and increasing evidences have indicated that microRNA (miRNA) may be involved in this dynamic program. Medaka (Oryzias latipes) is a good model for reproductive research as it has distinct sex determining genes, however, research in gonadal miRNAs is lacked. In this study, two small RNA libraries from the ovaries and testes were constructed and sequenced. A total of 285 conserved and 388 novel miRNAs were obtained, among which 142 mature miRNAs were significantly (> two-fold change) up or down regulated in the testis compared to the ovary. Quantitative Reverse Transcription-Polymerase Chain Reaction (qRT-PCR) analysis showed that miR-430c, miR-26a and miR-202-5p were expressed in a gonad-specific or sex-biased pattern. Fluorescence in situ hybridization (FISH) indicated that miR-202-5p was present throughout spermatogenesis and was only detected at the early stages of oogenesis, this sex biased expression pattern suggested that miR-202-5p might be a crucial candidate in male differentiation and development. Our study provides the repertoire, a comprehensive annotation of miRNAs from gonads and a reference for functional studies of miRNAs in medaka.

MicroRNA expression profiles in non‑epithelial ovarian tumors

Ovarian germ cell tumors (OGCTs) and sex cord stromal tumors (SCSTs) are rare gynecologic tumors that are derived from germ and stromal cells, respectively. Unlike their epithelial counterparts, molecular pathogenesis of these tumor types is still poorly understood. Here, we characterized microRNA (miRNA) expression profiles of 9 OGCTs (2 malignant and 7 benign) and 3 SCSTs using small RNA sequencing. We observed significant miRNA expression variations among the three tumor groups. To further demonstrate the biological relevance of our findings, we selected 12 miRNAs for validation in an extended cohort of 16 OGCTs (9 benign and 7 malignant) and 7 SCSTs by reverse transcription-quantitative polymerase chain reaction. Higher expression of miR‑373‑3p, miR‑372‑3p and miR‑302c‑3p and lower expression of miR‑199a‑5p, miR‑214‑5p and miR‑202‑3p were reproducibly observed in malignant OGCTs as compared to benign OGCTs or SCSTs. Comparing with benign OGCTs, miR‑202c‑3p and miR‑513c‑5p were more abundant in SCSTs. Additionally, we examined Beclin 1 (BECN1), a target of miR‑199a‑5p, in the clinical samples using western blot analysis. Our results show that BECN1 expression was higher in malignant OGCTs than benign OGCTs, which is concordant with their lower miR‑199a‑5p expression. This study suggests that these miRNAs may have potential value as tumor markers and implications for further understanding the molecular basis of these tumor types.

The Role of Sequential BMP Signaling in Directing Human Embryonic Stem Cells to Bipotential Gonadal Cells

CONTEXT

Human gonads arise as a pair of epithelial ridges on the surface of intermediate mesoderm (IM)-derived mesonephros. Toxic environmental factors and mutations in various genes are known to disturb normal gonadal development, but because of a lack of suitable in vitro models, detailed studies characterizing the molecular basis of the observed defects have not been performed.

OBJECTIVE

To establish an in vitro method for studying differentiation of bipotential gonadal progenitors by using human embryonic stem cells (hESCs) and to investigate the role of bone morphogenetic protein (BMP) in gonadal differentiation.

DESIGN

We tested 17 protocols using activin A, CHIR-99021, and varying durations of BMP-7 and the BMP inhibitor dorsomorphin. Activation of activin A, WNT, and BMP pathways was optimized to induce differentiation.

SETTING

Academic research laboratory.

MAIN OUTCOMES MEASURES

Cell differentiation, gene expression, and flow cytometry.

RESULTS

The two most efficient protocols consistently upregulated IM markers LHX1, PAX2, and OSR1 at days 2 to 4 and bipotential gonadal markers EMX2, GATA4, WT1, and LHX9 at day 8 of culture. The outcome depended on the combination of the duration, concentration, and type of BMP activation and the length of WNT signaling. Adjusting any of the parameters substantially affected the requirements for other parameters.

CONCLUSIONS

We have established a reproducible protocol for directed differentiation of hESCs into bipotential gonadal cells. The protocol can be used to model early gonadal development in humans and allows further differentiation to mature gonadal somatic cells.

Sex Drives Dimorphic Immune Responses to Viral Infections

New attention to sexual dimorphism in normal mammalian physiology and disease has uncovered a previously unappreciated breadth of mechanisms by which females and males differentially exhibit quantitative phenotypes. Thus, in addition to the established modifying effects of hormones, which prenatally and postpubertally pattern cells and tissues in a sexually dimorphic fashion, sex differences are caused by extragonadal and dosage effects of genes encoded on sex chromosomes. Sex differences in immune responses, especially during autoimmunity, have been studied predominantly within the context of sex hormone effects. More recently, immune response genes have been localized to sex chromosomes themselves or found to be regulated by sex chromosome genes. Thus, understanding how sex impacts immunity requires the elucidation of complex interactions among sex hormones, sex chromosomes, and immune response genes. In this Brief Review, we discuss current knowledge and new insights into these intricate relationships in the context of viral infections.

MiR-202-5p is a novel germ plasm-specific microRNA in zebrafish

Gametogenesis is a complicated biological process by which sperm and egg are produced for genetic transmission between generations. In many animals, the germline is segregated from the somatic lineage in early embryonic development through the specification of primordial germ cells (PGCs), the precursors of gametes for reproduction and fertility. In some species, such as fruit fly and zebrafish, PGCs are determined by the maternally provided germ plasm which contains various RNAs and proteins. Here, we identified a germ plasm/PGC-specific microRNA miR-202-5p for the first time in zebrafish. MiR-202-5p was specifically expressed in gonad. In female, it was expressed and accumulated in oocytes during oogenesis. Quantitative reverse transcription PCR and whole mount in situ hybridization results indicated that miR-202-5p exhibited a typical germ plasm /PGC-specific expression pattern throughout embryogenesis, which was consistent with that of the PGC marker vasa, indicating that miR-202-5p was a component of germ plasm and a potential PGC marker in zebrafish. Our present study might be served as a foundation for further investigating the regulative roles of miRNAs in germ plasm formation and PGC development in zebrafish and other teleost.

Discovery of microRNAs during early spermatogenesis in chicken

Spermatogenesis is a complex process that involves many elements. However, until now, little is known at the molecular level about spermatogenesis in poultry. Here we investigated microRNAs and their target genes that may be involved in germ cell development and spermatogonial in chicken. We used next-generation sequencing to analyze miRNA expression profiles in three types of germline cells: primordial germ cells (PGCs), spermatogonial stem cells (SSCs), and spermatogonia (Sp) during early stage of spermatogenesis. After validated the candidate miRNAs and corresponding genes’ expression in three types of cells, we found 15 miRNAs that were enriched 21 target genes that may be involved in spermatogenesis. Among the enriched miRNAs, miR-202-5p/3p were up-regulated in the Sp library and down-regulated in the PGCs library. Through RT-qPCR and Dual-Luciferase reporter assay, we confirmed that miR-202-5p bind to LIMK2 and involved in germ cell development. Collectively, we firstly discover the novel miRNAs, like miR-202-5p, and its related genes and pathways, expressed during the early spermatogonial stage in chicken, which will provide new clues for deciphering the molecular mechanism of the miRNAs regulating germline stem cell differentiation and spermatogenesis in chicken.

The roles of microRNAs in regulation of mammalian spermatogenesis

Mammalian spermatogenesis contains three continuous and organized processes, by which spermatogonia undergo mitosis and differentiate to spermatocytes, follow on meiosis to form haploid spermatids and ultimately transform into spermatozoa. These processes require an accurately, spatially and temporally regulated gene expression patterns. The microRNAs are a novel class of post-transcriptional regulators. Cumulating evidences have demonstrated that microRNAs are expressed in a cell-specific or stage-specific manner during spermatogenesis. In this review, we focus on the roles of microRNAs in spermatogenesis. We highlight that N6-methyladenosine (m6A) is involved in the biogenesis of microRNAs and miRNA regulates the m6A modification on mRNA, and that specific miRNAs have been exploited as potential biomarkers for the male factor infertility, which will provide insightful understanding of microRNA roles in spermatogenesis.

miR-202 Diminishes TGFβ Receptors and Attenuates TGFβ1-Induced EMT in Pancreatic Cancer

Previous studies in our laboratory identified that 3-deazaneplanocin A (DZNep), a carbocyclic adenosine analog and histone methyl transferase inhibitor, suppresses TGFβ-induced epithelial-to-mesenchymal (EMT) characteristics. In addition, DZNep epigenetically reprograms miRNAs to regulate endogenous TGFβ1 levels via miR-663/4787-mediated RNA interference (Mol Cancer Res. 2016 Sep 13. pii: molcanres.0083.2016) (1). Although DZNep also attenuates exogenous TGFβ-induced EMT response, the mechanism of this inhibition was unclear. Here, DZNep induced miR-202-5p to target both TGFβ receptors, TGFBR1 and TGFBR2, for RNA interference and thereby contributes to the suppression of exogenous TGFβ-induced EMT in pancreatic cancer cells. Lentiviral overexpression of miR-202 significantly reduced the protein levels of both TGFβ receptors and suppressed TGFβ signaling and EMT phenotypic characteristics of cultured parenchymal pancreatic cancer cells. Consistently, transfection of anti-miRNAs against miR-202-5p resulted in increased TGFBR1 and TGFBR2 protein expressions and induced EMT characteristics in these cells. In stellate pancreatic cells, miR-202 overexpression slowed growth as well as reduced stromal extracellular membrane matrix protein expression. In orthotopic pancreatic cancer mouse models, both immunodeficient and immunocompetent, miR-202 reduced tumor burden and metastasis. Together, these findings demonstrate an alternative mechanism of DZNep in suppressing TGFβ signaling at the receptor level and uncover the EMT-suppressing role of miR-202 in pancreatic cancer.Implications: These findings support the possibility of combining small molecule-based (e.g., DZNep analogs) or large molecule-based (e.g., miRNAs) epigenetic modifiers with conventional nucleoside analogs (e.g., gemcitabine, capecitabine) to improve the antimetastatic potential of current pancreatic cancer therapy. Mol Cancer Res; 15(8); 1029-39. ©2017 AACR.