MiRNA-133b promotes the proliferation of human Sertoli cells through targeting GLI3

Identification of miR-34c-5p as a potential regulatory molecule associated with testicular development of black goat

The growth and maturation of Sertoli cells (SCs) are important part of testicular development and miRNAs are considered as novel regulatory molecules involved in it. Here we systematically screened and analyzed the key miRNAs participating in testicular development of black goat, as well as identified underlying mechanism of candidate mRNAs that contributed to spermatogenesis. The miRNA transcriptional profiles of testicular tissues at 3 days old (D3), 30 days old (D30), 90 days old (D90), and 180 days old (D180) were constructed and comparative analyzed. Results showed that the most differentially expressed (DE) miRNAs were found between the testicular tissues of D30 and D90 black goats. Moreover, the predicted target genes of DE miRNAs were mainly enriched in biological processes including cell proliferation, cell composition and enriched in signaling pathways including p53, FoxO, and PI3K-Akt. The top one DE miRNA (miR-34c-5p), which significantly highly expressed in the testis of D90 when compared to that of D30, was mainly located within SCs and targeted to IGF1R. By performing miR-34c-5p overexpression and RNA interference, we found that the function of miR-34c-5p in SCs was inhibited cell proliferation, increased apoptosis rate, and significantly reduced the expression of growth factors (CXCL12, BMP4, GDNF, and IGF1). In summary, our study suggests that miR-34c-5p can serve as a potential target for regulation of testicular development and a reference marker of puberty applied to black goat genetic breeding.

Exploring the Characters of Non-Coding RNAs in Spermatogenesis and Male Infertility

Infertility is a widespread clinical problem that affects human reproduction and species persistence worldwide. Around 40-70% of cases are due to male reproductive defects. Functional spermatogenesis (sperm production through several coordinated events) is at the heart of male fertility. Non-coding RNAs (ncRNAs) are the primary regulators of gene expression, controlling extensive critical cellular processes, for example proliferation, differentiation, apoptosis, and reproduction. Due to advancements in high-throughput sequencing tools, many studies have revealed that ncRNAs are widely expressed in germ cells, meiosis, spermatogenesis, sperm fertility, early post-fertilization development, and male infertility. The present review examines the biology and function of ncRNAs, including microRNAs, circular RNAs, and long ncRNAs, in spermatogenesis, their correlation with infertility, and their potential as biomarkers for sperm quality and fertility. The function of ncRNA in Sertoli cells (SCs) and Leydig cells (LCs) is also outlined throughout this study, because spermatogenesis requires testicular somatic cells to be involved in testicular development and male fertility. Meanwhile, the future development of ncRNAs for the clinical treatment of male infertility is also anticipated and discussed.

Characterization of sexual maturity-associated N6-methyladenosine in boar testes

BACKGROUND

The health and size of the testes are crucial for boar fertility. Testicular development is tightly regulated by epigenetics. N6-methyladenosine (m6A) modification is a prevalent internal modification on mRNA and plays an important role in development. The mRNA m6A methylation in boar testicular development still needs to be investigated.

RESULTS

Using the MeRIP-seq technique, we identify and profile m6A modification in boar testes between piglets and adults. The results showed 7783 distinct m6A peaks in piglets and 6590 distinct m6A peaks in adults, with 2,471 peaks shared between the two groups. Enrichment of GO and KEGG analysis reveal dynamic m6A methylation in various biological processes and signalling pathways. Meanwhile, we conjointly analyzed differentially methylated and expressed genes in boar testes before and after sexual maturity, and reproductive related genes (TLE4, TSSK3, TSSK6, C11ORF94, PATZ1, PHLPP1 and PAQR7) were identified. Functional enrichment analysis showed that differential genes are associated with important biological functions, including regulation of growth and development, regulation of metabolic processes and protein catabolic processes.

CONCLUSION

The results demonstrate that m6A methylation, differential expression and the related signalling pathways are crucial for boar testicular development. These results suggest a role for m6A modification in boar testicular development and provided a resource for future studies on m6A function in boar testicular development.

A Single-Cell Landscape of Spermioteleosis in Mice and Pigs

(1) Background: Spermatozoa acquired motility and matured in epididymis after production in the testis. However, there is still limited understanding of the specific characteristics of sperm development across different species. In this study, we employed a comprehensive approach to analyze cell compositions in both testicular and epididymal tissues, providing valuable insights into the changes occurring during meiosis and spermiogenesis in mouse and pig models. Additionally, we identified distinct gene expression signatures associated with various spermatogenic cell types. (2) Methods: To investigate the differences in spermatogenesis between mice and pigs, we constructed a single-cell RNA dataset. (3) Results: Our findings revealed notable differences in testicular cell clusters between these two species. Furthermore, distinct gene expression patterns were observed among epithelial cells from different regions of the epididymis. Interestingly, regional gene expression patterns were also identified within principal cell clusters of the mouse epididymis. Moreover, through analysing differentially expressed genes related to the epididymis in both mouse and pig models, we successfully identified potential marker genes associated with sperm development and maturation for each species studied. (4) Conclusions: This research presented a comprehensive single-cell landscape analysis of both testicular and epididymal tissues, shedding light on the intricate processes involved in spermatogenesis and sperm maturation, specifically within mouse and pig models.

MicroRNAs in Male Fertility

Around 50% of all occurrences of infertility are attributable to the male factor, which is a significant global public health concern. There are numerous circumstances that might interfere with spermatogenesis and cause the body to produce abnormal sperm. While evaluating sperm, the count, the speed at which they migrate, and their appearance are the three primary characteristics that are analyzed. MicroRNAs, also known as miRNAs, are present in all physiological fluids and tissues. They participate in both physiological and pathological processes. Researches have demonstrated that the expression of microRNA genes differs in infertile men. These genes regulate spermatogenesis at various stages and in several male reproductive cells. Hence, microRNAs have the potential to act as useful indicators in the diagnosis and treatment of male infertility and other diseases affecting male reproduction. Despite this, additional research is necessary to determine the precise miRNA regulation mechanisms.

MicroRNAs in spermatogenesis dysfunction and male infertility: clinical phenotypes, mechanisms and potential diagnostic biomarkers

Infertility affects approximately 10-15% of couples worldwide who are attempting to conceive, with male infertility accounting for 50% of infertility cases. Male infertility is related to various factors such as hormone imbalance, urogenital diseases, environmental factors, and genetic factors. Owing to its relationship with genetic factors, male infertility cannot be diagnosed through routine examination in most cases, and is clinically called 'idiopathic male infertility.' Recent studies have provided evidence that microRNAs (miRNAs) are expressed in a cell-or stage-specific manner during spermatogenesis. This review focuses on the role of miRNAs in male infertility and spermatogenesis. Data were collected from published studies that investigated the effects of miRNAs on spermatogenesis, sperm quality and quantity, fertilization, embryo development, and assisted reproductive technology (ART) outcomes. Based on the findings of these studies, we summarize the targets of miRNAs and the resulting functional effects that occur due to changes in miRNA expression at various stages of spermatogenesis, including undifferentiated and differentiating spermatogonia, spermatocytes, spermatids, and Sertoli cells (SCs). In addition, we discuss potential markers for diagnosing male infertility and predicting the varicocele grade, surgical outcomes, ART outcomes, and sperm retrieval rates in patients with non-obstructive azoospermia (NOA).

Molecular mechanisms of cellular dysfunction in testes from men with non-obstructive azoospermia

Male factor infertility affects 50% of infertile couples worldwide; the most severe form, non-obstructive azoospermia (NOA), affects 10-15% of infertile males. Treatment for individuals with NOA is limited to microsurgical sperm extraction paired with in vitro fertilization intracytoplasmic sperm injection. Unfortunately, spermatozoa are only retrieved in ~50% of patients, resulting in live birth rates of 21-46%. Regenerative therapies could provide a solution; however, understanding the cell-type-specific mechanisms of cellular dysfunction is a fundamental necessity to develop precision medicine strategies that could overcome these abnormalities and promote regeneration of spermatogenesis. A number of mechanisms of cellular dysfunction have been elucidated in NOA testicular cells. These mechanisms include abnormalities in both somatic cells and germ cells in NOA testes, such as somatic cell immaturity, aberrant growth factor signalling, increased inflammation, increased apoptosis and abnormal extracellular matrix regulation. Future cell-type-specific investigations in identifying modulators of cellular transcription and translation will be key to understanding upstream dysregulation, and these studies will require development of in vitro models to functionally interrogate spermatogenic niche dysfunction in both somatic and germ cells.

Bta-miR-127 inhibits secretion, proliferation and promotes apoptosis by targeting ITGA6 in bovine Sertoli cell

Sertoli cell (SC) play a critical role in the spermatogenesis process involved in male fecundity and reproductive potential. SC development is regulated by microRNAs (miRNAs). However, the effect and molecular mechanism of miRNAs and target genes on bovine immature SC remains poorly understood. In this study, bta-miR-127 overexpression in SC inhibited cell secretion, proliferation, cell viability, and S-phase cells number. However, inhibition of bta-miR-127 had the opposite effect. An over-expression of bta-miR-127 significantly promotes SC apoptosis, and bta-miR-127 inhibition can significantly inhibit this process. These results reveal that bta-miR-127 is an inhibitor of SC proliferation and secretion. A combination of transcriptome sequencing, bioinformatics analysis, and dual-luciferase reporter assay showed that ITGA6 was targeted by bta-miR-127. The small interfering RNA of ITGA6 (si-ITGA6) inhibits SC proliferation and secretion, as well as promotes apoptosis. The SC proliferation and secretion marker genes, cell viability, and S phase cell number in co-transfected si-ITGA6 + miR-127 inhibitor was significantly lower than those of the bta-miR-127 inhibitor group. These results further confirmed that bta-miR-127 targeting ITGA6 inhibits the SC proliferation and secretion, and promotes SC apoptosis. These findings proposed a novel miRNA (bta-miR-127) that impeded bovine SC proliferation and promoted SC apoptosis through downregulation of ITGA6.

The Role of microRNA in Spermatogenesis: Is There a Place for Fertility Preservation Innovation?

Oncological treatments have dramatically improved over the last decade, and as a result, survival rates for cancer patients have also improved. Quality of life, including concerns about fertility, has become a major focus for both oncologists and patients. While oncologic treatments are often highly effective at suppressing neoplastic growth, they are frequently associated with severe gonadotoxicity, leading to infertility. For male patients, the therapeutic option to preserve fertility is semen cryopreservation. In prepubertal patients, immature testicular tissue can be sampled and stored to allow post-cure transplantation of the tissue, immature germ cells, or in vitro spermatogenesis. However, experimental techniques have not yet been proven effective for restoring sperm production for these patients. MicroRNAs (miRNAs) have emerged as promising molecular markers and therapeutic tools in various diseases. These small regulatory RNAs possess the unique characteristic of having multiple gene targets. MiRNA-based therapeutics can, therefore, be used to modulate the expression of different genes involved in signaling pathways dysregulated by changes in the physiological environment (disease, temperature, ex vivo culture, pharmacological agents). This review discusses the possible role of miRNA as an innovative treatment option in male fertility preservation-restoration strategies and describes the diverse applications where these new therapeutic tools could serve as fertility protection agents.

Functions and mechanism of noncoding RNA in regulation and differentiation of male mammalian reproduction

Noncoding RNAs (ncRNAs) are active regulators of a wide range of biological and physiological processes, including the majority of mammalian reproductive events. Knowledge of the biological activities of ncRNAs in the context of mammalian reproduction will allow for a more comprehensive and comparative understanding of male sterility and fertility. In this review, we describe recent advances in ncRNA-mediated control of mammalian reproduction and emphasize the importance of ncRNAs in several aspects of mammalian reproduction, such as germ cell biogenesis and reproductive organ activity. Furthermore, we focus on gene expression regulatory feedback loops including hormones and ncRNA expression to better understand germ cell commitment and reproductive organ function. Finally, this study shows the role of ncRNAs in male reproductive failure and provides suggestions for further research.

Comparative analysis of microRNA and messengerRNA expression profiles in plateau zokor testicular cells under reproductive suppression

Introduction

Reproductive suppression is an adaptive strategy that affects the success rate and reproductive efficiency in animals, which in turn affects population continuation and evolution. However, no studies on the miRNAs in testicular development and spermatogenesis regulatory mechanisms under reproductive suppression have been reported.

Methods

In this study, the differentially expressed (DE) miRNAs, miRNA-mRNA interaction network and function of the plateau zokor testicular cells of non-breeders and breeders during the breeding season were comprehensively analyzed by transcriptomics.

Results

In total, 381 known and 94 novel miRNAs were determined. Compared with that in the breeders, 70 downregulated and 68 upregulated DE miRNAs were identified in the non-breeders. We predicted 1670 significant target mRNAs by analyzing the miRNA and mRNA expression profiles. According to the miRNA-mRNA interaction network, the target mRNAs of the DE miRNAs were related to testicular development and spermatogenesis. GO indicate that the target mRNAs were related to testicular development and spermatogenesis. KEGG indicate that pathways of target mRNAs enrichment related to testicular development, spermatogenesis, and energy metabolism. PROK2 was determined as the target mRNA of rno-miR-143-3p.

Discussion

Our study offers a basis for the regulatory mechanisms of miRNAs in testicular development and spermatogenesis in plateau zokor under reproductive suppression and offers a reference for reproductive regulation.

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.

Sertoli cell-only syndrome: advances, challenges, and perspectives in genetics and mechanisms

Male infertility can be caused by quantitative and/or qualitative abnormalities in spermatogenesis, which affects men's physical and mental health. Sertoli cell-only syndrome (SCOS) is the most severe histological phenotype of male infertility characterized by the depletion of germ cells with only Sertoli cells remaining in the seminiferous tubules. Most SCOS cases cannot be explained by the already known genetic causes including karyotype abnormalities and microdeletions of the Y chromosome. With the development of sequencing technology, studies on screening new genetic causes for SCOS are growing in recent years. Directly sequencing of target genes in sporadic cases and whole-exome sequencing applied in familial cases have identified several genes associated with SCOS. Analyses of the testicular transcriptome, proteome, and epigenetics in SCOS patients provide explanations regarding the molecular mechanisms of SCOS. In this review, we discuss the possible relationship between defective germline development and SCOS based on mouse models with SCO phenotype. We also summarize the advances and challenges in the exploration of genetic causes and mechanisms of SCOS. Knowing the genetic factors of SCOS offers a better understanding of SCO and human spermatogenesis, and it also has practical significance for improving diagnosis, making appropriate medical decisions, and genetic counseling. For therapeutic implications, SCOS research, along with the achievements in stem cell technologies and gene therapy, build the foundation to develop novel therapies for SCOS patients to produce functional spermatozoa, giving them hope to father children.

MicroRNA profiling reveals the role of miR-133b-3p in promoting apoptosis and inhibiting cell proliferation and testosterone synthesis in mouse TM3 cells

Late-onset hypogonadism (LOH) is an age-related clinical and biological syndrome in which serum testosterone deficiency is an important characteristic and diagnostic indicator. In this study, we firstly analyzed the difference in the expression level of three miR-133 s (including miR-133a-3p, miR-133a-5p, and miR-133b-3p) in rat testis samples, blood samples from mice before and 1 wk after testis removal, and mouse TM3 cells. Secondly, the mimics and inhibitors corresponding to the three miR-133 s of mouse were transfected into TM3 cells separately to determine the correlation between the three miRNAs. Finally, using mouse TM3 cells to analyze the effect of miR-133b overexpression or inhibition on the proliferation and apoptosis of mouse testicular Leydig cells, the effect on genes related to testosterone synthesis, and the effect on the level of testosterone in the culture medium. We found that, compared with the testis tissue of newborn rats, miR-133a-5p was increased in adult rats, and miR-133a-3p and miR-133b-3p were decreased. In addition, 1 wk after the testis was removed, the expression levels of these three miRNAs in the blood of adult mice decreased. The correlation of the three miRNAs was summarized, and it was found that miR-133b-3p played an important role in it. In TM3 cells, overexpression of miR-133b-3p suppressed the proliferation and promotes apoptosis of cells, suppressed the expression level of most genes related to cell proliferation and testosterone synthesis, and the concentration of testosterone in the culture medium decreased while these phenomena can be reversed by the inhibition of miR-133b-3p expression. It was found that miR-133b-3p can regulate testosterone production in TM3 cells at least by targeting FSCN1. The above results suggest that miR-133b-3p plays an important role in regulating testosterone synthesis. These findings also provide new candidate diagnostic indicators for late-onset hypogonadism in men and provide new clues for the further study of pathogenesis.

miRNA Profiling of Major Testicular Germ Cells Identifies Stage-Specific Regulators of Spermatogenesis

Spermatogenesis is tightly controlled at transcriptional, post-transcriptional, and epigenetic levels by various regulators, including miRNAs. This study deals with the identification of miRNAs critical to the three important stages of germ cell development (spermatocytes, round spermatids, and mature sperm) during spermatogenesis. We used high-throughput transcriptome sequencing to identify the differentially expressed miRNAs in the pachytene spermatocytes, round spermatids, and mature sperm of rat. We identified 1843 miRNAs that were differentially expressed across the three stages of germ cell development. These miRNAs were further categorized into three classes according to their pattern of expression during spermatogenesis: class 1 - miRNAs found exclusively in one stage and absent in the other two stages; class 2 - miRNAs found in any two stages but absent in the third stage; class 3 - miRNAs expressed in all the three stages. Six hundred forty-six miRNAs were found to be specific to one developmental stage, 443 miRNAs were found to be common across any two stages, and 754 miRNAs were common to all the three stages. Target prediction for ten most abundant miRNAs specific to each category identified miRNA regulators of mitosis, meiosis, and cell differentiation. The expression of each miRNA is specific to a particular developmental stage, which is required to maintain a significant repertoire of target mRNAs in the respective stage. Thus, this study provided valuable data that can be used in the future to identify the miRNAs involved in spermatogenic arrest at a particular stage of the germ cell development.

Association between metabolic disorders and seminal plasma miRNA levels: a pilot study

BACKGROUND

Excess weight and metabolic disorders have a negative impact on male reproductive functions. The mechanisms involved are numerous and complex and epigenetic mechanisms may also be involved, notably through the small non-coding RNAs. Among them, microRNAs (miRNAs) are of particular interest. This preliminary study aimed to identify the miRNAs differentially enriched in seminal plasma related to metabolic disorders and if some are also associated with spermatic parameters alterations. One hundred and sixty men between 18 to 45 years, partners of infertile couple, were included in this cohort. The miRNAs associated with metabolism were selected from the literature and assayed by quantitative real-time PCR using TaqMan gene expression assays. A subset of those with an interesting profile in seminal plasma were secondarily tested in blood.

RESULTS

Among the 11 selected miRNAs, seven were detected in seminal plasma (miR10b, miR19a, miR19b, miR34b, miR34c, miR133b, miRlet7c). A negative correlation was observed between seminal miR19a levels and metabolic syndrome, blood glucose and C-peptide. Seminal miR19b levels were also negatively correlated with metabolic syndrome. Seminal miR34c levels were negatively correlated with body mass index (BMI) and waist circumference. Seminal miR133b levels were positively correlated with BMI, waist circumference and leptin levels. Interestingly, modifications of miRNAs in seminal plasma seem specific since highlighted above correlations were not retrieved in the blood plasma for the miR19a, 19b, 10b, 34c.

CONCLUSION

Few metabolic and anthropometric disorders are correlated with the level of specific miRNAs in seminal plasma. Further studies will be required to decipher if other small non-coding RNAs may also be correlated with metabolic and anthropometric disorders and to assess their potential implication in the alteration of reproductive functions in men with obesity or metabolic disorders.

CLINICAL STUDY

Metabolic Syndrome and Male Infertility (Metasperme): Trial registration:  NCT01974947 . Registered 18 July 2013.

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.

Protective role of m6A binding protein YTHDC2 on CCNB2 in manganese-induced spermatogenesis dysfunction

Human infertility has become the third largest serious disease in the world, seriously affecting the quality of human fertility. Studies have shown that manganese (Mn) can accumulate in the testis through the blood-testicular barrier and damage the male reproductive system. However, the mechanism has not been explored clearly. Recent studies have reported that YTH domain-containing 2 (YTHDC2) can regulate reproductive function. However, none has explored the role of YTHDC2 in Mn-induced reproductive toxicity. The present study investigated whether YTHDC2/CyclinB2 (CCNB2) pathway participates in Mn-induced reproductive toxicity using Kunming mice, spermatogonia, and the seminal plasma of male workers. The mice were received intraperitoneal (i.p.) injections of 0, 12.5, 25, and 50 mg/kg MnCl₂ once daily for 2 weeks. The cells were treated with 0, 100, 200 and 400 μM MnCl₂ for 24 h. Here, we found that occupational Mn exposure significantly increased Mn levels in the seminal plasma of male workers, while decreased sperm density, semen quality, and the levels of YTHDC2, CCNB1, and CCNB2. We found that Mn can inhibit the YTHDC2/CCNB2 signaling pathway and block the G2/M phase of the cell cycle. Moreover, the morphology of cells and the histomorphology of mice testis were injured. Notably, over-expression (OE) of YTHDC2 increased CCNB2 levels, reduced cell cycle arrest, and improved reproductive toxicity after Mn exposure. These findings suggest that the YTHDC2/CCNB2 signaling pathway participates in Mn-induced reproductive toxicity, and OE of YTHDC2 can mitigate the toxicity of Mn.

The gene regulatory role of non-coding RNAs in non-obstructive azoospermia

Non-coding RNAs are classified as small non-coding RNAs, long non-coding RNAs and circular RNAs, which are involved in a variety of biological processes, including cell differentiation, proliferation, apoptosis and pathological conditions of various diseases. Many studies have shown that non-coding RNAs are related to spermatogenesis, maturation, apoptosis, function, etc. In addition, the expression of non-coding RNAs in testicular tissue and semen of patients with non-obstructive azoospermia was different. However, the role of non-coding RNAs in the pathogenesis of non-obstructive azoospermia has not been fully elucidated, and the role of non-coding RNAs in non-obstructive azoospermia is rarely reviewed. Here we summarize the research progress of non-coding RNAs in the pathogenesis of non-obstructive azoospermia.

What Does Androgen Receptor Signaling Pathway in Sertoli Cells During Normal Spermatogenesis Tell Us?

Androgen receptor signaling pathway is necessary to complete spermatogenesis in testes. Difference between androgen binding location in Sertoli cell classifies androgen receptor signaling pathway into classical signaling pathway and non-classical signaling pathway. As the only somatic cell type in seminiferous tubule, Sertoli cells are under androgen receptor signaling pathway regulation via androgen receptor located in cytoplasm and plasma membrane. Androgen receptor signaling pathway is able to regulate biological processes in Sertoli cells as well as germ cells surrounded between Sertoli cells. Our review will summarize the major discoveries of androgen receptor signaling pathway in Sertoli cells and the paracrine action on germ cells. Androgen receptor signaling pathway regulates Sertoli cell proliferation and maturation, as well as maintain the integrity of blood-testis barrier formed between Sertoli cells. Also, Spermatogonia stem cells achieve a balance between self-renewal and differentiation under androgen receptor signaling regulation. Meiotic and post-meiotic processes including Sertoli cell - Spermatid attachment and Spermatid development are guaranteed by androgen receptor signaling until the final sperm release. This review also includes one disease related to androgen receptor signaling dysfunction named as androgen insensitivity syndrome. As a step further ahead, this review may be conducive to develop therapies which can cure impaired androgen receptor signaling in Sertoli cells.

Regulation of mammalian spermatogenesis by miRNAs

Male fertility requires the continual production of sperm by the process of spermatogenesis. This process requires the correct timing of regulatory signals to germ cells during each phase of their development. MicroRNAs (miRNAs) in germ cells and supporting Sertoli cells respond to regulatory signals and cause down- or upregulation of mRNAs and proteins required to produce proteins that act in various pathways to support spermatogenesis. The targets and functional consequences of altered miRNA expression in undifferentiated and differentiating spermatogonia, spermatocytes, spermatids and Sertoli cells are discussed. Mechanisms are reviewed by which miRNAs contribute to decisions that promote spermatogonia stem cell self-renewal versus differentiation, entry into and progression through meiosis, differentiation of spermatids, as well as the regulation of Sertoli cell proliferation and differentiation. Also discussed are miRNA actions providing the very first signals for the differentiation of spermatogonia stem cells in a non-human primate model of puberty initiation.

Comprehensive Analysis of miRNAs and Target mRNAs between Immature and Mature Testis Tissue in Chinese Red Steppes Cattle

Simple Summary

MicroRNAs are small molecules that can regulate the relative abundance of their target genes by binding to the 3′ untranslated region of the target genes at the post-transcriptional level to affect various biological processes, such as biosynthesis, fat metabolism and proliferation, apoptosis, and cell differentiation. Fertility is one of the most important economic traits in livestock production. Bulls require the continuous production of high-quality spermatozoa in abundance. The quality of semen is an exceptionally important factor affecting the fertilization rate of the dairy cow and is also associated with the increasing conception rate in the process of artificial insemination. Therefore, accurately predicting fertility potential for a semen sample from donor bull for artificial insemination is crucial for consistently high reproductive efficiency. The present study performed a genome-wide sequencing analysis of microRNAs and mRNAs between immature and mature testes of Chinese Red Steppes. These results provide novel candidate microRNAs and functional genes related to bull reproduction traits and the networks between microRNAs and target genes, which will provide a useful genetic mechanism and epigenetic information for marker-assisted selection of bulls with excellent sperm quality in the future.

Abstract

This study aims to screen potential regulators and regulate fecundity networks between microRNAs (miRNAs) and target genes. The bovine testes of immature and mature Chinese Red Steppes were performed by genome-wide analysis of mRNAs and miRNAs. Compared with testicular tissues of newborns, 6051 upregulated genes and 7104 downregulated genes in adult cattle were identified as differentially expressed genes (DEGs). The DEGs were significantly enriched in 808 GO terms (p < 0.05) including male gonad development, male genitalia development, spermatogenesis, and sperm motility. Moreover, DEGs were also significantly enriched in 105 KEGG pathways (p < 0.05), including cGMP-PKG signaling pathway and calcium signaling pathway. To explore the expression of miRNA-regulated gene expression, 896 differentially expressed target genes negatively regulated with the expression levels of 31 differentially expressed miRNAs (DERs) were predicted and analyzed, and a network-integrated analysis was constructed. Furthermore, real-time PCR was performed to verify the expression levels of DEGs and DERs. Our results identified novel candidate DEGs and DERs correlated with male reproduction and intricate regulating networks between miRNAs and genes, which will be valuable for future genetic and epigenetic studies of sperm development and maturity, as well as providing valuable insights into the molecular mechanisms of male fertility and spermatogenesis in cattle.

Estradiol ameliorates metformin-inhibited Sertoli cell proliferation via AMPK/TSC2/mTOR signaling pathway

Metformin is a commonly used for treating type 2 diabetes and it acts on a variety of organs including the male reproductive system. 17β-estradiol plays an important role in Sertoli cell (SC) proliferation which determines the germ cell development and spermatogenesis. The aim of this study is to investigate the effect of metformin on immature chicken SC proliferation and the potential mechanisms by which 17β-estradiol regulate this process. Results showed that metformin significantly inhibited SC proliferation, whereas 17β-estradiol weakened the inhibitory effects of metformin on SC viability, cell growth, and cell cycle progression. SC proliferation-inhibiting effect of metformin exposure was regulated by decreasing adenosine triphosphate level and respiratory enzyme activity in the mitochondria; this process was possibly mediated by the adenosine monophosphate-activated protein kinase (AMPK)/tuberous sclerosis complex 2 (TSC2)/mammalian target of rapamycin (mTOR) signaling pathway, which was regulated by the down-expressed miR-1764 and by the decreased antioxidant enzyme activity and excessive reactive oxygen species generation. In addition, SCs transfected with the miR-1764 agomir led to an improvement of proliferation capacity through down-regulating AMPKα2 level, which further decreased TSC2 expression and induced mTOR activation. However, the anti-proliferative effect of miR-1764 antagomir can be alleviated by 17β-estradiol treatment via the up-expression of miR-1764 in transfected SCs. Our findings suggest appropriate dose of exogenous 17β-estradiol treatment can ameliorate the inhibitory effect of metformin on SC proliferation via the regulation of AMPK/TSC2/mTOR signaling pathway, this might reduce the risk of poor male fertility caused by the abuse of anti-diabetic agents.

Determination of the Excitatory Effects of MicroRNA-30 in the Self-Renewal and Differentiation Process of Neonatal Mouse Spermatogonial Stem Cells

Background:

Spermatogonial stem cells (SSCs) are considered as special stem cells since they have the ability of self-renewal, differentiation, and transferring genetic information to the next generation. Also, they considered as vital players in initiating and preserving spermatogenesis. The fate decisions of SSCs are mediated by intrinsic and extrinsic factors, among which microRNAs (miRNAs) are one of the most essential factors in spermatogenesis among endogenous regulators. However, the mechanisms by which individual miRNAs regulate self-renewal and differentiation of SSCs are unclear. The present study aimed to evaluate the impact of miRNA-30 mimic on fate determinations of SSCs.

Materials and Methods:

The obtained SSCs from neonatal mice (3-6 days old) were purified by MACS and flow cytometry with a promyelocytic leukemia zinc-finger marker. Then, the cultured cells were transfected with miRNA- 30 mimic, and finally, the changes in expressing ID4 and c-kit proteins were assessed by western blot analysis.

Results:

According to flow cytometry findings, the percentage of SSC purity was about 98.32. The expression of ID4 protein and colonization increased significantly through the transfection of miRNA-30 mimic (P<0.05).

Conclusion:

The miRNA-30 controls spermatogonial stem cell self-renewal and differentiation, which may have significant implications for treating male infertility.

Identification and function prediction of novel microRNAs in adenosine monophosphate activated protein kinase-activated Sertoli cells of immature boar

This study was carried out with the objective to identify function prediction of novel microRNAs (miRNAs) in immature boar Sertoli cells (SCs) treated with 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR), which is an agonist of adenosine monophosphate-activated protein kinase (AMPK) for regulating cellular energy homeostasis. Two small RNA libraries (control and AICAR treatment) prepared from immature boar SCs were constructed and sequenced by the Illumina small RNA deep sequencing. We identified 77 novel miRNAs and predicted 177 potential target genes for 26 differential novel miRNAs (four miRNAs up-regulation and 22 miRNAs down-regulation) in AICAR-treated SCs. Gene Ontology enrichment and Kyoto Encyclopedia of Genes and Genomes pathway suggested that target genes of differential novel miRNAs were implicated in many biological processes and metabolic pathways. Our findings provided useful information for the functional regulation of novel miRNAs and target mRNAs on AMPK-activated immature boar SCs.

Role of microRNAs in etiology of azoospermia and their application as non-invasive biomarkers in diagnosis of azoospermic patients

Azoospermia is a common cause of male infertility without any sperm in the semen and consists of ∼1% of all males and ∼15% of infertile ones. Currently, no accurate non-invasive diagnostic method exists for patients with azoospermia and testis biopsy is mandatory to determine if any spermatozoa exist in the testes. Studies have clarified that the expression of some distinct microRNAs shows alterations in azoospermic patients. MicroRNAs play critical roles during spermatogenesis and their dysregulation can defect this process. Here, we review studied microRNAs involved in the pathogenesis of azoospermia and their target genes. Moreover, we will imply the utility of seminal plasma microRNAs as non-invasive diagnostic biomarkers for azoospermia. We hope such studies could help patients with azoospermia in both diagnosis and treatment, in order that they could father their own biological children.

Study of microRNA Expression Profile in Different Regions of Ram Epididymis

The regional expression of epididymal genes provides a guarantee for sperm maturation. As a class of endogenous non-coding small RNAs, microRNAs (miRNAs) play an important role in spermatogenesis, maturation and fertilization. Currently, the regulatory role of miRNA in the epididymis is poorly understood. Here, transcriptome sequencing was used to analyse miRNA expression profiles in three regions of the epididymis of rams, including caput, corpus and cauda. The results showed that there were 13 known miRNAs between the caput and corpus controls, 29 between the caput and cauda and 22 differences between the corpus and cauda. Based on the analysis of miRNA target genes by GO and KEGG, a negative regulation network of miRNA-mRNA was constructed in which let-7, miR-541-5p, miR-133b and miR-150 may play an important regulatory role in the maturation regulation of ram epididymal sperm. This research provides a reference for studying the regulation mechanism of sperm maturation in male epididymis and improving semen quality and male reproductive performance.

MicroRNA-30a-5p promotes differentiation in neonatal mouse spermatogonial stem cells (SSCs)

BACKGROUND

The importance of spermatogonial stem cells (SSCs) in spermatogenesis is crucial and intrinsic factors and extrinsic signals mediate fate decisions of SSCs. Among endogenous regulators, microRNAs (miRNAs) play critical role in spermatogenesis. However, the mechanisms which individual miRNAs regulate self- renewal and differentiation of SSCs are unknown. The aim of this study was to investigate effects of miRNA-30a-5p inhibitor on fate determinations of SSCs.

METHODS

SSCs were isolated from testes of neonate mice (3-6 days old) and their purities were performed by flow cytometry with ID4 and Thy1 markers. Cultured cells were transfected with miRNA- 30a-5p inhibitor. Evaluation of the proliferation (GFRA1, PLZF and ID4) and differentiation (C-Kit & STRA8) markers of SSCs were accomplished by immunocytochemistry and western blot 48 h after transfection.

RESULTS

Based on the results of flow cytometry with ID4 and Thy1 markers, percentage of purity of SSCs was about 84.3 and 97.4 % respectively. It was found that expression of differentiation markers after transfection was significantly higher in miRNA-30a- 5p inhibitor group compared to other groups. The results of proliferation markers evaluation also showed decrease of GFRA1, PLZF and ID4 protein in SSCs transfected with miRNA-30a-5p inhibitor compared to the other groups.

CONCLUSIONS

It can be concluded that inhibition of miRNA-30a-5p by overexpression of differentiation markers promotes differentiation of Spermatogonial Stem Cells.

Using miRNAs as diagnostic biomarkers for male infertility: opportunities and challenges

The non-coding genome has been extensively studied for its role in human development and diseases. MicroRNAs (miRNAs) are small non-coding RNAs, which can regulate the expression of hundreds of genes at the post-transcriptional level. Therefore, any defects in miRNA biogenesis or processing can affect the genes and have been linked to several diseases. Male infertility is a clinical disorder with a significant number of cases being idiopathic. Problems in spermatogenesis and epididymal maturation, testicular development, sperm maturation or migration contribute to male infertility, and many of these idiopathic cases are related to issues with the miRNAs which tightly regulate these processes. This review summarizes the recent research on various such miRNAs and puts together the candidate miRNAs that may be used as biomarkers for diagnosis. The development of strategies for male infertility treatment using anti-miRs or miRNA mimics is also discussed. Although promising, the development of miRNA diagnostics and therapeutics is challenging, and ways to overcome some of these challenges are also reviewed.

The mechanisms and functions of microRNAs in mediating the fate determinations of human spermatogonial stem cells and Sertoli cells

Human spermatogonial stem cells (SSCs) and Sertoli cells might have the applications in reproduction and regenerative medicine. Abnormal spermatogenesis results in male infertility, which seriously affects human reproduction and health. Spermatogenesis depends on the epigenetic and genetic regulation of male germ cells and somatic cells. A number of microRNAs (miRNAs) have been identified in human testicular tissues, and they are closely related to male fertility. Significantly, we and peers have recently demonstrated that numerous miRNAs are essential for regulating the self-renewal and apoptosis of human SSCs and Sertoli cells through controlling their mRNA and lncRNA targets. In this review, we critically discuss these findings regarding the important functions and mechanisms of miRNAs in mediating the fate determinations of human SSCs and Sertoli cells. Meanwhile, we illustrate the regulatory networks for miRNAs by forming the upstream and downstream regulators of mRNAs and lncRNAs in human SSCs, and we address that miRNAs regulate the decisions of Sertoli cells by targeting genes and via N6-methyladenosine (m6A). We also point out the future directions for further studies on this field. This review could offer an update on novel molecular targets for treating male infertility and new insights into epigenetic regulation of human spermatogenesis.

Novel Gene Regulation in Normal and Abnormal Spermatogenesis

Spermatogenesis is a complex and dynamic process which is precisely controlledby genetic and epigenetic factors. With the development of new technologies (e.g., single-cell RNA sequencing), increasingly more regulatory genes related to spermatogenesis have been identified. In this review, we address the roles and mechanisms of novel genes in regulating the normal and abnormal spermatogenesis. Specifically, we discussed the functions and signaling pathways of key new genes in mediating the proliferation, differentiation, and apoptosis of rodent and human spermatogonial stem cells (SSCs), as well as in controlling the meiosis of spermatocytes and other germ cells. Additionally, we summarized the gene regulation in the abnormal testicular microenvironment or the niche by Sertoli cells, peritubular myoid cells, and Leydig cells. Finally, we pointed out the future directions for investigating the molecular mechanisms underlying human spermatogenesis. This review could offer novel insights into genetic regulation in the normal and abnormal spermatogenesis, and it provides new molecular targets for gene therapy of male infertility.

Sertoli cell-only syndrome: etiology and clinical management

Almost 50% of infertility cases are due to male factors, and spermatogenesis failure is one of the most severe forms of male infertility. Sertoli cell-only syndrome (SCOS) also known as germ cell aplasia is characterized by azoospermia in which the seminiferous tubules of testicular biopsy are lined only with Sertoli cells. The definitive diagnosis of SCOS is by diagnostic testicular biopsy. Although SCOS may be a result of Klinefelter syndrome, most of the SCOS men have a normal karyotype. Along with genetic aberrations, signaling pathways and endocrine processes might be major factors in the development of SCOS. Sperm retrieval and intracytoplasmic sperm injection (ICSI) are available treatments for SCOS. However, some SCOS patients do not have therapeutic options to help them having a biological child. This review aims to summarize our present knowledge about SCOS and to highlight the importance of future researches in the diagnosis and treatment of this disorder.

Bta-miR-34b inhibits proliferation and promotes apoptosis via the MEK/ERK pathway by targeting MAP2K1 in bovine primary Sertoli cells

Immature Sertoli cell (SC) proliferation determines the final number of mature SCs and further regulates spermatogenesis. Accumulating evidence demonstrated that microRNAs (miRNAs) play an important role in SC proliferation, differentiation, and apoptosis. However, the effect and molecular mechanism of miRNA on bovine immature SC remain to be poorly understood. In this study, miRNA sequencing of testes collected in mature (24-mo old) and immature (neonatal) bulls was conducted to determine the miRNA expression profiles. MicroRNA-34b was one of the differentially expressed miRNAs and was selected for in-depth functional studies pertaining to SC growth. The results showed that miR-34b mimic transfection in primary Sertoli cells (PSC) inhibited cell proliferation and induced cell cycle arrested at G2 phase and decreased the expression of cell cycle-related genes such as CCNB1, CDK1, CDC25C, and C-MYC. MicroRNA-34b overexpression also leads to increased cell apoptosis, with proapoptotic genes P53 and BAX upregulated, while antiapoptotic gene BCL2 decreased. However, miR-34b knockdown had the opposite effects. Through a combination of transcriptome sequencing, bioinformatics analysis, dual-luciferase reporter assay, and Western blotting, mitogen-activated protein kinase kinase1 (MAP2K1), also known as MEK1, was identified as a target of miR-34b. In addition, PSC proliferation inhibition was mediated by cell cycle arrest and apoptosis with MAP2K1 interference. Overexpression of MAP2K1 effectively reversed the miR-34b-repressed PSC cell growth. Moreover, both miR-34b overexpression and MAP2K1 knockdown decreased the protein levels of P-ERK1/2, while MAP2K1 overexpression showed opposite effects. In summary, data suggest that miR-34b regulates PSC proliferation and apoptosis through the MEK/ERK signaling pathway. These data provide a theoretical and experimental framework for further clarifying the regulation of cell growth in PSC of bovine.

Exploring the dysregulated mRNAs-miRNAs-lncRNAs interactions associated to idiopathic non-obstructive azoospermia

Non-obstructive azoospermia (NOA) is the most clinical problem in case of infertility. About 70% of NOA patients are idiopathic with uncharacterized molecular mechanisms. This study aimed to analyze the possible pathogenic miRNA-target gene interaction and lncRNA-miRNA association involved in NOA. In the current study, differentially expressed (DE) nRNAs, miRNAs and lncRNAs were determined using the microarray dataset and statistical software R. miRNAs-mRNA and miRNA-lncRNA interactions were identified and the base-pair binding between the seed region of miRNAs and complementary nucleotides in 3' UTR of mRNAs were analyzed. The influence of the validated single nucleotide polymorphisms (SNPs) was described by calculating the minimum free energy (MFE) of the interaction. A total of 74 mRNAs, 14 miRNAs, and 10 lncRNAs were identified to have significant differential expression in testicular tissue between patients and the fertile group. Four of the DE-mRNAs and all of the reported DE-miRNAs were upregulated. In addition, all of the represented DE-lncRNAs were showed to be downregulated. miR-509-5p and miR-27b-3p were found to interact with target gene polo-like kinase 1 (PLK1) and Cysteine-rich secretory protein2 (CRISP2), respectively. Rs550967205 (A > G) positioned at 3' UTR CRISP2 and rs544604911 (T > C) located at 3' UTR PLK1, with lowest MFE in miRNA-mRNA interaction, were assumed to have possible pathogenic roles linked to spermatogenesis arrest. The results of the study provide new clues to understand the regulatory roles of miRNAs and lncRNAs in the pathogenesis and diagnosis of idiopathic azoospermia. Communicated by Ramaswamy H. Sarma.

AR regulates porcine immature Sertoli cell growth via binding to RNF4 and miR-124a

Sertoli cells are the only somatic cells in the seminiferous epithelium which directly contact with germ cells. Sertoli cells exhibit polarized alignment at the basal membrane of seminiferous tubules to maintain the microenvironment for growth and development of germ cells, and therefore play a crucial role in spermatogenesis. Androgens exert their action through androgen receptor (AR) and AR signalling in the testis is essential for maintenance of spermatogonial numbers, blood-testis barrier integrity, completion of meiosis, adhesion of spermatids and spermiation. In the present study, we demonstrated that AR gene could promote the proliferation of immature porcine Sertoli cells (ST cells) and the cell cycle procession, and accelerate the transition from G1 phase into S phase in ST cells. Meanwhile, miR-124a could affect the proliferation and cell cycle procession of ST cells by targeting 3'-UTR of AR gene. Furthermore, AR bound to the RNF4 via AR DNA-binding domain (DBD) and we verified that RNF4 was necessary for AR to regulate the growth of ST cells. Above all, this study suggests that AR regulates ST cell growth via binding to RNF4 and miR-124a, which may help us to further understand the function of AR in spermatogenesis.

miR-4270 regulates cell proliferation and apoptosis in patients with Sertoli cell-only syndrome by targeting GADD45A and inactivating the NOTCH signaling pathway

In recent decades, growing data has suggested that microRNAs (miRNAs, miRs) play a critical role in the development of Sertoli cells (SC), including regulating SC maturation, synthesis, proliferation, and apoptosis. Previous reports of miRNA microarray have identified aberrant miR-4270 expression in patients with Sertoli-cell-only syndrome (SCOS). However, it is not known whether miR-4270 is associated with the pathogenesis of SCOS. In this study, we aimed to further investigate the roles and potential mechanisms of miR-4270 on SC proliferation and apoptosis. Our data confirmed that miR-4270 was significantly upregulated in SC of SCOS patients compared with healthy controls. EdU and CCK-8 assays showed silencing of miR-4270 by specific inhibitor significantly enhanced human SC and TM4 cells proliferation. ELISA and flow cytometry assays indicated that miR-4270 knockdown prominently suppressed the apoptosis of human SC and TM4 cells. Furthermore, expression of cell cycle genes, including CCNE1 (cyclin E1), CCND1 (cyclin D1) and CDK4 (cyclin dependent kinase 4), were obviously upregulated in human SC and TM4 cells by qRT-PCR assay after knockdown of miR-4270, while expression of cell apoptotic factors, including CASP3 (caspase 3), CASP6 (caspase 6) and CASP7 (caspase 7), were all markedly decreased. Notably, GADD45A (growth arrest and DNA damage inducible alpha) mRNA was downregulated in SC of SCOS patients, and negatively corrected with miR-4270 expression. Moreover, bioinformatics tools and dual-luciferase reporter assay identified that miR-4270 directly bound the 3'-UTR of GADD45A mRNA to inhibit GADD45A expression. Meanwhile, Western blots analysis validated that the protein expression levels of NOTCH1 (notch receptor 1) and HES1 (hes family bHLH transcription factor 1) were significantly increased in SC and TM4 cells after miR-4270 silencing or GADD45A overexpression. Taken together, our data demonstrated that miR-4270 regulates proliferation and apoptosis in SC of SCOS patients by inactivating NOTCH signaling pathway via GADD45A gene, which may offer a new insight into the development of human SC and provide a promising biomarker for the treatment of SCOS.

miR-130a promotes immature porcine Sertoli cell growth by activating SMAD5 through the TGF-β-PI3K/AKT signaling pathway

Sertoli cells play vital roles in normal spermatogenesis, and microRNAs (miRNAs) participate in regulating Sertoli cell development. However, the functions and mechanisms of action of most identified miRNAs in porcine Sertoli cells remain largely unknown. Herein, we primarily explored the regulatory roles of miR-130a in immature porcine Sertoli cells using EdU-based high-content screening assay. The results demonstrated that 27 miRNAs have potential roles in the promotion of immature porcine Sertoli cell proliferation, and miR-130a was identified as a promising candidate. miR-130a promoted cell cycle progression and cell proliferation, whereas it impeded cell apoptosis in immature porcine Sertoli cells. It also contributed to Sertoli cell proliferation and testis development in vivo. A TMT-based proteomics approach revealed that miR-130a regulated the expression of 91 proteins and multiple pathways, including the TGF-β and PI3K/AKT signaling. miR-130a did not directly target the 3'-UTR of SMAD5; however, it increased SMAD5 phosphorylation. Moreover, miR-130a enhanced TGF-β signaling by activating SMAD5 protein, and TGF-β signaling further activated the PI3K/AKT signaling pathway to promote cell proliferation and inhibit cell apoptosis in porcine immature Sertoli cells. Collectively, miR-130a promoted immature porcine Sertoli cell growth by activating SMAD5 through the TGF-β-PI3K/AKT signaling pathway. This study, therefore, provides novel insights into the effects of miR-130a on porcine spermatogenesis through the regulation of immature Sertoli cell proliferation and apoptosis.

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.

GLI3: a mediator of genetic diseases, development and cancer

The transcription factor GLI3 is a member of the Hedgehog (Hh/HH) signaling pathway that can exist as a full length (Gli3-FL/GLI3-FL) or repressor (Gli3-R/GLI3-R) form. In response to HH activation, GLI3-FL regulates HH genes by targeting the GLI1 promoter. In the absence of HH signaling, GLI3 is phosphorylated leading to its partial degradation and the generation of GLI3-R which represses HH functions. GLI3 is also involved in tissue development, immune cell development and cancer. The absence of Gli3 in mice impaired brain and lung development and GLI3 mutations in humans are the cause of Greig cephalopolysyndactyly (GCPS) and Pallister Hall syndromes (PHS). In the immune system GLI3 regulates B, T and NK-cells and may be involved in LPS-TLR4 signaling. In addition, GLI3 was found to be upregulated in multiple cancers and was found to positively regulate cancerous behavior such as anchorage-independent growth, angiogenesis, proliferation and migration with the exception in acute myeloid leukemia (AML) and medulloblastoma where GLI plays an anti-cancerous role. Finally, GLI3 is a target of microRNA. Here, we will review the biological significance of GLI3 and discuss gaps in our understanding of this molecule. Video Abstract.

Some of the Factors Involved in Male Infertility: A Prospective Review

Infertility is defined as the inability of couples to have a baby after one year of regular unprotected intercourse, affecting 10 to 15% of couples. According to the latest WHO statistics, approximately 50-80 million people worldwide sufer from infertility, and male factors are responsible for approximately 20-30% of all infertility cases. The diagnosis of infertility in men is mainly based on semen analysis. The main parameters of semen include: concentration, appearance and motility of sperm. Causes of infertility in men include a variety of things including hormonal disorders, physical problems, lifestyle problems, psychological issues, sex problems, chromosomal abnormalities and single-gene defects. Despite numerous efforts by researchers to identify the underlying causes of male infertility, about 70% of cases remain unknown. These statistics show a lack of understanding of the mechanisms involved in male infertility. This article focuses on the histology of testicular tissue samples, the male reproductive structure, factors affecting male infertility, strategies available to find genes involved in infertility, existing therapeutic methods for male infertility, and sperm recovery in infertile men.

Downregulated long non-coding RNA SNHG7 restricts proliferation and boosts apoptosis of nasopharyngeal carcinoma cells by elevating microRNA-140-5p to suppress GLI3 expression

Long non-coding RNAs (lncRNAs) have been proposed to correlate with various carcinomas, yet the role of lncRNA SNHG7 in nasopharyngeal carcinoma (NPC) is hardly studied. This study intends to examine the molecular mechanism of SNHG7 on NPC cells. The NPC tissues and nasopharyngeal tissues of mild inflammation of nasopharyngeal mucosa were obtained. SNHG7, miR-140-5p, and GLI3 mRNA and protein expression in tissues and in the CNE1, HONE1, C666-1, CNE2, and normal NP69 cell lines was detected. IC50 and the protein expression of related drug-resistant genes of CNE2 and CNE2/DDP cells were determined. Proliferative ability, cell colony formation rate, cell cycle, and apoptosis of CNE2 and CNE2/DDP cells were also detected. SNHG7, miR-140-5p, and GLI3 mRNA and protein expression in CNE2 and CNE2/DDP cells in each group was detected. SNHG7’s cell localization, the binding sites of SNHG7 and miR-140-5p along with miR-140-5p and GLI3 were detected. Overexpressed SNHG7 and GLI3, and underexpressed miR-140-5p were found in NPC tissues and cells. SNHG7 silencing and miR-140-5p elevation declined the drug resistance of drug-resistant NPC cells and their parent cells, restrained NPC cell colony formation ability and proliferation, and boosted cell apoptosis. SNHG7 specially bound to miR-140-5p, and SNHG7 silencing elevated miR-140-5p expression. GLI3 was a direct target gene of miR-140-5p and miR-140-5p elevation diminished GLI3 expression. MiR-140-5p inhibition reversed the impacts of SNHG7 silencing on NPC cells. In summary, our study reveals that downregulated SNHG7 restricts GLI3 expression by upregulating miR-140-5p, which further suppresses cell proliferation, and promotes apoptosis of NPC.

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.

Biological role of microRNA-146a

MicroRNAs are endogenous single-stranded non-coding small RNAs that specifically bind to target mRNAs to degrade mRNAs or hinder their translation to regulate the expression of target mRNAs at the post-transcriptional level. MicroRNA-146a is involved in a bulk of biological processes and has a variety of biological functions. This article will review several aspects of the role of microRNA-146a, including controlling inflammation, regulating immunity, mediating myeloid cell proliferation, and involvement in tumor occurrence and development.

MiR-423 is differentially expressed in patients with stable and unstable coronary artery disease: A pilot study

Coronary artery disease (CAD) and acute myocardial infarction (AMI) are the leading causes of death worldwide. Since only a subset of CAD patients develops myocardial infarction, it is likely that unique factors predispose to AMI. Circulating microRNAs represent diagnostic powerful biomarkers for detection of heart injuries and patients’ risk stratification. Using an array-based approach, the expression of 84 circulating miRNAs was analyzed in plasma of pooled stable CAD patients (CAD; n = 5) and unstable CAD patients (AMI_T0; n = 5) enrolled within 24 hours from an AMI event. The array experiments showed 27 miRNAs differentially expressed with a two-fold up- or down-regulation (10 up- and 17 down-regulated miRNAs). Among them, miR-423-5p dis-regulation was confirmed in a larger case study (n = 99). Circulating miR-423-5p resulted to be significantly down-regulated within 24 hours from the AMI event (FC = -2, p≤0.05). Interestingly, miR-423-5p expression resulted to be increased (FC = +2; p≤0.005) in a subgroup of the same AMI patients (AMI_T1; n = 11) analyzed after 6 months from the acute event. We extended miR-423-5p expression study on PBMCs (peripheral blood mononuclear cells), confirming also in this tissue its up-regulation at 6 months post-AMI. Receiver operating characteristic analyses (ROC) were performed to detect the power of miR-423-5p to discriminate stable and unstable CAD. In plasma, miR-423-5p expression accurately distinguishes stable and unstable CAD patients (AUC = 0.7143, p≤0.005). Interestingly, the highest discriminatory value (AUC = 0.8529 p≤0.0005) was identified in blood cells, where miR-423-5p expression is able to differentiate unstable CAD patients during an acute event (AMI_T0) from those at six months post-AMI (AMI_T1). Furthermore, cellular miR-423-5p may discriminate also stable CAD patients from unstable CAD patients after six months post-AMI (AUC = 0.7355 p≤0.05). The results of this pilot-study suggest that miR-423-5p expression level both in plasma and blood cells, could represent a new promising biomarker for risk stratification of CAD patients.

Identification of microRNAs for regulating adenosine monophosphate-activated protein kinase expression in immature boar Sertoli cells in vitro

Adenosine monophosphate-activated protein kinase (AMPK) plays a key role in cellular energy homeostasis and cell proliferation. MicroRNAs (miRNAs) function as posttranscriptional regulators of gene expression in biological processes. It is unclear to whether miRNAs are involved in AMPK-regulated Sertoli cell (SC) proliferation. To further understand the regulation of miRNAs in the immature boar SC proliferation, 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR) was added to activate AMPK. By an Illumina small RNA deep sequencing, we obtained sequences and relative expression levels of 272 known mature miRNAs, among which 9 miRNAs were significantly upregulated whereas 16 miRNAs were downregulated following the AICAR treatment. The results identified 38 conserved miRNAs, with 8 significantly downregulated miRNAs whereas no upregulated miRNAs. Gene Ontology enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analyses suggested that miR-1285 was involved in many activities and pathways associated with cell proliferation via targeting on AMPKα2. We validated that AICAR significantly downregulated miR-1285 level in SCs. Transfection of miR-1285 mimic increased the SC viability and cell cycle progression but reduced AMPKα2 mRNA and protein levels, indicating that miR-1285 is involved in the immature boar SC proliferation via downregulating AMPKα2 expression.

Direct Sensing of Single Native RNA with a Single-Biomolecule Interface of Aerolysin Nanopore

RNA sensing is of vital significance to advance our comprehension of gene expression and to further benefit medical diagnostics. Taking advantage of the excellent sensing capability of the aerolysin nanopore as a single-biomolecule interface, we for the first time achieved the direct characterization of single native RNA of Poly(A)₄ and Poly(U)₄. Poly(A)₄ induces ∼10% larger blockade current amplitude than Poly(U)₄. The statistical duration of Poly(A)₄ is 18.83 ± 1.08 ms, which is 100 times longer than that of Poly(U)₄. Our results demonstrated that the capture of RNA homopolymers is restricted by the biased diffusion. The translocation of RNA needs to overcome a lower free-energy barrier than that of DNA. Moreover, the strong RNA-aerolysin interaction is attributed to the hydroxyl in pentose, which prolongs the translocation time. This study opens an avenue for aerolysin nanopores to directly achieve RNA sensing, including discrimination of RNA epigenetic modification and selective detection of miRNA.

miRNA-31-5p Mediates the Proliferation and Apoptosis of Human Spermatogonial Stem Cells via Targeting JAZF1 and Cyclin A2

Several lines of evidence highlight the important application of human spermatogonial stem cells (SSCs) in translational medicine. The fate decisions of SSCs are mainly mediated by genetic and epigenetic factors. We have recently demonstrated that PAK1 regulates the proliferation, DNA synthesis, and early apoptosis of human SSCs through the PDK1/KDR/ZNF367 and ERK1/2 and AKT pathway. However, the underlying epigenetic mechanism of PAK1 in human SSCs remains unknown. In this study, we found that the level of miRNA-31-5p was elevated by PAK1 knockdown. CCK-8, PCNA, and 5-ethynyl-2′-deoxyuridine (EDU) assays revealed that miRNA-31-5p mimics inhibited cell proliferation and DNA synthesis of human SSCs. Annexin V/propidium iodide (PI) staining and flow cytometry showed that miRNA-31-5p increased the early and late apoptosis of human SSCs. Furthermore, JAZF1 was predicted and verified as a target of miRNA-31-5p, and the three-dimensional (3D) structure model of JAZF1 protein was illustrated. JAZF1 silencing led to a reduction of cell proliferation and DNA synthesis as well as an enhancement of the early and late apoptosis of human SSCs. Finally, miRNA-31-5p mimics decreased the level of cyclin A2 rather than cyclin D1 or cyclin E1, and JAZF1 knockdown led to the reduction of cyclin A2 in human SSCs. Collectively, miRNA-31-5p regulates the proliferation, DNA synthesis, and apoptosis of human SSCs by the PAK1-JAZF1-cyclin A2 pathway. This study thus offers a novel insight into the molecular mechanisms underlying the fate determinations of human SSCs and might provide novel targets for molecular therapy of male infertility.