LncRNA, a new component of expanding RNA-protein regulatory network important for animal sperm development

Relationship between long non-coding RNA MALAT1 and HOTAIR expression with sperm parameters, DNA and malondialdehyde levels in male infertility

BACKGROUND

Sperm quality is a complex index used to evaluate the fertility potential of men. The long non-coding RNA (lncRNA) MALAT1 participate in sperm development and HOTAIR have critical roles in the regulation of oxidative stress responses. This study aimed to evaluate the relationship of lncRNA MALAT1 and HOTAIR expression with sperm parameters, DNA fragmentation and malondialdehyde (MDA)levels in sperm fertility.

METHODS

In this experimental study, semen samples (n = 30 fertile, n = 30 infertile) men were collected and evaluated for sperm parameters by computer-aided sperm analysis(CASA). Sperm DNA integrity quality was assessed by the Acridine orange(AO) test. MDA levels were determined by the Thiobarbituric acid reaction method. The expression of MALAT1 and HOTAIR was detected by RT-PCR.

RESULTS

We observed a decreased level of MALAT1and HOTAIR expression in the infertile men (p < 0.001). The relative expression level of MALAT1and HOTAIR showed a positive correlation with motility and morphology (p < 0.001). Subsequently, we found the DNA damage and MDA levels was negatively correlated with expression level of genes of sperm (p < 0.001).

CONCLUSION

In this study the low expression of MALATI and HOTAIR resulted in the high level of MDA, DNA damage, and reduced motility of sperm. This study suggests the therapeutic opportunities in respect to MALATI and HOTAIR expression in the sperm function.

LncRNA Functional Screening in Organismal Development

Controversy continues over the functional prevalence of long non-coding RNAs (lncRNAs) despite their being widely investigated in all kinds of cells and organisms. In animals, lncRNAs have aroused general interest from exponentially increasing transcriptomic repertoires reporting their highly tissue-specific and developmentally dynamic expression, and more importantly, from growing experimental evidence supporting their functionality in facilitating organogenesis and individual fitness. In mammalian testes, while a great multitude of lncRNA species are identified, only a minority of them have been shown to be useful, and even fewer have been demonstrated as true requirements for male fertility using knockout models to date. This noticeable gap is attributed to the virtual existence of a large number of junk lncRNAs, the lack of an ideal germline culture system, difficulty in loss-of-function interrogation, and limited screening strategies. Facing these challenges, in this review, we discuss lncRNA functionality in organismal development and especially in mouse testis, with a focus on lncRNAs with functional screening.

Knockdown of lncRNA Meg3 delays the onset of puberty in female rats

This study investigated how lncRNA Meg3 affects the onset of puberty in female rats. We determined Meg3 expression in the hypothalamus-pituitary-ovary axis of female rats at the infancy, prepubertal, pubertal, and adult life stages, using quantitative reverse transcription polymerase chain reaction (qRT-PCR). We also assessed the effects of Meg3 knockdown on the expression levels of puberty-related genes and Wnt/β-catenin proteins in the hypothalamus, time of puberty onset, levels of reproductive genes and hormones, and ovarian morphology in female rats. Meg3 expression in the ovary varied significantly between prepuberty and puberty (P < 0.01). Meg3 knockdown decreased the expression of Gnrh, and Kiss1 mRNA (P < 0.05) and increased the expression of Wnt (P < 0.01) and β-catenin proteins (P < 0.05) in the hypothalamic cells. Onset of puberty in Meg3 knockdown rats was delayed compared to the control group (P < 0.05). Meg3 knockdown decreased Gnrh mRNA levels (P < 0.05) and increased Rfrp-3 mRNA levels (P < 0.05) in the hypothalamus. The serum concentrations of progesterone (P₄) and estradiol (E₂) of Meg3 knockdown rats were lower than those in the control animals (P < 0.05). Higher longitudinal diameter and ovary weight were found in Meg3 knockdown rats (P < 0.05). These findings suggest that Meg3 regulates the expression of Gnrh, Kiss-1 mRNA and Wnt/β-catenin proteins in the hypothalamic cells, and Gnrh, Rfrp-3 mRNA of the hypothalamus and the serum concentration of P₄ and E₂, and its knockdown delays the onset of puberty in female rats.

Investigation of the mechanisms leading to human sperm DNA damage based on transcriptome analysis by RNA-seq techniques

RESEARCH QUESTION

What are the molecular mechanisms leading to human sperm DNA damage?

DESIGN

Semen samples were collected and the sperm DNA fragmentation index (DFI) was assessed. Differentially expressed RNA in spermatozoa with a high (DFI ≥30%, experimental group) or normal (DFI <30%, control group) DFI were identified by RNA-sequencing (RNA-seq) technology, and Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis was performed. Three differentially expressed RNA related to sperm DNA damage and repair, namely PMS1, TP53BP1 and TLK2, were validated using real-time quantitative (RT-qPCR).

RESULTS

A total of 19,970 expressed RNA were detected in the two groups. Compared with the control group, the expression levels of 189 RNA in the experimental group were significantly increased and those of 163 genes decreased. Gene Ontology enrichment analysis showed that these RNA were mainly concentrated in the ATPase-dependent transmembrane transport complex, extracellular exosome, somatic cell DNA recombination, protein binding, cytoplasm and regulation of localization. KEGG pathway analysis showed that these RNA were mainly related to the PI3K-Akt signalling pathway, endocytosis, p53 signalling pathway and cGMP-PKG signalling pathway. The RT-qPCR results showed that the expression levels of PMS1, TP53BP1 and TLK2 in the experimental group were significantly lower than in the control group (P = 0.01, 0.015 and 0.004, respectively), which was identical to the results of RNA sequencing.

CONCLUSIONS

Differentially expressed RNA related to sperm DNA damage and repair may be identified by RNA-seq technology, which provides new insights into the understanding of sperm DNA damage and repair, and will help to discover new biomarkers related to sperm DNA damage.

Identification of biomarkers for bull fertility using functional genomics

Prediction of bull fertility is critical for the sustainability of both dairy and beef cattle production. Even though bulls produce ample amounts of sperm with normal parameters, some bulls may still suffer from subpar fertility. This causes major economic losses in the cattle industry because using artificial insemination, semen from one single bull can be used to inseminate hundreds of thousands of cows. Although there are several traditional methods to estimate bull fertility, such methods are not sufficient to explain and accurately predict the subfertility of individual bulls. Since fertility is a complex trait influenced by a number of factors including genetics, epigenetics, and environment, there is an urgent need for a comprehensive methodological approach to clarify uncertainty in male subfertility. The present review focuses on molecular and functional signatures of bull sperm associated with fertility. Potential roles of functional genomics (proteome, small noncoding RNAs, lipidome, metabolome) on determining male fertility and its potential as a fertility biomarker are discussed. This review provides a better understanding of the molecular signatures of viable and fertile sperm cells and their potential to be used as fertility biomarkers. This information will help uncover the underlying reasons for idiopathic subfertility.

Long Noncoding RNAs: Recent Insights into Their Role in Male Infertility and Their Potential as Biomarkers and Therapeutic Targets

Long noncoding RNAs (lncRNAs) are composed of nucleotides located in the nucleus and cytoplasm; these are transcribed by RNA polymerase II and are greater than 200 nt in length. LncRNAs fulfill important functions in a variety of biological processes, including genome imprinting, cell differentiation, apoptosis, stem cell pluripotency, X chromosome inactivation and nuclear transport. As high throughput sequencing technology develops, a substantial number of lncRNAs have been found to be related to a variety of biological processes, such as development of the testes, maintaining the self-renewal and differentiation of spermatogonial stem cells, and regulating spermatocyte meiosis. These indicate that lncRNAs can be used as biomarkers and potential therapeutic targets for male infertility. However, only a few comprehensive reviews have described the role of lncRNAs in male reproduction. In this paper, we summarize recent findings relating to the role of lncRNAs in spermatogenesis, their potential as biomarkers for male infertility and the relationship between reproductive arrest and transgenerational effects. Finally, we suggest specific targets for the treatment of male infertility from the perspective of lncRNAs.

A Novel Meiosis-Related lncRNA, Rbakdn, Contributes to Spermatogenesis by Stabilizing Ptbp2

Spermatocyte meiosis is the cornerstone of mammalian production. Thousands of long noncoding RNAs (lncRNAs) have been reported to be functional in various cellular processes, but the function of lncRNAs in meiosis remains largely unknown. Here, we profiled lncRNAs in spermatocytes at stage I of meiosis and identified a testis-specific lncRNA, Rbakdn, as a vital regulator of meiosis. Rbakdn is dynamically expressed during meiosis I, and Rbakdn knockdown inhibits meiosis in vitro. Furthermore, Rbakdn knockdown in testes in mice by intratesticular injection disturbs meiosis, reduces testicular volume, and increases apoptosis of spermatocytes, resulting in vacuolation of the seminiferous tubules. Rbakdn can bind to Ptbp2, an RNA-binding protein that is important in the regulation of the alternative splicing of many genes in spermatogenesis. Rbakdn knockdown leads to a decrease in Ptbp2 through the ubiquitination degradation pathway, indicating that Rbakdn maintains the stability of Ptbp2. In conclusion, our study identified an lncRNA, Rbakdn, with a crucial role in meiosis.

Epigenetic transgenerational inheritance, gametogenesis and germline development†

One of the most important developing cell types in any biological system is the gamete (sperm and egg). The transmission of phenotypes and optimally adapted physiology to subsequent generations is in large part controlled by gametogenesis. In contrast to genetics, the environment actively regulates epigenetics to impact the physiology and phenotype of cellular and biological systems. The integration of epigenetics and genetics is critical for all developmental biology systems at the cellular and organism level. The current review is focused on the role of epigenetics during gametogenesis for both the spermatogenesis system in the male and oogenesis system in the female. The developmental stages from the initial primordial germ cell through gametogenesis to the mature sperm and egg are presented. How environmental factors can influence the epigenetics of gametogenesis to impact the epigenetic transgenerational inheritance of phenotypic and physiological change in subsequent generations is reviewed.

Alterations of mRNA and lncRNA profiles associated with the extracellular matrix and spermatogenesis in goats

Objective

Spermatozoa are produced within the seminiferous tubules after sexual maturity. The expression levels of mRNAs and lncRNAs in testicular tissues are different at each stage of testicular development and are closely related to formation of the extracellular matrix (ECM) and spermatogenesis. Therefore, we set out to study the expression of lncRNAs and mRNAs during the different developmental stages of the goat testis.

Methods

We constructed 12 RNA libraries using testicular tissues from goats aged 3, 6, and 12 months, and studied the functions of mRNAs and lncRNAs using the gene ontogeny (GO) and Kyoto encyclopedia of genes and genomes (KEGG) databases. Relationships between differentially expressed genes (DEGs) were analyzed by lncRNA-mRNA co-expression network and protein-protein interaction network (PPI). Finally, the protein expression levels of matrix metalloproteinase 2 (MMP2), insulin-like growth factor 2 (IGF2), and insulin-like growth factor-binding protein 6 (IGFBP6) were detected by western blotting.

Results

We found 23, 8, and 135 differentially expressed lncRNAs and 161, 12, and 665 differentially expressed mRNAs that were identified between 3 vs 6, 6 vs 12, and 3 vs 12 months, respectively. GO, KEGG, and PPI analyses showed that the differential genes were mainly related to the ECM. Moreover, MMP2 was a hub gene and co-expressed with the lncRNA TCONS-0002139 and TCONS-00093342. The results of quantitative reverse-transcription polymerase chain reaction verification were consistent with those of RNA-seq sequencing. The expression trends of MMP2, IGF2, and IGFBP6 protein were the same as that of mRNA, which all decreased with age. IGF2 and MMP2 were significantly different in the 3 vs 6-month-old group (p<0.05).

Conclusion

These results improve our understanding of the molecular mechanisms involved in sexual maturation of the goat testis.

Identification of Novel lncRNA and Differentially Expressed Genes (DEGs) of Testicular Tissues among Cattle, Yak, and Cattle-Yak Associated with Male Infertility

Simple Summary

Cattle-yak is an excellent hybrid of male cattle and female yak, which has many more outstanding production traits, such as better adaptability to high altitudes and better meat quality. However, the male sterility of cattle-yak restricts the utilization of superior heterosis. Few studies have focused on the comprehensive analysis of cattle-yak and its parents, in order to find factors on infertility of the cattle-yak. This study comprehensively analyzed the mRNA and lncRNA expression profiles of testicular tissue samples of cattle, yak, and cattle-yak by RNA-seq technology, and identified some differentially expressed genes that may be related to male sterility of cattle-yak, in order to provide a theoretical basis for solving the problem of breeding work.

Abstract

Cattle-yak is an excellent hybrid of cattle and yak; they are characterized by better meat quality and stronger adaptability of harsh environments than their parents. However, male sterility of cattle-yak lay restraints on the transmission of heterosis. In this study, next generation sequence technology was performed to profile the testicular tissues transcriptome (lncRNA and mRNA) of cattle, yak, and cattle-yak. We analyzed the features and functions of significant differentially expressed genes among the three breeds. There are 9 DE lncRNAs and 46 DE mRNAs with comparisons of cattle, yak, and cattle-yak. Among them, the upregulated targeting genes, such as IGF1 and VGLL3 of cattle-yak lncRNA, may be related to the derangement of spermatocyte maturation and cell proliferation. Similarly, we found that the LDOC1 gene, which is related to the process of cellular apoptosis, is overexpressed in cattle-yak. GO enrichment analysis demonstrated that the cattle-yak is lacking the regulation of fertilization (GO: 0009566), spermatogenesis process (GO: 0007283), male gamete generation process (GO: 0048232), sexual reproduction (GO: 0019953), and multi-organism reproductive process (GO: 0044703), such processes may play important and positive roles in spermatogenesis and fertilization. Furthermore, the KEGG enrichment analysis showed that the upregulated DEGs of cattle-yak most enriched in Apoptosis (ko04210) and Hippo signaling pathway (ko04390), may lead to excessively dead of cell and inhibit cell growth, resulting in obstruction of meiosis and spermatogenesis processes. This study will enable us to deeper understand the mechanism of male cattle-yak infertility.

Microarray profiling of LncRNA expression in the testis of pubertal mice following morning and evening exposure to 1800 MHz radiofrequency fields

In this paper, the chronotoxicity of radiofrequency fields (RF) in the pubertal testis development and the involved molecular pathways were investigated by exposing four-week-old mice to RF (1800 MHz, SAR, 0.50 W/kg) in the morning and evening of each day for three weeks. Then, pathological changes and functional indices within the testis were determined. We also used a long non-coding RNA (lncRNA) microarray and GO/KEGG pathway analyses to determine lncRNA expression profiles and predict their potential functions. The cis and trans regulation of lncRNAs were investigated, and an interaction network was constructed using Cytoscape software. RF exposure led to a range of pathological changes in the testes of adolescent mice, as testicular weights and daily sperm productions decreased, and the testosterone secretion reduced. Furthermore, RF induced dysregulation in the expression of testicular lncRNAs. We identified 615 and 183 differentially expressed lncRNAs that were associated with morning and evening exposure to RF, respectively. From 15 differential expression lncRNAs both in morning RF group and evening RF group, we selected 6 lncRNAs to be validated by quantitative reverse transcription PCR (qRT-PCR). The differentially expressed lncRNAs induced by morning RF exposure were highly correlated with many different pathways, including Fanconi syndrome, metabolic processes, cell cycle, DNA damage, and DNA replication. Trans-regulation analyses further showed that differentially expressed lncRNAs were involved in multiple transcription factor-regulated pathways, such as TCFAP4, NFkB, HINFP, TFDP2, FoxN1, and PAX5. These transcription factors have all been shown to be involved in the modulation of testis development, cell cycle progression, and spermatogenesis. These findings suggest that the extent to which 1800 MHz RF induced toxicity in the testes and changed the expression of lncRNAs showed differences between morning exposure and evening exposure. These data indicate that differentially expressed lncRNAs play crucial roles in the RF exposure damage to the developing pubertal testis. Collectively, our findings provide a better understanding of the mechanisms underlying the toxic effects of RF exposure on testicular development.

Integrated Analysis of Long Non-Coding RNA and mRNA Expression Profiles in Testes of Calves and Sexually Mature Wandong Bulls (Bos taurus)

The mRNAs and long non-coding RNAs axes are playing a vital role in the regulating of post-transcriptional gene expression. Thereby, elucidating the expression pattern of mRNAs and long non-coding RNAs underlying testis development is crucial. In this study, mRNA and long non-coding RNAs expression profiles were investigated in 3-month-old calves and 3-year-old mature bulls' testes by total RNA sequencing. Additionally, during the gene level analysis, 21,250 mRNAs and 20,533 long non-coding RNAs were identified. As a result, 7908 long non-coding RNAs (p-adjust < 0.05) and 5122 mRNAs (p-adjust < 0.05) were significantly differentially expressed between the distinct age groups. In addition, gene ontology and biological pathway analyses revealed that the predicted target genes are enriched in the lysine degradation, cell cycle, propanoate metabolism, adherens junction and cell adhesion molecules pathways. Correspondingly, the RT-qPCR validation results showed a strong consistency with the sequencing data. The source genes for the mRNAs (CCDC83, DMRTC2, HSPA2, IQCG, PACRG, SPO11, EHHADH, SPP1, NSD2 and ACTN4) and the long non-coding RNAs (COX7A2, COX6B2, TRIM37, PRM2, INHBA, ERBB4, SDHA, ATP6VOA2, FGF9 and TCF21) were found to be actively associated with bull sexual maturity and spermatogenesis. This study provided a comprehensive catalog of long non-coding RNAs in the bovine testes and also offered useful resources for understanding the differences in sexual development caused by the changes in the mRNA and long non-coding RNA interaction expressions between the immature and mature stages.

Analysis of Transcripts of Uncertain Coding Potential Using RNA Sequencing During the Preattachment Phase in Goat Endometrium

Transcripts of uncertain coding potential (TUCP) are part of long noncoding RNAs, which include short open reading frames and could be translated into small peptides. In recent years, a growing number of TUCPs has been implicated in multiple biological activities, such as embryogenesis and transcriptional regulation. However, the abundance of TUCPs and their roles in goat endometrium during pregnancy recognition (day 16) remain undocumented. In this study, bioinformatics analyses were conducted to identify the differentially expressed (DE) TUCPs between pregnant animals and corresponding nonpregnant controls. A total of 5551 TUCPs were identified; 114 TUCPs were DE in goat endometrium, of which 74 TUCPs were upregulated in pregnant endometrium, whereas 40 TUCPs were downregulated. The related genes of TUCP were predicted by using coexpression and colocalization methods. In summary, 419 genes were predicted by colocalization, and 9464 genes were predicted by coexpression. The kyoto encyclopedia of genes and genomes (KEGG) and gene ontology (GO) analysis showed that TUCPs, which are highly expressed in pregnant endometrium, were mainly associated with endometrial remodeling, nutrient synthesis, and transportation. However, TUCPs that were lowly expressed in pregnant endometrium were mainly associated with immune tolerance, which is necessary for the protection and development of the embryo in the uterus. These findings may be used for the comparative analysis of TUCP transcripts in endometrium and assist in the selection of applicable candidate genes associated with embryo implantation for further functional analyses.

Dynamic expression and functional analysis of circular RNA in the gonads of Chinese soft-shelled turtles (Pelodiscus sinensis)

Circular RNA (circRNA) is a noncoding RNA that can regulate a variety of biological processes. CircRNAs can regulate gene expression posttranscriptionally by acting as microRNA sponges. Many turtle species are remarkable organisms due to their reproductive processes. However, information on circRNA in the gonads of turtles is limited. In this study, 6, 121 circRNAs were identified in the testes and ovaries of Chinese soft-shelled turtles (Pelodiscus sinensis) using the Illumina platform, and 710 circRNAs were significantly differentially expressed (DE). The DE circRNAs included 541 upregulated and 169 downregulated circRNAs in the testes. GO and KEGG pathway analysis indicated that the DE circRNAs were enriched in several signaling pathways, including GnRH, Wnt, FoxO, Progesterone mediated oocyte maturation, and mTOR signaling pathways. Five DE circRNAs were randomly selected, and their relative expression levels in ovaries and testes were detected by quantitative real-time PCR. All of these circRNAs were differentially expressed. In addition, 9, 883 interactions between circRNAs and miRNAs were predicted in the turtles. Target genes of the miRNAs include a range of genes regulating gonadal development. Seven ceRNA networks (DE circRNAs-DE miRNAs-DE mRNAs), including 7 DE circRNAs, 11 DE miRNAs and 20 DE mRNAs, were constructed. The networks included Cdc6, the miR-1 family, the miR-203 family, and the miR-302 family. The expression profile of gonadal circRNAs might help to elucidate the roles of nonprotein coding RNAs in turtle gonadal development.

LncRNAs induce oxidative stress and spermatogenesis by regulating endoplasmic reticulum genes and pathways

Oligozoospermia or low sperm count is a leading cause of male infertility worldwide. Despite decades of work on non-coding RNAs (ncRNAs) as regulators of spermatogenesis, fertilization, and male fertility, the literature on the function of long non-coding RNAs (lncRNAs) in human oligozoospermia is scarce. We integrated lncRNA and mRNA sequencing data from 12 human normozoospermic and oligozoospermic samples and comprehensively analyzed the function of differentially expressed lncRNAs (DE lncRNAs) and mRNAs (DE mRNAs) in male infertility. The target genes of DE lncRNAs were identified using a Gaussian graphical model. Gene ontology terms and Kyoto Encyclopedia of Genes and Genomes pathways were primarily enriched in protein transport and localization to the endoplasmic reticulum (ER). The lncRNA–mRNA co-expression network revealed cis- and trans-regulated target genes of lncRNAs. The transcriptome data implicated DE lncRNAs and DE mRNAs and their target genes in the accumulation of unfolded proteins in sperm ER, PERK-EIF2 pathway-induced ER stress, oxidative stress, and sperm cell apoptosis in individuals with oligozoospermia. These findings suggest that the identified lncRNAs and pathways could serve as effective therapeutic targets for male infertility.

Effect and in silico characterization of genetic variants associated with severe spermatogenic disorders in a large Iberian cohort

BACKGROUND

Severe spermatogenic failure (SpF) represents the most extreme manifestation of male infertility, as it decreases drastically the semen quality leading to either severe oligospermia (SO, <5 million spermatozoa/mL semen) or non-obstructive azoospermia (NOA, complete lack of spermatozoa in the ejaculate without obstructive causes).

OBJECTIVES

The main objective of the present study is to analyze in the Iberian population the effect of 6 single-nucleotide polymorphisms (SNPs) previously associated with NOA in Han Chinese through genome-wide association studies (GWAS) and to establish their possible functional relevance in the development of specific SpF patterns.

MATERIALS AND METHODS

We genotyped 674 Iberian infertile men (including 480 NOA and 194 SO patients) and 1058 matched unaffected controls for the GWAS-associated variants PRMT6-rs12097821, PEX10-rs2477686, CDC42BPA-rs3000811, IL17A-rs13206743, ABLIM1-rs7099208, and SOX5-rs10842262. Their association with SpF, SO, NOA, and different NOA phenotypes was evaluated by logistic regression models, and their functional relevance was defined by comprehensive interrogation of public resources.

RESULTS

ABLIM1-rs7099208 was associated with SpF under both additive (OR = 0.86, p = 0.036) and dominant models (OR = 0.78, p = 0.026). The CDC42BPA-rs3000811 minor allele frequency was significantly increased in the subgroup of NOA patients showing maturation arrest (MA) of germ cells compared to the remaining NOA cases under the recessive model (OR = 4.45, p = 0.044). The PEX10-rs2477686 SNP was associated with a negative testicular sperm extraction (TESE) outcome under the additive model (OR = 1.32, p = 0.034). The analysis of functional annotations suggested that these variants affect the testis-specific expression of nearby genes and that lincRNA may play a role in SpF.

CONCLUSIONS

Our data support the association of three previously reported NOA risk variants in Asians (ABLIM1-rs7099208, CDC42BPA-rs3000811, and PEX10-rs2477686) with different manifestations of SpF in Iberians of European descent, likely by influencing gene expression and lincRNA deregulation.

Predicted gene 31453 (Gm31453) and the gene encoding carboxypeptidase A5 (Cpa5) are not essential for spermatogenesis and male fertility in the mouse

Numerous long non-coding (lnc) RNAs are highly enriched or exclusively expressed in the mammalian testis, even in spermatids. Spermatid perinuclear RNA-binding protein (STRBP) can bind many RNAs, and loss of STRBP impairs male fertility. However, the functions of lncRNAs interacting with STRBP are unknown. In this study, the roles of one STRBP-interacting lncRNA, namely predicted gene 31453 (Gm31453), and its potential target gene encoding carboxypeptidase A5 (Cpa5) in spermatogenesis were determined using gene-knockout (KO) mice. Gm31453 and Cpa5 are located adjacent to each other on the same chromosome and are highly expressed in the testis. Gm31453 and Cpa5 are primarily expressed from secondary spermatocytes to elongated spermatids, implying their involvement in spermiogenesis. Although deletion of Gm31453 disturbed the expression of both its target and interacting gene, as indicated by decreased Cpa5 and increased Strbp mRNA levels, both Gm31453- and Cpa5-KO mice showed normal spermatogenesis and fertility, and had no detectable abnormalities in terms of testicular and epididymal development, sperm production morphology or motility, pregnancy rate or litter size. Thus, Gm31453 and Cpa5 are dispensable for spermatogenesis and male fertility in mice. Their involvement in spermatogenesis may be a fine-tuning role, regulating gene expression at the molecular level.

Deletion of lncRNA5512 has no effect on spermatogenesis and reproduction in mice

Long non-coding (lnc) RNAs are a series of RNAs longer than 200 nucleotides that do not code for protein products. Whole-genome expression profiles of lncRNAs suggest that they play important roles in spermatogenesis because they are particularly abundant in testes. However, most of their characteristics and functions remain unclear. The aim of this study was to define the function of lncRNA5512, which is abundant in spermatocytes and round spermatids, in mouse fertility invivo. To investigate this we generated lncRNA5512-knockout mice by clustered regularly interspaced palindromic repeats (CRISPR)/CRISPR-associated protein (Cas) 9 technology. Knockout mice showed normal spermatogenesis and fertility, and had no detectable abnormalities. This indicates that lncRNA5512 does not affect mouse fertility despite its high expression in the testes. Its specific localisation in spermatocytes and round spermatids suggests that it could be a useful marker for the identification of spermatocytes and round spermatids in mouse testes.

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.

The effects of NONRATT008453.2 on autophagy in genital tubercle fibroblasts of rats with hypospadias induced by dibutyl phthalate

BACKGROUND

Hypospadias is a common birth defect that might be caused by inadequate fusion of the urethral folds in the process of male external genital development. We intended to discover the crucial long noncoding RNAs (lncRNAs) regulating autophagy from the gene expression profile of the genital tubercle (GT) of dibutyl phthalate (DBP) induced hypospadiac rats.

METHODS

Whole transcriptome resequencing was used to determine the expression of the total RNA in GTs and cultured fibroblasts obtained from GTs of DBP-induced hypospadiac male rat fetuses. Autophagosomes and autolysosomes were examined under a transmission electron microscope after overexpression of lncRNA NONRATT008453.2 in the fibroblasts by adenovirus transfection. Finally, the protein expression levels of Atg5, Beclin-1, Atg7, and the LC3A/B-II:LC3A/B-I ratio were detected in the fibroblasts by western blotting.

RESULTS

NONRATT008453.2 suppressed autophagy by promoting the expression of Atg7, but inhibited the expressions of Atg5, Beclin-1, and the LC3A/B-II:LC3A/B-I ratio in the GT fibroblasts.

CONCLUSIONS

NONRATT008453.2 may have an influence on autophagy in the fibroblasts of the GT in DBP-induced hypospadiac rats.

Regulation of Human Spermatogenesis

Human spermatogenesis (HS) is an intricate network of sequential processes responsible for the production of the male gamete, the spermatozoon. These processes take place in the seminiferous tubules (ST) of the testis, which are small tubular structures considered the functional units of the testes. Each human testicle contains approximately 600-1200 STs [1], and are capable of producing up to 275 million spermatozoa per day [2].

Analysis and Screening of Reproductive Long Non-coding RNAs Through Genome-Wide Analyses of Goat Endometrium During the Pre-attachment Phase

Reproduction in goat is highly impeded by implantation failure. Of concern, the underlying mechanism leading to embryo implantation remains unclear. In this study, deep sequencing was employed through strand-specific Ribo-Zero RNA-Seq to characterize transcriptome changes in the endometrium during the maternal recognition of pregnancy. A total of 996 differential transcripts (115 lncRNAs and 881 mRNAs) existing between the pregnant and non-pregnant endometrium were revealed through bioinformatics analysis. The screening was performed on lncRNAs (XR_001918173.1, LNC_002760, and LNC_000599) and LNC_009053, to determine their potential role in regulating the synthesis of retinol and endometrium remolding through the proteasome pathway, respectively. The hypothesis of whether certain lncRNAs, namely, LNC_007223, LNC_005256, and LNC_010092 could play important roles in embryo implantation was tested. These novel findings are of paramount relevance to further elucidate the molecular mechanisms of embryo implantation and uncover new targets to improve goat reproduction.

Analysis of lncRNA Expression Profile during the Formation of Male Germ Cells in Chickens

Simple Summary

The differentiation of germ cells plays an important role in sex differentiation in poultry. Therefore, it is necessary for us to explore the potential regulators in the process of germ cell development. In this study, RNA-seq was used to detect the expression profile of long non-coding RNAs (lncRNAs) in chicken embryonic stem cells (ESCs), primordial germ cells (PGCs) and spermatogonial stem cells (SSCs). The results showed that a total of 296, 280 and 357 differentially expressed lncRNAs (DELs) were screened in ESCs vs. PGCs, ESCs vs. SSCs and PGCs vs. SSCs, respectively. Functional analysis of the target genes of DELs showed that autophagy, Wnt/β-catenin, TGF-β, Notch and ErbB signaling pathways were involved in the differentiation process of male germ cells and, moreover, XLOC_612026, XLOC_612029, XLOC_240662, XLOC_362463, XLOC_023952, XLOC_674549, XLOC_160716, ALDBGALG0000001810, ALDBGALG0000002986, XLOC_657380674549, XLOC_022100 and XLOC_657380 were predicted to be the key lncRNAs in this process. Our findings could not only supply scientific data for constructing the gene regulatory network of germ cell development, but also provide new ideas for further optimizing the induction efficiency of germ cells in vitro.

Abstract

Germ cells have an irreplaceable role in transmitting genetic information from one generation to the next, and also play an important role in sex differentiation in poultry, while little is known about epigenetic factors that regulate germ cell differentiation. In this study, RNA-seq was used to detect the expression profiles of long non-coding RNAs (lncRNAs) during the differentiation of chicken embryonic stem cells (ESCs) into spermatogonial stem cells (SSCs). The results showed that a total of 296, 280 and 357 differentially expressed lncRNAs (DELs) were screened in ESCs vs. PGCs, ESCs vs. SSCs and PGCs vs. SSCs, respectively. Gene Ontology (GO) and KEGG enrichment analysis showed that DELs in the three cell groups were mainly enriched in autophagy, Wnt/β-catenin, TGF-β, Notch and ErbB and signaling pathways. The co-expression network of 37 candidate DELs and their target genes enriched in the biological function of germ cell development showed that XLOC_612026, XLOC_612029, XLOC_240662, XLOC_362463, XLOC_023952, XLOC_674549, XLOC_160716, ALDBGALG0000001810, ALDBGALG0000002986, XLOC_657380674549, XLOC_022100 and XLOC_657380 were the key lncRNAs in the process of male germ cell formation and, moreover, the function of these DELs may be related to the interaction of their target genes. Our findings preliminarily excavated the key lncRNAs and signaling pathways in the process of male chicken germ cell formation, which could be helpful to construct the gene regulatory network of germ cell development, and also provide new ideas for further optimizing the induction efficiency of germ cells in vitro.

Current mechanistic perspectives on male reproductive toxicity induced by heavy metals

Environmental and occupational exposures to heavy metals have led to various deleterious damages to the biological system of which infertility is one of them. Infertility is a global public health concern, affecting 15% of all couples of reproductive age. Out of the 100% cases of reported infertility among couples, 40% of the cases are related to male factors; including decreased semen quality. This review focuses on the recent mechanistic perspectives of heavy metal-induced male reproductive toxicity. The associated toxic metal-mediated mechanisms of male reproductive toxicity include ion mimicry, disruption of cell signaling pathways, oxidative stress, altered gene expression, epigenetic regulation of gene expression, apoptosis, disruption of testis/blood barrier, inflammation and endocrine disruption. The current literature suggests that non-coding RNAs (ncRNAs) mediate paternal intergenerational epigenetic inheritance and thus has a direct functional importance, as well as possess novel biomarker potential, for male reproductive toxicity. To identify the specific ncRNAs with the most profound impacts on heavy metal-induced male reproductive toxicity should be thrust of further research.

Analysis of Long Noncoding RNA and mRNA Expression Profiles of Testes with High and Low Sperm Motility in Domestic Pigeons (Columba livia)

Sperm motility is one of the most important indicators in assessing semen quality, and it is used to evaluate poultry fertility. Many long noncoding RNAs (lncRNAs) and mRNAs are involved in regulating testis development and spermatogenesis. In this study, we employed RNA sequencing to analyse the testis transcriptome (lncRNA and mRNA) of ten pigeons with high and low sperm motility. In total, 46,117 mRNAs and 17,463 lncRNAs were identified, of which 2673 mRNAs and 229 lncRNAs (P < 0.05) were significantly differentially expressed (DE) between the high and low sperm motility groups. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) annotation analysis showed that target genes of DE lncRNAs and DE mRNAs were related to calcium ion binding, ATP binding, and spermatogenesis. Moreover, we found that UBB, a target gene of lncRNA MSTRG.7787.5, was involved in germ cell development. Our study provided a catalogue of lncRNAs and mRNAs associated with sperm motility, and they deserve further study to deepen the understanding of biological processes in the pigeon testis.

Differential Expression of Long Noncoding RNAs and Their Function-Related mRNAs in the Peripheral Blood of Allergic Rhinitis Patients

BACKGROUND

The mechanism of long noncoding RNAs (lncRNAs) involved in the development of allergic rhinitis (AR) remains unclear.

OBJECTIVE

We investigated the mechanism by which differentially expressed lncRNAs contribute to pathogenesis of AR.

METHODS

Expression profiles of lncRNAs and mRNAs were analyzed by microarray detection from the blood samples of 3 AR patients and 3 control subjects, and the main lncRNAs were verified by quantitative real-time polymerase chain reaction (qRT-PCR) in the peripheral blood of 16 AR patients and 18 control subjects. GO (Gene_Ontology), Pathway, and Disease analysis of differentially expressed lncRNAs and mRNAs, and transcription factor prediction analysis were performed to explore synergistic effect of differentially expressed lncRNAs and their function-related mRNAs on AR pathogenesis.

RESULTS

Thirty-one lncRNAs were differentially expressed in the peripheral blood from AR patients, and 4 of the 5 most differentially expressed lncRNAs had significantly higher levels in AR patients than in control subjects by qRT-PCR analysis. A lncRNA-mRNA coexpression network analysis identified 16 pairs of positive correlations between the 4 lncRNAs and coexpressed mRNAs. GO, Pathway, and Disease analyses indicated that the 4 lncRNAs were correlated with 7 mRNAs enriched in terms of inflammation, immune response, and allergic diseases. Transcription factor prediction results suggested that Oct-1, AP-1, NF-kappaB, and c-Rel play key roles in the pathogenesis of AR mediated by lncRNAs.

CONCLUSION

Our results provide new insights into how lncRNAs and their function-related mRNAs might contribute to AR.

Dysregulation of lncRNA and circRNA Expression in Mouse Testes after Exposure to Triptolide

BACKGROUND

Triptolide has been shown to exert various pharmacological effects on systemic autoimmune diseases and cancers. However, its severe toxicity, especially reproductive toxicity, prevents its widespread clinical use for people with fertility needs. Noncoding RNAs including lncRNAs and circRNAs are novel regulatory molecules that mediate a wide variety of physiological activities; they are crucial for spermatogenesis and their dysregulation might cause male infertility. However, whether they are involved in triptolide-induced reproductive toxicity is completely unknown.

METHODS

After exposure of mice to triptolide, the total RNAs were used to investigate lncRNA/circRNA/mRNA expression profiles by strand-specific RNA sequencing at the transcriptome level to help uncover RNA-related mechanisms in triptolide-induced toxicity.

RESULTS

Triptolide significantly decreased testicular weight, damaged testis and sperm morphology, and reduced sperm motility and density. Remarkable deformities in sperm head and tail were also found in triptolide-exposed mice. At the transcriptome level, the triptolide-treated mice exhibited aberrant expression profiles of lncRNAs/circRNAs/mRNAs. Gene Ontology and pathway analyses revealed that the functions of the differentially expressed lncRNA targets, circRNA cognate genes, and mRNAs were closely linked to many processes involved in spermatogenesis. In addition, some lncRNAs/circRNAs were greatly upregulated or inducibly expressed, implying their potential value as candidate markers for triptolide-induced male reproductive toxicity.

CONCLUSION

This study provides a preliminary database of triptolide-induced transcriptome, promotes understanding of the reproductive toxicity of triptolide, and highlights the need for research on increasing the medical efficacy of triptolide and decreasing its toxicity.

Molecular mechanisms underlying nickel nanoparticle induced rat Sertoli-germ cells apoptosis

This study was done on SD rat Sertoli-germ co-cultured cells (Sertoli-germ cells) with nickel nanoparticles (Ni NPs). A series of investigations were performed to observe the role of Ni NPs on the apoptosis of Sertoli-germ cells and to explore the long-chain non-coding RNA (lncRNA) functions on key signaling pathways and regulatory mechanisms. We found that Ni NPs had an apoptotic effect on Sertoli-germ cells. Ni NPs-induced apoptosis in Sertoli-germ cells involves the LOC102551356, Insulin-like growth factor-binding protein 3 (Igfbp3), and mitochondrial apoptosis pathway. The specific mechanism may be: during the process of Ni NPs-induced apoptosis in Sertoli-germ cells, the expression of LOC102551356 is up-regulated, and LOC102551356 activates the mitochondrial apoptosis pathway through targeted regulation of the target gene Igfbp3 in the P53-reduced apoptosis pathway. The results of this study will be important for the safety evaluation of Ni NPs in the future, and could provide an approach for the prevention or alleviation of the toxicity induced by Ni NPs.

Comprehensive analysis of long noncoding RNA and mRNA expression patterns in sheep testicular maturation

Long noncoding RNAs (LncRNAs) have been identified as important regulators of testis development; however, their expression patterns and roles in sheep are not yet clear. Thus, we used stranded specific RNA-seq to profile the testis transcriptome (lncRNAs and mRNAs) in premature and mature sheep. Hormone levels and the testis index were examined, and histological analyses were performed at five stages of testis development, 5-day-old (D5), 3-month-old (3M), 6-month-old (6M), 9-month-old (9M), and 2-year-old (2Y), the results of which indicate a significant difference in hormone levels and testis morphometries between the 3M and 9M stages (P < 0.05). Based on the comparison between 3M and 9M samples, we found 1,118 differentially expressed (DE) lncRNAs and 7,253 DE mRNAs in the testes, and qRT-PCR analysis showed that the results correlated well with the transcriptome data. Furthermore, we constructed lncRNA-protein-coding gene interaction networks. Forty-seven DE lncRNA-targeted genes enriched for male reproduction were obtained by cis- and trans-acting; 51 DE lncRNAs and 45 cis-targets, 2 DE lncRNAs and 2 trans-targets were involved in this network. Of these, 5 lncRNAs and their targets, PRKCD, NANOS3, SERPINA5, and CYP19A1, were enriched for spermatogenesis and male gonad development signaling pathways. We further examined the expression levels of 5 candidate lncRNAs and their target genes during testis development. Lastly, the interaction of lncRNA TCONS__00863147 and its target gene PRKCD was validated in vitro in sheep Leydig cells. This study provides a valuable resource for further study of lncRNA function in sheep testis development and spermatogenesis.

A history of why fathers' RNA matters

Having been debated for many years, the presence and role of spermatozoal RNAs is resolving, and their contribution to development is now appreciated. Data from different species continue show that sperm contain a complex suite of coding and noncoding RNAs that play a role in an individual's life course. Mature sperm RNAs provide a retrospective of spermatogenesis, with their presence and abundance reflecting sperm maturation, fertility potential, and the paternal contribution to the developmental path the offspring may follow.Sperm RNAs delivered upon fertilization provide some of the initial contacts with the oocyte, directly confront the maternal with the paternal contribution as a prelude to genome consolidation. Following syngamy, early embryo development may in part be modulated by paternal RNAs that can include epidydimal passengers. This provides a direct path to relay an experience and then initiate a paternal response to the environment to the oocyte and beyond. Their epigenetic impact is likely felt prior to embryonic genome activation when the population of sperm delivered transcripts markedly changes. Here, we review the insights gained from sperm RNAs over the years, the subtypes, and the caveats of the RNAs described. We discuss the role of sperm RNAs in fertilization and embryo development, and their possible mechanism(s) influencing offspring phenotype. Approaches to meet the future challenges as the study of sperm RNAs continues, include, elucidating the potential mechanisms underlying how paternal allostatic load, the constant adaptation of health to external conditions, may be relayed by sperm RNAs to affect future generations.

Non-coding RNA regulation in reproduction: Their potential use as biomarkers

Non-coding RNAs (ncRNAs) are crucial regulatory elements in most biological processes and reproduction is also controlled by them. The different types of ncRNAs, as well as the high complexity of these regulatory pathways, present a complex scenario; however, recent studies have shed some light on these questions, discovering the regulatory function of specific ncRNAs on concrete reproductive biology processes. This mini review will focus on the role of ncRNAs in spermatogenesis and oogenesis, and their potential use as biomarkers for reproductive diseases or for reproduction success.

DAZL is a master translational regulator of murine spermatogenesis

Expression of DAZ-like (DAZL) is a hallmark of vertebrate germ cells, and is essential for embryonic germ cell development and differentiation, yet the gametogenic function of DAZL has not been fully characterized and most of its in vivo direct targets remain unknown. We showed that postnatal stage-specific deletion of Dazl in mouse germ cells did not affect female fertility, but caused complete male sterility with gradual loss of spermatogonial stem cells, meiotic arrest and spermatid arrest. Using the genome-wide high-throughput sequencing of RNAs isolated by cross-linking immunoprecipitation and mass spectrometry approach, we found that DAZL bound to a large number of testicular mRNA transcripts (at least 3008) at the 3'-untranslated region and interacted with translation proteins including poly(A) binding protein. In the absence of DAZL, polysome-associated target transcripts, but not their total transcripts, were significantly decreased, resulting in a drastic reduction of an array of spermatogenic proteins and thus developmental arrest. Thus, DAZL is a master translational regulator essential for spermatogenesis.

Long non-coding RNA: its evolutionary relics and biological implications in mammals: a review

The central dogma of gene expression propounds that DNA is transcribed to mRNA and finally gets translated into protein. Only 2–3% of the genomic DNA is transcribed to protein-coding mRNA. Interestingly, only a further minuscule part of genomic DNA encodes for long non-coding RNAs (lncRNAs) which are characteristically more than 200 nucleotides long and can be transcribed from both protein-coding (e.g. H19 and TUG1) as well as non-coding DNA by RNA polymerase II. The lncRNAs do not have open reading frames (with some exceptions), 3`-untranslated regions (3’-UTRs) and necessarily these RNAs lack any translation-termination regions, however, these can be spliced, capped and polyadenylated as mRNA molecules. The flexibility of lncRNAs confers them specific 3D-conformations that eventually enable the lncRNAs to interact with proteins, DNA or other RNA molecules via base pairing or by forming networks. The lncRNAs play a major role in gene regulation, cell differentiation, cancer cell invasion and metastasis and chromatin remodeling. Deregulation of lncRNA is also responsible for numerous diseases in mammals. Various studies have revealed their significance as biomarkers for prognosis and diagnosis of cancer. The aim of this review is to overview the salient features, evolution, biogenesis and biological importance of these molecules in the mammalian system.

Epigenetic reprogramming during spermatogenesis and male factor infertility

Infertility is an often devastating diagnosis encountered by around one in six couples who are trying to conceive. Moving away from the long-held belief that infertility is primarily a female issue, it is now recognised that half, if not more, of these cases may be due to male factors. Recent evidence has suggested that epigenetic abnormalities in chromatin dynamics, DNA methylation or sperm-borne RNAs may contribute to male infertility. In light of advances in deep sequencing technologies, researchers have been able to increase the coverage and depth of sequencing results, which in turn has allowed more comprehensive analyses of spermatozoa chromatin dynamics and methylomes and enabled the discovery of new subsets of sperm RNAs. This review examines the most current literature related to epigenetic processes in the male germline and the associations of aberrant modifications with fertility and development.

Long non-coding RNAs could act as vectors for paternal heredity of high fat diet-induced obesity

Long non-coding RNAs (lncRNAs) play an important role in epigenetic regulation, and abnormalities may lead to male infertility. To investigate whether lncRNAs are involved in intergenerational inheritance of obesity and obesity-induced decline in fertility, we divided mice into obesity (F0 mice fed a high-fat diet, F0-HFD) and non-obese (F0 mice fed normal chow, F0-NC) model groups and their male offspring (F1-HFD and F1-NC, respectively). We examined the differences in the expression levels of lncRNAs and mRNAs in the F0-HFD/F0-NC and F1-HFD/F1-NC groups. The results revealed similar expression patterns in the F1-HFD/F0-HFD groups at both the lncRNA and mRNA levels. The maximum difference in the lncRNA expression was observed between the F0-HFD and F0-NC groups. The differentially expressed lncRNA targets and mRNAs identified in our study are mainly involved in GnRH signalling pathway, metabolic process, and Hippo signalling pathway; similarly expressed lncRNAs and mRNAs in F1-HFD/F0-HFD are closely linked with G-protein coupled receptor signalling pathway, pancreatic polypeptide receptor activity, and lysine biosynthesis, which may play an important role in the molecular mechanism of intergenerational inheritance of obesity. Furthermore, potential genes that might play important roles in the pathogenesis of obesity-related low fertility were revealed by lncRNA-and mRNA-interaction studies based on the microarray expression profiles. In conclusion, we found that lncRNA could be involved in obesity-induced infertility by expressing abnormalities, which could act as genetic vectors of paternal inheritance of obesity.

LncRNA Gm2044 highly expresses in spermatocyte and inhibits Utf1 translation by interacting with Utf1 mRNA

Spermatogenesis is a process which includes the following phases: spermatogonial stem cell proliferation and differentiation, spermatogonia, spermatocyte, spermatid and mature sperm. Spermatogenic failure is the important factor resulting in male infertility. Recent studies showed that long noncoding RNA (lncRNA) have been found to be involved in the regulation of male reproduction. However, lncRNA associated with spermatogenesis and their mechanisms of action are unclear. The aim of this study is to explore the role and molecular mechanism of lncRNA in spermatogenesis. LncRNA microarray of germ cells and bioinformatic analysis showed lncRNA Gm2044 may play potential roles in spermatogenesis. The expression level of RNA and protein were analyzed by RT-qPCR and western blotting, respectively. The interaction of lncRNA with mRNA was detected by RNA pull down and cellular proliferation was measured using CCK-8 reagent. Testis-enriched lncRNA Gm2044 is abundant in mouse spermatocytes. Gm2044 can suppress the translation of adjacent spermatogenesis-related gene Utf1 by interacting with Utf1 mRNA. Furthermore, the proliferation of mouse spermatogonia GC-1 cell line and spermatocyte GC-2 cell line was inhibited by Gm2044.

CONCLUSION

LncRNA Gm2044 was identified to inhibit Utf1 mRNA translation and play important roles in spermatogenesis.

High-Sensitivity and High-Resolution In Situ Hybridization of Coding and Long Non-coding RNAs in Vertebrate Ovaries and Testes

Background

Subcellular localization of coding and non-coding RNAs has emerged as major regulatory mechanisms of gene expression in various cell types and many organisms. However, techniques that enable detection of the subcellular distribution of these RNAs with high sensitivity and high resolution remain limited, particularly in vertebrate adult tissues and organs. In this study, we examined the expression and localization of mRNAs encoding Pou5f1/Oct4, Mos, Cyclin B1 and Deleted in Azoospermia-like (Dazl) in zebrafish and mouse ovaries by combining tyramide signal amplification (TSA)-based in situ hybridization with paraffin sections which can preserve cell morphology of tissues and organs at subcellular levels. In addition, the distribution of a long non-coding RNA (lncRNA), lncRNA-HSVIII, in mouse testes was examined by the same method.

Results

The mRNAs encoding Mos, Cyclin B1 and Dazl were found to assemble into distinct granules that were distributed in different subcellular regions of zebrafish and mouse oocytes, suggesting conserved and specific regulations of these mRNAs. The lncRNA-HSVIII was first detected in the nucleus of spermatocytes at prophase I of the meiotic cell cycle and was then found in the cytoplasm of round spermatids, revealing expression patterns of lncRNA during germ cell development. Collectively, the in situ hybridization method demonstrated in this study achieved the detection and comparison of precise distribution patterns of coding and non-coding RNAs at subcellular levels in single cells of adult tissues and organs.

Conclusions

This high-sensitivity and high-resolution in situ hybridization is applicable to many vertebrate species and to various tissues and organs and will be useful for studies on the subcellular regulation of gene expression at the level of RNA localization.

Electronic supplementary material

The online version of this article (10.1186/s12575-018-0071-z) contains supplementary material, which is available to authorized users.

Circular RNAs: biogenesis, expression and their potential roles in reproduction

Unlike other non-coding RNAs (ncRNAs), circular RNA (circRNA) is generally presented as a covalently linked circle lacking both a 5' cap and a 3' tail. circRNAs were thought to be spliced intermediates, byproducts, or products of abnormal RNA splicing events. However, the high-throughput sequencing technology coupled with bioinformatics has recently uncovered thousands of endogenous circRNAs in cells of many different species. These circRNAs show various features, such as abundant expression, evolutionary conservation, cell- or tissue-specific expression, and a higher resistance to degradation caused by exonuclease or ribonuclease (RNase), suggesting their potentially biological significance. However, the function of these circRNAs, their mechanism of action, and the regulation of their biogenesis and degradation remains largely unclear. The current research and findings of circRNA in the context of reproduction will be reviewed. Additionally, the perspectives of circRNAs in the field will be discussed.

Genome-wide analysis and functional prediction of long non-coding RNAs in mouse uterus during the implantation window

Establishment of the receptive uterus is a crucial step for embryo implantation. In this study, the expression profiles and characterization of long non-coding RNAs (lncRNAs) in pregnant mouse uteri on day 4, day 5 at implantation sites and inter-implantation sites were conducted using RNA-seq. A total of 7,764 putative lncRNA transcripts were identified, including 6,179 known lncRNA transcripts and 1,585 novel lncRNA transcripts. Bioinformatics analysis of the cis and trans lncRNA targets showed that the differentially expressed lncRNAs were mainly involved in tissue remodelling, immune response and metabolism-related processes, indicating that lncRNAs could be involved in the regulation of embryo implantation. We also discovered that differentially expressed lncRNAs might regulate multiple signalling pathways that play an important role in the regulation of embryo implantation. In addition, nine known lncRNAs and four novel lncRNAs were randomly selected and validated by qRT-PCR. The expression of Tug1, Neat1, Gas5, Malat1, H19 and Rmst were significantly regulated in the mouse uterus during the implantation window. Our results are the first to systematically identify lncRNAs in the mouse uterus and provide a catalogue of lncRNAs for further understanding their functions in pregnant mouse uteri during the implantation window.

Analyses of Long Non-Coding RNA and mRNA profiling using RNA sequencing in chicken testis with extreme sperm motility

Sperm motility is the most important indicator in evaluating roosters' fecundity. However, the genetic mechanisms underlying chicken sperm motility is not yet clear. Long non-coding RNA (lncRNA) play epigenetic roles in reproduction. In this study, RNA sequencing was employed to profile the testis transcriptome (lncRNA and mRNA) of six Beijing-you cocks divergent in sperm motility. In total, 2,597 lncRNAs were identified in the chicken testis, including 1,267 lincRNAs, 975 anti-sense lncRNAs, and 355 intronic lncRNAs. They shared similar features with previous studies. Of these lncRNAs, 124 were differentially expressed. Among 17,690 mRNAs detected in this study, 544 were differentially expressed, including a bunch of genes with known functions on sperm motility. GO annotation analysis revealed these genes were involved in ATP binding, cilium assembly, and oxidation-reduction processes. Integrating analysis of lncRNA and mRNA profiles predicted 10 lncRNA-gene pairs, including 8 co-regulated and 2 inversely-regulated pairs. To the best of our knowledge, this is the first genome-wide investigation of the lncRNAs in the chicken testis associated with sperm motility. Our results provided a catalog of chicken testis lncRNAs and genes worthy of further studies to understand their roles in cocks' reproductive performance regulation.

Genome-wide analysis of long non-coding RNAs and their role in postnatal porcine testis development

A comprehensive and systematic understanding of the roles of lncRNAs in the postnatal development of the pig testis has still not been achieved. In the present study, we obtained more than one billion clean reads and identified 15,528 lncRNA transcripts; these transcripts included 5032 known and 10,496 novel porcine lncRNA transcripts and corresponded to 10,041 lncRNA genes. Pairwise comparisons identified 449 known and 324 novel lncRNAs that showed differential expression patterns. GO and KEGG pathway enrichment analyses revealed that the targeted genes were involved in metabolic pathways regulating testis development and spermatogenesis, such as the TGF-beta pathway, the PI3K-Akt pathway, the Wnt/β-catenin pathway, and the AMPK pathway. Using this information, we predicted some lncRNAs and coding gene pairs were predicted that may function in testis development and spermatogenesis; these are listed in detail. This study has provided the most comprehensive catalog to date of lncRNAs in the postnatal pig testis and will aid our understanding of their functional roles in testis development and spermatogenesis.

Long noncoding RNA expression profile changes associated with dietary energy in the sheep testis during sexual maturation

Spermatogenesis can be affected by nutrition, which operates through normal physiological processes by changing the testicular mass and hormone levels profoundly. However, little is known regarding how testis development is regulated by long noncoding RNA (lncRNA). In this study, we investigated the effects of high-grain (HG) feeding on testis development during sexual maturation mediated by lncRNA. The HG diet group showed an increase in growth hormone (GH), insulin-like growth factor-1 (IGF-1) and testosterone (T) levels, and in the number of sperm in the seminiferous tubules compared with the hay-fed group (p  < 0.05). Moreover, we found 59 differentially expressed (DE) lncRNAs and 229 DE mRNAs in sheep testis between the two groups. qRT-PCR results of 20 randomly selected DE lncRNAs and mRNAs were also consistent with the RNA-seq data. Through functional enrichment analysis and lncRNA-mRNA interaction network analysis, we screened several lncRNAs that may be enriched for male reproduction such as spermatogenesis, sperm motility, steroid hormones, MAPK and ErbB signaling pathways. This study provides a first insight into the development of the testis with HG feeding in sheep and shows that these changes are associated with alterations in lncRNA expression.

Differentially expressed genes in the testicular tissues of adenylyl cyclase 3 knockout mice

Adenylate cyclase 3 (AC3) is an important component of the cyclic adenosine 3',5'-monophosphate (cAMP) signaling pathway and converts adenosine triphosphate into cAMP. Male mice with AC3 deletion (AC3^-/-) are sterile. However, the mechanical mechanism remains unclear. By TUNEL staining, we found that cell apoptosis in the testicular tissues of AC3^-/- mice increased significantly compared with that in the wild-type (AC3^+/+) mice. Differentially expressed genes regulated by AC3 in the testicular tissues were identified by gene chip hybridization. We observed that the expression of 693 genes was altered in the testicular tissues of AC3^-/- mice, including 330 up-regulated and 363 down-regulated gene expression with fold changes higher than 2 (≥2) as the standards. Furthermore, part of these differentially expressed genes was verified by the real-time fluorescence quantification PCR and immunofluorescent staining. The expression levels of the genes related to olfactory receptors, cell apoptosis, transcriptional activity, defensive reaction, cell adhesion, cell death, and immunoreactions were significantly altered in the testicular tissues of AC3^-/- mice compared with AC3^+/+ mice. In addition, the corresponding Ca²⁺, cAMP, and cell adhesion signaling pathways, as well as the signaling pathways related to axon guidance and cell interaction, were altered significantly in the AC3^-/- mice. These data would help elucidate the general understanding of the mechanisms underlying the sterility in AC3^-/- male mice.