The implication of microRNAs and endo-siRNAs in animal germline and early development

Male gonad-enriched microRNAs function to control sperm production in C. elegans

Germ cell development and gamete production in animals require small RNA pathways. While studies indicate that microRNAs (miRNAs) are necessary for normal sperm production and function, the specific roles for individual miRNAs are largely unknown. Here, we use small RNA sequencing of dissected gonads and functional analysis of new loss of function alleles to identify functions for miRNAs in the control of fecundity and sperm production in Caenorhabditis elegans males and hermaphrodites. We describe a set of 29 male gonad-enriched miRNAs and identify a set of 3 individual miRNAs (mir-58.1, mir-83, and mir-235) and a miRNA cluster (mir-4807-4810.1) that are required for optimal sperm production at 20°C and 5 additional miRNAs (mir-49, mir-57, mir-261, and mir-357/358) that are required for sperm production at 25°C. We observed defects in meiotic progression in mir-58.1, mir-83, mir-235, and mir-4807-4810.1 mutants that may contribute to the reduced number of sperm. Further, analysis of multiple mutants of these miRNAs suggested complex genetic interactions between these miRNAs for sperm production. This study provides insights on the regulatory roles of miRNAs that promote optimal sperm production and fecundity in males and hermaphrodites.

Enrichment of boron element in follicular fluid and its potential effect on the immune function

The blood-follicle barrier (BFB) between the blood and follicular fluid (FF) can maintain the microenvironment balance of oocyte. Boron, an exogenous environmental trace element, has been found to possibly play an important role in oocyte maturation. This study aimed to examine the distribution characteristics of boron across the BFB and find the potential effect of boron on FF microenvironment. We analyzed the concentration of boron in paired FF and serum collected from 168 women undergoing in vitro fertilization and embryo transfer in Beijing City and Shandong Province, China. To explore the potential health impact of boron enrichment in oocyte maturation, a global proteomics analysis was conducted to tentatively correlate the protein levels with the boron enrichment. Interestingly, the results showed that the concentration of boron in FF (34.5 ng/mL) was significantly higher than that in serum (22.0 ng/mL), with a median concentration ratio of 1.52. Likewise, the concentrations of boron in FF and serum were positively correlated (r = 0.446), suggesting that boron concentration in serum can represent its concentration in follicular fluid to a large extent.. This is the first time to observe the enrichment of boron in the FF to our knowledge. It is interesting to observe a total of 13 proteins, which mainly belong to immunoglobulin class, were positively correlated with boron concentration in FF. We concluded that boron, as one environmental trace element, was enriched in FF from blood validated by two area in north china, which may be involved in an increased level of immune processes of immunoglobulins.

Targeting the androgen receptor to enhance NK cell killing efficacy in bladder cancer by modulating ADAR2/circ_0001005/PD-L1 signaling

Although androgen receptor (AR) can influence bladder cancer (BCa) initiation and progression, its impact on tumor immune escape remains unclear. Here, we found that targeting AR could enhance natural killer (NK) cell tumor-killing efficacy by decreasing PD-L1 expression. Both antiandrogen treatment and AR knockdown effectively reduced membrane PD-LI expression to facilitate NK cell-mediated BCa cell killing by downregulating circ_0001005. Mechanistically, AR upregulated circRNA circ_0001005 expression via the RNA-editing gene ADAR2. circ_0001005 competitively sponged the miRNA miR-200a-3p to promote PD-L1 expression. A preclinical BCa xenograft mouse model further confirmed this newly identified signaling using the small molecule circ_0001005-shRNA to improve NK cell killing of BCa tumor cells. Collectively, these results suggest that targeting the newly identified ADAR2/circ_0001005/miR-200a-3p/PD-L1 pathway to impact antitumor immunity may suppress progression and boost immunotherapeutic efficacy in BCa.

New insights into the role of co-receptor neuropilins in tumour angiogenesis and lymphangiogenesis and targeted therapy strategies

Local tumour sites lead to pathological angiogenesis and lymphangiogenesis due to malignant conditions such as hypoxia. Although VEGF and VEGFR are considered to be the main anti-tumour treatment targets, the problems of limited efficacy and observable side effects of some drugs relevant to this target still remain to be solved. Therefore, it is necessary to identify new therapeutic targets for angiogenesis or lymphangiogenesis. The neuropilin family is a class of single transmembrane glycoprotein receptors, including neuropilin1 (NRP1) and neuropilin2 (NRP2), which could act as co-receptors of VEGFA-165 and VEGFC and play a key role in promoting tumour proliferation, invasion and metastasis. In this review, we introduced the schematic diagram to visually reveal the function of NRP1 and NRP2 in enhancing the binding affinity of VEGFR2 to VEGFA-165 and VEGFR3 to VEGFC, respectively. We also discussed the signalling pathways that depend on the co-receptors NRP1 and NRP2 and some existing targeted therapeutic strategies, such as monoclonal antibodies, targeted peptides, microRNAs and small molecule inhibitors. It will contribute a vital foundation for the future research and development of new drugs targeting NRPs. HIGHLIGHTS NRP1 acts as a co-receptor with VEGFR2 and the pro-angiogenic factor VEGFA-165 to up-regulate tumour angiogenesis by promoting endothelial cells proliferation, survival, migration, invasion and by preventing of apoptosis. NRP2 acts as a co-receptor with VEGFR3 and the pro-lymphogenic factor VEGFC to facilitate tumour metastasis by promoting lymphangiogenesis. Although NRP1 and NRP2 do not have enzymatic signalling activity, the affinity of VEGFR2 for VEGFA-165 and VEGFR3 for VEGFC can increase in a co-receptor manner, as detailed in the schematic. The exclusive roles of NRP1 and NRP2 in signalling pathways are specifically described to emphasise the molecular regulatory mechanisms involved in co-receptors. Various studies have shown that the co-receptors NRP1 and NRP2 can be directly or indirectly targeted by different methods to prevent tumour angiogenesis and lymphangiogenesis. Therapeutic strategies targeting NRPs look promising soon as evidenced by preclinical and clinical studies.

MicroRNA-212 suppresses cell proliferation in nasopharyngeal carcinoma by targeting ELF3

Nasopharyngeal carcinoma (NPC) is an epithelial malignancy of the head and neck that is prevalent in China. The present study investigated the molecular mechanisms of microRNA-212 (miR-212) and E74-like factor 3 (ELF3) in NPC cell lines and tissues. Using reverse transcription-quantitative PCR, the present study identified that miR-212 expression was downregulated in NPC cell lines and tissues. Furthermore, an elevated expression level of miR-212 was revealed to inhibit NPC cell proliferation, as determined using a cell counting kit-8 assay in vitro. ELF3 was identified as a direct target of miR-212 in NPC cells by a luciferase reporter assay. Additionally, the expression levels of miR-212 and ELF3 were negatively correlated in NPC tissues. The expression levels of ELF3 and miR-212 were associated with metastasis and TNM stage in patients with NPC. In summary, the present study indicated that miR-212 was downregulated in NPC and suppressed cell proliferation. This suggested that the miR-212/ELF3 axis may serve as a novel target for the diagnosis and treatment of NPC.

miRNAs in NK Cell-Based Immune Responses and Cancer Immunotherapy

The incidence of certain forms of tumors has increased progressively in recent years and is expected to continue growing as life expectancy continues to increase. Tumor-infiltrating NK cells may contribute to develop an anti-tumor response. Optimized combinations of different cancer therapies, including NK cell-based approaches for targeting tumor cells, have the potential to open new avenues in cancer immunotherapy. Functional inhibitory receptors on NK cells are needed to prevent their attack on healthy cells. Nevertheless, disruption of inhibitory receptors function on NK cells increases the cytotoxic capacity of NK cells against cancer cells. MicroRNAs (miRNAs) are small non-coding RNA molecules that target mRNA and thus regulate the expression of genes involved in the development, maturation, and effector functions of NK cells. Therapeutic strategies that target the regulatory effects of miRNAs have the potential to improve the efficiency of cancer immunotherapy. Interestingly, emerging evidence points out that some miRNAs can, directly and indirectly, control the surface expression of immune checkpoints on NK cells or that of their ligands on tumor cells. This suggests a possible use of miRNAs in the context of anti-tumor therapy. This review provides the current overview of the connections between miRNAs and regulation of NK cell functions and discusses the potential of these miRNAs as innovative biomarkers/targets for cancer immunotherapy.

Epigenetic modifications associated with in utero exposure to endocrine disrupting chemicals BPA, DDT and Pb

Endocrine disrupting chemicals (EDCs) are xenobiotics which adversely modify the hormone system. The endocrine system is most vulnerable to assaults by endocrine disruptors during the prenatal and early development window, and effects may persist into adulthood and across generations. The prenatal stage is a period of vulnerability to environmental chemicals because the epigenome is usually reprogrammed during this period. Bisphenol A (BPA), lead (Pb), and dichlorodiphenyltrichloroethane (DDT) were chosen for critical review because they have become serious public health concerns globally, especially in Africa where they are widely used without any regulation. In this review, we introduce EDCs and describe the various modes of action of EDCs and the importance of the prenatal and developmental windows to EDC exposure. We give a brief overview of epigenetics and describe the various epigenetic mechanisms: DNA methylation, histone modifications and non-coding RNAs, and how each of them affects gene expression. We then summarize findings from previous studies on the effects of prenatal exposure to the endocrine disruptors BPA, Pb and DDT on each of the previously described epigenetic mechanisms. We also discuss how the epigenetic alterations caused by these EDCs may be related to disease processes.

Circular RNA profiling in the oocyte and cumulus cells reveals that circARMC4 is essential for porcine oocyte maturation

Thousands of circular RNAs (circRNAs) have been recently discovered in cumulus cells and oocytes from several species. However, the expression and function of circRNA during porcine oocyte meiotic maturation have been never examined. Here, we separately identified 7,067 and 637 circRNAs in both cumulus cells and oocytes via deep sequencing and bioinformatic analysis. Further analysis revealed that a faction of circRNAs is differentially expressed (DE) in a developmental stage-specific manner. The host genes of DE circRNAs are markedly enriched to multiple signaling pathways associated with cumulus cell function and oocyte maturation. Additionally, most DE circRNAs harbor several miRNA targets, suggesting that these DE circRNAs potentially act as miRNA sponge. Importantly, we found that maternal circARMC4 knockdown by siRNA microinjection caused a severely impaired chromosome alignment, and significantly inhibited first polar body extrusion and early embryo development. Taken together, these results demonstrate for the first time that circRNAs are abundantly and dynamically expressed in a developmental stage-specific manner in cumulus cells and oocytes, and maternally expressed circARMC4 is essential for porcine oocyte meiotic maturation and early embryo development.

Roles of MicroRNAs in Establishing and Modulating Stem Cell Potential

Early embryonic development in mammals, from fertilization to implantation, can be viewed as a process in which stem cells alternate between self-renewal and differentiation. During this process, the fates of stem cells in embryos are gradually specified, from the totipotent state, through the segregation of embryonic and extraembryonic lineages, to the molecular and cellular defined progenitors. Most of those stem cells with different potencies in vivo can be propagated in vitro and recapitulate their differentiation abilities. Complex and coordinated regulations, such as epigenetic reprogramming, maternal RNA clearance, transcriptional and translational landscape changes, as well as the signal transduction, are required for the proper development of early embryos. Accumulated studies suggest that Dicer-dependent noncoding RNAs, including microRNAs (miRNAs) and endogenous small-interfering RNAs (endo-siRNAs), are involved in those regulations and therefore modulate biological properties of stem cells in vitro and in vivo. Elucidating roles of these noncoding RNAs will give us a more comprehensive picture of mammalian embryonic development and enable us to modulate stem cell potencies. In this review, we will discuss roles of miRNAs in regulating the maintenance and cell fate potential of stem cells in/from mouse and human early embryos.

miR-7-5p inhibits cell migration and invasion in glioblastoma through targeting SATB1

MicroRNAs (miRNAs/miRs) have been revealed to influence the development and progression of glioblastoma. Although a number of miRNAs are abnormally expressed in glioblastoma it is not clear whether they are a factor associated with glioblastoma pathogenesis. In the present study, miR-7-5p was identified as being aberrantly downregulated in glioblastoma tissues and cell lines. miR-7-5p overexpression significantly decreased the migratory and invasive capacity of the cells, while miR-7-5p silencing had the opposite effect. In addition, a luciferase assay confirmed that special AT rich sequence binding protein 1 (SATB1) was a direct target gene of miR-7-5p in glioblastoma. The overexpression of SATB1 in glioblastoma was revealed to promote cell migration and invasion. In addition, SATB1 overexpression may weaken the inhibitory effect of miR-7-5p on cell migration and invasion. miR-7-5p overexpression reversed the effects of SATB1 on cell migration and invasion in glioblastoma cells. In conclusion, miR-7-5p may be a useful therapeutic target for the diagnosis and treatment of patients with glioblastoma.

Somatic and Germline MicroRNAs Form Distinct Silencing Complexes to Regulate Their Target mRNAs Differently

Animal germ cells possess a specific post-transcriptional regulatory context allowing the storage of maternal transcripts in the oocyte until their translation at a specific point in early development. As key regulators of gene expression, miRNAs repress translation mainly through mRNA destabilization. Thus, germline miRNAs likely use distinct ways to regulate their targets. Here, we use C. elegans to compare miRNA function within germline and somatic tissues. We show that the same miRNA displays tissue-specific gene regulatory mechanisms. While translational repression occurs in both tissues, targeted mRNAs are instead stabilized in the germline. Comparative analyses of miRNA silencing complexes (miRISC) demonstrate that their composition differs from germline to soma. We show that germline miRNA targets preferentially localize to perinuclear regions adjacent to P granules, and their repression is dependent on the core P granule component GLH-1. Together, our findings reveal the existence of different miRISC in animals that affect targeted mRNAs distinctively.

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

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

Oocyte related factors impacting on embryo quality: relevance for in vitro embryo production

The outcome of pregnancy is closely linked to early events that occur during the onset of embryogenesis. The first stages in embryonic development are mainly governed by the storage of maternal factors present in the oocyte at the time of fertilisation. In this review, we outline the different classes of oocyte transcripts that may be involved in activation of the embryonic genome as well as those associated with epigenetic reprogramming, imprinting maintenance or the control of transposon mobilisation during preimplantation development. We also report the influence of cumulus-oocyte crosstalk during the maturation process on the oocyte transcriptome and how in vitro procedures can affect these interactions.

The Non-Coding Transcriptome of Prostate Cancer: Implications for Clinical Practice

Prostate cancer (PCa) is the most common type of cancer and the second leading cause of cancer-related death in men. Despite extensive research, the molecular mechanisms underlying PCa initiation and progression remain unclear, and there is increasing need of better biomarkers that can distinguish indolent from aggressive and life-threatening disease. With the advent of advanced genomic technologies in the last decade, it became apparent that the human genome encodes tens of thousands non-protein-coding RNAs (ncRNAs) with yet to be discovered function. It is clear now that the majority of ncRNAs exhibit highly specific expression patterns restricted to certain tissues and organs or developmental stages and that the expression of many ncRNAs is altered in disease and cancer, including cancer of the prostate. Such ncRNAs can serve as important biomarkers for PCa diagnosis, prognosis, or prediction of therapy response. In this review, we give an overview of the different types of ncRNAs and their function, describe ncRNAs relevant for the diagnosis and prognosis of PCa, and present emerging new aspects of ncRNA research that may contribute to the future utilization of ncRNAs as clinically useful therapeutic targets.

Alterations in sperm DNA methylation, non-coding RNA expression, and histone retention mediate vinclozolin-induced epigenetic transgenerational inheritance of disease

Epigenetic transgenerational inheritance of disease and phenotypic variation can be induced by several toxicants, such as vinclozolin. This phenomenon can involve DNA methylation, non-coding RNA (ncRNA) and histone retention, and/or modification in the germline (e.g. sperm). These different epigenetic marks are called epimutations and can transmit in part the transgenerational phenotypes. This study was designed to investigate the vinclozolin-induced concurrent alterations of a number of different epigenetic factors, including DNA methylation, ncRNA, and histone retention in rat sperm. Gestating females (F0 generation) were exposed transiently to vinclozolin during fetal gonadal development. The directly exposed F1 generation fetus, the directly exposed germline within the fetus that will generate the F2 generation, and the transgenerational F3 generation sperm were studied. DNA methylation and ncRNA were altered in each generation rat sperm with the direct exposure F1 and F2 generations being distinct from the F3 generation epimutations. Interestingly, an increased number of differential histone retention sites were found in the F3 generation vinclozolin sperm, but not in the F1 or F2 generations. All three different epimutation types were affected in the vinclozolin lineage transgenerational sperm (F3 generation). The direct exposure generations (F1 and F2) epigenetic alterations were distinct from the transgenerational sperm epimutations. The genomic features and gene pathways associated with the epimutations were investigated to help elucidate the integration of these different epigenetic processes. Our results show that the three different types of epimutations are involved and integrated in the mediation of the epigenetic transgenerational inheritance phenomenon.

Alterations in sperm DNA methylation, non-coding RNA and histone retention associate with DDT-induced epigenetic transgenerational inheritance of disease

BACKGROUND

Environmental toxicants such as DDT have been shown to induce the epigenetic transgenerational inheritance of disease (e.g., obesity) through the germline. The current study was designed to investigate the DDT-induced concurrent alterations of a number of different epigenetic processes including DNA methylation, non-coding RNA (ncRNA) and histone retention in sperm.

METHODS

Gestating females were exposed transiently to DDT during fetal gonadal development, and then, the directly exposed F1 generation, the directly exposed germline F2 generation and the transgenerational F3 generation sperm were investigated.

RESULTS

DNA methylation and ncRNA were altered in each generation sperm with the direct exposure F1 and F2 generations being predominantly distinct from the F3 generation epimutations. The piRNA and small tRNA were the most predominant classes of ncRNA altered. A highly conserved set of histone retention sites were found in the control lineage generations which was not significantly altered between generations, but a large number of new histone retention sites were found only in the transgenerational generation DDT lineage sperm.

CONCLUSIONS

Therefore, all three different epigenetic processes were concurrently altered as DDT induced the epigenetic transgenerational inheritance of sperm epimutations. The direct exposure generations sperm epigenetic alterations were distinct from the transgenerational sperm epimutations. The genomic features and gene associations with the epimutations were investigated to help elucidate the integration of these different epigenetic processes. Observations demonstrate all three epigenetic processes are involved in transgenerational inheritance. The different epigenetic processes appear to be integrated in mediating the epigenetic transgenerational inheritance phenomenon.

Discovery and characterization of conserved and novel microRNAs from blunt snout bream (Megalobrama amblycephala) by deep sequencing

MicroRNAs (miRNAs) are short, single stranded RNA molecules with approximately 22 nts in length, which regulate the stability and translation of messenger RNAs in several organisms. To increase the repertoire of miRNAs characterized in M. amblycephala, we used the deep sequencing technology to sequence a small RNA library using pooled RNA sample isolated from the 4 different tissues of M. amblycephala. A total of 309 conserved miRNAs that originated from 131 miRNA families were detected. 15 novel candidates miRNA were identified. Randomly selected 6 miRNAs were analyzed by stem-loop qRT-PCR and differential expression patterns were observed in 6 different tissues of M. amblycephala. Furthermore, the potential targets were predicted. GO analysis showed that most of the targets were involved in a broad range of physiological functions including fish growth, development, metabolism, stress responses and so on. Overall, our results significantly increased the number of novel miRNAs in M. amblycephala, which should be useful for further investigation into the role of miRNAs in regulating diverse biological processes.

MiR-142 inhibits the development of cervical cancer by targeting HMGB1

It has been reported that miRNAs is deregulated in diverse human cancers, involving human cervical cancer. However, the clinical significances and potential mechanisms of miR-142 in the development and progression of cervical cancer were not elucidated completely till now. In this study, we found that the expression of miR- 142 was obviously down-regulated in human cervical cancer tissues and a panel of cell lines. According to statistics, the expression of miR-142 was negatively related to advanced FIGO stage and lymphatic metastasis (p < 0.001). Furthermore, our functional analysis revealed the overexpression of miR-142 affected cell proliferation and invasiveness, and enhanced cell apoptosis in representative SiHa and HeLa cells. Based on the molecular level, our findings showed the 3′ untranslated region (3′-UTR) of high-mobility group box 1 protein (HMGB1) was a direct target of miR-142, and determined an inverse correlation with the expression of miR-142. Ectopic expression of HMGB1 could attenuate the inhibitory impact of miR-142 on the proliferation and invasiveness of cervical cancer cells. In conclusion, the present work suggested that miR-142 affects cervical cancer cell proliferation and invasiveness, and enhances cell apoptosis via directly targeting the expression of HMGB1, and these findings may lay a novel foundation for the promising therapy target of cervical cancer.

Re-Arrangements in the Cytoplasmic Distribution of Small RNAs Following the Maternal-to-Zygotic Transition in Drosophila Embryos

Small ribonucleic acids (RNAs) are known to regulate gene expression during early development. However, the dynamics of interaction between small RNAs and polysomes during this process is largely unknown. To investigate this phenomenon, 0–1 h and 7–8 h Drosophila melanogaster embryos were fractionated on sucrose density gradients into four fractions based on A₂₅₄ reading (1) translationally inactive messenger ribonucleoprotein (mRNP), (2) 60S, (3) monosome, and (4) polysome. Comparative analysis of deep-sequencing reads from fractionated and un-fractionated 0–1 h and 7–8 h embryos revealed development-specific co-sedimentation pattern of small RNAs with the cellular translation machinery. Although most micro RNAs (miRNAs) did not have a specific preference for any state of the translational machinery, we detected fraction-specific enrichment of a few miRNAs such as dme-miR-1-3p, -184-3p, 5-5p and 263-5p. More interestingly, we observed changes in the subcellular location of a subset of miRNAs in fractionated embryos despite no measurable difference in their amount in unfractionated embryos. Transposon-derived endo small interfering RNAs (siRNAs) were over-expressed in 7–8 h embryos and associated mainly with the mRNP fraction. In contrast, transposon-derived PIWI-interacting RNAs (piRNA), which were more abundant in 0–1 h embryos, co-sedimented primarily with the polysome fractions. These results suggest that there appears to be a complex interplay among the small RNAs with respect to their polysome-cosedimentation pattern during early development in Drosophila melanogaster.

Glaucoma, Stem Cells, and Gene Therapy: Where Are We Now?

Glaucoma is the second most common cause of blindness, affecting 70∼80 million people around the world. The death of retinal ganglion cells (RGCs) is the main cause of blindness related to this disease. Current therapies do not provide enough protection and regeneration of RGCs. A novel opportunity for treatment of glaucoma is application of technologies related to stem cell and gene therapy. In this perspective we will thus focus on emerging approaches to glaucoma treatment including stem cells and gene therapy.

Acetylation and methylation profiles of H3K27 in porcine embryos cultured in vitro

Methylation and acetylation of histone H3 at lysine 27 (H3K27) regulate chromatin structure and gene expression during early embryo development. While H3K27 acetylation (H3K27ac) is associated with active gene expression, H3K27 methylation (H3K27me) is linked to transcriptional repression. The aim of this study was to assess the profile of H3K27 acetylation and methylation (mono-, di- and trimethyl) during oocyte maturation and early development in vitro of porcine embryos. Oocytes/embryos were fixed at different developmental stages from germinal vesicle to day 8 blastocysts and submitted to an immunocytochemistry protocol to identify the presence and quantify the immunofluorescence intensity of H3K27ac, H3K27me1, H3K27me2 and H3K27me3. A strong fluorescent signal for H3K27ac was observed in all developmental stages. H3K27me1 and H3K27me2 were detected in oocytes, but the fluorescent signal decreased through the cleavage stages and rose again at the blastocyst stage. H3K27me3 was detected in oocytes, in only one pronucleus in zygotes, cleaved-stage embryos and blastocysts. The nuclear fluorescence signal for H3K27me3 increased from the 2-cell stage to 4-cell stage embryos, decreased at the 8-cell and morula stages and increased again in blastocysts. Different patterns of the H3K27me3 mark were observed at the blastocyst stage. Our results suggest that changes in the H3K27 methylation status regulate early porcine embryo development as previously shown in other species.

Transposable Element Bm1645 is a Source of BmAGO2-associated Small RNAs that affect its expression in Bombyx mori

Background

A transposable element (TE) is a DNA fragment that can change its position within a genome. Transposable elements play important roles in maintaining the stability and diversity of organisms by transposition. Recent studies have shown that approximately half of the genes in Bombyx mori are TEs.

Results

We systematically identified and analyzed the BmAGO2-associated TEs, which exceed 100 in the B. mori genome. Additionally, we also mapped the small RNAs associated with BmAGO2 in B.mori. The transposon Bm1645 is the most abundant TE associated with BmAGO2, and Bm1645-derived small RNAs represent a small RNA pool. We determined the expression patterns of several Bm1645-derived small RNAs by northern blotting, and the results showed there was differential expression of multiple small RNAs in normal and BmNPV-infected BmN cells and silkworms from various developmental stages. We confirmed that four TE-siRNAs could bind to BmAGO2 using EMSA and also validated the recognition sites of these four TE-siRNAs in Bm1645 by dual-luciferase reporter assays. Furthermore, qRT-PCR analysis revealed the overexpression of the four TE-siRNAs could downregulate the expression of Bm1645 in BmN cells, and the transcription of Bm1645 was upregulated by the downregulation of BmAGO2.

Conclusions

Our results suggest Bm1645 functions as a source of small RNAs pool and this pool can produce many BmAGO2-associated small RNAs that regulate TE’s expression.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-017-3598-5) contains supplementary material, which is available to authorized users.

Exogenous Molecule and Organelle Delivery in Oogenesis

Recent discoveries on the delivery of small- and large-size molecules and organelles to the oocytes/eggs from external sources, such as surrounding somatic cells, body fluids, and sperm, change our understanding of female germ cells' (oocytes and eggs) self-containment and individuality. In this chapter, we will summarize present-day knowledge on sources and presumptive functions of different types of exogenous molecules and organelles delivered to the animal oocytes and eggs.

miR-15b Inhibits the Progression of Glioblastoma Cells Through Targeting Insulin-like Growth Factor Receptor 1

The microRNAs (miRNAs) have been suggested as a tumor suppressor in recent years. miR-15b was reported to exert an anti-oncogenic role in the proliferation, migration, and invasion of diverse tumor cells. However, the mechanisms underlying miR-15b-mediated biology of glioblastoma are still unclear. In the present study, the expression of miR-15b was down-regulated in glioblastoma tumor tissues and U87 and U251 cells, but insulin-like growth factor receptor 1 (IGF1R) expression became up-regulated in these tumor tissues and cells (all p < 0.001). Furthermore, IGF1R expression was inversely associated with miR-15b expression. Notably, patients with lower miR-15b expression have a much shorter survival period compared with high expression (log-rank test p = 0.045). In vitro data demonstrated that miR-15b mimics inhibited the proliferation, cell cycle arrest, and invasion of U87 and U251 cells. Besides, we validated IGF1R as a direct target of miR-15b using dual luciferase assays, and IGF1R plasmids partially abrogated miR-15b mimics inhibited cell proliferation. In vivo, miR-15b mimics indeed repressed cell proliferation in mouse xenograft model. In conclusion, our study demonstrated that miR-15b inhibits the progression of glioblastoma cells through targeting IGF1R, and miR-15b can be recommended as a tumor suppressor in the progression of glioblastoma.

Epigenetic reprogramming of the zygote in mice and men: on your marks, get set, go!

Gametogenesis (spermatogenesis and oogenesis) is accompanied by the acquisition of gender-specific epigenetic marks, such as DNA methylation, histone modifications and regulation by small RNAs, to form highly differentiated, but transcriptionally silent cell-types in preparation for fertilisation. Upon fertilisation, extensive global epigenetic reprogramming takes place to remove the previously acquired epigenetic marks and produce totipotent zygotic states. It is the aim of this review to delineate the cellular and molecular events involved in maternal, paternal and zygotic epigenetic reprogramming from the time of gametogenesis, through fertilisation, to the initiation of zygotic genome activation for preimplantation embryonic development. Recent studies have begun to uncover the indispensable functions of epigenetic players during gametogenesis, fertilisation and preimplantation embryo development, and a more comprehensive understanding of these early events will be informative for increasing pregnancy success rates, adding particular value to assisted fertility programmes.

MicroRNA-206 Inhibited the Progression of Glioblastoma Through BCL-2

Gliomas are the most common type of brain tumor and have a poor prognosis. MicroRNAs (miRNAs) are a class of small, endogenous, and non-coding RNAs that play crucial roles in cell proliferation, survival, and invasion. Deregulated expression of miR-206 has been investigated in many cancers. However, the role of miR-206 in glioblastoma is still unclear. In the present study, we found that the expression of miR-206 was decreased in cancer tissues compared with normal tissues. However, the expression level of BCL-2 was higher in cancer tissues than that in normal tissues (all p < 0.001). Statistically, the expression level of BCL-2 was inversely correlated with the miR-206. In addition, the overall survival of glioblastoma patients with lower miR-206 expression was significantly shorter than those with high miR-206 expression (p < 0.001). Besides, the expression of miR-206 was also decreased in U87 and U251 cells. In vitro assays showed that ectopic miR-206 expression affected the proliferation, cell cycle, and invasion in U87 and U251 cells. Importantly, we identified BCL-2 as a direct target of miR-206 in U87 and U251 cells using luciferase assay. Overexpression of BCL-2 partially attenuated the miR-206-mediated cell proliferation. In vivo, overexpression of miR-206 suppressed the progression of glioblastoma cells using mice xenograft model. In conclusion, this study suggested that miR-206 could act as a tumor suppressor gene through inhibiting BCL-2 in the development of glioblastoma.

Maternal stress and diet may influence affective behavior and stress-response in offspring via epigenetic regulation of central peptidergic function

It has been shown that maternal stress and malnutrition, or experience of other adverse events, during the perinatal period may alter susceptibility in the adult offspring in a time-of-exposure dependent manner. The mechanism underlying this may be epigenetic in nature. Here, we summarize some recent findings on the effects on gene-regulation following maternal malnutrition, focusing on epigenetic regulation of peptidergic activity. Numerous neuropeptides within the central nervous system are crucial components in regulation of homeostatic energy-balance, as well as affective health (i.e. health events related to affective disorders, psychiatric disorders also referred to as mood disorders). It is becoming evident that expression, and function, of these neuropeptides can be regulated via epigenetic mechanisms during fetal development, thereby contributing to the development of the adult phenotype and, possibly, modulating disease susceptibility. Here, we focus on two such neuropeptides, neuropeptide Y (NPY) and corticotropin-releasing hormone (CRH), both involved in regulation of endocrine function, energy homeostasis, as well as affective health. While a number of published studies indicate the involvement of epigenetic mechanisms in CRH-dependent regulation of the offspring adult phenotype, NPY has been much less studied in this context and needs further work.