MicroRNA-424/503 cluster members regulate bovine granulosa cell proliferation and cell cycle progression by targeting SMAD7 gene through activin signalling pathway

Granulosa Cells-Related MicroRNAs in Ovarian Diseases: Mechanism, Facts and Perspectives

MicroRNAs (miRNAs) are a class of short single-stranded, noncoding RNAs that affect the translation of mRNAs by imperfectly binding to homologous 3'UTRs. Research on miRNAs in ovarian diseases is constantly expanding because miRNAs are powerful regulators of gene expression and cellular processes and are promising biomarkers. miRNA mimics, miRNA inhibitors and molecules targeting miRNAs (antimiRs) have shown promise as novel therapeutic agents in preclinical development. Granulosa cells (GCs) are supporting cells for developing oocytes in the ovary. GCs regulate female reproductive health by producing sex hormones and LH receptors. Increasing research has reported the relevance of miRNAs in GC pathophysiology. With in-depth studies of disease mechanisms, there are an increasing number of studies on the biomolecular pathways of miRNAs in gynecology and endocrinology. In the present review, we summarize the different functions of GC-related microRNAs in various ovarian disorders, such as polycystic ovary syndrome, premature ovarian insufficiency, premature ovarian failure and ovarian granulosa cell tumors.

miR-423 sponged by lncRNA NORHA inhibits granulosa cell apoptosis

BACKGROUND

Atresia and degeneration, a follicular developmental fate that reduces female fertility and is triggered by granulosa cell (GC) apoptosis, have been induced by dozens of miRNAs. Here, we report a miRNA, miR-423, that inhibits the initiation of follicular atresia (FA), and early apoptosis of GCs.

RESULTS

We showed that miR-423 was down-regulated during sow FA, and its levels in follicles were negatively correlated with the GC density and the P4/E2 ratio in the follicular fluid in vivo. The in vitro gain-of-function experiments revealed that miR-423 suppresses cell apoptosis, especially early apoptosis in GCs. Mechanically speaking, the miR-423 targets and interacts with the 3'-UTR of the porcine SMAD7 gene, which encodes an apoptosis-inducing factor in GCs, and represses its expression and pro-apoptotic function. Interestingly, FA and the GC apoptosis-related lncRNA NORHA was demonstrated as a ceRNA of miR-423. Additionally, we showed that a single base deletion/insertion in the miR-423 promoter is significantly associated with the number of stillbirths (NSB) trait of sows.

CONCLUSION

These results demonstrate that miR-423 is a small molecule for inhibiting FA initiation and GC early apoptosis, suggesting that treating with miR-423 may be a novel approach for inhibiting FA initiation and improving female fertility.

miR-484 mediates oxidative stress-induced ovarian dysfunction and promotes granulosa cell apoptosis via SESN2 downregulation

Ovarian dysfunction is a common cause of female infertility, which is associated with genetic, autoimmune and environmental factors. Granulosa cells (GCs) constitute the largest cell population of ovarian follicles. Changes in GCs, including oxidative stress (OS) and excessive reactive oxygen species (ROS), are involved in regulating ovary function. miR-484 is highly expressed in 3-NP-induced oxidative stress models of ovaries and GCs. miR-484 overexpression aggravated GCs dysfunction and thereby intensified ovarian oxidative stress injury in mice. Moreover, bioinformatic analyses, luciferase assays and pull-down assays indicated that LINC00958 acted as a competing endogenous RNA (ceRNA) for miR-484 and formed a signaling axis with Sestrin2(SESN2) under oxidative stress conditions, which in turn regulated mitochondrial functions and mitochondrial-related apoptosis in GCs. Additionally, the inhibition of miR-484 alleviated GCs dysfunction under ovarian oxidative stress condition. Our present study revealed the role of miR-484 in oxidative stress of ovaries and GCs and the function of LINC00958/miR-484/SESN2 axis in mitochondrial function and mitochondria-related apoptosis.

Micro RNA based MSC EV engineering: Targeting the BMP2 cascade for bone repair

Mesenchymal stem cell derived extracellular vesicles (MSC EVs) possess excellent immunomodulatory and therapeutic properties. While beneficial, from a translational perspective, extracellular vesicles with consistent functionality and target specificity are required to achieve the goals of precision medicine and tissue engineering. Prior research has identified that the miRNA composition of mesenchymal stem cell derived extracellular vesicles contributes significantly towards extracellular vesicles functionality. In this study, we hypothesized that mesenchymal stem cell derived extracellular vesicle functionality can be rendered pathway-specific using a miRNA-based extracellular vesicles engineering approach. To test this hypothesis, we utilized bone repair as a model system and the BMP2 signaling cascade as the targeted pathway. We engineered mesenchymal stem cell extracellular vesicles to possess increased levels of miR-424, a potentiator of the BMP2 signaling cascade. We evaluated the physical and functional characteristics of these extracellular vesicles and their enhanced ability to trigger the osteogenic differentiation of naïve mesenchymal stem cell in vitro and facilitate bone repair in vivo. Results indicated that the engineered extracellular vesicles retained their extracellular vesicles characteristics and endocytic functionality and demonstrated enhanced osteoinductive function by activating SMAD1/5/8 phosphorylation and mesenchymal stem cell differentiation in vitro and enhanced bone repair in vivo. Furthermore, the inherent immunomodulatory properties of the mesenchymal stem cell derived extracellular vesicles remained unaltered. These results serve as a proof-of-concept for miRNA-based extracellular vesicles engineering approaches for regenerative medicine applications.

A therapeutic target for CKD: activin A facilitates TGFβ1 profibrotic signaling

BACKGROUND

TGFβ1 is a major profibrotic mediator in chronic kidney disease (CKD). Its direct inhibition, however, is limited by adverse effects. Inhibition of activins, also members of the TGFβ superfamily, blocks TGFβ1 profibrotic effects, but the mechanism underlying this and the specific activin(s) involved are unknown.

METHODS

Cells were treated with TGFβ1 or activins A/B. Activins were inhibited generally with follistatin, or specifically with neutralizing antibodies or type I receptor downregulation. Cytokine levels, signaling and profibrotic responses were assessed with ELISA, immunofluorescence, immunoblotting and promoter luciferase reporters. Wild-type or TGFβ1-overexpressing mice with unilateral ureteral obstruction (UUO) were treated with an activin A neutralizing antibody.

RESULTS

In primary mesangial cells, TGFβ1 induces secretion primarily of activin A, which enables longer-term profibrotic effects by enhancing Smad3 phosphorylation and transcriptional activity. This results from lack of cell refractoriness to activin A, unlike that for TGFβ1, and promotion of TGFβ type II receptor expression. Activin A also supports transcription through regulating non-canonical MRTF-A activation. TGFβ1 additionally induces secretion of activin A, but not B, from tubular cells, and activin A neutralization prevents the TGFβ1 profibrotic response in renal fibroblasts. Fibrosis induced by UUO is inhibited by activin A neutralization in wild-type mice. Worsened fibrosis in TGFβ1-overexpressing mice is associated with increased renal activin A expression and is inhibited to wild-type levels with activin A neutralization.

CONCLUSIONS

Activin A facilitates TGFβ1 profibrotic effects through regulation of both canonical (Smad3) and non-canonical (MRTF-A) signaling, suggesting it may be a novel therapeutic target for preventing fibrosis in CKD.

Genome-Wide Association Analysis Reveals Novel Loci Related with Visual Score Traits in Nellore Cattle Raised in Pasture-Based Systems

Body conformation traits assessed based on visual scores are widely used in Zebu cattle breeding programs. The aim of this study was to identify genomic regions and biological pathways associated with body conformation (CONF), finishing precocity (PREC), and muscling (MUSC) in Nellore cattle. The measurements based on visual scores were collected in 20,807 animals raised in pasture-based systems in Brazil. In addition, 2775 animals were genotyped using a 35 K SNP chip, which contained 31,737 single nucleotide polymorphisms after quality control. Single-step GWAS was performed using the BLUPF90 software while candidate genes were identified based on the Ensembl Genes 69. PANTHER and REVIGO platforms were used to identify key biological pathways and STRING to create gene networks. Novel candidate genes were revealed associated with CONF, including ALDH9A1, RXRG, RAB2A, and CYP7A1, involved in lipid metabolism. The genes associated with PREC were ELOVL5, PID1, DNER, TRIP12, and PLCB4, which are related to the synthesis of long-chain fatty acids, lipid metabolism, and muscle differentiation. For MUSC, the most important genes associated with muscle development were SEMA6A, TIAM2, UNC5A, and UIMC1. The polymorphisms identified in this study can be incorporated in commercial genotyping panels to improve the accuracy of genomic evaluations for visual scores in beef cattle.

Totipotency of miR-184 in porcine granulosa cells

Estradiol (E₂) synthesis, cell proliferation and the apoptosis of porcine granulosa cells (GCs) affect follicular growth and development. The miR-184 level in ovary tissues of Yorkshire × Landrace sows was significantly higher in high-yielding sows than that in low-yielding sows, which was the same as in Yorkshire sows. However, the roles of miR-184 on E₂ granulosa cells (GCs) are still unclear. We found that miR-184 promoted E₂ synthesis and proliferation but inhibited apoptosis in GCs by targeting nuclear receptor subfamily 1 group D member 1 (NR1D1), cyclin dependent kinase inhibitor 1A (P21,CDKN1A) and homeodomain interacting protein kinase 2 (HIPK2) respectively. These findings indicated that miR-184 is a novel key factor that regulates the physiological functions of GCs.

Why Is It So Difficult To Have Competent Oocytes from In vitro Cultured Preantral Follicles?

The developmental competence of oocytes is acquired gradually during follicular development, mainly through oocyte accumulation of RNA molecules and proteins that will be used during fertilization and early embryonic development. Several attempts to develop in vitro culture systems to support preantral follicle development up to maturation are reported in the literature, but oocyte competence has not yet been achieved in human and domestic animals. The difficulties to have fertilizable oocytes are related to thousands of mRNAs and proteins that need to be synthesized, long-term duration of follicular development, size of preovulatory follicles, composition of in vitro culture medium, and the need of multi-step culture systems. The development of a culture system that maintains bidirectional communication between the oocyte and granulosa cells and that meets the metabolic demands of each stage of follicle growth is the key to sustain an extended culture period. This review discusses the physiological and molecular mechanisms that determine acquisition of oocyte competence in vitro, like oocyte transcriptional activity, follicle and oocyte sizes, and length and regulation of follicular development in murine, human, and domestic animal species. The state of art of in vitro follicular development and the challenges to have complete follicular development in vitro are also highlighted.

chi-miR-324-3p Regulates Goat Granulosa Cell Proliferation by Targeting DENND1A

Granulosa cell (GC) proliferation provides essential conditions for ovulation in animals. A previous study showed that DENND1A plays a significant role in polycystic ovary syndrome. However, the modulation of DENND1A in GCs remains unclear. Our previous integrated analysis of miRNA–mRNA revealed that the 3'-untranslated region of DENND1A could be a target of chi-miR-324-3p. In this study, we used quantitative reverse transcription polymerase chain reaction (RT-qPCR) to investigate DENND1A expression in ovarian tissues of high- and low-yielding goats. Furthermore, dual-fluorescent reporter vector experiments, Cell Counting Kit-8 (CCK-8) assay, and RT-qPCR were used to elucidate the regulatory pathway of chi-miR-324-3p-DENND1A in GCs. The results revealed an opposite tendency between the expressions of chi-miR-324-3p and DENND1A in the ovaries of high- and low-yielding goats. The CCK-8 assay indicated that chi-miR-324-3p overexpression significantly suppressed GC proliferation, whereas chi-miR-324-3p inhibition promoted GC proliferation. In addition, the expressions of GC proliferation markers LHR, Cylin D2, and CDK4 showed the same tendency. The dual-fluorescent reporter assay revealed that chi-miR-324-3p directly targeted DENND1A, and the RT-qPCR results revealed that DENND1A expression was inhibited by chi-miR-324-3p. In summary, chi-miR-324-3p inhibited the proliferation of GCs by targeting DENND1A.

Follicular development in livestock: Influencing factors and underlying mechanisms

Livestock farming development has become increasingly important in recent years. It not only provides us with meat nutrition and pet feeding but also increases the economic value by providing numerous employment opportunities, which improves our life quality. The livestock farming development depends on successful animal reproduction. As a vital process in animal reproduction, folliculogenesis and its influencing factors as well as their underlying mechanisms need to be understood thoroughly. This review is aimed at summarizing the factors such as cellular processes, gene regulation, noncoding RNAs and other endocrine or paracrine regulatory factors that affect follicular development, and their underlying mechanisms of action in livestock in order to provide novel insights for future studies. The above factors were found as significant determinants influencing the follicular development in livestock through various signaling pathways.

MiR-145 regulates steroidogenesis in mouse primary granulosa cells through targeting Crkl

AIMS

It has been demonstrated that miR-145 is expressed in primordial follicles and modulates the initiation of primordial follicle development. We aimed to explore the function of miR-145 in mouse granulosa cells (mGCs).

MATERIALS AND METHODS

The proliferation and differentiation of GCs were examined via MTT, EDU assay, QRT-PCR, ELISA and electron microscope analysis. The target of miR-145 was determined by bioinformatics analysis and luciferase reporter assay and the molecular mechanisms were examined via western blot and quantitative Real-Time RT-PCR.

KEY FINDINGS

We proved that down-regulation of miR-145 could inhibit GCs proliferation and differentiation. In addition, we provided evidence that Crkl was the target gene of miR-145. The miR-145 antagomir caused an increase in Crkl expression and activation of the JNK/p38 MAPK pathway. Overexpression of Crkl with pEGFP-N1-Crkl vector inhibited GCs differentiation and progesterone synthesis as well as activation of the JNK/p38 MAPK pathway.

SIGNIFICANCE

Our study shows that miR-145 targets Crkl and through the JNK/p38 MAPK signaling pathway promotes the GCs proliferation, differentiation, and steroidogenesis. MiR-145 may play an important role in the ovarian physiology and pathology.

miR-135a Suppresses Granulosa Cell Growth by Targeting Tgfbr1 and Ccnd2 during Folliculogenesis in Mice

The success of female reproduction relies on high quality oocytes, which is determined by well-organized cooperation between granulosa cells (GCs) and oocytes during folliculogenesis. GC growth plays a crucial role in maintaining follicle development. Herein, miR-135a was identified as a differentially expressed microRNA in pre-ovulatory ovarian follicles between Large White and Chinese Taihu sows detected by Solexa deep sequencing. We found that miR-135a could significantly facilitate the accumulation of cells arrested at the G1/S phase boundary and increase apoptosis. Mechanically, miR-135a suppressed transforming growth factor, beta receptor I (Tgfbr1) and cyclin D2 (Ccnd2) expression by targeting their 3′UTR in GCs. Furthermore, subcellular localization analysis and a chromatin immunoprecipitation-quantitative real-time PCR (ChIP-qPCR) assay demonstrated that the TGFBR1-SMAD3 pathway could enhance Ccnd2 promoter activity and thus upregulate Ccnd2 expression. Finally, estrogen receptor 2 (ESR2) functioned as a transcription factor by directly binding to the miR-135a promoter region and decreasing the transcriptional activity of miR-135a. Taken together, our study reveals a pro-survival mechanism of ESR2/miR-135a/Tgfbr1/Ccnd2 axis for GC growth, and also provides a novel target for the improvement of female fertility.

MiR-34c-5p promotes granulosa cells apoptosis by targeting Bcl2 in broody goose (Anser cygnoides)

Goose (Anser cygnoides) are highly broody with low egg production, and large number of granulosa cells undergo apoptosis during broodiness. Our previous study has found that miR-34c-5p was highly abundant in the ovary of goose with broodiness phenotype. However, the mechanism that miR-34c-5p regulates granulosa cells function remains unclear. Here, we demonstrated that broody goose had higher levels of miR-34c-5p than that in laying goose by qRT-PCR. The dual luciferase reporter assay showed that Bcl2 was identified as a direct target of miR-34c-5p, which could be negatively regulated by miR-34c-5p. Furthermore, over-expression of miR-34c-5p significantly increased the rate of apoptosis and slowed down the proliferation of granulosa cells by inhibiting the Bcl2 expression, whereas the opposite trend was obtained when granulosa cells were supplemented with miR-34c-5p inhibitors. In addition, Bcl2 mRNA level was lower in goose with a brooding phenotype than that in goose with an egg-laying phenotype. Taken together, the data suggested that miR-34c-5p regulated granulosa cells apoptosis and brooding behavior by targeting Bcl2, which not only contribute to reveal the potential mechanism of miR-34c-5p underlying granulosa cells apoptosis in goose, but also provides an effective strategy to reduce the incidence of broodiness and improve the egg production.

Transcriptomic Data Analyses Reveal That Sow Fertility-Related lincRNA NORFA Is Essential for the Normal States and Functions of Granulosa Cells

NORFA, the first lincRNA associated with sow fertility, has been shown to control granulosa cell (GC) functions and follicular atresia. However, the underlying mechanism is not fully understood. In this study, RNA-seq was performed and we noticed that inhibition of NORFA led to dramatic transcriptomic alterations in porcine GCs. A total of 1,272 differentially expressed transcripts were identified, including 1167 DEmRNAs and 105 DEmiRNAs. Furthermore, protein–protein interaction, gene-pathway function, and TF–miRNA–mRNA regulatory networks were established and yielded four regulatory modules with multiple hub genes, such as AR, ATG5, BAK1, CENPE, NR5A1, NFIX, WNT5B, ssc-miR-27b, and ssc-miR-126. Functional assessment showed that these hub DEGs were mainly enriched in TGF-β, PI3K-Akt, FoxO, Wnt, MAPK, and ubiquitin pathways that are essential for GC states (apoptosis and proliferation) and functions (hormone secretion). In vitro, we also found that knockdown of NORFA in porcine GCs significantly induced cell apoptosis, impaired cell viability, and suppressed 17β-estradiol (E2) synthesis. Notably, four candidate genes for sow reproductive traits (INHBA, NCOA1, TGFβ-1, and TGFBR2) were also identified as potential targets of NORFA. These findings present a panoramic view of the transcriptome in NORFA-reduced GCs, highlighting that NORFA, a candidate lincRNA for sow fertility, is crucial for the normal states and functions of GCs.

MiR-21-5p actions at the Smad7 gene during pig ovarian granulosa cell apoptosis

MicroRNAs (miRNAs) are endogenous non-coding RNAs in eukaryotic cells that modulate apoptosis of ovarian granulosa cells (GCs), which is an important cause of mammalian follicular atresia. In the present study, associations were evaluated between miR-21-5p and the extent of Smad7 protein production in regulation of ovarian granulosa cell (pGC) apoptosis. There was detection of miR-21-5p and Smad7 primarily in the cytoplasm and nucleus of pGCs, respectively. When there was an enhanced abundance of miR-21-5p and decreased abundance of Smad7 there were similar effects in pGCs, including inducing proliferation, inhibiting apoptosis, increasing the number of cells in S and G2/M phases, increasing serum estradiol, and decreasing serum progesterone concentrations. Furthermore, the Smad7 mRNA transcript was identified as a target for miR-21-5p actions, with enhanced abundances of miR-21-5p being associated with a lesser abundance of Smad7 mRNA transcript and protein in pGCs. Overall, results from the present study indicate that miR-21-5p has actions on the Smad7 mRNA transcript during the process of ovarian granulosa cell apoptosis in pigs.

The Effect of Alpha Mangostin on Epithelial-Mesenchymal Transition on Human Hepatocellular Carcinoma HepG2 Cells Surviving Sorafenib via TGF-β/Smad Pathways

Purpose: This study was intended to find out the impact of alpha mangostin administration on the epithelial-mesenchymal transition (EMT) markers and TGF-β/Smad pathways in hepatocellular carcinoma Hep-G2 cells surviving sorafenib.

Methods: Hepatocellular carcinoma HepG2 cells were treated with sorafenib 10 μM. Cells surviving sorafenib treatment (HepG2^surv) were then treated vehicle, sorafenib, alpha mangostin, or combination of sorafenib and alpha mangostin. Afterward, cells were observed for their morphology with an inverted microscope and counted for cell viability. The concentrations of transforming growth factor (TGF)-β1 in a culture medium were examined using ELISA. The mRNA expressions of TGF-β1, TGF-β1-receptor, Smad3, Smad7, E-cadherin, and vimentin were evaluated using quantitative reverse transcriptase–polymerase chain reaction. The protein level of E-cadherin was also determined using western blot analysis.

Results: Treatment of alpha mangostin and sorafenib caused a significant decrease in the viability of sorafenib-surviving HepG2 cells versus control (both groups with P <0.05). Our study found that alpha mangostin treatment increased the expressions of vimentin (P <0.001 versus control). In contrast, alpha mangostin treatment tends to decrease the expressions of Smad7 and E-cadherin (both with P >0.05). In line with our findings, the expressions of TGF-β1 and Smad3 are significantly upregulated after alpha mangostin administration (both with P <0.05) versus control.

Conclusion: Alpha mangostin reduced cell viability of sorafenib-surviving HepG2 cells; however, it also enhanced epithelial–mesenchymal transition markers by activating TGF-β/Smad pathways.

MiR-214-3p promotes proliferation and inhibits estradiol synthesis in porcine granulosa cells

Background

Granulosa cells (GCs) proliferation and estradiol synthesis significantly affect follicular development. The miR-214-3p expression in the ovarian tissues of high-yielding sows is higher than that in low-yielding sows, indicating that miR-214-3p may be involved in sow fertility. However, the functions and mechanisms of miR-214-3p on GCs are unclear. This study focuses on miR-214-3p in terms of the effects on GCs proliferation and estradiol synthesis.

Results

Our findings revealed that miR-214-3p promotes proliferation and inhibits estradiol synthesis in porcine GCs. MiR-214-3p can increase the percentage of S-phase cells, the number of EdU labeled positive cells, and cell viability. However, E₂ concentration was reduced after miR-214-3p agomir treatment. We also found that miR-214-3p up-regulates the expression of cell cycle genes including cell cycle protein B (Cyclin B), cell cycle protein D (Cyclin D), cell cycle protein E (Cyclin E), and cyclin-dependent kinase 4 (CDK4) at the transcription and translation levels, but down-regulates the mRNA and protein levels of cytochrome P450 family 11 subfamily A member 1 (CYP11A1), cytochrome P450 family 19 subfamily A member 1 (CYP19A1), and steroidogenic acute regulatory protein (StAR) (i.e., the key enzymes in estradiol synthesis). On-line prediction, bioinformatics analysis, a luciferase reporter assay, RT-qPCR, and Western blot results showed that the target genes of miR-214-3p in proliferation and estradiol synthesis are Mfn2 and NR5A1, respectively.

Conclusions

Our findings suggest that miR-214-3p plays an important role in the functional regulation of porcine GCs and therefore may be a target gene for regulating follicular development.

MiR-581/SMAD7 Axis Contributes to Colorectal Cancer Metastasis: A Bioinformatic and Experimental Validation-Based Study

Metastasis is a well-known poor prognostic factor and primary cause of mortality in patients with colorectal cancer (CRC). Recently, with the progress of high through-put sequencing, aberrantly expressed non-coding RNAs (ncRNAs) were found to participate in the initiation and development of cancer. However, the mechanisms of ncRNA-mediated regulation of metastasis in CRC remain largely unknown. In this study, we systematically analyzed the expression network of microRNAs (miRNAs) and genes in CRC metastasis using bioinformatics, and discovered that the miR-581/SMAD7 axis could be a potential factor that drives CRC metastasis. A dual luciferase report assay and protein analysis confirmed the binding relationship between miR-581 and SMAD7. Further functional assays revealed that miR-581 inhibition could suppress cell proliferation and induce apoptosis in SW480 cells. Up-regulation or down-regulation of miR-581 could both affect cell invasion capacity and modulate epithelial to mesenchymal transition (EMT) via a SMAD7/TGFβ signaling pathway. In conclusion, our findings elucidated that miR-581/SMAD7 could be essential for CRC metastasis, and may serve as a potential therapeutic target for CRC patients.

miR-424 Promotes Bovine Adipogenesis Through an Unconventional Post-Transcriptional Regulation of STK11

Adipose tissue is the largest energy reservoir and secretory organ in the animal body, and is essential for maintaining normal physiological functions and metabolic balance. MicroRNAs regulate the process of adipogenic differentiation through post-transcriptional regulatory mechanisms. In the present study, miR-424 was upregulated during bovine adipocyte differentiation both in vivo and in vitro. The overexpression and interference of miR-424 exhibited the positive regulatory role in the differentiation of bovine adipocytes. Furthermore, miR-424 directly binds to the three prime untranslated region (3' UTR) of serine/threonine kinase 11 (STK11, also called LKB1), a master upstream gene in the AMP-activated protein kinase (AMPK) cascade, and up-regulates its expression. Functional studies showed that the knockdown of STK11 attenuated the pro-adipogenic effect of miR-424. Post-transcriptional regulation of STK11 by miR-424 was mediated potentially in an RNA binding protein (RBP) binding site-dependent manner. In conclusion, our study shows that miR-424 promotes bovine adipogenesis through an unconventional post-transcriptional regulation of STK11, which may serve as a potential target for the regulation of bovine adipogenesis and the improvement of livestock breeding efficiency.

The Role of MicroRNAs in Mammalian Fertility: From Gametogenesis to Embryo Implantation

The genetic codes inscribed during two key developmental processes, namely gametogenesis and embryogenesis, are believed to determine subsequent development and survival of adult life. Once the embryo is formed, its further development mainly depends on its intrinsic characteristics, maternal environment (the endometrial receptivity), and the embryo–maternal interactions established during each phase of development. These developmental processes are under strict genetic regulation that could be manifested temporally and spatially depending on the physiological and developmental status of the cell. MicroRNAs (miRNAs), one of the small non-coding classes of RNAs, approximately 19–22 nucleotides in length, are one of the candidates for post-transcriptional developmental regulators. These tiny non-coding RNAs are expressed in ovarian tissue, granulosa cells, testis, oocytes, follicular fluid, and embryos and are implicated in diverse biological processes such as cell-to-cell communication. Moreover, accumulated evidences have also highlighted that miRNAs can be released into the extracellular environment through different mechanisms facilitating intercellular communication. Therefore, understanding miRNAs mediated regulatory mechanisms during gametogenesis and embryogenesis provides further insights about the molecular mechanisms underlying oocyte/sperm formation, early embryo development, and implantation. Thus, this review highlights the role of miRNAs in mammalian gametogenesis and embryogenesis and summarizes recent findings about miRNA-mediated post-transcriptional regulatory mechanisms occurring during early mammalian development.

miR-181a promotes porcine granulosa cell apoptosis by targeting TGFBR1 via the activin signaling pathway

Activin/Smad3 signaling plays a pivotal role in follicle development and atresia. However, the precise mechanisms underlying this process are not yet fully understood. Herein, we identified miR-181a as a central component of activin/Smad3-mediated follicle atresia. miR-181a was strikingly upregulated in porcine atretic follicles, which induced the apoptosis of porcine granulosa cells (GCs) in vitro. Furthermore, the transforming growth factor-β type 1 receptor (TGFBR1) was confirmed as a direct target of miR-181a by bioinformatics analysis and luciferase assays. Transfection with an miR-181a agomir repressed the TGFBR1 mRNA and protein levels. In addition, TGFBR1 overexpression repressed GC apoptosis, whereas TGFBR1 inhibition promoted GC apoptosis. miR-181a overexpression downregulated the phosphorylation of Smad3 and blocked the activation of TGF-β signaling. Moreover, activin A downregulated miR-181a expression and upregulated the TGFBR1 and p-Smad3 protein levels. Collectively, these data suggest that miR-181a regulates porcine GC apoptosis by targeting TGFBR1 via the activin signaling pathway.

Computational Network Analysis Identifies Evolutionarily Conserved miRNA Gene Interactions Potentially Regulating Immune Response in Bovine Trypanosomosis

Bovine trypanosomosis is a devastating disease that causes huge economic loss to the global cattle industry on a yearly basis. Selection of accurate biomarkers are important in early disease diagnosis and treatment. Of late, micro-RNAs (miRNAs) are becoming the most useful biomarkers for both infectious and non-infectious diseases in humans, but this is not the case in animals. miRNAs are non-coding RNAs that regulate gene expression through binding to the 3'-, 5'-untranslated regions (UTR) or coding sequence (CDS) region of one or more target genes. The molecular identification of miRNAs that regulates the expression of immune genes responding to bovine trypanosomosis is poorly defined, as is the possibility that these miRNAs could serve as potential biomarkers for disease diagnosis and treatment currently unknown. To this end, we utilized in silico tools to elucidate conserved miRNAs regulating immune response genes during infection, in addition to cataloging significant genes. Based on the p value of 1.77E-32, we selected 25 significantly expressed immune genes. Using prediction analysis, we identified a total of 4,251 bovine miRNAs targeting these selected genes across the 3'UTR, 5'UTR and CDS regions. Thereafter, we identified candidate miRNAs based on the number of gene targets and their abundance at the three regions. In all, we found the top 13 miRNAs that are significantly conserved targeting 7 innate immune response genes, including bta-mir-2460, bta-mir-193a, bta-mir-2316, and bta-mir-2456. Our gene ontology analysis suggests that these miRNAs are involved in gene silencing, cellular protein modification process, RNA-induced silencing complex, regulation of humoral immune response mediated by circulating immunoglobulin and negative regulation of chronic inflammatory response, among others. In conclusion, this study identifies specific miRNAs that may be involved in the regulation of gene expression during bovine trypanosomosis. These miRNAs have the potential to be used as biomarkers in the animal and veterinary research community to facilitate the development of tools for early disease diagnosis/detection, drug targeting, and the rational design of drugs to facilitate disease treatment.

ALK4-SMAD2/3-SMAD4 signaling mediates the activin A-induced suppression of PTX3 in human granulosa-lutein cells

As one of the members of the transforming growth factor-β (TGF-β) superfamily, activin A plays an important role in regulating follicular development and oocyte maturation. Pentraxin 3 (PTX3) is the key component that promotes the process of cumulus expansion during mammalian ovulation. At present, the regulation of PTX3 expression in human granulosa cells remains largely unknown. This study aimed to examine the effects of activin A on the expression of PTX3 in human granulosa-lutein (hGL) cells and to investigate the underlying molecular mechanisms. Using an established immortalized hGL cell line (SVOG) and primary hGL cells as study models, we demonstrated that activin A significantly increased the phosphorylation of SMAD2 and SMAD3, which suppressed the expression of PTX3 at both the mRNA and protein levels. Additionally, these effects induced by activin A were completely reversed by pretreatment with the TGF-β type I receptor inhibitor SB431542 and knockdown of ALK4. Furthermore, knockdown of SMAD2, SMAD3, or SMAD4 completely reversed the activin A-induced suppressive effects on PTX3 expression. Notably, the ChIP analyses demonstrated that phosphorylated SMADs could bind to human PTX3 promoter. Collectively, our results showed that the ALK4-SMAD2/3-SMAD4 signaling pathway most likely mediates the suppressive effect of activin A on PTX3 expression in hGL cells.

Endogenous and Exogenous Modulation of Nrf2 Mediated Oxidative Stress Response in Bovine Granulosa Cells: Potential Implication for Ovarian Function

Nrf2 is a redox sensitive transcription factor regulating the expression of antioxidant genes as defense mechanism against various stressors. The aim of this study is to investigate the potential role of noncoding miRNAs as endogenous and quercetin as exogenous regulators of Nrf2 pathway in bovine granulosa cells. For this cultured granulosa cells were used for modulation of miRNAs (miR-28, 153 and miR-708) targeting the bovine Nrf2 and supplementation of quercentin to investigate the regulatory mechanisms of the Nrf2 antioxidant system. Moreover, cultured cells were treated with hydrogen peroxide to induce oxidative stress in those cells. Our results showed that, oxidative stress activated the expression of Nrf2 as a defense mechanism, while suppressing the expression of those miRNAs. Overexpression of those miRNAs resulted in downregulation of Nrf2 expression resulted in higher ROS accumulation, reduced mitochondrial activity and cellular proliferation. Quercetin supplementation showed its protective role against oxidative stress induced by H₂O₂ by inducing the expression of antioxidant enzymes. In conclusion, this study highlighted the involvement of miR-153, miR-28 and miR-708 in regulatory network of Nrf2 mediated antioxidant system in bovine granulosa cells function. Furthermore, quercetin at a low dose played a protective role in bovine granulosa cells against oxidative stress damage.

H19X-encoded miR-424(322)/-503 cluster: emerging roles in cell differentiation, proliferation, plasticity and metabolism

miR-424(322)/-503 are mammal-specific members of the extended miR-15/107 microRNA family. They form a co-expression network with the imprinted lncRNA H19 in tetrapods. miR-424(322)/-503 regulate fundamental cellular processes including cell cycle, epithelial-to-mesenchymal transition, hypoxia and other stress response. They control tissue differentiation (cardiomyocyte, skeletal muscle, monocyte) and remodeling (mammary gland involution), and paradoxically participate in tumor initiation and progression. Expression of miR-424(322)/-503 is governed by unique mechanisms involving sex hormones. Here, we summarize current literature and provide a primer for future endeavors.

The Role of microRNAs in Ovarian Granulosa Cells in Health and Disease

The granulosa cell (GC) is a critical somatic component of the ovary. It is essential for follicle development by supporting the developing oocyte, proliferating and producing sex steroids and disparate growth factors. Knowledge of the GC's function in normal ovarian development and function, and reproductive disorders, such as polycystic ovary syndrome (PCOS) and premature ovarian failure (POF), is largely acquired through clinical studies and preclinical animal models. Recently, microRNAs have been recognized to play important regulatory roles in GC pathophysiology. Here, we examine the recent findings on the role of miRNAs in the GC, including four related signaling pathways (Transforming growth factor-β pathway, Follicle-stimulating hormones pathway, hormone-related miRNAs, Apoptosis-related pathways) and relevant diseases. Therefore, miRNAs appear to be important regulators of GC function in both physiological and pathological conditions. We suggest that targeting specific microRNAs is a potential therapeutic option for treating ovary-related diseases, such as PCOS, POF, and GCT.

In silico identification of conserved miRNAs and their selective target gene prediction in indicine (Bos indicus) cattle

The modern cattle was domesticated from aurochs, sharing its physiological traits into two subspecies Bos taurus and Bos indicus. MicroRNAs (miRNAs) are a class of non-coding short RNAs of ~22nt which have a key role in the regulation of many cellular and physiological processes in the animal. The current study was aimed to predict and annotate the potential mutations in indicine miRNAs throughout the genome using de novo and homology-based in silico approaches. Genome-wide mapping was performed in available indicine assembly by the homology-based approach and 768 miRNAs were recovered out of 808 reported taurine miRNAs belonging to 521 unique mature miRNA families. While 42 precursors were dropped due to lack of secondary miRNA structure, increasing stringency or decreasing similarity between the two genomes' miRNA. Increasing tendency of miRNAs incidence was observed on chr5, chr7, chr8, chr12 and chr21 with 19 polycistronic miRNA within 1-kilobase distance throughout the indicine genome. Notably, 12 miRNAs showed copy number variation. Eighteen miRNAs showed a mutation in their mature sequences in which eight were found in their seed region. Whilst in de novo based approach, 12 novel potential miRNAs on Y chromosome in indicine cattle along with a new miRNA (bind-miR-1264) on chrX were found. The final data set is annotated and explains the impending target genes that are responsible for enhanced immunity, heat tolerance and disease tolerance regulation in indicine. The study conforms to better understanding and perceptive approach towards indicine genome.