Identification of long non-coding RNAs in the immature and mature rat anterior pituitary

Sequencing of the Pituitary Transcriptome after GnRH Treatment Uncovers the Involvement of lncRNA-m23b/miR-23b-3p/CAMK2D in FSH Synthesis and Secretion

The pituitary gland is a key participant in the hypothalamic–pituitary–gonadal axis, as it secretes a variety of hormones and plays an important role in mammalian reproduction. Gonadotrophin-releasing hormone(GnRH) signaling molecules can bind to GnRH receptors on the surfaces of adenohypophysis gonadotropin cells and regulate the expression of follicle-stimulating hormone(FSH) and luteinizing hormone(LH) through various pathways. An increasing number of studies have shown that noncoding RNAs mediate the regulation of GnRH signaling molecules in the adenohypophysis. However, the expression changes and underlying mechanisms of genes and noncoding RNAs in the adenohypophysis under the action of GnRH remain unclear. In the present study, we performed RNA sequencing (RNA-seq) of the rat adenohypophysis before and after GnRH treatment to identify differentially expressed mRNAs, lncRNAs, and miRNAs. We found 385 mRNAs, 704 lncRNAs, and 20 miRNAs that were significantly differentially expressed in the rat adenohypophysis. Then, we used a software to predict the regulatory roles of lncRNAs as molecular sponges that compete with mRNAs to bind miRNAs, and construct a GnRH-mediated ceRNA regulatory network. Finally, we enriched the differentially expressed mRNAs, lncRNA target genes, and ceRNA regulatory networks to analyze their potential roles. Based on the sequencing results, we verified that GnRH could affect FSH synthesis and secretion by promoting the competitive binding of lncRNA-m23b to miR-23b-3p to regulate the expression of Calcium/Calmodulin Dependent Protein Kinase II Delta(CAMK2D). Our findings provide strong data to support exploration of the physiological processes in the rat adenohypophysis under the action of GnRH. Furthermore, our profile of lncRNA expression in the rat adenohypophysis provides a theoretical basis for research on the roles of lncRNAs in the adenohypophysis.

LncRNA-m18as1 competitively binds with miR-18a-5p to regulate follicle-stimulating hormone secretion through the Smad2/3 pathway in rat primary pituitary cells

Long noncoding RNAs (lncRNAs) are expressed in different species and different tissues, and perform different functions, but little is known about their involvement in the synthesis or secretion of follicle-stimulating hormone (FSH). In general, we have revealed lncRNA‍‒‍microRNA (miRNA)‍‒‍‍messenger RNA (mRNA) interactions that may play important roles in rat primary pituitary cells. In this study, a new lncRNA was identified for the first time. First, we analyzed the gene expression of lncRNA-m18as1 in different tissues and different stages by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and observed the localization of lncRNA-m18as1 with fluorescence in situ hybridization, which indicated that this lncRNA was distributed mainly in the cytoplasm. Next, we used RT-qPCR and enzyme-linked immunosorbent assay (ELISA) to analyze the regulation of FSH synthesis and secretion after overexpression or knockdown of lncRNA-m18as1 and found that lncRNA-m18as1 was positively correlated with FSH synthesis and secretion. In addition, mothers against decapentaplegic homolog 2 (Smad2) was highly expressed in our sequencing results. We also screened miR-18a-5p from our sequencing results as a miRNA that may bind to lncRNA-m18as1 and Smad2. We used RNA immunoprecipitation-qPCR (RIP-qPCR) and/or dual luciferase assays to confirm that lncRNA-m18as1 interacted with miR-18a-5p and miR-18a-5p interacted with Smad2. Fluorescence in situ hybridization (FISH) showed that lncRNA-m18as1 and miR-18a-5p were localized mainly in the cytoplasm. Finally, we determined the relationship among lncRNA-m18as1, miR-18a-5p, and the Smad2/3 pathway. Overall, we found that lncRNA-m18as1 acts as a molecular sponge of miR-18a-5p to regulate the synthesis and secretion of FSH through the Smad2/3 pathway.

Comparative Transcriptomic Analysis of Hu Sheep Pituitary Gland Prolificacy at the Follicular and Luteal Phases

The pituitary gland directly regulates the reproduction of domestic animals. Research has increasingly focused on the potential regulatory mechanism of non-coding RNA in pituitary development. Little is known about the differential expression pattern of lncRNAs in Hu sheep, a famous sheep breed with high fecundity, and its role in the pituitary gland between the follicular phase and luteal phase. Herein, to identify the transcriptomic differences of the sheep pituitary gland during the estrus cycle, RNA sequencing (RNA-Seq) was performed. The results showed that 3529 lncRNAs and 16,651 mRNAs were identified in the pituitary gland. Among of them, 144 differentially expressed (DE) lncRNA transcripts and 557 DE mRNA transcripts were screened in the follicular and luteal phases. Moreover, GO and KEGG analyses demonstrated that 39 downregulated and 22 upregulated genes interacted with pituitary functions and reproduction. Lastly, the interaction of the candidate lncRNA XR_001039544.4 and its targeted gene LHB were validated in sheep pituitary cells in vitro. LncRNA XR_001039544.4 and LHB showed high expression levels in the luteal phase in Hu sheep. LncRNA XR_001039544.4 is mainly located in the cytoplasm, as determined by FISH analysis, indicating that XR_001039544.4 might act as competing endogenous RNAs for miRNAs to regulate LHB. LncRNA XR_001039544.4 knockdown significantly inhibited LH secretion and cell proliferation. LncRNA XR_001039544.4 may regulate the secretion of LH in the luteal-phase pituitary gland via affecting cell proliferation. Taken together, these findings provided genome-wide lncRNA- and mRNA-expression profiles for the sheep pituitary gland between the follicular and luteal phases, thereby contributing to the elucidation of the molecular mechanisms of pituitary function.

Rno_circ_0001004 Acts as a miR-709 Molecular Sponge to Regulate the Growth Hormone Synthesis and Cell Proliferation

(1) Background: As a novel type of non-coding RNA with a stable closed-loop structure, circular RNA (circRNA) can interact with microRNA (miRNA) and influence the expression of miRNA target genes. However, circRNA involved in pituitary growth hormone (GH) regulation is poorly understood. Our previous study revealed protein kinase C alpha (PRKCA) as the target gene of miR-709. Currently, the expression and function of rno_circRNA_0001004 in the rat pituitary gland is not clarified; (2) Methods: In this study, both bioinformatics analysis and dual-luciferase report assays showed a target relationship between rno_circRNA_0001004 and miR-709. Furthermore, the rno_circRNA_0001004 overexpression vector and si-circ_0001004 were constructed and transfected into GH₃ cells; (3) Results: We found that rno_circRNA_0001004 expression was positively correlated with the PRKCA gene and GH expression levels, while it was negatively correlated with miR-709. In addition, overexpression of rno-circ_0001004 also promoted proliferation and relieved the inhibition of miR-709 in GH₃ cells; (4) Conclusions: Our findings show that rno_circ_0001004 acts as a novel sponge for miR-709 to regulate GH synthesis and cell proliferation, and are the first case of discovery of the regulatory role of circRNA_0001004 in pituitary GH.

An Exploration of Non-Coding RNAs in Extracellular Vesicles Delivered by Swine Anterior Pituitary

Extracellular vesicles are lipid bilayer-delimited particles carrying proteins, lipids, and small RNAs. Previous studies have demonstrated that they had regulatory functions both physiologically and pathologically. However, information remains inadequate on extracellular vesicles from the anterior pituitary, a key endocrine organ in animals and humans. In this study, we separated and identified extracellular vesicles from the anterior pituitary of the Duroc swine model. Total RNA was extracted and RNA-seq was performed, followed by a comprehensive analysis of miRNAs, lncRNAs, and circRNAs. Resultantly, we obtained 416 miRNAs, 16,232 lncRNAs, and 495 circRNAs. Furthermore, GO and KEGG enrichment analysis showed that the ncRNAs in extracellular vesicles may participate in regulating intracellular signal transduction, cellular component organization or biogenesis, small molecule binding, and transferase activity. The cross-talk between them also suggested that they may play an important role in the signaling process and biological regulation. This is the first report of ncRNA data in the anterior pituitary extracellular vesicles from the duroc swine breed, which is a fundamental resource for exploring detailed functions of extracellular vesicles from the anterior pituitary.

Enhancing Gonadotrope Gene Expression Through Regulatory lncRNAs

The world of long non-coding RNAs (lncRNAs) has opened up massive new prospects in understanding the regulation of gene expression. Not only are there seemingly almost infinite numbers of lncRNAs in the mammalian cell, but they have highly diverse mechanisms of action. In the nucleus, some are chromatin-associated, transcribed from transcriptional enhancers (eRNAs) and/or direct changes in the epigenetic landscape with profound effects on gene expression. The pituitary gonadotrope is responsible for activation of reproduction through production and secretion of appropriate levels of the gonadotropic hormones. As such, it exemplifies a cell whose function is defined through changes in developmental and temporal patterns of gene expression, including those that are hormonally induced. Roles for diverse distal regulatory elements and eRNAs in gonadotrope biology have only just begun to emerge. Here, we will present an overview of the different kinds of lncRNAs that alter gene expression, and what is known about their roles in regulating some of the key gonadotrope genes. We will also review various screens that have detected differentially expressed pituitary lncRNAs associated with changes in reproductive state and those whose expression is found to play a role in gonadotrope-derived nonfunctioning pituitary adenomas. We hope to shed light on this exciting new field, emphasize the open questions, and encourage research to illuminate the roles of lncRNAs in various endocrine systems.

Advances in the Regulation of Mammalian Follicle-Stimulating Hormone Secretion

Simple Summary

The reproduction of mammals is regulated by the hypothalamic-pituitary-gonadal axis. Follicle stimulating hormone, as one of the gonadotropins secreted by the pituitary gland, plays an immeasurable role. This article mainly reviews the molecular basis and classical signaling pathways that regulate the synthesis and secretion of follicle stimulating hormone, and summarizes its internal molecular mechanism, which provides a certain theoretical basis for the research of mammalian reproduction regulation and the application of follicle stimulating hormone in production practice.

Abstract

Mammalian reproduction is mainly driven and regulated by the hypothalamic-pituitary-gonadal (HPG) axis. Follicle-stimulating hormone (FSH), which is synthesized and secreted by the anterior pituitary gland, is a key regulator that ultimately affects animal fertility. As a dimeric glycoprotein hormone, the biological specificity of FSH is mainly determined by the β subunit. As research techniques are being continuously innovated, studies are exploring the underlying molecular mechanism regulating the secretion of mammalian FSH. This article will review the current knowledge on the molecular mechanisms and signaling pathways systematically regulating FSH synthesis and will present the latest hypothesis about the nuclear cross-talk among the various endocrine-induced pathways for transcriptional regulation of the FSH β subunit. This article will provide novel ideas and potential targets for the improved use of FSH in livestock breeding and therapeutic development.

Nanopore long-read RNAseq reveals regulatory mechanisms of thermally variable reef environments promoting heat tolerance of scleractinian coral Pocillopora damicornis

Some scleractinian corals exhibit high thermal adaptability to climate changes, although the mechanism of their adaptation is unclear. This study investigated the adaptability of scleractinian coral Pocillopora damicornis to thermally variable reef environments by applying a nanopore-based RNA sequencing method to characterize different transcription responses that promote heat tolerance of P. damicornis. We identified 1414 novel genes and optimized 6256 mis-annotated loci. Based on full-length transcriptome data, we identified complex alternative polyadenylation and alternative splicing events, which can improve our understanding of the genome annotation and gene structures of P. damicornis. Furthermore, we constructed differentially expressed lncRNA-mRNA co-expression networks, which may play a crucial role in the P. damicornis thermal adaptive response. KEGG function enrichment analysis revealed that P. damicornis from the high-temperature pool had a lower metabolic rate than that from the low-temperature pool. We hypothesize that metabolic readjustment, in the form of a lower metabolic rate, positively correlated with increased heat tolerance in P. damicornis in thermally variable reef environments. Our study provides novel insights into lncRNAs that promote thermally tolerance of scleractinian corals in the thermally variable reef environment, suggesting potential mechanisms for their adaptation to global warming in the future.

Genome-wide identification and functional prediction of long non-coding RNAs in Sprague-Dawley rats during heat stress

Background

Heat stress (HS) is a major stress event in the life of an animal, with detrimental upshots in production and health. Long-non-coding RNAs (lncRNAs) play an important role in many biological processes by transcriptional regulation. However, no research has been reported on the characterization and functionality of lncRNAs in heat-stressed rats.

Results

We studied expression levels of lncRNAs in rats during HS, using strand-specific RNA sequencing. Six rats, three in each of Control (22 ± 1 °C) and H120 (42 °C for 120 min) experimental groups, were used to screen for lncRNAs in their liver and adrenal glands. Totally, 4498 and 7627 putative lncRNAs were identified in liver and adrenal glands of the Control and H120 groups, respectively. The majority of lncRNAs were relatively shorter and contained fewer exons than protein-coding transcripts. In total, 482 (174 up-regulated and 308 down-regulated) and 271 (126 up-regulated and 145 down-regulated) differentially-expressed lncRNAs (DElncRNAs, P < 0.05) were identified in the liver and adrenal glands of the Control and H120 groups, respectively. Furthermore, 1274, 121, and 73 target differentially-expressed genes (DEGs) in the liver were predicted to interact with DElncRNAs based on trans−/cis- and sequence similarity regulatory modes. Functional annotation analyses indicated that these DEGs were mostly significantly enriched in insulin signalling, myeloid leukaemia, and glucagon signalling pathways. Similarly, 437, 73 and 41 target DEGs in the adrenal glands were mostly significantly enriched in the cell cycle (trans-prediction) and lysosome pathways (cis-prediction). The DElncRNAs interacting with DEGs that encode heat shock proteins (HSPs) may play an important role in HS response, which include Hsf4, Dnaja1, Dnajb4, Hsph1 and Hspb1 in the liver, and Dnajb13 and Hspb8 in the adrenal glands. The strand-specific RNA sequencing findings were also further verified through RT-qPCR.

Conclusions

This study is the first to provide a detailed characterization and functional analysis of expression levels of lncRNAs in liver and adrenal glands of heat-stressed rats, which provides basis for further studies on the biological functions of lncRNAs under heat stress in rats and other mammalian species.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-021-07421-8.

Differentially expressed lncRNA-m433s1 regulates FSH secretion by functioning as a miRNA sponge in male rat anterior pituitary cells†

Long noncoding RNAs (lncRNAs) are important regulators that have multiple functions in a variety of biological processes. However, the contributions of lncRNAs to follicle-stimulating hormone (FSH) secretion remain largely unknown. In this study, we first identified a novel lncRNA, lncRNA-m433s1, as an intergenic lncRNA located in the cytoplasm. We next used MS2-RIP assays to demonstrate that lncRNA-m433s1 interacted with miR-433. Furthermore, we detected the levels of lncRNA-m433s1, miR-433, and Fshβ expression, FSH concentrations, and apoptosis upon overexpression and knockdown of lncRNA-m433s1, revealing that lncRNA-m433s1 upregulated Fshβ expression. Globally, lncRNA-m433s1 reduced the inhibitory effect of miR-433 on Fshβ and further regulated FSH secretion as a competing endogenous RNA (ceRNA) by sponging miR-433. This ceRNA model will provide novel insight into the regulatory mechanisms of lncRNAs associated with rat reproduction.

Genome-Wide Analysis and Function Prediction of Long Noncoding RNAs in Sheep Pituitary Gland Associated with Sexual Maturation

Long noncoding RNA (lncRNA) plays a crucial role in the hypothalamic-pituitary-testis (HPT) axis associated with sheep reproduction. The pituitary plays a connecting role in the HPT axis. However, little is known of their expression pattern and potential roles in the pituitary gland. To explore the potential lncRNAs that regulate the male sheep pituitary development and sexual maturation, we constructed immature and mature sheep pituitary cDNA libraries (three-month-old, TM, and nine-month-old, NM, respectively, n = 3) for lncRNA and mRNA high-throughput sequencing. Firstly, the expression of lncRNA and mRNA were comparatively analyzed. 2417 known lncRNAs and 1256 new lncRNAs were identified. Then, 193 differentially expressed (DE) lncRNAs and 1407 DE mRNAs were found in the pituitary between the two groups. Moreover, mRNA-lncRNA interaction network was constructed according to the target gene prediction of lncRNA and functional enrichment analysis. Five candidate lncRNAs and their targeted genes HSD17B12, DCBLD2, PDPK1, GPX3 and DLL1 that enriched in growth and reproduction related pathways were further filtered. Lastly, the interaction of candidate lncRNA TCONS_00066406 and its targeted gene HSD17B12 were validated in in vitro of sheep pituitary cells. Our study provided a systematic presentation of lncRNAs and mRNAs in male sheep pituitary, which revealed the potential role of lncRNA in male reproduction.

Genomewide analysis of circular RNA in pituitaries of normal and heat-stressed sows

Background

As a newly characterized type of noncoding RNA, circular RNA (circRNA) has been shown to have functions in diverse biological processes of animals. It has been reported that several noncoding RNAs may regulate animals’ response to heat stress which can be easily induced by hyperthermia in summer. However, the expression and functions of circRNAs in the pituitary of sows and whether they participate in heat stress adaption are still unclear.

Results

In this study, we found that high temperature over the thermoneutral zone of sows during the summer increased the serum heat shock protein 70 (HSP70) level, decreased the superoxide dismutase (SOD) vitality and prolactin (PRL) concentration, and induced heat stress in sows. Then, we explored circRNA in the pituitary of heat-stressed and normal sows using RNA sequencing and bioinformatics analysis. In total, 12,035 circRNAs were detected, with 59 circRNAs differentially expressed, including 42 up-regulated and 17 down-regulated circRNAs in pituitaries of the heat-stressed sows. Six randomly selected circRNAs were identified through reverse transcription PCR followed by DNA sequencing and other 7 randomly selected differentially expressed circRNAs were verified by quantitative real-time PCR analysis. The predicted target genes regulated by circRNAs through sponging microRNAs (miRNAs) were enriched in metabolic pathway. Furthermore, the predicted circRNA–miRNA–mRNA interactions showed that some circRNAs might sponge miRNAs to regulate pituitary-specific genes and heat shock protein family members, indicating circRNA’s roles in pituitary hormone secretion and heat stress response.

Conclusions

Our results provided a meaningful reference to understand the functions of circRNA in the porcine pituitary and the mechanisms by which circRNA may participate in animals’ response to heat stress.

Screening and evaluating of long non-coding RNAs in prenatal and postnatal pituitary gland of sheep

Long non-coding RNAs are transcribed into RNA molecules that are >200 nucleotides in length. However, the expression and function analysis of lncRNAs in the sheep pituitary gland are still lacking. In this study, we identified 1755 lncRNAs (545 annotated lncRNAs and 1210 novel lncRNAs) from RNA-seq data in the pituitary gland of embryonic and adult sheep. A total of 235 lncRNAs were differentially expressed between embryonic and adult group. We verified the presence of some lncRNAs using RT-PCR and DNA sequencing, and identified some differentially expressed lncRNAs using qPCR. We also investigated the role of cis-acting lncRNAs on target genes. GO and KEGG enrichment analysis revealed that the target genes of lncRNAs were involved in the regulation of hormones secretion and some signaling pathways in the sheep pituitary gland. Our study provides comprehensive expression profiles of lncRNAs and valuable resource for understanding their function in the pituitary gland.

Heat Stress-Responsive Transcriptome Analysis in the Liver Tissue of Hu Sheep

Heat stress has a severe effect on animal health and can reduce the productivity and reproductive efficiency; it is therefore necessary to explore the molecular mechanism involved in heat stress response, which is helpful for the cultivation of an animal breed with resistance to heat stress. However, little research about heat stress-responsive molecular analysis has been reported in sheep. Therefore, in this study, RNA sequencing (RNA-Seq) was used to investigate the transcriptome profiling in the liver of Hu sheep with and without heat stress. In total, we detected 520 and 22 differentially expressed mRNAs and lncRNAs, respectively. The differentially expressed mRNAs were mainly associated with metabolic processes, the regulation of biosynthetic processes, and the regulation of glucocorticoid; additionally, they were significantly enriched in the heat stress related pathways, including the carbon metabolism, the PPAR signaling pathway, and vitamin digestion and absorption. The co-located differentially expressed lncRNA Lnc_001782 might positively influence the expression of the corresponding genes APOA4 and APOA5, exerting co-regulative effects on the liver function. Thus, we made the hypothesis that Lnc_001782, APOA4 and APOA5 might function synergistically to regulate the anti-heat stress ability in Hu sheep. This study provides a catalog of Hu sheep liver mRNAs and lncRNAs, and will contribute to a better understanding of the molecular mechanism underlying heat stress responses.

Transcriptome analysis to identify long non coding RNA (lncRNA) and characterize their functional role in back fat tissue of pig

Long non coding RNAs (lncRNA) have been previously found to be involved in important cellular activities like epigenetics, implantation, cell growth etc. in pigs. However, comprehensive analysis of lncRNA in back fat tissues at different developmental stages in pigs is still lacking. In this study we conducted transcriptome analysis in the back fat tissue of a F1 crossbred Korean Native Pig (KNP) × Yorkshire Pig to identify lncRNA. We investigated their role in 16 pigs at two different growth stages; stage 1 (10 weeks, n = 8) and stage 2 (26 weeks, n = 8). After quality assessment of sequencing reads, we got a total of 1,641,165 assembled transcripts out of eight paired end read from each stage. Among them, 6808 lncRNA transcripts were identified by filtering on the basis of multiple parameters like read length ≥ 200 nucleotides, exon numbers ≥2, FPKM ≥0.5, coding potential score < 0 etc. PFAM and RFAM were used to filter out all possible protein coding genes and housekeeping RNAs respectively. A total of 103 lncRNAs and 1057 mRNAs were found to be differentially expressed (DE) between the two stages (|log2FC| > 2, q < 0.05). We also identified 306 genes located around 100 kb upstream and 234 genes downstream around these DE lncRNA transcripts. The expression of top eleven DE lncRNAs (COL4A6, LY7S, MYH2, OXCT1, SMPDL3A, TMEM182, TTC36, RFOOOO4, RFOOO15, RFOOO45, CADM2) had been validating by qRT-PCR. Pathway and GO terms analysis showed that, positive regulation of biosynthetic process, Wnt signaling pathway, cellular protein modification process, and positive regulation of nitrogen compound were differentially enriched. Our results suggested that, KEGG pathways such as protein digestion and absorption, Arrhythmogenic right ventricular cardiomyopathy (ARVC) to be significantly enriched in both DE lncRNAs as well as DE mRNAs and involved in back fat tissues development. It also suggests that, identified lncRNAs are involved in regulation of important adipose tissues development pathways.

Identification of circular RNAs in the immature and mature rat anterior pituitary

Circular RNAs (circRNAs) are a new class of RNA that have a stable structure characterized by covalently closed circular molecules and are involved in invasive pituitary adenomas and recurrent clinically nonfunctioning pituitary adenomas. However, information on circRNAs in the normal pituitary, especially in rats, is limited. In this study, we identified 4123 circRNAs in the immature (D15) and mature (D120) rat anterior pituitary using the Illumina platform, and 32 differentially expressed circRNAs were found. A total of 150 Gene Ontology terms were significantly enriched, and 16 KEGG pathways were found to contain differentially expressed genes. Moreover, we randomly selected eight highly expressed circRNAs and detected their relative expression levels in the mature and immature rat pituitary by qPCR. In addition, we predicted 90 interactions between 53 circRNAs and 57 miRNAs using miRanda. Notably, circ_0000964 and circ_0001303 are potential miRNA sponges that may regulate the Fshb gene. The expression profile of circRNAs in the immature and mature rat anterior pituitary may provide more information about the roles of circRNAs in the development and reproduction in mammals.

Pituitary Transcriptomic Study Reveals the Differential Regulation of lncRNAs and mRNAs Related to Prolificacy in Different FecB Genotyping Sheep

Long non-coding RNA (LncRNA) have been identified as important regulators in the hypothalamic-pituitary-ovarian axis associated with sheep prolificacy. However, their expression pattern and potential roles in the pituitary are yet unclear. To explore the potential mRNAs and lncRNAs that regulate the expression of the genes involved in sheep prolificacy, we used stranded specific RNA-seq to profile the pituitary transcriptome (lncRNA and mRNA) in high prolificacy (genotype FecB BB, litter size = 3; H) and low prolificacy sheep (genotype FecB B+; litter size = 1; L). Our results showed that 57 differentially expressed (DE) lncRNAs and 298 DE mRNAs were found in the pituitary between the two groups. The qRT-PCR results correlated well with the RNA-seq results. Moreover, functional annotation analysis showed that the target genes of the DE lncRNAs were significantly enriched in pituitary function, hormone-related pathways as well as response to stimulus and some other terms related to reproduction. Furthermore, a co-expression network of lncRNAs and target genes was constructed and reproduction related genes such as SMAD2, NMB and EFNB3 were included. Lastly, the interaction of candidate lncRNA MSTRG.259847.2 and its target gene SMAD2 were validated in vitro of sheep pituitary cells. These differential mRNA and lncRNA expression profiles provide a valuable resource for understanding the molecular mechanisms underlying Hu sheep prolificacy.

Identification and characterization of long non-coding RNAs in porcine granulosa cells exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin

Background

Long non-coding RNAs (lncRNAs) may regulate gene expression in numerous biological processes including cellular response to xenobiotics. The exposure of living organisms to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a persistent environmental contaminant, results in reproductive defects in many species including pigs. The aims of the study were to identify and characterize lncRNAs in porcine granulosa cells as well as to examine the effects of TCDD on the lncRNA expression profile in the cells.

Results

One thousand six hundred sixty-six lncRNAs were identified and characterized in porcine granulosa cells. The identified lncRNAs were found to be shorter than mRNAs. In addition, the number of exons was lower in lncRNAs than in mRNAs and their exons were longer. TCDD affected the expression of 22 lncRNAs (differentially expressed lncRNAs [DELs]; log₂ fold change  ≥ 1, P-adjusted < 0.05) in the examined cells. Potential functions of DELs were indirectly predicted via searching their target cis- and trans-regulated protein-coding genes. The co-expression analysis revealed that DELs may influence the expression of numerous genes, including those involved in cellular response to xenobiotics, dioxin metabolism, endoplasmic reticulum stress and cell proliferation. Aryl hydrocarbon receptor (AhR) and cytochrome P450 1A1 (CYP1A1) were found among the trans-regulated genes.

Conclusions

These findings indicate that the identified lncRNAs may constitute a part of the regulatory mechanism of TCDD action in granulosa cells. To our knowledge, this is the first study describing lncRNAs in porcine granulosa cells as well as TCDD effects on the lncRNA expression profile. These results may trigger new research directions leading to better understanding of molecular processes induced by xenobiotics in the ovary.