Immunity-associated long non-coding RNA and expression in response to bacterial infection in large yellow croaker (Larimichthys crocea)

Inter-Species Dynamics of Non-Coding RNAs: Impact on Host Immunomodulation and Pathogen Survival

Non-coding RNAs (ncRNAs) are composed of nucleotides that do not encode proteins but instead serve as guides. It interacts with amino acids at precise genomic sites, influencing chromatin structure and gene expression. These ncRNAs contribute to numerous inter-species dynamics, including those within the vector-host-pathogen triad. Vector-associated ncRNAs are released into hosts to combat the host immune system and sustain arthropod viability. Conversely, hosts may utilize specific ncRNAs as part of their defences to counteract pathogen-carrying vectors. Moreover, pathogens transmitted through vectors' saliva into hosts carry ncRNAs that enhances their virulence. While recent investigations have primarily focused on vector-associated ncRNAs in animal hosts, only a few have explored the functions of pathogen-associated ncRNAs and their role in initiating infections. Our review delves into the historical prospects of ncRNAs, mechanisms by which pathogen-derived ncRNAs influence host-pathogen interactions, regulate gene expression, and evade host defences. Ultimately, it underscores the importance ncRNAs mediated regulatory network in vector-host-pathogen dynamics, offering new strategies to combat vector-borne diseases and enhance public health outcomes.

Genome-Wide Identification and Involvement in Response to Biotic and Abiotic Stresses of lncRNAs in Turbot (Scophthalmus maximus)

Long non-coding RNAs (lncRNAs) play crucial roles in a variety of biological processes, including stress response. However, the number, characteristics and stress-related expression of lncRNAs in turbot are still largely unknown. In this study, a total of 12,999 lncRNAs were identified at the genome-wide level of turbot for the first time using 24 RNA-seq datasets. Sequence characteristic analyses of transcripts showed that lncRNA transcripts were shorter in average length, lower in average GC content and in average expression level as compared to the coding genes. Expression pattern analyses of lncRNAs in 12 distinct tissues showed that lncRNAs, especially lincRNA, exhibited stronger tissue-specific expression than coding genes. Moreover, 612, 1351, 1060, 875, 420 and 1689 differentially expressed (DE) lncRNAs under Vibrio anguillarum, Enteromyxum scophthalmi, and Megalocytivirus infection and heat, oxygen, and salinity stress conditions were identified, respectively. Among them, 151 and 62 lncRNAs showed differential expression under various abiotic and biotic stresses, respectively, and 11 lncRNAs differentially expressed under both abiotic and biotic stresses were selected as comprehensive stress-responsive lncRNA candidates. Furthermore, expression pattern analysis and qPCR validation both verified the comprehensive stress-responsive functions of these 11 lncRNAs. In addition, 497 significantly co-expressed target genes (correlation coefficient (R) > 0.7 and q-value < 0.05) for these 11 comprehensive stress-responsive lncRNA candidates were identified. Finally, GO and KEGG enrichment analyses indicated that these target genes were enriched mainly in molecular function, such as cytokine activity and active transmembrane transporter activity, in biological processes, such as response to stimulus and immune response, and in pathways, such as protein families: signaling and cellular processes, transporters and metabolism. These findings not only provide valuable reference resources for further research on the molecular basis and function of lncRNAs in turbot but also help to accelerate the progress of molecularly selective breeding of stress-resistant turbot strains or varieties.

Epigenetic mechanisms of lncRNA in response to thermal stress during embryogenesis of allotetraploid Cyprinus carpio

Embryogenesis and epigenetic mechanisms of lncRNA may play an important role in the formation of temperature tolerance in allotetraploid Cyprinus carpio. To investigate the response of lncRNA to thermal stress during embryogenesis of C. carpio, transcriptome sequencing was performed on 81 embryo or larva samples from different early development stages and temperatures. We identified 45,097 lncRNAs and analyzed transcriptome variation during embryogenesis. Stage-specific and temperature-specific DE lncRNAs and DEGs were screened. GO and KEGG analysis identified numerous pathways involved in thermal stress. Temperature-specific regulation of cis-/trans-/antisense lncRNAs was analyzed. Interaction network analysis identified 6 hub lncRNAs and many hub genes, such as cdk1 and hsf1. Decreased expression of many essential genes regulated by lncRNAs may lead to the death of embryos at 33 °C. Our findings provide new insights into the regulation of lncRNA in thermal stress response during embryogenesis and contribute to the understanding of environmental adaptation of allotetraploid species.

Role of non‑coding RNAs in cartilage endplate (Review)

Cartilage endplate (CEP) degeneration is considered one of the major causes of intervertebral disc degeneration (IDD), which causes non-specific neck and lower back pain. In addition, several non-coding RNAs (ncRNAs), including long ncRNAs, microRNAs and circular RNAs have been shown to be involved in the regulation of various diseases. However, the particular role of ncRNAs in CEP remains unclear. Identifying these ncRNAs and their interactions may prove to be is useful for the understanding of CEP health and disease. These RNA molecules regulate signaling pathways and biological processes that are critical for a healthy CEP. When dysregulated, they can contribute to the development disease. Herein, studies related to ncRNAs interactions and regulatory functions in CEP are reviewed. In addition, a summary of the current knowledge regarding the deregulation of ncRNAs in IDD in relation to their actions on CEP cell functions, including cell proliferation, apoptosis and extracellular matrix synthesis/degradation is presented. The present review provides novel insight into the pathogenesis of IDD and may shed light on future therapeutic approaches.

Mining glycosylation-related prognostic lncRNAs and constructing a prognostic model for overall survival prediction in glioma: A study based on bioinformatics analysis

Dysregulation of protein glycosylation plays a crucial role in the development of glioma. Long noncoding RNA (lncRNAs), functional RNA molecules without protein-coding ability, regulate gene expression and participate in malignant glioma progression. However, it remains unclear how lncRNAs are involved in glycosylation glioma malignancy. Identification of prognostic glycosylation-related lncRNAs in gliomas is necessary. We collected RNA-seq data and clinicopathological information of glioma patients from the cancer genome atlas and Chinese glioma genome atlas. We used the "limma" package to explore glycosylation-related gene and screened related lncRNAs from abnormally glycosylated genes. Using univariate Cox analyses Regression and least absolute shrinkage and selection operator analyses, we constructed a risk signature with 7 glycosylation-related lncRNAs. Based on the median risk score (RS), patients with gliomas were divided into low- and high-risk subgroups with different overall survival rates. Univariate and multivariate Cox analyses regression analyses were performed to assess the independent prognostic ability of the RS. Twenty glycosylation-related lncRNAs were identified by univariate Cox regression analyses. Two glioma subgroups were identified using consistent protein clustering, with the prognosis of the former being better than that of the latter. Least absolute shrinkage and selection operator analysis identified 7 survival RSs for glycosylation-related lncRNAs, which were identified as independent prognostic markers and predictors of glioma clinicopathological features. Glycosylation-related lncRNAs play an important role in the malignant development of gliomas and may help guide treatment options.

Host-microbiota interactions and responses of Metapenaeus ensis infected with decapod iridescent virus 1

Introduction

Decapod iridescent virus 1 (DIV1) has caused severe economic losses in shrimp aquaculture. So far, Researchs on DIV1-infected shrimp have mainly focused on the hemocytes immune response, while studies on the host-intestine microbiota interactions during DIV1 infection have been scarce.

Methods

This study determined the lethal concentration 50 (LC₅₀) of DIV1 to Metapenaeus ensis, preliminarily determining that M. ensis could serve as a susceptible object for DIV1. The interactions and responses between the immune and intestine microbiota of shrimp under DIV1 infection were also investigated.

Results and Discussion

DIV1 infection decreases intestine bacterial diversity and alters the composition of intestine microbiota. Specifically, DIV1 infection decreases the abundance of potentially beneficial bacteria (Bacteroidetes, Firmicutes, and Actinobacteria), and significantly increases the abundance of pathogenic bacteria such as Vibrio and Photobacterium, thereby increasing the risk of secondary bacterial infections. The results of PICRUSt functional prediction showed that altered intestine microbiota induces host metabolism disorders, which could be attributed to the bioenergetic and biosynthetic requirements for DIV1 replication in shrimp. The comparative transcriptomic analysis showed that some metabolic pathways related to host immunity were significantly activated following DIV1 infection, including ncRNA processing and metabolic process, Ascorbate and aldarate metabolism, and Arachidonic acid metabolism. M. ensis may against DIV1 infection by enhancing the expression of some immune-related genes, such as Wnt16, heat shock protein 90 (Hsp90) and C-type lectin 3 (Ctl3). Notably, correlation analysis of intestinal microbial variation with host immunity showed that expansion of pathogenic bacteria (Vibrio and Photobacterium) in DIV1 infection could increased the expression of NF-κB inhibitors cactus-like and Toll interacting protein (Tollip), which may limit the TLR-mediated immune response and ultimately lead to further DIV1 infection.

Significance and Impact of the Study

This study enhances our understanding of the interactions between shrimp immunity and intestinal microbiota. The ultimate goal is to develop novel immune enhancers for shrimp and formulate a safe and effective DIV1 defense strategy.

Long non‐coding RNA, a supreme post‐transcriptional immune regulator of bacterial or virus‐driven immune evolution in teleost

The global aquaculture boom, fuelled by a reduction in wild population and detection of novel viruses, has created a demanding market, hence, there is a pressing need to investigate the immune system of fish, further. As the most diverse community of vertebrates and a central contributor to the progressing global aquaculture market, teleost continues to draw vast scientific interest. Recent breakthroughs in multi‐omics technologies have provided a platform to understand the role of long non‐coding RNA (lncRNA) in the host immune system during infection. Emerging evidence shows that teleost lncRNA might have a regulatory role in immune responses, mostly through lncRNA–microRNA (miRNA) sponging. Teleost lncRNA shares a functionally active short sequence complement to target the miRNA which is conserved among the several fish species. Recent report suggests that rhabdovirus exploits a lncRNA in teleost and, to dodge the host immune mechanism and negatively regulate the immune system. This observation reveals the essentiality of lncRNA in pathogen‐driven immunity in teleost. Reports available on the function of teleost lncRNA are still in early stages and experimental verifications are a limiting factor. Unravelling the lncRNA‐mediated immune regulation in fishes could be used against the invading pathogens to strengthen the aquaculture production. This review elaborates on the experimentally identified and functionally characterized lncRNA and its regulatory role in the teleost immune response during infection and pathogen‐driven host immune evolution, which could eventually lead to achieving high standards in aquaculture productivity.

Divergent Carry-Over Effects of Hypoxia during the Early Development of Abalone

After being exposed to environmental stimuli during early developmental stages, some organisms may gain or weaken physiological regulating abilities, which would have long-lasting effects on their performance. Environmental hypoxia events can have significant effects on marine organisms, but for breeding programs and other practical applications, it is important to further explore the long-term physiological effects of early hypoxia exposure in economically significant species. In this study, the Pacific abalone Haliotis discus hannai was exposed to moderate hypoxia (∼4 mg/L) from zygote to trochophora, and the assessments of hypoxia tolerance were conducted on the grow-out stage. The results revealed that juvenile abalones exposed to hypoxia at the early development stages were more hypoxia-tolerant but with slower weight growth, a phenomenon called the trade-off between growth and survival. These phenotypic effects driven by the hypoxia exposure were explained by strong selection of genes involved in signal transduction, autophagy, apoptosis, and hormone regulation. Moreover, long non-coding RNA regulation plays an important role modulating carry-over effects by controlling DNA replication and repair, signal transduction, myocardial activity, and hormone regulation. This study revealed that the ability to create favorable phenotypic differentiation through genetic selection and/or epigenetic regulation is important for the survival and development of aquatic animals in the face of rapidly changing environmental conditions.

LncRNA-ANAPC2 and lncRNA-NEFM positively regulates the inflammatory response via the miR-451/npr2/ hdac8 axis in grass carp

In grass carp (Ctenopharyngodon idella), septicemia is a systemic inflammatory response to bacterial infection and could be leaded to lethality. MiR-451 involved in septicemia progression has been reported. However, the underlying mechanism of miR-451 in septicemia induced inflammatory response remains to be revealed. In the present study, miR-451 was highly expressed in Aeromonas hydrophila induced CIK cells, opposite to lncRNA-ANAPC2 and lncRNA-NEFM expression. Furthermore, we found that miR-451 interacted with lncRNA-ANAPC2 and lncRNA-NEFM, also targeted the 3' UTR of npr2 and hdac8. In CIK cells, the inhibition of npr2 and hdac8 were down-regulated by lncRNA-ANAPC2 and lncRNA-NEFM knockdown, while downstream proinflammatory factors were inhibited. In a word, this study indicates that lncRNA-ANAPC2 and lncRNA-NEFM regulation the LPS-induced progression of inflammatory response by modulating miR-451/npr2/hdac8 axis.

Identification and characterization of long non-coding RNAs in juvenile and adult skeletal muscle of largemouth bass (Micropterus salmoides)

Long non-coding RNAs (lncRNAs) are a class of transcriptional RNA molecules, which play critical roles in diverse biological processes. However, little is known about the overall expression pattern and roles of lncRNAs in skeletal muscle of largemouth bass (LMB). Here, we constructed two skeletal muscle RNA libraries to find lncRNAs that may involve in the regulation of skeletal muscle development between juvenile and adult LMB. A total of 16,147 lncRNAs and 4611 differentially expressed lncRNAs were identified. Among these identified lncRNAs, 10 lncRNAs were randomly selected to confirm their expression by real-time qPCR both in libraries, which were consistent with the RNA sequencing results. The target mRNAs of lncRNAs were predicted for GO enrichment analysis. Results showed that these targets associated with growth and development of muscle, such as skeletal muscle fiber development, myoblast proliferation and differentiation. Importantly, correlation analysis of lncRNA-miRNA-mRNA regulatory network revealed that several lncRNAs targeted miRNAs which are closely involved in the regulation of muscle development. It is the first time to identify a number of lncRNA that correlate with skeletal muscle development in LMB. Our results not only provide a comprehensive expression profile of muscle lncRNAs in this species, but also provide a theoretical basis for further elaborating genetic regulation mechanism of muscle growth and development, and pave the way for the future molecular assisted breeding in carnivorous fishes.

LncRNA ALDB-898 modulates intestinal epithelial cell damage caused by Clostridium perfringens type C in piglet by regulating ssc-miR-122-5p/OCLN signaling

Diarrhea of piglets caused by Clostridium perfringens type C (C. perfringens type C) infection is a global problem afflicting piglet production. Long noncoding RNA (LncRNA) and microRNA (miRNA) have emerged as critical regulators of this pathological process, but the underlying molecular mechanisms remain unclear. In this study, we first observed the expression changes of ALDBSSCG0000000898 (ALDB-898) and ssc-miR-122-5p in infected ileum tissue of piglets with C. perfringens type C, and then used C. perfringens beta2 toxin (CPB2) to induce intestinal porcine epithelial cells (IPEC-J2) to construct an injury model. Cytometry kit 8 (CCK-8), lactate dehydrogenase (LDH), real-time quantitative polymerase chain reaction (RT-qPCR), Western blot, flow cytometry and fluorescein isothiocyanate-dextran 4 (FITC-Dextran 4) flux assays were performed to study the effect of ALDB-898 and ssc-miR-122-5p in apoptosis, inflammation and intestinal barrier damage and inflammatory in IPEC-J2 cells induced by CPB2. In addition, dual-luciferase reporter gene analysis was performed to confirm the relationship between ssc-miR-122-5p and ALDB-898 or ssc-miR-122-5p and occludin (OCLN), respectively. There were lower expression levels of ALDB-898 and OCLN and higher expression levels of ssc-miR-122-5p in diarrhea piglets caused by Clostridium perfringens type C. ALDB-898 and OCLN were significantly decreased and ssc-miR-122-5p was increased in IPEC-J2 after exposure to the CPB2 in a dose- and time-dependent manner. ALDB-898 overexpression mitigated CPB2-induced cell injury by promoting viability, restraining apoptosis, cytotoxicity, and inflammatory response, as well as weakening the destruction of the intestinal barrier. Further mechanisms disclosed that ALDB-898 functioned as a competing endogenous RNA (ceRNA) via binding to ssc-miR-122-5p, and OCLN was a target of ssc-miR-122-5p. Importantly, the ssc-miR-122-5p mimic led to abolishing the protective function of ALDB-898 on CPB2-induced IPEC-J2 cell damage, and the addition of OCLN reversed the negative impact of ssc-miR-122-5p, thereby restoring the protection of ALDB-898. Our data showed that ALDB-898 could enhance the expression of OCLN through competitive binding ssc-miR-122-5p to suppress CPB2-induced damage. The ALDB-898/ssc-miR-122-5p/OCLN signaling may be a candidate therapeutic pathway for diarrhea of piglets.

Identification of mRNA-miRNA-lncRNA regulatory network associated with the immune response to Aeromonas salmonicides infection in the black rockfish (Sebastes schlegelii)

In aquaculture, Aeromonas salmonicides (A. salmonicida) is a main fish pathogen because of its nearly worldwide distribution, and broad host range. Recently, an increasing number of evidences have uncovered the roles of mRNA-miRNA-lncRNA network in fish diseases. In current study, RNA-seq was conducted in the black rockfish spleen following A. salmonicida infection at 0 h (Sp0 or control) and three different post-infection time-points (2 h: Sp2, 12 h: Sp12 and 24 h: Sp24, respectively) to comprehensively identify differentially expressed (DE) mRNAs, miRNAs and lncRNAs. Enrichment analysis and protein-protein interaction (PPI) analysis of DE mRNAs were performed. Then, expression and correlation analysis for mRNAs and their upstream miRNAs and lncRNAs were conducted. Finally, a total of 1364 mRNAs, 17 miRNAs and 1584 lncRNAs exhibited significantly differential expressions during bacterial infection in the black rockfish spleen. Functional enrichment analysis suggested that they were significantly enriched in several immune-related pathways, including Amino sugar and nucleotide sugar metabolism, Cell adhesion molecules (CAMs), Neuroactive ligand-receptor interaction, Nicotinate and nicotinamide metabolism, Pentose and glucuronate interconversions, Phagosome, Proteasome, etc. Subsequently, 1091 lncRNA-miRNA-mRNA pathways (323 in Sp2, 609 in Sp12 and 207 in Sp24) were constructed including 400 lncRNAs, 69 miRNAs, and 70 mRNAs. Meanwhile, NLRC3/novel-264/LNC_00116154 pathway demonstrated important immune modulating function in the black rockfish against A. salmonicida infection. Finally, the novel mRNA-miRNA-lncRNA sub-networks were established, among which all mRNAs and ncRNAs possessed significant predictive values for further studies for immune responses in the black rockfish.

Brain and Pituitary Transcriptome Analyses Reveal the Differential Regulation of Reproduction-Related LncRNAs and mRNAs in Cynoglossus semilaevis

Long noncoding RNAs (lncRNAs) have been identified to be involved in half-smooth tongue sole (Cynoglossus semilaevis) reproduction. However, studies of their roles in reproduction have focused mainly on the ovary, and their expression patterns and potential roles in the brain and pituitary are unclear. Thus, to explore the mRNAs and lncRNAs that are closely associated with reproduction in the brain and pituitary, we collected tongue sole brain and pituitary tissues at three stages for RNA sequencing (RNA-seq), the 5,135 and 5,630 differentially expressed (DE) mRNAs and 378 and 532 DE lncRNAs were identified in the brain and pituitary, respectively. The RNA-seq results were verified by RT-qPCR. Moreover, enrichment analyses were performed to analyze the functions of DE mRNAs and lncRNAs. Interestingly, their involvement in pathways related to metabolism, signal transduction and endocrine signaling was revealed. LncRNA-target gene interaction networks were constructed based on antisense, cis and trans regulatory mechanisms. Moreover, we constructed competing endogenous RNA (ceRNA) networks. In summary, this study provides mRNA and lncRNA expression profiles in the brain and pituitary to understand the molecular mechanisms regulating tongue sole reproduction.

Integrated analysis of lncRNA and mRNA in liver of Megalobrama amblycephala post Aeromonas hydrophila infection

Background

As non-coding RNA molecules of more than 200 bp in length, long non-coding RNAs (lncRNAs) play a variety of roles in biological processes, including regulating the immune responses to bacterial infections. In recent years, there have been many in-depth studies on mammalian lncRNAs, but the relevant studies in fish are very limited. Meanwhile, since lncRNAs are not conserved among species, it is difficult to apply the existing results directly to unstudied species.

Results

To obtain the information of lncRNAs in Megalobrama amblycephala, one of the most economically important freshwater fish in China, also to better understand the biological significance of lncRNAs in the immunity system, the fish liver at 0, 4, 12, 24, and 72 h post Aeromonas hydrophila infection (hpi) were obtained for lncRNA-sequencing (lncRNA-seq). A total of 14,849 lncRNAs were identified, and 2196 lncRNAs showed significant differences at different time points post A. hydrophila infection. Gene Ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses showed that the target genes of the differentially expressed lncRNAs were enriched in several pathways related to immune such as apoptosis, inflammation, and immune response. Time-specific modules were then identified, using weighted correlation network analysis (WGCNA), and 28 modules significantly correlated with different time point after infection were found. Furthermore, four immune-related genes and six lncRNAs in the time-specific modules were subsequently verified by RT-qPCR.

Conclusions

The above findings reveal the discovery of widespread differentially expressed lncRNAs in the M. amblycephala liver post A. hydrophila infection, suggesting that lncRNAs might participate in the regulation of host response to bacterial infection, enriching the information of lncRNAs in teleost and providing a resources basis for further studies on the immune function of lncRNAs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-021-07969-5.

Differentially expressed lncRNAs involved in immune responses of Haliotis diversicolor and H. discus hannai challenged with Vibrio parahaemolyticus

Although many studies have shown that lncRNA, a non-coding RNA with a length of more than 200 bases, is involved in various biological functions, including the immune process, stress process, and cell development process. However, the function of lncRNA in abalone, especially in immunity, has been rarely studied. H. discus hannai and H. diversicolor are two main aquaculture abalone, and their growth is easily affected by the main pathogen Vibrio parahaemolyticus. Through rigorous screening procedures for transcripts in this study, we found that lncRNAs were 34,240, 23,022 in Haliotis diversicolor and H. discus hannai injected with V. parahaemolyticus, respectively. We also identified the unique and common lncRNAs and mRNAs of two abalone species for the first time; the shared lncRNAs and mRNAs in Haliotis diversicolor and H. discus hannai were 2352 and 13,165, respectively. Then gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis of the differentially expressed target genes of common and unique lncRNAs has shown that common lncRNAs could be widely involved in the biological processes of stress and cell development in both abalone species. In contrast, unique lncRNAs are linked to the Toll-like receptor, NF-kappaB signaling pathway of H. diversicolor, and pattern recognition receptors and lectins immune-related pathways of H. discus hannai. The co-expression network shows that some immune-related genes, such as INFK1, INFK2, CASP2, CASP8, IRAK1, lectin C, were closely related to lncRNAs. Further, we identified the targeted relationship between some immune-related genes and lncRNAs by qRT-PCR, through which we showed that the expression trend between targeted genes, such as INFK1 and Lnc7057, lectin C and Lnc6943, Lnc5637, and PLCG1 and Lnc1692, were consistent. In general, our results showed that lncRNA expression was induced in the two species of abalone after being infected with V. parahaemolyticus, and lncRNA was involved in the immune response of abalone by targeting coding genes.

Integrated lncRNA and mRNA Transcriptome Analyses in the Ovary of Cynoglossus semilaevis Reveal Genes and Pathways Potentially Involved in Reproduction

Long non-coding RNAs (lncRNAs) have been reported to be involved in multiple biological processes. However, the roles of lncRNAs in the reproduction of half-smooth tongue sole (Cynoglossus semilaevis) are unclear, especially in the molecular regulatory mechanism driving ovarian development and ovulation. Thus, to explore the mRNA and lncRNA mechanisms regulating reproduction, we collected tongue sole ovaries in three stages for RNA sequencing. In stage IV vs. V, we identified 312 differentially expressed (DE) mRNAs and 58 DE lncRNAs. In stage V vs. VI, we identified 1,059 DE mRNAs and 187 DE lncRNAs. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses showed that DE mRNAs were enriched in ECM-receptor interaction, oocyte meiosis and steroid hormone biosynthesis pathways. Furthermore, we carried out gene set enrichment analysis (GSEA) to identify potential reproduction related-pathways additionally, such as fatty metabolism and retinol metabolism. Based on enrichment analysis, DE mRNAs with a potential role in reproduction were selected and classified into six categories, including signal transduction, cell growth and death, immune response, metabolism, transport and catabolism, and cell junction. The interactions of DE lncRNAs and mRNAs were predicted according to antisense, cis-, and trans-regulatory mechanisms. We constructed a competing endogenous RNA (ceRNA) network. Several lncRNAs were predicted to regulate genes related to reproduction including cyp17a1, cyp19a1, mmp14, pgr, and hsd17b1. The functional enrichment analysis of these target genes of lncRNAs revealed that they were involved in several signaling pathways, such as the TGF-beta, Wnt signaling, and MAPK signaling pathways and reproduction related-pathways such as the progesterone-mediated oocyte maturation, oocyte meiosis, and GnRH signaling pathway. RT-qPCR analysis showed that two lncRNAs (XR_522278.2 and XR_522171.2) were mainly expressed in the ovary. Dual-fluorescence in situ hybridization experiments showed that both XR_522278.2 and XR_522171.2 colocalized with their target genes cyp17a1 and cyp19a1, respectively, in the follicular cell layer. The results further demonstrated that lncRNAs might be involved in the biological processes by modulating gene expression. Taken together, this study provides lncRNA profiles in the ovary of tongue sole and further insight into the role of lncRNA involvement in regulating reproduction in tongue sole.

The emerging regulatory roles of noncoding RNAs in immune function of fish: MicroRNAs versus long noncoding RNAs

The genome could be considered as raw data expressed in proteins and various types of noncoding RNAs (ncRNAs). However, a large portion of the genome is dedicated to ncRNAs, which in turn represent a considerable amount of the transcriptome. ncRNAs are modulated on levels of type and amount whenever any physiological process occurs or as a response to external modulators. ncRNAs, typically forming complexes with other partners, are key molecules that influence diverse cellular processes. Based on the knowledge of mammalian biology, ncRNAs are known to regulate and control diverse trafficking pathways and cellular activities. Long noncoding RNAs (lncRNAs) notably have diverse and more regulatory roles than microRNAs. Expanding these studies on fish has derived the same conclusion with relevance to other species, including invertebrates, explored the potentials to harness such types of RNA to further understand the biology of such organisms, and opened gates for applying recent technologies, such as RNA interference and delivering micromolecules as microRNAs to living cells and possibly to target organs. These technologies should improve aquaculture productivity and fish health, as well as help understand fish biology.

LncRNA-WAS and lncRNA-C8807 interact with miR-142a-3p to regulate the inflammatory response in grass carp

Septicemia of grass carp is a systemic inflammatory reaction caused by bacterial infection. More and more evidences show that long non-coding RNAs (lncRNAs) can participate in the regulation of inflammatory response. In the present study, lncRNA-WAS and lncRNA-C8807 were confirmed to be involved in the inflammatory response following infection with Aeromonas hydrophila. LncRNA-WAS and lncRNA-C8807 could interact with miR-142a-3p. LncRNA-WAS and lncRNA-C8807 interact with miR-142a-3p to effect pro-inflammatory genes and NF-κB pathway. Our results provide a theoretical basis for studying the molecular mechanism underlying the regulation of inflammation by lncRNA in grass carp.

Identification and Characterization of Long Non-coding RNAs in the Intestine of Olive Flounder (Paralichthys olivaceus) During Edwardsiella tarda Infection

Long non-coding RNAs (lncRNAs) play widespread roles in fundamental biological processes, including immune responses. The olive flounder (Paralichthys olivaceus), an important economical flatfish widely cultured in Japan, Korea, and China, is threatened by infectious pathogens, including bacteria, viruses, and parasites. However, the role of lncRNAs in the immune responses of this species against pathogen infections is not well-understood. Therefore, in this study, we aimed to identify lncRNAs in the intestine of olive flounder and evaluate their differential expression profiles during Edwardsiella tarda infection, which is an important zoonotic and intestinal pathogen. A total of 4,445 putative lncRNAs were identified, including 3,975 novel lncRNAs and 470 annotated lncRNAs. These lncRNAs had shorter lengths and fewer exons compared with mRNAs. In total, 115 differentially expressed lncRNAs (DE-lncRNAs) were identified during E. tarda infection. To validate the expression pattern of lncRNAs, six DE-lncRNAs were randomly selected for quantitative real-time PCR. The co-located and co-expressed mRNAs of DE-lncRNAs were predicted, which were used to conduct the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. The target genes of DE-lncRNAs enriched numerous immune-related processes and exhibited a strong correlation with immune-related signaling pathways. To better understand the extensive regulatory functions of lncRNAs, the lncRNA–miRNA–mRNA regulatory networks were constructed, and two potential competing endogenous RNA (ceRNA) networks, LNC_001979-novel_171-Potusc2 and LNC_001979-novel_171-Podad1, were preliminarily identified from the intestine of olive flounders for the first time. In conclusion, this study provides an invaluable annotation and expression profile of lncRNAs in the intestine of olive flounder infected with E. tarda; this forms a basis for further studies on the regulatory function of lncRNAs in the intestinal mucosal immune responses of olive flounder.

Effects and mechanism of lncRNA-27785.1 that regulates TGF-β1 of Sika deer on antler cell proliferation

Transforming growth factor (TGF-β) plays an important role in the development of deer antlers. The purpose of this study was to investigate the role of long noncoding RNA in the transcriptional regulation of TGF-β1 and its relationship with the proliferation and differentiation of antler chondrocytes. High-throughput sequencing was used to screen lncRNAs related to TGF-β1. Next, the overexpression plasmid and interference sequence of target lncRNA27785.1 were constructed and transfected into chondrocytes. We found that lncRNA27785.1 inhibited the proliferation and migration of chondrocytes and delayed the transition of cells from G1 to S phase. qRT-PCR and Western blot analysis indicated that the overexpression of lncRNA27785.1 may downregulate mRNA and protein expression of TGF-BR2, Smad3, pSmad3, and Smad4. Our findings highlight lncRNA27785.1 as an inhibitor of chondrocytes proliferation and differentiation by negatively regulating the TGF-β/Smad signaling pathway; this implicates an important regulatory role for long noncoding RNA in the regeneration of antler.

Identification and Expression Analysis of Long Non-coding RNA in Large Yellow Croaker (Larimichthys crocea) in Response to Cryptocaryon irritans Infection

Large-scale transcription studies have revealed numerous lncRNAs (long non-coding RNAs). lncRNAs have been proposed to participate in the regulation of a diverse range of biological processes, including transcriptional regulation. Although lncRNAs have attracted increasing attention, the studies in large yellow croaker (Larimichthys crocea) are still rare, and they lack systematic analysis. In this study, 101 RNA-seq datasets varied in ages, sexes, and tissues were retrieved from the NCBI database to generate a comprehensive catalog of large yellow croaker transcriptome database. A set of 14,599 high-confidence lncRNAs from 13,673 loci were identified and characterized. Furthermore, RNA-seq datasets obtained from the infection of C. irritans were employed to investigate the differential expression pattern of lncRNAs and analyze potential biological functions. A total of 77 differentially expressed lncRNAs targeting to 567 protein-coding genes were identified by using expression analysis. Several immune genes, including TLR5, CD2AP, and MMP9, were highlighted. With GO enrichment and KEGG pathway analysis, the immune-related terms or pathways were enriched. This study created a comprehensive dataset of lncRNAs for large yellow croaker, which would be helpful for the researches of functional roles of lncRNAs in large yellow croaker.

Full-length transcriptome and long non-coding RNA profiling of whiteleg shrimp Penaeus vannamei hemocytes in response to Spiroplasma eriocheiris infection

Spiroplasma eriocheiris (S. eriocheiris) infection causes a significant economic loss in Penaeus vannamei (P. vannamei) culture industry. However, the response of P. vannamei hemocytes to S. eriocheiris infection has not been extensively studied. In this study, we conducted full-length transcriptome and long non-coding RNA (lncRNA) analyses of P. vannamei hemocytes by a challenge test with S. eriocheiris. Following assembly and annotation, there were 8077 high-quality unigenes. A total of 1168 differentially expressed genes (DEGs) were obtained, including 792 up-regulated and 376 down-regulated genes by differential expression analysis. Gene ontology (GO) enrichment analysis showed that the up-regulated DEGs were mainly clustered into immune system process, defense response, cell cycle and organelle organization. On the other hand, the down-regulated DEGs included that genes that were mainly clustered into metabolic processes related to organic compounds, metabolic process and cellular metabolic process. Protein-protein interaction (PPI) network analysis of DEGs indicated that the pivotal gene interactions were connected to stress response, immune system process and cell cycle. The lncRNA analysis identified multiple lncRNAs, which were highly co-expressed with the immune-related genes, such as lncRNA transcript-12631 and transcript-12631, suggesting that lncRNAs may be involved in the regulation of immune defense in shrimp hemocytes. Additionally, 20 hub unigenes and putative lncRNAs related to immune system were validated by quantitative real-time PCR (qRT-PCR), validating the reliability of RNA-Seq. This study revealed a close connection between the immune and metabolic systems of S. eriocheiris infected P. vannamei.

Screening and functional identification of lncRNAs in antler mesenchymal and cartilage tissues using high-throughput sequencing

Long non-coding RNA (lncRNA) is a transcription product of the mammalian genome that regulates the development and growth in the body. The present study aimed to analyze the expression dynamics of lncRNA in sika antler mesenchymal and cartilage tissues by high-throughput sequencing. Bioinformatics was applied to predict differentially expressed lncRNAs and target genes and screen lncRNAs and mRNAs related to osteogenic differentiation, cell proliferation, and migration. Finally, the expression of the lncRNAs and target genes were analyzed by qRT-PCR. The results showed that compared to the cartilage tissue, the transcription levels of lncRNA and mRNA, 1212 lncRNAs and 518 mRNAs, in mesenchymal tissue were altered significantly. Thus, a complex interaction network was constructed, and the lncRNA-mRNA interaction network correlation related to osteogenic differentiation, cell proliferation, and migration was analyzed. Among these, the 26 lncRNAs and potential target genes were verified by qRT-PCR, and the results of qRT-PCR were consistent with high-throughput sequencing results. These data indicated that lncRNA promotes the differentiation of deer antler mesenchymal tissue into cartilage tissue by regulating the related osteogenic factors, cell proliferation, and migration-related genes and accelerating the process of deer antler regeneration and development.