Integrative analysis of circRNA, miRNA, and mRNA profiles to reveal ceRNA regulation in chicken muscle development from the embryonic to post-hatching periods

Novel circular RNA Sestrin1 promotes chicken myoblast proliferation and differentiation via circSesn1/miR-16-5p/SESN1 pathway

1. The development of chicken skeletal muscle is directly relevant to poultry husbandry production. Numerous studies have suggested that circular RNA play pivotal roles in muscle development. However, the functions and mechanisms of most circRNA in chicken myogenesis remain largely unknown.2. This study identified a novel circSESN1 based on existing sequencing data and examined its authenticity and subcellular localisation by enzyme digestion and RNA fluorescence in situ hybridisation. Additionally, there was a positive correlation between the expression levels of circSESN1 and the developmental stage of chicken muscle.3. Mechanistically, knockdown or overexpression of circSESN1 was performed in primary myoblasts to validate its function. The interactions between circSESN1, miR-16-5p, and the target gene sestrin 1 (SESN1) were investigated using bioinformatics analysis and a dual fluorescein reporter system. Real-time qPCR, a cell proliferation assay, and immunofluorescence staining techniques were used to investigate the promotion effect of circSESN1 on myoblast proliferation and differentiation by miR-16-5p/SESN1 pathway.4. The results demonstrated that the newly identified chicken circSESN1 directly sponges gga-miR-16-5p to regulate SESN1 gene expression, promoting myoblast proliferation and differentiation.

Genome-wide characteristics and potential functions of circular RNAs from the embryo muscle development in Chengkou mountain chicken

The Chengkou mountain chicken, a native Chinese poultry breed, holds significant importance in the country's poultry sector due to its delectable meat and robust stress tolerance. Muscle growth and development are pivotal characteristics in poultry breeding, with muscle fiber development during the embryonic period crucial for determining inherent muscle growth potential. Extensive evidence indicates that non-coding RNAs (ncRNAs) play a regulatory role in muscle growth and development. Among ncRNAs, circular RNAs (circRNAs), characterized by a closed-loop structure, have been shown to modulate biological processes through the regulation of microRNAs (miRNAs). This study seeks to identify and characterize the spatiotemporal-specific expression of circRNAs during embryonic muscle development in Chengkou mountain chicken, and to construct the potential regulatory network of circRNAs-miRNA-mRNAs. The muscle fibers of HE-stained sections became more distinct, and their boundaries were more defined over time. Subsequent RNA sequencing of 12 samples from four periods generated 9,904 novel circRNAs, including 917 differentially expressed circRNAs. The weighted gene co-expression network analysis (WGCNA)-identified circRNA source genes significantly enriched pathways related to cell fraction, cell growth, and muscle fiber growth regulation. Furthermore, a competitive endogenous RNA (ceRNA) network constructed using combined data of present and previous differentially expressed circRNAs, miRNA, and mRNA revealed that several circRNA transcripts regulate MYH1D, MYH1B, CAPZA1, and PERM1 proteins. These findings provide insight into the potential pathways and mechanisms through which circRNAs regulate embryonic muscle development in poultry, a theoretical support for trait improvement in domestic chickens.

Whole genome discovery of regulatory genes responsible for the response of chicken to heat stress

Long noncoding RNAs (lncRNAs) are functional bridges connecting the genome with phenotypes by interacting with DNA, mRNA, and proteins. Using publically available acute heat stress (AHS)-related RNA-seq data, we discovered novel lncRNAs and tested their association with AHS along with ~ 8800 known lncRNAs and ~ 28,000 mRNA transcripts. Our pipeline discovered a total of 145 potentially novel-lncRNAs. One of them (Fishcomb_p-value = 0.06) along with another novel transcript (annotated as protein-coding; Fishcomb_p-value = 0.03) were identified as significantly associated with AHS. We found five known-lncRNAs and 134 mRNAs transcripts that were significantly associated with AHS. Four novel lncRNAs interact cis-regulated with 12 mRNA transcripts and are targeted by 11 miRNAs. Also six meta-lncRNAs associate with 134 meta-mRNAs through trans-acting co-expression, each targeted by 15 and 216 miRNAs, respectively. Three of the known-lncRNAs significantly co-expressed with almost 97 of the significant mRNAs (Pearson correlation p-value < 0.05). We report the mentioned three known-lncRNAs (ENSGALT00000099876, ENSGALT00000107573, and ENSGALT00000106323) as the most, significantly regulatory elements of AHS in chicken. It can be concluded that in order to alleviate the adverse effects of AHS on chicken, the manipulation of the three regulatory lncRNAs could lead to a more desirable result than the manipulation of the most significant mRNAs.

Transcriptome Data Revealed the circRNA-miRNA-mRNA Regulatory Network during the Proliferation and Differentiation of Myoblasts in Shitou Goose

CircRNA, a recently characterized non-coding RNA (ncRNA) variant, functions as a molecular sponge, exerting regulatory control by binding to microRNA (miRNA) and modulating the expression of downstream proteins, either promoting or inhibiting their expression. Among poultry species, geese hold significant importance, prized by consumers for their delectable taste and rich nutritional content. Despite the prominence of geese, research on the growth and development of goose muscle, particularly the regulatory role of circRNAs in goose muscle formation, remains insufficiently explored. In this study, we constructed comprehensive expression profiles of circRNAs and messenger RNAs (mRNAs) within the myoblasts and myotubes of Shitou geese. We identified a total of 96 differentially expressed circRNAs (DEcircRNAs) and 880 differentially expressed mRNAs (DEmRNAs). Notably, the parental genes of DEcircRNAs and DEmRNAs exhibited enrichment in the Wnt signaling pathway, highlighting its potential impact on the proliferation and differentiation of goose myoblasts. Employing RNAhybrid and miRDB, we identified circRNA-miRNA pairs and mRNA-miRNA pairs that may play a role in regulating myogenic differentiation or muscle growth. Subsequently, utilizing Cytoscape, we constructed a circRNA-miRNA-mRNA interaction network aimed at unraveling the intricate regulatory mechanisms involved in goose muscle growth and development, which comprises 93 circRNAs, 351 miRNAs, and 305 mRNAs. Moreover, the identification of 10 hub genes (ACTB, ACTN1, BDNF, PDGFRA, MYL1, EFNA5, MYSM1, THBS1, ITGA8, and ELN) potentially linked to myogenesis, along with the exploration of their circRNA-miRNA-hub gene regulatory axis, was also conducted. These competitive endogenous RNA (ceRNA) regulatory networks elucidate the molecular regulatory mechanisms associated with muscle growth in Shitou geese, providing deeper insights into the reciprocal regulation of circRNA, miRNA, and mRNA in the context of goose muscle formation.

Analysis of circRNA-miRNA-mRNA regulatory network of embryonic gonadal development in Mulard duck

The aim of the study was to explore the regulatory mechanism of differences in embryonic gonadal development between intergeneric distance hybrid offspring Mulard ducks and parent ducks. The morphological differences gonadal tissues of Muscovy ducks, Pekin ducks and Mulard ducks at 12.5-day embryonic age were observed by sectioning and hematoxylin-eosin (HE) staining. Then followed by transcriptome sequencing to screen for gonadal development-related differentially expressed circRNAs and mRNAs to construct a competitive endogenous RNA (ceRNA) regulatory network. Finally, qRT-PCR and luciferase reporter system were used to verify the sequencing data and targeting relationship of ceRNA pairs. The results showed that the seminiferous tubule lumen of Mulard ducks was not obvious, while there were obvious seminiferous tubules and tubular structures in testis of Pekin ducks and Muscovy ducks, with number and shape indicating maturity. There were 18 upregulated circRNAs and 16 downregulated circRNAs in Mulard ducks and Pekin ducks, respectively, and 39 upregulated circRNAs and 1 downregulated circRNA in Mulard ducks and Muscovy ducks, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis found that genes involves in dorso-ventral axis formation, for example, neurogenic locus notch homolog protein 1 (NOTCH1), were significantly enriched (P < 0.05). The novel_circ_0002265-gga-miR-122-5p-PAFAH1B2 regulatory network was constructed. The qRT-PCR results showed that the sequencing results were reliable. The dual-luciferase reporter assay showed that gga-miR-122-5p exists binding site of circ_0002265 and PAFAH1B2, indicating circ_0002265-gga-miR-122-5p-PAFAH1B2 targeting relationship. In summary, the embryonic gonadal development of intergeneric hybrid Mulard ducks may be regulated by differentially expressed circRNAs and genes, such as novel_circ_0000519, novel_circ_0003537, NOTCH1, FGFR2, PAFAH1B1, and PAFAH1B2, among which circ_0002265-gga-miR-122-5p-PAFAH1B2 may participate in the targeted regulation of gonadal development in Mulard ducks. The findings of this study are helpful for analyzing the mechanism of embryonic gonadal development differences in avians.

Effect of Echinacea purpurea (L.) Moench and its extracts on the immunization outcome of avian influenza vaccine in broilers

ETHNOPHARMACOLOGICAL RELEVANCE

Echinacea purpurea (L.) Moench (EP) is a perennial herbaceous flowering plant with immunomodulatory effects. However, the immunomodulatory effects of EP on broilers after vaccination are still unclear.

AIM OF THE STUDY

The aim is to study the effect of EP and Echinacea purpurea (L.) Moench extracts(EE) on avian influenza virus (AIV) immunity, and further explore the potential mechanism of immune regulation.

MATERIALS AND METHODS

Broilers were fed with feed additives containing 2% EP or 0.5% EE, and vaccinated against avian influenza. The samples were collected on the 7th, 21st, and 35th day after vaccination, and the feed conversion ratio (FCR) was calculated. Blood antibody titer, jejunal sIgA content, tight junction protein, gene and protein expression of TLR4-MAPK signaling pathway were also detected.

RESULTS

The results showed that vaccination could cause immune stress, weight loss, increase sIgA content, and up-regulate the expression of tight junction proteins, including zonula occludens-1 (ZO-1), Occludin, and Claudin-1, as well as the genes of Toll-like receptor 4 (TLR4), myeloid differentiation primary response 88 (MyD88), receptor-associated factor 6 (TRAF6), activator protein 1 (AP-1) protein gene expression on TLR4-mitogen-activated protein kinase (MAPK) signaling pathway, and the protein expression of MyD88, extracellular regulated protein kinases (ERK), and c-Jun N-terminal kinase (JNK). EP and EE could increase the body weight of broilers, further improve antibody titers, decrease FCR, increase sIgA levels, up-regulate the expression of tight junction proteins, including ZO-1, Occludin, and Claudin-1, as well as the genes of TLR4, MyD88, TRAF6, and AP-1 and the protein expression of MyD88, ERK, and JNK in the TLR4-MAPK signaling pathway.

CONCLUSION

In conclusion, EP and EE can increase the broiler's production performance and improve vaccine immune effect through the TLR4-MAPK signaling pathway.

Functional analysis of circSTX8 in chicken macrophages under lipopolysaccharide stimulation

Circular RNAs (circRNAs) have a regulatory role in gene expression, development, differentiation, and immune response. In a previous study, circular RNA STX8 (circSTX8) exhibited low expression in chicken lungs during lipopolysaccharide (LPS) stimulation. PCR amplification and Sanger sequencing showed that circSTX8 was created by back-splicing of exons 5 to 6 of STX8. RNase R exonuclease treatment indicated that circSTX8 was a stable circular RNA. RT-qPCR showed that circSTX8 was highly expressed in cecum, spleen, harderian gland, stomach, thymus, liver, small intestine, and lung instead of that in muscle, cerebrum, and cerebellum (n = 8). Chicken macrophages were then divided into four groups: control, overexpression of circSTX8 group, LPS group, and overexpression of circSTX8 + LPS group. CCK8 and RT-qPCR showed that circSTX8 can exacerbate the cellular injury induced by LPS, resulting in a reduction of cell viability and an increase of the pro-inflammatory cytokines expression. In addition, four miRNAs were identified to interact with circSTX8, potentially targeting 914 genes, which were significantly enriched in the pathways of Tight junction, mTOR signaling pathway, MAPK signaling pathway, TGF-beta signaling pathway, Notch signaling pathway, ErbB signaling pathway, and Cell adhesion molecules. These findings showed that circSTX8 was able to regulate the LPS induced cellular immune and inflammatory response.

Evolutionary conserved circular MEF2A RNAs regulate myogenic differentiation and skeletal muscle development

Circular RNAs (circRNAs) have been recognized as critical regulators of skeletal muscle development. Myocyte enhancer factor 2A (MEF2A) is an evolutionarily conserved transcriptional factor that regulates myogenesis. However, it remains unclear whether MEF2A produces functional circRNAs. In this study, we identified two evolutionarily conserved circular MEF2A RNAs (circMEF2As), namely circMEF2A1 and circMEF2A2, in chicken and mouse muscle stem cells. Our findings revealed that circMEF2A1 promotes myogenesis by regulating the miR-30a-3p/PPP3CA/NFATC1 axis, whereas circMEF2A2 facilitates myogenic differentiation by targeting the miR-148a-5p/SLIT3/ROBO2/β-catenin signaling pathway. Furthermore, in vivo experiments demonstrated that circMEF2As both promote skeletal muscle growth. We also discovered that the linear MEF2A mRNA-derived MEF2A protein binds to its own promoter region, accelerating the transcription of MEF2A and upregulating the expression of both linear MEF2A and circMEF2As, forming a MEF2A autoregulated positive feedback loop. Moreover, circMEF2As positively regulate the expression of linear MEF2A by adsorbing miR-30a-3p and miR-148a-5p, which directly contribute to the MEF2A autoregulated feedback loop. Importantly, we found that mouse circMEF2As are essential for the myogenic differentiation of C2C12 cells. Collectively, our results demonstrated the evolution, function, and underlying mechanisms of circMEF2As in animal myogenesis, which may provide novel insight for both the farm animal meat industry and human medicine.

RNA sequencing reveals CircRNA expression profiles in chicken embryo fibroblasts infected with velogenic Newcastle disease virus

Introduction

Newcastle disease virus (NDV) is an important avian pathogen prevalent worldwide; it has an extensive host range and seriously harms the poultry industry. Velogenic NDV strains exhibit high pathogenicity and mortality in chickens. Circular RNAs (circRNAs) are among the most abundant and conserved eukaryotic transcripts. They are part of the innate immunity and antiviral response. However, the relationship between circRNAs and NDV infection is unclear.

Methods

In this study, we used circRNA transcriptome sequencing to analyze the differences in circRNA expression profiles post velogenic NDV infection in chicken embryo fibroblasts (CEFs). Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were used to reveal significant enrichment of differentially expressed (DE) circRNAs. The circRNA- miRNA-mRNA interaction networks were further predicted. Moreover, circ-EZH2 was selected to determine its effect on NDV infection in CEFs.

Results

NDV infection altered circRNA expression profiles in CEFs, and 86 significantly DE circRNAs were identified. GO and KEGG enrichment analyses revealed significant enrichment of DE circRNAs for metabolism-related pathways, such as lysine degradation, glutaminergic synapse, and alanine, aspartic-acid, and glutamic-acid metabolism. The circRNA- miRNA-mRNA interaction networks further demonstrated that CEFs might combat NDV infection by regulating metabolism through circRNA-targeted mRNAs and miRNAs. Furthermore, we verified that circ-EZH2 overexpression and knockdown inhibited and promoted NDV replication, respectively, indicating that circRNAs are involved in NDV replication.

Conclusions

These results demonstrate that CEFs exert antiviral responses by forming circRNAs, offering new insights into the mechanisms underlying NDV-host interactions.

Characteristics and Expression of circ_003628 and Its Promoted Effect on Proliferation and Differentiation of Skeletal Muscle Satellite Cells in Goats

Simple Summary

Circular RNAs (circRNAs) are new regulators of the development of skeletal muscle in mammals. Herein, circ_003628 in Longissimus dorsi muscle tissue of goats, previously found by RNA-seq, was selected to construct an expression profile in different caprine tissues, and investigate the effect on proliferation and differentiation of caprine skeletal muscle satellite cells (SMSCs), using RT-qPCR, EdU, CCK-8 and immunofluorescence assays. The results showed that circ_003628 had the highest expression level both in the longissimus dorsi muscle among nine caprine tissues collected, and on day 6 after differentiation during SMSCs differentiation periods. The interfering of circ_003628 inhibited the viability, proliferation, and differentiation of goat SMSCs.

Abstract

In our previous a study, circ_003628 was one of the most highly expressed circular RNAs (circRNAs) in the Longissimus dorsi muscle of goats found by RNA-seq, suggesting that the circRNA may be important for caprine muscle growth and development. However, there have been no reports describing the molecular mechanisms by which circ_003628 regulates the activities of goat skeletal muscle satellite cells (SMSCs). In this study, reverse transcriptase-PCR (RT-PCR) and DNA sequencing were used to validate the authenticity of circ_003628, and its characteristics, expression profile and effect on goat SMSCs were also studied using real-time quantitative-PCR (RT-qPCR), EdU, CCK-8 and immunofluorescence assays. Circ_003628 is partially originated from 13 exons, 12 introns and 3′-untranslated regions (UTR) of caprine Myosin Heavy Chain 1 (MYH1), and 25 exons and 5′ UTR of Myosin Heavy Chain 4 (MYH4), as well as intergenic sequences between the two genes. A total of 77.07% of circ_003628 were located in the nuclei of goat SMSCs, while 22.93% were expressed in the cytoplasm. The circRNAs were only expressed in triceps brachii, quadriceps femoris and longissimus dorsi muscle tissues in nine caprine tissues investigated, with the highest expression level in longissimus dorsi muscle. The expression level of circ_003628 gradually increased during differentiation periods of goat SMSCs and reached the maximum on day 6 after differentiation. The small interfering RNA of circ_003628 (named si-circ_003628) inhibited the viability and proliferation of goat SMSCs, and also decreased the expression of four cell proliferation marker genes: paired box 7 (Pax7), cyclin-dependent kinase 2 (CDK2), CDK4 and CyclinD1 in goat SMSCs. Transfection of si-circ_003628 significantly decreased the area of MyHC-labeled myotubes of goat SMSCs, as well as the expression levels of three differentiation marker genes: myosin heavy chain (MyHC), myogenin (MyoG), and myocyte enhancer factor 2C (MEF2C). These results suggest that circ_003628 promotes the viability, proliferation, and differentiation of goat SMSCs, and they also provide an improved understanding of the roles of circ_003628 in skeletal muscle growth and development in goats.