Genome-Wide Analysis of H3K27me3 in Porcine Embryonic Muscle Development

The trimethylation of histone H3 lysine 27 (H3K27me3) is one of the most important chromatin modifications, which is generally presented as a repressive mark in various biological processes. However, the dynamic and global-scale distribution of H3K27me3 during porcine embryonic muscle development remains unclear. Here, our study provided a comprehensive genome-wide view of H3K27me3 and analyzed the matching transcriptome in the skeletal muscles on days 33, 65, and 90 post-coitus from Duroc fetuses. Transcriptome analysis identified 4,124 differentially expressed genes (DEGs) and revealed the key transcriptional properties in three stages. We found that the global H3K27me3 levels continually increased during embryonic development, and the H3K27me3 level was negatively correlated with gene expression. The loss of H3K27me3 in the promoter was associated with the transcriptional activation of 856 DEGs in various processes, including skeletal muscle development, calcium signaling, and multiple metabolic pathways. We also identified for the first time that H3K27me3 could enrich in the promoter of genes, such as DES, MYL1, TNNC1, and KLF5, to negatively regulate gene expression in porcine satellite cells (PSCs). The loss of H3K27me3 could promote muscle cell differentiation. Taken together, this study provided the first genome-wide landscape of H3K27me3 in porcine embryonic muscle development. It revealed the complex and broad function of H3K27me3 in the regulation of embryonic muscle development from skeletal muscle morphogenesis to myofiber maturation.

Analysis of long intergenic non-coding RNAs transcriptomic profiling in skeletal muscle growth during porcine embryonic development

Skeletal muscle growth plays a critical role during porcine muscle development stages. Genome-wide transcriptome analysis reveals that long intergenic non-coding RNAs (lincRNAs) are implicated as crucial regulator involving in epigenetic regulation. However, comprehensive analysis of lincRNAs in embryonic muscle development stages remain still elusive. Here, we investigated the transcriptome profiles of Duroc embryonic muscle tissues from days 33, 65, and 90 of gestation using RNA-seq, and 228 putative lincRNAs were identified. Moreover, these lincRNAs exhibit the characteristics of shorter transcripts length, longer exons, less exon numbers and lower expression level compared with protein-coding transcripts. Expression profile analysis showed that a total of 120 lincRNAs and 2638 mRNAs were differentially expressed. In addition, we also performed quantitative trait locus (QTL) mapping analysis for differentially expressed lincRNAs (DE lincRNAs), 113 of 120 DE lincRNAs were localized on 2200 QTLs, we observed many QTLs involved in growth and meat quality traits. Furthermore, we predicted potential target genes of DE lincRNAs in cis or trans regulation. Gene ontology and pathway analysis reveals that potential targets of DE lincRNAs mostly were enriched in the processes and pathways related to tissue development, MAPK signaling pathway, Wnt signaling pathway, TGF-beta signaling pathway and insulin signaling pathway, which involved in skeletal muscle physiological functions. Based on cluster analysis, co-expression network analysis of DE lincRNAs and their potential target genes indicated that DE lincRNAs highly regulated protein-coding genes associated with skeletal muscle development. In this study, many of the DE lincRNAs may play essential roles in pig muscle growth and muscle mass. Our study provides crucial information for further exploring the molecular mechanisms of lincRNAs during skeletal muscle development.

Comparative Analysis of Skeletal Muscle DNA Methylation and Transcriptome of the Chicken Embryo at Different Developmental Stages

DNA methylation is a key epigenetic mechanism involved in embryonic muscle development and plays an important role in early muscle development. In this study, we sought to investigate the effects of genome-wide DNA methylation by combining the expression profiles of the chicken embryonic muscle. Genome-wide DNA methylation maps and transcriptomes of muscle tissues collected from different embryonic development points (E7, E11, E17, and D1) were used for whole-genome bisulfite sequencing (WGBS) and RNA sequencing, respectively. We found that the differentially methylated genes (DMGs) were significantly associated with muscle organ development, regulation of skeletal muscle satellite cell proliferation, and actin filament depolymerization. Furthermore, genes TBX1, MEF2D, SPEG, CFL2, and TWF2 were strongly correlated with the methylation-caused expression switch. Therefore, we chose the CFL2 gene to explore its function in skeletal muscle satellite cells, and the in vitro experiments showed that CFL2 acts as a negative regulator of chicken skeletal muscle satellite cell proliferation and can induce cell apoptosis. These results provide valuable data for future genome and epigenome studies of chicken skeletal muscle and may help reveal the molecular mechanisms of potential economic traits.

Transcriptome analysis of embryonic muscle development in Chengkou Mountain Chicken

Background Muscle is the predominant portion of any meat product, and growth performance and product quality are the core of modern breeding. The embryonic period is highly critical for muscle development, the number, shape and structure of muscle fibers are determined at the embryonic stage. Herein, we performed transcriptome analysis to reveal the law of muscle development in the embryonic stage of Chengkou Mountain Chicken at embryonic days (E) 12, 16, 19, 21. Results Diameter and area of muscle fibers exhibited significant difference at different embryonic times(P < 0.01). A total of 16,330 mRNAs transcripts were detected, including 109 novel mRNAs transcripts. By comparing different embryonic muscle development time points, 2,262 in E12vsE16, 5,058 in E12vsE19, 6139 in E12vsE21, 1,282 in E16vsE19, 2,920 in E16vsE21, and 646 in E19vsE21differentially expressed mRNAs were identified. It is worth noting that 7,572 mRNAs were differentially expressed. The time-series expression profile of differentially expressed genes (DEGs) showed that the rising and falling expression trends were significantly enriched. The significant enrichment trends included 3,150 DEGs. GO enrichment analysis provided three significantly enriched categories of significantly enriched differential genes, including 65 cellular components, 88 molecular functions, and 453 biological processes. Through KEGG analysis, we explored the biological metabolic pathways involved in differentially expressed genes. A total of 177 KEGG pathways were enriched, including 19 significant pathways, such as extracellular matrix-receptor interactions. Similarly, numerous pathways related to muscle development were found, including the Wnt signaling pathway (P < 0.05), MAPK signalingpathway, TGF-beta signaling pathway, PI3K-Akt signaling pathway and mTOR signaling pathway. Among the differentially expressed genes, we selected those involved in developing 4-time points; notably, up-regulated genes included MYH1F, SLC25A12, and HADHB, whereas the down-regulated genes included STMN1, VASH2, and TUBAL3. Conclusions Our study explored the embryonic muscle development of the Chengkou Mountain Chicken. A large number of DEGs related to muscle development have been identified ,and validation of key genes for embryonic development and preliminary explanation of their role in muscle development. Overall, this study broadened our current understanding of the phenotypic mechanism for myofiber formation and provides valuable information for improving chicken quality.

The landscape of chromatin accessibility in skeletal muscle during embryonic development in pigs

Background The development of skeletal muscle in pigs during the embryonic stage is precisely regulated by transcriptional mechanisms, which depend on chromatin accessibility. However, how chromatin accessibility plays a regulatory role during embryonic skeletal muscle development in pigs has not been reported. To gain insight into the landscape of chromatin accessibility and the associated genome-wide transcriptome during embryonic muscle development, we performed ATAC-seq and RNA-seq analyses of skeletal muscle from pig embryos at 45, 70 and 100 days post coitus (dpc). Results In total, 21,638, 35,447 and 60,181 unique regions (or peaks) were found across the embryos at 45 dpc (LW45), 70 dpc (LW70) and 100 dpc (LW100), respectively. More than 91% of the peaks were annotated within − 1 kb to 100 bp of transcription start sites (TSSs). First, widespread increases in specific accessible chromatin regions (ACRs) from embryos at 45 to 100 dpc suggested that the regulatory mechanisms became increasingly complicated during embryonic development. Second, the findings from integrated ATAC-seq and RNA-seq analyses showed that not only the numbers but also the intensities of ACRs could control the expression of associated genes. Moreover, the motif screening of stage-specific ACRs revealed some transcription factors that regulate muscle development-related genes, such as MyoG, Mef2c, and Mef2d. Several potential transcriptional repressors, including E2F6, OTX2 and CTCF, were identified among the genes that exhibited different regulation trends between the ATAC-seq and RNA-seq data. Conclusions This work indicates that chromatin accessibility plays an important regulatory role in the embryonic muscle development of pigs and regulates the temporal and spatial expression patterns of key genes in muscle development by influencing the binding of transcription factors. Our results contribute to a better understanding of the regulatory dynamics of genes involved in pig embryonic skeletal muscle development.

Analysis of Long Intergenic Non-Coding RNAs Transcriptomic Profiling in Skeletal Muscle Growth During Porcine Embryonic Development

Skeletal muscle growth plays a critical role during porcine muscle development stages. Genome-wide transcriptome analysis reveals that thousands of long intergenic non-coding RNAs (lincRNAs) have been identified in various species and implicated as crucial regulator involving in epigenetic regulation. However, comprehensive analysis of lincRNAs in embryonic muscle development stages remain still elusive. Here, we investigated the transcriptome profiles of duroc embryonic muscle tissues from days 33, 65, and 90 of gestation using RNA-seq, there were 228 putative lincRNAs identified. Moreover, these lincRNAs exhibit the characteristics of shorter transcripts length, longer exons, less exon numbers and lower expression level compared with protein-coding transcripts. Differential expression analysis showed that a total of 91 lincRNAs and 2638 mRNAs were differentially expressed. In addition, we also performed quantitative trait locus (QTL) mapping analysis for DE lincRNAs, 113 of 120 DE lincRNAs were localized on 2200 QTLs, we observed many QTLs involved in growth and meat quality traits. Furthermore, we predicted potential target genes of DE lincRNAs in cis or trans regulation. Gene ontology and pathway analysis reveals that potential targets of DE lincRNAs mostly were enriched in the processes and pathways related to tissue development, MAPK signaling pathway, Wnt signaling pathway, TGF-beta signaling pathway and insulin signaling pathway, which involved in skeletal muscle physiological functions. Based on cluster analysis, a co-expression network analysis of DE lincRNAs and their potential target genes indicated that DE lincRNAs highly regulated protein-coding genes associated with skeletal muscle development. In this study, many of the DE lincRNAs identified may play essential roles in pig muscle growth and muscle mass. Our study provides crucial information for exploring further the molecular mechanisms of lincRNAs during skeletal muscle development.

The landscape of chromatin accessibility in skeletal muscle during embryonic development in pigs

Background: The development of skeletal muscle during the embryonic stage in pigs is precisely regulated by transcriptional mechanisms, which depends on chromatin accessibility. However, the landscape of chromatin accessibility in skeletal muscle during embryonic development in pigs has not been reported. To gain insight into the landscape of chromatin accessibility and the associated genome-wide transcriptome during embryonic muscle development, we performed ATAC-seq and RNA-seq on skeletal muscle of pig embryos at 45, 70 and 100 days post coitus (dpc).Results: In total, 21638, 35447 and 60181 unique regions (or peaks) were found across 45 dpc (LW45), 70 dpc (LW70) and 100 dpc (LW100) embryos, respectively. More than 91% of peaks were annotated within -1 kb to 100 bp of transcription start sites (TSSs). First, widespread increases in specific accessible chromatin regions (ACRs) from 45 to 100 dpc embryos suggested that the regulatory mechanisms became increasingly complicated during embryonic development. Second, the findings of integrated ATAC-seq and RNA-seq analyses showed that not only the numbers but also the peak intensities of ACRs could control the expression of associated genes. Finally, motif screening of stage-specific ACRs revealed some transcription factors that regulated muscle development-related genes, such as MyoD, Mef2c, and Mef2d. Motif screening of DPI of common peaks detected that a potential transcriptional repressor, namely CTCF, was identified among those genes that exhibited different change trends between the ATAC-seq and RNA-seq data.Conclusions: This work indicates that chromatin accessibility plays an important regulatory role in the embryonic muscle development of pigs and regulates the temporal and spatial expression patterns of key genes in muscle development by influencing the binding of transcription factors. Our results contribute to a better understanding of the regulatory dynamics of genes involved in pig embryonic skeletal muscle development.

Transcriptome Analysis of Embryonic Muscle Development in Chengkou Mountain Chicken

Background: Muscle is the predominant portion of any meat product, and growth performance and product quality are the core of modern breeding. The embryonic period is highly critical for muscle development, the number, shape and structure of muscle fibers are determined at the embryonic stage. Herein, we performed transcriptome analysis to reveal the law of muscle development in the embryonic stage of Chengkou Mountain Chicken at embryonic days (E) 12, 16, 19, 21. Results: Diameter and area of muscle fibers exhibited significant difference at different embryonic times(P<0.01). A total of 16,330 mRNAs transcripts were detected, including 109 novel mRNAs transcripts. By comparing different embryonic muscle development time points, 2,251 (E12vsE16), 4,324 (E12vsE19), and 5,224 (E12vsE21), 1,274 (E16vsE19), 2,735 (E16vsE21) and 857 (E19vsE21) differentially expressed mRNAs were identified. It is worth noting that 6,726 mRNAs were differentially expressed. The time-series expression profile of differentially expressed genes (DEGs) showed that the rising and falling expression trends were significantly enriched. The downward trend was the most important and was enriched in 3,963 DEGs. GO enrichment analysis provided three significantly enriched categories of the down-trending genes, including 91 cellular components, 53 molecular functions, and 248 biological processes. Through KEGG analysis, we explored the pathway of downtrend genes. A total of 183 KEGG pathways were enriched, including 17 significant pathways, such as extracellular matrix-receptor interactions. Similarly, numerous pathways related to muscle development were found, including the Wnt signaling pathway (P<0.05), MAPK signalingpathway, TGF-beta signaling pathway, and mTOR signaling pathway. Among the differentially expressed genes, we selected those involved in developing 4-time points; notably, up-regulated genes included MYH1F, SLC25A12, and HADHB, whereas the down-regulated genes included STMN1, VASH2, and TUBAL3. Conclusion: Our study explored the embryonic muscle development of the Chengkou Mountain Chicken. A large number of DEGs related to muscle development have been identified ,and validation of key genes for embryonic development and preliminary explanation of their role in muscle development. Overall, this study broadened our current understanding of the phenotypic mechanism for myofiber formation and provides valuable information for improving chicken quality.

The Landscape of Chromatin Accessibility in Skeletal Muscle During Embryonic Development in Pigs

Background: The development of skeletal muscle during the embryonic stage in pigs is precisely regulated by transcriptional regulation, which depends on chromatin accessibility. However, how chromatin accessibility plays a regulatory role during embryonic skeletal muscle development in pigs has not been reported. To gain insight into the landscape of chromatin accessibility and the associated genome-wide transcriptome during embryonic muscle development, we performed ATAC-seq and RNA-seq on skeletal muscle of pig embryos at 45, 70 and 100 days post coitus (dpc). Results: In total, 21638, 35447 and 60181 unique regions (or peaks) were found across 45 dpc (LW45), 70 dpc (LW70) and 100 dpc (LW100) embryos, respectively. More than 91% of peaks were annotated within -1 kb to 100 bp of transcription start sites (TSSs). First, widespread increases in specific accessible chromatin regions (ACRs) from 45 to 100 dpc embryos suggested that the regulatory mechanisms became increasingly complicated during embryonic development. Second, the findings of integrated ATAC-seq and RNA-seq analyses showed that not only the numbers but also the peak intensities of ACRs could control the expression of associated genes. Finally, motif screening of stage-specific ACRs revealed some transcription factors that regulated muscle development-related genes, such as MyoD, Mef2c, Mef2d and Pax7. Several potential transcriptional repressors, including E2F6, GRHL2, OTX2 and CTCF, were identified among those genes that exhibited different change trends between the ATAC-seq and RNA-seq data. Conclusions: This work indicates that chromatin accessibility plays an important regulatory role in the embryonic muscle development of pigs and regulates the temporal and spatial expression patterns of key genes in muscle development by influencing the binding of transcription factors. Our results contribute to a better understanding of the regulatory dynamics of genes involved in pig embryonic skeletal muscle development.