Feed efficiency (FE) is an important trait affecting costs in swine industry. Investigation on FE-related genes in different tissues is valuable for molecular breeding. Hypothalamus is a convergent and integrated centre for multiple nutrient-related signals. The present study identified 363 differentially expressed (DE) genes and 14 DE lincRNAs in the hypothalamus of high- and low-FE Yorkshire pigs. Furthermore, 983 significantly correlated DE gene-lincRNA pairs were identified through weighted correlation network analysis (WGCNA) and Pearson correlation analysis. These DE genes were primarily enriched in the neuronal signal transduction process containing the upregulated genes of VIPR1, CCR1, CCR5, LEPR, INSR, ADRA1A, CCKAR, and ADORA3 and the downregulated genes of GRM1, GRM4, GRM5, and VIPR2, which were located in the cell membrane. These signal receptors were mainly connected to downstream Jak-STAT signaling that involved the increased genes (JAK2, STAT3, and POMC) and mTOR signaling pathway, including the decreased genes (CAMKK2, AMPK, and MTOR). STAT3 and AMPK genes also played a role in two major hypothalamic neurons of POMC and NPY/AGRP. A total of eight DE lincRNAs also participated in the potential network. In conclusion, neuronal signaling transduction-involved genes and lincRNAs were related to FE variation in pig hypothalamus.

Comprehensive functional genome annotation is crucial to elucidate the molecular mechanisms of agronomic traits in livestock, yet systematic functional annotation of the sheep genome is lacking. Here, we generated 92 transcriptomic and epigenomic data sets from nine major tissues, along with whole‐genome data from 2357 individuals across 29 breeds worldwide, and 4006 phenotypic data related to tail fat weight. We constructed the first multi‐tissue epigenome atlas in terms of functional elements, chromatin states, and their functions and explored the utility of the functional elements in interpreting phenotypic variation during sheep domestication and improvement. Particularly, we identified a total of 753,723 nonredundant functional elements, with over 60% being novel. We found tissue‐specific promoters and enhancers related to sensory abilities and immune response that were highly enriched in genomic regions influenced by domestication, while longissimus dorsi tissue‐specific active enhancers and tail fat tissue‐specific active promoters were highly enriched in genomic regions influenced by breeding and improvement. Notably, a variant, Chr13:51760995A>C, located in an enhancer region, was identified as a causal variant for tail fat deposition based on multi‐layered data sets. Overall, this research provides foundational resources and a successful case for future investigations of complex traits in sheep through the integration of multi‐omics data sets.

MiRNAs reportedly participate in various biological processes, such as skeletal muscle proliferation and differentiation. However, the regulation of differentially expressed (DE) miRNAs and their function in myogenesis remain unclear. Herein, miRNA expression profiles and regulation during C2C12 differentiation were analyzed in relation to chromatin states by RNA-seq, ATAC-seq, and ChIP-seq. We identified 19 known and nine novel differentially expressed miRNAs at days 0, 1, 2, and 4. The expression of the differentially expressed miRNAs was related to the chromatin states of the 113 surrounding open chromatin regions defined by ATAC-seq peaks. Of these open chromatin regions, 44.25% were colocalized with MyoD/MyoG binding sites. The remainder of the above open chromatin regions were enriched with motifs of the myoblast-expressed AP-1 family, Ctcf, and Bach2 transcription factors (TFs). Additionally, the target genes of the above differentially expressed miRNAs were enriched primarily in muscle growth and development pathways, especially the Hippo signaling pathway. Moreover, via combining a loss-of-function assay with Q-PCR, western blotting, and immunofluorescence, we confirmed that the Hippo signaling pathway was responsible for C2C12 myoblast differentiation. Thus, our results showed that these differentially expressed miRNAs were regulated by chromatin states and affected muscle differentiation through the Hippo signaling pathway. Our findings provide new insights into the function of these differentially expressed miRNAs and the regulation of their expression during myoblast differentiation.

Understanding genetic variant functionality is essential for advancing animal genomics and precision breeding. However, the lack of comprehensive functional genomic annotations in animals limits the effectiveness of most variant function assessment methods. In this study, we gather 1030 raw epigenomic datasets from 10 farm animal species and systematically annotate 7 types of key regulatory regions, creating a comprehensive functional annotation map of animal genomic variants. Our findings demonstrate that integrating variants with regulatory annotations can identify tissues and cell types underlying economic traits, underscoring the utility of these annotations in functional variant discovery. Using our functional annotations, we rank the functional potential of genetic variants and classify over 127 million candidate variants into 5 functional confidence categories, with high-confidence variants significantly enriched in eQTLs and trait-associated SNPs. Incorporating these variants into genomic prediction models can improve estimated breeding value (EBV) accuracy, demonstrating their practical utility in breeding programs. To facilitate the use of our results, we develop the Integrated Functional Mutation (IFmut: http://www.ifmutants.com:8212) platform, enabling researchers to explore regulatory annotations and assess the functional potential of animal variants efficiently. Our study provides a robust framework for functional genomic annotations in farm animals, enhancing variant function assessment and breeding precision.

Objective: This study aims to clarify the mechanisms underlying transcriptional regulation and regulatory roles of lncRNAs in skeletal muscle cell differentiation.Methods: We analysed the expression patterns of lncRNAs via time‐course RNA‐seq. Then, we further combined the ATAC‐seq and ChIP‐seq to investigate the governing mechanisms of transcriptional regulation of differentially expressed (DE) lncRNAs. Weighted correlation network analysis and GO analysis were conducted to identify the transcription factor (TF)‐lncRNA pairs related to skeletal muscle cell differentiation.Results: We identified 385 DE lncRNAs during C2C12 differentiation, the transcription of which is determined by chromatin states around their transcriptional start sites. The TF‐lncRNA correlation network showed substantially concordant changes in DE lncRNAs between C2C12 differentiation and satellite cell rapid growth stages. Moreover, the up‐regulated lncRNAs showed a significant decrease following the differentiation capacity of satellite cells, which gradually declines during skeletal muscle development. Notably, inhibition of the lncRNA Atcayos and Trp53cor1 led to the delayed differentiation of satellite cells. Those lncRNAs were significantly up‐regulated during the rapid growth stage of satellite cells (4‐6 weeks) and down‐regulated with reduced differentiation capacity (8‐12 weeks). It confirms that these lncRNAs are positively associated with myogenic differentiation of satellite cells during skeletal muscle development.Conclusions: This study extends the understanding of mechanisms governing transcriptional regulation of lncRNAs and provides a foundation for exploring their functions in skeletal muscle cell differentiation.

The liver plays a key role in metabolism and affects pig production. However, the functional annotation of noncoding regions of the pig liver remains poorly understood. We revealed the landscape of cis-regulatory elements and their functional characterization in pig liver. We identified 102,373 cis-regulatory elements in the pig liver, including enhancers, promoters, super-enhancers, and broad H3K4me3 domains, and highlighted 26 core transcription regulatory factors in the pig liver as well. We found similarity of cis-regulatory elements among those of pigs, humans, and cattle. Despite the low proportion of functionally conserved enhancers (~30%) between pig and human liver tissue, ~78% of the pig liver enhancer orthologues sequence could play an enhancer role in other human tissues. Additionally, we observed that the ratio of consistent super-enhancer-associated genes was significantly higher than the ratio of functionally conserved super-enhancers. Approximately 54% of the core regulation factors driven by super-enhancers were consistent across the liver from these three species. Our pig liver annotation and functional characterization studies provide a system and resource for noncoding annotation for future gene regulatory studies in pigs. Furthermore, our study also showed the high level functional conservation of cis-regulatory elements in mammals; it also improved our understanding of regulation function of mammal cis-regulatory elements.