MicroRNAs (miRNAs) are endogenous small non-coding RNAs that play crucial regulatory roles in many biological processes, including the growth and development of skeletal muscle. miRNA-100-5p is often associated with tumor cell proliferation and migration. This study aimed to uncover the regulatory mechanism of miRNA-100-5p in myogenesis. In our study, we found that the miRNA-100-5p expression level was significantly higher in muscle tissue than in other tissues in pigs. Functionally, this study shows that miR-100-5p overexpression significantly promotes the proliferation and inhibits the differentiation of C2C12 myoblasts, whereas miR-100-5p inhibition results in the opposite effects. Bioinformatic analysis predicted that Trib2 has potential binding sites for miR-100-5p at the 3′UTR region. A dual-luciferase assay, qRT-qPCR, and Western blot confirmed that Trib2 is a target gene of miR-100-5p. We further explored the function of Trib2 in myogenesis and found that Trib2 knockdown markedly facilitated proliferation but suppressed the differentiation of C2C12 myoblasts, which is contrary to the effects of miR-100-5p. In addition, co-transfection experiments demonstrated that Trib2 knockdown could attenuate the effects of miR-100-5p inhibition on C2C12 myoblasts differentiation. In terms of the molecular mechanism, miR-100-5p suppressed C2C12 myoblasts differentiation by inactivating the mTOR/S6K signaling pathway. Taken together, our study results indicate that miR-100-5p regulates skeletal muscle myogenesis through the Trib2/mTOR/S6K signaling pathway.

Muscle cell growth plays an important role in skeletal muscle development. Circular RNAs (circRNAs) have been proven to be involved in the regulation of skeletal muscle growth and development. In this study, we explored the effect of circTTN on myoblast growth and its possible molecular mechanism. Using C2C12 cells as a functional model, the authenticity of circTTN was confirmed by RNase R digestion and Sanger sequencing. Previous functional studies have showed that the overexpression of circTTN inhibits myoblast proliferation and differentiation. Mechanistically, circTTN recruits the PURB protein on the Titin (TTN) promoter to inhibit the expression of the TTN gene. Moreover, PURB inhibits myoblast proliferation and differentiation, which is consistent with circTTN function. In summary, our results indicate that circTTN inhibits the transcription and myogenesis of the host gene TTN by recruiting PURB proteins to form heterotypic complexes. This work may act as a reference for further research on the role of circRNA in skeletal muscle growth and development.

Background: Crossbreeding strategies that combine the growth performance of Western pig breeds with the meat quality traits of Chinese indigenous breeds have garnered considerable interest. Duroc pigs are known for their high growth efficiency but have relatively low intramuscular fat (IMF) content. In contrast, native breeds like the Diannan Small-Eared pig exhibit superior pork quality with higher IMF levels. This study aimed to compare the muscle growth characteristics and molecular mechanisms between Duroc × Landrace × Yorkshire (DLY) and Duroc × Berkshire × Diannan Small-Eared (DBD) pigs. Methods: The longissimus dorsi tissue of 210-day-old DLY and DBD pigs was collected for analysis. HE staining assessed muscle fiber characteristics, IMF content was measured, and ELISA quantified muscle-derived growth and development-related factors. Transcriptome sequencing was conducted, followed by differential gene expression analysis, Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and protein–protein interaction (PPI) analyses. Functional validation of key genes was performed in C2C12 cells. Results: DBD pigs exhibited significantly larger muscle fiber diameter and higher IMF content compared to DLY pigs. IGF1 and GH levels were elevated in DBD pigs. Transcriptome analysis identified 185 upregulated and 102 downregulated genes, with enrichment in pathways including PI3K-Akt, MAPK, FoxO, and cGMP-PKG signaling. ACSL1 and FABP3 were functionally validated, showing promotion of differentiation and inhibition of proliferation in C2C12 cells. Conclusions: DBD pigs exhibit superior muscle growth traits and higher IMF content compared to DLY pigs. ACSL1 and FABP3 may serve as key regulators of muscle development in pigs.

To unravel the genetic basis of economically critical reproductive traits in swine, we genotyped 839 sows from three commercial breeds (Duroc, Landrace, Yorkshire) using the Porcine Breeding Chip_plus 50K SNP array, and analyzed three key traits: total number born (TNB), number born alive (NBA), and number of healthy piglets (NHP). We integrated principal component analysis (PCA) for population structure, runs of homozygosity (ROH) detection, genome-wide association studies (GWAS), and GO/KEGG enrichment analysis. Phenotypically, Yorkshire sows exhibited superior and persistent reproductive capacity across parities 1–7 (peak TNB: 14.17 ± 2.82 at parity 4 based on N ≥ 3 data), Duroc sows had limited data with only parity 1 available (TNB: 9.44 ± 2.13), and Landrace sows showed moderate to high performance across parities 1–4 and 7, with peak TNB at parity 4 (17.08 ± 4.61). ROH analysis further revealed that short ROH fragments (1–5 Mb) were the most abundant category across breeds, while the majority of detected ROH were under 10 Mb in length. GWAS identified significant SNPs concentrated on chromosomes 1 and 2, and annotated candidate genes including AMH (ovarian reserve), IZUMO4 (embryo implantation), ACSBG2 (steroid synthesis), RFX2 (follicular maturation), and DOT1L (embryonic development). GO/KEGG enrichment highlighted pathways such as “histone methyltransferase activity” and “fatty acid biosynthesis”, which are critical for reproductive processes. This study clarifies breed-specific reproductive patterns and identifies key genetic loci/genes for porcine reproductive traits, providing molecular markers and a theoretical basis for improving swine reproductive performance via molecular breeding.

This study systematically explored the regulatory mechanisms of uterine function across four reproductive stages: sexual maturity sow (SMS), low-yield sow (LYS), high-yield sow (HYS), and culled sow (CS) in Large White (LW) pigs through integrated transcriptomic, proteomic, and metabolomic analyses. Twelve healthy LW sows were selected, and uterine tissues were collected for multi-omics detection. Combined with bioinformatics analysis, molecular regulatory networks were constructed. Results showed that transcriptomics identified 12 types of alternative splicing and 1243 novel genes, which were enriched in energy metabolism and signal transduction pathways. Proteomics revealed 430 differentially co-expressed proteins, indicating high protein synthesis activity in the SMS stage and extracellular inflammatory characteristics in the CS stage. Metabolomics detected numerous differential metabolites, among which XTP and DHA ethyl ester were associated with high fecundity and aging, respectively. Integrated multi-omics analysis identified hub genes such as PLA2G4A, which influence reproductive performance by regulating inflammatory and metabolic balance, and clarified stage-specific “gene–protein–metabolite” modules. This study provides a molecular map for understanding dynamic changes in uterine function in Large White pigs and offers a theoretical basis for optimizing reproductive lifespan and breeding strategies.