Effects of Ten-Eleven Translocation-2 (Tet2) on myogenic differentiation of chicken myoblasts

Integrative Transcriptomic and Metabolomic Analysis of Muscle and Liver Reveals Key Molecular Pathways Influencing Growth Traits in Zhedong White Geese

Geese (Anser cygnoides) are popular worldwide with consumers for their unique meat quality, egg production, foie gras, and goose down; however, the key genes that influence geese growth remain elusive. To explore the mechanism of geese growth, a total of 500 Zhedong White geese were raised; four high-weight (HW) and four low-weight (LW) male geese were selected to collect carcass traits and for further transcriptomic and metabolomic analysis. The body weight and average daily gain of HW geese were significantly higher than those of the LW geese (p-value < 0.05), and the yields of the liver, gizzard, glandular stomach, and pancreas showed no significant difference between the HW and the LW group (p-value > 0.05). Compared with the LW geese, 19 differentially expressed genes (DEGs) (i.e., COL11A2, COL22A1, and TF) were detected in the breast muscle from the HW geese, which were involved in the PPAR signaling pathway, adipocytokine signaling pathway, fatty acid biosynthesis, and ferroptosis. A total of 59 differential accumulation metabolites (DAMs), which influence the pathways of glutathione metabolism and vitamin B6 metabolism, were detected in the breast muscle between the HW and LW geese. In the liver, 106 DEGs (i.e., THSD4, CREB3L3, and CNST) and 202 DAMs were found in the livers of the HW and LW groups, respectively. DEGs regulated the pathways of the TGF-beta signaling pathway, pyruvate metabolism, and adipocytokine signaling pathway; DAMs were involved in pyrimidine metabolism, nitrogen metabolism, and phenylalanine metabolism. Correlation analysis between the top DEGs and DAMs revealed that in the breast muscle, the expression levels of COL11A2 and COL22A1 were positively correlated with the content of S-(2-Hydroxy-3-buten-1-yl)glutathione. In the liver, the expression of THSD4 was positively correlated with the content of 2-Hydroxyhexadecanoic acid. In addition, one DEG (LOC106049048) and four DAMs (mogrol, brassidic acid, flabelline, and L-Leucyl-L-alanine) were shared in the breast muscle and liver. These important results contribute to improving the knowledge of goose growth and exploring the effective molecular markers that could be adopted for Zhedong White goose breeding.

The Development of Prenatal Muscle Satellite Cells (MuSCs) and Their Epigenetic Modifications During Skeletal Muscle Development in Yak Fetus

To investigate prenatal muscle satellite cell (MuSC) development and the associated epigenetic modifications in yak. Here, we conducted morphological and protein co-localization analyses of fetal longissimus dorsi muscle at various developmental stages using histology and immunofluorescence staining methods. Our study observed that primary muscle fibers began forming at 40 days of gestation, fully developed by 11 weeks, and secondary muscle fibers were predominantly formed by around 105 days. Throughout development, MuSCs were mainly located between the muscle fiber membrane and the basement membrane, acting as a reserve for the stem cell pool. MuSCs appeared within myotubes only during critical phases of primary and secondary muscle fiber formation. The proliferation of MuSCs gradually decreases until birth. MuSCs with 5mC modification show a trend of increasing first and then decreasing. MuSCs with 5hmC modification also present a dynamic change trend. The 41st day and 11th week are the critical periods for the changes of both. From the 11th week to around the 110th day of gestation, the modification effect of histone H3K4me3 is crucial for MuSCs during the development of the fetal longissimus dorsi muscle. Combined, our data identify key time points for yak fetal skeletal muscle growth and development and demonstrate that DNA methylation and histone modifications in MuSCs are closely related to this process, offering a valuable basis for future research into the molecular mechanisms underlying yak muscle development.

An Updated Review on the Significance of DNA and Protein Methyltransferases and De-methylases in Human Diseases: From Molecular Mechanism to Novel Therapeutic Approaches

Epigenetic mechanisms are crucial in regulating gene expression. These mechanisms include DNA methylation and histone modifications, like methylation, acetylation, and phosphorylation. DNA methylation is associated with gene expression suppression; however, histone methylation can stimulate or repress gene expression depending on the methylation pattern of lysine or arginine residues on histones. These modifications are key factors in mediating the environmental effect on gene expression regulation. Therefore, their aberrant activity is associated with the development of various diseases. The current study aimed to review the significance of DNA and histone methyltransferases and demethylases in developing various conditions, like cardiovascular diseases, myopathies, diabetes, obesity, osteoporosis, cancer, aging, and central nervous system conditions. A better understanding of the epigenetic roles in developing diseases can pave the way for developing novel therapeutic approaches for affected patients.

Knockdown of Tet2 Inhibits the Myogenic Differentiation of Chicken Myoblasts Induced by Ascorbic Acid

Ascorbic acid (also called Vitamin C, VC) strengthens the function of Tets families and directly increases DNA demethylation level to affect myogenic differentiation. However, the precise regulatory mechanism of DNA methylation in chicken myogenesis remains unclear. Results of present study showed that the mRNA expression of MyoD significantly decreased and MyoG and MyHC increased in myoblasts treated with 5 μM 5-azacytidine (5-AZA) and 5 μM VC (p < 0.05). Results also indicated the formation of myotubes was induced by 5-AZA or VC, but this effect was attenuated after knockdown of Tet2. In addition, the protein expression of TET2, DESMIN and MyHC was remarkable increased by the addition of 5-AZA or VC, and the upregulation was inhibited after knockdown of Tet2 (p < 0.05). DNA dot blot and immunofluorescence staining results suggested that the level of 5hmC was significantly increased when treated with 5-AZA or VC, even by Tet2 knockdown (p < 0.05). Moreover, 5-AZA and VC reduced the level of dimethylation of lysine 9 (H3K9me2) and trimethylation of lysine 27 of histone 3 (H3K27me3), and this inhibitory effect was eliminated after Tet2 knockdown (p < 0.05). These data indicated that Tet2 knockdown antagonized the increased levels of 5hmC and H3K27me3 induced by 5-AZA and VC, and eventually reduced myotube formation by modulating the expression of genes involved in myogenic differentiation. This study provides insights that epigenetic regulators play essential roles in mediating the myogenic program of chicken myoblasts.

Disturbance of calcium homeostasis and myogenesis caused by TET2 deletion in muscle stem cells

Skeletal muscle myogenesis is a sophisticated process controlled by genetic and epigenetic regulators. In animals, one of the key enzymes for the DNA demethylation of 5-methylcytosine is TET2. Although TET2 is essential for muscle development, the mechanisms by which TET2 regulates myogenesis, particularly the implication for muscle stem cells, remains unclear. In the present study, we employed the TET2 knockout mouse model to investigate the function of TET2 in muscle development and regeneration. We observed that TET2 deficiency caused impaired muscle stem cell proliferation and differentiation, resulting in the reduction in both myofiber number and muscle tissue size. Specifically, TET2 maintains calcium homeostasis in muscle stem cells by controlling the DNA methylation levels of the calcium pathway genes. Forced expression of the sodium/calcium exchanger protein SLC8A3 could rescue the myogenic defects in TET2 knockout cells. Our data not only illustrated the vital function of TET2 during myogenesis but also identified novel targets that contribute to calcium homeostasis for enhancing muscle function.