Subtitle: Study Reveals Specific Blend Activates Akt/mTOR Pathway to Combat Muscle Protein Degradation
A 2024 study published in Food and Fermentation Industries demonstrates that a specific combination of wheat, soybean, and pea peptides can effectively counteract TNF-α-induced muscle protein degradation in C2C12 skeletal muscle cells by modulating the Akt/mTOR signaling pathway, offering promising applications for sports nutrition and muscle health.
Numerous studies have confirmed that small-molecule food-derived oligopeptides exhibit superior absorption characteristics compared to whole proteins, amino acids, and larger molecular weight polypeptides, while also possessing certain physiological functions. Wheat peptide, soybean peptide, and pea peptide are small-molecule oligopeptides obtained through the enzymatic hydrolysis of wheat protein, soybean protein isolate, and pea protein, respectively. This study, conducted by Cheng Gaiping, Li Mingliang, Liu Jing, and colleagues, investigated the synergistic effects of these three plant-derived peptides on protein expression in TNF-α-stimulated C2C12 skeletal muscle cells.
Background: The Role of Plant Peptides in Sports Nutrition
Various experiments have demonstrated the positive effects of wheat peptide, soybean peptide, and pea peptide in sports nutrition:
| Peptide Type | Key Findings | Source |
|---|---|---|
| Wheat Peptide | Contains high glutamine content (23.54 ± 0.49%), which promotes desmin synthesis in skeletal muscle fibers and aids in repairing exercise-induced muscle micro-damage. | Jin Zhentao et al. [2-3] |
| Wheat Peptide | Alleviates grip strength decrease, reaction time prolongation, and skeletal muscle damage in over-trained athletes; promotes recovery from exercise-induced fatigue. | Pan Xingchang et al. [4] |
| Soybean Peptide | Assists muscle growth during exercise in rats; inhibits exercise-induced increase in glucose-6-phosphate dehydrogenase; alleviates morphological changes in skeletal muscle tissue. | FUSHIKI et al. [6], Wei Yuan [7] |
| Soybean + Wheat Peptide | Synergistic effect in alleviating skeletal muscle damage by enhancing antioxidant capacity and inhibiting lipid peroxidation. | Li Mingliang et al. [8] |
| Pea Peptide | Alleviates insulin resistance; enhances immunity; inhibits ACE enzyme activity. | Cui Xinyue et al. [9], Zhang Minjia et al. [10], Zhu Ling et al. [11-12] |
Pea peptide is derived from pea protein, which has a balanced amino acid composition that meets the standard model recommended by the Food and Agriculture Organization of the United Nations and the World Health Organization, and is superior to soybean protein. Therefore, pea peptide theoretically also has a positive effect on sports nutrition. However, research on the effects of pea peptide on skeletal muscle has been scarce, and studies on the synergistic functions of combinations of multiple bioactive peptides have also been limited.
Study Design and Methods
This study established a TNF-α stimulation model to investigate the effects of combinations of wheat peptide, soybean peptide, and pea peptide on mouse skeletal muscle myoblast C2C12 cells. Based on the soybean peptide + pea peptide ratio previously established in the laboratory’s preliminary research, the researchers examined protein expression of myogenic regulatory factors, related myosin, ubiquitin ligases, and the mammalian target of rapamycin (mTOR) and its related regulatory factors, in conjunction with the Akt/mTOR pathway.
Key Methodological Parameters:
| Parameter | Details |
|---|---|
| Cell Line | C2C12 mouse skeletal muscle myoblasts |
| Stimulation Model | TNF-α at final concentration of 25 ng/mL for 4 days |
| Peptide Treatment Concentration | 200 μg/mL (determined safe by CCK-8 assay) |
| Measured Proteins | MyoD, MyoG, MyHC, TRIM63, MAFbx, Akt, p-Akt, mTOR, p-mTOR |
Key Research Findings
1. Effects on Myogenic Regulatory Factors and Myosin
Myosin heavy chain (MyHC) is the basic subunit of myosin. MyoD and MyoG are myogenic regulatory factors. MyoD is a decisive regulatory factor for the muscle lineage. MyoG gene expression can be activated by MyoD, promoting muscle stem cell differentiation.
After TNF-α treatment, the protein expression levels of MyoD, MyoG, and MyHC in C2C12 cells decreased to varying degrees compared to the control group. Particularly, the expression level of myosin heavy chain MyHC was significantly reduced compared to the control group. This trend is consistent with the decrease in MyoD and MyoG gene expression caused by oxidative stress induced by H₂O₂ in C2C12 cells reported in previous research.
After treatment with peptide samples, the expression levels of these three proteins increased to varying extents. The increase in the expression levels of the three proteins in cells treated with the XM:DD+WD = 1:3 group was the most significant compared to the model group.
2. Effects on Ubiquitin Ligases (Protein Degradation Markers)
The ubiquitin-proteasome system is the main pathway for intracellular protein degradation. In almost all types of muscle atrophy, two important E3 ubiquitin ligases are induced to be highly expressed:
- MAFbx (also known as Atrogin-1): Associated with skeletal muscle protein degradation
- TRIM63 (also known as MuRF1): Involved in skeletal muscle atrophy
In the model group, the expression levels of both proteins were significantly increased compared to the control group. After treatment with peptide samples, the expression levels of these two proteins began to decrease. The decrease in the expression levels of the two proteins in cells treated with the XM:DD+WD = 1:3 and 2:1 groups was the most significant compared to the model group.
3. Effects on Akt/mTOR Signaling Pathway
The mammalian target of rapamycin (mTOR) is one of the important downstream substrates of Akt. mTOR primarily regulates protein synthesis and degradation through the p70 S6K and 4E-BP1 signaling pathways. Additionally, activated Akt can inhibit the activity of glycogen synthase kinase 3β (GSK3β), thereby increasing protein synthesis.
In the model group, the phosphorylation levels of Akt and mTOR were significantly reduced compared to the control group. After treatment with peptide samples, the phosphorylation levels of these two proteins increased to varying degrees. The increase in the phosphorylation levels of the two proteins in cells treated with the XM:DD+WD = 1:3 group was the most significant compared to the model group.
Mechanistic Insights: The Akt/mTOR Pathway
Anabolism is the foundation of muscle regeneration, repair, and remodeling. A key anabolic pathway affecting muscle health is the serine/threonine kinase/mammalian target of rapamycin (Akt/mTOR) pathway, which plays a crucial role in protein translation (upregulating translation initiation and ribosome biogenesis).
This study found that the trends in the expression changes of MyoD, MyoG, MyHC, MAFbx, and TRIM63 proteins were consistent with the expression trends of phosphorylated Akt and mTOR. This indicates that the effect of wheat peptide combined with soybean peptide + pea peptide in improving muscle protein expression in C2C12 cells is regulated by the Akt/mTOR pathway.
The peptides can:
- Decrease the expression of E3 ubiquitin ligases (MAFbx, TRIM63)
- Increase the phosphorylation levels of Akt and mTOR proteins
- Thereby reducing protein degradation and promoting protein synthesis in the cells
| Protein | Function | Effect of Optimal Peptide Blend (1:3 Ratio) |
|---|---|---|
| MyoD | Myogenic regulatory factor (muscle lineage determination) | ↑ Significantly increased |
| MyoG | Myogenic regulatory factor (muscle stem cell differentiation) | ↑ Significantly increased |
| MyHC | Myosin heavy chain (muscle contraction) | ↑ Significantly increased |
| MAFbx | E3 ubiquitin ligase (protein degradation marker) | ↓ Significantly decreased |
| TRIM63 | E3 ubiquitin ligase (muscle atrophy marker) | ↓ Significantly decreased |
| p-Akt/Akt | Kinase (activates protein synthesis) | ↑ Significantly increased |
| p-mTOR/mTOR | Kinase (regulates protein synthesis) | ↑ Significantly increased |
Conclusions and Implications
This study successfully established a TNF-α-stimulated C2C12 cell model to investigate the effects of plant peptide combinations on muscle protein metabolism. The key findings are:
- TNF-α effectively induces muscle protein degradation by decreasing myogenic regulatory factors (MyoD, MyoG) and myosin (MyHC), while increasing ubiquitin ligases (MAFbx, TRIM63).
- The combination of wheat peptide with soybean peptide + pea peptide at a mass ratio of 1:3 was the most effective among several tested ratios in ameliorating the decrease in muscle protein content caused by TNF-α.
- The mechanism of action involves the Akt/mTOR signaling pathway. The peptide blend increases phosphorylation of Akt and mTOR, thereby promoting protein synthesis and reducing protein degradation.
These findings have significant implications for sports nutrition and muscle health applications:
- Sports Recovery: The 1:3 peptide blend could be developed into functional foods or supplements to accelerate muscle recovery after intense exercise.
- Age-Related Muscle Loss (Sarcopenia): The blend may help combat muscle wasting associated with aging by promoting anabolic pathways.
- Clinical Nutrition: Potential applications in conditions involving muscle atrophy, such as cachexia or recovery from injury.
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Post time: Mar-02-2026
