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Attenuation of muscle wasting in murine C2C 12 myotubes by epigallocatechin-3-gallate.

Mirza KA, Pereira SL, Edens NK, Tisdale MJ - J Cachexia Sarcopenia Muscle (2014)

Bottom Line: EGCg effectively attenuated the depression of protein synthesis and increase in protein degradation in murine myotubes at concentrations as low as 10 μM.Serum starvation did not increase expression of the ubiquitin ligases MuRF1 and MAFbx, but EGCg reduced their expression below basal levels, possibly due to an increased expression of phospho Akt (pAkt) and phospho forkhead box O3a (pFoxO3a).The ability of EGCg to attenuate depressed protein synthesis and increase protein degradation in the myotubule model system suggests that it may be effective in preserving skeletal muscle mass in catabolic conditions.

View Article: PubMed Central - PubMed

Affiliation: Nutritional Biomedicine, School of Life and Health Sciences, Aston University, Birmingham, B4 7ET, UK, k.a.mirza@aston.ac.uk.

ABSTRACT

Background: Loss of muscle protein is a common feature of wasting diseases where currently treatment is limited. This study investigates the potential of epigallocatechin-3-gallate (EGCg), the most abundant catechin in green tea, to reverse the increased protein degradation and rescue the decreased protein synthesis which leads to muscle atrophy.

Methods: Studies were conducted in vitro using murine C2C12 myotubes. Increased protein degradation and reduced rates of protein synthesis were induced by serum starvation and tumour necrosis factor-α (TNF-α).

Results: EGCg effectively attenuated the depression of protein synthesis and increase in protein degradation in murine myotubes at concentrations as low as 10 μM. Serum starvation increased expression of the proteasome 20S and 19S subunits, as well as the proteasome 'chymotrypsin-like' enzyme activity, and these were all attenuated down to basal values in the presence of EGCg. Serum starvation did not increase expression of the ubiquitin ligases MuRF1 and MAFbx, but EGCg reduced their expression below basal levels, possibly due to an increased expression of phospho Akt (pAkt) and phospho forkhead box O3a (pFoxO3a). Attenuation of protein degradation by EGCg was increased in the presence of ZnSO4, suggesting an EGCg-Zn(2+) complex may be the active species.

Conclusion: The ability of EGCg to attenuate depressed protein synthesis and increase protein degradation in the myotubule model system suggests that it may be effective in preserving skeletal muscle mass in catabolic conditions.

No MeSH data available.


Related in: MedlinePlus

Effect of EGCg on protein synthesis (a) and protein degradation (b) in murine myotubes in the presence of TNF-α. Myotubes were incubated with TNF-α (50 ng/ml) for 2 h in the absence, or presence of EGCg, and protein synthesis was measured over the following 4 h, while protein degradation was measured after 24 h in the presence of TNF-α. Differences from NC are shown as *p < 0.05, while differences from TNFα alone in the presence of EGCg are shown as †p < 0.05, ††p < 0.01 and †††p < 0.001
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Fig5: Effect of EGCg on protein synthesis (a) and protein degradation (b) in murine myotubes in the presence of TNF-α. Myotubes were incubated with TNF-α (50 ng/ml) for 2 h in the absence, or presence of EGCg, and protein synthesis was measured over the following 4 h, while protein degradation was measured after 24 h in the presence of TNF-α. Differences from NC are shown as *p < 0.05, while differences from TNFα alone in the presence of EGCg are shown as †p < 0.05, ††p < 0.01 and †††p < 0.001

Mentions: To determine whether EGCg could also overcome the depression of protein synthesis and increase protein degradation caused by inflammatory cytokines, myotubes were exposed to TNF-α (50 ng/ml) for 4 h (Fig. 5a) or 24 h (Fig. 5b) in the absence or presence of EGCg (10 and 50 μM). This concentration of TNF-α was employed because previous studies [12] had indicated that lower concentrations had no significant effect on protein synthesis or degradation in murine myotubes. The results (Fig. 5) show that both concentrations of EGCg attenuated the depression of protein synthesis and increased protein degradation induced by TNF-α, while at 25 μM EGCg reduced protein degradation below basal levels in the negative control (NC).Fig. 5


Attenuation of muscle wasting in murine C2C 12 myotubes by epigallocatechin-3-gallate.

Mirza KA, Pereira SL, Edens NK, Tisdale MJ - J Cachexia Sarcopenia Muscle (2014)

Effect of EGCg on protein synthesis (a) and protein degradation (b) in murine myotubes in the presence of TNF-α. Myotubes were incubated with TNF-α (50 ng/ml) for 2 h in the absence, or presence of EGCg, and protein synthesis was measured over the following 4 h, while protein degradation was measured after 24 h in the presence of TNF-α. Differences from NC are shown as *p < 0.05, while differences from TNFα alone in the presence of EGCg are shown as †p < 0.05, ††p < 0.01 and †††p < 0.001
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4248406&req=5

Fig5: Effect of EGCg on protein synthesis (a) and protein degradation (b) in murine myotubes in the presence of TNF-α. Myotubes were incubated with TNF-α (50 ng/ml) for 2 h in the absence, or presence of EGCg, and protein synthesis was measured over the following 4 h, while protein degradation was measured after 24 h in the presence of TNF-α. Differences from NC are shown as *p < 0.05, while differences from TNFα alone in the presence of EGCg are shown as †p < 0.05, ††p < 0.01 and †††p < 0.001
Mentions: To determine whether EGCg could also overcome the depression of protein synthesis and increase protein degradation caused by inflammatory cytokines, myotubes were exposed to TNF-α (50 ng/ml) for 4 h (Fig. 5a) or 24 h (Fig. 5b) in the absence or presence of EGCg (10 and 50 μM). This concentration of TNF-α was employed because previous studies [12] had indicated that lower concentrations had no significant effect on protein synthesis or degradation in murine myotubes. The results (Fig. 5) show that both concentrations of EGCg attenuated the depression of protein synthesis and increased protein degradation induced by TNF-α, while at 25 μM EGCg reduced protein degradation below basal levels in the negative control (NC).Fig. 5

Bottom Line: EGCg effectively attenuated the depression of protein synthesis and increase in protein degradation in murine myotubes at concentrations as low as 10 μM.Serum starvation did not increase expression of the ubiquitin ligases MuRF1 and MAFbx, but EGCg reduced their expression below basal levels, possibly due to an increased expression of phospho Akt (pAkt) and phospho forkhead box O3a (pFoxO3a).The ability of EGCg to attenuate depressed protein synthesis and increase protein degradation in the myotubule model system suggests that it may be effective in preserving skeletal muscle mass in catabolic conditions.

View Article: PubMed Central - PubMed

Affiliation: Nutritional Biomedicine, School of Life and Health Sciences, Aston University, Birmingham, B4 7ET, UK, k.a.mirza@aston.ac.uk.

ABSTRACT

Background: Loss of muscle protein is a common feature of wasting diseases where currently treatment is limited. This study investigates the potential of epigallocatechin-3-gallate (EGCg), the most abundant catechin in green tea, to reverse the increased protein degradation and rescue the decreased protein synthesis which leads to muscle atrophy.

Methods: Studies were conducted in vitro using murine C2C12 myotubes. Increased protein degradation and reduced rates of protein synthesis were induced by serum starvation and tumour necrosis factor-α (TNF-α).

Results: EGCg effectively attenuated the depression of protein synthesis and increase in protein degradation in murine myotubes at concentrations as low as 10 μM. Serum starvation increased expression of the proteasome 20S and 19S subunits, as well as the proteasome 'chymotrypsin-like' enzyme activity, and these were all attenuated down to basal values in the presence of EGCg. Serum starvation did not increase expression of the ubiquitin ligases MuRF1 and MAFbx, but EGCg reduced their expression below basal levels, possibly due to an increased expression of phospho Akt (pAkt) and phospho forkhead box O3a (pFoxO3a). Attenuation of protein degradation by EGCg was increased in the presence of ZnSO4, suggesting an EGCg-Zn(2+) complex may be the active species.

Conclusion: The ability of EGCg to attenuate depressed protein synthesis and increase protein degradation in the myotubule model system suggests that it may be effective in preserving skeletal muscle mass in catabolic conditions.

No MeSH data available.


Related in: MedlinePlus