The Tocotrienol-Rich Fraction Is Superior to Tocopherol in Promoting Myogenic Differentiation in the Prevention of Replicative Senescence of Myoblasts

Abstract

Aging results in a loss of muscle mass and strength. Myoblasts play an important role in maintaining muscle mass through regenerative processes, which are impaired during aging. Vitamin E potentially ameliorates age-related phenotypes. Hence, this study aimed to determine the effects of the tocotrienol-rich fraction (TRF) and α-tocopherol (ATF) in protecting myoblasts from replicative senescence and promoting myogenic differentiation. Primary human myoblasts were cultured into young and senescent stages and were then treated with TRF or ATF for 24 h, followed by an analysis of cell proliferation, senescence biomarkers, cellular morphology and differentiation. Our data showed that replicative senescence impaired the normal regenerative processes of myoblasts, resulting in changes in cellular morphology, cell proliferation, senescence-associated β-galactosidase (SA-β-gal) expression, myogenic differentiation and myogenic regulatory factors (MRFs) expression. Treatment with both TRF and ATF was beneficial to senescent myoblasts in reclaiming the morphology of young cells, improved cell viability and decreased SA-β-gal expression. However, only TRF treatment increased BrdU incorporation in senescent myoblasts, as well as promoted myogenic differentiation through the modulation of MRFs at the mRNA and protein levels. MYOD1 and MYOG gene expression and myogenin protein expression were modulated in the early phases of myogenic differentiation. In conclusion, the tocotrienol-rich fraction is superior to α-tocopherol in ameliorating replicative senescence-related aberration and promoting differentiation via modulation of MRFs expression, indicating vitamin E potential in modulating replicative senescence of myoblasts.

Potential Role of Tocotrienols on Non-Communicable Diseases: A Review of Current Evidence

“…An adjusted data according to plasma concentration and daily intake showed a strong correlation between γTF and muscle strength, as well as a significant correlation between αTF and both measurements [207]. Although this study only focused on the effects two types of TF on muscle strength, several experimental studies examining the antioxidant effects of T3 have found that T3 was superior due to their better distribution in the lipid layers of the cell membrane [199,208]. Thus, T3 may act as a better antioxidant than TF.…”

“…It was also shown to reverse senescence in stress-induced pre-senescence myoblasts, demonstrating the potential therapeutic effects of TRF on senescent muscle cells [198]. Furthermore, Khor et al suggested that TRF was superior to αTF in promoting myogenic differentiation followed by prevention of replicative senescence of myoblasts [199].…”

Modulation of Ki67 and myogenic regulatory factor expression by tocotrienol-rich fraction ameliorates myogenic program of senescent human myoblasts

“…Cells were cultivated at 37°C in a humid atmosphere containing 5% CO 2 . After that, the myoblasts were expanded extensively to reach replicative senescence, which was manifested by the decline in proliferative capacity and accumulation of senescence biomarker in culture [15]. For each passage, the population doubling (PD) of cells was calculated as: ln(N/n)/In2, where N is the number of cells at harvest stage and n is the number of cells at seeding stage.…”

“…Replicative senescence affects myogenic differentiation in myoblasts resulting in the production of impaired myotubes [14]. The expression of the factors regulating myogenic differentiation, such as myogenic regulatory factors (MRFs), is deregulated in senescent myoblasts [15,16]. The MRFs, which include Myf5, MyoD, myogenin and MRF4, are the key transcription factors in the myogenic specification, differentiation and maintenance [17].…”

“…Besides its antioxidant activity, vitamin E, particularly TRF, has shown non-antioxidant properties, acting as signaling molecules and modulating gene and protein expression. Moreover, TRF can ameliorate the replicative senescence-related abnormalities, including improving proliferation capacity of senescent myoblasts and promoting the myogenic differentiation via modulation of MRF gene expression [15]. However, our previous study focused on the effect of TRF which was given to myoblast cells during the proliferation phase before stimulation of the differentiation phase.…”