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Differential expression of apoptosis-related factors induces the age-related apoptosis of the gracilis muscle in humans.

Park SY, Lee JH, Kim HY, Yoon KH, Park SK, Chang MS - Int. J. Mol. Med. (2014)

Bottom Line: TUNEL assay revealed a significant increase in gracilis muscle apoptosis with aging.The activity of caspase-3 in the gracilis muscle tended to change with age, although the changes were not significant, while the increase in DNA nuclei in muscle from 50 years of age (5.419±0.97) was associated with an increase in the expression of AIF, as observed both at protein (10-30%) and mRNA level (10-60%) in gracilis tissues.Taken together, our results demonstrated that the relative Bcl-2 expression decreased with aging, while Bax expression was upregulated compared to 10-year-olds.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Education, Yong In University, Seoul 130-701, Republic of Korea.

ABSTRACT
In the normal aging process, apoptosis has been implicated as a mechanism responsible for the loss of muscle cells and plays an important role in age-related muscle loss. Several signaling pathways involved in skeletal muscle apoptosis are currently under intense investigation, particularly the caspase-independent pathway. This study investigated the age-related apoptotic changes occurring in the gracilis muscle in humans between 10 and 50 years of age. For this purpose, muscle samples were divided into 5 groups (n=8). Terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) staining and immunofluorescence detection were performed to determine the number of apoptotic muscle cells in each group. In addition, the expression levels of apoptosis-related factors, such as Bcl-2, Bax, apoptosis-inducing factor (AIF), caspase-3 and calpain-1 were determined by RT-PCR and western blot analysis. TUNEL assay revealed a significant increase in gracilis muscle apoptosis with aging. The activity of caspase-3 in the gracilis muscle tended to change with age, although the changes were not significant, while the increase in DNA nuclei in muscle from 50 years of age (5.419±0.97) was associated with an increase in the expression of AIF, as observed both at protein (10-30%) and mRNA level (10-60%) in gracilis tissues. Taken together, our results demonstrated that the relative Bcl-2 expression decreased with aging, while Bax expression was upregulated compared to 10-year-olds. In addition, a double-labeling experiment with TUNEL staining and immunofluorescence revealed the co-localization of nuclear AIF-positive and TUNEL-labeled cells. This study suggests that apoptosis in gracilis skeletal muscle in the elderly is partly mediated through the expression of Bcl-2/Bax and the degradation of AIF.

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Gracilis muscle sampling and staining of morphological changes in gracilis skeletal muscle. (A) Muscle tissues sampling were prepared from the musculotendinous junction. (B) Staining of morphological changes in frozen sections of gracilis skeletal muscle using the hematoxylin and eosin (H&E). (a) Individuals of 10 years of age, (b) 20 years of age, (c) 30 years of age, (d) 40 years of age, and (e) 50 years of age. Images were obtained at an objective magnification of ×200. Scale bars, 150 μm.
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f1-ijmm-33-05-1110: Gracilis muscle sampling and staining of morphological changes in gracilis skeletal muscle. (A) Muscle tissues sampling were prepared from the musculotendinous junction. (B) Staining of morphological changes in frozen sections of gracilis skeletal muscle using the hematoxylin and eosin (H&E). (a) Individuals of 10 years of age, (b) 20 years of age, (c) 30 years of age, (d) 40 years of age, and (e) 50 years of age. Images were obtained at an objective magnification of ×200. Scale bars, 150 μm.

Mentions: Samples of gracilis skeletal muscle were collected from the musculotendinous junction of different individuals (Fig. 1A). We used H&E staining to examine the morphological changes induced by apoptosis from aging in human gracilis skeletal muscle (Fig. 1B). The detection of large numbers of nuclei is a distinct feature of necrosis. With H&E staining, none of the tissues showed evidence of necrosis.


Differential expression of apoptosis-related factors induces the age-related apoptosis of the gracilis muscle in humans.

Park SY, Lee JH, Kim HY, Yoon KH, Park SK, Chang MS - Int. J. Mol. Med. (2014)

Gracilis muscle sampling and staining of morphological changes in gracilis skeletal muscle. (A) Muscle tissues sampling were prepared from the musculotendinous junction. (B) Staining of morphological changes in frozen sections of gracilis skeletal muscle using the hematoxylin and eosin (H&E). (a) Individuals of 10 years of age, (b) 20 years of age, (c) 30 years of age, (d) 40 years of age, and (e) 50 years of age. Images were obtained at an objective magnification of ×200. Scale bars, 150 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4020492&req=5

f1-ijmm-33-05-1110: Gracilis muscle sampling and staining of morphological changes in gracilis skeletal muscle. (A) Muscle tissues sampling were prepared from the musculotendinous junction. (B) Staining of morphological changes in frozen sections of gracilis skeletal muscle using the hematoxylin and eosin (H&E). (a) Individuals of 10 years of age, (b) 20 years of age, (c) 30 years of age, (d) 40 years of age, and (e) 50 years of age. Images were obtained at an objective magnification of ×200. Scale bars, 150 μm.
Mentions: Samples of gracilis skeletal muscle were collected from the musculotendinous junction of different individuals (Fig. 1A). We used H&E staining to examine the morphological changes induced by apoptosis from aging in human gracilis skeletal muscle (Fig. 1B). The detection of large numbers of nuclei is a distinct feature of necrosis. With H&E staining, none of the tissues showed evidence of necrosis.

Bottom Line: TUNEL assay revealed a significant increase in gracilis muscle apoptosis with aging.The activity of caspase-3 in the gracilis muscle tended to change with age, although the changes were not significant, while the increase in DNA nuclei in muscle from 50 years of age (5.419±0.97) was associated with an increase in the expression of AIF, as observed both at protein (10-30%) and mRNA level (10-60%) in gracilis tissues.Taken together, our results demonstrated that the relative Bcl-2 expression decreased with aging, while Bax expression was upregulated compared to 10-year-olds.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Education, Yong In University, Seoul 130-701, Republic of Korea.

ABSTRACT
In the normal aging process, apoptosis has been implicated as a mechanism responsible for the loss of muscle cells and plays an important role in age-related muscle loss. Several signaling pathways involved in skeletal muscle apoptosis are currently under intense investigation, particularly the caspase-independent pathway. This study investigated the age-related apoptotic changes occurring in the gracilis muscle in humans between 10 and 50 years of age. For this purpose, muscle samples were divided into 5 groups (n=8). Terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) staining and immunofluorescence detection were performed to determine the number of apoptotic muscle cells in each group. In addition, the expression levels of apoptosis-related factors, such as Bcl-2, Bax, apoptosis-inducing factor (AIF), caspase-3 and calpain-1 were determined by RT-PCR and western blot analysis. TUNEL assay revealed a significant increase in gracilis muscle apoptosis with aging. The activity of caspase-3 in the gracilis muscle tended to change with age, although the changes were not significant, while the increase in DNA nuclei in muscle from 50 years of age (5.419±0.97) was associated with an increase in the expression of AIF, as observed both at protein (10-30%) and mRNA level (10-60%) in gracilis tissues. Taken together, our results demonstrated that the relative Bcl-2 expression decreased with aging, while Bax expression was upregulated compared to 10-year-olds. In addition, a double-labeling experiment with TUNEL staining and immunofluorescence revealed the co-localization of nuclear AIF-positive and TUNEL-labeled cells. This study suggests that apoptosis in gracilis skeletal muscle in the elderly is partly mediated through the expression of Bcl-2/Bax and the degradation of AIF.

Show MeSH