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Various jobs of proteolytic enzymes in skeletal muscle during unloading: facts and speculations.

Kachaeva EV, Shenkman BS - J. Biomed. Biotechnol. (2012)

Bottom Line: Skeletal muscles, namely, postural muscles, as soleus, suffer from atrophy under disuse.Disuse atrophy is supposed to be the result of shift of protein synthesis/proteolysis balance towards protein degradation increase.Maintaining of the balance involves many systems of synthesis and proteolysis, whose activation leads to muscle adaptation to disuse rather than muscle degeneration.

View Article: PubMed Central - PubMed

Affiliation: SSC RF Institute for Biomedical Problems, RAS, Moscow, Russia. e_kachaeva@mail.ru

ABSTRACT
Skeletal muscles, namely, postural muscles, as soleus, suffer from atrophy under disuse. Muscle atrophy development caused by unloading differs from that induced by denervation or other stimuli. Disuse atrophy is supposed to be the result of shift of protein synthesis/proteolysis balance towards protein degradation increase. Maintaining of the balance involves many systems of synthesis and proteolysis, whose activation leads to muscle adaptation to disuse rather than muscle degeneration. Here, we review recent data on activity of signaling systems involved in muscle atrophy development under unloading and muscle adaptation to the lack of support.

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MuRF-2 localization on titin molecule [73].
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Related In: Results  -  Collection


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fig3: MuRF-2 localization on titin molecule [73].

Mentions: Results of studies on volunteers using biopsy of vastus lateralis revealed difference between muscle atrophy development in animal and in human, because, in human biopsy significant decrement of protein synthesis and lack of proteolysis increase were observed [68]. At the same time, studies on volunteers during antiorthostatic head-down bed-rest showed increased MuRF-1 quantity in soleus (slow muscle), rather than in vastus lateralis (containing predominantly fast fibers) [69]. Later, expression intensification of MAFbx and ubiquitin ligase cbl-b was found in vastus lateralis after 20 days of disuse [70]. After 48 hours of unilateral lower limb suspension of volunteers, complete genomic analysis revealed increase in expression rate of mRNA of E3 ubiquitin ligases [71], also accumulation of 3-metilhistidine, product of degradation of myofibril proteins (actin and some myosin) was observed [72]. Ten days of immobilization caused threefold increase in MuRF-1 mRNA content in quadriceps femoris, which, however, was diminished to the control level to the 21st day of unloading [73]. We also observed changes in expression rate of ubiquitin ligases under HS of animals. Thus, we found that expression rate of MuRF-1 and MAFbx mRNA in rat soleus increased 3 .3 and 2 .1 times, correspondingly, at the 3rd day of disuse. To the 7th day of HS, this parameter decreased but was 1 .27 and 1 .52 times higher than in control (Figure 3) [74]. The 37% increase in total level of protein ubiquitination at the 4th day of functional unloading [75] confirms our data.


Various jobs of proteolytic enzymes in skeletal muscle during unloading: facts and speculations.

Kachaeva EV, Shenkman BS - J. Biomed. Biotechnol. (2012)

MuRF-2 localization on titin molecule [73].
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3303694&req=5

fig3: MuRF-2 localization on titin molecule [73].
Mentions: Results of studies on volunteers using biopsy of vastus lateralis revealed difference between muscle atrophy development in animal and in human, because, in human biopsy significant decrement of protein synthesis and lack of proteolysis increase were observed [68]. At the same time, studies on volunteers during antiorthostatic head-down bed-rest showed increased MuRF-1 quantity in soleus (slow muscle), rather than in vastus lateralis (containing predominantly fast fibers) [69]. Later, expression intensification of MAFbx and ubiquitin ligase cbl-b was found in vastus lateralis after 20 days of disuse [70]. After 48 hours of unilateral lower limb suspension of volunteers, complete genomic analysis revealed increase in expression rate of mRNA of E3 ubiquitin ligases [71], also accumulation of 3-metilhistidine, product of degradation of myofibril proteins (actin and some myosin) was observed [72]. Ten days of immobilization caused threefold increase in MuRF-1 mRNA content in quadriceps femoris, which, however, was diminished to the control level to the 21st day of unloading [73]. We also observed changes in expression rate of ubiquitin ligases under HS of animals. Thus, we found that expression rate of MuRF-1 and MAFbx mRNA in rat soleus increased 3 .3 and 2 .1 times, correspondingly, at the 3rd day of disuse. To the 7th day of HS, this parameter decreased but was 1 .27 and 1 .52 times higher than in control (Figure 3) [74]. The 37% increase in total level of protein ubiquitination at the 4th day of functional unloading [75] confirms our data.

Bottom Line: Skeletal muscles, namely, postural muscles, as soleus, suffer from atrophy under disuse.Disuse atrophy is supposed to be the result of shift of protein synthesis/proteolysis balance towards protein degradation increase.Maintaining of the balance involves many systems of synthesis and proteolysis, whose activation leads to muscle adaptation to disuse rather than muscle degeneration.

View Article: PubMed Central - PubMed

Affiliation: SSC RF Institute for Biomedical Problems, RAS, Moscow, Russia. e_kachaeva@mail.ru

ABSTRACT
Skeletal muscles, namely, postural muscles, as soleus, suffer from atrophy under disuse. Muscle atrophy development caused by unloading differs from that induced by denervation or other stimuli. Disuse atrophy is supposed to be the result of shift of protein synthesis/proteolysis balance towards protein degradation increase. Maintaining of the balance involves many systems of synthesis and proteolysis, whose activation leads to muscle adaptation to disuse rather than muscle degeneration. Here, we review recent data on activity of signaling systems involved in muscle atrophy development under unloading and muscle adaptation to the lack of support.

Show MeSH
Related in: MedlinePlus