scholarly journals The relationship between myonuclear number and protein synthesis in individual rat skeletal muscle fibre

2021 ◽  
Author(s):  
Satoru Ato ◽  
Riki Ogasawara
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Muscle Fibre ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Skeletal Muscle Fibre ◽  
Fibre Length ◽  
Individual Muscle ◽  
The Relationship

Skeletal muscle cell has numerous nucleus within a cell. The nucleus has been considered as the central organelle for muscle protein synthesis. However, it is unclear whether myonuclear number associate with the MPS capacity within the individual muscle fibre. Therefore, the purpose of the present study was to reveal the relationship between myonuclear number per unit muscle fibre length and MPS under basal and conditions of elevated MPS by high-intensity muscle contraction (HiMC) using in vivo nascent protein labelling technique (SUnSET) in rodent. As the result, myonuclear number positively correlate to the MPS in individual muscle fibre at the basal condition. Similarly, ribosomal protein S6 (rpS6) content, which is a rough estimate of ribosome content, was positively correlated with MPS. However, myonuclear number was not associated with rpS6 content. In contrast to the basal condition, where MPS was increased by acute HiMC, no correlation was observed between myonuclear number and MPS, but the association between rpS6 and MPS was maintained. Importantly, these observations indicate that the number of nuclei in individual myofibers is related only to the MPS at rest. However, the ribosome content in individual fibres is related to the MPS of individual myofibers both at rest and in the elevated MPS, due to HiMC.

scholarly journals Novel insights into the regulation of skeletal muscle protein synthesis as revealed by a new nonradioactive in vivo technique

2010 ◽  
Vol 25 (3) ◽  
pp. 1028-1039 ◽  
Author(s):  
Craig A. Goodman ◽  
Danielle M. Mabrey ◽  
John W. Frey ◽  
Man Hing Miu ◽  
Enrico K. Schmidt ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Skeletal Muscle Protein ◽  
Skeletal Muscle Protein Synthesis

Skeletal muscle, liver and wool protein synthesis by sheep infected by the nematode Trichostrongylus colubriformis

1975 ◽  
Vol 26 (6) ◽  
pp. 1063
Author(s):  
LEA Symons ◽  
WO Jones
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Liver Protein ◽  
Trichostrongylus Colubriformis ◽  
Intestinal Nematode ◽  
Skeletal Muscle Proteins

Incorporation of radioisotopically labelled L-leucine into skeletal muscle proteins was measured in vivo and in vitro, and into liver proteins in vivo in three groups of sheep: (1) infected by Trichostrongylus colubriformis, (2) uninfected, pair-fed with the infected animals, (3) uninfected, fed ad lib. Incorporation of [14C]L-leucine by an homogenate of wool follicles from infected and uninfected sheep was also measured. Incorporation of leucine by muscle, and hence muscle protein synthesis, was equally depressed in the anorexic infected sheep losing weight, and in pair-fed animals, whether measured in vivo or in vitro, or expressed in terms of either RNA or DNA. Incorporation into protein was elevated equally in vivo in the livers of the infected and pair-fed sheep when expressed in terms of content of tissue nitrogen, but not in terms of cither nucleic acid. Incorporation by the wool follicular homogenate was appreciably depressed by the infection and is consistent with the poor wool growth in nematode infections. These results show that the same depression of skeletal muscle and, possibly, elevation of liver protein synthesis occur in a ruminant as were reported earlier for laboratory monogastric animals with intestinal nematode infections. Pair-feeding uninfected animals in both this and the earlier experiments emphasized the importance of anorexia as a major cause of these effects on protein synthesis. The importance of these effects upon production is discussed briefly.

Phosphorylation of eukaryotic initiation factor eIF2Bε in skeletal muscle during sepsis

2002 ◽  
Vol 283 (5) ◽  
pp. E1032-E1039 ◽  
Author(s):  
Thomas C. Vary ◽  
Gina Deiter ◽  
Scot R. Kimball
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Glycogen Synthase ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Sterile Inflammation ◽  
Initiation Factor ◽  
Eukaryotic Initiation Factor ◽  
Skeletal Muscle Protein

We reported that the inhibition of protein synthesis in skeletal muscle during sepsis correlated with reduced eukaryotic initiation factor eIF2B activity. The present studies define changes in eIF2Bε phosphorylation in gastrocnemius of septic animals. eIF2B kinase activity was significantly elevated 175% by sepsis compared with sterile inflammation, whereas eIF2B phosphatase activity was unaffected. Phosphorylation of eIF2Bε-Ser535 was significantly augmented over 2-fold and 2.5-fold after 3 and 5 days and returned to control values after 10 days of sepsis. Phosphorylation of glycogen synthase kinase-3 (GSK-3), a potential upstream kinase responsible for the elevated phosphorylation of eIF2Bε, was significantly reduced over 36 and 41% after 3 and 5 days and returned to control values after 10 days of sepsis. The phosphorylation of PKB, a kinase thought to directly phosphorylate and inactivate GSK-3, was significantly reduced ∼50% on day 3, but not on days 5 or 10, postinfection compared with controls. Treatment of septic rats with TNF-binding protein prevented the sepsis-induced changes in eIF2Bε and GSK-3 phosphorylation, implicating TNF in mediating the effects of sepsis. Thus increased phosphorylation of eIF2Bε via activation of GSK-3 is an important mechanism to account for the inhibition of skeletal muscle protein synthesis during sepsis. Furthermore, the study presents the first demonstration of changes in eIF2Bε phosphorylation in vivo.

Effect of insulin on rat heart and skeletal muscle phenylalanyl-tRNA labeling and protein synthesis in vivo

1994 ◽  
Vol 267 (2) ◽  
pp. E337-E342 ◽  
Author(s):  
L. H. Young ◽  
W. Stirewalt ◽  
P. H. McNulty ◽  
J. H. Revkin ◽  
E. J. Barrett
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Hormonal Regulation ◽  
Specific Activity ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
In Vivo Measurement ◽  
Arterial Plasma ◽  
Kinetics Of

In vivo measurement of muscle protein synthesis and its hormonal regulation is limited by the difficulty of measuring aminoacyl-tRNA specific activity (SA). We assessed the kinetics of heart and skeletal muscle phenylalanyl-tRNA labeling during continuous infusion of L-[ring-2,6-3H]phenylalanine (Phe) to fasted anesthetized rats. We measured Phe SA in arterial and femoral venous plasma, the tissue acid-soluble pool and muscle protein hydrolysates after 5 min (n = 7), 30 min (n = 6), and 90 min (n = 7). We also assessed insulin's effect on labeling of the tRNA pool and muscle protein synthesis during a hyperinsulinemic clamp (2 mU.kg-1.min-1; n = 7). Labeling of tRNA in heart reached 59 +/- 5, 67 +/- 3, and 83 +/- 3% of arterial SA at 5, 30, and 90 min of saline infusion, respectively, but only 10 +/- 5, 34 +/- 2, and 48 +/- 2% in skeletal muscle at those times (P < 0.01 vs. heart). The tRNA SA was intermediate between SA in the acid-soluble pool and arterial plasma. Femoral venous SA was 32 +/- 2% lower (P < 0.001) than arterial SA. Skeletal muscle tRNA SA was also 29 +/- 3% lower (P < 0.001) than femoral venous SA. Insulin did not alter tRNA labeling and neither heart (9.8 +/- 1.1%/day for saline vs. 8.4 +/- 1.0%/day for insulin) nor skeletal muscle (6.7 +/- 1.5%/day vs. 4.2 +/- 0.4%/day) protein synthesis. Thus labeling of phenylalanyl-tRNA occurs more rapidly in heart than in skeletal muscle and is unaffected by insulin.(ABSTRACT TRUNCATED AT 250 WORDS)

Neuromuscular electrical stimulation increases muscle protein synthesis in elderly type 2 diabetic men

2012 ◽  
Vol 303 (5) ◽  
pp. E614-E623 ◽  
Author(s):  
Benjamin T. Wall ◽  
Marlou L. Dirks ◽  
Lex B. Verdijk ◽  
Tim Snijders ◽  
Dominique Hansen ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Neuromuscular Electrical Stimulation ◽  
Skeletal Muscle Protein ◽  
Skeletal Muscle Protein Synthesis ◽  
Type 2 Diabetic

Physical activity is required to attenuate the loss of skeletal muscle mass with aging. Short periods of muscle disuse, due to sickness or hospitalization, reduce muscle protein synthesis rates, resulting in rapid muscle loss. The present study investigates the capacity of neuromuscular electrical stimulation (NMES) to increase in vivo skeletal muscle protein synthesis rates in older type 2 diabetes patients. Six elderly type 2 diabetic men (70 ± 2 yr) were subjected to 60 min of one-legged NMES. Continuous infusions with l-[ ring-13C6]phenylalanine were applied, with blood and muscle samples being collected regularly to assess muscle protein synthesis rates in both the stimulated (STIM) and nonstimulated control (CON) leg during 4 h of recovery after NMES. Furthermore, mRNA expression of key genes implicated in the regulation of muscle mass were measured over time in the STIM and CON leg. Muscle protein synthesis rates were greater in the STIM compared with the CON leg during recovery from NMES (0.057 ± 0.008 vs. 0.045 ± 0.008%/h, respectively, P < 0.01). Skeletal muscle myostatin mRNA expression in the STIM leg tended to increase immediately following NMES compared with the CON leg (1.63- vs. 1.00-fold, respectively, P = 0.07) but strongly declined after 2 and 4 h of recovery in the STIM leg only. In conclusion, this is the first study to show that NMES directly stimulates skeletal muscle protein synthesis rates in vivo in humans. NMES likely represents an effective interventional strategy to attenuate muscle loss in elderly individuals during bed rest and/or in other disuse states.

scholarly journals Alcohol impairs skeletal muscle protein synthesis and mTOR signaling in a time-dependent manner following electrically stimulated muscle contraction

2014 ◽  
Vol 117 (10) ◽  
pp. 1170-1179 ◽  
Author(s):  
Jennifer L. Steiner ◽  
Charles H. Lang
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Mammalian Target Of Rapamycin ◽  
Mtor Signaling ◽  
Saline Control ◽  
Dependent Manner ◽  
Skeletal Muscle Protein

Alcohol (EtOH) decreases protein synthesis and mammalian target of rapamycin (mTOR)-mediated signaling and blunts the anabolic response to growth factors in skeletal muscle. The purpose of the current investigation was to determine whether acute EtOH intoxication antagonizes the contraction-induced increase in protein synthesis and mTOR signaling in skeletal muscle. Fasted male mice were injected intraperitoneally with 3 g/kg EtOH or saline (control), and the right hindlimb was electrically stimulated (10 sets of 6 contractions). The gastrocnemius muscle complex was collected 30 min, 4 h, or 12 h after stimulation. EtOH decreased in vivo basal protein synthesis (PS) in the nonstimulated muscle compared with time-matched Controls at 30 min, 4 h, and 12 h. In Control, but not EtOH, PS was decreased 15% after 30 min. In contrast, PS was increased in Control 4 h poststimulation but remained unchanged in EtOH. Last, stimulation increased PS 10% in Control and EtOH at 12 h, even though the absolute rate remained reduced by EtOH. The stimulation-induced increase in the phosphorylation of S6K1 Thr421/Ser424 (20–52%), S6K1 Thr389 (45–57%), and its substrate rpS6 Ser240/244 (37–72%) was blunted by EtOH at 30 min, 4 h, and 12 h. Phosphorylation of 4E-BP1 Ser65 was also attenuated by EtOH (61%) at 4 h. Conversely, phosphorylation of extracellular signal-regulated kinase Thr202/Tyr204 was increased by stimulation in Control and EtOH mice at 30 min but only in Control at 4 h. Our data indicate that acute EtOH intoxication suppresses muscle protein synthesis for at least 12 h and greatly impairs contraction-induced changes in synthesis and mTOR signaling.

Indinavir alters regulators of protein anabolism and catabolism in skeletal muscle

2005 ◽  
Vol 289 (3) ◽  
pp. E382-E390 ◽  
Author(s):  
Ly Q. Hong-Brown ◽  
Anne M. Pruznak ◽  
Robert A. Frost ◽  
Thomas C. Vary ◽  
Charles H. Lang
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Mrna Translation ◽  
Hiv Protease ◽  
Plasma Testosterone ◽  
Translational Efficiency ◽  
Model Assessment

The HIV protease inhibitor indinavir adversely impairs carbohydrate and lipid metabolism, whereas its influence on protein metabolism under in vivo conditions remains unknown. The present study tested the hypothesis that indinavir also decreases basal protein synthesis and impairs the anabolic response to insulin in skeletal muscle. Indinavir was infused intravenously for 4 h into conscious rats, at which time the homeostasis model assessment of insulin resistance was increased. Indinavir decreased muscle protein synthesis by 30%, and this reduction was due to impaired translational efficiency. To identify potential mechanisms responsible for regulating mRNA translation, several eukaryotic initiation factors (eIFs) were examined. Under basal fasted conditions, there was a redistribution of eIF4E from the active eIF4E·eIF4G complex to the inactive eIF4E·4E-BP1 complex, and this change was associated with a marked decrease in the phosphorylation of 4E-BP1 in muscle. Likewise, indinavir decreased constitutive phosphorylation of eIF4G and mTOR in muscle, but not S6K1 or the ribosomal protein S6. In contrast, the ability of a maximally stimulating dose of insulin to increase the phosphorylation of PKB, 4E-BP1, S6K1, or mTOR was not altered 20 min after intravenous injection. Indinavir increased mRNA expression of the ubiquitin ligase MuRF1, but the plasma concentration of 3-methylhistidine remained unaltered. These indinavir-induced changes were associated with a marked reduction in the plasma testosterone concentration but were independent of changes in plasma levels of IGF-I, corticosterone, TNF-α, or IL-6. In conclusion, indinavir acutely impairs basal protein synthesis and translation initiation in skeletal muscle but, in contrast to muscle glucose uptake, does not impair insulin-stimulated signaling of protein synthetic pathways.

Sign in / Sign up

Export Citation Format

Share Document