Mitochondrial Protein Content and in Vivo Synthesis Rates in Skeletal Muscle from Critically Ill Rats

1996 ◽  
Vol 91 (4) ◽  
pp. 475-481 ◽  
Author(s):  
Olav E. Rooyackers ◽  
Alexande R H. Kersten ◽  
Anton J. M. Wagenmakers

1. Recently we reported decreased activities of two mitochondrial marker enzymes (citrate synthase and cytochrome c oxidase) in skeletal muscle from a rat model of critical illness (zymosan injection). In the present study we investigated (i) whether these decreases in enzyme activity reflect a reduction in mitochondrial content and (ii) whether this potential reduction in mitochondrial content was the result of decreased mitochondrial protein synthesis rates. 2. Mitochondrial protein content was calculated from the activities of cytochrome c oxidase in whole-muscle homogenates and purified mitochondria. Synthesis rates of mitochondrial protein in vivo were studied by measuring the incorporation of [3H]phenylalanine into mitochondrial protein using the flooding dose technique. 3. Mitochondrial protein content was reduced to 54% of that measured in the pair-fed rats and to 71% of that measured in control rats fed ad libitum 2 days after the zymosan treatment The decreased mitochondrial protein content observed 2 days after zymosan challenge was preceded by a reduced rate of synthesis of mitochondrial protein 16 h after treatment. Both changes were of greater magnitude than the general muscle wasting and the decreased rate of synthesis of mixed protein observed in the zymosan-treated rats. 4. We conclude that the acute phase of critical illness in zymosan-treated rats is characterized by a substantial reduction in muscle mitochondria that is at least in part caused by a decreased rate of synthesis of mitochondrial protein. This derangement in mitochondrial protein metabolism may be related to the impaired muscle function observed during and after critical illness.

2021 ◽  
Vol 249 (2) ◽  
pp. 113-124
Author(s):  
Stephen P Ashcroft ◽  
Gareth Fletcher ◽  
Ashleigh M Philp ◽  
Carl Jenkinson ◽  
Shatarupa Das ◽  
...  

Vitamin D deficiency is associated with symptoms of skeletal muscle myopathy including muscle weakness and fatigue. Recently, vitamin D-related metabolites have been linked to the maintenance of mitochondrial function within skeletal muscle. However, current evidence is limited to in vitro models and the effects of diet-induced vitamin D deficiency upon skeletal muscle mitochondrial function in vivo have received little attention. In order to examine the role of vitamin D in the maintenance of mitochondrial function in vivo, we utilised an established model of diet-induced vitamin D deficiency in C57BL/6J mice. Mice were either fed a control diet (2200 IU/kg i.e. vitamin D replete) or a vitamin D-deplete (0 IU/kg) diet for periods of 1, 2 and 3 months. Gastrocnemius muscle mitochondrial function and ADP sensitivity were assessed via high-resolution respirometry and mitochondrial protein content via immunoblotting. As a result of 3 months of diet-induced vitamin D deficiency, respiration supported via complex I + II (CI + IIP) and the electron transport chain (ETC) were 35 and 37% lower when compared to vitamin D-replete mice (P < 0.05). Despite functional alterations, citrate synthase activity, AMPK phosphorylation, mitofilin, OPA1 and ETC subunit protein content remained unchanged in response to dietary intervention (P > 0.05). In conclusion, we report that 3 months of diet-induced vitamin D deficiency reduced skeletal muscle mitochondrial respiration in C57BL/6J mice. Our data, when combined with previous in vitro observations, suggest that vitamin D-mediated regulation of mitochondrial function may underlie the exacerbated muscle fatigue and performance deficits observed during vitamin D deficiency.


1994 ◽  
Vol 77 (4) ◽  
pp. 1885-1889 ◽  
Author(s):  
R. Theriault ◽  
G. Theriault ◽  
J. A. Simoneau

The purpose of the study was to verify the influence of several weeks of chronic low-frequency electrical stimulation (LFES) on the metabolic profile and functional capacity of human skeletal muscle. Knee extensor muscles (KEM) of eight subjects were electrically stimulated at 8 Hz for 8 h/day and 6 days/wk. Vastus lateralis muscle samples were taken before, after 4 wk, and after 8 wk of LFES, and activities of anaerobic (creatine kinase, phosphofructokinase, glyceraldehyde-3-phosphate dehydrogenase) and aerobic-oxidative (citrate synthase, 3-hydroxyacyl-CoA dehydrogenase, cytochrome-c oxidase) enzyme markers were determined. KEM dynamic performance was also assessed before, after 4 wk, and after 8 wk of LFES. Activity levels of anaerobic enzymes were not altered, whereas the activity levels of citrate synthase (29%),3-hydroxyacyl-CoA dehydrogenase (22%), and cytochrome-c oxidase (25%) were significantly increased after 4 wk of LFES but were not further increased after 4 additional wk of LFES. KEM performance was also improved (P < 0.05) but leveled off after 4 wk of LFES. Although significant changes were observed, the results of the present study suggest that the muscle characteristics investigated in the current study have a limited capacity of adaptation in response to this form of chronic LFES.


1989 ◽  
Vol 257 (3) ◽  
pp. 665-671 ◽  
Author(s):  
L Casteilla ◽  
O Champigny ◽  
F Bouillaud ◽  
J Robelin ◽  
D Ricquier

Samples of adipose tissue were obtained from different sites in bovine and ovine foetuses and newborns. RNA was isolated and analysed using bovine cDNA and ovine genomic probe for uncoupling protein (UCP), cDNA for subunits III and IV of cytochrome c oxidase and cDNA for ADP/ATP carrier. UCP mRNA was characterized for the first time in foetal bovine and ovine adipose tissue. It appeared later than mRNA of cytochrome c oxidase subunit III, and increased dramatically at birth (10-fold). ADP/ATP carrier mRNA was expressed at a lower level but also increased 10-fold at birth. It was demonstrated that UCP mRNA reached its highest level at birth in all bovine adipose tissues studied, except subcutaneous tissue. It disappeared quickly afterwards, being no longer detectable two days after birth. Similar variations were observed in newborn lambs. ADP/ATP carrier mRNA showed the same pattern of expression as UCP mRNA; although it was still lightly expressed two days after birth, it disappeared soon afterwards. Only mRNAs for cytochrome c oxidase subunits III and IV remained at the same level during the first postnatal week. On the basis of these data and of observations reported in the literature a sequence of events for the development of brown adipose cells in vivo is proposed. Soon after birth the perirenal adipose tissue of ruminants, which still contains mitochondria of typical brown adipose tissue morphology and high levels of cytochrome c oxidase mRNA, lacks UCP mRNA. Can it still be considered as brown fat? Ruminant species appear to be attractive models to study both the differentiation of brown adipose tissue and its possible conversion to white fat in large animals.


1990 ◽  
Vol 10 (9) ◽  
pp. 4984-4986 ◽  
Author(s):  
L K Dircks ◽  
R O Poyton

Subunit Va of Saccharomyces cerevisiae cytochrome c oxidase is a nucleus-encoded mitochondrial protein that is derived from a precursor with a 20-residue leader peptide. We previously reported that this leader peptide is required for import of subunit Va into mitochondria in vivo (S. M. Glaser, C. E. Trueblood, L. K. Dircks, R. O. Poyton, and M. G. Cumsky, J. Cell. Biochem. 36:275-278, 1988). Here we show that overproduction of a leaderless form of subunit Va circumvents the leader peptide requirement for import into mitochondria in vivo.


2009 ◽  
Vol 297 (6) ◽  
pp. R1761-R1768 ◽  
Author(s):  
Bruce C. Frier ◽  
Deon B. Williams ◽  
David C. Wright

Adipose tissue is recognized as a key player in the regulation of whole body metabolism. Apelin, is a recently identified adipokine that when given to mice results in increases in skeletal muscle uncoupling protein 3 (UCP3) content. Similarly, acute apelin treatment has been shown to increase the activity of 5′-AMP-activated protein kinase (AMPK), a reputed mediator of skeletal muscle mitochondrial biogenesis. Given these findings, we sought to determine the effects of apelin on skeletal muscle mitochondrial content. Male Wistar rats were given daily intraperitoneal injections of apelin-13 (100 nmol/kg) for 2 wk. We made the novel observation that the activities of citrate synthase, cytochrome c oxidase, and β-hydroxyacyl coA dehydrogenase (βHAD) were increased in triceps but not heart and soleus muscles from apelin-treated rats. When confirming these results we found that both nuclear and mitochondrial-encoded subunits of the respiratory chain were increased in triceps from apelin-treated rats. Similarly, apelin treatment increased the protein content of components of the mitochondrial import and assembly pathway. The increases in mitochondrial marker proteins were associated with increases in proliferator-activated receptor-γ coactivator-1 (PGC-1β) but not PGC-1α or Pgc-1-related co-activator (PRC) mRNA expression. Chronic and acute apelin treatment did not increase the protein content and/or phosphorylation status of AMPK and its downstream substrate acetyl-CoA carboxylase. These findings are the first to demonstrate that apelin treatment can induce skeletal muscle mitochondrial content. Given the lack of an effect of apelin on AMPK signaling and PGC-1α mRNA expression, these results suggest that apelin increases skeletal muscle mitochondrial content through a mechanism that is distinct from that of more robust physiological stressors.


2015 ◽  
Vol 40 (10) ◽  
pp. 1086-1088 ◽  
Author(s):  
Eric A.F. Herbst ◽  
Arend Bonen ◽  
Graham P. Holloway

Changes in nuclear receptor interacting protein 140 (RIP140) influences mitochondrial content in skeletal muscle; however, the translation of these findings to the brain has not been investigated. The present study examined the impact of overexpressing and ablating RIP140 on mitochondrial content in muscle and the cortex through examining mRNA, mtDNA, and mitochondrial protein content. Our results show that changes in RIP140 expression significantly alters markers of mitochondrial content in skeletal muscle but not the brain.


1990 ◽  
Vol 10 (9) ◽  
pp. 4984-4986
Author(s):  
L K Dircks ◽  
R O Poyton

Subunit Va of Saccharomyces cerevisiae cytochrome c oxidase is a nucleus-encoded mitochondrial protein that is derived from a precursor with a 20-residue leader peptide. We previously reported that this leader peptide is required for import of subunit Va into mitochondria in vivo (S. M. Glaser, C. E. Trueblood, L. K. Dircks, R. O. Poyton, and M. G. Cumsky, J. Cell. Biochem. 36:275-278, 1988). Here we show that overproduction of a leaderless form of subunit Va circumvents the leader peptide requirement for import into mitochondria in vivo.


2011 ◽  
Vol 301 (4) ◽  
pp. R864-R872 ◽  
Author(s):  
Andrew Philp ◽  
Micah Y. Belew ◽  
Ashleigh Evans ◽  
Don Pham ◽  
Itwinder Sivia ◽  
...  

The transcriptional coactivator PGC-1α is a potent regulator of skeletal muscle metabolism. Less is known about the structurally similar PGC-1α-related coactivator (PRC) that is enriched in myoblasts and adult skeletal muscle. The present study was designed to determine the effect of PRC on the metabolic profile of C2C12 myotubes. Overexpression of full-length PRC increased PRC gene expression by 2.7 ± 0.3-fold and protein content by 108 ± 5.3%. This modest elevation in PRC resulted in an increased rate of myoblast proliferation (61.5 ± 2.7%) and resulted in myotubes characterized by increased MyoD (18.2 ± 0.52%) and myosin heavy chain (15.4 ± 3.13%) protein. PRC overexpressing myotubes showed increases in mRNA for some—COX4 (2.6 ± 0.18-fold), ATP5B (2.7 ± 0.34-fold) cytochrome c (5.1 ± 0.68-fold)—but not all, MTCO1 (0.61 ± 0.18-fold) and HAD (0.98 ± 0.36-fold) mitochondrial genes, as well as a significant increase in cytochrome– c (28.7 ± 7.02%) protein content. The enzyme activity of the electron transport chain (ETC) complex IV (3.7 ± 0.01-fold) and citrate synthase (2.1 ± 0.14-fold) was increased by PRC, as was the mtDNA:nucDNA ratio (11 ± 0.3%). PRC increased cellular respiration (142%), basal (197%) and insulin-stimulated (253%) glucose uptake, as well as palmitate uptake (28.6 ± 3.31%) and oxidation (31.1 ± 2.17%). Associated with these changes in function, PRC overexpression increased GLUT4 mRNA (4.5 ± 0.22-fold) and protein (13.8 ± 2.08%) and CPT1 protein (28.9 ± 4.23%). Electrical stimulation of C2C12 myotubes resulted in a transient increase in PRC mRNA that was smaller (2.1 ± 0.3-fold vs. 4.4 ± 0.23-fold) and occurred earlier (3 h vs. 6 h) than PGC-1α. Collectively, our data show that PRC promotes skeletal muscle myogenesis and metabolism in vitro, thus identifying PRC as a functional skeletal muscle coactivator capable of regulating mitochondrial substrate utilization and respiration.


1989 ◽  
Vol 257 (5) ◽  
pp. C936-C939 ◽  
Author(s):  
P. R. Morrison ◽  
R. B. Biggs ◽  
F. W. Booth

The purpose of the study was to determine whether daily running durations that were 7-14% of the durations employed in the chronic stimulation protocols (consisting of 24 h of daily indirect electrical stimulation of skeletal muscles) still resulted in increases in a mitochondrial protein mRNA. Adult female rats were run 100 min/day on motor-driven treadmills for 2 wk. Documentation that rats underwent the stated training program was obtained by a 30-41% increase in citrate synthase activity in hindlimb muscles after 2 wk of the training. Cytochrome c mRNA was increased 17-56% in hindlimb muscles after the 2-wk training program. Thus shorter durations of exercise (100 min/day rather than 24 h/day) can increase cytochrome c mRNA. alpha-Actin mRNA increased 61-62% in fast-twitch muscles in the hindlimbs of the same rats that underwent the 2 wk of run training but did not increase in the predominantly slow-twitch soleus muscle. The increase in alpha-actin mRNA was unexpected, since it is well known that this type of physical exercise does not increase the size of fast-twitch skeletal muscle.


Author(s):  
Stephan Gielen ◽  
Volker Adams ◽  
Axel Linke ◽  
Sandra Erbs ◽  
Sven Möbius-Winkler ◽  
...  

Background Chronic heart failure (CHF) is accompanied by an inflammatory activation which occurs both systemically and in the skeletal muscle. Exercise training has been shown to reduce the local expression of cytokines and inducible nitric oxide synthase (iNOS) in muscle biopsies of CHF patients. INOS-derived NO can inhibit oxidative phosphorylation and contribute to skeletal muscle dysfunction in CHF. Design To investigate the correlation between changes in local iNOS expression associated with regular exercise and changes in aerobic enzyme activities in the skeletal muscle of patients with CHF. Twenty male CHF patients [ejection fraction 25% (SE 2), age 54 (SE 2) years] were randomized to a training ( n = 10) or a control group (C, n = 10). Methods At baseline and after 6 months skeletal muscle iNOS expression was measured by real-time polymerase chain reaction. INOS protein and protein nitrosylation were assessed by immunohistochemistry. Cytochrome c oxidase (COX) activity was quantified electrochemically using the Clark oxygen electrode. Results Exercise training led to a 27% increase in cytochrome c oxidase activity [from 21.8 (SE 3.2) to 27.7 (SE 3.5) nmol O2/mg per min, P=0.02 versus baseline]. Changes in iNOS expression and iNOS protein content were inversely correlated with changes in COX-activity ( r= −0.60, P=0.01; r= −0.71, P<0.001). Conclusions The inverse correlation between iNOS expression/iNOS protein content and COX-activity indicates that local anti-inflammatory effects may contribute to improved muscular oxidative metabolism.


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