scholarly journals Absence of uncoupling protein-3 leads to greater activation of an adenine nucleotide translocase-mediated proton conductance in skeletal muscle mitochondria from calorie restricted mice

2010 ◽  
Vol 1797 (8) ◽  
pp. 1389-1397 ◽  
Author(s):  
Lisa Bevilacqua ◽  
Erin L. Seifert ◽  
Carmen Estey ◽  
Martin F. Gerrits ◽  
Mary-Ellen Harper
Keyword(s):  
Skeletal Muscle ◽  
Adenine Nucleotide ◽  
Uncoupling Protein ◽  
Adenine Nucleotide Translocase ◽  
Proton Conductance ◽  
Muscle Mitochondria ◽  
Skeletal Muscle Mitochondria ◽  
Uncoupling Protein 3

scholarly journals Energization-dependent endogenous activation of proton conductance in skeletal muscle mitochondria

2008 ◽  
Vol 412 (1) ◽  
pp. 131-139 ◽  
Author(s):  
Nadeene Parker ◽  
Charles Affourtit ◽  
Antonio Vidal-Puig ◽  
Martin D. Brand
Keyword(s):  
Skeletal Muscle ◽  
Knockout Mice ◽  
Adenine Nucleotide ◽  
Specific Inhibitor ◽  
Adenine Nucleotide Translocase ◽  
Protonmotive Force ◽  
Proton Conductance ◽  
Wild Type ◽  
Muscle Mitochondria ◽  
Skeletal Muscle Mitochondria

Leak of protons into the mitochondrial matrix during substrate oxidation partially uncouples electron transport from phosphorylation of ADP, but the functions and source of basal and inducible proton leak in vivo remain controversial. In the present study we describe an endogenous activation of proton conductance in mitochondria isolated from rat and mouse skeletal muscle following addition of respiratory substrate. This endogenous activation increased with time, required a high membrane potential and was diminished by high concentrations of serum albumin. Inhibition of this endogenous activation by GDP [classically considered specific for UCPs (uncoupling proteins)], carboxyatractylate and bongkrekate (considered specific for the adenine nucleotide translocase) was examined in skeletal muscle mitochondria from wild-type and Ucp3-knockout mice. Proton conductance through endogenously activated UCP3 was calculated as the difference in leak between mitochondria from wild-type and Ucp3-knockout mice, and was found to be inhibited by carboxyatractylate and bongkrekate, but not GDP. Proton conductance in mitochondria from Ucp3-knockout mice was strongly inhibited by carboxyatractylate, bongkrekate and partially by GDP. We conclude the following: (i) at high protonmotive force, an endogenously generated activator stimulates proton conductance catalysed partly by UCP3 and partly by the adenine nucleotide translocase; (ii) GDP is not a specific inhibitor of UCP3, but also inhibits proton translocation by the adenine nucleotide translocase; and (iii) the inhibition of UCP3 by carboxyatractylate and bongkrekate is likely to be indirect, acting through the adenine nucleotide translocase.

scholarly journals AMP decreases the efficiency of skeletal-muscle mitochondria

2000 ◽  
Vol 351 (2) ◽  
pp. 307-311 ◽  
Author(s):  
Susana CADENAS ◽  
Julie A. BUCKINGHAM ◽  
Julie ST-PIERRE ◽  
Keith DICKINSON ◽  
Robert B. JONES ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Metabolic Rate ◽  
Rana Temporaria ◽  
Adenine Nucleotide ◽  
Uncoupling Protein ◽  
Metabolic Efficiency ◽  
Proton Conductance ◽  
Muscle Mitochondria ◽  
Rat Muscle ◽  
Skeletal Muscle Mitochondria

Mitochondrial proton leak in rat muscle is responsible for approx. 15% of the standard metabolic rate, so its modulation could be important in regulating metabolic efficiency. We report in the present paper that physiological concentrations of AMP (K0.5 = 80µM) increase the resting respiration rate and double the proton conductance of rat skeletal-muscle mitochondria. This effect is specific for AMP. AMP also doubles proton conductance in skeletal-muscle mitochondria from an ectotherm (the frog Rana temporaria), suggesting that AMP activation is not primarily for thermogenesis. AMP activation in rat muscle mitochondria is unchanged when uncoupling protein-3 is doubled by starvation, indicating that this protein is not involved in the AMP effect. AMP activation is, however, abolished by inhibitors and substrates of the adenine nucleotide translocase (ANT), suggesting that this carrier (possibly the ANT1 isoform) mediates AMP activation. AMP activation of ANT could be important for physiological regulation of metabolic rate.

scholarly journals The Basal Proton Conductance of Skeletal Muscle Mitochondria from Transgenic Mice Overexpressing or Lacking Uncoupling Protein-3

2001 ◽  
Vol 277 (4) ◽  
pp. 2773-2778 ◽  
Author(s):  
Susana Cadenas ◽  
Karim S. Echtay ◽  
James A. Harper ◽  
Mika B. Jekabsons ◽  
Julie A. Buckingham ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Transgenic Mice ◽  
Uncoupling Protein ◽  
Proton Conductance ◽  
Muscle Mitochondria ◽  
Skeletal Muscle Mitochondria ◽  
Uncoupling Protein 3

Artifactual uncoupling by uncoupling protein 3 in yeast mitochondria at the concentrations found in mouse and rat skeletal-muscle mitochondria

2001 ◽  
Vol 361 (1) ◽  
pp. 49-56 ◽  
Author(s):  
James A. HARPER ◽  
Jeff A. STUART ◽  
Mika B. JEKABSONS ◽  
Damien ROUSSEL ◽  
Kevin M. BRINDLE ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Adipose Tissue ◽  
Uncoupling Protein ◽  
Mitochondrial Protein ◽  
Yeast Mitochondria ◽  
Rat Skeletal Muscle ◽  
Muscle Mitochondria ◽  
Skeletal Muscle Mitochondria ◽  
Uncoupling Protein 3 ◽  
Brown Adipose

Western blots detected uncoupling protein 3 (UCP3) in skeletal-muscle mitochondria from wild-type but not UCP3 knock-out mice. Calibration with purified recombinant UCP3 showed that mouse and rat skeletal muscle contained 0.14μg of UCP3/mg of mitochondrial protein. This very low UCP3 content is 200–700-fold less than the concentration of UCP1 in brown-adipose-tissue mitochondria from warm-adapted hamster (24–84μg of UCP1/mg of mitochondrial protein). UCP3 was present in brown-adipose-tissue mitochondria from warm-adapted rats but was undetectable in rat heart mitochondria. We expressed human UCP3 in yeast mitochondria at levels similar to, double and 7-fold those found in rodent skeletal-muscle mitochondria. Yeast mitochondria containing UCP3 were more uncoupled than empty-vector controls, particularly at concentrations that were 7-fold physiological. However, uncoupling by UCP3 was not stimulated by the known activators palmitate and superoxide; neither were they inhibited by GDP, suggesting that the observed uncoupling was a property of non-native protein. As a control, UCP1 was expressed in yeast mitochondria at similar concentrations to that of UCP3 and at up to 50% of the physiological level of UCP1. Low levels of UCP1 gave palmitate-dependent and GDP-sensitive proton conductance but higher levels of UCP1 caused an additional GDP-insensitive uncoupling artifact. We conclude that the uncoupling of yeast mitochondria by high levels of UCP3 expression is entirely an artifact and provides no evidence for any native uncoupling activity of the protein.

scholarly journals Oxidative damage and phospholipid fatty acyl composition in skeletal muscle mitochondria from mice underexpressing or overexpressing uncoupling protein 3

2002 ◽  
Vol 368 (2) ◽  
pp. 597-603 ◽  
Author(s):  
Martin D. BRAND ◽  
Reinald PAMPLONA ◽  
Manuel PORTERO-OTÍN ◽  
Jesús R. REQUENA ◽  
Stephen J. ROEBUCK ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Oxidative Damage ◽  
Uncoupling Protein ◽  
Fatty Acyl ◽  
Proton Conductance ◽  
Acyl Composition ◽  
Skeletal Muscle Mitochondria ◽  
Fatty Acyl Composition ◽  
Uncoupling Protein 3

Five markers of different kinds of oxidative damage to proteins [glutamic semialdehyde, aminoadipic semialdehyde, N∊-(carboxymethyl)lysine, N∊-(carboxyethyl)lysine and N∊-(malondialdehyde)lysine] and phospholipid fatty acyl composition were identified and measured in skeletal muscle mitochondria isolated from mice genetically engineered to underexpress or overexpress uncoupling protein 3 (UCP3). Mitochondria from UCP3-underexpressing mice had significantly higher levels of oxidative damage than wild-type controls, suggesting that UCP3 functions in vivo as part of the antioxidant defences of the cell, but mitochondria from UCP3-overexpressing mice had unaltered oxidative damage, suggesting that mild uncoupling in vivo beyond the normal basal uncoupling provides little protection against oxidative stress. Mitochondria from UCP3-underexpressing mice showed little change, but mitochondria from UCP3-overexpressing mice showed marked changes in mitochondrial phospholipid fatty acyl composition. These changes were very similar to those previously found to correlate with basal proton conductance in mitochondria from a range of species and treatments, suggesting that high protein expression, or some secondary result of uncoupling, may cause the observed correlation between basal proton conductance and phospholipid fatty acyl composition.

Aging skeletal muscle mitochondria in the rat: decreased uncoupling protein-3 content

2001 ◽  
Vol 281 (5) ◽  
pp. E1054-E1062 ◽  
Author(s):  
Janos Kerner ◽  
Peter J. Turkaly ◽  
Paul E. Minkler ◽  
Charles L. Hoppel
Keyword(s):  
Skeletal Muscle ◽  
Aerobic Capacity ◽  
Citrate Synthase ◽  
Uncoupling Protein ◽  
Carnitine Palmitoyltransferase ◽  
Lower State ◽  
Adult Rats ◽  
Muscle Mitochondria ◽  
Skeletal Muscle Mitochondria ◽  
Uncoupling Protein 3

The goal of the present study was to discern the cellular mechanism(s) that contributes to the age-associated decrease in skeletal muscle aerobic capacity. Skeletal muscle mitochondrial content, a parameter of oxidative capacity, was significantly lower (25 and 20% calculated on the basis of citrate synthase and succinate dehydrogenase activities, respectively) in 24-mo-old Fischer 344 rats compared with 6-mo-old adult rats. Mitochondria isolated from skeletal muscle of both age groups had identical state 3 (ADP-stimulated) and ADP-stimulated maximal respiratory rates and phosphorylation potential (ADP-to-O ratios) with both nonlipid and lipid substrates. In contrast, mitochondria from 24-mo-old rats displayed significantly lower state 4 (ADP-limited) respiratory rates and, consequently, higher respiratory control ratios. Consistent with the tighter coupling, there was a 68% reduction in uncoupling protein-3 (UCP-3) abundance in mitochondria from elderly compared with adult rats. Congruent with the respiratory studies, there was no age-associated decrease in carnitine palmitoyltransferase I and carnitine palmitoyltransferase II activities in isolated skeletal muscle mitochondria. However, there was a small, significant decrease in tissue total carnitine content. It is concluded that the in vivo observed decrease in skeletal muscle aerobic capacity with advanced age is a consequence of the decreased mitochondrial density. On the basis of the dramatic reduction of UCP-3 content associated with decreased state 4 respiration of skeletal muscle mitochondria from elderly rats, we propose that an increased free radical production might contribute to the metabolic compromise in aging.

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