Uncoupling protein 1 inhibition by purine nucleotides is under the control of the endogenous ubiquinone redox state

2009 ◽  
Vol 424 (2) ◽  
pp. 297-306 ◽  
Author(s):  
Aleksandra Swida-Barteczka ◽  
Andrzej Woyda-Ploszczyca ◽  
Francis E. Sluse ◽  
Wieslawa Jarmuszkiewicz
Keyword(s):  
Fatty Acid ◽  
Redox State ◽  
Uncoupling Protein ◽  
Yeast Mitochondria ◽  
Purine Nucleotide ◽  
Uncoupling Protein 1 ◽  
Purine Nucleotides ◽  
State Dependent ◽  
Brown Adipose ◽  
The Relationship

We studied non-esterified fatty acid-induced uncoupling of heterologously expressed rat UCP1 (uncoupling protein 1) in yeast mitochondria, as well as UCP1 in rat BAT (brown adipose tissue) mitochondria. The proton-conductance curves and the relationship between the ubiquinone reduction level and membrane potential were determined in non-phosphorylating BAT and yeast mitochondria. The ADP/O method was applied to determine the ADP phosphorylation rate and the relationship between the ubiquinone reduction level and respiration rate in yeast mitochondria. Our studies of the membranous ubiquinone reduction level in mitochondria demonstrate that activation of UCP1 leads to a purine nucleotide-sensitive decrease in the ubiquinone redox state. Results obtained for non-phosphorylating and phosphorylating mitochondria, as the endogenous ubiquinone redox state was gradually varied by a lowering rate of the ubiquinone-reducing or ubiquinol-oxidizing pathways, indicate that the endogenous ubiquinone redox state has no effect on non-esterified fatty acid-induced UCP1 activity in the absence of GTP, and can only regulate this activity through sensitivity to inhibition by the purine nucleotide. At a given oleic acid concentration, inhibition by GTP diminishes when ubiquinone is reduced sufficiently. The ubiquinone redox state-dependent alleviation of UCP1 inhibition by the purine nucleotide was observed at a high ubiquinone reduction level, when it exceeded 85–88%.

A history of UCPI

2001 ◽  
Vol 29 (6) ◽  
pp. 751-755 ◽  
Author(s):  
D. G. Nicholls
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Uncoupling Protein ◽  
Respiratory Control ◽  
Receptor Activation ◽  
Protonmotive Force ◽  
Acid Activation ◽  
Outer Face ◽  
Purine Nucleotides ◽  
Brown Adipose

Interest in the enormous thermogenic capacity of brown adipose tissue (BAT) began in the 1960s and focused on BAT mitochondria (BATM), which when prepared by conventional techniques respired rapidly but displayed no respiratory control. Two apparently distinct treatments, fatty acid removal and purine nucleotide addition, induced respiratory control. In 1972, we found that BATM were highly permeant to halides and protons, and that albumin decreased the proton conductance while purine nucleotides decreased both. Devising techniques to quantify the proton leak in respiring mitochondria we found a nucleotide-sensitive conductance pathway whose ‘break-point’, the protonmotive force at which conductance suddenly increased, could be subtly modulated by free fatty acids. The nucleotide-binding site on the outer face of the inner membrane was characterized and identified by photoaffinity labelling as a 32 kDa ‘uncoupling protein’, now UCP1. Studies with intact brown adipocytes generated the currently accepted model, namely that fatty acids liberated by β3-adrenergic receptor activation act as both self-regulating second messengers for UCP1 and substrates for fatty acid activation and oxidation. Fatty acid concentration increases at the outset of thermogenesis, binding to UCP1 lowers the protonmotive force below that giving respiratory control and rapid thermogenesis proceeds. At the termination of receptor activation oxidation of residual fatty acid ‘recouples’ the mitochondria. The challenge with the novel UCPs is to demonstrate a similar coherent mechanism.

scholarly journals A comparative study of the inhibitory effects of purine nucleotides and carboxyatractylate on the uncoupling protein-3 and adenine nucleotide translocase.

2010 ◽  
Vol 57 (4) ◽  
Author(s):  
Natalia P Komelina ◽  
Zarif G Amerkhanov
Keyword(s):  
Fatty Acid ◽  
Adenine Nucleotide ◽  
Uncoupling Protein ◽  
Specific Inhibitor ◽  
Inhibitory Effect ◽  
Ground Squirrels ◽  
Adenine Nucleotide Translocase ◽  
Purine Nucleotides ◽  
Chloride Permeability ◽  
Brown Adipose

Uncoupling proteins (UCPs) mediate fatty acid-induced proton cycling in mitochondria, which is stimulated by superoxide and inhibited by GDP. Fatty acid anions can also be transported by adenine nucleotide translocase (ANT), thus resulting in the uncoupling of oxidative phosphorylation. In the present work, an attempt was made to distinguish between the protonophoric activity of UCP3 and that of ANT using inhibition analysis. This study was carried out using mitochondria from skeletal muscles of hibernating Yakut ground squirrel, which have a significant level of UCP3 mRNA. We found that millimolar concentrations of GDP, which is considered to be a specific inhibitor of UCPs, slightly recoupled the mitochondrial respiration and restored the membrane potential. Addition of the specific ANT inhibitor CAT (carboxyatractylate), in micromolar concentration, prior to GDP prevented its recoupling effect. Moreover, GDP and ADP exhibited a competitive kinetic behavior with respect to ANT. In brown adipose tissue, CAT did not prevent the UCP1-iduced increase in chloride permeability and the inhibitory effect of GDP, thus confirming the inability of CAT to affect UCP1. These results allow us to conclude that the recoupling effect of purine nucleotides on skeletal muscle mitochondria of hibernating ground squirrels can be explained by interaction of the nucleotides with ANT, whereas UCP3 is not involved in the process.

A mitochondrial uncoupling artifact can be caused by expression of uncoupling protein 1 in yeast

2001 ◽  
Vol 356 (3) ◽  
pp. 779-789 ◽  
Author(s):  
Jeff A. STUART ◽  
James A. HARPER ◽  
Kevin M. BRINDLE ◽  
Mika B. JEKABSONS ◽  
Martin D. BRAND
Keyword(s):  
Uncoupling Protein ◽  
Mitochondrial Protein ◽  
Physiological Property ◽  
Growth Defect ◽  
Yeast Mitochondria ◽  
Proton Conductance ◽  
Uncoupling Protein 1 ◽  
Mitochondrial Uncoupling ◽  
Mitochondrial Carrier ◽  
Brown Adipose

Uncoupling protein 1 (UCP1) from mouse was expressed in yeast and the specific (GDP-inhibitable) and artifactual (GDP-insensitive) effects on mitochondrial uncoupling were assessed. UCP1 provides a GDP-inhibitable model system to help interpret the uncoupling effects of high expression in yeast of other members of the mitochondrial carrier protein family, such as the UCP1homologues UCP2 and UCP3. Yeast expressing UCP1 at modest levels (approx. 1μg/mg of mitochondrial protein) showed no growth defect, normal rates of chemically uncoupled respiration and an increased non-phosphorylating proton conductance that was completely GDP-sensitive. The catalytic-centre activity of UCP1 in these yeast mitochondria was similar to that in mammalian brown-adipose-tissue mitochondria. However, yeast expressing UCP1 at higher levels (approx. 11μg/mg of mitochondrial protein) showed a growth defect. Their mitochondria had depressed chemically uncoupled respiration rates and an increased proton conductance that was partly GDP-insensitive. Thus, although UCP1 shows native behaviour at modest levels of expression in yeast, higher levels (or rates) of expression can lead to an uncoupling that is not a physiological property of the native protein and is therefore artifactual. This observation might be important in the interpretation of results from experiments in which the functions of UCP1homologues are verified by their ability to uncouple yeast mitochondria.

scholarly journals Supplementary prenatal copper increases plasma triiodothyronine and brown adipose tissue uncoupling protein-1 gene expression but depresses thermogenesis in newborn lambs

2020 ◽  
Vol 33 (3) ◽  
pp. 506-514
Author(s):  
Stephen B. Smith ◽  
Craig R. Sweatt ◽  
Gordon E. Carstens
Keyword(s):  
Gene Expression ◽  
Adipose Tissue ◽  
Fatty Acid ◽  
Rectal Temperature ◽  
Cold Exposure ◽  
Uncoupling Protein ◽  
Plasma Fatty Acid ◽  
Uncoupling Protein 1 ◽  
Brown Adipose ◽  
Plasma Triiodothyronine

Objective: We tested the hypothesis that increasing dietary copper (Cu) to gravid ewes would enhance brown adipose tissue (BAT) thermogenesis in their offspring.Methods: Twin-bearing ewes were assigned on d 70 of gestation to diets containing 3, 10, or 20 ppm dietary Cu (n = 8 per group). Twin lambs were assigned at birth to a cold (6°C) or warm (28°C) environmental chamber for 48 h. Blood was collected from ewes and from lambs and perirenal BAT was collected after 48 h in the environmental chambers.Results: Prenatal Cu exposure increased ewe plasma triiodothyronine (T<sub>3</sub>) and thyroxine concentration (T<sub>4</sub>) (p<0.01) but prenatal Cu exposure had no effect on lamb plasma concentrations of T<sub>3</sub>, T<sub>4</sub>, glucose, or nonesterified fatty acid concentration (p≥0.08). The high level of prenatal Cu exposure depressed 48-h rectal temperature (p = 0.03). Cold exposure decreased BAT norepinephrine (NE) and increased BAT dopamine (p≤0.01), but prenatal Cu exposure had no effect on BAT cytochrome C oxidase activity or BAT NE or dopamine (p≥0.07). However, BAT of lambs from high-Cu ewes maintained higher uncoupling protein-1 (UCP1) gene expression than BAT of lambs from low- and medium-Cu ewes following warm or cold exposure in environmental chambers (p = 0.02). Cold exposure caused near depletion of BAT lipid by 48 h (p<0.001), increased BAT cytochrome c oxidase activity (p< 0.01), and depressed plasma fatty acid concentrations (p<0.001).Conclusion: Although prenatal Cu exposure increased BAT UCP1 expression during warm and cold exposure, prenatal cold Cu exposure depressed 48-h rectal temperature. Cold exposure decreased BAT lipid content by over 80% and decreased lamb plasma fatty acid concentration by over 40%, indicating that fuel reserves for thermogenesis were nearly depleted by 48 h of cold exposure.

scholarly journals The Role of Uncoupling Protein 1 in the Metabolism and Adiposity of RIIβ-Protein Kinase A-Deficient Mice

2004 ◽  
Vol 18 (9) ◽  
pp. 2302-2311 ◽  
Author(s):  
Michael A. Nolan ◽  
Maria A. Sikorski ◽  
G. Stanley McKnight
Keyword(s):  
Adipose Tissue ◽  
Oxygen Consumption ◽  
Protein Kinase ◽  
Protein Kinase A ◽  
Uncoupling Protein ◽  
Mrna Level ◽  
Regulatory Subunit ◽  
Uncoupling Protein 1 ◽  
Brown Adipose ◽  
Kinase A

Abstract Mice lacking the RIIβ regulatory subunit of protein kinase A exhibit a 50% reduction in white adipose tissue stores compared with wild-type littermates and are resistant to diet-induced obesity. RIIβ−/− mice also have an increase in resting oxygen consumption along with a 4-fold increase in the brown adipose-specific mitochondrial uncoupling protein 1 (UCP1). In this study, we examined the basis for UCP1 induction and tested the hypothesis that the induced levels of UCP1 in RIIβ null mice are essential for the lean phenotype. The induction of UCP1 occurred at the protein but not the mRNA level and correlated with an increase in mitochondria in brown adipose tissue. Mice lacking both RIIβ and UCP1 (RIIβ−/−/Ucp1−/−) were created, and the key parameters of metabolism and body composition were studied. We discovered that RIIβ−/− mice exhibit nocturnal hyperactivity in addition to the increased oxygen consumption at rest. Disruption of UCP1 in RIIβ−/− mice reduced basal oxygen consumption but did not prevent the nocturnal hyperactivity. The double knockout animals also retained the lean phenotype of the RIIβ null mice, demonstrating that induction of UCP1 and increased resting oxygen consumption is not the cause of leanness in the RIIβ mutant mice.

scholarly journals Immunoreactivity of Canine Liposarcoma to Muscle and Brown Adipose Antigens

2017 ◽  
Vol 54 (6) ◽  
pp. 885-891 ◽  
Author(s):  
Elise E. B. LaDouceur ◽  
Sarah E. Stevens ◽  
Jason Wood ◽  
Christopher M. Reilly
Keyword(s):  
Uncoupling Protein ◽  
Smooth Muscle Actin ◽  
Antigen Expression ◽  
Muscle Actin ◽  
Uncoupling Protein 1 ◽  
Diagnostic Challenge ◽  
Brown Adipose ◽  
Well Differentiated ◽  
Relationship Of ◽  
Oil Red O

Liposarcoma, rhabdomyosarcoma, and hibernoma share some overlapping histologic and immunohistochemical features. Although immunohistochemistry (IHC) is commonly used in the diagnosis of these neoplasms, expression of muscle markers has been reported in human liposarcoma and canine hibernoma in addition to rhabdomyosarcoma. Thus, these neoplasms are a diagnostic challenge but important to distinguish because of differences in prognosis and treatment. Rhabdomyosarcoma and liposarcoma are both malignant, but rhabdomyosarcoma has a higher potential for metastasis. In contrast, hibernomas are benign with low risk of recurrence. This study investigated expression of the muscle markers desmin, myogenin, and α-smooth muscle actin (α-SMA) and the brown fat marker uncoupling protein 1 (UCP1) in 25 cases of canine liposarcoma using IHC. Oil red O histochemistry was performed to confirm the presence of lipid and the diagnosis of liposarcoma in cases that were not well-differentiated. The 25 cases included 15 well-differentiated, 5 pleomorphic, 3 myxoid, and 2 dedifferentiated subtypes of liposarcoma. By IHC, 23 of 25 expressed UCP1, 7 of 25 expressed α-SMA, 7 of 25 expressed desmin, and 3 of 25 expressed myogenin with no clear relationship of antigen expression and tumor subtype. These findings clarify the immunohistochemical profile of canine liposarcoma and suggest overlap in the expression of several muscle antigens and UCP1 between liposarcoma, hibernoma, and rhabdomyosarcoma.

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