scholarly journals Cysteine residues are not essential for uncoupling protein function

1993 ◽  
Vol 296 (3) ◽  
pp. 693-700 ◽  
Author(s):  
I Arechaga ◽  
S Raimbault ◽  
S Prieto ◽  
C Levi-Meyrueis ◽  
P Zaragoza ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Protein Function ◽  
Chloride Transport ◽  
Uncoupling Protein ◽  
Atp Synthesis ◽  
Site Directed Mutagenesis ◽  
Metabolic Energy ◽  
Cysteine Residues ◽  
Brown Adipose ◽  
In The Wild

The uncoupling protein (UCP) of brown adipose tissue is a regulated proton carrier which allows uncoupling of mitochondrial respiration from ATP synthesis and, therefore, dissipation of metabolic energy as heat. In this article we demonstrate that, when UCP is expressed in Saccharomyces cerevisiae, it retains all its functional properties: proton and chloride transport, high-affinity binding of nucleotides and regulation of proton conductance by nucleotides and fatty acids. Site-directed mutagenesis demonstrates that sequential replacement by serine of cysteine residues in the UCP does not affect either its uncoupling activity or its regulation by nucleotides and fatty acids, and therefore establishes that none of the seven cysteine residues present in the wild-type UCP is critical for its activity. These data indicate that transport models involving essential thiol groups can be discounted and that chemical modification data require critical re-evaluation.

scholarly journals Brown adipose tissue mitochondria: modulation by GDP and fatty acids depends on the respiratory substrates

2011 ◽  
Vol 32 (1) ◽  
pp. 53-59 ◽  
Author(s):  
Leopoldo De Meis ◽  
Luisa A. Ketzer ◽  
Juliana Camacho-Pereira ◽  
Antonio Galina
Keyword(s):  
Fatty Acids ◽  
Adipose Tissue ◽  
Membrane Potential ◽  
Brown Adipose Tissue ◽  
Heat Production ◽  
Uncoupling Protein ◽  
Atp Synthesis ◽  
Brown Adipocytes ◽  
Bat Mitochondria ◽  
Brown Adipose

The UCP1 [first UCP (uncoupling protein)] that is found in the mitochondria of brown adipocytes [BAT (brown adipose tissue)] regulates the heat production, a process linked to non-shivering thermogenesis. The activity of UCP1 is modulated by GDP and fatty acids. In this report, we demonstrate that respiration and heat released by BAT mitochondria vary depending on the respiratory substrate utilized and the coupling state of the mitochondria. It has already been established that, in the presence of pyruvate/malate, BAT mitochondria are coupled by faf-BSA (fatty-acid-free BSA) and GDP, leading to an increase in ATP synthesis and mitochondrial membrane potential along with simultaneous decreases in both the rates of respiration and heat production. Oleate restores the uncoupled state, inhibiting ATP synthesis and increasing the rates of both respiration and heat production. We now show that in the presence of succinate: (i) the rates of uncoupled mitochondria respiration and heat production are five times slower than in the presence of pyruvate/malate; (ii) faf-BSA and GDP accelerate heat and respiration as a result and, in coupled mitochondria, these two rates are accelerated compared with pyruvate/malate; (iii) in spite of the differences in respiration and heat production noted with the two substrates, the membrane potential and the ATP synthesized were the same; and (iv) oleate promoted a decrease in heat production and respiration in coupled mitochondria, an effect different from that observed using pyruvate/malate. These effects are not related to the production of ROS (reactive oxygen species). We suggest that succinate could stimulate a new route to heat production in BAT mitochondria.

scholarly journals Inhibition of Uncoupling Protein Expression during Lactation: Role of Leptin

Endocrinology ◽  
2004 ◽  
Vol 145 (2) ◽  
pp. 830-838 ◽  
Author(s):  
Xiao Qiu Xiao ◽  
Kevin L. Grove ◽  
Bernadette E. Grayson ◽  
M. Susan Smith
Keyword(s):  
Skeletal Muscle ◽  
Protein Expression ◽  
Mrna Expression ◽  
Uncoupling Protein ◽  
Atp Synthesis ◽  
Negative Energy ◽  
Down Regulation ◽  
Serum Free Fatty Acid ◽  
Serum Leptin ◽  
Brown Adipose

Abstract Uncoupling proteins (UCPs) are mitochondrial proteins that play a role in regulation of energy expenditure by uncoupling respiration from ATP synthesis. Lactation is a physiological condition characterized by negative energy balance due to the loss of energy sources to the production of milk. The objective of the current study was to investigate whether UCP mRNA and protein expressions were altered during lactation compared with those after 48 h of fasting. Lactation significantly reduced serum leptin levels, and removal of pups for 48 h increased serum leptin to higher levels than those observed in control rats. Compared with control rats, mRNA expression of UCP1 and UCP3 in brown adipose tissue (BAT) was dramatically reduced during lactation and fasting. The reduction in mRNAs was reflected by a lowered UCP1 protein level, and to some extent, UCP3 protein. Treatment of lactating rats with exogenous leptin (3 mg/kg) or removal of pups for 48 h completely reversed the down-regulation of UCP1 and UCP3 mRNA expression in BAT, and pup removal led to a recovery of protein expression. In contrast to BAT, UCP3 expression in skeletal muscle was increased in fasted rats and decreased during lactation. Similar changes were observed in serum free fatty acid levels. These changes are consistent with the idea that the utilization of free fatty acids as a fuel source is spared during lactation. As in BAT, leptin treatment and removal of pups were able to restore changes in mRNA expression of UCP3 in skeletal muscle during lactation. The present results suggest that the inhibition of leptin secretion during lactation is involved in the down-regulation of UCP expression in BAT and skeletal muscle, which, in turn, is responsible for the decrease in metabolic fuel oxidation and thermogenesis.

scholarly journals Fatty Acids Rescue the Thermogenic Function of Sympathetically Denervated Brown Fat

Biomolecules ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1428
Author(s):  
Qiang Cao ◽  
Shirong Wang ◽  
Huan Wang ◽  
Xin Cui ◽  
Jia Jing ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Body Temperature ◽  
Cold Exposure ◽  
Uncoupling Protein ◽  
Sympathetic Innervation ◽  
Brown Fat ◽  
Key Factors ◽  
Uncoupling Protein 1 ◽  
Physiological Factors ◽  
Brown Adipose

Sympathetic nervous system (SNS) innervation into brown adipose tissue (BAT) has been viewed as an impetus for brown fat thermogenesis. However, we surprisingly discovered that BAT SNS innervation is dispensable for mice to maintain proper body temperature during a prolonged cold exposure. Here we aimed to uncover the physiological factors compensating for maintaining brown fat thermogenesis in the absence of BAT innervation. After an initial decline of body temperature during cold exposure, mice with SNS surgical denervation in interscapular BAT gradually recovered their temperature comparable to that of sham-operated mice. The surgically denervated BAT also maintained a sizable uncoupling protein 1 (UCP1) protein along with basal norepinephrine (NE) at a similar level to that of sham controls, which were associated with increased circulating NE. Furthermore, the denervated mice exhibited increased free fatty acid levels in circulation. Indeed, surgical denervation of mice with CGI-58 deletion in adipocytes, a model lacking lipolytic capacity to release fatty acids from WAT, dramatically reduced BAT UCP1 protein and rendered the mice susceptible to cold. We conclude that circulating fatty acids and NE may serve as key factors for maintaining BAT thermogenic function and body temperature in the absence of BAT sympathetic innervation.

scholarly journals Mutation yellow in agouti loci prevents age-related increase of skeletal muscle genes regulating free fatty acids oxidation

2018 ◽  
Vol 22 (2) ◽  
pp. 265-272 ◽  
Author(s):  
Y. V. Piskunova ◽  
A. Y. Kazantceva ◽  
A. V. Baklanov ◽  
N. M. Bazhan
Keyword(s):  
Skeletal Muscle ◽  
Fatty Acids ◽  
Adipose Tissue ◽  
Free Fatty Acids ◽  
Glucose Uptake ◽  
White Adipose Tissue ◽  
Uncoupling Protein ◽  
Age Related ◽  
Brown Adipose ◽  
Ay Mice

The lethal yellow mutation in agouti loci (Ay mutation) reduces the activity of melanocortin (MC) receptors and causes hyperphagia, obesity and type two diabetes mellitus in aging mice (Ay mice). It is unknown if changes in distinct elements of the metabolic system such as white adipose tissue (WAT) and brown adipose tissue (BAT), and skeletal muscle will manifest before the development of obesity. The aim of this work was to measure the relative gene expression of key proteins that regulate carbohydrate-lipid metabolism in WAT, BAT and skeletal muscle in Ay mice before the development of obesity. C57Bl/6J mice bearing a dominant autosomal mutation Ay (Ay /a mice) and mice of the standard genotype (a/a mice, control) have been studied in three age groups: 10, 15 and 30 weeks. The relative mRNA level of genes was measured by real-time PCR in skeletal muscles (uncoupling protein 3 (Ucp3) and carnitine palmitoyl transferase 1b (Cpt1b) (free fatty acids oxidation), solute carrier family 2 (facilitated glucose transporter), member 4 (Slc2a4) (glucose uptake)), in WAT lipoprotein lipase (Lpl) (triglyceride deposition), hormone-sensitive lipase (Lipe) (lipid mobilization), and Slc2a4 (glucose uptake)), and in BAT: uncoupling protein 1 (Ucp1) (energy expenditure). The expression of Cpt1b was reduced in young Ay mice (10 weeks), there was no transient peak of transcription of Cpt1b, Ucp3 in skeletal muscle tissue and Lipe, Slc2a4 in WAT in early adult Ay mice (15 weeks), which was noted in а/а mice. Reduction of the transcriptional activity of the studied genes in skeletal muscle and white adipose tissue can initiate the development of melanocortin obesity in Ay mice.

scholarly journals Mitochondrial uncoupling protein may participate in futile cycling of pyruvate and other monocarboxylates

1998 ◽  
Vol 275 (2) ◽  
pp. C496-C504 ◽  
Author(s):  
Petr Jezek ◽  
Jirí Borecky
Keyword(s):  
Fatty Acids ◽  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Uncoupling Protein ◽  
Specific Inhibitor ◽  
Physiological Role ◽  
Mitochondrial Uncoupling ◽  
Mitochondrial Uncoupling Protein ◽  
Brown Adipose ◽  
Futile Cycling

The physiological role of monocarboxylate transport in brown adipose tissue mitochondria has been reevaluated. We studied pyruvate, α-ketoisovalerate, α-ketoisocaproate, and phenylpyruvate uniport via the uncoupling protein (UCP1) as a GDP-sensitive swelling in K+ salts induced by valinomycin or by monensin and carbonyl cyanide- p-(trifluoromethoxy)phenylhydrazone in Na+ salts. We have demonstrated that this uniport is inhibited by fatty acids. GDP inhibition in K+ salts was not abolished by an uncoupler, indicating a negligible monocarboxylic acid penetration via the lipid bilayer. In contrast, the electroneutral pyruvate uptake (swelling in ammonium pyruvate or potassium pyruvate induced by change in pH) mediated by the pyruvate carrier was inhibited by its specific inhibitor α-cyano-4-hydroxycinnamate but not by fatty acids. Moreover, α-cyano-4-hydroxycinnamate enhanced the energization of brown adipose tissue mitochondria, which was monitored fluorometrically by 2-(4-dimethylaminostyryl)-1-methylpyridinium iodide and safranin O. Consequently, we suggest that UCP1 might participate in futile cycling of unipolar ketocarboxylates under certain physiological conditions while expelling these anions from the matrix. The cycle is completed on their return via the pyruvate carrier in an H+ symport mode.

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.

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