Native UCP1 Displays Simple Competitive Kinetics between the Regulators Purine Nucleotides and Fatty Acids

Shabalina, Irina G.; Jacobsson, Anders; Cannon, Barbara; Nedergaard, Jan

doi:10.1074/jbc.m402375200

Cited by 149 publications

(150 citation statements)

References 53 publications

Supporting

Mentioning

138

Contrasting

Unclassified

Order By: Relevance

“…Mouse and human UCP1 are activated by free fatty acids and inhibited by purine nucleotides such as GDP (12,29,(36)(37)(38). Along these lines, addition of GDP specifically reduced the oxygen flux of UCP1 containing mitochondria to such an extent that mUCP1-HA became indistinguishable from control, which remained unchanged ( Fig.…”

Section: Resultsmentioning

confidence: 77%

Neuronal UCP1 expression suggests a mechanism for local thermogenesis during hibernation

Laursen

Mastrotto

Pesta

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Hibernating mammals possess a unique ability to reduce their body temperature to ambient levels, which can be as low as −2.9°C, by active down-regulation of metabolism. Despite such a depressed physiologic phenotype, hibernators still maintain activity in their nervous systems, as evidenced by their continued sensitivity to auditory, tactile, and thermal stimulation. The molecular mechanisms that underlie this adaptation remain unknown. We report, using differential transcriptomics alongside immunohistologic and biochemical analyses, that neurons from thirteen-lined ground squirrels (Ictidomys tridecemlineatus) express mitochondrial uncoupling protein 1 (UCP1). The expression changes seasonally, with higher expression during hibernation compared with the summer active state. Functional and pharmacologic analyses show that squirrel UCP1 acts as the typical thermogenic protein in vitro. Accordingly, we found that mitochondria isolated from torpid squirrel brain show a high level of palmitate-induced uncoupling. Furthermore, torpid squirrels during the hibernation season keep their brain temperature significantly elevated above ambient temperature and that of the rest of the body, including brown adipose tissue. Together, our findings suggest that UCP1 contributes to local thermogenesis in the squirrel brain, and thus supports nervous tissue function at low body temperature during hibernation.T hirteen-lined ground squirrels (Ictidomys tridecemlineatus) are obligatory hibernating mammals. They are found across a wide range of latitudes, from southern Canada to the Gulf of Mexico. In northern habitats with long winters and limited food resources, ground squirrels breed only once a year, in late spring, and then hibernate in underground burrows from October to April. Hibernation consists of cycling between bouts of torpor and brief interbout arousal periods, each usually lasting less than 24 h (1, 2).During the long hibernation season, torpid animals undergo dramatic perturbations, including reduction in heart, respiratory, and overall metabolic rates, as well as decreases in core body temperature from 37°C to just above ambient temperature (often as low as 1-5°C) (2). Despite such a depressed physiologic phenotype, torpid animals remain sensitive to their environment (3). For example, during extreme winters, when ambient burrow temperatures reach the freezing point of water, most hibernating mammals increase metabolic activity and warm up as a safety precaution to prevent freezing (4). Similarly, arousal can be triggered by sound, touch, or a sudden increase in ambient temperature (3, 5). Thus, hibernating animals maintain activity in their peripheral and central nervous systems. Indeed, physiologic experiments conducted on nerve fibers isolated from torpid hamsters and squirrels demonstrated the ability to generate action potentials at temperatures prohibitively low for their nonhibernating relatives (i.e., rats, mice) (6-8).Deeply hibernating animals can keep their brain temperatures elevated above ambient by seve...

show abstract

Section: Resultsmentioning

confidence: 77%

Neuronal UCP1 expression suggests a mechanism for local thermogenesis during hibernation

Laursen

Mastrotto

Pesta

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…The tissue was minced and then homogenized by hand using a glass/Teflon Potter-Elvehjem tissue grinder in a 250 mM sucrose solution containing 0.2% BSA. Mitochondria were isolated as described (26). Protein concentration was determined by Bradford assay using BSA as the standard.…”

Section: Methodsmentioning

confidence: 99%

“…Mitochondria were then isolated as described (25). BAT mitochondria were isolated using a standard protocol, as described (26). Interscapular BAT was dissected from 2-3 mice/genotype, cleaned, and pooled in a 250 mM sucrose solution.…”

Section: Methodsmentioning

confidence: 99%

Glutathionylation Acts as a Control Switch for Uncoupling Proteins UCP2 and UCP3

Mailloux

Seifert

Bouillaud

et al. 2011

Journal of Biological Chemistry

158

148

View full text Add to dashboard Cite

The mitochondrial uncoupling proteins 2 and 3 (UCP2 and -3) are known to curtail oxidative stress and participate in a wide array of cellular functions, including insulin secretion and the regulation of satiety. However, the molecular control mechanism(s) governing these proteins remains elusive. Here we reveal that UCP2 and UCP3 contain reactive cysteine residues that can be conjugated to glutathione. We further demonstrate that this modification controls UCP2 and UCP3 function. Both reactive oxygen species and glutathionylation were found to activate and deactivate UCP3-dependent increases in nonphosphorylating respiration. We identified both Cys 25 and Cys 259 as the major glutathionylation sites on UCP3. Additional experiments in thymocytes from wild-type and UCP2 null mice demonstrated that glutathionylation similarly diminishes non-phosphorylating respiration. Our results illustrate that UCP2-and UCP3-mediated state 4 respiration is controlled by reversible glutathionylation. Altogether, these findings advance our understanding of the roles UCP2 and UCP3 play in modulating metabolic efficiency, cell signaling, and oxidative stress processes.UCP2 and -3 belong to the mitochondrial anion carrier family and are ϳ73% homologous to each other, and they are both ϳ58% homologous to the highly thermogenic uncoupling protein, UCP1. Whereas UCP3 is expressed in skeletal muscle and brown adipose tissue (BAT) 3 and to some extent in the heart, UCP2 is found in a wide variety of tissues (1). UCP2 and UCP3 have been shown to diminish oxidative stress by lowering the mitochondrial membrane potential (2, 3). Acute increases in reactive oxygen species (ROS) production increase proton conductance through both UCP2 and UCP3, providing a negative feedback loop to limit further mitochondrial ROS formation (4, 5). Furthermore, UCP2 and UCP3 have also been implicated in many physiologic functions, suggesting that the common underlying mechanism may be ROS-mediated cell signaling.Previous work has reported that UCP3 protects against insulin resistance and obesity (6 -9), whereas UCP2 has been implicated a broad range of functions, including hormone secretion from the pancreas, immune cell function, and feeding behavior (10 -13). For UCP2, most of these functions are linked to ROS level buffering (14 -16). Indeed, UCP2 null mice on various genetic backgrounds exhibit oxidative stress in many tissue types and a decrease in the circulating glutathione (GSH)/glutathione disulfide ratio (2, 12). Increased expression of UCP2 in cancer cells is associated with the acquisition of drug-resistant phenotypes, a phenomenon related to the ROS-quenching function of UCP2 (17, 18). The absence of UCP3 in skeletal muscle increases oxidative damage and perturbs skeletal muscle metabolism (19). Increased UCP3 expression in muscle augments fatty acid metabolism and also curtails ROS production during fatty acid oxidation (20,21). Remarkably, although they have been linked to a plethora of cellular processes, the molecular control of UCP2 and UCP3 ha...

show abstract

“…As elucidated from studies of UCP1-ablated mice, brown fat mitochondria from wild-type mice exhibit innate UCP1-dependent high oxygen consumption (uncoupling) that can be inhibited by GDP and reactivated by fatty acids (3,34). To see whether this innate uncoupling was affected by the ELOVL3 deficiency, we analyzed mitochondria from Elovl3-ablated mice.…”

Section: Oxidative Capacity Of Brown Adipose Tissue In Elovl3-ablatedmentioning

confidence: 99%

ELOVL3 Is an Important Component for Early Onset of Lipid Recruitment in Brown Adipose Tissue

Westerberg

Månsson

Golozoubova

et al. 2006

Journal of Biological Chemistry

Self Cite

128

View full text Add to dashboard Cite

During the recruitment process of brown adipose tissue, the mRNA level of the fatty acyl chain elongase Elovl3 is elevated more than 200-fold in cold-stressed mice. We have obtained Elovl3-ablated mice and report here that, although cold-acclimated Elovl3-ablated mice experienced an increased heat loss due to impaired skin barrier, they were unable to hyperrecruit their brown adipose tissue. Instead, they used muscle shivering in order to maintain body temperature. Lack of Elovl3 resulted in a transient decrease in the capacity to elongate saturated fatty acyl-CoAs into very long chain fatty acids, concomitantly with the occurrence of reduced levels of arachidic acid (C20:0) and behenic acid (C22:0) in brown adipose tissue during the initial cold stress. This effect on very long chain fatty acid synthesis could be illustrated as a decrease in the condensation activity of the elongation enzyme. In addition, warmacclimated Elovl3-ablated mice showed diminished ability to accumulate fat and reduced metabolic capacity within the brown fat cells. This points to ELOVL3 as an important regulator of endogenous synthesis of saturated very long chain fatty acids and triglyceride formation in brown adipose tissue during the early phase of the tissue recruitment.Brown adipose tissue is the only tissue that functions exclusively to combust fat for heat production (1-3). When mammals encounter cold, there is an induced synthesis of specific mRNA species in brown adipose tissue, which encode enzymes regulating energy expenditure and lipid metabolism (4 -6). Most notable is the increased mRNA level of the mitochondrial uncoupling protein 1 (UCP1), which can uncouple the mitochondrial respiratory chain and thereby dissipate heat instead of conserving energy in the form of ATP. The induction of processes needed for increased brown adipose tissue activity is referred to as brown fat recruitment.The process is controlled by norepinephrine release from sympathetic nerve endings found in the tissue (7, 8) and can roughly be divided into two major phases, depending on how the animal experiences the cold (4°C) (i.e. cold stress or cold acclimation). During the first days of cold exposure (i.e. cold stress), the major effect on brown adipose tissue is the initiation of hypertrophy, and a few days later, during the onset of cold acclimation, hyperplasia occurs (9, 10). After 4 days of cold exposure, there is a doubling in DNA amount, and after 3 weeks, a 3-fold increase is detected, which is the maximal level achieved with this degree of cold (11,12). The increase in the total amount of protein in cold-exposed mice occurs also as a two-phase phenomenon (5). The first phase is completed within 3 days, and the second phase of protein increase (i.e. during cold acclimation) is found in the tissue after 2-3 weeks of cold exposure. During these events, protein synthesis mainly reflects an increase in mRNA levels (5).During the process of identifying specific cDNA molecules corresponding to mRNA species that are induced in the brown adipose ti...

show abstract

Native UCP1 Displays Simple Competitive Kinetics between the Regulators Purine Nucleotides and Fatty Acids

Cited by 149 publications

References 53 publications

Neuronal UCP1 expression suggests a mechanism for local thermogenesis during hibernation

Neuronal UCP1 expression suggests a mechanism for local thermogenesis during hibernation

Glutathionylation Acts as a Control Switch for Uncoupling Proteins UCP2 and UCP3

ELOVL3 Is an Important Component for Early Onset of Lipid Recruitment in Brown Adipose Tissue

Contact Info

Product

Resources

About