Temperature and phenylmethylsulfonyl fluoride sensitive loss of uncoupling protein in isolated brown adipose tissue mitochondrial membranes

1994 ◽  
Vol 72 (1-2) ◽  
pp. 1-7 ◽  
Author(s):  
M. Desautels ◽  
R. A. Dulos
Keyword(s):  
Lysosomal Enzymes ◽  
Uncoupling Protein ◽  
Brown Fat ◽  
Alkaline Ph ◽  
Phenylmethylsulfonyl Fluoride ◽  
Mitochondrial Membranes ◽  
Western Blots ◽  
Binding Characteristics ◽  
Brown Adipose ◽  
Brown Fat Mitochondria

When a membrane suspension prepared from isolated rat brown fat mitochondria was incubated at 37 °C for 4 h, a loss of uncoupling protein (UCP) immunoreactivity was observed on Western blots. Analysis of [3H]GDP-binding characteristics to UCP in isolated membranes also showed a significant reduction in Bmax without significant effect on Kd. The loss of UCP was not due to protease contamination from lysosomes or mast cell granules, since loss of UCP was still observed when mitochondria were treated with digitonin to lyse lysosomes prior to membrane preparation and when mitochondria were isolated from rats injected with compound 48/80 to degranulate mast cells. Furthermore, loss of UCP was observed at alkaline pH and was not affected by inhibitors of lysosomal enzymes. Loss of UCP immunoreactivity was markedly reduced when membranes were incubated at 4 °C or in the presence of phenylmethylsulfonyl fluoride, but was not influenced by the addition of GDP. Overall, these results indicate the presence of a serine protease within brown fat mitochondrial membranes that may be involved in the breakdown of UCP.Key words: thermoregulation, body weight, mitochondria, uncoupling protein, protein degradation, protease.

scholarly journals Adaptative decrease in expression of the mRNA for uncoupling protein and subunit II of cytochrome c oxidase in rat brown adipose tissue during pregnancy and lactation

1989 ◽  
Vol 263 (3) ◽  
pp. 965-968 ◽  
Author(s):  
I Martin ◽  
M Giralt ◽  
O Viñas ◽  
R Iglesias ◽  
T Mampel ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Mrna Expression ◽  
Cytochrome C Oxidase ◽  
Uncoupling Protein ◽  
Late Pregnancy ◽  
Brown Fat ◽  
Breeding Cycle ◽  
Brown Adipose ◽  
Pregnancy And Lactation ◽  
Brown Fat Mitochondria

Uncoupling-protein (UCP) mRNA expression is decreased to 15% of virgin control levels between days 10 and 15 of pregnancy, and remains at these low values during late pregnancy and lactation. Abrupt weaning of mid-lactating rats causes a slight but significant increase in UCP mRNA. Expression of mRNA for subunit II of cytochrome c oxidase (COII) decreased to half that of virgin control in late pregnancy and during lactation. Whereas COII mRNA expression is in step with the known modifications of brown-fat mitochondria content during the breeding cycle of the rat, UCP mRNA expression appears to be diminished much earlier than the mitochondrial proton-conductance-pathway activity. On the other hand, the reactivity of brown fat to increase expression of UCP and COII mRNAs in response to acute cold or noradrenaline treatment is not impaired during lactation.

[3H]GDP binding and thermogenin amount in brown adipose tissue mitochondria from cold-exposed rats

1985 ◽  
Vol 248 (3) ◽  
pp. C365-C371 ◽  
Author(s):  
J. Nedergaard ◽  
B. Cannon
Keyword(s):  
Adipose Tissue ◽  
Uncoupling Protein ◽  
Brown Fat ◽  
Enzyme Linked Immunosorbent Assay ◽  
Elisa Assay ◽  
Brown Adipose ◽  
Significant Difference ◽  
And Control ◽  
Relationship Of ◽  
Brown Fat Mitochondria

Brown fat mitochondria were isolated from cold-exposed and control rats, and their content of the brown-fat-specific 32-kDa “uncoupling” protein thermogenin determined both by the traditional [3H]GDP-binding method and by the recently developed enzyme-linked immunosorbent assay (ELISA). In mitochondria isolated from both cold-acclimated (3 wk at 4 degrees C) and cold-exposed rats (24 h), an increase in thermogenin content was observable, both when estimated by the [3H]GDP-binding method and by the ELISA assay, and there was no statistically significant difference in the magnitude of these increases in the two methods. In 1 h cold-exposed rats there was no increase in [3H]GDP binding or in the ELISA reaction. When the amount of thermogenin was plotted against [3H]GDP binding in the different states, a relationship of 75,000 g thermogenin per mole GDP bound was obtained. Based on the resolution of these two methods, and under the three conditions investigated, it was concluded that there was no reason to postulate the existence of a “masked” form of thermogenin or of an “unmasking” process and that thermogenin in the mitochondria, as in the isolated state, has apparently one GDP binding site per dimer.

GDP binding to rat brown fat mitochondria: effects of thyroxine at different ambient temperatures

1981 ◽  
Vol 241 (3) ◽  
pp. C134-C139 ◽  
Author(s):  
U. Sundin
Keyword(s):  
Linear Increase ◽  
Reciprocal Relationship ◽  
Brown Fat ◽  
Hormone Activity ◽  
Ambient Temperatures ◽  
Heating Capacity ◽  
Brown Adipose ◽  
Induced Changes ◽  
Brown Fat Mitochondria

Reports on a reciprocal relationship between sympathetic-nerve and experimentally induced changes in thyroid-hormone activity called into question the proposed role of thyroxine in the changes seen in the brown fat after cold adaptation. Rats reared at +30, +22, and +5 degrees C received daily injections of thyroxine (1 mg/kg). After 3 wk of treatment, the thermogenic state of the tissue was assessed by measuring the capacity of the brown fat mitochondria to bind guanosine 5'-diphosphate (GDP). GDP-inhibited mitochondrial swelling, brown adipose tissue (BAT) wet weights, and mitochondrial yields were also measured. The control animals showed a linear increase in GDP binding between +30 and +5 degrees C. Thyroxine was found to lower the GDP binding markedly at +5 degrees C, less so at +22 degrees C, while no effect was evident at +30 degrees C. The values at +22 and +30 degrees C were identical. The other parameters studied all confirmed these results. The conclusion made is that the thyroxine-induced rise in basal metabolic rate lowers the critical temperature and reduces the demand for nonshivering thermogenesis. This is reflected in the reduced GDP binding and hence heating capacity of the brown fat mitochondria.

Influence of subdiaphragmatic vagotomy and brown fat sympathectomy on thermogenesis in rats

1985 ◽  
Vol 249 (3) ◽  
pp. E239-E243 ◽  
Author(s):  
P. L. Andrews ◽  
N. J. Rothwell ◽  
M. J. Stock
Keyword(s):  
Insulin Treatment ◽  
Brown Fat ◽  
Guanosine Diphosphate ◽  
Subdiaphragmatic Vagotomy ◽  
Brown Adipose ◽  
Adrenergic Antagonist ◽  
Brown Adipose Tissue Activity ◽  
Acute Injection ◽  
Brown Fat Mitochondria ◽  
Thermogenic Response

Infusion of rats with insulin (8 U/day via implanted minipump) for 7 days caused a 22% rise in resting oxygen consumption, which was inhibited by acute injection of the beta-adrenergic antagonist propranolol. Insulin treatment produced significant increases in brown fat mass, protein content, and total thermogenic activity (assessed from binding of guanosine diphosphate to isolated brown fat mitochondria), but these responses were inhibited by prior surgical sympathectomy of the tissue. Animals subjected to subdiaphragmatic vagotomy gained more weight than pair-fed, sham-operated controls and showed reductions in total energy expenditure, the acute thermogenic response to a meal and brown adipose tissue activity. Daily injections of insulin (1 U/day) prevented all of these effects of vagotomy. These data demonstrate that the changes in brown fat activity induced by exogenous insulin are mediated by the sympathetic nervous system and that the depressed thermogenesis and brown fat activity associated with vagotomy appear to be due to a relative insulin deficiency and can be reversed by treatment with the hormone.

scholarly journals β3-Adrenergic agonist induces a functionally active uncoupling protein in fat and slow-twitch muscle fibers

1998 ◽  
Vol 274 (3) ◽  
pp. E469-E475 ◽  
Author(s):  
Toshihide Yoshida ◽  
Tsunekazu Umekawa ◽  
Kenzo Kumamoto ◽  
Naoki Sakane ◽  
Akinori Kogure ◽  
...  
Keyword(s):  
Uncoupling Protein ◽  
Muscle Fibers ◽  
Ectopic Expression ◽  
Brown Fat ◽  
Obese Mice ◽  
Adrenergic Agonist ◽  
Brown Adipose ◽  
Slow Twitch Muscle ◽  
Slow Twitch ◽  
White Fat

The mitochondrial uncoupling protein (UCP) has usually been found only in brown adipose tissue. We recently observed that a chronic administration of the β3-adrenergic agonist CL-316,243 (CL) induced the ectopic expression of UCP in white fat and skeletal muscle in genetic obese yellow KK mice. The aim of the present study was to examine whether UCP could be induced in nongenetic obese animals produced by neonatal injections of monosodiuml-glutamate (MSG). The daily subcutaneous injection of CL (0.1 mg/kg) to MSG-induced obese mice for 2 wk caused significant reductions of body weight (15%) and white fat pad weight (58%). Northern and Western blot analyses showed that CL induced significant expressions of UCP in the white fat and muscle, as well as in brown fat. Immunohistochemical observations revealed that the UCP stains in white fat were localized on multilocular cells and that those in muscle were localized on slow-twitch fibers rich in mitochondria. Immunoelectron microscopy confirmed the mitochondrial localization of UCP in the myocytes. The guanosine 5′-diphosphate (GDP) binding to mitochondria in brown fat doubled after the CL treatment. Moreover, significant GDP binding was detected in the white fat and muscle of the CL-treated mice, at about one-fourth and one-thirteenth the activity of brown fat, respectively, suggesting that ectopically expressed UCP is functionally active. We concluded that the β3-adrenergic agonist CL can induce functionally active UCP in white fat and slow-twitch muscle fibers of obese mice.

scholarly journals Iodothyronine 5′-deiodinase activity as an early event of prenatal brown-fat differentiation in bovine development

1989 ◽  
Vol 259 (2) ◽  
pp. 555-559 ◽  
Author(s):  
M Giralt ◽  
L Casteilla ◽  
O Viñas ◽  
T Mampel ◽  
R Iglesias ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
White Adipose Tissue ◽  
Uncoupling Protein ◽  
Brown Fat ◽  
Early Event ◽  
Type I ◽  
Fetal Life ◽  
Reverse T3 ◽  
Deiodinase Activity ◽  
Brown Adipose

Iodothyronine 5'-deiodinase activity appears to be a type I enzyme in bovine brown adipose tissue, on the basis of its high Km for 3,3',5'-tri-iodothyronine (‘reverse T3’) (in the micromolar range) and sensitivity to propylthiouracil inhibition. This enzyme activity is already detectable in perirenal adipose tissue of bovine fetuses in the second month of gestation, reaches peak values around the seventh month of fetal life, declines before birth, becomes lower after parturition and finally undetectable in the adult cow. Iodothyronine 5'-deiodinase activity is present in the pericardic, peritoneal and intermuscular adipose depots of the neonatal calf, but it is always undetectable in the subcutaneous adipose tissue. It is concluded that iodothyronine 5'-deiodinase is a specific feature of brown fat in the bovine species that is not shared by white adipose tissue. white adipose tissue. Peak values of 5'-deiodinating activity appear as an early event in the prenatal differentiation programme of bovine brown-fat cells as they occur when uncoupling-protein-gene expression first starts.

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.

Sign in / Sign up

Export Citation Format

Share Document