The Thermogenic Activity of Rat Brown Adipose Tissue and Rabbit White Muscle Ca2 + ‐ATPase

Meis, Leopoldo de; Oliveira, Gaya M.; Arruda, Ana Paula; Santos, R.M.M.; Costa, Rodrigo Madeiro da; Benchimol, Marlene

doi:10.1080/15216540500092534

Cited by 25 publications

(32 citation statements)

References 44 publications

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“…In then long term, these fundamental studies may be useful to understand from a microscopic perspective certain human diseases, e.g., muscular dystrophy and sickle cell disease, as well as temperature regulation in muscle tissue, which have been linked to the Ca 2+ -ATPase protein. 58,59 …”

Section: Discussionmentioning

confidence: 99%

Heat transfer in protein–water interfaces

Lervik

Bresme

Kjelstrup

et al. 2010

Phys. Chem. Chem. Phys.

135

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We investigate using transient non-equilibrum molecular dynamics simulation the temperature relaxation process of three structurally different proteins in water, namely; myoglobin, green fluorescence protein (GFP) and two conformations of the Ca 2+ -ATPase protein. By modeling the temperature relaxation process using the solution of the heat conduction equation we compute the thermal conductivity and thermal diffusivity of the proteins, as well as the thermal conductance of the protein-water interface. Our results indicate that the temperature relaxation of the protein can be described using a macroscopic approach. The protein-water interface has a thermal conductance of the order of 100-270 MW m −2 K −1 , characteristic of water-hydrophilic interfaces. The thermal conductivity of the proteins is of the order of 0.1-0.2 † Imperial College and NTNU ‡ Imperial College and CAS ¶ NTNU and CAS § UB and CAS 1 Anders Lervik et al.Heat transfer in protein-water interfaces W m −1 K −1 as compared with ≈ 0.6 W m −1 K −1 for water, suggesting that these proteins can develop temperature gradients within the biomolecular structures that are larger than those of aqueous solutions. We find that the thermal diffusivity of the transmembrane protein, Ca 2+ -ATPase is about three times larger than that of myoglobin or GFP. Our simulation shows that the Kapitza length of these structurally different proteins is of the order of 1 nm, showing that the protein-water interface should play a major role in defining the thermal relaxation of biomolecules.

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Section: Discussionmentioning

confidence: 99%

Heat transfer in protein–water interfaces

Lervik

Bresme

Kjelstrup

et al. 2010

Phys. Chem. Chem. Phys.

135

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“…This work began with an attempt to visualize in electron microscopy the BAT SERCA 1 attached to the membrane of the ER (25). When ultrathin sections were analyzed, to our surprise, we found that, in addition to the ER, the anti-SERCA 1 antibodies also reacted with BAT mitochondrial cristae.…”

Section: Transmission Electron Microscopy Andmentioning

confidence: 99%

Identification of a Ca2+-ATPase in Brown Adipose Tissue Mitochondria

Meis

Arruda

Costa

et al. 2006

Journal of Biological Chemistry

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In brown adipose tissue (BAT) adrenaline promotes a rise of the cytosolic Ca 2؉ concentration from 0.05 up to 0.70 M. It is not known how the rise of Ca 2؉ concentration activates BAT thermogenesis. In this report we compared the effects of Ca 2؉ in BAT and liver mitochondria. Using electron microscopy and immunolabeling we identified a sarco/endoplasmic reticulum (ER) Ca 2؉ -ATPase bound to the inner membrane of BAT mitochondria. A Ca 2؉ -dependent ATPase activity was detected in BAT mitochondria when the respiratory substrates malate and pyruvate were included in the medium. ATP and Ca 2؉ enhanced the amount of heat produced by BAT mitochondria during respiration. The Ca 2؉ concentration needed for half-maximal activation of the ATPase activity and rate of heat production were the same and varied between 0.1 and 0.2 M. Heat production was partially inhibited by the proton ionophore carbonyl cyanide p-trifluoromethoxyphenylhydrazone and abolished by thapsigargin, a specific ER Ca 2؉ -ATPase inhibitor, and by both rotenone and KCN, two substances that inhibit the electron transfer trough the mitochondrial cytochrome chain. In liver mitochondria Ca 2؉ did not stimulate the ATPase activity nor increase the rate of heat production. Thapsigargin had no effect on liver mitochondria. In conclusion, this is the first report of a Ca 2؉ -ATPase in mitochondria that is BAT-specific and can generate heat in the presence of Ca 2؉ concentrations similar to those noted in the cell during adrenergic stimulation. BAT3 is capable of rapidly converting fat stores to heat and has been used as a model system for the understanding of nonshivering heat production and mechanisms of energy wasting to control obesity (1-9). The signal that activates the rate of heat production in BAT cells is the rise of the cytosolic Ca 2ϩ concentration from a basal level of 0.05 M up to the range of 0.2-0.7 M. This is promoted by ␣ 1 -and ␤ 3 -adrenergic receptors located in the cell membrane. Activation of ␣ 1 -adrenoreceptors leads to the release of Ca 2ϩ from intracellular stores into the cytosol, whereas ␤ 3 -adrenergic receptors promote the release of free fatty acids and increase the effect of Ca 2ϩ release induced by ␣ 1 -adrenoreceptors (10, 11). At present we do not know how the rise of the cytosolic Ca 2ϩ concentration activates the rate of heat production in BAT cells.In a previous report (12) we identified a sarco/ER Ca 2ϩ ATPase (SERCA 1) in vesicles derived from BAT ER. In this report we show that the rate of heat produced by BAT mitochondria is enhanced when the Ca 2ϩ concentration in the medium is raised to a level similar to that observed in BAT cells during adrenergic stimulation. This effect is not observed in liver mitochondria, a tissue that is not specialized in heat production. EXPERIMENTAL PROCEDURES Isolation of Mitochondria from Rat BAT and Liver-Adult maleWistar rats were killed by decapitation. Mitochondria were isolated as previously described (13). Briefly, interscapular BAT and liver were removed and homogenized in a mix...

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“…de Meis et al (3)(4)(5)(6) has shown that ATP is hydrolyzed by SR Ca 2ϩ -ATPase both to transport Ca 2ϩ and to generate heat (3)(4)(5)(6). In the process of transport, two Ca 2ϩ ions are pumped from the cytoplasm to the lumen of the SR for each molecule of ATP hydrolyzed (Scheme 1), and the expected ratio of two Ca 2ϩ ions accumulated per ATP molecule hydrolyzed was observed during the first reaction cycle of the ATPase before the lumenal concentration of Ca 2ϩ had increased to a high level (27).…”

Section: Molar Ratiomentioning

confidence: 99%

“…However, this is not the only important physiological role of the Ca 2ϩ -ATPase since the principle source of heat during nonshivering thermogenesis in animals lacking brown adipose tissue is muscle, heat being produced by the hydrolysis of ATP by the SR Ca 2ϩ -ATPase (2). de Meis et al (3)(4)(5)(6) has shown that the proportions of ATP used by the Ca 2ϩ -ATPase for transport and for heat generation varies with conditions and that changes in work/heat output by the Ca 2ϩ -ATPase are related to changes in the reaction cycle of the Ca 2ϩ -ATPase. The reaction cycle of the Ca 2ϩ -ATPase is shown in simplified form in Scheme 1 (7).…”

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confidence: 99%