Mice devoid of the original uncoupling protein UCP1 have provided opportunities to delineate UCP1 function in a series of biochemical and physiological contexts. The isolated brown-fat mitochondria from such mice are fully coupled (without the addition of GDP), but still exhibit a depressed capacity for ATP synthesis. However, they only show a 2-fold decrease in sensitivity to the de-energizing effect of free fatty acids, compared with UCP1-containing mitochondria, whereas they possess a (UCP1-independent) 50-fold higher sensitivity than liver mitochondria; the fatty acid sensitivities in wild-type and UCP1-deficient mitochondria may, however, be of different natures. Despite the fact that brown-fat cells from UCP1-ablated mice cannot produce heat when stimulated by noradrenaline (‘norepinephrine’) or fatty acids, UCP1-ablated mice can be induced to tolerate extended cold exposure, but the heat then fully results from shivering thermogenesis. Recruitable or adaptive (by cold acclimation or adaptation to a cafeteria diet) adrenergically-stimulated thermogenesis does not exist in the UCP1-ablated animals, demonstrating the unique ability of UCP1 to mediate recruitable non-shivering thermogenesis. In addition to information on the function of UCP1, the UCP1 -ablated mice can be used to gain information concerning the function of the UCP1 homologues. Thus whereas an uncoupling function of the UCP1 homologues cannot be excluded, UCP1-ablated animals clearly lack any ability to recruit any UCP1 homologue to functionally replace the loss of thermogenesis resulting from UCP1. UCP1 (thermogenin) thus remains the only protein the activity of which can be recruited for the purpose of facultative thermogenesis.
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Conference Article|
November 01 2001
Life without UCPI: mitochondrial, cellular and organismal characteristics of the UCPI-ablated mice
J. Nedergaard;
J. Nedergaard
1
1The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, SE-106 91 Stockholm, Sweden
1To whom correspondence should be addressed (e-mail jan@metabol.su.se).
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V. Golozoubova;
V. Golozoubova
1The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, SE-106 91 Stockholm, Sweden
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I. Shabalina;
I. Shabalina
1The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, SE-106 91 Stockholm, Sweden
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K.-i. Ohba;
K.-i. Ohba
1The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, SE-106 91 Stockholm, Sweden
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K. Ohlson;
K. Ohlson
1The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, SE-106 91 Stockholm, Sweden
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A. Jacobsson;
A. Jacobsson
1The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, SE-106 91 Stockholm, Sweden
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B. Cannon
B. Cannon
1The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, SE-106 91 Stockholm, Sweden
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Publisher: Portland Press Ltd
Received:
June 27 2001
Online ISSN: 1470-8752
Print ISSN: 0300-5127
© 2001 Biochemical Society
2001
Biochem Soc Trans (2001) 29 (6): 756–763.
Article history
Received:
June 27 2001
Citation
J. Nedergaard, V. Golozoubova, A. Matthias, I. Shabalina, K.-i. Ohba, K. Ohlson, A. Jacobsson, B. Cannon; Life without UCPI: mitochondrial, cellular and organismal characteristics of the UCPI-ablated mice. Biochem Soc Trans 1 November 2001; 29 (6): 756–763. doi: https://doi.org/10.1042/bst0290756
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