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Spending your energy
Wijers and colleagues found that ers analyzed the skeletal muscle promean energy expenditure in their subteomes of nine male subjects. Each subDo you pony up four bucks for a frothy jects increased significantly both after ject lived in a respiration chamber under coffee shop latte while your frugal laboverfeeding and upon cold exposure, as baseline conditions at energy balance, mate prefers to drink the swill from the expected, and identified 95 spots as difthen in random order during overfeedgrungy communal pot? If so, you’ve ferentially expressed between conditions. ing (at 160% energy balance) and mild got a difference in spending habits. Fifty-two proteins were identified with cold exposure conditions. Their total Energy expenditure in humans is simiMALDI-TOF MS/MS analysis, and most daily energy expenditure (TDEE) was larly individualisticsconditions such as of these have metabolic, contractile, and monitored and recorded. Immediately cold exposure that would make one stress response functions. upon exiting the chamber, the subjects individual expend 12% more energy According to Wijers, the than usual may make the most interesting results were next person expend 4% the metabolic proteins. Upon more and produce no overfeeding, the abundances change in energy spending of specific isoforms of glycoin another individual. lytic enzymes increased, sugIn this issue of JPR (DOI gesting changes in the capac10.1021/pr9010074), ity of glycolysis. After mild Sander Wijers and colcold exposure, differences in leagues at the Nutrition glycolytic enzyme concentraand Toxicology Research tions correlated with the inInstitute Maastricht (NUter-individual differences in TRIM; The Netherlands) mild cold-induced adaptive report the use of a novel thermogenesis. “Striking in statistical approach that this publication was not that correlates changes in the Running hot and cold. Changes in skeletal muscle protein expression the same proteins were inskeletal muscle proteome correlate to changes in energy expenditure under adaptive thermogenesisvolved in the changes upon of individuals who are exinducing conditions cold exposure and overfeedperiencing adaptive thering, but that most related mogenesis-inducing conunderwent a percutaneous thigh muscle proteins are involved in glycolysis,” says ditions. This allowed the researchers to biopsy. Wijers. “To discover why, much more reelucidate trends despite inter-indiProteins extracted from the biopsies search has to be carried out.” vidual differences. They found that, were analyzed with 2DE, and image analyBurniston notes that some of the prosurprisingly, many of the proteins that sis software was used to compare spot teins that changed in relation to adaptive changed expression with increased endensities between subjects. “In proteomthermogenesis are also differentially exergy expenditure were involved in glyics,” says Wijers, “often researchers look pressed after interval-exercise training, and colysis; this is the first time adaptive simply at changes in expression. But bethe alteration of the expression of indithermogenesis and glycolysis have cause of the large spread in reaction bevidual isoelectric species of muscle probeen linked. tween people, we deliberately looked both teins rather than their total abundance is In rodents, the 2-4× increase in enat the changes in expression and also the consistent with his findings in rodents and ergy expenditure upon overfeeding or correlations between expression and the humans. “Such changes may relate to spemild cold exposure, called adaptive cific localization or activity of the protein TDEE.” Spot densities of individual subthermogenesis, is a well known process and are likely to be biologically imporjects were compared between conditions that is attributable to brown adipose tant,” he says. with the Wilcox Signed Rank test, then the tissue (BAT). Recently, the NUTRIM Currently, Wijers and colleagues are changes between baseline and intervenresearch group showed that active BAT writing up the results of another set of tion were correlated to changes in TDEE exists in humans, and a small increase studies comparing sympathetic nervous with the non-parametric Spearman in energy expenditure (with large intersystem effects in lean and obese subjects correlation. individual differences) occurs with cold during cold induced adaptive thermogenJatin Burniston of the Liverpool John and overfeeding conditions. In addiesis. “In preventing or curing obesity, most Moores University (U.K.) agrees that the tion, Wijers and colleagues reported attention is drawn towards diminishing approach is an effective one, and says, that inter-individual differences in food intake. However, a similar amount of “Wijers et al. apply a novel statistical apcold-induced energy expenditure are food intake leads to weight gain in some proach to correlate changes in protein exdue to differences in mitochondrial people and a steady state in other people. pression with physiological data and so uncoupling in muscle tissue (PLoS One This might be explained by a difference in address the greater inter-individual varia2008, DOI 10.1371/journal.pone.0001777). adaptive thermogenesis,” says Wijers. tion of humans over animal or in vitro To better understand the mechanisms —Amy Hodson Thompson models.” of adaptive thermogenesis, the research-
2050
Journal of Proteome Research • Vol. 9, No. 5, 2010
10.1021/pr1002164
© 2010 American Chemical Society
