Metabolic Flux Analysis of Mitochondrial Uncoupling in 3T3-L1 Adipocytes

Si, Yaguang; Shi, Hai; Lee, Kyongbum

doi:10.1371/journal.pone.0007000

Cited by 30 publications

(42 citation statements)

References 42 publications

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“…1D). When applied acutely, FCCP collapses the mitochondrial membrane potential (Δψ m ) and stimulates cellular respiration (Si et al ., 2009). isp‐1(qm150) Mit mutants respond to FCCP treatment within seconds (Fig.…”

Section: Resultsmentioning

confidence: 99%

Mitochondrial metabolites extend lifespan

et al. 2016

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SummaryDisruption of mitochondrial respiration in the nematode Caenorhabditis elegans can extend lifespan. We previously showed that long‐lived respiratory mutants generate elevated amounts of α‐ketoacids. These compounds are structurally related to α‐ketoglutarate, suggesting they may be biologically relevant. Here, we show that provision of several such metabolites to wild‐type worms is sufficient to extend their life. At least one mode of action is through stabilization of hypoxia‐inducible factor‐1 (HIF‐1). We also find that an α‐ketoglutarate mimetic, 2,4‐pyridinedicarboxylic acid (2,4‐PDA), is alone sufficient to increase the lifespan of wild‐type worms and this effect is blocked by removal of HIF‐1. HIF‐1 is constitutively active in isp‐1(qm150) Mit mutants, and accordingly, 2,4‐PDA does not further increase their lifespan. Incubation of mouse 3T3‐L1 fibroblasts with life‐prolonging α‐ketoacids also results in HIF‐1α stabilization. We propose that metabolites that build up following mitochondrial respiratory dysfunction form a novel mode of cell signaling that acts to regulate lifespan.

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Section: Resultsmentioning

confidence: 99%

Mitochondrial metabolites extend lifespan

et al. 2016

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“…Furthermore, expression of ectopic UCP1 resulted in reduced expression of genes characteristic of differentiated energy-storing adipocytes, such as peroxisome proliferator-activated receptor gamma (PPARc) and aP2 , in analogy with the induction of ''fat burning adipocytes'' in response to leptin treatment in rats (Zhou et al 1999). In accordance, mitochondrial uncoupling in adipocytes in vitro led to lower intracellular ATP concentrations (Yamada et al 2006;Si et al 2009), up-regulation of glycolysis and mitochondrial biogenesis, and down-regulation of energyconsuming pathways such as fatty acid synthesis (Rossmeisl et al 2000;Si et al 2009;Senocak et al 2007), while lactate production was increased (Rossmeisl et al 2000; ) N D Decreased (Ishigaki et al 2005) Mitochondrial biogenesis and/or content Increased (Rossmeisl et al 2002) Content decreased (Han et al 2004) N D Mitochondrial ROS production ND Reduced (Keipert et al 2010) N D Cellular ATP levels Decreased Yamada et al 2006); increased AMP/ATP ratio Unchanged (Li et al 2000) or decreased (Li et al 2000;Couplan et al 2002;Han et al 2004 Rossmeisl et al, unpublished) suggested an upregulation of lipid catabolism in SM of high-fat diet-fed mice in response to the transgenic UCP1 expression in WAT, which is also associated with hypolipidemic effects, especially under fasted conditions. The effect of UCP1 expression on SM phenotype was studied in detail by Couplan et al (2002), who reported a fiber type switch from fast glycolytic fibers to slow oxidative fibers in gastrocnemius and plantaris muscle accompanied by a reduced muscle mass.…”

Section: Metabolic Effects Of Ectopic Ucp1 At Cellular and Tissue Levelsmentioning

confidence: 94%

“…In mice with the transient adenoviral UCP1 expression in epididymal fat, no significant changes in body weight and the weight of epididymal fat were observed, but the diameter of UCP1-expressing adipocytes was significantly reduced (Yamada et al 2006). Forced UCP1 expression in 3T3-L1 adipocytes also led to a reduction in lipid accumulation (Si et al , 2009.…”

Section: Body Composition and Obesitymentioning

confidence: 96%

“…There are also reports on the forced expression of UCP1 in 3T3-L1 cells, a murine preadipocyte cell line (Yamada et al 2006;Si et al 2007Si et al , 2009Senocak et al 2007). …”

Section: White Adipose Tissuementioning

confidence: 99%

“…Increased AMP/ATP ratio was found in WAT of aP2-Ucp1 mice, suggesting a decrease in ATP production in vivo ). There are no data on the functionality of UCP1 expressed transiently in epididymal fat of mice using the adenoviral vector (Yamada et al 2006); however, adenoviral UCP1 expression in 3T3-L1 cells decreased intracellular ATP concentrations (Si et al 2009). …”

Section: Functionality Of Ectopic Ucp1mentioning

confidence: 99%

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Augmenting energy expenditure by mitochondrial uncoupling: a role of AMP-activated protein kinase

et al. 2011

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Strategies to prevent and treat obesity aim to decrease energy intake and/or increase energy expenditure. Regarding the increase of energy expenditure, two key intracellular targets may be considered (1) mitochondrial oxidative phosphorylation, the major site of ATP production, and (2) AMP-activated protein kinase (AMPK), the master regulator of cellular energy homeostasis. Experiments performed mainly in transgenic mice revealed a possibility to ameliorate obesity and associated disorders by mitochondrial uncoupling in metabolically relevant tissues, especially in white adipose tissue (WAT), skeletal muscle (SM), and liver. Thus, ectopic expression of brown fat-specific mitochondrial uncoupling protein 1 (UCP1) elicited major metabolic effects both at the cellular/tissue level and at the whole-body level. In addition to expected increases in energy expenditure, surprisingly complex phenotypic effects were detected. The consequences of mitochondrial uncoupling in WAT and SM are not identical, showing robust and stable obesity resistance accompanied by improvement of lipid metabolism in the case of ectopic UCP1 in WAT, while preservation of insulin sensitivity in the context of high-fat feeding represents the major outcome of muscle UCP1 expression. These complex responses could be largely explained by tissue-specific activation of AMPK, triggered by a depression of cellular energy charge. Experimental data support the idea that (1) while being always activated in response to mitochondrial uncoupling and compromised intracellular energy status in general, AMPK could augment energy expenditure and mediate local as well as whole-body effects; and (2) activation of AMPK alone does not lead to induction of energy expenditure and weight reduction.

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Mild mitochondrial uncoupling induces HSL/ATGL‐independent lipolysis relying on a form of autophagy in 3T3‐L1 adipocytes

Demine

Tejerina

Bihin

et al. 2017

Journal Cellular Physiology

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Obesity is characterized by an excessive triacylglycerol accumulation in white adipocytes. Various mechanisms allowing the tight regulation of triacylglycerol storage and mobilization by lipid droplet-associated proteins as well as lipolytic enzymes have been identified. Increasing energy expenditure by inducing a mild uncoupling of mitochondria in adipocytes might represent a putative interesting anti-obesity strategy as it reduces the adipose tissue triacylglycerol content (limiting alterations caused by cell hypertrophy) by stimulating lipolysis through yet unknown mechanisms, limiting the adverse effects of adipocyte hypertrophy. Herein, the molecular mechanisms involved in lipolysis induced by a mild uncoupling of mitochondria in white 3T3-L1 adipocytes were characterized. Mitochondrial uncoupling-induced lipolysis was found to be independent from canonical pathways that involve lipolytic enzymes such as HSL and ATGL. Finally, enhanced lipolysis in response to mitochondrial uncoupling relies on a form of autophagy as lipid droplets are captured by endolysosomal vesicles. This new mechanism of triacylglycerol breakdown in adipocytes exposed to mild uncoupling provides new insights on the biology of adipocytes dealing with mitochondria forced to dissipate energy.

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Metabolic Flux Analysis of Mitochondrial Uncoupling in 3T3-L1 Adipocytes

Cited by 30 publications

References 42 publications

Mitochondrial metabolites extend lifespan

Mitochondrial metabolites extend lifespan

Augmenting energy expenditure by mitochondrial uncoupling: a role of AMP-activated protein kinase

Mild mitochondrial uncoupling induces HSL/ATGL‐independent lipolysis relying on a form of autophagy in 3T3‐L1 adipocytes

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