Reduced hepatic mitochondrial respiration following acute high-fat diet is prevented by PGC-1α overexpression

Changes in substrate utilization and reduced mitochondrial respiratory capacity following exposure to energy-dense, high-fat diets (HFD) are putatively key components in the development of obesity-related metabolic disease. We examined the effect of a 3-day HFD on isolated liver mitochondrial respiration and whole body energy utilization in obesity-prone (OP) rats. We also examined if hepatic overexpression of peroxisomal proliferator-activated receptor-γ coactivator-1α (PGC-1α), a master regulator of mitochondrial respiratory capacity and biogenesis, would modify liver and whole body responses to the HFD. Acute, 3-day HFD (45% kcal) in OP rats resulted in increased daily energy intake, energy balance, weight gain, and adiposity, without an increase in liver triglyceride (triacylglycerol) accumulation. HFD-fed OP rats also displayed decreased whole body substrate switching from the dark to the light cycle, which was paired with reductions in hepatic mitochondrial respiration of multiple substrates in multiple respiratory states. Hepatic PGC-1α overexpression was observed to protect whole body substrate switching, as well as maintain mitochondrial respiration, following the acute HFD. Additionally, liver PGC-1α overexpression did not alter whole body dietary fatty acid oxidation but resulted in greater storage of dietary free fatty acids in liver lipid, primarily as triacylglycerol. Together, these data demonstrate that a short-term HFD can result in a decrease in metabolic flexibility and hepatic mitochondrial respiratory capacity in OP rats that is completely prevented by hepatic overexpression of PGC-1α.

Download Full-text

Tissue-specific control of mitochondrial respiration in obesity-related insulin resistance and diabetes

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00159.2011 ◽

2012 ◽

Vol 302 (6) ◽

pp. E731-E739 ◽

Cited By ~ 81

Author(s):

Maria H. Holmström ◽

Eduardo Iglesias-Gutierrez ◽

Juleen R. Zierath ◽

Pablo M. Garcia-Roves

Keyword(s):

Insulin Resistance ◽

Skeletal Muscle ◽

Mitochondrial Dysfunction ◽

Mitochondrial Respiration ◽

Mitochondrial Dynamics ◽

Acid Oxidation ◽

Peroxisome Proliferator ◽

Respiratory Capacity ◽

Tissue Specific ◽

Mitochondrial Respiratory

The tissue-specific role of mitochondrial respiratory capacity in the development of insulin resistance and type 2 diabetes is unclear. We determined mitochondrial function in glycolytic and oxidative skeletal muscle and liver from lean (+/ ?) and obese diabetic ( db/db) mice. In lean mice, the mitochondrial respiration pattern differed between tissues. Tissue-specific mitochondrial profiles were then compared between lean and db/db mice. In liver, mitochondrial respiratory capacity and protein expression, including peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), was decreased in db/db mice, consistent with increased mitochondrial fission. In glycolytic muscle, mitochondrial respiration, as well as protein and mRNA expression of mitochondrial markers, was increased in db/db mice, suggesting increased mitochondrial content and fatty acid oxidation capacity. In oxidative muscle, mitochondrial complex I function and PGC-1α and mitochondrial transcription factor A (TFAM) protein levels were decreased in db/db mice, along with increased level of proteins related to mitochondrial dynamics. In conclusion, mitochondrial respiratory performance is under the control of tissue-specific mechanisms and is not uniformly altered in response to obesity. Furthermore, insulin resistance in glycolytic skeletal muscle can be maintained by a mechanism independent of mitochondrial dysfunction. Conversely, insulin resistance in liver and oxidative skeletal muscle from db/db mice is coincident with mitochondrial dysfunction.

Download Full-text

Long-term, high-fat feeding exacerbates short-term increases in adipose mitochondrial reactive oxygen species, without impairing mitochondrial respiration

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00028.2020 ◽

2020 ◽

Vol 319 (2) ◽

pp. E376-E387 ◽

Cited By ~ 2

Author(s):

Valerie Politis-Barber ◽

Henver S. Brunetta ◽

Sabina Paglialunga ◽

Heather L. Petrick ◽

Graham P. Holloway

Keyword(s):

Reactive Oxygen Species ◽

Mitochondrial Respiration ◽

Reactive Oxygen ◽

Oxygen Species ◽

Mitochondrial Reactive Oxygen Species ◽

High Fat ◽

Respiratory Capacity ◽

Tissue Weight ◽

Mitochondrial Respiratory

White adipose tissue (WAT) dysfunction in obesity is implicated in the onset of whole body insulin resistance. Alterations in mitochondrial bioenergetics, namely impaired mitochondrial respiration and increased mitochondrial reactive oxygen species (mtROS) production, have been suggested to contribute to this metabolic dysregulation. However, techniques investigating mitochondrial function are classically normalized to tissue weight, which may be confounding when considering obesity-related adipocyte hypertrophy. Furthermore, the effect of long-term high-fat diet (HFD) on mtROS in WAT has yet to be elucidated. Therefore, we sought to determine the HFD-mediated temporal changes in mitochondrial respiration and mtROS emission in WAT. C57BL/6N mice received low-fat diet or HFD for 1 or 8 wk and changes in inguinal WAT (iWAT) and epididymal WAT (eWAT) were assessed. While tissue weight-normalized mitochondrial respiration was reduced in iWAT following 8-wk HFD-feeding, this effect was mitigated when adipocyte cell size and/or number were considered. These data suggest HFD does not impair mitochondrial respiratory capacity per adipocyte within WAT. In support of this assertion, within eWAT compensatory increases in lipid-supported and maximal succinate-supported respiration occurred at 8 wk despite cell hypertrophy and increases in WAT inflammation. Although these data suggest impairments in mitochondrial respiration do not contribute to HFD-mediated WAT phenotype, lipid-supported mtROS emission increased following 1-wk HFD in eWAT, while both lipid and carbohydrate-supported mtROS were increased at 8 wk in both depots. Combined, these data establish that while HFD does not impair adipocyte mitochondrial respiratory capacity, increased mtROS is an enduring physiological occurrence within WAT in HFD-induced obesity.

Download Full-text

Estradiol treatment or modest exercise improves hepatic health and mitochondrial outcomes in female mice following ovariectomy

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00013.2021 ◽

2021 ◽

Author(s):

Kelly N. Z. Fuller ◽

Colin S. McCoin ◽

Alex T. Von Schulze ◽

Claire J. Houchen ◽

Michael A. Choi ◽

...

Keyword(s):

Bile Acid ◽

Mitochondrial Function ◽

High Fat Diet ◽

Acid Metabolism ◽

Bile Acid Metabolism ◽

High Fat ◽

Estradiol Treatment ◽

Respiratory Capacity ◽

Female Mice ◽

Mitochondrial Respiratory

We recently reported that compared to males, female mice have increased hepatic mitochondrial respiratory capacity and are protected against high-fat diet-induced steatosis. Here we sought to determine the role of estrogen in hepatic mitochondrial function, steatosis, and bile acid metabolism in female mice, as well as investigate potential benefits of exercise in the absence or presence of estrogen via ovariectomy (OVX). Female C57BL mice (n=6 per group) were randomly assigned to sham surgery (Sham), ovariectomy (OVX), or OVX plus estradiol replacement therapy (OVX+Est). Half of the mice in each treatment group were sedentary (SED) or had access to voluntary wheel running (VWR). All mice were fed a high-fat diet (HFD) and were housed at thermoneutral temperatures. We assessed isolated hepatic mitochondrial respiratory capacity using the Oroboros O2k with both pyruvate and palmitoylcarnitine as substrates. As expected, OVX mice presented with greater hepatic steatosis, weight gain, and fat mass gain compared to Sham and OVX+Est animals. Hepatic mitochondrial coupling (Basal/State 3 respiration) with pyruvate was impaired following OVX, but both VWR and estradiol treatment rescued coupling to levels greater than or equal to Sham animals. Estradiol and exercise also had different effects on liver electron transport chain protein expression depending on OVX status. Markers of bile acid metabolism and excretion were also impaired by ovariectomy but rescued with estradiol add-back. Together our data suggest that estrogen depletion impairs hepatic mitochondrial function and liver health, and that estradiol replacement and modest exercise can aid in rescuing this phenotype.

Download Full-text

Selective overexpression of Toll-like receptor-4 in skeletal muscle impairs metabolic adaptation to high-fat feeding

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00139.2015 ◽

2015 ◽

Vol 309 (3) ◽

pp. R304-R313 ◽

Cited By ~ 8

Author(s):

Ryan P. McMillan ◽

Yaru Wu ◽

Kevin Voelker ◽

Gabrielle Fundaro ◽

John Kavanaugh ◽

...

Keyword(s):

Skeletal Muscle ◽

High Fat Diet ◽

Whole Body ◽

Metabolic Adaptation ◽

Acid Oxidation ◽

Chow Diet ◽

Toll Like Receptor ◽

High Fat ◽

Toll Like Receptor 4 ◽

Fat Feeding

Toll-like receptor-4 (TLR-4) is elevated in skeletal muscle of obese humans, and data from our laboratory have shown that activation of TLR-4 in skeletal muscle via LPS results in decreased fatty acid oxidation (FAO). The purpose of this study was to determine whether overexpression of TLR-4 in skeletal muscle alters mitochondrial function and whole body metabolism in the context of a chow and high-fat diet. C57BL/6J mice (males, 6–8 mo of age) with skeletal muscle-specific overexpression of the TLR-4 (mTLR-4) gene were created and used for this study. Isolated mitochondria and whole muscle homogenates from rodent skeletal muscle (gastrocnemius and quadriceps) were investigated. TLR-4 overexpression resulted in a significant reduction in FAO in muscle homogenates; however, mitochondrial respiration and reactive oxygen species (ROS) production did not appear to be affected on a standard chow diet. To determine the role of TLR-4 overexpression in skeletal muscle in response to high-fat feeding, mTLR-4 mice and WT control mice were fed low- and high-fat diets for 16 wk. The high-fat diet significantly decreased FAO in mTLR-4 mice, which was observed in concert with elevated body weight and fat, greater glucose intolerance, and increase in production of ROS and cellular oxidative damage compared with WT littermates. These findings suggest that TLR-4 plays an important role in the metabolic response in skeletal muscle to high-fat feeding.

Download Full-text

MON-672 Progesterone Receptor Membrane Component 1 Suppresses Lipid Accumulation and Lipotoxicity in Animal Model of Diabetic Cardiomyopathy (DCM)

Journal of the Endocrine Society ◽

10.1210/jendso/bvaa046.763 ◽

2020 ◽

Vol 4 (Supplement_1) ◽

Author(s):

Sang R Lee ◽

Eui-ju Hong

Keyword(s):

Fatty Acid ◽

Progesterone Receptor ◽

Fatty Acid Oxidation ◽

Diabetic Cardiomyopathy ◽

Mitochondrial Respiration ◽

Lipid Accumulation ◽

High Fat Diet ◽

Acid Oxidation ◽

High Fat ◽

Membrane Component

Abstract Diabetic cardiomyopathy (DCM) is one of the complications triggered by type II diabetes (T2D) (1). When free fatty acids (FFA) are abundant in insulin resistant pre-diabetic patients because of adipose lipolysis, FFA tends to move toward heart (2). Lipid accumulation can cause cardiac lipotoxicity and exacerbate DCM (3). In previous study, Pgrmc1 has been identified to associate with fatty acid synthesis (4). Therefore, we assumed that Pgrmc1 will associate with DCM. By feeding high-fat diet for 8 weeks and injecting streptozotocin (30mg/kg), T2D and DCM were induced. The lipid accumulation was exacerbated in T2D-induced Pgrmc1 KO heart, and FFA level was also high. Levels of lipid metabolic genes showed the tendency for lipid accumulation and lipotoxicity, and glycolysis was induced in T2D-induced Pgrmc1 KO heart. Though glycolysis presents higher efficiency for energy production in cardiomyopathy (5), it did not compensate the impairment of mitochondrial respiration in Pgrmc1 KO heart. High-fat diet and streptozotocin could not be the interfering factors, because suppression of fatty acid oxidation, induction of glycolysis, and impairment of mitochondrial respiration were observed similarly in post-prandial mice which were fed with normal chow. Insulin was excluded for interfering factor as cell line with serum starvation showed mitochondrial suppression and glycolytic induction in flux analyzer analysis in Pgrmc1 knockdown. Conversely, induction of fatty acid oxidation and suppression of glycolysis were observed in 72 h fasting of Pgrmc1 KO heart, suggesting the nutrition is closely associated with the metabolic modulation of Pgrmc1 on heart. This metabolic phenotype of Pgrmc1 KO heart consequently exacerbated DCM by showing high levels of fibrosis, inflammation, endoplasmic reticulum stress, and oxidative stress. References: (1) Jia G, Hill MA, Sowers JR. Diabetic Cardiomyopathy: An Update of Mechanisms Contributing to This Clinical Entity. Circulation research. 2018;122:624-38. (2) Noll C, Carpentier AC. Dietary fatty acid metabolism in prediabetes. Current opinion in lipidology. 2017;28:1-10. (3) Goldberg IJ, Trent CM, Schulze PC. Lipid metabolism and toxicity in the heart. Cell metabolism. 2012;15:805-12. (4) Lee SR, Kwon SW, Kaya P, Lee YH, Lee JG, Kim G, et al. Loss of progesterone receptor membrane component 1 promotes hepatic steatosis via the induced de novo lipogenesis. Scientific reports. 2018;8:15711. (5) Nagoshi T, Yoshimura M, Rosano GM, Lopaschuk GD, Mochizuki S. Optimization of cardiac metabolism in heart failure. Current pharmaceutical design. 2011;17:3846-53.

Download Full-text

Different contribution of muscle and liver lipid metabolism to endurance capacity and obesity susceptibility of mice

Journal of Applied Physiology ◽

10.1152/japplphysiol.90804.2008 ◽

2009 ◽

Vol 106 (3) ◽

pp. 871-879 ◽

Cited By ~ 30

Author(s):

Satoshi Haramizu ◽

Azumi Nagasawa ◽

Noriyasu Ota ◽

Tadashi Hase ◽

Ichiro Tokimitsu ◽

...

Keyword(s):

Lipid Metabolism ◽

Liver Lipid ◽

Whole Body ◽

Endurance Capacity ◽

High Fat ◽

Oxidation Activity ◽

Protein Levels ◽

Liver Lipid Metabolism ◽

Obesity Susceptibility ◽

Body Energy

We investigated strain differences in whole body energy metabolism, peripheral lipid metabolism, and energy metabolism-related gene expression and protein levels in BALB/c, C57BL/6J, and A/J mice to evaluate the relationship between endurance capacity, susceptibility to diet-induced obesity, and differences in lipid metabolism in muscle and liver. A high-fat diet significantly increased body weight and fat weight in C57BL/6J mice, but not in BALB/c and A/J mice. The endurance capacity of BALB/c mice was 52% greater than that of C57BL/6J mice and 217% greater than that of A/J mice. The respiratory exchange ratio was lowest in BALB/c mice, higher in C57BL/6J mice, and highest in A/J mice, which inversely correlated with the endurance capacity and fatty acid β-oxidation activity in the muscle. Plasma lactate levels measured immediately after exercise were lowest in BALB/c mice and highest in A/J mice, although there was no difference under resting conditions, suggesting that carbohydrate breakdown is suppressed by enhanced fat utilization during exercise in BALB/c mice. On the other hand, the body weight increase induced by high-fat feeding was related to a reduced whole body energy expenditure, higher respiratory quotient, and lower fatty acid β-oxidation activity in the liver. In addition, β-oxidation activity in the muscle and liver roughly paralleled the mRNA and protein levels of lipid metabolism-related molecules, such as peroxisome proliferator-activated receptor and medium-chain acyl-CoA dehydrogenase, in each tissue. These findings indicate that genetically determined basal muscle and liver lipid metabolism and responsiveness to exercise influence physical performance and obesity susceptibility.

Download Full-text

Rev-erbα heterozygosity produces a dose-dependent phenotypic advantage in mice

10.1101/2019.12.30.890806 ◽

2019 ◽

Author(s):

Ryan D. Welch ◽

Cyrielle Billon ◽

Thomas P. Burris ◽

Colin A. Flaveny

Keyword(s):

Fatty Acid ◽

Fatty Acid Oxidation ◽

Knockout Mice ◽

Muscular Atrophy ◽

Whole Body ◽

Acid Oxidation ◽

Light Cycle ◽

Clock Proteins ◽

Circadian Clock Proteins ◽

Muscle Homeostasis

AbstractNumerous mutational studies have demonstrated that circadian clock proteins regulate behavior and metabolism. Nr1d1(Rev-erbα) is a key regulator of circadian gene expression and a pleiotropic regulator of skeletal muscle homeostasis and lipid metabolism. Loss of Rev-erbα expression induces muscular atrophy, high adiposity, and metabolic syndrome in mice. Here we show that, unlike knockout mice, Nr1d1 heterozygous mice are not susceptible to muscular atrophy and in fact paradoxically possess larger myofiber diameters and improved neuromuscular function, compared to wildtype mice. Heterozygous mice lacked dyslipidemia, a characteristic of Nr1d1 knockout mice and displayed increased whole-body fatty-acid oxidation during periods of inactivity (light cycle). Heterozygous mice also exhibited higher rates of glucose uptake when fasted, and had elevated basal rates of gluconeogenesis compared to wildtype and knockout littermates. Rev-erbα ablation suppressed glycolysis and fatty acid-oxidation in white-adipose tissue (WAT), whereas partial Rev-erbα loss, curiously stimulated these processes. Our investigations revealed that Rev-erbα dose-dependently regulates glucose metabolism and fatty acid oxidation in WAT and muscle.

Download Full-text

Hepatic IKKε expression is dispensable for high-fat feeding-induced increases in liver lipid content and alterations in glucose tolerance

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00309.2019 ◽

2020 ◽

Vol 318 (1) ◽

pp. E11-E21

Author(s):

J. Jason Collier ◽

Heidi M. Batdorf ◽

Tamra M. Mendoza ◽

David H. Burk ◽

Thomas M. Martin ◽

...

Keyword(s):

Weight Gain ◽

Insulin Sensitivity ◽

Glucose Tolerance ◽

Liver Lipid ◽

Nuclear Factor Κb ◽

Whole Body ◽

High Fat ◽

Glycogen Accumulation ◽

Liver Lipid Content ◽

Sites Of Action

There are endocrine and immunological changes that occur during onset and progression of the overweight and obese states. The inhibitor of nuclear factor-κB kinase-ε (IKKε) was originally described as an inducible protein kinase; whole body gene deletion or systemic pharmaceutical targeting of this kinase improved insulin sensitivity and glucose tolerance in mice. To investigate the primary sites of action associated with IKKε during weight gain, we describe the first mouse line with conditional elimination of IKKε in the liver (IKKεAlb–/–). IKKεAlb–/– mice and littermate controls gain weight, show similar changes in body composition, and do not display any improvements in insulin sensitivity or whole body glucose tolerance. These studies were conducted using breeder chow diets and matched low- vs. high-fat diets. While glycogen accumulation in the liver is reduced in IKKεAlb–/– mice, lipid storage in liver is similar in IKKεAlb–/– mice and littermate controls. Our results using IKKεAlb–/– mice suggest that the primary action of this kinase to impact insulin sensitivity during weight gain lies predominantly within extrahepatic tissues.

Download Full-text

Changes in insulin resistance do not occur in parallel with changes in mitochondrial content and function in male rats

10.1101/2020.07.06.190702 ◽

2020 ◽

Author(s):

Amanda J Genders ◽

Jujiao Kuang ◽

Evelyn C Marin ◽

Nicholas J Saner ◽

Javier Botella ◽

...

Keyword(s):

Insulin Resistance ◽

Exercise Training ◽

Mitochondrial Respiration ◽

High Fat Diet ◽

Respiratory Function ◽

High Fat ◽

Mitochondrial Content ◽

Insulin Tolerance ◽

And Function ◽

Mitochondrial Respiratory

AbstractAims/hypothesisTo investigate if there is a causal relationship between changes in insulin resistance and mitochondrial respiratory function and content in rats fed a high fat diet (HFD) with or without concurrent exercise training. We hypothesised that provision of a high fat diet (HFD) would increase insulin resistance and decrease mitochondrial characteristics (content and function), and that exercise training would improve both mitochondrial characteristics and insulin resistance in rats fed a HFD.MethodsMale Wistar rats were given either a chow diet or a high fat diet (HFD) for 12 weeks. After 4 weeks of the dietary intervention, half of the rats in each group began eight weeks of interval training. In vivo glucose and insulin tolerance was assessed, as was ex vivo glucose uptake in epitrochlearis muscle. Mitochondrial respiratory function was assessed in permeabilised soleus and white gastrocnemius (WG) muscles. Mitochondrial content was determined by measurement of citrate synthase (CS) activity and protein expression of components of the electron transport system (ETS).ResultsHFD rats had impaired glucose and insulin tolerance. HFD did not change CS activity in the soleus; however, it did increase CS activity in WG (Chow 5.9 ± 0.5, HFD 7.2 ± 0.7 mol h-1 kg protein-1). Protein expression of components of the ETS and mitochondrial respiratory function (WG Chow 65.2 ± 8.4, HFD 88.6 ± 8.7 pmol O2 s-1 mg-1) were also increased by HFD. Exercise training improved glucose and insulin tolerance in the HFD rats. Exercise training did not alter CS activity in either muscle. Mitochondrial respiratory function was increased with exercise training in the chow fed animals in soleus muscle, but not in WG. This exercise effect was absent in the HFD animals. Mitochondrial characteristics did not consistently correlate with insulin or glucose tolerance.Conclusions/interpretationHFD induced insulin resistance, but it did not negatively affect any of the measured mitochondrial characteristics. Exercise training improved insulin resistance, but without changes in mitochondrial respiration and content. The lack of an association between mitochondrial characteristics and insulin resistance was reinforced by the absence of strong correlations between these measures. Our results suggest that defects in mitochondrial respiration and content are not responsible for insulin resistance in HFD rats.

Download Full-text

Genetically increasing flux through β-oxidation in skeletal muscle increases mitochondrial reductive stress and glucose intolerance

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00010.2021 ◽

2021 ◽

Author(s):

Cody D. Smith ◽

Chein-Te Lin ◽

Shawna L. McMillin ◽

Luke A. Weyrauch ◽

Cameron Alan Schmidt ◽

...

Keyword(s):

Skeletal Muscle ◽

Fatty Acid ◽

Glucose Tolerance ◽

Glucose Intolerance ◽

High Fat Diet ◽

Whole Body ◽

Acid Oxidation ◽

Wild Type ◽

High Fat ◽

Redox Environment

Elevated mitochondrial H2O2 emission and an oxidative shift in cytosolic redox environment have been linked to high fat diet-induced insulin resistance in skeletal muscle. To test specifically whether increased flux through mitochondrial fatty acid oxidation, in the absence of elevated energy demand, directly alters mitochondrial function and redox state in muscle, two genetic models characterized by increased muscle β-oxidation flux were studied. In mice overexpressing peroxisome proliferator activated receptor-α in muscle (MCK-PPARα), lipid supported mitochondrial respiration, membrane potential (ΔΨm) and H2O2 production rate (JH2O2) were increased, which coincided with a more oxidized cytosolic redox environment, reduced muscle glucose uptake, and whole-body glucose intolerance despite an increased rate of energy expenditure. Similar results were observed in lipin-1 deficient, fatty-liver dystrophic mice, another model characterized by increased β-oxidation flux and glucose intolerance. Crossing MCAT (mitochondrial-targeted catalase) with MCK-PPARα mice normalized JH2O2 production, redox environment and glucose tolerance, but surprisingly both basal and absolute insulin-stimulated rates of glucose uptake in muscle remained depressed. Also surprising, when placed on a high fat diet MCK-PPARα mice were characterized by much lower whole body, fat and lean mass as well as improved glucose tolerance relative to wild-type mice, providing additional evidence that overexpression of PPARα in muscle imposes more extensive metabolic stress than experienced by wild-type mice on a high fat diet. Overall, the findings suggest that driving an increase in skeletal muscle fatty acid oxidation in the absence of metabolic demand imposes mitochondrial reductive stress and elicits multiple counterbalance metabolic responses in attempt to restore bioenergetic homeostasis.

Download Full-text