Reduced delta-6 desaturase activity partially protects against high-fat diet-induced impairment in whole-body glucose tolerance

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

Chronic Urotensin-II Administration Improves Whole-Body Glucose Tolerance in High-Fat Diet-Fed Mice

Frontiers in Endocrinology ◽

10.3389/fendo.2019.00453 ◽

2019 ◽

Vol 10 ◽

Author(s):

Xi Chen ◽

Lin Yin ◽

Wei-hua Jia ◽

Nuo-qi Wang ◽

Chun-yang Xu ◽

...

Keyword(s):

Glucose Tolerance ◽

High Fat Diet ◽

Whole Body ◽

Urotensin Ii ◽

High Fat

Download Full-text

Inactivation of SPAK kinase reduces body weight gain in mice fed a high-fat diet by improving energy expenditure and insulin sensitivity

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00108.2017 ◽

2018 ◽

Vol 314 (1) ◽

pp. E53-E65 ◽

Cited By ~ 8

Author(s):

Ivan Torre-Villalvazo ◽

Luz Graciela Cervantes-Pérez ◽

Lilia G. Noriega ◽

Jose V. Jiménez ◽

Norma Uribe ◽

...

Keyword(s):

Adipose Tissue ◽

Weight Gain ◽

Insulin Sensitivity ◽

Energy Expenditure ◽

Glucose Tolerance ◽

High Fat Diet ◽

Whole Body ◽

High Fat ◽

The Metabolic Syndrome ◽

Brown Adipose

The STE20/SPS1-related proline-alanine-rich protein kinase (SPAK) controls the activity of the electroneutral cation-chloride cotransporters (SLC12 family) and thus physiological processes such as modulation of cell volume, intracellular chloride concentration [Cl−]i, and transepithelial salt transport. Modulation of SPAK kinase activity may have an impact on hypertension and obesity, as STK39, the gene encoding SPAK, has been suggested as a hypertension and obesity susceptibility gene. In fact, the absence of SPAK activity in mice in which the activating threonine in the T loop was substituted by alanine (SPAK-KI mice) is associated with decreased blood pressure; however its consequences in metabolism have not been explored. Here, we fed wild-type and homozygous SPAK-KI mice a high-fat diet for 17 wk to evaluate weight gain, circulating substrates and hormones, energy expenditure, glucose tolerance, and insulin sensitivity. SPAK-KI mice exhibit resistance to HFD-induced obesity and hepatic steatosis associated with increased energy expenditure, higher thermogenic activity in brown adipose tissue, increased mitochondrial activity in skeletal muscle, and reduced white adipose tissue hypertrophy mediated by augmented whole body insulin sensitivity and glucose tolerance. Our data reveal a previously unrecognized role for the SPAK kinase in the regulation of energy balance, thermogenesis, and insulin sensitivity, suggesting that this kinase could be a new drug target for the treatment of obesity and the metabolic syndrome.

Download Full-text

High-fat diet-induced impairment of skeletal muscle insulin sensitivity is not prevented by SIRT1 overexpression

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00001.2014 ◽

2014 ◽

Vol 307 (9) ◽

pp. E764-E772 ◽

Cited By ~ 30

Author(s):

Amanda T. White ◽

Andrew Philp ◽

Heidi N. Fridolfsson ◽

Jan M. Schilling ◽

Anne N. Murphy ◽

...

Keyword(s):

Insulin Resistance ◽

Skeletal Muscle ◽

Energy Expenditure ◽

Glucose Tolerance ◽

Glucose Uptake ◽

High Fat Diet ◽

Sirtuin 1 ◽

Whole Body ◽

Oral Glucose ◽

High Fat

Skeletal muscle sirtuin 1 (SIRT1) expression is reduced under insulin-resistant conditions, such as those resulting from high-fat diet (HFD) feeding and obesity. Herein, we investigated whether constitutive activation of SIRT1 in skeletal muscle prevents HFD-induced muscle insulin resistance. To address this, mice with muscle-specific overexpression of SIRT1 (mOX) and wild-type (WT) littermates were fed a control diet (10% calories from fat) or HFD (60% of calories from fat) for 12 wk. Magnetic resonance imaging and indirect calorimetry were used to measure body composition and energy expenditure, respectively. Whole body glucose metabolism was assessed by oral glucose tolerance test, and insulin-stimulated glucose uptake was measured at a physiological insulin concentration in isolated soleus and extensor digitorum longus muscles. Although SIRT1 was significantly overexpressed in muscle of mOX vs. WT mice, body weight and percent body fat were similarly increased by HFD for both genotypes, and energy expenditure was unaffected by diet or genotype. Importantly, impairments in glucose tolerance and insulin-mediated activation of glucose uptake in skeletal muscle that occurred with HFD feeding were not prevented in mOX mice. In contrast, mOX mice showed enhanced postischemic cardiac functional recovery compared with WT mice, confirming the physiological functionality of the SIRT1 transgene in this mouse model. Together, these results demonstrate that activation of SIRT1 in skeletal muscle alone does not prevent HFD-induced glucose intolerance, weight gain, or insulin resistance.

Download Full-text

Short-Term High-Fat Diet Alters Substrate Utilization during Exercise but Not Glucose Tolerance in Highly Trained Athletes

International Journal of Sport Nutrition and Exercise Metabolism ◽

10.1123/ijsnem.11.3.273 ◽

2001 ◽

Vol 11 (3) ◽

pp. 273-286 ◽

Cited By ~ 10

Author(s):

Heidi M. Staudacher ◽

Andrew L. Carey ◽

Nicola K. Cummings ◽

John A. Hawley ◽

Louise M. Burke

Keyword(s):

Insulin Sensitivity ◽

Glucose Tolerance ◽

High Fat Diet ◽

Dietary Intervention ◽

Substrate Oxidation ◽

Whole Body ◽

Oral Glucose ◽

High Fat ◽

Short Term ◽

Time Curve

We determined the effect of a high-fat diet and carbohydrate (CHO) restoration on substrate oxidation and glucose tolerance in 7 competitive ultra-endurance athletes (peak oxygen uptake [V̇O2peak] 68 ± 1 ml · kg−1 · min−1; mean±SEM). For 6 days, subjects consumed a random order of a high-fat (69% fat; FAT-adapt) or a high-CHO (70% CHO; HCHO) diet, each followed by 1 day of a high-CHO diet. Treatments were separated by an 18-day wash out. Substrate oxidation was determined during submaximal cycling (20 min at 65% V̇O2peak) prior to and following the 6 day dietary interventions. Fat oxidation at baseline was not different between treatments (17.4 ± 2.1 vs. 16.1 ± 1.3 g · 20 min−1 for FAT-adapt and HCHO, respectively) but increased 34% after 6 days of FAT-adapt (to 23.3 ± 0.9 g · 20 min−1, p < .05) and decreased 30% after HCHO (to 11.3±1.4 g · 20 min−1, p < .05). Glucose tolerance, determined by the area under the plasma [glucose] versus time curve during an oral glucose tolerance (OGTT) test, was similar at baseline (545±21 vs. 520±28 mmol · L−1 · 90 min−1), after 5-d of dietary intervention (563 ± 26 vs. 520 ± 18 mmol · L−1 · 90 min−1) and after 1 d of high-CHO (491 ± 28 vs. 489 ± 22 mmol · L−1 · 90min−1 for FAT- adapt and HCHO, respectively). An index of whole-body insulin sensitivity (SI 10000/÷fasting [glucose] × fasting [insulin] × mean [glucose] during OGTT × mean [insulin] during OGTT) was similar at baseline (15 ± 2 vs. 17 ± 5 arbitrary units), after 5-d of dietary intervention (15 ± 2 vs. 15 ± 2) and after 24 h of CHO loading (17 ± 3 vs. 18 ± 2 for FAT- adapt and HCHO, respectively). We conclude that despite marked changes in the pattern of substrate oxidation during submaximal exercise, short-term adaptation to a high-fat diet does not alter whole-body glucose tolerance or an index of insulin sensitivity in highly-trained individuals.

Download Full-text

Wt1 haploinsufficiency induces browning of epididymal fat and alleviates metabolic dysfunction in mice on high-fat diet

Diabetologia ◽

10.1007/s00125-021-05621-1 ◽

2021 ◽

Author(s):

Karin M. Kirschner ◽

Anna Foryst-Ludwig ◽

Sabrina Gohlke ◽

Chen Li ◽

Roberto E. Flores ◽

...

Keyword(s):

Metabolic Disease ◽

Adipose Tissue ◽

Glucose Tolerance ◽

Knockout Mice ◽

High Fat Diet ◽

Whole Body ◽

Mrna Levels ◽

Wild Type ◽

High Fat ◽

Fat Depots

Abstract Aims/hypothesis Despite a similar fat storing function, visceral (intra-abdominal) white adipose tissue (WAT) is detrimental, whereas subcutaneous WAT is considered to protect against metabolic disease. Recent findings indicate that thermogenic genes, expressed in brown adipose tissue (BAT), can be induced primarily in subcutaneous WAT. Here, we investigate the hypothesis that the Wilms tumour gene product (WT1), which is expressed in intra-abdominal WAT but not in subcutaneous WAT and BAT, suppresses a thermogenic program in white fat cells. Methods Heterozygous Wt1 knockout mice and their wild-type littermates were examined in terms of thermogenic and adipocyte-selective gene expression. Glucose tolerance and hepatic lipid accumulation in these mice were assessed under normal chow and high-fat diet conditions. Pre-adipocytes isolated from the stromal vascular fraction of BAT were transduced with Wt1-expressing retrovirus, induced to differentiate and analysed for the expression of thermogenic and adipocyte-selective genes. Results Expression of the thermogenic genes Cpt1b and Tmem26 was enhanced and transcript levels of Ucp1 were on average more than tenfold higher in epididymal WAT of heterozygous Wt1 knockout mice compared with wild-type mice. Wt1 heterozygosity reduced epididymal WAT mass, improved whole-body glucose tolerance and alleviated severe hepatic steatosis upon diet-induced obesity in mice. Retroviral expression of WT1 in brown pre-adipocytes, which lack endogenous WT1, reduced mRNA levels of Ucp1, Ppargc1a, Cidea, Prdm16 and Cpt1b upon in vitro differentiation by 60–90%. WT1 knockdown in epididymal pre-adipocytes significantly lowered Aldh1a1 and Zfp423 transcripts, two key suppressors of the thermogenic program. Conversely, Aldh1a1 and Zfp423 mRNA levels were increased approximately five- and threefold, respectively, by retroviral expression of WT1 in brown pre-adipocytes. Conclusion/interpretation WT1 functions as a white adipocyte determination factor in epididymal WAT by suppressing thermogenic genes. Reducing Wt1 expression in this and other intra-abdominal fat depots may represent a novel treatment strategy in metabolic disease. Graphical abstract

Download Full-text

Antisense oligonucleotides against monoacylglycerol acyltransferase 1 (Mogat1) improve glucose metabolism independently of Mogat1

10.1101/2020.08.05.238535 ◽

2020 ◽

Author(s):

Andrew J. Lutkewitte ◽

Jason M. Singer ◽

Trevor M. Shew ◽

Michael R. Martino ◽

Angela M. Hall ◽

...

Keyword(s):

Insulin Resistance ◽

Insulin Sensitivity ◽

Glucose Metabolism ◽

Glucose Tolerance ◽

High Fat Diet ◽

Hepatic Insulin Resistance ◽

Whole Body ◽

High Fat ◽

Target Effects ◽

Monoacylglycerol Acyltransferase

ABSTRACTObjectiveMonoacylglycerol acyltransferase (MGAT) enzymes catalyze the synthesis of diacylglycerol from monoacylglycerol. Previous work has suggested the importance of MGAT activity in the development of obesity-related hepatic insulin resistance. Indeed, antisense oligonucleotide (ASO)-mediated knockdown of the gene encoding MGAT1, Mogat1, reduced hepatic MGAT activity and improved glucose tolerance and insulin resistance in high fat diet (HFD) fed mice. However, recent work has suggested that some ASOs may have off-target effects on body weight and metabolic parameters via activation of the interferon alpha/beta receptor 1 (IFNAR-1) pathway.MethodsMice with whole-body Mogat1 knockout or a floxed allele for Mogat1 to allow for liver-specific Mogat1-knockout (by either a liver-specific transgenic or adeno-associated virus-driven Cre recombinase) were generated. These mice were placed on a high fat diet and glucose metabolism and insulin sensitivity was assessed after 16 weeks on diet. In some experiments, mice were treated with control or Mogat1 or control ASOs in the presence or absence of IFNAR-1 neutralizing antibody.ResultsGenetic deletion of hepatic Mogat1, either acutely or chronically, did not improve hepatic steatosis, glucose tolerance, or insulin sensitivity in HFD-fed mice. Furthermore, constitutive Mogat1 knockout in all tissues actually exacerbated HFD-induced weight gain, insulin resistance, and glucose intolerance on a HFD. Despite markedly reduced Mogat1 expression, liver MGAT activity was unaffected in all knockout mouse models. Mogat1 overexpression hepatocytes increased liver MGAT activity and TAG content in low-fat fed mice, but did not cause insulin resistance. Interestingly, Mogat1 ASO treatment improved glucose tolerance in both wild-type and Mogat1 null mice, suggesting an off target effect. Inhibition of IFNAR-1 did not block the effect of Mogat1 ASO on glucose homeostasis.ConclusionThese results indicate that genetic loss of Mogat1 does not affect hepatic MGAT activity or metabolic homeostasis on HFD and show that Mogat1 ASOs improve glucose metabolism through effects independent of targeting Mogat1 or activation of IFNAR-1 signaling.Abstract FigureHighlightsMogat1 liver-specific KO or KD does not improve metabolism in HFD fed mice.Whole-body Mogat1-deletion impairs insulin tolerance in HFD fed mice.Mogat1 ASOs improves whole body metabolism independently of gene knockdown.Blockade of the INFR response does not prevent off-target effects of Mogat1 ASOs.

Download Full-text

Methionine restriction plus overload improves skeletal muscle and metabolic health in old mice on a high fat diet

Scientific Reports ◽

10.1038/s41598-021-81037-6 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Anandini Swaminathan ◽

Andrej Fokin ◽

Tomas Venckūnas ◽

Hans Degens

Keyword(s):

Skeletal Muscle ◽

Glucose Tolerance ◽

Muscle Mass ◽

Body Mass ◽

High Fat Diet ◽

Control Diet ◽

Metabolic Health ◽

High Fat ◽

Methionine Restriction ◽

Old Mice

AbstractMethionine restriction (MR) has been shown to reduce the age-induced inflammation. We examined the effect of MR (0.17% methionine, 10% kCal fat) and MR + high fat diet (HFD) (0.17% methionine, 45% kCal fat) on body mass, food intake, glucose tolerance, resting energy expenditure, hind limb muscle mass, denervation-induced atrophy and overload-induced hypertrophy in young and old mice. In old mice, MR and MR + HFD induced a decrease in body mass. Muscle mass per body mass was lower in old compared to young mice. MR restored some of the HFD-induced reduction in muscle oxidative capacity. The denervation-induced atrophy of the m. gastrocnemius was larger in animals on MR than on a control diet, irrespective of age. Old mice on MR had larger hypertrophy of m. plantaris. Irrespective of age, MR and MR + HFD had better glucose tolerance compared to the other groups. Young and old mice on MR + HFD had a higher resting VO2 per body mass than HFD group. Mice on MR and MR + HFD had a resting respiratory quotient closer to 0.70, irrespective of age, indicating an increased utilization of lipids. In conclusion, MR in combination with resistance training may improve skeletal muscle and metabolic health in old age even in the face of obesity.

Download Full-text

Distinct Effects of a High Fat Diet on Bone in Skeletally Mature and Developing Male C57BL/6J Mice

Nutrients ◽

10.3390/nu13051666 ◽

2021 ◽

Vol 13 (5) ◽

pp. 1666

Author(s):

Dean S. Ross ◽

Tzu-Hsuan Yeh ◽

Shalinie King ◽

Julia Mathers ◽

Mark S. Rybchyn ◽

...

Keyword(s):

Glucose Tolerance ◽

Bone Formation ◽

Glucose Intolerance ◽

High Fat Diet ◽

Age Groups ◽

Oral Glucose ◽

Rna Expression ◽

High Fat ◽

Mineral Density ◽

Skeletal Fragility

Increased risks of skeletal fractures are common in patients with impaired glucose handling and type 2 diabetes mellitus (T2DM). The pathogenesis of skeletal fragility in these patients remains ill-defined as patients present with normal to high bone mineral density. With increasing cases of glucose intolerance and T2DM it is imperative that we develop an accurate rodent model for further investigation. We hypothesized that a high fat diet (60%) administered to developing male C57BL/6J mice that had not reached skeletal maturity would over represent bone microarchitectural implications, and that skeletally mature mice would better represent adult-onset glucose intolerance and the pre-diabetes phenotype. Two groups of developing (8 week) and mature (12 week) male C57BL/6J mice were placed onto either a normal chow (NC) or high fat diet (HFD) for 10 weeks. Oral glucose tolerance tests were performed throughout the study period. Long bones were excised and analysed for ex vivo biomechanical testing, micro-computed tomography, 2D histomorphometry and gene/protein expression analyses. The HFD increased fasting blood glucose and significantly reduced glucose tolerance in both age groups by week 7 of the diets. The HFD reduced biomechanical strength, both cortical and trabecular indices in the developing mice, but only affected cortical outcomes in the mature mice. Similar results were reflected in the 2D histomorphometry. Tibial gene expression revealed decreased bone formation in the HFD mice of both age groups, i.e., decreased osteocalcin expression and increased sclerostin RNA expression. In the mature mice only, while the HFD led to a non-significant reduction in runt-related transcription factor 2 (Runx2) RNA expression, this decrease became significant at the protein level in the femora. Our mature HFD mouse model more accurately represents late-onset impaired glucose tolerance/pre-T2DM cases in humans and can be used to uncover potential insights into reduced bone formation as a mechanism of skeletal fragility in these patients.

Download Full-text

Partial Deficiency of Zfp217 Resists High-Fat Diet-Induced Obesity by Increasing Energy Metabolism in Mice

International Journal of Molecular Sciences ◽

10.3390/ijms22105390 ◽

2021 ◽

Vol 22 (10) ◽

pp. 5390

Author(s):

Qianhui Zeng ◽

Nannan Wang ◽

Yaru Zhang ◽

Yuxuan Yang ◽

Shuangshuang Li ◽

...

Keyword(s):

Adipose Tissue ◽

Weight Gain ◽

Insulin Sensitivity ◽

Energy Metabolism ◽

Glucose Tolerance ◽

High Fat Diet ◽

Chow Diet ◽

High Fat ◽

Glycolipid Metabolism ◽

Partial Deficiency

Obesity-induced adipose tissue dysfunction and disorders of glycolipid metabolism have become a worldwide research priority. Zfp217 plays a crucial role in adipogenesis of 3T3-L1 preadipocytes, but about its functions in animal models are not yet clear. To explore the role of Zfp217 in high-fat diet (HFD)-induced obese mice, global Zfp217 heterozygous knockout (Zfp217+/−) mice were constructed. Zfp217+/− mice and Zfp217+/+ mice fed a normal chow diet (NC) did not differ significantly in weight gain, percent body fat mass, glucose tolerance, or insulin sensitivity. When challenged with HFD, Zfp217+/− mice had less weight gain than Zfp217+/+ mice. Histological observations revealed that Zfp217+/− mice fed a high-fat diet had much smaller white adipocytes in inguinal white adipose tissue (iWAT). Zfp217+/− mice had improved metabolic profiles, including improved glucose tolerance, enhanced insulin sensitivity, and increased energy expenditure compared to the Zfp217+/+ mice under HFD. We found that adipogenesis-related genes were increased and metabolic thermogenesis-related genes were decreased in the iWAT of HFD-fed Zfp217+/+ mice compared to Zfp217+/− mice. In addition, adipogenesis was markedly reduced in mouse embryonic fibroblasts (MEFs) from Zfp217-deleted mice. Together, these data indicate that Zfp217 is a regulator of energy metabolism and it is likely to provide novel insight into treatment for obesity.

Download Full-text