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Zhang H, Zhao C, Hou J, Su P, Yang Y, Xia B, Zhao X, He R, Wang L, Cao C, Liu T, Tian J. Red ginseng extract improves skeletal muscle energy metabolism and mitochondrial function in chronic fatigue mice. Front Pharmacol 2022; 13:1077249. [PMID: 36618917 PMCID: PMC9816794 DOI: 10.3389/fphar.2022.1077249] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2022] [Accepted: 12/13/2022] [Indexed: 12/24/2022] Open
Abstract
Background: Skeletal muscles are organs with high energy requirements, especially during vigorous exercise. Adequate mitochondrial function is essential to meet the high energy needs of skeletal muscle cells. Recent studies have reported that red ginseng can significantly improve chronic fatigue; however, the specific mechanism of action is still not clear. Methods: A chronic fatigue syndrome mouse model was developed using C57BL/6J mice through long-term compound stimulation of stress factors. Following this, the animals were orally administered 200, 400, or 600 mg/kg red ginseng extracts for 28 days. Skeletal muscle lactate acid, serum lactate dehydrogenase, urea concentrations, ATP level, mitochondrial membrane potential, activities of Na+-K+-ATPase and cytochrome c oxidase were determined using assay kits or an automatic biochemical analyser detection system. Skeletal muscle mitochondria morphology was observed using electron microscopy and the expression of p-AMPK, PGC-1α, ACO2 and complex I in skeletal muscle protein was determined by western blotting. Results: Oral administration of 400 or 600 mg/kg red ginseng extract in mice with chronic fatigue reduced lactic acid, lactate dehydrogenase and urea, rescued the density and morphology of skeletal muscle mitochondria, increased the activities of Na+-K+-ATPase and cytochrome c oxidase, and activated the AMPK/PGC-1α cascade pathway, resulting in improved skeletal muscle mitochondrial function by restoring ATP level, mitochondrial membrane potential, complex I and mitochondrial biogenesis. Conclusion: The anti-fatigue effects of red ginseng are partly related to its potent mitochondrial improving activity, including decreasing mitochondrial swelling and mitochondrial membrane permeability, increasing mitochondrial biogenesis, thus ameliorating mitochondrial dysfunction.
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Affiliation(s)
- Haijing Zhang
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, China
| | - Chunhui Zhao
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, China
| | - Jinli Hou
- Experimental Research Center, China Academy of Chinese Medical Sciences, Beijing, China
| | - Ping Su
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, China
| | - Yifei Yang
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, China
| | - Bing Xia
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, China
| | - Xiaoang Zhao
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, China
| | - Rong He
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, China
| | - Lifang Wang
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, China
| | - Chunyu Cao
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, China
| | - Ting Liu
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, China,*Correspondence: Ting Liu, ; Jixiang Tian,
| | - Jixiang Tian
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, China,*Correspondence: Ting Liu, ; Jixiang Tian,
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Iliuta IA, Song X, Pickel L, Haghighi A, Retnakaran R, Scholey J, Sung HK, Steinberg GR, Pei Y. Shared pathobiology identifies AMPK as a therapeutic target for obesity and autosomal dominant polycystic kidney disease. Front Mol Biosci 2022; 9:962933. [PMID: 36106024 PMCID: PMC9467623 DOI: 10.3389/fmolb.2022.962933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 07/21/2022] [Indexed: 12/02/2022] Open
Abstract
Autosomal dominant polycystic kidney disease (ADPKD) is the most common Mendelian kidney disease, affecting approximately one in 1,000 births and accounting for 5% of end-stage kidney disease in developed countries. The pathophysiology of ADPKD is strongly linked to metabolic dysregulation, which may be secondary to defective polycystin function. Overweight and obesity are highly prevalent in patients with ADPKD and constitute an independent risk factor for progression. Recent studies have highlighted reduced AMP-activated protein kinase (AMPK) activity, increased mammalian target of rapamycin (mTOR) signaling, and mitochondrial dysfunction as shared pathobiology between ADPKD and overweight/obesity. Notably, mTOR and AMPK are two diametrically opposed sensors of energy metabolism that regulate cell growth and proliferation. However, treatment with the current generation of mTOR inhibitors is poorly tolerated due to their toxicity, making clinical translation difficult. By contrast, multiple preclinical and clinical studies have shown that pharmacological activation of AMPK provides a promising approach to treat ADPKD. In this narrative review, we summarize the pleiotropic functions of AMPK as a regulator of cellular proliferation, macromolecule metabolism, and mitochondrial biogenesis, and discuss the potential for pharmacological activation of AMPK to treat ADPKD and obesity-related kidney disease.
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Affiliation(s)
- Ioan-Andrei Iliuta
- Division of Nephrology, Department of Medicine, University Health Network and University of Toronto, Toronto, ON, Canada
| | - Xuewen Song
- Division of Nephrology, Department of Medicine, University Health Network and University of Toronto, Toronto, ON, Canada
| | - Lauren Pickel
- Translational Medicine Program, The Hospital for Sick Children, Toronto, ON, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
| | - Amirreza Haghighi
- Division of Nephrology, Department of Medicine, University Health Network and University of Toronto, Toronto, ON, Canada
- Division of Genetics, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, United States
| | - Ravi Retnakaran
- Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, ON, Canada
| | - James Scholey
- Division of Nephrology, Department of Medicine, University Health Network and University of Toronto, Toronto, ON, Canada
| | - Hoon-Ki Sung
- Translational Medicine Program, The Hospital for Sick Children, Toronto, ON, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
| | - Gregory R. Steinberg
- Department of Medicine, Centre for Metabolism, Obesity, and Diabetes Research, McMaster University, Hamilton, ON, Canada
| | - York Pei
- Division of Nephrology, Department of Medicine, University Health Network and University of Toronto, Toronto, ON, Canada
- *Correspondence: York Pei,
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de Meeûs d'Argenteuil C, Boshuizen B, Vidal Moreno de Vega C, Leybaert L, de Maré L, Goethals K, De Spiegelaere W, Oosterlinck M, Delesalle C. Comparison of Shifts in Skeletal Muscle Plasticity Parameters in Horses in Three Different Muscles, in Answer to 8 Weeks of Harness Training. Front Vet Sci 2021; 8:718866. [PMID: 34733900 PMCID: PMC8558477 DOI: 10.3389/fvets.2021.718866] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 09/07/2021] [Indexed: 12/02/2022] Open
Abstract
Training-induced follow-up of multiple muscle plasticity parameters in postural stability vs. locomotion muscles provides an integrative physiological view on shifts in the muscular metabolic machinery. It can be expected that not all muscle plasticity parameters show the same expression time profile across muscles. This knowledge is important to underpin results of metabolomic studies. Twelve non-competing Standardbred mares were subjected to standardized harness training. Muscle biopsies were taken on a non-training day before and after 8 weeks. Shifts in muscle fiber type composition and muscle fiber cross-sectional area (CSA) were compared in the m. pectoralis, the m. vastus lateralis, and the m. semitendinosus. In the m. vastus lateralis, which showed most pronounced training-induced plasticity, two additional muscle plasticity parameters (capillarization and mitochondrial density) were assessed. In the m. semitendinosus, additionally the mean minimum Feret's diameter was assessed. There was a significant difference in baseline profiles. The m. semitendinosus contained less type I and more type IIX fibers compatible with the most pronounced anaerobic profile. Though no baseline fiber type-specific and overall mean CSA differences could be detected, there was a clear post-training decrease in fiber type specific CSA, most pronounced for the m. vastus lateralis, and this was accompanied by a clear increase in capillary supply. No shifts in mitochondrial density were detected. The m. semitendinosus showed a decrease in fiber type specific CSA of type IIAX fibers and a decrease of type I fiber Feret's diameter as well as mean minimum Feret's diameter. The training-induced increased capillary supply in conjunction with a significant decrease in muscle fiber CSA suggests that the muscular machinery models itself toward an optimal smaller individual muscle fiber structure to receive and process fuels that can be swiftly delivered by the circulatory system. These results are interesting in view of the recently identified important fuel candidates such as branched-chain amino acids, aromatic amino acids, and gut microbiome-related xenobiotics, which need a rapid gut-muscle gateway to reach these fibers and are less challenging for the mitochondrial system. More research is needed with that respect. Results also show important differences between muscle groups with respect to baseline and training-specific modulation.
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Affiliation(s)
- Constance de Meeûs d'Argenteuil
- Department of Translational Physiology, Infectiology and Public Health, Research Group of Comparative Physiology, Faculty of Veterinary Medicine, Research Group of Comparative Physiology, Ghent University, Merelbeke, Belgium
| | - Berit Boshuizen
- Department of Translational Physiology, Infectiology and Public Health, Research Group of Comparative Physiology, Faculty of Veterinary Medicine, Research Group of Comparative Physiology, Ghent University, Merelbeke, Belgium
- Wolvega Equine Hospital, Oldeholtpade, Netherlands
| | - Carmen Vidal Moreno de Vega
- Department of Translational Physiology, Infectiology and Public Health, Research Group of Comparative Physiology, Faculty of Veterinary Medicine, Research Group of Comparative Physiology, Ghent University, Merelbeke, Belgium
| | - Luc Leybaert
- Department of Basic and Applied Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
| | - Lorie de Maré
- Department of Translational Physiology, Infectiology and Public Health, Research Group of Comparative Physiology, Faculty of Veterinary Medicine, Research Group of Comparative Physiology, Ghent University, Merelbeke, Belgium
| | - Klara Goethals
- Department of Veterinary and Biosciences, Faculty of Veterinary Medicine, Research Group Biometrics, Ghent University, Merelbeke, Belgium
| | - Ward De Spiegelaere
- Department of Morphology, Imaging, Orthopedics, Rehabilitation and Nutrition, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Maarten Oosterlinck
- Department of Large Animal Surgery, Anaesthesia and Orthopaedics, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Cathérine Delesalle
- Department of Translational Physiology, Infectiology and Public Health, Research Group of Comparative Physiology, Faculty of Veterinary Medicine, Research Group of Comparative Physiology, Ghent University, Merelbeke, Belgium
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Li Y, Wang B, Shen J, Bai M, Xu E. Berberine attenuates fructose-induced insulin resistance by stimulating the hepatic LKB1/AMPK/PGC1α pathway in mice. PHARMACEUTICAL BIOLOGY 2020; 58:385-392. [PMID: 32393087 PMCID: PMC7269079 DOI: 10.1080/13880209.2020.1756349] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 03/02/2020] [Accepted: 04/03/2020] [Indexed: 05/22/2023]
Abstract
Context: Berberine is an alkaloid that possesses various pharmacologic effects.Objective: To explore the mechanism of berberine to improve insulin sensitivity in fructose-fed mice.Materials and methods: Sixty male ICR mice were randomly divided into 6 groups (10 mice in each group): control, fructose, pioglitazone (10 mg/kg) and berberine (50, 100, and 200 mg/kg). Except for the control group, the mice received 20% fructose drinking for 10 weeks. Pioglitazone and berberine were orally administered once daily during the last 4 weeks. The insulin sensitivity was evaluated using an oral glucose tolerance test (OGTT). The serum levels of fasting glucose and insulin, blood lipids, and hormones were determined. The hepatic AMP and ATP contents were detected using high performance liquid chromatography (HPLC) analysis, and the protein expression was examined by immunoblotting.Results: Berberine significantly reversed the insulin resistance induced by fructose, including lowering fasting insulin levels (from 113.9 to 67.4) and area under the curve (AUC) during OGTT (from 1310 to 1073), decreasing serum leptin (from 0.28 to 0.13) and increasing serum adiponectin levels (from 1.50 to 2.80). Moreover, berberine enhanced the phosphorylation levels of protein kinase B (PKB/AKT; 2.27-fold) and glycogen synthase kinase-3β (GSK3β; 2.56-fold), and increased hepatic glycogen content (from 0.19 to 1.65). Furthermore, berberine upregulated the protein expression of peroxisome proliferator activated receptor gamma coactivator 1α (PGC1α; 2.61-fold), phospho-AMP-activated protein kinase (p-AMPK; 1.35-fold) and phospho-liver kinase B1 (p-LKB1; 1.41-fold), whereas it decreased the AMP/ATP ratio (from 4.25 to 1.82).Conclusion: The present study demonstrated the protective effects of berberine against insulin resistance induced by fructose. Our findings may provide an experimental basis for the application of berberine in the treatment of insulin resistance.
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Affiliation(s)
- Yucheng Li
- Henan Key Laboratory for Modern Research on Zhongjing’s Herbal Formulae, Scientific Research and Experiment Center, Henan University of Chinese Medicine, Zhengzhou, Henan, PR China
| | - Baoying Wang
- Henan Key Laboratory for Modern Research on Zhongjing’s Herbal Formulae, Scientific Research and Experiment Center, Henan University of Chinese Medicine, Zhengzhou, Henan, PR China
| | - Jiduo Shen
- College of Pharmacy, Henan University of Chinese Medicine, Zhengzhou, Henan, PR China
| | - Ming Bai
- Henan Key Laboratory for Modern Research on Zhongjing’s Herbal Formulae, Scientific Research and Experiment Center, Henan University of Chinese Medicine, Zhengzhou, Henan, PR China
- CONTACT Ming Bai
| | - Erping Xu
- Henan Key Laboratory for Modern Research on Zhongjing’s Herbal Formulae, Scientific Research and Experiment Center, Henan University of Chinese Medicine, Zhengzhou, Henan, PR China
- Erping Xu Henan Key Laboratory for Modern Research on Zhongjing’s Herbal Formulae, Scientific Research and Experiment Center, Henan University of Chinese Medicine, Zhengzhou, Henan, PR China
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Fan L, Cacicedo JM, Ido Y. Impaired nicotinamide adenine dinucleotide (NAD + ) metabolism in diabetes and diabetic tissues: Implications for nicotinamide-related compound treatment. J Diabetes Investig 2020; 11:1403-1419. [PMID: 32428995 PMCID: PMC7610120 DOI: 10.1111/jdi.13303] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 05/13/2020] [Accepted: 05/14/2020] [Indexed: 01/08/2023] Open
Abstract
One of the biochemical abnormalities found in diabetic tissues is a decrease in the cytosolic oxidized to reduced forms of the nicotinamide adenine dinucleotide ratio (NAD+/NADH also known as pseudohypoxia) caused by oxidation of excessive substrates (glucose through the polyol pathway, free fatty acids and lactate). Subsequently, a decline in NAD+ levels as a result of the activation of poly adenine nucleotide diphosphate‐ribose polymerase (mainly in type 1 diabetes) or the inhibition of adenine nucleotide monophosphate‐activated protein kinase (in type 2 diabetes). Thus, replenishment of NAD+ levels by nicotinamide‐related compounds could be beneficial. However, these compounds also increase nicotinamide catabolites that cause oxidative stress. This is particularly troublesome for patients with diabetes, because they have impaired nicotinamide salvage pathway reactions at the level of nicotinamide phosphoribosyl transferase and phosphoribosyl pyrophosphate, which occurs by the following mechanisms. First, phosphoribosyl pyrophosphate synthesis from pentose phosphate pathway is compromised by a decrease in plasma thiamine and transketolase activity. Second, nicotinamide phosphoribosyl transferase expression is decreased because of reduced adenosine monophosphate‐activated protein kinase activity, which occurs in type 2 diabetes. The adenosine monophosphate‐activated protein kinase inhibition is caused by an activation of protein kinase C and D1 as a result of enhanced diacylglycerol synthesis caused by pseudohypoxia and increased fatty acids levels. In this regard, nicotinamide‐related compounds should be given with caution to treat diabetes. To minimize the risk and maximize the benefit, nicotinamide‐related compounds should be taken with insulin sensitizers (for type 2 diabetes), polyphenols, benfotiamine, acetyl‐L‐carnitine and aldose reductase inhibitors. The efficacy of these regimens can be monitored by measuring serum NAD+ and urinary nicotinamide catabolites.
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Affiliation(s)
- Lan Fan
- Boston University School of Medicine, Boston, Massachusetts, USA
| | - Jose M Cacicedo
- Boston University School of Medicine, Boston, Massachusetts, USA
| | - Yasuo Ido
- Boston University School of Medicine, Boston, Massachusetts, USA
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Perry CGR, Hawley JA. Molecular Basis of Exercise-Induced Skeletal Muscle Mitochondrial Biogenesis: Historical Advances, Current Knowledge, and Future Challenges. Cold Spring Harb Perspect Med 2018; 8:cshperspect.a029686. [PMID: 28507194 DOI: 10.1101/cshperspect.a029686] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We provide an overview of groundbreaking studies that laid the foundation for our current understanding of exercise-induced mitochondrial biogenesis and its contribution to human skeletal muscle fitness. We highlight the mechanisms by which skeletal muscle responds to the acute perturbations in cellular energy homeostasis evoked by a single bout of endurance-based exercise and the adaptations resulting from the repeated demands of exercise training that ultimately promote mitochondrial biogenesis through hormetic feedback loops. Despite intense research efforts to elucidate the cellular mechanisms underpinning mitochondrial biogenesis in skeletal muscle, translating this basic knowledge into improved metabolic health at the population level remains a future challenge.
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Affiliation(s)
- Christopher G R Perry
- School of Kinesiology and Health Science, Muscle Health Research Centre, York University, Toronto, Ontario M3J 1P3, Canada
| | - John A Hawley
- Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne 3000, Australia.,Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Merseyside L3 5UA, United Kingdom
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Zhao L, Zou T, Gomez NA, Wang B, Zhu MJ, Du M. Raspberry alleviates obesity-induced inflammation and insulin resistance in skeletal muscle through activation of AMP-activated protein kinase (AMPK) α1. Nutr Diabetes 2018; 8:39. [PMID: 29961765 PMCID: PMC6026595 DOI: 10.1038/s41387-018-0049-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 05/23/2018] [Indexed: 12/21/2022] Open
Abstract
OBJECTIVE Through dynamic means, etiological factors, including chronic inflammation and insulin resistance have the potential to perpetuate metabolic incidences such as type 2 diabetes and obesity. Abatement of such syndromes can be achieved by complex mechanisms initiated through bioactive compounds such as polyphenols derived from fruits. Using a whole-fruit approach, the effects of dietary red raspberry, which is rich in polyphenols, on inflammatory responses and insulin resistance in the skeletal muscles of Mus musculus were studied along with the potential role of AMP-activated protein kinase (AMPK) to act as a key mediator. SUBJECTS Wild-type (WT) mice and mice deficient in the catalytic subunit (α1) of AMPK (AMPKα1-/-) were fed with a high-fat diet (HFD) or HFD supplemented with raspberry (5% dry weight) for 10 weeks. Factors involved in inflammatory responses, insulin signaling transduction, and mitochondrial biogenesis were evaluated. RESULTS Dietary raspberry reduced ectopic lipid storage, alleviated inflammation responses, improved whole-body insulin sensitivity, and promoted mitochondrial biogenesis in the skeletal muscle of WT mice, but not AMPKα1-/- mice. CONCLUSIONS AMPKα1 is an important mediator for the beneficial effects of raspberry through alleviating inflammatory responses and sensitizing insulin signaling in skeletal muscle of HFD-fed mice.
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Affiliation(s)
- Liang Zhao
- Department of Animal Sciences, Nutrigenomics and Growth Biology laboratory, Washington State University, Pullman, WA, 99164, USA
| | - Tiande Zou
- Department of Animal Sciences, Nutrigenomics and Growth Biology laboratory, Washington State University, Pullman, WA, 99164, USA
- Jiangxi Province Key Laboratory of Animal Nutrition, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, Jiangxi, 330045, China
| | - Noe Alberto Gomez
- Department of Animal Sciences, Nutrigenomics and Growth Biology laboratory, Washington State University, Pullman, WA, 99164, USA
| | - Bo Wang
- Department of Animal Sciences, Nutrigenomics and Growth Biology laboratory, Washington State University, Pullman, WA, 99164, USA
| | - Mei-Jun Zhu
- School of Food Sciences, Washington State University, Pullman, WA, 99164, USA
| | - Min Du
- Department of Animal Sciences, Nutrigenomics and Growth Biology laboratory, Washington State University, Pullman, WA, 99164, USA.
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science & Nutritional Engineering, China Agricultural University, Beijing, 100194, China.
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Bae JY, Woo J, Kang S, Shin KO. Effects of detraining and retraining on muscle energy-sensing network and meteorin-like levels in obese mice. Lipids Health Dis 2018; 17:97. [PMID: 29703203 PMCID: PMC5924483 DOI: 10.1186/s12944-018-0751-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 04/19/2018] [Indexed: 11/16/2022] Open
Abstract
Background Increased intramuscular peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) with exercise directly or indirectly affects other tissues, but the effector pathway of PGC-1α has not been clearly elucidated. The purpose of this study was to investigate the effect of exercise and/or dietary change on the protein levels of the soleus muscle energy-sensing network and meteorin-like (Metrnl), and additionally to analyze the detraining and retraining effects in high-fat diet (HFD)-induced obese mice. Methods One hundred male C57BL/6 mice were divided into normal-diet + sedentary (CO, n = 20) and HFD + sedentary (HF, n = 80) groups, and obesity was induced in the HF group through consumption of a 45% HFD for 6 weeks. The HF group was subdivided into HF only (n = 20), HF + training (HFT, n = 20), dietary change + sedentary (HFND, n = 20), and HFND + training (HFNDT, n = 20) groups, and the mice in the training groups underwent a treadmill training for 8 weeks, 5 times per week, 40 min per day. The HFT and HFNDT groups underwent 8-week training, 8-week detraining, and 4-week retraining. Results An 8-week training was effective in increasing the protein levels of soleus muscle AMP-activated protein kinase (AMPK), PGC-1α, and plasma Metrnl in the obese mice (P < 0.05). Moreover, exercise in obesity reduced body weight (P < 0.05), and exercise with dietary conversion was effective in reducing body weight (P < 0.05) and fat mass (P < 0.05) after 8-week training. 8-week detraining restored the increased protein level to the pre-exercise state, but, the previous exercise effect in body weight and fat mass (P < 0.05) of the HFNDT group remained until the end of 4-week detraining. 4-week retraining was effective in increasing the protein levels of soleus muscle AMPK, PGC-1α, blood Metrnl (P < 0.05), and reducing in body weight (P < 0.05) and fat mass (P < 0.05), when retraining with dietary change. Conclusions The results of this study suggest that regular exercise is indispensable to reduce body weight and fat mass through upregulation of the muscle energy-sensing network and Metrnl protein levels, and retraining with dietary change is necessary to obtain the retraining effects more quickly. Electronic supplementary material The online version of this article (10.1186/s12944-018-0751-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ju Yong Bae
- Laboratory of Exercise Biochemistry, Department of Physical Education, College of Arts and Physical Education, Dong-A University, 37 Nakdong-daero 550 beon-gil, Hadan-dong, Saha-gu, Busan, 604-714, Republic of Korea
| | - Jinhee Woo
- Laboratory of Exercise Biochemistry, Department of Physical Education, College of Arts and Physical Education, Dong-A University, 37 Nakdong-daero 550 beon-gil, Hadan-dong, Saha-gu, Busan, 604-714, Republic of Korea
| | - Sunghwun Kang
- Laboratory of Exercise Physiology, Division of Sport Science, Kangwon National University, 1 Kangwondaehak-gil, Chuncheon-si, Gangwon-do, 24341, Republic of Korea
| | - Ki Ok Shin
- Laboratory of Exercise Biochemistry, Department of Physical Education, College of Arts and Physical Education, Dong-A University, 37 Nakdong-daero 550 beon-gil, Hadan-dong, Saha-gu, Busan, 604-714, Republic of Korea.
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9
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Liu Y, Zhao YB, Wang SW, Zhou Y, Tang ZS, Li F. Mulberry granules protect against diabetic cardiomyopathy through the AMPK/Nrf2 pathway. Int J Mol Med 2017; 40:913-921. [PMID: 28677741 DOI: 10.3892/ijmm.2017.3050] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 05/15/2017] [Indexed: 11/06/2022] Open
Abstract
Mulberry granules (MLD) is a traditional Chinese medicine prescription that has been used in the treatment of diabetes for many years. Recently, we found that MLD protected the heart from diabetes-associated cardiomyopathy when it was used to treat diabetes. However, the beneficial effects and possible mechanism remain unknown. To elucidate these effects, an experimental myocardial ischemia/reperfusion (MI/R) injury model in diabetes rats was used in this study. Male C57BL/6 mice were injected with streptozotocin to induce diabetes. The mice were pretreated with MLD for one month, and then exposed to 30 min of ischemia followed by 24 h of reperfusion. Infarct size, heart function and various cytokines in the heart were assessed. Expression of AMP-activated protein kinase (AMPK) and nuclear factor erythroid 2‑related factor 2 (Nrf2) were investigated by western blotting. In vitro, MLD significantly cleared oxygen-free radicals in DPPH and luminol chemiluminescence models. In vivo, fasting blood glucose, fasting blood insulin and lipids were significantly decreased by MLD. The results showed that MLD improved the cardiac function and decreased myocardial infarct size in the diabetic mice subjected to MI/R. In addition, upon pretreatment with MLD before MI/R treatment, GSH, SOD, CAT and GR were significantly increased in a dose-dependent manner. Pretreatment with MLD also significantly induced the expression of Nrf2, and the cardioprotective effects of MLD were abolished in Nrf2-knockout mice. Furthermore, we also found that AMPK increase is upstream and was required for Nrf2 activation mediated by MLD. In conclusion, MLD protects against diabetic-associated cardiomyopathy by suppressing oxidative stress induced by hyperglycemia and MI/R through the AMPK/Nrf2 signaling pathway.
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Affiliation(s)
- Yang Liu
- School of Pharmacy, Shaanxi University of Chinese Medicine, Xianyang, Shaanxi 712000, P.R. China
| | - Yan-Bo Zhao
- Department of Emergency, Renmin Hospital, Hubei University of Medicine, Shiyan, Hubei 442000, P.R. China
| | - Si-Wang Wang
- Department of Natural Medicine, School of Pharmacy, The Fourth Military Medical University, Xi'an, Shaanxi 710032, P.R. China
| | - Yu Zhou
- Department of Otorhinolaryngology, The People's Hospital of Ankang, Ankang, Shaanxi 725000, P.R. China
| | - Zhi-Shu Tang
- School of Pharmacy, Shaanxi University of Chinese Medicine, Xianyang, Shaanxi 712000, P.R. China
| | - Feng Li
- Department of Traditional Chinese Medicine, Xijing Hospital, The Fourth Military Medical University, Xi'an, Shaanxi 710032, P.R. China
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Lew JKS, Pearson JT, Schwenke DO, Katare R. Exercise mediated protection of diabetic heart through modulation of microRNA mediated molecular pathways. Cardiovasc Diabetol 2017; 16:10. [PMID: 28086863 PMCID: PMC5237289 DOI: 10.1186/s12933-016-0484-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Accepted: 12/17/2016] [Indexed: 12/18/2022] Open
Abstract
Hyperglycaemia, hypertension, dyslipidemia and insulin resistance collectively impact on the myocardium of people with diabetes, triggering molecular, structural and myocardial abnormalities. These have been suggested to aggravate oxidative stress, systemic inflammation, myocardial lipotoxicity and impaired myocardial substrate utilization. As a consequence, this leads to the development of a spectrum of cardiovascular diseases, which may include but not limited to coronary endothelial dysfunction, and left ventricular remodelling and dysfunction. Diabetic heart disease (DHD) is the term used to describe the presence of heart disease specifically in diabetic patients. Despite significant advances in medical research and long clinical history of anti-diabetic medications, the risk of heart failure in people with diabetes never declines. Interestingly, sustainable and long-term exercise regimen has emerged as an effective synergistic therapy to combat the cardiovascular complications in people with diabetes, although the precise molecular mechanism(s) underlying this protection remain unclear. This review provides an overview of the underlying mechanisms of hyperglycaemia- and insulin resistance-mediated DHD with a detailed discussion on the role of different intensities of exercise in mitigating these molecular alterations in diabetic heart. In particular, we provide the possible role of exercise on microRNAs, the key molecular regulators of several pathophysiological processes.
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Affiliation(s)
- Jason Kar Sheng Lew
- Department of Physiology, HeartOtago, University of Otago, 270, Great King Street, Dunedin, 9010, New Zealand
| | - James T Pearson
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Suita, Osaka, Japan.,Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, Australia
| | - Daryl O Schwenke
- Department of Physiology, HeartOtago, University of Otago, 270, Great King Street, Dunedin, 9010, New Zealand.
| | - Rajesh Katare
- Department of Physiology, HeartOtago, University of Otago, 270, Great King Street, Dunedin, 9010, New Zealand.
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Pan JH, Kim JH, Kim HM, Lee ES, Shin DH, Kim S, Shin M, Kim SH, Lee JH, Kim YJ. Acetic acid enhances endurance capacity of exercise-trained mice by increasing skeletal muscle oxidative properties. Biosci Biotechnol Biochem 2015; 79:1535-41. [DOI: 10.1080/09168451.2015.1034652] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Abstract
Acetic acid has been shown to promote glycogen replenishment in skeletal muscle during exercise training. In this study, we investigated the effects of acetic acid on endurance capacity and muscle oxidative metabolism in the exercise training using in vivo mice model. In exercised mice, acetic acid induced a significant increase in endurance capacity accompanying a reduction in visceral adipose depots. Serum levels of non-esterified fatty acid and urea nitrogen were significantly lower in acetic acid-fed mice in the exercised mice. Importantly, in the mice, acetic acid significantly increased the muscle expression of key enzymes involved in fatty acid oxidation and glycolytic-to-oxidative fiber-type transformation. Taken together, these findings suggest that acetic acid improves endurance exercise capacity by promoting muscle oxidative properties, in part through the AMPK-mediated fatty acid oxidation and provide an important basis for the application of acetic acid as a major component of novel ergogenic aids.
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Affiliation(s)
- Jeong Hoon Pan
- Department of Food and Biotechnology, Korea University, Sejong, Republic of Korea
| | - Jun Ho Kim
- Department of Food and Biotechnology, Korea University, Sejong, Republic of Korea
| | - Hyung Min Kim
- Department of Food and Biotechnology, Korea University, Sejong, Republic of Korea
| | - Eui Seop Lee
- Department of Food and Biotechnology, Korea University, Sejong, Republic of Korea
| | - Dong-Hoon Shin
- Department of Food and Biotechnology, Korea University, Sejong, Republic of Korea
| | - Seongpil Kim
- R&D Center, Daesang Corp., Icheon, Republic of Korea
| | | | - Sang Ho Kim
- School of Global Sport Studies, Korea University, Sejong, Republic of Korea
| | - Jin Hyup Lee
- Department of Food and Biotechnology, Korea University, Sejong, Republic of Korea
| | - Young Jun Kim
- Department of Food and Biotechnology, Korea University, Sejong, Republic of Korea
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12
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Unacylated ghrelin restores insulin and autophagic signaling in skeletal muscle of diabetic mice. Pflugers Arch 2015; 467:2555-69. [PMID: 26228926 DOI: 10.1007/s00424-015-1721-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 06/21/2015] [Accepted: 07/13/2015] [Indexed: 01/04/2023]
Abstract
Impairment of insulin signaling in skeletal muscle detrimentally affects insulin-stimulated disposal of glucose. Restoration of insulin signaling in skeletal muscle is important as muscle is one of the major sites for disposal of blood glucose. Recently, unacylated ghrelin (UnAG) has received attention in diabetic research due to its favorable actions on improving glucose tolerance, glycemic control, and insulin sensitivity. The investigation of UnAG has entered phase Ib clinical trial in type 2 diabetes and phase II clinical trial in hyperphagia in Prader-Willi syndrome. Nonetheless, the precise mechanisms responsible for the anti-diabetic actions of UnAG remain incompletely understood. In this study, we examined the effects of UnAG on restoring the impaired insulin signaling in skeletal muscle of db/db diabetic mice. Our results demonstrated that UnAG effectively restored the impaired insulin signaling in diabetic muscle. UnAG decreased insulin receptor substrate (IRS) phosphorylation, increased protein kinase B (Akt) phosphorylation, and, hence, suppressed mTOR signaling. Consequently, UnAG enhanced Glut4 localization and increased PDH activity in the diabetic skeletal muscle. Intriguingly, our data indicated that UnAG normalized the suppressed autophagic signaling in diabetic muscle. In conclusion, our findings illustrated that UnAG restored the impaired insulin and autophagic signaling in skeletal muscle of diabetic mice, which are valuable to understand the underlying mechanisms of the anti-diabetic action of UnAG at peripheral skeletal muscle level.
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Booth FW, Ruegsegger GN, Toedebusch RG, Yan Z. Endurance Exercise and the Regulation of Skeletal Muscle Metabolism. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015; 135:129-51. [DOI: 10.1016/bs.pmbts.2015.07.016] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Abbott MJ, Turcotte LP. AMPK-α2 is involved in exercise training-induced adaptations in insulin-stimulated metabolism in skeletal muscle following high-fat diet. J Appl Physiol (1985) 2014; 117:869-79. [DOI: 10.1152/japplphysiol.01380.2013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
AMP-activated protein kinase (AMPK) has been studied extensively and postulated to be a target for the treatment and/or prevention of metabolic disorders such as insulin resistance. Exercise training has been deemed a beneficial treatment for obesity and insulin resistance. Furthermore, exercise is a feasible method to combat high-fat diet (HFD)-induced alterations in insulin sensitivity. The purpose of this study was to determine whether AMPK-α2 activity is required to gain beneficial effects of exercise training with high-fat feeding. Wild-type (WT) and AMPK-α2 dominant-negative (DN) male mice were fed standard diet (SD), underwent voluntary wheel running (TR), fed HFD, or trained with HFD (TR + HFD). By week 6, TR, irrespective of genotype, decreased blood glucose and increased citrate synthase activity in both diet groups and decreased insulin levels in HFD groups. Hindlimb perfusions were performed, and, in WT mice with SD, TR increased insulin-mediated palmitate uptake (76.7%) and oxidation (>2-fold). These training-induced changes were not observed in the DN mice. With HFD, TR decreased palmitate oxidation (61–64%) in both WT and DN and increased palmitate uptake (112%) in the WT with no effects on palmitate uptake in the DN. With SD, TR increased ERK1/2 and JNK1/2 phosphorylation, regardless of genotype. With HFD, TR reduced JNK1/2 phosphorylation, regardless of genotype, carnitine palmitoyltransferase 1 expression in WT, and CD36 expression in both DN and WT. These data suggest that low AMPK-α2 signaling disrupts, in part, the exercise training-induced adaptations in insulin-stimulated metabolism in skeletal muscle following HFD.
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Affiliation(s)
- Marcia J. Abbott
- Department of Biological Sciences, Human and Evolutionary Biology Section, Dana and David Dornsife College of Arts, Letters, and Sciences, University of Southern California, Los Angeles, California; and
- Crean College of Health and Behavioral Sciences, Chapman University, Orange, California
| | - Lorraine P. Turcotte
- Department of Biological Sciences, Human and Evolutionary Biology Section, Dana and David Dornsife College of Arts, Letters, and Sciences, University of Southern California, Los Angeles, California; and
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15
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Genetic Dissection of the Physiological Role of Skeletal Muscle in Metabolic Syndrome. ACTA ACUST UNITED AC 2014. [DOI: 10.1155/2014/635146] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The primary deficiency underlying metabolic syndrome is insulin resistance, in which insulin-responsive peripheral tissues fail to maintain glucose homeostasis. Because skeletal muscle is the major site for insulin-induced glucose uptake, impairments in skeletal muscle’s insulin responsiveness play a major role in the development of insulin resistance and type 2 diabetes. For example, skeletal muscle of type 2 diabetes patients and their offspring exhibit reduced ratios of slow oxidative muscle. These observations suggest the possibility of applying muscle remodeling to recover insulin sensitivity in metabolic syndrome. Skeletal muscle is highly adaptive to external stimulations such as exercise; however, in practice it is often not practical or possible to enforce the necessary intensity to obtain measurable benefits to the metabolic syndrome patient population. Therefore, identifying molecular targets for inducing muscle remodeling would provide new approaches to treat metabolic syndrome. In this review, the physiological properties of skeletal muscle, genetic analysis of metabolic syndrome in human populations and model organisms, and genetically engineered mouse models will be discussed in regard to the prospect of applying skeletal muscle remodeling as possible therapy for metabolic syndrome.
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16
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Successive exposure to moderate hypoxia does not affect glucose metabolism and substrate oxidation in young healthy men. SPRINGERPLUS 2014; 3:370. [PMID: 25089253 PMCID: PMC4117865 DOI: 10.1186/2193-1801-3-370] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Accepted: 07/03/2014] [Indexed: 12/03/2022]
Abstract
Introduction Exposure to hypoxia has been suggested to acutely alter glucose regulation. However, the effects of successive exposure to moderate hypoxia on postprandial glucose regulation and substrate oxidation pattern after multiple meals have not been elucidated. Purpose We examined the effects of successive exposure to moderate hypoxia on metabolic responses and substrate oxidation pattern. Methods Eight healthy men (21.0 ± 0.6 yrs, 173 ± 2.3 cm, 70.6 ± 5.0 kg, 23.4 ± 1.1 kg/m2) completed two experimental trials on separate days: a rest trial under normoxic conditions (FiO2 = 20.9%) and a rest trial under hypoxic conditions (FiO2 = 15.0%). Experimental trials were performed over 7 h in an environmental chamber. Blood and respiratory gas samples were collected over 7 h. Standard meals were provided 1 h (745 kcal) and 4 h (731 kcal) after entering the chamber. Results Although each meal significantly increased blood glucose and serum insulin concentrations (P < 0.05), these responses did not differ significantly between the trials. There were no significant differences in areas under the curves for glucose or insulin concentrations over 7 h between the trials. No significant differences were observed in blood lactate, serum cortisol, free fatty acid, or glycerol concentrations over 7 h between the trials. The oxygen consumption (
) and carbon dioxide production (
) 3 h after entering the chamber were significantly higher in the hypoxic trial than in the normoxic trial (P < 0.05). However, the differences did not affect respiratory exchange ratio (RER). The average values of
,
, and RER did not differ between the trials. Conclusion Seven hours of moderate hypoxia did not alter postprandial glucose responses or substrate oxidation in young healthy men.
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17
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Greene NP, Nilsson MI, Washington TA, Lee DE, Brown LA, Papineau AM, Shimkus KL, Greene ES, Crouse SF, Fluckey JD. Impaired exercise-induced mitochondrial biogenesis in the obese Zucker rat, despite PGC-1α induction, is due to compromised mitochondrial translation elongation. Am J Physiol Endocrinol Metab 2014; 306:E503-11. [PMID: 24398401 DOI: 10.1152/ajpendo.00671.2013] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Previously, we demonstrated that high-volume resistance exercise stimulates mitochondrial protein synthesis (a measure of mitochondrial biogenesis) in lean but not obese Zucker rats. Here, we examined factors involved in regulating mitochondrial biogenesis in the same animals. PGC-1α was 45% higher following exercise in obese but not lean animals compared with sedentary counterparts. Interestingly, exercised animals demonstrated greater PPARδ protein in both lean (47%) and obese (>200%) animals. AMPK phosphorylation (300%) and CPT-I protein (30%) were elevated by exercise in lean animals only, indicating improved substrate availability/flux. These findings suggest that, despite PGC-1α induction, obese animals were resistant to exercise-induced synthesis of new mitochondrial and oxidative protein. Previously, we reported that most anabolic processes are upregulated in these same obese animals regardless of exercise, so the purpose of this study was to assess specific factors associated with the mitochondrial genome as possible culprits for impaired mitochondrial biogenesis. Exercise resulted in higher mRNA contents of mitochondrial transcription factor A (∼50% in each phenotype) and mitochondrial translation initiation factor 2 (31 and 47% in lean and obese, respectively). However, mitochondrial translation elongation factor-Tu mRNA was higher following exercise in lean animals only (40%), suggesting aberrant regulation of mitochondrial translation elongation as a possible culprit in impaired mitochondrial biogenesis following exercise with obesity.
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Affiliation(s)
- Nicholas P Greene
- Applied Exercise Science Laboratory, Department of Health and Kinesiology, Texas A & M University, College Station, Texas
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18
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Mortensen B, Friedrichsen M, Andersen NR, Alibegovic AC, Højbjerre L, Sonne MP, Stallknecht B, Dela F, Wojtaszewski JFP, Vaag A. Physical inactivity affects skeletal muscle insulin signaling in a birth weight-dependent manner. J Diabetes Complications 2014; 28:71-8. [PMID: 24120282 DOI: 10.1016/j.jdiacomp.2013.09.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Revised: 09/03/2013] [Accepted: 09/05/2013] [Indexed: 10/26/2022]
Abstract
AIMS We investigated whether physical inactivity could unmask defects in insulin and AMPK signaling in low birth weight (LBW) subjects. METHODS Twenty LBW and 20 normal birth weight (NBW) subjects were investigated using the euglycemic-hyperinsulinemic clamp with excision of skeletal muscle biopsies pre and post 9days of bed rest. Employing Western blotting, we investigated skeletal muscle Akt, AS160, GLUT4, and AMPK signaling. RESULTS Peripheral insulin action was similar in the two groups and was decreased to the same extent post bed rest. Insulin and AMPK signaling was unaffected by bed rest in NBW individuals. LBW subjects showed decreased insulin-stimulated Akt phosphorylation and increased AMPK α1 and γ3 protein expression post bed rest. Insulin response of AS160 phosphorylation was lower in LBW subjects both pre and post bed rest. CONCLUSIONS Bed rest-induced insulin resistance is not explained by impaired muscle insulin or AMPK signaling in subjects with or without LBW. Lower muscle insulin signaling in LBW subjects post bed rest despite similar degree of insulin resistance as seen in controls may to some extent support the idea that LBW subjects are at higher risk of developing type 2 diabetes when being physically inactive.
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Affiliation(s)
- Brynjulf Mortensen
- Steno Diabetes Center, Gentofte, Denmark; Molecular Physiology Group, The August Krogh Centre, Department of Nutrition, Exercise and Sports, University of Copenhagen.
| | - Martin Friedrichsen
- Steno Diabetes Center, Gentofte, Denmark; Molecular Physiology Group, The August Krogh Centre, Department of Nutrition, Exercise and Sports, University of Copenhagen
| | - Nicoline R Andersen
- Molecular Physiology Group, The August Krogh Centre, Department of Nutrition, Exercise and Sports, University of Copenhagen
| | | | - Lise Højbjerre
- Department of Biomedical Sciences, University of Copenhagen; Center for Healthy Ageing, University of Copenhagen
| | - Mette P Sonne
- Department of Biomedical Sciences, University of Copenhagen; Center for Healthy Ageing, University of Copenhagen
| | | | - Flemming Dela
- Department of Biomedical Sciences, University of Copenhagen; Center for Healthy Ageing, University of Copenhagen
| | - Jørgen F P Wojtaszewski
- Molecular Physiology Group, The August Krogh Centre, Department of Nutrition, Exercise and Sports, University of Copenhagen
| | - Allan Vaag
- Steno Diabetes Center, Gentofte, Denmark; Rigshospitalet, Department of Endocrinology, Denmark
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Romo-Vaquero M, Larrosa M, Yáñez-Gascón MJ, Issaly N, Flanagan J, Roller M, Tomás-Barberán FA, Espín JC, García-Conesa MT. A rosemary extract enriched in carnosic acid improves circulating adipocytokines and modulates key metabolic sensors in lean Zucker rats: Critical and contrasting differences in the obese genotype. Mol Nutr Food Res 2013; 58:942-53. [DOI: 10.1002/mnfr.201300524] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Revised: 10/02/2013] [Accepted: 10/03/2013] [Indexed: 12/12/2022]
Affiliation(s)
- María Romo-Vaquero
- Research Group on Quality; Safety, and Bioactivity of Plant Foods; Department of Food Science and Technology; CEBAS-CSIC; Murcia Spain
| | - Mar Larrosa
- Research Group on Quality; Safety, and Bioactivity of Plant Foods; Department of Food Science and Technology; CEBAS-CSIC; Murcia Spain
| | - María J. Yáñez-Gascón
- Research Group on Quality; Safety, and Bioactivity of Plant Foods; Department of Food Science and Technology; CEBAS-CSIC; Murcia Spain
| | | | | | | | - Francisco A. Tomás-Barberán
- Research Group on Quality; Safety, and Bioactivity of Plant Foods; Department of Food Science and Technology; CEBAS-CSIC; Murcia Spain
| | - Juan C. Espín
- Research Group on Quality; Safety, and Bioactivity of Plant Foods; Department of Food Science and Technology; CEBAS-CSIC; Murcia Spain
| | - María-Teresa García-Conesa
- Research Group on Quality; Safety, and Bioactivity of Plant Foods; Department of Food Science and Technology; CEBAS-CSIC; Murcia Spain
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20
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Palacios-González B, Zarain-Herzberg A, Flores-Galicia I, Noriega LG, Alemán-Escondrillas G, Zariñan T, Ulloa-Aguirre A, Torres N, Tovar AR. Genistein stimulates fatty acid oxidation in a leptin receptor-independent manner through the JAK2-mediated phosphorylation and activation of AMPK in skeletal muscle. Biochim Biophys Acta Mol Cell Biol Lipids 2013; 1841:132-40. [PMID: 24013029 DOI: 10.1016/j.bbalip.2013.08.018] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 08/02/2013] [Accepted: 08/27/2013] [Indexed: 11/19/2022]
Abstract
Obesity is a public health problem that contributes to the development of insulin resistance, which is associated with an excessive accumulation of lipids in skeletal muscle tissue. There is evidence that soy protein can decrease the ectopic accumulation of lipids and improves insulin sensitivity; however, it is unknown whether soy isoflavones, particularly genistein, can stimulate fatty acid oxidation in the skeletal muscle. Thus, we studied the mechanism by which genistein stimulates fatty acid oxidation in the skeletal muscle. We showed that genistein induced the expression of genes of fatty acid oxidation in the skeletal muscle of Zucker fa/fa rats and in leptin receptor (ObR)-silenced C2C12 myotubes through AMPK phosphorylation. Furthermore, the genistein-mediated AMPK phosphorylation occurred via JAK2, which was possibly activated through a mechanism that involved cAMP. Additionally, the genistein-mediated induction of fatty acid oxidation genes involved PGC1α and PPARδ. As a result, we observed that genistein increased fatty acid oxidation in both the control and silenced C2C12 myotubes, as well as a decrease in the RER in mice, suggesting that genistein can be used in strategies to decrease lipid accumulation in the skeletal muscle.
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Affiliation(s)
- Berenice Palacios-González
- Posgrado Ciencias Bioquímicas, Facultad de Química, UNAM, México, D.F. 04510, Mexico; Departamento de Fisiología de la Nutrición, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, México, D.F. 14000, Mexico
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21
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Nilsson MI, Dobson JP, Greene NP, Wiggs MP, Shimkus KL, Wudeck EV, Davis AR, Laureano ML, Fluckey JD. Abnormal protein turnover and anabolic resistance to exercise in sarcopenic obesity. FASEB J 2013; 27:3905-16. [PMID: 23804240 DOI: 10.1096/fj.12-224006] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Obesity may impair protein synthesis rates and cause anabolic resistance to growth factors, hormones, and exercise, ultimately affecting skeletal muscle mass and function. To better understand muscle wasting and anabolic resistance with obesity, we assessed protein 24-h fractional synthesis rates (24-h FSRs) in selected hind-limb muscles of sedentary and resistance-exercised lean and obese Zucker rats. Despite atrophied hind-limb muscles (-28% vs. lean rats), 24-h FSRs of mixed proteins were significantly higher in quadriceps (+18%) and red or white gastrocnemius (+22 or +38%, respectively) of obese animals when compared to lean littermates. Basal synthesis rates of myofibrillar (+8%) and mitochondrial proteins (-1%) in quadriceps were not different between phenotypes, while manufacture of cytosolic proteins (+12%) was moderately elevated in obese cohorts. Western blot analyses revealed a robust activation of p70S6k (+178%) and a lower expression of the endogenous mTOR inhibitor DEPTOR (-28%) in obese rats, collectively suggesting that there is an obesity-induced increase in net protein turnover favoring degradation. Lastly, the protein synthetic response to exercise of mixed (-7%), myofibrillar (+6%), and cytosolic (+7%) quadriceps subfractions was blunted compared to the lean phenotype (+34, +40, and +17%, respectively), indicating a muscle- and subfraction-specific desensitization to the anabolic stimulus of exercise in obese animals.
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Affiliation(s)
- Mats I Nilsson
- 1Department of Health and Kinesiology, Texas A&M University, College Station, TX 77843-4243.
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22
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Wu MC, Tsai YL, Huang CY, Kao CL, Hou CW, Chen CY, Korivi M, Jean WH, Lee SD, Kuo CH. Hyperinsulinemia and overweight in obese Zucker rats effectively suppressed by exercise training with hypoxia recovery. Eur J Sport Sci 2013. [DOI: 10.1080/17461391.2011.606839] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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23
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Sarvas JL, Khaper N, Lees SJ. The IL-6 Paradox: Context Dependent Interplay of SOCS3 and AMPK. ACTA ACUST UNITED AC 2013; Suppl 13. [PMID: 24244888 DOI: 10.4172/2155-6156.s13-003] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Insulin resistance is the principle step towards the progression of type 2 diabetes, and has been linked to increased circulating levels of cytokines, leading to chronic low-grade inflammation. Specifically, in chronic disease states increased IL-6 is thought to play a critical role in the regulation of insulin resistance in the peripheral tissues, and has been used as a marker of insulin resistance. There is also an endogenous up-regulation of IL-6 in response to exercise, which has been linked to improved insulin sensitivity. This leads to the question "how can elevated IL-6 lead to the development of insulin resistance, and yet also lead to increased insulin sensitivity?" Resolving the dual role of IL-6 in regulating insulin resistance/sensitivity is critical to the development of potential therapeutic interventions. This review summarizes the literature on the seemingly paradoxical role of elevated IL-6 on insulin signalling, including the activation of AMPK and the involvement of leptin and SOCS3.
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Cao S, Li B, Yi X, Chang B, Zhu B, Lian Z, Zhang Z, Zhao G, Liu H, Zhang H. Effects of exercise on AMPK signaling and downstream components to PI3K in rat with type 2 diabetes. PLoS One 2012; 7:e51709. [PMID: 23272147 PMCID: PMC3521695 DOI: 10.1371/journal.pone.0051709] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Accepted: 11/05/2012] [Indexed: 01/31/2023] Open
Abstract
Exercise can increase skeletal muscle sensitivity to insulin, improve insulin resistance and regulate glucose homeostasis in rat models of type 2 diabetes. However, the potential mechanism remains poorly understood. In this study, we established a male Sprague–Dawley rat model of type 2 diabetes, with insulin resistance and β cell dysfunction, which was induced by a high-fat diet and low-dose streptozotocin to replicate the pathogenesis and metabolic characteristics of type 2 diabetes in humans. We also investigated the possible mechanism by which chronic and acute exercise improves metabolism, and the phosphorylation and expression of components of AMP-activated protein kinase (AMPK) and downstream components of phosphatidylinositol 3-kinase (PI3K) signaling pathways in the soleus. As a result, blood glucose, triglyceride, total cholesterol, and free fatty acid were significantly increased, whereas insulin level progressively declined in diabetic rats. Interestingly, chronic and acute exercise reduced blood glucose, increased phosphorylation and expression of AMPKα1/2 and the isoforms AMPKα1 and AMPKα2, and decreased phosphorylation and expression of AMPK substrate, acetyl CoA carboxylase (ACC). Chronic exercise upregulated phosphorylation and expression of AMPK upstream kinase, LKB1. But acute exercise only increased LKB1 expression. In particular, exercise reversed the changes in protein kinase C (PKC)ζ/λ phosphorylation, and PKCζ phosphorylation and expression. Additionally, exercise also increased protein kinase B (PKB)/Akt1, Akt2 and GLUT4 expression, but AS160 protein expression was unchanged. Chronic exercise elevated Akt (Thr308) and (Ser473) and AS160 phosphorylation. Finally, we found that exercise increased peroxisome proliferator-activated receptor-γ coactivator 1 (PGC1) mRNA expression in the soleus of diabetic rats. These results indicate that both chronic and acute exercise influence the phosphorylation and expression of components of the AMPK and downstream to PIK3 (aPKC, Akt), and improve GLUT4 trafficking in skeletal muscle. These data help explain the mechanism how exercise regulates glucose homeostasis in diabetic rats.
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Affiliation(s)
- Shicheng Cao
- Department of Sport Medicine, College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning Province, China.
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Greene NP, Fluckey JD, Lambert BS, Greene ES, Riechman SE, Crouse SF. Regulators of blood lipids and lipoproteins? PPARδ and AMPK, induced by exercise, are correlated with lipids and lipoproteins in overweight/obese men and women. Am J Physiol Endocrinol Metab 2012; 303:E1212-21. [PMID: 22990076 DOI: 10.1152/ajpendo.00309.2012] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
PPARδ is a transcription factor regulating the expression of genes involved in oxidative metabolism, which may regulate blood cholesterols through transcription of oxidative and lipoprotein metabolism genes. To determine the association of skeletal muscle PPARδ content with blood lipids and lipoproteins before and following exercise, overweight and obese men (n = 9) and women (n = 7) were recruited; age, BMI, body fat percentage, and Vo(2max) were (means ± SE) 45 ± 2.5 yr, 31.9 ± 1.4 kg/m(-2), 41.1 ± 1.5%, and 26.0 ± 1.3 mLO(2)·kg(-1)·min(-1), respectively. Subjects performed 12 wk of endurance exercise training (3 sessions/wk, progressing to 500 kcal/session). To assess the acute exercise response, subjects performed a single exercise session on a treadmill (70% Vo(2max), 400 kcal energy expenditure) before and after training. Muscle and blood samples were obtained prior to any exercise and 24 h after each acute exercise session. Muscle was analyzed for protein content of PPARδ, PPARα, PGC-1α, AMPKα, and the oxidative and lipoprotein markers FAT/CD36, CPT I, COX-IV, LPL, F(1) ATPase, ABCAI, and LDL receptor. Blood was assessed for lipids and lipoproteins. Repeated-measures ANOVA revealed no influence of sex on measured outcomes. PPARδ, PGC-1α, FAT/CD36, and LPL content were enhanced following acute exercise, whereas PPARα, AMPKα, CPT I, and COX-IV content were enhanced only after exercise training. PPARδ content negatively correlated with total and LDL cholesterol concentrations primarily in the untrained condition (r ≤ -0.4946, P < 0.05), whereas AMPKα was positively correlated with HDL cholesterol concentrations regardless of exercise (r ≥ 0.5543, P < 0.05). Our findings demonstrate exercise-induced expression of skeletal muscle PPARs and their target proteins, and this expression is associated with improved blood lipids and lipoproteins in obese adults.
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Affiliation(s)
- Nicholas P Greene
- Applied Exercise Science Laboratory, Department of Health and Kinesiology, Texas A & M University, College Station, Texas, USA.
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Abstract
Mitochondria are dynamic organelles in skeletal muscle critical in physical performance and disease. The mitochondrial life cycle spans biogenesis, maintenance, and clearance. Exercise training may promote each of these processes, conferring positive impacts on skeletal muscle contractile and metabolic functions. This review focuses on the regulation of these processes by endurance exercise and discusses potential benefits in health and disease.
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Lee JE, Yi CO, Jeon BT, Shin HJ, Kim SK, Jung TS, Choi JY, Roh GS. α-Lipoic acid attenuates cardiac fibrosis in Otsuka Long-Evans Tokushima Fatty rats. Cardiovasc Diabetol 2012; 11:111. [PMID: 22992429 PMCID: PMC3558371 DOI: 10.1186/1475-2840-11-111] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Accepted: 09/18/2012] [Indexed: 02/06/2023] Open
Abstract
Background Hyperglycemia leads to cardiac oxidative stress and an imbalance in glucose homeostasis. Diabetic cardiomyopathy is characterised by cardiac hypertrophy and fibrosis. However, the underlying mechanisms of diabetic cardiomyopathy are not fully understood. This study aimed to investigate the effects of alpha-lipoic acid (ALA) on cardiac energy metabolism, antioxidant effect, and fibrosis in the hearts of Otsuka Long-Evans Tokushima fatty (OLETF) rats. Methods Animals were separated into non-diabetic Long-Evans Tokushima Otsuka (LETO) rats and diabetes-prone OLETF rats with or without ALA (200 mg/kg/day) administration for 16 weeks. Diabetic cardiomyopathy was assessed by staining with Sirius Red. The effect of ALA on AMPK signalling, antioxidant enzymes, and fibrosis-related genes in the heart of OLETF rats were performed by Western blot analysis or immunohistochemistry. Results Western blot analysis showed that cardiac adenosine monophosphate-activated kinase (AMPK) signalling was lower in OLETF rats than in LETO rats, and that ALA treatment increased the signalling in OLETF rats. Furthermore, the low antioxidant activity in OLETF rats was increased by ALA treatment. In addition to increased Sirius red staining of collagen deposits, transforming growth factor-β1 (TGF-β1) and connective tissue growth factor (CTGF) were expressed at higher levels in OLETF rat hearts than in LETO rat hearts, and the levels of these factors were decreased by ALA. Conclusions ALA enhances AMPK signalling, antioxidant, and antifibrogenic effect. Theses findings suggest that ALA may have beneficial effects in the treatment of diabetic cardiomyopathy.
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Affiliation(s)
- Jung Eun Lee
- Department of Anatomy, Institute of Health Sciences, Gyeongsang National University School of Medicine, Jinju, Gyeongnam, Republic of Korea
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Kang L, Lustig ME, Bonner JS, Lee-Young RS, Mayes WH, James FD, Lin CT, Perry CGR, Anderson EJ, Neufer PD, Wasserman DH. Mitochondrial antioxidative capacity regulates muscle glucose uptake in the conscious mouse: effect of exercise and diet. J Appl Physiol (1985) 2012; 113:1173-83. [PMID: 22653994 DOI: 10.1152/japplphysiol.01344.2011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The objective of this study was to test the hypothesis that exercise-stimulated muscle glucose uptake (MGU) is augmented by increasing mitochondrial reactive oxygen species (mtROS) scavenging capacity. This hypothesis was tested in genetically altered mice fed chow or a high-fat (HF) diet that accelerates mtROS formation. Mice overexpressing SOD2 (sod2(Tg)), mitochondria-targeted catalase (mcat(Tg)), and combined SOD2 and mCAT (mtAO) were used to increase mtROS scavenging. mtROS was assessed by the H(2)O(2) emitting potential (JH(2)O(2)) in muscle fibers. sod2(Tg) did not decrease JH(2)O(2) in chow-fed mice, but decreased JH(2)O(2) in HF-fed mice. mcat(Tg) and mtAO decreased JH(2)O(2) in both chow- and HF-fed mice. In parallel, the ratio of reduced to oxidized glutathione (GSH/GSSG) was unaltered in sod2(Tg) in chow-fed mice, but was increased in HF-fed sod2(Tg) and both chow- and HF-fed mcat(Tg) and mtAO. Nitrotyrosine, a marker of NO-dependent, reactive nitrogen species (RNS)-induced nitrative stress, was decreased in both chow- and HF-fed sod2(Tg), mcat(Tg), and mtAO mice. This effect was not changed with exercise. Kg, an index of MGU was assessed using 2-[(14)C]-deoxyglucose during exercise. In chow-fed mice, sod2(Tg), mcat(Tg), and mtAO increased exercise Kg compared with wild types. Exercise Kg was also augmented in HF-fed sod2(Tg) and mcat(Tg) mice but unchanged in HF-fed mtAO mice. In conclusion, mtROS scavenging is a key regulator of exercise-mediated MGU and this regulation depends on nutritional state.
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Affiliation(s)
- Li Kang
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA.
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Tian DR, Tso P, Han JS. Diet-induced obese rats exhibit impaired LKB1-AMPK signaling in hypothalamus and adipose tissue. Peptides 2012; 35:23-30. [PMID: 22465622 DOI: 10.1016/j.peptides.2012.02.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Revised: 02/02/2012] [Accepted: 02/02/2012] [Indexed: 11/18/2022]
Abstract
AMPK not only acts as a sensor of cellular energy status but also plays a critical role in the energy balance of the body. In this study, LKB1-AMPK signaling was investigated in diet-induced obese (DIO) and diet resistant (DR) rats. In hypothalamus, DIO rats had lower level of LKB1, AMPKα and pAMPKα than chow-fed or DR rats. Both orexigenic peptide NPY and anorexigenic peptide POMC expression were reduced in hypothalamus of DIO rats. i.c.v. injection of AICAR, an activator of AMPK, increased NPY expression but did not alter POMC expression in DIO rats. In periphery, LKB1 protein content and pAMPKα level were lower in the adipose tissue of DIO rats compared to chow-fed and DR rats. Moreover, pAMPKα and LKB1 protein levels obtained from epididymal fat pad were inversely correlated with epididymal fat mass. LKB1 protein content and pAMPKα in skeletal muscle of DIO rats were not different from those in the muscles of chow-fed and DR rats. In summary, DIO rats, but not DR rats, have impaired LKB1-AMPK signaling in hypothalamus and adipose tissue, suggesting the disturbed energy balance observed in DIO rats is related with abnormalities of AMPK signaling in a tissue specific manner.
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Chen YC, Lee SD, Kuo CH, Ho LT. The effects of altitude training on the AMPK-related glucose transport pathway in the red skeletal muscle of both lean and obese Zucker rats. High Alt Med Biol 2012; 12:371-8. [PMID: 22206563 DOI: 10.1089/ham.2010.1088] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
INTRODUCTION The skeletal muscle AMP-activated protein kinase (AMPK)-related glucose transport pathway is involved in glucose homeostasis. AIM In this study, we examined whether obese control Zucker rats had abnormal expression of proteins in the LKB1-AMPK-AS160-GLUT4 pathway in red gastrocnemius muscle compared to that in lean (normal) control Zucker rats. We also compared the chronic training effects of exercise, hypoxia, and altitude training on this pathway in lean and obese rats. METHODS At sea level, lean and obese rats were divided into 4 groups for 6 weeks training as follows: 1) control; 2) exercise (progressive daily swimming-exercise training with comparable exercise signals between the two groups); 3) hypoxia (8 hours of daily 14% O2 exposure); and 4) exercise plus hypoxia (also called altitude training). Seven animals were used for each group. RESULTS The obese rats in the control group had higher body weights, elevated fasting insulin and glucose levels, and higher baseline levels of muscle AMPK and AS160 phosphorylation compared with those of lean control rats. For obese Zucker rats in the exercise or hypoxia groups, the muscle AMPK phosphorylation level was significantly decreased compared with that of the control group. For obese Zucker rats in the altitude training group, the levels of AMPK, AS160 phosphorylation, fasting insulin, and fasting glucose were decreased concomitant with an approximate 50% increase in the muscle GLUT4 protein level compared with those of the control group. In lean rats, the altitude training efficiently lowered fasting glucose and insulin levels and increased muscle AMPK and AS160 phosphorylation as well as GLUT4 protein levels. CONCLUSION Our results provide evidence that long-term altitude training may be a potentially effective nonpharmacological strategy for treating and preventing insulin resistance based on its effects on the skeletal muscle AMPK-AS160-GLUT4 pathway.
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Affiliation(s)
- Yu-Ching Chen
- Department and Institute of Physiology, School of Medicine, National Yang Ming University, Taipei, Republic of China
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Frier BC, Wan Z, Williams DB, Stefanson AL, Wright DC. Epinephrine and AICAR-induced PGC-1α mRNA expression is intact in skeletal muscle from rats fed a high-fat diet. Am J Physiol Cell Physiol 2012; 302:C1772-9. [PMID: 22496244 DOI: 10.1152/ajpcell.00410.2011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) is a master regulator of mitochondrial biogenesis and is controlled, at least in part, through AMP-activated protein kinase and p38-dependent pathways. There is evidence demonstrating that activation of these kinases and induction of PGC-1α in skeletal muscle are regulated by catecholamines. The purpose of the present study was to determine if consumption of a high-fat diet (HFD) impairs epinephrine and 5-aminoimidazole-4-carboxamide-1β-d-ribofuranoside (AICAR) signaling and induction of PGC-1α in rat skeletal muscle. Male Wistar rats were fed chow or a HFD for 6 wk and then given a weight-adjusted bolus injection of epinephrine (20, 10, or 5 μg/100 g body wt sc) or saline, and triceps muscles were harvested 30 min (signaling) or 2 and 4 h (gene expression) postinjection. Despite blunted increases in p38 phosphorylation, the ability of epinephrine to induce PGC-1α was intact in skeletal muscle from HFD-fed rats and was associated with normal increases in activation of PKA and phosphorylation of cAMP response element-binding protein, reputed mediators of PGC-1α expression. The attenuated epinephrine-mediated increase in p38 phosphorylation was independent of increases in MAPK phosphatase 1. At 2 h following AICAR treatment (0.5 g/kg body wt sc), AMP-activated protein kinase and acetyl-CoA carboxylase phosphorylation were similar in skeletal muscle from chow- and HFD-fed rats. Surprisingly, AICAR-induced increases in PGC-1α mRNA levels were greater in skeletal muscle from HFD-fed rats. Our results demonstrate that the ability of epinephrine and AICAR to induce PGC-1α remains intact in skeletal muscle from HFD-fed rats. These results question the existence of reduced β-adrenergic responsiveness in diet-induced obesity and demonstrate that increases in p38 phosphorylation are not required for induction of PGC-1α in muscle from obese rats.
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Affiliation(s)
- Bruce C Frier
- Department of Agriculture, Food, and Nutritional Science, University of Alberta, Edmonton, Canada
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The adenosine derivative 2′,3′,5′-tri-O-acetyl-N6-(3-hydroxylaniline) adenosine activates AMPK and regulates lipid metabolism in vitro and in vivo. Life Sci 2012; 90:1-7. [DOI: 10.1016/j.lfs.2011.09.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2011] [Revised: 07/27/2011] [Accepted: 08/28/2011] [Indexed: 01/02/2023]
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Coletta DK, Mandarino LJ. Mitochondrial dysfunction and insulin resistance from the outside in: extracellular matrix, the cytoskeleton, and mitochondria. Am J Physiol Endocrinol Metab 2011; 301:E749-55. [PMID: 21862724 PMCID: PMC3214002 DOI: 10.1152/ajpendo.00363.2011] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Insulin resistance in skeletal muscle is a prominent feature of obesity and type 2 diabetes. The association between mitochondrial changes and insulin resistance is well known. More recently, there is growing evidence of a relationship between inflammation, extracellular remodeling, and insulin resistance. The intent of this review is to propose a potentially novel mechanism for the development of insulin resistance, focusing on the underappreciated connections among inflammation, extracellular remodeling, cytoskeletal interactions, mitochondrial function, and insulin resistance in human skeletal muscle. Several sources of inflammation, including expansion of adipose tissue resulting in increased lipolysis and alterations in pro- and anti-inflammatory cytokines, contribute to the insulin resistance observed in obesity and type 2 diabetes. In the experimental model of lipid oversupply, an inflammatory response in skeletal muscle leads to altered expression extracellular matrix-related genes as well as nuclear encoded mitochondrial genes. A similar pattern also is observed in "naturally" occurring insulin resistance in muscle of obese nondiabetic individuals and patients with type 2 diabetes mellitus. More recently, alterations in proteins (including α-actinin-2, desmin, proteasomes, and chaperones) involved in muscle structure and function have been observed in insulin-resistant muscle. Some of these cytoskeletal proteins are mechanosignal transducers that allow muscle fibers to sense contractile activity and respond appropriately. The ensuing alterations in expression of genes coding for mitochondrial proteins and cytoskeletal proteins may contribute to the mitochondrial changes observed in insulin-resistant muscle. These changes in turn may lead to a reduction in fat oxidation and an increase in intramyocellular lipid, which contributes to the defects in insulin signaling in insulin resistance.
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Affiliation(s)
- Dawn K Coletta
- Center for Metabolic and Vascular Biology, Arizona State University, Tempe, Arizona 85287-3704, USA
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Takatani T, Minagawa M, Takatani R, Kinoshita K, Kohno Y. AMP-activated protein kinase attenuates Wnt/β-catenin signaling in human osteoblastic Saos-2 cells. Mol Cell Endocrinol 2011; 339:114-9. [PMID: 21501658 DOI: 10.1016/j.mce.2011.04.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2010] [Revised: 03/28/2011] [Accepted: 04/01/2011] [Indexed: 01/05/2023]
Abstract
AMP-activated protein kinase (AMPK) is a key sensor of cellular energetic conditions. Recent studies suggest that AMPK affects osteoblast differentiation, although its role and mechanism are not fully understood. One of the most important signals in osteoblast differentiation is the Wnt/β-catenin pathway which induces T-cell transcription factor 1 (TCF)-dependent transcription. Using human osteoblast-like Saos-2 cells, we determined whether AMPK modulates Wnt/β-catenin signaling in osteoblasts. Chemical activators of AMPK (AICAR [5-aminoimidazole-4-carboxamide riboside], metformin) suppressed Wnt3a-induced TCF-dependent transcriptional activity. Transactivation by Wnt was potentiated by inhibiting β-catenin degradation with lithium chloride (LiCl). LiCl-induced Wnt transactivation was suppressed by addition of metformin. Metformin increased the phosphorylation of β-catenin and decreased β-catenin protein levels leading to suppression of Wnt/β-catenin signaling. Our present study showed that AMPK attenuates Wnt/β-catenin signaling by reducing β-catenin protein levels in osteoblast-like cells.
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Affiliation(s)
- Tomozumi Takatani
- Department of Pediatrics, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba-shi, Chiba 260-8670, Japan.
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Chen YC, Lee SD, Hsih SY, Hsu YP, Kuo CH, Ho LT. Perturbations of the stress-induced GLUT4 localization pathway in slow-twitch muscles of obese Zucker rats. J Physiol Biochem 2011; 67:297-305. [PMID: 21347724 DOI: 10.1007/s13105-011-0075-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Accepted: 01/17/2011] [Indexed: 11/25/2022]
Abstract
Past studies have suggested that the stress-induced GLUT4 localization pathway is damaged in fast-twitch muscles (white muscles) of obese subjects. In this study, we used obese rodents in an attempt to determine whether the stress-induced GLUT4 localization pathway is abnormal in slow-twitch muscles (red muscles), which are responsible for most daily activities. Protein expression levels of the intracellular stress sensor AMP-activated protein kinase (AMPK), its upstream kinase LKB1, its downstream protein AS160 and the glucose transporter protein 4 (GLUT4) in the red gastrocnemius muscle were measured under either resting or stress conditions (1 h of swimming or 14% hypoxia) in both lean and obese Zucker rats (n = 7 for each group). At rest, obese rats displayed higher fasting plasma insulin levels and increased muscle AMPK and AS160 phosphorylation levels compared with lean controls. No significant difference was found in the protein levels of LKB1, total GLUT4, or membrane GLUT4 between the obese and lean control groups. After one hour of swimming, AMPK and AS160 phosphorylation levels and the amount of GLUT4 translocated to the plasma membrane were significantly elevated in lean rats but remained unchanged in obese rats relative to their resting conditions. One hour 14% hypoxia did not cause significant changes in the LKB1-AMPK-AS160-GLUT4 pathway in either lean or obese rats. This study demonstrated that the AMPK-AS160-GLUT4 pathway was altered at basal levels and after exercise stimulation in the slow-twitch muscle of obese Zucker rats.
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Affiliation(s)
- Yu-Ching Chen
- Department and Institute of Physiology, School of Medicine, National Yang Ming University, Shih-Pai, Taipei, Taiwan, Republic of China
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Lira VA, Benton CR, Yan Z, Bonen A. PGC-1alpha regulation by exercise training and its influences on muscle function and insulin sensitivity. Am J Physiol Endocrinol Metab 2010; 299:E145-61. [PMID: 20371735 PMCID: PMC2928513 DOI: 10.1152/ajpendo.00755.2009] [Citation(s) in RCA: 266] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The peroxisome proliferator-activated receptor-gamma (PPARgamma) coactivator-1alpha (PGC-1alpha) is a major regulator of exercise-induced phenotypic adaptation and substrate utilization. We provide an overview of 1) the role of PGC-1alpha in exercise-mediated muscle adaptation and 2) the possible insulin-sensitizing role of PGC-1alpha. To these ends, the following questions are addressed. 1) How is PGC-1alpha regulated, 2) what adaptations are indeed dependent on PGC-1alpha action, 3) is PGC-1alpha altered in insulin resistance, and 4) are PGC-1alpha-knockout and -transgenic mice suitable models for examining therapeutic potential of this coactivator? In skeletal muscle, an orchestrated signaling network, including Ca(2+)-dependent pathways, reactive oxygen species (ROS), nitric oxide (NO), AMP-dependent protein kinase (AMPK), and p38 MAPK, is involved in the control of contractile protein expression, angiogenesis, mitochondrial biogenesis, and other adaptations. However, the p38gamma MAPK/PGC-1alpha regulatory axis has been confirmed to be required for exercise-induced angiogenesis and mitochondrial biogenesis but not for fiber type transformation. With respect to a potential insulin-sensitizing role of PGC-1alpha, human studies on type 2 diabetes suggest that PGC-1alpha and its target genes are only modestly downregulated (< or =34%). However, studies in PGC-1alpha-knockout or PGC-1alpha-transgenic mice have provided unexpected anomalies, which appear to suggest that PGC-1alpha does not have an insulin-sensitizing role. In contrast, a modest ( approximately 25%) upregulation of PGC-1alpha, within physiological limits, does improve mitochondrial biogenesis, fatty acid oxidation, and insulin sensitivity in healthy and insulin-resistant skeletal muscle. Taken altogether, there is substantial evidence that the p38gamma MAPK-PGC-1alpha regulatory axis is critical for exercise-induced metabolic adaptations in skeletal muscle, and strategies that upregulate PGC-1alpha, within physiological limits, have revealed its insulin-sensitizing effects.
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Affiliation(s)
- Vitor A Lira
- Center for Skeletal Muscle Research, Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA, USA
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Sun X, Feng L, Tian L, Zhang J, Gao L, Zhao J. High-fat and low-carbohydrate diet feeding down-regulates the expression of the AMP-activated protein kinase pathway in rat cardiac muscle. Process Biochem 2010. [DOI: 10.1016/j.procbio.2010.02.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Paturi S, Gutta AK, Kakarla SK, Katta A, Arnold EC, Wu M, Rice KM, Blough ER. Impaired overload-induced hypertrophy in obese Zucker rat slow-twitch skeletal muscle. J Appl Physiol (1985) 2010; 108:7-13. [DOI: 10.1152/japplphysiol.00330.2009] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The effect of insulin resistance (IR) on the adaptation of skeletal muscle loading is not well understood. Here we examine whether the soleus muscles of the lean Zucker (LZ) and insulin-resistant obese Zucker (OZ) rat exhibit differences in their ability to undergo muscle hypertrophy following 8 wk of mechanical overload. Four-week-old male LZ ( n = 5) and OZ ( n = 5) rats underwent unilateral surgical ablation of the gastrocnemius muscle while the contralateral hindlimb was used as an internal control. Mechanical overload increased soleus muscle wet weight (LZ 57% and OZ 33%, respectively; P < 0 .05) and average type 1 fiber cross-sectional area (LZ 32% and OZ 5%, respectively; P < 0.05) in LZ and OZ rats, while the magnitude of these increases was greater in the LZ animals ( P < 0 .05). The reduced degree of muscle hypertrophy observed in the OZ animals was associated with decreases in the ability of the OZ soleus muscle to phosphorylate p70s6kThr 389 and mTOR, while phosphorylation of p70s6kThr 389 was increased in the LZ overloaded soleus by 83% ( P < 0 .05). The amount of Tuberin/TSC2 phosphorylation, an inhibitor of mTOR, was unchanged in the LZ soleus after overload while it was increased (68.3%, P < 0.05) in OZ animals. Conversely, AMPK phosphorylation was decreased in the LZ (−22.77%, P < 0 .05) but increased (57%, P < 0 .05) in the OZ soleus with overload. Taken together, these data suggest that IR or other related comorbidities may impair the ability of the soleus to activate mTOR signaling and undergo load-induced muscle hypertrophy.
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Affiliation(s)
| | | | - Sunil K. Kakarla
- Department of Pharmacology, Physiology and Toxicology, Joan C. Edwards School of Medicine, and
| | - Anjaiah Katta
- Department of Pharmacology, Physiology and Toxicology, Joan C. Edwards School of Medicine, and
| | - Eric C. Arnold
- Division of Exercise Science, Sport and Recreation, Marshall University, Huntington, West Virginia
| | - Miaozong Wu
- Department of Biological Sciences,
- Cell Differentiation and Development Center,
| | - Kevin M. Rice
- Department of Biological Sciences,
- Cell Differentiation and Development Center,
| | - Eric R. Blough
- Department of Biological Sciences,
- Cell Differentiation and Development Center,
- Department of Pharmacology, Physiology and Toxicology, Joan C. Edwards School of Medicine, and
- Division of Exercise Science, Sport and Recreation, Marshall University, Huntington, West Virginia
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Guo P, Kai Q, Gao J, Lian ZQ, Wu CM, Wu CA, Zhu HB. Cordycepin Prevents Hyperlipidemia in Hamsters Fed a High-Fat Diet via Activation of AMP-Activated Protein Kinase. J Pharmacol Sci 2010; 113:395-403. [DOI: 10.1254/jphs.10041fp] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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Lessard SJ, Rivas DA, Chen ZP, van Denderen BJ, Watt MJ, Koch LG, Britton SL, Kemp BE, Hawley JA. Impaired skeletal muscle beta-adrenergic activation and lipolysis are associated with whole-body insulin resistance in rats bred for low intrinsic exercise capacity. Endocrinology 2009; 150:4883-91. [PMID: 19819977 PMCID: PMC2775978 DOI: 10.1210/en.2009-0158] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Rats selectively bred for high endurance running capacity (HCR) have higher insulin sensitivity and improved metabolic health compared with those bred for low endurance capacity (LCR). We investigated several skeletal muscle characteristics, in vitro and in vivo, that could contribute to the metabolic phenotypes observed in sedentary LCR and HCR rats. After 16 generations of selective breeding, HCR had approximately 400% higher running capacity (P < 0.001), improved insulin sensitivity (P < 0.001), and lower fasting plasma glucose and triglycerides (P < 0.05) compared with LCR. Skeletal muscle ceramide and diacylglycerol content, basal AMP-activated protein kinase (AMPK) activity, and basal lipolysis were similar between LCR and HCR. However, the stimulation of lipolysis in response to 10 mum isoproterenol was 70% higher in HCR (P = 0.004). Impaired isoproterenol sensitivity in LCR was associated with lower basal triacylglycerol lipase activity, Ser660 phosphorylation of HSL, and beta2-adrenergic receptor protein content in skeletal muscle. Expression of the orphan nuclear receptor Nur77, which is induced by beta-adrenergic signaling and is associated with insulin sensitivity, was lower in LCR (P < 0.05). Muscle protein content of Nur77 target genes, including uncoupling protein 3, fatty acid translocase/CD36, and the AMPK gamma3 subunit were also lower in LCR (P < 0.05). Our investigation associates whole-body insulin resistance with impaired beta-adrenergic response and reduced expression of genes that are critical regulators of glucose and lipid metabolism in skeletal muscle. We identify impaired beta-adrenergic signal transduction as a potential mechanism for impaired metabolic health after artificial selection for low intrinsic exercise capacity.
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Affiliation(s)
- Sarah J Lessard
- Joslin Diabetes Center, 1 Joslin Place, Boston, Massachusetts 02215, USA.
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Mortensen B, Poulsen P, Wegner L, Stender-Petersen KL, Ribel-Madsen R, Friedrichsen M, Birk JB, Vaag A, Wojtaszewski JFP. Genetic and metabolic effects on skeletal muscle AMPK in young and older twins. Am J Physiol Endocrinol Metab 2009; 297:E956-64. [PMID: 19671840 DOI: 10.1152/ajpendo.00058.2009] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The protein complex AMP-activated protein kinase (AMPK) is believed to play an important role in the regulation of skeletal muscle glucose and lipid metabolism. Defects in the AMPK system might therefore be an important factor in the pathogenesis of type 2 diabetes. We aimed to identify genetic and environmental mechanisms involved in the regulation of AMPK expression and activity and to examine the association between AMPK protein levels and activity on the one hand, and glucose and fat metabolism on the other. We investigated skeletal muscle biopsies from 100 young and 82 older mono- and dizygotic nondiabetic twins excised during the basal and insulin-stimulated states of a physiological hyperinsulinemic-euglycemic clamp. AMPKalpha1, -alpha2, and -gamma3 mRNA expression was investigated using real-time PCR, and Western blotting was employed to measure protein levels. Multiple regression analyses indicated that skeletal muscle AMPK mRNA and protein expression as well as activity were regulated by sex, age, obesity, and aerobic capacity. Comparison of intraclass correlations on AMPK measurements from mono- and dizygotic twins suggested that skeletal muscle AMPK expression was under minor genetic influence. AMPKgamma3 protein expression and activity were negatively related to whole body glucose uptake through the nonoxidative metabolic pathway and positively related to phosphorylation of glycogen synthase. Our results suggest that skeletal muscle AMPK expression is under minor genetic control but regulated by age and sex and associated with obesity and aerobic capacity. Furthermore, our results indicate a role for gamma3-containing AMPK complexes in downregulation of insulin-stimulated nonoxidative glucose metabolism possibly through inhibition of glycogen synthase activity.
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Affiliation(s)
- Brynjulf Mortensen
- Department of Exercise and Sport Sciences, University of Copenhagen, Denmark.
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Sáinz N, Rodríguez A, Catalán V, Becerril S, Ramírez B, Gómez-Ambrosi J, Frühbeck G. Leptin administration favors muscle mass accretion by decreasing FoxO3a and increasing PGC-1alpha in ob/ob mice. PLoS One 2009; 4:e6808. [PMID: 19730740 PMCID: PMC2733298 DOI: 10.1371/journal.pone.0006808] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2009] [Accepted: 07/31/2009] [Indexed: 12/26/2022] Open
Abstract
Absence of leptin has been associated with reduced skeletal muscle mass in leptin-deficient ob/ob mice. The aim of our study was to examine the effect of leptin on the catabolic and anabolic pathways regulating muscle mass. Gastrocnemius, extensor digitorum longus and soleus muscle mass as well as fiber size were significantly lower in ob/ob mice compared to wild type littermates, being significantly increased by leptin administration (P<0.001). This effect was associated with an inactivation of the muscle atrophy-related transcription factor forkhead box class O3 (FoxO3a) (P<0.05), and with a decrease in the protein expression levels of the E3 ubiquitin-ligases muscle atrophy F-box (MAFbx) (P<0.05) and muscle RING finger 1 (MuRF1) (P<0.05). Moreover, leptin increased (P<0.01) protein expression levels of peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), a regulator of muscle fiber type, and decreased (P<0.05) myostatin protein, a negative regulator of muscle growth. Leptin administration also activated (P<0.01) the regulators of cell cycle progression proliferating cell nuclear antigen (PCNA) and cyclin D1, and increased (P<0.01) myofibrillar protein troponin T. The present study provides evidence that leptin treatment may increase muscle mass of ob/ob mice by inhibiting myofibrillar protein degradation as well as enhancing muscle cell proliferation.
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Affiliation(s)
- Neira Sáinz
- Metabolic Research Laboratory, University of Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
| | - Amaia Rodríguez
- Metabolic Research Laboratory, University of Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
| | - Victoria Catalán
- Metabolic Research Laboratory, University of Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
| | - Sara Becerril
- Metabolic Research Laboratory, University of Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
| | - Beatriz Ramírez
- Metabolic Research Laboratory, University of Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
| | - Javier Gómez-Ambrosi
- Metabolic Research Laboratory, University of Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
| | - Gema Frühbeck
- Metabolic Research Laboratory, University of Navarra, Pamplona, Spain
- Department of Endocrinology, Clínica Universidad de Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
- * E-mail:
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Abstract
The function and survival of all organisms is dependent on the dynamic control of energy metabolism, when energy demand is matched to energy supply. The AMP-activated protein kinase (AMPK) alphabetagamma heterotrimer has emerged as an important integrator of signals that control energy balance through the regulation of multiple biochemical pathways in all eukaryotes. In this review, we begin with the discovery of the AMPK family and discuss the recent structural studies that have revealed the molecular basis for AMP binding to the enzyme's gamma subunit. AMPK's regulation involves autoinhibitory features and phosphorylation of both the catalytic alpha subunit and the beta-targeting subunit. We review the role of AMPK at the cellular level through examination of its many substrates and discuss how it controls cellular energy balance. We look at how AMPK integrates stress responses such as exercise as well as nutrient and hormonal signals to control food intake, energy expenditure, and substrate utilization at the whole body level. Lastly, we review the possible role of AMPK in multiple common diseases and the role of the new age of drugs targeting AMPK signaling.
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Affiliation(s)
- Gregory R Steinberg
- Protein Chemistry and Metabolism, St. Vincent's Institute of Medical Research, University of Melbourne, Fitzroy, Victoria, Australia.
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44
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Bonen A. PGC-1alpha-induced improvements in skeletal muscle metabolism and insulin sensitivity. Appl Physiol Nutr Metab 2009; 34:307-14. [PMID: 19448691 DOI: 10.1139/h09-008] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The peroxisome proliferator-activated receptor gamma (PPARgamma) coactivator 1alpha (PGC-1alpha), a nuclear encoded transcriptional coactivator, increases the expression of many genes in skeletal muscle, including those involved with fatty acid oxidation and oxidative phosphorylation. Exercise increases the expression of PGC-1alpha, and the exercise-induced upregulation of many genes is attributable, in part, to the preceding activation and upregulation of PGC-1alpha. Indeed, PGC-1alpha overexpression, like exercise training, increases exercise performance. PGC-1alpha reductions in humans have been observed in type 2 diabetes, while, in cell lines, PGC-1alpha mimics the exercise-induced improvement in insulin sensitivity. However, unexpectedly, in mammalian muscle, PGC-1alpha overexpression contributed to the development of diet-induced insulin resistance. This may have been related to the massive overexpression of PGC-1alpha, which induced the upregulation of the fatty acid transporter FAT/CD36 and led to an increase in intramuscular lipids, which interfere with insulin signalling. In contrast, when PGC-1alpha was overexpressed modestly, within physiological limits, mitochondrial fatty acid oxidation was increased, GLUT4 expression was upregulated, and insulin-stimulated glucose transport was increased. More recently, similar PGC-1alpha-induced improvements in the insulin-resistant skeletal muscle of obese Zucker rats have been observed. These studies suggest that massive PGC-1alpha overexpression, but not physiologic PGC-1alpha overexpression, induces deleterious metabolic effects, and that exercise-induced improvements in insulin sensitivity are induced, in part, by the exercise-induced upregulation of PGC-1alpha.
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Affiliation(s)
- Arend Bonen
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada.
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45
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Wohlers LM, Sweeney SM, Ward CW, Lovering RM, Spangenburg EE. Changes in contraction-induced phosphorylation of AMP-activated protein kinase and mitogen-activated protein kinases in skeletal muscle after ovariectomy. J Cell Biochem 2009; 107:171-8. [PMID: 19259949 DOI: 10.1002/jcb.22113] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Recent evidence suggests that ovarian hormones contribute to altered function of skeletal muscle, however the signaling processes thought to regulate muscle function remain undefined in females. Thus, the purpose of this investigation is to determine if ovarian hormone status is critical for contraction-induced activation of AMPK or MAPK in skeletal muscle. Female mice were divided into two groups, ovariectomy (OVX) and SHAM, which were then subjected to in situ isometric contractile protocols. AMPK, ERK 1/2, p38, and JNK phosphorylation were measured in the control and contracting limb. In the in situ protocol, OVX muscles were significantly more resistant to fatigue compared to the SHAM animals. In addition, the muscles from OVX mice demonstrated significantly lower levels of normalized AMPK phosphorylation at rest. AMPK phosphorylation was not increased in the muscles from SHAM mice after the in situ contractile protocol, while the OVX demonstrated significant increases in AMPK phosphorylation. After contraction, normalized ERK2 phosphorylation was significantly higher in the OVX group compared to the SHAM group. Both p38 and JNK phosphorylation increased in response to contraction; but no group differences were detected. A second set of SHAM and OVX animals were subjected to fatigue stimulated under in vitro conditions. Significant increases in AMPK and ERK2 phosphorylation were detected, but no differences were found between groups. In conclusion, removal of the ovaries results in different responses to contraction-induced changes in phosphorylation of AMPK and ERK2 in female mice and suggests hormones secreted from the ovaries significantly impacts cellular signaling in skeletal muscle.
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Affiliation(s)
- Lindsay M Wohlers
- Department of Kinesiology, School of Public Health, University of Maryland, College Park, Maryland 21045, USA
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MacLean PS, Higgins JA, Wyatt HR, Melanson EL, Johnson GC, Jackman MR, Giles ED, Brown IE, Hill JO. Regular exercise attenuates the metabolic drive to regain weight after long-term weight loss. Am J Physiol Regul Integr Comp Physiol 2009; 297:R793-802. [PMID: 19587114 DOI: 10.1152/ajpregu.00192.2009] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Weight loss is accompanied by several metabolic adaptations that work together to promote rapid, efficient regain. We employed a rodent model of regain to examine the effects of a regular bout of treadmill exercise on these adaptations. Obesity was induced in obesity-prone rats with 16 wk of high-fat feeding and limited physical activity. Obese rats were then weight reduced (approximately 14% of body wt) with a calorie-restricted, low-fat diet and maintained at that reduced weight for 8 wk by providing limited provisions of the diet with (EX) or without (SED) a daily bout of treadmill exercise (15 m/min, 30 min/day, 6 days/wk). Weight regain, energy balance, fuel utilization, adipocyte cellularity, and humoral signals of adiposity were monitored during eight subsequent weeks of ad libitum feeding while the rats maintained their respective regimens of physical activity. Regular exercise decreased the rate of regain early in relapse and lowered the defended body weight. During weight maintenance, regular exercise reduced the biological drive to eat so that it came closer to matching the suppressed level of energy expenditure. The diurnal extremes in fuel preference observed in weight-reduced rats were blunted, since exercise promoted the oxidation of fat during periods of feeding (dark cycle) and promoted the oxidation of carbohydrate (CHO) later in the day during periods of deprivation (light cycle) . At the end of relapse, exercise reestablished the homeostatic steady state between intake and expenditure to defend a lower body weight. Compared with SED rats, relapsed EX rats exhibited a reduced turnover of energy, a lower 24-h oxidation of CHO, fewer adipocytes in abdominal fat pads, and peripheral signals that overestimated their adiposity. These observations indicate that regimented exercise altered several metabolic adaptations to weight reduction in a manner that would coordinately attenuate the propensity to regain lost weight.
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Affiliation(s)
- Paul S MacLean
- Center for Human Nutrition, Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Colorado Denver, Denver, Colorado, USA.
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Du M, Yan X, Tong JF, Zhao J, Zhu MJ. Maternal obesity, inflammation, and fetal skeletal muscle development. Biol Reprod 2009; 82:4-12. [PMID: 19516021 DOI: 10.1095/biolreprod.109.077099] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Maternal obesity coupled with Western-style high-energy diets represents a special problem that can result in poor fetal development, leading to harmful, persistent effects on offspring, including predisposition to obesity and type 2 diabetes. Mechanisms linking maternal obesity to the increased incidence of obesity and other metabolic diseases in offspring remain poorly defined. Because skeletal muscle is the principal site for glucose and fatty acid utilization and composes 40%-50% of total body mass, changes in the properties of offspring skeletal muscle and its mass resulting from maternal obesity may be responsible for the increase in type 2 diabetes and obesity. Fetal stage is crucial for skeletal muscle development because there is no net increase in the muscle fiber number after birth. Fetal skeletal muscle development involves myogenesis, adipogenesis, and fibrogenesis, which are all derived from mesenchymal stem cells (MSCs). Shifting commitment of MSCs from myogenesis to adipogenesis and fibrogenesis will result in increased intramuscular fat and connective tissue, as well as reduced numbers of muscle fiber and/or diameter, all of which have lasting negative effects on offspring muscle function and properties. Maternal obesity leads to low-grade inflammation, which changes the commitment of MSCs in fetal muscle through several possible mechanisms: 1) inflammation downregulates wingless and int (WNT) signaling, which attenuates myogenesis; 2) inflammation inhibits AMP-activated protein kinase, which promotes adipogenesis; and 3) inflammation may induce epigenetic modification through polycomb group proteins. More studies are needed to further explore the underlying mechanisms associated with maternal obesity, inflammation, and the commitment of MSCs.
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Affiliation(s)
- Min Du
- Department of Animal Science, University of Wyoming, Laramie, Wyoming 82071, USA.
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48
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Muraoka M, Fukushima A, Viengchareun S, Lombès M, Kishi F, Miyauchi A, Kanematsu M, Doi J, Kajimura J, Nakai R, Uebi T, Okamoto M, Takemori H. Involvement of SIK2/TORC2 signaling cascade in the regulation of insulin-induced PGC-1alpha and UCP-1 gene expression in brown adipocytes. Am J Physiol Endocrinol Metab 2009; 296:E1430-9. [PMID: 19351809 DOI: 10.1152/ajpendo.00024.2009] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Salt-inducible kinase 2 (SIK2) is expressed abundantly in adipose tissues and represses cAMP-response element-binding protein (CREB)-mediated gene expression by phosphorylating the coactivator transducer of regulated CREB activity (TORC2). Phosphorylation at Ser(587) of SIK2 diminishes its TORC2 phosphorylation activity. In 3T3-L1 white adipocytes, SIK2 downregulates lipogenic gene in response to nutritional stresses. To investigate the impact of SIK2 on the function of brown adipose tissue (BAT), we used T37i brown adipocytes, mice with diet-induced obesity, and SIK2 mutant (S587A) transgenic mice. When T37i adipocytes were treated with insulin, the levels of peroxisome proliferator-activated receptor-coactivator-1alpha (PGC-1alpha) and uncoupling protein-1 (UCP-1) mRNA were increased, and the induction was inhibited by overexpression of SIK2 (S587A) mutant or dominant-negative CREB. Insulin enhanced SIK2 phosphorylation at Ser(587), which was accompanied by decrease in phospho-TORC2. Similarly, the decrease in the level of SIK2 phosphorylation at Ser(587) was observed in the BAT of mice with diet-induced obesity, which was negatively correlated with TORC2 phosphorylation. To confirm the negative correlation between SIK2 phosphorylation at Ser(587) and TORC2 phosphorylation in BAT, SIK2 mutant (S587A) was overexpressed in adipose tissues by using the adipocyte fatty acid-binding protein 2 promoter. The expression of recombinant SIK2 (S587A) was restricted to BAT, and the levels of phospho-TORC2 were elevated in BAT of transgenic mice. Male transgenic mice developed high-fat diet-induced obesity, and their BAT expressed low levels of PGC-1alpha and UCP-1 mRNA, suggesting that SIK2-TORC2 cascade may be important for the regulation of PGC-1alpha and UCP-1 gene expression in insulin signaling in BAT.
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Affiliation(s)
- Masaaki Muraoka
- Laboratory of Cell Signaling and Metabolism, National Institute of Biomedical Innovation, 7-6-8, Asagi, Saito, Ibaraki, Osaka 567-0085, Japan
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49
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Pauli JR, Ropelle ER, Cintra DE, Souza CTD. Efeitos do exercício físico na expressão e atividade da AMPKα em ratos obesos induzidos por dieta rica em gordura. REV BRAS MED ESPORTE 2009. [DOI: 10.1590/s1517-86922009000200003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
INTRODUÇÃO: A ingestão de dieta hiperlipídica é um fator de risco singular no desenvolvimento de resistência à insulina e diabetes do tipo 2. OBJETIVO: O estudo investigou os efeitos do exercício físico na expressão e atividade da AMPKα em ratos obesos. MÉTODOS: Foram utilizados ratos Wistar, aleatoriamente divididos em quatro grupos, que receberam dieta padrão de manutenção (grupo controle) ou dieta hiperlipídica (DHL) (grupos sedentários e exercitados), por período de quatro meses. Dois diferentes protocolos de exercícios foram utilizados: exercício agudo ou crônico de natação. O teste de tolerância à insulina foi realizado para estimar a sensibilidade à insulina. Os níveis protéicos da AMPKα e do GLUT4 e também de p-AMPKα e pACC no músculo esquelético dos ratos foram determinados através da técnica de Western blot. RESULTADOS: O teste de tolerância à insulina revelou significativo prejuízo na ação da insulina após a alimentação com a DHL, indicando insulino-resistência quando comparado com grupo controle (p < 0,05). O tratamento por quatro meses com a DHL resultou em significativa redução no conteúdo protéico de AMPKα (2,2 vezes) e do GLUT4 (2,5 vezes) e nos níveis de p-AMPKα (2,4 vezes) e p-ACC (2,5 vezes) no músculo esquelético dos ratos sedentários quando comparado aos ratos controles. Ambos os protocolos de exercícios resultaram em aumento na fosforilação da AMPKα e ACC e aumento da sensibilidade à insulina, enquanto apenas o programa de exercício crônico promoveu o aumento da expressão dessas proteínas (p < 0,05). CONCLUSÃO: A alimentação com uma DHL causa redução na expressão e na atividade da AMPKα, enquanto a ativação da AMPKα pelo exercício físico melhora a sensibilidade à insulina, indicando que ratos obesos mantêm preservada a funcionalidade da via AMPKα.
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Garg M, Thamotharan M, Oak SA, Pan G, Maclaren DC, Lee PWN, Devaskar SU. Early exercise regimen improves insulin sensitivity in the intrauterine growth-restricted adult female rat offspring. Am J Physiol Endocrinol Metab 2009; 296:E272-81. [PMID: 19001551 PMCID: PMC2645014 DOI: 10.1152/ajpendo.90473.2008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We examined the effect of early exercise training (Ex) on glucose kinetics, basal, and insulin-stimulated skeletal muscle (SKM) plasma membrane (PM) GLUT4 in pre- and/or postnatal nutrient-restricted adult rat offspring compared with sedentary (Sed) state. Pregestational control female (Ex CON vs. Sed CON) and offspring exposed to prenatal (Ex IUGR vs. Sed IUGR), postnatal (Ex PNGR vs. Sed PNGR), or pre- and postnatal (Ex IUGR + PNGR vs. Sed IUGR + PNGR) nutrient restriction were studied. The combined effect of exercise and pre/postnatal nutrition in the Ex IUGR demonstrated positive effects on basal and glucose-stimulated plasma insulin response (GSIR) with suppression of endogenous hepatic glucose production (HGP) compared with sedentary state. Ex PNGR was hyperglycemic after glucose challenge with no change in glucose-stimulated insulin production or HGP compared with sedentary state. Ex IUGR + PNGR remained glucose tolerant with unchanged glucose-stimulated insulin production but increased endogenous HGP compared with sedentary state. Basal SKM PM-associated GLUT4 was unchanged by exercise in all four groups. Whereas Ex PNGR and Ex IUGR + PNGR insulin responsiveness was similar to that of Ex CON, Ex IUGR remained nonresponsive to insulin. Early introduction of regular Ex in the pregestational female offspring had a positive effect on hepatic adaptation to GSIR and HGP in IUGR and IUGR + PNGR, with no effect in PNGR. Change in insulin responsiveness of SKM GLUT4 translocation was observed in exercised IUGR + PNGR and PNGR but not in exercised IUGR.
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Affiliation(s)
- Meena Garg
- Division of Neonatology and Developmental Biology, Neonatal Research Center, Department of Pediatrics, David Geffen School of Medicine, UCLA, Los Angeles, CA 90095-1752, USA
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