1
|
Imerb N, Thonusin C, Pratchayasakul W, Chanpaisaeng K, Aeimlapa R, Charoenphandhu N, Chattipakorn N, Chattipakorn SC. Hyperbaric oxygen therapy exerts anti-osteoporotic effects in obese and lean D-galactose-induced aged rats. FASEB J 2023; 37:e23262. [PMID: 37855727 DOI: 10.1096/fj.202301197rr] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 09/24/2023] [Accepted: 10/04/2023] [Indexed: 10/20/2023]
Abstract
Obesity accelerates the aging processes, resulting in an aggravation of aging-induced osteoporosis. We investigated the anti-osteoporotic effect of hyperbaric oxygen therapy (HBOT) in obese- and lean-aged rats through measurement of cellular senescence, hypoxia, inflammation, antioxidants, and bone microarchitecture. Obese and lean male Wistar rats were injected with 150 mg/kg/day of D-galactose for 8 weeks to induce aging. Then, all rats were randomly given either sham or HBOT for 14 days. Metabolic parameters were determined. Expression by bone mRNA for cellular senescence, hypoxia, inflammation, antioxidative capacity, and bone remodeling were examined. Micro-computed tomography and atomic absorption spectroscopy were performed to evaluate bone microarchitecture and bone mineral profiles, respectively. We found that HBOT restored the alterations in the mRNA expression level of p16, p21, HIF-1α, TNF-α, IL-6, RANKL, RANK, NFATc1, DC-STAMP, Osx, ALP, and Col1a1 in the bone in obese-and lean- aging rats. In obese-aging rats, HBOT increased the level of expression of Sirt1 and CuZnSOD mRNA and diminished the expression level of HIF-2α and ctsk mRNA to the same levels as the control group. However, HBOT failed to alter catalase and OCN mRNA expression in obese-aged rats. HBOT partially improved the bone microarchitecture in obese-aged rats, but completely restored it in lean-aged rats. Interestingly, HBOT protected against obesity-induced demineralization in obese-aged rats. In summary, HBOT exerts an anti-osteoporotic effect in lean-aged rats and prevents some, but not all the negative effects of obese-aged conditions on bone health. Therefore, HBOT is considered as a potential therapy for aging-induced osteoporosis, regardless of obese status.
Collapse
Affiliation(s)
- Napatsorn Imerb
- Neurophysiology Unit, Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
- Center of Excellence in Cardiac Electrophysiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
- Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Chiang Mai University, Chiang Mai, Thailand
| | - Chanisa Thonusin
- Neurophysiology Unit, Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
- Center of Excellence in Cardiac Electrophysiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
- Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Wasana Pratchayasakul
- Neurophysiology Unit, Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
- Center of Excellence in Cardiac Electrophysiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
- Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Krittikan Chanpaisaeng
- National Center for Genetic Engineering and Biotechnology (BIOTEC), Pathum Thani, Thailand
- Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Ratchaneevan Aeimlapa
- Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, Thailand
- Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Narattaphol Charoenphandhu
- Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, Thailand
- Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand
- Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom, Thailand
- The Academy of Science, The Royal Society of Thailand, Bangkok, Thailand
| | - Nipon Chattipakorn
- Neurophysiology Unit, Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
- Center of Excellence in Cardiac Electrophysiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
- Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Siriporn C Chattipakorn
- Neurophysiology Unit, Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
- Center of Excellence in Cardiac Electrophysiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
- Department of Oral Biology and Diagnostic Sciences, Faculty of Dentistry, Chiang Mai University, Chiang Mai, Thailand
| |
Collapse
|
2
|
Signaling pathways in obesity: mechanisms and therapeutic interventions. Signal Transduct Target Ther 2022; 7:298. [PMID: 36031641 PMCID: PMC9420733 DOI: 10.1038/s41392-022-01149-x] [Citation(s) in RCA: 51] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 07/26/2022] [Accepted: 08/08/2022] [Indexed: 12/19/2022] Open
Abstract
Obesity is a complex, chronic disease and global public health challenge. Characterized by excessive fat accumulation in the body, obesity sharply increases the risk of several diseases, such as type 2 diabetes, cardiovascular disease, and nonalcoholic fatty liver disease, and is linked to lower life expectancy. Although lifestyle intervention (diet and exercise) has remarkable effects on weight management, achieving long-term success at weight loss is extremely challenging, and the prevalence of obesity continues to rise worldwide. Over the past decades, the pathophysiology of obesity has been extensively investigated, and an increasing number of signal transduction pathways have been implicated in obesity, making it possible to fight obesity in a more effective and precise way. In this review, we summarize recent advances in the pathogenesis of obesity from both experimental and clinical studies, focusing on signaling pathways and their roles in the regulation of food intake, glucose homeostasis, adipogenesis, thermogenesis, and chronic inflammation. We also discuss the current anti-obesity drugs, as well as weight loss compounds in clinical trials, that target these signals. The evolving knowledge of signaling transduction may shed light on the future direction of obesity research, as we move into a new era of precision medicine.
Collapse
|
3
|
Lei LM, Lin X, Xu F, Shan SK, Guo B, Li FXZ, Zheng MH, Wang Y, Xu QS, Yuan LQ. Exosomes and Obesity-Related Insulin Resistance. Front Cell Dev Biol 2021; 9:651996. [PMID: 33816504 PMCID: PMC8012888 DOI: 10.3389/fcell.2021.651996] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 02/24/2021] [Indexed: 12/13/2022] Open
Abstract
Exosomes are extracellular vesicles, delivering signal molecules from donor cells to recipient cells. The cargo of exosomes, including proteins, DNA and RNA, can target the recipient tissues and organs, which have an important role in disease development. Insulin resistance is a kind of pathological state, which is important in the pathogeneses of type 2 diabetes mellitus (T2DM), gestational diabetes mellitus and Alzheimer's disease. Furthermore, obesity is a kind of inducement of insulin resistance. In this review, we summarized recent research advances on exosomes and insulin resistance, especially focusing on obesity-related insulin resistance. These studies suggest that exosomes have great importance in the development of insulin resistance in obesity and have great potential for use in the diagnosis and therapy of insulin resistance.
Collapse
Affiliation(s)
- Li-Min Lei
- National Clinical Research Center for Metabolic Disease, Hunan Provincial Key Laboratory of Metabolic Bone Diseases, Department of Endocrinology and Metabolism, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Xiao Lin
- Department of Radiology, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Feng Xu
- National Clinical Research Center for Metabolic Disease, Hunan Provincial Key Laboratory of Metabolic Bone Diseases, Department of Endocrinology and Metabolism, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Su-Kang Shan
- National Clinical Research Center for Metabolic Disease, Hunan Provincial Key Laboratory of Metabolic Bone Diseases, Department of Endocrinology and Metabolism, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Bei Guo
- National Clinical Research Center for Metabolic Disease, Hunan Provincial Key Laboratory of Metabolic Bone Diseases, Department of Endocrinology and Metabolism, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Fu-Xing-Zi Li
- National Clinical Research Center for Metabolic Disease, Hunan Provincial Key Laboratory of Metabolic Bone Diseases, Department of Endocrinology and Metabolism, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Ming-Hui Zheng
- National Clinical Research Center for Metabolic Disease, Hunan Provincial Key Laboratory of Metabolic Bone Diseases, Department of Endocrinology and Metabolism, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Yi Wang
- National Clinical Research Center for Metabolic Disease, Hunan Provincial Key Laboratory of Metabolic Bone Diseases, Department of Endocrinology and Metabolism, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Qiu-Shuang Xu
- National Clinical Research Center for Metabolic Disease, Hunan Provincial Key Laboratory of Metabolic Bone Diseases, Department of Endocrinology and Metabolism, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Ling-Qing Yuan
- National Clinical Research Center for Metabolic Disease, Hunan Provincial Key Laboratory of Metabolic Bone Diseases, Department of Endocrinology and Metabolism, The Second Xiangya Hospital, Central South University, Changsha, China
| |
Collapse
|
4
|
Grinder-Hansen L, Ribel-Madsen R, Wojtaszewski JFP, Poulsen P, Grunnet LG, Vaag A. A common variation of the PTEN gene is associated with peripheral insulin resistance. DIABETES & METABOLISM 2016; 42:280-4. [PMID: 27068875 DOI: 10.1016/j.diabet.2016.03.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 03/02/2016] [Accepted: 03/12/2016] [Indexed: 12/13/2022]
Abstract
AIM Phosphatase and tensin homologue (PTEN) reduces insulin sensitivity by inhibiting the phosphatidylinositol 3-kinase (PI3K)/v-akt murine thymoma viral oncogene homologue (Akt) pathway. This study investigated how a common single nucleotide polymorphism near PTEN, previously associated with fasting levels of plasma insulin and glucose, influences in vivo glucose metabolism and insulin signalling. The primary outcome measure was the gene variant's association with peripheral glucose disposal rate and, secondarily, whether this association was explained by altered activities of PTEN targets PI3K and Akt. METHODS A total of 183 normoglycaemic Danes, including 158 twins and 25 singletons, were genotyped for PTEN rs11202614, which is in complete linkage disequilibrium with rs2142136 and rs10788575, which have also been reported in association with glycaemic traits and type 2 diabetes (T2D). Hepatic and peripheral insulin sensitivity was measured using tracer and euglycaemic-hyperinsulinaemic clamp techniques; insulin secretion was assessed by intravenous glucose tolerance test; and muscle biopsies were taken during insulin infusion from 150 twins for measurement of PI3K and Akt activities. RESULTS The minor G allele of PTEN rs11202614 was associated with elevated fasting plasma insulin levels and a decreased peripheral glucose disposal rate, but not with the hepatic insulin resistance index or insulin secretion measured as the first-phase insulin response and disposition index. The single nucleotide polymorphism was not associated with either PI3K or Akt activities. CONCLUSION A common PTEN variation is associated with peripheral insulin resistance and subsequent risk of developing T2D. However, the association with insulin resistance is not explained by decreased proximal insulin signalling in skeletal muscle.
Collapse
Affiliation(s)
- L Grinder-Hansen
- Department of Endocrinology, Diabetes and Metabolism, Rigshospitalet, Tagensvej 20, DK-2200 Copenhagen N, Denmark
| | - R Ribel-Madsen
- Department of Endocrinology, Diabetes and Metabolism, Rigshospitalet, Tagensvej 20, DK-2200 Copenhagen N, Denmark; The Danish Diabetes Academy, Odense University Hospital, Sondre Boulevard 29, DK-5000 Odense, Denmark; Section of Metabolic Genetics, The Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Universitetsparken 1, DK-2100 Copenhagen O, Denmark.
| | - J F P Wojtaszewski
- Section of Molecular Physiology, The August Krogh Centre, Department of Nutrition, Exercise and Sports, University of Copenhagen, Universitetsparken 13, DK-2100 Copenhagen O, Denmark
| | - P Poulsen
- Novo Nordisk A/S, Vandtårnsvej 108, DK-2860 Soborg, Denmark
| | - L G Grunnet
- Department of Endocrinology, Diabetes and Metabolism, Rigshospitalet, Tagensvej 20, DK-2200 Copenhagen N, Denmark
| | - A Vaag
- Department of Endocrinology, Diabetes and Metabolism, Rigshospitalet, Tagensvej 20, DK-2200 Copenhagen N, Denmark
| |
Collapse
|
5
|
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.
Collapse
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
| |
Collapse
|
6
|
Tonks KT, Ng Y, Miller S, Coster ACF, Samocha-Bonet D, Iseli TJ, Xu A, Patrick E, Yang JYH, Junutula JR, Modrusan Z, Kolumam G, Stöckli J, Chisholm DJ, James DE, Greenfield JR. Impaired Akt phosphorylation in insulin-resistant human muscle is accompanied by selective and heterogeneous downstream defects. Diabetologia 2013; 56:875-85. [PMID: 23344726 DOI: 10.1007/s00125-012-2811-y] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Accepted: 11/29/2012] [Indexed: 01/04/2023]
Abstract
AIMS/HYPOTHESIS Muscle insulin resistance, one of the earliest defects associated with type 2 diabetes, involves changes in the phosphoinositide 3-kinase/Akt network. The relative contribution of obesity vs insulin resistance to perturbations in this pathway is poorly understood. METHODS We used phosphospecific antibodies against targets in the Akt signalling network to study insulin action in muscle from lean, overweight/obese and type 2 diabetic individuals before and during a hyperinsulinaemic-euglycaemic clamp. RESULTS Insulin-stimulated Akt phosphorylation at Thr309 and Ser474 was highly correlated with whole-body insulin sensitivity. In contrast, impaired phosphorylation of Akt substrate of 160 kDa (AS160; also known as TBC1D4) was associated with adiposity, but not insulin sensitivity. Neither insulin sensitivity nor obesity was associated with defective insulin-dependent phosphorylation of forkhead box O (FOXO) transcription factor. In view of the resultant basal hyperinsulinaemia, we predicted that this selective response within the Akt pathway might lead to hyperactivation of those processes that were spared. Indeed, the expression of genes targeted by FOXO was downregulated in insulin-resistant individuals. CONCLUSIONS/INTERPRETATION These results highlight non-linearity in Akt signalling and suggest that: (1) the pathway from Akt to glucose transport is complex; and (2) pathways, particularly FOXO, that are not insulin-resistant, are likely to be hyperactivated in response to hyperinsulinaemia. This facet of Akt signalling may contribute to multiple features of the metabolic syndrome.
Collapse
Affiliation(s)
- K T Tonks
- Diabetes and Obesity Research Program, Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst, 2010 NSW, Australia
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
7
|
Friedrichsen M, Birk JB, Richter EA, Ribel-Madsen R, Pehmøller C, Hansen BF, Beck-Nielsen H, Hirshman MF, Goodyear LJ, Vaag A, Poulsen P, Wojtaszewski JFP. Akt2 influences glycogen synthase activity in human skeletal muscle through regulation of NH₂-terminal (sites 2 + 2a) phosphorylation. Am J Physiol Endocrinol Metab 2013; 304:E631-9. [PMID: 23321478 PMCID: PMC3774094 DOI: 10.1152/ajpendo.00494.2012] [Citation(s) in RCA: 14] [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: 11/22/2022]
Abstract
Type 2 diabetes is characterized by reduced muscle glycogen synthesis. The key enzyme in this process, glycogen synthase (GS), is activated via proximal insulin signaling, but the exact molecular events remain unknown. Previously, we demonstrated that phosphorylation of Thr³⁰⁸ on Akt (p-Akt-Thr³⁰⁸), Akt2 activity, and GS activity in muscle were positively associated with insulin sensitivity. Here, in the same study population, we determined the influence of several upstream elements in the canonical PI3K signaling on muscle GS activation. One-hundred eighty-one nondiabetic twins were examined with the euglycemic hyperinsulinemic clamp combined with excision of muscle biopsies. Insulin signaling was evaluated at the levels of the insulin receptor, IRS-1-associated PI3K (IRS-1-PI3K), Akt, and GS employing activity assays and phosphospecific Western blotting. The insulin-stimulated GS activity was positively associated with p-Akt-Thr³⁰⁸ (P = 0.01) and Akt2 activity (P = 0.04) but not p-Akt-Ser⁴⁷³ or IRS-1-PI3K activity. Furthermore, p-Akt-Thr³⁰⁸ and Akt2 activity were negatively associated with NH₂-terminal GS phosphorylation (P = 0.001 for both), which in turn was negatively associated with insulin-stimulated GS activity (P < 0.001). We found no association between COOH-terminal GS phosphorylation and Akt or GS activity. Employing whole body Akt2-knockout mice, we validated the necessity for Akt2 in insulin-mediated GS activation. However, since insulin did not affect NH₂-terminal phosphorylation in mice, we could not use this model to validate the observed association between GS NH₂-terminal phosphorylation and Akt activity in humans. In conclusion, our study suggests that although COOH-terminal dephosphorylation is likely necessary for GS activation, Akt2-dependent NH₂-terminal dephosphorylation may be the site for "fine-tuning" insulin-mediated GS activation in humans.
Collapse
|
8
|
Friedrichsen M, Poulsen P, Wojtaszewski J, Hansen PR, Vaag A, Rasmussen HB. Carboxylesterase 1 gene duplication and mRNA expression in adipose tissue are linked to obesity and metabolic function. PLoS One 2013; 8:e56861. [PMID: 23468884 PMCID: PMC3585247 DOI: 10.1371/journal.pone.0056861] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Accepted: 01/14/2013] [Indexed: 11/19/2022] Open
Abstract
CONTEXT AND AIMS Carboxylesterase 1 (CES1) appears to play an important role in the control of the metabolism of triglycerides and cholesterol in adipocytes and other cell types including hepatocytes. Therefore, it is relevant to gain insights into the genetic versus non-genetic mechanisms involved in the control of CES1 mRNA expression. Here, we investigated CES1 mRNA expression level in adipose tissue and its association with measures of adiposity and metabolic function in a population of elderly twins. Furthermore, the heritability of CES1 mRNA expression level in adipose tissue and the effect of CES1 gene duplication were assessed. METHODOLOGY A total of 295 monozygotic and dizygotic twin subjects (62-83 years) with (n = 48) or without (n = 247) type 2 diabetes mellitus were enrolled in the study. They were subjected to a standard oral glucose tolerance test and excision of abdominal subcutaneous fat biopsies during the fasting state. Levels of CES1 mRNA and copy number of the gene were assessed by quantitative PCR. RESULTS CES1 mRNA expression level in adipose tissue was positively associated with body-mass index (P<0.001), homeostasis model assessment-insulin resistance (P = 0.003) and level of fasting glucose (P = 0.002), insulin (P = 0.006), and triglycerides (P = 0.003). The heritability for the expression of CES1 mRNA in adipose tissue was high. CES1 gene duplication was positively associated with insulin sensitivity (P = 0.05) as well as glucose tolerance (P = 0.03) and negatively associated with homeostasis model assessment-insulin resistance (P = 0.02). Duplication of CES1 was not linked to mRNA level of this gene (P = 0.63). CONCLUSION CES1 mRNA in adipose tissue appears to be under strong genetic control and was associated with measures of metabolic function raising the possibility of a potential role of this enzyme in the development of type 2 diabetes mellitus. Further studies are needed to understand the potential effect of CES1 gene duplication on adipocyte and whole-body metabolic functions.
Collapse
Affiliation(s)
- Martin Friedrichsen
- Department of Diabetes and Metabolism, Rigshospitalet, Copenhagen, Denmark
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | | | - Jørgen Wojtaszewski
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Peter Riis Hansen
- Department of Cardiology, Copenhagen University Hospital Gentofte, Hellerup, Denmark
| | - Allan Vaag
- Department of Diabetes and Metabolism, Rigshospitalet, Copenhagen, Denmark
| | - Henrik Berg Rasmussen
- Research Institute of Biological Psychiatry, Mental Health Centre Sct. Hans, Copenhagen University Hospital, Roskilde, Denmark
- * E-mail:
| |
Collapse
|
9
|
Obesity-induced insulin resistance in human skeletal muscle is characterised by defective activation of p42/p44 MAP kinase. PLoS One 2013; 8:e56928. [PMID: 23468892 PMCID: PMC3585240 DOI: 10.1371/journal.pone.0056928] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Accepted: 01/16/2013] [Indexed: 01/14/2023] Open
Abstract
Insulin resistance (IR), an impaired cellular, tissue and whole body response to insulin, is a major pathophysiological defect of type 2 diabetes mellitus. Although IR is closely associated with obesity, the identity of the molecular defect(s) underlying obesity-induced IR in skeletal muscle remains controversial; reduced post-receptor signalling of the insulin receptor substrate 1 (IRS1) adaptor protein and downstream effectors such as protein kinase B (PKB) have previously been implicated. We examined expression and/or activation of a number of components of the insulin-signalling cascade in skeletal muscle of 22 healthy young men (with body mass index (BMI) range, 20-37 kg/m(2)). Whole body insulin sensitivity (M value) and body composition was determined by the hyperinsulinaemic (40 mU. min(-1).m(-2).), euglycaemic clamp and by dual energy X-ray absorptiometry (DEXA) respectively. Skeletal muscle (vastus lateralis) biopsies were taken before and after one hour of hyperinsulinaemia and the muscle insulin signalling proteins examined by western blot and immunoprecipitation assay. There was a strong inverse relationship between M-value and BMI. The most striking abnormality was significantly reduced insulin-induced activation of p42/44 MAP kinase, measured by specific assay, in the volunteers with poor insulin sensitivity. However, there was no relationship between individuals' BMI or M-value and protein expression/phosphorylation of IRS1, PKB, or p42/44 MAP kinase protein, under basal or hyperinsulinaemic conditions. In the few individuals with poor insulin sensitivity but preserved p42/44 MAP kinase activation, other signalling defects were evident. These findings implicate defective p42/44 MAP kinase signalling as a potential contributor to obesity-related IR in a non-diabetic population, although clearly multiple signalling defects underlie obesity associated IR.
Collapse
|
10
|
Ma X, Tsuda S, Yang X, Gu N, Tanabe H, Oshima R, Matsushita T, Egawa T, Dong AJ, Zhu BW, Hayashi T. Pu-erh tea hot-water extract activates Akt and induces insulin-independent glucose transport in rat skeletal muscle. J Med Food 2013; 16:259-62. [PMID: 23437791 DOI: 10.1089/jmf.2012.2520] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Skeletal muscle is a major organ that is important for whole-body glucose metabolism. We found that when isolated rat epitrochlearis muscle was incubated with a Pu-erh tea hot-water extract (PTE) for 30 min, the rate of 3-O-methyl-D-glucose (3MG) transport increased in the absence of insulin. This activation was associated with an increase in Ser(473) phosphorylation of Akt, a signaling intermediary leading to insulin-dependent glucose transport, but not Tyr(458) phosphorylation of phosphoinositide 3-kinase p85, an upstream molecule of Akt. PTE-stimulated 3MG transport was also not accompanied by Thr(172) phosphorylation of the catalytic α-subunit of 5'-AMP-activated protein kinase (AMPK). Gallic acid, a water-soluble ingredient in Pu-erh tea, stimulated Akt phosphorylation, but not AMPK phosphorylation. These results suggest that Pu-erh tea potentially promotes skeletal muscle glucose transport at least in part by activating Akt.
Collapse
Affiliation(s)
- Xiao Ma
- Laboratory of Sports and Exercise Medicine, Kyoto University Graduate School of Human and Environmental Studies, Kyoto, Japan.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
11
|
Amino acids potentiate insulin signaling in CHO-K1 at high glucose conditions. Arch Med Res 2012; 43:173-82. [PMID: 22609522 DOI: 10.1016/j.arcmed.2012.04.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2011] [Accepted: 03/26/2012] [Indexed: 12/14/2022]
Abstract
BACKGROUND AND AIMS Amino acids reportedly increase the glucose uptake under high glucose conditions. However, there are controversies in the role of amino acids in diabetes mellitus. The present study explores the insulin signaling pathway involved in glucose uptake mediated by amino acids in CHO-K1 cells. METHODS CHO-K1 cells were exposed to normal (7 mM) and high glucose (17 and 27 mM) with 100 nM insulin in the presence and absence of amino acid mixtures (AAM) in varying concentration (5 and 20 mM) followed by the assays, insulin receptor tyrosine kinase (IRTK) and phosphatidylinositol 3 kinase (PI3K) by autoradiography, protein kinase B (Akt) and glucose transporter (GLUT4) by Western blot and glycogen synthase (GS) by HPLC. RESULTS The addition of 5 and 20 mM AAM significantly increased IRTK and PI3K activity (ANOVA p = 0.025, p = 0.003, respectively) with increasing glucose concentration. Addition of 5 mM AAM in the presence of normal glucose significantly increased the levels of phosphorylated Akt Ser473 (p = 0.02) with no significant change at high glucose. At 20 mM AAM there was a significant decrease in Akt phosphorylation (p = 0.035) that was increased by high glucose concentration. GLUT4 protein levels were increased with AAM (5 mM) along with increase in glycogen synthase activity at all glucose concentrations (p <0.05). CONCLUSIONS Amino acids as a mixture is beneficial in augmenting insulin signaling pathway via IRTK/PI3K/GLUT4 pathway along with activation of GS in CHO-K1 cells, thereby ensuring increased intracellular glucose availability.
Collapse
|
12
|
De Blasio MJ, Gatford KL, Harland ML, Robinson JS, Owens JA. Placental restriction reduces insulin sensitivity and expression of insulin signaling and glucose transporter genes in skeletal muscle, but not liver, in young sheep. Endocrinology 2012; 153:2142-51. [PMID: 22434080 DOI: 10.1210/en.2011-1955] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Poor growth before birth is associated with impaired insulin sensitivity later in life, increasing the risk of type 2 diabetes. The tissue sites at which insulin resistance first develops after intrauterine growth restriction (IUGR), and its molecular basis, are unclear. We have therefore characterized the effects of placental restriction (PR), a major cause of IUGR, on whole-body insulin sensitivity and expression of molecular determinants of insulin signaling and glucose uptake in skeletal muscle and liver of young lambs. Whole-body insulin sensitivity was measured at 30 d by hyperinsulinaemic euglycaemic clamp and expression of insulin signaling genes (receptors, pathways, and targets) at 43 d in muscle and liver of control (n = 15) and PR (n = 13) lambs. PR reduced size at birth and increased postnatal growth, fasting plasma glucose (+15%, P = 0.004), and insulin (+115%, P = 0.009). PR reduced whole-body insulin sensitivity (-43%, P < 0.001) and skeletal muscle expression of INSR (-36%), IRS1 (-28%), AKT2 (-44%), GLUT4 (-88%), GSK3α (-35%), and GYS1 (-31%) overall (each P < 0.05) and decreased AMPKγ3 expression in females (P = 0.030). PR did not alter hepatic expression of insulin signaling and related genes but increased GLUT2 expression (P = 0.047) in males. Whole-body insulin sensitivity correlated positively with skeletal muscle expression of IRS1, AKT2, HK, AMPKγ2, and AMPKγ3 in PR lambs only (each P < 0.05) but not with hepatic gene expression in control or PR lambs. Onset of insulin resistance after PR and IUGR is accompanied by, and can be accounted for by, reduced expression of insulin signaling and metabolic genes in skeletal muscle but not liver.
Collapse
Affiliation(s)
- Miles J De Blasio
- The Robinson Institute and School of Pediatrics and Reproductive Health, University of Adelaide, Adelaide, South Australia 5005, Australia
| | | | | | | | | |
Collapse
|
13
|
Vendelbo MH, Clasen BFF, Treebak JT, Møller L, Krusenstjerna-Hafstrøm T, Madsen M, Nielsen TS, Stødkilde-Jørgensen H, Pedersen SB, Jørgensen JOL, Goodyear LJ, Wojtaszewski JFP, Møller N, Jessen N. Insulin resistance after a 72-h fast is associated with impaired AS160 phosphorylation and accumulation of lipid and glycogen in human skeletal muscle. Am J Physiol Endocrinol Metab 2012; 302:E190-200. [PMID: 22028408 PMCID: PMC4971894 DOI: 10.1152/ajpendo.00207.2011] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
During fasting, human skeletal muscle depends on lipid oxidation for its energy substrate metabolism. This is associated with the development of insulin resistance and a subsequent reduction of insulin-stimulated glucose uptake. The underlying mechanisms controlling insulin action on skeletal muscle under these conditions are unresolved. In a randomized design, we investigated eight healthy subjects after a 72-h fast compared with a 10-h overnight fast. Insulin action on skeletal muscle was assessed by a hyperinsulinemic euglycemic clamp and by determining insulin signaling to glucose transport. In addition, substrate oxidation, skeletal muscle lipid content, regulation of glycogen synthesis, and AMPK signaling were assessed. Skeletal muscle insulin sensitivity was reduced profoundly in response to a 72-h fast and substrate oxidation shifted to predominantly lipid oxidation. This was associated with accumulation of both lipid and glycogen in skeletal muscle. Intracellular insulin signaling to glucose transport was impaired by regulation of phosphorylation at specific sites on AS160 but not TBC1D1, both key regulators of glucose uptake. In contrast, fasting did not impact phosphorylation of AMPK or insulin regulation of Akt, both of which are established upstream kinases of AS160. These findings show that insulin resistance in muscles from healthy individuals is associated with suppression of site-specific phosphorylation of AS160, without Akt or AMPK being affected. This impairment of AS160 phosphorylation, in combination with glycogen accumulation and increased intramuscular lipid content, may provide the underlying mechanisms for resistance to insulin in skeletal muscle after a prolonged fast.
Collapse
Affiliation(s)
| | - B. F. F. Clasen
- Departments of 1Internal Medicine and Endocrinology and
- 2Clinical Pharmacology, Aarhus University Hospital, Aarhus;
| | - J. T. Treebak
- 3Molecular Physiology Group, Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen;
| | - L. Møller
- Departments of 1Internal Medicine and Endocrinology and
| | | | - M. Madsen
- Departments of 1Internal Medicine and Endocrinology and
| | - T. S. Nielsen
- Departments of 1Internal Medicine and Endocrinology and
- 2Clinical Pharmacology, Aarhus University Hospital, Aarhus;
| | | | | | | | - L. J. Goodyear
- 5Joslin Diabetes Center and Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts
| | - J. F. P. Wojtaszewski
- 3Molecular Physiology Group, Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen;
| | - N. Møller
- Departments of 1Internal Medicine and Endocrinology and
| | - N. Jessen
- Departments of 1Internal Medicine and Endocrinology and
- 2Clinical Pharmacology, Aarhus University Hospital, Aarhus;
| |
Collapse
|