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Park SE, Park CY, Sweeney G. Biomarkers of insulin sensitivity and insulin resistance: Past, present and future. Crit Rev Clin Lab Sci 2015; 52:180-90. [PMID: 26042993 DOI: 10.3109/10408363.2015.1023429] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Insulin resistance in insulin target tissues including liver, skeletal muscle and adipose tissue is an early step in the progression towards type 2 diabetes. Accurate diagnostic parameters reflective of insulin resistance are essential. Longstanding tests for fasting blood glucose and HbA1c are useful and although the hyperinsulinemic euglycemic clamp remains a "gold standard" for accurately determining insulin resistance, it cannot be implemented on a routine basis. The study of adipokines, and more recently myokines and hepatokines, as potential biomarkers for insulin sensitivity is now an attractive and relatively straightforward approach. This review discusses potential biomarkers including adiponectin, RBP4, chemerin, A-FABP, FGF21, fetuin-A, myostatin, IL-6, and irisin, all of which may play significant roles in determining insulin sensitivity. We also review potential future directions of new biological markers for measuring insulin resistance, including metabolomics and gut microbiome. Collectively, these approaches will provide clinicians with the tools for more accurate, and perhaps personalized, diagnosis of insulin resistance.
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Affiliation(s)
- Se Eun Park
- a Division of Endocrinology and Metabolism, Department of Internal Medicine , Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine , Seoul , South Korea and
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Lee J, Hong SW, Park SE, Rhee EJ, Park CY, Oh KW, Park SW, Lee WY. Exendin-4 Inhibits the Expression of SEPP1 and Fetuin-A via Improvement of Palmitic Acid-Induced Endoplasmic Reticulum Stress by AMPK. Endocrinol Metab (Seoul) 2015; 30:177-84. [PMID: 26194078 PMCID: PMC4508262 DOI: 10.3803/enm.2015.30.2.177] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Revised: 05/30/2014] [Accepted: 06/24/2014] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Selenoprotein P (SEPP1) and fetuin-A, both circulating liver-derived glycoproteins, are novel biomarkers for insulin resistance and nonalcoholic fatty liver disease. However, the effect of exendin-4 (Ex-4), a glucagon-like peptide-1 receptor agonist, on the expression of hepatokines, SEPP1, and fetuin-A, is unknown. METHODS The human hepatoma cell line HepG2 was treated with palmitic acid (PA; 0.4 mM) and tunicamycin (tuni; 2ug/ml) with or without exendin-4 (100 nM) for 24 hours. The change in expression of PA-induced SEPP1, fetuin-A, and endoplasmic reticulum (ER) stress markers by exendin-4 treatment were evaluated using quantitative real-time reverse transcription polymerase chain reaction and Western blotting. Transfection of cells with AMP-activated protein kinase (AMPK) small interfering RNA (siRNA) was performed to establish the effect of exendin-4-mediated AMPK in the regulation of SEPP1 and fetuin-A expression. RESULTS Exendin-4 reduced the expression of SEPP1, fetuin-A, and ER stress markers including PKR-like ER kinase, inositol-requiring kinase 1α, activating transcription factor 6, and C/EBP homologous protein in HepG2 cells. Exendin-4 also reduced the expression of SEPP1 and fetuin-A in cells treated with tunicamycin, an ER stress inducer. In cells treated with the AMPK activator 5-aminoidazole-4-carboxamide ribonucleotide (AICAR), the expression of hepatic SEPP1 and fetuin-A were negatively related by AMPK, which is the target of exendin-4. In addition, exendin-4 treatment did not decrease SEPP1 and fetuin-A expression in cells transfected with AMPK siRNA. CONCLUSION These data suggest that exendin-4 can attenuate the expression of hepatic SEPP1 and fetuin-A via improvement of PA-induced ER stress by AMPK.
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Affiliation(s)
- Jinmi Lee
- Institute of Medical Research, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Seok Woo Hong
- Institute of Medical Research, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Se Eun Park
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Eun Jung Rhee
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Cheol Young Park
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Ki Won Oh
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Sung Woo Park
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Won Young Lee
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea.
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Yu XH, Zheng XL, Tang CK. Nuclear Factor-κB Activation as a Pathological Mechanism of Lipid Metabolism and Atherosclerosis. Adv Clin Chem 2015; 70:1-30. [PMID: 26231484 DOI: 10.1016/bs.acc.2015.03.004] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Atherosclerosis is a chronic inflammatory disease of the arterial wall with lipid-laden lesions, involving a complex interaction between multiple different cell types and cytokine networks. Inflammatory responses mark all stages of atherogenesis: from lipid accumulation in the intima to plaque formation and eventual rupture. One of the most important regulators of inflammation is the transcription factor nuclear factor-κB (NF-κB), which is activated through the canonical and noncanonical pathways in response to various stimuli. NF-κB has long been regarded as a proatherogenic factor, because it is implicated in multiple pathological processes during atherogenesis, including foam cell formation, vascular inflammation, proliferation of vascular smooth muscle cells, arterial calcification, and plaque progression. In contrast, inhibition of NF-κB signaling has been shown to protect against atherosclerosis. This chapter aims to discuss recent progress on the roles of NF-κB in lipid metabolism and atherosclerosis and also to highlight its potential therapeutic benefits.
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Affiliation(s)
- Xiao-Hua Yu
- Key Laboratory for Atherosclerology of Hunan Province, Molecular Target New Drug Discovery and Cooperative Innovation Center of Hunan Province, Life Science Research Center, University of South China, Hengyang, PR China
| | - Xi-Long Zheng
- Department of Biochemistry and Molecular Biology, The Libin Cardiovascular Institute of Alberta, Cumming School of Medicine, The University of Calgary, Health Sciences Center, Calgary, Alberta, Canada
| | - Chao-Ke Tang
- Key Laboratory for Atherosclerology of Hunan Province, Molecular Target New Drug Discovery and Cooperative Innovation Center of Hunan Province, Life Science Research Center, University of South China, Hengyang, PR China.
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Molecular and immunohistochemical effects of metformin in a rat model of type 2 diabetes mellitus. Exp Ther Med 2015; 9:1921-1930. [PMID: 26136915 DOI: 10.3892/etm.2015.2354] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2014] [Accepted: 03/05/2015] [Indexed: 12/14/2022] Open
Abstract
Type 2 diabetes mellitus (T2DM) is a serious health issue worldwide. The disease is characterized by insulin resistance (IR), which leads to dyslipidemia and alterations in the expression levels of a number of genes. Metformin is the standard treatment for T2DM; however, the exact mechanism underlying metformin regulation is not fully understood. The aim of the present study was to investigate the effects of metformin on serum lipid profiles and the expression levels of various genes that are associated with IR, as well as the histopathological changes in the liver and pancreas. A T2DM rat model was established by feeding the rats a high-fat diet for 4 weeks, combined with a dose of streptozotocin (35 mg/kg body weight). Following the successful induction of T2DM, metformin was administered orally (400 mg/kg/day) for 4 weeks. The results indicated that metformin improved the symptoms of IR by normalizing the serum lipid profiles in the diabetic rats. Furthermore, metformin upregulated the expression of insulin receptors and genes associated with lipid metabolism, including acyl-CoA oxidase, carnitine palmitoyl transferase-1 and peroxisome proliferator activated receptor-α. In addition, treatment with metformin downregulated the expression levels of fetuin-A and retinol binding protein-4 (RBP-4), while normalizing the expression of perilipin that had been reduced in the T2DM rats. Metformin administration induced regenerative changes in the hepatocyte cytoplasm and parenchyma. In the pancreas, treatment with metformin was shown to induce positive signaling for insulin and the regeneration of pancreatic β cells. In summary, metformin treatment ameliorated a number of the harmful effects associated with T2DM via the modulation of the expression levels of fetuin-A, RBP-4, perilipin and various genes associated with lipid metabolism, resulting in regenerative changes in the liver and pancreatic cells.
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Alderete TL, Sattler FR, Richey JM, Allayee H, Mittelman SD, Sheng X, Tucci J, Gyllenhammer LE, Grant EG, Goran MI. Salsalate treatment improves glycemia without altering adipose tissue in nondiabetic obese hispanics. Obesity (Silver Spring) 2015; 23:543-51. [PMID: 25644856 PMCID: PMC4340767 DOI: 10.1002/oby.20991] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Accepted: 11/13/2014] [Indexed: 01/01/2023]
Abstract
OBJECTIVE Salsalate treatment has well-known effects on improving glycemia, and the objective of this study was to examine whether the mechanism of this effect was related to changes in adipose tissue. METHODS A randomized double-blind and placebo-controlled trial in obese Hispanics (18-35 years) was conducted. The intervention consisted of 4 g day(-1) of salsalate (n = 11) versus placebo (n = 13) for 4 weeks. Outcome measures included glycemia, adiposity, ectopic fat, and adipose tissue gene expression and inflammation. RESULTS In those receiving salsalate, plasma fasting glucose decreased by 3.4% (P < 0.01), free fatty acids decreased by 42.5% (P = 0.06), and adiponectin increased by 27.7% (P < 0.01). Salsalate increased insulin AUC by 38% (P = 0.01) and HOMA-B by 47.2% (P < 0.01) while estimates of insulin sensitivity/resistance were unaffected. These metabolic improvements occurred without changes in total, abdominal, visceral, or liver fat. Plasma markers of inflammation/immune activation were unchanged following salsalate. Salsalate had no effects on adipose tissue including adipocyte size, presence of crown-like structures, or gene expression of adipokines, immune cell markers, or cytokines downstream of NF-κB with the exception of downregulation of IL-1β (P < 0.01). CONCLUSIONS Findings suggest that metabolic improvements in response to salsalate occurred without alterations in adiposity, ectopic fat, or adipose tissue gene expression and inflammation.
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Affiliation(s)
- Tanya L Alderete
- Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
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Abstract
Non-alcoholic fatty liver disease, which is considered a hepatic manifestation of metabolic syndrome, independently increases the risks of developing cardiovascular disease (CVD) and type 2 diabetes mellitus. Recent emerging evidence suggests that a group of predominantly liver-derived proteins called hepatokines directly affect the progression of atherosclerosis by modulating endothelial dysfunction and infiltration of inflammatory cells into vessel walls. Here, we summarize the role of the representative hepatokines fibroblast growth factor 21, fetuin-A, and selenoprotein P in the progression of CVD.
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Affiliation(s)
- Hye Jin Yoo
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Korea University College of Medicine, Seoul, Korea
| | - Kyung Mook Choi
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Korea University College of Medicine, Seoul, Korea
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Trepanowski JF, Mey J, Varady KA. Fetuin-A: a novel link between obesity and related complications. Int J Obes (Lond) 2014; 39:734-41. [PMID: 25468829 DOI: 10.1038/ijo.2014.203] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 10/04/2014] [Accepted: 11/02/2014] [Indexed: 12/13/2022]
Abstract
Fetuin-A (FetA) is a 64-kDa glycoprotein that is secreted from both the liver and adipose tissue. Circulating FetA is elevated in obesity and related disorders including type 2 diabetes mellitus, nonalcoholic fatty liver disease and the metabolic syndrome; and a FetA-related parameter, caliciprotein particle, is highly relevant to vascular calcification in overweight/obese patients with chronic kidney disease. FetA level is also associated with impaired insulin sensitivity and glucose tolerance. Accumulating evidence suggests that elevated FetA level causes impaired glycemic control, as FetA has been implicated in impairment of insulin receptor signaling, toll-like receptor 4 activation, macrophage migration and polarization, adipocyte dysfunction, hepatocyte triacylglycerol accumulation and liver inflammation and fibrosis. Weight loss, aerobic exercise, metformin and pioglitazone have each been shown to be effective for reducing FetA level.
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Affiliation(s)
- J F Trepanowski
- Department of Kinesiology and Nutrition, University of Illinois at Chicago, Chicago, IL, USA
| | - J Mey
- Department of Kinesiology and Nutrition, University of Illinois at Chicago, Chicago, IL, USA
| | - K A Varady
- Department of Kinesiology and Nutrition, University of Illinois at Chicago, Chicago, IL, USA
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Mukhopadhyay S, Mondal SA, Kumar M, Dutta D. Proinflammatory and Antiinflammatory Attributes of Fetu Iν-A: A Novel Hepatokine Modulating Cardiovascular and Glycemic Outcomes in Metabolic Syndrome. Endocr Pract 2014; 20:1345-1351. [DOI: 10.4158/ep14421.ra] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
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Knebel B, Lehr S, Hartwig S, Haas J, Kaber G, Dicken HD, Susanto F, Bohne L, Jacob S, Nitzgen U, Passlack W, Muller-Wieland D, Kotzka J. Phosphorylation of sterol regulatory element-binding protein (SREBP)-1c by p38 kinases, ERK and JNK influences lipid metabolism and the secretome of human liver cell line HepG2. Arch Physiol Biochem 2014; 120:216-27. [PMID: 25353341 DOI: 10.3109/13813455.2014.973418] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The transcription factor sterol regulatory element binding protein (SREBP)-1c plays a pivotal role in lipid metabolism. In this report we identified the main phosphorylation sites of MAPK-families, i.e. p38 stress-activated MAPK (p38), ERK-MAPK (ERK) or c-JUN N-terminal protein kinases (JNK) in SREBP-1c. The major phosphorylation sites of p38, i.e. serine 39 and threonine 402, are identical to those we recently identified in the splice-variant SREBP-1a. In contrast, ERK and JNK phosphorylate SREBP-1c at two major sites, i.e. threonine 81 and serine 93, instead of one site in SREBP-1a. Functional analyses of the biological outcome in the human liver cell line HepG2 reveals SREBP-1c phosphorylation dependent alteration in lipid metabolism and secretion pattern of lipid transporting proteins, e.g. ApoE or ApoA1. These results suggest that phosphorylation of SREBP-1c by different MAPKs interferes with lipid metabolism and the secretory activity of liver cells.
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Affiliation(s)
- Birgit Knebel
- Institute of Clinical Biochemistry and Pathobiochemistry, German Diabetes Center at the Heinrich-Heine-University Duesseldorf, Leibniz Center for Diabetes Research , Duesseldorf , Germany
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Xu XJ, Valentine RJ, Ruderman NB. AMP-activated Protein Kinase (AMPK): Does This Master Regulator of Cellular Energy State Distinguish Insulin Sensitive from Insulin Resistant Obesity? Curr Obes Rep 2014; 3:248-55. [PMID: 24891985 PMCID: PMC4039173 DOI: 10.1007/s13679-014-0095-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Although a correlation exists between obesity and insulin resistance, roughly 25 % of obese individuals are insulin sensitive. AMP-activated protein kinase (AMPK) is a cellular energy sensor that among its many actions, integrates diverse physiological signals to restore energy balance. In addition, in many situations it also increases insulin sensitivity. In this context, AMPK activity is decreased in very obese individuals undergoing bariatric surgery who are insulin resistant compared to equally obese patients who are insulin sensitive. In this review, we will both explore what distinguishes these individuals, and evaluate the evidence that diminished AMPK is associated with insulin resistance and metabolic syndrome-associated disorders in other circumstances.
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Yin J, Luo Y, Deng H, Qin S, Tang W, Zeng L, Zhou B. Hugan Qingzhi medication ameliorates hepatic steatosis by activating AMPK and PPARα pathways in L02 cells and HepG2 cells. JOURNAL OF ETHNOPHARMACOLOGY 2014; 154:229-239. [PMID: 24735863 DOI: 10.1016/j.jep.2014.04.011] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Revised: 03/15/2014] [Accepted: 04/05/2014] [Indexed: 06/03/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Hugan Qingzhi tablet (HQT), a lipid- lowering traditional Chinese medicine formula, has been used for the prevention and treatment of nonalcoholic fatty liver (NAFLD). AIM OF THE STUDY This study was realized to evaluate the effects of HQT-medicated serum on hepatic steatosis using in vitro experiments with cells and explore the relevant mechanisms with method of serum pharmacology. MATERIALS AND METHODS A model of hepatic steatosis in the L02 and HepG2 cells was induced by free fatty acid (FFA). The components in the HQT-medicated serum were assayed by high-performance liquid chromatography. Intracellular lipid droplets were detected by Oil Red O staining, and their ultrastructure was examined by transmission electron microscope. The biochemical parameters, including triglyceride (TG), lactate dehydrogenase (LDH), aspartate aminotransferase (AST) and alanine aminotransferase (ALT), total antioxidant capacity (T-AOC), malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione (GSH), were measured with commercial kits. Furthermore, the expression of adiponectin, AMP-activated protein kinase (AMPK) phosphorylation, sterol regulatory element-binding protein 1 (SREBP-1), peroxisome proliferator activated receptor-α (PPARα), carnitine palmitoyltransferase 1 (CPT-1), and acetyl-CoA oxidase 1 (ACOX1) was analyzed by Western blot and/or quantitative reverse transcription-polymerase chain reaction (qRT-PCR). RESULTS Moderate- and high-dose HQT-medicated serum reduced (P<0.05 or P<0.01) the accumulation of lipid droplets and the cellular TG content in L02 and HepG2 cells. They caused significant reductions (P<0.01) in LDH, AST, ALT and MDA and significant increase (P<0.05 or P<0.01) in T-AOC in the culture medium. They also caused increase (P<0.05 or P<0.01) in GSH level and SOD activity in FFA-induced steatotic L02 and HepG2 cells. Furthermore, moderate- and high-dose HQT-medicated serum enhanced (P<0.01) adiponectin expression in a concentration-dependent manner and increased (P<0.05 or P<0.01) the phosphorylation of AMPK and the expression of PPARα, CPT-1, and ACOX1, and reduced (P<0.05 or P<0.01) the expression of SREBP-1. CONCLUSION The results suggested that HQT-medicated serum exerts a preventive effect against hepatic steatosis, and the potential mechanism might be activation of AMPK and PPARα pathways.
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Affiliation(s)
- JinJin Yin
- Center for Drug Research and Development, Zhujiang Hospital, Southern Medical University, Guangdong, Guangzhou 510282, PR China
| | - YanQin Luo
- Department of Pharmacy, Nanfang Hospital, Southern Medical University, Guangzhou 510515, PR China
| | - HouLiang Deng
- Center for Drug Research and Development, Zhujiang Hospital, Southern Medical University, Guangdong, Guangzhou 510282, PR China
| | - ShuMin Qin
- Institute of Digestive Disease, Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200032, PR China
| | - WaiJiao Tang
- Center for Drug Research and Development, Zhujiang Hospital, Southern Medical University, Guangdong, Guangzhou 510282, PR China
| | - Lu Zeng
- Center for Drug Research and Development, Zhujiang Hospital, Southern Medical University, Guangdong, Guangzhou 510282, PR China
| | - BenJie Zhou
- Center for Drug Research and Development, Zhujiang Hospital, Southern Medical University, Guangdong, Guangzhou 510282, PR China.
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