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Jiang JX, Tomilov A, Montgomery C, Hui CK, Török NJ, Cortopassi G. Shc inhibitor idebenone ameliorates liver injury and fibrosis in dietary NASH in mice. J Biochem Mol Toxicol 2021; 35:e22876. [PMID: 34369032 DOI: 10.1002/jbt.22876] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 07/20/2021] [Accepted: 07/24/2021] [Indexed: 12/20/2022]
Abstract
Shc expression rises in human nonalcoholic steatohepatitis (NASH) livers, and Shc-deficient mice are protected from NASH-thus Shc inhibition could be a novel therapeutic strategy for NASH. Idebenone was recently identified as the first small-molecule Shc inhibitor drug. We tested idebenone in the fibrotic methionine-choline deficient (MCD) diet and the metabolic fast food diet (FFD) mouse models of NASH. In the fibrotic MCD NASH model, idebenone reduced Shc expression and phosphorylation in peripheral blood mononuclear cells and Shc expression in the liver; decreased serum alanine aminotransferase and aspartate aminotransferase; and attenuated liver fibrosis as observed by quantitative polymerase chain reaction (qPCR) and hydroxyproline quantification. In the metabolic FFD model, idebenone administration improved insulin resistance, and reduced inflammation and fibrosis shown with qPCR, hydroxyproline measurement, and histology. Thus, idebenone ameliorates NASH in two mouse models. As an approved drug with a benign safety profile, Idebenone could be a reasonable human NASH therapy.
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Affiliation(s)
- Joy X Jiang
- Department of Molecular Biosciences, School of Veterinary Medicine, Davis, California, USA
| | - Alexey Tomilov
- Department of Molecular Biosciences, School of Veterinary Medicine, Davis, California, USA
| | - Claire Montgomery
- Department of Molecular Biosciences, School of Veterinary Medicine, Davis, California, USA
| | - Chun Kui Hui
- Department of Molecular Biosciences, School of Veterinary Medicine, Davis, California, USA
| | - Natalie J Török
- Gastroenterology and Hepatology, Stanford University, Palo Alto, California, USA.,VA Palo Alto, Palo Alto, California, USA
| | - Gino Cortopassi
- Department of Molecular Biosciences, School of Veterinary Medicine, Davis, California, USA
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Tomilov A, Allen S, Hui CK, Bettaieb A, Cortopassi G. Idebenone is a cytoprotective insulin sensitizer whose mechanism is Shc inhibition. Pharmacol Res 2018; 137:89-103. [PMID: 30290222 DOI: 10.1016/j.phrs.2018.09.024] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Revised: 09/20/2018] [Accepted: 09/24/2018] [Indexed: 01/04/2023]
Abstract
When insulin binds insulin receptor, IRS1 signaling is stimulated to trigger the maximal insulin response. p52Shc protein competes directly with IRS1, thus damping and diverting maximal insulin response. Genetic reduction of p52Shc minimizes competition with IRS1, and improves insulin signaling and glucose control in mice, and improves pathophysiological consequences of hyperglycemia. Given the multiple benefits of Shc reduction in vivo, we investigated whether any of 1680 drugs used in humans may function as Shc inhibitors, and thus potentially serve as novel anti-diabetics. Of the 1680, 30 insulin sensitizers were identified by screening in vitro, and of these 30 we demonstrated that 7 bound Shc protein. Of the 7 drugs, idebenone dose-dependently bound Shc protein in the 50-100 nM range, and induced insulin sensitivity and cytoprotection in this same 100 nM range that clinically dosed idebenone reaches in human plasma. By contrast we observe mitochondrial effects of idebenone in the 5,000 nM range that are not reached in human dosing. Multiple assays of target engagement demonstrate that idebenone physically interacts with Shc protein. Idebenone sensitizes mice to insulin in two different mouse models of prediabetes. Genetic depletion of idebenone's target eliminates idebenone's ability to insulin-sensitize in vivo. Thus, idebenone is the first-in-class member of a novel category of insulin-sensitizing and cytoprotective agents, the Shc inhibitors. Idebenone is an approved drug and could be considered for other indications such as type 2 diabetes and fatty liver disease, in which insulin resistance occurs.
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Affiliation(s)
- Alexey Tomilov
- Department of Molecular Biosciences, 1089 Veterinary Medicine Dr., VM3B, UC Davis, CA, 95616, USA.
| | - Sonia Allen
- Department of Molecular Biosciences, 1089 Veterinary Medicine Dr., VM3B, UC Davis, CA, 95616, USA.
| | - Chun Kiu Hui
- Department of Molecular Biosciences, 1089 Veterinary Medicine Dr., VM3B, UC Davis, CA, 95616, USA.
| | - Ahmed Bettaieb
- Department of Nutrition, The University of Tennessee, 1215 W. Cumberland Ave, Knoxville, TN, 37996-1920, USA.
| | - Gino Cortopassi
- Department of Molecular Biosciences, 1089 Veterinary Medicine Dr., VM3B, UC Davis, CA, 95616, USA.
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Ramalingam L, Oh E, Thurmond DC. Novel roles for insulin receptor (IR) in adipocytes and skeletal muscle cells via new and unexpected substrates. Cell Mol Life Sci 2013; 70:2815-34. [PMID: 23052216 PMCID: PMC3556358 DOI: 10.1007/s00018-012-1176-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Revised: 08/21/2012] [Accepted: 09/18/2012] [Indexed: 01/30/2023]
Abstract
The insulin signaling pathway regulates whole-body glucose homeostasis by transducing extracellular signals from the insulin receptor (IR) to downstream intracellular targets, thus coordinating a multitude of biological functions. Dysregulation of IR or its signal transduction is associated with insulin resistance, which may culminate in type 2 diabetes. Following initial stimulation of IR, insulin signaling diverges into different pathways, activating multiple substrates that have roles in various metabolic and cellular processes. The integration of multiple pathways arising from IR activation continues to expand as new IR substrates are identified and characterized. Accordingly, our review will focus on roles for IR substrates as they pertain to three primary areas: metabolism/glucose uptake, mitogenesis/growth, and aging/longevity. While IR functions in a seemingly pleiotropic manner in many cell types, through these three main roles in fat and skeletal muscle cells, IR multi-tasks to regulate whole-body glucose homeostasis to impact healthspan and lifespan.
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Affiliation(s)
- Latha Ramalingam
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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Fatani S, Abubakari AR, Itua I, Wong C, Thomas C, Naderali EK. Effects of diet-induced obesity on protein expression in insulin signaling pathways of skeletal muscle in male Wistar rats. Int J Gen Med 2012; 5:573-82. [PMID: 22866009 PMCID: PMC3410719 DOI: 10.2147/ijgm.s31819] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND The prevalence of diet-induced obesity is increasing globally, and posing significant health problems for millions of people worldwide. Diet-induced obesity is a major contributor to the global pandemic of type 2 diabetes mellitus. The reduced ability of muscle tissue to regulate glucose homeostasis plays a major role in the development and prognosis of type 2 diabetes. In this study, an animal model of diet-induced obesity was used to elucidate changes in skeletal muscle insulin signaling in obesity-induced diabetes. METHODS Adult male Wistar rats were randomized and assigned to either a control group or to a test group. Controls were fed a standard laboratory pellet diet (chow-fed), while the test group had free access to a highly palatable diet (diet-fed). After 8 weeks, the diet-fed animals were subdivided into three subgroups and their diets were altered as follows: diet-to-chow, diet-fed with addition of fenofibrate given by oral gavage for a further 7 weeks, or diet-fed with vehicle given by oral gavage for a further 7 weeks, respectively. RESULTS Untreated diet-fed animals had a significantly higher body weight and metabolic profile than the control chow-fed animals. Intramuscular triacylglyceride levels in the untreated obese animals were significantly higher than those in the control chow-fed group. Expression of protein kinase C beta, phosphatidylinositol 3, Shc, insulin receptor substrate 1, ERK1/2, and endothelial nitric oxide synthase was significantly increased by dietary obesity, while that of insulin receptor beta, insulin receptor substrate 1, and protein kinase B (Akt) were not affected by obesity. CONCLUSION These data suggest that diet-induced obesity affects insulin signaling mechanisms, leading to insulin resistance in muscle.
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Affiliation(s)
- Sameer Fatani
- Obesity Biology Unit, School of Clinical Sciences, University of Liverpool, Liverpool, UK
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Fontana L, Klein S, Holloszy JO. Effects of long-term calorie restriction and endurance exercise on glucose tolerance, insulin action, and adipokine production. AGE (DORDRECHT, NETHERLANDS) 2010; 32:97-108. [PMID: 19904628 PMCID: PMC2829643 DOI: 10.1007/s11357-009-9118-z] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2009] [Accepted: 10/13/2009] [Indexed: 05/28/2023]
Abstract
Calorie restriction (CR) slows aging and is thought to improve insulin sensitivity in laboratory animals. In contrast, decreased insulin signaling and/or mild insulin resistance paradoxically extends maximal lifespan in various genetic animal models of longevity. Nothing is known regarding the long-term effects of CR on glucose tolerance and insulin action in lean healthy humans. In this study we evaluated body composition, glucose, and insulin responses to an oral glucose tolerance test and serum adipokines levels in 28 volunteers, who had been eating a CR diet for an average of 6.9 +/- 5.5 years, (mean age 53.0 +/- 11 years), in 28 age-, sex-, and body fat-matched endurance runners (EX), and 28 age- and sex-matched sedentary controls eating Western diets (WD). We found that the CR and EX volunteers were significantly leaner than the WD volunteers. Insulin sensitivity, determined according to the HOMA-IR and the Matsuda and DeFronzo insulin sensitivity indexes, was significantly higher in the CR and EX groups than in the WD group (P = 0.001). Nonetheless, despite high serum adiponectin and low inflammation, approximately 40% of CR individuals exhibited an exaggerated hyperglycemic response to a glucose load. This impaired glucose tolerance is associated with lower circulating levels of IGF-1, total testosterone, and triiodothyronine, which are typical adaptations to life-extending CR in rodents.
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Affiliation(s)
- Luigi Fontana
- Washington University School of Medicine, St. Louis, MO 63110, USA.
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Rocha EM, Carvalho CRO, Saad MJA, Velloso LA. The influence of ageing on the insulin signalling system in rat lacrimal and salivary glands. ACTA ACUST UNITED AC 2004; 81:639-45. [PMID: 14641268 DOI: 10.1111/j.1395-3907.2003.00162.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
PURPOSE Ageing adversely affects the structure and function of lacrimal and salivary glands (LG and SG) and leads to marked insulin resistance that correlates with reduced insulin signal transduction. The aim of this study was to investigate whether ageing affects insulin signal transduction in LG and SG in vivo. METHODS Male Wistar rats aged 20 months and 2 months (control group) were compared (n=8/group). Samples were removed under anaesthesia after i.v. injection of insulin, homogenized, immunoprecipitated with anti-insulin receptor (IR), Shc and STAT-1 antibodies and immunoblotted with antiphosphotyrosine antibody. RESULTS The 20-month-old rats were significantly hyperinsulinaemic and presented a reduced rate of blood glucose disappearance in response to insulin, compared to the 2-month-old rats. The level of phosphorylation determined by densitometry in the older group of rats showed that ageing significantly reduced insulin-induced IR phosphorylation in LG and SG and STAT-1 phosphorylation in SG, compared to in the control group, but did not alter Shc phosphorylation. CONCLUSIONS Ageing influences insulin signal transduction in the LG and SG of rats. Considering the major anabolic actions of insulin, these observations may help to explain the mechanisms of LG and SG dysfunctions observed in ageing.
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Affiliation(s)
- Eduardo M Rocha
- Laboratory of Medical Physiopathology, Department of Clinical Medicine, Faculty of Medical Science, State University of Campinas (UNICAMP), São Paulo, Brazil.
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Carvalheira JBC, Ribeiro EB, Araújo EP, Guimarães RB, Telles MM, Torsoni M, Gontijo JAR, Velloso LA, Saad MJA. Selective impairment of insulin signalling in the hypothalamus of obese Zucker rats. Diabetologia 2003; 46:1629-40. [PMID: 14600817 DOI: 10.1007/s00125-003-1246-x] [Citation(s) in RCA: 119] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2003] [Revised: 08/04/2003] [Indexed: 02/07/2023]
Abstract
AIM/HYPOTHESIS By acting in the brain, insulin suppresses food intake. However, little is known with regard to insulin signalling in the hypothalamus in insulin-resistant states. METHODS Western blotting, immunohistochemistry and polymerase chain reaction assays were combined to compare in vivo hypothalamic insulin signalling through the PI3-kinase and MAP kinase pathways between lean and obese Zucker rats. RESULTS Intracerebroventricular insulin infusion reduced food intake in lean rats to a greater extent than that observed in obese rats, and pre-treatment with PI3-kinase inhibitors prevented insulin-induced anorexia. The relative abundance of IRS-2 was considerably higher than that of IRS-1 in hypothalamus of both lean and obese rats. Insulin-stimulated phosphorylation of IR, IRS-1/2, the associations of PI 3-kinase to IRS-1/2 and phosphorylation of Akt in hypothalamus were decreased in obese rats compared to lean rats. These effects seem to be mediated by increased phosphoserine content of IR, IRS-1/2 and decreased protein levels of IRS-1/2 in obese rats. In contrast, insulin stimulated the phosphorylation of MAP kinase equally in lean and obese rats. CONCLUSION/INTERPRETATION This study provides direct measurements of insulin signalling in hypothalamus, and documents selective resistance to insulin signalling in hypothalamus of Zucker rats. These findings provide support for the hypothesis that insulin could have anti-obesity actions mediated by the PI3-kinase pathway, and that impaired insulin signalling in hypothalamus could play a role in the development of obesity in this animal model of insulin-resistance.
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Affiliation(s)
- J B C Carvalheira
- Departamento de Clínica Médica, FCM, Universidade Estadual de Campinas (UNICAMP), 13081-970, Campinas, SP, Brasil
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Torsoni MA, Carvalheira JB, Pereira-Da-Silva M, de Carvalho-Filho MA, Saad MJA, Velloso LA. Molecular and functional resistance to insulin in hypothalamus of rats exposed to cold. Am J Physiol Endocrinol Metab 2003; 285:E216-23. [PMID: 12644444 DOI: 10.1152/ajpendo.00031.2003] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Insulin and leptin act in the hypothalamus, providing robust anorexigenic signals. The exposure of homeothermic animals to a cold environment leads to increased feeding, accompanied by sustained low levels of insulin and leptin. In the present study, the initial and intermediate steps of the insulin-signaling cascade were evaluated in the hypothalamus of cold-exposed Wistar rats. By immunohistochemistry, most insulin receptor (IR) and insulin receptor substrate-2 (IRS-2) immunoreactivity localized to the arcuate nucleus. Basal levels of tyrosine phosphorylation of IR and IRS-2 were increased in cold-exposed rats compared with rats maintained at room temperature. However, after an acute, peripheral infusion of exogenous insulin, significantly lower increases of IR and IRS-2 tyrosine phosphorylation were detected in the hypothalamus of cold-exposed rats. Insulin-induced association of p85/phosphatidylinositol 3-kinase with IRS-2, Ser473 phosphorylation of Akt, and tyrosine phosphorylation of ERK was significantly reduced in the hypothalamus of cold-exposed rats. To test the hypothesis of functional impairment of insulin signaling in the hypothalamus, intracerebroventricularly cannulated rats were acutely treated with insulin, and food ingestion was measured over a period of 12 h. Cold-exposed animals presented a significantly lower insulin-induced reduction in food consumption compared with animals maintained at room temperature. Hence, the present studies reveal that animals exposed to cold are resistant, both at the molecular and the functional level, to the actions of insulin in the hypothalamus.
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Affiliation(s)
- Márcio A Torsoni
- Department of Internal Medicine, State University of Campinas, Brazil
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Du K, Herzig S, Kulkarni RN, Montminy M. TRB3: a tribbles homolog that inhibits Akt/PKB activation by insulin in liver. Science 2003; 300:1574-7. [PMID: 12791994 DOI: 10.1126/science.1079817] [Citation(s) in RCA: 682] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Insulin resistance is a major hallmark in the development of type II diabetes, which is characterized by the failure of insulin to promote glucose uptake in muscle and to suppress glucose production in liver. The serine-threonine kinase Akt (PKB) is a principal target of insulin signaling that inhibits hepatic glucose output when glucose is available from food. Here we show that TRB3, a mammalian homolog of Drosophila tribbles, functions as a negative modulator of Akt. TRB3 expression is induced in liver under fasting conditions, and TRB3 disrupts insulin signaling by binding directly to Akt and blocking activation of the kinase. Amounts of TRB3 RNA and protein were increased in livers of db/db diabetic mice compared with those in wild-type mice. Hepatic overexpression of TRB3 in amounts comparable to those in db/db mice promoted hyperglycemia and glucose intolerance. Our results suggest that, by interfering with Akt activation, TRB3 contributes to insulin resistance in individuals with susceptibility to type II diabetes.
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Affiliation(s)
- Keyong Du
- Peptide Biology Laboratories, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037-1002, USA
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Rocha EM, Carvalho CRO, Saad MJA, Velloso LA. The influence of aging in the insulin-signaling system in rat exocrine glands. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2003; 506:27-31. [PMID: 12613885 DOI: 10.1007/978-1-4615-0717-8_3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- Eduardo M Rocha
- Laboratory of Clinical Physiopathology, Department of Clinical Medicine, FCM-UNICAMP, Campinas, São Paulo, Brazil
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Abstract
A insulina é um hormônio anabólico com efeitos metabólicos potentes. Os eventos que ocorrem após a ligação da insulina são específicos e estritamente regulados. Definir as etapas que levam à especificidade deste sinal representa um desafio para as pesquisas bioquímicas, todavia podem resultar no desenvolvimento de novas abordagens terapêuticas para pacientes que sofrem de estados de resistência à insulina, inclusive o diabetes tipo 2. O receptor de insulina pertence a uma família de receptores de fatores de crescimento que têm atividade tirosina quinase intrínseca. Após a ligação da insulina o receptor sofre autofosforilação em múltiplos resíduos de tirosina. Isto resulta na ativação da quinase do receptor e conseqüente fosforilação em tirosina de um a família de substratos do receptor de insulina (IRS). De forma similar a outros fatores de crescimento, a insulina usa fosforilação e interações proteína-proteína como ferramentas essenciais para transmitir o sinal. Estas interações proteína-proteína são fundamentais para transmitir o sinal do receptor em direção ao efeito celular final, tais como translocação de vesículas contendo transportadores de glicose (GLUT4) do pool intracelular para a membrana plasmática, ativação da síntese de glicogênio e de proteínas, e transcrição de genes específicos.
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