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  1. Endothelin-1 exacerbates development of hypertension and atherosclerosis in modest insulin resistant syndrome

    activation, whereas remained insulin-induced ERK activation. ET-1 and insulin synergistically potentiated migration and proliferation mainly through ETAR/ERK dependent pathway, which is dominant in VSMCs during modest insulin resistance syndrome. Therefore, ET-1 and ETAR are potential targets responsible for the observed synergism effect in the hypertensive atherosclerotic process through enhancement of ET-1 binding, ET-1 binding, ETAR expression, and ET-1-induced mitogenic actions in aortic VSMCs. - Highlights: • ET-1/ETAR signaling and insulin-induced pERK were high in modest insulin resistance. • ET-1 via ETAR suppressed insulin-induced pAKT but remained intact pERK in VSMCs. • Insulin potentiated ET-1-induced VSMC mitogenic action was ETAR/ERK dependent

  2. Endothelin-1 exacerbates development of hypertension and atherosclerosis in modest insulin resistant syndrome

    Lin, Yan-Jie [Institute of Physiology, National Yang-Ming University, Taipei, Taiwan (China); Department of Medical Research, Taipei Veterans General Hospital, Taipei, Taiwan (China); Juan, Chi-Chang [Institute of Physiology, National Yang-Ming University, Taipei, Taiwan (China); Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan (China); Kwok, Ching-Fai [Division of Endocrinology and Metabolism, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan (China); Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan (China); Hsu, Yung-Pei [Department of Medical Research, Taipei Veterans General Hospital, Taipei, Taiwan (China); Shih, Kuang-Chung [Division of Endocrinology and Metabolism, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan (China); Chen, Chin-Chang [Institute of Physiology, National Yang-Ming University, Taipei, Taiwan (China); Ho, Low-Tone, E-mail: ltho@vghtpe.gov.tw [Institute of Physiology, National Yang-Ming University, Taipei, Taiwan (China); Division of Endocrinology and Metabolism, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan (China); Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan (China); Department of Medical Research, Taipei Veterans General Hospital, Taipei, Taiwan (China)

    2015-05-08

    suppressed insulin-induced AKT activation, whereas remained insulin-induced ERK activation. ET-1 and insulin synergistically potentiated migration and proliferation mainly through ET{sub A}R/ERK dependent pathway, which is dominant in VSMCs during modest insulin resistance syndrome. Therefore, ET-1 and ET{sub A}R are potential targets responsible for the observed synergism effect in the hypertensive atherosclerotic process through enhancement of ET-1 binding, ET-1 binding, ET{sub A}R expression, and ET-1-induced mitogenic actions in aortic VSMCs. - Highlights: • ET-1/ET{sub A}R signaling and insulin-induced pERK were high in modest insulin resistance. • ET-1 via ET{sub A}R suppressed insulin-induced pAKT but remained intact pERK in VSMCs. • Insulin potentiated ET-1-induced VSMC mitogenic action was ET{sub A}R/ERK dependent.

  3. High Protein Intake Improves Insulin Sensitivity but Exacerbates Bone Resorption in Immobility (WISE Study)

    Heer, Martina; Smith, Scott M.; Frings-Meuthen, Petra; Zwart, Sara R.; Baecker, Natalie

    2012-01-01

    Inactivity, like bed rest (BR), causes insulin resistance (IR) and bone loss even in healthy subjects. High protein intake seems to mitigate this IR but might exacerbate bone loss. We hypothesized that high protein intake (animal:vegetable protein ratio: 60:40), isocaloric, compared to the control group plus high potassium intake would prevent IR without affecting bone turnover. After a 20-day ambulatory adaptation to controlled confinement and diet, 16 women participated in a 60-day, 6 deg head-down-tilt BR and were assigned randomly to one of the two groups. Control subjects (CON, n=8) received 1g/kg body mass/d dietary protein. Nutrition subjects (NUT, n=8) received 1.45g/kg body mass/d dietary protein plus 7.2g branched chain amino acids per day during BR. All subjects received 1670 kcal/d. Bed rest decreased glucose disposal by 35% (pprotein intake prevented insulin resistance, but exacerbated bed rest induced increase in bone resorption markers C-telopeptide (> 30%) and Ntelopeptide (>20%) (both: pprotein intake. We conclude from these results that high protein intake might positively affect glucose tolerance, but might also foster bone loss. Further long-duration studies are mandatory before high protein intake for diabetic patients, who have an increased fracture risk, might be recommended.

  4. Insulin deficiency exacerbates cerebral amyloidosis and behavioral deficits in an Alzheimer transgenic mouse model

    Teng Wei-Ping

    2010-11-01

    Full Text Available Abstract Background Although increasing evidence has indicated that brain insulin dysfunction is a risk factor for Alzheimer disease (AD, the underlying mechanisms by which insulin deficiency may impact the development of AD are still obscure. Using a streptozotocin (STZ-induced insulin deficient diabetic AD transgenic mouse model, we evaluated the effect of insulin deficiency on AD-like behavior and neuropathology. Results Our data showed that administration of STZ increased the level of blood glucose and reduced the level of serum insulin, and further decreased the phosphorylation levels of insulin receptors, and increased the activities of glycogen synthase kinase-3α/β and c-Jun N-terminal kinase in the APP/PS1 mouse brain. We further showed that STZ treatment promoted the processing of amyloid-β (Aβ precursor protein resulting in increased Aβ generation, neuritic plaque formation, and spatial memory deficits in transgenic mice. Conclusions Our present data indicate that there is a close link between insulin deficient diabetes and cerebral amyloidosis in the pathogenesis of AD.

  5. Macrophage activation in acute exacerbation of idiopathic pulmonary fibrosis.

    Jonas Christian Schupp

    Full Text Available Acute exacerbation (AE of idiopathic pulmonary fibrosis (IPF is a common cause of disease acceleration in IPF and has a major impact on mortality. The role of macrophage activation in AE of IPF has never been addressed before.We evaluated BAL cell cytokine profiles and BAL differential cell counts in 71 IPF patients w/wo AE and in 20 healthy volunteers. Twelve patients suffered from AE at initial diagnosis while sixteen patients developed AE in the 24 months of follow-up. The levels of IL-1ra, CCL2, CCL17, CCL18, CCL22, TNF-α, IL-1β, CXCL1 and IL-8 spontaneously produced by BAL-cells were analysed by ELISA.In patients with AE, the percentage of BAL neutrophils was significantly increased compared to stable patients. We found an increase in the production rate of the pro-inflammatory cytokines CXCL1 and IL-8 combined with an increase in all tested M2 cytokines by BAL-cells. An increase in CCL18 levels and neutrophil counts during AE was observed in BAL cells from patients from whom serial lavages were obtained. Furthermore, high baseline levels of CCL18 production by BAL cells were significantly predictive for the development of future AE.BAL cell cytokine production levels at acute exacerbation show up-regulation of pro-inflammatory as well as anti-inflammatory/ M2 cytokines. Our data suggest that AE in IPF is not an incidental event but rather driven by cellular mechanisms including M2 macrophage activation.

  6. Macrophage-derived human resistin exacerbates adipose tissue inflammation and insulin resistance in mice

    Qatanani, Mohammed; Szwergold, Nava R.; Greaves, David R.; Ahima, Rexford S.; Lazar, Mitchell A.

    2009-01-01

    Resistin is an adipokine that contributes to insulin resistance in mice. In humans, however, studies investigating the link between resistin and metabolic disease are conflicting. Further complicating the matter, human resistin is produced mainly by macrophages rather than adipocytes. To address this important issue, we generated mice that lack adipocyte-derived mouse resistin but produce human resistin in a pattern similar to that found in humans, i.e., in macrophages (humanized resistin mic...

  7. Diclofenac derivatives with insulin-sensitizing activity

    Jian Ta Wang; Ying Wang; Ji Quan Zhang; Xing Cui; Yi Zhang; Gao Feng Zhu; Lei Tang

    2011-01-01

    A series of diclofenac derivatives were synthesized. The insulin-sensitizing activity of 28 new compounds was evaluated in 3T3-L1 cells. The compounds 10a and 10f exhibited similar insulin-sensitizing activity with positive drag rosiglitazone.

  8. Stress Exacerbates Neuropathic Pain via Glucocorticoid and NMDA Receptor Activation

    Alexander, Jessica K.; DeVries, A. Courtney; KIGERL, KRISTINA A.; Dahlman, Jason M.; G.Popovich, Phillip

    2009-01-01

    There is growing recognition that psychological stress influences pain. Hormones that comprise the physiological response to stress (e.g. corticosterone; CORT) may interact with effectors of neuropathic pain. To test this hypothesis, mice received a spared nerve injury (SNI) after exposure to 60 min restraint stress. In stressed mice, allodynia was consistently increased. The mechanism(s) underlying the exacerbated pain response involves CORT acting via glucocorticoid receptors (GRs); RU486, ...

  9. Relationship between Inflammation markers, Coagulation Activation and Impaired Insulin Sensitivity in Obese Healthy Women

    Obesity, insulin resistance syndrome, and atherosclerosis are closely linked phenomena, often connected with a chronic low grade inflammatory state and pro thrombotic hypo fibrinolytic condition. This study investigated the relationship between impaired insulin sensitivity and selected markers of inflammation and thrombin generation in obese healthy women. The study included 36 healthy obese women (body mass index ≥ 30), with normal insulin sensitivity (NIS, n = 18) or impaired insulin sensitivity (IIS, n 18), and 10 non obese women (body mass index < 25).Impaired insulin sensitivity patients had significantly higher levels of high sensitivity C-reactive protein (hs-CRP), transforming growth factor -β1(TGF-β1), plasminogen activator inhibitor-1 (PAI-1), activated factor VII (VIIa), and prothrombin fragments 1 + 2 (F1 + 2) compared with either control subjects or normal insulin sensitivity patients. On the other hand, NIS patients had higher hs-CRP, TGF-β1, PAI-1, and factor VIIa, but not F1 + 2, levels than controls. Significant inverse correlations were observed between the insulin sensitivity index and TGF-β1, hs-CRP, PAI-1; factor VIIa, and F1 + 2 levels. Moreover, significant direct correlations were noted between TGF-β1 and CRP, PAI-1, factor VIIa, and F1 + 2 concentrations. Finally, multiple regressions revealed that TGF-β1 and the insulin sensitivity index were independently related to F1 + 2. These results document an in vivo relationship between insulin sensitivity and coagulation activation in obesity. Here we report that obesity is associated with higher TGF-β, PAI-1, prothrombin fragments 1 and 2 (F1 + 2), and activated factor VII (VIIa) plasma levels, and that insulin resistance exacerbates these alterations. The elevated TGF-β1 levels detected in the obese population may provide a biochemical link between insulin resistance and an increased risk for cardiovascular disease

  10. Monoclonal antibodies to the human insulin receptor that activate glucose transport but not insulin receptor kinase activity

    Forsayeth, J.R.; Caro, J.F.; Sinha, M.K.; Maddux, B.A.; Goldfine, I.D.

    1987-05-01

    Three mouse monoclonal antibodies were produced that reacted with the ..cap alpha.. subunit of the human insulin receptor. All three both immunoprecipitated /sup 125/I-labeled insulin receptors from IM-9 lymphocytes and competitively inhibited /sup 125/I-labeled insulin binding to its receptor. Unlike insulin, the antibodies failed to stimulate receptor autophosphorylation in both intact IM-9 lymphocytes and purified human placental insulin receptors. Moreover, unlike insulin, the antibodies failed to stimulate receptor-mediated phosphorylation of exogenous substrates. However, like insulin, two of the three antibodies stimulated glucose transport in isolated human adipocytes. One antibody, on a molar basis, was as potent as insulin. These studies indicate, therefore, that monoclonal antibodies to the insulin receptor can mimic a major function of insulin without activating receptor kinase activity. They also raise the possibility that certain actions of insulin such as stimulation of glucose transport may not require the activation of receptor kinase activity.

  11. Monoclonal antibodies to the human insulin receptor that activate glucose transport but not insulin receptor kinase activity

    Three mouse monoclonal antibodies were produced that reacted with the α subunit of the human insulin receptor. All three both immunoprecipitated 125I-labeled insulin receptors from IM-9 lymphocytes and competitively inhibited 125I-labeled insulin binding to its receptor. Unlike insulin, the antibodies failed to stimulate receptor autophosphorylation in both intact IM-9 lymphocytes and purified human placental insulin receptors. Moreover, unlike insulin, the antibodies failed to stimulate receptor-mediated phosphorylation of exogenous substrates. However, like insulin, two of the three antibodies stimulated glucose transport in isolated human adipocytes. One antibody, on a molar basis, was as potent as insulin. These studies indicate, therefore, that monoclonal antibodies to the insulin receptor can mimic a major function of insulin without activating receptor kinase activity. They also raise the possibility that certain actions of insulin such as stimulation of glucose transport may not require the activation of receptor kinase activity

  12. Physical activity and exercise capacity in patients with moderate COPD exacerbations.

    Alahmari, Ayedh D; Kowlessar, Beverly S; Patel, Anant R C; Mackay, Alex J; Allinson, James P; Wedzicha, Jadwiga A; Donaldson, Gavin C

    2016-08-01

    Little is known about changes in physical activity during moderate (out-patient managed) exacerbations.6-min walking distance (6MWD) was measured during 50 exacerbations when the patients were stable, and at 3 and 7 days post-exacerbation presentation. At similar time points, quadriceps maximum voluntary contraction (QMVC) was measured during 47 different exacerbations. Physical activity (SenseWear; Bodymedia Inc., Pittsburgh, PA, USA) was recorded over 2 consecutive-week periods post-presentation.6MWD fell from a median 422 m when stable to 373 m on day 3 (p=0.001). Similarly, QMVC fell from 32.6 versus 29.7 kg (p=0.026). Falls in 6MWD were associated with a rise in C-reactive protein (r= -0.364; p=0.041) and increased Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F) (r= -0.44; p=0.013). Light physical activity was 2.18 h·day(-1) during the first week post-exacerbation and was less over week 2 (1.98 h·day(-1); p=0.009). Patients who had attended pulmonary rehabilitation had smaller changes in 6MWD than those who had not attended (-35.0 versus -114.9 m; p=0.013). Falls in physical activity were correlated with higher depression scores (rho= -0.51; p=0.006).These findings indicate that exercise capacity and muscle strength fall at exacerbation in chronic obstructive pulmonary disease patients who are treated at home and are free to maintain normal activity. PMID:27126688

  13. NOX Activity in Brain Aging: Exacerbation by High Fat Diet

    Bruce-Keller, Annadora J.; White, Christy L.; Gupta, Sunita; Knight, Alecia G.; Pistell, Paul J.; Ingram, Donald K.; Morrison, Christopher D.; Keller, Jeffrey N.

    2010-01-01

    This study describes how age and high fat diet affect the profile of NADPH oxidase (NOX). Specifically, NOX activity and subunit expression were evaluated in the frontal cerebral cortex of 7-, 16-, and 24-month old mice following a 4-month exposure to either Western diet (WD, 41% calories from fat) or very high fat lard diet (VHFD, 60% calories from fat). Data reveal a significant effect of age in on NOX activity, and show that NOX activity was only increased by VHFD, and only in 24-month old...

  14. Insulin

    ... Short Acting Humulin N NPH Human Insulin (Human Insulin Isophane Suspension) Intermediate Acting Novolin N NPH Human Insulin (Human Insulin Isophane Suspension) Intermediate Acting Lantus Insulin Glargine Long Acting ...

  15. A telecare programme for self-management of COPD exacerbations and promotion of an active lifestyle

    Tabak, Monique; Brusse-Keizer, Marjolein; Ommeren, Clara; Kotte, Hayke; Weltevreden, Paul; Hermens, Hermie; Vollenbroek-Hutten, Miriam

    2013-01-01

    Objective: The Condition Coach (CoCo) is a technology-supported care programme for self-management of COPD exacerbations and for promotion of an active lifestyle. The objective is to investigate the added value of the telecare programme in terms of clinical changes compared to usual care, and in add

  16. Evidence that adiponectin receptor 1 activation exacerbates ischemic neuronal death

    Thundyil John

    2010-08-01

    Full Text Available Abstract Background- Adiponectin is a hormone produced in and released from adipose cells, which has been shown to have anti-diabetic and anti-inflammatory actions in peripheral cells. Two cell surface adiponectin receptors (ADRs mediate the majority of the known biological actions of adiponectin. Thus far, ADR expression in the brain has been demonstrated in the arcuate and the paraventricular nucleus of hypothalamus, where its activation affects food intake. Recent findings suggest that levels of circulating adiponectin increase after an ischemic stroke, but the role of adiponectin receptor activation in stroke pathogenesis and its functional outcome is unclear. Methods- Ischemic stroke was induced in C57BL/6 mice by middle cerebral artery occlusion (MCAO for 1 h, followed by reperfusion. Primary cortical neuronal cultures were established from individual embryonic neocortex. For glucose deprivation (GD, cultured neurons were incubated in glucose-free Locke's medium for 6, 12 or 24 h. For combined oxygen and glucose deprivation (OGD, neurons were incubated in glucose-free Locke's medium in an oxygen-free chamber with 95% N2/5% CO2 atmosphere for either 3, 6, 9, 12 or 24 h. Primary neurons and brain tissues were analysed for Adiponectin and ADRs using reverse transcriptase polymerase chain reaction (RT-PCR, immunoblot and immunochemistry methods. Results- Cortical neurons express ADR1 and ADR2, and that the levels of ADR1 are increased in neurons in response to in vitro or in vivo ischemic conditions. Neurons treated with either globular or trimeric adiponectin exhibited increased vulnerability to oxygen and glucose deprivation which was associated with increased activation of a pro-apoptotic signaling cascade involving p38 mitogen-activated protein kinase (p38MAPK and AMP-activated protein kinase (AMPK. Conclusions- This study reveals a novel pathogenic role for adiponectin and adiponectin receptor activation in ischemic stroke. We show that

  17. Insulin resistance is associated with reduced fasting and insulin-stimulated glycogen synthase phosphatase activity in human skeletal muscle.

    Kida, Y; Esposito-Del Puente, A; Bogardus, C; Mott, D M

    1990-01-01

    Insulin-stimulated glycogen synthase activity in human skeletal muscle correlates with insulin-mediated glucose disposal rate (M) and is reduced in insulin-resistant subjects. We have previously reported reduced insulin-stimulated glycogen synthase activity associated with reduced fasting glycogen synthase phosphatase activity in skeletal muscle of insulin-resistant Pima Indians. In this study we investigated the time course for insulin stimulation of glycogen synthase and synthase phosphatas...

  18. Treatment with the 3-ketoacyl-CoA thiolase inhibitor trimetazidine does not exacerbate whole-body insulin resistance in obese mice.

    Ussher, John R; Keung, Wendy; Fillmore, Natasha; Koves, Timothy R; Mori, Jun; Zhang, Liyan; Lopaschuk, David G; Ilkayeva, Olga R; Wagg, Cory S; Jaswal, Jagdip S; Muoio, Deborah M; Lopaschuk, Gary D

    2014-06-01

    There is a growing need to understand the underlying mechanisms involved in the progression of cardiovascular disease during obesity and diabetes. Although inhibition of fatty acid oxidation has been proposed as a novel approach to treat ischemic heart disease and heart failure, reduced muscle fatty acid oxidation rates may contribute to the development of obesity-associated insulin resistance. Our aim was to determine whether treatment with the antianginal agent trimetazidine, which inhibits fatty acid oxidation in the heart secondary to inhibition of 3-ketoacyl-CoA thiolase (3-KAT), may have off-target effects on glycemic control in obesity. We fed C57BL/6NCrl mice a high-fat diet (HFD) for 10 weeks before a 22-day treatment with the 3-KAT inhibitor trimetazidine (15 mg/kg per day). Insulin resistance was assessed via glucose/insulin tolerance testing, and lipid metabolite content was assessed in gastrocnemius muscle. Trimetazidine-treatment led to a mild shift in substrate preference toward carbohydrates as an oxidative fuel source in obese mice, evidenced by an increase in the respiratory exchange ratio. This shift in metabolism was accompanied by an accumulation of long-chain acyl-CoA and a trend to an increase in triacylglycerol content in gastrocnemius muscle, but did not exacerbate HFD-induced insulin resistance compared with control-treated mice. It is noteworthy that trimetazidine treatment reduced palmitate oxidation rates in the isolated working mouse heart and neonatal cardiomyocytes but not C2C12 skeletal myotubes. Our findings demonstrate that trimetazidine therapy does not adversely affect HFD-induced insulin resistance, suggesting that treatment with trimetazidine would not worsen glycemic control in obese patients with angina. PMID:24700885

  19. Sarcopenia exacerbates obesity-associated insulin resistance and dysglycemia: findings from the National Health and Nutrition Examination Survey III.

    Preethi Srikanthan; Hevener, Andrea L.; Karlamangla, Arun S.

    2010-01-01

    BACKGROUND: Sarcopenia often co-exists with obesity, and may have additive effects on insulin resistance. Sarcopenic obese individuals could be at increased risk for type 2 diabetes. We performed a study to determine whether sarcopenia is associated with impairment in insulin sensitivity and glucose homeostasis in obese and non-obese individuals. METHODOLOGY: We performed a cross-sectional analysis of National Health and Nutrition Examination Survey III data utilizing subjects of 20 years or ...

  20. Severe Maternal Hyperglycemia Exacerbates the Development of Insulin Resistance and Fatty Liver in the Offspring on High Fat Diet

    Yong Song

    2012-01-01

    Full Text Available Background. Adverse maternal environments may predispose the offspring to metabolic syndrome in adulthoods, but the underlying mechanism has not been fully understood. Methods. Maternal hyperglycemia was induced by streptozotocin (STZ injection while control (CON rats received citrate buffer. Litters were adjusted to eight pups per dam and then weaned to standard diet. Since 13 weeks old, a subset of offspring from STZ and CON dams were switched to high fat diet (HFD for another 13 weeks. Glucose and insulin tolerance tests (GTT and ITT and insulin secretion assay were performed; serum levels of lipids and leptin were measured. Hepatic fat accumulation and islet area were evaluated through haematoxylin and eosin staining. Results. STZ offspring exhibited lower survival rate, lower birth weights, and growth inhibition which persisted throughout the study. STZ offspring on HFD showed more severe impairment in GTT and ITT, and more profound hepatic steatosis and more severe hyperlipidemia compared with CON-HFD rats. Conclusions. Offspring from diabetic dams would be prone to exhibit low birth weight and postnatal growth inhibition, but could maintain normal glucose tolerance and insulin sensitivity. HFD accelerates development of insulin resistance in the offspring of diabetic dams mainly via a compensatory response of islets.

  1. Sarcopenia exacerbates obesity-associated insulin resistance and dysglycemia: findings from the National Health and Nutrition Examination Survey III.

    Preethi Srikanthan

    2010-05-01

    Full Text Available BACKGROUND: Sarcopenia often co-exists with obesity, and may have additive effects on insulin resistance. Sarcopenic obese individuals could be at increased risk for type 2 diabetes. We performed a study to determine whether sarcopenia is associated with impairment in insulin sensitivity and glucose homeostasis in obese and non-obese individuals. METHODOLOGY: We performed a cross-sectional analysis of National Health and Nutrition Examination Survey III data utilizing subjects of 20 years or older, non-pregnant (N = 14,528. Sarcopenia was identified from bioelectrical impedance measurement of muscle mass. Obesity was identified from body mass index. Outcomes were homeostasis model assessment of insulin resistance (HOMA IR, glycosylated hemoglobin level (HbA1C, and prevalence of pre-diabetes (6.0≤ HbA1C<6.5 and not on medication and type 2 diabetes. Covariates in multiple regression were age, educational level, ethnicity and sex. PRINCIPAL FINDINGS: Sarcopenia was associated with insulin resistance in non-obese (HOMA IR ratio 1.39, 95% confidence interval (CI 1.26 to 1.52 and obese individuals (HOMA-IR ratio 1.16, 95% CI 1.12 to 1.18. Sarcopenia was associated with dysglycemia in obese individuals (HbA1C ratio 1.021, 95% CI 1.011 to 1.043 but not in non-obese individuals. Associations were stronger in those under 60 years of age. We acknowledge that the cross-sectional study design limits our ability to draw causal inferences. CONCLUSIONS: Sarcopenia, independent of obesity, is associated with adverse glucose metabolism, and the association is strongest in individuals under 60 years of age, which suggests that low muscle mass may be an early predictor of diabetes susceptibility. Given the increasing prevalence of obesity, further research is urgently needed to develop interventions to prevent sarcopenic obesity and its metabolic consequences.

  2. Stiffness-activated GEF-H1 expression exacerbates LPS-induced lung inflammation.

    Isa Mambetsariev

    Full Text Available Acute lung injury (ALI is accompanied by decreased lung compliance. However, a role of tissue mechanics in modulation of inflammation remains unclear. We hypothesized that bacterial lipopolysacharide (LPS stimulates extracellular matrix (ECM production and vascular stiffening leading to stiffness-dependent exacerbation of endothelial cell (EC inflammatory activation and lung barrier dysfunction. Expression of GEF-H1, ICAM-1, VCAM-1, ECM proteins fibronectin and collagen, lysyl oxidase (LOX activity, interleukin-8 and activation of Rho signaling were analyzed in lung samples and pulmonary EC grown on soft (1.5 or 2.8 kPa and stiff (40 kPa substrates. LPS induced EC inflammatory activation accompanied by expression of ECM proteins, increase in LOX activity, and activation of Rho signaling. These effects were augmented in EC grown on stiff substrate. Stiffness-dependent enhancement of inflammation was associated with increased expression of Rho activator, GEF-H1. Inhibition of ECM crosslinking and stiffening by LOX suppression reduced EC inflammatory activation and GEF-H1 expression in response to LPS. In vivo, LOX inhibition attenuated LPS-induced expression of GEF-H1 and lung dysfunction. These findings present a novel mechanism of stiffness-dependent exacerbation of vascular inflammation and escalation of ALI via stimulation of GEF-H1-Rho pathway. This pathway represents a fundamental mechanism of positive feedback regulation of inflammation.

  3. Low concentration of arsenite exacerbates UVR-induced DNA strand breaks by inhibiting PARP-1 activity

    Epidemiological studies have associated arsenic exposure with many types of human cancers. Arsenic has also been shown to act as a co-carcinogen even at low concentrations. However, the precise mechanism of its co-carcinogenic action is unknown. Recent studies indicate that arsenic can interfere with DNA-repair processes. Poly(ADP-ribose) polymerase (PARP)-1 is a zinc-finger DNA-repair protein, which can promptly sense DNA strand breaks and initiate DNA-repair pathways. In the present study, we tested the hypothesis that low concentrations of arsenic could inhibit PAPR-1 activity and so exacerbate levels of ultraviolet radiation (UVR)-induced DNA strand breaks. HaCat cells were treated with arsenite and/or UVR, and then DNA strand breaks were assessed by comet assay. Low concentrations of arsenite (≤ 2 μM) alone did not induce significant DNA strand breaks, but greatly enhanced the DNA strand breaks induced by UVR. Further studies showed that 2 μM arsenite effectively inhibited PARP-1 activity. Zinc supplementation of arsenite-treated cells restored PARP-1 activity and significantly diminished the exacerbating effect of arsenite on UVR-induced DNA strand breaks. Importantly, neither arsenite treatment, nor zinc supplementation changed UVR-triggered reactive oxygen species (ROS) formation, suggesting that their effects upon UVR-induced DNA strand breaks are not through a direct free radical mechanism. Combination treatments of arsenite with PARP-1 inhibitor 3-aminobenzamide or PARP-1 siRNA demonstrate that PARP-1 is the target of arsenite. Together, these findings show that arsenite at low concentration exacerbates UVR-induced DNA strand breaks by inhibiting PARP-1 activity, which may represent an important mechanism underlying the co-carcinogenicity of arsenic

  4. Modulation of insulin degrading enzyme activity and liver cell proliferation

    Pivovarova, Olga; von Loeffelholz, Christian; Ilkavets, Iryna; Sticht, Carsten; Zhuk, Sergei; Murahovschi, Veronica; Lukowski, Sonja; Döcke, Stephanie; Kriebel, Jennifer; de las Heras Gala, Tonia; Malashicheva, Anna; Kostareva, Anna; Lock, Johan F; Stockmann, Martin; Grallert, Harald

    2015-01-01

    Diabetes mellitus type 2 (T2DM), insulin therapy, and hyperinsulinemia are independent risk factors of liver cancer. Recently, the use of a novel inhibitor of insulin degrading enzyme (IDE) was proposed as a new therapeutic strategy in T2DM. However, IDE inhibition might stimulate liver cell proliferation via increased intracellular insulin concentration. The aim of this study was to characterize effects of inhibition of IDE activity in HepG2 hepatoma cells and to analyze liver specific expre...

  5. Low concentration of arsenite exacerbates UVR-induced DNA strand breaks by inhibiting PARP-1 activity.

    Qin, Xu-Jun; Hudson, Laurie G; Liu, Wenlan; Timmins, Graham S; Liu, Ke Jian

    2008-10-01

    Epidemiological studies have associated arsenic exposure with many types of human cancers. Arsenic has also been shown to act as a co-carcinogen even at low concentrations. However, the precise mechanism of its co-carcinogenic action is unknown. Recent studies indicate that arsenic can interfere with DNA-repair processes. Poly(ADP-ribose) polymerase (PARP)-1 is a zinc-finger DNA-repair protein, which can promptly sense DNA strand breaks and initiate DNA-repair pathways. In the present study, we tested the hypothesis that low concentrations of arsenic could inhibit PAPR-1 activity and so exacerbate levels of ultraviolet radiation (UVR)-induced DNA strand breaks. HaCat cells were treated with arsenite and/or UVR, and then DNA strand breaks were assessed by comet assay. Low concentrations of arsenite (mechanism. Combination treatments of arsenite with PARP-1 inhibitor 3-aminobenzamide or PARP-1 siRNA demonstrate that PARP-1 is the target of arsenite. Together, these findings show that arsenite at low concentration exacerbates UVR-induced DNA strand breaks by inhibiting PARP-1 activity, which may represent an important mechanism underlying the co-carcinogenicity of arsenic. PMID:18619636

  6. Chronic Toxoplasma gondii in Nurr1-null heterozygous mice exacerbates elevated open field activity.

    Jeffrey B Eells

    Full Text Available Latent infection with Toxoplasma gondii is common in humans (approximately 30% of the global population and is a significant risk factor for schizophrenia. Since prevalence of T. gondii infection is far greater than prevalence of schizophrenia (0.5-1%, genetic risk factors are likely also necessary to contribute to schizophrenia. To test this concept in an animal model, Nurr1-null heterozygous (+/- mice and wild-type (+/+ mice were evaluate using an emergence test, activity in an open field and with a novel object, response to bobcat urine and prepulse inhibition of the acoustic startle response (PPI prior to and 6 weeks after infection with T. gondii. In the emergence test, T. gondii infection significantly decreased the amount of time spent in the cylinder. Toxoplasma gondii infection significantly elevated open field activity in both +/+ and +/- mice but this increase was significantly exacerbated in +/- mice. T. gondii infection reduced PPI in male +/- mice but this was not statistically significant. Aversion to bobcat urine was abolished by T. gondii infection in +/+ mice. In female +/- mice, aversion to bobcat urine remained after T. gondii infection while the male +/- mice showed no aversion to bobcat urine. Antibody titers of infected mice were a critical variable associated with changes in open field activity, such that an inverted U shaped relationship existed between antibody titers and the percent change in open field activity with a significant increase in activity at low and medium antibody titers but no effect at high antibody titers. These data demonstrate that the Nurr1 +/- genotype predisposes mice to T. gondii-induced alterations in behaviors that involve dopamine neurotransmission and are associated with symptoms of schizophrenia. We propose that these alterations in murine behavior were due to further exacerbation of the altered dopamine neurotransmission in Nurr1 +/- mice.

  7. Insulin-like growth factor induced signals activate mitochondrial respiration

    Hütter, E.; Unterluggauer, H.; Viertler, H.P.; Jansen-Dürr, P

    2008-01-01

    From experiments with lower eukaryotes it is known that the metabolic rate and also the rate of aging are tightly controlled by the IGF / insulin signal transduction pathway. The mitochondrial theory of aging implies that an increased metabolic rate leads to increased mitochondrial activity; increased production of reactive oxygen species due to these alterations would speed up the aging process. To address the question if mitochondrial activity is influenced by insulin / IGF signalling, we h...

  8. Designed Inhibitors of Insulin-Degrading Enzyme Regulate the Catabolism and Activity of Insulin

    Leissring, Malcolm A.; Malito, Enrico; Hedouin, Sabrine; Reinstatler, Lael; Sahara, Tomoko; Abdul-Hay, Samer O.; Choudhry, Shakeel; Maharvi, Ghulam M.; Fauq, Abdul H.; Huzarska, Malwina; May, Philip S.; Choi, Sungwoon; Logan, Todd P.; Turk, Benjamin E.; Cantley, Lewis C.; Manolopoulou, Marika; Tang, Wei-Jen; Stein, Ross L.; Cuny, Gregory D.; Selkoe, Dennis J. (Harvard-Med); (BWH); (Yale-MED); (Scripps); (UC); (Mayo)

    2010-09-20

    Insulin is a vital peptide hormone that is a central regulator of glucose homeostasis, and impairments in insulin signaling cause diabetes mellitus. In principle, it should be possible to enhance the activity of insulin by inhibiting its catabolism, which is mediated primarily by insulin-degrading enzyme (IDE), a structurally and evolutionarily distinctive zinc-metalloprotease. Despite interest in pharmacological inhibition of IDE as an attractive anti-diabetic approach dating to the 1950s, potent and selective inhibitors of IDE have not yet emerged. We used a rational design approach based on analysis of combinatorial peptide mixtures and focused compound libraries to develop novel peptide hydroxamic acid inhibitors of IDE. The resulting compounds are {approx} 10{sup 6} times more potent than existing inhibitors, non-toxic, and surprisingly selective for IDE vis-a-vis conventional zinc-metalloproteases. Crystallographic analysis of an IDE-inhibitor complex reveals a novel mode of inhibition based on stabilization of IDE's 'closed,' inactive conformation. We show further that pharmacological inhibition of IDE potentiates insulin signaling by a mechanism involving reduced catabolism of internalized insulin. Conclusions/Significance: The inhibitors we describe are the first to potently and selectively inhibit IDE or indeed any member of this atypical zinc-metalloprotease superfamily. The distinctive structure of IDE's active site, and the mode of action of our inhibitors, suggests that it may be possible to develop inhibitors that cross-react minimally with conventional zinc-metalloproteases. Significantly, our results reveal that insulin signaling is normally regulated by IDE activity not only extracellularly but also within cells, supporting the longstanding view that IDE inhibitors could hold therapeutic value for the treatment of diabetes.

  9. Complement activation, endothelial dysfunction, insulin resistance and chronic heart failure

    Bjerre, M.; Kistorp, C.; Hansen, T.K.;

    2010-01-01

    CRP), endothelial activation (soluble E-selectin, sEsel)), endothelial damage/dysfunction (von Willebrand factor, vWf) and insulin resistance (IR) and prognosis in CHF remains unknown. Design. We investigated the association(s) between plasma sMAC, hsCRP, sEsel, vWf and IR (assessed by homeostatic model assessment...

  10. Soluble urokinase-type plasminogen activator receptor is a novel biomarker predicting acute exacerbation in COPD

    Gumus A

    2015-02-01

    Full Text Available Aziz Gumus,1 Nejat Altintas,2 Halit Cinarka,1 Aynur Kirbas,3 Muge Haziroglu,1 Mevlut Karatas,1 Unal Sahin1 1Department of Pulmonary Medicine, School of Medicine, Recep Tayyip Erdogan University, Rize, Turkey; 2Department of Pulmonary Medicine, School of Medicine, Namik Kemal University, Tekirdag, Turkey; 3Department of Clinical Biochemistry, School of Medicine, Recep Tayyip Erdogan University, Rize, Turkey Background: Chronic obstructive pulmonary disease (COPD is a chronic inflammatory condition, and progresses with acute exacerbations. (AE. During AE, levels of acute phase reactants such as C-reactive protein (CRP and inflammatory cells in the circulation increase. Soluble urokinase-type plasminogen activator receptor (suPAR levels increase in acute viral and bacterial infections and in diseases involving chronic inflammation. The purpose of this study was to investigate the effectiveness of suPAR in predicting diagnosis of AE of COPD (AE-COPD and response to treatment. Methods: The study population consisted of 43 patients diagnosed with AE-COPD and 30 healthy controls. suPAR, CRP, and fibrinogen levels were measured on the first day of hospitalization and on the seventh day of treatment. Results: We found that fibrinogen (P<0.001, CRP (P<0.001, and suPAR (P<0.001 were significantly higher in patients with AE-COPD than in healthy controls. Fibrinogen (P<0.001, CRP (P=0.001, and suPAR (P<0.001 were significantly decreased by the seventh day of treatment. However, the area under receiver operator characteristic curve showed that suPAR is superior to CRP and fibrinogen in distinguishing AE-COPD. There was a correlation between fibrinogen, CRP, and suPAR. However, only fibrinogen was a powerful predictor of suPAR in multiple linear regression. In multiple logistic regression, only suPAR and fibrinogen were strong predictors of AE-COPD (P=0.002 and P=0.014, respectively. Serum suPAR was negatively correlated with forced expiratory volume in 1

  11. Adipocyte insulin receptor activity maintains adipose tissue mass and lifespan.

    Friesen, Max; Hudak, Carolyn S; Warren, Curtis R; Xia, Fang; Cowan, Chad A

    2016-08-01

    Type 2 diabetes follows a well-defined progressive pathogenesis, beginning with insulin resistance in metabolic tissues such as the adipose. Intracellular signaling downstream of insulin receptor activation regulates critical metabolic functions of adipose tissue, including glucose uptake, lipogenesis, lipolysis and adipokine secretion. Previous studies have used the aP2 promoter to drive Cre recombinase expression in adipose tissue. Insulin receptor (IR) knockout mice created using this aP2-Cre strategy (FIRKO mice) were protected from obesity and glucose intolerance. Later studies demonstrated the promiscuity of the aP2 promoter, casting doubts upon the tissue specificity of aP2-Cre models. It is our goal to use the increased precision of the Adipoq promoter to investigate adipocyte-specific IR function. Towards this end we generated an adipocyte-specific IR knockout (AIRKO) mouse using an Adipoq-driven Cre recombinase. Here we report AIRKO mice are less insulin sensitive throughout life, and less glucose tolerant than wild-type (WT) littermates at the age of 16 weeks. In contrast to WT littermates, the insulin sensitivity of AIRKO mice is unaffected by age or dietary regimen. At any age, AIRKO mice are comparably insulin resistant to old or obese WT mice and have a significantly reduced lifespan. Similar results were obtained when these phenotypes were re-examined in FIRKO mice. We also found that the AIRKO mouse is protected from high-fat diet-induced weight gain, corresponding with a 90% reduction in tissue weight of major adipose depots compared to WT littermates. Adipose tissue mass reduction is accompanied by hepatomegaly and increased hepatic steatosis. These data indicate that adipocyte IR function is crucial to systemic energy metabolism and has profound effects on adiposity, hepatic homeostasis and lifespan. PMID:27246738

  12. Ouabain exacerbates activation-induced cell death in human peripheral blood lymphocytes

    Mabel B. Esteves

    2005-06-01

    Full Text Available Lymphocytes activated by mitogenic lectins display changes in transmembrane potential, an elevation in the cytoplasmic Ca2+ concentrations, proliferation and/or activation induced cell death. Low concentrations of ouabain (an inhibitor of Na+,K+-ATPase suppress mitogen-induced proliferation and increases cell death. To understand the mechanisms involved, a number of parameters were analyzed using fluorescent probes and flow cytometry. The addition of 100nM ouabain to cultures of peripheral blood lymphocytes activated with 5µg/ml phytohemagglutinin (PHA did not modify the increased expression of the Fas receptor or its ligand FasL induced by the mitogen. However, treatment with ouabain potentiated apoptosis induced by an anti-Fas agonist antibody. A synergy between ouabain and PHA was also observed with regard to plasma membrane depolarization. PHA per se did not induce dissipation of mitochondrial membrane potential but when cells were also exposed to ouabain a marked depolarization could be observed, and this was a late event. It is possible that the inhibitory effect of ouabain on activated peripheral blood lymphocytes involves the potentiation of some of the steps of the apoptotic process and reflects an exacerbation of the mechanism of activation-induced cell death.Quando linfócitos são ativados por lectinas mitogênicas apresentam mudanças do potencial de membrana, elevação das concentrações citoplasmáticas de cálcio, proliferação e/ou morte celular induzida por ativação (AICD. Concentrações baixas de ouabaína (um inibidor da Na,K-ATPase suprimem a proliferação induzida por mitógenos e aumentam a morte celular. Para entender os mecanismos envolvidos, uma série de parâmetros foram avaliados usando sondas fluorescentes e citometria de fluxo. A adição de 100nM de ouabaína para culturas de linfócitos de sangue periférico ativadas por fitohemaglutinina (PHA não modificou o aumento de expressão do receptor Fas ou de

  13. Allergic Conjunctivitis Exacerbates Corneal Allograft Rejection by Activating Th1 and Th2 Alloimmune Responses

    Niederkorn, Jerry Y.; Chen, Peter W.; Mellon, Jessamee; Stevens, Christina; Mayhew, Elizabeth

    2010-01-01

    Allergic conjunctivitis (AC) and airway hyperreactivity exacerbate corneal allograft rejection. Because AC and airway hyperreactivity are allergic diseases of mucosal tissues, we determined whether an allergic disease of a nonmucosal tissue would affect corneal allograft rejection and whether Th2 cells alone accounted for accelerated graft rejection in allergic mice. Hosts sensitized cutaneously with short ragweed pollen developed cutaneous immediate hypersensitivity but rejected corneal allo...

  14. A novel hydroxyfuroic acid compound as an insulin receptor activator – structure and activity relationship of a prenylindole moiety to insulin receptor activation

    Tsai Henry J

    2009-07-01

    Full Text Available Abstract Background Diabetes Mellitus is a chronic disease and many patients of which require frequent subcutaneous insulin injection to maintain proper blood glucose levels. Due to the inconvenience of insulin administration, an orally active insulin replacement has long been a prime target for many pharmaceutical companies. Demethylasterriquinone (DMAQ B1, extracted from tropical fungus, Pseudomassaria sp., has been reported to be an orally effective agent at lowering circulating glucose levels in diabetic (db/db mice; however, the cytotoxicity associated with the quinone moiety has not been addressed thus far. Methods A series of hydroxyfuroic acid compounds were synthesized and tested for their efficacies at activating human insulin receptor. Cytotoxicity to Chinese hamster ovary cells, selectivities over insulin-like growth factor-1 (IGF-1, epidermal growth factor (EGF, and fibroblast growth factor (FGF receptors were examined in this study. Result and Conclusion This study reports a new non-quinone DMAQ B1 derivative, a hydroxyfuroic acid compound (D-410639, which is 128 fold less cytotoxic as DMAQ B1 and as potent as compound 2, a DMAQ B1 synthetic derivative from Merck, at activating human insulin receptor. D-410639 has little activation potential on IGF-1 receptor but is a moderate inhibitor to EGF receptor. Structure and activity relationship of the prenylindole moiety to insulin receptor activation is discussed.

  15. Insulin stimulates choline acetyltransferase activity in cultured embryonic chicken retina neurons

    The effect of insulin on the appearance of the enzyme choline acetyltransferase in embryonic chicken retina neurons cultured in defined medium was studied. In the presence of a minimal level of insulin (1 ng/ml), ChoAcT activity increased with time in culture. A correspondence between the insulin concentration in the defined medium (1-100 ng/ml) and both the rate of increase and maximum attained level of ChoAcT activity was observed. Maximal ChoAcT activity was 2- to 3-fold greater in cells cultured in the presence of 100 ng of insulin per ml than in cells cultured in the presence of 1 ng of insulin per ml. To elicit maximum ChoAcT activity, insulin at 100 ng/ml was required in the medium for only the first 4 days of the culture period, at which time insulin could be reduced to maintenance levels (10 ng/ml) without affecting ChoAcT activity. Insulin binding assays performed during a 7-day culture period revealed that irrespective of the 125I-insulin concentration in the medium during culture, cell-surface insulin receptors decreased by ≅ 90% between 4 and 7 days in culture. This decrease in insulin binding corresponded to the observed decrease in the sensitivity of ChoAcT activity to insulin. The findings suggest that insulin plays a role in mediating cholinergic differentiation in the embryonic chicken retina

  16. Measuring phospholipase D activity in insulin-secreting pancreatic beta-cells and insulin-responsive muscle cells and adipocytes.

    Cazzolli, Rosanna; Huang, Ping; Teng, Shuzhi; Hughes, William E

    2009-01-01

    Phospholipase D (PLD) is an enzyme producing phosphatidic acid and choline through hydrolysis of phosphatidylcholine. The enzyme has been identified as a member of a variety of signal transduction cascades and as a key regulator of numerous intracellular vesicle trafficking processes. A role for PLD in regulating glucose homeostasis is emerging as the enzyme has recently been identified in events regulating exocytosis of insulin from pancreatic beta-cells and also in insulin-stimulated glucose uptake through controlling GLUT4 vesicle exocytosis in muscle and adipose tissue. We present methodologies for assessing cellular PLD activity in secretagogue-stimulated insulin-secreting pancreatic beta-cells and also insulin-stimulated adipocyte and muscle cells, two of the principal insulin-responsive cell types controlling blood glucose levels. PMID:19160674

  17. Orally active insulin mimics: where do we stand now?

    M Balasubramanyam; V Mohan

    2001-09-01

    The war against diabetes through the development of new drugs is an ongoing continuous process to counter the alarming global increase in the prevalence of diabetes and its complications, particularly in developing countries like India. Unfortunately, the speed with which our knowledge of diabetes and its effects is expanding is not matched by the availability of new drugs. Following the identification of the insulin receptor (IR), its intrinsic kinase activity and molecular cloning, many studies have looked at IR as an ideal drug target. This review summarizes in brief the latest advancements in this field with particular reference to the current situation in respect of the development of orally active insulin mimetics in the treatment of type 2 diabetes.

  18. Disruption of Inducible 6-Phosphofructo-2-kinase Ameliorates Diet-induced Adiposity but Exacerbates Systemic Insulin Resistance and Adipose Tissue Inflammatory Response*

    Huo, Yuqing; Guo, Xin; Li, Honggui; Wang, Huan; Zhang, Weiyu; Wang, Ying; Zhou, Huaijun; Gao, Zhanguo; Telang, Sucheta; Chesney, Jason; Chen, Y. Eugene; Ye, Jianping; Chapkin, Robert S.; Wu, Chaodong

    2009-01-01

    Adiposity is commonly associated with adipose tissue dysfunction and many overnutrition-related metabolic diseases including type 2 diabetes. Much attention has been paid to reducing adiposity as a way to improve adipose tissue function and systemic insulin sensitivity. PFKFB3/iPFK2 is a master regulator of adipocyte nutrient metabolism. Using PFKFB3+/− mice, the present study investigated the role of PFKFB3/iPFK2 in regulating diet-induced adiposity and systemic insulin resistance. On a high...

  19. The insulin receptor activation process involves localized conformational changes.

    Baron, V; Kaliman, P; Gautier, N; Van Obberghen, E

    1992-11-15

    The molecular process by which insulin binding to the receptor alpha-subunit induces activation of the receptor beta-subunit with ensuing substrate phosphorylation remains unclear. In this study, we aimed at approaching this molecular mechanism of signal transduction and at delineating the cytoplasmic domains implied in this process. To do this, we used antipeptide antibodies to the following sequences of the receptor beta-subunit: (i) positions 962-972 in the juxtamembrane domain, (ii) positions 1247-1261 at the end of the kinase domain, and (iii) positions 1294-1317 and (iv) positions 1309-1326, both in the receptor C terminus. We have previously shown that insulin binding to its receptor induces a conformational change in the beta-subunit C terminus. Here, we demonstrate that receptor autophosphorylation induces an additional conformational change. This process appears to be distinct from the one produced by ligand binding and can be detected in at least three different beta-subunit regions: the juxtamembrane domain, the kinase domain, and the C terminus. Hence, the cytoplasmic part of the receptor beta-subunit appears to undergo an extended conformational change upon autophosphorylation. By contrast, the insulin-induced change does not affect the juxtamembrane domain 962-972 nor the kinase domain 1247-1261 and may be limited to the receptor C terminus. Further, we show that the hormone-dependent conformational change is maintained in a kinase-deficient receptor due to a mutation at lysine 1018. Therefore, during receptor activation, the ligand-induced change could precede ATP binding and receptor autophosphorylation. We propose that insulin binding leads to a transient receptor form that may allow ATP binding and, subsequently, autophosphorylation. The second conformational change could unmask substrate-binding sites and stabilize the receptor in an active conformation. PMID:1331080

  20. Insulin regulation of Na/K pump activity in rat hepatoma cells

    Insulin rapidly increases Na/K pump activity in HTC rat hepatoma cells in tissue culture, as measured by the ouabain-sensitive influx of the potassium analogue 86Rb+. Increased influx is observed within minutes and is maximal (70% above control) within 1-2 h. The effect appears to be mediated by the insulin receptors, as: the concentration dependence on insulin is identical to that for insulin induction of tyrosine aminotransferase and stimulation of 2-aminoisobutyric acid transport, proinsulin is 6% as potent as insulin, and the effect is blocked by anti-receptor antibodies. The early stimulation of potassium influx is not blocked by cycloheximide and is not associated with an increased number of pump sites as measured by 3H-ouabain binding. The insulin effect is blocked by amiloride, which blocks sodium influx, and is mimicked by the sodium ionophore monensin, which increases sodium influx and intracellular accumulation. Insulin also rapidly increases the initial rate of 22Na+ influx, suggesting that insulin may enhance Na/K pump activity, in part, by increasing intracellular sodium concentration. Incubation of HTC cells with insulin for 24 h causes complete unresponsiveness to the insulin induction of transaminase and stimulation of amino acid transport, a phenomenon mediated by postbinding mechanisms. In contrast, similar incubation with insulin does not cause unresponsiveness to the insulin stimulation of Na/K pump activity. Therefore, the site of regulation of responsiveness to insulin must be distal to, or separate from, those events causing stimulation of ion fluxes

  1. Insulin regulation of Na/K pump activity in rat hepatoma cells

    Gelehrter, T.D.; Shreve, P.D.; Dilworth, V.M.

    1984-05-01

    Insulin rapidly increases Na/K pump activity in HTC rat hepatoma cells in tissue culture, as measured by the ouabain-sensitive influx of the potassium analogue 86Rb+. Increased influx is observed within minutes and is maximal (70% above control) within 1-2 h. The effect appears to be mediated by the insulin receptors, as: the concentration dependence on insulin is identical to that for insulin induction of tyrosine aminotransferase and stimulation of 2-aminoisobutyric acid transport, proinsulin is 6% as potent as insulin, and the effect is blocked by anti-receptor antibodies. The early stimulation of potassium influx is not blocked by cycloheximide and is not associated with an increased number of pump sites as measured by /sup 3/H-ouabain binding. The insulin effect is blocked by amiloride, which blocks sodium influx, and is mimicked by the sodium ionophore monensin, which increases sodium influx and intracellular accumulation. Insulin also rapidly increases the initial rate of /sup 22/Na+ influx, suggesting that insulin may enhance Na/K pump activity, in part, by increasing intracellular sodium concentration. Incubation of HTC cells with insulin for 24 h causes complete unresponsiveness to the insulin induction of transaminase and stimulation of amino acid transport, a phenomenon mediated by postbinding mechanisms. In contrast, similar incubation with insulin does not cause unresponsiveness to the insulin stimulation of Na/K pump activity. Therefore, the site of regulation of responsiveness to insulin must be distal to, or separate from, those events causing stimulation of ion fluxes.

  2. Structure, Aggregation, and Activity of a Covalent Insulin Dimer Formed During Storage of Neutral Formulation of Human Insulin

    Hjorth, Christian Fogt; Norrman, Mathias; Wahlund, Per-Olof; Benie, Andrew J.; Petersen, Bent O.; Jessen, Christian M; Pedersen, Thomas Å.; Vestergaard, Kirsten; Steensgaard, Dorte B; Pedersen, Jan Skov; Naver, Helle; Hubálek, František; Poulsen, Christian; Otzen, Daniel

    2016-01-01

    first detailed characterization of a specific type of human insulin HMWP formed during storage of a marketed pharmaceutical formulation. These results indicate that this specific type of HMWP is unlikely to antagonize the physical stability of the formulation, as HMWP retained a tertiary structure......A specific covalently linked dimeric species of insulin high molecular weight products (HMWPs), formed during prolonged incubation of a neutral pharmaceutical formulation of human insulin, were characterized in terms of tertiary structure, self-association, biological activity, and fibrillation...

  3. Monoclonal antibodies to the human insulin receptor that activate glucose transport but not insulin receptor kinase activity.

    Forsayeth, J R; Caro, J F; Sinha, M K; Maddux, B A; Goldfine, I D

    1987-01-01

    Three mouse monoclonal antibodies were produced that reacted with the alpha subunit of the human insulin receptor. All three both immunoprecipitated 125I-labeled insulin receptors from IM-9 lymphocytes and competitively inhibited 125I-labeled insulin binding to its receptor. Unlike insulin, the antibodies failed to stimulate receptor autophosphorylation in both intact IM-9 lymphocytes and purified human placental insulin receptors. Moreover, unlike insulin, the antibodies failed to stimulate ...

  4. Insulin and insulin-like growth factor I exert different effects on plasminogen activator production or cell growth in the ovine thyroid cell line OVNIS.

    Degryse, B; Maisonobe, F; Hovsépian, S; Fayet, G

    1991-11-01

    Insulin and Insulin-like Growth Factor I (IGF-I) are evaluated for their capacity to affect cell proliferation and plasminogen activator (PA) activity production in an ovine thyroid cell line OVNIS. Insulin at physiological and supraphysiological doses induces cell proliferation and increases PA activity. IGF-I, which is also clearly mitogenic for these cells, surprisingly does not modulate PA activity. The results indicate that the growth promoting effect is mediated through the insulin and IGF-I receptors whereas PA activity is solely regulated via the insulin receptors. PMID:1802921

  5. Insulin receptor substrates 1 and 2 but not Shc can activate the insulin receptor independent of insulin and induce proliferation in CHO-IR cells

    Ligand-activated insulin receptor (IR) attracts and phosphorylates various substrates such as insulin receptor substrates 1-4 (IRS) and Shc. To investigate how binding affinity for substrate affects signalling we generated chimeric receptors with the β-chain of the insulin receptor containing NPXY motives with different affinities for receptor substrates. We found that the extent of receptor tyrosine phosphorylation positively correlates with binding affinity towards IRS1/2 but not towards Shc. Moreover, overexpression of IRS1 or IRS2 but not of Shc increased IR tyrosine phosphorylation in a dose-dependent manner, also independent of insulin. Molecular truncations of IRS1 revealed that neither the isolated PH and PTB domains nor the C-terminus with the tyrosine phosphorylation sites alone are sufficient for substrate-dependent receptor activation. Overexpression of IRS1 and IRS2 impaired insulin-induced internalization of the IR in a dose-dependent manner suggesting that IRS proteins prevent endosome-associated receptor dephosphorylation/inactivation. IRS1 and IRS2 could therefore target the activated IR to different cellular compartments. Overexpression of IRS1 and IRS2 inhibited insulin-stimulated activation of the MAP kinases Erk1/2 while it increased/induced activation of Akt/PKB. Finally, overexpression of IRS1 and IRS2 but not of Shc induced DNA synthesis in starved CHO-IR cells independent of exogenous growth factors. Our results demonstrate that variations in cellular IRS1 and IRS2 concentration affect insulin signalling both upstream and downstream and that IRS proteins could play instructive rather than just permissive roles in signal transmission

  6. Treatment with the 3-Ketoacyl-CoA Thiolase Inhibitor Trimetazidine Does Not Exacerbate Whole-Body Insulin Resistance in Obese Mice

    Ussher, John R.; Keung, Wendy; Fillmore, Natasha; Koves, Timothy R.; Mori, Jun; Zhang, Liyan; Lopaschuk, David G.; Ilkayeva, Olga R.; Wagg, Cory S.; Jaswal, Jagdip S.; Muoio, Deborah M.; Lopaschuk, Gary D.

    2014-01-01

    There is a growing need to understand the underlying mechanisms involved in the progression of cardiovascular disease during obesity and diabetes. Although inhibition of fatty acid oxidation has been proposed as a novel approach to treat ischemic heart disease and heart failure, reduced muscle fatty acid oxidation rates may contribute to the development of obesity-associated insulin resistance. Our aim was to determine whether treatment with the antianginal agent trimetazidine, which inhibits...

  7. Insulin receptor activation in the nucleus accumbens reflects nutritive value of a recently ingested meal.

    Woods, C A; Guttman, Z R; Huang, D; Kolaric, R A; Rabinowitsch, A I; Jones, K T; Cabeza de Vaca, S; Sclafani, A; Carr, K D

    2016-05-15

    With respect to feeding, insulin is typically thought of as a satiety hormone, acting in the hypothalamus to limit ingestive behavior. However, accumulating evidence suggests that insulin also has the ability to alter dopamine release in the striatum and influence food preferences. With increased access to high calorie foods, Western societies have a high prevalence of obesity, accompanied by insulin insensitivity. Little is known about how insulin is trafficked into the brain following food consumption and whether insulin insensitivity in the periphery is mirrored in the central nervous system. We investigated insulin receptor activation in the ventral striatum of rats receiving water or 16% glucose either orally or intragastrically. We also investigated whether glucose-induced insulin receptor activation was altered in food-restricted (FR) or diet-induced obesity (OB) rat models. Lastly, we examined whether insulin plays a significant role in flavor-nutrient preference learning. Glucose intake stimulated a rapid increase in insulin receptor activity in the ventral striatum of FR and ad libitum (AL) fed rats, but not OB rats. Similarly, both AL and FR, but not OB rats demonstrated significant flavor-nutrient preferences. However AL rats receiving brief inhibition of insulin activity during conditioning failed to acquire a significant flavor-nutrient preference. These findings suggest that impaired insulin receptor activation in the ventral striatum may result in inaccurate valuation of nutritive foods, which could lead to overconsumption of food or the selection of foods that don't accurately meet the body's current physiological needs. PMID:26988281

  8. Activation of the insulin receptor (IR) by insulin and a synthetic peptide has different effects on gene expression in IR-transfected L6 myoblasts

    Jensen, M.; Palsgaard, J.; Borup, R.;

    2008-01-01

    Single-chain peptides have been recently produced that display either mimetic or antagonistic properties against the insulin and IGF-1 (insulin-like growth factor 1) receptors. We have shown previously that the insulin mimetic peptide S597 leads to significant differences in receptor activation and...

  9. DAMPs-activated neutrophil extracellular trap exacerbates sterile inflammatory liver injury

    Huang, Hai; Tohme, Samer; Al-Khafaji, Ahmed B; Tai, Sheng; Loughran, Patricia; Chen, Li; Wang, Shu; Kim, Jiyun; Billiar, Timothy; Wang, Yanming; Tsung, Allan

    2015-01-01

    Innate immunity plays a crucial role in the response to sterile inflammation such as liver ischemia/reperfusion (I/R) injury. The initiation of liver I/R injury results in the release of damage associated molecular patterns (DAMPs), which trigger innate immune and inflammatory cascade via pattern recognition receptors. Neutrophils are recruited to the liver after I/R and contribute to the organ damage, innate immune and inflammatory responses. Formation of neutrophil extracellular trap (NET) has been recently found in response to various stimuli. However, the role of NETs during liver I/R injury remains unknown. We show that NETs form in the sinusoids of ischemic liver lobes in vivo. This was associated with increased NET markers, serum level of myeloperoxidase (MPO)-DNA complexes and tissue level of citrullinated-histone H3 compared to control mice. Treatment with peptidyl-arginine-deiminase (PAD) 4 inhibitor or DNase I significantly protected hepatocytes and reduced inflammation after liver I/R as evidenced by inhibition of NET formation, indicating the pathophysiological role of NETs in liver I/R injury. In vitro, NETs increase hepatocyte death and induce Kupffer cells to release proinflammatory cytokines. DAMPs, such as HMGB1 and histones, released by injured hepatocytes stimulate NET formation through Toll-like receptor (TLR4)- and TLR9-MyD88 signaling pathways. After neutrophil depletion in mice, the adoptive transfer of TLR4 knockout (KO) or TLR9 KO neutrophils confers significant protection from liver I/R injury with significant decrease in NET formation. In addition, we found inhibition of NET formation by PAD4 inhibitor or DNase I reduces HMGB1 and histone-mediated liver I/R injury. Conclusion DAMPs released during liver I/R promotes NET formation through TLRs signaling pathway. Development of NETs subsequently exacerbates organ damage and initiates inflammatory responses during liver I/R. PMID:25855125

  10. Replacement of lysine residue 1030 in the putative ATP-binding region of the insulin receptor abolishes insulin- and antibody-stimulated glucose uptake and receptor kinase activity

    To test whether the tyrosine kinase activity of the insulin receptor is crucial for insulin action, the authors have constructed mutations of the human insulin receptor at Lys-1030, which is in the presumed ATP-binding region. By using oligonucleotide-directed mutagenesis, this lysine residue was replaced with either methionine, arginine, or alanine. Chinese hamster ovary cells were transfected by mutant cDNAs and the expressed insulin receptors were characterized. They show here that none of these mutants exhibited insulin-activated autophosphorylation and kinase activity in vitro. They also do not mediate insulin- and antibody-stimulated uptake of 2-deoxyglucose. The tyrosine kinase activity is thus required for a key physiological response of insulin

  11. A two-week reduction of ambulatory activity attenuates peripheral insulin sensitivity

    Krogh-Madsen, Rikke; Thyfault, John P; Broholm, Christa;

    2009-01-01

    activity would influence peripheral insulin sensitivity. We aimed to explore if healthy, non-exercising subjects who went from a normal to a low level of ambulatory activity for two weeks would display metabolic alterations including reduced peripheral insulin sensitivity. -To do this, ten healthy young...... number of daily steps induced a significant reduction of 17% in the glucose infusion rate (GIR) during the clamp. This reduction was due to a decline in peripheral insulin sensitivity with no effect on hepatic endogenous glucose production. The insulin-stimulated ratio of pAkt(thr308)/total Akt decreased...... possible biological cause for the public health problem of type 2 diabetes has been identified. Reduced ambulatory activity for two weeks in healthy, non-exercising young men significantly reduced peripheral insulin sensitivity, cardiovascular fitness, and lean leg mass. Key words: Inactivity, Insulin...

  12. Association of disease activity with acute exacerbation of interstitial lung disease during tocilizumab treatment in patients with rheumatoid arthritis: a retrospective, case-control study.

    Akiyama, Mitsuhiro; Kaneko, Yuko; Yamaoka, Kunihiro; Kondo, Harumi; Takeuchi, Tsutomu

    2016-06-01

    The objective of the study was to identify risk factors for acute exacerbation of interstitial lung disease (ILD) during tocilizumab treatment in patients with rheumatoid arthritis (RA). This is a retrospective, case-control study. We reviewed 395 consecutive RA patients who received tocilizumab. First, we divided the patients according to the presence (RA-ILD) or absence of ILD (non-ILD) assessed by chest X-ray or high-resolution computed tomography, and compared them for characteristics relevant to RA-ILD. Subsequently, focusing on the patients with RA-ILD, we assessed their baseline characteristics and clinical courses comparing patients with acute exacerbation to those without. Comparing 78 with ILD and 317 without ILD, the following were identified as factors related to RA-ILD on multivariate analysis: age 60 years or older (OR 4.5, 95 % CI 2.2-9.4, P smoking habit (OR 2.9, 95 % CI 1.5-5.5, P = 0.002), and high rheumatoid factor levels (OR 2.8, 95 % CI 1.4-5.5, P = 0.002). Of 78 RA-ILD patients, six developed acute exacerbation during tocilizumab treatment. The median duration between the initiation of tocilizumab treatment and the acute exacerbation occurrence was 48 weeks. While baseline characteristics did not differ between acute exacerbation and non-acute exacerbation groups, patients experiencing acute exacerbation had significantly higher Clinical Disease Activity Index (CDAI) at 24 weeks (20.8 vs. 6.2, P = 0.019). Univariate analysis showed that CDAI > 10 at 24 weeks was a risk factor for acute exacerbation (OR 4.7, 95 % CI 2.1-10.4, P = 0.02). Uncontrolled arthritis activity during tocilizumab treatment may be associated with acute exacerbation of RA-ILD, suggesting post-treatment monitoring of disease activity is important not only with respect to RA itself but also for RA-ILD. PMID:27072347

  13. Intraoral film containing insulin-phospholipid microemulsion: formulation and in vivo hypoglycemic activity study.

    Rachmawati, Heni; Haryadi, Bernard Manuel; Anggadiredja, Kusnandar; Suendo, Veinardi

    2015-06-01

    Non-invasive administration of insulin is expected for better diabetes mellitus therapy. In this report, we developed intraoral preparation for insulin. Insulin was encapsulated into nanocarrier using self-assembly emulsification process. To increase lipophilicity of insulin, it was dispersed in phospholipid resulted in insulin-phospholipid solid dispersion. The microemulsion formula was established from our previous work which contained glyceryl monooleate (GMO), Tween 20, and polyethylene glycol (PEG 400) in a ratio of 1:8:1. To confirm the formation of insulin-phospholipid solid dispersion, PXRD, FTIR spectroscopy, and Raman spectroscopy were performed. Then, the microemulsion was evaluated for droplet size and distribution, zeta potential, entrapment efficiency, physical stability, and Raman spectroscopy. In addition, microemulsion with expected characteristic was evaluated for in vitro release, in vitro permeation, and in vivo activity. The droplets size of ∼100 nm with narrow distribution and positive charge of +0.56 mV were formed. The insulin encapsulated in the oil droplet was accounted of >90%. Water-soluble chitosan seems to be a promising film matrix polymer which also functioned as insulin release controller. Oral administration of insulin microemulsion to healthy Swiss-Webster mice showed hypoglycemic effect indicating the success of this protein against a harsh environment of the gastrointestinal tract. This effectiveness significantly increased by fourfold as compared to free insulin. Taken together, microemulsion seems to be a promising carrier for oral delivery of insulin. PMID:25511810

  14. Structure, Aggregation, and Activity of a Covalent Insulin Dimer Formed During Storage of Neutral Formulation of Human Insulin.

    Hjorth, Christian Fogt; Norrman, Mathias; Wahlund, Per-Olof; Benie, Andrew J; Petersen, Bent O; Jessen, Christian M; Pedersen, Thomas Å; Vestergaard, Kirsten; Steensgaard, Dorte B; Pedersen, Jan Skov; Naver, Helle; Hubálek, František; Poulsen, Christian; Otzen, Daniel

    2016-04-01

    A specific covalently linked dimeric species of insulin high molecular weight products (HMWPs), formed during prolonged incubation of a neutral pharmaceutical formulation of human insulin, were characterized in terms of tertiary structure, self-association, biological activity, and fibrillation properties. The dimer was formed by a covalent link between A21Asn and B29Lys. It was analyzed using static and dynamic light scattering and small-angle X-ray scattering to evaluate its self-association behavior. The tertiary structure was obtained using nuclear magnetic resonance and X-ray crystallography. The biological activity of HMWP was determined using 2 in vitro assays, and its influence on fibrillation was investigated using Thioflavin T assays. The dimer's tertiary structure was nearly identical to that of the noncovalent insulin dimer, and it was able to form hexamers in the presence of zinc. The dimer exhibited reduced propensity for self-association in the absence of zinc but significantly postponed the onset of fibrillation in insulin formulations. Consistent with its dimeric state, the tested species of HMWP showed little to no biological activity in the used assays. This study is the first detailed characterization of a specific type of human insulin HMWP formed during storage of a marketed pharmaceutical formulation. These results indicate that this specific type of HMWP is unlikely to antagonize the physical stability of the formulation, as HMWP retained a tertiary structure similar to the noncovalent dimer and participated in hexamer assembly in the presence of zinc. In addition, increasing amounts of HMWP reduce the rate of insulin fibrillation. PMID:26921119

  15. Dark chocolate exacerbates acne.

    Vongraviopap, Saivaree; Asawanonda, Pravit

    2016-05-01

    The effects of chocolate on acne exacerbations have recently been reevaluated. For so many years, it was thought that it had no role in worsening acne. To investigate whether 99% dark chocolate, when consumed in regular daily amounts, would cause acne to worsen in acne-prone male subjects, twenty-five acne prone male subjects were asked to consume 25 g of 99% dark chocolate daily for 4 weeks. Assessments which included Leeds revised acne scores as well as lesion counts took place weekly. Food frequency questionnaire was used, and daily activities were recorded. Statistically significant changes of acne scores and numbers of comedones and inflammatory papules were detected as early as 2 weeks into the study. At 4 weeks, the changes remained statistically significant compared to baseline. Dark chocolate when consumed in normal amounts for 4 weeks can exacerbate acne in male subjects with acne-prone skin. PMID:26711092

  16. Growth hormone-induced insulin resistance in human subjects involves reduced pyruvate dehydrogenase activity

    Nellemann, Birgitte; Vendelbo, Mikkel H; Nielsen, Thomas S;

    2014-01-01

    Insulin resistance induced by growth hormone (GH) is linked to promotion of lipolysis by unknown mechanisms. We hypothesized that suppression of the activity of pyruvate dehydrogenase in the active form (PDHa) underlies GH-induced insulin resistance similar to what is observed during fasting....

  17. Bcl10 links saturated fat overnutrition with hepatocellular NF-kB activation and insulin resistance

    Beek, M.H. van; Oravecz-Wilson, K.I.; Delekta, P.C.; Gu, S.; Li, X.; Jin, X.; Apel, I.J.; Konkle, K.S.; Feng, Y.; Teitelbaum, D.H.; Ruland, J.; McAllister-Lucas, L.M.; Lucas, P.C.

    2012-01-01

    Excess serum free fatty acids (FFAs) are fundamental to the pathogenesis of insulin resistance. With high-fat feeding, FFAs activate NF-kB in target tissues, initiating negative crosstalk with insulin signaling. However, the mechanisms underlying FFA-dependent NF-kB activation remain unclear. Here,

  18. Minocycline Transiently Reduces Microglia/Macrophage Activation but Exacerbates Cognitive Deficits Following Repetitive Traumatic Brain Injury in the Neonatal Rat.

    Hanlon, Lauren A; Huh, Jimmy W; Raghupathi, Ramesh

    2016-03-01

    Elevated microglial/macrophage-associated biomarkers in the cerebrospinal fluid of infant victims of abusive head trauma (AHT) suggest that these cells play a role in the pathophysiology of the injury. In a model of AHT in 11-day-old rats, 3 impacts (24 hours apart) resulted in spatial learning and memory deficits and increased brain microglial/macrophage reactivity, traumatic axonal injury, neuronal degeneration, and cortical and white-matter atrophy. The antibiotic minocycline has been effective in decreasing injury-induced microglial/macrophage activation while simultaneously attenuating cellular and functional deficits in models of neonatal hypoxic ischemia, but the potential for this compound to rescue deficits after impact-based trauma to the immature brain remains unexplored. Acute minocycline administration in this model of AHT decreased microglial/macrophage reactivity in the corpus callosum of brain-injured animals at 3 days postinjury, but this effect was lost by 7 days postinjury. Additionally, minocycline treatment had no effect on traumatic axonal injury, neurodegeneration, tissue atrophy, or spatial learning deficits. Interestingly, minocycline-treated animals demonstrated exacerbated injury-induced spatial memory deficits. These results contrast with previous findings in other models of brain injury and suggest that minocycline is ineffective in reducing microglial/macrophage activation and ameliorating injury-induced deficits following repetitive neonatal traumatic brain injury. PMID:26825312

  19. Targeted activation of endothelin-1 exacerbates hypoxia-induced pulmonary hypertension

    Pulmonary arterial hypertension (PAH) is a fatal disease that eventually results in right heart failure and death. Current pharmacologic therapies for PAH are limited, and there are no drugs that could completely cure PAH. Enhanced activity of endothelin system has been implicated in PAH severity and endothelin receptor antagonists have been used clinically to treat PAH. However, there is limited experimental evidence on the direct role of enhanced endothelin system activity in PAH. Here, we investigated the correlation between endothelin-1 (ET-1) and PAH using ET-1 transgenic (ETTG) mice. Exposure to chronic hypoxia increased right ventricular pressure and pulmonary arterial wall thickness in ETTG mice compared to those in wild type mice. Of note, ETTG mice exhibited modest but significant increase in right ventricular pressure and vessel wall thickness relative to wild type mice even under normoxic conditions. To induce severe PAH, we administered SU5416, a vascular endothelial growth factor receptor inhibitor, combined with exposure to chronic hypoxia. Treatment with SU5416 modestly aggravated hypoxia-induced pulmonary hypertension, right ventricular hypertrophy, and pulmonary arterial vessel wall thickening in ETTG mice in association with increased interleukin-6 expression in blood vessels. However, there was no sign of obliterative endothelial cell proliferation and plexiform lesion formation in the lungs. These results demonstrated that enhanced endothelin system activity could be a causative factor in the development of PAH and provided rationale for the inhibition of endothelin system to treat PAH. - Highlights: • Role of endothelin-1 in pulmonary arterial hypertension (PAH) was investigated. • The endothelin-1 transgenic (ETTG) and wild type (WT) mice were analyzed. • ETTG mice spontaneously developed PAH under normoxia conditions. • SU5416 further aggravated PAH in ETTG mice. • Enhanced endothelin system activity could be a causative factor in

  20. Targeted activation of endothelin-1 exacerbates hypoxia-induced pulmonary hypertension

    Satwiko, Muhammad Gahan [Division of Cardiovascular Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe (Japan); Ikeda, Koji [Department of Clinical Pharmacy, Kobe Pharmaceutical University, Kobe (Japan); Nakayama, Kazuhiko [Division of Cardiovascular Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe (Japan); Yagi, Keiko [Department of Clinical Pharmacy, Kobe Pharmaceutical University, Kobe (Japan); Hocher, Berthold [Institute for Nutritional Science, University of Potsdam, Potsdam (Germany); Hirata, Ken-ichi [Division of Cardiovascular Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe (Japan); Emoto, Noriaki, E-mail: emoto@med.kobe-u.ac.jp [Division of Cardiovascular Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe (Japan); Department of Clinical Pharmacy, Kobe Pharmaceutical University, Kobe (Japan)

    2015-09-25

    Pulmonary arterial hypertension (PAH) is a fatal disease that eventually results in right heart failure and death. Current pharmacologic therapies for PAH are limited, and there are no drugs that could completely cure PAH. Enhanced activity of endothelin system has been implicated in PAH severity and endothelin receptor antagonists have been used clinically to treat PAH. However, there is limited experimental evidence on the direct role of enhanced endothelin system activity in PAH. Here, we investigated the correlation between endothelin-1 (ET-1) and PAH using ET-1 transgenic (ETTG) mice. Exposure to chronic hypoxia increased right ventricular pressure and pulmonary arterial wall thickness in ETTG mice compared to those in wild type mice. Of note, ETTG mice exhibited modest but significant increase in right ventricular pressure and vessel wall thickness relative to wild type mice even under normoxic conditions. To induce severe PAH, we administered SU5416, a vascular endothelial growth factor receptor inhibitor, combined with exposure to chronic hypoxia. Treatment with SU5416 modestly aggravated hypoxia-induced pulmonary hypertension, right ventricular hypertrophy, and pulmonary arterial vessel wall thickening in ETTG mice in association with increased interleukin-6 expression in blood vessels. However, there was no sign of obliterative endothelial cell proliferation and plexiform lesion formation in the lungs. These results demonstrated that enhanced endothelin system activity could be a causative factor in the development of PAH and provided rationale for the inhibition of endothelin system to treat PAH. - Highlights: • Role of endothelin-1 in pulmonary arterial hypertension (PAH) was investigated. • The endothelin-1 transgenic (ETTG) and wild type (WT) mice were analyzed. • ETTG mice spontaneously developed PAH under normoxia conditions. • SU5416 further aggravated PAH in ETTG mice. • Enhanced endothelin system activity could be a causative factor in

  1. Insulin Activation of the Phosphatidylinositol 3-Kinase/Protein Kinase B (Akt) Pathway Reduces Lipopolysaccharide-Induced Inflammation in Mice

    Kidd, Linda B.; Schabbauer, Gernot A.; Luyendyk, James P.; Holscher, Todd D.; Tilley, Rachel E.; Tencati, Michael; Mackman, Nigel

    2008-01-01

    Insulin is used to control pro-inflammatory hyperglycemia in critically ill patients. However, recent studies suggest that insulin-induced hypoglycemia may negate its beneficial effects in these patients. It is noteworthy that recent evidence indicates that insulin has anti-inflammatory effects that are independent of controlling hyperglycemia. To date, the mechanism by which insulin directly reduces inflammation has not been elucidated. It is well established that insulin activates phosphati...

  2. Effect of insulin-like factors on glucose transport activity in unweighted rat skeletal muscle

    Henriksen, Erik J.; Ritter, Leslie S.

    1993-01-01

    The effect of 3 or 6 days of unweighting on glucose transport activity, as assessed by 2-deoxyglucose uptake, in soleus strips stimulated by maximally effective concentrations of insulin, IGF-I, vanadate, or phospholipase C (PLC) is examined. Progressively increased responses to maximally effective doses of insulin or insulin-like growth factor were observed after 3 and 6 days of unweighting compared with weight matched control strips. Enhanced maximal responses to vanadate (6 days only) and PLC (3 and 6 days) were also observed. The data provide support for the existance of postreceptor binding mechanisms for the increased action of insulin on the glucose transport system in unweighted rat skeletal muscle.

  3. Latent cytomegalovirus infection exacerbates experimental pulmonary fibrosis by activating TGF-β1.

    Li, Yonghuai; Gao, Jian; Wang, Guoliang; Fei, Guanghe

    2016-08-01

    The aim of the present study was to investigate the hypotheses that cytomegalovirus (CMV) may trigger idiopathic pulmonary fibrosis (IPF) in a susceptible host and/or that the presence of CMV may alter IPF in response to a well-defined trigger of pulmonary fibrosis. A mouse model of murine CMV (MCMV) infection was established, and the mice were divided into a control group, bleomycin group and an MCMV+bleomycin group. Changes in the weights of the mice were determined in the three groups. Pulmonary fibrosis was detected using a histopathological method. The activity of transforming growth factor (TGF)‑β1 was measured, and the levels of E‑cadherin, Vimentin and phosphorylated (phospho)‑small mothers against decapentaplegic (SMAD)2 were determined using western blot analysis. MCMV was found to invade the lungs, however, it did not cause pulmonary fibrosis. The progression of fibrosis in the mice treated with MCMV+bleomycin was more rapid, compared with that in the control mice. The protein levels of Vimentin and phospho-SMAD2 were upregulated, whereas the level of E‑cadherin was downregulated in the MCMV+bleomycin group,. The results suggested that latent MCMV infection aggravated pulmonary fibrosis in the mouse model, possibly through the activation of TGF-β1. PMID:27279470

  4. Degradation of insulin by isolated mouse pancreatic acini. Evidence for cell surface protease activity

    In the present study, we have used isolated mouse pancreatic acini were used to investigate the relationship between 125I-insulin binding and its degradation in order to probe the nature and cellular localization of the degradative process. In these cells, the proteolysis of 125I-insulin was dependent on time and cell concentration, and was saturated by unlabeled insulin with a Km of 290 nM. Since this value was much higher than the Kd for insulin binding to its receptor (1.1 nM), the data indicated that 125I-insulin degradation by acini occurred primarily via nonreceptor mechanisms. Several lines of evidence suggested that insulin was being degraded by the neutral thiol protease, insulin degrading enzyme (IDE). First, insulin degradation was inhibited by thiolreacting agents such as N-ethylmaleimide and p-chloromercuribenzoate. Second, the Km for degradation in acini was similar to the reported Km for IDE in other tissues. Third, the enzyme activity had a relative mol wt of approximately 130,000 by gel filtration, a value similar to that reported for purified IDE. Fourth, the degrading activity was removed with a specific antibody to IDE. Other lines of evidence suggested that enzymes located on the cell surface played a role in insulin degradation by acini. First, the nonpenetrating sulfhydryl reacting agent 5,5' dithiobis-2-nitrobenzoic acid blocked 125I-insulin degradation. Second, a specific antibody to IDE identified the presence of the enzyme on the cell surface. Third, chloroquine, leupeptin and antipain, agents that inhibit lysosomal function, did not influence 125I-insulin degradation. Fourth, highly purified pancreatic plasma membranes degraded 125I-insulin

  5. Stimulation of protein phosphatase activity by insulin and growth factors in 3T3 cells

    Incubation of Swiss mouse 3T3-D1 cells with physiological concentrations of insulin resulted in a rapid and transient activation of protein phosphatase activity as measure by using [32P]phosphorylase α as substrate. Activation reached a maximum level (140% of control value) within 5 min of addition and returned to control levels within 20 min. The effect of insulin was dose-dependent with half-maximal activation occurring at ∼5 nM insulin. This activity could be completely inhibited by addition of the heat-stable protein inhibitor 2, which suggests the presence of an activated type-1 phosphatase. Similar effects on phosphatase activity were seen when epidermal growth factor and platelet-derived growth factor were tested. These results suggest that some of the intracellular effects caused by insulin and growth factors are mediated through the activation of a protein phosphatase

  6. Inhibition of carnitine palmitoyltransferase-1 activity alleviates insulin resistance in diet-induced obese mice.

    Keung, Wendy; Ussher, John R; Jaswal, Jagdip S; Raubenheimer, Monique; Lam, Victoria H M; Wagg, Cory S; Lopaschuk, Gary D

    2013-03-01

    Impaired skeletal muscle fatty acid oxidation has been suggested to contribute to insulin resistance and glucose intolerance. However, increasing muscle fatty acid oxidation may cause a reciprocal decrease in glucose oxidation, which might impair insulin sensitivity and glucose tolerance. We therefore investigated what effect inhibition of mitochondrial fatty acid uptake has on whole-body glucose tolerance and insulin sensitivity in obese insulin-resistant mice. C57BL/6 mice were fed a high-fat diet (60% calories from fat) for 12 weeks to develop insulin resistance. Subsequent treatment of mice for 4 weeks with the carnitine palmitoyltransferase-1 inhibitor, oxfenicine (150 mg/kg i.p. daily), resulted in improved whole-body glucose tolerance and insulin sensitivity. Exercise capacity was increased in oxfenicine-treated mice, which was accompanied by an increased respiratory exchange ratio. In the gastrocnemius muscle, oxfenicine increased pyruvate dehydrogenase activity, membrane GLUT4 content, and insulin-stimulated Akt phosphorylation. Intramyocellular levels of lipid intermediates, including ceramide, long-chain acyl CoA, and diacylglycerol, were also decreased. Our results demonstrate that inhibition of mitochondrial fatty acid uptake improves insulin sensitivity in diet-induced obese mice. This is associated with increased carbohydrate utilization and improved insulin signaling in the skeletal muscle, suggestive of an operating Randle Cycle in muscle. PMID:23139350

  7. Insulin Activates Vagal Afferent Neurons Including those Innervating Pancreas via Insulin Cascade and Ca(2+ Influx: Its Dysfunction in IRS2-KO Mice with Hyperphagic Obesity.

    Yusaku Iwasaki

    Full Text Available Some of insulin's functions, including glucose/lipid metabolism, satiety and neuroprotection, involve the alteration of brain activities. Insulin could signal to the brain via penetrating through the blood-brain barrier and acting on the vagal afferents, while the latter remains unproved. This study aimed to clarify whether insulin directly regulates the nodose ganglion neurons (NGNs of vagal afferents in mice. NGs expressed insulin receptor (IR and insulin receptor substrate-2 (IRS2 mRNA, and some of NGNs were immunoreactive to IR. In patch-clamp and fura-2 microfluorometric studies, insulin (10(-12∼10(-6 M depolarized and increased cytosolic Ca(2+ concentration ([Ca(2+]i in single NGNs. The insulin-induced [Ca(2+]i increases were attenuated by L- and N-type Ca(2+ channel blockers, by phosphatidylinositol 3 kinase (PI3K inhibitor, and in NGNs from IRS2 knockout mice. Half of the insulin-responsive NGNs contained cocaine- and amphetamine-regulated transcript. Neuronal fibers expressing IRs were distributed in/around pancreatic islets. The NGNs innervating the pancreas, identified by injecting retrograde tracer into the pancreas, responded to insulin with much greater incidence than unlabeled NGNs. Insulin concentrations measured in pancreatic vein was 64-fold higher than that in circulation. Elevation of insulin to 10(-7 M recruited a remarkably greater population of NGNs to [Ca(2+]i increases. Systemic injection of glibenclamide rapidly released insulin and phosphorylated AKT in NGs. Furthermore, in IRS2 knockout mice, insulin action to suppress [Ca(2+]i in orexigenic ghrelin-responsive neurons in hypothalamic arcuate nucleus was intact while insulin action on NGN was markedly attenuated, suggesting a possible link between impaired insulin sensing by NGNs and hyperphagic obese phenotype in IRS2 knockout mice These data demonstrate that insulin directly activates NGNs via IR-IRS2-PI3K-AKT-cascade and depolarization-gated Ca(2+ influx. Pancreas

  8. Oxcarbazepine and its active metabolite, (S)-licarbazepine, exacerbate seizures in a mouse model of genetic generalized epilepsy.

    Kim, Tae Hwan; Reid, Christopher A; Petrou, Steven

    2015-01-01

    Oxcarbazepine (OXC), widely used to treat focal epilepsy, is reported to exacerbate seizures in patients with generalized epilepsy. OXC is metabolized to monohydroxy derivatives in two enantiomeric forms: (R)-licarbazepine and (S)-licarbazepine. Eslicarbazepine acetate is a recently approved antiepileptic drug that is rapidly metabolized to (S)-licarbazepine. It is not known whether (S)-licarbazepine exacerbates seizures. Here, we test whether OXC or either of its enantiomers exacerbates the number of spike-and-wave discharges (SWDs) in mice harboring the human γ-aminobutyric acid A receptor (GABAA)γ2(R43Q) mutation. OXC (20 mg/kg), (S)-licarbazepine (20 mg/kg), and (R)-licarbazepine (20 mg/kg) all significantly increased the number of SWDs, while their duration was unaffected. The potential for (S)-licarbazepine to exacerbate SWDs suggests that eslicarbazepine acetate should be used with caution in generalized epilepsy. Furthermore, generalized seizure exacerbation for first-, second-, and third-generation carbamazepine-based compounds is likely to occur through a common mechanism. PMID:25489632

  9. Body fat related to daily physical activity and insulin concentrations in non-diabetic children

    Dencker, Magnus; Thorsson, Ola; Karlsson, Magnus K; Lindén, Christian; Eiberg, Stig; Wollmer, Per; Andersen, Lars Bo; Ahrén, Bo

    2008-01-01

    This study explored the associations between body fat versus daily physical activity and insulin concentrations in non-diabetic young children in a cross-sectional study of 172 children (93 boys and 79 girls) aged 8–11 years. Blood samples were analysed for serum insulin and daily physical activity was measured by accelerometers. Time spent performing vigorous activity was estimated from accelerometer data by using established cut-off points. Dual-energy x-ray absorptiometry (DXA) was used to...

  10. Coupling between insulin binding and activation of glucose transport in rat adipocytes

    Previous studies have shown that the kinetics of binding of insulin (I) to its receptor (R) in isolated rat adipocytes at 150C, where insulin degradation was observed to be negligible, could best be described by the model: R+I ↔ RI ↔ R'I. According to this model, bound insulin is distributed between two kinetically distinct states of the occupied receptor, RI and R'I. The quantities of RI and R'I contributing to the observed total binding of insulin to cells can be obtained from the four rate constants describing the model. In order to examine the possible roles of RI and R'I in mediating hormone action, insulin stimulation of carrier-mediated 3-0-methyl-[U-14C] glucose transport at 150C was studied. The results show that insulin activation of the rate of glucose transport was sigmoidal with time, and this was qualitatively similar to the formation of R'I with time. In contrast, formation of RI was described by an exponential approach to a plateau. This finding raises the possibility that R'I is the form of the insulin receptor directly mediating insulin activation of glucose transport

  11. Relationship between insulinase activity of erythrocytes and insulin resistance in patients with type 2 diabetes mellitus

    LI Chen-zhong; ZHANG Su-hua; QIU Hong-xin; WANG Ding-nian

    2001-01-01

    To investigate the relationship between insulinase activity of erythrocytes (EIA) and insulin resistance in patients with type 2 diabetes mellitus. Methods: EIA was determined with the method of radioassay of enzyme activity in 65 healthy subjects, and 109 patients with type 2 diabetes mellitus divided into 3 subgroups according to their therapy and plasma glucose control. Fasting plasma insulin (FINS) and other related indices were also measured in all the subjects. Moreover, insulin sensitive index (lSI) was calculated for estimation of insulin sensitivity. Results: EIA and FINS are increased in two subgroups of diabetic patients on hypoglycemics (subgroup A and subgroup B), and especially higher in the poor controlled subgroup of patients ( subgroup A). EIA and FINS are normal in subgroup of patients without medication (subgroup C). Moreover, ISI is decreased in all the subgroups of patients as compared with normal subjects. Correlation analysis show that EIA is inversely correlated with ISI in all subgroups of patients and normal subjects, and positively correlated with FINS in normal subjects. Conclusions:The rate of insulin degradation in erythrocytes is increased in patients with type 2 diabetes, and increased insulin degradation may result in their insulin- resistant state. Moreover, EIA may be used as one of the indices for estimation of insulin sensitivity.

  12. Dithiothreitol activation of the insulin receptor/kinase does not involve subunit dissociation of the native α2β2 insulin receptor subunit complex

    The subunit composition of the dithiothreitol- (DTT) activated insulin receptor/kinase was examined by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis and gel filtration chromatography under denaturing or nondenaturing conditions. Pretreatment of 32P-labeled insulin receptors with 50 mM DTT followed by gel filtration chromatography in 0.1% SDS demonstrated the dissociation of the α2β2 insulin receptor complex (M/sub r/ 400,000) into the monomeric 95,000 β subunit. In contrast, pretreatment of the insulin receptors with 1-50 mM DTT followed by gel filtration chromatography in 0.1% Triton X-100 resulted in no apparent alteration in mobility compared to the untreated insulin receptors. Resolution of this complex by nonreducing SDS-polyacrylamide gel electrophoresis and autoradiography demonstrated the existence of the α2β2 heterotetrameric complex with essentially no αβ heterodimeric or free monomeric β subunit species present. This suggests that the insulin receptor can reoxidize into the M/sub r/ 400,000 complex after the removal of DTT by gel filtration chromatography. To prevent reoxidation, the insulin receptors were pretreated with 50 mM DTT. Under the conditions the insulin receptors migrated as the M/sub r/ 400,000 α2β2 complex. These results demonstrate that treatment of the insulin receptors with high concentrations of DTT, followed by removal of DTT by gel filtration, results in reoxidation of the reduced α2β2 insulin receptor complex. Further, these results document that although the DTT stimulation of the insulin receptor/kinase does involve reduction of the insulin receptor subunits, it does not result in dissociation of the native α2β2 insulin receptor subunit complex

  13. Activation of transforming potential of the human insulin receptor gene

    A retrovirus containing part of the human insulin receptor (hIR) gene was constructed by replacing ros sequences in the avian sarcoma virus UR2 with hIR cDNA sequences coding for 46 amino acids of the extracellular domain and the entire transmembrane and cytoplasmic domains of the β subunit of hIR. The resulting virus, named UIR, contains the hIR sequence fused to the 5' portion of the UR2 gag gene coding for p19. UIR is capable of transforming chicken embryo fibroblasts and promoting formation of colonies in soft agar; however, it does not form tumors in vivo. A variant that arose from the parental UIR is capable of efficiently inducing sarcomas in vivo. UIR-transformed cells exhibit higher rates of glucose uptake and growth than normal cells. The 4-kilobase UIR genome codes for a membrane-associated, glycosylated gag-hIR fusion protein of 75 kDa designated P75/sup gag-hir/. P75/sup gag-hir/ contains a protein tyrosine kinase activity that is capable of undergoing autophosphorylation and of phosphorylating foreign substrates in vitro; it is phosphorylated at both serine and tyrosine residues in vivo

  14. Activation of transforming potential of the human insulin receptor gene

    Wang, L.H.; Lin, B.; Jong, S.M.J.; Dixon, D.; Ellis, L.; Roth, R.A.; Rutter, W.J.

    1987-08-01

    A retrovirus containing part of the human insulin receptor (hIR) gene was constructed by replacing ros sequences in the avian sarcoma virus UR2 with hIR cDNA sequences coding for 46 amino acids of the extracellular domain and the entire transmembrane and cytoplasmic domains of the ..beta.. subunit of hIR. The resulting virus, named UIR, contains the hIR sequence fused to the 5' portion of the UR2 gag gene coding for p19. UIR is capable of transforming chicken embryo fibroblasts and promoting formation of colonies in soft agar; however, it does not form tumors in vivo. A variant that arose from the parental UIR is capable of efficiently inducing sarcomas in vivo. UIR-transformed cells exhibit higher rates of glucose uptake and growth than normal cells. The 4-kilobase UIR genome codes for a membrane-associated, glycosylated gag-hIR fusion protein of 75 kDa designated P75/sup gag-hir/. P75/sup gag-hir/ contains a protein tyrosine kinase activity that is capable of undergoing autophosphorylation and of phosphorylating foreign substrates in vitro; it is phosphorylated at both serine and tyrosine residues in vivo

  15. Body fat related to daily physical activity and insulin concentrations in non-diabetic children

    Dencker, Magnus; Thorsson, Ola; Karlsson, Magnus K;

    2007-01-01

    This study explored the associations between body fat versus daily physical activity and insulin concentrations in non-diabetic young children in a cross-sectional study of 172 children (93 boys and 79 girls) aged 8-11 years. Blood samples were analysed for serum insulin and daily physical activity...... was measured by accelerometers. Time spent performing vigorous activity was estimated from accelerometer data by using established cut-off points. Dual-energy x-ray absorptiometry (DXA) was used to quantify abdominal fat mass (AFM) and total body fat (TBF), also calculated as percentage of body weight (BF......%). Body fat distribution was calculated as AFM/TBF. Body fat distribution was independently linked to both insulin concentrations and physical activity. In contrast, TBF, AFM, and BF% were linked to physical activity only and not to insulin concentrations. In conclusion in this population of non...

  16. Alteration of insulin content in thermal and combined radiation-thermal burns and the insulin modulating activity of blood medium-weight molecular peptides

    Influence of thermal and combined radiation thermal burns on insulin content in blood plasma was studied in mice irradiated with 137Cs in 3.4 Gy. Insulin content in blood plasma of experimental animals and patients with thermal burns was determined with the help of radioimmune method. The insulin modulating activity of bolld medium-weight molecular peptides wqas considered. The investigations conducted showed that with the severity of burn in the period of toxemia the level of immunoreactive insulin and medium-weight molecular peptides increased

  17. Kupffer cells ameliorate hepatic insulin resistance induced by high-fat diet rich in monounsaturated fatty acids: the evidence for the involvement of alternatively activated macrophages

    Papackova Zuzana

    2012-03-01

    Full Text Available Abstract Background Resident macrophages (Kupffer cells, KCs in the liver can undergo both pro- or anti-inflammatory activation pathway and exert either beneficiary or detrimental effects on liver metabolism. Until now, their role in the metabolically dysfunctional state of steatosis remains enigmatic. Aim of our study was to characterize the role of KCs in relation to the onset of hepatic insulin resistance induced by a high-fat (HF diet rich in monounsaturated fatty acids. Methods Male Wistar rats were fed either standard (SD or high-fat (HF diet for 4 weeks. Half of the animals were subjected to the acute GdCl3 treatment 24 and 72 hrs prior to the end of the experiment in order to induce the reduction of KCs population. We determined the effect of HF diet on activation status of liver macrophages and on the changes in hepatic insulin sensitivity and triacylglycerol metabolism imposed by acute KCs depletion by GdCl3. Results We found that a HF diet rich in MUFA itself triggers an alternative but not the classical activation program in KCs. In a steatotic, but not in normal liver, a reduction of the KCs population was associated with a decrease of alternative activation and with a shift towards the expression of pro-inflammatory activation markers, with the increased autophagy, elevated lysosomal lipolysis, increased formation of DAG, PKCε activation and marked exacerbation of HF diet-induced hepatic insulin resistance. Conclusions We propose that in the presence of a high MUFA content the population of alternatively activated resident liver macrophages may mediate beneficial effects on liver insulin sensitivity and alleviate the metabolic disturbances imposed by HF diet feeding and steatosis. Our data indicate that macrophage polarization towards an alternative state might be a useful strategy for treating type 2 diabetes.

  18. Functional characterization of autophosphorylation sites of the activated insulin receptor-tyrosine kinase

    Insulin receptor, solubilized from 3T3-L1 cellular membranes and then purified, was autophosphorylated with [γ-32P]ATP in the absence or presence of insulin. Specific phosphopeptides generated by trypsin digestion of the 32P-labeled β-subunit were identified and separated by reverse phase HPLC. In the absence of insulin, radioactivity of the phosphopeptides is evenly distributed among four major peaks designated as sites I, II, III and IV, according to their order of elution. This pattern is maintained for at least the first 30 min of autophosphorylation. When the reaction is carried out in the presence of insulin, > 50% of the total 32P radioactivity is found in site I and the rate of 32P incorporation into this site is markedly higher than into sites II, III and IV. Maximal activation of tyrosine kinase activity, as estimated by substrate phosphorylation, is coincident with the nearly complete phosphorylation of site I. Delayed activation of previously autophosphorylated receptor by insulin, but not by EGF or IGF-I, produced a similar pattern where phosphorylated site I predominates. These observations indicate that one major insulin-regulated autophosphorylation site in the β-subunit is responsible for activation of the insulin receptor tyrosine kinase. The isolation of this phosphopeptide on a preparative scale and its characterization are now in progress

  19. Functional characterization of autophosphorylation sites of the activated insulin receptor-tyrosine kinase

    Flores-Riveros, J.R.; Lane, M.D.

    1987-05-01

    Insulin receptor, solubilized from 3T3-L1 cellular membranes and then purified, was autophosphorylated with (..gamma..-/sup 32/P)ATP in the absence or presence of insulin. Specific phosphopeptides generated by trypsin digestion of the /sup 32/P-labeled ..beta..-subunit were identified and separated by reverse phase HPLC. In the absence of insulin, radioactivity of the phosphopeptides is evenly distributed among four major peaks designated as sites I, II, III and IV, according to their order of elution. This pattern is maintained for at least the first 30 min of autophosphorylation. When the reaction is carried out in the presence of insulin, > 50% of the total /sup 32/P radioactivity is found in site I and the rate of /sup 32/P incorporation into this site is markedly higher than into sites II, III and IV. Maximal activation of tyrosine kinase activity, as estimated by substrate phosphorylation, is coincident with the nearly complete phosphorylation of site I. Delayed activation of previously autophosphorylated receptor by insulin, but not by EGF or IGF-I, produced a similar pattern where phosphorylated site I predominates. These observations indicate that one major insulin-regulated autophosphorylation site in the ..beta..-subunit is responsible for activation of the insulin receptor tyrosine kinase. The isolation of this phosphopeptide on a preparative scale and its characterization are now in progress.

  20. ANTIDIABETIC AND HYPOLIPIDEMIC ACTIVITY OF GYMNEMA SYLVESTRE IN DEXAMETHASONE INDUCED INSULIN RESISTANCE IN ALBINO RATS

    Hemanth Kumar V, Nagendra Nayak IM , Shobha V Huilgol, Saeed M Yendigeri , Narendar K

    2015-01-01

    Background: Gymnema sylvestre plant was widely used for medicinal purpose. The plant leaves were traditionally used to treat diabetes. Aim: To determine the antidiabetic and hypolipidemic activity of Gymnema sylvestre in dexamethasone induced insulin resistance in Albino rats. Objectives: The present study was undertaken to evaluate antidiabetic and hypolipidemic activity of Gymnema sylvestre leaf aqueous extract against dexamethasone induced insulin resistance in Albino rats. Materials and M...

  1. Oxidized LDL impair adipocyte response to insulin by activating serine/threonine kinases.

    Scazzocchio, Beatrice; Varì, Rosaria; D'Archivio, Massimo; Santangelo, Carmela; Filesi, Carmelina; Giovannini, Claudio; Masella, Roberta

    2009-05-01

    Oxidized LDL (oxLDL) increase in patients affected by type-2 diabetes, obesity, and metabolic syndrome. Likewise, insulin resistance, an impaired responsiveness of target tissues to insulin, is associated with those pathological conditions. To investigate a possible causal relationship between oxLDL and the onset of insulin resistance, we evaluated the response to insulin of 3T3-L1 adipocytes treated with oxLDL. We observed that oxLDL inhibited glucose uptake (-40%) through reduced glucose transporter 4 (GLUT4) recruitment to the plasma membrane (-70%), without affecting GLUT4 gene expression. These findings were associated to the impairment of insulin signaling. Specifically, in oxLDL-treated cells insulin receptor (IR) substrate-1 (IRS-1) was highly degraded likely because of the enhanced Ser(307)phosphorylation. This process was largely mediated by the activation of the inhibitor of kappaB-kinase beta (IKKbeta) and the c-Jun NH(2)-terminal kinase (JNK). Moreover, the activation of IKKbeta positively regulated the nuclear content of nuclear factor kappaB (NF-kappaB), by inactivating the inhibitor of NF-kappaB (IkappaBalpha). The activated NF-kappaB further impaired per se GLUT4 functionality. Specific inhibitors of IKKbeta, JNK, and NF-kappaB restored insulin sensitivity in adipocytes treated with oxLDL. These data provide the first evidence that oxLDL, by activating serine/threonine kinases, impaired adipocyte response to insulin affecting pathways involved in the recruitment of GLUT4 to plasma membranes (PM). This suggests that oxLDL might participate in the development of insulin resistance. PMID:19136667

  2. Hepatic Insulin Resistance Following Chronic Activation of the CREB Coactivator CRTC2

    Hogan, Meghan F; Ravnskjaer, Kim; Matsumura, Shigenobu;

    2015-01-01

    and dephosphorylation of the cAMP regulated CREB coactivators CRTC2 and CRTC3. In parallel, decreases in circulating insulin also increase gluconeogenic gene expression via the de-phosphorylation and activation of the forkhead transcription factor FOXO1. Hepatic gluconeogenesis is increased in insulin resistance where...... accompanying decreases in FOXO1 activity, hepatic gluconeogenic gene expression remained elevated in CRTC2S171,275A mice demonstrating that chronic increases in CRTC2 activity in the liver are indeed sufficient to promote hepatic insulin resistance and to disrupt glucose homeostasis....... increased gluconeogenic gene expression under fasting as well as feeding conditions. Circulating glucose concentrations were constitutively elevated in CRTC2S171,275A expressing mice, leading to compensatory increases in circulating insulin concentrations that enhance FOXO1 phosphorylation. Despite...

  3. Insulin modulates network activity in olfactory bulb slices: impact on odour processing

    Kuczewski, Nicola; Fourcaud-Trocmé, Nicolas; Savigner, Agnès; Thevenet, Marc; Aimé, Pascaline; Garcia, Samuel; Duchamp-Viret, Patricia; Palouzier-Paulignan, Brigitte

    2014-01-01

    Odour perception depends closely on nutritional status, in animals as in humans. Insulin, the principal anorectic hormone, appears to be one of the major candidates for ensuring the link between olfactory abilities and nutritional status, by modifying processing in the olfactory bulb (OB), one of its main central targets. The present study investigates whether and how insulin can act in OB, by evaluating its action on the main output neurons activities, mitral cells (MCs), in acute rat OB slices. Insulin was found to act at two OB network levels: (1) on MCs, by increasing their excitability, probably by inhibiting two voltage-gated potassium (K+) channels; (2) on interneurons by modifying the GABAergic and on glutamatergic synaptic activity impinging on MCs, mainly reducing them. Insulin also altered the olfactory nerve (ON)-evoked excitatory postsynaptic currents in 60% of MCs. Insulin decreased or increased the ON-evoked responses in equal proportion and the direction of its effect depended on the initial neuron ON-evoked firing rate. Indeed, insulin tended to decrease the high and to increase the low ON-evoked firing rates, thereby reducing inter-MC response firing variability. Therefore, the effects of insulin on the evoked firing rates were not carried out indiscriminately in the MC population. By constructing a mathematical model, the impact of insulin complex effects on OB was assessed at the population activity level. The model shows that the reduction of variability across cells could affect MC detection and discrimination abilities, mainly by decreasing and, less frequently, increasing them, depending on odour quality. Thus, as previously proposed, this differential action of insulin on MCs across odours would allow this hormone to put the olfactory function under feeding signal control, given the discerning valence of an odour as a function of nutritional status. PMID:24710056

  4. The road to the first, fully active and more stable human insulin variant with an additional disulfide bond

    Vinther, Tine N.; Kjeldsen, Thomas B.; Jensen, Knud Jørgen;

    2015-01-01

    addressed the question whether a human insulin variant with four disulfide bonds could exist and be fully functional. In this review, we give an overview of the road to engineering four-disulfide bonded insulin analogs. During our journey, we discovered several active four disulfide bonded insulin analogs...

  5. Osteoinductive activity of insulin-functionalized cell culture surfaces obtained using diazonium chemistry

    Mikulska, Anna; Filipowska, Joanna; Osyczka, Anna; Nowakowska, Maria; Szczubiałka, Krzysztof

    2014-12-01

    Polymeric surfaces suitable for cell culture (DR/Pec) were constructed from diazoresin (DR) and pectin (Pec) in a form of ultrathin films using the layer-by-layer (LbL) technique. The surfaces were functionalized with insulin using diazonium chemistry. Such functionalized surfaces were used to culture human mesenchymal stem cells (hMSCs) to assess their suitability for bone tissue engineering and regeneration. The activity of insulin immobilized on the surfaces (DR/Pec/Ins) was compared to that of insulin dissolved in the culture medium. Human MSC grown on insulin-immobilized DR/Pec surfaces displayed increased proliferation and higher osteogenic activity. The latter was determined by means of alkaline phosphatase (ALP) activity, which increases at early stages of osteoblasts differentiation. Insulin dissolved in the culture medium did not stimulate cell proliferation and its osteogenic activity was significantly lower. Addition of recombinant human bone morphogenetic protein 2 (rhBMP-2) to the culture medium further increased ALP activity in hMSCs indicating additive osteogenic action of immobilized insulin and rhBMP-2

  6. Antidiabetic activity of 3-hydroxyflavone analogues in high fructose fed insulin resistant rats

    Nayak, Yogendra; Venkatachalam, H.; Daroji, Vijay Kumar; Mathew, Geetha; Jayashree, B. S.; Unnikrishnan, M. K.

    2014-01-01

    Synthetic 3-hydroxyflavone analogues (JY-1, JY-2, JY-3, JY-4), were tested for antidiabetic activity in high-fructose-diet-fed (66 %, for 6 weeks) insulin-resistant Wistar rats (FD-fed rats). The fasting blood glucose, insulin, creatinine and AGEs were decreased to near normal upon treatment with test compounds. Insulin resistance markers such as HOMA-IR, K-ITT, plasma triglycerides, lipids, endogenous antioxidant defense and glycogen were restored in FD-fed rats after treatment with 3-hydrox...

  7. Hydrogen peroxide induces activation of insulin signaling pathway via AMP-dependent kinase in podocytes

    Highlights: ► H2O2 activates the insulin signaling pathway and glucose uptake in podocytes. ► H2O2 induces time-dependent changes in AMPK phosphorylation. ► H2O2 enhances insulin signaling pathways via AMPK activation. ► H2O2 stimulation of glucose uptake is AMPK-dependent. -- Abstract: Podocytes are cells that form the glomerular filtration barrier in the kidney. Insulin signaling in podocytes is critical for normal kidney function. Insulin signaling is regulated by oxidative stress and intracellular energy levels. We cultured rat podocytes to investigate the effects of hydrogen peroxide (H2O2) on the phosphorylation of proximal and distal elements of insulin signaling. We also investigated H2O2-induced intracellular changes in the distribution of protein kinase B (Akt). Western blots showed that H2O2 (100 μM) induced rapid, transient phosphorylation of the insulin receptor (IR), the IR substrate-1 (IRS1), and Akt with peak activities at 5 min (Δ 183%, P 2O2>. Furthermore, H2O2 inhibited phosphorylation of the phosphatase and tensin homologue (PTEN; peak activity at 10 min; Δ −32%, P 2O2 on IR phosphorylation by about 40% (from 2.07 ± 0.28 to 1.28 ± 0.12, P 2O2 increased glucose uptake in podocytes (from 0.88 ± 0.04 to 1.29 ± 0.12 nmol/min/mg protein, P 2O2 activated the insulin signaling pathway and glucose uptake via AMPK in cultured rat podocytes. This signaling may play a potential role in the prevention of insulin resistance under conditions associated with oxidative stress.

  8. Anti-diabetic activity of insulin-degrading enzyme inhibitors mediated by multiple hormones.

    Maianti, Juan Pablo; McFedries, Amanda; Foda, Zachariah H; Kleiner, Ralph E; Du, Xiu Quan; Leissring, Malcolm A; Tang, Wei-Jen; Charron, Maureen J; Seeliger, Markus A; Saghatelian, Alan; Liu, David R

    2014-07-01

    Despite decades of speculation that inhibiting endogenous insulin degradation might treat type-2 diabetes, and the identification of IDE (insulin-degrading enzyme) as a diabetes susceptibility gene, the relationship between the activity of the zinc metalloprotein IDE and glucose homeostasis remains unclear. Although Ide(-/-) mice have elevated insulin levels, they exhibit impaired, rather than improved, glucose tolerance that may arise from compensatory insulin signalling dysfunction. IDE inhibitors that are active in vivo are therefore needed to elucidate IDE's physiological roles and to determine its potential to serve as a target for the treatment of diabetes. Here we report the discovery of a physiologically active IDE inhibitor identified from a DNA-templated macrocycle library. An X-ray structure of the macrocycle bound to IDE reveals that it engages a binding pocket away from the catalytic site, which explains its remarkable selectivity. Treatment of lean and obese mice with this inhibitor shows that IDE regulates the abundance and signalling of glucagon and amylin, in addition to that of insulin. Under physiological conditions that augment insulin and amylin levels, such as oral glucose administration, acute IDE inhibition leads to substantially improved glucose tolerance and slower gastric emptying. These findings demonstrate the feasibility of modulating IDE activity as a new therapeutic strategy to treat type-2 diabetes and expand our understanding of the roles of IDE in glucose and hormone regulation. PMID:24847884

  9. Aging Exacerbates Depressive-like Behavior in Mice in Response to Activation of the Peripheral Innate Immune System

    Godbout, Jonathan P.; Moreau, Maïté; Lestage, Jacques; Chen, Jing; Sparkman, Nathan L; O’Connor, Jason; Castanon, Nathalie; Kelley, Keith W.; Dantzer, Robert; Johnson, Rodney W.

    2007-01-01

    Exposure to peripheral infections may be permissive to cognitive and behavioral complications in the elderly. We have reported that peripheral stimulation of the innate immune system with lipopolysaccharide (LPS) causes an exaggerated neuroinflammatory response and prolonged sickness behavior in aged BALB/c mice. Because LPS also causes depressive behavior, the purpose of this study was to determine whether aging is associated with an exacerbated depressive-like response. We confirmed that LP...

  10. High fat diet exacerbates neuroinflammation in an animal model of multiple sclerosis by activation of the Renin Angiotensin system.

    Timmermans, Silke; Bogie, Jeroen; Vanmierlo, Tim; Lütjohann, Dieter; Stinissen, Piet; Hellings, Niels; Hendriks, Jerome J.A.

    2014-01-01

    Epidemiological studies suggest a positive correlation between the incidence and severity of multiple sclerosis (MS) and the intake of fatty acids. It remains to be clarified whether high fat diet (HFD) indeed can exacerbate the disease pathology associated with MS and what the underlying mechanisms are. In this study, we determined the influence of HFD on the severity and pathology of experimental autoimmune encephalomyelitis (EAE), an animal model of MS. Mice were fed either normal diet (ND...

  11. Exercise-induced changes in expression and activity of proteins involved in insulin signal transduction in skeletal muscle: Differential effects on insulin-receptor substrates 1 and 2

    Chibalin, Alexander V; Yu, Mei; Ryder, Jeffrey W.; Song, Xiao Mei; Galuska, Dana; Krook, Anna; Wallberg-Henriksson, Harriet; Juleen R. Zierath

    2000-01-01

    Level of physical activity is linked to improved glucose homeostasis. We determined whether exercise alters the expression and/or activity of proteins involved in insulin-signal transduction in skeletal muscle. Wistar rats swam 6 h per day for 1 or 5 days. Epitrochlearis muscles were excised 16 h after the last exercise bout, and were incubated with or without insulin (120 nM). Insulin-stimulated glucose transport increased 30% and 50% after 1 and 5 days of exercise, respectively. Glycogen co...

  12. Prolonged treatment of genetically obese mice with conjugated linoleic acid improves glucose tolerance and lowers plasma insulin concentration: possible involvement of PPAR activation

    Einerhand Alexandra WC

    2005-01-01

    Full Text Available Abstract Background Studies in rodents and some studies in humans have shown that conjugated linoleic acid (CLA, especially its trans-10, cis-12 isomer, reduces body fat content. However, some but not all studies in mice and humans (though none in rats have found that CLA promotes insulin resistance. The molecular mechanisms responsible for these effects are unclear, and there are conflicting reports on the effects of CLA on peroxisomal proliferator-activated receptor-γ (PPARγ activation and expression. We have conducted three experiments with CLA in obese mice over three weeks, and one over eleven weeks. We have also investigated the effects of CLA isomers in PPARγ and PPARα reporter gene assays. Results Inclusion of CLA or CLA enriched with its trans-10, cis-12 isomer in the diet of female genetically obese (lepob/lepob mice for up to eleven weeks reduced body weight gain and white fat pad weight. After two weeks, in contrast to beneficial effects obtained with the PPARγ agonist rosiglitazone, CLA or CLA enriched with its trans-10, cis-12 isomer raised fasting blood glucose and plasma insulin concentrations, and exacerbated glucose tolerance. After 10 weeks, however, CLA had beneficial effects on glucose and insulin concentrations. At this time, CLA had no effect on the plasma TNFα concentration, but it markedly reduced the plasma adiponectin concentration. CLA and CLA enriched with either isomer raised the plasma triglyceride concentration during the first three weeks, but not subsequently. CLA enriched with its trans-10, cis-12 isomer, but not with its cis-9, trans-11 isomer, stimulated PPARγ-mediated reporter gene activity; both isomers stimulated PPARα-mediated reporter gene activity. Conclusions CLA initially decreased but subsequently increased insulin sensitivity in lepob/lepob mice. Activation of both PPARγ and PPARα may contribute to the improvement in insulin sensitivity. In the short term, however, another mechanism

  13. Improved Insulin Resistance and Lipid Metabolism by Cinnamon Extract through Activation of Peroxisome Proliferator-Activated Receptors

    Xiaoyan Sheng; Yuebo Zhang; Zhenwei Gong; Cheng Huang; Ying Qin Zang

    2008-01-01

    Peroxisome proliferator-activated receptors (PPARs) are transcriptional factors involved in the regulation of insulin resistance and adipogenesis. Cinnamon, a widely used spice in food preparation and traditional antidiabetic remedy, is found to activate PPARγ and α, resulting in improved insulin resistance, reduced fasted glucose, FFA, LDL-c, and AST levels in high-caloric diet-induced obesity (DIO) and db/db mice in its water extract form. In vitro studies demonstrate that cinnamon increase...

  14. Plasma phospholipid transfer protein activity is related to insulin resistance : impaired acute lowering by insulin in obese Type II diabetic patients

    Riemens, SC; van Tol, A; Sluiter, WJ; Dullaart, RPF

    1998-01-01

    Cholesteryl ester transfer protein (CETP) and phospholipid transfer protein (PLTP) have important functions in high density lipoprotein (HDL) metabolism. We determined the association of plasma CETP and PLTP activities (measured with exogenous' substrate assays) with insulin resistance, plasma trigl

  15. Insulin-induced NADPH oxidase activation promotes proliferation and matrix metalloproteinase activation in monocytes/macrophages

    San-Jose, G. (Gorka); Bidegain, J. (J.); Robador, P.A. (Pablo A.); J. Diez; Fortuño, A. (Ana); Zalba, G. (Guillermo)

    2009-01-01

    Insulin stimulates superoxide (O(2)(-)) production in monocytes and macrophages. However, the mechanisms through which insulin induces O(2)(-) production are not completely understood. In this study, we (a) characterized the enzyme and the pathways involved in insulin-stimulated O(2)(-) production in human monocytes and murine macrophages, and (b) analyzed the consequences of insulin-stimulated O(2)(-) production on the cellular phenotype in these cells. We showed that insulin stimulated O(2)...

  16. Role of signal transducer and activator of transcription 1 in murine allergen-induced airway remodeling and exacerbation by carbon nanotubes.

    Thompson, Elizabeth A; Sayers, Brian C; Glista-Baker, Ellen E; Shipkowski, Kelly A; Ihrie, Mark D; Duke, Katherine S; Taylor, Alexia J; Bonner, James C

    2015-11-01

    Asthma is characterized by a T helper type 2 phenotype and by chronic allergen-induced airway inflammation (AAI). Environmental exposure to air pollution ultrafine particles (i.e., nanoparticles) exacerbates AAI, and a concern is possible exacerbation posed by engineered nanoparticles generated by emerging nanotechnologies. Signal transducer and activator of transcription (STAT) 1 is a transcription factor that maintains T helper type 1 cell development. However, the role of STAT1 in regulating AAI or exacerbation by nanoparticles has not been explored. In this study, mice with whole-body knockout of the Stat1 gene (Stat1(-/-)) or wild-type (WT) mice were sensitized to ovalbumin (OVA) allergen and then exposed to multiwalled carbon nanotubes (MWCNTs) by oropharygneal aspiration. In Stat1(-/-) and WT mice, OVA increased eosinophils in bronchoalveolar lavage fluid, whereas MWCNTs increased neutrophils. Interestingly, OVA sensitization prevented MWCNT-induced neutrophilia and caused only eosinophilic inflammation. Stat1(-/-) mice displayed increased IL-13 in bronchoalveolar lavage fluid at 1 day compared with WT mice after treatment with OVA or OVA and MWCNTs. At 21 days, the lungs of OVA-sensitized Stat1(-/-) mice displayed increased eosinophilia, goblet cell hyperplasia, airway fibrosis, and subepithelial apoptosis. MWCNTs further increased OVA-induced goblet cell hyperplasia, airway fibrosis, and apoptosis in Stat1(-/-) mice at 21 days. These changes corresponded to increased levels of profibrogenic mediators (transforming growth factor-β1, TNF-α, osteopontin) but decreased IL-10 in Stat1(-/-) mice. Finally, fibroblasts isolated from the lungs of Stat1(-/-) mice produced significantly more collagen mRNA and protein in response to transforming growth factor-β1 compared with WT lung fibroblasts. Our results support a protective role for STAT1 in chronic AAI and exacerbation of remodeling caused by MWCNTs. PMID:25807359

  17. A 2-wk reduction of ambulatory activity attenuates peripheral insulin sensitivity

    Krogh-Madsen, Rikke; Thyfault, John P; Broholm, Christa; Mortensen, Ole Hartvig; Olsen, Rasmus H.; Mounier, Remi; Plomgaard, Peter; van Hall, Gerrit; Booth, Frank W; Pedersen, Bente K

    2010-01-01

    US adults take between approximately 2,000 and approximately 12,000 steps per day, a wide range of ambulatory activity that at the low range could increase risk for developing chronic metabolic diseases. Dramatic reductions in physical activity induce insulin resistance; however, it is uncertain if...... and how low ambulatory activity would influence peripheral insulin sensitivity. We aimed to explore if healthy, nonexercising subjects who went from a normal to a low level of ambulatory activity for 2 wk would display metabolic alterations including reduced peripheral insulin sensitivity. To do this......, ten healthy young men decreased their daily activity level from a mean of 10,501+/-808 to 1,344+/-33 steps/day for 2 wk. Hyperinsulinemic-euglycemic clamps with stable isotopes and muscle biopsies, maximal oxygen consumption (VO2 max) tests, and blood samples were performed pre- and postintervention...

  18. Increased IL-1β activation, the culprit not only for defective insulin secretion but also for insulin resistance?

    Marianne B(o)ni-Schnetzler; Marc Y Donath

    2011-01-01

    @@ Type 2 diabetes is a chronic progressive disease characterized by insufficient insulin secretion to compensate for insulin resistance.The onset of type 2 diabetes and its progression are mainly determined by the progressive failure of the pancreatic islet β-cells to produce sufficient levels of insulin.

  19. The Guanine Nucleotide Exchange Factor ARNO mediates the activation of ARF and phospholipase D by insulin

    Fluharty Eric

    2003-09-01

    Full Text Available Abstract Background Phospholipase D (PLD is involved in many signaling pathways. In most systems, the activity of PLD is primarily regulated by the members of the ADP-Ribosylation Factor (ARF family of GTPases, but the mechanism of activation of PLD and ARF by extracellular signals has not been fully established. Here we tested the hypothesis that ARF-guanine nucleotide exchange factors (ARF-GEFs of the cytohesin/ARNO family mediate the activation of ARF and PLD by insulin. Results Wild type ARNO transiently transfected in HIRcB cells was translocated to the plasma membrane in an insulin-dependent manner and promoted the translocation of ARF to the membranes. ARNO mutants: ΔCC-ARNO and CC-ARNO were partially translocated to the membranes while ΔPH-ARNO and PH-ARNO could not be translocated to the membranes. Sec7 domain mutants of ARNO did not facilitate the ARF translocation. Overexpression of wild type ARNO significantly increased insulin-stimulated PLD activity, and mutations in the Sec7 and PH domains, or deletion of the PH or CC domains inhibited the effects of insulin. Conclusions Small ARF-GEFs of the cytohesin/ARNO family mediate the activation of ARF and PLD by the insulin receptor.

  20. A telehealth program for self-management of COPD exacerbations and promotion of an active lifestyle: a pilot randomized controlled trial

    Tabak M

    2014-09-01

    Full Text Available Monique Tabak,1,2 Marjolein Brusse-Keizer,3 Paul van der Valk,3,4 Hermie Hermens,1,2 Miriam Vollenbroek-Hutten1,2 1Telemedicine Group, Roessingh Research and Development, 2Telemedicine Group, University of Twente, 3Department of Pulmonary Medicine, Medisch Spectrum Twente, 4Medical School Twente, Medisch Spectrum Twente, Enschede, the Netherlands Abstract: The objective of this pilot study was to investigate the use of and satisfaction with a chronic obstructive pulmonary disease (COPD telehealth program applied in both primary and secondary care. The program consisted of four modules: 1 activity coach for ambulant activity monitoring and real-time coaching of daily activity behavior, 2 web-based exercise program for home exercising, 3 self-management of COPD exacerbations via a triage diary on the web portal, including self-treatment of exacerbations, and 4 teleconsultation. Twenty-nine COPD patients were randomly assigned to either the intervention group (telehealth program for 9 months or the control group (usual care. Page hits on the web portal showed the use of the program, and the Client Satisfaction Questionnaire showed satisfaction with received care. The telehealth program with decision support showed good satisfaction (mean 26.4, maximum score 32. The program was accessed on 86% of the treatment days, especially the diary. Patient adherence with the exercise scheme was low (21%. Health care providers seem to play an important role in patients' adherence to telehealth in usual care. Future research should focus on full-scale implementation in daily care and investigating technological advances, like gaming, to increase adherence. Keywords: COPD, physical activity, exacerbations, telehealth, self-management

  1. The AMPK activator R419 improves exercise capacity and skeletal muscle insulin sensitivity in obese mice

    Marcinko, Katarina; Bujak, Adam L.; Lally, James S.V.; Ford, Rebecca J.; Wong, Tammy H.; Smith, Brennan K.; Kemp, Bruce E.; Jenkins, Yonchu; Li, Wei; Kinsella, Todd M.; Hitoshi, Yasumichi; Steinberg, Gregory R.

    2015-01-01

    Objective Skeletal muscle AMP-activated protein kinase (AMPK) is important for regulating glucose homeostasis, mitochondrial content and exercise capacity. R419 is a mitochondrial complex-I inhibitor that has recently been shown to acutely activate AMPK in myotubes. Our main objective was to examine whether R419 treatment improves insulin sensitivity and exercise capacity in obese insulin resistant mice and whether skeletal muscle AMPK was important for mediating potential effects. Methods Glucose homeostasis, insulin sensitivity, exercise capacity, and electron transport chain content/activity were examined in wildtype (WT) and AMPK β1β2 muscle-specific null (AMPK-MKO) mice fed a high-fat diet (HFD) with or without R419 supplementation. Results There was no change in weight gain, adiposity, glucose tolerance or insulin sensitivity between HFD-fed WT and AMPK-MKO mice. In both HFD-fed WT and AMPK-MKO mice, R419 enhanced insulin tolerance, insulin-stimulated glucose disposal, skeletal muscle 2-deoxyglucose uptake, Akt phosphorylation and glucose transporter 4 (GLUT4) content independently of alterations in body mass. In WT, but not AMPK-MKO mice, R419 improved treadmill running capacity. Treatment with R419 increased muscle electron transport chain content and activity in WT mice; effects which were blunted in AMPK-MKO mice. Conclusions Treatment of obese mice with R419 improved skeletal muscle insulin sensitivity through a mechanism that is independent of skeletal muscle AMPK. R419 also increases exercise capacity and improves mitochondrial function in obese WT mice; effects that are diminished in the absence of skeletal muscle AMPK. These findings suggest that R419 may be a promising therapy for improving whole-body glucose homeostasis and exercise capacity. PMID:26413470

  2. CYP24A1 exacerbated activity during diabetes contributes to kidney tubular apoptosis via caspase-3 increased expression and activation.

    Alexandre Tourigny

    Full Text Available Decreases in circulating 25,hydroxyl-vitamin D3 (25 OH D3 and 1,25,dihydroxyl-vitamin D3 (1,25 (OH2 D3 have been extensively documented in patients with type 2 diabetes. Nevertheless, the molecular reasons behind this drop, and whether it is a cause or an effect of disease progression is still poorly understood. With the skin and the liver, the kidney is one of the most important sites for vitamin D metabolism. Previous studies have also shown that CYP24A1 (an enzyme implicated in vitamin D metabolism, might play an important role in furthering the progression of kidney lesions during diabetic nephropathy. In this study we show a link between CYP24A1 increase and senescence followed by apoptosis induction in the renal proximal tubules of diabetic kidneys. We show that CYP24A1 expression was increased during diabetic nephropathy progression. This increase derived from protein kinase C activation and increased H(2O(2 cellular production. CYP24A1 increase had a major impact on cellular phenotype, by pushing cells into senescence, and later into apoptosis. Our data suggest that control of CYP24A1 increase during diabetes has a beneficial effect on senescence induction and caspase-3 increased expression. We concluded that diabetes induces an increase in CYP24A1 expression, destabilizing vitamin D metabolism in the renal proximal tubules, leading to cellular instability and apoptosis, and thereby accelerating tubular injury progression during diabetic nephropathy.

  3. Antipeptide antibody that specifically inhibits insulin receptor autophosphorylation and protein kinase activity

    Two site-specific antibodies that immunoprecipitate the human insulin receptor have been prepared by immunizing rabbits with chemically synthesized peptides derived from the cDNA-predicted amino acid sequence of the β subunit of the proreceptor. Antibodies to the carboxyl terminus (AbP5) and to a domain around tyrosine-960 (AbP4) specifically recognize the β subunit of the receptor on immunoblots. Both antibodies immunoprecipitated 125I-labeled insulin-receptor complexes and the autophosphorylated receptor. Although neither antibody inhibited insulin binding to the receptor, both insulin-dependent autophosphorylation and exogenous substrate phosphorylation were inhibited by AbP4. Inhibition by AbP4 was dependent upon the phosphorylation state of the receptor; it was not detected when the receptor was autophosphorylated prior to addition of AbP4. AbP4 did not inhibit activity of the related epidermal growth factor (EGF)-receptor tyrosine protein kinase nor did it inhibit the activity of cAMP-dependent kinase or protein kinase C. The observation that an antibody directed to residues 952-967 of the proreceptor neutralizes the protein kinase activity of the β subunit suggest that this region may play a critical role in the function of the hormone-dependent, protein tyrosine-specific kinase activity of the insulin receptor

  4. Inhaled corticosteroids do not reduce initial high activity of matrix metalloproteinase (MMP)-9 in exhaled breath condensates of children with asthma exacerbation: a proof of concept study

    Grzela, Katarzyna; Zagórska, Wioletta; Krejner, Alicja; Banaszkiewicz, Aleksandra; Litwiniuk, Małgorzata; Kulus, Marek

    2016-01-01

    Inhaled corticosteroids (ICS) are the key component of asthma treatment. However, it is unclear whether they could control the activity and level of matrix metalloproteinase (MMP)-9, which is an important factor in asthma-associated inflammation and airway remodeling. Therefore, the aim of this proof of concept study was to analyze the influence of increased doses of ICS on MMP-9 in exhaled breath condensates (EBC) of patients with allergic asthma exacerbation. Apart from MMP-9, the assessment concerned selected inflammation markers – exhaled nitric oxide (eNO) and cytokines (IL-8 and TNF). The study involved a small group (n = 4) of individuals with asthma exacerbation. The intervention concerned increased doses of ICS with β-mimetics for 4 weeks. In addition to clinical evaluation, eNO measurements and EBC collections were done before and after 4 weeks of intense ICS treatment. The biochemical assessment of EBC concerned MMP-9, IL-8 and TNF. The data were compared to results of healthy controls (n = 6). The initial levels of eNO, MMP-9 and TNF in EBC were higher in the asthma group than in controls. In all subjects IL-8 levels were below the detection limit. After 4 weeks of ICS treatment in all patients we observed improvement of clinical and laboratory parameters. Interestingly, despite reduction of eNO and TNF, the activity of MMP-9/EBC remained on the initial level. Practical relevance of our results is limited by a small group. Nevertheless, our data suggest that ICS, although sufficient to control symptoms and inflammatory markers, may be ineffective to reduce MMP-9/EBC activity in asthma exacerbation and, possibly, airway remodeling. PMID:27536209

  5. Antigen Presentation and T-Cell Activation Are Critical for RBP4-Induced Insulin Resistance.

    Moraes-Vieira, Pedro M; Castoldi, Angela; Aryal, Pratik; Wellenstein, Kerry; Peroni, Odile D; Kahn, Barbara B

    2016-05-01

    Adipose tissue (AT) inflammation contributes to impaired insulin action, which is a major cause of type 2 diabetes. RBP4 is an adipocyte- and liver-derived protein with an important role in insulin resistance, metabolic syndrome, and AT inflammation. RBP4 elevation causes AT inflammation by activating innate immunity, which elicits an adaptive immune response. RBP4-overexpressing mice (RBP4-Ox) are insulin resistant and glucose intolerant and have increased AT macrophages and T-helper 1 cells. We show that high-fat diet-fed RBP4(-/-) mice have reduced AT inflammation and improved insulin sensitivity versus wild type. We also elucidate the mechanism for RBP4-induced macrophage antigen presentation and subsequent T-cell activation. In RBP4-Ox, AT macrophages display enhanced c-Jun N-terminal kinase, extracellular signal-related kinase, and p38 phosphorylation. Inhibition of these pathways and of NF-κB reduces activation of macrophages and CD4 T cells. MyD88 is an adaptor protein involved in proinflammatory signaling. In macrophages from MyD88(-/-) mice, RBP4 fails to stimulate secretion of tumor necrosis factor, IL-12, and IL-6 and CD4 T-cell activation. In vivo blockade of antigen presentation by treating RBP4-Ox mice with CTLA4-Ig, which blocks costimulation of T cells, is sufficient to reduce AT inflammation and improve insulin resistance. Thus, MyD88 and downstream mitogen-activated protein kinase and NF-κB pathways are necessary for RBP4-induced macrophage antigen presentation and subsequent T-cell activation. Also, blocking antigen presentation with CTLA4-Ig improves RBP4-induced insulin resistance and macrophage-induced T-cell activation. PMID:26936962

  6. Insulin receptor activation and down-regulation by cationic lipid transfection reagents

    Renström Ing-Marie

    2004-01-01

    Full Text Available Abstract Background Transfection agents comprised of cationic lipid preparations are widely used to transfect cell lines in culture with specific recombinant complementary DNA molecules. We have found that cells in culture are often resistant to stimulation with insulin subsequent to treatment with transfection agents such as LipofectAMINE 2000™ and FuGENE-6™. This is seen with a variety of different readouts, including insulin receptor signalling, glucose uptake into muscle cells, phosphorylation of protein kinase B and reporter gene activity in a variety of different cell types Results We now show that this is due in part to the fact that cationic lipid agents activate the insulin receptor fully during typical transfection experiments, which is then down-regulated. In attempts to circumvent this problem, we investigated the effects of increasing concentrations of LipofectAMINE 2000™ on insulin receptor phosphorylation in Chinese hamster ovary cells expressing the human insulin receptor. In addition, the efficiency of transfection that is supported by the same concentrations of transfection reagent was studied by using a green fluorescent protein construct. Our data indicate that considerably lower concentrations of LipofectAMINE 2000™ can be used than are recommended by the manufacturers. This is without sacrificing transfection efficiency markedly and avoids the problem of reducing insulin receptor expression in the cells. Conclusion Widely-used cationic lipid transfection reagents cause a state of insulin unresponsiveness in cells in culture due to fully activating and subsequently reducing the expression of the receptor in cells. This phenomenon can be avoided by reducing the concentration of reagent used in the transfection process.

  7. ANTIDIABETIC AND HYPOLIPIDEMIC ACTIVITY OF GYMNEMA SYLVESTRE IN DEXAMETHASONE INDUCED INSULIN RESISTANCE IN ALBINO RATS

    Hemanth Kumar V, Nagendra Nayak IM , Shobha V Huilgol, Saeed M Yendigeri , Narendar K

    2015-07-01

    Full Text Available Background: Gymnema sylvestre plant was widely used for medicinal purpose. The plant leaves were traditionally used to treat diabetes. Aim: To determine the antidiabetic and hypolipidemic activity of Gymnema sylvestre in dexamethasone induced insulin resistance in Albino rats. Objectives: The present study was undertaken to evaluate antidiabetic and hypolipidemic activity of Gymnema sylvestre leaf aqueous extract against dexamethasone induced insulin resistance in Albino rats. Materials and Methods: Animals were divided into five groups. Normal control and diabetic control group received gum acacia (2% orally for 12days, and normal saline (i.p., dexamethasone (8mg/kg/i.p. from day 7- day12 respectively. Two test groups (Gymnema sylvestre leaf aqueous extract 2 and 4gm/kg/p.o./12days and standard control received metformin (2gm/kg/p.o./12 days. The two test groups, standard control group received dexamethasone (8mg/kg/i.p from day 7- day 12 respectively. The antidiabetic and hypolipidemic activity was estimated by measuring serum glucose, insulin, lipid levels and histopathological evaluation of liver tissue. Results were analyzed by using one way ANOVA followed by Scheffe’s multiple comparison test. Results: Treatment with aqueous extract of Gymnema sylvestre (2 and 4gm/kg/p.o significantly (p<0.01 altered the elevated glucose, lipid, insulin levels and also improved the histopathology of liver in dexamethasone induced insulin resistance rats. Conclusion: Treatment with aqueous extract of Gymnema sylvestre improved the altered glucose, insulin and lipid profile in insulin resistance rats.

  8. The Proton-Activated Receptor GPR4 Modulates Glucose Homeostasis by Increasing Insulin Sensitivity

    Luca Giudici

    2013-11-01

    Full Text Available Background: The proton-activated G protein-coupled receptor GPR4 is expressed in many tissues including white adipose tissue. GPR4 is activated by extracellular protons in the physiological pH range (i.e. pH 7.7 - 6.8 and is coupled to the production of cAMP. Methods: We examined mice lacking GPR4 and examined glucose tolerance and insulin sensitivity in young and aged mice as well as in mice fed with a high fat diet. Expression profiles of pro- and anti-inflammatory cytokines in white adipose tissue, liver and skeletal muscle was assessed. Results: Here we show that mice lacking GPR4 have an improved intraperitoneal glucose tolerance test and increased insulin sensitivity. Insulin levels were comparable but leptin levels were increased in GPR4 KO mice. Gpr4-/- showed altered expression of PPARα, IL-6, IL-10, TNFα, and TGF-1β in skeletal muscle, white adipose tissue, and liver. High fat diet abolished the differences in glucose tolerance and insulin sensitivity between Gpr4+/+ and Gpr4-/- mice. In contrast, in aged mice (12 months old, the positive effect of GPR4 deficiency on glucose tolerance and insulin sensitivity was maintained. Liver and adipose tissue showed no major differences in the mRNA expression of pro- and anti-inflammatory factors between aged mice of both genotypes. Conclusion: Thus, GPR4 deficiency improves glucose tolerance and insulin sensitivity. The effect may involve an altered balance between pro- and anti-inflammatory factors in insulin target tissues.

  9. Complement activation capacity in plasma before and during high-dose prednisolone treatment and tapering in exacerbations of Crohn's disease and ulcerative colitis

    Baatrup Gunnar

    2005-09-01

    Full Text Available Abstract Background Ulcerative colitis (UC and Crohn's disease (CD are characterized by intestinal inflammation mainly caused by a disturbance in the balance between cytokines and increased complement (C activation. Our aim was to evaluate possible associations between C activation capacity and prednisolone treatment. Methods Plasma from patients with exacerbations of UC (n = 18 or CD (n = 18 were collected before and during high dose prednisolone treatment (1 mg/kg body weight and tapering. Friedman's two way analysis of variance, Mann-Whitney U test and Wilcoxon signed-rank sum test were used Results Before treatment, plasma from CD patients showed significant elevations in all C-mediated analyses compared to the values obtained from 38 healthy controls (p Conclusion Our findings indicate that C activation capacity is up-regulated significantly in plasma from CD patients. The decreases observed after prednisolone treatment reflect a general down-regulation in immune activation.

  10. A divergent INS protein in Caenorhabditis elegans structurally resembles human insulin and activates the human insulin receptor

    Hua, Qing-Xin; Nakagawa, Satoe H.; Wilken, Jill; Ramos, Rowena R.; Jia, Wenhua; Bass, Joseph; Weiss, Michael A.

    2003-01-01

    Caenorhabditis elegans contains a family of putative insulin-like genes proposed to regulate dauer arrest and senescence. These sequences often lack characteristic sequence features of human insulin essential for its folding, structure, and function. Here, we describe the structure and receptor-binding properties of INS-6, a single-chain polypeptide expressed in specific neurons. Despite multiple nonconservative changes in sequence, INS-6 recapitulates an insulin-like fold. Although lacking c...

  11. Elevated total and central adiposity and low physical activity are associated with insulin resistance in children.

    Krekoukia, Maria; Nassis, George P; Psarra, Glykeria; Skenderi, Katerina; Chrousos, George P; Sidossis, Labros S

    2007-02-01

    The aim of this study was 2-fold: (1) to examine insulin resistance, blood lipid levels, and inflammatory markers in 9- to 11.5-year-old obese and lean children and (2) to identify factors that influence insulin resistance in this cohort of youths. Body mass index, skinfold thickness, waist circumference, physical activity (4-day triaxial accelerometer), cardiorespiratory fitness (submaximal bicycle ergometer test), and dietary intake (3-day food records) were evaluated in 27 obese and 27 lean boys and girls. Fasting blood samples were analyzed for insulin, glucose, lipids and lipoproteins, C-reactive protein (CRP), interleukin 6, soluble intercellular adhesion molecule, and soluble vascular cell adhesion molecule. Homeostasis model assessment (HOMA) was used to evaluate insulin resistance (HOMA-IR). Obese children presented higher HOMA-IR, CRP, and blood lipid levels (all P or = 0.51), HOMA-IR (r > or = 0.56), CRP (r > or = 0.51), and blood triacylglycerol (r > or = 0.38), and were inversely correlated with high-density lipoprotein cholesterol (r > or = -0.39; all P < .01). Cardiorespiratory fitness was inversely associated with HOMA-IR (r = -0.24; P < .05), but this association disappeared when adjusted for age, sex, and fat mass. Waist circumference and total daily physical activity explained 49% of the variance in HOMA-IR in these children. In conclusion, these findings suggest that total and central adiposity are positively associated and physical activity is negatively associated with insulin resistance in children. Interventions to improve glucose metabolism in youth should target at reducing total body and abdominal fat and increasing physical activity. The lack of association between inflammatory markers and HOMA-IR suggests that obesity may precede the elevation of these markers in the evolution of insulin resistance in youth. PMID:17224334

  12. The relationship between vitamin D status, physical activity and insulin resistance in overweight and obese subjects

    Gülis Kavadar

    2015-05-01

    Full Text Available Type 2 diabetes mellitus (T2DM incidence has been increasing worldwide along with the rise of obesity and sedantery lifestyle. Decreased physical activity (PA and obesity have also been associated with the low vitamin D levels. We aimed to determine the association between PA, vitamin D status and insulin resistance in overweight and obese subjects. A total of 294 (186 female, 108 male overweight or obese subjects were included in this cross-sectional study. 25-hydroxy vitamin D (25(OHD, insulin, fasting plasma glucose (FPG and HbA1c levels were measured in blood samples. Body mass index (BMI, HOMA-index and total score of International Physical Activity Questionnaire-long form (IPAQ were calculated. Insulin resistant subjects were compared with the non-resistant group. The mean age of the participants was 45±12.25 and 41.39±10.32; 25(OHD levels were 8.91 ± 4.30 and 17.62 ± 10.47 ng/dL; BMIs were 31.29 ± 4.48  and 28.2 ± 3.16 kg/m², IPAQ total scores were 548.71±382.81 and 998±486.21 in the insulin resistant and nonresistant subjects, respectively. There was a statistically significant difference in terms of 25(OHD, FPG, insulin levels, IPAQ  total score and BMI between the two groups (p = 0.001, p = 0.001, p = 0.001, p = 0.001, p = 0.001.Significantly low 25(OHD levels, high BMI and low PA in insulin resistant subjects confirm the importance of active lifestyle and the maintenance of normal vitamin D levels in overweight and obese subjects in prevention of T2DM.

  13. Potentiation of insulin release in response to amino acid methyl esters correlates to activation of islet glutamate dehydrogenase activity

    Kofod, Hans; Lernmark, A; Hedeskov, C J

    1986-01-01

    Column perifusion of mouse pancreatic islets was used to study the ability of amino acids and their methyl esters to influence insulin release and activate islet glutamate dehydrogenase activity. In the absence of L-glutamine, L-serine and the methyl ester of L-phenylalanine, but neither L-phenyl...

  14. Structure Based Discovery of Small Molecules to Regulate the Activity of Human Insulin Degrading Enzyme

    Çakir, Bilal; Dağliyan, Onur; Dağyildiz, Ezgi; Bariş, İbrahim; Kavakli, Ibrahim Halil; Kizilel, Seda; Türkay, Metin

    2012-01-01

    Background Insulin-degrading enzyme (IDE) is an allosteric Zn+2 metalloprotease involved in the degradation of many peptides including amyloid-β, and insulin that play key roles in Alzheimer's disease (AD) and type 2 diabetes mellitus (T2DM), respectively. Therefore, the use of therapeutic agents that regulate the activity of IDE would be a viable approach towards generating pharmaceutical treatments for these diseases. Crystal structure of IDE revealed that N-terminal has an exosite which is ∼30 Å away from the catalytic region and serves as a regulation site by orientation of the substrates of IDE to the catalytic site. It is possible to find small molecules that bind to the exosite of IDE and enhance its proteolytic activity towards different substrates. Methodology/Principal Findings In this study, we applied structure based drug design method combined with experimental methods to discover four novel molecules that enhance the activity of human IDE. The novel compounds, designated as D3, D4, D6, and D10 enhanced IDE mediated proteolysis of substrate V, insulin and amyloid-β, while enhanced degradation profiles were obtained towards substrate V and insulin in the presence of D10 only. Conclusion/Significance This paper describes the first examples of a computer-aided discovery of IDE regulators, showing that in vitro and in vivo activation of this important enzyme with small molecules is possible. PMID:22355395

  15. Structure based discovery of small molecules to regulate the activity of human insulin degrading enzyme.

    Bilal Çakir

    Full Text Available BACKGROUND: Insulin-degrading enzyme (IDE is an allosteric Zn(+2 metalloprotease involved in the degradation of many peptides including amyloid-β, and insulin that play key roles in Alzheimer's disease (AD and type 2 diabetes mellitus (T2DM, respectively. Therefore, the use of therapeutic agents that regulate the activity of IDE would be a viable approach towards generating pharmaceutical treatments for these diseases. Crystal structure of IDE revealed that N-terminal has an exosite which is ∼30 Å away from the catalytic region and serves as a regulation site by orientation of the substrates of IDE to the catalytic site. It is possible to find small molecules that bind to the exosite of IDE and enhance its proteolytic activity towards different substrates. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we applied structure based drug design method combined with experimental methods to discover four novel molecules that enhance the activity of human IDE. The novel compounds, designated as D3, D4, D6, and D10 enhanced IDE mediated proteolysis of substrate V, insulin and amyloid-β, while enhanced degradation profiles were obtained towards substrate V and insulin in the presence of D10 only. CONCLUSION/SIGNIFICANCE: This paper describes the first examples of a computer-aided discovery of IDE regulators, showing that in vitro and in vivo activation of this important enzyme with small molecules is possible.

  16. Activation of cerebral sodium-glucose transporter type 1 function mediated by post-ischemic hyperglycemia exacerbates the development of cerebral ischemia.

    Yamazaki, Y; Ogihara, S; Harada, S; Tokuyama, S

    2015-12-01

    The regulation of post-ischemic hyperglycemia plays an important role in suppressing neuronal damage in therapeutic strategies for cerebral ischemia. We previously reported that the cerebral sodium-glucose transporter (SGLT) was involved in the post-ischemic hyperglycemia-induced exacerbation of cerebral ischemic neuronal damage. Cortical SGLT-1, one of the cerebral SGLT isoforms, is dramatically increased by focal cerebral ischemia. In this study, we focused on the involvement of cerebral SGLT-1 in the development of cerebral ischemic neuronal damage. It was previously reported that activation of 5'-adenosine monophosphate-activated protein kinase (AMPK) increases SGLT-1 expression. Moreover, ischemic stress-induced activation of AMPK exacerbates cerebral ischemic neuronal damage. Therefore, we directly confirmed the relationship between cerebral SGLT-1 and cerebral AMPK activation using in vitro primary culture of mouse cortical neurons. An in vivo mouse model of focal cerebral ischemia was generated using a middle cerebral artery occlusion (MCAO). The development of infarct volume and behavioral abnormalities on day 3 after MCAO were ameliorated in cerebral SGLT-1 knock down mice. Cortical and striatal SGLT-1 expression levels were significantly increased at 12h after MCAO. Immunofluorescence revealed that SGLT-1 and the neuronal nuclear antigen (NeuN) were co-localized in the cortex and striatum of MCAO mice. In the in vitro study, primary cortical neurons were cultured for five days before each treatment with reagents. Concomitant treatment with hydrogen peroxide and glucose induced the elevation of SGLT-1 and phosphorylated AMPK/AMPK ratio, and this elevation was suppressed by compound C, an AMPK inhibitor in primary cortical neurons. Moreover, compound C suppressed neuronal cell death induced by concomitant hydrogen peroxide/glucose treatment in primary cortical neurons. Therefore, we concluded that enhanced cerebral SGLT-1 function mediated by post

  17. The road to the first, fully active and more stable human insulin variant with an additional disulfide bond.

    Vinther, Tine N; Kjeldsen, Thomas B; Jensen, Knud J; Hubálek, František

    2015-11-01

    Insulin, a small peptide hormone, is crucial in maintaining blood glucose homeostasis. The stability and activity of the protein is directed by an intricate system involving disulfide bonds to stabilize the active monomeric species and by their non-covalent oligomerization. All known insulin variants in vertebrates consist of two peptide chains and have six cysteine residues, which form three disulfide bonds, two of them link the two chains and a third is an intra-chain bond in the A-chain. This classical insulin fold appears to have been conserved over half a billion years of evolution. We addressed the question whether a human insulin variant with four disulfide bonds could exist and be fully functional. In this review, we give an overview of the road to engineering four-disulfide bonded insulin analogs. During our journey, we discovered several active four disulfide bonded insulin analogs with markedly improved stability and gained insights into the instability of analogs with seven cysteine residues, importance of dimerization for stability, insulin fibril formation process, and the conformation of insulin binding to its receptor. Our results also open the way for new strategies in the development of insulin biopharmaceuticals. PMID:26382042

  18. Improved insulin sensitivity associated with reduced mitochondrial complex IV assembly and activity.

    Deepa, Sathyaseelan S; Pulliam, Daniel; Hill, Shauna; Shi, Yun; Walsh, Michael E; Salmon, Adam; Sloane, Lauren; Zhang, Ning; Zeviani, Massimo; Viscomi, Carlo; Musi, Nicolas; Van Remmen, Holly

    2013-04-01

    Mice lacking Surf1, a complex IV assembly protein, have ∼50-70% reduction in cytochrome c oxidase activity in all tissues yet a paradoxical increase in lifespan. Here we report that Surf1(-/-) mice have lower body (15%) and fat (20%) mass, in association with reduced lipid storage, smaller adipocytes, and elevated indicators of fatty acid oxidation in white adipose tissue (WAT) compared with control mice. The respiratory quotient in the Surf1(-/-) mice was significantly lower than in the control animals (0.83-0.93 vs. 0.90-0.98), consistent with enhanced fat utilization in Surf1(-/-) mice. Elevated fat utilization was associated with increased insulin sensitivity measured as insulin-stimulated glucose uptake, as well as an increase in insulin receptor levels (∼2-fold) and glucose transporter type 4 (GLUT4; ∼1.3-fold) levels in WAT in the Surf1(-/-) mice. The expression of peroxisome proliferator-activated receptor γ-coactivator 1-α (PGC-1α) mRNA and protein was up-regulated by 2.5- and 1.9-fold, respectively, in WAT from Surf1(-/-) mice, and the expression of PGC-1α target genes and markers of mitochondrial biogenesis was elevated. Together, these findings point to a novel and unexpected link between reduced mitochondrial complex IV activity, enhanced insulin sensitivity, and increased mitochondrial biogenesis that may contribute to the increased longevity in the Surf1(-/-) mice. PMID:23241310

  19. Implications for the active form of human insulin based on the structural convergence of highly active hormone analogues

    Jiráček, Jiří; Žáková, Lenka; Antolíková, Emília; Watson, Christopher J.; Turkenburg, Johan P.; Dodson, Guy G.; Brzozowski, Andrzej M.

    2010-01-01

    Insulin is a key protein hormone that regulates blood glucose levels and, thus, has widespread impact on lipid and protein metabolism. Insulin action is manifested through binding of its monomeric form to the Insulin Receptor (IR). At present, however, our knowledge about the structural behavior of insulin is based upon inactive, multimeric, and storage-like states. The active monomeric structure, when in complex with the receptor, must be different as the residues crucial for the interactions are buried within the multimeric forms. Although the exact nature of the insulin’s induced-fit is unknown, there is strong evidence that the C-terminal part of the B-chain is a dynamic element in insulin activation and receptor binding. Here, we present the design and analysis of highly active (200–500%) insulin analogues that are truncated at residue 26 of the B-chain (B26). They show a structural convergence in the form of a new β-turn at B24-B26. We propose that the key element in insulin’s transition, from an inactive to an active state, may be the formation of the β-turn at B24-B26 associated with a trans to cis isomerisation at the B25-B26 peptide bond. Here, this turn is achieved with N-methylated L-amino acids adjacent to the trans to cis switch at the B25-B26 peptide bond or by the insertion of certain D-amino acids at B26. The resultant conformational changes unmask previously buried amino acids that are implicated in IR binding and provide structural details for new approaches in rational design of ligands effective in combating diabetes. PMID:20133841

  20. TRPV1 Activation Exacerbates Hypoxia/Reoxygenation-Induced Apoptosis in H9C2 Cells via Calcium Overload and Mitochondrial Dysfunction

    Zewei Sun

    2014-10-01

    Full Text Available Transient potential receptor vanilloid 1 (TRPV1 channels, which are expressed on sensory neurons, elicit cardioprotective effects during ischemia reperfusion injury by stimulating the release of neuropeptides, namely calcitonin gene-related peptide (CGRP and substance P (SP. Recent studies show that TRPV1 channels are also expressed on cardiomyocytes and can exacerbate air pollutant-induced apoptosis. However, whether these channels present on cardiomyocytes directly modulate cell death and survival pathways during hypoxia/reoxygenation (H/R injury remains unclear. In the present study, we investigated the role of TRPV1 in H/R induced apoptosis of H9C2 cardiomyocytes. We demonstrated that TRPV1 was indeed expressed in H9C2 cells, and activated by H/R injury. Although neuropeptide release caused by TRPV1 activation on sensory neurons elicits a cardioprotective effect, we found that capsaicin (CAP; a TRPV1 agonist treatment of H9C2 cells paradoxically enhanced the level of apoptosis by increasing intracellular calcium and mitochondrial superoxide levels, attenuating mitochondrial membrane potential, and inhibiting mitochondrial biogenesis (measured by the expression of ATP synthase β. In contrast, treatment of cells with capsazepine (CPZ; a TRPV1 antagonist or TRPV1 siRNA attenuated H/R induced-apoptosis. Furthermore, CAP and CPZ treatment revealed a similar effect on cell viability and mitochondrial superoxide production in primary cardiomyocytes. Finally, using both CGRP8–37 (a CGRP receptor antagonist and RP67580 (a SP receptor antagonist to exclude the confounding effects of neuropeptides, we confirmed aforementioned detrimental effects as TRPV1−/− mouse hearts exhibited improved cardiac function during ischemia/reperfusion. In summary, direct activation of TRPV1 in myocytes exacerbates H/R-induced apoptosis, likely through calcium overload and associated mitochondrial dysfunction. Our study provides a novel understanding of the role of

  1. Direct Angiotensin II Type 2 Receptor Stimulation Ameliorates Insulin Resistance in Type 2 Diabetes Mice with PPARγ Activation

    Ohshima, Kousei; Mogi, Masaki; Jing, Fei;

    2012-01-01

    The role of angiotensin II type 2 (AT(2)) receptor stimulation in the pathogenesis of insulin resistance is still unclear. Therefore we examined the possibility that direct AT(2) receptor stimulation by compound 21 (C21) might contribute to possible insulin-sensitizing/anti-diabetic effects in type...... 2 diabetes (T2DM) with PPARγ activation, mainly focusing on adipose tissue....

  2. Early limited nitrosamine exposures exacerbate high fat diet-mediated type 2 diabetes and neurodegeneration

    Longato Lisa

    2010-03-01

    Full Text Available Abstract Background Type 2 diabetes mellitus (T2DM and several types of neurodegeneration, including Alzheimer's, are linked to insulin-resistance, and chronic high dietary fat intake causes T2DM with mild neurodegeneration. Intra-cerebral Streptozotocin, a nitrosamine-related compound, causes neurodegeneration, whereas peripheral treatment causes DM. Hypothesis Limited early exposures to nitrosamines that are widely present in the environment, enhance the deleterious effects of high fat intake in promoting T2DM and neurodegeneration. Methods Long Evans rat pups were treated with N-nitrosodiethylamine (NDEA by i.p. injection, and upon weaning, they were fed with high fat (60%; HFD or low fat (5%; LFD chow for 8 weeks. Cerebella were harvested to assess gene expression, and insulin and insulin-like growth factor (IGF deficiency and resistance in the context of neurodegeneration. Results HFD ± NDEA caused T2DM, neurodegeneration with impairments in brain insulin, insulin receptor, IGF-2 receptor, or insulin receptor substrate gene expression, and reduced expression of tau and choline acetyltransferase (ChAT, which are regulated by insulin and IGF-1. In addition, increased levels of 4-hydroxynonenal and nitrotyrosine were measured in cerebella of HFD ± NDEA treated rats, and overall, NDEA+HFD treatment reduced brain levels of Tau, phospho-GSK-3β (reflecting increased GSK-3β activity, glial fibrillary acidic protein, and ChAT to greater degrees than either treatment alone. Finally, pro-ceramide genes, examined because ceramides cause insulin resistance, oxidative stress, and neurodegeneration, were significantly up-regulated by HFD and/or NDEA exposure, but the highest levels were generally present in brains of HFD+NDEA treated rats. Conclusions Early limited exposure to nitrosamines exacerbates the adverse effects of later chronic high dietary fat intake in promoting T2DM and neurodegeneration. The mechanism involves increased generation of

  3. In situ autoradiography and ligand-dependent tyrosine kinase activity reveal insulin receptors and insulin-like growth factor I receptors in prepancreatic chicken embryos

    We previously reported specific cross-linking of 125I-labeled insulin and 125I-labeled insulin-like growth factor I (IGF-I) to the alpha subunit of their respective receptors in chicken embryos of 20 somites and older. To achieve adequate sensitivity and localize spatially the receptors in younger embryos, we adapted an autoradiographic technique using whole-mounted chicken blastoderms. Insulin receptors and IGF-I receptors were expressed and could be localized as early as gastrulation, before the first somite is formed. Relative density was analyzed by a computer-assisted image system, revealing overall slightly higher binding of IGF-I than of insulin. Structures rich in both types of receptors were predominantly of ectodermal origin: Hensen's node in gastrulating embryos and neural folds, neural tube and optic vesicles during neurulation. The signal transduction capability of the receptors in early organogenesis was assessed by their ability to phosphorylate the exogenous substrate poly(Glu80Tyr20). Ligand-dependent tyrosine phosphorylation was demonstrable with both insulin and IGF-I in glycoprotein-enriched preparations from embryos at days 2 through 6 of embryogenesis. There was a developmentally regulated change in ligand-dependent tyrosine kinase activity, with a sharp increase from day 2 to day 4, in contrast with a small increase in the ligand binding. Binding of 125I-labeled IGF-I was, with the solubilized receptors, severalfold higher than binding of 125I-labeled insulin. However, the insulin-dependent phosphorylation was as high as the IGF-I-dependent phosphorylation at each developmental stage

  4. The insulin receptor C-terminus is involved in regulation of the receptor kinase activity.

    Kaliman, P; Baron, V; Alengrin, F; Takata, Y; Webster, N J; Olefsky, J M; Van Obberghen, E

    1993-09-21

    During the insulin receptor activation process, ligand binding and autophosphorylation induce two distinct conformational changes in the C-terminal domain of the receptor beta-subunit. To analyze the role of this domain and the involvement of the C-terminal autophosphorylation sites (Tyr1316 and Tyr1322) in receptor activation, we used (i) antipeptide antibodies against three different C-terminal sequences (1270-1281, 1294-1317, and 1309-1326) and (ii) an insulin receptor mutant (Y/F2) where Tyr1316 and Tyr1322 have been replaced by Phe. We show that the autophosphorylation-induced C-terminal conformational change is preserved in the Y/F2 receptor, indicating that this change is not induced by phosphorylation of the C-terminal sites but most likely by phosphorylation of the major sites in the kinase domain (Tyr1146, Tyr1150, and Tyr1151). Binding of antipeptide antibodies to the C-terminal domain modulated (activated or inhibited) both mutant and wild-type receptor-mediated phosphorylation of poly(Glu/Tyr). In contrast to the wild-type receptor, Y/F2 exhibited the same C-terminal configuration before and after insulin binding, evidencing that mutation of Tyr1316 and Tyr1322 introduced conformational changes in the C-terminus. Finally, the mutant receptor was 2-fold more active than the wild-type receptor for poly(Glu/Tyr) phosphorylation. In conclusion, the whole C-terminal region of the insulin receptor beta-subunit is likely to exert a regulatory influence on the receptor kinase activity. Perturbations of the C-terminal region, such as binding of antipeptides or mutation of Tyr1316 and Tyr1322, provoke alterations at the receptor kinase level, leading to activation or inhibition of the enzymic activity. PMID:7690586

  5. Cafeteria diet-induced insulin resistance is not associated with decreased insulin signaling or AMPK activity and is alleviated by physical training in rats

    Brandt, Nina; De Bock, Katrien; Richter, Erik A.; Hespel, Peter

    2010-01-01

    Brandt N, De Bock K, Richter EA, Hespel P. Cafeteria diet-induced insulin resistance is not associated with decreased insulin signaling or AMPK activity and is alleviated by physical training in rats. Am J Physiol Endocrinol Metab 299: E215-E224, 2010. First published May 18, 2010; doi:10.1152/ajpendo.00098.2010.-Excess energy intake via a palatable low-fat diet (cafeteria diet) is known to induce obesity and glucose intolerance in rats. However, the molecular mechanisms behind this adaptatio...

  6. Insulin-induced decrease in protein phosphorylation in rat adipocytes not explained by decreased A-kinase activity

    In isolated rat adipocytes, insulin inhibits lipolysis to a greater extent than would be predicted by the decrease in (-/+)cAMP activity ratio of cAMP-dependent protein kinase [A-kinase], from which it was speculated that insulin promotes the dephosphorylation of hormone-sensitive lipase. They have examined the phosphorylation state of cellular proteins under conditions of varying A-kinase activities in the presence and absence of insulin. Protein phosphorylation was determined by SDS-PAGE electrophoresis of extracts from 32P-loaded cells; glycerol and A-kinase activity ratios were measured in the cytosolic extracts from control, non-radioactive cells. Increased protein phosphorylation in general occurred over the same range of A-kinase activity ratios, 0.1-0.3, associated with increased glycerol release. The insulin-induced decrease in lipolysis was associated with a decrease in the 32P content of several proteins, an effect not explained by the modest reduction in A-kinase activity by insulin. This effect of insulin on protein phosphorylation was lost as the A-kinase activity ratios exceeded 0.5. The results suggest that insulin promotes the dephosphorylation of those adipocyte proteins which are subject to phosphorylation by A-kinase

  7. Insulin-induced decrease in protein phosphorylation in rat adipocytes not explained by decreased A-kinase activity

    Egan, J.J.; Greenberg, A.S.; Chang, M.K.; Londos, C.

    1987-05-01

    In isolated rat adipocytes, insulin inhibits lipolysis to a greater extent than would be predicted by the decrease in (-/+)cAMP activity ratio of cAMP-dependent protein kinase (A-kinase), from which it was speculated that insulin promotes the dephosphorylation of hormone-sensitive lipase. They have examined the phosphorylation state of cellular proteins under conditions of varying A-kinase activities in the presence and absence of insulin. Protein phosphorylation was determined by SDS-PAGE electrophoresis of extracts from /sup 32/P-loaded cells; glycerol and A-kinase activity ratios were measured in the cytosolic extracts from control, non-radioactive cells. Increased protein phosphorylation in general occurred over the same range of A-kinase activity ratios, 0.1-0.3, associated with increased glycerol release. The insulin-induced decrease in lipolysis was associated with a decrease in the /sup 32/P content of several proteins, an effect not explained by the modest reduction in A-kinase activity by insulin. This effect of insulin on protein phosphorylation was lost as the A-kinase activity ratios exceeded 0.5. The results suggest that insulin promotes the dephosphorylation of those adipocyte proteins which are subject to phosphorylation by A-kinase.

  8. Effect of exogenous insulin on plasma and follicular insulin-like growth factor I, insulin-like growth factor binding protein activity, follicular oestradiol and progesterone, and follicular growth in superovulated Angus and Brahman cows.

    Simpson, R B; Chase, C C; Spicer, L J; Vernon, R K; Hammond, A C; Rae, D O

    1994-11-01

    Angus (n = 14) and Brahman (n = 14) cows were used to evaluate the effects of insulin administered concomitantly with FSH in a superovulation regimen. Cows were allotted to four pen replicates by treatment and breed, and received FSH (i.m.) twice a day for 5 consecutive days (first day of injections = day 0 of study) plus concomitant administration of either saline (control) or long-acting bovine insulin (0.25 iu kg-1 body mass; s.c.). Blood samples were collected at intervals of 6 h during the injection period and analysed for plasma insulin, glucose, insulin-like growth factor I (IGF-I) and IGF-I binding protein (IGFBP) activity. Cows were ovariectomized on day 5. The number and diameter of follicles were recorded. Follicular fluid was aspirated for determination of IGF-I, IGFBP activity, oestradiol and progesterone. Mean plasma concentration of glucose was lower in insulin-treated than in control cows averaged over days 1-5 (56 +/- 3 versus 82 +/- 3 mg dl-1; P 0.10) by treatment, but were higher in Brahman than in Angus cows (IGF-I: 41 +/- 6 versus 19 +/- 6 ng ml-1, P or = 8.0 mm) follicles. Brahman cows had a greater (P Angus cows (7.5 +/- 2.6 and 30.5 +/- 5.6, respectively). Diameter of large follicles was greater in insulin-treated than in control cows (11.4 +/- 0.2 versus 10.6 +/- 0.1 mm; P Brahman cows (60 +/- 2 ng ml-1) than in control Brahman cows (37 +/- 2 ng ml-1), but was lower in insulin-treated Angus cows (31 +/- 3 ng ml-1) than in control Angus cows (38 +/- 2 ng ml-1; treatment x breed interaction, P Brahman cows but was reduced (P Angus cows.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:7532225

  9. Slow acting protein extract from fruit pulp of Momordica charantia with insulin secretagogue and insulinomimetic activities.

    Yibchok-anun, Sirintorn; Adisakwattana, Sirichai; Yao, Cheng Yu; Sangvanich, Polkit; Roengsumran, Sophon; Hsu, Walter Haw

    2006-06-01

    The protein from Thai bitter gourd (Momordica charantia) fruit pulp was extracted and studied for its hypoglycemic effect. Subcutaneous administration of the protein extract (5, 10 mg/kg) significantly and markedly decreased plasma glucose concentrations in both normal and streptozotocin-induced diabetic rats in a dose-dependent manner. The onset of the protein extract-induced antihyperglycemia/hypoglycemia was observed at 4 and 6 h in diabetic and normal rats, respectively. This protein extract also raised plasma insulin concentrations by 2 fold 4 h following subcutaneous administration. In perfused rat pancreas, the protein extract (10 microg/ml) increased insulin secretion, but not glucagon secretion. The increase in insulin secretion was apparent within 5 min of administration and was persistent during 30 min of administration. Furthermore, the protein extract enhanced glucose uptake into C2C12 myocytes and 3T3-L1 adipocytes. Time course experiments performed in rat adipocytes revealed that M. charantia protein extract significantly increased glucose uptake after 4 and 6 h of incubation. Thus, the M. charantia protein extract, a slow acting chemical, exerted both insulin secretagogue and insulinomimetic activities to lower blood glucose concentrations in vivo. PMID:16755004

  10. SIRT2 inhibition exacerbates neuroinflammation and blood-brain barrier disruption in experimental traumatic brain injury by enhancing NF-κB p65 acetylation and activation.

    Yuan, Fang; Xu, Zhi-Ming; Lu, Li-Yan; Nie, Hui; Ding, Jun; Ying, Wei-Hai; Tian, Heng-Li

    2016-02-01

    Sirtuin 2 (SIRT2) is a member of the sirtuin family of NAD(+) -dependent protein deacetylases. In recent years, SIRT2 inhibition has emerged as a promising treatment for neurodegenerative diseases. However, to date, there is no evidence of a specific role for SIRT2 in traumatic brain injury (TBI). We investigated the effects of SIRT2 inhibition on experimental TBI using the controlled cortical impact (CCI) injury model. Adult male mice underwent CCI or sham surgery. A selective brain-permeable SIRT2 inhibitor, AK-7, was administrated 30 min before injury. The volume of the brain edema lesion and the water content of the brain were significantly increased in mice treated with AK-7 (20 mg/kg), compared with the vehicle group, following TBI (p aquaporin 4 (AQP4), MMP-9, and pro-inflammatory cytokines. Together, these data demonstrate that SIRT2 inhibition exacerbates TBI by increasing NF-κB p65 acetylation and activation. Our findings provide additional evidence of an anti-inflammatory effect of SIRT2. SIRT2 is a member of the sirtuin family of NAD+-dependent protein deacetylases. Our study suggests that the SIRT2 inhibitor AK-7 exacerbates traumatic brain injury (TBI) via a potential mechanism involving increased acetylation and nuclear translocation of NF-κB p65, resulting in up-regulation of NF-κB target genes, including aquaporin 4 (AQP4), matrix metalloproteinase 9 (MMP-9), and pro-inflammatory cytokines. Our findings provide additional evidence of an anti-inflammatory effect of SIRT2. PMID:26546505

  11. The structural determinants of insulin-like peptide 3 activity

    Ross AD Bathgate

    2012-02-01

    Full Text Available INSL3 is a hormone and/or paracrine factor which is a member of the relaxin peptide family. It has key roles as a fertility regulator in both males and females. The receptor for INSL3 is the leucine rich repeat (LRR containing G-protein coupled receptor 8 (LGR8 which is now known as relaxin family peptide receptor 2 (RXFP2. Receptor activation by INSL3 involves binding to the LRRs in the large ectodomain of RXFP2 by residues within the B-chain of INSL3 as well as an interaction with the transmembrane exoloops of the receptor. Although the binding to the LRRs is well characterized the features of the peptide and receptor involved in the exoloop interaction are currently unknown. This study was designed to determine the key INSL3 determinants for RXFP2 activation. A chimeric peptide approach was first utilized to demonstrate that the A-chain is critical for receptor activation. Replacement of the INSL3 A-chain with that from the related peptides INSL5 and INSL6 resulted in complete loss of activity despite only minor changes in binding affinity. Subsequent replacement of specific A-chain residues with those from the INSL5 peptide highlighted that the N-terminus of the A-chain of INSL3 is critical for its activity. Remarkably, replacement of the entire N-terminus with four or five alanine residues resulted in peptides with near native activity suggesting that specific residues are not necessary for activity. Additionally removal of two amino acids at the C-terminus of the A-chain and mutation of Lys-8 in the B-chain also resulted in minor decreases in peptide activity. Therefore we have demonstrated that the activity of the INSL3 peptide is driven predominantly by residues 5-9 in the A-chain, with minor additional contributions from the two C-terminal A-chain residues and Lys-8 in the B-chain. Using this new knowledge, we were able to produce a truncated INSL3 peptide structure which retained native activity, despite having 14 fewer residues than

  12. Free radical activity during development of insulin-dependent diabetes mellitus in the rat

    Pitkaenen, O.M.; Akerblom, H.K.; Sariola, H.; Andersson, S.M. (Univ. of Helsinki (Finland)); Martin, J.M. (Hospital for Sick Children, Toronto, Ontario (Canada)); Hallman, M. (Univ. of California, Irvine (United States))

    1991-01-01

    Free radical-induced lipid peroxidation was quantified by measuring expired pentane from diabetic prone BB Wistar rats of 45-90 d of age. Insulin-dependent diabetes mellitus was manifest at the age of 71 {plus minus} 8 d. Expired pentane increased from 2.1 {plus minus} 0.7 to 5.0 {plus minus}3.0 pmol/100g/min (p <0.01) at manifestation of the disease and remained high throughout the test period. In healthy age-matched control rats it persisted low. In rats made diabetic with streptozotocin, expired pentane remained low. The changes in expired pentane suggest that the development of endogenous insulin-dependent diabetes mellitus in BB rats is associated with increased free radical activity. This is not due to hyperglycemia or ketosis per se, and reflects a fundamental difference in the free radical activity between the spontaneously diabetic BB rats and the disease produced by streptozotocin. Development of spontaneous insulin-dependent diabetes in BB rats is associated with increased free radical activity that persists after the manifestation of the disease.

  13. Reduced insulin-mediated citrate synthase activity in cultured skeletal muscle cells from patients with type 2 diabetes

    Ørtenblad, Niels; Mogensen, Martin; Petersen, Ingrid;

    2005-01-01

    In myotubes established from patients with type 2 diabetes (T2D), lipid oxidation and insulin-mediated glucose oxidation are reduced, whereas in myotubes from obese non-diabetic subjects, exposure to palmitate impairs insulin-mediated glucose oxidation. To determine the underlying mechanisms of...... obese subjects and T2D patients. Basal CS activity was lower (14%) in diabetic myotubes compared with myotubes from lean controls (P=0.03). Incubation with insulin (1 microM) for 4 h increased the CS activity (26-33%) in myotubes from both lean (P=0.02) and obese controls (P<0.001), but not from...

  14. Leptin Regulated Insulin Secretion via Stimulating IRS2-associated Phosphoinositide 3-kinase Activity in the isolated Rat Pancreatic Islets

    袁莉; 安汉祥; 李卓娅; 邓秀玲

    2003-01-01

    To investigate the molecular mechanism of leptin regulating insulin secretion through determining the regulation of insulin secretion and the insulin receptor substrate (IRS)-2-associated phosphoinositide 3-kinase (PI3K) activity by leptin in the isolated rat pancreatic islets, pancreatic islets were isolated from male SD rats by the collagenase method. The purified islets were incubated with leptin 2 nmol/L for 1 h in the presence of 5.6 mmol/L or 11.1 mmol/L glucose. Insulin release was measured using radioimmunoassay. IRS-2-associated activity of PI3K was determined by immunoprecipitate assay and Western blot. The results showed that in the presence of 5.6 mmol/L glucose, leptin had no significant effect on both insulin secretion and IRS-2-associated PI3K activity, but in the presence of 11.1 mmol/L glucose, insulin release was significantly inhibited after the islets were exposed to leptin for 1 h (P<0. 01). PI3K inhibitor wortmannin blocked the inhibitory regulation of leptin on insulin release (P<0. 05). Western Blot assay revealed that 2 nmol/L leptin could significantly increase the IRS-2-associated activity of PI3K by 51.5 % (P<0. 05) in the presence of 11.1 mmol/L glucose. It was concluded that Leptin could significantly inhibit insulin secretion in the presence of 11.1 mmol/L glucose by stimulating IRS-2-associated activity of PI3K, which might be the molecular mechanism of leptin regulating insulin secretion.

  15. Fumosorinone, a novel PTP1B inhibitor, activates insulin signaling in insulin-resistance HepG2 cells and shows anti-diabetic effect in diabetic KKAy mice

    Insulin resistance is a characteristic feature of type 2 diabetes mellitus (T2DM) and is characterized by defects in insulin signaling. Protein tyrosine phosphatase 1B (PTP1B) is a key negative regulator of the insulin signaling pathways, and its increased activity and expression are implicated in the pathogenesis of insulin resistance. Therefore, the inhibition of PTP1B is anticipated to become a potential therapeutic strategy to treat T2DM. Fumosorinone (FU), a new natural product isolated from insect fungi Isaria fumosorosea, was found to inhibit PTP1B activity in our previous study. Herein, the effects of FU on insulin resistance and mechanism in vitro and in vivo were investigated. FU increased the insulin-provoked glucose uptake in insulin-resistant HepG2 cells, and also reduced blood glucose and lipid levels of type 2 diabetic KKAy mice. FU decreased the expression of PTP1B both in insulin-resistant HepG2 cells and in liver tissues of diabetic KKAy mice. Furthermore, FU increased the phosphorylation of IRβ, IRS-2, Akt, GSK3β and Erk1/2 in insulin-resistant HepG2 cells, as well as the phosphorylation of IRβ, IRS-2, Akt in liver tissues of diabetic KKAy mice. These results showed that FU increased glucose uptake and improved insulin resistance by down-regulating the expression of PTP1B and activating the insulin signaling pathway, suggesting that it may possess antidiabetic properties. - Highlights: • Fumosorinone is a new PTP1B inhibitor isolated from insect pathogenic fungi. • Fumosorinone attenuated the insulin resistance both in vitro and in vivo. • Fumosorinone decreased the expression of PTP1B both in vitro and in vivo. • Fumosorinone activated the insulin signaling pathway both in vitro and in vivo

  16. Fumosorinone, a novel PTP1B inhibitor, activates insulin signaling in insulin-resistance HepG2 cells and shows anti-diabetic effect in diabetic KKAy mice

    Liu, Zhi-Qin [College of Life Sciences, Key Laboratory of Medicinal Chemistry and Molecular Diagnosis of Ministry of Education, Hebei University, Baoding 071002 (China); College of Pharmaceutical Sciences, key laboratory of pharmaceutical quality control of Hebei province, Hebei University, Baoding 071002 (China); Liu, Ting; Chen, Chuan [College of Life Sciences, Key Laboratory of Medicinal Chemistry and Molecular Diagnosis of Ministry of Education, Hebei University, Baoding 071002 (China); Li, Ming-Yan; Wang, Zi-Yu; Chen, Ruo-song; Wei, Gui-xiang; Wang, Xiao-yi [College of Pharmaceutical Sciences, key laboratory of pharmaceutical quality control of Hebei province, Hebei University, Baoding 071002 (China); Luo, Du-Qiang, E-mail: duqiangluo999@126.com [College of Life Sciences, Key Laboratory of Medicinal Chemistry and Molecular Diagnosis of Ministry of Education, Hebei University, Baoding 071002 (China)

    2015-05-15

    Insulin resistance is a characteristic feature of type 2 diabetes mellitus (T2DM) and is characterized by defects in insulin signaling. Protein tyrosine phosphatase 1B (PTP1B) is a key negative regulator of the insulin signaling pathways, and its increased activity and expression are implicated in the pathogenesis of insulin resistance. Therefore, the inhibition of PTP1B is anticipated to become a potential therapeutic strategy to treat T2DM. Fumosorinone (FU), a new natural product isolated from insect fungi Isaria fumosorosea, was found to inhibit PTP1B activity in our previous study. Herein, the effects of FU on insulin resistance and mechanism in vitro and in vivo were investigated. FU increased the insulin-provoked glucose uptake in insulin-resistant HepG2 cells, and also reduced blood glucose and lipid levels of type 2 diabetic KKAy mice. FU decreased the expression of PTP1B both in insulin-resistant HepG2 cells and in liver tissues of diabetic KKAy mice. Furthermore, FU increased the phosphorylation of IRβ, IRS-2, Akt, GSK3β and Erk1/2 in insulin-resistant HepG2 cells, as well as the phosphorylation of IRβ, IRS-2, Akt in liver tissues of diabetic KKAy mice. These results showed that FU increased glucose uptake and improved insulin resistance by down-regulating the expression of PTP1B and activating the insulin signaling pathway, suggesting that it may possess antidiabetic properties. - Highlights: • Fumosorinone is a new PTP1B inhibitor isolated from insect pathogenic fungi. • Fumosorinone attenuated the insulin resistance both in vitro and in vivo. • Fumosorinone decreased the expression of PTP1B both in vitro and in vivo. • Fumosorinone activated the insulin signaling pathway both in vitro and in vivo.

  17. Hydrogen peroxide induces activation of insulin signaling pathway via AMP-dependent kinase in podocytes

    Piwkowska, Agnieszka, E-mail: apiwkowska@cmdik.pan.pl [Mossakowski Medical Research Centre, Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdansk (Poland); Rogacka, Dorota; Angielski, Stefan [Mossakowski Medical Research Centre, Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdansk (Poland); Jankowski, Maciej [Mossakowski Medical Research Centre, Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdansk (Poland); Medical University of Gdansk, Department of Therapy Monitoring and Pharmacogenetics (Poland)

    2012-11-09

    Highlights: Black-Right-Pointing-Pointer H{sub 2}O{sub 2} activates the insulin signaling pathway and glucose uptake in podocytes. Black-Right-Pointing-Pointer H{sub 2}O{sub 2} induces time-dependent changes in AMPK phosphorylation. Black-Right-Pointing-Pointer H{sub 2}O{sub 2} enhances insulin signaling pathways via AMPK activation. Black-Right-Pointing-Pointer H{sub 2}O{sub 2} stimulation of glucose uptake is AMPK-dependent. -- Abstract: Podocytes are cells that form the glomerular filtration barrier in the kidney. Insulin signaling in podocytes is critical for normal kidney function. Insulin signaling is regulated by oxidative stress and intracellular energy levels. We cultured rat podocytes to investigate the effects of hydrogen peroxide (H{sub 2}O{sub 2}) on the phosphorylation of proximal and distal elements of insulin signaling. We also investigated H{sub 2}O{sub 2}-induced intracellular changes in the distribution of protein kinase B (Akt). Western blots showed that H{sub 2}O{sub 2} (100 {mu}M) induced rapid, transient phosphorylation of the insulin receptor (IR), the IR substrate-1 (IRS1), and Akt with peak activities at 5 min ({Delta} 183%, P < 0.05), 3 min ({Delta} 414%, P < 0.05), and 10 min ({Delta} 35%, P < 0.05), respectively. Immunostaining cells with an Akt-specific antibody showed increased intensity at the plasma membrane after treatment with H{sub 2}O{sub 2}>. Furthermore, H{sub 2}O{sub 2} inhibited phosphorylation of the phosphatase and tensin homologue (PTEN; peak activity at 10 min; {Delta} -32%, P < 0.05) and stimulated phosphorylation of the AMP-dependent kinase alpha subunit (AMPK{alpha}; 78% at 3 min and 244% at 10 min). The stimulation of AMPK was abolished with an AMPK inhibitor, Compound C (100 {mu}M, 2 h). Moreover, Compound C significantly reduced the effect of H{sub 2}O{sub 2} on IR phosphorylation by about 40% (from 2.07 {+-} 0.28 to 1.28 {+-} 0.12, P < 0.05). In addition, H{sub 2}O{sub 2} increased glucose uptake in podocytes

  18. Fuel-Stimulated Insulin Secretion Depends upon Mitochondria Activation and the Integration of Mitochondrial and Cytosolic Substrate Cycles

    Gary W Cline

    2011-01-01

    The pancreatic islet β-cell is uniquely specialized to couple its metabolism and rates of insulin secretion with the levels of circulating nutrient fuels, with the mitochondrial playing a central regulatory role in this process. In the β-cell, mitochondrial activation generates an integrated signal reflecting rates of oxidativephosphorylation, Kreb's cycle flux, and anaplerosis that ultimately determines the rate of insulin exocytosis. Mitochondrial activation can be regulated by proton leak ...

  19. Fenofibrate inhibits adipocyte hypertrophy and insulin resistance by activating adipose PPARα in high fat diet-induced obese mice

    Jeong, Sunhyo; Yoon, Michung

    2009-01-01

    Peroxisome proliferator-activated receptor α (PPARα) activation in rodents is thought to improve insulin sensitivity by decreasing ectopic lipids in non-adipose tissues. Fenofibrate, a lipid-modifying agent that acts as a PPARα agonist, may prevent adipocyte hypertrophy and insulin resistance by increasing intracellular lipolysis from adipose tissue. Consistent with this hypothesis, fenofibrate decreased visceral fat mass and adipocyte size in high fat diet-fed obese mice, and concomitantly i...

  20. Tyrosine kinase activity of a chimeric insulin-like-growth-factor-1 receptor containing the insulin receptor C-terminal domain. Comparison with the tyrosine kinase activities of the insulin and insulin-like-growth-factor-1 receptors using a cell-free system.

    Mothe, I; Tartare, S; Kowalski-Chauvel, A; Kaliman, P; Van Obberghen, E; Ballotti, R

    1995-03-15

    In a previous study, we showed that a chimeric insulin-like-growth-factor-1 (IGF-1) receptor, with the beta subunit C-terminal part of the insulin receptor was more efficient in stimulating glycogen synthesis and p44mapk activity compared to the wild-type IFG-1 receptor [Tartare, S., Mothe, I., Kowalski-Chauvel, A., Breittmayer, J.-P., Ballotti, R. & Van Obberghen, E. (1994) J. Biol. Chem. 269, 11449-11455]. These data indicate that the receptor C-terminal domain plays an important role in the transmission of biological effects. To understand the molecular basis of the differences in receptor specificity, we studied the characteristics of insulin, IGF-1 and chimeric receptor tyrosine kinase activities in a cell-free system. We found that, compared to wild-type insulin and IGF-1 receptors, the chimeric receptor showed a decrease in (a) autophosphorylation, (b) tyrosine kinase activity towards insulin receptor substrate-1 and the insulin receptor-(1142-1158)-peptide, and (c) the ability to activate phosphatidylinositol 3-kinase. However, for all the effects measured in a cell-free system, the chimeric receptor displayed an increased response to IGF-1 compared to the native IGF-1 receptor. Concerning the cation dependence of the tyrosine kinase activity, we showed that, at 10 mM Mg2+, the ligand-stimulated phosphorylation of poly(Glu80Tyr20) by both insulin receptor and chimeric receptor was increased by Mn2+. Conversely at 50 mM Mg2+, the chimeric receptor behaved like the IGF-1 receptor, since the presence of Mn2+ decreased the stimulatory effect of IGF-1 on their kinase activity. Furthermore, the Km of the chimeric receptor for ATP was increased compared to the wild-type receptors. These data demonstrate that the replacement of the C-terminal tail of the IGF-1 receptor by that of the insulin receptor has changed the receptor characteristics studied in a cell-free system. Our findings indicate that the C-terminal domain of the insulin receptor beta subunit plays a

  1. COPD exacerbations · 3: Pathophysiology

    O'Donnell, D. E.; Parker, C M

    2006-01-01

    Exacerbations of chronic obstructive pulmonary disease (COPD) are associated with increased morbidity and mortality. The effective management of COPD exacerbations awaits a better understanding of the underlying pathophysiological mechanisms that shape its clinical expression. The clinical presentation of exacerbations of COPD is highly variable and ranges from episodic symptomatic deterioration that is poorly responsive to usual treatment, to devastating life threatening events. This undersc...

  2. TLR4 mutation reduces microglial activation, increases Aβ deposits and exacerbates cognitive deficits in a mouse model of Alzheimer's disease

    Song Min

    2011-08-01

    Full Text Available Abstract Background Amyloid plaques, a pathological hallmark of Alzheimer's disease (AD, are accompanied by activated microglia. The role of activated microglia in the pathogenesis of AD remains controversial: either clearing Aβ deposits by phagocytosis or releasing proinflammatory cytokines and cytotoxic substances. Microglia can be activated via toll-like receptors (TLRs, a class of pattern-recognition receptors in the innate immune system. We previously demonstrated that an AD mouse model homozygous for a loss-of-function mutation of TLR4 had increases in Aβ deposits and buffer-soluble Aβ in the brain as compared with a TLR4 wild-type AD mouse model at 14-16 months of age. However, it is unknown if TLR4 signaling is involved in initiation of Aβ deposition as well as activation and recruitment of microglia at the early stage of AD. Here, we investigated the role of TLR4 signaling and microglial activation in early stages using 5-month-old AD mouse models when Aβ deposits start. Methods Microglial activation and amyloid deposition in the brain were determined by immunohistochemistry in the AD models. Levels of cerebral soluble Aβ were determined by ELISA. mRNA levels of cytokines and chemokines in the brain and Aβ-stimulated monocytes were quantified by real-time PCR. Cognitive functions were assessed by the Morris water maze. Results While no difference was found in cerebral Aβ load between AD mouse models at 5 months with and without TLR4 mutation, microglial activation in a TLR4 mutant AD model (TLR4M Tg was less than that in a TLR4 wild-type AD model (TLR4W Tg. At 9 months, TLR4M Tg mice had increased Aβ deposition and soluble Aβ42 in the brain, which were associated with decrements in cognitive functions and expression levels of IL-1β, CCL3, and CCL4 in the hippocampus compared to TLR4W Tg mice. TLR4 mutation diminished Aβ-induced IL-1β, CCL3, and CCL4 expression in monocytes. Conclusion This is the first demonstration of TLR4

  3. CHANGES IN LEVELS OF SOLUBLE T-CELL ACTIVATION MARKERS, SIL-2R, SCD4 AND SCD8, IN RELATION TO DISEASE EXACERBATIONS IN PATIENTS WITH SYSTEMIC LUPUS-ERYTHEMATOSUS - A PROSPECTIVE-STUDY

    SPRONK, P.E.; TERBORG, E.J.; HUITEMA, M.G.; Limburg, Piet; Kallenberg, Cees

    1994-01-01

    Objectives-To assess serial activation of T-cell subsets in relation to auto-antibody production and the occurrence of disease exacerbations in patients with systemic lupus erythematosus (SLE). Methods-To study the possible role of T-cells in the pathophysiology of the disease, 16 consecutive exacer

  4. Separate domains of the insulin receptor contain sites of autophosphorylation and tyrosine kinase activity

    The authors have studied the structure and function of the solubilized insulin receptor before and after partial proteolytic digestion to define domains in the β-subunit that undergo autophosphorylation and contain the tyrosine kinase activity. Wheat germ agglutinin purified insulin receptor from Fao cells was digested briefly at 220C with low concentrations of trypsin, staphylococcal V8 protease, or elastase. Autophosphorylation of the β-subunit was carried out before and after digestion, and the [32P]phosphoproteins were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, detected by autoradiography, and analyzed by tryptic peptide mapping by use of reverse-phase high-performance liquid chromatography. The 85-kDa fragment was not immunoprecipitated by an antibody directed against the C-terminal domain of the β-subunit (αPep-1), indicating that this region of the receptor was lost. The 85-kDa fragment contained about half of the [32P]phosphate originally found in the β-subunit, and tryptic peptide mapping showed that two major tryptic phosphopeptides (previously called pY2 and pY3) were removed. Three other tryptic phosphopeptides (pY1, pY1a, and pY4) were found in the 85- and 70-kDa fragments. To determined the structural requirements for kinase activity, the insulin receptor was subjected to tryptic digestion for 30 s-30 min, such that the receptor was composed exclusively of 85- and 70-kDa fragments of the β-subunit. The 85-kDa fragment exhibited autophosphorylation at pY1, pY1a, and pY4. Both the 85- and 70-kDa fragments phosphorylated tyrosine residues in a synthetic decapeptide that has the sequence of the C-terminal domain of the β-subunit of human insulin rare in the receptor

  5. Preparation of biologically active monomeric ferritin-insulin and its use as a high resolution electron microscopic marker of occupied insulin receptors

    A rapid, reproducible method for preparing monomeric ferritin-insulin conjugate is described using porcine insulin and horse spleen ferritin as starting materials. The standard protocol includes superactivation of ferritin, conjugation of insulin, neutralization of unreacted aldehyde group, concentration of ferritin and ferritin-insulin, and purification of monomeric ferritin-insulin. Characterization was performed by radioimmunoassay, radioreceptor assay, and bioassay

  6. c-Jun represses the human insulin promoter activity that depends on multiple cAMP response elements

    Inagaki, Nobuya; Seino, Yutaka; Imura, Hiroo (Kyoto Univ. (Japan)); Maekawa, Toshio; Sudo, Tatsuhiko; Ishii, Shunsuke (Inst. of Physical and Chemical Research (RIKEN), Tsukuba (Japan))

    1992-02-01

    Glucose is known to increase the cAMP concentration in pancreatic {beta} cells. To determine the mechanism by which cAMP augments insulin gene expression, the authors first identified the cAMP response elements (CREs) of human insulin gene. In DNase I footprint analysis, the bacterially synthesized CRE-binding protein, CRE-BP1, protected four sites: two sites in the region upstream from the insulin core promoter, one site in the first exon, and one site in the first intron. To examine the roles of those four sites, they constructed a series of DNA plasmids in which the wild-type and mutant insulin promoters were linked to the chloramphenicol acetyltransferase gene. Studies of the transcriptional activity of these plasmids after transfection into hamster insulinoma (HIT) cells showed that these four sites contributed additively to the cAMP inducibility of the insulin promoter. Surprisingly, the c-jun protooncogene product (c-Jun) repressed the cAMP-induced activity of the insulin promoter in a cotransfection assay with the c-Jun expression plasmic. Northern blot analysis demonstrated that the level of c-jun mRNA was dramatically increased by glucose deprivation in HIT cells. These results suggest that glucose deprivation in HIT cells. These results suggest that glucose may regulate expression of the human insulin gene through multiple CREs and c-Jun.

  7. Subthreshold α2-Adrenergic Activation Counteracts Glucagon-Like Peptide-1 Potentiation of Glucose-Stimulated Insulin Secretion

    Minglin Pan

    2011-01-01

    Full Text Available The pancreatic β cell harbors α2-adrenergic and glucagon-like peptide-1 (GLP-1 receptors on its plasma membrane to sense the corresponding ligands adrenaline/noradrenaline and GLP-1 to govern glucose-stimulated insulin secretion. However, it is not known whether these two signaling systems interact to gain the adequate and timely control of insulin release in response to glucose. The present work shows that the α2-adrenergic agonist clonidine concentration-dependently depresses glucose-stimulated insulin secretion from INS-1 cells. On the contrary, GLP-1 concentration-dependently potentiates insulin secretory response to glucose. Importantly, the present work reveals that subthreshold α2-adrenergic activation with clonidine counteracts GLP-1 potentiation of glucose-induced insulin secretion. This counteractory process relies on pertussis toxin- (PTX- sensitive Gi proteins since it no longer occurs following PTX-mediated inactivation of Gi proteins. The counteraction of GLP-1 potentiation of glucose-stimulated insulin secretion by subthreshold α2-adrenergic activation is likely to serve as a molecular mechanism for the delicate regulation of insulin release.

  8. Interleukin-18 activates skeletal muscle AMPK and reduces weight gain and insulin resistance in mice

    Madsen, Birgitte Lindegaard; Matthews, Vance B; Brandt, Claus;

    2013-01-01

    receptor (IL-18R(-/-)), fed a standard chow or high fat diet (HFD). We next performed gain of function experiments in skeletal muscle, in vitro, ex vivo and in vivo. We show that IL-18 is implicated in metabolic homeostasis, inflammation and insulin resistance via mechanisms involving the activation of......-18 into skeletal muscle activated AMPK and concomitantly inhibited high fat diet-induced weight gain. In summary IL-18 enhances AMPK signaling and lipid oxidation in skeletal muscle implicating IL-18 in metabolic homeostasis....

  9. Biosynthetic 20-kilodalton methionyl-human growth hormone has diabetogenic and insulin-like activities.

    Kostyo, J L; Cameron, C M; Olson, K.C.; Jones, A J; Pai, R C

    1985-01-01

    The anterior pituitary gland produces a 20-kilodalton (kDa) variant of human growth hormone (hGH) that differs from the predominant 22-kDa form of hGH in that amino acid residues 32-46 are deleted. Previous work has suggested that the 20-kDa variant possesses the full growth-promoting and lactogenic activities of 22-kDa hGH but lacks its intrinsic diabetogenic and insulin-like activities. In the present study, recombinant DNA techniques were used to prepare biosynthetic 20-kDa hGH, and some o...

  10. Comparison of In Vivo Effects of Insulin on SREBP-1c Activation and INSIG-1/2 in Rat Liver and Human and Rat Adipose Tissue

    Boden, Guenther; Salehi, Sajad; Cheung, Peter; Homko, Carol; Song, Weiwei; Loveland-Jones, Catherine; Jayarajan, Senthil

    2013-01-01

    The stimulatory effects of insulin on de novo lipogenesis (DNL) in the liver, where it is an important contributor to non-alcoholic fatty liver disease (NAFLD), hepatic and systemic insulin resistance, is strong and well established. In contrast, insulin plays only a minor role in DNL in adipose tissue. The reason why insulin stimulates DNL more in liver than in fat is not known but may be due to differential regulation of the transcription and post-translational activation of sterol regulato...

  11. Activation of transmembrane bile acid receptor TGR5 stimulates insulin secretion in pancreatic β cells

    Highlights: ► G protein coupled receptor TGR5 is expressed in mouse and human islets. ► TGR5 is coupled to activation of Gs and Ca2+ release via cAMP/Epac/PLC-ε pathway. ► Activation of TGR5 by bile salts and selective ligands causes insulin secretion. ► TGR5 could be a potential therapeutic target to treat diabetes. -- Abstract: Bile acids act as signaling molecules and stimulate the G protein coupled receptor, TGR5, in addition to nuclear farnesoid X receptor to regulate lipid, glucose and energy metabolism. Bile acid induced activation of TGR5 in the enteroendocrine cells promotes glucagon like peptide-1 (GLP-1) release, which has insulinotropic effect in the pancreatic β cells. In the present study, we have identified the expression of TGR5 in pancreatic β cell line MIN6 and also in mouse and human pancreatic islets. TGR5 selective ligands, oleanolic acid (OA) and INT-777 selectively activated Gαs and caused an increase in intracellular cAMP and Ca2+. OA and INT-777 also increased phosphoinositide (PI) hydrolysis and the increase was blocked by NF449 (a selective Gαs inhibitor) or (U73122) (PI hydrolysis inhibitor). OA, INT-777 and lithocholic acid increased insulin release in MIN6 and human islets and the increase was inhibited by treatment with NF449, (U73122) or BAPTA-AM (chelator of calcium), but not with myristoylated PKI (PKA inhibitor), suggesting that the release is dependent on Gs/cAMP/Ca2+ pathway. 8-pCPT-2′-O-Me-cAMP, a cAMP analog, which activates Epac, but not PKA also stimulated PI hydrolysis. In conclusion, our study demonstrates that the TGR5 expressed in the pancreatic β cells regulates insulin secretion and highlights the importance of ongoing therapeutic strategies targeting TGR5 in the control of glucose homeostasis.

  12. Dairy Consumption and Insulin Resistance: The Role of Body Fat, Physical Activity, and Energy Intake

    Larry A. Tucker

    2015-01-01

    Full Text Available The relationship between dairy consumption and insulin resistance was ascertained in 272 middle-aged, nondiabetic women using a cross-sectional design. Participants kept 7-day, weighed food records to report their diets, including dairy intake. Insulin resistance was assessed using the homeostatic model assessment (HOMA. The Bod Pod was used to measure body fat percentage, and accelerometry for 7 days was used to objectively index physical activity. Regression analysis was used to determine the extent to which mean HOMA levels differed across low, moderate, and high dairy intake categories. Results showed that women in the highest quartile of dairy consumption had significantly greater log-transformed HOMA values (0.41 ± 0.53 than those in the middle-two quartiles (0.22 ± 0.55 or the lowest quartile (0.19 ± 0.58 (F = 6.90, P = 0.0091. The association remained significant after controlling for each potential confounder individually and all covariates simultaneously. Adjusting for differences in energy intake weakened the relationship most, but the association remained significant. Of the 11 potential confounders, only protein intake differed significantly across the dairy categories, with those consuming high dairy also consuming more total protein than their counterparts. Apparently, high dairy intake is a significant predictor of insulin resistance in middle-aged, nondiabetic women.

  13. Inhibition of human insulin gene transcription by peroxisome proliferator-activated receptor γ and thiazolidinedione oral antidiabetic drugs

    Schinner, S; Krätzner, R; Baun, D; Dickel, C; Blume, R; Oetjen, E

    2009-01-01

    Background and purpose: The transcription factor peroxisome proliferator-activated receptor γ (PPARγ) is essential for glucose homeostasis. PPARγ ligands reducing insulin levels in vivo are used as drugs to treat type 2 diabetes mellitus. Genes regulated by PPARγ have been found in several tissues including insulin-producing pancreatic islet β-cells. However, the role of PPARγ at the insulin gene was unknown. Therefore, the effect of PPARγ and PPARγ ligands like rosiglitazone on insulin gene transcription was investigated. Experimental approach: Reporter gene assays were used in the β-cell line HIT and in primary mature pancreatic islets of transgenic mice. Mapping studies and internal mutations were carried out to locate PPARγ-responsive promoter regions. Key results: Rosiglitazone caused a PPARγ-dependent inhibition of insulin gene transcription in a β-cell line. This inhibition was concentration-dependent and had an EC50 similar to that for the activation of a reporter gene under the control of multimerized PPAR binding sites. Also in normal primary pancreatic islets of transgenic mice, known to express high levels of PPARγ, rosiglitazone inhibited glucose-stimulated insulin gene transcription. Transactivation and mapping experiments suggest that, in contrast to the rat glucagon gene, the inhibition of the human insulin gene promoter by PPARγ/rosiglitazone does not depend on promoter-bound Pax6 and is attributable to the proximal insulin gene promoter region around the transcription start site from −56 to +18. Conclusions and implications: The human insulin gene represents a novel PPARγ target that may contribute to the action of thiazolidinediones in type 2 diabetes mellitus. PMID:19338578

  14. Insulin sensitizers prevent fine particulate matter-induced vascular insulin resistance and changes in endothelial progenitor cell homeostasis.

    Haberzettl, Petra; McCracken, James P; Bhatnagar, Aruni; Conklin, Daniel J

    2016-06-01

    Exposure to fine particular matter (PM2.5) increases the risk of developing cardiovascular disease and Type 2 diabetes. Because blood vessels are sensitive targets of air pollutant exposure, we examined the effects of concentrated ambient PM2.5 (CAP) on vascular insulin sensitivity and circulating levels of endothelial progenitor cells (EPCs), which reflect cardiovascular health. We found that CAP exposure for 9 days decreased insulin-stimulated Akt phosphorylation in the aorta of mice maintained on control diet. This change was accompanied by the induction of IL-1β and increases in the abundance of cleaved IL-18 and p10 subunit of Casp-1, consistent with the activation of the inflammasome pathway. CAP exposure also suppressed circulating levels of EPCs (Flk-1(+)/Sca-1(+) cells), while enhancing the bone marrow abundance of these cells. Although similar changes in vascular insulin signaling and EPC levels were observed in mice fed high-fat diet, CAP exposure did not exacerbate diet-induced changes in vascular insulin resistance or EPC homeostasis. Treatment with an insulin sensitizer, metformin or rosiglitazone, prevented CAP-induced vascular insulin resistance and NF-κB and inflammasome activation and restored peripheral blood and bone marrow EPC levels. These findings suggest that PM2.5 exposure induces diet-independent vascular insulin resistance and inflammation and prevents EPC mobilization, and that this EPC mobilization defect could be mediated by vascular insulin resistance. Impaired vascular insulin sensitivity may be an important mechanism underlying PM2.5-induced vascular injury, and pharmacological sensitization to insulin action could potentially prevent deficits in vascular repair and mitigate vascular inflammation due to exposure to elevated levels of ambient air pollution. PMID:27016579

  15. Deletion of Asn{sup 281} in the {alpha}-subunit of the human insulin receptor causes constitutive activation of the receptor and insulin desensitization

    Desbois-Mouthon, C.; Sert-Langeron, C.; Magre, J.; Blivet, M.J. [INSERM, Paris (France)] [and others

    1996-02-01

    We studied the structure and function of the insulin receptor (IR) in two sisters with leprechaunism. The patients had inherited alterations in the IR gene and were compound heterozygotes. Their paternal IR allele carried a major deletion, including exons 10-13, which shifted the reading frame and introduced a premature chain termination codon in the IR sequence. This allele was expressed at a very low level in cultured fibroblasts (<10% of total IR messenger ribonucleic acid content) and encoded a truncated protein lacking transmembrane and tyrosine kinase domains. The maternal IR allele was deleted of 3 bp in exon 3, causing the loss of Asn{sup 281} in the {alpha}-subunit. This allele generated levels of IR messenger ribonucleic acid and cell surface receptors similar to those seen in control fibroblasts. However, IRs from patients` cells had impaired insulin binding and exhibited in vivo and in vitro constitutive activation of autophosphorylation and tyrosine kinase activity. As a result of this IR-preactivated state, the cells were desensitized to insulin stimulation of glycogen and DNA syntheses. These findings strongly suggest that Asn{sup 281} of the IR {alpha}-subunit plays a critical role in the inhibitory constraint exerted by the extracellular {alpha}-subunit over the intracellular kinase activity. 59 refs., 6 figs.

  16. Insulin resistance reduces arterial prostacyclin synthase and eNOS activities by increasing endothelial fatty acid oxidation

    DU, XUELIANG; Edelstein, Diane; Obici, Silvana; Higham, Ninon; Zou, Ming-Hui; Brownlee, Michael

    2006-01-01

    Insulin resistance markedly increases cardiovascular disease risk in people with normal glucose tolerance, even after adjustment for known risk factors such as LDL, triglycerides, HDL, and systolic blood pressure. In this report, we show that increased oxidation of FFAs in aortic endothelial cells without added insulin causes increased production of superoxide by the mitochondrial electron transport chain. FFA-induced overproduction of superoxide activated a variety of proinflammatory signals...

  17. Analysis of Phosphatidylinositol 3-kinase Activation in the Adipose Tissue of Gestational Diabetes Mellitus Patients and Insulin Resistance

    初永丽; 刘文娟; 崔青; 冯桂姣; 王彦; 姜学强

    2010-01-01

    The P85 regulatory subunit protein and gene expression and P110 catalylic subunit activity of phosphatidylinositol 3-kinase (PI-3K) were investigated in adipose tissue of patients with gestational diabetes mellitus (GDM) in order to explore the molecular mechanisms of insulin resistance (IR) of GDM. Samples from patients with GDM (n=50), and controls (n=50) were collected. Fasting insulin (FIN) was determined by radioimmunoassay. Fasting plasma glucose (FPG) was measured by oxidase assay. Western blot techn...

  18. Akt/PKB activation and insulin signaling: a novel insulin signaling pathway in the treatment of type 2 diabetes

    Mackenzie RWA; Elliott BT

    2014-01-01

    Richard WA Mackenzie, Bradley T Elliott Department of Human and Health Sciences, Facility of Science and Technology, University of Westminster, London, UK Abstract: Type 2 diabetes is a metabolic disease categorized primarily by reduced insulin sensitivity, β-cell dysfunction, and elevated hepatic glucose production. Treatments reducing hyperglycemia and the secondary complications that result from these dysfunctions are being sought after. Two distinct pathways encourage glucose tr...

  19. The influence of thyroid function and bone turnover on lipoprotein profile in young physically active men with different insulin sensitivity.

    Kęska, A; Lutosławska, G; Czajkowska, A; Tkaczyk, J; Mazurek, K; Tomaszewski, P

    2014-06-01

    Physical activity induces changes in the endocrine system. Previous data indicated that changes in insulin secretion and the tissue response to this hormone are very important for energy metabolism. It is believed that they are accompanied by changes in lipid metabolism, but factors contributing to this process are still disputed. The aim of this study was to assess interactions among insulin sensitivity, thyroid function, a bone turnover marker and serum lipid profile in young physically active men. Eighty-seven physical education students, aged 18-23 years, participated in the study. We measured serum levels of glucose, lipids, insulin, thyroid-stimulating hormone (TSH), osteocalcin and anthropometric parameters. Insulin sensitivity was determined using homeostatic model assessment for insulin resistance (HOMA-IR). The median value of HOMA-IR (1.344) was used to divide the study population into Group A (above the median) and Group B (below the median). Men from both groups did not differ in anthropometric parameters or in daily physical activity. Triglycerides (TG), total cholesterol (TC) and high-density lipoprotein cholesterol (HDL-C) levels were higher in Group A (P lipid profile at a certain level of insulin sensitivity. PMID:24899778

  20. New Target Genes for the Peroxisome Proliferator-Activated Receptor-γ (PPARγ Antitumour Activity: Perspectives from the Insulin Receptor

    Daniela P. Foti

    2009-01-01

    Full Text Available The insulin receptor (IR plays a crucial role in mediating the metabolic and proliferative functions triggered by the peptide hormone insulin. There is considerable evidence that abnormalities in both IR expression and function may account for malignant transformation and tumour progression in some human neoplasias, including breast cancer. PPARγ is a ligand-activated, nuclear hormone receptor implicated in many pleiotropic biological functions related to cell survival and proliferation. In the last decade, PPARγ agonists—besides their known action and clinical use as insulin sensitizers—have proved to display a wide range of antineoplastic effects in cells and tissues expressing PPARγ, leading to intensive preclinical research in oncology. PPARγ and activators affect tumours by different mechanisms, involving cell proliferation and differentiation, apoptosis, antiinflammatory, and antiangiogenic effects. We recently provided evidence that PPARγ and agonists inhibit IR by non canonical, DNA-independent mechanisms affecting IR gene transcription. We conclude that IR may be considered a new PPARγ “target” gene, supporting a potential use of PPARγ agonists as antiproliferative agents in selected neoplastic tissues that overexpress the IR.

  1. Inhibition of human insulin gene transcription and MafA transcriptional activity by the dual leucine zipper kinase.

    Stahnke, Marie-Jeannette; Dickel, Corinna; Schröder, Sabine; Kaiser, Diana; Blume, Roland; Stein, Roland; Pouponnot, Celio; Oetjen, Elke

    2014-09-01

    Insulin biosynthesis is an essential β-cell function and inappropriate insulin secretion and biosynthesis contribute to the pathogenesis of diabetes mellitus type 2. Previous studies showed that the dual leucine zipper kinase (DLK) induces β-cell apoptosis. Since β-cell dysfunction precedes β-cell loss, in the present study the effect of DLK on insulin gene transcription was investigated in the HIT-T15 β-cell line. Downregulation of endogenous DLK increased whereas overexpression of DLK decreased human insulin gene transcription. 5'- and 3'-deletion human insulin promoter analyses resulted in the identification of a DLK responsive element that mapped to the DNA binding-site for the β-cell specific transcription factor MafA. Overexpression of DLK wild-type but not its kinase-dead mutant inhibited MafA transcriptional activity conferred by its transactivation domain. Furthermore, in the non-β-cell line JEG DLK inhibited MafA overexpression-induced human insulin promoter activity. Overexpression of MafA and DLK or its kinase-dead mutant into JEG cells revealed that DLK but not its mutant reduced MafA protein content. Inhibition of the down-stream DLK kinase c-Jun N-terminal kinase (JNK) by SP600125 attenuated DLK-induced MafA loss. Furthermore, mutation of the serine 65 to alanine, shown to confer MafA protein stability, increased MafA-dependent insulin gene transcription and prevented DLK-induced MafA loss in JEG cells. These data suggest that DLK by activating JNK triggers the phosphorylation and degradation of MafA thereby attenuating insulin gene transcription. Given the importance of MafA for β-cell function, the inhibition of DLK might preserve β-cell function and ultimately retard the development of diabetes mellitus type 2. PMID:24726898

  2. Structure Based Discovery of Small Molecules to Regulate the Activity of Human Insulin Degrading Enzyme

    Bilal Çakir; Onur Dağliyan; Ezgi Dağyildiz; İbrahim Bariş; Ibrahim Halil Kavakli; Seda Kizilel; Metin Türkay

    2012-01-01

    Structure Based Discovery of Small Molecules to Regulate the Activity of Human Insulin Degrading Enzyme Bilal C¸ akir1, Onur Dag˘ liyan1, Ezgi Dag˘ yildiz1, I˙brahim Baris¸1, Ibrahim Halil Kavakli1,2*, Seda Kizilel1*, Metin Tu¨ rkay3* 1 Department of Chemical and Biological Engineering, Koc¸ University, Sariyer, Istanbul, Turkey, 2 Department of Molecular Biology and Genetics, Koc¸ University, Sariyer, Istanbul, Turkey, 3 Department of Industrial Engineering, Koc¸ University...

  3. Work-related exacerbation of asthma.

    Henneberger, Paul K; Hoffman, Christopher D; Magid, David J; Lyons, Ella E

    2002-01-01

    Adults with asthma who had been enrolled in an HMO for at least a year were requested to complete a questionnaire about their health status. Approximately 25% of the 1,461 participants responded positively to "Does your current work environment make your asthma worse?" and were classified as having workplace exacerbation of asthma. Those with workplace exacerbation were more likely to have never attended college, be current or former smokers, have a history of other respiratory diseases, have missed work or usual activities at least one day in the past for weeks, and report their asthma was moderate, severe, or very severe. Percentages with workplace exacerbation of asthma were highest for mining and construction (36%), wholesale and retail trade (33%), and public administration (33%), and lowest for educational services (22%), finance, insurance, and real estate (22%), and non-medical and non-educational services (18%). Future studies are needed for objective validation of self-reported workplace exacerbation, and to follow subjects prospectively to clarify the temporal sequence of workplace exacerbation and asthma severity, and how other respiratory conditions and smoking might contribute to work-related worsening of asthma. PMID:12412844

  4. Somatostatin modulates insulin-degrading-enzyme metabolism: implications for the regulation of microglia activity in AD.

    Grazia Tundo

    Full Text Available The deposition of β-amyloid (Aβ into senile plaques and the impairment of somatostatin-mediated neurotransmission are key pathological events in the onset of Alzheimer's disease (AD. Insulin-degrading-enzyme (IDE is one of the main extracellular protease targeting Aβ, and thus it represents an interesting pharmacological target for AD therapy. We show that the active form of somatostatin-14 regulates IDE activity by affecting its expression and secretion in microglia cells. A similar effect can also be observed when adding octreotide. Following a previous observation where somatostatin directly interacts with IDE, here we demonstrate that somatostatin regulates Aβ catabolism by modulating IDE proteolytic activity in IDE gene-silencing experiments. As a whole, these data indicate the relevant role played by somatostatin and, potentially, by analogue octreotide, in preventing Aβ accumulation by partially restoring IDE activity.

  5. Involvement of tristetraprolin in transcriptional activation of hepatic 3-hydroxy-3-methylglutaryl coenzyme A reductase by insulin

    Highlights: ► siRNAs to tristetraprolin blocks transcription of HMGR in vivo in rat liver. ► siRNAs to tristetraprolin inhibits insulin activation of HMGR transcription. ► Insulin acts to rapidly increase tristetraprolin in liver nuclear extracts. -- Abstract: Several AU-rich RNA binding element (ARE) proteins were investigated for their possible effects on transcription of hepatic 3-hydroxy-3-methyglutaryl coenzyme A reductase (HMGR) in normal rats. Using in vivo electroporation, four different siRNAs to each ARE protein were introduced together with HMGR promoter (−325 to +20) luciferase construct and compared to saline controls. All four siRNAs to tristetraprolin (TTP) completely eliminated transcription from the HMGR promoter construct. Since insulin acts to rapidly increase hepatic HMGR transcription, the effect of TTP siRNA on induction by insulin was tested. The 3-fold stimulation by insulin was eliminated by this treatment. In comparison, siRNA to AU RNA binding protein/enoyl coenzyme A hydratase (AUH) had no effect. These findings indicate a role for TTP in the insulin-mediated activation of hepatic HMGR transcription.

  6. Involvement of tristetraprolin in transcriptional activation of hepatic 3-hydroxy-3-methylglutaryl coenzyme A reductase by insulin

    Ness, Gene C., E-mail: gness@hsc.usf.edu [Department of Molecular Medicine, College of Medicine, University of South Florida, Tampa, FL 33612 (United States); Edelman, Jeffrey L.; Brooks, Patricia A. [Department of Molecular Medicine, College of Medicine, University of South Florida, Tampa, FL 33612 (United States)

    2012-03-30

    Highlights: Black-Right-Pointing-Pointer siRNAs to tristetraprolin blocks transcription of HMGR in vivo in rat liver. Black-Right-Pointing-Pointer siRNAs to tristetraprolin inhibits insulin activation of HMGR transcription. Black-Right-Pointing-Pointer Insulin acts to rapidly increase tristetraprolin in liver nuclear extracts. -- Abstract: Several AU-rich RNA binding element (ARE) proteins were investigated for their possible effects on transcription of hepatic 3-hydroxy-3-methyglutaryl coenzyme A reductase (HMGR) in normal rats. Using in vivo electroporation, four different siRNAs to each ARE protein were introduced together with HMGR promoter (-325 to +20) luciferase construct and compared to saline controls. All four siRNAs to tristetraprolin (TTP) completely eliminated transcription from the HMGR promoter construct. Since insulin acts to rapidly increase hepatic HMGR transcription, the effect of TTP siRNA on induction by insulin was tested. The 3-fold stimulation by insulin was eliminated by this treatment. In comparison, siRNA to AU RNA binding protein/enoyl coenzyme A hydratase (AUH) had no effect. These findings indicate a role for TTP in the insulin-mediated activation of hepatic HMGR transcription.

  7. PLTP activity in premenopausal women. Relationship with lipoprotein lipase, HDL, LDL, body fat, and insulin resistance.

    Murdoch, S J; Carr, M C; Hokanson, J E; Brunzell, J D; Albers, J J

    2000-02-01

    Plasma phospholipid transfer protein (PLTP) is thought to play a major role in the facilitated transfer of phospholipids between lipoproteins and in the modulation of high density lipoprotein (HDL) particle size and composition. However, little has been reported concerning the relationships of PLTP with plasma lipoprotein parameters, lipolytic enzymes, body fat distribution, insulin, and glucose in normolipidemic individuals, particularly females. In the present study, 50 normolipidemic healthy premenopausal females were investigated. The relationships between the plasma PLTP activity and selected variables were assessed. PLTP activity was significantly and positively correlated with low density lipoprotein (LDL) cholesterol (r(s) = 0.53), apoB (r(s) = 0.44), glucose (r(s) = 0.40), HDL cholesterol (r(s) = 0.38), HDL(3) cholesterol (r(s) = 0.37), lipoprotein lipase activity (r(s) = 0.36), insulin (r(s) = 0.33), subcutaneous abdominal fat (r(s) = 0.36), intra-abdominal fat (r(s) = 0.29), and body mass index (r(s) = 0.29). HDL(2) cholesterol, triglyceride, and hepatic lipase were not significantly related to PLTP activity. As HDL(2) can be decreased by hepatic lipase and hepatic lipase is increased in obesity with increasing intra-abdominal fat, the participants were divided into sub-groups of non-obese (n = 35) and obese (n = 15) individuals and the correlation of PLTP with HDL(2) cholesterol was re-examined. In the non-obese subjects, HDL(2) cholesterol was found to be significantly and positively related to PLTP activity (r(s) = 0.44). Adjustment of the HDL(2) values for the effect of hepatic lipase activity resulted in a significant positive correlation between PLTP and HDL(2) (r(s) = 0.41), indicating that the strength of the relationship between PLTP activity and HDL(2) can be reduced by the opposing effect of hepatic lipase on HDL(2) concentrations. We conclude that PLTP-facilitated lipid transfer activity is related to HDL and LDL metabolism, as well as

  8. Improved Insulin Resistance and Lipid Metabolism by Cinnamon Extract through Activation of Peroxisome Proliferator-Activated Receptors

    Xiaoyan Sheng

    2008-01-01

    Full Text Available Peroxisome proliferator-activated receptors (PPARs are transcriptional factors involved in the regulation of insulin resistance and adipogenesis. Cinnamon, a widely used spice in food preparation and traditional antidiabetic remedy, is found to activate PPARγ and α, resulting in improved insulin resistance, reduced fasted glucose, FFA, LDL-c, and AST levels in high-caloric diet-induced obesity (DIO and db/db mice in its water extract form. In vitro studies demonstrate that cinnamon increases the expression of peroxisome proliferator-activated receptors γ and α (PPARγ/α and their target genes such as LPL, CD36, GLUT4, and ACO in 3T3-L1 adipocyte. The transactivities of both full length and ligand-binding domain (LBD of PPARγ and PPARα are activated by cinnamon as evidenced by reporter gene assays. These data suggest that cinnamon in its water extract form can act as a dual activator of PPARγ and α, and may be an alternative to PPARγ activator in managing obesity-related diabetes and hyperlipidemia.

  9. Insulin secretion enhancing activity of roselle calyx extract in normal and streptozotocin-induced diabetic rats

    Eamruthai Wisetmuen

    2013-01-01

    Full Text Available Background and Objective: Our recent study revealed the antihyperglycemic activity of an ethanolic extract of roselle calyxes (Hibiscus sabdariffa in diabetic rats. The present study had, therefore, an objective to investigate the mechanism underlying this activity. Materials and Methods: Male Sprague Dawley rats were induced to be diabetes by intraperitoneal injection of 45 mg/kg streptozotocin (STZ. Normal rats as well as diabetic rats were administered with the ethanolic extract of H. sabdariffa calyxes (HS-EE at 0.1 and 1.0 g/kg/day, respectively, for 6 weeks. Then, blood glucose and insulin levels, at basal and glucose-stimulated secretions, were measured. The pancreas was dissected to examine histologically. Results: HS-EE 1.0 g/kg/day significantly decreased the blood glucose level by 38 ± 12% in diabetic rats but not in normal rats. In normal rats, treatment with 1.0 g/kg HS-EE increased the basal insulin level significantly as compared with control normal rats (1.28 ± 0.25 and 0.55 ± 0.05 ng/ml, respectively. Interestingly, diabetic rats treated with 1.0 g/kg HS-EE also showed a significant increase in basal insulin level as compared with the control diabetic rats (0.30 ± 0.05 and 0.15 ± 0.01 ng/ml, respectively. Concerning microscopic histological examination, HS-EE 1.0 g/kg significantly increased the number of islets of Langerhans in both normal rats (1.2 ± 0.1 and 2.0 ± 0.1 islet number/10 low-power fields (LPF for control and HS-EE treated group, respectively and diabetic rats (1.0 ± 0.3 and 3.9 ± 0.6 islet number/10 LPF for control and HS-EE treated group, respectively. Conclusion: The antidiabetic activity of HS-EE may be partially mediated via the stimulating effect on insulin secretion.

  10. Studies on the mechanism of insulin resistance in the liver from humans with noninsulin-dependent diabetes. Insulin action and binding in isolated hepatocytes, insulin receptor structure, and kinase activity.

    Caro, J F; Ittoop, O; Pories, W J; Meelheim, D; Flickinger, E G; F. Thomas; Jenquin, M; Silverman, J F; Khazanie, P G; Sinha, M K

    1986-01-01

    We have developed a method to isolate insulin-responsive human hepatocytes from an intraoperative liver biopsy to study insulin action and resistance in man. Hepatocytes from obese patients with noninsulin-dependent diabetes were resistant to maximal insulin concentration, and those from obese controls to submaximal insulin concentration in comparison to nonobese controls. Insulin binding per cell number was similar in all groups. However, insulin binding per surface area was decreased in the...

  11. THE ROLE OF PHYSICAL ACTIVITY IN THE PRIMARY PREVENTION OF TYPE 2 DIABETES VIA THE AMELIORATION OF INSULIN RESISTANCE

    Ash C. Routen

    2010-08-01

    Full Text Available Type 2 diabetes is the most common endocrine disease in our society, affecting around 5% of Western populations, whilst showing a steady rise in prevalence. The complications that arise from the disease are known to cause morbidity and mortality, and are associated with long-term damage, dysfunction, and failure of variousorgans. These complications include atherosclerosis in the micro and macro vasculature, kidney dysfunction, nerve problems, hypertension; and eye problems such as retinopathy. Epidemiological evidence suggests regular physical activity improves insulin sensitivity. This review presents the case for physical activity as a tool ofprimary prevention, in the population of non-diabetics and high risk individuals (IFG & IGT, in reference to obesity related insulin resistance. Cross-sectional, prospective cohort and randomised control trials clearly show that moderate-intensity physical activity can improve insulin sensitivity; this can be improved further byundertaking vigorous-intensity physical activity.

  12. Analysis of IRS-1-mediated phosphatidylinositol 3-kinase activation in the adipose tissue of polycystic ovary syndrome patients complicated with insulin resistance

    Objective: To investigate the insulin receptor substance-1 (IRS-1)-mediated phosphatidylinositol-3 (PI-3) kinase activity in adipose tissue of polycystic ovary syndrome (PCOS) patients, and to explore molecular mechanisms of insulin resistance of PCOS. Methods: Blood and adipose tissue samples from patients with PCOS with insulin resistance (n=19), PCOS without insulin resistance (n=10) and controls (n=15) were collected. Serum luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone (T) were measured by chemiluminescence assay. Fasting insulin (FIN) was measured by radioimmunoassay. Fasting plasma glucose (FPG) was measured by oxidase assay. Insulin resistance index (IR) was calculated using homeostasis model assessment (HOMA) to analyze the relationship between these markers and insulin resistance. The tyrosine phosphorylation of IRS-1 was measured by immunoprecipitation and enhanced chemiluminescent immunoblotting technique. PI-3 kinase activity was detected by immunoprecipitation, thin-layer chromatography and gamma scintillation counting. The results were analyzed by statistical methods. Results: 1) The levels of serum LH, LH/FSH, T, FIN and HOMA-IR in PCOS without insulin resistance were significantly higher than those of control group (all P<0.05); the levels of serum LH, LH/FSH, T, FIN and HOMA-IR in PCOS with insulin resistance were significantly higher than those of PCOS without insulin resistance (all P<0.05). 2) The tyrosine phosphorylation analysis of IRS-1 showed that IRS-1 tyrosine phosphorylation was significantly decreased in PCOS with insulin resistance compared to that of PCOS without insulin resistance and control groups (P<0.01). 3) PI-3 kinase activity was significantly decreased (P<0.01) and negatively correlated with HOMA-IR. Conclusion: In consequence of the weaker signal caused by the change of upper stream signal molecule IRS-1 tyrosine phosphorylation, PI-3 kinase activity decreased, it affects the insulin signal

  13. Inhibition of carnitine palmitoyltransferase-1 activity alleviates insulin resistance in diet-induced obese mice

    Keung, Wendy; Ussher, John R.; Jaswal, Jagdip S.; Raubenheimer, Monique; Lam, Victoria H.M.; Wagg, Cory S.; Lopaschuk, Gary D

    2013-01-01

    Impaired skeletal muscle fatty acid oxidation has been suggested to contribute to insulin resistance and glucose intolerance. However, increasing muscle fatty acid oxidation may cause a reciprocal decrease in glucose oxidation, which might impair insulin sensitivity and glucose tolerance. We therefore investigated what effect inhibition of mitochondrial fatty acid uptake has on whole-body glucose tolerance and insulin sensitivity in obese insulin-resistant mice. C57BL/6 mice were fed a high-f...

  14. Oxidized LDL impair adipocyte response to insulin by activating serine/threonine kinases

    Scazzocchio, Beatrice; Varì, Rosaria; D'Archivio, Massimo; Santangelo, Carmela; Filesi, Carmelina; Giovannini, Claudio; Masella, Roberta

    2009-01-01

    Oxidized LDL (oxLDL) increase in patients affected by type-2 diabetes, obesity, and metabolic syndrome. Likewise, insulin resistance, an impaired responsiveness of target tissues to insulin, is associated with those pathological conditions. To investigate a possible causal relationship between oxLDL and the onset of insulin resistance, we evaluated the response to insulin of 3T3-L1 adipocytes treated with oxLDL. We observed that oxLDL inhibited glucose uptake (−40%) through reduced glucose tr...

  15. Tyrosine-specific protein kinase activity is associated with the purified insulin receptor.

    Kasuga, M.; Fujita-Yamaguchi, Y; Blithe, D L; Kahn, C. R.

    1983-01-01

    Highly purified human placental insulin receptors were obtained by sequential affinity chromatography on wheat germ agglutinin and insulin-agarose. The preparation had an insulin binding capacity of 4,700 pmol/mg of protein approaching theoretical purity. The purified receptor revealed three major bands of Mr 135,000, 95,000, and 52,000 in NaDodSO4/polyacrylamide gel electrophoresis after reduction by dithiothreitol. All three bands were immunoprecipitated by anti-insulin-receptor antibodies....

  16. Insulin activation of mouse diaphragm glycogen synthase (GS) involves generation of electrophoretically distinct subunit species

    Glycogen synthase, the rate limiting enzyme for glycogen synthesis, was analyzed in mouse diaphragm extracts both by immunoprecipitation and immunoblotting using specific antibodies raised to the rabbit muscle enzyme. Diaphragms, with the supporting ribs attached, were incubated either with or without [32P]P/sub i/ in the medium. In extracts from unincubated, rapidly frozen diaphragms, immunoblotting indicated the presence of 3 distinct species, separated by SDS-polyacrylamide gel electrophoresis (SDS-PAGE). In addition, phosphorylation of immunoprecipitated GS with the kinase F/sub A//GSK-3 converted the higher mobility forms into the low mobility species. In diaphragms incubated with [32P]P/sub i/, 32P was incorporated only into one of the GS species, that of lowest mobility, indicating differential labelling among the multiple subunit forms. Insulin action, which increased the -/+ glucose-6-P activity ratio from 0.2 to 0.4, converted the low mobility species to the two higher mobility forms. The authors propose that this effect of insulin can be explained by dephosphorylation in the proline/serine rich site 3 region of GS, which has potent influence on both mobility on SDS-PAGE and activity

  17. Insulin analog with additional disulfide bond has increased stability and preserved activity

    Vinther, Tine N.; Norrman, Mathias; Ribel, Ulla;

    2013-01-01

    bond may enhance insulin structural stability which would be highly desirable in a pharmaceutical use. To address this hypothesis, we designed insulin with an additional interchain disulfide bond in positions A10/B4 based on Cα-Cα distances, solvent exposure, and side-chain orientation in human insulin...

  18. 25-hydroxyvitamin D deficiency, exacerbation frequency and human rhinovirus exacerbations in chronic obstructive pulmonary disease

    Quint Jennifer K

    2012-06-01

    Full Text Available Abstract Background 25-hydroxyvitamin D deficiency is associated with COPD and increased susceptibility to infection in the general population. Methods We investigated whether COPD patients deficient in 25-hydroxyvitamin D were more likely to be frequent exacerbators, had reduced outdoor activity and were more susceptible to human rhinovirus (HRV exacerbations than those with insufficient and normal levels. We also investigated whether the frequency of FokI, BsmI and TaqIα 25-hydroxyvitamin D receptor (VDR polymorphisms differed between frequent and infrequent exacerbators. Results There was no difference in 25-hydroxyvitamin D levels between frequent and infrequent exacerbators in the summer; medians 44.1nmol/L (29.1 – 68.0 and 39.4nmol/L (22.3 – 59.2 or winter; medians 24.9nmol/L (14.3 – 43.1 and 27.1nmol/L (19.9 – 37.6. Patients who spent less time outdoors in the 14 days prior to sampling had lower 25-hydroxyvitamin D levels (p = 0.02. Day length was independently associated with 25-hydroxyvitamin D levels (p = 0.02. There was no difference in 25-hydroxyvitamin D levels between baseline and exacerbation; medians 36.2nmol/L (IQR 22.4-59.4 and 33.3nmol/L (23.0-49.7; p = 0.43. HRV positive exacerbations were not associated with lower 25-hydroxyvitamin D levels at exacerbation than exacerbations that did not test positive for HRV; medians 30.0nmol/L (20.4 – 57.8 and 30.6nmol/L (19.4 – 48.7. There was no relationship between exacerbation frequency and any VDR polymorphisms (all p > 0.05. Conclusions Low 25-hydroxyvitamin D levels in COPD are not associated with frequent exacerbations and do not increase susceptibility to HRV exacerbations. Independent of day length, patients who spend less time outdoors have lower 25-hydroxyvitamin D concentration.

  19. Total and free insulin-like growth factor I, insulin-like growth factor binding protein 3 and acid-labile subunit reflect clinical activity in acromegaly

    Sneppen, S B; Lange, Merete Wolder; Pedersen, L M; Kristensen L, L Ø; Main, K M; Juul, A; Skakkebaek, N E; Feldt-Rasmussen, U

    2001-01-01

    insulin-like growth factor binding protein-3 (IGFBP-3) with PV(pos) of 0.69 and 0.71 and PV(neg) of 0.91 and 0.92 respectively. We conclude that free IGF-I is more closely related than total IGF-I to perceived disease activity and is as such useful when evaluating previously treated acromegaly for disease...... the inactive and the active groups, we found that positive and negative predictive values (PV(pos), PV(neg)) for clinical disease activity of total and free insulin-like growth factor-I (IGF-I) were 0.59, 0.90 and 1.00, 0.82 respectively. Acid-labile subunit (ALS) showed diagnostic merit similar to...... activity. Total IGF-I, IGFBP-3 and ALS possess a higher PV(neg) for the clinical disease activity. None of the parameters can at present be claimed to be superior to the others and thus all the measured parameters are recommended to be part of the evaluation of acromegalic patients....

  20. Bioluminescence imaging of β cells and intrahepatic insulin gene activity under normal and pathological conditions.

    Tokio Katsumata

    Full Text Available In diabetes research, bioluminescence imaging (BLI has been applied in studies of β-cell impairment, development, and islet transplantation. To develop a mouse model that enables noninvasive imaging of β cells, we generated a bacterial artificial chromosome (BAC transgenic mouse in which a mouse 200-kbp genomic fragment comprising the insulin I gene drives luciferase expression (Ins1-luc BAC transgenic mouse. BLI of mice was performed using the IVIS Spectrum system after intraperitoneal injection of luciferin, and the bioluminescence signal from the pancreatic region analyzed. When compared with MIP-Luc-VU mice [FVB/N-Tg(Ins1-lucVUPwrs/J] expressing luciferase under the control of the 9.2-kbp mouse insulin I promoter (MIP, the bioluminescence emission from Ins1-luc BAC transgenic mice was enhanced approximately 4-fold. Streptozotocin-treated Ins1-luc BAC transgenic mice developed severe diabetes concomitant with a sharp decline in the BLI signal intensity in the pancreas. Conversely, mice fed a high-fat diet for 8 weeks showed an increase in the signal, reflecting a decrease or increase in the β-cell mass. Although the bioluminescence intensity of the islets correlated well with the number of isolated islets in vitro, the intensity obtained from a living mouse in vivo did not necessarily reflect an absolute quantification of the β-cell mass under pathological conditions. On the other hand, adenovirus-mediated gene transduction of β-cell-related transcription factors in Ins1-luc BAC transgenic mice generated luminescence from the hepatic region for more than 1 week. These results demonstrate that BLI in Ins1-luc BAC transgenic mice provides a noninvasive method of imaging islet β cells and extrapancreatic activity of the insulin gene in the liver under normal and pathological conditions.

  1. The effects of two-week program of individually measured physical activity on insulin resistance in obese non-insulin-dependent diabetes mellitus

    Čizmić Milica

    2003-01-01

    Full Text Available It is well known that under the influence of regular, individually measured aerobic physical activity, it is possible to raise the biological efficiency of insulin by several mechanisms: by increasing the number of insulin receptors, their sensitivity and efficiency, as well as by increasing glucose transporters GLUT-4 on the level of cell membrane. The aim of this research was to examine whether decreased insulin resistance could be achieved under the influence of the program of individually measured aerobic physical activity in the 2-week period, in the obese type 2 diabetes patients with the increased aerobic capacity (VO2max. In 10 type 2 diabetes patients 47.6 ± 4.6 years of age (group E, in the 14-days period, program of aerobic training was applied (10 sessions - 35 min session of walking on treadmill, intensity 60.8 ± 5.7% (VO2max, frequency 5 times a week , as well as 1 600 kcal diet. At the same time, other 10 type 2 diabetes patients 45.9 ± 5.5 years of age (group C were on 1 600 kcal diet. Before and after this period the following was measured in both groups: insulin sensitivity (M/I by the method of hyperinsulin euglycemic clamp, and (VO2max by Astrand test on ergocycle. In contrast to the group C, in the second testing of E group subjects a significant increase was obtained in M/I (1.23 ± 0.78 vs. 2.42 ± 0.95 mg/kg/min/mU p<0.001, 96.75% as well as the increase of (VO2max (26.34 ± 4.26 vs. 29.16 ± 5.01 ml/kg/min p<0.05, 10.7%. The results had shown that 2-week program of aerobic training had had significant influence on the increased aerobic capacity and insulin sensitivity in the tested patients.

  2. Insulin Secretagogues

    ... Your Body in Balance › Insulin Secretagogues Fact Sheet Insulin Secretagogues March, 2012 Download PDFs English Espanol Editors ... medicines can help you stay healthy. What are insulin secretagogues? Insulin secretagogues (pronounced seh-KREET-ah-gogs) ...

  3. Krüppel-like factor 14 increases insulin sensitivity through activation of PI3K/Akt signal pathway.

    Yang, Min; Ren, Yan; Lin, Zhimin; Tang, Chenchen; Jia, Yanjun; Lai, Yerui; Zhou, Tingting; Wu, Shaobo; Liu, Hua; Yang, Gangyi; Li, Ling

    2015-11-01

    Genome-wide association studies (GWAS) have shown that Krüppel-like factor 14 (KLF14) is associated with type 2 diabetes mellitus (T2DM). However, no report has demonstrated a relationship between KLF14 and glucose metabolism. The aim of this study was to determine whether KLF14 is associated with glucose metabolism and insulin signaling in vitro. The mRNA and protein expressions of KLF14 were determined by Real-time PCR and Western blotting. Glucose uptake was assessed by 2-[(3)H]-deoxyglucose (2-DG) uptake. Western blotting was used to identify the activation of insulin signaling proteins. KLF14 mRNA and protein in fat and muscle were significantly decreased in HFD-fed mice, db/db mice and T2DM patients. Overexpression of KLF14 enhanced insulin-stimulated glucose uptake and the activation of Akt kinase in Hepa1-6 cells. The phosphorylation of insulin receptor (InsR), insulin receptor substrate-1(IRS-1), glycogen synthase kinase-3β (GSK-3β) and Akt also elevated significantly by up-regulation of KLF14. KLF14 overexpression in Hepa1-6 cells prevented the inhibition of glucose uptake and Akt phosphorylation induced by high glucose and/or high insulin, or T2DM serum. However, KLF14's ability to increase glucose uptake and Akt activation was significantly attenuated by LY294002, a PI3-kinase inhibitor. These data suggested that KLF14 could increase insulin sensitivity probably through the PI3K/Akt pathway. PMID:26226221

  4. TM-25659-Induced Activation of FGF21 Level Decreases Insulin Resistance and Inflammation in Skeletal Muscle via GCN2 Pathways.

    Jung, Jong Gab; Yi, Sang-A; Choi, Sung-E; Kang, Yup; Kim, Tae Ho; Jeon, Ja Young; Bae, Myung Ae; Ahn, Jin Hee; Jeong, Hana; Hwang, Eun Sook; Lee, Kwan-Woo

    2015-12-01

    The TAZ activator 2-butyl-5-methyl-6-(pyridine-3-yl)-3-[2'-(1H-tetrazole-5-yl)-biphenyl-4-ylmethyl]-3H-imidazo[4,5-b]pyridine] (TM-25659) inhibits adipocyte differentiation by interacting with peroxisome proliferator-activated receptor gamma. TM-25659 was previously shown to decrease weight gain in a high fat (HF) diet-induced obesity (DIO) mouse model. However, the fundamental mechanisms underlying the effects of TM-25659 remain unknown. Therefore, we investigated the effects of TM-25659 on skeletal muscle functions in C2 myotubes and C57BL/6J mice. We studied the molecular mechanisms underlying the contribution of TM-25659 to palmitate (PA)-induced insulin resistance in C2 myotubes. TM-25659 improved PA-induced insulin resistance and inflammation in C2 myotubes. In addition, TM-25659 increased FGF21 mRNA expression, protein levels, and FGF21 secretion in C2 myotubes via activation of GCN2 pathways (GCN2-phosphoeIF2α-ATF4 and FGF21). This beneficial effect of TM-25659 was diminished by FGF21 siRNA. C57BL/6J mice were fed a HF diet for 30 weeks. The HF-diet group was randomly divided into two groups for the next 14 days: the HF-diet and HF-diet + TM-25659 groups. The HF diet + TM-25659-treated mice showed improvements in their fasting blood glucose levels, insulin sensitivity, insulin-stimulated Akt phosphorylation, and inflammation, but neither body weight nor food intake was affected. The HF diet + TM-25659-treated mice also exhibited increased expression of both FGF21 mRNA and protein. These data indicate that TM-25659 may be beneficial for treating insulin resistance by inducing FGF21 in models of PA-induced insulin resistance and HF diet-induced insulin resistance. PMID:26537193

  5. Implications of compound heterozygous insulin receptor mutations in congenital muscle fibre type disproportion myopathy for the receptor kinase activation

    Klein, H H; Müller, R; Vestergaard, H;

    1999-01-01

    We studied insulin receptor kinase activation in two brothers with congenital muscle fibre type disproportion myopathy and compound heterozygous mutations of the insulin receptor gene, their parents, and their unaffected brother. In the father who has a heterozygote Arg1174-->Gln mutation, in situ...... receptors to become insulin-dependently activated. The mother carries a point mutation at the last base pair in exon 17 which, due to abnormal alternative splicing, could lead to normally transcribed receptor or truncated receptor lacking the kinase region. Kinase activation was normal in the mother...... receptors in the mother's skeletal muscle are transcribed almost exclusively from the non-mutated allele. The mutation in exon 17 could lead to reduced transcription or rapid degradation of a predominantly transcribed truncated gene product or both....

  6. Activation of transmembrane bile acid receptor TGR5 stimulates insulin secretion in pancreatic {beta} cells

    Kumar, Divya P.; Rajagopal, Senthilkumar; Mahavadi, Sunila [Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA (United States); Mirshahi, Faridoddin [Division of Gastroenterology, Hepatology and Nutrition, Department of Internal Medicine, Virginia Commonwealth University School of Medicine, Richmond, VA (United States); Grider, John R. [Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA (United States); Murthy, Karnam S., E-mail: skarnam@vcu.edu [Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA (United States); Sanyal, Arun J., E-mail: asanyal@mcvh-vcu.edu [Division of Gastroenterology, Hepatology and Nutrition, Department of Internal Medicine, Virginia Commonwealth University School of Medicine, Richmond, VA (United States)

    2012-10-26

    Highlights: Black-Right-Pointing-Pointer G protein coupled receptor TGR5 is expressed in mouse and human islets. Black-Right-Pointing-Pointer TGR5 is coupled to activation of Gs and Ca{sup 2+} release via cAMP/Epac/PLC-{epsilon} pathway. Black-Right-Pointing-Pointer Activation of TGR5 by bile salts and selective ligands causes insulin secretion. Black-Right-Pointing-Pointer TGR5 could be a potential therapeutic target to treat diabetes. -- Abstract: Bile acids act as signaling molecules and stimulate the G protein coupled receptor, TGR5, in addition to nuclear farnesoid X receptor to regulate lipid, glucose and energy metabolism. Bile acid induced activation of TGR5 in the enteroendocrine cells promotes glucagon like peptide-1 (GLP-1) release, which has insulinotropic effect in the pancreatic {beta} cells. In the present study, we have identified the expression of TGR5 in pancreatic {beta} cell line MIN6 and also in mouse and human pancreatic islets. TGR5 selective ligands, oleanolic acid (OA) and INT-777 selectively activated G{alpha}{sub s} and caused an increase in intracellular cAMP and Ca{sup 2+}. OA and INT-777 also increased phosphoinositide (PI) hydrolysis and the increase was blocked by NF449 (a selective G{alpha}{sub s} inhibitor) or (U73122) (PI hydrolysis inhibitor). OA, INT-777 and lithocholic acid increased insulin release in MIN6 and human islets and the increase was inhibited by treatment with NF449, (U73122) or BAPTA-AM (chelator of calcium), but not with myristoylated PKI (PKA inhibitor), suggesting that the release is dependent on G{sub s}/cAMP/Ca{sup 2+} pathway. 8-pCPT-2 Prime -O-Me-cAMP, a cAMP analog, which activates Epac, but not PKA also stimulated PI hydrolysis. In conclusion, our study demonstrates that the TGR5 expressed in the pancreatic {beta} cells regulates insulin secretion and highlights the importance of ongoing therapeutic strategies targeting TGR5 in the control of glucose homeostasis.

  7. COPD exacerbations · 1: Epidemiology

    Donaldson, G C; Wedzicha, J A

    2006-01-01

    The epidemiology of exacerbations of chronic obstructive pulmonary disease (COPD) is reviewed with particular reference to the definition, frequency, time course, natural history and seasonality, and their relationship with decline in lung function, disease severity and mortality. The importance of distinguishing between recurrent and relapsed exacerbations is discussed.

  8. Melanocortin-4 receptor activation inhibits c-Jun N-terminal kinase activity and promotes insulin signaling

    Chai, Biaoxin; Li, Ji-Yao; Zhang, Weizhen; Wang, Hui; Mulholland, Michael W.

    2009-01-01

    The melanocortin system is crucial to regulation of energy homeostasis. The melanocortin receptor type 4 (MC4R) modulates insulin signaling via effects on c-Jun N-terminal kinase (JNK). The melanocortin agonist NDP-MSH dose-dependently inhibited JNK activity in HEK293 cells stably expressing the human MC4R; effects were reversed by melanocortin receptor antagonist. NDP-MSH time- and dose-dependently inhibited IRS-1ser307 phosphorylation, effects also reversed by a specific melanocortin recept...

  9. Exogenous progesterone exacerbates running response of adolescent female mice to repeated food restriction stress by changing α4-GABAA receptor activity of hippocampal pyramidal cells.

    Wable, G S; Chen, Y-W; Rashid, S; Aoki, C

    2015-12-01

    Adolescent females are particularly vulnerable to mental illnesses with co-morbidity of anxiety, such as anorexia nervosa (AN). We used an animal model of AN, called activity-based anorexia (ABA), to investigate the neurobiological basis of vulnerability to repeated, food restriction (FR) stress-evoked anxiety. Twenty-one of 23 adolescent female mice responded to the 1st FR with increased wheel-running activity (WRA), even during the limited period of food access, thereby capturing AN's symptoms of voluntary FR and over-exercise. Baseline WRA was an excellent predictor of FR-elicited WRA (severity of ABA, SOA), with high baseline runners responding to FR with minimal SOA (i.e., negative correlation). Nine gained resistance to ABA following the 1st FR. Even though allopregnanolone (3α-OH-5α-pregnan-20-one, THP), the metabolite of progesterone (P4), is a well-recognized anxiolytic agent, subcutaneous P4 to these ABA-resistant animals during the 2nd FR was exacerbative, evoking greater WRA than the counterpart resistant group that received oil vehicle, only. Moreover, P4 had no WRA-reducing effect on animals that remained ABA-vulnerable. To explain the sensitizing effect of P4 upon the resistant mice, we examined the relationship between P4 treatment and levels of the α4 subunit of GABAARs at spines of pyramidal cells of the hippocampal CA1, a parameter previously shown to correlate with resistance to ABA. α4 levels at spine membrane correlated strongly and negatively with SOA during the 1st ABA (prior to P4 injection), confirming previous findings. α4 levels were greater among P4-treated animals that had gained resistance than of vehicle-treated resistant animals or of the vulnerable animals with or without P4. We propose that α4-GABAARs play a protective role by counterbalancing the ABA-induced increase in excitability of CA1 pyramidal neurons, and although exogenous P4's metabolite, THP, enhances α4 expression, especially among those that can gain resistance

  10. The association of intensity and overall level of physical activity energy expenditure with a marker of insulin resistance

    Assah, F. K.; Brage, S.; Wareham, N. J.

    2008-01-01

    Aims/hypothesis Physical activity is important in preventing insulin resistance, but it is unclear which dimension of activity confers this benefit. We examined the association of overall level and intensity of physical activity with fasting insulin level, a marker of insulin resistance. Methods This was a cross-sectional analysis of the Medical Research Council Ely population-based cohort study (2000–2002). Physical activity energy expenditure (PAEE) in kJ kg−1 min−1 was measured by heart rate monitoring with individual calibration over a period of 4 days. The percentage of time spent above 1.5, 1.75 and 2 times resting heart rate (RHR) represented all light-to-vigorous, moderate-to-vigorous and vigorous activity, respectively. Results Data from a total of 643 non-diabetic individuals (319 men, 324 women) aged 50 to 75 years were analysed. In multivariate linear regression analyses, adjusting for age, sex and body fat percentage, PAEE was significantly associated with fasting insulin (pmol/l) (β = −0.875, p = 0.006). Time (% of total) spent above 1.75 × RHR and also time spent above 2 × RHR were both significantly associated with fasting insulin (β = −0.0109, p = 0.007 and β = −0.0365, p = 0.001 respectively), after adjusting for PAEE, age, sex and body fat percentage. Time spent above 1.5 × RHR was not significantly associated with fasting insulin in a similar model (β = −0.0026, p = 0.137). Conclusions/interpretation The association between PAEE and fasting insulin level, a marker of insulin resistance, may be attributable to the time spent in moderate-to-vigorous and vigorous activity, but not to time spent in light-intensity physical activity. PMID:18488189

  11. Triterpenoid Saponins from Stauntonia chinensis Ameliorate Insulin Resistance via the AMP-Activated Protein Kinase and IR/IRS-1/PI3K/Akt Pathways in Insulin-Resistant HepG2 Cells

    Xin Hu; Sha Wang; Jing Xu; De-Bing Wang; Yu Chen; Guang-Zhong Yang

    2014-01-01

    Inflammation and oxidative stress play crucial roles in the etiology of type 2 diabetes mellitus. In this study, we examined the anti-diabetic effects of triterpenoid saponins extracted from Stauntonia chinensis on stimulating glucose uptake by insulin-resistant human HepG2 cells. The results showed that saponin 6 significantly increased glucose uptake and glucose catabolism. Saponin 6 also enhanced the phosphorylation of AMP-activated protein kinase (AMPK) and activated the insulin receptor...

  12. Insulin glulisine: insulin receptor signaling characteristics in vivo.

    Hennige, Anita M; Lehmann, Rainer; Weigert, Cora; Moeschel, Klaus; Schäuble, Myriam; Metzinger, Elisabeth; Lammers, Reiner; Häring, Hans-Ulrich

    2005-02-01

    In recent years, recombinant DNA technology has been used to design insulin molecules that overcome the limitations of regular insulin in mealtime supplementation. However, safety issues have been raised with these alternatives, as the alteration of the three-dimensional structure may alter the interaction with the insulin and/or IGF-I receptors and therefore lead to the activation of alternate metabolic as well as mitogenic signaling pathways. It is therefore essential to carefully study acute and long-term effects in a preclinical state, as insulin therapy is meant to be a lifelong treatment. In this study, we determined in vivo the insulin receptor signaling characteristics activated by insulin glulisine (Lys(B3), Glu(B29)) at the level of insulin receptor phosphorylation, insulin receptor substrate phosphorylation, and downstream signaling elements such as phosphatidylinositol (PI) 3-kinase, AKT, and mitogen-activated protein kinase. C57BL/6 mice were injected with insulin glulisine or regular insulin and Western blot analysis was performed for liver and muscle tissue. The extent and time course of insulin receptor phosphorylation and activation of downstream signaling elements after insulin glulisine treatment was similar to that of human regular insulin in vivo. Moreover, insulin signaling in hypothalamic tissue determined by PI 3-kinase activity was comparable. Therefore, insulin glulisine may be a useful tool for diabetes treatment. PMID:15677493

  13. Insulin alters cAMP-activated lipolysis but not cAMP-inhibited glycogen synthase in permeabilized adipocytes

    Lipolysis and, to a lesser extent, glycogen synthase activity are regulated in adipocytes by cellular cAMP and counter-regulated by insulin. These activities were measured in situ in digitonin (20 μg/ml) permeabilized rat adipocytes. Incorporation of 3H UDP-glucose into endogenous glycogen in the presence of KF, EDTA and 10mM glucose-6-phosphate was the basis of the G.S. assay. Cellular GS activity determined by this technique was 1.4 +/- 0.2 fold greater than that of matched homogenates. Insulin treatment of intact cells prior to permeabilization increased GS activity ratio (-/+ G-6-P) 2.5 fold when subsequently measured by the in situ assay. Following digitonin permeabilization, addition of cAMP to the suspension medium increased lipolysis 7 fold and decreased GS activity ratio to 0.38 +/- 0.01 from a basal value of 0.44 +/- 0.06. ATP had a negligible effect on lipolysis but decreased GS to 0.16 +/- 0.04. ATP plus cAMP was only slightly more effective on GS than ATP alone. Insulin at 10-9M inhibited cAMP-dependent lipolysis by 27% but had no effect on the cAMP- or ATP-dependent decrease in GS. These results suggest that insulin's counter-regulatory mechanisms on these two cAMP-dependent processes may be different

  14. Insulin alters cAMP-activated lipolysis but not cAMP-inhibited glycogen synthase in permeabilized adipocytes

    Mooney, R.A.; Wisniewski, J.L.

    1986-05-01

    Lipolysis and, to a lesser extent, glycogen synthase activity are regulated in adipocytes by cellular cAMP and counter-regulated by insulin. These activities were measured in situ in digitonin (20 ..mu..g/ml) permeabilized rat adipocytes. Incorporation of /sup 3/H UDP-glucose into endogenous glycogen in the presence of KF, EDTA and 10mM glucose-6-phosphate was the basis of the G.S. assay. Cellular GS activity determined by this technique was 1.4 +/- 0.2 fold greater than that of matched homogenates. Insulin treatment of intact cells prior to permeabilization increased GS activity ratio (-/+ G-6-P) 2.5 fold when subsequently measured by the in situ assay. Following digitonin permeabilization, addition of cAMP to the suspension medium increased lipolysis 7 fold and decreased GS activity ratio to 0.38 +/- 0.01 from a basal value of 0.44 +/- 0.06. ATP had a negligible effect on lipolysis but decreased GS to 0.16 +/- 0.04. ATP plus cAMP was only slightly more effective on GS than ATP alone. Insulin at 10/sup -9/M inhibited cAMP-dependent lipolysis by 27% but had no effect on the cAMP- or ATP-dependent decrease in GS. These results suggest that insulin's counter-regulatory mechanisms on these two cAMP-dependent processes may be different.

  15. Electroacupuncture-Induced Cholinergic Nerve Activation Enhances the Hypoglycemic Effect of Exogenous Insulin in a Rat Model of Streptozotocin-Induced Diabetes

    Yu-Chen Lee

    2011-01-01

    Full Text Available The aim of this study is to explore the mechanisms by which electroacupuncture (EA enhances the hypoglycemic effect of exogenous insulin in a streptozotocin- (STZ- diabetic rats. Animals in the EA group were anesthetized and subjected to the insulin challenge test (ICT and EA for 60 minutes. In the control group, rats were subjected to the same treatment with the exception of EA stimulation. Blood samples were drawn to measure changes in plasma glucose, free fatty acids (FFA, and insulin levels. Western blot was used to assay proteins involved in insulin signaling. Furthermore, atropine, hemicholinium-3 (HC-3, and Eserine were used to explore the relationship between EA and cholinergic nerve activation during ICT. EA augmented the blood glucose-lowering effects of EA by activating the cholinergic nerves in STZ rats that had been exposed to exogenous insulin. This phenomenon may be related to enhancement of insulin signaling rather than to changes in FFA concentration.

  16. TRPV1 Activation Exacerbates Hypoxia/Reoxygenation-Induced Apoptosis in H9C2 Cells via Calcium Overload and Mitochondrial Dysfunction

    Zewei Sun; Jie Han; Wenting Zhao; Yuanyuan Zhang; Shuai Wang; Lifang Ye; Tingting Liu; Liangrong Zheng

    2014-01-01

    Transient potential receptor vanilloid 1 (TRPV1) channels, which are expressed on sensory neurons, elicit cardioprotective effects during ischemia reperfusion injury by stimulating the release of neuropeptides, namely calcitonin gene-related peptide (CGRP) and substance P (SP). Recent studies show that TRPV1 channels are also expressed on cardiomyocytes and can exacerbate air pollutant-induced apoptosis. However, whether these channels present on cardiomyocytes directly modulate cell death a...

  17. Total and free insulin-like growth factor I, insulin-like growth factor binding protein 3 and acid-labile subunit reflect clinical activity in acromegaly

    Sneppen, S B; Lange, Merete Wolder; Pedersen, L M;

    2001-01-01

    insulin-like growth factor binding protein-3 (IGFBP-3) with PV(pos) of 0.69 and 0.71 and PV(neg) of 0.91 and 0.92 respectively. We conclude that free IGF-I is more closely related than total IGF-I to perceived disease activity and is as such useful when evaluating previously treated acromegaly for disease...... activity. Total IGF-I, IGFBP-3 and ALS possess a higher PV(neg) for the clinical disease activity. None of the parameters can at present be claimed to be superior to the others and thus all the measured parameters are recommended to be part of the evaluation of acromegalic patients....

  18. Dietary Fructose Activates Insulin Signaling and Inflammation in Adipose Tissue: Modulatory Role of Resveratrol

    Mehmet Bilgehan Pektas; Halit Bugra Koca; Gokhan Sadi; Fatma Akar

    2016-01-01

    The effects of high-fructose diet on adipose tissue insulin signaling and inflammatory process have been poorly documented. In this study, we examined the influences of long-term fructose intake and resveratrol supplementation on the expression of genes involved in insulin signaling and the levels of inflammatory cytokines and sex hormones in the white adipose tissues of male and female rats. Consumption of high-fructose diet for 24 weeks increased the expression of genes involved in insulin ...

  19. Cyanidin-3-O-β-Glucoside and Protocatechuic Acid Exert Insulin-Like Effects by Upregulating PPARγ Activity in Human Omental Adipocytes

    Scazzocchio, Beatrice; Varì, Rosaria; Filesi, Carmelina; D’Archivio, Massimo; Santangelo, Carmela; Giovannini, Claudio; Iacovelli, Annunziata; Silecchia, Gianfranco; Volti, Giovanni Li; Galvano, Fabio; Masella, Roberta

    2011-01-01

    OBJECTIVE Insulin resistance (IR) represents an independent risk factor for metabolic, cardiovascular, and neoplastic disorders. Preventing/attenuating IR is a major objective to be reached to preserve population health. Because many insulin-sensitizing drugs have shown unwanted side effects, active harmless compounds are sought after. Dietary anthocyanins have been demonstrated to ameliorate hyperglycemia and insulin sensitivity. This study aimed at investigating whether cyanidin-3-O-β-gluco...

  20. A superactive insulin: [B10-aspartic acid]insulin(human).

    Schwartz, G P; Burke, G. T.; Katsoyannis, P G

    1987-01-01

    The genetic basis for a case of familial hyperproinsulinemia has been elucidated recently. It involves a single point mutation in the proinsulin gene resulting in the substitution of aspartic acid for histidine-10 of the B chain of insulin. We have synthesized a human insulin analogue, [AspB10]insulin, corresponding to the mutant proinsulin and evaluated its biological activity. [AspB10]Insulin displayed a binding affinity to insulin receptors in rat liver plasma membranes that was 534 +/- 14...

  1. NKX3.1 activates expression of insulin-like growth factor binding protein-3 to mediate insulin-like growth factor-I signaling and cell proliferation.

    Muhlbradt, Erin; Asatiani, Ekaterina; Ortner, Elizabeth; Wang, Antai; Gelmann, Edward P

    2009-03-15

    NKX3.1 is a homeobox gene that codes for a haploinsufficient prostate cancer tumor suppressor. NKX3.1 protein levels are down-regulated in the majority of primary prostate cancer tissues. NKX3.1 expression in PC-3 cells increased insulin-like growth factor binding protein-3 (IGFBP-3) mRNA expression 10-fold as determined by expression microarray analysis. In both stably and transiently transfected PC-3 cells and in LNCaP cells, NKX3.1 expression increased IGFBP-3 mRNA and protein expression. In prostates of Nkx3.1 gene-targeted mice Igfbp-3 mRNA levels correlated with Nkx3.1 copy number. NKX3.1 expression in PC-3 cells attenuated the ability of insulin-like growth factor-I (IGF-I) to induce phosphorylation of type I IGF receptor (IGF-IR), insulin receptor substrate 1, phosphatidylinositol 3-kinase, and AKT. The effect of NKX3.1 on IGF-I signaling was not seen when cells were exposed to long-R3-IGF-I, an IGF-I variant peptide that does not bind to IGFBP-3. Additionally, small interfering RNA-induced knockdown of IGFBP-3 expression partially reversed the attenuation of IGF-IR signaling by NKX3.1 and abrogated NKX3.1 suppression of PC-3 cell proliferation. Thus, there is a close relationship in vitro and in vivo between NKX3.1 and IGFBP-3. The growth-suppressive effects of NKX3.1 in prostate cells are mediated, in part, by activation of IGFBP-3 expression. PMID:19258508

  2. Intravenous tissue plasminogen activator in patients with stroke increases the bioavailability of insulin-like growth factor-1

    Wilczak, Nadine; Elting, Jan Willem; Chesik, Daniel; Kema, Ido P.; De Keyser, Jacques

    2006-01-01

    Background and Purpose-Insulin-like growth factor (IGF)-1 has potent neuroprotective properties. We investigated the effects of intravenous administration of tissue plasminogen activator (tPA) on serum levels of IGF-1 and IGF-binding protein (IGFBP)-3 in patients with acute ischemic stroke. Methods-

  3. Lifelong Physical Activity Prevents Aging-Associated Insulin Resistance in Human Skeletal Muscle Myotubes via Increased Glucose Transporter Expression

    Bunprajun, Tipwadee; Henriksen, Tora Ida; Scheele, Camilla; Pedersen, Bente Klarlund; Green, Charlotte Jane

    2013-01-01

    significantly higher GLUT4 protein. It is likely that physical activity induces a number of stable adaptations, including increased GLUT4 expression that are retained in cells ex vivo and protect, or delay the onset of middle-aged-associated insulin resistance. Additionally, a sedentary lifestyle has an impact...

  4. Ultrastructure of the liver microcirculation influences hepatic and systemic insulin activity and provides a mechanism for age-related insulin resistance.

    Mohamad, Mashani; Mitchell, Sarah Jayne; Wu, Lindsay Edward; White, Melanie Yvonne; Cordwell, Stuart James; Mach, John; Solon-Biet, Samantha Marie; Boyer, Dawn; Nines, Dawn; Das, Abhirup; Catherine Li, Shi-Yun; Warren, Alessandra; Hilmer, Sarah Nicole; Fraser, Robin; Sinclair, David Andrew; Simpson, Stephen James; de Cabo, Rafael; Le Couteur, David George; Cogger, Victoria Carroll

    2016-08-01

    While age-related insulin resistance and hyperinsulinemia are usually considered to be secondary to changes in muscle, the liver also plays a key role in whole-body insulin handling and its role in age-related changes in insulin homeostasis is largely unknown. Here, we show that patent pores called 'fenestrations' are essential for insulin transfer across the liver sinusoidal endothelium and that age-related loss of fenestrations causes an impaired insulin clearance and hyperinsulinemia, induces hepatic insulin resistance, impairs hepatic insulin signaling, and deranges glucose homeostasis. To further define the role of fenestrations in hepatic insulin signaling without any of the long-term adaptive responses that occur with aging, we induced acute defenestration using poloxamer 407 (P407), and this replicated many of the age-related changes in hepatic glucose and insulin handling. Loss of fenestrations in the liver sinusoidal endothelium is a hallmark of aging that has previously been shown to cause deficits in hepatic drug and lipoprotein metabolism and now insulin. Liver defenestration thus provides a new mechanism that potentially contributes to age-related insulin resistance. PMID:27095270

  5. COPD exacerbations, inflammation and treatment

    Bathoorn, Derk

    2007-01-01

    This thesis describes investigations into the inflammation in COPD, and its treatment. Inflammation in COPD is a central factor in the onset of the disease and its progression. During acute deteriorations of the disease, exacerbations, the inflammation is more severe, and depending on the cause of the exacerbation, it has a different pattern. To date, it has been difficult to efficiently suppress this inflammation, and the anti-inflammatory treatment currently so far has considerable side eff...

  6. Signal Transducer and Activator of Transcription (Stat)-Induced Stat Inhibitor 1 (Ssi-1)/Suppressor of Cytokine Signaling 1 (Socs1) Inhibits Insulin Signal Transduction Pathway through Modulating Insulin Receptor Substrate 1 (Irs-1) Phosphorylation

    Kawazoe, Yoshinori; Naka, Tetsuji; Fujimoto, Minoru; Kohzaki, Hidetsugu; Morita, Yoshiaki; Narazaki, Masashi; Okumura, Kohichi; Saitoh, Hiroshi; Nakagawa, Reiko; Uchiyama, Yasuo; Akira, Shizuo; Kishimoto, Tadamitsu

    2001-01-01

    Signal transducer and activator of transcription (STAT)-induced STAT inhibitor 1 (SSI-1) is known to function as a negative feedback regulator of cytokine signaling, but it is unclear whether it is involved in other biological events. Here, we show that SSI-1 participates and plays an important role in the insulin signal transduction pathway. SSI-1–deficient mice showed a significantly low level of blood sugar. While the forced expression of SSI-1 reduced the phosphorylation level of insulin ...

  7. Structure, antihyperglycemic activity and cellular actions of a novel diglycated human insulin

    O'Harte, F P; Boyd, A C; McKillop, A M;

    2000-01-01

    Human insulin was glycated under hyperglycemic reducing conditions and a novel diglycated form (M(r) 6135.1 Da) was purified by RP-HPLC. Endoproteinase Glu-C digestion combined with mass spectrometry and automated Edman degradation localized glycation to Gly(1) and Phe(1) of the insulin A- and B...

  8. Central GLP-2 enhances hepatic insulin sensitivity via activating PI3K signaling in POMC neurons

    Glucagon-like peptides (GLP-1/GLP-2) are coproduced and highlighted as key modulators to improve glucose homeostasis and insulin sensitivity after bariatric surgery. However, it is unknown if CNS GLP-2 plays any physiological role in the control of glucose homeostasis and insulin sensitivity. We sho...

  9. Acute exacerbations of chronic obstructive pulmonary disease: causes and impacts.

    Chhabra, Sunil K; Dash, Devi Jyoti

    2014-01-01

    Acute exacerbations of chronic obstructive pulmonary disease (AECOPD) are recognised clinically as episodes of increased breathlessness and productive cough requiring a more intensive treatment. A subset of patients with this disease is especially prone to such exacerbations. These patients are labelled as 'frequent exacerbators'. Though yet poorly characterised in terms of host characteristics, including any genetic basis, these patients are believed to represent a distinct phenotype as they have a different natural history with a more progressive disease and a poorer prognosis than those who get exacerbations infrequently. Most exacerbations appear to be associated with infective triggers, either bacterial or viral, although 'non-infective' agents, such as air pollution and other irritants may also be important. Susceptibility to exacerbations is determined by multiple factors. Several risk factors have been identified, some of which are modifiable. Chronic obstructive pulmonary disease (COPD) exacerbations are major drivers of health status and patient-centered outcomes, and are a major reason for health care utilisation including hospitalisations and intensive care admissions. These are associated with considerable morbidity and mortality, both immediate and long-term. These episodes have a negative impact on the patient and the disease including high economic burden, increased mortality, worsening of health status, limitation of activity, and aggravation of comorbidities including cardiovascular disease, osteoporosis and neuro-psychiatric complications. Exacerbations also increase the rate of progression of disease, increasing the annual decline in lung function and leading to a poorer prognosis. Evaluation of risk of exacerbations is now included as a major component of the initial assessment of a patient with COPD in addition to the traditionally used lung function parameter, forced expiratory volume in one second (FEV1). Decreasing the risk of exacerbations

  10. Insulin Test

    ... especially as a result of taking non-human (animal or synthetic) insulin, these can interfere with insulin testing. In this case, a C-peptide may be performed as an alternative way to evaluate insulin production. Note also that ...

  11. Fibronectin and laminin promote differentiation of human mesenchymal stem cells into insulin producing cells through activating Akt and ERK

    Chiou Shih-Hwa

    2010-07-01

    Full Text Available Abstract Background Islet transplantation provides a promising cure for Type 1 diabetes; however it is limited by a shortage of pancreas donors. Bone marrow-derived multipotent mesenchymal stem cells (MSCs offer renewable cells for generating insulin-producing cells (IPCs. Methods We used a four-stage differentiation protocol, containing neuronal differentiation and IPC-conversion stages, and combined with pellet suspension culture to induce IPC differentiation. Results Here, we report adding extracellular matrix proteins (ECM such as fibronectin (FN or laminin (LAM enhances pancreatic differentiation with increases in insulin and Glut2 gene expressions, proinsulin and insulin protein levels, and insulin release in response to elevated glucose concentration. Adding FN or LAM induced activation of Akt and ERK. Blocking Akt or ERK by adding LY294002 (PI3K specific inhibitor, PD98059 (MEK specific inhibitor or knocking down Akt or ERK failed to abrogate FN or LAM-induced enhancement of IPC differentiation. Only blocking both of Akt and ERK or knocking down Akt and ERK inhibited the enhancement of IPC differentiation by adding ECM. Conclusions These data prove IPC differentiation by MSCs can be modulated by adding ECM, and these stimulatory effects were mediated through activation of Akt and ERK pathways.

  12. Endoplasmic Reticulum Stress-Induced Activation of Activating Transcription Factor 6 Decreases Insulin Gene Expression via Up-Regulation of Orphan Nuclear Receptor Small Heterodimer Partner

    Seo, Hye-Young; Kim, Yong Deuk; Lee, Kyeong-Min; Min, Ae-Kyung; Kim, Mi-Kyung; Kim, Hye-Soon; Won, Kyu-Chang; Park, Joong-Yeol; Lee, Ki-Up; Choi, Hueng-Sik; Park, Keun-Gyu; Lee, In-Kyu

    2008-01-01

    The highly developed endoplasmic reticulum (ER) structure of pancreatic β-cells is a key factor in β-cell function. Here we examined whether ER stress-induced activation of activating transcription factor (ATF)-6 impairs insulin gene expression via up-regulation of the orphan nuclear receptor small heterodimer partner (SHP; NR0B2), which has been shown to play a role in β-cell dysfunction. We examined whether ER stress decreases insulin gene expression, and this process is mediated by ATF6. A...

  13. Objectively Measured Sedentary Time May Predict Insulin Resistance Independent of Moderate- and Vigorous-Intensity Physical Activity

    Helmerhorst, Hendrik J. F.; Wijndaele, Katrien; Brage, Søren; Wareham, Nicholas J.; Ekelund, Ulf

    2009-01-01

    OBJECTIVE To examine the prospective association between objectively measured time spent sedentary and insulin resistance and whether this association is independent of moderate- and vigorous-intensity physical activity (MVPA) and other relevant confounders. RESEARCH DESIGN AND METHODS This was a population-based study (Medical Research Council Ely study) in 376 middle-aged adults (166 men; 210 women) over 5.6 years of follow-up. Physical activity and sedentary time were measured objectively ...

  14. INSULIN ANALOGUES: ANALYSIS OF PROLIFERATIVE POTENCY AND CHARACTERIZATION OF RECEPTORS AND SIGNALLING PATHWAYS ACTIVATED IN HUMAN MAMMARY EPITHELIAL CELLS

    Shukla, Ashish

    2009-01-01

    Insulin analogues have been developed with the aim to provide better glycaemic control to diabetic patients. They are generated by modifying the insulin backbone which, however, may alter relevant biochemical characteristics such as the affinity to insulin receptor and type I insulin-like growth factor receptor (IGF-IR), and the insulin receptor dissociation rate. As a result insulin analogues may exhibit stronger mitogenic potency than regular insulin. Normal mammary epithelial cells show hi...

  15. Insulin analogs and cancer

    Laura eSciacca

    2012-02-01

    Full Text Available Today, insulin analogs are used in millions of diabetic patients. Insulin analogs have been developed to achieve more physiological insulin replacement in terms of time course of the effect. Modifications in the amino acid sequence of the insulin molecule change the pharmacokinetics and pharmacodynamics of the analogs in respect to human insulin. However, these changes can also modify the molecular and biological effects of the analogs. The rapid-acting insulin analogs, lispro, aspart and glulisine, have a rapid onset and shorter duration of action. The long-acting insulin analogs glargine and detemir have a protracted duration of action and a relatively smooth serum concentration profile. Insulin and its analogs may function as growth factors and therefore have a theoretical potential to promote tumor proliferation. A major question is whether analogs have an increased mitogenic activity in respect to insulin. These ligands can promote cell proliferation through many mechanisms like the prolonged stimulation of the insulin receptor, stimulation of the IGF-1 receptor (IGF-1R, prevalent activation of the ERK rather than the AKT intracellular post-receptor pathways. Studies on in vitro models indicate that short-acting analogs elicit molecular and biological effects that are similar to those of insulin. In contrast, long-acting analogs behave differently. Although not all data are homogeneous, both glargine and detemir have been found to have a decreased binding to IR but an increased binding to IGF-1R, a prevalent activation of the ERK pathway, and an increased mitogenic effect in respect to insulin. Recent retrospective epidemiological clinical studies have suggested that treatment with long-acting analogs (specifically glargine may increase the relative risk for cancer. Results are controversial and methodologically weak. Therefore prospective clinical studies are needed to evaluate the possible tumor growth-promoting effects of these insulin

  16. Effect of Insulin Analogues on Insulin/IGF1 Hybrid Receptors: Increased Activation by Glargine but Not by Its Metabolites M1 and M2

    Cécile Pierre-Eugene; Patrick Pagesy; Tuyet Thu Nguyen; Marion Neuillé; Georg Tschank; Norbert Tennagels; Cornelia Hampe; Tarik Issad

    2012-01-01

    BACKGROUND: In diabetic patients, the pharmacokinetics of injected human insulin does not permit optimal control of glycemia. Fast and slow acting insulin analogues have been developed, but they may have adverse properties, such as increased mitogenic or anti-apoptotic signaling. Insulin/IGF1 hybrid receptors (IR/IGF1R), present in most tissues, have been proposed to transmit biological effects close to those of IGF1R. However, the study of hybrid receptors is difficult because of the presenc...

  17. Sustained PI3K Activation exacerbates BLM-induced Lung Fibrosis via activation of pro-inflammatory and pro-fibrotic pathways.

    Kral, Julia Barbara; Kuttke, Mario; Schrottmaier, Waltraud Cornelia; Birnecker, Birgit; Warszawska, Joanna; Wernig, Christina; Paar, Hannah; Salzmann, Manuel; Sahin, Emine; Brunner, Julia Stefanie; Österreicher, Christoph; Knapp, Sylvia; Assinger, Alice; Schabbauer, Gernot

    2016-01-01

    Idiopathic pulmonary fibrosis (IPF) is a life-threatening disease with limited treatment options. Additionally, the lack of a complete understanding of underlying immunological mechanisms underscores the importance of discovering novel options for therapeutic intervention. Since the PI3K/PTEN pathway in myeloid cells influences their effector functions, we wanted to elucidate how sustained PI3K activity induced by cell-type specific genetic deficiency of its antagonist PTEN modulates IPF, in a murine model of bleomycin-induced pulmonary fibrosis (BIPF). We found that myeloid PTEN deficient mice (PTEN(MyKO)), after induction of BIPF, exhibit increased TGF-β1 activation, mRNA expression of pro-collagens and lysyl oxidase as well as augmented collagen deposition compared to wild-type littermates, leading to enhanced morbidity and decreased survival. Analysis of alveolar lavage and lung cell composition revealed that PTEN(MyKO) mice exhibit reduced numbers of macrophages and T-cells in response to bleomycin, indicating an impaired recruitment function. Interestingly, we found dysregulated macrophage polarization as well as elevated expression and release of the pro-fibrotic cytokines IL-6 and TNF-α in PTEN(MyKO) mice during BIPF. This might point to an uncontrolled wound healing response in which the inflammatory as well as tissue repair mechanisms proceed in parallel, thereby preventing resolution and at the same time promoting extensive fibrosis. PMID:26971883

  18. Impaired insulin activation and dephosphorylation of glycogen synthase in skeletal muscle of women with polycystic ovary syndrome is reversed by pioglitazone treatment

    Glintborg, Dorte; Højlund, Kurt; Andersen, Nicoline Resen;

    2008-01-01

    CONTEXT: Insulin resistance is a major risk factor for type 2 diabetes in women with polycystic ovary syndrome (PCOS). The molecular mechanisms underlying reduced insulin-mediated glycogen synthesis in skeletal muscle of patients with PCOS have not been established. SUBJECTS AND METHODS: We...... investigated protein content, activity, and phosphorylation of glycogen synthase (GS) and its major upstream inhibitor, GS kinase (GSK)-3 in skeletal muscle biopsies from 24 PCOS patients (before treatment) and 14 matched control subjects and 10 PCOS patients after 16 wk treatment with pioglitazone. All were...... metabolically characterized by euglycemic-hyperinsulinemic clamps and indirect calorimetry. RESULTS: Reduced insulin-mediated glucose disposal (P < 0.05) was associated with a lower insulin-stimulated GS activity in PCOS patients (P < 0.05), compared with controls. This was, in part, explained by absent insulin...

  19. Hmgcr in the corpus allatum controls sexual dimorphism of locomotor activity and body size via the insulin pathway in Drosophila.

    Yesser Hadj Belgacem

    Full Text Available The insulin signaling pathway has been implicated in several physiological and developmental processes. In mammals, it controls expression of 3-Hydroxy-3-Methylglutaryl CoA Reductase (HMGCR, a key enzyme in cholesterol biosynthesis. In insects, which can not synthesize cholesterol de novo, the HMGCR is implicated in the biosynthesis of juvenile hormone (JH. However, the link between the insulin pathway and JH has not been established. In Drosophila, mutations in the insulin receptor (InR decrease the rate of JH synthesis. It is also known that both the insulin pathway and JH play a role in the control of sexual dimorphism in locomotor activity. In studies here, to demonstrate that the insulin pathway and HMGCR are functionally linked in Drosophila, we first show that hmgcr mutation also disrupts the sexual dimorphism. Similarly to the InR, HMGCR is expressed in the corpus allatum (ca, which is the gland where JH biosynthesis occurs. Two p[hmgcr-GAL4] lines were therefore generated where RNAi was targeted specifically against the HMGCR or the InR in the ca. We found that RNAi-HMGCR blocked HMGCR expression, while the RNAi-InR blocked both InR and HMGCR expression. Each RNAi caused disruption of sexual dimorphism and produced dwarf flies at specific rearing temperatures. These results provide evidence: (i that HMGCR expression is controlled by the InR and (ii that InR and HMGCR specifically in the ca, are involved in the control of body size and sexual dimorphism of locomotor activity.

  20. Proteasome inhibitors, including curcumin, improve pancreatic β-cell function and insulin sensitivity in diabetic mice

    Weisberg, S; Leibel, R; Tortoriello, D V

    2016-01-01

    Background: Type 2 diabetes stems from obesity-associated insulin resistance, and in the genetically susceptible, concomitant pancreatic β-cell failure can occur, which further exacerbates hyperglycemia. Recent work by our group and others has shown that the natural polyphenol curcumin attenuates the development of insulin resistance and hyperglycemia in mouse models of hyperinsulinemic or compensated type 2 diabetes. Although several potential downstream molecular targets of curcumin exist, it is now recognized to be a direct inhibitor of proteasome activity. We now show that curcumin also prevents β-cell failure in a mouse model of uncompensated obesity-related insulin resistance (Leprdb/db on the Kaliss background). Results: In this instance, dietary supplementation with curcumin prevented hyperglycemia, increased insulin production and lean body mass, and prolonged lifespan. In addition, we show that short-term in vivo treatment with low dosages of two molecularly distinct proteasome inhibitors celastrol and epoxomicin reverse hyperglycemia in mice with β-cell failure by increasing insulin production and insulin sensitivity. Conclusions: These studies suggest that proteasome inhibitors may prove useful for patients with diabetes by improving both β-cell function and relieving insulin resistance. PMID:27110686

  1. Glucosamine induces REDD1 to suppress insulin action in retinal Müller cells.

    Moore, Joshua A; Miller, William P; Dennis, Michael D

    2016-05-01

    Resistance to insulin action is a key cause of diabetic complications, yet much remains unknown about the molecular mechanisms that contribute to the defect. Glucose-induced insulin resistance in peripheral tissues such as the retina is mediated in part by the hexosamine biosynthetic pathway (HBP). Glucosamine (GAM), a leading dietary supplement marketed to relieve the discomfort of osteoarthritis, is metabolized by the HBP, and in doing so bypasses the rate-limiting enzyme of the pathway. Thus, exogenous GAM consumption potentially exacerbates the resistance to insulin action observed with diabetes-induced hyperglycemia. In the present study, we evaluated the effect of GAM on insulin action in retinal Müller cells in culture. Addition of GAM to Müller cell culture repressed insulin-induced activation of the Akt/mTORC1 signaling pathway. However, the effect was not recapitulated by chemical inhibition to promote protein O-GlcNAcylation, nor was blockade of O-GlcNAcylation sufficient to prevent the effects of GAM. Instead, GAM induced ER stress and subsequent expression of the protein Regulated in DNA Damage and Development (REDD1), which was necessary for GAM to repress insulin-stimulated phosphorylation of Akt on Thr308. Overall, the findings support a model whereby GAM promotes ER stress in retinal Müller cells, resulting in elevated REDD1 expression and thus resistance to insulin action. PMID:26852666

  2. Exacerbations of asthma during pregnancy

    Ali, Zarqa; Hansen, A V; Ulrik, C S

    2016-01-01

    Asthma is common among pregnant women, and the incidence of asthma exacerbations during pregnancy is high. This literature review provides an overview of the impact of exacerbations of asthma during pregnancy on pregnancy-related complications. The majority of published retrospective studies reveal...... that asthma exacerbations during pregnancy increase the risk of pre-eclampsia, gestational diabetes, placental abruption and placenta praevia. Furthermore, these women also have higher risk for breech presentation, haemorrhage, pulmonary embolism, caesarean delivery, maternal admission to the intensive...... care unit and longer postpartum hospital stay. Asthma has been associated with increased risk of intrauterine growth retardation, small-for-gestational age, low birth weight, infant hypoglycaemia and preterm birth, but more recent prospective studies have not revealed significant associations with...

  3. The importance of apoptotic activity and plasma NT-proBNP levels in patients with acute exacerbation of decompensated heart failure and their relation to different drugs and comorbidities

    Objective: To demonstrate the presence and importance of apoptotic activity in heart failure during acute exacerbations and to investigate the effects of different drugs used and co-morbidities on levels of N-Terminal pro-Brain Natriuretic Peptide and apoptotic activity on admission and during hospitalisation. Methods: The descriptive study was conducted at the emergency department of Istanbul University Cardiology Institute between October 2010 and May 2011 and comprised patients with complaints of shortness of breath, and who were evaluated as acutely exacerbated decompensated heart failure with an aetiology of ischaemic or dilated cardiomyopathy. Apoptotic activity and N-Terminal pro-Brain Natriuretic Peptide levels were measured on admission and on the seventh day of treatment. SPSS 15 was used for statistical analysis. Results: Of the 89 patients in the study, 67(75%) were males. Overall mean age of the study sample was 61+-12 years. Patients who had N-Terminal pro-Brain Natriuretic Peptide levels higher than 6000 pg/ml on admission had greater in-patient mortality rate (p<0.001). N-Terminal pro-Brain Natriuretic Peptide levels decreased significantly on the seventh day of treatment compared to the admission values (p<0.012). Apoptotic activity levels, although not statistically significant, increased on the seventh day compared with admission values (p<0.12). Apoptotic activity levels on the 7th day were associated with in-patient deaths (p<0.002). Dopamine infusion in the treatment group during hospitalisation significantly increased apoptotic activity (p<0.035), whereas there was a trend towards decreased apoptotic activity levels with spironolactone (p<0.07). Treatment with beta-blockers did not change apoptotic activity levels (p<0.751), whereas lack of beta-blocker therapy increased apoptotic activity (p<0.02). Conclusion: N-Terminal pro-Brain Natriuretic Peptide may be an important risk predictor in decompensated heart failure exacerbations during

  4. Activity restriction, impaired capillary function, and the development of insulin resistance in lean primates

    Chadderdon, Scott M.; Belcik, J. Todd; Smith, Elise; Pranger, Lindsay; Kievit, Paul; Grove, Kevin L.; Lindner, Jonathan R

    2012-01-01

    Insulin produces capillary recruitment in skeletal muscle through a nitric oxide (NO)-dependent mechanism. Capillary recruitment is blunted in obese and diabetic subjects and contributes to impaired glucose uptake. This study's objective was to define whether inactivity, in the absence of obesity, leads to impaired capillary recruitment and contributes to insulin resistance (IR). A comprehensive metabolic and vascular assessment was performed on 19 adult male rhesus macaques (Macaca mulatta) ...

  5. Rac1 Activation Caused by Membrane Translocation of a Guanine Nucleotide Exchange Factor in Akt2-Mediated Insulin Signaling in Mouse Skeletal Muscle.

    Nobuyuki Takenaka

    Full Text Available Insulin-stimulated glucose uptake in skeletal muscle is mediated by the glucose transporter GLUT4, which is translocated to the plasma membrane following insulin stimulation. Several lines of evidence suggested that the protein kinase Akt2 plays a key role in this insulin action. The small GTPase Rac1 has also been implicated as a regulator of insulin-stimulated GLUT4 translocation, acting downstream of Akt2. However, the mechanisms whereby Akt2 regulates Rac1 activity remain obscure. The guanine nucleotide exchange factor FLJ00068 has been identified as a direct regulator of Rac1 in Akt2-mediated signaling, but its characterization was performed mostly in cultured myoblasts. Here, we provide in vivo evidence that FLJ00068 indeed acts downstream of Akt2 as a Rac1 regulator by using mouse skeletal muscle. Small interfering RNA knockdown of FLJ00068 markedly diminished GLUT4 translocation to the sarcolemma following insulin administration or ectopic expression of a constitutively activated mutant of either phosphoinositide 3-kinase or Akt2. Additionally, insulin and these constitutively activated mutants caused the activation of Rac1 as shown by immunofluorescent microscopy using a polypeptide probe specific to activated Rac1 in isolated gastrocnemius muscle fibers and frozen sections of gastrocnemius muscle. This Rac1 activation was also abrogated by FLJ00068 knockdown. Furthermore, we observed translocation of FLJ00068 to the cell periphery following insulin stimulation in cultured myoblasts. Localization of FLJ00068 in the plasma membrane in insulin-stimulated, but not unstimulated, myoblasts and mouse gastrocnemius muscle was further affirmed by subcellular fractionation and subsequent immunoblotting. Collectively, these results strongly support a critical role of FLJ00068 in Akt2-mediated Rac1 activation in mouse skeletal muscle insulin signaling.

  6. Interaction of the C-terminal acidic domain of the insulin receptor with histone modulates the receptor kinase activity.

    Baron, V; Kaliman, P; Alengrin, F; Van Obberghen, E

    1995-04-01

    In this study, we investigated the role of the insulin receptor domain 1270-1280, an acid-rich sequence located in the receptor C-terminus. Antipeptide IgG raised against this sequence were obtained and used to analyze their effect on receptor function. Antipeptide IgG inhibited receptor autophosphorylation at Tyr1146, Tyr1150 and Tyr1151. These sites are known to be key modulators of the receptor activity. Autophosphorylation at other sites may also have been inhibited. The antipeptide antibody decreased the receptor kinase activity measured with poly(Glu80Tyr20) and a synthetic peptide corresponding to the proreceptor sequence 1142-1158. We provide evidence that the effect of the antibody on substrate phosphorylation may result from the control of the phosphorylation level of the receptor. Concerning the action of the antipeptide IgG on the receptor kinase activity, histone did not behave similarly to poly(Glu80Tyr20). The antibody recognizing sequence 1270-1280 competed with histone for an overlapping binding site. Histone also modulated insulin receptor autophosphorylation, supporting the idea that interference with domain 1270-1280 alters the receptor kinase. Our data suggest that the acidic region including residues 1270-1280 of the insulin receptor C-terminus is involved in the following events: (a) receptor binding with histone, an exogenous substrate of the receptor kinase, and (b) the regulation of receptor autophosphorylation and kinase activity. Based on these observations, we would like to propose that this insulin receptor domain could interact with cellular proteins modulating the receptor kinase. PMID:7744039

  7. Cafeteria diet-induced insulin resistance is not associated with decreased insulin signaling or AMPK activity and is alleviated by physical training in rats

    Brandt, Nina; De Bock, Katrien; Richter, Erik;

    2010-01-01

    counteracted by training. In the perfused hindlimb, insulin-stimulated glucose transport in red gastrocnemius muscle was completely abolished in CAF and rescued by exercise training. Apart from a tendency toward an approximately 20% reduction in both basal and insulin-stimulated Akt Ser(473) phosphorylation (P......) among the groups. In conclusion, surplus energy intake of a palatable but low-fat cafeteria diet resulted in obesity and insulin resistance that was rescued by exercise training. Interestingly, insulin resistance was not accompanied by major defects in the insulin-signaling cascade or in altered AMPK......Excess energy intake via a palatable low-fat diet (cafeteria diet) is known to induce obesity and glucose intolerance in rats. However, the molecular mechanisms behind this adaptation are not known, and it is also not known whether exercise training can reverse it. Male Wistar rats were assigned to...

  8. Rat liver insulin receptor

    Using insulin affinity chromatography, the authors have isolated highly purified insulin receptor from rat liver. When evaluated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions, the rat liver receptor contained the M/sub r/ 125,000 α-subunit, the M/sub r/ 90,000 β-subunit, and varying proportions of the M/sub r/ 45,000 β'-subunit. The specific insulin binding of the purified receptor was 25-30 μg of 125I-insulin/mg of protein, and the receptor underwent insulin-dependent autophosphorylation. Rat liver and human placental receptors differ from each other in several functional aspects: (1) the adsorption-desorption behavior from four insulin affinity columns indicated that the rat liver receptor binds less firmly to immobilized ligands; (2) the 125I-insulin binding affinity of the rat liver receptor is lower than that of the placental receptor; (3) partial reduction of the rat liver receptor with dithiothreitol increases its insulin binding affinity whereas the binding affinity of the placental receptor is unchanged; (4) at optimal insulin concentration, rat liver receptor autophosphorylation is stimulated 25-50-fold whereas the placental receptor is stimulated only 4-6-fold. Conversion of the β-subunit to β' by proteolysis is a major problem that occurs during exposure of the receptor to the pH 5.0 buffer used to elute the insulin affinity column. Proteolytic destruction and the accompanying loss of insulin-dependent autophosphorylation can be substantially reduced by proteolysis inhibitors. In summary, rat liver and human placental receptors differ functionally in both α- and β-subunits. Insulin binding to the α-subunit of the purified rat liver receptor communicates a signal that activates the β-subunit; however, major proteolytic destruction of the β-subunit does not affect insulin binding to the α-subunit

  9. Macrophage TCF-4 co-activates p65 to potentiate chronic inflammation and insulin resistance in mice.

    Kang, Xia; Hou, Along; Wang, Rui; Liu, Da; Xiang, Wei; Xie, Qingyun; Zhang, Bo; Gan, Lixia; Zheng, Wei; Miao, Hongming

    2016-07-01

    Transcription factor 4 (TCF-4) was recently identified as a candidate gene for the cause of type 2 diabetes, although the mechanisms have not been fully elucidated. In the present study, we demonstrated that the TCF-4 transgene in macrophages aggravated high-fat diet (HFD)-induced insulin resistance and chronic inflammation, characterized by the elevation of proinflammatory cytokines in the blood, liver and white adipose tissue, as well as a proinflammatory profile of immune cells in visceral fats in mice. Mechanistically, TCF-4 functioned as a co-activator of p65 to amplify the saturated free fatty acid (FFA)-stimulated promoter activity, mRNA transcription and secretion of proinflammatory cytokines in primary macrophages. Blockage of p65 with a specific interfering RNA or inhibitor could prevent TCF-4-enhanced expression of proinflammatory cytokines in FFA/lipopolysaccharide-treated primary macrophages. The p65 inhibitor could abolish macrophage TCF-4 transgene-aggravated systemic inflammation, glucose intolerance and insulin resistance in HFD-treated mice. In addition, we demonstrated that the mRNA expression of TCF-4 in the peripheral blood monocytes from humans was positively correlated to the levels of interleukin (IL)-1β, tumour necrosis factor α, IL-6 and fasting plasma glucose. In summary, we identified TCF-4 as a co-activator of p65 in the potentiation of proinflammatory cytokine production in macrophages and aggravation of HFD-induced chronic inflammation and insulin resistance in mice. PMID:27129186

  10. Evidence of insulin-stimulated phosphorylation and activation of the mammalian target of rapamycin mediated by a protein kinase B signaling pathway

    Scott, Pamela H; Brunn, Gregory J.; Kohn, Aimee D; Roth, Richard A.; Lawrence, John C.

    1998-01-01

    The effects of insulin on the mammalian target of rapamycin, mTOR, were investigated in 3T3-L1 adipocytes. mTOR protein kinase activity was measured in immune complex assays with recombinant PHAS-I as substrate. Insulin-stimulated kinase activity was clearly observed when immunoprecipitations were conducted with the mTOR antibody, mTAb2. Insulin also increased by severalfold the 32P content of mTOR that was determined after purifying the protein from 32P-labeled adipocytes with rapamycin⋅FKBP...

  11. [Transaminase activity of the cortical layer of the kidney of rats of different ages and sex after administration of hydrocortisone and insulin].

    Poletaeva, K A

    1971-01-01

    Response of cortical layer of rat kidney to separate and combined administration of hydrocortisone and insulin, as manifested by the activity of aspartate-alpha-ketoglutarate transaminase (Asp-T) and alanine-alpha-ketoglutarate transaminase (Ala-T), varied in males and females of different age. Prolonged administration of insulin to normal preadolescent rats and to adult males and females did not affect the activity of Asp-T and Ala-T in the cortical layer of kidney. During simultaneous prolonged administration of hydrocortisone and insulin to preadolescent male rats, there occurred no increase in the activity of Asp-T induced by administration of hydrocortisone alone. During simultaneous prolonged administration of hydrocortisone and insulin to adult male rats, activity of Asp-T of the cortical layer of kidney remained at the same level at after administration of hydrocortisone alone. PMID:5317624

  12. The role of mitogen-activated protein kinase in insulin and insulin-like growth factor I (IGF-I) signaling cascades for progesterone and IGF-binding protein-1 production in human granulosa cells.

    Seto-Young, Donna; Zajac, Jacek; Liu, Hung-Ching; Rosenwaks, Zev; Poretsky, Leonid

    2003-07-01

    Insulin and IGF-I participate in the regulation of ovulation, steroidogenesis, and IGF-binding protein (IGFBP) production in the ovary. Insulin and IGF-I actions in the ovary are closely related. For example, insulin may amplify IGF-I action in the ovary by up-regulating type I IGF receptors and inhibiting IGFBP-1 production, thus increasing the bioavailability of IGF-I. It is hypothesized that ovarian effects of insulin in insulin-resistant states are mediated via an insulin action pathway(s) distinct from those involved in glucose transport. We previously reported that insulin-induced stimulation of progesterone and inhibition of IGFBP-1 production in the human ovary are mediated by signaling pathways that are independent of phosphatidylinositol 3-kinase, the enzyme whose activation is crucial for glucose transport. We now examined whether activation of MAPK is necessary to mediate insulin-induced or IGF-I-induced stimulation of progesterone or inhibition of IGFBP-1 production in human granulosa cells. Human granulosa cells were obtained during in vitro fertilization. Cells (0.5-1 x 10(5)) were incubated for 24 h in the presence of 0, 10, 10(2), or 10(3) ng/ml insulin or 0, 0.5, 1, 2.5, or 5 ng/ml IGF-I and in the presence or absence of 1 micro M PD98059, a specific inhibitor of ERK1/2 MAPK. The progesterone concentration in the tissue culture medium was measured by RIA (Pantex, Santa Monica, CA), and the IGFBP-1 concentration was measured by immunoradiometric assay (DSL-7800, Diagnostic Systems Laboratories, Inc., Webster, TX). MAPK activity was assessed using the MAPK IP-Kinase assay kit (Upstate Biotechnology, Inc., Lake Placid, NY). ANOVA was used to compare mean values of progesterone or IGFBP-1 concentrations. MAPK was stimulated by insulin up to 350% of the baseline value. Progesterone production in human granulosa cells was stimulated by insulin in a dose-related manner to 123% of the control value (P < 0.001), and IGFBP-1 production was inhibited to 25

  13. Fuel-Stimulated Insulin Secretion Depends upon Mitochondria Activation and the Integration of Mitochondrial and Cytosolic Substrate Cycles

    Gary W. Cline

    2011-10-01

    Full Text Available The pancreatic islet β-cell is uniquely specialized to couple its metabolism and rates of insulin secretion with the levels of circulating nutrient fuels, with the mitochondrial playing a central regulatory role in this process. In the β-cell, mitochondrial activation generates an integrated signal reflecting rates of oxidativephosphorylation, Kreb's cycle flux, and anaplerosis that ultimately determines the rate of insulin exocytosis. Mitochondrial activation can be regulated by proton leak and mediated by UCP2, and by alkalinization to utilize the pH gradient to drive substrate and ion transport. Converging lines of evidence support the hypothesis that substrate cycles driven by rates of Kreb's cycle flux and by anaplerosis play an integral role in coupling responsive changes in mitochondrial metabolism with insulin secretion. The components and mechanisms that account for the integrated signal of ATP production, substrate cycling, the regulation of cellular redox state, and the production of other secondary signaling intermediates are operative in both rodent and human islet β-cells.

  14. Long-Term Consumption of Platycodi Radix Ameliorates Obesity and Insulin Resistance via the Activation of AMPK Pathways.

    Lee, Chae Eun; Hur, Haeng Jeon; Hwang, Jin-Taek; Sung, Mi Jeong; Yang, Hye Jeong; Kim, Hyun-Jin; Park, Jae Ho; Kwon, Dae Young; Kim, Myung-Sunny

    2012-01-01

    This study was designed to evaluate the effects and mechanism of Platycodi radix, having white balloon flower (Platycodon grandiflorum for. albiflorum (Honda) H. Hara) on obesity and insulin resistance. The extracts of Platycodi radix with white balloon flower were tested in cultured cells and administered into mice on a high-fat diet. The Platycodi radix activated the AMPK/ACC phosphorylation in C2C12 myotubes and also suppressed adipocyte differentiation in 3T3-L1 cells. In experimental animal, it suppressed the weight gain of obese mice and ameliorated obesity-induced insulin resistance. It also reduced the elevated circulating mediators, including triglyceride (TG), T-CHO, leptin, resistin, and monocyte chemotactic protein (MCP)-1 in obesity. As shown in C2C12 myotubes, the administration of Platycodi radix extracts also recovered the AMPK/ACC phosphorylation in the muscle of obese mice. These results suggest that Platycodi radix with white balloon flower ameliorates obesity and insulin resistance in obese mice via the activation of AMPK/ACC pathways and reductions of adipocyte differentiation. PMID:22829857

  15. Long-Term Consumption of Platycodi Radix Ameliorates Obesity and Insulin Resistance via the Activation of AMPK Pathways

    Chae Eun Lee

    2012-01-01

    Full Text Available This study was designed to evaluate the effects and mechanism of Platycodi radix, having white balloon flower (Platycodon grandiflorum for. albiflorum (Honda H. Hara on obesity and insulin resistance. The extracts of Platycodi radix with white balloon flower were tested in cultured cells and administered into mice on a high-fat diet. The Platycodi radix activated the AMPK/ACC phosphorylation in C2C12 myotubes and also suppressed adipocyte differentiation in 3T3-L1 cells. In experimental animal, it suppressed the weight gain of obese mice and ameliorated obesity-induced insulin resistance. It also reduced the elevated circulating mediators, including triglyceride (TG, T-CHO, leptin, resistin, and monocyte chemotactic protein (MCP-1 in obesity. As shown in C2C12 myotubes, the administration of Platycodi radix extracts also recovered the AMPK/ACC phosphorylation in the muscle of obese mice. These results suggest that Platycodi radix with white balloon flower ameliorates obesity and insulin resistance in obese mice via the activation of AMPK/ACC pathways and reductions of adipocyte differentiation.

  16. Effect of insulin analogues on insulin/IGF1 hybrid receptors: increased activation by glargine but not by its metabolites M1 and M2.

    Cécile Pierre-Eugene

    Full Text Available BACKGROUND: In diabetic patients, the pharmacokinetics of injected human insulin does not permit optimal control of glycemia. Fast and slow acting insulin analogues have been developed, but they may have adverse properties, such as increased mitogenic or anti-apoptotic signaling. Insulin/IGF1 hybrid receptors (IR/IGF1R, present in most tissues, have been proposed to transmit biological effects close to those of IGF1R. However, the study of hybrid receptors is difficult because of the presence of IR and IGF1R homodimers. Our objective was to perform the first study on the pharmacological properties of the five marketed insulin analogues towards IR/IGF1R hybrids. METHODOLOGY: To study the effect of insulin analogues on IR/IGF1R hybrids, we used our previously developed Bioluminescence Resonance Energy Transfer (BRET assay that permits specific analysis of the pharmacological properties of hybrid receptors. Moreover, we have developed a new, highly sensitive BRET-based assay to monitor phophatidylinositol-3 phosphate (PIP(3 production in living cells. Using this assay, we performed a detailed pharmacological analysis of PIP(3 production induced by IGF1, insulin and insulin analogues in living breast cancer-derived MCF-7 and MDA-MB231 cells. RESULTS: Among the five insulin analogues tested, only glargine stimulated IR/IGF1R hybrids with an EC50 that was significantly lower than insulin and close to that of IGF1. Glargine more efficiently stimulated PIP(3 production in MCF-7 cells but not in MDA-MB231 cells as compared to insulin. In contrast, glargine metabolites M1 and M2 showed lower potency for hybrid receptors stimulation, PIP(3 production, Akt and Erk1/2 phosphorylation and DNA synthesis in MCF-7 cells, compared to insulin. CONCLUSION: Glargine, possibly acting through IR/IGF1R hybrids, displays higher potency, whereas its metabolites M1 and M2 display lower potency than insulin for the stimulation of proliferative/anti-apoptotic pathways in

  17. Microgravity alters basal and insulin-mediated metabolic activity of normal and neoplastic cells.

    Coinu, Rita; Galleri, Grazia; Pippia, Proto; Tilocca, Maria Giovanna; Meloni, Mariantonia; Covelli, Bianca; Chiaviello, Angela; Palumbo, Giuseppe

    2004-07-01

    In this paper we report the behaviour of normal vascular smooth muscle cells and transformed breast cancer cells under normal versus simulated microgravity conditions by comparing cell proliferation, Glucose transport, Methionine uptake and protein synthesis. Modeled microgravity profoundly affects cell growth (especially in normal cells) and Glucose or Methionine metabolism (although to different extent in the two cell lines). Since both cells own responsive insulin receptors, the comparison was extended to insulin-stimulated versus unstimulated conditions. We report that the detected metabolic changes were strongly enhanced when the cells were simultaneously stimulated with insulin and subjected to modeled microgravity stress. Such observations may have important returns for human health in space; they deserve further attention. PMID:16237830

  18. Predicting an asthma exacerbation in children 2 to 5 years of age

    Swern, A.S.; Tozzi, C.A.; Knorr, B.;

    2008-01-01

    an exacerbation. Caregiver-reported information (daytime cough, breathing difficulties, limitation of activity, nighttime cough or awakening, daytime and nighttime beta2-agonist use) were analyzed using general estimating equations with an exchangeable within-subject log odds ratio regression...... structure to identify predictors of an exacerbation. RESULTS: Average symptom scores and beta2-agonist use increased significantly before exacerbation but at different rates. A combination of daytime cough and wheeze and nighttime beta2-agonist use 1 day before the exacerbation was identified as strongly...... predictive of an exacerbation. These methods predicted 149 (66.8%) of the exacerbations with a very low false-positive rate of 14.2%. CONCLUSIONS: No individual symptom was predictive of an imminent asthma exacerbation, but a combination of increased daytime cough, daytime wheeze, and nighttime beta2-agonist...

  19. Insulin sensitizes FGF21 in glucose and lipid metabolisms via activating common AKT pathway.

    Yu, Dan; Ye, Xianlong; Wu, Qiang; Li, Shujie; Yang, Yongbi; He, Jinjiao; Liu, Yunye; Zhang, Xiaoyu; Yuan, Qingyan; Liu, Mingyao; Li, Deshan; Ren, Guiping

    2016-06-01

    Previous studies reveal that fibroblast growth factor 21 (FGF21) sensitizes insulin to achieve a synergy in regulating glucose metabolism. Here, we report that insulin sensitizes FGF21 in regulating both glucose and lipid metabolisms. db/db diabetic mice were subcutaneously administrated once a day for 6 weeks. Effective dose of insulin (1 U) could control blood glucose level of the db/db mice for maximum of 2 h, increased the body weight of the db/db mice and did not improve serum lipid parameters. In contrast, effective dose of FGF21 (0.5 mg/kg) could maintain blood glucose of the db/db mice at normal level for at least 24 h, repressed the weight gain of the mice and significantly improved lipid parameters. Ineffective doses of FGF21 (0.125 mg/kg) and insulin had no effect on blood glucose level of the db/db mice after 24 h administration, body weight or lipid parameters. However, combination of the two ineffective doses could maintain blood glucose level of the db/db mice for at least 24 h, suppressed weight gain and significantly improved lipid parameters. These results suggest that insulin sensitizes FGF21 in regulating both glucose and lipid metabolism. The results aimed to study the molecular basis of FGF21 sensitization indicates that combination of the two ineffective doses increased the mRNA expression of glut1, glut4, β-Klotho, sirt1, pgc-1α, ucp-1 and AKT phosphorylation, decreased fasn. The results demonstrate that insulin sensitizes FGF21 through elevating the phosphorylation of common gene Akt and amplifying FGF21 downstream signaling, including increasing expression of glut1 sirt1, pgc-1α, ucp-1, and decreasing fasn expression. In summary, we reports herein for the first time that insulin sensitizes FGF21 to achieve a synergy in regulating glucose and lipid metabolism. Along with previous studies, we conclude that the synergistic effect between FGF21 and insulin is realized through mutual sensitization. PMID:26607153

  20. Defective insulin response of cyclic adenosine monophosphate-dependent protein kinase in insulin-resistant humans.

    Kida, Y; Nyomba, B L; Bogardus, C; Mott, D M

    1991-01-01

    Insulin-stimulated glycogen synthase activity in human muscle correlates with insulin-mediated glucose disposal and is reduced in insulin-resistant subjects. Inhibition of the cyclic AMP-dependent protein kinase (A-kinase) is considered as a possible mechanism of insulin action for glycogen synthase activation. In this study, we investigated the time course of insulin action on human muscle A-kinase activity during a 2-h insulin infusion in 13 insulin-sensitive (group S) and 7 insulin-resista...

  1. Adipokines and Hepatic Insulin Resistance

    Yu Li; Lin Ding; Waseem Hassan; Daoud Abdelkader; Jing Shang

    2013-01-01

    Obesity is a major risk factor for insulin resistance and type 2 diabetes. Adipose tissue is now considered to be an active endocrine organ that secretes various adipokines such as adiponectin, leptin, resistin, tumour necrosis factor-α, and interleukin-6. Recent studies have shown that these factors might provide a molecular link between increased adiposity and impaired insulin sensitivity. Since hepatic insulin resistance plays the key role in the whole body insulin resistance, clarificatio...

  2. Barbiturates inhibit ATP-K+ channels and voltage-activated currents in CRI-G1 insulin-secreting cells.

    Kozlowski, R. Z.; Ashford, M. L.

    1991-01-01

    1. Patch-clamp recording techniques were used to examine the effects of barbiturates upon the ATP-K+ channel, and voltage-activated channels present in the plasma membrane of CRI-G1 insulin-secreting cells. 2. Thiopentone inhibited ATP-K+ channel activity when applied to cell-attached patches or the intracellular or extracellular surface of cell-free patches. Secobarbitone and pentobarbitone were also effective inhibitors of ATP-K+ channels in cell-free patches, whereas phenobarbitone was ine...

  3. The monomeric alpha beta form of the insulin receptor exhibits much higher insulin-dependent tyrosine-specific protein kinase activity than the intact alpha 2 beta 2 form of the receptor.

    Fujita-Yamaguchi, Y; Kathuria, S.

    1985-01-01

    The relationship between the structure of the insulin receptor and its kinase activity was studied on the purified receptor treated with different concentrations of dithiothreitol. An enhanced autophosphorylation of the beta subunit (Mr, 90,000) was observed on NaDodSO4/PAGE under reducing conditions when the receptor was treated with 0.1-0.75 mM dithiothreitol in the presence of 1 microM insulin. Since we have previously observed (unpublished data) that incubation of the purified receptor wi...

  4. Accelerated extracellular matrix turnover during exacerbations of COPD

    Sand, Jannie M B; Knox, Alan J; Lange, Peter;

    2015-01-01

    BACKGROUND: Exacerbations of chronic obstructive pulmonary disease (COPD) contribute significantly to disease progression. However, the effect on tissue structure and turnover is not well described. There is an urgent clinical need for biomarkers of disease activity associated with disease...... progression. Extracellular matrix (ECM) turnover reflects activity in tissues and consequently assessment of ECM turnover may serve as biomarkers of disease activity. We hypothesized that the turnover of lung ECM proteins were altered during exacerbations of COPD. METHODS: 69 patients with COPD hospitalised...... elevated levels of circulating fragments of structural proteins, which may serve as markers of disease activity. This suggests that patients with COPD have accelerated ECM turnover during exacerbations which may be related to disease progression....

  5. Quercetin inhibits AMPK/TXNIP activation and reduces inflammatory lesions to improve insulin signaling defect in the hypothalamus of high fructose-fed rats.

    Zhang, Qing-Yu; Pan, Ying; Wang, Rong; Kang, Lin-Lin; Xue, Qiao-Chu; Wang, Xiao-Ning; Kong, Ling-Dong

    2014-04-01

    Fructose is a nutritional composition of fruits and honey. Its excess consumption induces insulin resistance-associated metabolic diseases. Hypothalamic insulin signaling plays a pivotal role in controlling whole-body insulin sensitivity and energy homeostasis. Quercetin, a natural flavonoid, has been reported to ameliorate high fructose-induced rat insulin resistance and hyperlipidemia. In this study, we investigated its regulatory effects on the hypothalamus of high fructose-fed rats. Rats were fed 10% fructose in drinking water for 10 weeks. After 4 weeks, these animals were orally treated with quercetin (50 and 100 mg/kg), allopurinol (5 mg/kg) and water daily for the next 6 weeks, respectively. Quercetin effectively restored high fructose-induced hypothalamic insulin signaling defect by up-regulating the phosphorylation of insulin receptor and protein kinase B. Furthermore, quercetin was found to reduce metabolic nutrient sensors adenosine monophosphate-activated protein kinase (AMPK) activation and thioredoxin-interacting protein (TXNIP) overexpression, as well as the glutamine-glutamate cycle dysfunction in the hypothalamus of high fructose-fed rats. Subsequently, it ameliorated high fructose-caused hypothalamic inflammatory lesions in rats by suppressing the activation of hypothalamic nuclear factor κB (NF-κB) pathway and NOD-like receptor 3 (NLRP3) inflammasome with interleukin 1β maturation. Allopurinol had similar effects. These results provide in vivo evidence that quercetin-mediated down-regulation of AMPK/TXNIP and subsequent inhibition of NF-κB pathway/NLRP3 inflammasome activation in the hypothalamus of rats may be associated with the reduction of hypothalamic inflammatory lesions, contributing to the improvement of hypothalamic insulin signaling defect in this model. Thus, quercetin with the central activity may be a therapeutic for high fructose-induced insulin resistance and hyperlipidemia in humans. PMID:24491314

  6. Endothelial activation markers (VCAM-1, vWF in patients with chronic hepatitis C and insulin resistance

    T. V. Antonova

    2012-01-01

    Full Text Available Blood markers of endothelial activation (sVCAM-1, vWF: Ag in patients with chronic hepatitis C in the presence of insulin resistance, metabolic syndrome and its components had been evaluated. The study included 69 patients with chronic hepatitis C with oligosymptomatic the disease. In one third of cases of chronic hepatitis C (33.3% showed improvement in the blood content of sVCAM-1 and / or vWF: Ag. In patients with chronic hepatitis C with insulin resistance, metabolic syndrome significantly more often found signs adhesion of endothelial dysfunction (increased blood concentrations of sVCAM-1 than in patients without these disorders. Found that in patients with severe hepatic fibrosis in patients with chronic hepatitis C blood concentration sVCAM-1 is significantly higher compared to patients with early stages of fibrosis (F0-F2, including those in patients without insulin resistance. These data suggest the multivariate development of endothelial dysfunction in chronic hepatitis C.

  7. Drosophila insulin and target of rapamycin (TOR pathways regulate GSK3 beta activity to control Myc stability and determine Myc expression in vivo

    Parisi Federica

    2011-09-01

    Full Text Available Abstract Background Genetic studies in Drosophila melanogaster reveal an important role for Myc in controlling growth. Similar studies have also shown how components of the insulin and target of rapamycin (TOR pathways are key regulators of growth. Despite a few suggestions that Myc transcriptional activity lies downstream of these pathways, a molecular mechanism linking these signaling pathways to Myc has not been clearly described. Using biochemical and genetic approaches we tried to identify novel mechanisms that control Myc activity upon activation of insulin and TOR signaling pathways. Results Our biochemical studies show that insulin induces Myc protein accumulation in Drosophila S2 cells, which correlates with a decrease in the activity of glycogen synthase kinase 3-beta (GSK3β a kinase that is responsible for Myc protein degradation. Induction of Myc by insulin is inhibited by the presence of the TOR inhibitor rapamycin, suggesting that insulin-induced Myc protein accumulation depends on the activation of TOR complex 1. Treatment with amino acids that directly activate the TOR pathway results in Myc protein accumulation, which also depends on the ability of S6K kinase to inhibit GSK3β activity. Myc upregulation by insulin and TOR pathways is a mechanism conserved in cells from the wing imaginal disc, where expression of Dp110 and Rheb also induces Myc protein accumulation, while inhibition of insulin and TOR pathways result in the opposite effect. Our functional analysis, aimed at quantifying the relative contribution of Myc to ommatidial growth downstream of insulin and TOR pathways, revealed that Myc activity is necessary to sustain the proliferation of cells from the ommatidia upon Dp110 expression, while its contribution downstream of TOR is significant to control the size of the ommatidia. Conclusions Our study presents novel evidence that Myc activity acts downstream of insulin and TOR pathways to control growth in Drosophila. At

  8. PPARgamma activation attenuates T-lymphocyte-dependent inflammation of adipose tissue and development of insulin resistance in obese mice

    Unger Thomas

    2010-10-01

    Full Text Available Abstract Background Inflammation of adipose tissue (AT has been recently accepted as a first step towards obesity-mediated insulin resistance. We could previously show that mice fed with high fat diet (HFD develop systemic insulin resistance (IR and glucose intolerance (GI associated with CD4-positive T-lymphocyte infiltration into visceral AT. These T-lymphocytes, when enriched in AT, participate in the development of fat tissue inflammation and subsequent recruitment of proinflammatory macrophages. The aim of this work was to elucidate the action of the insulin sensitizing PPARgamma on T-lymphocyte infiltration during development of IR, and comparison of the PPARgamma-mediated anti-inflammatory effects of rosiglitazone and telmisartan in diet-induced obesity model (DIO-model in mice. Methods In order to investigate the molecular mechanisms underlying early development of systemic insulin resistance and glucose intolerance male C57BL/6J mice were fed with high fat diet (HFD for 10-weeks in parallel to the pharmacological intervention with rosiglitazone, telmisartan, or vehicle. Results Both rosiglitazone and telmisartan were able to reduce T-lymphocyte infiltration into AT analyzed by quantitative analysis of the T-cell marker CD3gamma and the chemokine SDF1alpha. Subsequently, both PPARgamma agonists were able to attenuate macrophage infiltration into AT, measured by the reduction of MCP1 and F4/80 expression. In parallel to the reduction of AT-inflammation, ligand-activated PPARgamma improved diet-induced IR and GI. Conclusion Together the present study demonstrates a close connection between PPARgamma-mediated anti-inflammation in AT and systemic improvement of glucose metabolism identifying T-lymphocytes as one cellular mediator of PPARgamma´s action.

  9. Insulin increases sympathetic nerve activity in part by suppression of tonic inhibitory neuropeptide Y inputs into the paraventricular nucleus in female rats.

    Cassaglia, Priscila A; Shi, Zhigang; Brooks, Virginia L

    2016-07-01

    Following binding to receptors in the arcuate nucleus (ArcN), insulin increases sympathetic nerve activity (SNA) and baroreflex control of SNA via a pathway that includes the paraventricular nucleus of the hypothalamus (PVN). Previous studies in males indicate that the sympathoexcitatory response is mediated by α-melanocyte stimulating hormone (α-MSH), which binds to PVN melanocortin type 3/4 receptors (MC3/4R). The present study was conducted in α-chloralose-anesthetized female rats to test the hypothesis that suppression of inhibitory neuropeptide Y (NPY) inputs to the PVN is also involved. In support of this, blockade of PVN NPY Y1 receptors with BIBO 3304 (NPY1x), ArcN insulin nanoinjections, and PVN NPY1x followed by ArcN insulin each increased lumbar SNA (LSNA) and its baroreflex regulation similarly. Moreover, prior PVN injections of NPY blocked the sympathoexcitatory effects of ArcN insulin. Finally, PVN nanoinjections of the MC3/4R inhibitor SHU9119 prevented both the acute (15 min) and longer, more slowly developing (60 min), increases in LSNA in response to ArcN insulin. In conclusion, in females, ArcN insulin increases LSNA, in part, by suppressing tonic PVN NPY inhibition, which unmasks excitatory α-MSH drive of LSNA. Moreover, the steadily increasing rise in LSNA induced by ArcN insulin is also dependent on PVN MC3/4R. PMID:27122366

  10. Compliance with behavioral guidelines for diet, physical activity and sedentary behaviors is related to insulin resistance among overweight and obese youth

    Sallis James F

    2011-02-01

    Full Text Available Abstract Background Overweight and obesity are established risk factors for insulin resistance in youth. A number of behavioral recommendations have been publicized with the goal of improving glycemic control. However, there is limited information about whether meeting these behavioral recommendations actually reduces insulin resistance. Findings 92 youths 11 - 16 years with BMI ≥ 85% underwent oral glucose tolerance testing. HOMA-IR and AUCInsulin/AUCGlucose were calculated as measures of insulin resistance. Dietary and physical activity (PA measures were performed. Assessments included whether or not participants met recommended levels of diet, PA and sedentary behaviors. 62% youths met criteria for insulin resistance. 82% (75/92 met at least one behavioral recommendation. Participants who met ≥ 1 dietary, sedentary, or PA recommendations had significantly reduced insulin resistance as compared with youth who did not. This relationship remained significant in multivariate modeling of insulin resistance adjusting for age, sex, and BMI. Conclusions Even relatively minor behavior change may reduce insulin resistance in youth at risk for diabetes. Our findings support the relevance of current behavioral interventions for glycemic control. Trials Registration Clinical Trials #NCT00412165.