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Sample records for cell-restricted insulin receptor

  1. Metformin and insulin receptors

    Energy Technology Data Exchange (ETDEWEB)

    Vigneri, R.; Gullo, D.; Pezzino, V.

    The authors evaluated the effect of metformin (N,N-dimethylbiguanide), a biguanide known to be less toxic than phenformin, on insulin binding to its receptors, both in vitro and in vivo. Specific /sup 125/I-insulin binding to cultured IM-9 human lymphocytes and MCF-7 human breast cancer cells was determined after preincubation with metformin. Specific /sup 125/I-insulin binding to circulating monocytes was also evaluated in six controls, eight obese subjects, and six obese type II diabetic patients before and after a short-term treatment with metformin. Plasma insulin levels and blood glucose were also measured on both occasions. Metformin significantly increased insulin binding in vitro to both IM-9 lymphocytes and MCF-7 cells; the maximum increment was 47.1% and 38.0%, respectively. Metformin treatment significantly increased insulin binding in vivo to monocytes of obese subjects and diabetic patients. Scatchard analysis indicated that the increased binding was mainly due to an increase in receptor capacity. Insulin binding to monocytes of normal controls was unchanged after metformin as were insulin levels in all groups; blood glucose was significantly reduced after metformin only in diabetic patients. These data indicate that metformin increases insulin binding to its receptors in vitro and in vivo. The effect in vivo is observed in obese subjects and in obese type II diabetic patients, paralleling the clinical effectiveness of this antidiabetic agent, and is not due to receptor regulation by circulating insulin, since no variation in insulin levels was recorded.

  2. Estradiol Binds to Insulin and Insulin Receptor Decreasing Insulin Binding in vitro

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    Robert eRoot-Bernstein

    2014-07-01

    Full Text Available Rationale: Insulin resistance associated with hyperestrogenemias occurs in gestational diabetes mellitus, polycystic ovary syndrome, ovarian hyperstimulation syndrome, estrogen therapies, metabolic syndrome and obesity. The mechanism by which insulin and estrogen interact is unknown. We hypothesize that estrogen binds directly to insulin and the insulin receptor producing insulin resistance.Objectives: To determine the binding constants of steroid hormones to insulin, the insulin receptor, and insulin-like peptides derived from the insulin receptor; and to investigate the effect of estrogens on the binding of insulin to its receptor.Methods: Ultraviolet spectroscopy, capillary electrophoresis and NMR demonstrated estrogen binding to insulin and its receptor. Horse-radish peroxidase-linked insulin was used in an ELISA-like procedure to measure the effect of estradiol on binding of insulin to its receptor. Measurements: Binding constants for estrogens to insulin and the insulin receptor were determined by concentration-dependent spectral shifts. The effect of estradiol on insulin-HRP binding to its receptor was determined by shifts in the insulin binding curve. Main Results: Estradiol bound to insulin with a Kd of 12 x 10-9 M and to the insulin receptor with a Kd of 24 x 10-9 M, while other hormones had significantly less affinity. 200 nM estradiol shifted the binding curve of insulin to its receptor 0.8 log units to the right. Conclusions: Estradiol concentrations in many hyperestrogenemic syndromes are sufficient to interfere with insulin binding to its receptor producing significant insulin resistance.

  3. Insulin receptor what role in breast cancer?

    Science.gov (United States)

    Papa, V; Costantino, A; Belfiore, A

    1997-10-01

    It is commonly believed that the insulin receptor mainly mediates the metabolic effects of insulin, whereas the closely related IGF-I receptor is considered a major factor for the regulation of cell proliferation. Experimental and epidemiological evidence indicates, however, that insulin and insulin receptors may play an important role in breast cancer. This article reviews evidence indicating that (a) insulin receptors are overexpressed in human breast cancer, (b) insulin stimulates growth in breast cancer cells, (c) cells transfected with human insulin receptor may acquire a ligand-dependent transformed phenotype, and (d) breast cancer is associated with insulin resistance and hyperinsulinemia. These findings may open new possibilities in breast cancer prevention, prognosis assessment, and therapy. (Trends Endocrinol Metab 1997; 8:306-312). (c) 1997, Elsevier Science Inc.

  4. Phenobarbital and Insulin Reciprocate Activation of the Nuclear Receptor Constitutive Androstane Receptor through the Insulin Receptor.

    Science.gov (United States)

    Yasujima, Tomoya; Saito, Kosuke; Moore, Rick; Negishi, Masahiko

    2016-05-01

    Phenobarbital (PB) antagonized insulin to inactivate the insulin receptor and attenuated the insulin receptor downstream protein kinase B (AKT)-forkhead box protein O1 and extracellular signal-regulated kinase 1/2 signals in mouse primary hepatocytes and HepG2 cells. Hepatic AKT began dephosphorylation in an early stage of PB treatment, and blood glucose levels transiently increased in both wild-type and constitutive androstane receptor (CAR) knockout (KO) mice. On the other hand, blood glucose levels increased in wild-type mice, but not KO mice, in later stages of PB treatment. As a result, PB, acting as an insulin receptor antagonist, elicited CAR-independent increases and CAR-dependent decreases of blood glucose levels at these different stages of treatment, respectively. Reciprocally, insulin activation of the insulin receptor repressed CAR activation and induction of its target CYP2B6 gene in HepG2 cells. Thus, PB and insulin cross-talk through the insulin receptor to regulate glucose and drug metabolism reciprocally.

  5. Insulin receptor knock-out mice.

    Science.gov (United States)

    Accili, D

    1997-04-01

    Targeted mutagenesis of the insulin receptor gene in mice has yielded unexpected results. This article reviews recent findings and analyzes this animal model can further our understanding of the mechanism of insulin action and its impairment in non-insulin-dependent diabetes mellitus is analyzed. (Trends Endocrinol Metab 1997;8:101-104). Published 1997 by Elsevier Science Inc.

  6. Role of insulin and insulin receptor in learning and memory.

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    Zhao, W Q; Alkon, D L

    2001-05-25

    As one of the most extensively studied protein hormones, insulin and its receptor have been known to play key roles in a variety of important biological functions. Until recent years, the functions of insulin and insulin receptor (IR) in the central nervous system (CNS) have largely remained unclear. IR is abundantly expressed in several specific brain regions that govern fundamental behaviors such as food intake, reproduction and high cognition. The IR from the periphery and CNS exhibit differences in both structure and function. In addition to that from the peripheral system, locally synthesized insulin in the brain has also been identified. Accumulated evidence has demonstrated that insulin/IR plays important roles in associative learning, as suggested by results from both interventive and correlative studies. Interruption of insulin production and IR activity causes deficits in learning and memory formation. Abnormal insulin/IR levels and activities are seen in Alzheimer's dementia, whereas administration of insulin significantly improves the cognitive performance of these patients. The synaptic bases for the action of insulin/IR include modifying neurotransmitter release processes at various types of presynaptic terminals and modulating the activities of both excitatory and inhibitory postsynaptic receptors such as NMDA and GABA receptors, respectively. At the molecular level, insulin/IR participates in regulation of learning and memory via activation of specific signaling pathways, one of which is shown to be associated with the formation of long-term memory and is composed of intracellular molecules including the shc, Grb-r/SOS, Ras/Raf, and MEK/MAP kinases. Cross-talk with another IR pathway involving IRS1, PI3 kinase, and protein kinase C, as well as with the non-receptor tyrosine kinase pp60c-src, may also be associated with memory processing.

  7. Membrane topology of insulin receptors reconstituted into lipid vesicles

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    Tranum-Jensen, Jørgen; Christiansen, K.; Carlsen, Jens;

    1994-01-01

    Anatomy, insulin receptors, membrane reconstitution, electron microscopy, quaternary structure, immunogold labeling......Anatomy, insulin receptors, membrane reconstitution, electron microscopy, quaternary structure, immunogold labeling...

  8. Agonism and antagonism at the insulin receptor

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    Knudsen, Louise; Hansen, Bo Falck; Jensen, Pia

    2012-01-01

    Insulin can trigger metabolic as well as mitogenic effects, the latter being pharmaceutically undesirable. An understanding of the structure/function relationships between insulin receptor (IR) binding and mitogenic/metabolic signalling would greatly facilitate the preclinical development of new...... insulin analogues. The occurrence of ligand agonism and antagonism is well described for G protein-coupled receptors (GPCRs) and other receptors but in general, with the exception of antibodies, not for receptor tyrosine kinases (RTKs). In the case of the IR, no natural ligand or insulin analogue has been...... shown to exhibit antagonistic properties, with the exception of a crosslinked insulin dimer (B29-B'29). However, synthetic monomeric or dimeric peptides targeting sites 1 or 2 of the IR were shown to be either agonists or antagonists. We found here that the S961 peptide, previously described to be an IR...

  9. Combining GLP-1 receptor agonists with insulin

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    Holst, Jens Juul; Vilsbøll, T

    2013-01-01

    Due to the increasing prevalence of type 2 diabetes mellitus (T2DM), the emergent trend towards diagnosis in younger patients and the progressive nature of this disease, many more patients than before now require insulin to maintain glycaemic control. However, there is a degree of inertia among...... physicians and patients regarding the initiation and intensification of insulin therapy, in part due to concerns about the associated weight gain and increased risk of hypoglycaemia. Glucagon-like peptide-1 receptor agonists (GLP-1RAs) increase insulin release and suppress glucagon secretion in a glucose......, compared with insulin, the antihyperglycaemic efficacy of GLP-1RAs is limited. The combination of a GLP-1RA and insulin might thus be highly effective for optimal glucose control, ameliorating the adverse effects typically associated with insulin. Data from clinical studies support the therapeutic...

  10. Engineering of insulin receptor isoform-selective insulin analogues.

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    Tine Glendorf

    Full Text Available BACKGROUND: The insulin receptor (IR exists in two isoforms, A and B, and the isoform expression pattern is tissue-specific. The C-terminus of the insulin B chain is important for receptor binding and has been shown to contact the IR just adjacent to the region where the A and B isoforms differ. The aim of this study was to investigate the importance of the C-terminus of the B chain in IR isoform binding in order to explore the possibility of engineering tissue-specific/liver-specific insulin analogues. METHODOLOGY/PRINCIPAL FINDINGS: Insulin analogue libraries were constructed by total amino acid scanning mutagenesis. The relative binding affinities for the A and B isoform of the IR were determined by competition assays using scintillation proximity assay technology. Structural information was obtained by X-ray crystallography. Introduction of B25A or B25N mutations resulted in analogues with a 2-fold preference for the B compared to the A isoform, whereas the opposite was observed with a B25Y substitution. An acidic amino acid residue at position B27 caused an additional 2-fold selective increase in affinity for the receptor B isoform for analogues bearing a B25N mutation. Furthermore, the combination of B25H with either B27D or B27E also resulted in B isoform-preferential analogues (2-fold preference even though the corresponding single mutation analogues displayed no differences in relative isoform binding affinity. CONCLUSIONS/SIGNIFICANCE: We have discovered a new class of IR isoform-selective insulin analogues with 2-4-fold differences in relative binding affinities for either the A or the B isoform of the IR compared to human insulin. Our results demonstrate that a mutation at position B25 alone or in combination with a mutation at position B27 in the insulin molecule confers IR isoform selectivity. Isoform-preferential analogues may provide new opportunities for developing insulin analogues with improved clinical benefits.

  11. Transgenic silkworms expressing human insulin receptors for evaluation of therapeutically active insulin receptor agonists.

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    Matsumoto, Yasuhiko; Ishii, Masaki; Ishii, Kenichi; Miyaguchi, Wataru; Horie, Ryo; Inagaki, Yoshinori; Hamamoto, Hiroshi; Tatematsu, Ken-ichiro; Uchino, Keiro; Tamura, Toshiki; Sezutsu, Hideki; Sekimizu, Kazuhisa

    2014-12-12

    We established a transgenic silkworm strain expressing the human insulin receptor (hIR) using the GAL4/UAS system. Administration of human insulin to transgenic silkworms expressing hIR decreased hemolymph sugar levels and facilitated Akt phosphorylation in the fat body. The decrease in hemolymph sugar levels induced by injection of human insulin in the transgenic silkworms expressing hIR was blocked by co-injection of wortmannin, a phosphoinositide 3-kinase inhibitor. Administration of bovine insulin, an hIR ligand, also effectively decreased sugar levels in the transgenic silkworms. These findings indicate that functional hIRs that respond to human insulin were successfully induced in the transgenic silkworms. We propose that the humanized silkworm expressing hIR is useful for in vivo evaluation of the therapeutic activities of insulin receptor agonists. Copyright © 2014 Elsevier Inc. All rights reserved.

  12. Diabetes reduces basal retinal insulin receptor signaling: reversal with systemic and local insulin.

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    Reiter, Chad E N; Wu, Xiaohua; Sandirasegarane, Lakshman; Nakamura, Makoto; Gilbert, Kirk A; Singh, Ravi S J; Fort, Patrice E; Antonetti, David A; Gardner, Thomas W

    2006-04-01

    Diabetic retinopathy is characterized by early onset of neuronal cell death. We previously showed that insulin mediates a prosurvival pathway in retinal neurons and that normal retina expresses a highly active basal insulin receptor/Akt signaling pathway that is stable throughout feeding and fasting. Using the streptozotocin-induced diabetic rat model, we tested the hypothesis that diabetes diminishes basal retinal insulin receptor signaling concomitantly with increased diabetes-induced retinal apoptosis. The expression, phosphorylation status, and/or kinase activity of the insulin receptor and downstream signaling proteins were investigated in retinas of age-matched control, diabetic, and insulin-treated diabetic rats. Four weeks of diabetes reduced basal insulin receptor kinase, insulin receptor substrate (IRS)-1/2-associated phosphatidylinositol 3-kinase, and Akt kinase activity without altering insulin receptor or IRS-1/2 expression or tyrosine phosphorylation. After 12 weeks of diabetes, constitutive insulin receptor autophosphorylation and IRS-2 expression were reduced, without changes in p42/p44 mitogen-activated protein kinase or IRS-1. Sustained systemic insulin treatment of diabetic rats prevented loss of insulin receptor and Akt kinase activity, and acute intravitreal insulin administration restored insulin receptor kinase activity. Insulin treatment restored insulin receptor-beta autophosphorylation in rat retinas maintained ex vivo, demonstrating functional receptors and suggesting loss of ligand as a cause for reduced retinal insulin receptor/Akt pathway activity. These results demonstrate that diabetes progressively impairs the constitutive retinal insulin receptor signaling pathway through Akt and suggests that loss of this survival pathway may contribute to the initial stages of diabetic retinopathy.

  13. Receptor binding characteristics and cytotoxicity of insulin-methotrexate

    Institute of Scientific and Technical Information of China (English)

    Xiao-Hong Ou; An-Ren Kuang; Zheng-Lu Liang; Xian Peng; Yu-Guo Zhong

    2004-01-01

    AIM: To characterize the receptor binding affinity and cytotoxicity of insulin-methotrexate (MTX) for the potential utilization of insulin as carriers for carcinoma target drugs.METHODS: MTX was covalently linked to insulin. InsulinMTX conjugate was purified by Sephadex G-25 column and analyzed by high performance liquid chromatography.Hepatocellular carcinoma cell membrane fractions were isolated by sucrose density gradient centrifugation.Competitive displacement of 125I-insulin with insulin and insulin-MTX binding to insulin receptors were carried out.Cytoreductive effect of insulin-MTX on human hepatoma BEL7402 cells and human hepatocyte cell line HL7702 was evaluated using the MTT assay.RESULTS: Insulin-MTX competed as effectively as insulin with 125I-insulin for insulin receptors. The values of Kd for insulin-MTX and insulin were 93.82±19.32 nmol/L and 5.01±1.24 nmol/L, respectively. The value of Kd for insulinMTX was significantly increased in comparison with insulin (t=7.2532,n=4, P<0.005). Insulin-MTX inhibited the growth of human hepatoma cells (BEL7402) almost as potently as MTX. The inhibitory effect reached a peak on the 5 th day when the growth of cells was inhibited by 79% at a concentration of 5.0 μg/mL insulin-MTX. Treatment with 5.0 μg/mL of MTX and 5.0 μg/mL of insulin-MTX merely resulted in inhibition of HL7702 cells by 31.5% and 7.8%on the 5 th day.CONCLUSION: Insulin-MTX specifically recognizes insulin receptors and inhibits the growth of BEL7402 cells. These results suggest that insulin can be used as a carrier in receptor mediated carcinoma-targeting therapy.

  14. Agonism and antagonism at the insulin receptor.

    Directory of Open Access Journals (Sweden)

    Louise Knudsen

    Full Text Available Insulin can trigger metabolic as well as mitogenic effects, the latter being pharmaceutically undesirable. An understanding of the structure/function relationships between insulin receptor (IR binding and mitogenic/metabolic signalling would greatly facilitate the preclinical development of new insulin analogues. The occurrence of ligand agonism and antagonism is well described for G protein-coupled receptors (GPCRs and other receptors but in general, with the exception of antibodies, not for receptor tyrosine kinases (RTKs. In the case of the IR, no natural ligand or insulin analogue has been shown to exhibit antagonistic properties, with the exception of a crosslinked insulin dimer (B29-B'29. However, synthetic monomeric or dimeric peptides targeting sites 1 or 2 of the IR were shown to be either agonists or antagonists. We found here that the S961 peptide, previously described to be an IR antagonist, exhibited partial agonistic effects in the 1-10 nM range, showing altogether a bell-shaped dose-response curve. Intriguingly, the agonistic effects of S961 were seen only on mitogenic endpoints ((3H-thymidine incorporation, and not on metabolic endpoints ((14C-glucose incorporation in adipocytes and muscle cells. The agonistic effects of S961 were observed in 3 independent cell lines, with complete concordance between mitogenicity ((3H-thymidine incorporation and phosphorylation of the IR and Akt. Together with the B29-B'29 crosslinked dimer, S961 is a rare example of a mixed agonist/antagonist for the human IR. A plausible mechanistic explanation based on the bivalent crosslinking model of IR activation is proposed.

  15. Quercetin suppresses insulin receptor signaling through inhibition of the insulin ligand–receptor binding and therefore impairs cancer cell proliferation

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    Wang, Feng [Department of Gastroenterology, The Tenth People’s Hospital of Shanghai, Tongji University, Shanghai 200072 (China); Department of Nanomedicine, Houston Methodist Research Institute, Houston, TX 77030 (United States); Yang, Yong, E-mail: yyang@houstonmethodist.org [Department of Nanomedicine, Houston Methodist Research Institute, Houston, TX 77030 (United States); Department of Medicine, Weill Cornell Medical College, New York, NY 10065 (United States)

    2014-10-03

    Graphical abstract: - Highlights: • Quercetin inhibits insulin ligand–receptor interactions. • Quercetin reduces downstream insulin receptor signaling. • Quercetin blocks insulin induced glucose uptake. • Quercetin suppresses insulin stimulated cancer cell proliferation and tumor growth. - Abstract: Although the flavonoid quercetin is known to inhibit activation of insulin receptor signaling, the inhibitory mechanism is largely unknown. In this study, we demonstrate that quercetin suppresses insulin induced dimerization of the insulin receptor (IR) through interfering with ligand–receptor interactions, which reduces the phosphorylation of IR and Akt. This inhibitory effect further inhibits insulin stimulated glucose uptake due to decreased cell membrane translocation of glucose transporter 4 (GLUT4), resulting in impaired cancer cell proliferation. The effect of quercetin in inhibiting tumor growth was also evident in an in vivo model, indicating a potential future application for quercetin in the treatment of cancers.

  16. Changes of insulin effect on lipogenesis and insulin binding receptors during hypokinesia

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    Macho, L.; Fickova, M.; Zorad, S.

    The effect of hypokinesia on insulin action and insulin binding to specific receptors in fat cells was studied. Male Wistar rats were exposed to hypokinesia in special adjustable plastic cages for 1, 7, 21 and 60 days, and the stimulatory effect of insulin (10 and 100 mU) on the incorporation of radiocarbon labelled glucose into lipids of fat tissue and the binding of insulin to receptors of isolated adipocytes was estimated. The stimulation of lipogenesis by insulin was slightly diminished after hypokinesia for 1 day, however, an important increase of insulin action was found in rats exposed to hypokinesia for 60 days. The decrease of insulin binding capacity of the number of binding sites per cell and of the insulin receptor density was found after 1 day of hypokinesia. In rats exposed to hypokinesia for 60 days, in agreement with the higher stimulatory affect of insulin, an increase of insulin receptor density was observed. These results showed that hypokinesia has an important influence on stimulatory action of insulin and on insulin receptors in adipocytes.

  17. Study on insulin erythrocyte receptors in patients with myocadial infarction

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    @@It has been hypothesized that the defects of insulin receptors may play an important role in the insulin resistance of coronary heart disease. As a test of this hypothesis, 20 male patients with myocardial infarction, 20 male patients with type 2 diabetes mellitus and 20 normal subjects as control were investigated.Plasma insulin were determined; at the meantinme, insulin receptors of erythrocyte were indentified by means of 125 I -labeled insulin binding to erythrocytes while the affinity constants (K1 ,K2) and the number of receptors with different affinity and capacity (Q1,Q2) were calculated according to Scatchard's graphic method. The results showed that the number of insulin receptors with low affinity (Q2) on erythrocytes,K1, K, were lower in patients with myocardial infarction than those in controls ; and Q2, K1 in patents with type 2 diabetes mellitus were also lower. So we concluded that the mechanism of insulin resistance in coronary heart disease might be associated with insulin receptor and affinity abnormalities ,differed from that in diabetic state with some degree of post-receptor defects, which suggests that there may be an interrelationship among insulin receptor defects, insulin resistance,hyperinsulinemia in developing coronary heart disease.

  18. Insulin phosphorylates calmodulin in preparations of solubilized rat hepatocyte insulin receptors

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    Sacks, D.B.; McDonald, J.M.

    1987-05-01

    It has previously been shown that insulin stimulates the phosphorylation of calmodulin in adipocyte insulin receptor preparations. Here they demonstrate that insulin also stimulates the phosphorylation of calmodulin in wheat germ lectin-enriched insulin receptor preparations obtained from rat hepatocytes. Standard phosphorylation assays were performed at 30C in the presence of 50mM Tris-HCl (pH 7.5), 0.1% (v/v) Triton X-100, 1mM EGTA, 50 M (el-TSP)ATP, 5mM MgCl2, 0.25 M polylysine, 1.2 M calmodulin and various CaS and insulin concentrations. The phosphorylation of calmodulin was determined by SDS-PAGE and autoradiography. Phosphorylation of calmodulin had an absolute requirement for insulin receptors, insulin and certain basic proteins. Phosphorylation was maximal above 13 nM insulin and at submicromolar CaS concentrations, whereas supramicromolar CaS concentrations were inhibitory. As was observed in the adipocyte insulin receptor system, calmodulin phosphorylation was dependent upon the presence of co-factors, such as polylysine, histone H/sub f/2b and protamine sulfate. The role played by these co-factors has not yet been established. These data suggest that both CaS and calmodulin participate in post receptor insulin events in hepatocytes.

  19. Equine insulin receptor and insulin-like growth factor-1 receptor expression in digital lamellar tissue and insulin target tissues.

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    Kullmann, A; Weber, P S; Bishop, J B; Roux, T M; Norby, B; Burns, T A; McCutcheon, L J; Belknap, J K; Geor, R J

    2016-09-01

    Hyperinsulinaemia is implicated in the pathogenesis of endocrinopathic laminitis. Insulin can bind to different receptors: two insulin receptor isoforms (InsR-A and InsR-B), insulin-like growth factor-1 receptor (IGF-1R) and InsR/IGF-1R hybrid receptor (Hybrid). Currently, mRNA expression of these receptors in equine tissues and the influence of body type and dietary carbohydrate intake on expression of these receptors is not known. The study objectives were to characterise InsR-A, InsR-B, IGF-1R and Hybrid expression in lamellar tissue (LT) and insulin responsive tissues from horses and examine the effect of dietary nonstructural carbohydrate (NSC) on mRNA expression of these receptors in LT, skeletal muscle, liver and two adipose tissue (AT) depots of lean and obese ponies. In vivo experiment. Lamellar tissue samples were evaluated by quantitative reverse transcription polymerase chain reaction (RT-qPCR) for receptor mRNA expression (n = 8) and immunoblotting for protein expression (n = 3). Archived LT, skeletal muscle, liver and AT from lean and obese mixed-breed ponies fed either a low (~7% NSC as dry matter; 5 lean, 5 obese) or high NSC diet (~42% NSC as dry matter; 6 lean, 6 obese) for 7 days were evaluated by RT-qPCR to determine the effect of body condition and diet on expression of the receptors in different tissues. Significance was set at P≤0.05. Lamellar tissue expresses both InsR isoforms, IGF-1R and Hybrid. LT IGF-1R gene expression was greater than either InsR isoform and InsR-A expression was greater than InsR-B (P≤0.05). Obesity significantly lowered IGF-1R, InsR-A and InsR-B mRNA expression in LT and InsR-A in tailhead AT. High NSC diet lowered expression of all three receptor types in liver; IGF-1R and InsR-A in LT and InsR-A in tailhead AT. Lamellar tissue expresses IGF-1R, InsR isoforms and Hybrids. The functional characteristics of these receptors and their role in endocrinopathic laminitis warrants further investigation. © 2015 EVJ

  20. Insulin Receptor Signaling in POMC, but Not AgRP, Neurons Controls Adipose Tissue Insulin Action.

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    Shin, Andrew C; Filatova, Nika; Lindtner, Claudia; Chi, Tiffany; Degann, Seta; Oberlin, Douglas; Buettner, Christoph

    2017-06-01

    Insulin is a key regulator of adipose tissue lipolysis, and impaired adipose tissue insulin action results in unrestrained lipolysis and lipotoxicity, which are hallmarks of the metabolic syndrome and diabetes. Insulin regulates adipose tissue metabolism through direct effects on adipocytes and through signaling in the central nervous system by dampening sympathetic outflow to the adipose tissue. Here we examined the role of insulin signaling in agouti-related protein (AgRP) and pro-opiomelanocortin (POMC) neurons in regulating hepatic and adipose tissue insulin action. Mice lacking the insulin receptor in AgRP neurons (AgRP IR KO) exhibited impaired hepatic insulin action because the ability of insulin to suppress hepatic glucose production (hGP) was reduced, but the ability of insulin to suppress lipolysis was unaltered. To the contrary, in POMC IR KO mice, insulin lowered hGP but failed to suppress adipose tissue lipolysis. High-fat diet equally worsened glucose tolerance in AgRP and POMC IR KO mice and their respective controls but increased hepatic triglyceride levels only in POMC IR KO mice, consistent with impaired lipolytic regulation resulting in fatty liver. These data suggest that although insulin signaling in AgRP neurons is important in regulating glucose metabolism, insulin signaling in POMC neurons controls adipose tissue lipolysis and prevents high-fat diet-induced hepatic steatosis. © 2017 by the American Diabetes Association.

  1. Prediction of a novel internal rearrangement of the insulin receptor.

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    Sit, Kei C; van Lonkhuyzen, Derek; Walsh, Terry; Croll, Tristan

    2017-03-01

    The insulin receptor (IR) plays critical roles in metabolism and growth, directed by the binding of insulin. Decades of research to understand the mechanism of insulin binding and activation of the IR have identified a region of the receptor, the C-terminal (CT) peptide, to be crucial for insulin binding. In particular, a truncated IR consisting of the first three domains fused to the CT peptide was found to bind insulin with nanomolar affinity, with undetectable binding in the absence of fused or soluble CT peptide. Problematically, all current crystal structures of the IR indicate the fusion point of the CT peptide to the three domains is located far from the position of the CT peptide as resolved in such structures. We have attempted to address this problem using molecular modelling and dynamics simulations. The results led to the identification of a potential inter-domain interaction between the L2 domain and the CT peptide that is not observed in any of the crystal structures of the IR. Investigations into this new interaction found a conformational change that could potentially be in response to insulin binding. Additionally, further simulation work with the new conformation demonstrated its compatibility with the position and orientation of insulin from the latest insulin-bound IR crystal structure.

  2. Binding Mode of Insulin Receptor and Agonist Peptide

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Insulin is a protein hormone secreted by pancreatic β cells. One of its main functions is to keep the balance of glucose inside the body by regulating the absorption and metabolism of glucose in the periphery tissue, as well as the production and storage of hepatic glycogen. The insulin receptor is a transmembrane glycoprotein in which two α subunits with a molecular weight of 135 kD and twoβ subunits with a molecular weight of 95 kD are joined by a disulfide bond to form a β-α-α-β structure. The extracellular α subunit, especially, its three domains near the N-terminal are partially responsible for signal transduction or ligand-binding, as indicated by the experiments. The extracellular α subunits are involved in binding the ligands. The experimental results indicate that the three domains of the N-terminal of the α subunits are the main determinative parts of the insulin receptor to bind the insulin or mimetic peptide.We employed the extracellular domain (PDBID: 1IGR) of the insulin-like growth factor-1 receptor (IGF-1 R ) as the template to simulate and optimize the spatial structures of the three domains in the extracellular domain of the insulin receptor, which includes 468 residues. The work was accomplished by making use of the homology program in the Insight Ⅱ package on an Origin3800 server. The docking calculations of the insulin receptor obtained by homology with hexapeptides were carried out by means of the program Affinity. The analysis indicated that there were hydrogen bonding, and electrostatic and hydrophobic effects in the docking complex of the insulin receptor with hexapeptides.Moreover, we described the spatial orientation of a mimetic peptide with agonist activity in the docking complex. We obtained a rough model of binding of DLAPSQ or STIVYS with the insulin receptor, which provides the powerful theoretical support for designing the minimal insulin mimetic peptide with agonist activity, making it possible to develop oral small

  3. Interacting with the Human Insulin Receptor

    DEFF Research Database (Denmark)

    Kidmose, Rune Thomas; Andersen, Gregers Rom

    2016-01-01

    Insulin is an essential regulator of glucose homeostasis. In this issue of Structure, Croll et al. (2016) reports a significantly improved model of the Fab-complexed IR ectodomain refined against a dataset extending to 3.3 Å.......Insulin is an essential regulator of glucose homeostasis. In this issue of Structure, Croll et al. (2016) reports a significantly improved model of the Fab-complexed IR ectodomain refined against a dataset extending to 3.3 Å....

  4. Identification of Host Insulin Binding Sites on Schistosoma japonicum Insulin Receptors.

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    Rachel J Stephenson

    Full Text Available Schistosoma japonicum insulin receptors (SjIRs have been identified as encouraging vaccine candidates. Interrupting or blocking the binding between host insulin and the schistosome insulin receptors (IRs may result in reduced glucose uptake leading to starvation and stunting of worms with a reduction in egg output. To further understand how schistosomes are able to exploit host insulin for development and growth, and whether these parasites and their mammalian hosts compete for the same insulin source, we identified insulin binding sites on the SjIRs. Based on sequence analysis and the predicted antigenic structure of the primary sequences of the SjIRs, we designed nine and eleven peptide analogues from SjIR-1 and SjIR-2, respectively. Using the Octet RED system, we identified analogues derived from SjIR-1 (10 and SjIR-2 (20, 21 and 22 with insulin-binding sequences specific for S. japonicum. Nevertheless, the human insulin receptor (HIR may compete with the SjIRs in binding human insulin in other positions which are important for HIR binding to insulin. However, no binding occurred between insulin and parasite analogues derived from SjIR-1 (2, 7 and 8 and SjIR-2 (14, 16 and 18 at the same locations as HIR sequences which have been shown to have strong insulin binding affinities. Importantly, we found two analogues (1 and 3, derived from SjIR-1, and two analogues (13 and 15 derived from SjIR-2, were responsible for the major insulin binding affinity in S. japonicum. These peptide analogues were shown to have more than 10 times (in KD value stronger binding capacity for human insulin compared with peptides derived from the HIR in the same sequence positions. Paradoxically, analogues 1, 3, 13 and 15 do not appear to contain major antigenic determinants which resulted in poor antibody responses to native S. japonicum protein. This argues against their future development as peptide-vaccine candidates.

  5. Autophagy downregulation contributes to insulin resistance mediated injury in insulin receptor knockout podocytes in vitro

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    Ying Xu

    2016-04-01

    Full Text Available It is unknown whether autophagy activity is altered in insulin resistant podocytes and whether autophagy could be a therapeutic target for diabetic nephropathy (DN. Here we used shRNA transfection to knockdown the insulin receptor (IR gene in cultured human immortalized podocytes as an in vitro insulin resistant model. Autophagy related proteins LC3, Beclin, and p62 as well as nephrin, a podocyte injury marker, were assessed using western blot and immunofluorescence staining. Our results show that autophagy is suppressed when podocytes lose insulin sensitivity and that treatment of rapamycin, an mTOR specific inhibitor, could attenuate insulin resistance induced podocytes injury via autophagy activation. The present study deepens our understanding of the role of autophagy in the pathogenesis of DN.

  6. Degradation of pro-insulin-receptor proteins by proteasomes.

    Science.gov (United States)

    Cruz, Miguel; Velasco, Eduardo; Kumate, Jesús

    2004-01-01

    Type-2 diabetes is characterized by hyperinsulinemia, peripheral insulin resistance, and diminished tyrosine phosphorylation activity. It has been recently shown that proteasomes are implicated in the degradation of the insulin receptor substrate-1 (IRS-1) but not in that of the insulin receptor (IR). However, it is unknown whether proteasomes are involved in pro-IR degradation. We used CHO-IR and the 3T3-L1 cells treated with insulin at different concentrations and compared the proteasome activity of IRS-1, IR, and pro-IR degradation either in presence or in absence of lactacystin. A total of 100 nM of insulin allowed degradation of IRS-1 after 6 h of incubation. At 1,000 nM of insulin, pro-IR degradation began at 1 h of incubation, similar to IRS-1 degradation. Surprisingly, at a higher concentration (10 microM) of insulin, a drastic decrease of proteins was observed from the first minute of incubation. This activity was blocked by lactacystin, a specific proteasome inhibitor. According to these results, we propose that pro-IR is degraded by proteasomes.

  7. Signal transduction through the IL-4 and insulin receptor families.

    Science.gov (United States)

    Wang, L M; Keegan, A; Frankel, M; Paul, W E; Pierce, J H

    1995-07-01

    Activation of tyrosine kinase-containing receptors and intracellular tyrosine kinases by ligand stimulation is known to be crucial for mediating initial and subsequent events involved in mitogenic signal transduction. Receptors for insulin and insulin-like growth factor 1 (IGF-1) contain cytoplasmic tyrosine kinase domains that undergo autophosphorylation upon ligand stimulation. Activation of these receptors also leads to pronounced and rapid tyrosine phosphorylation of insulin receptor substrate 1 (IRS-1) in cells of connective tissue origin. A related substrate, designated 4PS, is similarly phosphorylated by insulin and IGF-1 stimulation in many hematopoietic cell types. IRS-1 and 4PS possess a number of tyrosine phosphorylation sites that are within motifs that bind specific SH2-containing molecules known to be involved in mitogenic signaling such as PI-3 kinase, SHPTP-2 (Syp) and Grb-2. Thus, they appear to act as docking substrates for a variety of signaling molecules. The majority of hematopoietic cytokines bind to receptors that do not possess intrinsic kinase activity, and these receptors have been collectively termed as members of the hematopoietin receptor superfamily. Despite their lack of tyrosine kinase domains, stimulation of these receptors has been demonstrated to activate intracellular kinases leading to tyrosine phosphorylation of multiple substrates. Recent evidence has demonstrated that activation of different members of the Janus family of tyrosine kinases is involved in mediating tyrosine phosphorylation events by specific cytokines. Stimulation of the interleukin 4 (IL-4) receptor, a member of the hematopoietin receptor superfamily, is thought to result in activation of Jak1, Jak3, and/or Fes tyrosine kinases.(ABSTRACT TRUNCATED AT 250 WORDS)

  8. Saturated fatty acids inhibit hepatic insulin action by modulating insulin receptor expression and post-receptor signalling.

    Science.gov (United States)

    Ruddock, Mark W; Stein, Andrew; Landaker, Edwin; Park, Jun; Cooksey, Robert C; McClain, Donald; Patti, Mary-Elizabeth

    2008-11-01

    Free fatty acids (FFAs) are proposed to play a pathogenic role in both peripheral and hepatic insulin resistance. We have examined the effect of saturated FFA on insulin signalling (100 nM) in two hepatocyte cell lines. Fao hepatoma cells were treated with physiological concentrations of sodium palmitate (0.25 mM) (16:0) for 0.25-48 h. Palmitate decreased insulin receptor (IR) protein and mRNA expression in a dose- and time-dependent manner (35% decrease at 12 h). Palmitate also reduced insulin-stimulated IR and IRS-2 tyrosine phosphorylation, IRS-2-associated PI 3-kinase activity, and phosphorylation of Akt, p70 S6 kinase, GSK-3 and FOXO1A. Palmitate also inhibited insulin action in hepatocytes derived from wild-type IR (+/+) mice, but was ineffective in IR-deficient (-/-) cells. The effects of palmitate were reversed by triacsin C, an inhibitor of fatty acyl CoA synthases, indicating that palmitoyl CoA ester formation is critical. Neither the non-metabolized bromopalmitate alone nor the medium chain fatty acid octanoate (8:0) produced similar effects. However, the CPT-1 inhibitor (+/-)-etomoxir and bromopalmitate (in molar excess) reversed the effects of palmitate. Thus, the inhibition of insulin signalling by palmitate in hepatoma cells is dependent upon oxidation of fatty acyl-CoA species and requires intact insulin receptor expression.

  9. Insulin Receptor Substrate 2 Is a Negative Regulator of Memory Formation

    Science.gov (United States)

    Irvine, Elaine E.; Drinkwater, Laura; Radwanska, Kasia; Al-Qassab, Hind; Smith, Mark A.; O'Brien, Melissa; Kielar, Catherine; Choudhury, Agharul I.; Krauss, Stefan; Cooper, Jonathan D.; Withers, Dominic J.; Giese, Karl Peter

    2011-01-01

    Insulin has been shown to impact on learning and memory in both humans and animals, but the downstream signaling mechanisms involved are poorly characterized. Insulin receptor substrate-2 (Irs2) is an adaptor protein that couples activation of insulin- and insulin-like growth factor-1 receptors to downstream signaling pathways. Here, we have…

  10. Insulin Receptor Substrate 2 Is a Negative Regulator of Memory Formation

    Science.gov (United States)

    Irvine, Elaine E.; Drinkwater, Laura; Radwanska, Kasia; Al-Qassab, Hind; Smith, Mark A.; O'Brien, Melissa; Kielar, Catherine; Choudhury, Agharul I.; Krauss, Stefan; Cooper, Jonathan D.; Withers, Dominic J.; Giese, Karl Peter

    2011-01-01

    Insulin has been shown to impact on learning and memory in both humans and animals, but the downstream signaling mechanisms involved are poorly characterized. Insulin receptor substrate-2 (Irs2) is an adaptor protein that couples activation of insulin- and insulin-like growth factor-1 receptors to downstream signaling pathways. Here, we have…

  11. Mechanical stretch augments insulin-induced vascular smooth muscle cell proliferation by insulin-like growth factor-1 receptor

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Gang [Department of Pharmacology, Faculty of Medicine, Kagawa University, Kagawa (Japan); Department of Anesthesiology, First Affiliated Hospital of China Medical University, Shenyang (China); Hitomi, Hirofumi, E-mail: hitomi@kms.ac.jp [Department of Pharmacology, Faculty of Medicine, Kagawa University, Kagawa (Japan); Hosomi, Naohisa [Department of Cardiorenal and Cerebrovascular Medicine, Faculty of Medicine, Kagawa University, Kagawa (Japan); Lei, Bai; Nakano, Daisuke [Department of Pharmacology, Faculty of Medicine, Kagawa University, Kagawa (Japan); Deguchi, Kazushi; Mori, Hirohito; Masaki, Tsutomu [Department of Gastroenterology and Neurology, Faculty of Medicine, Kagawa University, Kagawa (Japan); Ma, Hong [Department of Anesthesiology, First Affiliated Hospital of China Medical University, Shenyang (China); Griendling, Kathy K. [Department of Medicine, Division of Cardiology, Emory University School of Medicine, Atlanta, GA (United States); Nishiyama, Akira [Department of Pharmacology, Faculty of Medicine, Kagawa University, Kagawa (Japan)

    2011-10-15

    Insulin resistance and hypertension have been implicated in the pathogenesis of cardiovascular disease; however, little is known about the roles of insulin and mechanical force in vascular smooth muscle cell (VSMC) remodeling. We investigated the contribution of mechanical stretch to insulin-induced VSMC proliferation. Thymidine incorporation was stimulated by insulin in stretched VSMCs, but not in un-stretched VSMCs. Insulin increased 2-deoxy-glucose incorporation in both stretched and un-stretched VSMCs. Mechanical stretch augmented insulin-induced extracellular signal-regulated kinase (ERK) and Akt phosphorylation. Inhibitors of epidermal growth factor (EGF) receptor tyrosine kinase and Src attenuated insulin-induced ERK and Akt phosphorylation, as well as thymidine incorporation, whereas 2-deoxy-glucose incorporation was not affected by these inhibitors. Moreover, stretch augmented insulin-like growth factor (IGF)-1 receptor expression, although it did not alter the expression of insulin receptor and insulin receptor substrate-1. Insulin-induced ERK and Akt activation, and thymidine incorporation were inhibited by siRNA for the IGF-1 receptor. Mechanical stretch augments insulin-induced VSMC proliferation via upregulation of IGF-1 receptor, and downstream Src/EGF receptor-mediated ERK and Akt activation. Similar to in vitro experiment, IGF-1 receptor expression was also augmented in hypertensive rats. These results provide a basis for clarifying the molecular mechanisms of vascular remodeling in hypertensive patients with hyperinsulinemia. -- Highlights: {yields} Mechanical stretch augments insulin-induced VSMC proliferation via IGF-1 receptor. {yields} Src/EGFR-mediated ERK and Akt phosphorylation are augmented in stretched VSMCs. {yields} Similar to in vitro experiment, IGF-1 receptor is increased in hypertensive rats. {yields} Results provide possible mechanisms of vascular remodeling in hypertension with DM.

  12. Drosophila adiponectin receptor in insulin producing cells regulates glucose and lipid metabolism by controlling insulin secretion.

    Directory of Open Access Journals (Sweden)

    Su-Jin Kwak

    Full Text Available Adipokines secreted from adipose tissue are key regulators of metabolism in animals. Adiponectin, one of the adipokines, modulates pancreatic beta cell function to maintain energy homeostasis. Recently, significant conservation between Drosophila melanogaster and mammalian metabolism has been discovered. Drosophila insulin like peptides (Dilps regulate energy metabolism similarly to mammalian insulin. However, in Drosophila, the regulatory mechanism of insulin producing cells (IPCs by adipokine signaling is largely unknown. Here, we describe the discovery of the Drosophila adiponectin receptor and its function in IPCs. Drosophila adiponectin receptor (dAdipoR has high homology with the human adiponectin receptor 1. The dAdipoR antibody staining revealed that dAdipoR was expressed in IPCs of larval and adult brains. IPC- specific dAdipoR inhibition (Dilp2>dAdipoR-Ri showed the increased sugar level in the hemolymph and the elevated triglyceride level in whole body. Dilps mRNA levels in the Dilp2>dAdipoR-Ri flies were similar with those of controls. However, in the Dilp2>dAdipoR-Ri flies, Dilp2 protein was accumulated in IPCs, the level of circulating Dilp2 was decreased, and insulin signaling was reduced in the fat body. In ex vivo fly brain culture with the human adiponectin, Dilp2 was secreted from IPCs. These results indicate that adiponectin receptor in insulin producing cells regulates insulin secretion and controls glucose and lipid metabolism in Drosophila melanogaster. This study demonstrates a new adipokine signaling in Drosophila and provides insights for the mammalian adiponectin receptor function in pancreatic beta cells, which could be useful for therapeutic application.

  13. Drosophila adiponectin receptor in insulin producing cells regulates glucose and lipid metabolism by controlling insulin secretion.

    Science.gov (United States)

    Kwak, Su-Jin; Hong, Seung-Hyun; Bajracharya, Rijan; Yang, Se-Yeol; Lee, Kyu-Sun; Yu, Kweon

    2013-01-01

    Adipokines secreted from adipose tissue are key regulators of metabolism in animals. Adiponectin, one of the adipokines, modulates pancreatic beta cell function to maintain energy homeostasis. Recently, significant conservation between Drosophila melanogaster and mammalian metabolism has been discovered. Drosophila insulin like peptides (Dilps) regulate energy metabolism similarly to mammalian insulin. However, in Drosophila, the regulatory mechanism of insulin producing cells (IPCs) by adipokine signaling is largely unknown. Here, we describe the discovery of the Drosophila adiponectin receptor and its function in IPCs. Drosophila adiponectin receptor (dAdipoR) has high homology with the human adiponectin receptor 1. The dAdipoR antibody staining revealed that dAdipoR was expressed in IPCs of larval and adult brains. IPC- specific dAdipoR inhibition (Dilp2>dAdipoR-Ri) showed the increased sugar level in the hemolymph and the elevated triglyceride level in whole body. Dilps mRNA levels in the Dilp2>dAdipoR-Ri flies were similar with those of controls. However, in the Dilp2>dAdipoR-Ri flies, Dilp2 protein was accumulated in IPCs, the level of circulating Dilp2 was decreased, and insulin signaling was reduced in the fat body. In ex vivo fly brain culture with the human adiponectin, Dilp2 was secreted from IPCs. These results indicate that adiponectin receptor in insulin producing cells regulates insulin secretion and controls glucose and lipid metabolism in Drosophila melanogaster. This study demonstrates a new adipokine signaling in Drosophila and provides insights for the mammalian adiponectin receptor function in pancreatic beta cells, which could be useful for therapeutic application.

  14. Effect of tetrahydrocurcumin on insulin receptor status in type 2 diabetic rats: studies on insulin binding to erythrocytes

    Indian Academy of Sciences (India)

    Pidaran Murugan; Leelavinothan Pari; Chippada Appa Rao

    2008-03-01

    Curcumin is the most active component of turmeric. It is believed that curcumin is a potent antioxidant and anti-inflammatory agent. Tetrahydrocurcumin (THC) is one of the major metabolites of curcumin, and exhibits many of the same physiological and pharmacological activities as curcumin and, in some systems, may exert greater antioxidant activity than curcumin. Using circulating erythrocytes as the cellular mode, the insulin-binding effect of THC and curcumin was investigated. Streptozotocin (STZ)–nicotinamide-induced male Wistar rats were used as the experimental models. THC (80 mg/kg body weight) was administered orally for 45 days. The effect of THC on blood glucose, plasma insulin and insulin binding to its receptor on the cell membrane of erythrocytes were studied. Mean specific binding of insulin was significantly lowered in diabetic rats with a decrease in plasma insulin. This was due to a significant decrease in mean insulin receptors. Erythrocytes from diabetic rats showed a decreased ability for insulin–receptor binding when compared with THC-treated diabetic rats. Scatchard analysis demonstrated that the decrease in insulin binding was accounted for by a decrease in insulin receptor sites per cell, with erythrocytes of diabetic rats having less insulin receptor sites per cell than THC-treated rats. High affinity (Kd1), low affinity (Kd2) and kinetic analyses revealed an increase in the average receptor affinity of erythrocytes from THC-treated rats compared with those of diabetic rats. These results suggest that acute alteration of the insulin receptor on the membranes of erythrocytes occurred in diabetic rats. Treatment with THC significantly improved specific insulin binding to the receptors, with receptor numbers and affinity binding reaching near-normal levels. Our study suggests the mechanism by which THC increases the number of total cellular insulin binding sites resulting in a significant increase in plasma insulin. The effect of THC is

  15. Cloning and characterisation of Schistosoma japonicum insulin receptors.

    Directory of Open Access Journals (Sweden)

    Hong You

    Full Text Available BACKGROUND: Schistosomes depend for growth and development on host hormonal signals, which may include the insulin signalling pathway. We cloned and assessed the function of two insulin receptors from Schistosoma japonicum in order to shed light on their role in schistosome biology. METHODOLOGY/PRINCIPAL FINDINGS: We isolated, from S. japonicum, insulin receptors 1 (SjIR-1 and 2 (SjIR-2 sharing close sequence identity to their S. mansoni homologues (SmIR-1 and SmIR-2. SjIR-1 is located on the tegument basal membrane and the internal epithelium of adult worms, whereas SjIR-2 is located in the parenchyma of males and the vitelline tissue of females. Phylogenetic analysis showed that SjIR-2 and SmIR-2 are close to Echinococcus multilocularis insulin receptor (EmIR, suggesting that SjIR-2, SmIR-2 and EmIR share similar roles in growth and development in the three taxa. Structure homology modelling recovered the conserved structure between the SjIRs and Homo sapiens IR (HIR implying a common predicted binding mechanism in the ligand domain and the same downstream signal transduction processing in the tyrosine kinase domain as in HIR. Two-hybrid analysis was used to confirm that the ligand domains of SjIR-1 and SjIR-2 contain the insulin binding site. Incubation of adult worms in vitro, both with a specific insulin receptor inhibitor and anti-SjIRs antibodies, resulted in a significant decrease in worm glucose levels, suggesting again the same function for SjIRs in regulating glucose uptake as described for mammalian cells. CONCLUSIONS: Adult worms of S. japonicum possess insulin receptors that can specifically bind to insulin, indicating that the parasite can utilize host insulin for development and growth by sharing the same pathway as mammalian cells in regulating glucose uptake. A complete understanding of the role of SjIRs in the biology of S. japonicum may result in their use as new targets for drug and vaccine development against

  16. Insulin Resistance Induced by Hyperinsulinemia Coincides with a Persistent Alteration at the Insulin Receptor Tyrosine Kinase Domain

    Science.gov (United States)

    Catalano, Karyn J.; Maddux, Betty A.; Szary, Jaroslaw; Youngren, Jack F.; Goldfine, Ira D.; Schaufele, Fred

    2014-01-01

    Insulin resistance, the diminished response of target tissues to insulin, is associated with the metabolic syndrome and a predisposition towards diabetes in a growing proportion of the worldwide population. Under insulin resistant states, the cellular response of the insulin signaling pathway is diminished and the body typically responds by increasing serum insulin concentrations to maintain insulin signaling. Some evidence indicates that the increased insulin concentration may itself further dampen insulin response. If so, insulin resistance would worsen as the level of circulating insulin increases during compensation, which could contribute to the transition of insulin resistance to more severe disease. Here, we investigated the consequences of excess insulin exposure to insulin receptor (IR) activity. Cells chronically exposed to insulin show a diminished the level of IR tyrosine and serine autophosphorylation below that observed after short-term insulin exposure. The diminished IR response did not originate with IR internalization since IR amounts at the cell membrane were similar after short- and long-term insulin incubation. Förster resonance energy transfer between fluorophores attached to the IR tyrosine kinase (TK) domain showed that a change in the TK domain occurred upon prolonged, but not short-term, insulin exposure. Even though the altered ‘insulin refractory’ IR TK FRET and IR autophosphorylation levels returned to baseline (non-stimulated) levels after wash-out of the original insulin stimulus, subsequent short-term exposure to insulin caused immediate re-establishment of the insulin-refractory levels. This suggests that some cell-based ‘memory’ of chronic hyperinsulinemic exposure acts directly at the IR. An improved understanding of that memory may help define interventions to reset the IR to full insulin responsiveness and impede the progression of insulin resistance to more severe disease states. PMID:25259572

  17. Fiber mediated receptor masking in non-infected bystander cells restricts adenovirus cell killing effect but promotes adenovirus host co-existence.

    Directory of Open Access Journals (Sweden)

    Johan Rebetz

    Full Text Available The basic concept of conditionally replicating adenoviruses (CRAD as oncolytic agents is that progenies generated from each round of infection will disperse, infect and kill new cancer cells. However, CRAD has only inhibited, but not eradicated tumor growth in xenograft tumor therapy, and CRAD therapy has had only marginal clinical benefit to cancer patients. Here, we found that CRAD propagation and cancer cell survival co-existed for long periods of time when infection was initiated at low multiplicity of infection (MOI, and cancer cell killing was inefficient and slow compared to the assumed cell killing effect upon infection at high MOI. Excessive production of fiber molecules from initial CRAD infection of only 1 to 2% cancer cells and their release prior to the viral particle itself caused a tropism-specific receptor masking in both infected and non-infected bystander cells. Consequently, the non-infected bystander cells were inefficiently bound and infected by CRAD progenies. Further, fiber overproduction with concomitant restriction of adenovirus spread was observed in xenograft cancer therapy models. Besides the CAR-binding Ad4, Ad5, and Ad37, infection with CD46-binding Ad35 and Ad11 also caused receptor masking. Fiber overproduction and its resulting receptor masking thus play a key role in limiting CRAD functionality, but potentially promote adenovirus and host cell co-existence. These findings also give important clues for understanding mechanisms underlying the natural infection course of various adenoviruses.

  18. Structural Dynamics of Insulin Receptor and Transmembrane Signaling.

    Science.gov (United States)

    Tatulian, Suren A

    2015-09-15

    The insulin receptor (IR) is a (αβ)2-type transmembrane tyrosine kinase that plays a central role in cell metabolism. Each αβ heterodimer consists of an extracellular ligand-binding α-subunit and a membrane-spanning β-subunit that comprises the cytoplasmic tyrosine kinase (TK) domain and the phosphorylation sites. The α- and β-subunits are linked via a single disulfide bridge, and the (αβ)2 tetramer is formed by disulfide bonds between the α-chains. Insulin binding induces conformational changes in IR that reach the intracellular β-subunit followed by a protein phosphorylation and activation cascade. Defects in this signaling process, including IR dysfunction caused by mutations, result in type 2 diabetes. Rational drug design aimed at treatment of diabetes relies on knowledge of the detailed structure of IR and the dynamic structural transformations during transmembrane signaling. Recent X-ray crystallographic studies have provided important clues about the mode of binding of insulin to IR, the resulting structural changes and their transmission to the TK domain, but a complete understanding of the structural basis underlying insulin signaling has not been achieved. This review presents a critical analysis of the current status of the structure-function relationship of IR, with a comparative assessment of the other IR family receptors, and discusses potential advancements that may provide insight into the molecular mechanism of insulin signaling.

  19. Founder effect in the Horn of Africa for an insulin receptor mutation that may impair receptor recycling

    DEFF Research Database (Denmark)

    Raffan, E; Soos, M A; Rocha, N;

    2011-01-01

    Genetic insulin receptoropathies are a rare cause of severe insulin resistance. We identified the Ile119Met missense mutation in the insulin receptor INSR gene, previously reported in a Yemeni kindred, in four unrelated patients with Somali ancestry. We aimed to investigate a possible genetic...... founder effect, and to study the mechanism of loss of function of the mutant receptor....

  20. Targeting Insulin Receptor with a Novel Internalizing Aptamer

    Directory of Open Access Journals (Sweden)

    Margherita Iaboni

    2016-01-01

    Full Text Available Nucleic acid-based aptamers are emerging as therapeutic antagonists of disease-associated proteins such as receptor tyrosine kinases. They are selected by an in vitro combinatorial chemistry approach, named Systematic Evolution of Ligands by Exponential enrichment (SELEX, and thanks to their small size and unique chemical characteristics, they possess several advantages over antibodies as diagnostics and therapeutics. In addition, aptamers that rapidly internalize into target cells hold as well great potential for their in vivo use as delivery tools of secondary therapeutic agents. Here, we describe a nuclease resistant RNA aptamer, named GL56, which specifically recognizes the insulin receptor (IR. Isolated by a cell-based SELEX method that allows enrichment for internalizing aptamers, GL56 rapidly internalizes into target cells and is able to discriminate IR from the highly homologous insulin-like growth factor receptor 1. Notably, when applied to IR expressing cancer cells, the aptamer inhibits IR dependent signaling. Given the growing interest in the insulin receptor as target for cancer treatment, GL56 reveals a novel molecule with great translational potential as inhibitor and delivery tool for IR-dependent cancers.

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

    Science.gov (United States)

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

    2016-08-05

    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. Copyright © 2016. Published by Elsevier Inc.

  2. A docking study of insulin with LI-CR-L2 ecto domain of insulin receptor: an easy way for preliminary screening of novel anti-diabetic peptides

    OpenAIRE

    Bhattacharyya, Rajasri; Banerjee, Dibyajyoti

    2012-01-01

    Although interaction of human insulin with its receptor is studied to considerable extent such studies are currently lacking with recombinant insulin in-spite of its rampant clinical use. It is known that at molecular level the interaction of recombinant insulin with insulin receptor is similar to human insulin but not exactly same. With the increasing incidence of diabetes throughout the globe use of recombinant insulin is also increasing at a considerable rate. Therefore it is need of the h...

  3. Molecular Recognition of Insulin by a Synthetic Receptor

    Energy Technology Data Exchange (ETDEWEB)

    Chinai, Jordan M.; Taylor, Alexander B.; Ryno, Lisa M.; Hargreaves, Nicholas D.; Morris, Christopher A.; Hart, P. John; Urbach, Adam R. (Texas-HSC); (Trinity U)

    2011-08-29

    The discovery of molecules that bind tightly and selectively to desired proteins continues to drive innovation at the interface of chemistry and biology. This paper describes the binding of human insulin by the synthetic receptor cucurbit[7]uril (Q7) in vitro. Isothermal titration calorimetry and fluorescence spectroscopy experiments show that Q7 binds to insulin with an equilibrium association constant of 1.5 x 10{sup 6} M{sup -1} and with 50-100-fold selectivity versus proteins that are much larger but lack an N-terminal aromatic residue, and with >1000-fold selectivity versus an insulin variant lacking the N-terminal phenylalanine (Phe) residue. The crystal structure of the Q7{center_dot}insulin complex shows that binding occurs at the N-terminal Phe residue and that the N-terminus unfolds to enable binding. These findings suggest that site-selective recognition is based on the properties inherent to a protein terminus, including the unique chemical epitope presented by the terminal residue and the greater freedom of the terminus to unfold, like the end of a ball of string, to accommodate binding. Insulin recognition was predicted accurately from studies on short peptides and exemplifies an approach to protein recognition by targeting the terminus.

  4. Aminoacid polymorphisms of insulin receptor substrate-1 in non-insulin-dependent diabetes mellitus

    DEFF Research Database (Denmark)

    Almind, K; Bjørbaek, C; Vestergaard, H

    1993-01-01

    the insulin-receptor and IGF1-receptor kinases with enzymes that regulate cellular metabolism and growth. Single-stranded conformation polymorphism analysis and direct nucleotide sequencing were applied to genomic DNA from 86 unrelated patients with NIDDM and 76 normoglycaemic controls. 10 of the patients...... with NIDDM and 3 of the controls were heterozygous at codon 972 for a polymorphism in which glycine was substituted with arginine. Moreover, at codon 513, 6 patients with NIDDM and 2 controls had a heterozygous polymorphism with a transition from alanine to proline. None of the polymorphism carriers had both...... aminoacid variants and the total allelic frequency of IRS-1 polymorphisms was about three times higher in patients with NIDDM than in controls (p = 0.02). Both aminoacid substitutions were located close to tyrosine phosphorylation motifs that are putative recognition sites for insulin and IGF1 signal...

  5. APPL1 potentiates insulin sensitivity by facilitating the binding of IRS1/2 to the insulin receptor.

    Science.gov (United States)

    Ryu, Jiyoon; Galan, Amanda K; Xin, Xiaoban; Dong, Feng; Abdul-Ghani, Muhammad A; Zhou, Lijun; Wang, Changhua; Li, Cuiling; Holmes, Bekke M; Sloane, Lauren B; Austad, Steven N; Guo, Shaodong; Musi, Nicolas; DeFronzo, Ralph A; Deng, Chuxia; White, Morris F; Liu, Feng; Dong, Lily Q

    2014-05-22

    Binding of insulin receptor substrate proteins 1 and 2 (IRS1/2) to the insulin receptor (IR) is essential for the regulation of insulin sensitivity and energy homeostasis. However, the mechanism of IRS1/2 recruitment to the IR remains elusive. Here, we identify adaptor protein APPL1 as a critical molecule that promotes IRS1/2-IR interaction. APPL1 forms a complex with IRS1/2 under basal conditions, and this complex is then recruited to the IR in response to insulin or adiponectin stimulation. The interaction between APPL1 and IR depends on insulin- or adiponectin-stimulated APPL1 phosphorylation, which is greatly reduced in insulin target tissues in obese mice. appl1 deletion in mice consistently leads to systemic insulin resistance and a significant reduction in insulin-stimulated IRS1/2, but not IR, tyrosine phosphorylation, indicating that APPL1 sensitizes insulin signaling by acting at a site downstream of the IR. Our study uncovers a mechanism regulating insulin signaling and crosstalk between the insulin and adiponectin pathways.

  6. APPL1 Potentiates Insulin Sensitivity by Facilitating the Binding of IRS1/2 to the Insulin Receptor

    Directory of Open Access Journals (Sweden)

    Jiyoon Ryu

    2014-05-01

    Full Text Available Binding of insulin receptor substrate proteins 1 and 2 (IRS1/2 to the insulin receptor (IR is essential for the regulation of insulin sensitivity and energy homeostasis. However, the mechanism of IRS1/2 recruitment to the IR remains elusive. Here, we identify adaptor protein APPL1 as a critical molecule that promotes IRS1/2-IR interaction. APPL1 forms a complex with IRS1/2 under basal conditions, and this complex is then recruited to the IR in response to insulin or adiponectin stimulation. The interaction between APPL1 and IR depends on insulin- or adiponectin-stimulated APPL1 phosphorylation, which is greatly reduced in insulin target tissues in obese mice. appl1 deletion in mice consistently leads to systemic insulin resistance and a significant reduction in insulin-stimulated IRS1/2, but not IR, tyrosine phosphorylation, indicating that APPL1 sensitizes insulin signaling by acting at a site downstream of the IR. Our study uncovers a mechanism regulating insulin signaling and crosstalk between the insulin and adiponectin pathways.

  7. S961, an insulin receptor antagonist causes hyperinsulinemia, insulin-resistance and depletion of energy stores in rats

    Energy Technology Data Exchange (ETDEWEB)

    Vikram, Ajit [Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), SAS Nagar, Mohali, Punjab 160 062 (India); Jena, Gopabandhu, E-mail: gbjena@gmail.com [Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), SAS Nagar, Mohali, Punjab 160 062 (India)

    2010-07-23

    Research highlights: {yields}Insulin receptor antagonist S961 causes hyperglycemia, hyperinsulinemia and insulin resistance in rats. {yields}Peroxysome-proliferator-activated-receptor-gamma agonist pioglitazone improves S961 induced hyperglycemia and glucose intolerance. {yields}Long term treatment with insulin receptor antagonist S961 results in the decreased adiposity and hepatic glycogen content. {yields}Improvement in the hyperglycemia and glucose intolerance by pioglitazone clearly demonstrates that S961 treated rats can be successfully used to screen the novel therapeutic interventions having potential to improve glucose disposal through receptor independent mechanisms. -- Abstract: Impairment in the insulin receptor signaling and insulin mediated effects are the key features of type 2 diabetes. Here we report that S961, a peptide insulin receptor antagonist induces hyperglycemia, hyperinsulinemia ({approx}18-fold), glucose intolerance and impairment in the insulin mediated glucose disposal in the Sprague-Dawley rats. Further, long-term S961 treatment (15 day, 10 nM/kg/day) depletes energy storage as evident from decrease in the adiposity and hepatic glycogen content. However, peroxysome-proliferator-activated-receptor-gamma (PPAR{gamma}) agonist pioglitazone significantly (P < 0.001) restored S961 induced hyperglycemia (196.73 {+-} 16.32 vs. 126.37 {+-} 27.07 mg/dl) and glucose intolerance ({approx}78%). Improvement in the hyperglycemia and glucose intolerance by pioglitazone clearly demonstrates that S961 treated rats can be successfully used to screen the novel therapeutic interventions having potential to improve glucose disposal through receptor independent mechanisms. Further, results of the present study reconfirms and provide direct evidence to the crucial role of insulin receptor signaling in the glucose homeostasis and fuel metabolism.

  8. Potentiation of Insulin-Mediated Glucose Lowering without Elevated Hypoglycemia Risk by a Small Molecule Insulin Receptor Modulator

    Science.gov (United States)

    Wu, Margaret; Dai, Ge; Yao, Jun; Hoyt, Scott; Wang, Liangsu; Mu, James

    2015-01-01

    Insulin resistance is the key feature of type 2 diabetes and is manifested as attenuated insulin receptor (IR) signaling in response to same levels of insulin binding. Several small molecule IR activators have been identified and reported to exhibit insulin sensitization properties. One of these molecules, TLK19781 (Cmpd1), was investigated to examine its IR sensitizing action in vivo. Our data demonstrate that Cmpd1, at doses that produced minimal efficacy in the absence of insulin, potentiated insulin action during an OGTT in non-diabetic mice and enhanced insulin-mediated glucose lowering in diabetic mice. Interestingly, different from insulin alone, Cmpd1 combined with insulin showed enhanced efficacy and duration of action without increased hypoglycemia. To explore the mechanism underlying the apparent glucose dependent efficacy, tissue insulin signaling was compared in healthy and diabetic mice. Cmpd1 enhanced insulin’s effects on IR phosphorylation in both healthy and diabetic mice. In contrast, the compound potentiated insulin’s effects on Akt phosphorylation in diabetic but not in non-diabetic mice. These differential effects on signaling corresponding to glucose levels could be part of the mechanism for reduced hypoglycemia risk. The in vivo efficacy of Cmpd1 is specific and dependent on IR expression. Results from these studies support the idea of targeting IR for insulin sensitization, which carries low hypoglycemia risk by standalone treatment and could improve the effectiveness of insulin therapies. PMID:25799496

  9. Pharmacologic inhibition of ghrelin receptor signaling is insulin sparing and promotes insulin sensitivity.

    Science.gov (United States)

    Longo, Kenneth A; Govek, Elizabeth K; Nolan, Anna; McDonagh, Thomas; Charoenthongtrakul, Soratree; Giuliana, Derek J; Morgan, Kristen; Hixon, Jeffrey; Zhou, Chaoseng; Kelder, Bruce; Kopchick, John J; Saunders, Jeffrey O; Navia, Manuel A; Curtis, Rory; DiStefano, Peter S; Geddes, Brad J

    2011-10-01

    Ghrelin influences a variety of metabolic functions through a direct action at its receptor, the GhrR (GhrR-1a). Ghrelin knockout (KO) and GhrR KO mice are resistant to the negative effects of high-fat diet (HFD) feeding. We have generated several classes of small-molecule GhrR antagonists and evaluated whether pharmacologic blockade of ghrelin signaling can recapitulate the phenotype of ghrelin/GhrR KO mice. Antagonist treatment blocked ghrelin-induced and spontaneous food intake; however, the effects on spontaneous feeding were absent in GhrR KO mice, suggesting target-specific effects of the antagonists. Oral administration of antagonists to HFD-fed mice improved insulin sensitivity in both glucose tolerance and glycemic clamp tests. The insulin sensitivity observed was characterized by improved glucose disposal with dramatically decreased insulin secretion. It is noteworthy that these results mimic those obtained in similar tests of HFD-fed GhrR KO mice. HFD-fed mice treated for 56 days with antagonist experienced a transient decrease in food intake but a sustained body weight decrease resulting from decreased white adipose, but not lean tissue. They also had improved glucose disposal and a striking reduction in the amount of insulin needed to achieve this. These mice had reduced hepatic steatosis, improved liver function, and no evidence of systemic toxicity relative to controls. Furthermore, GhrR KO mice placed on low- or high-fat diets had lifespans similar to the wild type, emphasizing the long-term safety of ghrelin receptor blockade. We have therefore demonstrated that chronic pharmacologic blockade of the GhrR is an effective and safe strategy for treating metabolic syndrome.

  10. Pinitol supplementation does not affect insulin-mediated glucose metabolism and muscle insulin receptor content and phosphorylation in older humans.

    Science.gov (United States)

    Campbell, Wayne W; Haub, Mark D; Fluckey, James D; Ostlund, Richard E; Thyfault, John P; Morse-Carrithers, Hannah; Hulver, Matthew W; Birge, Zonda K

    2004-11-01

    This study assessed the effect of oral pinitol supplementation on oral and intravenous glucose tolerances and on skeletal muscle insulin receptor content and phosphorylation in older people. Fifteen people (6 men, 9 women; age 66 +/- 8 y; BMI 27.9 +/- 3.3 kg/m(2); hemoglobin A1c 5.39 +/- 0.46%, mean +/- SD) completed a 7-wk protocol. Subjects were randomly assigned to groups that during wk 2-7 consumed twice daily either a non-nutritive beverage (Placebo group, n = 8) or the same beverage with 1000 mg pinitol dissolved into it (Pinitol group, n = 7, total dose = 2000 mg pinitol/d). Testing was done at wk 1 and wk 7. In the Pinitol group with supplementation, 24-h urinary pinitol excretion increased 17-fold. The fasting concentrations of glucose, insulin, and C-peptide, and the 180-min area under the curve for these compounds, in response to oral (75 g) and intravenous (300 mg/kg) glucose tolerance challenges, were unchanged from wk 1 to wk 7 and were not influenced by pinitol. Also, pinitol did not affect indices of hepatic and whole-body insulin sensitivity from the oral glucose tolerance test and indices of insulin sensitivity, acute insulin response to glucose, and glucose effectiveness from the intravenous glucose tolerance test, estimated using minimal modeling. Pinitol did not differentially affect total insulin receptor content and insulin receptor phosphotyrosine 1158 and insulin receptor phosphotyrosine 1162/1163 activation in vastus lateralis samples taken during an oral-glucose-induced hyperglycemic and hyperinsulinemic state. These data suggest that pinitol supplementation does not influence whole-body insulin-mediated glucose metabolism and muscle insulin receptor content and phosphorylation in nondiabetic, older people.

  11. Structure and dynamics of the insulin receptor: implications for receptor activation and drug discovery.

    Science.gov (United States)

    Ye, Libin; Maji, Suvrajit; Sanghera, Narinder; Gopalasingam, Piraveen; Gorbunov, Evgeniy; Tarasov, Sergey; Epstein, Oleg; Klein-Seetharaman, Judith

    2017-07-01

    Recently, major progress has been made in uncovering the mechanisms of how insulin engages its receptor and modulates downstream signal transduction. Here, we present in detail the current structural knowledge surrounding the individual components of the complex, binding sites, and dynamics during the activation process. A novel kinase triggering mechanism, the 'bow-arrow model', is proposed based on current knowledge and computational simulations of this system, in which insulin, after its initial interaction with binding site 1, engages with site 2 between the fibronectin type III (FnIII)-1 and -2 domains, which changes the conformation of FnIII-3 and eventually translates into structural changes across the membrane. This model provides a new perspective on the process of insulin binding to its receptor and, thus, could lead to future novel drug discovery efforts. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. [Differences in dynamics of insulin and insulin-like growth I (IGF-I) receptors internalization in isolated rat hepatocytes].

    Science.gov (United States)

    2013-01-01

    Insulin and IGF-I are two related peptides performing in the mammalian body functionally different roles of the metabolic and growth hormones, respectively. Internalization of the insulin-receptor complex (IRC) is the most important chain of mechanism of the action of hormone. To elucidate differences in the main stages of internalization of the two related hormones, the internalization dynamics of 125I-insulin and 125I-IGF-I was traced in isolated rat hepatocytes at 37 and 12 degrees C. There were established marked differences in the process of internalization of labeled hormones, which is stimulated by insulin and IGF-I. At 37 degrees C the insulin-stimulated internalization, unlike the process initiated by IGF-I, did not reach the maximal level for 1 h of incubation. However, essential differences in the internalization course of these two related peptide were obvious at the temperature of 12 degrees C. The internalization level of insulin receptors at 12 degrees C decreased by one third in spite of a significant increase of the insulin receptor binding on the hepatocytes plasma membrane. At 12 degrees C a slight decrease of the proportion of intracellular 125I-IGF-I correlated with a decrease in the 125I-IGF-I binding to receptors on the cell membrane. Internalization of IGF-I receptors was not affected by low temperature, as neither its level, nor the rate changed at 12 degrees C. The paradoxical decrease of the insulin-stimulated internalization at low temperature seems to represent a peculiar "inhibition mechanism" of immersion of IRC into the cell, which leads to accumulation of the complexes on the cell surface and possibly to a readjustment of the insulin biological activity. The resistance of internalization of the IGF-I receptor to cold seems to be related to the more ancient origin of this mechanism in the poikilothermal vertebrates.

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

    Directory of Open Access Journals (Sweden)

    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.

  14. Substitution of isoleucine for methionine at position 1153 in the beta-subunit of the human insulin receptor. A mutation that impairs receptor tyrosine kinase activity, receptor endocytosis, and insulin action.

    Science.gov (United States)

    Cama, A; Quon, M J; de la Luz Sierra, M; Taylor, S I

    1992-04-25

    The intracellular domain of the insulin receptor possesses activity as a tyrosine-specific protein kinase. The receptor tyrosine kinase is stimulated by insulin binding to the extracellular domain of the receptor. Previously, we have identified a patient with a genetic form of insulin resistance who is heterozygous for a mutation substituting Ile for Met1153 in the tyrosine kinase domain of the receptor near the cluster of the three major autophosphorylation sites (Tyr1158, Tyr1162, and Tyr1163). In this investigation, the Ile1153 mutant receptor was expressed by transfection of mutant cDNA into NIH-3T3 cells. The mutation impairs receptor tyrosine kinase activity and also inhibits the ability of insulin to stimulate 2-deoxyglucose uptake and thymidine incorporation. These data support the hypothesis that the receptor tyrosine activity plays a necessary role in the ability of the receptor to mediate insulin action in vivo. Furthermore, expression of the Ile1153 mutant receptor exerted a dominant negative effect to inhibit the ability of endogenous murine receptors for insulin and insulin-like growth factor I to mediate their actions upon the cell. This observation is consistent with previous suggestions that mutant receptors dimerize with wild type receptors, thereby creating hybrid molecules which lack biological activity. The dominant negative effect of the mutant receptor may explain the dominant mode of inheritance of insulin resistance caused by the Ile1153 mutation. Finally, the mutation inhibits the ability of insulin to stimulate receptor endocytosis. This may explain the normal number of insulin receptors on the surface of the patient's cells in vivo. Despite the presence of markedly elevated levels of insulin in the patient's plasma, the receptors were resistant to down-regulation.

  15. Increased interaction with insulin receptor substrate 1, a novel abnormality in insulin resistance and type 2 diabetes

    DEFF Research Database (Denmark)

    Caruso, Michael; Ma, Danjun; Msallaty, Zaher

    2014-01-01

    and disease conditions. We used a proteomic approach to assess IRS1 interaction partners in skeletal muscle from lean healthy control subjects (LCs), obese insulin-resistant nondiabetic control subjects (OCs), and participants with T2D before and after insulin infusion. We identified 113 novel endogenous IRS1...... in obesity and T2D in humans, provides new insights into the molecular mechanism of insulin resistance and identifies new targets for T2D drug development.......Insulin receptor substrate 1 (IRS1) is a key mediator of insulin signal transduction. Perturbations involving IRS1 complexes may lead to the development of insulin resistance and type 2 diabetes (T2D). Surprisingly little is known about the proteins that interact with IRS1 in humans under health...

  16. Hyperinsulinemia is Associated with Increased Soluble Insulin Receptors Release from Hepatocytes

    Science.gov (United States)

    Hiriart, Marcia; Sanchez-Soto, Carmen; Diaz-Garcia, Carlos Manlio; Castanares, Diana T.; Avitia, Morena; Velasco, Myrian; Mas-Oliva, Jaime; Macias-Silva, Marina; González-Villalpando, Clicerio; Delgado-Coello, Blanca; Sosa-Garrocho, Marcela; Vidaltamayo, Román; Fuentes-Silva, Deyanira

    2014-01-01

    It has been generally assumed that insulin circulates freely in blood. However it can also interact with plasma proteins. Insulin receptors are located in the membrane of target cells and consist of an alpha and beta subunits with a tyrosine kinase cytoplasmic domain. The ectodomain, called soluble insulin receptor (SIR) has been found elevated in patients with diabetes mellitus. We explored if insulin binds to SIRs in circulation under physiological conditions and hypothesize that this SIR may be released by hepatocytes in response to high insulin concentrations. The presence of SIR in rat and human plasmas and the culture medium of hepatocytes was explored using Western blot analysis. A purification protocol was performed to isolated SIR using affinity, gel filtration, and ion exchange chromatographies. A modified reverse hemolytic plaque assay was used to measure SIR release from cultured hepatocytes. Incubation with 1 nmol l−1 insulin induces the release of the insulin receptor ectodomains from normal rat hepatocytes. This effect can be partially prevented by blocking protease activity. Furthermore, plasma levels of SIR were higher in a model of metabolic syndrome, where rats are hyperinsulinemic. We also found increased SIR levels in hyperinsulinemic humans. SIR may be an important regulator of the amount of free insulin in circulation. In hyperinsulinemia, the amount of this soluble receptor increases and this could lead to higher amounts of insulin bound to this receptor, rather than free insulin, which is the biologically active form of the hormone. This observation could enlighten the mechanisms of insulin resistance. PMID:24995000

  17. Hyperinsulinemia is associated with increased soluble insulin receptors release from hepatocytes

    Directory of Open Access Journals (Sweden)

    Marcia eHiriart

    2014-06-01

    Full Text Available It has been generally assumed that insulin circulates freely in blood. However it can also interact with plasma proteins. Insulin receptors are located in the membrane of target cells and consist of an alpha and beta subunits with a tyrosine kinase cytoplasmic domain. The ectodomain, called soluble insulin receptor (SIR has been found elevated in patients with diabetes mellitus. We explored if insulin binds to SIRs in circulation under physiological conditions and hypothesize that this SIR may be released by hepatocytes in response to high insulin concentrations. The presence of SIR in rat and human plasmas and the culture medium of hepatocytes was explored using Western blot analysis. A purification protocol was performed to isolated SIR using affinity, gel filtration and ion exchange chromatographies. A modified reverse hemolytic plaque assay was used to measure SIR release from cultured hepatocytes. Incubation with 1 nmol l-1 insulin induces the release of the insulin receptor ectodomains from normal rat hepatocytes. This effect can be partially prevented by blocking protease activity. Furthermore, plasma levels of SIR were higher in a model of metabolic syndrome, where rats are hyperinsulinemic. We also found increased SIR levels in hyperinsulinemic humans. SIR may be an important regulator of the amount of free insulin in circulation. In hyperinsulinemia the amount of this soluble receptor increases, this could lead to higher amounts of insulin bound to this receptor, rather than free insulin, which is the biologically active form of the hormone. This observation could enlighten the mechanisms of insulin resistance.

  18. Increased abundance of insulin/insulin-like growth factor-I hybrid receptors in skeletal muscle of obese subjects is correlated with in vivo insulin sensitivity.

    Science.gov (United States)

    Federici, M; Porzio, O; Lauro, D; Borboni, P; Giovannone, B; Zucaro, L; Hribal, M L; Sesti, G

    1998-08-01

    We reported that in noninsulin-dependent diabetes melitus (NIDDM) patients expression of insulin/insulin-like growth factor I (IGF-I) hybrid receptors is increased in insulin target tissues. Whether this is a defect associated with NIDDM or represents a generalized abnormality associated with insulin resistant states is still unsettled. To address this, we applied a microwell-based immunoassay to measure abundance of insulin receptors, type 1 IGF receptors, and hybrid receptors in muscle of eight normal and eight obese subjects. Maximal insulin binding to insulin receptors was lower in obese than in control subjects (B/T = 1.8 +/- 0.20 and 2.6 +/- 0.30; P < 0.03, respectively) and was negatively correlated with insulinemia (r = -0.60; P < 0.01). Maximal IGF-I binding to type 1 IGF receptors was higher in obese than in controls (B/T = 1.9 +/- 0.20 and 0.86 +/- 0.10; P < 0.0001, respectively) and was negatively correlated with plasma IGF-I levels (r = -0.69; P < 0.003). Hybrid receptor abundance was higher in obese than in normal subjects (B/T = 1.21 +/- 0.14 and 0.44 +/- 0.06; P < 0.0003, respectively) and was negatively correlated with insulin binding (r = -0.60; P < 0.01) and positively correlated with IGF-I binding (r = 0.92; P < 0.0001). Increased abundance of hybrids was correlated with insulinemia (r = 0.70; P < 0.002) and body mass index (r = 0.71; P < 0.0019), whereas it was negatively correlated with in vivo insulin sensitivity measured by ITT (r = -0.67; P < 0.016). These results indicate that downregulation of insulin receptors or upregulation of type 1 IGF receptors because of changes in plasma insulin and IGF-I levels may result in modifications in hybrid receptor abundance.

  19. Nephrin Contributes to Insulin Secretion and Affects Mammalian Target of Rapamycin Signaling Independently of Insulin Receptor.

    Science.gov (United States)

    Villarreal, Rodrigo; Mitrofanova, Alla; Maiguel, Dony; Morales, Ximena; Jeon, Jongmin; Grahammer, Florian; Leibiger, Ingo B; Guzman, Johanna; Fachado, Alberto; Yoo, Tae H; Busher Katin, Anja; Gellermann, Jutta; Merscher, Sandra; Burke, George W; Berggren, Per-Olof; Oh, Jun; Huber, Tobias B; Fornoni, Alessia

    2016-04-01

    Nephrin belongs to a family of highly conserved proteins with a well characterized function as modulators of cell adhesion and guidance, and nephrin may have a role in metabolic pathways linked to podocyte and pancreatic β-cell survival. However, this role is incompletely characterized. In this study, we developed floxed nephrin mice for pancreatic β-cell-specific deletion of nephrin, which had no effect on islet size and glycemia. Nephrin deficiency, however, resulted in glucose intolerance in vivo and impaired glucose-stimulated insulin release ex vivo Glucose intolerance was also observed in eight patients with nephrin mutations compared with three patients with other genetic forms of nephrotic syndrome or nine healthy controls.In vitro experiments were conducted to investigate if nephrin affects autocrine signaling through insulin receptor A (IRA) and B (IRB), which are both expressed in human podocytes and pancreatic islets. Coimmunoprecipitation of nephrin and IRB but not IRA was observed and required IR phosphorylation. Nephrin per se was sufficient to induce phosphorylation of p70S6K in an phosphatidylinositol 3-kinase-dependent but IR/Src-independent manner, which was not augmented by exogenous insulin. These results suggest a role for nephrin as an independent modulator of podocyte and pancreatic β-cell nutrient sensing in the fasting state and the potential of nephrin as a drug target in diabetes.

  20. Comparative effects of several simple carbohydrates on erythrocyte insulin receptors in obese subjects.

    Science.gov (United States)

    Rizkalla, S W; Baigts, F; Fumeron, F; Rabillon, B; Bayn, P; Ktorza, A; Spielmann, D; Apfelbaum, M

    1986-09-01

    The effects of simple carbohydrates on erythrocyte insulin receptors, plasma insulin and plasma glucose were studied during four hypocaloric, hyperproteic, diets. One diet contained no carbohydrate; the other three contained 36 g of either glucose, galactose or fructose. These diets were given for a 14-day period to groups of moderately obese subjects. The hypocaloric carbohydrate-free diet produced a decrease in plasma insulin and glucose concentrations concomitant with an increase in the number of insulin receptors. A similar increase in insulin receptor number was found when the diet was supplemented with glucose or galactose, but not with fructose. The presence of fructose in the diet prevented any increase in insulin receptor number.

  1. Unique expression pattern of the three insulin receptor family members in the rat mammary gland

    DEFF Research Database (Denmark)

    Hvid, Henning; Klopfleisch, Robert; Vienberg, Sara Gry

    2011-01-01

    Supra-pharmacological doses of the insulin analog X10 (AspB10) increased the incidence of mammary tumors in female Sprague-Dawley rats in chronic toxicity studies, most likely via receptor-mediated mechanisms. However, little is known about the expression of the insulin receptor family in the rat...

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

    DEFF Research Database (Denmark)

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

    1999-01-01

    % of the 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......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......'s skeletal muscle, suggesting that virtually no truncated receptor was expressed. Receptor kinase activity was, however, reduced by 95 and 91% in the compound heterozygous brothers. This suggests that the mother's mutated allele contributes little to the generation of functional receptor protein...

  3. Combining a GLP-1 receptor agonist and basal insulin: study evidence and practical considerations.

    Science.gov (United States)

    Carris, Nicholas W; Taylor, James R; Gums, John G

    2014-12-01

    Most patients with diabetes mellitus require multiple medications to achieve glycemic goals. Considering this and the increasing incidence of type 2 diabetes worldwide, the need for effective combination therapy is pressing. Basal insulin and glucagon-like peptide 1 (GLP-1) receptor agonists are frequently used to treat type 2 diabetes. Though both classes of medication are exclusively injectable, which may cause initial hesitation from providers, evidence for their combined use is substantial. This review summarizes the theoretical benefit, supporting evidence, and implementation of a combined basal insulin-GLP-1 receptor agonist regimen. Basal insulin added to a GLP-1 receptor agonist reduces hemoglobin A1c (HbA1c) without weight gain or significantly increased hypoglycemia. A GLP-1 receptor agonist added to basal insulin reduces HbA1c and body weight. Compared with the addition of meal-time insulin to basal insulin, a GLP-1 receptor agonist produces similar or greater reduction in HbA1c, weight loss instead of weight gain, and less hypoglycemia. Gastrointestinal adverse events are common with GLP-1 receptor agonists, especially during initiation and titration. However, combination with basal insulin is not expected to augment expected adverse events that come with using a GLP-1 receptor agonist. Basal insulin can be added to a GLP-1 receptor agonist with a slow titration to target goal fasting plasma glucose. In patients starting a GLP-1 receptor agonist, the dose of basal insulin should be decreased by 20 % in patients with an HbA1c ≤8 %. The evidence from 15 randomized prospective studies supports the combined use of a GLP-1 receptor agonist with basal insulin in a broad range of patients with uncontrolled type 2 diabetes.

  4. The impact of low-dose insulin on peripheral nerve insulin receptor signaling in streptozotocin-induced diabetic rats.

    Directory of Open Access Journals (Sweden)

    Kazuhiro Sugimoto

    Full Text Available BACKGROUND: The precise mechanisms of the neuroprotective effects of insulin in streptozotocin (STZ-induced diabetic animals remain unknown, but altered peripheral nerve insulin receptor signaling due to insulin deficiency might be one cause. METHODOLOGY AND PRINCIPAL FINDINGS: Diabetes was induced in 10-week-old, male Wistar rats by injecting them with STZ (45 mg/kg. They were assigned to one group that received half of an insulin implant (∼1 U/day; I-group, n = 11 or another that remained untreated (U-group, n = 10 for 6 weeks. The controls were age- and sex-matched, non-diabetic Wistar rats (C-group, n = 12. Low-dose insulin did not change haemoglobin A1c, which increased by 136% in the U-group compared with the C-group. Thermal hypoalgesia and mechanical hyperalgesia developed in the U-group, but not in the I-group. Sensory and motor nerve conduction velocities decreased in the U-group, whereas sensory nerve conduction velocity increased by 7% (p = 0.0351 in the I-group compared with the U-group. Western blots showed unaltered total insulin receptor (IR, but a 31% decrease and 3.1- and 4.0-fold increases in phosphorylated IR, p44, and p42 MAPK protein levels, respectively, in sciatic nerves from the U-group compared with the C-group. Phosphorylated p44/42 MAPK protein decreased to control levels in the I-group (p<0.0001. CONCLUSIONS AND SIGNIFICANCE: Low-dose insulin deactivated p44/42 MAPK and ameliorated peripheral sensory nerve dysfunction in rats with STZ-induced diabetes. These findings support the notion that insulin deficiency per se introduces impaired insulin receptor signaling in type 1 diabetic neuropathy.

  5. 4PS/insulin receptor substrate (IRS)-2 is the alternative substrate of the insulin receptor in IRS-1-deficient mice.

    Science.gov (United States)

    Patti, M E; Sun, X J; Bruening, J C; Araki, E; Lipes, M A; White, M F; Kahn, C R

    1995-10-20

    Insulin receptor substrate-1 (IRS-1) is the major cytoplasmic substrate of the insulin and insulin-like growth factor (IGF)-1 receptors. Transgenic mice lacking IRS-1 are resistant to insulin and IGF-1, but exhibit significant residual insulin action which corresponds to the presence of an alternative high molecular weight substrate in liver and muscle. Recently, Sun et al. (Sun, X.-J., Wang, L.-M., Zhang, Y., Yenush, L. P., Myers, M. G., Jr., Glasheen, E., Lane, W.S., Pierce, J. H., and White, M. F. (1995) Nature 377, 173-177) purified and cloned 4PS, the major substrate of the IL-4 receptor-associated tyrosine kinase in myeloid cells, which has significant structural similarity to IRS-1. To determine if 4PS is the alternative substrate of the insulin receptor in IRS-1-deficient mice, we performed immunoprecipitation, immunoblotting, and phosphatidylinositol (PI) 3-kinase assays using specific antibodies to 4PS. Following insulin stimulation, 4PS is rapidly phosphorylated in liver and muscle, binds to the p85 subunit of PI 3-kinase, and activates the enzyme. Insulin stimulation also results in the association of 4PS with Grb 2 in both liver and muscle. In IRS-1-deficient mice, both the phosphorylation of 4PS and associated PI 3-kinase activity are enhanced, without an increase in protein expression. Immunodepletion of 4PS from liver and muscle homogenates removes most of the phosphotyrosine-associated PI 3-kinase activity in IRS-1-deficient mice. Thus, 4PS is the primary alternative substrate, i.e. IRS-2, which plays a major role in physiologic insulin signal transduction via both PI 3-kinase activation and Grb 2/Sos association. In IRS-1-deficient mice, 4PS/IRS-2 provides signal transduction to these two major pathways of insulin signaling.

  6. Role of the occult insulin receptors in the regulation of atrophy and hypertrophy of skeletal muscles

    Energy Technology Data Exchange (ETDEWEB)

    McLeod, M.J.

    1980-10-01

    Insulin levels in the plasma are variable, as are insulin receptor numbers on the surface of skeletal muscles. Increased blood supply to the muscle during exercise delivers more insulin to the muscles even though insulin levels are suppressed by epinephrine. Increasing muscle temperatures result in an increased insulin effect, if enough receptors are available for binding. In exhaustive exercise, insulin levels are minimal but the movement of glucose across the cell membrane increases. Since insulin-receptor affinity decreases at high temperature, the only way this increased movement of glucose can be accomplished is by increased insulin binding. Thus more receptors must be available to capture the insulin. Epinephrine levels drop drastically after exercise. Insulin levels increase and the cell can import glucose, amino acids, and nucleotides. As the cell temperature decreases after exercise, insulin binding increases but the total effect decreases because the many surface receptors disappear again over a period of time. If the muscle is immobilized, the number of surface receptors decreases. There is less insulin effect and as a result the muscle atrophies. Acetylcholine (ACh) causes the proper arrangement of the myofibrils in the foetus, and has some effect on the rate of atrophy in an immobilized muscle. It also appears to maintain the cell membrane organization. Disuse atrophy is caused by a decrease in cell size, while exercise hypertrophy is caused by an increase in cell size. Growth hormone (STH) is therefore ruled out as the exercise hypertrophy controlling factor, since STH causes cell division and not hypertrophy. Testosterone can also be ruled out as the controlling factor in the development of hypertrophy and atrophy of muscles. Estrogen can likewise be ruled out. (ERB)

  7. Autoimmune Hypoglycemia in a Patient with Characterization of Insulin Receptor Autoantibodies

    Directory of Open Access Journals (Sweden)

    Suk Chon

    2011-02-01

    Full Text Available BackgroundType B insulin resistance syndrome is a manifestation of autoantibodies to the insulin receptor that results in severe hyperglycemia and acanthosis nigricans. However, the mechanisms by which these autoantibodies induce hypoglycemia are largely unknown. In this paper, we report the case of patient with type B insulin resistance syndrome who presented with frequent severe fasting hypoglycemia and acanthosis nigricans.MethodsTo evaluate the mechanism of hypoglycemia, we measured the inhibition of insulin binding to erythrocytes and IM9 lymphocytes in a sample of the patient's dialyzed serum before and after immunosuppressive therapy.ResultsIn the patient's pre-treatment serum IgG, the binding of 125I-insulin to erythrocytes was markedly inhibited in a dose-dependent manner until the cold insulin level reached 10-9 mol/L. We also observed dose-dependent inhibition of insulin binding to IM9 lymphocytes, which reached approximately 82% inhibition and persisted even when diluted 1:20. After treatment with glucocorticoids, insulin-erythrocyte binding activity returned to between 70% and 80% of normal, while the inhibition of insulin-lymphocyte binding was reduced by 17%.ConclusionWe treated a patient with type B insulin resistance syndrome showing recurrent fasting hypoglycemia with steroids and azathioprine. We characterized the patient's insulin receptor antibodies by measuring the inhibition of insulin binding.

  8. Knockout of Vasohibin-1 Gene in Mice Results in Healthy Longevity with Reduced Expression of Insulin Receptor, Insulin Receptor Substrate 1, and Insulin Receptor Substrate 2 in Their White Adipose Tissue

    Science.gov (United States)

    Takeda, Eichi; Suzuki, Yasuhiro; Yamada, Tetsuya; Katagiri, Hideki

    2017-01-01

    Vasohibin-1 (Vash1), originally isolated as an endothelium-derived angiogenesis inhibitor, has a characteristic of promoting stress tolerance in endothelial cells (ECs). We therefore speculated that the lack of the vash1 gene would result in a short lifespan. However, to our surprise, vash1−/− mice lived significantly longer with a milder senescence phenotype than wild-type (WT) mice. We sought the cause of this healthy longevity and found that vash1−/− mice exhibited mild insulin resistance along with reduced expression of the insulin receptor (insr), insulin receptor substrate 1 (irs-1), and insulin receptor substrate 2 (irs-2) in their white adipose tissue (WAT) but not in their liver or skeletal muscle. The expression of vash1 dominated in the WAT among those 3 organs. Importantly, vash1−/− mice did not develop diabetes even when fed a high-fat diet. These results indicate that the expression of vash1 was required for the normal insulin sensitivity of the WAT and that the target molecules for this activity were insr, irs1, and irs2. The lack of vash1 caused mild insulin resistance without the outbreak of overt diabetes and might contribute to healthy longevity.

  9. Knockout of Vasohibin-1 Gene in Mice Results in Healthy Longevity with Reduced Expression of Insulin Receptor, Insulin Receptor Substrate 1, and Insulin Receptor Substrate 2 in Their White Adipose Tissue

    Directory of Open Access Journals (Sweden)

    Eichi Takeda

    2017-01-01

    Full Text Available Vasohibin-1 (Vash1, originally isolated as an endothelium-derived angiogenesis inhibitor, has a characteristic of promoting stress tolerance in endothelial cells (ECs. We therefore speculated that the lack of the vash1 gene would result in a short lifespan. However, to our surprise, vash1−/− mice lived significantly longer with a milder senescence phenotype than wild-type (WT mice. We sought the cause of this healthy longevity and found that vash1−/− mice exhibited mild insulin resistance along with reduced expression of the insulin receptor (insr, insulin receptor substrate 1 (irs-1, and insulin receptor substrate 2 (irs-2 in their white adipose tissue (WAT but not in their liver or skeletal muscle. The expression of vash1 dominated in the WAT among those 3 organs. Importantly, vash1−/− mice did not develop diabetes even when fed a high-fat diet. These results indicate that the expression of vash1 was required for the normal insulin sensitivity of the WAT and that the target molecules for this activity were insr, irs1, and irs2. The lack of vash1 caused mild insulin resistance without the outbreak of overt diabetes and might contribute to healthy longevity.

  10. Insulin and Metabolic Stress Stimulate Multisite Serine/Threonine Phosphorylation of Insulin Receptor Substrate 1 and Inhibit Tyrosine Phosphorylation*

    Science.gov (United States)

    Hançer, Nancy J.; Qiu, Wei; Cherella, Christine; Li, Yedan; Copps, Kyle D.; White, Morris F.

    2014-01-01

    IRS1 and IRS2 are key substrates of the insulin receptor tyrosine kinase. Mass spectrometry reveals more than 50 phosphorylated IRS1 serine and threonine residues (Ser(P)/Thr(P) residues) in IRS1 from insulin-stimulated cells or human tissues. We investigated a subset of IRS1 Ser(P)/Thr(P) residues using a newly developed panel of 25 phospho-specific monoclonal antibodies (αpS/TmAbIrs1). CHO cells overexpressing the human insulin receptor and rat IRS1 were stimulated with insulin in the absence or presence of inhibitors of the PI3K → Akt → mechanistic target of rapamycin (mTOR) → S6 kinase or MEK pathways. Nearly all IRS1 Ser(P)/Thr(P) residues were stimulated by insulin and significantly suppressed by PI3K inhibition; fewer were suppressed by Akt or mTOR inhibition, and none were suppressed by MEK inhibition. Insulin-stimulated Irs1 tyrosine phosphorylation (Tyr(P)Irs1) was enhanced by inhibition of the PI3K → Akt → mTOR pathway and correlated with decreased Ser(P)-302Irs1, Ser(P)-307Irs1, Ser(P)-318Irs1, Ser(P)-325Irs1, and Ser(P)-346Irs1. Metabolic stress modeled by anisomycin, thapsigargin, or tunicamycin increased many of the same Ser(P)/Thr(P) residues as insulin, some of which (Ser(P)-302Irs1, Ser(P)-307Irs1, and four others) correlated significantly with impaired insulin-stimulated Tyr(P)Irs1. Thus, IRS1 Ser(P)/Thr(P) is an integrated response to insulin stimulation and metabolic stress, which associates with reduced Tyr(P)Irs1 in CHOIR/IRS1 cells. PMID:24652289

  11. Insulin Dissociates the Effects of Liver X Receptor on Lipogenesis, Endoplasmic Reticulum Stress, and Inflammation.

    Science.gov (United States)

    Sun, Xiaowei; Haas, Mary E; Miao, Ji; Mehta, Abhiruchi; Graham, Mark J; Crooke, Rosanne M; Pais de Barros, Jean-Paul; Wang, Jian-Guo; Aikawa, Masanori; Masson, David; Biddinger, Sudha B

    2016-01-15

    Diabetes is characterized by increased lipogenesis as well as increased endoplasmic reticulum (ER) stress and inflammation. The nuclear hormone receptor liver X receptor (LXR) is induced by insulin and is a key regulator of lipid metabolism. It promotes lipogenesis and cholesterol efflux, but suppresses endoplasmic reticulum stress and inflammation. The goal of these studies was to dissect the effects of insulin on LXR action. We used antisense oligonucleotides to knock down Lxrα in mice with hepatocyte-specific deletion of the insulin receptor and their controls. We found, surprisingly, that knock-out of the insulin receptor and knockdown of Lxrα produced equivalent, non-additive effects on the lipogenic genes. Thus, insulin was unable to induce the lipogenic genes in the absence of Lxrα, and LXRα was unable to induce the lipogenic genes in the absence of insulin. However, insulin was not required for LXRα to modulate the phospholipid profile, or to suppress genes in the ER stress or inflammation pathways. These data show that insulin is required specifically for the lipogenic effects of LXRα and that manipulation of the insulin signaling pathway could dissociate the beneficial effects of LXR on cholesterol efflux, inflammation, and ER stress from the negative effects on lipogenesis.

  12. Presence of insulin receptors in cultured glial C6 cells. Regulation by butyrate.

    Science.gov (United States)

    Montiel, F; Ortiz-Caro, J; Villa, A; Pascual, A; Aranda, A

    1989-01-01

    The presence of insulin receptor and its regulation by butyrate and other short-chain fatty acids was studied in C6 cells, a rat glioma cell line. Intact C6 cells bind 125I-insulin in a rapid, reversible and specific manner. Scatchard analysis of the binding data gives typical curvilinear plots with apparent affinities of approx. 6 nM and 70 nM for the low-affinity (approx. 90% of total) and high-affinity (approx. 10% of total) sites respectively. Incubation with butyrate results in a time- and dose-dependent decrease of insulin binding to C6 cells. A maximal effect was found with 2 mM-butyrate that decreased the receptor by 40-70% after 48 h. Butyrate decreased numbers of receptors of both classes, but did not significantly alter receptor affinity. Other short-chain fatty acids, as well as keto acids, had a similar effect, but with a lower potency. Cycloheximide caused an accumulation of insulin receptors at the cell surface, since insulin binding increased and receptor affinity did not change after incubation with the inhibitor. Simultaneous addition of butyrate and cycloheximide abolished the loss of receptors produced by the fatty acid. In cells preincubated with butyrate, cycloheximide also produced a large increase in receptor numbers, showing that in the absence of new receptor synthesis a large pool of receptors re-appears at the surface of butyrate-treated cells. PMID:2930502

  13. Elevation of serum insulin concentration during euglycemic hyperinsulinemic clamp studies leads to similar activation of insulin receptor kinase in skeletal muscle of subjects with and without NIDDM

    DEFF Research Database (Denmark)

    Klein, H H; Vestergaard, H; Kotzke, G;

    1995-01-01

    The role of skeletal muscle insulin receptor kinase in the pathogenesis of non-insulin-dependent diabetes mellitus (NIDDM) was investigated. Muscle biopsies from 13 patients with NIDDM and 10 control subjects at fasting serum insulin concentrations and approximately 1,000 pmol/l steady-state serum...... insulin during euglycemic hyperinsulinemic clamps were immediately frozen. The biopsies were then solubilized, and the receptors were immobilized to anti-insulin receptor antibody-coated microwells. Receptor kinase and binding activities were consecutively measured in these wells. The increase in serum...... insulin concentration (73 +/- 14 to 1,004 +/- 83 and 45 +/- 7 to 1,07 +/- 77 pmol/l in the NIDDM and control groups, respectively) had similar effects on receptor kinase activity in both study groups (12 +/- 1 to 42 +/- 5 and 12 +/- 2 to 47 +/- 5 amol P.fmol binding activity-1. min-1 in the NIDDM...

  14. Effect of glyburide on in vivo recycling of the hepatic insulin receptor

    Energy Technology Data Exchange (ETDEWEB)

    Frank, H.J.; Donohoe, M.T.; Morris, W.L.

    1985-09-20

    Sulfonylureas affect insulin action at both receptor and post-receptor sites, but their exact mechanism is poorly understood. In these studies, a novel technique was used to examine the influence of glyburide on in vivo cycling of the hepatic insulin receptor. Rats were gavage-fed with 5 mg/kg per day of glyburide solubilized in 60 percent polyethylene glycol and 40 percent phosphate buffer. Control rats were fed polyethylene glycol and buffer alone. After seven days, each rat was anesthetized, the abdomen was surgically exposed, and the animal was given a saturating bolus of 30 micrograms of unlabeled insulin via the portal vein. At seven specified times from 10 seconds to 45 minutes later, a second portal vein injection of a mixture of 1.5 microCi (0.015 micrograms) SVI-labeled insulin and 15 microCi THOH (a highly diffusible internal reference marker) was administered; 18 seconds later (time for one circulation), the right lobe of the liver was removed, and SVI and TH values were counted. The liver uptake index and the turnover half-time were then calculated. Glyburide caused a doubling of the turnover half-time for the receptor. This suggests that sulfonylureas potentiate the action of insulin either by increasing the dwell time of insulin on its receptor or by affecting an intracellular event that delays the recycling of the insulin receptor back to the cell surface plasma membrane.

  15. Insulin/receptor binding: the last piece of the puzzle? What recent progress on the structure of the insulin/receptor complex tells us (or not) about negative cooperativity and activation.

    Science.gov (United States)

    De Meyts, Pierre

    2015-04-01

    Progress in solving the structure of insulin bound to its receptor has been slow and stepwise, but a milestone has now been reached with a refined structure of a complex of insulin with a "microreceptor" that contains the primary binding site. The insulin receptor is a dimeric allosteric enzyme that belongs to the family of receptor tyrosine kinases. The insulin binding process is complex and exhibits negative cooperativity. Biochemical evidence suggested that insulin, through two distinct binding sites, crosslinks two receptor sites located on each α subunit. The structure of the unliganded receptor ectodomain showed a symmetrical folded-over conformation with an antiparallel disposition. Further work resolved the detailed structure of receptor site 1, both without and with insulin. Recently, a missing piece in the puzzle was added: the C-terminal portion of insulin's B-chain known to be critical for binding and negative cooperativity. Here I discuss these findings and their implications.

  16. Insulin receptor signaling in POMC, but Not AgRP, neurons controls adipose tissue insulin action

    National Research Council Canada - National Science Library

    Oberlin, Douglas; Chi, Tiffany; Buettner, Christoph; Shin, Andrew C; Degann, Seta; Filatova, Nika; Lindtner, Claudia

    2017-01-01

    Insulin is a key regulator of adipose tissue lipolysis, and impaired adipose tissue insulin action results in unrestrained lipolysis and lipotoxicity, which are hallmarks of the metabolic syndrome and diabetes...

  17. Receptor-like protein-tyrosine phosphatase alpha specifically inhibits insulin-increased prolactin gene expression

    DEFF Research Database (Denmark)

    Jacob, K K; Sap, J; Stanley, F M

    1998-01-01

    A physiologically relevant response to insulin, stimulation of prolactin promoter activity in GH4 pituitary cells, was used as an assay to study the specificity of protein-tyrosine phosphatase function. Receptor-like protein-tyrosine phosphatase alpha (RPTPalpha) blocks the effect of insulin to i...

  18. Hepatocyte Toll-like receptor 4 regulates obesity-induced inflammation and insulin resistance

    Science.gov (United States)

    Chronic low-grade inflammation is a hallmark of obesity and thought to contribute to the development of obesity-related insulin resistance. Toll-like receptor 4 (Tlr4) is a key mediator of pro-inflammatory responses. Mice lacking Tlr4s are protected from diet-induced insulin resistance and inflammat...

  19. Expression of the growth hormone receptor gene in insulin producing cells

    DEFF Research Database (Denmark)

    Møldrup, Annette; Billestrup, N; Nielsen, Jens Høiriis

    1990-01-01

    Growth hormone (GH) plays a dual role in glucose homeostasis. On the one hand, it exerts an insulin antagonistic effect on the peripheral tissue, on the other hand, it stimulates insulin biosynthesis and beta-cell proliferation. The expression of GH-receptors on the rat insulinoma cell line RIN-5AH...

  20. Kinome analysis reveals nongenomic glucocorticoid receptor-dependent inhibition of insulin signaling

    NARCIS (Netherlands)

    Loewenberg, M; Tuynman, J; Scheffer, M; Verhaar, A; Vermeulen, L; van Deventer, S; Hommes, D; Peppelenbosch, M

    2006-01-01

    Glucocorticoids (GCs) are powerful immunosuppressive agents that control genomic effects through GC receptor (GR)-dependent transcriptional changes. A common complication of GC therapy is insulin resistance, but the underlying molecular mechanism remains obscure. Evidence is increasing for rapid gen

  1. Insulin receptor isoforms A and B as well as insulin receptor substrates-1 and -2 are differentially expressed in prostate cancer.

    Directory of Open Access Journals (Sweden)

    Martin Heni

    Full Text Available AIMS/HYPOTHESIS: In different cancers types, insulin receptor isoform composition or insulin receptor substrate (IRS isoforms are different to healthy tissue. This may be a molecular link to increased cancer risk in diabetes and obesity. Since this is yet unclear for prostate cancer, we investigated IR isoform composition and IRS balance in prostate cancer compared to benign and tumor adjacent benign prostate tissue and brought this into relation to cell proliferation. METHODS: We studied 23 benign prostate samples from radical cystectomy or benign prostatic hyperplasia surgery, 30 samples from benign tissue directly adjacent to prostate cancer foci and 35 cancer samples from different patients. RNA expression levels for insulin receptor isoforms A and B, IRS-1, IRS-2, and IGF-1 receptor were assessed by quantitative real-time RT-PCR. In addition, RNA- and protein expression of the cell cycle regulator p27(Kip1 was quantified by real-time RT-PCR and immunohistochemistry. RESULTS: Insulin receptor isoform A to B ratio was significantly higher in cancer as well as in tumor adjacent benign prostate tissue compared to purely benign prostates (p<0.05. IRS-1 to IRS-2 ratios were lower in malignant than in benign prostatic tissue (p<0.05. These altered ratios both in cancer and adjacent tissue were significantly associated with reduced p27(Kip1 content (p<0.02. Interestingly, IGF-1 receptor levels were significantly lower in patients with type 2 diabetes (p = 0.0019. CONCLUSIONS/INTERPRETATION: We found significant differences in the insulin signaling cascade between benign prostate tissue and prostate cancer. Histological benign tissue adjacent to cancer showed expression patterns similar to the malignancies. Our findings suggest a role of the insulin signaling pathway in prostate cancer and surrounding tissue and can hence be relevant for both novel diagnostic and therapeutic approaches in this malignancy.

  2. Concentrations of insulin glargine and its metabolites during long-term insulin therapy in type 2 diabetic patients and comparison of effects of insulin glargine, its metabolites, IGF-I, and human insulin on insulin and IGF-I receptor signaling

    NARCIS (Netherlands)

    A.J. Varewijck (Aimee); H. Yki-Jarvinen (Hannele); R. Schmidt (Reinhold); N. Tennagels (Norbert); J.A.M.J.L. Janssen (Joseph)

    2013-01-01

    textabstractWe investigated 1) the ability of purified glargine (GLA), metabolites 1 (M1) and 2 (M2), IGF-I, and NPH insulin to activate the insulin receptor (IR)-A and IR-B and IGF-I receptor (IGF-IR) in vitro; 2) plasma concentrations of GLA, M1, and M2 during longterm insulin therapy in type 2

  3. Alterations in the hepatic insulin receptor kinase in genetic and acquired obesity in rats.

    Science.gov (United States)

    Hurrell, D G; Pedersen, O; Kahn, C R

    1989-11-01

    Obesity is associated with insulin resistance and type II diabetes mellitus. In the present study, we have characterized hepatic insulin receptor function in two animal models of obesity: the Zucker fatty rat (ZFR), a model of genetic obesity with severe hyperinsulinemia, and the Sprague-Dawley rat with dietary obesity, a model of acquired obesity. Zucker fatty rats were also treated with streptozotocin (STZ) in an effort to examine the effects of relative insulin deficiency and hyperglycemia in the setting of obesity. Using wheat germ agglutinin-purified insulin receptor extracted from liver, no significant difference in insulin binding was identified in either model of obesity. beta-Subunit autophosphorylation was significantly decreased in both obese models relative to that in controls (72% in the obese ZFR and 49% in the overfed Sprague-Dawley model). Kinase activity, as measured by phosphorylation of the 1142-1153 synthetic peptide, was also decreased in both models of obesity by 22% and 64%, respectively. In the Zucker rat, STZ treatment led to an 80% increase in receptor concentration and a further 70% increase in beta-subunit autophosphorylation per receptor, whereas tyrosine kinase activity toward substrate was not altered. Since kinase activity is closely linked to autophosphorylation, we determined the fraction of autophosphorylated (activated) receptors vs. non-phosphorylated (inactive) receptors by using antiphosphotyrosine antibody to precipitate receptors bound with [125I]insulin. There was no significant difference in the percentage of activated insulin receptors in the dietary obese, ZFR, or STZ-treated Zucker rat vs. that in the controls. In all models, the percentage of activated receptors ranged from 32-46% of the total receptor pool. These data suggest that in genetic and acquired obesity, autophosphorylation of the beta-subunit is reduced and is a limiting factor in insulin receptor activation. A similar fraction of all receptors appears to

  4. Design of an insulin analog with enhanced receptor binding selectivity: rationale, structure, and therapeutic implications.

    Science.gov (United States)

    Zhao, Ming; Wan, Zhu-li; Whittaker, Linda; Xu, Bin; Phillips, Nelson B; Katsoyannis, Panayotis G; Ismail-Beigi, Faramarz; Whittaker, Jonathan; Weiss, Michael A

    2009-11-13

    Insulin binds with high affinity to the insulin receptor (IR) and with low affinity to the type 1 insulin-like growth factor (IGF) receptor (IGFR). Such cross-binding, which reflects homologies within the insulin-IGF signaling system, is of clinical interest in relation to the association between hyperinsulinemia and colorectal cancer. Here, we employ nonstandard mutagenesis to design an insulin analog with enhanced affinity for the IR but reduced affinity for the IGFR. Unnatural amino acids were introduced by chemical synthesis at the N- and C-capping positions of a recognition alpha-helix (residues A1 and A8). These sites adjoin the hormone-receptor interface as indicated by photocross-linking studies. Specificity is enhanced more than 3-fold on the following: (i) substitution of Gly(A1) by D-Ala or D-Leu, and (ii) substitution of Thr(A8) by diaminobutyric acid (Dab). The crystal structure of [D-Ala(A1),Dab(A8)]insulin, as determined within a T(6) zinc hexamer to a resolution of 1.35 A, is essentially identical to that of human insulin. The nonstandard side chains project into solvent at the edge of a conserved receptor-binding surface shared by insulin and IGF-I. Our results demonstrate that modifications at this edge discriminate between IR and IGFR. Because hyperinsulinemia is typically characterized by a 3-fold increase in integrated postprandial insulin concentrations, we envisage that such insulin analogs may facilitate studies of the initiation and progression of cancer in animal models. Future development of clinical analogs lacking significant IGFR cross-binding may enhance the safety of insulin replacement therapy in patients with type 2 diabetes mellitus at increased risk of colorectal cancer.

  5. Structural insights into ligand-induced activation of the insulin receptor

    Energy Technology Data Exchange (ETDEWEB)

    Ward, C.; Lawrence, M.; Streltsov, V.; Garrett, T.; McKern, N.; Lou, M.-Z.; Lovrecz, G.; Adams, T. (CSIRO); (WEHIMR)

    2008-04-29

    The current model for insulin binding to the insulin receptor proposes that there are two binding sites, referred to as sites 1 and 2, on each monomer in the receptor homodimer and two binding surfaces on insulin, one involving residues predominantly from the dimerization face of insulin (the classical binding surface) and the other residues from the hexamerization face. High-affinity binding involves one insulin molecule using its two surfaces to make bridging contacts with site 1 from one receptor monomer and site 2 from the other. Whilst the receptor dimer has two identical site 1-site 2 pairs, insulin molecules cannot bridge both pairs simultaneously. Our structures of the insulin receptor (IR) ectodomain dimer and the L1-CR-L2 fragments of IR and insulin-like growth factor receptor (IGF-1R) explain many of the features of ligand-receptor binding and allow the two binding sites on the receptor to be described. The IR dimer has an unexpected folded-over conformation which places the C-terminal surface of the first fibronectin-III domain in close juxtaposition to the known L1 domain ligand-binding surface suggesting that the C-terminal surface of FnIII-1 is the second binding site involved in high-affinity binding. This is very different from previous models based on three-dimensional reconstruction from scanning transmission electron micrographs. Our single-molecule images indicate that IGF-1R has a morphology similar to that of IR. In addition, the structures of the first three domains (L1-CR-L2) of the IR and IGF-1R show that there are major differences in the two regions governing ligand specificity. The implications of these findings for ligand-induced receptor activation will be discussed. This review summarizes the key findings regarding the discovery and characterization of the insulin receptor, the identification and arrangement of its structural domains in the sequence and the key features associated with ligand binding. The remainder of the review

  6. Research resource: new and diverse substrates for the insulin receptor isoform a revealed by quantitative proteomics after stimulation with igf-ii or insulin

    DEFF Research Database (Denmark)

    Morcavallo, Alaide; Gaspari, Marco; Pandini, Giuseppe;

    2011-01-01

    The isoform A of the insulin receptor (IR) (IR-A) is a bifunctional receptor, because it binds both insulin and IGF-II. IR-A activation by IGF-II plays a role in development, but its physiological role in adults is unknown. IGF-II signaling through IR-A is deregulated in cancer and favors tumor p...

  7. Novel method demonstrates differential ligand activation and phosphatase-mediated deactivation of insulin receptor tyrosine-specific phosphorylation.

    Science.gov (United States)

    Cieniewicz, Anne M; Cooper, Philip R; McGehee, Jennifer; Lingham, Russell B; Kihm, Anthony J

    2016-08-01

    Insulin receptor signaling is a complex cascade leading to a multitude of intracellular functional responses. Three natural ligands, insulin, IGF1 and IGF2, are each capable of binding with different affinities to the insulin receptor, and result in variable biological responses. However, it is likely these affinity differences alone cannot completely explain the myriad of diverse cellular outcomes. Ligand binding initiates activation of a signaling cascade resulting in phosphorylation of the IR itself and other intracellular proteins. The direct catalytic activity along with the temporally coordinated assembly of signaling proteins is critical for insulin receptor signaling. We hypothesized that determining differential phosphorylation among individual tyrosine sites activated by ligand binding or dephosphorylation by phosphatases could provide valuable insight into insulin receptor signaling. Here, we present a sensitive, novel immunoassay adapted from Meso Scale Discovery technology to quantitatively measure changes in site-specific phosphorylation levels on endogenous insulin receptors from HuH7 cells. We identified insulin receptor phosphorylation patterns generated upon differential ligand activation and phosphatase-mediated deactivation. The data demonstrate that insulin, IGF1 and IGF2 elicit different insulin receptor phosphorylation kinetics and potencies that translate to downstream signaling. Furthermore, we show that insulin receptor deactivation, regulated by tyrosine phosphatases, occurs distinctively across specific tyrosine residues. In summary, we present a novel, quantitative and high-throughput assay that has uncovered differential ligand activation and site-specific deactivation of the insulin receptor. These results may help elucidate some of the insulin signaling mechanisms, discriminate ligand activity and contribute to a better understanding of insulin receptor signaling. We propose this methodology as a powerful approach to characterize

  8. Influence of berberine on protein tyrosine kinase of erythrocyte insulin receptors from type 2 diabetes mellitus

    Institute of Scientific and Technical Information of China (English)

    Xianglei Deng; Xinrong Li; Chenggong Tian

    2005-01-01

    Objective: Bererine has been used to treat type 2 diabetes mellitus in Chinese traditional medicine because of its hypoglycemic effect. In this report, we compared the intrinsic tyrosine kinase activities of erythrocyte insulin receptors from type 2 diabetes mellitus with or without stimulation by berberine in vitro. Methods: Preparations containing insulin receptors were obtained from soluble human erythrocytes, and the insulin receptors were partially purified by affinity chromatography. The tyrosine kinase activity was measured by the exogenous substrate phosphorylation. Results: Both the membrane tyrosine kinase activity and the purified receptor tyrosine kinase activity from diabetics decreased significantly compared with those of normal individuals (reduced by 67.4 % and 47.2 %, respectively).After incubation with berberine, there is a statistical difference in the activity of membrane tyrosine kinase for diabetic patients (a 150% increase). Bererine had no effect on the tyrosine kinase activity of purified insulin receptors. Conclusion: We concluded from these results that berberine was able to improve the insulin sensitivity by increasing the protein tyrosine kinase activity of membrane-bound insulin receptors from type 2 diabetes mellitus.

  9. MG53-IRS-1 (Mitsugumin 53-Insulin Receptor Substrate-1) Interaction Disruptor Sensitizes Insulin Signaling in Skeletal Muscle.

    Science.gov (United States)

    Lee, Hyun; Park, Jung-Jin; Nguyen, Nga; Park, Jun Sub; Hong, Jin; Kim, Seung-Hyeob; Song, Woon Young; Kim, Hak Joong; Choi, Kwangman; Cho, Sungchan; Lee, Jae-Seon; Kim, Bong-Woo; Ko, Young-Gyu

    2016-12-23

    Mitsugumin 53 (MG53) is an E3 ligase that interacts with and ubiquitinates insulin receptor substrate-1 (IRS-1) in skeletal muscle; thus, an MG53-IRS-1 interaction disruptor (MID), which potentially sensitizes insulin signaling with an elevated level of IRS-1 in skeletal muscle, is an excellent candidate for treating insulin resistance. To screen for an MID, we developed a bimolecular luminescence complementation system using an N-terminal luciferase fragment fused with IRS-1 and a C-terminal luciferase fragment fused with an MG53 C14A mutant that binds to IRS-1 but does not have E3 ligase activity. An MID, which was discovered using the bimolecular luminescence complementation system, disrupted the molecular association of MG53 with IRS-1, thus abolishing MG53-mediated IRS-1 ubiquitination and degradation. Thus, the MID sensitized insulin signaling and increased insulin-elicited glucose uptake with an elevated level of IRS-1 in C2C12 myotubes. These data indicate that this MID holds promise as a drug candidate for treating insulin resistance. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  10. Chronic insulin therapy reduces adipose tissue macrophage content in LDL-receptor-deficient mice.

    Science.gov (United States)

    Yoon, J; Subramanian, S; Ding, Y; Wang, S; Goodspeed, L; Sullivan, B; Kim, J; O'Brien, K D; Chait, A

    2011-05-01

    Insulin has anti-inflammatory effects in short-term experiments. However, the effects of chronic insulin administration on inflammation are unknown. We hypothesised that chronic insulin administration would beneficially alter adipose tissue inflammation and several circulating inflammatory markers. We administered two forms of long-acting insulin, insulin glargine (A21Gly,B31Arg,B32Arg human insulin) and insulin detemir (B29Lys[ε-tetradecanoyl],desB30 human insulin), to LDL-receptor-deficient mice. After 8 weeks on a diet that causes obesity, hyperglycaemia, adipose tissue macrophage accumulation and atherosclerosis, the mice received subcutaneous glargine, detemir or NaCl (control) for 12 weeks. Serum amyloid A (SAA) and serum amyloid P (SAP), metabolic variables, adipose tissue macrophages and aortic atherosclerosis were evaluated. Weight gain was equivalent in all groups. The glycated haemoglobin level fell equivalently in both insulin-treated groups. Plasma cholesterol and triacylglycerol levels, and hepatic triacylglycerol level significantly improved in the glargine compared with the detemir or control groups. Levels of mRNA expression for monocyte chemotactic protein-1 and F4/80, a macrophage marker, in adipose tissue were decreased only in the glargine group (p adipose tissue macrophage content decreased in both insulin groups (p insulin-treated group, but IL-6 levels fell in the glargine-treated mice. While chronic insulin administration did not decrease SAA and SAP, administration of glargine but not detemir insulin improved dyslipidaemia, IL-6 levels and atherosclerosis, and both insulins reduced macrophage accumulation in visceral adipose tissue. Thus, chronic insulin therapy has beneficial tissue effects independent of circulating inflammatory markers in this murine model of diet-induced obesity and diabetes.

  11. All-Atom Structural Models of the Transmembrane Domains of Insulin and Type 1 Insulin-Like Growth Factor Receptors.

    Science.gov (United States)

    Mohammadiarani, Hossein; Vashisth, Harish

    2016-01-01

    The receptor tyrosine kinase superfamily comprises many cell-surface receptors including the insulin receptor (IR) and type 1 insulin-like growth factor receptor (IGF1R) that are constitutively homodimeric transmembrane glycoproteins. Therefore, these receptors require ligand-triggered domain rearrangements rather than receptor dimerization for activation. Specifically, binding of peptide ligands to receptor ectodomains transduces signals across the transmembrane domains for trans-autophosphorylation in cytoplasmic kinase domains. The molecular details of these processes are poorly understood in part due to the absence of structures of full-length receptors. Using MD simulations and enhanced conformational sampling algorithms, we present all-atom structural models of peptides containing 51 residues from the transmembrane and juxtamembrane regions of IR and IGF1R. In our models, the transmembrane regions of both receptors adopt helical conformations with kinks at Pro961 (IR) and Pro941 (IGF1R), but the C-terminal residues corresponding to the juxtamembrane region of each receptor adopt unfolded and flexible conformations in IR as opposed to a helix in IGF1R. We also observe that the N-terminal residues in IR form a kinked-helix sitting at the membrane-solvent interface, while homologous residues in IGF1R are unfolded and flexible. These conformational differences result in a larger tilt-angle of the membrane-embedded helix in IGF1R in comparison to IR to compensate for interactions with water molecules at the membrane-solvent interfaces. Our metastable/stable states for the transmembrane domain of IR, observed in a lipid bilayer, are consistent with a known NMR structure of this domain determined in detergent micelles, and similar states in IGF1R are consistent with a previously reported model of the dimerized transmembrane domains of IGF1R. Our all-atom structural models suggest potentially unique structural organization of kinase domains in each receptor.

  12. Insulin receptor substrate signaling controls cardiac energy metabolism and heart failure.

    Science.gov (United States)

    Guo, Cathy A; Guo, Shaodong

    2017-06-01

    The heart is an insulin-dependent and energy-consuming organ in which insulin and nutritional signaling integrates to the regulation of cardiac metabolism, growth and survival. Heart failure is highly associated with insulin resistance, and heart failure patients suffer from the cardiac energy deficiency and structural and functional dysfunction. Chronic pathological conditions, such as obesity and type 2 diabetes mellitus, involve various mechanisms in promoting heart failure by remodeling metabolic pathways, modulating cardiac energetics and impairing cardiac contractility. Recent studies demonstrated that insulin receptor substrates 1 and 2 (IRS-1,-2) are major mediators of both insulin and insulin-like growth factor-1 (IGF-1) signaling responsible for myocardial energetics, structure, function and organismal survival. Importantly, the insulin receptor substrates (IRS) play an important role in the activation of the phosphatidylinositide-3-dependent kinase (PI-3K) that controls Akt and Foxo1 signaling cascade, regulating the mitochondrial function, cardiac energy metabolism and the renin-angiotensin system. Dysregulation of this branch in signaling cascades by insulin resistance in the heart through the endocrine system promotes heart failure, providing a novel mechanism for diabetic cardiomyopathy. Therefore, targeting this branch of IRS→PI-3K→Foxo1 signaling cascade and associated pathways may provide a fundamental strategy for the therapeutic and nutritional development in control of metabolic and cardiovascular diseases. In this review, we focus on insulin signaling and resistance in the heart and the role energetics play in cardiac metabolism, structure and function. © 2017 Society for Endocrinology.

  13. Metabolism of covalent receptor-insulin complexes by 3T3-L1 adipocytes. Synthesis and use of photosensitive insulin analogs to study insulin receptor metabolism in cell culture.

    Science.gov (United States)

    Reed, B C

    1983-04-10

    To facilitate labeling cell surface insulin receptors and analyzing their metabolism by 3T3-L1 adipocytes, a characterization of both the interaction of photosensitive insulin analogs with 3T3-L1 adipocytes and the conditions for photocross-linking these derivatives to the insulin receptor are described. The synthesis and purification of two photoaffinity analogs of insulin are presented. Both B29-lysine- and A1-glycine-substituted N-(2-nitro-4-azidophenyl)glycyl insulin compete with 125I-insulin for binding to 3T3-L1 adipocytes, and the B29-derivative retains a biological activity similar to that for native insulin. An apparatus developed for these studies permits photolysis of cells in monolayer culture using the visible region of the lamp emission spectrum. Activation of the photoderivative by this apparatus occurs with a half-life of approximately 15 s and permits rapid photolabeling of a single species of receptor of 300,000 Da. The conditions for photolabeling permit a measurement of the turnover of covalent receptor-insulin complexes by 3T3-L1 adipocytes in monolayer culture. Degradation of this complex occurs as an apparent first order process with a half-life of 7 h. A comparison with previous studies (Reed, B. C., Ronnett, G. V., Clements, P. R., and Lane, M. D. (1981) J. Biol. Chem 256, 3917-3925; Ronnett, G. V., Knutson, V. P., and Lane, M. D. (1982) J. Biol. Chem. 257, 4285-4291) indicates that in a "down-regulated" state, 3T3-L1 adipocytes degrade covalent receptor-hormone complexes with kinetics similar to those for the degradation of dissociable receptor-hormone complexes.

  14. Direct demonstration of insulin receptor internalization. A quantitative electron microscopic study of covalently bound /sup 125/I-photoreactive insulin incubated with isolated hepatocytes

    Energy Technology Data Exchange (ETDEWEB)

    Gorden, P.; Carpentier, J.L.; Moule, M.L.; Yip, C.C.; Orci, L.

    1982-07-01

    When /sup 125/I-insulin is incubated with isolated rodent hepatocytes at 37 degrees C, the ligand initially binds to the plasma membrane of the cell and is subsequently internalized by adsorptive endocytosis. To confirm directly that the insulin receptor is internalized with the ligand, we covalently linked photoreactive /sup 125/I-N sigma B29 (azidobenzoyl) insulin to its specific hepatocyte receptor and followed its fate by quantitative electron microscopic autoradiography. We found that the covalently linked photoreactive insulin is internalized by the cell in fashion analogous to the internalization of ordinary /sup 125/I-insulin, indicating that, at least under these conditions, the insulin receptor is internalized with the ligand.

  15. Ghrelin counteracts insulin-induced activation of vagal afferent neurons via growth hormone secretagogue receptor.

    Science.gov (United States)

    Iwasaki, Yusaku; Dezaki, Katsuya; Kumari, Parmila; Kakei, Masafumi; Yada, Toshihiko

    2015-08-01

    Vagal afferent nerves sense meal-related gastrointestinal and pancreatic hormones and convey their information to the brain, thereby regulating brain functions including feeding. We have recently demonstrated that postprandial insulin directly acts on the vagal afferent neurons. Plasma concentrations of orexigenic ghrelin and anorexigenic insulin show reciprocal dynamics before and after meals. The present study examined interactive effects of ghrelin and insulin on vagal afferent nerves. Cytosolic Ca(2+) concentration ([Ca(2+)]i) in isolated nodose ganglion (NG) neurons was measured to monitor their activity. Insulin at 10(-7)M increased [Ca(2+)]i in NG neurons, and the insulin-induced [Ca(2+)]i increase was inhibited by treatment with ghrelin at 10(-8)M. This inhibitory effect of ghrelin was attenuated by [D-Lys(3)]-GHRP-6, an antagonist of growth hormone-secretagogue receptor (GHSR). Des-acyl ghrelin had little effect on insulin-induced [Ca(2+)]i increases in NG neurons. Ghrelin did not affect [Ca(2+)]i increases in response to cholecystokinin (CCK), a hormone that inhibits feeding via vagal afferent neurons, indicating that ghrelin selectively counteracts the insulin action. These results demonstrate that ghrelin via GHSR suppresses insulin-induced activation of NG neurons. The action of ghrelin to counteract insulin effects on NG might serve to efficiently inform the brain of the systemic change between fasting-associated ghrelin-dominant and fed-associated insulin-dominant states for the homeostatic central regulation of feeding and metabolism.

  16. Genomic actions of 1,25-dihydroxyvitamin D3 on insulin receptor gene expression, insulin receptor number and insulin activity in the kidney, liver and adipose tissue of streptozotocin-induced diabetic rats

    Directory of Open Access Journals (Sweden)

    García-Arencibia Moisés

    2008-07-01

    Full Text Available Abstract Background this study set out to examine the effects of the treatment with 1,25-dihydroxyvitamin D3 (1,25D3 [150 IU/Kg (3.75 μg/Kg one a day, for 15 days] to non-diabetic rats and in rats rendered diabetic by a single injection of streptozotocin [65 mg/kg]. Results treatment with 1,25D3 to non-diabetic rats did not affect the biochemical parameters measured in the plasma and urine of these animals. Likewise, insulin receptor expression in the kidney, liver, or adipose tissue and insulin-stimulated glucose transport in adipocytes from these animals were not affected either. Treatment with 1,25D3 to streptozotocin-induced diabetic rats did not correct the hyperglycemia, hypoinsulinemia, glycosuria or ketonemia induced by the diabetes, although it partially reversed the over-expression of the insulin receptor gene in the liver and adipose tissue, without altering the normal expression of this gene in the kidney. These effects were accompanied by a normalization of the number of insulin receptors without altering receptor affinity but improving the insulin response to glucose transport in adipocytes from these diabetic animals. Moreover, a computer search in the rat insulin receptor promoter revealed the existence of two candidate vitamin D response element (VDRE sequences located at -256/-219 bp and -653/-620 bp, the first overlapped by three and the second by four AP-2-like sites. Conclusion these genomic actions of 1,25D3 could represent beneficial effects associated with the amelioration of diabetes via mechanisms that possibly involve direct transcriptional activation of the rat insulin receptor gene. The candidate VDREs identified may respond to 1,25D3 via activation of the vitamin D receptor, although this remains to be investigated.

  17. A comparative structural bioinformatics analysis of the insulin receptor family ectodomain based on phylogenetic information.

    Directory of Open Access Journals (Sweden)

    Miguel E Rentería

    Full Text Available The insulin receptor (IR, the insulin-like growth factor 1 receptor (IGF1R and the insulin receptor-related receptor (IRR are covalently-linked homodimers made up of several structural domains. The molecular mechanism of ligand binding to the ectodomain of these receptors and the resulting activation of their tyrosine kinase domain is still not well understood. We have carried out an amino acid residue conservation analysis in order to reconstruct the phylogeny of the IR Family. We have confirmed the location of ligand binding site 1 of the IGF1R and IR. Importantly, we have also predicted the likely location of the insulin binding site 2 on the surface of the fibronectin type III domains of the IR. An evolutionary conserved surface on the second leucine-rich domain that may interact with the ligand could not be detected. We suggest a possible mechanical trigger of the activation of the IR that involves a slight 'twist' rotation of the last two fibronectin type III domains in order to face the likely location of insulin. Finally, a strong selective pressure was found amongst the IRR orthologous sequences, suggesting that this orphan receptor has a yet unknown physiological role which may be conserved from amphibians to mammals.

  18. Partial rescue of in vivo insulin signalling in skeletal muscle by impaired insulin clearance in heterozygous carriers of a mutation in the insulin receptor gene

    DEFF Research Database (Denmark)

    Højlund, K.; Wojtaszewski, Jørgen; Birk, Jesper Bratz

    2006-01-01

    AIMS/HYPOTHESIS: Recently we reported the coexistence of postprandial hypoglycaemia and moderate insulin resistance in heterozygous carriers of the Arg1174Gln mutation in the insulin receptor gene (INSR). Controlled studies of in vivo insulin signalling in humans with mutant INSR are unavailable,...

  19. Expression of insulin receptor spliced variants and their functional correlates in muscle from patients with non-insulin-dependent diabetes mellitus

    DEFF Research Database (Denmark)

    Hansen, Torben; Bjørbaek, C; Vestergaard, H;

    1993-01-01

    Due to alternative splicing of exon 11 of the receptor gene, the human insulin receptor exists in two forms, that have distinct tissue-specific expression and are functionally different. Needle biopsies obtained from vastus lateralis muscle from 20 patients with noninsulin-dependent diabetes...... mellitus (NIDDM) and 20 normal control subjects were analyzed for the relative expression of insulin receptor mRNA variants in a novel assay using fluorescence-labeled primers and subsequent analysis on an automated DNA sequencer. In subgroups of patients and control subjects, insulin binding and tyrosine...... kinase activity were examined in wheat germ agglutinin-purified insulin receptors isolated from muscle biopsies. Moreover, insulin-stimulated glucose disposal was studied by means of the euglycemic hyperinsulinemic clamp technique. No difference in the relative expression of spliced variants...

  20. Removal of melatonin receptor type 1 induces insulin resistance in the mouse.

    Science.gov (United States)

    Contreras-Alcantara, Susana; Baba, Kenkichi; Tosini, Gianluca

    2010-09-01

    The incidence of obesity, insulin resistance, and type 2 diabetes (T2D) is increasing at an alarming rate worldwide. Emerging experimental evidence suggests that the hormone melatonin plays an important role in the regulation of glucose metabolisms. In this study, we report that removal of melatonin receptor type 1 (MT1) significantly impairs the ability of mice to metabolize glucose and such inability is probably due to an increased insulin resistance in these mice. Our data suggest that MT1 receptors are implicated in the pathogenesis of T2D and open the door for a detailed exploration on the mechanisms by which MT1 receptors signaling may affect glucose metabolism.

  1. Reduced insulin-receptor mediated modulation of striatal dopamine release by basal insulin as a possible contributing factor to hyperdopaminergia in schizophrenia.

    Science.gov (United States)

    Caravaggio, Fernando; Hahn, Margaret; Nakajima, Shinichiro; Gerretsen, Philip; Remington, Gary; Graff-Guerrero, Ariel

    2015-10-01

    Schizophrenia is a severe and chronic neuropsychiatric disorder which affects 1% of the world population. Using the brain imaging technique positron emission tomography (PET) it has been demonstrated that persons with schizophrenia have greater dopamine transmission in the striatum compared to healthy controls. However, little progress has been made as to elucidating other biological mechanisms which may account for this hyperdopaminergic state in this disease. Studies in animals have demonstrated that insulin receptors are expressed on midbrain dopamine neurons, and that insulin from the periphery acts on these receptors to modify dopamine transmission in the striatum. This is pertinent given that several lines of evidence suggest that insulin receptor functioning may be abnormal in the brains of persons with schizophrenia. Post-mortem studies have shown that persons with schizophrenia have less than half the number of cortical insulin receptors compared to healthy persons. Moreover, these post-mortem findings are unlikely due to the effects of antipsychotic treatment; studies in cell lines and animals suggest antipsychotics enhance insulin receptor functioning. Further, hyperinsulinemia - even prior to antipsychotic use - seems to be related to less psychotic symptoms in patients with schizophrenia. Collectively, these data suggest that midbrain insulin receptor functioning may be abnormal in persons with schizophrenia, resulting in reduced insulin-mediated regulation of dopamine transmission in the striatum. Such a deficit may account for the hyperdopaminergic state observed in these patients and would help guide the development of novel treatment strategies. We hypothesize that, (i) insulin receptor expression and/or function is reduced in midbrain dopamine neurons in persons with schizophrenia, (ii) basal insulin should reduce dopaminergic transmission in the striatum via these receptors, and (iii) this modulation of dopaminergic transmission by basal insulin

  2. G Protein–Coupled Receptor Kinase 2 Plays a Relevant Role in Insulin Resistance and Obesity

    Science.gov (United States)

    Garcia-Guerra, Lucia; Nieto-Vazquez, Iria; Vila-Bedmar, Rocio; Jurado-Pueyo, María; Zalba, Guillermo; Díez, Javier; Murga, Cristina; Fernández-Veledo, Sonia; Mayor, Federico; Lorenzo, Margarita

    2010-01-01

    OBJECTIVE Insulin resistance is associated with the pathogenesis of metabolic disorders as type 2 diabetes and obesity. Given the emerging role of signal transduction in these syndromes, we set out to explore the possible role that G protein–coupled receptor kinase 2 (GRK2), first identified as a G protein–coupled receptor regulator, could have as a modulator of insulin responses. RESEARCH DESIGN AND METHODS We analyzed the influence of GRK2 levels in insulin signaling in myoblasts and adipocytes with experimentally increased or silenced levels of GRK2, as well as in GRK2 hemizygous animals expressing 50% lower levels of this kinase in three different models of insulin resistance: tumor necrosis factor-α (TNF-α) infusion, aging, and high-fat diet (HFD). Glucose transport, whole-body glucose and insulin tolerance, the activation status of insulin pathway components, and the circulating levels of important mediators were measured. The development of obesity and adipocyte size with age and HFD was analyzed. RESULTS Altering GRK2 levels markedly modifies insulin-mediated signaling in cultured adipocytes and myocytes. GRK2 levels are increased by ∼2-fold in muscle and adipose tissue in the animal models tested, as well as in lymphocytes from metabolic syndrome patients. In contrast, hemizygous GRK2 mice show enhanced insulin sensitivity and do not develop insulin resistance by TNF-α, aging, or HFD. Furthermore, reduced GRK2 levels induce a lean phenotype and decrease age-related adiposity. CONCLUSIONS Overall, our data identify GRK2 as an important negative regulator of insulin effects, key to the etiopathogenesis of insulin resistance and obesity, which uncovers this protein as a potential therapeutic target in the treatment of these disorders. PMID:20627936

  3. Insulin decreases atherosclerosis by inducing endothelin receptor B expression

    DEFF Research Database (Denmark)

    Park, Kyoungmin; Mima, Akira; Li, Qian

    2016-01-01

    ) in the endothelia of Apoe(-/-) mice (Irs1/Apoe(-/-)) increased insulin signaling and function in the aorta. Atherosclerosis was significantly reduced in Irs1/ApoE(-/-) mice on diet-induced hyperinsulinemia and hyperglycemia. The mechanism of insulin's enhanced antiatherogenic actions in EC was related to remarkable...... overexpression in the endothelia of Aki/ApoE(-/-) mice significantly decreased atherosclerosis. Interestingly, endothelial EDNRB expression was selectively reduced in intima of arteries from diabetic patients and rodents. However, endothelial EDNRB expression was upregulated by insulin via P13K/Akt pathway...

  4. Human insulin analogues modified at the B26 site reveal a hormone conformation that is undetected in the receptor complex

    Energy Technology Data Exchange (ETDEWEB)

    Žáková, Lenka; Kletvíková, Emília; Lepšík, Martin; Collinsová, Michaela [Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10 Prague 6 (Czech Republic); Watson, Christopher J.; Turkenburg, Johan P. [The University of York, Heslington, York YO10 5DD (United Kingdom); Jiráček, Jiří [Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10 Prague 6 (Czech Republic); Brzozowski, Andrzej M., E-mail: marek.brzozowski@york.ac.uk [The University of York, Heslington, York YO10 5DD (United Kingdom); Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10 Prague 6 (Czech Republic)

    2014-10-01

    [AsnB26]- and [GlyB26]-insulin mutants attain a B26-turn like fold without assistance of chemical modifications. Their structures match the insulin receptor interface and expand the spectrum of insulin conformations. The structural characterization of the insulin–insulin receptor (IR) interaction still lacks the conformation of the crucial B21–B30 insulin region, which must be different from that in its storage forms to ensure effective receptor binding. Here, it is shown that insulin analogues modified by natural amino acids at the TyrB26 site can represent an active form of this hormone. In particular, [AsnB26]-insulin and [GlyB26]-insulin attain a B26-turn-like conformation that differs from that in all known structures of the native hormone. It also matches the receptor interface, avoiding substantial steric clashes. This indicates that insulin may attain a B26-turn-like conformation upon IR binding. Moreover, there is an unexpected, but significant, binding specificity of the AsnB26 mutant for predominantly the metabolic B isoform of the receptor. As it is correlated with the B26 bend of the B-chain of the hormone, the structures of AsnB26 analogues may provide the first structural insight into the structural origins of differential insulin signalling through insulin receptor A and B isoforms.

  5. Hepatic structural enhancement and insulin resistance amelioration due to AT1 receptor blockade.

    Science.gov (United States)

    Souza-Mello, Vanessa

    2017-01-18

    Over the last decade, the role of renin-angiotensin system (RAS) on the development of obesity and its comorbidities has been extensively addressed. Both circulating and local RAS components are up-regulated in obesity and involved in non-alcoholic fatty liver disease onset. Pharmacological manipulations of RAS are viable strategies to tackle metabolic impairments caused by the excessive body fat mass. Renin inhibitors rescue insulin resistance, but do not have marked effects on hepatic steatosis. However, angiotensin-converting enzyme inhibitors and angiotensin receptor blockers (ARB) yield beneficial hepatic remodeling. ARBs elicit body mass loss and normalize insulin levels, tackling insulin resistance. Also, this drug class increases adiponectin levels, besides countering interleukin-6, tumoral necrosis factor-alpha, and transforming growth factor-beta 1. The latter is essential to prevent from liver fibrosis. When conjugated with peroxisome proliferator-activated receptor (PPAR)-alpha activation, ARB fully rescues fatty liver. These effects might be orchestrated by an indirect up-regulation of MAS receptor due to angiotensin II receptor type 1 (AT1R) blockade. These associations of ARB with PPAR activation and ACE2-angiotensin (ANG) (1-7)-MAS receptor axis deserve a better understanding. This editorial provides a brief overview of the current knowledge regarding AT1R blockade effects on sensitivity to insulin and hepatic structural alterations as well as the intersections of AT1R blockade with peroxisome proliferator-activated receptor activation and ACE2-ANG (1-7) - MAS receptor axis.

  6. Disruption of growth hormone receptor prevents calorie restriction from improving insulin action and longevity.

    Directory of Open Access Journals (Sweden)

    Michael S Bonkowski

    Full Text Available Most mutations that delay aging and prolong lifespan in the mouse are related to somatotropic and/or insulin signaling. Calorie restriction (CR is the only intervention that reliably increases mouse longevity. There is considerable phenotypic overlap between long-lived mutant mice and normal mice on chronic CR. Therefore, we investigated the interactive effects of CR and targeted disruption or knock out of the growth hormone receptor (GHRKO in mice on longevity and the insulin signaling cascade. Every other day feeding corresponds to a mild (i.e. 15% CR which increased median lifespan in normal mice but not in GHRKO mice corroborating our previous findings on the effects of moderate (30% CR on the longevity of these animals. To determine why insulin sensitivity improves in normal but not GHRKO mice in response to 30% CR, we conducted insulin stimulation experiments after one year of CR. In normal mice, CR increased the insulin stimulated activation of the insulin signaling cascade (IR/IRS/PI3K/AKT in liver and muscle. Livers of GHRKO mice responded to insulin by increased activation of the early steps of insulin signaling, which was dissipated by altered PI3K subunit abundance which putatively inhibited AKT activation. In the muscle of GHRKO mice, there was elevated downstream activation of the insulin signaling cascade (IRS/PI3K/AKT in the absence of elevated IR activation. Further, we found a major reduction of inhibitory Ser phosphorylation of IRS-1 seen exclusively in GHRKO muscle which may underpin their elevated insulin sensitivity. Chronic CR failed to further modify the alterations in insulin signaling in GHRKO mice as compared to normal mice, likely explaining or contributing to the absence of CR effects on insulin sensitivity and longevity in these long-lived mice.

  7. Removal of Melatonin Receptor Type 1 Induces Insulin Resistance in the Mouse

    OpenAIRE

    Contreras-Alcantara, Susana; Baba, Kenkichi; Tosini, Gianluca

    2010-01-01

    The incidence of obesity, insulin resistance and type 2 diabetes (T2D) is increasing at an alarming rate worldwide. Emerging experimental evidence suggests that the hormone melatonin plays an important role in the regulation of glucose metabolisms. In this study we report that removal of melatonin receptor type 1 (MT1) significantly impairs the ability of mice to metabolize glucose and such inability is probably due to an increased insulin resistance in these mice. Our data suggest that MT1 r...

  8. All-atom structural models of insulin binding to the insulin receptor in the presence of a tandem hormone-binding element.

    Science.gov (United States)

    Vashisth, Harish; Abrams, Cameron F

    2013-06-01

    Insulin regulates blood glucose levels in higher organisms by binding to and activating insulin receptor (IR), a constitutively homodimeric glycoprotein of the receptor tyrosine kinase (RTK) superfamily. Therapeutic efforts in treating diabetes have been significantly impeded by the absence of structural information on the activated form of the insulin/IR complex. Mutagenesis and photo-crosslinking experiments and structural information on insulin and apo-IR strongly suggest that the dual-chain insulin molecule, unlike the related single-chain insulin-like growth factors, binds to IR in a very different conformation than what is displayed in storage forms of the hormone. In particular, hydrophobic residues buried in the core of the folded insulin molecule engage the receptor. There is also the possibility of plasticity in the receptor structure based on these data, which may in part be due to rearrangement of the so-called CT-peptide, a tandem hormone-binding element of IR. These possibilities provide opportunity for large-scale molecular modeling to contribute to our understanding of this system. Using various atomistic simulation approaches, we have constructed all-atom structural models of hormone/receptor complexes in the presence of CT in its crystallographic position and a thermodynamically favorable displaced position. In the "displaced-CT" complex, many more insulin-receptor contacts suggested by experiments are satisfied, and our simulations also suggest that R-insulin potentially represents the receptor-bound form of hormone. The results presented in this work have further implications for the design of receptor-specific agonists/antagonists.

  9. Label-Free Proteomic Identification of Endogenous, Insulin-Stimulated Interaction Partners of Insulin Receptor Substrate-1

    Science.gov (United States)

    Geetha, Thangiah; Langlais, Paul; Luo, Moulun; Mapes, Rebekka; Lefort, Natalie; Chen, Shu-Chuan; Mandarino, Lawrence J.; Yi, Zhengping

    2011-03-01

    Protein-protein interactions are key to most cellular processes. Tandem mass spectrometry (MS/MS)-based proteomics combined with co-immunoprecipitation (CO-IP) has emerged as a powerful approach for studying protein complexes. However, a majority of systematic proteomics studies on protein-protein interactions involve the use of protein overexpression and/or epitope-tagged bait proteins, which might affect binding stoichiometry and lead to higher false positives. Here, we report an application of a straightforward, label-free CO-IP-MS/MS method, without the use of protein overexpression or protein tags, to the investigation of changes in the abundance of endogenous proteins associated with a bait protein, which is in this case insulin receptor substrate-1 (IRS-1), under basal and insulin stimulated conditions. IRS-1 plays a central role in the insulin signaling cascade. Defects in the protein-protein interactions involving IRS-1 may lead to the development of insulin resistance and type 2 diabetes. HPLC-ESI-MS/MS analyses identified eleven novel endogenous insulin-stimulated IRS-1 interaction partners in L6 myotubes reproducibly, including proteins play an important role in protein dephosphorylation [protein phosphatase 1 regulatory subunit 12A, (PPP1R12A)], muscle contraction and actin cytoskeleton rearrangement, endoplasmic reticulum stress, and protein folding, as well as protein synthesis. This novel application of label-free CO-IP-MS/MS quantification to assess endogenous interaction partners of a specific protein will prove useful for understanding how various cell stimuli regulate insulin signal transduction.

  10. Mammary tumorigenesis and metastasis caused by overexpression of insulin receptor substrate 1 (IRS-1) or IRS-2

    Science.gov (United States)

    Insulin receptor substrates (IRSs) are signaling adaptors that play a major role in the metabolic and mitogenic actions of insulin and insulin-like growth factors. Reports have recently noted increased levels, or activity, of IRSs in many human cancers, and some have linked this to poor patient prog...

  11. Insulin Excites Anorexigenic Proopiomelanocortin Neurons via Activation of Canonical Transient Receptor Potential Channels

    Science.gov (United States)

    Qiu, Jian; Zhang, Chunguang; Borgquist, Amanda; Nestor, Casey C; Smith, Arik W.; Bosch, Martha A.; Ku, Stephen; Wagner, Edward J.; Rønnekleiv, Oline K.; Kelly, Martin J.

    2014-01-01

    SUMMARY Proopiomelanocortin (POMC) neurons within the hypothalamic arcuate nucleus are vital anorexigenic neurons. Although both the leptin receptor and insulin receptor are coupled to activation of phosphatidylinositide3-kinase (PI3K) in POMC neurons, they are thought to have disparate actions on POMC excitability. Using whole-cell recording and selective pharmacological tools, we have found that similar to leptin, purified insulin depolarized POMC, and adjacent kisspeptin neurons via activation of TRPC5 channels, which are highly expressed in these neurons. In contrast, insulin hyperpolarized and inhibited NPY/AgRP neurons via activation of KATP channels. Moreover, Zn2+, which is found in insulin formulations at nanomolar concentrations, inhibited POMC neurons via activation of KATP channels. Finally as predicted, insulin given intracerebroventrically robustly inhibited food intake and activated c-fos expression in arcuate POMC neurons. Our results show that purified insulin excites POMC neurons in the arcuate nucleus, which we propose is a major mechanism by which insulin regulates energy homeostasis. PMID:24703699

  12. Role of Peroxisome Proliferator-Activated Receptor Gamma in Glucose-induced Insulin Secretion

    Institute of Scientific and Technical Information of China (English)

    Ze-Kuan XU; Neng-Guin CHEN; Chang-Yan MA; Zhuo-Xian MENG; Yu-Jie SUN; Xiao HAN

    2006-01-01

    Peroxisome proliferator-activated receptor (PPAR) isoforms (α and γ) are known to be expressed in pancreatic islets as well as in insulin-producing cell lines. Ligands of PPAR have been shown to enhance glucose-induced insulin secretion in rat pancreatic islets. However, their effect on insulin secretion is still unclear. To understand the molecular mechanism by which PPARγ exerts its effect on glucoseinduced insulin secretion, we examined the endogenous activity of PPAR isoforms, and studied the PPARγfunction and its target gene expression in INS-1 cells. We found that: (1) endogenous PPARγ was activated in a ligand-dependent manner in INS-1 cells; (2) overexpression of PPARγ in the absence of PPARγ ligands enhanced glucose-induced insulin secretion, which indicates that the increased glucose-induced insulin secretion is a PPARγ-mediated event; (3) the addition of both PPARγ and retinoid X receptor (RXR) ligands showed a synergistic effect on the augmentation of reporter activity, suggesting that the hetero-dimerization of PPARγand RXR is required for the regulation of the target genes; (4) PPARs upregulated both the glucose transporter 2 (GLUT2) and Cbl-associated protein (CAP) genes in INS-1 cells. Our findings suggest an important mechanistic pathway in which PPARγ enhances glucose-induced insulin secretion by activating the expression of GLUT2 and CAP genes in a ligand-dependent manner.

  13. Insulin receptor signaling in the development of neuronal structure and function

    Directory of Open Access Journals (Sweden)

    Cline Hollis T

    2010-03-01

    Full Text Available Abstract Sensory experience plays a crucial role in regulating neuronal shape and in developing synaptic contacts during brain formation. These features are required for a neuron to receive, integrate, and transmit signals within the neuronal network so that animals can adapt to the constant changing environment. Insulin receptor signaling, which has been extensively studied in peripheral organ systems such as liver, muscle and adipocyte, has recently been shown to play important roles in the central nervous system. Here we review the current understanding of the underlying mechanisms that regulate structural and functional aspects of circuit development, particularly with respect to the role of insulin receptor signaling in synaptic function and the development of dendritic arbor morphology. The potential link between insulin receptor signaling malfunction and neurological disorders will also be discussed.

  14. Resistin does not down-regulate the transcription of insulin receptor promoter

    Institute of Scientific and Technical Information of China (English)

    Xiao-zhi QIAO; Xian-feng WANG; Zhe-rong XU; Yun-mei YANG

    2008-01-01

    Objective: To detect the effect of resistin on the transcription of insulin receptor promoter. Methods: Luciferase reporter gene was fused downstream of human insulin receptor promoter and the enzymatic activity of luciferase was determined in the presence or absence of resistin. The resistin expressed with plasmid was stained with antibody against Myc tag which was in frame fused with resistin coding sequence, and then imaged with confocal microscopy. Results: The treatment of pIRP-LUC transfected cells with recombinant resistin did not result in significant difference in the enzymatic activity of luciferase compared to the untreated cells. Cell staining showed that green fluorescence could be observed in the cytoplasm, but not in the nucleus. Conclusion: The results suggest that the endogenous resistin may functionally locate in the cytoplasm, but does not enter the nucleus and not down-regulate the transcription of insulin receptor promoter.

  15. Polymorphisms of Exon 17 of Insulin-Receptor Gene in Pathogenesis of Human Disorders With Insulin Resistance

    Institute of Scientific and Technical Information of China (English)

    LU WANG; JIE MI; XIAO-YUAN ZHAO; JIAN-XIN WU; HONG CHENG; ZHI-KUN ZHANG; XIU-YUAN DING; DONG-QING HOU; HUILI

    2004-01-01

    To investigate the relationship between polymorphisms of insulin-receptor (INSR) gene and insulin resistance in a population-based study in China. Methods Polymerase Chain Reaction (PCR) was used to the amplify Exon 17 of INSR gene and all amplified products were analyzed by direct sequencing. Results Six single-nucleotide polymorphisms (SNPs) were found at the following loci: T to TC at the locus of 10699 (Tyr984), G to GC at the locus of 10731 (Glu994), Deletion G at the locus of 10798 (Asp1017), C to T/TC at the locus of 10923 (His1058), C to CA at the locus of 10954 (Leu1069), and T to TA at the locus of 10961 (Phe1071), which might not change the amino acid sequence. The data were in agreement with the test of Hardy-Weinberg balance (P>0.05). Among the 345 cases, all clinical indices were higher in males than in females except for HDL cholesterol (P0.05). After sex stratification in analysis,all allele frequencies on the six loci of SNPs of Exon 17 had different distributions between the insulin resistant group and the control group, but P>0.05. Conclusion SNPs of Exon 17 of INSR gene are unlikely to play a direct role in the pathogenesis of human disorders with insulin resistance.

  16. Diabetes mellitus caused by mutations in human insulin: analysis of impaired receptor binding of insulins Wakayama, Los Angeles and Chicago using pharmacoinformatics.

    Science.gov (United States)

    Islam, Md Ataul; Bhayye, Sagar; Adeniyi, Adebayo A; Soliman, Mahmoud E S; Pillay, Tahir S

    2017-03-01

    Several naturally occuring mutations in the human insulin gene are associated with diabetes mellitus. The three known mutant molecules, Wakayama, Los Angeles and Chicago were evaluated using molecular docking and molecular dynamics (MD) to analyse mechanisms of deprived binding affinity for insulin receptor (IR). Insulin Wakayama, is a variant in which valine at position A3 is substituted by leucine, while in insulin Los Angeles and Chicago, phenylalanine at positions B24 and B25 is replaced by serine and leucine, respectively. These mutations show radical changes in binding affinity for IR. The ZDOCK server was used for molecular docking, while AMBER 14 was used for the MD study. The published crystal structure of IR bound to natural insulin was also used for MD. The binding interactions and MD trajectories clearly explained the critical factors for deprived binding to the IR. The surface area around position A3 was increased when valine was substituted by leucine, while at positions B24 and B25 aromatic amino acid phenylalanine replaced by non-aromatic serine and leucine might be responsible for fewer binding interactions at the binding site of IR that leads to instability of the complex. In the MD simulation, the normal mode analysis, rmsd trajectories and prediction of fluctuation indicated instability of complexes with mutant insulin in order of insulin native insulin insulin Chicago insulin Los Angeles insulin Wakayama molecules which corresponds to the biological evidence of the differing affinities of the mutant insulins for the IR.

  17. Plasma adiponectin concentration is associated with skeletal muscle insulin receptor tyrosine phosphorylation, and low plasma concentration precedes a decrease in whole-body insulin sensitivity in humans

    DEFF Research Database (Denmark)

    Stefan, Norbert; Vozarova, Barbora; Funahashi, Tohru;

    2002-01-01

    -induced tyrosine phosphorylation of the insulin receptor (IR) and also increase whole-body insulin sensitivity. To further characterize the relationship between plasma adiponectin concentration and insulin sensitivity in humans, we examined 1) the cross-sectional association between plasma adiponectin......Adiponectin, the most abundant adipose-specific protein, has been found to be negatively associated with degree of adiposity and positively associated with insulin sensitivity in Pima Indians and other populations. Moreover, adiponectin administration to rodents has been shown to increase insulin...... concentration and skeletal muscle IR tyrosine phosphorylation and 2) the prospective effect of plasma adiponectin concentration at baseline on change in insulin sensitivity. Fasting plasma adiponectin concentration, body composition (hydrodensitometry or dual energy X-ray absorptiometry), insulin sensitivity...

  18. Venus Kinase Receptors at the Crossroads of Insulin Signaling: Their Role in Reproduction for Helminths and Insects

    OpenAIRE

    Dissous, Colette

    2015-01-01

    Venus kinase receptors (VKRs) are invertebrate receptor tyrosine kinases (TKs) first discovered in the human parasite Schistosoma. They contain an extracellular Venus FlyTrap module similar to the ligand-binding domain of G protein-coupled receptors of class C and an intracellular TK domain similar to that of insulin receptors. VKRs are present from cnidarians to echinoderms. They were shown to be activated by amino-acids, to induce insulin-like intracellular pathways, and to be highly expres...

  19. Association of the insulin-receptor variant Met-985 with hyperglycemia and non-insulin-dependent diabetes mellitus in the Netherlands: A population-based study

    Energy Technology Data Exchange (ETDEWEB)

    `t Hart, L.M.; Maassen, J.A. [Leiden Univ. (Netherlands); Does, F.E.E. van der [Free Univ., Amsterdam (Netherlands)] [and others

    1996-11-01

    One of the characteristics of non-insulin-dependent diabetes mellitus (NIDDM) is the presence of insulin. Most NIDDM patients have a normal sequence of the insulin receptor, indicating that, if insulin-receptor mutations contribute to the development of NIDDM, they will be present only in a minor fraction of the NIDDM population. The goal of the present study was to examine whether insulin-receptor mutations contribute to the development of NIDDM. We examined 161 individuals with NIDDM and 538 healthy controls from the population-based Rotterdam study for the presence of mutations in the insulin-receptor gene by SSCP. A heterozygous mutation changing valine-985 into methionine was detected in 5.6% of diabetic subjects and in 1.3% of individuals with normal oral glucose tolerance test. Adjusted for age, gender, and body-mass index, this revealed a relative risk for diabetes of 4.49 (95% confidence interval 1.59-12.25) for Met-985 carriers. When the total study group was analyzed, the prevalence of the mutation increased with increasing serum glucose levels (test for trend P < .005). We conclude that the Met-985 insulin-receptor variant associates with hyperglycemia and represents a risk factor for NIDDM. 30 refs., 3 figs., 1 tab.

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

    DEFF Research Database (Denmark)

    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 ty...... 2 diabetes (T2DM) with PPARγ activation, mainly focusing on adipose tissue....

  1. Insulin receptors mediate growth effects in cultured fetal neurons. I. Rapid stimulation of protein synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Heidenreich, K.A.; Toledo, S.P. (Univ. of California-San Diego, La Jolla (USA))

    1989-09-01

    In this study we have examined the effects of insulin on protein synthesis in cultured fetal chick neurons. Protein synthesis was monitored by measuring the incorporation of (3H)leucine (3H-leu) into trichloroacetic acid (TCA)-precipitable protein. Upon addition of 3H-leu, there was a 5-min lag before radioactivity occurred in protein. During this period cell-associated radioactivity reached equilibrium and was totally recovered in the TCA-soluble fraction. After 5 min, the incorporation of 3H-leu into protein was linear for 2 h and was inhibited (98%) by the inclusion of 10 micrograms/ml cycloheximide. After 24 h of serum deprivation, insulin increased 3H-leu incorporation into protein by approximately 2-fold. The stimulation of protein synthesis by insulin was dose dependent (ED50 = 70 pM) and seen within 30 min. Proinsulin was approximately 10-fold less potent than insulin on a molar basis in stimulating neuronal protein synthesis. Insulin had no effect on the TCA-soluble fraction of 3H-leu at any time and did not influence the uptake of (3H)aminoisobutyric acid into neurons. The isotope ratio of 3H-leu/14C-leu in the leucyl tRNA pool was the same in control and insulin-treated neurons. Analysis of newly synthesized proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that insulin uniformly increased the incorporation of 14C-leu into all of the resolved neuronal proteins. We conclude from these data that (1) insulin rapidly stimulates overall protein synthesis in fetal neurons independent of amino acid uptake and aminoacyl tRNA precursor pools; (2) stimulation of protein synthesis is mediated by the brain subtype of insulin receptor; and (3) insulin is potentially an important in vivo growth factor for fetal central nervous system neurons.

  2. Insulin receptor isoform A ameliorates long-term glucose intolerance in diabetic mice.

    Science.gov (United States)

    Diaz-Castroverde, Sabela; Gómez-Hernández, Almudena; Fernández, Silvia; García-Gómez, Gema; Di Scala, Marianna; González-Aseguinolaza, Gloria; Fernández-Millán, Elisa; González-Rodríguez, Águeda; García-Bravo, María; Chambon, Pierre; Álvarez, Carmen; Perdomo, Liliana; Beneit, Nuria; Escribano, Oscar; Benito, Manuel

    2016-11-01

    Type 2 diabetes mellitus is a complex metabolic disease and its pathogenesis involves abnormalities in both peripheral insulin action and insulin secretion. Previous in vitro data showed that insulin receptor isoform A, but not B, favours basal glucose uptake through its specific association with endogenous GLUT1/2 in murine hepatocytes and beta cells. With this background, we hypothesized that hepatic expression of insulin receptor isoform A in a mouse model of type 2 diabetes could potentially increase the glucose uptake of these cells, decreasing the hyperglycaemia and therefore ameliorating the diabetic phenotype. To assure this hypothesis, we have developed recombinant adeno-associated viral vectors expressing insulin receptor isoform A (IRA) or isoform B (IRB) under the control of a hepatocyte--specific promoter. Our results demonstrate that in the long term, hepatic expression of IRA in diabetic mice is more efficient than IRB in ameliorating glucose intolerance. Consequently, it impairs the induction of compensatory mechanisms through beta cell hyperplasia and/or hypertrophy that finally lead to beta cell failure, reverting the diabetic phenotype in about 8 weeks. Our data suggest that long-term hepatic expression of IRA could be a promising therapeutic approach for the treatment of type 2 diabetes mellitus.

  3. Insulin receptor and IGF-I receptor Bioactivity in Health and Disease

    NARCIS (Netherlands)

    A.J. Varewijck (Aimee)

    2013-01-01

    textabstractInsulin was discovered in 1921 by Banting and Best and its structure elucidated in 1955. The first insulin bioassays appeared in the 1940s. First, rats were injected with a range of known concentrations of purified commercial or ‘standard’ insulin and the subsequent fall in blood glucose

  4. Unusual duplication of the insulin-like receptor in the crustacean Daphnia pulex

    Directory of Open Access Journals (Sweden)

    Dufresne France

    2010-10-01

    Full Text Available Abstract Background The insulin signaling pathway (ISP has a key role in major physiological events like carbohydrate metabolism and growth regulation. The ISP has been well described in vertebrates and in a few invertebrate model organisms but remains largely unexplored in non-model invertebrates. This study is the first detailed genomic study of this pathway in a crustacean species, Daphnia pulex. Results The Daphnia pulex draft genome sequence assembly was scanned for major components of the ISP with a special attention to the insulin-like receptor. Twenty three putative genes are reported. The pathway appears to be generally well conserved as genes found in other invertebrates are present. Major findings include a lower number of insulin-like peptides in Daphnia as compared to other invertebrates and the presence of multiple insulin-like receptors (InR, with four genes as opposed to a single one in other invertebrates. Genes encoding for the Dappu_InR are likely the result of three duplication events and bear some unusual features. Dappu_InR-4 has undergone extensive evolutionary divergence and lacks the conserved site of the catalytic domain of the receptor tyrosine kinase. Dappu_InR-1 has a large insert and lacks the transmembranal domain in the β-subunit. This domain is also absent in Dappu_InR-3. Dappu_InR-2 is characterized by the absence of the cystein-rich region. Real-time q-PCR confirmed the expression of all four receptors. EST analyses of cDNA libraries revealed that the four receptors were differently expressed under various conditions. Conclusions Duplications of the insulin receptor genes might represent an important evolutionary innovation in Daphnia as they are known to exhibit extensive phenotypic plasticity in body size and in the size of defensive structures in response to predation.

  5. Receptor-isoform-selective insulin analogues give tissue-preferential effects

    DEFF Research Database (Denmark)

    Vienberg, Sara Gry; Bouman, Stephan D; Sørensen, Heidi

    2011-01-01

    The relative expression patterns of the two IR (insulin receptor) isoforms, +/- exon 11 (IR-B/IR-A respectively), are tissue-dependent. Therefore we have developed insulin analogues with different binding affinities for the two isoforms to test whether tissue-preferential biological effects can...... be attained. In rats and mice, IR-B is the most prominent isoform in the liver (> 95%) and fat (> 90%), whereas in muscles IR-A is the dominant isoform (> 95%). As a consequence, the insulin analogue INS-A, which has a higher relative affinity for human IR-A, had a higher relative potency [compared with HI...... (human insulin)] for glycogen synthesis in rat muscle strips (26%) than for glycogen accumulation in rat hepatocytes (5%) and for lipogenesis in rat adipocytes (4%). In contrast, the INS-B analogue, which has an increased affinity for human IR-B, had higher relative potencies (compared with HI...

  6. A receptor state space model of the insulin signalling system in glucose transport.

    Science.gov (United States)

    Gray, Catheryn W; Coster, Adelle C F

    2015-12-01

    Insulin is a potent peptide hormone that regulates glucose levels in the blood. Insulin-sensitive cells respond to insulin stimulation with the translocation of glucose transporter 4 (GLUT4) to the plasma membrane (PM), enabling the clearance of glucose from the blood. Defects in this process can give rise to insulin resistance and ultimately diabetes. One widely cited model of insulin signalling leading to glucose transport is that of Sedaghat et al. (2002) Am. J. Physiol. Endocrinol. Metab. 283, E1084-E1101. Consisting of 20 deterministic ordinary differential equations (ODEs), it is the most comprehensive model of insulin signalling to date. However, the model possesses some major limitations, including the non-conservation of key components. In the current work, we detail mathematical and sensitivity analyses of the Sedaghat model. Based on the results of these analyses, we propose a reduced state space model of the insulin receptor subsystem. This reduced model maintains the input-output relation of the original model but is computationally more efficient, analytically tractable and resolves some of the limitations of the Sedaghat model.

  7. Aptamer-based single-molecule imaging of insulin receptors in living cells

    Science.gov (United States)

    Chang, Minhyeok; Kwon, Mijin; Kim, Sooran; Yunn, Na-Oh; Kim, Daehyung; Ryu, Sung Ho; Lee, Jong-Bong

    2014-05-01

    We present a single-molecule imaging platform that quantitatively explores the spatiotemporal dynamics of individual insulin receptors in living cells. Modified DNA aptamers that specifically recognize insulin receptors (IRs) with a high affinity were selected through the SELEX process. Using quantum dot-labeled aptamers, we successfully imaged and analyzed the diffusive motions of individual IRs in the plasma membranes of a variety of cell lines (HIR, HEK293, HepG2). We further explored the cholesterol-dependent movement of IRs to address whether cholesterol depletion interferes with IRs and found that cholesterol depletion of the plasma membrane by methyl-β-cyclodextrin reduces the mobility of IRs. The aptamer-based single-molecule imaging of IRs will provide better understanding of insulin signal transduction through the dynamics study of IRs in the plasma membrane.

  8. Hyperinsulinemia: effect on cardiac mass/function, angiotensin II receptor expression, and insulin signaling pathways.

    Science.gov (United States)

    Samuelsson, Anne-Maj; Bollano, Entela; Mobini, Reza; Larsson, Britt-Mari; Omerovic, Elmir; Fu, Michael; Waagstein, Finn; Holmäng, Agneta

    2006-08-01

    To investigate the association between hyperinsulinemia and cardiac hypertrophy, we treated rats with insulin for 7 wk and assessed effects on myocardial growth, vascularization, and fibrosis in relation to the expression of angiotensin II receptors (AT-R). We also characterized insulin signaling pathways believed to promote myocyte growth and interact with proliferative responses mediated by G protein-coupled receptors, and we assessed myocardial insulin receptor substrate-1 (IRS-1) and p110 alpha catalytic and p85 regulatory subunits of phospatidylinositol 3 kinase (PI3K), Akt, MEK, ERK1/2, and S6 kinase-1 (S6K1). Left ventricular (LV) geometry and performance were evaluated echocardiographically. Insulin decreased AT1a-R mRNA expression but increased protein levels and increased AT2-R mRNA and protein levels and phosphorylation of IRS-1 (Ser374/Tyr989), MEK1/2 (Ser218/Ser222), ERK1/2 (Thr202/Tyr204), S6K1 (Thr421/Ser424/Thr389), Akt (Thr308/Thr308), and PI3K p110 alpha but not of p85 (Tyr508). Insulin increased LV mass and relative wall thickness and reduced stroke volume and cardiac output. Histochemical examination demonstrated myocyte hypertrophy and increases in interstitial fibrosis. Metoprolol plus insulin prevented the increase in relative wall thickness, decreased fibrosis, increased LV mass, and improved function seen with insulin alone. Thus our data demonstrate that chronic hyperinsulinemia decreases AT1a-to-AT2 ratio and increases MEK-ERK1/2 and S6K1 pathway activity related to hypertrophy. These changes might be crucial for increased cardiovascular growth and fibrosis and signs of impaired LV function.

  9. Insulin receptor isoforms : an integrated view focused on gestational diabetes mellitus

    NARCIS (Netherlands)

    Westermeier, F.; Sáez, T.; Arroyo, P.; Toledo, F.; Gutierrez, J.; Sanhueza, C.; Pardo, F.; Leiva, A.; Sobrevia, L.

    2016-01-01

    The human insulin receptor (IR) exists in two isoforms that differ by the absence (IR-A) or the presence (IR-B) of a 12-amino acid segment encoded by exon 11. Both isoforms are functionally distinct regarding their binding affinities and intracellular signalling. However, the underlying mechanisms r

  10. Study of Androgen and Androgen Receptor in Relation to Insulin Resistance in Polycystic Ovary Syndrome

    Institute of Scientific and Technical Information of China (English)

    初永丽; 孙永玉; 邱红玉

    2003-01-01

    In order to investigate the relationship between serum testosterone level and expression of androgen receptors in ovary in relation to insulin resistance in polycystic ovary syndrome (PCOS). Serum testosterone levels were determined by radioimmunoassay in 17 patients with PCOS and 20 cases as control group. The expression of androgen receptor in ovary was detected by immunohistochemistry method. The results showed that serum testosterone level [ (3. 1± 1.5) nmol/L] and insulin resistance index (0. 85±0. 49) in patients with PCOS were significantly higher than in control group (P<0. 05), and showed a positive relation (r=0. 65, P<0. 01). The expression levels of androgen receptor in ovary of patients with PCOS were significantly higher than that in control group (P<0.05). The optical density value was positively related with insulin resistance index (r=0.59,P<0. 01). It was concluded that androgen and androgen receptor could accelerate insulin resistance and the interaction of them might aggravate the pathophysiological change in PCOS.

  11. The insulin-like growth factor 1 receptor in cancer : Old focus, new future

    NARCIS (Netherlands)

    Hartog, Hermien; Wesseling, Jelle; Boezen, H. Marike; van der Graaf, Winette T. A.

    2007-01-01

    The importance of insulin-like growth factor 1 receptor (IGF-1R) signalling in malignant behaviour of tumour cells is well established. Currently, development of drugs targeting the IGF-1R as anticancer treatment is emerging. Several IGF-1R targeting strategies are being investigated in phases I and

  12. The insulin-like growth factor 1 receptor in cancer : Old focus, new future

    NARCIS (Netherlands)

    Hartog, Hermien; Wesseling, Jelle; Boezen, H. Marike; van der Graaf, Winette T. A.

    2007-01-01

    The importance of insulin-like growth factor 1 receptor (IGF-1R) signalling in malignant behaviour of tumour cells is well established. Currently, development of drugs targeting the IGF-1R as anticancer treatment is emerging. Several IGF-1R targeting strategies are being investigated in phases I and

  13. The insulin-like growth factor 1 receptor in cancer: old focus, new future.

    NARCIS (Netherlands)

    Hartog, H. de; Wesseling, J.; Boezen, H.M.; Graaf, W.T.A. van der

    2007-01-01

    The importance of insulin-like growth factor 1 receptor (IGF-1R) signalling in malignant behaviour of tumour cells is well established. Currently, development of drugs targeting the IGF-1R as anticancer treatment is emerging. Several IGF-1R targeting strategies are being investigated in phases I and

  14. Expression, receptor binding, and biophysical characterization of guinea pig insulin desB30

    DEFF Research Database (Denmark)

    Engholm, Ebbe; Hansen, Thomas Hesselhøj; Johansson, Eva;

    2015-01-01

    not indicate the formation of any larger structures of GI desB30 in the presence of various divalent metal ions, but did indicate that GI desB30 has an affinity towards Mn, Co, and Cu ions. Finally, the low affinity for the insulin receptor and the very low affinity for the IGF-I receptor by GI desB30 were......Here we report, for the first time, the heterologous expression of desB30 guinea pig insulin (GI desB30) in the yeast Saccharomyces cerevisiae. The affinities of GI desB30 for the insulin receptor A and the IGF-I receptor were also quantified for the first time. Small-angle X-ray scattering...... and analytical ultracentrifugation studies confirmed that GI desB30 did not form dimers or hexamers, in contrast to human insulin. Sizeexclusion chromatography connected to inductively coupled plasma mass spectrometry revealed that GI desB30 has affinity towards several divalent metal ions. These studies did...

  15. Cannabinoid CB2 receptor potentiates obesity-associated inflammation, insulin resistance and hepatic steatosis.

    Directory of Open Access Journals (Sweden)

    Vanessa Deveaux

    Full Text Available BACKGROUND: Obesity-associated inflammation is of critical importance in the development of insulin resistance and non-alcoholic fatty liver disease. Since the cannabinoid receptor CB2 regulates innate immunity, the aim of the present study was to investigate its role in obesity-induced inflammation, insulin resistance and fatty liver. METHODOLOGY: Murine obesity models included genetically leptin-deficient ob/ob mice and wild type (WT mice fed a high fat diet (HFD, that were compared to their lean counterparts. Animals were treated with pharmacological modulators of CB2 receptors. Experiments were also performed in mice knock-out for CB2 receptors (Cnr2 -/-. PRINCIPAL FINDINGS: In both HFD-fed WT mice and ob/ob mice, Cnr2 expression underwent a marked induction in the stromal vascular fraction of epididymal adipose tissue that correlated with increased fat inflammation. Treatment with the CB2 agonist JWH-133 potentiated adipose tissue inflammation in HFD-fed WT mice. Moreover, cultured fat pads isolated from ob/ob mice displayed increased Tnf and Ccl2 expression upon exposure to JWH-133. In keeping, genetic or pharmacological inactivation of CB2 receptors decreased adipose tissue macrophage infiltration associated with obesity, and reduced inductions of Tnf and Ccl2 expressions. In the liver of obese mice, Cnr2 mRNA was only weakly induced, and CB2 receptors moderately contributed to liver inflammation. HFD-induced insulin resistance increased in response to JWH-133 and reduced in Cnr2 -/- mice. Finally, HFD-induced hepatic steatosis was enhanced in WT mice treated with JWH-133 and blunted in Cnr2 -/- mice. CONCLUSION/SIGNIFICANCE: These data unravel a previously unrecognized contribution of CB2 receptors to obesity-associated inflammation, insulin resistance and non-alcoholic fatty liver disease, and suggest that CB2 receptor antagonists may open a new therapeutic approach for the management of obesity-associated metabolic disorders.

  16. Insulin directly regulates steroidogenesis via induction of the orphan nuclear receptor DAX-1 in testicular Leydig cells.

    Science.gov (United States)

    Ahn, Seung Won; Gang, Gil-Tae; Kim, Yong Deuk; Ahn, Ryun-Sup; Harris, Robert A; Lee, Chul-Ho; Choi, Hueng-Sik

    2013-05-31

    Testosterone level is low in insulin-resistant type 2 diabetes. Whether this is due to negative effects of high level of insulin on the testes caused by insulin resistance has not been studied in detail. In this study, we found that insulin directly binds to insulin receptors in Leydig cell membranes and activates phospho-insulin receptor-β (phospho-IR-β), phospho-IRS1, and phospho-AKT, leading to up-regulation of DAX-1 (dosage-sensitive sex reversal, adrenal hypoplasia critical region, on chromosome X, gene 1) gene expression in the MA-10 mouse Leydig cell line. Insulin also inhibits cAMP-induced and liver receptor homolog-1 (LRH-1)-induced steroidogenic enzyme gene expression and steroidogenesis. In contrast, knockdown of DAX-1 reversed insulin-mediated inhibition of steroidogenesis. Whether insulin directly represses steroidogenesis through regulation of steroidogenic enzyme gene expression was assessed in insulin-injected mouse models and high fat diet-induced obesity. In insulin-injected mouse models, insulin receptor signal pathway was activated and subsequently inhibited steroidogenesis via induction of DAX-1 without significant change of luteinizing hormone or FSH levels. Likewise, the levels of steroidogenic enzyme gene expression and steroidogenesis were low, but interestingly, the level of DAX-1 was high in the testes of high fat diet-fed mice. These results represent a novel regulatory mechanism of steroidogenesis in Leydig cells. Insulin-mediated induction of DAX-1 in Leydig cells of testis may be a key regulatory step of serum sex hormone level in insulin-resistant states.

  17. Characterization of the insulin sensitivity of ghrelin receptor KO mice using glycemic clamps

    Directory of Open Access Journals (Sweden)

    Morgan Kristen

    2011-01-01

    Full Text Available Abstract Background We and others have demonstrated previously that ghrelin receptor (GhrR knock out (KO mice fed a high fat diet (HFD have increased insulin sensitivity and metabolic flexibility relative to WT littermates. A striking feature of the HFD-fed GhrR KO mouse is the dramatic decrease in hepatic steatosis. To characterize further the underlying mechanisms of glucose homeostasis in GhrR KO mice, we conducted both hyperglycemic (HG and hyperinsulinemic-euglycemic (HI-E clamps. Additionally, we investigated tissue glucose uptake and specifically examined liver insulin sensitivity. Results Consistent with glucose tolerance-test data, in HG clamp experiments, GhrR KO mice showed a reduction in glucose-stimulated insulin release relative to WT littermates. Nevertheless, a robust 1st phase insulin secretion was still achieved, indicating that a healthy β-cell response is maintained. Additionally, GhrR KO mice demonstrated both a significantly increased glucose infusion rate and significantly reduced insulin requirement for maintenance of the HG clamp, consistent with their relative insulin sensitivity. In HI-E clamps, both LFD-fed and HFD-fed GhrR KO mice showed higher peripheral insulin sensitivity relative to WT littermates as indicated by a significant increase in insulin-stimulated glucose disposal (Rd, and decreased hepatic glucose production (HGP. HFD-fed GhrR KO mice showed a marked increase in peripheral tissue glucose uptake in a variety of tissues, including skeletal muscle, brown adipose tissue and white adipose tissue. GhrR KO mice fed a HFD also showed a modest, but significant decrease in conversion of pyruvate to glucose, as would be anticipated if these mice displayed increased liver insulin sensitivity. Additionally, the levels of UCP2 and UCP1 were reduced in the liver and BAT, respectively, in GhrR KO mice relative to WT mice. Conclusions These results indicate that improved glucose homeostasis of GhrR KO mice is

  18. Association of vitamin D receptor gene polymorphisms with insulin resistance and response to vitamin D.

    Science.gov (United States)

    Jain, Reema; von Hurst, Pamela R; Stonehouse, Welma; Love, Donald R; Higgins, Colleen M; Coad, Jane

    2012-03-01

    The objectives of the study were to determine associations between single nucleotide polymorphisms (SNPs) of the vitamin D receptor (VDR) gene and insulin resistance and the effects of these SNPs on changes in insulin sensitivity in response to vitamin D supplementation. The research described here was an extension of the Surya study. Genotyping of the Cdx-2, FokI, BsmI, ApaI, and TaqI SNPs was carried out on 239 South Asian women in New Zealand using polymerase chain reaction-based techniques. Associations of these genotypes and 3' end haplotypes with insulin resistance were determined using multiple regression analysis. Associations between SNP genotypes and responses in insulin sensitivity to vitamin D supplementation (4000 IU vitamin D(3) per day) were also determined for a subset (81) of these women. BsmI BB, ApaI AA, and TaqI tt genotypes were significantly associated with lower insulin resistance compared with BsmI bb, ApaI aa, and TaqI TT, respectively, in the cohort of 239 women. Furthermore, homozygosity of the haplotypes baT and BAt was associated with higher and lower insulin resistance, respectively, compared with no copies of their respective alleles. Of the 81 subjects who were supplemented with vitamin D, women with the FokI Ff genotype showed a significantly greater improvement in insulin sensitivity (increase of 29.4 [2.9, 38.1]) compared with women with the FokI FF genotype (increase of 2.3 [-11.5, 10.1]). This study has highlighted the association of vitamin D responsiveness and insulin resistance with VDR gene polymorphisms. This is the first study to determine associations between all three. Genotyping of the VDR gene may provide a predictive measure for insulin resistance in response to vitamin D intervention.

  19. Human insulin production from a novel mini-proinsulin which has high receptor-binding activity.

    Science.gov (United States)

    Chang, S G; Kim, D Y; Choi, K D; Shin, J M; Shin, H C

    1998-02-01

    To increase the folding efficiency of the insulin precursor and the production yield of insulin, we have designed a mini-proinsulin (M2PI) having the central C-peptide region replaced with a sequence forming a reverse turn. The mini-proinsulin was fused at the N-terminus to a 21-residue fusion partner containing a His10 tag for affinity purification. The gene for the fusion protein was inserted downstream of the T7 promoter of the expression plasmid pET-3a, and the fusion proteins were produced as inclusion bodies in the Escherichia coli cytoplasm at levels up to 25% of the total cell protein. The protein was sulphonated, cleaved by CNBr and the M2PI mini-proinsulin was purified using ion-exchange chromatography. The refolding yield of M2PI was 20-40% better than that of proinsulin studied at the same molar concentrations, indicating that the short turn-forming sequence is more effective in the refolding process than the much longer C-peptide. Native human insulin was successfully generated by subsequent enzymic conversion of mini-proinsulin. The mini-proinsulin exhibited high receptor-binding activity, about 50% as potent as insulin, suggesting that this single-chained mini-proinsulin may provide a foundation in understanding the receptor-bound structure of insulin as well as the role of C-peptide in the folding and activity of proinsulin.

  20. Central Administration of Galanin Receptor 1 Agonist Boosted Insulin Sensitivity in Adipose Cells of Diabetic Rats

    Directory of Open Access Journals (Sweden)

    Zhenwen Zhang

    2016-01-01

    Full Text Available Our previous studies testified the beneficial effect of central galanin on insulin sensitivity of type 2 diabetic rats. The aim of the study was further to investigate whether central M617, a galanin receptor 1 agonist, can benefit insulin sensitivity. The effects of intracerebroventricular administration of M617 on insulin sensitivity and insulin signaling were evaluated in adipose tissues of type 2 diabetic rats. The results showed that central injection of M617 significantly increased plasma adiponectin contents, glucose infusion rates in hyperinsulinemic-euglycemic clamp tests, GLUT4 mRNA expression levels, GLUT4 contents in plasma membranes, and total cell membranes of the adipose cells but reduced the plasma C-reactive protein concentration in nondiabetic and diabetic rats. The ratios of GLUT4 contents were higher in plasma membranes to total cell membranes in both nondiabetic and diabetic M617 groups than each control. In addition, the central administration of M617 enhanced the ratios of pAkt/Akt and pAS160/AS160, but not phosphorylative cAMP response element-binding protein (pCREB/CREB in the adipose cells of nondiabetic and diabetic rats. These results suggest that excitation of central galanin receptor 1 facilitates insulin sensitivity via activation of the Akt/AS160 signaling pathway in the fat cells of type 2 diabetic rats.

  1. Single-Nucleotide Polymorphism on Exon 17 of Insulin Receptor Gene Influences Insulin Resistance in PCOS: A Pilot Study on North Indian Women.

    Science.gov (United States)

    Gangopadhyay, Sukanya; Agrawal, Nitin; Batra, Aruna; Kabi, Bhaskar Charan; Gupta, Akash

    2016-04-01

    Polycystic ovarian syndrome (PCOS), a major cause of infertility, is also strongly associated with insulin resistance. Defects in insulin receptor signaling are considered as one of the major molecular pathogeneses for insulin resistance. To investigate the possible mechanism of this signaling defect at genetic level, single-nucleotide polymorphism (SNP) [His 1085 C/T] at the exon 17 of insulin receptor gene (INSR) was studied in this pilot study. Polymerase chain reaction was performed on leucocytic DNA of women diagnosed with PCOS, selected from the outpatient department of Safdarjung Hospital, New Delhi, using suitable primer to amplify a region on INSR. An equal number of age-matched healthy women were selected as controls. SNP analysis was performed with restriction enzyme length polymorphism technique using Pm II enzyme. Serum insulin level was measured by ELISA kit and HOMA-IR was calculated mathematically. A higher frequency of the CC genotype was observed in PCOS women than in controls. Also, HOMA-IR, a tool for estimating insulin resistance, was significantly high in PCOS women with the CC genotype. C1008T SNP at exon 17 of INSR is associated with insulin resistance in Indian women with PCOS. Presence of CC genotype (C1085T) could be developed as a marker for insulin resistance and metabolic complications in PCOS women.

  2. Non-small cell lung cancer cell survival crucially depends on functional insulin receptors.

    Science.gov (United States)

    Frisch, Carolin Maria; Zimmermann, Katrin; Zilleßen, Pia; Pfeifer, Alexander; Racké, Kurt; Mayer, Peter

    2015-08-01

    Insulin plays an important role as a growth factor and its contribution to tumor proliferation is intensely discussed. It acts via the cognate insulin receptor (IR) but can also activate the IGF1 receptor (IGF1R). Apart from increasing proliferation, insulin might have additional effects in lung cancer. Therefore, we investigated insulin action and effects of IR knockdown (KD) in three (NCI-H292, NCI-H226 and NCI-H460) independent non-small cell lung cancer (NSCLC) cell lines. All lung cancer lines studied were found to express IR, albeit with marked differences in the ratio of the two variants IR-A and IR-B. Insulin activated the classical signaling pathway with IR autophosphorylation and Akt phosphorylation. Moreover, activation of MAPK was observed in H292 cells, accompanied by enhanced proliferation. Lentiviral shRNA IR KD caused strong decrease in survival of all three lines, indicating that the effects of insulin in lung cancer go beyond enhancing proliferation. Unspecific effects were ruled out by employing further shRNAs and different insulin-responsive cells (human pre-adipocytes) for comparison. Caspase assays demonstrated that IR KD strongly induced apoptosis in these lung cancer cells, providing the physiological basis of the rapid cell loss. In search for the underlying mechanism, we analyzed alterations in the gene expression profile in response to IR KD. A strong induction of certain cytokines (e.g. IL20 and tumour necrosis factor) became obvious and it turned out that these cytokines trigger apoptosis in the NSCLC cells tested. This indicates a novel role of IR in tumor cell survival via suppression of pro-apoptotic cytokines.

  3. Identification and evolution of two insulin receptor genes involved in Tribolium castaneum development and reproduction.

    Science.gov (United States)

    Sang, Ming; Li, Chengjun; Wu, Wei; Li, Bin

    2016-07-10

    The insulin and insulin-like signaling (IIS) pathway exists in a wide range of organisms from mammals to invertebrates and regulates several vital physiological functions. A phylogenetic analysis have indicated that insulin receptors have been duplicated at least twice among vertebrates, whereas only one duplication occurred in insects before the differentiation of Coleoptera, Hymenoptera, and Hemiptera. Thus, we cloned two putative insulin receptor genes, T.cas-ir1 and T.cas-ir2, from T. castaneum and determined that T.cas-ir1 is most strongly expressed during the late adult and early pupal stages, whereas T.cas-ir2 is most strongly expressed during the late larval stage. We found that larval RNAi against T.cas-ir1 and T.cas-ir2 causes 100% and 42.0% insect death, respectively, and that parental RNAi against T.cas-ir1 and T.cas-ir2 leads to 100% and 33.3% reductions in beetle fecundity, respectively. The hatching rate of ds-ir2 insects was 66.2%. Moreover, RNAi against these two genes increased the expression of the pkc, foxo, jnk, cdc42, ikk, and mekk genes but decreased erk gene expression. Despite these similarities, these two genes act via distinct regulatory pathways. These results indicate that these two receptors have functionally diverged with respect to the development and reproduction of T. castaneum, even though they retain some common regulatory signaling pathways.

  4. [The role of peroxisome proliferator-activated receptors γ (PPARγ) in obesity and insulin resistance].

    Science.gov (United States)

    Chmielewska-Kassassir, Małgorzata; Woźniak, Lucyna A; Ogrodniczek, Paweł; Wójcik, Marzena

    2013-12-11

    Obesity, defined as abnormal or excessive fat accumulation, is currently believed to be a major public health problem worldwide. Over the past 20 years, the prevalence of obesity has increased rapidly in both industrialized and developing countries, resulting in a considerably increased risk of type 2 diabetes mellitus (T2DM) and metabolic syndrome. Although the exact pathophysiological mechanisms underlying these diseases remain unclear, clinical and epidemiological studies support the existence of a relationship between obesity-induced inflammation and insulin resistance linked with the development and progression of metabolic diseases. Adipokines, produced and released by adipose tissue, are considered as factors linking obesity-induced inflammation with insulin resistance, and their regulation through peroxisome proliferator-activated receptors γ (PPARγ also known as NR1C3) is essential in these processes. PPARγ are transcriptional factors belonging to the ligand-activated nuclear receptor superfamily which directly regulate the expression of a large number of genes involved in adipocyte differentiation, lipid and carbohydrate metabolism as well as adipokine synthesis; thereby they are implicated in various metabolic disorders, including obesity, insulin resistance, dyslipidemia, and hypertension. This review summarizes the current literature on a functional relationship of PPARγ with obesity and insulin resistance and, moreover, highlights the significance of synthetic ligands of these receptors in the mentioned metabolic disorders.

  5. A novel insulin receptor-binding protein from Momordica charantia enhances glucose uptake and glucose clearance in vitro and in vivo through triggering insulin receptor signaling pathway.

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    Lo, Hsin-Yi; Ho, Tin-Yun; Li, Chia-Cheng; Chen, Jaw-Chyun; Liu, Jau-Jin; Hsiang, Chien-Yun

    2014-09-10

    Diabetes, a common metabolic disorder, is characterized by hyperglycemia. Insulin is the principal mediator of glucose homeostasis. In a previous study, we identified a trypsin inhibitor, named Momordica charantia insulin receptor (IR)-binding protein (mcIRBP) in this study, that might interact with IR. The physical and functional interactions between mcIRBP and IR were clearly analyzed in the present study. Photo-cross-linking coupled with mass spectrometry showed that three regions (17-21, 34-40, and 59-66 residues) located on mcIRBP physically interacted with leucine-rich repeat domain and cysteine-rich region of IR. IR-binding assay showed that the binding behavior of mcIRBP and insulin displayed a cooperative manner. After binding to IR, mcIRBP activated the kinase activity of IR by (5.87 ± 0.45)-fold, increased the amount of phospho-IR protein by (1.31 ± 0.03)-fold, affected phosphoinositide-3-kinase/Akt pathways, and consequently stimulated the uptake of glucose in 3T3-L1 cells by (1.36 ± 0.12)-fold. Intraperitoneal injection of 2.5 nmol/kg mcIRBP significantly decreased the blood glucose levels by 20.9 ± 3.2% and 10.8 ± 3.6% in normal and diabetic mice, respectively. Microarray analysis showed that mcIRBP affected genes involved in insulin signaling transduction pathway in mice. In conclusion, our findings suggest that mcIRBP is a novel IRBP that binds to sites different from the insulin-binding sites on IR and stimulates both the glucose uptake in cells and the glucose clearance in mice.

  6. Insulin receptor-overexpressing β-cells ameliorate hyperglycemia in diabetic rats through Wnt signaling activation.

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    Mi-Hyun Kim

    Full Text Available To investigate the therapeutic efficacy and mechanism of β-cells with insulin receptor (IR overexpression on diabetes mellitus (DM, rat insulinoma (INS-1 cells were engineered to stably express human insulin receptor (INS-IR cells, and subsequently transplanted into streptozotocin- induced diabetic rats. Compared with INS-1 cells, INS-IR cells showed improved β-cell function, including the increase in glucose utilization, calcium mobilization, and insulin secretion, and exhibited a higher rate of cell proliferation, and maintained lower levels of blood glucose in diabetic rats. These results were attributed to the increase of β-catenin/PPARγ complex bindings to peroxisome proliferator response elements in rat glucokinase (GK promoter and the prolongation of S-phase of cell cycle by cyclin D1. These events resulted from more rapid and higher phosphorylation levels of insulin-signaling intermediates, including insulin receptor substrate (IRS-1/IRS-2/phosphotylinositol 3 kinase/v-akt murine thymoma viral oncogene homolog (AKT 1, and the consequent enhancement of β-catenin nuclear translocation and Wnt responsive genes including GK and cyclin D1. Indeed, the higher functionality and proliferation shown in INS-IR cells were offset by β-catenin, cyclin D1, GK, AKT1, and IRS-2 gene depletion. In addition, the promotion of cell proliferation and insulin secretion by Wnt signaling activation was shown by 100 nM insulin treatment, and to a similar degree, was shown in INS-IR cells. In this regard, this study suggests that transferring INS-IR cells into diabetic animals is an effective and feasible DM treatment. Accordingly, the method might be a promising alternative strategy for treatment of DM given the adverse effects of insulin among patients, including the increased risk of modest weight gain and hypoglycemia. Additionally, this study demonstrates that the novel mechanism of cross-talk between insulin and Wnt signaling plays a primary role in

  7. Obesity-induced miR-15b is linked causally to the development of insulin resistance through the repression of the insulin receptor in hepatocytes.

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    Yang, Won-Mo; Jeong, Hyo-Jin; Park, Se-Whan; Lee, Wan

    2015-11-01

    Obesity increases intracellular lipid accumulation in key tissues or organs, which often leads to metabolic dysfunction and insulin resistance. Diets rich in saturated fatty acid (SFA) exacerbate obesity and hepatic steatosis, which accentuate the risk of insulin resistance and type 2 diabetes (T2DM). Although microRNAs (miRNAs) play a critical role in the regulation of gene expression, the implication of obesity-induced miRNAs in metabolic disorders particularly in the development of insulin resistance is largely unknown. Here, we investigated the implication of miR-15b, which is induced by SFA palmitate or obesity, in hepatic insulin resistance. Diet-induced obesity (DIO) in mice developed hyperglycemia and insulin resistance, accompanying with a reduction of insulin receptor (INSR) expression. Palmitate impaired insulin signaling as well as a decrease of INSR in hepatocytes. The expression of miR-15b was upregulated by DIO or palmitate in hepatocytes. Furthermore, the overexpression of miR-15b suppressed the protein expression of INSR through targeting INSR 3' untranslated region directly, resulting in an impairment of the insulin signaling and glycogen synthesis in hepatocytes. These results unveil a novel mechanism whereby miR-15b is linked causally to the pathogenesis of hepatic insulin resistance in SFA-induced obesity. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Striatal dopamine receptors modulate the expression of insulin receptor, IGF-1 and GLUT-3 in diabetic rats: effect of pyridoxine treatment.

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    Anitha, M; Abraham, Pretty Mary; Paulose, C S

    2012-12-05

    The incidence of type 2 diabetes mellitus is rising at alarming proportions. Central nervous system plays an important part in orchestrating glucose metabolism, with accumulating evidence linking dysregulated central nervous system circuits to the failure of normal glucoregulatory mechanisms. Pyridoxine is a water soluble vitamin and it has important role in brain function. This study aims to evaluate the role of pyridoxine in striatal glucose regulation through dopaminergic receptor expressions in streptozotocin induced diabetic rats. Radio receptor binding assays for dopamine D(1), D(2) receptors were done using [(3)H] 7-chloro-3-methyl-1-phenyl-1,2,4,5-tetrahydro-3-benzazepin-8-ol and [(3)H] 5-chloro-2-methoxy-4-methylamino-N-[-2-methyl-1-(phenylmethyl)pyrrolidin-3-yl]benzamide. Gene expressions were done using fluorescently labeled Taqman probes of dopamine D(1), D(2) receptor, Insulin receptor, Insulin like growth factor-1(IGF-1) and Glucose transporter-3 (GLUT-3). Bmax of dopamine D(1) receptor is decreased and B(max) of dopamine D(2) was increased in diabetic rats compared to control. Gene expression of dopamine D(1) receptor was down regulated and dopamine D(2) receptor was up regulated in diabetic rats. Our results showed decreased gene expression of Insulin receptor, IGF-1 and increased gene expression of GLUT-3 in diabetic rats compared to control. Pyridoxine treatment restored diabetes induced alterations in dopamine D(1), D(2) receptors, Insulin receptor, IGF-1, GLUT-3 gene expressions in striatum compared to diabetic rats. Insulin treatment reversed dopamine D(1), D(2) receptor, GLUT-3 mRNA expression, D(2) receptor binding parameters in the striatum compared to diabetic group. Our results suggest the potential role of pyridoxine supplementation in ameliorating diabetes mediated dysfunctions in striatal dopaminergic receptor expressions and insulin signaling. Thus pyridoxine has therapeutic significance in diabetes management.

  9. Low-Density Lipoprotein Receptor-Related Protein-1 Protects Against Hepatic Insulin Resistance and Hepatic Steatosis

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    Yinyuan Ding

    2016-05-01

    Full Text Available Low-density lipoprotein receptor-related protein-1 (LRP1 is a multifunctional uptake receptor for chylomicron remnants in the liver. In vascular smooth muscle cells LRP1 controls reverse cholesterol transport through platelet-derived growth factor receptor β (PDGFR-β trafficking and tyrosine kinase activity. Here we show that LRP1 regulates hepatic energy homeostasis by integrating insulin signaling with lipid uptake and secretion. Somatic inactivation of LRP1 in the liver (hLRP1KO predisposes to diet-induced insulin resistance with dyslipidemia and non-alcoholic hepatic steatosis. On a high-fat diet, hLRP1KO mice develop a severe Metabolic Syndrome secondary to hepatic insulin resistance, reduced expression of insulin receptors on the hepatocyte surface and decreased glucose transporter 2 (GLUT2 translocation. While LRP1 is also required for efficient cell surface insulin receptor expression in the absence of exogenous lipids, this latent state of insulin resistance is unmasked by exposure to fatty acids. This further impairs insulin receptor trafficking and results in increased hepatic lipogenesis, impaired fatty acid oxidation and reduced very low density lipoprotein (VLDL triglyceride secretion.

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

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    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

  11. Differential interaction of Apolipoprotein-E isoforms with insulin receptors modulates brain insulin signaling in mutant human amyloid precursor protein transgenic mice.

    Science.gov (United States)

    Chan, Elizabeth S; Chen, Christopher; Cole, Gregory M; Wong, Boon-Seng

    2015-09-08

    It is unclear how human apolipoprotein E4 (ApoE4) increases the risk for Alzheimer's disease (AD). Although Aβ levels can lead to insulin signaling impairment, these experiments were done in the absence of human ApoE. To examine ApoE role, we crossed the human ApoE-targeted replacement mice with mutant human amyloid precursor protein (APP) mice. In 26 week old mice with lower Aβ levels, the expression and phosphorylation of insulin signaling proteins remained comparable among APP, ApoE3xAPP and ApoE4xAPP mouse brains. When the mice aged to 78 weeks, these proteins were markedly reduced in APP and ApoE4xAPP mouse brains. While Aβ can bind to insulin receptor, how ApoE isoforms modulate this interaction remains unknown. Here, we showed that ApoE3 had greater association with insulin receptor as compared to ApoE4, regardless of Aβ42 concentration. In contrast, ApoE4 bound more Aβ42 with increasing peptide levels. Using primary hippocampal neurons, we showed that ApoE3 and ApoE4 neurons are equally sensitive to physiological levels of insulin. However, in the presence of Aβ42, insulin failed to elicit a downstream response only in ApoE4 hippocampal neurons. Taken together, our data show that ApoE genotypes can modulate this Aβ-mediated insulin signaling impairment.

  12. Leptin receptor polymorphisms interact with polyunsaturated fatty acids to augment risk of insulin resistance and metabolic syndrome in adults

    Science.gov (United States)

    The leptin receptor (LEPR) is associated with insulin resistance, a key feature of metabolic syndrome (MetS). Gene-fatty acid interactions may affect MetS risk. The objective was to investigate the relationship among LEPR polymorphisms, insulin resistance, andMetSrisk and whether plasma fatty acids,...

  13. Mactosylceramide Prevents Glial Cell Overgrowth by Inhibiting Insulin and Fibroblast Growth Factor Receptor Signaling

    DEFF Research Database (Denmark)

    Gerdøe-Kristensen, Stine; Lund, Viktor K; Wandall, Hans H

    2017-01-01

    , in which the mannosyltransferase Egghead controls conversion of glucosylceramide (GlcCer) to mactosylceramide (MacCer). Lack of elongated GSL in egghead (egh) mutants causes overgrowth of subperineurial glia (SPG), largely due to aberrant activation of phosphatidylinositol 3-kinase (PI3K). However, to what...... extent this effect involves changes in upstream signaling events is unresolved. We show here that glial overgrowth in egh is strongly linked to increased activation of Insulin and Fibroblast Growth Factor receptors (FGFR). Glial hypertrophy is phenocopied when overexpressing gain-of-function mutants...... hyperactivation is caused by absence of MacCer and not by GlcCer accumulation. We conclude that an early product in GSL biosynthesis, MacCer, prevents inappropriate activation of Insulin and Fibroblast Growth Factor Receptors in Drosophila glia. This article is protected by copyright. All rights reserved....

  14. Plasma adiponectin concentration is associated with skeletal muscle insulin receptor tyrosine phosphorylation, and low plasma concentration precedes a decrease in whole-body insulin sensitivity in humans.

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    Stefan, Norbert; Vozarova, Barbora; Funahashi, Tohru; Matsuzawa, Yuji; Weyer, Christian; Lindsay, Robert S; Youngren, Jack F; Havel, Peter J; Pratley, Richard E; Bogardus, Clifton; Tataranni, P Antonio

    2002-06-01

    Adiponectin, the most abundant adipose-specific protein, has been found to be negatively associated with degree of adiposity and positively associated with insulin sensitivity in Pima Indians and other populations. Moreover, adiponectin administration to rodents has been shown to increase insulin-induced tyrosine phosphorylation of the insulin receptor (IR) and also increase whole-body insulin sensitivity. To further characterize the relationship between plasma adiponectin concentration and insulin sensitivity in humans, we examined 1) the cross-sectional association between plasma adiponectin concentration and skeletal muscle IR tyrosine phosphorylation and 2) the prospective effect of plasma adiponectin concentration at baseline on change in insulin sensitivity. Fasting plasma adiponectin concentration, body composition (hydrodensitometry or dual energy X-ray absorptiometry), insulin sensitivity (insulin-stimulated glucose disposal, hyperinsulinemic clamp), and glucose tolerance (75-g oral glucose tolerance test) were measured in 55 Pima Indians (47 men and 8 women, aged 31 +/- 8 years, body fat 29 +/- 8% [mean +/- SD]; 50 with normal glucose tolerance, 3 with impaired glucose tolerance, and 2 with diabetes). Group 1 (19 subjects) underwent skeletal muscle biopsies for the measurement of basal and insulin-stimulated tyrosine phosphorylation of the IR (stimulated by 100 nmol/l insulin). The fold increase after insulin stimulation was calculated as the ratio between maximal and basal phosphorylation. Group 2 (38 subjects) had follow-up measurements of insulin-stimulated glucose disposal. Cross-sectionally, plasma adiponectin concentration was positively associated with insulin-stimulated glucose disposal (r = 0.58, P < 0.0001) and negatively associated with percent body fat (r = -0.62, P < 0.0001) in the whole group. In group 1 plasma adiponectin was negatively associated with the basal (r = -0.65, P = 0.003) and positively associated with the fold increase in IR

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

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    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.

  16. Lipodystrophy and severe metabolic dysfunction in mice with adipose tissue-specific insulin receptor ablation.

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    Qiang, Guifen; Whang Kong, Hyerim; Xu, Shanshan; Pham, Hoai An; Parlee, Sebastian D; Burr, Aaron A; Gil, Victoria; Pang, Jingbo; Hughes, Amy; Gu, Xuejiang; Fantuzzi, Giamila; MacDougald, Ormond A; Liew, Chong Wee

    2016-07-01

    Insulin signaling plays pivotal roles in the development and metabolism of many tissues and cell types. A previous study demonstrated that ablation of insulin receptor (IR) with aP2-Cre markedly reduced adipose tissues mass and protected mice from obesity. However, multiple studies have demonstrated widespread non-adipocyte recombination of floxed alleles in aP2-Cre mice. These findings underscore the need to re-evaluate the role of IR in adipocyte and systemic metabolism with a more adipose tissue-specific Cre mouse line. We generated and phenotyped a new adipose tissue-specific IR mouse model using the adipose tissue-specific Adipoq-Cre line. Here we show that the Adipoq-Cre-mediated IR KO in mice leads to lipodystrophy and metabolic dysfunction, which is in stark contrast to the previous study. In contrast to white adipocytes, absence of insulin signaling does not affect development of marrow and brown adipocytes, but instead is required for lipid accumulation particularly for the marrow adipocytes. Lipodystrophic IR KO mice have profound insulin resistance, hyperglycemia, organomegaly, and impaired adipokine secretion. Our results demonstrate differential roles for insulin signaling for white, brown, and marrow adipocyte development and metabolic regulation.

  17. Novel Zn2+ Modulated GPR39 Receptor Agonists Do Not Drive Acute Insulin Secretion in Rodents.

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    Ola Fjellström

    Full Text Available Type 2 diabetes (T2D occurs when there is insufficient insulin release to control blood glucose, due to insulin resistance and impaired β-cell function. The GPR39 receptor is expressed in metabolic tissues including pancreatic β-cells and has been proposed as a T2D target. Specifically, GPR39 agonists might improve β-cell function leading to more adequate and sustained insulin release and glucose control. The present study aimed to test the hypothesis that GPR39 agonism would improve glucose stimulated insulin secretion in vivo. A high throughput screen, followed by a medicinal chemistry program, identified three novel potent Zn2+ modulated GPR39 agonists. These agonists were evaluated in acute rodent glucose tolerance tests. The results showed a lack of glucose lowering and insulinotropic effects not only in lean mice, but also in diet-induced obese (DIO mice and Zucker fatty rats. It is concluded that Zn2+ modulated GPR39 agonists do not acutely stimulate insulin release in rodents.

  18. Defective insulin secretion by chronic glucagon receptor activation in glucose intolerant mice.

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    Ahlkvist, Linda; Omar, Bilal; Valeur, Anders; Fosgerau, Keld; Ahrén, Bo

    2016-03-01

    Stimulation of insulin secretion by short-term glucagon receptor (GCGR) activation is well characterized; however, the effect of long-term GCGR activation on β-cell function is not known, but of interest, since hyperglucagonemia occurs early during development of type 2 diabetes. Therefore, we examined whether chronic GCGR activation affects insulin secretion in glucose intolerant mice. To induce chronic GCGR activation, high-fat diet fed mice were continuously (2 weeks) infused with the stable glucagon analog ZP-GA-1 and challenged with oral glucose and intravenous glucose±glucagon-like peptide 1 (GLP1). Islets were isolated to evaluate the insulin secretory response to glucose±GLP1 and their pancreas were collected for immunohistochemical analysis. Two weeks of ZP-GA-1 infusion reduced insulin secretion both after oral and intravenous glucose challenges in vivo and in isolated islets. These inhibitory effects were corrected for by GLP1. Also, we observed increased β-cell area and islet size. We conclude that induction of chronic ZP-GA-1 levels in glucose intolerant mice markedly reduces insulin secretion, and thus, we suggest that chronic activation of the GCGR may contribute to the failure of β-cell function during development of type 2 diabetes.

  19. Targeting non-small cell lung cancer cells by dual inhibition of the insulin receptor and the insulin-like growth factor-1 receptor.

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    Emma E Vincent

    Full Text Available Phase III trials of the anti-insulin-like growth factor-1 receptor (IGF1R antibody figitumumab in non-small cell lung cancer (NSCLC patients have been discontinued owing to lack of survival benefit. We investigated whether inhibition of the highly homologous insulin receptor (IR in addition to the IGF1R would be more effective than inhibition of the IGF1R alone at preventing the proliferation of NSCLC cells. Signalling through IGF1R and IR in the NSCLC cell lines A549 and Hcc193 was stimulated by a combination of IGF1, IGF2 and insulin. It was inhibited by antibodies that block ligand binding, αIR3 (IGF1R and IR47-9 (IR, and by the ATP-competitive small molecule tyrosine kinase inhibitors AZ12253801 and NVPAWD742 which inhibit both IGF1R and IR tyrosine kinases. The effect of inhibitors was determined by an anchorage-independent proliferation assay and by analysis of Akt phosphorylation. In Hcc193 cells the reduction in cell proliferation and Akt phosphorylation due to anti-IGF1R antibody was enhanced by antibody-mediated inhibition of the IR whereas in A549 cells, with a relatively low IR:IGF1R expression ratio, it was not. In each cell line proliferation and Akt phosphorylation were more effectively inhibited by AZ12253801 and NVPAWD742 than by combined αIR3 and IR47-9. When the IGF1R alone is inhibited, unencumbered signalling through the IR can contribute to continued NSCLC cell proliferation. We conclude that small molecule inhibitors targeting both the IR and IGF1R more effectively reduce NSCLC cell proliferation in a manner independent of the IR:IGF1R expression ratio, providing a therapeutic rationale for the treatment of this disease.

  20. Effect of Yoga and Traditional Physical Exercise on Hormones and Percentage Insulin Binding Receptor in Patients with Type 2 Diabetes

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    Lorenzo Gordon

    2008-01-01

    Full Text Available The objective of the study was to investigate the short-term impact of a brief lifestyle intervention of yoga and traditional Physical Training (PT exercise regimens on: serum insulin, percentage insulin binding receptor, internalization of insulin-receptor complex, T3, T4, TSH and cortisol at baseline, 3 months and 6 months in patients with type 2 diabetes mellitus. A total of 231 patients completed this prospective randomized study with 77 type 2 diabetic patients in the yoga group (62 females and 15 males that were matched with the same number of patients in the traditional Physical Training (PT exercise and control groups. Biochemical parameters such as fasting Blood Glucose (FBG, serum insulin, percentage insulin binding receptor and internalization of insulin-receptor complex were determined at the beginning (baseline and two consecutive three monthly intervals. The effect of the lifestyle interventions on hormones such as cortisol, TSH, T4 and T3 were also investigated. The FBG concentration in the yoga and the traditional PT exercise groups were markedly decreased compared with control (P 0.05. The findings indicates the beneficial effects of yoga and traditional PT exercise regimens in improving glycaemic control by increasing percentage insulin binding receptor in type 2 diabetic patients with no significant change in cortisol and thyroid hormones.

  1. Sweet-taste receptors, low-energy sweeteners, glucose absorption and insulin release.

    Science.gov (United States)

    Renwick, Andrew G; Molinary, Samuel V

    2010-11-01

    The present review explores the interactions between sweeteners and enteroendocrine cells, and consequences for glucose absorption and insulin release. A combination of in vitro, in situ, molecular biology and clinical studies has formed the basis of our knowledge about the taste receptor proteins in the glucose-sensing enteroendocrine cells and the secretion of incretins by these cells. Low-energy (intense) sweeteners have been used as tools to define the role of intestinal sweet-taste receptors in glucose absorption. Recent studies using animal and human cell lines and knockout mice have shown that low-energy sweeteners can stimulate intestinal enteroendocrine cells to release glucagon-like peptide-1 and glucose-dependent insulinotropic peptide. These studies have given rise to major speculations that the ingestion of food and beverages containing low-energy sweeteners may act via these intestinal mechanisms to increase obesity and the metabolic syndrome due to a loss of equilibrium between taste receptor activation, nutrient assimilation and appetite. However, data from numerous publications on the effects of low-energy sweeteners on appetite, insulin and glucose levels, food intake and body weight have shown that there is no consistent evidence that low-energy sweeteners increase appetite or subsequent food intake, cause insulin release or affect blood pressure in normal subjects. Thus, the data from extensive in vivo studies in human subjects show that low-energy sweeteners do not have any of the adverse effects predicted by in vitro, in situ or knockout studies in animals.

  2. Insulin Resistance and Insulin Receptor Isoform A in Cancer%胰岛素抵抗和胰岛素受体亚型A与肿瘤

    Institute of Scientific and Technical Information of China (English)

    仲英洁

    2012-01-01

    Epidemiologic studies have demonstrated that type 2 diabetes mellitus increases the incidence of cancer. In addition, several epidemiological studies have shown that insulin resistance status, characterized by hyperinsulinaemia, is associated with an increased risk for a number of malignancies, including carcinomas of the breast,pancreas and colonrectal. Indeed,the hormone insulin and its tyrosine kinase receptor have been documented both in vitro and in vivo to play a key role in cancer biology. Insulin receptor is over-expressed in several human malignancies and insulin receptor isoform A is especially over-expressed in cancer. Over-expression of insulin receptor isoform A and its high affinity for both insulin and insulin-like growth factor- Ⅱ is a major mechanism in cancer initiation and/or promotion.%流行病学调查显示,2型糖尿病患者的肿瘤发生率增加.研究发现,以高胰岛素血症为特征的胰岛素抵抗与数种肿瘤的发生风险增加有关,包括乳腺癌、胰腺癌及结直肠癌.体内外研究均显示,胰岛素及其受体在肿瘤的发生、发展中起到重要作用.胰岛素受体,尤其是胰岛素受体亚型A,在人类数种肿瘤中均有高表达,其和胰岛素及胰岛素样生长因子Ⅱ结合后,引起肿瘤的发生和(或)发展.

  3. Safety and efficacy of a glucagon-like peptide-1 receptor agonist added to basal insulin therapy versus basal insulin with or without a rapid-acting insulin in patients with type 2 diabetes: results of a meta-analysis.

    Science.gov (United States)

    Wysham, Carol H; Lin, Jay; Kuritzky, Louis

    2017-05-01

    To consolidate the evidence from randomized controlled trials evaluating the use of glucagon-like peptide-1 receptor agonists (GLP-1 RAs) as add-on to basal insulin therapy in type 2 diabetes (T2D) patients. We searched the EMBASE® and NCBI PubMed (Medline) databases and relevant congress abstracts for randomized controlled trials evaluating the efficacy and safety of GLP-1 RAs as add-on to basal insulin compared with basal insulin with or without rapid-acting insulin (RAI) through 23 May 2016. The pooled data were analyzed using a random-effects meta-analysis model. A subanalysis was performed for trials investigating basal insulin plus GLP-1 RAs versus basal insulin plus RAI. Of the 2617 retrieved records, 19 randomized controlled trials enrolling 7,053 patients with T2D were included. Compared with basal insulin ± RAI, reduction in glycated hemoglobin (HbA1c) from baseline (difference in means: -0.48% [95% confidence interval (CI), -0.67 to -0.30]; p insulin plus GLP-1 RA. The subanalysis similarly showed significant results for change in HbA1c from baseline and for weight loss, as well as a significantly lower risk of symptomatic hypoglycemia in patients treated with basal insulin plus GLP-1 RA versus basal insulin plus RAI (odds ratio, 0.52 [95% CI, 0.42 to 0.64]; p insulin provided improved glycemic control, led to weight reduction and similar hypoglycemia rates versus an intensified insulin strategy; however, symptomatic hypoglycemia rates were significantly lower when compared with a basal insulin plus RAI.

  4. Insulin receptor binding and tyrosine kinase activity in skeletal muscle from normal pregnant women and women with gestational diabetes

    DEFF Research Database (Denmark)

    Damm, P; Handberg, A; Kühl, C

    1993-01-01

    OBJECTIVE: To ascertain whether the decreased glucose tolerance and insulin resistance found in normal and gestational diabetic pregnancy might be associated with changes in insulin receptor function. METHODS: Eight nonpregnant healthy women (nonpregnant controls), eight healthy pregnant women...... (pregnant controls), and eight women with gestational diabetes were investigated. All were non-obese. Muscle biopsies were obtained from the vastus lateralis muscle, and insulin binding and tyrosine kinase activities in partially purified skeletal muscle insulin receptors were studied. The pregnant controls...... with gestational diabetes compared to nonpregnant controls (P pregnant women did not differ from the other two groups. Postpartum, no differences in insulin binding were found between the groups. Basal and maximal tyrosine kinase activities toward the exogenous substrate poly(Glu4Tyr1) were...

  5. Cannabinoid 2 Receptor Agonist Improves Systemic Sensitivity to Insulin in High-Fat Diet/Streptozotocin-Induced Diabetic Mice

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    Xiuyuan Zhang

    2016-12-01

    Full Text Available Background/Aims: The endocannabinoid signalling (ECS system has been known to regulate glucose homeostasis. Previous studies have suggested that the cannabinoid 2 (CB2 receptor may play a regulatory role on insulin secretion, immune modulation and insulin resistance. Given that diabetes and insulin resistance are attributable to elevated inflammatory tone, we investigated the role of CB2 receptor on glucose tolerance and insulin sensitivity in high-fat diet (HFD/streptozotocin (STZ-induced mice. Methods: Diabetes was induced in male ICR mice by HFD/STZ and exposed to a CB2 receptor agonist, SER601, for 2- or 4-weeks via subcutaneous implantation of osmotic minipumps. Glucose and insulin tolerance tests were performed at the end of treatment. Islets were isolated for assessment of β-cell function. Pancreases and skeletal muscles were also obtained for histological analyses. Results: Despite a lack of impact on glucose tolerance, substantial improvement on insulin sensitivity was observed in SER601-treated mice, which could partly be attributed to improved islet β-cell function, shown as increased glucose-induced insulin secretion and insulin content. No changes on islet macrophage infiltration or skeletal muscle fat deposition were detectable from SER601-treated mice. However, a major decrease in body weight was recorded at the end of 4-week SER601 exposure, accompanied by a lack of epididymal adipose mass in SER601-treated mice. Conclusion: Our data suggest a lipolytic role of SER601 in HFD/STZ-induced diabetic mice, which results in significant improvement of systemic insulin sensitivity. Thus, the CB2 receptor may be considered a promising target for therapeutic development against insulin resistance and obesity-related diabetes.

  6. Dopamine D2-like receptors are expressed in pancreatic beta cells and mediate inhibition of insulin secretion.

    Science.gov (United States)

    Rubí, Blanca; Ljubicic, Sanda; Pournourmohammadi, Shirin; Carobbio, Stefania; Armanet, Mathieu; Bartley, Clarissa; Maechler, Pierre

    2005-11-04

    Dopamine signaling is mediated by five cloned receptors, grouped into D1-like (D1 and D5) and D2-like (D2, D3 and D4) families. We identified by reverse transcription-PCR the presence of dopamine receptors from both families in INS-1E insulin-secreting cells as well as in rodent and human isolated islets. D2 receptor expression was confirmed by immunodetection revealing localization on insulin secretory granules of INS-1E and primary rodent and human beta cells. We then tested potential effects mediated by the identified receptors on beta cell function. Dopamine (10 microM) and the D2-like receptor agonist quinpirole (5 microM) inhibited glucose-stimulated insulin secretion tested in several models, i.e. INS-1E beta cells, fluorescence-activated cell-sorted primary rat beta cells, and pancreatic islets of rat, mouse, and human origin. Insulin exocytosis is controlled by metabolism coupled to cytosolic calcium changes. Measurements of glucose-induced mitochondrial hyperpolarization and ATP generation showed that dopamine and D2-like agonists did not inhibit glucose metabolism. On the other hand, dopamine decreased cell membrane depolarization as well as cytosolic calcium increases evoked by glucose stimulation in INS-1E beta cells. These results show for the first time that dopamine receptors are expressed in pancreatic beta cells. Dopamine inhibited glucose-stimulated insulin secretion, an effect that could be ascribed to D2-like receptors. Regarding the molecular mechanisms implicated in dopamine-mediated inhibition of insulin release, our results point to distal steps in metabolism-secretion coupling. Thus, the role played by dopamine in glucose homeostasis might involve dopamine receptors, expressed in pancreatic beta cells, modulating insulin release.

  7. Type I insulin-like growth factor receptor signaling in skeletal muscle regeneration and hypertrophy.

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    Philippou, A; Halapas, A; Maridaki, M; Koutsilieris, M

    2007-01-01

    Skeletal muscle is able not only to increase its mass as an adaptation to mechanical loading generated by and imposed upon muscle but also to regenerate after damage, via its intrinsic regulation of gene transcription. Both cellular processes, muscle regeneration and hypertrophy, are mediated by the activation, proliferation and differentiation of muscle satellite cells and appear to be modulated by the mitotic and myogenic activity of locally produced insulin-like growth factor 1 (IGF-1), which functions in an autocrine/paracrine mode. Differentiation of satellite cells into myoblasts involves the regulation of skeletal muscle-specific proteins belonging to the family of myogenic regulatory factors (MRFs). The endocrine, autocrine and paracrine functions of IGF-1 are mediated through binding to the type I IGF receptor (IGF-1.R), which is a ligand-activated receptor tyrosine kinase. The binding of IGF-1 to IGF-1.R induces its autophosphorylation, which recruits specific cytoplasmic molecules containing the Insulin Receptor Substrate Proteins (IRS). The recruitment of IRS proteins by IGF-1/IGF-1.R binding is a critical level at which the proliferative and differentiative actions of IGF-1 diverge. Specific signaling pathways downstream of IGF-1, potentially involved in the mitogenic and myogenic responses and mediating skeletal muscle protein synthesis and hypertrophy following exercise-induced muscle overloading and damage, are discussed. A potential alternative activation of different signaling pathway(s) via a different receptor remains to be demonstrated.

  8. Treating Diabetes Mellitus: Pharmacophore Based Designing of Potential Drugs from Gymnema sylvestre against Insulin Receptor Protein.

    Science.gov (United States)

    Hossain, Mohammad Uzzal; Khan, Md Arif; Rakib-Uz-Zaman, S M; Ali, Mohammad Tuhin; Islam, Md Saidul; Keya, Chaman Ara; Salimullah, Md

    2016-01-01

    Diabetes mellitus (DM) is one of the most prevalent metabolic disorders which can affect the quality of life severely. Injectable insulin is currently being used to treat DM which is mainly associated with patient inconvenience. Small molecules that can act as insulin receptor (IR) agonist would be better alternatives to insulin injection. Herein, ten bioactive small compounds derived from Gymnema sylvestre (G. sylvestre) were chosen to determine their IR binding affinity and ADMET properties using a combined approach of molecular docking study and computational pharmacokinetic elucidation. Designing structural analogues were also performed for the compounds associated with toxicity and less IR affinity. Among the ten parent compounds, six were found to have significant pharmacokinetic properties with considerable binding affinity towards IR while four compounds were associated with toxicity and less IR affinity. Among the forty structural analogues, four compounds demonstrated considerably increased binding affinity towards IR and less toxicity compared with parent compounds. Finally, molecular interaction analysis revealed that six parent compounds and four analogues interact with the active site amino acids of IR. So this study would be a way to identify new therapeutics and alternatives to insulin for diabetic patients.

  9. Treating Diabetes Mellitus: Pharmacophore Based Designing of Potential Drugs from Gymnema sylvestre against Insulin Receptor Protein

    Directory of Open Access Journals (Sweden)

    Mohammad Uzzal Hossain

    2016-01-01

    Full Text Available Diabetes mellitus (DM is one of the most prevalent metabolic disorders which can affect the quality of life severely. Injectable insulin is currently being used to treat DM which is mainly associated with patient inconvenience. Small molecules that can act as insulin receptor (IR agonist would be better alternatives to insulin injection. Herein, ten bioactive small compounds derived from Gymnema sylvestre (G. sylvestre were chosen to determine their IR binding affinity and ADMET properties using a combined approach of molecular docking study and computational pharmacokinetic elucidation. Designing structural analogues were also performed for the compounds associated with toxicity and less IR affinity. Among the ten parent compounds, six were found to have significant pharmacokinetic properties with considerable binding affinity towards IR while four compounds were associated with toxicity and less IR affinity. Among the forty structural analogues, four compounds demonstrated considerably increased binding affinity towards IR and less toxicity compared with parent compounds. Finally, molecular interaction analysis revealed that six parent compounds and four analogues interact with the active site amino acids of IR. So this study would be a way to identify new therapeutics and alternatives to insulin for diabetic patients.

  10. Treating Diabetes Mellitus: Pharmacophore Based Designing of Potential Drugs from Gymnema sylvestre against Insulin Receptor Protein

    Science.gov (United States)

    Hossain, Mohammad Uzzal; Khan, Md. Arif; Rakib-Uz-Zaman, S. M.; Ali, Mohammad Tuhin; Islam, Md. Saidul; Keya, Chaman Ara; Salimullah, Md.

    2016-01-01

    Diabetes mellitus (DM) is one of the most prevalent metabolic disorders which can affect the quality of life severely. Injectable insulin is currently being used to treat DM which is mainly associated with patient inconvenience. Small molecules that can act as insulin receptor (IR) agonist would be better alternatives to insulin injection. Herein, ten bioactive small compounds derived from Gymnema sylvestre (G. sylvestre) were chosen to determine their IR binding affinity and ADMET properties using a combined approach of molecular docking study and computational pharmacokinetic elucidation. Designing structural analogues were also performed for the compounds associated with toxicity and less IR affinity. Among the ten parent compounds, six were found to have significant pharmacokinetic properties with considerable binding affinity towards IR while four compounds were associated with toxicity and less IR affinity. Among the forty structural analogues, four compounds demonstrated considerably increased binding affinity towards IR and less toxicity compared with parent compounds. Finally, molecular interaction analysis revealed that six parent compounds and four analogues interact with the active site amino acids of IR. So this study would be a way to identify new therapeutics and alternatives to insulin for diabetic patients. PMID:27034931

  11. P2Y₁ receptor-dependent diacylglycerol signaling microdomains in β cells promote insulin secretion.

    Science.gov (United States)

    Wuttke, Anne; Idevall-Hagren, Olof; Tengholm, Anders

    2013-04-01

    Diacylglycerol (DAG) controls numerous cell functions by regulating the localization of C1-domain-containing proteins, including protein kinase C (PKC), but little is known about the spatiotemporal dynamics of the lipid. Here, we explored plasma membrane DAG dynamics in pancreatic β cells and determined whether DAG signaling is involved in secretagogue-induced pulsatile release of insulin. Single MIN6 cells, primary mouse β cells, and human β cells within intact islets were transfected with translocation biosensors for DAG, PKC activity, or insulin secretion and imaged with total internal reflection fluorescence microscopy. Muscarinic receptor stimulation triggered stable, homogenous DAG elevations, whereas glucose induced short-lived (7.1 ± 0.4 s) but high-amplitude elevations (up to 109 ± 10% fluorescence increase) in spatially confined membrane regions. The spiking was mimicked by membrane depolarization and suppressed after inhibition of exocytosis or of purinergic P2Y₁, but not P2X receptors, reflecting involvement of autocrine purinoceptor activation after exocytotic release of ATP. Each DAG spike caused local PKC activation with resulting dissociation of its substrate protein MARCKS from the plasma membrane. Inhibition of spiking reduced glucose-induced pulsatile insulin secretion. Thus, stimulus-specific DAG signaling patterns appear in the plasma membrane, including distinct microdomains, which have implications for the kinetic control of exocytosis and other membrane-associated processes.

  12. Loss of Insulin Receptor in Osteoprogenitor Cells Impairs Structural Strength of Bone

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    Kathryn Thrailkill

    2014-01-01

    Full Text Available Type 1 diabetes mellitus (T1D is associated with decreased bone mineral density, a deficit in bone structure, and subsequently an increased risk of fragility fracture. These clinical observations, paralleled by animal models of T1D, suggest that the insulinopenia of T1D has a deleterious effect on bone. To further examine the action of insulin signaling on bone development, we generated mice with an osteoprogenitor-selective (osterix-Cre ablation of the insulin receptor (IR, designated OIRKO. OIRKO mice exhibited an 80% decrease in IR in osteoblasts. Prenatal elimination of IR did not affect fetal survival or gross morphology. However, loss of IR in mouse osteoblasts resulted in a postnatal growth-constricted phenotype. By 10–12 weeks of age, femurs of OIRKO mice were more slender, with a thinner diaphyseal cortex and, consequently, a decrease in whole bone strength when subjected to bending. In male mice alone, decreased metaphyseal trabecular bone, with thinner and more rodlike trabeculae, was also observed. OIRKO mice did not, however, exhibit abnormal glucose tolerance. The skeletal phenotype of the OIRKO mouse appeared more severe than that of previously reported bone-specific IR knockdown models, and confirms that insulin receptor expression in osteoblasts is critically important for proper bone development and maintenance of structural integrity.

  13. The novel functions of high-molecular-mass complexes containing insulin receptor substrates in mediation and modulation of insulin-like activities: Emerging concept of diverse function by IRS-associated proteins

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    Fumihiko eHakuno

    2015-05-01

    Full Text Available Insulin-like peptides, such as insulin and insulin-like growth factors (IGFs, induce a variety of bioactivities, such as growth, differentiation, survival, increased anabolism and decreased catabolism in many cell types and in vivo. In general, insulin or IGFs bind to insulin receptor (IR or IGF-I receptor (IGF-IR, activating the receptor tyrosine kinase. Insulin receptor substrates (IRSs are known to be major substrates of receptor kinases, mediating IGF/insulin signals to direct bioactivities. Recently, we discovered that IRSs form high-molecular-mass complexes (referred to here as IRSomes even without IGF/insulin stimulation. These complexes contain proteins (referred to here as IRSAP; IRS-associated protein, which modulate tyrosine phosphorylation of IRSs by receptor kinases, control IRS stability and determine intracellular localization of IRSs. In addition, in these complexes we found not only proteins that are involved in RNA metabolism but also RNAs themselves. Thus IRSAPs possibly contribute to modulation of IGF/insulin bioactivities. Since it is established that disorder of modulation of insulin-like activities causes various age-related diseases including cancer we could propose that the IRSome is an important target for treatment of these diseases.

  14. Adding prandial GLP-1 receptor agonists to basal insulin: a promising option for type 2 diabetes therapy.

    Science.gov (United States)

    Goldenberg, Ronald M; Berard, Lori

    2017-08-24

    Diabetes mellitus is a serious and increasingly prevalent condition in Canada and around the world. Treatment strategies have become increasingly complex, with a widening array of pharmacological agents available for glycemic management in type 2 diabetes mellitus (T2DM). New therapies that act in concert with available basal insulins may represent alternatives to basal insulin intensification with prandial or premixed insulin. Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) have recently shown promise as useful additions to basal insulin, with significant reductions in glycated hemoglobin and potentially beneficial effects on body weight. This review will focus on pivotal clinical trials to assess the potential benefits of adding prandial GLP-1 RAs to basal insulin in patients with T2DM. Clinical studies combining prandial GLP-1 RAs and basal insulin (published between 2011 and July 2017) were identified and reviewed in PubMed, the Cochrane Central Register of Clinical Trials (Issue 6, June 2017) and clinicaltrials.gov. Most of the studies presented in this review show that the addition of a prandial GLP-1 RA to basal insulin results in equal or slightly superior efficacy compared to the addition of prandial insulin, together with weight loss and less hypoglycemia. The results of the studies suggest that a prandial GLP-1 RA as an add-on to basal insulin may be a safe and effective treatment intensification option (vs basal-plus or basal-bolus insulin).

  15. Inflammatory Mediators and Insulin Resistance in Obesity: Role of Nuclear Receptor Signaling in Macrophages

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    Lucía Fuentes

    2010-01-01

    Full Text Available Visceral obesity is coupled to a general low-grade chronic inflammatory state characterized by macrophage activation and inflammatory cytokine production, leading to insulin resistance (IR. The balance between proinflammatory M1 and antiinflammatory M2 macrophage phenotypes within visceral adipose tissue appears to be crucially involved in the development of obesity-associated IR and consequent metabolic abnormalities. The ligand-dependent transcription factors peroxisome proliferator activated receptors (PPARs have recently been implicated in the determination of the M1/M2 phenotype. Liver X receptors (LXRs, which form another subgroup of the nuclear receptor superfamily, are also important regulators of proinflammatory cytokine production in macrophages. Disregulation of macrophage-mediated inflammation by PPARs and LXRs therefore underlies the development of IR. This review summarizes the role of PPAR and LXR signaling in macrophages and current knowledge about the impact of these actions in the manifestation of IR and obesity comorbidities such as liver steatosis and diabetic osteopenia.

  16. Ahsg-fetuin blocks the metabolic arm of insulin action through its interaction with the 95-kD β-subunit of the insulin receptor.

    Science.gov (United States)

    Goustin, Anton Scott; Derar, Nada; Abou-Samra, Abdul B

    2013-04-01

    We previously have shown that Ahsg, a liver glycoprotein, inhibits insulin receptor (InsR) tyrosine kinase (TK) activity and the ERK1/2 mitogenic signaling arm of insulin signaling. Here we show that Ahsg blocks insulin-stimulated GLUT4 translocation and Akt activation in intact cells (mouse myoblasts). Furthermore, Ahsg inhibits InsR autophosphorylation of highly-purified insulin holoreceptors in a cell-free, ATP-dependent system, with an IC50 within the range of single-chain Ahsg concentrations in human serum. Binding of (125)I-insulin to living cells overexpressing the InsR shows a dissociation constant (KD) of 250pM, unaltered in the presence of 300 nM Ahsg. A mutant InsR cDNA encoding the signal peptide, the β-subunit and the furin processing site, but deleting the α-subunit, was stably expressed in HEK293 cells. Treatment with peroxovanadate, but not insulin, dramatically increased the 95 kD β-subunit tyrosine phosphoryation. The level of tyrosine phosphorylation of the 95-kD β-subunit can be driven down sharply by treatment of living HEK293 transfectant cells with physiological doses of Ahsg. Treatment of myogenic cells with Ahsg blunts insulin-stimulated InsR autophosphorylation and AKT phosphorylation. Taken together, we show that Ahsg antagonizes the metabolic functions initiated by InsR activation without interference in insulin binding. The experiments suggest a direct interaction of Ahsg with the InsR ectodomain β-subunit in a mode that does not significantly alter the high-affinity binding of insulin to the holoreceptor's two complementing α-subunits.

  17. [Treatment strategy for elderly diabetic patient with insulin or GLP-1 receptor agonist].

    Science.gov (United States)

    Ando, Yasuyo

    2013-11-01

    It has been established that diabetes is an independent risk factor for microvascular and macrovascular complications, and many studies indicate that diabetic subjects are at greater risk of dementia, depression and fracture. Risk reductions for microvascular, macrovascular and death were observed by intensive therapy using insulin or oral diabetic agents. But a history of hypoglycemia was increased myocardial infarction, mortality, dementia and fracture. So it is important that optimum glycemic control has to be achieved without hypoglycemia. Treatment with a long-acting basal insulin analogue or glucagon-like peptide-1(GLP-1) receptor agonist, provide effective glycemic control without serious hypoglycemia in elderly patients. Self-monitoring of blood glucose might be effective in improving glycemic control in elderly patients, and it is useful for the diagnosis of hypoglycemia.

  18. Role of the Insulin-Like Growth Factor Type 1 Receptor in the Pathogenesis of Diabetic Encephalopathy

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    Duo Zhang

    2015-01-01

    Full Text Available Defective cognitive function is common in patients with diabetes, suggesting that insulin normally exerts anabolic actions in neuron, namely, diabetic encephalopathy. However, because insulin can cross-activate the insulin-like growth factor type 1 receptor (IGF-1R, which also functions in most of tissues, such as muscle and bone, it has been difficult to establish the direct (IGF-1-independent actions of insulin in the pathogenesis of diabetic encephalopathy. To overcome this problem, we examined insulin signaling and action in primary PC-12 cells engineered for conditional disruption of the IGF-1 receptor (ΔIGF-1R. The results showed that the lower glucose metabolism and high expression of IGF-1R occurred in the brain of the DE rat model. The results also showed the defect of IGF-1R could significantly improve the ability of glucose consumption and enhance sensitivity to insulin-induced IR and Akt phosphorylation in PC12 cells. And meanwhile, IGF-1R allele gene knockout (IGF-1Rneo mice treated with HFD/STZ had better cognitive abilities than those of wild mice. Those results indicate that insulin exerts direct anabolic actions in neuron-like cells by activation of its cognate receptor and prove that IGF-1R plays an important role in the pathogenesis of diabetic encephalopathy.

  19. Insulin receptor substrate-1 (IRS-1 associates with small nucleolar RNA which contributes to ribosome biogenesis

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    Atsufumi eOzoe

    2014-03-01

    Full Text Available Insulin receptor substrates (IRSs are well known to play crucial roles in mediating intracellular signals of insulin-like growth factors (IGFs/insulin. Previously we showed that IRS-1 forms high molecular mass complexes containing RNAs. To identify RNAs in IRS-1 complexes, we performed UV cross-linking and immunoprecipitation (CLIP analysis using HEK293 cells expressing FLAG-IRS-1 and FLAG-IRS-2. We detected the radioactive signals in the immunoprecipitates of FLAG-IRS-1 proportional to the UV irradiation, but not in the immunoprecipitates of FLAG-IRS-2, suggesting the direct contact of RNAs with IRS-1. RNAs cross-linked to IRS-1 were then amplified by RT-PCR, followed by sequence analysis. We isolated sequence tags attributed to 25 messenger RNAs and 8 non-coding RNAs, including small nucleolar RNAs (snoRNAs. We focused on the interaction of IRS-1 with U96A snoRNA (U96A and its host Rack1 (receptor for activated C kinase 1 pre-mRNA. We confirmed the interaction of IRS-1 with U96A, and with RACK1 pre-mRNA by immunoprecipitation with IRS-1 followed by Northern blotting or RT-PCR analyses. Mature U96A in IRS-1-/- mouse embryonic fibroblasts was quantitatively less than WT. We also found that a part of nuclear IRS-1 is localized in the Cajal body, a nuclear subcompartment where snoRNA mature. The unanticipated function of IRS-1 in snoRNA biogenesis highlights the potential of RNA-associated IRS-1 complex to open a new line of investigation to dissect the novel mechanisms regulating IGFs/insulin-mediated biological events.

  20. Differential Roles of Insulin and IGF-1 Receptors in Adipose Tissue Development and Function.

    Science.gov (United States)

    Boucher, Jeremie; Softic, Samir; El Ouaamari, Abdelfattah; Krumpoch, Megan T; Kleinridders, Andre; Kulkarni, Rohit N; O'Neill, Brian T; Kahn, C Ronald

    2016-08-01

    To determine the roles of insulin and insulin-like growth factor 1 (IGF-1) action in adipose tissue, we created mice lacking the insulin receptor (IR), IGF-1 receptor (IGF1R), or both using Cre-recombinase driven by the adiponectin promoter. Mice lacking IGF1R only (F-IGFRKO) had a ∼25% reduction in white adipose tissue (WAT) and brown adipose tissue (BAT), whereas mice lacking both IR and IGF1R (F-IR/IGFRKO) showed an almost complete absence of WAT and BAT. Interestingly, mice lacking only the IR (F-IRKO) had a 95% reduction in WAT, but a paradoxical 50% increase in BAT with accumulation of large unilocular lipid droplets. Both F-IRKO and F-IR/IGFRKO mice were unable to maintain body temperature in the cold and developed severe diabetes, ectopic lipid accumulation in liver and muscle, and pancreatic islet hyperplasia. Leptin treatment normalized blood glucose levels in both groups. Glucose levels also improved spontaneously by 1 year of age, despite sustained lipodystrophy and insulin resistance. Thus, loss of IR is sufficient to disrupt white fat formation, but not brown fat formation and/or maintenance, although it is required for normal BAT function and temperature homeostasis. IGF1R has only a modest contribution to both WAT and BAT formation and function. © 2016 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.

  1. Insulin/glucose induces natriuretic peptide clearance receptor in human adipocytes: a metabolic link with the cardiac natriuretic pathway.

    Science.gov (United States)

    Bordicchia, M; Ceresiani, M; Pavani, M; Minardi, D; Polito, M; Wabitsch, M; Cannone, V; Burnett, J C; Dessì-Fulgheri, P; Sarzani, R

    2016-07-01

    Cardiac natriuretic peptides (NP) are involved in cardiorenal regulation and in lipolysis. The NP activity is largely dependent on the ratio between the signaling receptor NPRA and the clearance receptor NPRC. Lipolysis increases when NPRC is reduced by starving or very-low-calorie diet. On the contrary, insulin is an antilipolytic hormone that increases sodium retention, suggesting a possible functional link with NP. We examined the insulin-mediated regulation of NP receptors in differentiated human adipocytes and tested the association of NP receptor expression in visceral adipose tissue (VAT) with metabolic profiles of patients undergoing renal surgery. Differentiated human adipocytes from VAT and Simpson-Golabi-Behmel Syndrome (SGBS) adipocyte cell line were treated with insulin in the presence of high-glucose or low-glucose media to study NP receptors and insulin/glucose-regulated pathways. Fasting blood samples and VAT samples were taken from patients on the day of renal surgery. We observed a potent insulin-mediated and glucose-dependent upregulation of NPRC, through the phosphatidylinositol 3-kinase pathway, associated with lower lipolysis in differentiated adipocytes. No effect was observed on NPRA. Low-glucose medium, used to simulate in vivo starving conditions, hampered the insulin effect on NPRC through modulation of insulin/glucose-regulated pathways, allowing atrial natriuretic peptide to induce lipolysis and thermogenic genes. An expression ratio in favor of NPRC in adipose tissue was associated with higher fasting insulinemia, HOMA-IR, and atherogenic lipid levels. Insulin/glucose-dependent NPRC induction in adipocytes might be a key factor linking hyperinsulinemia, metabolic syndrome, and higher blood pressure by reducing NP effects on adipocytes. Copyright © 2016 the American Physiological Society.

  2. Robert Feulgen Prize Lecture 1993. The journey of the insulin receptor into the cell: from cellular biology to pathophysiology.

    Science.gov (United States)

    Carpentier, J L

    1993-09-01

    The data that we have reviewed indicate that insulin binds to a specific cell-surface receptor. The complex then becomes involved in a series of steps which lead the insulin-receptor complex to be internalized and rapidly delivered to endosomes. From this sorting station, the hormone is targeted to lysosomes to be degraded while the receptor is recycled back to the cell surface. This sequence of events presents two degrees of ligand specificity: (a) The first step is ligand-dependent and requires insulin-induced receptor phosphorylation of specific tyrosine residues. It consists in the surface redistribution of the receptor from microvilli where it preferentially localizes in its unoccupied form. (b) The second step is more general and consists in the association with clathrin-coated pits which represents the internalization gate common to many receptors. This sequence of events participates in the regulation of the biological action of the hormone and can thus be implicated in the pathophysiology of diabetes mellitus and various extreme insulin resistance syndromes, including type A extreme insulin resistance, leprechaunism, and Rabson-Mendehall syndrome. Alterations of the internalization process can result either from intrinsic abnormalities of the receptor or from more general alteration of the plasma membrane or of the cell metabolism. Type I diabetes is an example of the latter possibility, since general impairment of endocytosis could contribute to extracellular matrix accumulation and to an increase in blood cholesterol. Thus, better characterization of the molecular and cellular biology of the insulin receptor and of its journey inside the cell definitely leads to better understanding of disease states, including diabetes.

  3. Angiotensin II receptor blocker ameliorates stress-induced adipose tissue inflammation and insulin resistance.

    Directory of Open Access Journals (Sweden)

    Motoharu Hayashi

    Full Text Available A strong causal link exists between psychological stress and insulin resistance as well with hypertension. Meanwhile, stress-related responses play critical roles in glucose metabolism in hypertensive patients. As clinical trials suggest that angiotensin-receptor blocker delays the onset of diabetes in hypertensive patients, we investigated the effects of irbesartan on stress-induced adipose tissue inflammation and insulin resistance. C57BL/6J mice were subjected to 2-week intermittent restraint stress and orally treated with vehicle, 3 and 10 mg/kg/day irbesartan. The plasma concentrations of lipid and proinflammatory cytokines [Monocyte Chemoattractant Protein-1 (MCP-1, tumor necrosis factor-α, and interleukin-6] were assessed with enzyme-linked immunosorbent assay. Monocyte/macrophage accumulation in inguinal white adipose tissue (WAT was observed with CD11b-positive cell counts and mRNA expressions of CD68 and F4/80 using immunohistochemistry and RT-PCR methods respectively. The mRNA levels of angiotensinogen, proinflammatory cytokines shown above, and adiponectin in WAT were also assessed with RT-PCR method. Glucose metabolism was assessed by glucose tolerance tests (GTTs and insulin tolerance tests, and mRNA expression of insulin receptor substrate-1 (IRS-1 and glucose transporter 4 (GLUT4 in WAT. Restraint stress increased monocyte accumulation, plasma free fatty acids, expression of angiotensinogen and proinflammatory cytokines including MCP-1, and reduced adiponectin. Irbesartan reduced stress-induced monocyte accumulation in WAT in a dose dependent manner. Irbesartan treatment also suppressed induction of adipose angiotensinogen and proinflammatory cytokines in WAT and blood, and reversed changes in adiponectin expression. Notably, irbesartan suppressed stress-induced reduction in adipose tissue weight and free fatty acid release, and improved insulin tolerance with restoration of IRS-1 and GLUT4 mRNA expressions in WAT. The results

  4. Introduction of exogenous growth hormone receptors augments growth hormone-responsive insulin biosynthesis in rat insulinoma cells

    Energy Technology Data Exchange (ETDEWEB)

    Billestrup, N.; Moeldrup, A.; Serup, P.; Nielsen, J.H. (Hagedorn Research Lab., Gentofte (Denmark)); Mathews, L.S.; Norstedt, G. (Karolinska Inst., Huddinge (Sweden))

    1990-09-01

    The stimulation of insulin biosynthesis in the pancreatic insulinoma cell line RIN5-AH by growth hormone (GH) is initiated by GH binding to specific receptors. To determine whether the recently cloned rat hepatic GH receptor is able to mediate the insulinotropic effect of GH, the authors have transfected a GH receptor cDNA under the transcriptional control of the human metallothionein promoter into RIN5-AH cells. The transfected cells were found to exhibit an increased expression of GH receptors and to contain a specific GH receptor mRNA that was not expressed in the parent cell line. The expression of GH receptors in one clone (1.24) selected for detailed analysis was increased 2.6-fold compared to untransfected cells. The increased GH receptor expression was accompanied by an increased responsiveness to GH. Thus, the maximal GH-stimulated increase of insulin biosynthesis was 4.1-fold in 1.24 cells compared to 1.9-fold in the nontransfected RIN5-AH cells. The expression of the transfected receptor was stimulated 1.6- and 2.3-fold when cells were cultured in the presence of 25 or 50 {mu}M Zn{sup 2+} was associated with an increased magnitude of GH-stimulated insulin biosynthesis. A close stoichiometric relationship between the level of receptor expression and the level of GH-stimulated insulin biosynthesis was observed. They conclude from these results that the hepatic GH receptor is able to mediate the effect of GH on insulin biosynthesis in RIN5-AH cells.

  5. Essential role of PSM/SH2-B variants in insulin receptor catalytic activation and the resulting cellular responses.

    Science.gov (United States)

    Zhang, Manchao; Deng, Youping; Tandon, Ruchi; Bai, Cheng; Riedel, Heimo

    2008-01-01

    The positive regulatory role of PSM/SH2-B downstream of various mitogenic receptor tyrosine kinases or gene disruption experiments in mice support a role of PSM in the regulation of insulin action. Here, four alternative PSM splice variants and individual functional domains were compared for their role in the regulation of specific metabolic insulin responses. We found that individual PSM variants in 3T3-L1 adipocytes potentiated insulin-mediated glucose and amino acid transport, glycogenesis, lipogenesis, and key components in the metabolic insulin response including p70 S6 kinase, glycogen synthase, glycogen synthase kinase 3 (GSK3), Akt, Cbl, and IRS-1. Highest activity was consistently observed for PSM alpha, followed by beta, delta, and gamma with decreasing activity. In contrast, dominant-negative peptide mimetics of the PSM Pro-rich, pleckstrin homology (PH), or src homology 2 (SH2) domains inhibited any tested insulin response. Potentiation of the insulin response originated at the insulin receptor (IR) kinase level by PSM variant-specific regulation of the Km (ATP) whereas the Vmax remained unaffected. IR catalytic activation was inhibited by peptide mimetics of the PSM SH2 or dimerization domain (DD). Either peptide should disrupt the complex of a PSM dimer linked to IR via SH2 domains as proposed for PSM activation of tyrosine kinase JAK2. Either peptide abolished downstream insulin responses indistinguishable from PSM siRNA knockdown. Our results implicate an essential role of the PSM variants in the activation of the IR kinase and the resulting metabolic insulin response. PSM variants act as internal IR ligands that in addition to potentiating the insulin response stimulate IR catalytic activation even in the absence of insulin.

  6. Insulin-like growth factor-I receptor in proliferation and motility of pancreatic cancer

    Institute of Scientific and Technical Information of China (English)

    Minoru; Tomizawa; Fuminobu; Shinozaki; Takao; Sugiyama; Shigenori; Yamamoto; Makoto; Sueishi; Takanobu; Yoshida

    2010-01-01

    AIM:To develop a molecular therapy for pancreatic cancer, the insulin-like growth factor-I (IGF-I) signaling pathway was analyzed.METHODS: Pancreatic cancer cell lines (MIA-Paca2, NOR-P1, PANC-1, PK-45H, PK-1, PK-59 and KP-4) were cultured in media with 10 mL/L fetal bovine serum. Western blotting analysis was performed to clarify the expression of IGF-I receptor (IGF-IR). Picropodophyllin (PPP), a specific inhibitor of IGF-IR, LY294002, a specific inhibitor of phosphatidylinositol3 kinase (PI3K), and PD980...

  7. Novel Small Molecule Glucagon-Like Peptide-1 Receptor Agonist Stimulates Insulin Secretion in Rodents and From Human Islets

    Science.gov (United States)

    Sloop, Kyle W.; Willard, Francis S.; Brenner, Martin B.; Ficorilli, James; Valasek, Kathleen; Showalter, Aaron D.; Farb, Thomas B.; Cao, Julia X.C.; Cox, Amy L.; Michael, M. Dodson; Gutierrez Sanfeliciano, Sonia Maria; Tebbe, Mark J.; Coghlan, Michael J.

    2010-01-01

    OBJECTIVE The clinical effectiveness of parenterally-administered glucagon-like peptide-1 (GLP-1) mimetics to improve glucose control in patients suffering from type 2 diabetes strongly supports discovery pursuits aimed at identifying and developing orally active, small molecule GLP-1 receptor agonists. The purpose of these studies was to identify and characterize novel nonpeptide agonists of the GLP-1 receptor. RESEARCH DESIGN AND METHODS Screening using cells expressing the GLP-1 receptor and insulin secretion assays with rodent and human islets were used to identify novel molecules. The intravenous glucose tolerance test (IVGTT) and hyperglycemic clamp characterized the insulinotropic effects of compounds in vivo. RESULTS Novel low molecular weight pyrimidine-based compounds that activate the GLP-1 receptor and stimulate glucose-dependent insulin secretion are described. These molecules induce GLP-1 receptor-mediated cAMP signaling in HEK293 cells expressing the GLP-1 receptor and increase insulin secretion from rodent islets in a dose-dependent manner. The compounds activate GLP-1 receptor signaling, both alone or in an additive fashion when combined with the endogenous GLP-1 peptide; however, these agonists do not compete with radiolabeled GLP-1 in receptor-binding assays. In vivo studies using the IVGTT and the hyperglycemic clamp in Sprague Dawley rats demonstrate increased insulin secretion in compound-treated animals. Further, perifusion assays with human islets isolated from a donor with type 2 diabetes show near-normalization of insulin secretion upon compound treatment. CONCLUSIONS These studies characterize the insulinotropic effects of an early-stage, small molecule GLP-1 receptor agonist and provide compelling evidence to support pharmaceutical optimization. PMID:20823098

  8. Insulin use, hormone receptor status and hematopoietic cytokines׳ circulation in women with diabetes mellitus and breast cancer

    Directory of Open Access Journals (Sweden)

    Zachary A.P. Wintrob

    2017-04-01

    The data presented here is among the first to show a relationship between pre-existing use of injectable insulin in women diagnosed with breast cancer and type 2 diabetes mellitus, hematopoietic cytokine profiles at time of breast cancer diagnosis, and subsequent cancer outcomes. A Pearson correlation analysis evaluating the relationship between G-CSF, GM-CSF, and IL-7 stratified by insulin use, controls, as well as by estrogen and progesterone receptor status is also provided.

  9. Neuronal Androgen Receptor Regulates Insulin Sensitivity via Suppression of Hypothalamic NF-κB–Mediated PTP1B Expression

    OpenAIRE

    Yu, I-Chen; Lin, Hung-Yun; Liu, Ning-Chun; Sparks, Janet D.; Yeh, Shuyuan; Fang, Lei-Ya; Chen, Lumin; Chang, Chawnshang

    2013-01-01

    Clinical investigations highlight the increased incidence of metabolic syndrome in prostate cancer (PCa) patients receiving androgen deprivation therapy (ADT). Studies using global androgen receptor (AR) knockout mice demonstrate that AR deficiency results in the development of insulin resistance in males. However, mechanisms by which AR in individual organs coordinately regulates insulin sensitivity remain unexplored. Here we tested the hypothesis that functional AR in the brain contributes ...

  10. Blockade of mineralocorticoid receptor reverses adipocyte dysfunction and insulin resistance in obese mice.

    Science.gov (United States)

    Hirata, Ayumu; Maeda, Norikazu; Hiuge, Aki; Hibuse, Toshiyuki; Fujita, Koichi; Okada, Takuya; Kihara, Shinji; Funahashi, Tohru; Shimomura, Iichiro

    2009-10-01

    In obesity, chronic low-grade inflammation and overproduction of reactive oxygen species (ROS) in fat contribute to the development of metabolic syndrome. Suppression of inflammation and ROS production in fat may attenuate the metabolic syndrome. Activation of mineralocorticoid receptor (MR) promotes inflammation in heart, kidney, and vasculature via ROS generation. However, the significance of MR in fat remains elusive. Here we investigated whether MR blockade attenuates obesity-related insulin resistance and improves adipocyte dysfunction. Obese ob/ob and db/db mice were treated with eplerenone, a MR antagonist, for 3 weeks. 3T3-L1 adipocytes were treated with aldosterone or H2O2, with and without eplerenone or MR-siRNA. High levels of MR mRNA were detected in adipose tissue of obese ob/ob and db/db mice. Eplerenone treatment significantly reduced insulin resistance, suppressed macrophage infiltration and ROS production in adipose tissues, and corrected the mRNA levels of obesity-related genes in obese mice. In 3T3-L1 adipocytes, aldosterone and H2O2 increased intracellular ROS levels and MR blockade inhibited such increases. H2O2 and aldosterone resulted in dysregulation of mRNAs of various genes related to ROS and cytokines, whereas MR blockade corrected such changes. MR blockade attenuates obesity-related insulin resistance partly through reduction of fat ROS production, inflammatory process, and induction of cytokines.

  11. Solution structure of the transmembrane domain of the insulin receptor in detergent micelles.

    Science.gov (United States)

    Li, Qingxin; Wong, Ying Lei; Kang, CongBao

    2014-05-01

    The insulin receptor (IR) binds insulin and plays important roles in glucose homeostasis by regulating the tyrosine kinase activity at its C-terminus. Its transmembrane domain (TMD) is shown to be important for transferring conformational changes induced by insulin across the cell membrane to regulate kinase activity. In this study, a construct IR(940-988) containing the TMD was expressed and purified for structural studies. Its solution structure in dodecylphosphocholine (DPC) micelles was determined. The sequence containing residues L962 to Y976 of the TMD of the IR in micelles adopts a well-defined helical structure with a kink formed by glycine and proline residues present at its N-terminus, which might be important for its function. Paramagnetic relaxation enhancement (PRE) and relaxation experimental results suggest that residues following the TMD are flexible and expose to aqueous solution. Although purified IR(940-988) in micelles existed mainly as a monomeric form verified by gel filtration and relaxation analysis, cross-linking study suggests that it may form a dimer or oligomers under micelle conditions.

  12. Angiotensin receptor blockers improve insulin signaling and prevent microvascular rarefaction in the skeletal muscle of spontaneously hypertensive rats.

    Science.gov (United States)

    Rizzoni, Damiano; Pasini, Evasio; Flati, Vincenzo; Rodella, Luigi F; Paiardi, Silvia; Assanelli, Deodato; De Ciuceis, Carolina; Porteri, Enzo; Boari, Gianluca Em; Rezzani, Rita; Speca, Silvia; Favero, Gaia; Martinotti, Stefano; Toniato, Elena; Platto, Caterina; Agabiti-Rosei, Enrico

    2008-08-01

    Spontaneously hypertensive rats are an example of an animal model of genetic hypertension with insulin resistance. The aim of this study was to investigate insulin signaling in the heart and in the skeletal muscle of spontaneously hypertensive rats, as well as to evaluate the effects of renin-angiotensin system blockade. We investigated eight untreated spontaneously hypertensive rats of 12 weeks of age and eight age-matched normotensive Wistar-Kyoto controls. In addition, eight spontaneously hypertensive rats were treated for 8 weeks with the angiotensin receptor blocker olmesartan, and eight spontaneously hypertensive rats with the angiotensin-converting enzyme inhibitor enalapril. The heart and a skeletal muscle (quadriceps femoris) were promptly dissected and frozen. Insulin signaling was evaluated by Western blot analysis of involved proteins; in addition, microvessel density was indirectly evaluated by immunohistochemistry. Blood pressure values were normalized by both olmesartan and enalapril. In the heart, no statistically significant difference in the expression of proteins involved in insulin signaling was observed between untreated spontaneously hypertensive rats and Wistar-Kyoto controls. On the contrary, in the skeletal muscle of untreated spontaneously hypertensive rats, we noted a significant reduction of insulin receptors, of insulin-receptor substrate-1, and of phosphorylated-mammalian target of rapamycin. The treatment with olmesartan normalized insulin signaling, including expression of glucose transporter-4, whereas the treatment with enalapril was ineffective for the insulin receptor and less effective than olmesartan on the insulin-receptor substrate-1, phosphorylated-mammalian target of rapamycin and glucose transporter-4. There was a significant reduction in microvessel density in the skeletal muscle of spontaneously hypertensive rats compared with Wistar-Kyoto controls, and this was completely prevented by both olmesartan and enalapril

  13. Growth inhibition signalled through the interleukin-4/interleukin-13 receptor complex is associated with tyrosine phosphorylation of insulin receptor substrate-1.

    Science.gov (United States)

    Schnyder, B; Lahm, H; Woerly, G; Odartchenko, N; Ryffel, B; Car, B D

    1996-05-01

    Induction of growth inhibition in human colorectal carcinoma cell lines by interleukin (IL)-4 and IL-13 was associated with the neophosphorylation of a 170 kDa cellular protein, identified as insulin receptor substrate-1 (IRS-1) by immunoprecipitation. Tyrosine phosphorylation of IRS-I was also induced by insulin and insulin-like growth factor I. Sublines of colorectal carcinoma cells unresponsive to growth modulation by IL-4, IL-13 or insulin-like growth factor I-induced growth did not phosphorylate IRS-1. A functional, multimeric IL-4 receptor complex was present on all carcinoma cell lines with a subunit composition of 65 kDa, 75 kDa and the previously characterized 130 kDa band as demonstrated by affinity cross-link with 126I labelled IL-4. The 65 kDa subunit is novel whereas the 75 kDa band represents the common IL-2 receptor gama-chain the novel 65 kDa receptor was present as a double band and bound primarily 125I-labelled IL-13. The present study demonstrates the involvement of a novel chain other than the gama-chain in the receptor complexes of IL-4 and IL-13 and and post-receptor tyrosine phosphorylation of IRS-1. The association of IRS-1 with growth inhibitory signals in carcinoma cells suggests a novel mechanism of tumour growth control.

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

    DEFF Research Database (Denmark)

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

    2008-01-01

    differentially activates post-receptor signalling, we studied the gene expression profile in response to IR activation by either insulin or S597 using microarray technology. We found striking differences between the patterns induced by these two ligands. Most remarkable was that almost half of the genes...... differentially regulated by insulin and S597 were involved in cell proliferation and growth. Insulin either selectively regulated the expression of these genes or was a more potent regulator. Furthermore, we found that half of the differentially regulated genes interact with the genes involved with the MAPK...... differentially affect gene expression in cells, resulting in a different mitogenicity of the two ligands, a finding which has critical therapeutic implications Udgivelsesdato: 2008/6/15...

  15. Regulation of Blood Pressure, Appetite, and Glucose by Leptin After Inactivation of Insulin Receptor Substrate 2 Signaling in the Entire Brain or in Proopiomelanocortin Neurons

    National Research Council Canada - National Science Library

    do Carmo, Jussara M; da Silva, Alexandre A; Wang, Zhen; Freeman, Nathan J; Alsheik, Ammar J; Adi, Ahmad; Hall, John E

    Insulin receptor substrate 2 (IRS2) is one of the 3 major leptin receptor signaling pathways, but its role in mediating the chronic effects of leptin on blood pressure, food intake, and glucose regulation is unclear...

  16. Oleanolic acid supplement attenuates liquid fructose-induced adipose tissue insulin resistance through the insulin receptor substrate-1/phosphatidylinositol 3-kinase/Akt signaling pathway in rats.

    Science.gov (United States)

    Li, Ying; Wang, Jianwei; Gu, Tieguang; Yamahara, Johji; Li, Yuhao

    2014-06-01

    Oleanolic acid, a triterpenoid contained in more than 1620 plants including various fruits and foodstuffs, has numerous metabolic effects, such as hepatoprotection. However, its underlying mechanisms remain poorly understood. Adipose tissue insulin resistance (Adipo-IR) may contribute to the development and progress of metabolic abnormalities through release of excessive free fatty acids from adipose tissue. This study investigated the effect of oleanolic acid on Adipo-IR. The results showed that supplement with oleanolic acid (25 mg/kg, once daily, by oral gavage) over 10 weeks attenuated liquid fructose-induced increase in plasma insulin concentration and the homeostasis model assessment of insulin resistance (HOMA-IR) index in rats. Simultaneously, oleanolic acid reversed the increase in the Adipo-IR index and plasma non-esterified fatty acid concentrations during the oral glucose tolerance test assessment. In white adipose tissue, oleanolic acid enhanced mRNA expression of the genes encoding insulin receptor, insulin receptor substrate (IRS)-1 and phosphatidylinositol 3-kinase. At the protein level, oleanolic acid upregulated total IRS-1 expression, suppressed the increased phosphorylated IRS-1 at serine-307, and restored the increased phosphorylated IRS-1 to total IRS-1 ratio. In contrast, phosphorylated Akt to total Akt ratio was increased. Furthermore, oleanolic acid reversed fructose-induced decrease in phosphorylated-Akt/Akt protein to plasma insulin concentration ratio. However, oleanolic acid did not affect IRS-2 mRNA expression. Therefore, these results suggest that oleanolic acid supplement ameliorates fructose-induced Adipo-IR in rats via the IRS-1/phosphatidylinositol 3-kinase/Akt pathway. Our findings may provide new insights into the mechanisms of metabolic actions of oleanolic acid. Copyright © 2014 Elsevier Inc. All rights reserved.

  17. Surface-expressed insulin receptors as well as IGF-I receptors both contribute to the mitogenic effects of human insulin and its analogues

    DEFF Research Database (Denmark)

    Lundby, Anders; Bolvig, Pernille; Hegelund, Anne Charlotte

    2015-01-01

    There is a medical need for new insulin analogues. Yet, molecular alterations to the insulin molecule can theoretically result in analogues with carcinogenic effects. Preclinical carcinogenicity risk assessment for insulin analogues rests to a large extent on mitogenicity assays in cell lines. We...

  18. Sleep deprivation alters energy homeostasis through non-compensatory alterations in hypothalamic insulin receptors in Wistar rats.

    Science.gov (United States)

    Moraes, Danilo Alves; Venancio, Daniel Paulino; Suchecki, Deborah

    2014-11-01

    Studies have shown a gradual reduction of sleep time in the general population, accompanied by increased food intake, representing a risk for developing obesity, type II diabetes and cardiovascular disease. Rats subjected to paradoxical sleep deprivation (PSD) exhibit feeding and metabolic alterations, both of which are regulated by the communication between peripheral signals and the hypothalamus. This study aimed to investigate the daily change of 96 h of PSD-induced food intake, body weight, blood glucose, plasma insulin and leptin concentrations and the expression of their receptors in the hypothalamus of Wistar rats. Food intake was assessed during the light and dark phases and was progressively increased in sleep-deprived animals, during the light phase. PSD produced body weight loss, particularly on the first day, and decreased plasma insulin and leptin levels, without change in blood glucose levels. Reduced leptin levels were compensated by increased expression of leptin receptors in the hypothalamus, whereas no compensations occurred in insulin receptors. The present results on body weight loss and increased food intake replicate previous studies from our group. The fact that reduced insulin levels did not lead to compensatory changes in hypothalamic insulin receptors, suggests that this hormone may be, at least in part, responsible for PSD-induced dysregulation in energy metabolism. Copyright © 2014 Elsevier Inc. All rights reserved.

  19. Human blood-brain barrier insulin-like growth factor receptor

    Energy Technology Data Exchange (ETDEWEB)

    Duffy, K.R.; Pardridge, W.M.; Rosenfeld, R.G.

    1988-02-01

    Insulin-like growth factor (IGF)-1 and IGF-2, may be important regulatory molecules in the CNS. Possible origins of IGFs in brain include either de novo synthesis or transport of circulating IGFs from blood into brain via receptor mediated transcytosis mechanisms at the brain capillary endothelial wall, ie, the blood-brain barrier (BBB). In the present studies, isolated human brain capillaries are used as an in vitro model system of the human BBB and the characteristics of IGF-1 or IGF-2 binding to this preparation were assessed. The total binding of IGF-2 at 37 degrees C exceeded 130% per mg protein and was threefold greater than the total binding for IGF-1. However, at 37 degrees C nonsaturable binding equaled total binding, suggesting that endocytosis is rate limiting at physiologic temperatures. Binding studies performed at 4 degrees C slowed endocytosis to a greater extent than membrane binding, and specific binding of either IGF-1 or IGF-2 was detectable. Scatchard plots for either peptide were linear and the molar dissociation constant of IGF-1 and IGF-2 binding was 2.1 +/- 0.4 and 1.1 +/- 0.1 nmol/L, respectively. Superphysiologic concentrations of porcine insulin inhibited the binding of both IGF-1 (ED50 = 2 micrograms/mL) and IGF-2 (ED50 = 0.5 microgram/mL). Affinity cross linking of /sup 125/I-IGF-1, /sup 125/I-IGF-2, and /sup 125/I-insulin to isolated human brain capillaries was performed using disuccinimidylsuberate (DSS). These studies revealed a 141 kd binding site for both IGF-1 and IGF-2, and a 133 kd binding site for insulin.

  20. Peroxisome proliferator-activated receptor gamma agonists as insulin sensitizers: from the discovery to recent progress.

    Science.gov (United States)

    Cho, Nobuo; Momose, Yu

    2008-01-01

    An epidemic of metabolic diseases including type 2 diabetes and obesity is undermining the health of people living in industrialized societies. There is an urgent need to develop innovative therapeutics. The peroxisome proliferator-activated receptor gamma (PPARgamma) is one of the ligand-activated transcription factors in the nuclear hormone receptor superfamily and a pivotal regulator of glucose and lipid homeostasis. The discovery of PPARgamma as a target of multimodal insulin sensitizers, represented by thiazolidinediones (TZDs), has attracted remarkable scientific interest and had a great impact on the pharmaceutical industry. With the clinical success of the PPARgamma agonists, pioglitazone (Actos) and rosiglitazone (Avandia), development of novel and potent insulin-sensitizing agents with diverse clinical profiles has been accelerated. Currently, a number of PPARgamma agonists from different chemical classes and with varying pharmacological profiles are being developed. Despite quite a few obstacles to the development of PPAR-related drugs, PPARgamma-targeted agents still hold promise. There are new concepts and encouraging evidence emerging that suggest this class can yield improved anti-diabetic agents. This review covers the discovery of TZDs, provides an overview of PPARgamma including the significance of PPARgamma as a drug target, describes the current status of a wide variety of novel PPARgamma ligands including PPAR dual and pan agonists and selective PPARgamma modulators (SPPARgammaMs), and highlights new approaches for identifying agents targeting PPARgamma in the treatment of type 2 diabetes.

  1. Distinct growth hormone receptor signaling modes regulate skeletal muscle development and insulin sensitivity in mice.

    Science.gov (United States)

    Mavalli, Mahendra D; DiGirolamo, Douglas J; Fan, Yong; Riddle, Ryan C; Campbell, Kenneth S; van Groen, Thomas; Frank, Stuart J; Sperling, Mark A; Esser, Karyn A; Bamman, Marcas M; Clemens, Thomas L

    2010-11-01

    Skeletal muscle development, nutrient uptake, and nutrient utilization is largely coordinated by growth hormone (GH) and its downstream effectors, in particular, IGF-1. However, it is not clear which effects of GH on skeletal muscle are direct and which are secondary to GH-induced IGF-1 expression. Thus, we generated mice lacking either GH receptor (GHR) or IGF-1 receptor (IGF-1R) specifically in skeletal muscle. Both exhibited impaired skeletal muscle development characterized by reductions in myofiber number and area as well as accompanying deficiencies in functional performance. Defective skeletal muscle development, in both GHR and IGF-1R mutants, was attributable to diminished myoblast fusion and associated with compromised nuclear factor of activated T cells import and activity. Strikingly, mice lacking GHR developed metabolic features that were not observed in the IGF-1R mutants, including marked peripheral adiposity, insulin resistance, and glucose intolerance. Insulin resistance in GHR-deficient myotubes derived from reduced IR protein abundance and increased inhibitory phosphorylation of IRS-1 on Ser 1101. These results identify distinct signaling pathways through which GHR regulates skeletal muscle development and modulates nutrient metabolism.

  2. Pleiotropic effects of insulin and GLP-1 receptor agonists: Potential benefits of the association.

    Science.gov (United States)

    Cariou, B

    2015-12-01

    The combination of basal insulin and glucagon-like peptide-1 receptor agonists (GLP-1RAs) is an emerging option for patients with type 2 diabetes (T2D). GLP-1RAs have been shown to improve glycaemic control with a low risk of hypoglycaemia and to promote body weight loss. However, GLP-1 receptors (GLP-1Rs) are widely expressed in extrapancreatic tissues and could sustain pleiotropic actions of GLP-1RAs beyond glycaemic control. The underlying molecular mechanisms maintaining these extrapancreatic actions of GLP-1 are complex, and involve GLP-1R signalling in both the brain and several peripheral tissues. The present review focuses specifically on the role of GLP-1RAs in the cardiovascular system and liver. Preclinical data in rodents and pilot studies in humans suggest that GLP-1RAs may have potential beneficial effects on heart function, blood pressure, postprandial lipaemia, liver steatosis and non-alcoholic steatohepatitis (NASH). Long-term studies are now warranted to determine the safety and clinical relevance of the association between insulin and GLP-1RAs in T2D.

  3. Autoradiographic visualization of insulin-like growth factor-II receptors in rat brain

    Energy Technology Data Exchange (ETDEWEB)

    Mendelsohn, L.G.; Kerchner, G.A.; Clemens, J.A.; Smith, M.C.

    1986-03-01

    The documented presence of IGF-II in brain and CSF prompted us to investigate the distribution of receptors for IGF-II in rat brain slices. Human /sup 125/-I-IGF-II (10 pM) was incubated for 16 hrs at 4/sup 0/C with slide-mounted rat brain slices in the absence and presence of unlabeled human IGF-II (67 nM) or human insulin (86 nM). Slides were washed, dried, and exposed to X-ray film for 4-7 days. The results showed dense labeling in the granular layers of the olfactory bulbs, deep layers of the cerebral cortex, pineal gland, anterior pituitary, hippocampus (pyramidal cells CA/sub 1/-CA/sub 2/ and dentate gyrus), and the granule cell layers of the cerebellum. Unlabeled IGF-II eliminated most of the binding of these brain regions while insulin produced only a minimal reduction in the amount of /sup 125/I-IGF-II bound. These results indicate that a specific neural receptor for IGS-II is uniquely distributed in rat brain tissue and supports the notion that this peptide might play an important role in normal neuronal functioning.

  4. Depletion of insulin receptor substrate 2 reverses oncogenic transformation induced by v-src

    Institute of Scientific and Technical Information of China (English)

    Hong-zhi SUN; Lin XU; Bo ZHOU; Wei-jin ZANG; Shu-fang WU

    2011-01-01

    Aim: To investigate the role of insulin receptor substrate 2 (IRS-2) in oncogenic transformation induced by v-src. Methods: IRS-2 gene was silenced using small interfering RNAs (siRNAs). Nuclear translocation and interaction of IRS-2 with v-src was determined using subcellular fractionation, confocal microscopy, and immunoprecipitation. The activity of the cyclin D1 promoter and r-DNA promoter was measured with a luciferase assay.Results: Depletion of IRS-2 inhibited R-/v-src cell growth and reverse the oncogenic transformation. IRS-2 bound to src via its two PI3-K binding sites, which are critical for activities involved in the transformation. Nuclear IRS-2 occupied the cyclin D1 and rDNA promoters. The combination of IRS-2 and v-src increased the activity of the two promoters, especially the rDNA promoter.Conclusion: Depletion of insulin receptor substrate 2 could reverse oncogenic transformation induced by v-src.

  5. Novel nuclear localization and potential function of insulin-like growth factor-1 receptor/insulin receptor hybrid in corneal epithelial cells.

    Directory of Open Access Journals (Sweden)

    Yu-Chieh Wu

    Full Text Available BACKGROUND: Type I insulin-like growth factor receptor (IGF-1R and insulin receptor (INSR are highly homologous molecules, which can heterodimerize to form an IGF-1R/INSR hybrid (Hybrid-R. The presence and biological significance of the Hybrid-R in human corneal epithelium has not yet been established. In addition, while nuclear localization of IGF-1R was recently reported in cancer cells and human corneal epithelial cells, the function and profile of nuclear IGF-1R is unknown. In this study, we characterized the nuclear localization and function of the Hybrid-R and the role of IGF-1/IGF-1R and Hybrid-R signaling in the human corneal epithelium. METHODOLOGY/PRINCIPLE FINDINGS: IGF-1-mediated signaling and cell growth were examined in a human telomerized corneal epithelial (hTCEpi cell line using co-immunoprecipitation, immunoblotting and cell proliferation assays. The presence of Hybrid-R in hTCEpi and primary cultured human corneal epithelial cells was confirmed by immunofluorescence and reciprocal immunoprecipitation of whole cell lysates. We found that IGF-1 stimulated Akt and promoted cell growth through IGF-1R activation, which was independent of the Hybrid-R. The presence of Hybrid-R, but not IGF-1R/IGF-1R, was detected in nuclear extracts. Knockdown of INSR by small interfering RNA resulted in depletion of the INSR/INSR and preferential formation of Hybrid-R. Chromatin-immunoprecipitation sequencing assay with anti-IGF-1R or anti-INSR was subsequently performed to identify potential genomic targets responsible for critical homeostatic regulatory pathways. CONCLUSION/SIGNIFICANCE: In contrast to previous reports on nuclear localized IGF-1R, this is the first report identifying the nuclear localization of Hybrid-R in an epithelial cell line. The identification of a nuclear Hybrid-R and novel genomic targets suggests that IGF-1R traffics to the nucleus as an IGF-1R/INSR heterotetrameric complex to regulate corneal epithelial homeostatic

  6. Peroxisome proliferator-activated receptor γ decouples fatty acid uptake from lipid inhibition of insulin signaling in skeletal muscle.

    Science.gov (United States)

    Hu, Shanming; Yao, Jianrong; Howe, Alexander A; Menke, Brandon M; Sivitz, William I; Spector, Arthur A; Norris, Andrew W

    2012-06-01

    Peroxisome proliferator-activated receptor γ (PPARγ) is expressed at low levels in skeletal muscle, where it protects against adiposity and insulin resistance via unclear mechanisms. To test the hypothesis that PPARγ directly modulates skeletal muscle metabolism, we created two models that isolate direct PPARγ actions on skeletal myocytes. PPARγ was overexpressed in murine myotubes by adenotransfection and in mouse skeletal muscle by plasmid electroporation. In cultured myotubes, PPARγ action increased fatty acid uptake and incorporation into myocellular lipids, dependent upon a 154 ± 20-fold up-regulation of CD36 expression. PPARγ overexpression more than doubled insulin-stimulated thymoma viral proto-oncogene (AKT) phosphorylation during low lipid availability. Furthermore, in myotubes exposed to palmitate levels that inhibit insulin signaling, PPARγ overexpression increased insulin-stimulated AKT phosphorylation and glycogen synthesis over 3-fold despite simultaneously increasing myocellular palmitate uptake. The insulin signaling enhancement was associated with an increase in activating phosphorylation of phosphoinositide-dependent protein kinase 1 and a normalized expression of palmitate-induced genes that antagonize AKT phosphorylation. In vivo, PPARγ overexpression more than doubled insulin-dependent AKT phosphorylation in lipid-treated mice but did not augment insulin-stimulated glucose uptake. We conclude that direct PPARγ action promotes myocellular storage of energy by increasing fatty acid uptake and esterification while simultaneously enhancing insulin signaling and glycogen formation. However, direct PPARγ action in skeletal muscle is not sufficient to account for the hypoglycemic actions of PPARγ agonists during lipotoxicity.

  7. Serine 302 Phosphorylation of Mouse Insulin Receptor Substrate 1 (IRS1) Is Dispensable for Normal Insulin Signaling and Feedback Regulation by Hepatic S6 Kinase.

    Science.gov (United States)

    Copps, Kyle D; Hançer, Nancy J; Qiu, Wei; White, Morris F

    2016-04-15

    Constitutive activation of the mammalian target of rapamycin complex 1 and S6 kinase (mTORC1→ S6K) attenuates insulin-stimulated Akt activity in certain tumors in part through "feedback" phosphorylation of the upstream insulin receptor substrate 1 (IRS1). However, the significance of this mechanism for regulating insulin sensitivity in normal tissue remains unclear. We investigated the function of Ser-302 in mouse IRS1, the major site of its phosphorylation by S6K in vitro, through genetic knock-in of a serine-to-alanine mutation (A302). Although insulin rapidly stimulated feedback phosphorylation of Ser-302 in mouse liver and muscle, homozygous A302 mice (A/A) and their knock-in controls (S/S) exhibited similar glucose homeostasis and muscle insulin signaling. Furthermore, both A302 and control primary hepatocytes from which Irs2 was deleted showed marked inhibition of insulin-stimulated IRS1 tyrosine phosphorylation and PI3K binding after emetine treatment to raise intracellular amino acids and activate mTORC1 → S6K signaling. To specifically activate mTORC1 in mouse tissue, we deleted hepatic Tsc1 using Cre adenovirus. Although it moderately decreased IRS1/PI3K association and Akt phosphorylation in liver, Tsc1 deletion failed to cause glucose intolerance or promote hyperinsulinemia in mixed background A/A or S/S mice. Moreover, Tsc1 deletion failed to stimulate phospho-Ser-302 or other putative S6K sites within IRS1, whereas ribosomal S6 protein was constitutively phosphorylated. Following acute Tsc1 deletion from hepatocytes, Akt phosphorylation, but not IRS1/PI3K association, was rapidly restored by treatment with the mTORC1 inhibitor rapamycin. Thus, within the hepatic compartment, mTORC1 → S6K signaling regulates Akt largely through IRS-independent means with little effect upon physiologic insulin sensitivity.

  8. Insulin Receptor and GPCR Crosstalk Stimulates YAP via PI3K and PKD in Pancreatic Cancer Cells.

    Science.gov (United States)

    Hao, Fang; Xu, Qinhong; Zhao, Yinglan; Stevens, Jan V; Young, Steven H; Sinnett-Smith, James; Rozengurt, Enrique

    2017-07-01

    We examined the impact of crosstalk between the insulin receptor and G protein-coupled receptor (GPCR) signaling pathways on the regulation of Yes-associated protein (YAP) localization, phosphorylation, and transcriptional activity in the context of human pancreatic ductal adenocarcinoma (PDAC). Stimulation of PANC-1 or MiaPaCa-2 cells with insulin and neurotensin, a potent mitogenic combination of agonists for these cells, promoted striking YAP nuclear localization and decreased YAP phosphorylation at Ser(127) and Ser(397) Challenging PDAC cells with either insulin or neurotensin alone modestly induced the expression of YAP/TEAD-regulated genes, including connective tissue growth factor (CTGF), cysteine-rich angiogenic inducer 61 (CYR61), and CXCL5, whereas the combination of neurotensin and insulin induced a marked increase in the level of expression of these genes. In addition, siRNA-mediated knockdown of YAP/TAZ prevented the increase in the expression of these genes. A small-molecule inhibitor (A66), selective for the p110α subunit of PI3K, abrogated the increase in phosphatidylinositol 3,4,5-trisphosphate production and the expression of CTGF, CYR61, and CXCL5 induced by neurotensin and insulin. Furthermore, treatment of PDAC cells with protein kinase D (PKD) family inhibitors (CRT0066101 or kb NB 142-70) or with siRNAs targeting the PKD family prevented the increase of CTGF, CYR61, and CXCL5 mRNA levels in response to insulin and neurotensin stimulation. Thus, PI3K and PKD mediate YAP activation in response to insulin and neurotensin in pancreatic cancer cells.Implications: Inhibitors of PI3K or PKD disrupt crosstalk between insulin receptor and GPCR signaling systems by blocking YAP/TEAD-regulated gene expression in pancreatic cancer cells. Mol Cancer Res; 15(7); 929-41. ©2017 AACR. ©2017 American Association for Cancer Research.

  9. Role of endosomal trafficking dynamics on the regulation of hepatic insulin receptor activity: models for Fao cells.

    Science.gov (United States)

    Hori, Sharon S; Kurland, Irwin J; DiStefano, Joseph J

    2006-05-01

    Evidence indicates that endosomal insulin receptor (IR) trafficking plays a role in regulating insulin signal transduction. To evaluate its importance, we developed a series of biokinetic models for quantifying activated surface and endosomal IR dynamics from published experimental data. Starting with a published two-compartment Fao hepatoma model, a four-pool model was formulated that depicts IR autophosphorylation after receptor binding, IR endosomal internalization/trafficking, insulin dissociation from and dephosphorylation of internalized IR, and recycling of unliganded, dephosphorylated IR to the plasma membrane. Quantification required three additional data sets, two measured, but unmodeled by the same group. A five-pool model created to include endosomal trafficking of the nonphosphorylated insulin-IR complex was fitted using the same data sets, augmented with another published data set. Creation of a six-pool model added the physiologically relevant dissociation of insulin ligand from the activated endosomal IR. More importantly, all three models, validated against additional data not used in model fitting, predict that, mechanistically, internalization of activated IR is a rate-limiting step, at least under the receptor saturating conditions of the fitting data. This rate includes the transit time to a site where insulin dissociation from and/or dephosphorylation of the IR occurs by docking with protein-tyrosine phosphatases (PTPases), or where a sufficient conformational change occurs in the IR, perhaps due to insulin-IR dissociation, where associated PTPases may complete IR dephosphorylation. Our new models indicate that key events in endosomal IR trafficking have significance in mediating IR activity, possibly serving to regulate insulin signal transduction.

  10. Proliferator-activated receptor gamma Pro12Ala interacts with the insulin receptor substrate 1 Gly972Arg and increase the risk of insulin resistance and diabetes in the mixed ancestry population from South Africa.

    Science.gov (United States)

    Vergotine, Zelda; Yako, Yandiswa Y; Kengne, Andre P; Erasmus, Rajiv T; Matsha, Tandi E

    2014-01-21

    The peroxisome proliferator-activated receptor gamma (PPARG), Pro12Ala and the insulin receptor substrate (IRS1), Gly972Arg confer opposite effects on insulin resistance and type 2 diabetes mellitus (T2DM). We investigated the independent and joint effects of PPARG Pro12Ala and IRS1 Gly972Arg on markers of insulin resistance and T2DM in an African population with elevated risk of T2DM. In all 787 (176 men) mixed-ancestry adults from the Bellville-South community in Cape Town were genotyped for PPARG Pro12Ala and IRS1 Gly972Arg by two independent laboratories. Glucose tolerance status and insulin resistance/sensitivity were assessed. Genotype frequencies were 10.4% (PPARG Pro12Ala) and 7.7% (IRS1 Gly972Arg). Alone, none of the polymorphisms predicted prevalent T2DM, but in regression models containing both alleles and their interaction term, PPARG Pro12 conferred a 64% higher risk of T2DM. Furthermore PPARG Pro12 was positively associated in adjusted linear regressions with increased 2-hour post-load insulin in non-diabetic but not in diabetic participants. The PPARG Pro12 is associated with insulin resistance and this polymorphism interacts with IRS1 Gly972Arg, to increase the risk of T2DM in the mixed-ancestry population of South Africa. Our findings require replication in a larger study before any generalisation and possible application for risk stratification.

  11. Mannose-6-phosphate/insulin-like growth Factor-II receptors may represent a target for the selective delivery of mycophenolic acid to fibrogenic cells

    NARCIS (Netherlands)

    Greupink, Albert; Bakker, Hester; van Goor, H.; de Borst, M.H.; Beljaars, L.; Poelstra, Klaas

    2006-01-01

    Purpose. The insulin-like growth factor axis plays an important role in fibrogenesis. However, little is known about mannose-6-phosphate/Insulin-like growth factor-II receptor (M6P/IGF-IIR) expression during fibrosis. When expressed preferentially on fibrogenic cells, this receptor may be used to se

  12. The receptor CD44 is associated with systemic insulin resistance and proinflammatory macrophages in human adipose tissue.

    Science.gov (United States)

    Liu, Li Fen; Kodama, Keiichi; Wei, Ke; Tolentino, Lorna L; Choi, Okmi; Engleman, Edgar G; Butte, Atul J; McLaughlin, Tracey

    2015-07-01

    Proinflammatory immune cell infiltration in human adipose tissue is associated with the development of insulin resistance. We previously identified, via a gene expression-based genome-wide association study, the cell-surface immune cell receptor CD44 as a functionally important gene associated with type 2 diabetes. We then showed that, compared with controls, Cd44 knockout mice were protected from insulin resistance and adipose tissue inflammation during diet-induced obesity. We thus sought to test whether CD44 is associated with adipose tissue inflammation and insulin resistance in humans. Participants included 58 healthy, overweight/moderately obese white adults who met predetermined criteria for insulin resistance or insulin sensitivity based on the modified insulin-suppression test. Serum was collected from 43 participants to measure circulating concentrations of CD44. Subcutaneous adipose tissue was obtained from 17 participants to compare CD44, its ligand osteopontin (OPN, also known as SPP1) and pro-inflammatory gene expression. CD44 expression on adipose tissue macrophage (ATM) surfaces was determined by flow cytometry. Serum CD44 concentrations were significantly increased in insulin-resistant (IR) participants. CD44 gene expression in subcutaneous adipose tissue was threefold higher in the IR subgroup. The expression of OPN, CD68 and IL6 was also significantly elevated in IR individuals. CD44 gene expression correlated significantly with CD68 and IL6 expression. CD44 density on ATMs was associated with proinflammatory M1 polarisation. CD44 and OPN in human adipose tissue are associated with localised inflammation and systemic insulin resistance. This receptor-ligand pair is worthy of further research as a potentially modifiable contributor to human insulin resistance and type 2 diabetes.

  13. Insulin signaling, lifespan and stress resistance are modulated by metabotropic GABA receptors on insulin producing cells in the brain of Drosophila.

    Directory of Open Access Journals (Sweden)

    Lina E Enell

    Full Text Available Insulin-like peptides (ILPs regulate growth, reproduction, metabolic homeostasis, life span and stress resistance in worms, flies and mammals. A set of insulin producing cells (IPCs in the Drosophila brain that express three ILPs (DILP2, 3 and 5 have been the main focus of interest in hormonal DILP signaling. Little is, however, known about factors that regulate DILP production and release by these IPCs. Here we show that the IPCs express the metabotropic GABA(B receptor (GBR, but not the ionotropic GABA(A receptor subunit RDL. Diminishing the GBR expression on these cells by targeted RNA interference abbreviates life span, decreases metabolic stress resistance and alters carbohydrate and lipid metabolism at stress, but not growth in Drosophila. A direct effect of diminishing GBR on IPCs is an increase in DILP immunofluorescence in these cells, an effect that is accentuated at starvation. Knockdown of irk3, possibly part of a G protein-activated inwardly rectifying K(+ channel that may link to GBRs, phenocopies GBR knockdown in starvation experiments. Our experiments suggest that the GBR is involved in inhibitory control of DILP production and release in adult flies at metabolic stress and that this receptor mediates a GABA signal from brain interneurons that may convey nutritional signals. This is the first demonstration of a neurotransmitter that inhibits insulin signaling in its regulation of metabolism, stress and life span in an invertebrate brain.

  14. Aromatic anchor at an invariant hormone-receptor interface: function of insulin residue B24 with application to protein design.

    Science.gov (United States)

    Pandyarajan, Vijay; Smith, Brian J; Phillips, Nelson B; Whittaker, Linda; Cox, Gabriella P; Wickramasinghe, Nalinda; Menting, John G; Wan, Zhu-li; Whittaker, Jonathan; Ismail-Beigi, Faramarz; Lawrence, Michael C; Weiss, Michael A

    2014-12-12

    Crystallographic studies of insulin bound to fragments of the insulin receptor have recently defined the topography of the primary hormone-receptor interface. Here, we have investigated the role of Phe(B24), an invariant aromatic anchor at this interface and site of a human mutation causing diabetes mellitus. An extensive set of B24 substitutions has been constructed and tested for effects on receptor binding. Although aromaticity has long been considered a key requirement at this position, Met(B24) was found to confer essentially native affinity and bioactivity. Molecular modeling suggests that this linear side chain can serve as an alternative hydrophobic anchor at the hormone-receptor interface. These findings motivated further substitution of Phe(B24) by cyclohexanylalanine (Cha), which contains a nonplanar aliphatic ring. Contrary to expectations, [Cha(B24)]insulin likewise exhibited high activity. Furthermore, its resistance to fibrillation and the rapid rate of hexamer disassembly, properties of potential therapeutic advantage, were enhanced. The crystal structure of the Cha(B24) analog, determined as an R6 zinc-stabilized hexamer at a resolution of 1.5 Å, closely resembles that of wild-type insulin. The nonplanar aliphatic ring exhibits two chair conformations with partial occupancies, each recapitulating the role of Phe(B24) at the dimer interface. Together, these studies have defined structural requirements of an anchor residue within the B24-binding pocket of the insulin receptor; similar molecular principles are likely to pertain to insulin-related growth factors. Our results highlight in particular the utility of nonaromatic side chains as probes of the B24 pocket and suggest that the nonstandard Cha side chain may have therapeutic utility. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  15. The insulin receptor is required for the development of the Drosophila peripheral nervous system.

    Directory of Open Access Journals (Sweden)

    Annie Dutriaux

    Full Text Available The Insulin Receptor (InR in Drosophila presents features conserved in its mammalian counterparts. InR is required for growth; it is expressed in the central and embryonic nervous system and modulates the time of differentiation of the eye photoreceptor without altering cell fate. We show that the InR is required for the formation of the peripheral nervous system during larval development and more particularly for the formation of sensory organ precursors (SOPs on the fly notum and scutellum. SOPs arise in the proneural cluster that expresses high levels of the proneural proteins Achaete (Ac and Scute (Sc. The other cells will become epidermis due to lateral inhibition induced by the Notch (N receptor signal that prevents its neighbors from adopting a neural fate. In addition, misexpression of the InR or of other components of the pathway (PTEN, Akt, FOXO induces the development of an abnormal number of macrochaetes that are Drosophila mechanoreceptors. Our data suggest that InR regulates the neural genes ac, sc and sens. The FOXO transcription factor which is localized in the cytoplasm upon insulin uptake, displays strong genetic interaction with the InR and is involved in Ac regulation. The genetic interactions between the epidermal growth factor receptor (EGFR, Ras and InR/FOXO suggest that these proteins cooperate to induce neural gene expression. Moreover, InR/FOXO is probably involved in the lateral inhibition process, since genetic interactions with N are highly significant. These results show that the InR can alter cell fate, independently of its function in cell growth and proliferation.

  16. The Prostaglandin E2 Receptor EP4 Regulates Obesity-Related Inflammation and Insulin Sensitivity.

    Directory of Open Access Journals (Sweden)

    Mika Yasui

    Full Text Available With increasing body weight, macrophages accumulate in adipose tissue. There, activated macrophages secrete numerous proinflammatory cytokines and chemokines, giving rise to chronic inflammation and insulin resistance. Prostaglandin E2 suppresses macrophage activation via EP4; however, the role of EP4 signaling in insulin resistance and type 2 diabetes mellitus remains unknown. In this study, we treated db/db mice with an EP4-selective agonist, ONO-AE1-329, for 4 weeks to explore the role of EP4 signaling in obesity-related inflammation in vivo. Administration of the EP4 agonist did not affect body weight gain or food intake; however, in the EP4 agonist-treated group, glucose tolerance and insulin resistance were significantly improved over that of the vehicle-treated group. Additionally, administration of the EP4 agonist inhibited the accumulation of F4/80-positive macrophages and the formation of crown-like structures in white adipose tissue, and the adipocytes were significantly smaller. The treatment of the EP4 agonist increased the number of anti-inflammatory M2 macrophages, and in the stromal vascular fraction of white adipose tissue, which includes macrophages, it markedly decreased the levels of proinflammatory cytokines and chemokines. Further, EP4 activation increased the expression of adiponectin and peroxidase proliferator-activated receptors in white adipose tissue. Next, we examined in vitro M1/M2 polarization assay to investigate the impact of EP4 signaling on determining the functional phenotypes of macrophages. Treatment with EP4 agonist enhanced M2 polarization in wild-type peritoneal macrophages, whereas EP4-deficient macrophages were less susceptible to M2 polarization. Notably, antagonizing peroxidase proliferator-activated receptor δ activity suppressed EP4 signaling-mediated shift toward M2 macrophage polarization. Thus, our results demonstrate that EP4 signaling plays a critical role in obesity-related adipose tissue

  17. The Prostaglandin E2 Receptor EP4 Regulates Obesity-Related Inflammation and Insulin Sensitivity.

    Science.gov (United States)

    Yasui, Mika; Tamura, Yukinori; Minami, Manabu; Higuchi, Sei; Fujikawa, Risako; Ikedo, Taichi; Nagata, Manabu; Arai, Hidenori; Murayama, Toshinori; Yokode, Masayuki

    2015-01-01

    With increasing body weight, macrophages accumulate in adipose tissue. There, activated macrophages secrete numerous proinflammatory cytokines and chemokines, giving rise to chronic inflammation and insulin resistance. Prostaglandin E2 suppresses macrophage activation via EP4; however, the role of EP4 signaling in insulin resistance and type 2 diabetes mellitus remains unknown. In this study, we treated db/db mice with an EP4-selective agonist, ONO-AE1-329, for 4 weeks to explore the role of EP4 signaling in obesity-related inflammation in vivo. Administration of the EP4 agonist did not affect body weight gain or food intake; however, in the EP4 agonist-treated group, glucose tolerance and insulin resistance were significantly improved over that of the vehicle-treated group. Additionally, administration of the EP4 agonist inhibited the accumulation of F4/80-positive macrophages and the formation of crown-like structures in white adipose tissue, and the adipocytes were significantly smaller. The treatment of the EP4 agonist increased the number of anti-inflammatory M2 macrophages, and in the stromal vascular fraction of white adipose tissue, which includes macrophages, it markedly decreased the levels of proinflammatory cytokines and chemokines. Further, EP4 activation increased the expression of adiponectin and peroxidase proliferator-activated receptors in white adipose tissue. Next, we examined in vitro M1/M2 polarization assay to investigate the impact of EP4 signaling on determining the functional phenotypes of macrophages. Treatment with EP4 agonist enhanced M2 polarization in wild-type peritoneal macrophages, whereas EP4-deficient macrophages were less susceptible to M2 polarization. Notably, antagonizing peroxidase proliferator-activated receptor δ activity suppressed EP4 signaling-mediated shift toward M2 macrophage polarization. Thus, our results demonstrate that EP4 signaling plays a critical role in obesity-related adipose tissue inflammation and

  18. Reevaluation of Fatty Acid Receptor 1 as a Drug Target for the Stimulation of Insulin Secretion in Humans

    Science.gov (United States)

    Wagner, Robert; Kaiser, Gabriele; Gerst, Felicia; Christiansen, Elisabeth; Due-Hansen, Maria E.; Grundmann, Manuel; Machicao, Fausto; Peter, Andreas; Kostenis, Evi; Ulven, Trond; Fritsche, Andreas; Häring, Hans-Ulrich; Ullrich, Susanne

    2013-01-01

    The role of free fatty acid receptor 1 (FFAR1/GPR40) in glucose homeostasis is still incompletely understood. Small receptor agonists stimulating insulin secretion are undergoing investigation for the treatment of type 2 diabetes. Surprisingly, genome-wide association studies did not discover diabetes risk variants in FFAR1. We reevaluated the role of FFAR1 in insulin secretion using a specific agonist, FFAR1-knockout mice and human islets. Nondiabetic individuals were metabolically phenotyped and genotyped. In vitro experiments indicated that palmitate and a specific FFAR1 agonist, TUG-469, stimulate glucose-induced insulin secretion through FFAR1. The proapoptotic effect of chronic exposure of β-cells to palmitate was independent of FFAR1. TUG-469 was protective, whereas inhibition of FFAR1 promoted apoptosis. In accordance with the proapoptotic effect of palmitate, in vivo cross-sectional observations demonstrated a negative association between fasting free fatty acids (NEFAs) and insulin secretion. Because NEFAs stimulate secretion through FFAR1, we examined the interaction of genetic variation in FFAR1 with NEFA and insulin secretion. The inverse association of NEFA and secretion was modulated by rs1573611 and became steeper for carriers of the minor allele. In conclusion, FFAR1 agonists support β-cell function, but variation in FFAR1 influences NEFA effects on insulin secretion and therefore could affect therapeutic efficacy of FFAR1 agonists. PMID:23378609

  19. Glucagon-like peptide 1 receptor playsa critical role in geniposide-regulated insulin secretion in INS-1 cells

    Institute of Scientific and Technical Information of China (English)

    Li-xia GUO; Zhi-ning XIA; Xue GAO; Fei YIN; Jian-hui LIU

    2012-01-01

    Aim:To explore the role of the glucagon-like peptide 1 receptor (GLP-1R) in geniposide regulated insulin secretion in rat INS-1 insulinoma cells.Methods:Rat INS-1 insulinoma cells were cultured.The content of insulin in the culture medium was measured with ELISA assay.GLP-1R gene in INS-1 cells was knocked down with shRNA interference.The level of GLP-1R protein in INS-1 cells was measured with Western blotting.Results:Geniposide (0.01-100 μmol/L) increased insulin secretion from INS-1 cells in a concentration-dependent manner.Geniposide (10 μmol/L) enhanced acute insulin secretion in response to both the low (5.5 mmol/L) and moderately high levels (11 mmol/L) of glucose.Blockade of GLP-1R with the GLP-1R antagonist exendin (9-39) (200 nmol/L) or knock-down of GLP-1R with shRNA interference in INS-1 cells decreased the effect of geniposide (10 μmol/L) on insulin secretion stimulated by glucose (5.5 mmol/L).Conclusion:Geniposide increases insulin secretion through glucagon-like peptide 1 receptors in rat INS-1 insulinoma cells.

  20. Vitamin D inhibits CEACAM1 to promote insulin/IGF-I receptor signaling without compromising anti-proliferative action.

    Science.gov (United States)

    Liu, Wei; Guo, Miao; Ezzat, Shereen; Asa, Sylvia L

    2011-01-01

    Population studies suggest putative links between vitamin D (VD)-deficiency and risk of cancer and diabetes. The insulin/IGF-I receptor represents a signaling target of the carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) that is implicated in both diabetes and cancer, therefore we hypothesized that VD actions may be mediated through this adhesion molecule. In this study, we show that 1,25 vitamin D3 and its analogues EB1089 and KH1060 potently inhibit CEACAM1 expression in cancer cells. This effect was associated with significant reductions in mRNA and protein levels, resulting from transcriptional and posttranslational actions respectively. Insulin/IGF-I-mediated IRS-1 and Akt activation were enhanced by VD treatment. Similarly, CEACAM1 downregulation significantly upregulated the insulin and IGF-I receptors and mimicked the effect of VD-mediated enhanced insulin/IGF-I receptor signaling. Despite improved insulin/IGF-I signaling, the anti-proliferative actions of VD were preserved in the absence or presence of forced CEACAM1 expression. Forced CEACAM1, however, abrogated the anti-invasive actions of VD. Our findings highlight CEACAM1 as a target of VD action. The resulting inhibition of CEACAM1 has potentially beneficial effects on metabolic disorders without necessarily compromising the anticancer properties of this vitamin.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  2. Germline TRAV5D-4 T-cell receptor sequence targets a primary insulin peptide of NOD mice.

    Science.gov (United States)

    Nakayama, Maki; Castoe, Todd; Sosinowski, Tomasz; He, XiangLing; Johnson, Kelly; Haskins, Kathryn; Vignali, Dario A A; Gapin, Laurent; Pollock, David; Eisenbarth, George S

    2012-04-01

    There is accumulating evidence that autoimmunity to insulin B chain peptide, amino acids 9-23 (insulin B:9-23), is central to development of autoimmune diabetes of the NOD mouse model. We hypothesized that enhanced susceptibility to autoimmune diabetes is the result of targeting of insulin by a T-cell receptor (TCR) sequence commonly encoded in the germline. In this study, we aimed to demonstrate that a particular Vα gene TRAV5D-4 with multiple junction sequences is sufficient to induce anti-islet autoimmunity by studying retrogenic mouse lines expressing α-chains with different Vα TRAV genes. Retrogenic NOD strains expressing Vα TRAV5D-4 α-chains with many different complementarity determining region (CDR) 3 sequences, even those derived from TCRs recognizing islet-irrelevant molecules, developed anti-insulin autoimmunity. Induction of insulin autoantibodies by TRAV5D-4 α-chains was abrogated by the mutation of insulin peptide B:9-23 or that of two amino acid residues in CDR1 and 2 of the TRAV5D-4. TRAV13-1, the human ortholog of murine TRAV5D-4, was also capable of inducing in vivo anti-insulin autoimmunity when combined with different murine CDR3 sequences. Targeting primary autoantigenic peptides by simple germline-encoded TCR motifs may underlie enhanced susceptibility to the development of autoimmune diabetes.

  3. Roles of sulfonylurea receptor 1 and multidrug resistance protein 1 in modulating insulin secretion in human insulinoma

    Institute of Scientific and Technical Information of China (English)

    Cheng-Jiang Li; Hua-Li Zhou; Jun Li; Hong-TianYao; Rong Su; Wen-Peng Li

    2011-01-01

    BACKGROUND: Sulfonylurea receptor 1 (SUR1) and multidrug resistance protein 1 (MRP1) are two prominent members of multidrug resistance proteins associated with insulin secretion. The aims of this study were to investigate their expression in insulinomas and their sole and synergistic effects in modulating abnormalinsulinsecretion. METHODS: Fasting glucose, insulin and C-peptide were measured in 11 insulinoma patients and 11 healthy controls. Prolonged oral glucose tolerance tests were performed in 6 insulinoma patients. Insulin content, SUR1 and MRP1 were detected in 11 insulinoma patients by immunohistochemistry. SUR1 and MRP1 were also detected in 6 insulinoma patients by immunofluorescence. RESULTS: Insulinoma patients presented the typical demons-trations of Whipple's triad. Fasting glucose of each insulinoma patient was lower than 2.8 mmol/L, and simultaneous insulin and C-peptide were increased in insulinoma patients. Prolonged oral glucose tolerance tests showed that insulin secretion in insulinoma patients were also stimulated by high glucose. Immunohistochemistry and immunofluorescence staining showed that SUR1 increased, but MRP1 decreased in insulinoma compared with the adjacent islets. CONCLUSIONS: The hypersecretion of insulin in insulinomas might be, at least partially, due to the enrichment of SUR1. In contrast, MRP1, which is down-regulated in insulinomas, might reflect a negative feedback in insulin secretion.

  4. Effects of insulin and exercise training on FGF21, its receptors and target genes in obesity and type 2 diabetes

    DEFF Research Database (Denmark)

    Sørensen, Rikke Kruse; Vienberg, Sara Gry; Vind, Birgitte F

    2017-01-01

    that insulin and exercise increase FGF21 in plasma. Obesity and type 2 diabetes are potentially FGF21-resistant states, but to what extent FGF21 responses to insulin and exercise training are preserved, and whether FGF21, its receptors and target genes are altered, remains to be established. METHODS......: The effects of insulin during euglycaemic-hyperinsulinaemic clamps and 10 week endurance training on serum FGF21 were examined in individuals with type 2 diabetes and in glucose tolerant overweight/obese and lean individuals. Gene expression of FGF21, its receptors and target genes in muscle and WAT biopsies...... obesity with and without type 2 diabetes led to reduced expression of KLB, but increased FGFR1c expression. However, the expression of most FGF21 target genes was unaltered except for reduced CIDEA expression in individuals with type 2 diabetes. CONCLUSIONS...

  5. Improved glucose metabolism in vitro and in vivo by an allosteric monoclonal antibody that increases insulin receptor binding affinity.

    Directory of Open Access Journals (Sweden)

    John A Corbin

    Full Text Available Previously we reported studies of XMetA, an agonist antibody to the insulin receptor (INSR. We have now utilized phage display to identify XMetS, a novel monoclonal antibody to the INSR. Biophysical studies demonstrated that XMetS bound to the human and mouse INSR with picomolar affinity. Unlike monoclonal antibody XMetA, XMetS alone had little or no agonist effect on the INSR. However, XMetS was a strong positive allosteric modulator of the INSR that increased the binding affinity for insulin nearly 20-fold. XMetS potentiated insulin-stimulated INSR signaling ∼15-fold or greater including; autophosphorylation of the INSR, phosphorylation of Akt, a major enzyme in the metabolic pathway, and phosphorylation of Erk, a major enzyme in the growth pathway. The enhanced signaling effects of XMetS were more pronounced with Akt than with Erk. In cultured cells, XMetS also enhanced insulin-stimulated glucose transport. In contrast to its effects on the INSR, XMetS did not potentiate IGF-1 activation of the IGF-1 receptor. We studied the effect of XMetS treatment in two mouse models of insulin resistance and diabetes. The first was the diet induced obesity mouse, a hyperinsulinemic, insulin resistant animal, and the second was the multi-low dose streptozotocin/high-fat diet mouse, an insulinopenic, insulin resistant animal. In both models, XMetS normalized fasting blood glucose levels and glucose tolerance. In concert with its ability to potentiate insulin action at the INSR, XMetS reduced insulin and C-peptide levels in both mouse models. XMetS improved the response to exogenous insulin without causing hypoglycemia. These data indicate that an allosteric monoclonal antibody can be generated that markedly enhances the binding affinity of insulin to the INSR. These data also suggest that an INSR monoclonal antibody with these characteristics may have the potential to both improve glucose metabolism in insulinopenic type 2 diabetes mellitus and correct

  6. Aflatoxin B1 up-regulates insulin receptor substrate 2 and stimulates hepatoma cell migration.

    Directory of Open Access Journals (Sweden)

    Yanli Ma

    Full Text Available Aflatoxin B1 (AFB1 is a potent carcinogen that can induce hepatocellular carcinoma. AFB1-8,9-exo-epoxide, one of AFB1 metabolites, acts as a mutagen to react with DNA and induce gene mutations, including the tumor suppressor p53. In addition, AFB1 reportedly stimulates IGF receptor activation. Aberrant activation of IGF-I receptor (IGF-IR signaling is tightly associated with various types of human tumors. In the current study, we investigated the effects of AFB1 on key elements in IGF-IR signaling pathway, and the effects of AFB1 on hepatoma cell migration. The results demonstrated that AFB1 induced IGF-IR, Akt, and Erk1/2 phosphorylation in hepatoma cell lines HepG2 and SMMC-7721, and an immortalized human liver cell line Chang liver. AFB1 also down-regulated insulin receptor substrate (IRS 1 but paradoxically up-regulated IRS2 through preventing proteasomal degradation. Treatment of hepatoma cells and Chang liver cells with IGF-IR inhibitor abrogated AFB1-induced Akt and Erk1/2 phosphorylation. In addition, IRS2 knockdown suppressed AFB1-induced Akt and Erk1/2 phosphorylation. Finally, AFB1 stimulated hepatoma cell migration. IGF-IR inhibitor or IRS2 knockdown suppressed AFB1-induced hepatoma cell migration. These data demonstrate that AFB1 stimulates hepatoma cell migration through IGF-IR/IRS2 axis.

  7. Expression of transient receptor potential ankyrin 1 (TRPA1 and its role in insulin release from rat pancreatic beta cells.

    Directory of Open Access Journals (Sweden)

    De-Shou Cao

    Full Text Available OBJECTIVE: Several transient receptor potential (TRP channels are expressed in pancreatic beta cells and have been proposed to be involved in insulin secretion. However, the endogenous ligands for these channels are far from clear. Here, we demonstrate the expression of the transient receptor potential ankyrin 1 (TRPA1 ion channel in the pancreatic beta cells and its role in insulin release. TRPA1 is an attractive candidate for inducing insulin release because it is calcium permeable and is activated by molecules that are produced during oxidative glycolysis. METHODS: Immunohistochemistry, RT-PCR, and Western blot techniques were used to determine the expression of TRPA1 channel. Ca²⁺ fluorescence imaging and electrophysiology (voltage- and current-clamp techniques were used to study the channel properties. TRPA1-mediated insulin release was determined using ELISA. RESULTS: TRPA1 is abundantly expressed in a rat pancreatic beta cell line and freshly isolated rat pancreatic beta cells, but not in pancreatic alpha cells. Activation of TRPA1 by allyl isothiocyanate (AITC, hydrogen peroxide (H₂O₂, 4-hydroxynonenal (4-HNE, and cyclopentenone prostaglandins (PGJ₂ and a novel agonist methylglyoxal (MG induces membrane current, depolarization, and Ca²⁺ influx leading to generation of action potentials in a pancreatic beta cell line and primary cultured pancreatic beta cells. Activation of TRPA1 by agonists stimulates insulin release in pancreatic beta cells that can be inhibited by TRPA1 antagonists such as HC030031 or AP-18 and by RNA interference. TRPA1-mediated insulin release is also observed in conditions of voltage-gated Na⁺ and Ca²⁺ channel blockade as well as ATP sensitive potassium (K(ATP channel activation. CONCLUSIONS: We propose that endogenous and exogenous ligands of TRPA1 cause Ca²⁺ influx and induce basal insulin release and that TRPA1-mediated depolarization acts synergistically with K(ATP channel blockade to

  8. Differential pathway coupling efficiency of the activated insulin receptor drives signaling selectivity by xmeta, an allosteric partial agonist antibody

    Science.gov (United States)

    XMetA, an anti-insulin receptor (IR) monoclonal antibody, is an allosteric partial agonist of the IR. We have previously reported that XMetA activates the “metabolic-biased” Akt kinase signaling pathway while having little or no effect on the “mitogenic” MAPK signaling pathwayof ERK 1/2. To inves...

  9. A novel syndrome of autosomal-dominant hyperinsulinemic hypoglycemia linked to a mutation in the human insulin receptor gene

    DEFF Research Database (Denmark)

    Højlund, Kurt; Hansen, Torben; Lajer, Maria

    2004-01-01

    a missense mutation (Arg1174Gln) in the tyrosine kinase domain of the insulin receptor gene that cosegregated with the disease phenotype (logarithm of odds [LOD] score 3.21). In conclusion, we report a novel syndrome of autosomal-dominant hyperinsulinemic hypoglycemia. The findings demonstrate...

  10. Insulin-like growth factor-I and its receptor in neovascular age-related macular degeneration

    NARCIS (Netherlands)

    A.C. Lambooij; K.H.M. van Wely (Karel); D.J. Lindenbergh-Kortleve (Dicky); R.W.A.M. Kuijpers (Robert); M. Kliffen (Mike); C.M. Mooy (Cornelia)

    2003-01-01

    textabstractPURPOSE: The insulin-like growth factor (IGF)-I protein is a growth-promoting polypeptide that can act as an angiogenic agent in the eye. The purpose of the current study was to localize the expression of IGF-I and its receptor (IGF-IR) mRNA and IGF-IR protein in situ i

  11. Long-term intermittent feeding, but not caloric restriction, leads to redox imbalance, insulin receptor nitration, and glucose intolerance.

    Science.gov (United States)

    Cerqueira, Fernanda M; da Cunha, Fernanda M; Caldeira da Silva, Camille C; Chausse, Bruno; Romano, Renato L; Garcia, Camila C M; Colepicolo, Pio; Medeiros, Marisa H G; Kowaltowski, Alicia J

    2011-10-01

    Calorie restriction is a dietary intervention known to improve redox state, glucose tolerance, and animal life span. Other interventions have been adopted as study models for caloric restriction, including nonsupplemented food restriction and intermittent, every-other-day feedings. We compared the short- and long-term effects of these interventions to ad libitum protocols and found that, although all restricted diets decrease body weight, intermittent feeding did not decrease intra-abdominal adiposity. Short-term calorie restriction and intermittent feeding presented similar results relative to glucose tolerance. Surprisingly, long-term intermittent feeding promoted glucose intolerance, without a loss in insulin receptor phosphorylation. Intermittent feeding substantially increased insulin receptor nitration in both intra-abdominal adipose tissue and muscle, a modification associated with receptor inactivation. All restricted diets enhanced nitric oxide synthase levels in the insulin-responsive adipose tissue and skeletal muscle. However, whereas calorie restriction improved tissue redox state, food restriction and intermittent feedings did not. In fact, long-term intermittent feeding resulted in largely enhanced tissue release of oxidants. Overall, our results show that restricted diets are significantly different in their effects on glucose tolerance and redox state when adopted long-term. Furthermore, we show that intermittent feeding can lead to oxidative insulin receptor inactivation and glucose intolerance.

  12. Divergent effects of insulin-like growth factor-1 receptor expression on prognosis of estrogen receptor positive versus triple negative invasive ductal breast carcinoma

    NARCIS (Netherlands)

    Hartog, H.; Horlings, H.M.; Vegt, B. van der; Kreike, B.; Ajouaou, A.; Vijver, M.J. van de; Marike Boezen, H.; Bock, G.H. de; Graaf, W.T. van der; Wesseling, J.

    2011-01-01

    The insulin-like growth factor type 1 receptor (IGF1R) is involved in progression of breast cancer and resistance to systemic treatment. Targeting IGF1R signaling may, therefore, be beneficial in systemic treatment. We report the effect of IGF1R expression on prognosis in invasive ductal breast carc

  13. Divergent effects of insulin-like growth factor-1 receptor expression on prognosis of estrogen receptor positive versus triple negative invasive ductal breast carcinoma

    NARCIS (Netherlands)

    Hartog, Hermien; Horlings, Hugo M; van der Vegt, Bert; Kreike, Bas; Ajouaou, Abderrahim; van de Vijver, Marc J; Boezen, Hendrika; de Bock, Geertruida H; van der Graaf, Wilhelmina; Wesseling, Jelle

    2011-01-01

    The insulin-like growth factor type 1 receptor (IGF1R) is involved in progression of breast cancer and resistance to systemic treatment. Targeting IGF1R signaling may, therefore, be beneficial in systemic treatment. We report the effect of IGF1R expression on prognosis in invasive ductal breast carc

  14. Role of cannabinoid receptor 1 in human adipose tissue for lipolysis regulation and insulin resistance.

    Science.gov (United States)

    Sidibeh, Cherno O; Pereira, Maria J; Lau Börjesson, Joey; Kamble, Prasad G; Skrtic, Stanko; Katsogiannos, Petros; Sundbom, Magnus; Svensson, Maria K; Eriksson, Jan W

    2017-03-01

    We recently showed that the peripheral cannabinoid receptor type 1 (CNR1) gene is upregulated by the synthetic glucocorticoid dexamethasone. CNR1 is highly expressed in the central nervous system and has been a drug target for the treatment of obesity. Here we explore the role of peripheral CNR1 in states of insulin resistance in human adipose tissue. Subcutaneous adipose tissue was obtained from well-controlled type 2 diabetes subjects and controls. Subcutaneous adipose tissue gene expression levels of CNR1 and endocannabinoid synthesizing and degrading enzymes were assessed. Furthermore, paired human subcutaneous adipose tissue and omental adipose tissue from non-diabetic volunteers undergoing kidney donation or bariatric surgery, was incubated with or without dexamethasone. Subcutaneous adipose tissue obtained from volunteers through needle biopsy was incubated with or without dexamethasone and in the presence or absence of the CNR1-specific antagonist AM281. CNR1 gene and protein expression, lipolysis and glucose uptake were evaluated. Subcutaneous adipose tissue CNR1 gene expression levels were 2-fold elevated in type 2 diabetes subjects compared with control subjects. Additionally, gene expression levels of CNR1 and endocannabinoid-regulating enzymes from both groups correlated with markers of insulin resistance. Dexamethasone increased CNR1 expression dose-dependently in subcutaneous adipose tissue and omental adipose tissue by up to 25-fold. Dexamethasone pre-treatment of subcutaneous adipose tissue increased lipolysis rate and reduced glucose uptake. Co-incubation with the CNR1 antagonist AM281 prevented the stimulatory effect on lipolysis, but had no effect on glucose uptake. CNR1 is upregulated in states of type 2 diabetes and insulin resistance. Furthermore, CNR1 is involved in glucocorticoid-regulated lipolysis. Peripheral CNR1 could be an interesting drug target in type 2 diabetes and dyslipidemia.

  15. Oleanolic acid supplement attenuates liquid fructose-induced adipose tissue insulin resistance through the insulin receptor substrate-1/phosphatidylinositol 3-kinase/Akt signaling pathway in rats

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ying [Faculty of Basic Medical Sciences, Chongqing Medical University, Chongqing 400016 (China); Wang, Jianwei, E-mail: wangjianwei1968@gmail.com [Department of Traditional Chinese Medicine, Chongqing Medical University, Chongqing 400016 (China); Gu, Tieguang [Endocrinology and Metabolism Group, Sydney Institute of Health Sciences, Sydney, NSW 2000 Australia (Australia); Yamahara, Johji [Pharmafood Institute, Kyoto 602-8136 (Japan); Li, Yuhao, E-mail: yuhao@sitcm.edu.au [Endocrinology and Metabolism Group, Sydney Institute of Health Sciences, Sydney, NSW 2000 Australia (Australia)

    2014-06-01

    Oleanolic acid, a triterpenoid contained in more than 1620 plants including various fruits and foodstuffs, has numerous metabolic effects, such as hepatoprotection. However, its underlying mechanisms remain poorly understood. Adipose tissue insulin resistance (Adipo-IR) may contribute to the development and progress of metabolic abnormalities through release of excessive free fatty acids from adipose tissue. This study investigated the effect of oleanolic acid on Adipo-IR. The results showed that supplement with oleanolic acid (25 mg/kg, once daily, by oral gavage) over 10 weeks attenuated liquid fructose-induced increase in plasma insulin concentration and the homeostasis model assessment of insulin resistance (HOMA-IR) index in rats. Simultaneously, oleanolic acid reversed the increase in the Adipo-IR index and plasma non-esterified fatty acid concentrations during the oral glucose tolerance test assessment. In white adipose tissue, oleanolic acid enhanced mRNA expression of the genes encoding insulin receptor, insulin receptor substrate (IRS)-1 and phosphatidylinositol 3-kinase. At the protein level, oleanolic acid upregulated total IRS-1 expression, suppressed the increased phosphorylated IRS-1 at serine-307, and restored the increased phosphorylated IRS-1 to total IRS-1 ratio. In contrast, phosphorylated Akt to total Akt ratio was increased. Furthermore, oleanolic acid reversed fructose-induced decrease in phosphorylated-Akt/Akt protein to plasma insulin concentration ratio. However, oleanolic acid did not affect IRS-2 mRNA expression. Therefore, these results suggest that oleanolic acid supplement ameliorates fructose-induced Adipo-IR in rats via the IRS-1/phosphatidylinositol 3-kinase/Akt pathway. Our findings may provide new insights into the mechanisms of metabolic actions of oleanolic acid. - Highlights: • Adipose insulin resistance (Adipo-IR) contributes to metabolic abnormalities. • We investigated the effect of oleanolic acid (OA) on adipo-IR in

  16. PTPIP51: A New Interaction Partner of the Insulin Receptor and PKA in Adipose Tissue

    Directory of Open Access Journals (Sweden)

    M. A. Bobrich

    2013-01-01

    Full Text Available Aims. Our previous experiments revealed an association of PTPIP51 (protein tyrosine phosphatase interacting protein 51 with the insulin signalling pathway through PTP1B and 14-3-3beta. We aimed to clarify the role of PTPIP51 in adipocyte metabolism. Methods. Four groups of ten C57Bl/6 mice each were used. Two groups were fed a standard diet; two groups were fed a high-fat diet. Two groups (one high-fat diet and one standard diet were submitted to endurance training, while the remaining two groups served as untrained control groups. After ten weeks, we measured glucose tolerance of the mice. Adipose tissue samples were analyzed by immunofluorescence and Duolink proximity ligation assay to quantify interactions of PTPIP51 with either insulin receptor (IR or PKA. Results. PTPIP51 and the IR and PTPIP51 and PKA, respectively, were colocalized in all groups. Standard diet animals that were submitted to endurance training showed low PTPIP51-IR and PTPIP51-PKA interactions. The interaction levels of both the IR and PKA differed between the feeding and training groups. Conclusion. PTPIP51 might serve as a linking protein in adipocyte metabolism by connecting the IR-triggered lipogenesis with the PKA-dependent lipolysis. PTPIP51 interacts with both proteins, therefore being a potential gateway for the cooperation of both pathways.

  17. Type 1 insulin-like growth factor receptor monoclonal antibody (HX-1162 treatment for liver cancer

    Directory of Open Access Journals (Sweden)

    Chen XH

    2013-05-01

    Full Text Available Xue-Hui Chen, Zhi-Qiang Li, Hua Peng, Su-Mei Jin, Hui-Qing Fu, Tie-Chui Zhu, Xiao-Gang WengThe First Affiliated Hospital of Xinxiang Medical University, Weihui, People's Republic of ChinaAbstract: One of the most important molecules mediating the proliferation, growth, and metastasis of cancer cells is insulin-like growth factor (IGF, with its receptor IGF-R1. Here, we describe the potential of an IGF-1R monoclonal antibody, HX-1162, on liver cancer apoptosis in vitro and in vivo. We found that HX-1162 could induce the apoptosis of cultured liver cancer cells. Additionally, HX-1162 treatment inhibited the tumor growth after cancer cell grafting and enhanced the cell apoptosis inside the tumor tissue. We conclude that IGF-R1 targeting therapy provides a new avenue toward treating liver cancer.Keywords: IGF, IGF-R1, apoptosis, hepatocellular carcinoma

  18. Direct observation of the autophosphorylation of insulin receptor kinase by mass spectrometry

    Institute of Scientific and Technical Information of China (English)

    Zhi Li Li

    2009-01-01

    The catalytic and signaling activities of insulin receptor kinase(IRK)are regulated by the autophosphorylation of three tyrosine residues in a cytoplasmic protein-tyrosine kinase domain at Tyro 1158,Tyro 1162 and Tyro 1163.In this study,time-course of the auphosphorylation of the core kinase(residues 978-1283)from IRK was directly investigated by online electrospray ionization mass spectrometry.It is found that two tyrosine residues were phosphorylated in reaction time range of 30 min.This study implies that mass spectrometric technique must be a powerful tool to directly monitor the biological macromolecular modification and will also provide the information of the order and the mechanism of autophosphorylation at the tyrosine sites coupled with tandem mass spectrometric technique.

  19. Differential Expression of IGF Components and Insulin Receptor Isoforms in Human Seminoma Versus Normal Testicular Tissue

    Directory of Open Access Journals (Sweden)

    Tanja Pascale Neuvians

    2005-05-01

    Full Text Available Insulin-like growth factors (IGF have mitogenic and antiapoptotic functions, and may be involved in tumor growth. The purpose of the study was to investigate the role of IGF components in seminoma compared to normal testis. Normal testicular tissues from autopsy cases and seminoma from surgery cases were obtained for microarray and real-time reverse transcription polymerase chain reaction (RT-PCR analysis of IGF-1, IGF-2, IGF receptor type 1 (IGF-R1, IGF-R2, insulin receptor isoforms A (IR-A and B (IR-B, and IGF-binding proteins (IGFBP 1-6. IGF-2 was localized by immunohistochemistry. IGFBP-5 protein expression was evaluated by Western blot analysis. mRNA expression in microarray and real-time RT-PCR showed similar tendencies: IGF-1, IGF-R1, IGF-R2, IR-A, and IGFBP-2 were not different in both groups. IGF-2, IR-B, IGFBP-1, IGFBP-4, and IGFBP-6 mRNA were downregulated in seminoma. IGFBP-3 tended to be upregulated in pT1 seminoma, but downregulated in pT2 stages. IGFBP-5 and IGF-2 protein expression correlated with mRNA expression. In conclusion, downregulation of mainly inhibiting IGFBPs may allow a stimulated tumor growth. The downregulated IGF-2 does not seem to be involved in the growth regulation of seminoma. Constantly expressed genes (e.g., IGF-1, IGF-R1, IR-A, and IGFBP-2 may reflect an involvement in spermatogenesis, but may also play a major role in tumor growth as their expression is not downregulated despite the lack of spermatogenesis in tumor tissue.

  20. Silencing of Two Insulin Receptor Genes Disrupts Nymph-Adult Transition of Alate Brown Citrus Aphid

    Science.gov (United States)

    Ding, Bi-Yue; Shang, Feng; Zhang, Qiang; Xiong, Ying; Yang, Qun; Niu, Jin-Zhi; Smagghe, Guy; Wang, Jin-Jun

    2017-01-01

    Insulin receptors play key roles in growth, development, and polymorphism in insects. Here, we report two insulin receptor genes (AcInR1 and AcInR2) from the brown citrus aphid, Aphis (Toxoptera) citricidus. Transcriptional analyses showed that AcInR1 increased during the nymph–adult transition in alate aphids, while AcInR2 had the highest expression level in second instar nymphs. AcInR1 is important in aphid development from fourth instar nymphs to adults as verified by dsRNA feeding mediated RNAi. The silencing of AcInR1 or/and AcInR2 produced a variety of phenotypes including adults with normal wings, malformed wings, under-developed wings, and aphids failing to develop beyond the nymphal stages. Silencing of AcInR1 or AcInR2 alone, and co-silencing of both genes, resulted in 73% or 60%, and 87% of aphids with problems in the transition from nymph to normal adult. The co-silencing of AcInR1 and AcInR2 resulted in 62% dead nymphs, but no mortality occurred by silencing of AcInR1 or AcInR2 alone. Phenotypes of adults in the dsInR1 and dsInR2 were similar. The results demonstrate that AcInR1 and AcInR2 are essential for successful nymph–adult transition in alate aphids and show that RNAi methods may be useful for the management of this pest. PMID:28230772

  1. Combined and individual tumor-specific expression of insulin-like growth factor-I receptor, insulin receptor and phospho-insulin-like growth factor-I receptor/insulin receptor in primary breast cancer: Implications for prognosis in different treatment groups.

    Science.gov (United States)

    Björner, Sofie; Rosendahl, Ann H; Simonsson, Maria; Markkula, Andrea; Jirström, Karin; Borgquist, Signe; Rose, Carsten; Ingvar, Christian; Jernström, Helena

    2017-02-07

    Clinical trials examining insulin-like growth factor-I receptor (IGF1R)-targeting strategies have emphasized that better predictive biomarkers are required to improve patient selection.Immunohistochemical tumor-specific protein expression of IGF1R, insulin receptor (InsR), and phosphorylated IGF1R/InsR (pIGF1R/InsR) individually and combined in relation to breast cancer prognosis was evaluated in a population-based cohort of 1,026 primary invasive breast cancer patients without preoperative treatment diagnosed in Sweden. IGF1R (n = 923), InsR (n = 900), and pIGF1R/InsR (n = 904) combined cytoplasmic and membrane staining was dichotomized. IGF1Rstrong/InsRmod/strong/pIGF1R/InsRpos tumors were borderline associated with 2-fold risk for events, HRadj (2.00; 95%CI 0.96-4.18). Combined IGF1R and pIGF1R/InsR status only impacted prognosis in patients with InsRmod/strong expressing tumors (Pinteraction = 0.041). IGF1Rstrong expression impacted endocrine treatment response differently depending on patients' age and type of endocrine therapy. Phospho-IGF1R/InsRpos was associated with lower risk for events among non-endocrine-treated patients irrespective of ER status, HRadj (0.32; 95%CI 0.16-0.63), but not among endocrine-treated patients (Pinteraction = 0.024). In non-endocrine-treated patients, pIGF1R/InsRpos was associated with lower risk for events after radiotherapy, HRadj (0.31; 95%CI 0.12-0.80), and chemotherapy, HRadj (0.29; 95%CI 0.09-0.99). This study highlights the complexity of IGF hetero-and homodimer signaling network and its interplay with endocrine treatment, suggesting that combinations of involved factors may improve patient selection for IGF1R-targeted therapy.

  2. Neuronal androgen receptor regulates insulin sensitivity via suppression of hypothalamic NF-κB-mediated PTP1B expression.

    Science.gov (United States)

    Yu, I-Chen; Lin, Hung-Yun; Liu, Ning-Chun; Sparks, Janet D; Yeh, Shuyuan; Fang, Lei-Ya; Chen, Lumin; Chang, Chawnshang

    2013-02-01

    Clinical investigations highlight the increased incidence of metabolic syndrome in prostate cancer (PCa) patients receiving androgen deprivation therapy (ADT). Studies using global androgen receptor (AR) knockout mice demonstrate that AR deficiency results in the development of insulin resistance in males. However, mechanisms by which AR in individual organs coordinately regulates insulin sensitivity remain unexplored. Here we tested the hypothesis that functional AR in the brain contributes to whole-body insulin sensitivity regulation and to the metabolic abnormalities developed in AR-deficient male mice. The mouse model selectively lacking AR in the central nervous system and AR-expressing GT1-7 neuronal cells were established and used to delineate molecular mechanisms in insulin signaling modulated by AR. Neuronal AR deficiency leads to reduced insulin sensitivity in middle-aged mice. Neuronal AR regulates hypothalamic insulin signaling by repressing nuclear factor-κB (NF-κB)-mediated induction of protein-tyrosine phosphatase 1B (PTP1B). Hypothalamic insulin resistance leads to hepatic insulin resistance, lipid accumulation, and visceral obesity. The functional deficiency of AR in the hypothalamus leads to male mice being more susceptible to the effects of high-fat diet consumption on PTP1B expression and NF-κB activation. These findings suggest that in men with PCa undergoing ADT, reduction of AR function in the brain may contribute to insulin resistance and visceral obesity. Pharmacotherapies targeting neuronal AR and NF-κB may be developed to combat the metabolic syndrome in men receiving ADT and in elderly men with age-associated hypogonadism.

  3. Characterization of IRA/IRB hybrid insulin receptors using bioluminescence resonance energy transfer.

    Science.gov (United States)

    Blanquart, Christophe; Achi, Josepha; Issad, Tarik

    2008-10-01

    The insulin receptor (IR) is composed of two alpha-chains that bind ligands and two beta-chains that possess an intracellular tyrosine kinase activity. The IR is expressed in cells as two isoforms containing or not exon 11 (IRB and IRA, respectively). Several mRNA studies have demonstrated that the two isoforms are co-expressed in different tissues and in several cancer cells. IRA/IRB hybrid receptors, constituting of an alphabeta-chain from IRA and an alphabeta-chain from IRB, are likely to occur in cells co-expressing both isoforms, but their study has been hampered by the lack of specific tools. In previous work, we used BRET to study IR and IGF1R homodimers and heterodimers. Here, we have used BRET to characterize IRA/IRB hybrids. BRET saturation experiments showed that IRA/IRB hybrids are randomly formed in cells. Moreover, by co-transfecting HEK-293 cells with a luciferase-tagged kinase-dead version of one isoform and a wild-type untagged version of the other isoform, we showed that IRA/IRB hybrids can recruit, upon ligand stimulation, a YFP-tagged intracellular partner. Finally, using BRET, we have studied ligand-induced conformational changes within IRA/IRB hybrids. Dose-response experiments showed that hybrid receptors bind IGF-2 with the same affinity than IRA homodimers, whereas they bind IGF-1 with a lower affinity. Altogether, our data indicate that IRA/IRB hybrid receptors can form in cells co-expressing both IR isoforms, that they are capable of recruiting intracellular partners upon ligand stimulation, and that they have pharmacological properties more similar to those of IRA than those of IRB homodimers with regards to IGF-2.

  4. nitric oxide triggers the phosphatidylinositol 3-kinase/Akt survival pathway in insulin-producing RINm5F cells by arousing Src to activate insulin receptor substrate-1.

    Science.gov (United States)

    Tejedo, Juan R; Cahuana, Gladys M; Ramírez, Remedios; Esbert, Margarida; Jiménez, Juan; Sobrino, Francisco; Bedoya, Francisco J

    2004-05-01

    Mechanisms involved in the protective action of nitric oxide (NO) in insulin-producing cells are a matter of debate. We have previously shown that pharmacological inhibition of c-Src cancels the antiapoptotic action of low and sustained concentrations of exogenous NO. In this study, using insulin-producing RINm5F cells that overexpress Src either permanently active (v-Src) or dominant negative (dn-Src) forms, we determine that this tyrosine kinase is the principal mediator of the protective action of NO. We also show that Src-directed activation of insulin receptor substrate-1, phosphatidylinositol 3-kinase (PI3K), Akt, and Bad phosphorylation conform a substantial component of the survival route because pharmacological inhibition of PI3K and Akt canceled the antiapoptotic effects of NO. Studies performed with the protein kinase G (PKG) inhibitor KT-5823 revealed that NO-dependent activation of c-Src/ insulin receptor substrate-1 is not affected by PKG activation. By contrast, Akt and Bad activation are partially dependent on PKG activation. Endogenous production of NO after overexpression of endothelial nitric oxide synthase in RINm5F cells mimics the effects produced by generation of low amounts of NO from exogenous diethylenetriamine/NO. In addition, we found that NO produces c-Src/PI3K- and PKG-dependent activation of ERK 1/2. The MAPK kinase inhibitor PD 98059 suppresses NO-dependent protection from DNA fragmentation induced by serum deprivation. The protective action of low and sustained concentration of NO is also observed in staurosporine- and Taxol-induced apoptosis. Finally, NO also protects isolated rat islets from DNA fragmentation induced by serum deprivation. These data strengthen the notion that NO production at physiological levels plays a role in protection from apoptosis in pancreatic beta-cells.

  5. Direct angiotensin II type 2 receptor stimulation ameliorates insulin resistance in type 2 diabetes mice with PPARγ activation.

    Directory of Open Access Journals (Sweden)

    Kousei Ohshima

    Full Text Available OBJECTIVES: 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. METHODS: T2DM mice, KK-Ay, were subjected to intraperitoneal injection of C21 and/or a PPARγ antagonist, GW9662 in drinking water for 2 weeks. Insulin resistance was evaluated by oral glucose tolerance test, insulin tolerance test, and uptake of 2-[(3H] deoxy-D-glucose in white adipose tissue. Morphological changes of adipose tissues as well as adipocyte differentiation and inflammatory response were examined. RESULTS: Treatment with C21 ameliorated insulin resistance in KK-Ay mice without influencing blood pressure, at least partially through effects on the PPARγ pathway. C21 treatment increased serum adiponectin concentration and decreased TNF-α concentration; however, these effects were attenuated by PPARγ blockade by co-treatment with GW9662. Moreover, we observed that administration of C21 enhanced adipocyte differentiation and PPARγ DNA-binding activity, with a decrease in inflammation in white adipose tissue, whereas these effects of C21 were attenuated by co-treatment with GW9662. We also observed that administration of C21 restored β cell damage in diabetic pancreatic tissue. CONCLUSION: The present study demonstrated that direct AT(2 receptor stimulation by C21 accompanied with PPARγ activation ameliorated insulin resistance in T2DM mice, at least partially due to improvement of adipocyte dysfunction and protection of pancreatic β cells.

  6. Mice lacking the p43 mitochondrial T3 receptor become glucose intolerant and insulin resistant during aging.

    Directory of Open Access Journals (Sweden)

    Christelle Bertrand

    Full Text Available Thyroid hormones (TH play an important regulatory role in energy expenditure regulation and are key regulators of mitochondrial activity. We have previously identified a mitochondrial triiodothyronine (T3 receptor (p43 which acts as a mitochondrial transcription factor of the organelle genome, which leads in vitro and in vivo, to a stimulation of mitochondrial biogenesis. Recently, we generated mice carrying a specific p43 invalidation. At 2 months of age, we reported that p43 depletion in mice induced a major defect in insulin secretion both in vivo and in isolated pancreatic islets, and a loss of glucose-stimulated insulin secretion. The present study was designed to determine whether p43 invalidation influences life expectancy and modulates blood glucose and insulin levels as well as glucose tolerance or insulin sensitivity during aging. We report that from 4 months old onwards, mice lacking p43 are leaner than wild-type mice. p43-/- mice also have a moderate reduction of life expectancy compared to wild type. We found no difference in blood glucose levels, excepted at 24 months old where p43-/- mice showed a strong hyperglycemia in fasting conditions compared to controls animals. However, the loss of glucose-stimulated insulin secretion was maintained whatever the age of mice lacking p43. If up to 12 months old, glucose tolerance remained unchanged, beyond this age p43-/- mice became increasingly glucose intolerant. In addition, if up to 12 months old p43 deficient animals were more sensitive to insulin, after this age we observed a loss of this capacity, culminating in 24 months old mice with a decreased sensitivity to the hormone. In conclusion, we demonstrated that during aging the depletion of the mitochondrial T3 receptor p43 in mice progressively induced an increased glycemia in the fasted state, glucose intolerance and an insulin-resistance several features of type-2 diabetes.

  7. Activation and Regulation of the Pattern Recognition Receptors in Obesity-Induced Adipose Tissue Inflammation and Insulin Resistance

    Directory of Open Access Journals (Sweden)

    Kiyoshi Takatsu

    2013-09-01

    Full Text Available Obesity-associated chronic tissue inflammation is a key contributing factor to type 2 diabetes mellitus, and a number of studies have clearly demonstrated that the immune system and metabolism are highly integrated. Recent advances in deciphering the various immune cells and signaling networks that link the immune and metabolic systems have contributed to our understanding of the pathogenesis of obesity-associated inflammation. Other recent studies have suggested that pattern recognition receptors in the innate immune system recognize various kinds of endogenous and exogenous ligands, and have a crucial role in initiating or promoting obesity-associated chronic inflammation. Importantly, these mediators act on insulin target cells or on insulin-producing cells impairing insulin sensitivity and its secretion. Here, we discuss how various pattern recognition receptors in the immune system underlie the etiology of obesity-associated inflammation and insulin resistance, with a particular focus on the TLR (Toll-like receptor family protein Radioprotective 105 (RP105/myeloid differentiation protein-1 (MD-1.

  8. Photoperiodic regulation of insulin receptor mRNA and intracellular insulin signaling in the arcuate nucleus of the Siberian hamster, Phodopus sungorus.

    Science.gov (United States)

    Tups, Alexander; Helwig, Michael; Stöhr, Sigrid; Barrett, Perry; Mercer, Julian G; Klingenspor, Martin

    2006-09-01

    During the last 5 years it has been well established that photoperiod-induced changes in body weight in the seasonal hamster, Phodopus sungorus, are accompanied by a marked seasonal cycle in leptin sensitivity. In the present study, we investigated the possible involvement of insulin signaling in seasonal body weight regulation. We analyzed the expression pattern and relative intensity of insulin receptor (IR), phosphatidylinositol 3-kinase (PI3-kinase), and protein tyrosine phosphatase 1B (PTP1B) mRNAs by in situ hybridization in the brains of juvenile female hamsters acclimated to either long- (LD) or short-day length (SD) for 8 wk, with or without superimposed food deprivation for 48 h. Furthermore, the hypothalamic concentration and distribution of phospho-AKT, a marker of PI3-kinase activity was determined by immunoblotting and immunohistochemistry. Eight weeks of acclimation to SD led to a substantial downregulation of IR, PTP1B gene expression, and phospho-AKT concentration in this brain region, whereas PI3-kinase mRNA was unchanged. Food deprivation induced a decrease in PTP1B and a trend toward lowered IR gene expression in LD but not in SD. Additionally, a striking increase in PTP1B gene expression in the thalamus was observed after food deprivation in both photoperiods. The direction of change in neuronal insulin signaling contrasts to the central catabolic nature of this pathway described in other species. SD-induced reduction in insulin signaling may be due to decline in body fat stores mediated by enhanced central leptin sensitivity. Increased anorexigenic tone of leptin may overwrite central insulin signaling to prevent catabolic overdrive.

  9. Central Insulin Action Activates Kupffer Cells by Suppressing Hepatic Vagal Activation via the Nicotinic Alpha 7 Acetylcholine Receptor

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    Kumi Kimura

    2016-03-01

    Full Text Available Central insulin action activates hepatic IL-6/STAT3 signaling, which suppresses the gene expression of hepatic gluconeogenic enzymes. The vagus nerve plays an important role in this centrally mediated hepatic response; however, the precise mechanism underlying this brain-liver interaction is unclear. Here, we present our findings that the vagus nerve suppresses hepatic IL-6/STAT3 signaling via α7-nicotinic acetylcholine receptors (α7-nAchR on Kupffer cells, and that central insulin action activates hepatic IL-6/STAT3 signaling by suppressing vagal activity. Indeed, central insulin-mediated hepatic IL-6/STAT3 activation and gluconeogenic gene suppression were impeded in mice with hepatic vagotomy, pharmacological cholinergic blockade, or α7-nAchR deficiency. In high-fat diet-induced obese and insulin-resistant mice, control of the vagus nerve by central insulin action was disturbed, inducing a persistent increase of inflammatory cytokines. These findings suggest that dysregulation of the α7-nAchR-mediated control of Kupffer cells by central insulin action may affect the pathogenesis of chronic hepatic inflammation in obesity.

  10. AT1-IR-beta Association: A New Mechanism for the Inhibition of Insulin Receptor Function in Breast Cancer

    Directory of Open Access Journals (Sweden)

    Lakshmi Pulakat

    2008-01-01

    Full Text Available Epidemiological evidence show that increased mortality in breast cancer is linked to hypertension and insulin resistance. Because Angiotensin II (Ang II, a hormone implicated in hypertension and insulin resistance, is a normal mitogen for breast tissue and elevated expression of the Ang II receptor AT1 is seen in breast cancer, we analyzed the effects of Ang II exposure on the functions of IR in human breast cancer cell line MCF-7. Exposure of MCF-7 to Ang II for 2 hours a significantly reduced 125I-insulin binding to IR, and b induced co-immuno-precipitation of the AT1 with IR-beta subunit. These Ang II-mediated effects on IR were inhibited by the AT1 antagonist losartan, and were not observed when exposure time was below 1-hour. These observations suggest extended exposure to Ang II have detrimental effects on insulin binding to IR that were not discovered in the previous studies where Ang II-exposure of insulin responsive cells was performed for periods less than one hour. In addition, they suggest a novel mechanism that involves AT1-IR-beta association for the inhibition of insulin binding to IR in response to extended exposure (2-hours of breast cancer cells to elevated levels of Ang II (as seen in hypertensive patients, and provides a molecular link for the inhibition of normal IR signaling by Ang II in breast cancer.

  11. Reduced phosphorylation of brain insulin receptor substrate and Akt proteins in apolipoprotein-E4 targeted replacement mice.

    Science.gov (United States)

    Ong, Qi-Rui; Chan, Elizabeth S; Lim, Mei-Li; Cole, Gregory M; Wong, Boon-Seng

    2014-01-17

    Human ApoE4 accelerates memory decline in ageing and in Alzheimer's disease. Although intranasal insulin can improve cognition, this has little effect in ApoE4 subjects. To understand this ApoE genotype-dependent effect, we examined brain insulin signaling in huApoE3 and huApoE4 targeted replacement (TR) mice. At 32 weeks, lower insulin receptor substrate 1 (IRS1) at S636/639 and Akt phosphorylation at T308 were detected in fasting huApoE4 TR mice as compared to fasting huApoE3 TR mice. These changes in fasting huApoE4 TR mice were linked to lower brain glucose content and have no effect on plasma glucose level. However, at 72 weeks of age, these early changes were accompanied by reduction in IRS2 expression, IRS1 phosphorylation at Y608, Akt phosphorylation at S473, and MAPK (p38 and p44/42) activation in the fasting huApoE4 TR mice. The lower brain glucose was significantly associated with higher brain insulin in the aged huApoE4 TR mice. These results show that ApoE4 reduces brain insulin signaling and glucose level leading to higher insulin content.

  12. Proteomic analysis of the palmitate-induced myotube secretome reveals involvement of the annexin A1-formyl peptide receptor 2 (FPR2) pathway in insulin resistance.

    Science.gov (United States)

    Yoon, Jong Hyuk; Kim, Dayea; Jang, Jin-Hyeok; Ghim, Jaewang; Park, Soyeon; Song, Parkyong; Kwon, Yonghoon; Kim, Jaeyoon; Hwang, Daehee; Bae, Yoe-Sik; Suh, Pann-Ghill; Berggren, Per-Olof; Ryu, Sung Ho

    2015-04-01

    Elevated levels of the free fatty acid palmitate are found in the plasma of obese patients and induce insulin resistance. Skeletal muscle secretes myokines as extracellular signaling mediators in response to pathophysiological conditions. Here, we identified and characterized the skeletal muscle secretome in response to palmitate-induced insulin resistance. Using a quantitative proteomic approach, we identified 36 secretory proteins modulated by palmitate-induced insulin resistance. Bioinformatics analysis revealed that palmitate-induced insulin resistance induced cellular stress and modulated secretory events. We found that the decrease in the level of annexin A1, a secretory protein, depended on palmitate, and that annexin A1 and its receptor, formyl peptide receptor 2 agonist, played a protective role in the palmitate-induced insulin resistance of L6 myotubes through PKC-θ modulation. In mice fed with a high-fat diet, treatment with the formyl peptide receptor 2 agonist improved systemic insulin sensitivity. Thus, we identified myokine candidates modulated by palmitate-induced insulin resistance and found that the annexin A1- formyl peptide receptor 2 pathway mediated the insulin resistance of skeletal muscle, as well as systemic insulin sensitivity. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  13. Association between GRB2/Sos and insulin receptor substrate 1 is not sufficient for activation of extracellular signal-regulated kinases by interleukin-4: implications for Ras activation by insulin.

    Science.gov (United States)

    Pruett, W; Yuan, Y; Rose, E; Batzer, A G; Harada, N; Skolnik, E Y

    1995-03-01

    Insulin receptor substrate 1 (IRS-1) mediates the activation of a variety of signaling pathways by the insulin and insulin-like growth factor 1 receptors by serving as a docking protein for signaling molecules with SH2 domains. We and others have shown that in response to insulin stimulation IRS-1 binds GRB2/Sos and have proposed that this interaction is important in mediating Ras activation by the insulin receptor. Recently, it has been shown that the interleukin (IL)-4 receptor also phosphorylates IRS-1 and an IRS-1-related molecule, 4PS. Unlike insulin, however, IL-4 fails to activate Ras, extracellular signal-regulated kinases (ERKs), or mitogen-activated protein kinases. We have reconstituted the IL-4 receptor into an insulin-responsive L6 myoblast cell line and have shown that IRS-1 is tyrosine phosphorylated to similar degrees in response to insulin and IL-4 stimulation in this cell line. In agreement with previous findings, IL-4 failed to activate the ERKs in this cell line or to stimulate DNA synthesis, whereas the same responses were activated by insulin. Surprisingly, IL-4's failure to activate ERKs was not due to a failure to stimulate the association of tyrosine-phosphorylated IRS-1 with GRB2/Sos; the amounts of GRB2/Sos associated with IRS-1 were similar in insulin- and IL-4-stimulated cells. Moreover, the amounts of phosphatidylinositol 3-kinase activity associated with IRS-1 were similar in insulin- and IL-4-stimulated cells. In contrast to insulin, however, IL-4 failed to induce tyrosine phosphorylation of Shc or association of Shc with GRB2. Thus, ERK activation correlates with Shc tyrosine phosphorylation and formation of an Shc/GRB2 complex. Thus, ERK activation correlates with Shc tyrosine phosphorylation and formation of an Shc/GRB2 complex. Previous studies have indicated that activation of ERks in this cell line is dependent upon Ras since a dominant-negative Ras (Asn-17) blocks ERK activation by insulin. Our findings, taken in the context

  14. Regulation of leptin on insulin secretion and sulfonulurea receptor 1 transcription level in isolated rats pancreatic islets

    Institute of Scientific and Technical Information of China (English)

    袁莉; 安汉祥; 邓秀玲; 李卓娅

    2003-01-01

    Objective To investigate the regulation of leptin on insulin secretion and expression of ATP-sensitive potassium channel subunit sulfonulurea receptor 1 (SUR1) mRNA, and to determine whether the effects of leptin are mediated through known intracellular signaling transduction. Methods Pancreatic islets were isolated by the collagenase method from male SD rats. The purified islets were incubated with different concentrations of leptin for 2 h in the presence of different concentrations of glucose. Insulin release was measured using radioimmunoassay. Expression of SUR1 mRNA was detected by RT-PCR. Results In the presence of leptin 2 nmol/L, insulin release was significantly inhibited at either 11.1 or 16.7 mmol/L glucose concentration (bothP<0.05), but insulin release was not altered at glucose of 5.6 mmol/L physiological concentration. The dose-response experiment showed that the maximal effect of leptin on insulin secretion achieved at 2 nmol/L. Exposure of islets to 2 nmol/L leptin induced a significant increase of SUR1 transcription evels by 71% (P<0.01) at 11.1 mmol/L glucose and by 56% (P<0.05) at 16.7 mmol/L glucose concentration. Selective phosphatidylinositol 3-kinase (PI 3-kinase) inhibitor wortmannin significantly prevented the leptin effect on insulin secretion and SUR1 mRNA expression. Conclusions Regulatory effects of leptin on insulin secretion could be biphasic at different concentrations of glucose and leptin. The stimulatory regulation of SUR1 transcription levels may be mediated through activation of PI 3-kinase pathway, which may be a possible mechanism of leptin in regulating insulin secretion.

  15. Pinitol Supplementation Does Not Affect Insulin-Mediated Glucose Metabolism and Muscle Insulin Receptor Content and Phosphorylation in Older Humans12

    OpenAIRE

    Campbell, Wayne W.; Haub, Mark D.; Fluckey, James D.; Ostlund, Richard E.; Thyfault, John P.; Morse-Carrithers, Hannah; Hulver, Matthew W.; Birge, Zonda K.

    2004-01-01

    This study assessed the effect of oral pinitol supplementation on oral and intravenous glucose tolerances and on skeletal muscle insulin receptor content and phosphorylation in older people. Fifteen people (6 men, 9 women; age 66 ± 8 y; BMI 27.9 ± 3.3 kg/m2; hemoglobin A1c 5.39 ± 0.46%, mean ± SD) completed a 7-wk protocol. Subjects were randomly assigned to groups that during wk 2−7 consumed twice daily either a non-nutritive beverage (Placebo group, n = 8) or the same beverage with 1000 mg ...

  16. Targeting colorectal cancer via its microenvironment by inhibiting IGF-1 Receptor-insulin receptor substrate and STAT3 signaling

    Science.gov (United States)

    Sanchez-Lopez, Elsa; Flashner-Abramson, Efrat; Shalapour, Shabnam; Zhong, Zhenyu; Taniguchi, Koji; Levitzki, Alexander; Karin, Michael

    2015-01-01

    The tumor microenvironment (TME) exerts critical pro-tumorigenic effects through cytokines and growth factors that support cancer cell proliferation, survival, motility and invasion. Insulin-like growth factor-1 (IGF-1) and Signal transducer and activator of transcription 3 (STAT3) stimulate colorectal cancer (CRC) development and progression via cell autonomous and microenvironmental effects. Using a unique inhibitor, NT157, which targets both IGF-1 receptor (IGF-1R) and STAT3, we show that these pathways regulate many TME functions associated with sporadic colonic tumorigenesis in CPC-APC mice, in which cancer development is driven by loss of the Apc tumor suppressor gene. NT157 causes a substantial reduction in tumor burden by affecting cancer cells, cancer-associated fibroblasts (CAF) and myeloid cells. Decreased cancer cell proliferation and increased apoptosis were accompanied by inhibition of CAF activation and decreased inflammation. Furthermore, NT157 inhibited expression of pro-tumorigenic cytokines, chemokines and growth factors, including IL-6, IL-11 and IL-23 as well as CCL2, CCL5, CXCL7, CXCL5, ICAM1 and TGFβ; decreased cancer cell migratory activity and reduced their proliferation in the liver. NT157 represents a new class of anti-cancer drugs that affect both the malignant cell and its supportive microenvironment. PMID:26364612

  17. Venus Kinase Receptors at the crossroads of insulin signaling: their role in reproduction for helminths and insects

    Directory of Open Access Journals (Sweden)

    Colette eDissous

    2015-08-01

    Full Text Available Venus kinase receptors (VKRs are invertebrate receptor tyrosine kinases (RTKs first discovered in the human parasite Schistosoma. They contain an extracellular Venus FlyTrap (VFT module similar to the ligand-binding domain of G protein-coupled receptors of class C and an intracellular tyrosine kinase domain similar to that of insulin receptors. VKRs are present from cnidarians to echinoderms. They were shown to be activated by amino-acids, to induce insulin-like intracellular pathways and to be highly expressed in larvae and in gonads of helminths and insects. The function of VKR in gametogenesis was demonstrated in schistosomes by VKR silencing and recent studies in Aedes aegypti have confirmed the importance of VKR in mosquito egg formation. AaeVKR was shown to bind to ovary ecdysteroidogenic hormone (OEH and to activate the production of ecdysteroids by the ovary, independently of signaling mediated by insulin-like peptides. These new data confirm and specify the function of VKRs in the reproduction of helminths and insects and they open interesting perspectives for elucidating the role of VKRs in other models. VKR targeting would also provide opportunities for the control of parasites and various vector-borne diseases.

  18. Venus Kinase Receptors at the Crossroads of Insulin Signaling: Their Role in Reproduction for Helminths and Insects.

    Science.gov (United States)

    Dissous, Colette

    2015-01-01

    Venus kinase receptors (VKRs) are invertebrate receptor tyrosine kinases (TKs) first discovered in the human parasite Schistosoma. They contain an extracellular Venus FlyTrap module similar to the ligand-binding domain of G protein-coupled receptors of class C and an intracellular TK domain similar to that of insulin receptors. VKRs are present from cnidarians to echinoderms. They were shown to be activated by amino-acids, to induce insulin-like intracellular pathways, and to be highly expressed in larvae and in gonads of helminths and insects. The function of VKR in gametogenesis was demonstrated in schistosomes by VKR silencing and recent studies in Aedes aegypti have confirmed the importance of VKR in mosquito egg formation. AaeVKR was shown to bind to ovary ecdysteroidogenic hormone and to activate the production of ecdysteroids by the ovary, independently of signaling mediated by insulin-like peptides. These new data confirm and specify the function of VKRs in the reproduction of helminths and insects and they open interesting perspectives for elucidating the role of VKRs in other models. VKR targeting would also provide opportunities for the control of parasites and various vector-borne infectious diseases.

  19. The insulin receptor substrate 1 (IRS1 in intestinal epithelial differentiation and in colorectal cancer.

    Directory of Open Access Journals (Sweden)

    Diana L Esposito

    Full Text Available Colorectal cancer (CRC is associated with lifestyle factors that affect insulin/IGF signaling, of which the insulin receptor substrate 1 (IRS1 is a key transducer. We investigated expression, localization and pathologic correlations of IRS1 in cancer-uninvolved colonic epithelium, primary CRCs with paired liver metastases and in vitro polarizing Caco2 and HT29 cells. IRS1 mRNA and protein resulted higher, relative to paired mucosa, in adenomas of familial adenomatous polyposis patients and in CRCs that overexpressed c-MYC, ß-catenin, InsRß, and IGF1R. Analysis of IRS1 immunostaining in 24 cases of primary CRC with paired colonic epithelium and hepatic metastasis showed that staining intensity was significantly higher in metastases relative to both primary CRC (P<0.01 and colonic epithelium (P<0.01. Primary and metastatic CRCs, compared to colonic epithelium, contained significantly higher numbers of IRS1-positive cells (P = 0.013 and P = 0.014, respectively. Pathologic correlations in 163 primary CRCs revealed that diffuse IRS1 staining was associated with tumors combining differentiated phenotype and aggressive markers (high Ki67, p53, and ß-catenin. In Caco 2 IRS1 and InsR were maximally expressed after polarization, while IGF1R was highest in pre-polarized cells. No nuclear IRS1 was detected, while, with polarization, phosphorylated IRS1 (pIRS1 shifted from the lateral to the apical plasma membrane and was expressed in surface cells only. In HT29, that carry mutations constitutively activating survival signaling, IRS1 and IGF1R decreased with polarization, while pIRS1 localized in nuclear spots throughout the course. Overall, these data provide evidence that IRS1 is modulated according to CRC differentiation, and support a role of IRS1 in CRC progression and liver metastatization.

  20. Insulin-increased L-arginine transport requires A(2A adenosine receptors activation in human umbilical vein endothelium.

    Directory of Open Access Journals (Sweden)

    Enrique Guzmán-Gutiérrez

    Full Text Available Adenosine causes vasodilation of human placenta vasculature by increasing the transport of arginine via cationic amino acid transporters 1 (hCAT-1. This process involves the activation of A(2A adenosine receptors (A(2AAR in human umbilical vein endothelial cells (HUVECs. Insulin increases hCAT-1 activity and expression in HUVECs, and A(2AAR stimulation increases insulin sensitivity in subjects with insulin resistance. However, whether A(2AAR plays a role in insulin-mediated increase in L-arginine transport in HUVECs is unknown. To determine this, we first assayed the kinetics of saturable L-arginine transport (1 minute, 37°C in the absence or presence of nitrobenzylthioinosine (NBTI, 10 µmol/L, adenosine transport inhibitor and/or adenosine receptors agonist/antagonists. We also determined hCAT-1 protein and mRNA expression levels (Western blots and quantitative PCR, and SLC7A1 (for hCAT-1 reporter promoter activity. Insulin and NBTI increased the extracellular adenosine concentration, the maximal velocity for L-arginine transport without altering the apparent K(m for L-arginine transport, hCAT-1 protein and mRNA expression levels, and SLC7A1 transcriptional activity. An A2AAR antagonist ZM-241385 blocked these effects. ZM241385 inhibited SLC7A1 reporter transcriptional activity to the same extent in cells transfected with pGL3-hCAT-1(-1606 or pGL3-hCAT-1(-650 constructs in the presence of NBTI + insulin. However, SLC7A1 reporter activity was increased by NBTI only in cells transfected with pGL3-hCAT-1(-1606, and the ZM-241385 sensitive fraction of the NBTI response was similar in the absence or in the presence of insulin. Thus, insulin modulation of hCAT-1 expression and activity requires functional A(2AAR in HUVECs, a mechanism that may be applicable to diseases associated with fetal insulin resistance, such as gestational diabetes.

  1. CCR2 knockout exacerbates cerulein-induced chronic pancreatitis with hyperglycemia via decreased GLP-1 receptor expression and insulin secretion.

    Science.gov (United States)

    Nakamura, Yuji; Kanai, Takanori; Saeki, Keita; Takabe, Miho; Irie, Junichiro; Miyoshi, Jun; Mikami, Yohei; Teratani, Toshiaki; Suzuki, Takahiro; Miyata, Naoteru; Hisamatsu, Tadakazu; Nakamoto, Nobuhiro; Yamagishi, Yoshiyuki; Higuchi, Hajime; Ebinuma, Hirotoshi; Hozawa, Shigenari; Saito, Hidetsugu; Itoh, Hiroshi; Hibi, Toshifumi

    2013-04-15

    Glucagon-like peptide-1 (GLP-1) promotes insulin release; however, the relationship between the GLP-1 signal and chronic pancreatitis is not well understood. Here we focus on chemokine (C-C motif) ligand 2 (CCL2) and its receptor (CCR2) axis, which regulates various immune cells, including macrophages, to clarify the mechanism of GLP-1-mediated insulin secretion in chronic pancreatitis in mice. One and multiple series of repetitive cerulein administrations were used to induce acute and chronic cerulein pancreatitis, respectively. Acute cerulein-administered CCR2-knockout (KO) mice showed suppressed infiltration of CD11b(+)Gr-1(low) macrophages and pancreatic inflammation and significantly upregulated insulin secretion compared with paired wild-type (WT) mice. However, chronic cerulein-administered CCR2-KO mice showed significantly increased infiltration of CD11b(+)/Gr-1(-) and CD11b(+)/Gr-1(high) cells, but not CD11b(+)/Gr-1(low) cells, in pancreas with severe inflammation and significantly decreased insulin secretion compared with their WT counterparts. Furthermore, although serum GLP-1 levels in chronic cerulein-administered WT and CCR2-KO mice were comparably upregulated after cerulein administrations, GLP-1 receptor levels in pancreases of chronic cerulein-administered CCR2-KO mice were significantly lower than in paired WT mice. Nevertheless, a significantly higher hyperglycemia level in chronic cerulein-administered CCR2-KO mice was markedly restored by treatment with a GLP-1 analog to a level comparable to the paired WT mice. Collectively, the CCR2/CCL2 axis-mediated CD11b(+)-cell migration to the pancreas is critically involved in chronic pancreatitis-mediated hyperglycemia through the modulation of GLP-1 receptor expression and insulin secretion.

  2. Deficiency of the leukotriene B4 receptor, BLT-1, protects against systemic insulin resistance in diet-induced obesity.

    Science.gov (United States)

    Spite, Matthew; Hellmann, Jason; Tang, Yunan; Mathis, Steven P; Kosuri, Madhavi; Bhatnagar, Aruni; Jala, Venkatakrishna R; Haribabu, Bodduluri

    2011-08-15

    Chronic inflammation is an underlying factor linking obesity with insulin resistance. Diet-induced obesity promotes an increase in circulating levels of inflammatory monocytes and their infiltration into expanding adipose tissue. Nevertheless, the endogenous pathways that trigger and sustain chronic low-grade inflammation in obesity are incompletely understood. In this study, we report that a high-fat diet selectively increases the circulating levels of CD11b(+) monocytes in wild-type mice that express leukotriene B(4) receptor, BLT-1, and that this increase is abolished in BLT-1-null mice. The accumulation of classically activated (M1) adipose tissue macrophages (ATMs) and the expression of proinflammatory cytokines and chemokines (i.e., IL-6 and Ccl2) was largely blunted in adipose tissue of obese BLT-1(-/-) mice, whereas the ratio of alternatively activated (M2) ATMs to M1 ATMs was increased. Obese BLT-1(-/-) mice were protected from systemic glucose and insulin intolerance and this was associated with a decrease in inflammation in adipose tissue and liver and a decrease in hepatic triglyceride accumulation. Deletion of BLT-1 prevented high fat-induced loss of insulin signaling in liver and skeletal muscle. These observations elucidate a novel role of chemoattractant receptor, BLT-1, in promoting monocyte trafficking to adipose tissue and promoting chronic inflammation in obesity and could lead to the identification of new therapeutic targets for treating insulin resistance in obesity.

  3. Inhibition of sweet chemosensory receptors alters insulin responses during glucose ingestion in healthy adults: a randomized crossover interventional study.

    Science.gov (United States)

    Karimian Azari, Elnaz; Smith, Kathleen R; Yi, Fanchao; Osborne, Timothy F; Bizzotto, Roberto; Mari, Andrea; Pratley, Richard E; Kyriazis, George A

    2017-04-01

    Background: Glucose is a natural ligand for sweet taste receptors (STRs) that are expressed on the tongue and in the gastrointestinal tract. Whether STRs directly contribute to the regulation of glucose homeostasis in response to glucose ingestion is unclear.Objective: We sought to determine the metabolic effects of the pharmacologic inhibition of STRs in response to an oral glucose load in healthy lean participants.Design: Ten healthy lean participants with a body mass index (in kg/m(2)) of 22.4 ± 0.8 were subjected to an oral-glucose-tolerance test (OGTT) on 4 separate days with the use of a randomized crossover design. Ten minutes before the 75-g OGTT, participants consumed a preload solution of either 300 parts per million (ppm) saccharin or water with or without the addition of 500 ppm lactisole, a human-specific inhibitor of STRs. When present, lactisole was included in both the preload and OGTT solutions. We assessed plasma responses of glucose, insulin, C-peptide, glucagon, glucagon-like peptides 1 and 2, gastric inhibitory peptide, acetaminophen, and 3-O-methylglucose. With the use of mathematical modeling, we estimated gastric emptying, glucose absorption, β-cell function, insulin sensitivity and clearance, and the portal insulin:glucagon ratio.Results: The addition of lactisole to the OGTT caused increases in the plasma responses of insulin (P = 0.012), C-peptide (P = 0.004), and the insulin secretory rate (P = 0.020) compared with the control OGTT. The addition of lactisole also caused a slight reduction in the insulin sensitivity index independent of prior saccharin consumption (P insulin responses during an oral glucose challenge in lean healthy participants. This trial was registered at clinicaltrials.gov as NCT02835859. © 2017 American Society for Nutrition.

  4. Insulin resistance and increased lipolysis in bone marrow derived adipocytes stimulated with agonists of Toll-like receptors.

    Science.gov (United States)

    Franchini, M; Monnais, E; Seboek, D; Radimerski, T; Zini, E; Kaufmann, K; Lutz, T; Reusch, C; Ackermann, M; Muller, B; Linscheid, P

    2010-09-01

    Our objectives were to identify Toll-like receptors (TLRs) in human bone marrow derived adipocytes, to test specific TLR agonists for their ability to induce a proinflammatory response, and to investigate possible metabolic effects after TLR activation, in particular, those associated with insulin resistance and lipolysis. Mesenchymal stem cells were isolated from human bone marrow and differentiated into adipocytes. Total RNA before or after stimulation with agonists specific for TLR was extracted for analysis of expression of TLRs proinflammatory signals and molecules involved in glucose metabolism (IRS-1 and GLUT4). Furthermore, cytokine protein expression was measured from cell lysates. Finally, insulin induced glucose uptake and lipolysis were measured. Human bone marrow-derived adipocytes express TLR1-10. They react to stimulation with specific ligands with expression of inflammatory markers (IL-1beta, IL-6, TNFalpha, IL-8, MCP-1) at the RNA and protein levels. IRS-1 and GLUT4 expression was downregulated after stimulation with the TLR4 and TLR3 specific ligands LPS and poly (I:C), respectively. Insulin-induced glucose uptake was decreased and lipolysis increased. We conclude that adipocytes express TLR 1-10 and react to agonists specific for TLR 1-6. As a consequence proinflammatory cytokine are induced, in particular, IL-6, IL-8, and MCP-1. Since stimulation is followed by decreased insulin-induced glucose uptake and increased lipolysis we conclude that TLRs may be important linking molecules in the generation of insulin resistance in fat tissue.

  5. Suppression of the Insulin Receptors in Adult Schistosoma japonicum Impacts on Parasite Growth and Development: Further Evidence of Vaccine Potential.

    Science.gov (United States)

    You, Hong; Gobert, Geoffrey N; Cai, Pengfei; Mou, Rong; Nawaratna, Sujeevi; Fang, Guofu; Villinger, Francois; McManus, Donald P

    2015-05-01

    To further investigate the importance of insulin signaling in the growth, development, sexual maturation and egg production of adult schistosomes, we have focused attention on the insulin receptors (SjIRs) of Schistosoma japonicum, which we have previously cloned and partially characterised. We now show, by Biolayer Interferometry, that human insulin can bind the L1 subdomain (insulin binding domain) of recombinant (r)SjIR1 and rSjIR2 (designated SjLD1 and SjLD2) produced using the Drosophila S2 protein expression system. We have then used RNA interference (RNAi) to knock down the expression of the SjIRs in adult S. japonicum in vitro and show that, in addition to their reduced transcription, the transcript levels of other important downstream genes within the insulin pathway, associated with glucose metabolism and schistosome fecundity, were also impacted substantially. Further, a significant decrease in glucose uptake was observed in the SjIR-knockdown worms compared with luciferase controls. In vaccine/challenge experiments, we found that rSjLD1 and rSjLD2 depressed female growth, intestinal granuloma density and faecal egg production in S. japonicum in mice presented with a low dose challenge infection. These data re-emphasize the potential of the SjIRs as veterinary transmission blocking vaccine candidates against zoonotic schistosomiasis japonica in China and the Philippines.

  6. (Pro)renin receptor and insulin resistance: possible roles of angiotensin II-dependent and -independent pathways.

    Science.gov (United States)

    Rafiq, Kazi; Mori, Hirohito; Masaki, Tsutomu; Nishiyama, Akira

    2013-09-25

    A growing body of evidence has suggested the potential role of (pro)renin receptor [(P)RR] in the pathogenesis of cardiovascular and renal injuries during the development of hypertension and diabetes. However, there is very little information on the contribution of (P)RR to the pathophysiology of insulin resistance. In this regard, our preliminary data showed that the development of insulin resistance was associated with nonproteolytic activation of prorenin as well as local angiotensin II generation in skeletal muscle and adipose tissues of obese Otsuka Long-Evans Tokushima Fatty rats. In fructose-fed rats, insulin resistance was also associated with nonproteolytic activation of prorenin and skeletal muscle angiotensin II generation. Furthermore, inhibition of (P)RR with handle region decoy peptide (HRP) improved the development of fructose-induced insulin resistance. However, in other animal model, such as transgenic rats overexpressing the human renin gene, HRP failed to ameliorate glucose intolerance. In this review, we will summarized the current knowledge regarding the possible contribution of (P)RR to the pathophysiology of insulin resistance.

  7. Transient receptor potential vanilloid type-1 channel regulates diet-induced obesity, insulin resistance, and leptin resistance.

    Science.gov (United States)

    Lee, Eunjung; Jung, Dae Young; Kim, Jong Hun; Patel, Payal R; Hu, Xiaodi; Lee, Yongjin; Azuma, Yoshihiro; Wang, Hsun-Fan; Tsitsilianos, Nicholas; Shafiq, Umber; Kwon, Jung Yeon; Lee, Hyong Joo; Lee, Ki Won; Kim, Jason K

    2015-08-01

    Insulin resistance is a major characteristic of obesity and type 2 diabetes, but the underlying mechanism is unclear. Recent studies have shown a metabolic role of capsaicin that may be mediated via the transient receptor potential vanilloid type-1 (TRPV1) channel. In this study, TRPV1 knockout (KO) and wild-type (WT) mice (as controls) were fed a high-fat diet (HFD), and metabolic studies were performed to measure insulin and leptin action. The TRPV1 KO mice became more obese than the WT mice after HFD, partly attributed to altered energy balance and leptin resistance in the KO mice. The hyperinsulinemic-euglycemic clamp experiment showed that the TRPV1 KO mice were more insulin resistant after HFD because of the ∼40% reduction in glucose metabolism in the white and brown adipose tissue, compared with that in the WT mice. Leptin treatment failed to suppress food intake, and leptin-mediated hypothalamic signal transducer and activator of transcription (STAT)-3 activity was blunted in the TRPV1 KO mice. We also found that the TRPV1 KO mice were more obese and insulin resistant than the WT mice at 9 mo of age. Taken together, these results indicate that lacking TRPV1 exacerbates the obesity and insulin resistance associated with an HFD and aging, and our findings further suggest that TRPV1 has a major role in regulating glucose metabolism and hypothalamic leptin's effects in obesity. © FASEB.

  8. Obesity-induced infertility and hyperandrogenism are corrected by deletion of the insulin receptor in the ovarian theca cell.

    Science.gov (United States)

    Wu, Sheng; Divall, Sara; Nwaopara, Amanda; Radovick, Sally; Wondisford, Fredric; Ko, Chemyong; Wolfe, Andrew

    2014-04-01

    Women with polycystic ovary syndrome (PCOS) exhibit elevated androgen levels, oligoanovulation, infertility, and insulin resistance in metabolic tissues. The aims of these studies were to determine the role of insulin signaling in the development and function of ovarian theca cells and the pathophysiologic effects of hyperinsulinism on ovarian function in obesity. We disrupted the insulin receptor (IR) gene specifically in the theca-interstitial (TI) cells of the ovaries (Cyp17IRKO). No changes in reproductive development or function were observed in lean Cyp17IRKO female mice, suggesting that insulin signaling in TI cell is not essential for reproduction. However, when females were fed a high-fat diet, diet-induced obesity (DIO) wild-type (DIO-WT) mice were infertile and experienced increased circulating testosterone levels, whereas DIO-Cyp17IRKO mice exhibited improved fertility and testosterone levels comparable to those found in lean mice. The levels of phosphorylated IRS1 and CYP17 protein were higher in the ovary of DIO-WT compared with DIO-Cyp17IRKO or lean mice. Ex vivo studies using a whole ovary culture model demonstrated that insulin acts independently or additively with human chorionic gonadotropin to enhance androstenedione secretion. These studies reveal the causal pathway linking hyperinsulinism with ovarian hyperandrogenism and the infertility of obesity.

  9. Extension of Drosophila lifespan by cinnamon through a sex-specific dependence on the insulin receptor substrate chico.

    Science.gov (United States)

    Schriner, Samuel E; Kuramada, Steven; Lopez, Terry E; Truong, Stephanie; Pham, Andrew; Jafari, Mahtab

    2014-12-01

    Cinnamon is a spice commonly used worldwide to flavor desserts, fruits, cereals, breads, and meats. Numerous health benefits have been attributed to its consumption, including the recent suggestion that it may decrease blood glucose levels in people with diabetes. Insulin signaling is an integral pathway regulating the lifespan of laboratory organisms, such as worms, flies, and mice. We posited that if cinnamon truly improved the clinical signs of diabetes in people that it would also act on insulin signaling in laboratory organisms and increase lifespan. We found that cinnamon did extend lifespan in the fruit fly, Drosophila melanogaster. However, it had no effect on the expression levels of the 3 aging-related Drosophila insulin-like peptides nor did it alter sugar, fat, or soluble protein levels, as would be predicted. In addition, cinnamon exhibited no protective effects in males against oxidative challenges. However, in females it did confer a protective effect against paraquat, but sensitized them to iron. Cinnamon provided no protective effect against desiccation and starvation in females, but sensitized males to both. Interestingly, cinnamon protected both sexes against cold, sensitized both to heat, and elevated HSP70 expression levels. We also found that cinnamon required the insulin receptor substrate to extend lifespan in males, but not females. We conclude that cinnamon does not extend lifespan by improving stress tolerance in general, though it does act, at least in part, through insulin signaling.

  10. Impact of the 5-HT3 receptor channel system for insulin secretion and interaction of ginger extracts.

    Science.gov (United States)

    Heimes, Katharina; Feistel, Björn; Verspohl, Eugen J

    2009-12-10

    The relevance of serotonin and in particular that of 5-HT(3) receptors is unequivocal with respect to emetic/antiemetic effects, but it is controversial with respect to antidiabetic effects. The effects of tropisetron (5-HT(3) receptor antagonist) and various ginger (Zingiber officinale) extracts (known to interact with the 5-HT(3) receptor channel system) were investigated. Serotonin (32 to 500 microM) inhibits insulin release (RIA) from INS-1 cells which is reversed by tropisetron (10 to 100 microM) and two different ginger extracts (spissum and an oily extract). Their effects are obvious even in the absence of serotonin but are more pronounced in its presence (doubled to tripled). Specific 5-HT(3) binding sites are present in INS-1 cells using 0.4 nM [3H] GR65630 in displacement experiments. The in vitro data with respect to ginger are corroborated by in vivo data on glucose-loaded rats showing that blood glucose (Glucoquant) is decreased by approximately 35% and plasma insulin (RIA) is increased by approximately 10%. Both the spissum extract and the oily ginger extract are effective in two other models: they inhibit [(14)C] guanidinium uptake into N1E-115 cells (model of 5-HT(3) effects) and relax rat ileum both directly and as a serotonin antagonistic effect. Other receptors addressed by ginger are 5-HT(2) receptors as demonstrated by using methysergide and ketanserin. They weakly antagonize the serotonin effect as well. It may be concluded that serotonin and in particular the 5-HT(3) receptor channel system are involved in modulating insulin release and that tropisetron and various ginger extracts can be used to improve a diabetic situation.

  11. Insulin-like growth factor II mRNA, peptides, and receptors in a thoracopulmonary malignant small round cell tumor

    DEFF Research Database (Denmark)

    Nielsen, F C; Orskov, C; Haselbacher, G;

    1994-01-01

    Insulin-like growth factor-(IGF) II and IGF-I and IGF-II/mannose 6-phosphate receptors were expressed in a thoracopulmonary malignant small round cell tumor (MSRCT) from a 14-year-old boy. Northern analysis showed that the MSRCT expresses multiple IGF-II mRNA of 6.0, 4.8, 4.2, and 2.2 kilobase from...

  12. Insulin like growth factor 2 regulation of aryl hydrocarbon receptor in MCF-7 breast cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Tomblin, Justin K.; Salisbury, Travis B., E-mail: salisburyt@marshall.edu

    2014-01-17

    Highlights: •IGF-2 stimulates concurrent increases in AHR and CCND1 expression. •IGF-2 promotes the binding of AHR to the endogenous cyclin D1 promoter. •AHR knockdown inhibits IGF-2 stimulated increases in CCND1 mRNA and protein. •AHR knockdown inhibits IGF-2 stimulated increases in MCF-7 proliferation. -- Abstract: Insulin like growth factor (IGF)-1 and IGF-2 stimulate normal growth, development and breast cancer cell proliferation. Cyclin D1 (CCND1) promotes cell cycle by inhibiting retinoblastoma protein (RB1). The aryl hydrocarbon receptor (AHR) is a major xenobiotic receptor that also regulates cell cycle. The purpose of this study was to investigate whether IGF-2 promotes MCF-7 breast cancer proliferation by inducing AHR. Western blot and quantitative real time PCR (Q-PCR) analysis revealed that IGF-2 induced an approximately 2-fold increase (P < .001) in the expression of AHR and CCND1. Chromatin immunoprecipitation (ChIP), followed by Q-PCR indicated that IGF-2 promoted (P < .001) a 7-fold increase in AHR binding on the CCND1 promoter. AHR knockdown significantly (P < .001) inhibited IGF-2 stimulated increases in CCND1 mRNA and protein. AHR knockdown cells were less (P < .001) responsive to the proliferative effects of IGF-2 than control cells. Collectively, our findings have revealed a new regulatory mechanism by which IGF-2 induction of AHR promotes the expression of CCND1 and the proliferation of MCF-7 cells. This previously uncharacterized pathway could be important for the proliferation of IGF responsive cancer cells that also express AHR.

  13. Green tea (-)-epigallocatechin gallate inhibits insulin stimulation of 3T3-L1 preadipocyte mitogenesis via the 67-kDa laminin receptor pathway.

    Science.gov (United States)

    Ku, Hui-Chen; Chang, Hsin-Huei; Liu, Hsien-Chun; Hsiao, Chiao-Hsin; Lee, Meng-Jung; Hu, Yu-Jung; Hung, Pei-Fang; Liu, Chi-Wei; Kao, Yung-Hsi

    2009-07-01

    Insulin and (-)-epigallocatechin gallate (EGCG) have been reported to regulate fat cell mitogenesis and adipogenesis, respectively. This study investigated the pathways involved in EGCG modulation of insulin-stimulated mitogenesis in 3T3-L1 preadipocytes. EGCG inhibited insulin stimulation of preadipocyte proliferation in a dose- and time-dependent manner. EGCG also suppressed insulin-stimulated phosphorylation of the insulin receptor-beta, insulin receptor (IR) substrates 1 and 2 (IRS1 and IRS2), and mitogen-activated protein kinase pathway proteins, RAF1, MEK1/2, and ERK1/2, but not JNK. Furthermore, EGCG inhibited the association of IR with the IRS1 and IRS2 proteins, but not with the IRS4 protein. These data suggest that EGCG selectively affects particular types of IRS and MAPK family members. Generally, EGCG was more effective than epicatechin, epicatechin gallate, and epigallocatechin in modulating insulin-stimulated mitogenic signaling. We identified the EGCG receptor [also known as the 67-kDa laminin receptor (67LR)] in fat cells and found that its expression was sensitive to growth phase, tissue type, and differentiation state. Pretreatment of preadipocytes with 67LR antiserum prevented the effects of EGCG on insulin-stimulated phosphorylation of IRS2, RAF1, and ERK1/2 and insulin-stimulated preadipocyte proliferation (cell number and bromodeoxyuridine incorporation). Moreover, EGCG tended to increase insulin-stimulated associations between the 67LR and IR, IRS1, IRS2, and IRS4 proteins. These data suggest that EGCG mediates anti-insulin signaling in preadipocyte mitogenesis via the 67LR pathway.

  14. Synthesis and Evaluation of a Library of Trifunctional Scaffold-Derived Compounds as Modulators of the Insulin Receptor.

    Science.gov (United States)

    Fabre, Benjamin; Pícha, Jan; Vaněk, Václav; Selicharová, Irena; Chrudinová, Martina; Collinsová, Michaela; Žáková, Lenka; Buděšínský, Miloš; Jiráček, Jiří

    2016-12-12

    We designed a combinatorial library of trifunctional scaffold-derived compounds, which were derivatized with 30 different in-house-made azides. The compounds were proposed to mimic insulin receptor (IR)-binding epitopes in the insulin molecule and bind to and activate this receptor. This work has enabled us to test our synthetic and biological methodology and to prove its robustness and reliability for the solid-phase synthesis and testing of combinatorial libraries of the trifunctional scaffold-derived compounds. Our effort resulted in the discovery of two compounds, which were able to weakly induce the autophosphorylation of IR and weakly bind to this receptor at a 0.1 mM concentration. Despite these modest biological results, which well document the well-known difficulty in modulating protein-protein interactions, this study represents a unique example of targeting the IR with a set of nonpeptide compounds that were specifically designed and synthesized for this purpose. We believe that this work can open new perspectives for the development of next-generation insulin mimetics based on the scaffold structure.

  15. Quercetin ameliorates chronic unpredicted stress-mediated memory dysfunction in male Swiss albino mice by attenuating insulin resistance and elevating hippocampal GLUT4 levels independent of insulin receptor expression.

    Science.gov (United States)

    Mehta, Vineet; Parashar, Arun; Sharma, Arun; Singh, Tiratha Raj; Udayabanu, Malairaman

    2017-03-01

    Chronic stress is associated with impaired neuronal functioning, altered insulin signaling, and behavioral dysfunction. Quercetin has shown neuroprotective and antidiabetic effects, besides modulating cognition and insulin signaling. Therefore, in the present study, we explored whether or not quercetin ameliorates stress-mediated cognitive dysfunction and explored the underlying mechanism. Swiss albino male mice were subjected to an array of unpredicted stressors for 21days, during which 30mg/kg quercetin treatment was given orally. The effect of chronic unpredicted stress (CUS) and quercetin treatment on cognition were evaluated using novel object recognition (NOR) and Morris water maze (MWM) tests. Hippocampal neuronal integrity was observed by histopathological examination. Blood glucose, serum corticosterone, and insulin levels were measured by commercial kits and insulin resistance was evaluated in terms of HOMA-IR index. Hippocampal insulin signaling was determined by immunofluorescence staining. CUS induced significant cognitive dysfunction (NOR and MWM) and severely damaged hippocampal neurons, especially in the CA3 region. Quercetin treatment alleviated memory dysfunction and rescued neurons from CUS-mediated damage. Fasting blood glucose, serum corticosterone, and serum insulin were significantly elevated in stressed animals, besides, having significantly higher HOMA-IR index, suggesting the development of insulin resistance. Quercetin treatment alleviated insulin resistance and attenuated altered biochemical parameters. CUS markedly down-regulated insulin signaling in CA3 region and quercetin treatment improved neuronal GLUT4 expression, which seemed to be independent of insulin and insulin receptor levels. These results suggest that intact insulin functioning in the hippocampus is essential for cognitive functions and quercetin improves CUS-mediated cognitive dysfunction by modulating hippocampal insulin signaling. Copyright © 2016 Elsevier Inc. All

  16. The insulin-like growth factor I receptor regulates glucose transport by astrocytes.

    Science.gov (United States)

    Hernandez-Garzón, Edwin; Fernandez, Ana M; Perez-Alvarez, Alberto; Genis, Laura; Bascuñana, Pablo; Fernandez de la Rosa, Ruben; Delgado, Mercedes; Angel Pozo, Miguel; Moreno, Estefania; McCormick, Peter J; Santi, Andrea; Trueba-Saiz, Angel; Garcia-Caceres, Cristina; Tschöp, Matthias H; Araque, Alfonso; Martin, Eduardo D; Torres Aleman, Ignacio

    2016-11-01

    Previous findings indicate that reducing brain insulin-like growth factor I receptor (IGF-IR) activity promotes ample neuroprotection. We now examined a possible action of IGF-IR on brain glucose transport to explain its wide protective activity, as energy availability is crucial for healthy tissue function. Using (18) FGlucose PET we found that shRNA interference of IGF-IR in mouse somatosensory cortex significantly increased glucose uptake upon sensory stimulation. In vivo microscopy using astrocyte specific staining showed that after IGF-IR shRNA injection in somatosensory cortex, astrocytes displayed greater increases in glucose uptake as compared to astrocytes in the scramble-injected side. Further, mice with the IGF-IR knock down in astrocytes showed increased glucose uptake in somatosensory cortex upon sensory stimulation. Analysis of underlying mechanisms indicated that IGF-IR interacts with glucose transporter 1 (GLUT1), the main facilitative glucose transporter in astrocytes, through a mechanism involving interactions with the scaffolding protein GIPC and the multicargo transporter LRP1 to retain GLUT1 inside the cell. These findings identify IGF-IR as a key modulator of brain glucose metabolism through its inhibitory action on astrocytic GLUT1 activity. GLIA 2016;64:1962-1971.

  17. Immunohistochemical Evaluation of Insulin-like Growth Factor I Receptor Status in Cervical Cancer Specimens

    Directory of Open Access Journals (Sweden)

    Nakamura,Keiichiro

    2008-08-01

    Full Text Available The insulin-like growth factor I receptor (IGF-IR is exceptionally overexpressed in many cervicalcancer-derived cell lines. It is postulated that a decrease of p53 protein levels due to human papillomavirus (HPV infection may contribute to the up-regulation of IGF-IR expression in cervical cancer cells because transcription of IGF-IR is strictly down-regulated by p53. To evaluate this fact in clinical cervical cancer specimens, we checked the expression levels and activated status of IGF-IR by immunohistochemistry. Formalin-fixed and paraffin-embedded specimens obtained by conization or hysterectomy were stained with anti-IGF-IR and with an antibody recognizing phosphorylated tyrosine at its c-terminus. The expression levels of IGF-IR were significantly high in cervical intraepithelial neoplasia (CIN III and invasive cancer specimens. Phosphorylation of IGF-IR was promoted in all CIN and invasive cancer specimens, and its intensity was related to the promotion of lesions. Interestingly, IGF-IR overexpression was missing in the basal layer of CIN I and II lesions, whereas it was evenly distributed in CIN III and invasive cancer lesions. This IGF-IR overexpression pattern may be utilized in the diagnosis of HPV infection status in CIN lesions.

  18. The Relationship of Insulin-receptor Gene Polymorphism to Ischemic Stroke?

    Institute of Scientific and Technical Information of China (English)

    张颖冬; 石铸; 刘阳

    2002-01-01

    Objective To investigate the role of mutation of insulin-receptor ( INSR ) gene in the development of ischemic stroke. Methods The base-variations at exoa 17 and 20 of INSR gene, by means of PCR-SSCP were determined in 68 cases of atherothrombotic cerebral infarction (ACI), 81 cases of lacunar infarction (LI) and 62 healthy controls (HC). Results There were 2 alleles of T and C at exoa 17 of INSR gene. The prevalence of mutant of T allele in ACI patients was more common than that in the controls. The blood pressure and the parameters of lipid metabolism in the patients with mutant were higher than those in the controls with wild-type gene. However, the correlative analysis showed that the polymorphism of INSR gene was not related statistically to the blood pressure. No base-variation at exon 20 was found in the study. Conclusion The mutation at exon 17 of INSR gene, by promoting the development of atherosclerosis, may participate in the occurrence of ischemic stroke.

  19. Rosiglitazone treatment of patients with extreme insulin resistance and diabetes mellitus due to insulin receptor mutations has no effects on glucose and lipid metabolism

    DEFF Research Database (Denmark)

    Vestergaard, H; Lund, S; Pedersen, O;

    2001-01-01

    Rosiglitazone, a thiazolidinedione (TZD), increases insulin sensitivity by reducing levels of plasma NEFA, triglycerides (TG), glucose and serum insulin. Rosiglitazone treatment decreases insulin resistance in type 2 diabetic patients, but no data exist concerning rosiglitazone treatment of patie...

  20. The dog as a naturally-occurring model for insulin-like growth factor type 1 receptor-overexpressing breast cancer: an observational cohort study

    OpenAIRE

    Jaillardon, Laetitia; Abadie, Jérome; Godard, Tiffanie; Campone, Mario; Loussouarn, Delphine; Siliart, Brigitte; Nguyen, Frédérique

    2015-01-01

    Background Dogs spontaneously develop invasive mammary carcinoma with a high prevalence of the triple-negative (TN) subtype (lack of ER-Estrogen Receptor and PR-Progesterone Receptor expression, lack of HER2-Human Epidermal Growth Factor Receptor 2 overexpression), making this animal model relevant for investigating new therapeutic pathways. Insulin-like growth factor Type-1 receptor (IGF1R) is frequently overexpressed in primary human breast cancers, with a growing role in the TN phenotype. ...

  1. Conjugated Linoleic Acids Mediate Insulin Release through Islet G Protein-coupled Receptor FFA1/GPR40*

    Science.gov (United States)

    Schmidt, Johannes; Liebscher, Kathrin; Merten, Nicole; Grundmann, Manuel; Mielenz, Manfred; Sauerwein, Helga; Christiansen, Elisabeth; Due-Hansen, Maria E.; Ulven, Trond; Ullrich, Susanne; Gomeza, Jesús; Drewke, Christel; Kostenis, Evi

    2011-01-01

    Among dietary components, conjugated linoleic acids (CLAs) have attracted considerable attention as weight loss supplements in the Western world because they reduce fat stores and increase muscle mass. However, a number of adverse effects are also ascribed to the intake of CLAs such as aggravation of insulin resistance and the risk of developing diabetes. However, the mechanisms accounting for the effects of CLAs on glucose homeostasis are incompletely understood. Herein we provide evidence that CLAs specifically activate the cell surface receptor FFA1, an emerging therapeutic target to treat type 2 diabetes. Using different recombinant cellular systems engineered to stably express FFA1 and a set of diverse functional assays including the novel, label-free non-invasive dynamic mass redistribution technology (Corning® Epic® biosensor), both CLA isomers cis-9, trans-11-CLA and trans-10, cis-12-CLA were found to activate FFA1 in vitro at concentrations sufficient to also account for FFA1 activation in vivo. Each CLA isomer markedly increased glucose-stimulated insulin secretion in insulin-producing INS-1E cells that endogenously express FFA1 and in primary pancreatic β-cells of wild type but not FFA1−/− knock-out mice. Our findings establish a clear mechanistic link between CLAs and insulin production and identify the cell surface receptor FFA1 as a molecular target for CLAs, explaining their acute stimulatory effects on insulin secretion in vivo. CLAs are also revealed as insulinotropic components in widely used nutraceuticals, a finding with significant implication for development of FFA1 modulators to treat type 2 diabetes. PMID:21339298

  2. Myoinositol ameliorates high-fat diet and streptozotocin-induced diabetes in rats through promoting insulin receptor signaling.

    Science.gov (United States)

    Antony, Poovathumkal James; Gandhi, Gopalsamy Rajiv; Stalin, Antony; Balakrishna, Kedike; Toppo, Erenius; Sivasankaran, Kuppusamy; Ignacimuthu, Savarimuthu; Al-Dhabi, Naif Abdullah

    2017-04-01

    Mimosa pudica Linn. (Mimosaceae) has been traditionally used for the management of type 2 diabetes mellitus (T2DM) in India. The present study evaluates the therapeutic efficacy of myoinositol (25 and 50mg/kg) isolated from M. pudica stem methanol extract in Triton WR-1339 induced hyperlipidemic and high-fat diet (HFD) fed-streptozotocin (STZ)-induced insulin-resistant diabetic rats. Lipid biomarkers, fasting blood glucose (FBG), changes in body weight, food and water intakes, plasma insulin, HOMA-IR, oral glucose tolerance, intraperitoneal insulin tolerance, urea, creatinine, marker enzymes of liver function, β-cell function and the expression levels of insulin receptor-induced signaling molecules were studied. Molecular-docking was also carried out to determine the possible interactions of myoinositol into the active sites of insulin-induced signaling markers. In addition, histology of liver, pancreas, kidney, heart and adipose tissues were also performed. In Triton WR-1339 induced hyperlipidemic rats, myoinositol (25 and 50mg/kg) exhibited significant reductions in total cholesterol: 37.5% and 59.73%, triglycerides: 57.75% and 80.14% and LDL-c: 81.44% and 101.75% respectively. HFD fed-STZ receiving myoinositol (25 and 50mg/kg) showed significant reductions in fasting blood glucose: 55.68% and 56.48%, plasma insulin level: 25.45% and 27.06% when compared with diabetic control. It significantly normalized the hyperglycemia induced biochemical abnormalities in insulin-resistant diabetic rats. Furthermore, it demonstrated cytoprotective effects besides increase in the intensity of positive reaction for insulin in pancreas. Myoinositol enhanced the level of PPARγ expression in the adipose tissue of treated rats when compared with rats that did not receive drug treatment; also, it significantly upregulated GLUT4 and IR signaling molecules. Myoinositol had predicted the interactions within the active sites of PPARγ, GLUT4 and IR. These findings suggested that

  3. Insulin receptor signaling in the GnRH neuron plays a role in the abnormal GnRH pulsatility of obese female mice.

    Directory of Open Access Journals (Sweden)

    Sara A DiVall

    Full Text Available Infertility associated with obesity is characterized by abnormal hormone release from reproductive tissues in the hypothalamus, pituitary, and ovary. These tissues maintain insulin sensitivity upon peripheral insulin resistance. Insulin receptor signaling may play a role in the dysregulation of gonadotropin-releasing hormone (GnRH secretion in obesity, but the interdependence of hormone secretion in the reproductive axis and the multi-hormone and tissue dysfunction in obesity hinders investigations of putative contributing factors to the disrupted GnRH secretion. To determine the role of GnRH insulin receptor signaling in the dysregulation of GnRH secretion in obesity, we created murine models of diet-induced obesity (DIO with and without intact insulin signaling in the GnRH neuron. Obese control female mice were infertile with higher luteinizing hormone levels and higher GnRH pulse amplitude and total pulsatile secretion compared to lean control mice. In contrast, DIO mice with a GnRH specific knockout of insulin receptor had improved fertility, luteinizing hormone levels approaching lean mice, and GnRH pulse amplitude and total secretion similar to lean mice. Pituitary responsiveness was similar between genotypes. These results suggest that in the obese state, insulin receptor signaling in GnRH neurons increases GnRH pulsatile secretion and consequent LH secretion, contributing to reproductive dysfunction.

  4. Loss of BMP receptor type 1A in murine adipose tissue attenuates age-related onset of insulin resistance.

    Science.gov (United States)

    Schulz, Tim J; Graja, Antonia; Huang, Tian Lian; Xue, Ruidan; An, Ding; Poehle-Kronawitter, Sophie; Lynes, Matthew D; Tolkachov, Alexander; O'Sullivan, Lindsay E; Hirshman, Michael F; Schupp, Michael; Goodyear, Laurie J; Mishina, Yuji; Tseng, Yu-Hua

    2016-08-01

    Adipose tissue dysfunction is a prime risk factor for the development of metabolic disease. Bone morphogenetic proteins (BMPs) have previously been implicated in adipocyte formation. Here, we investigate the role of BMP signalling in adipose tissue health and systemic glucose homeostasis. We employed the Cre/loxP system to generate mouse models with conditional ablation of BMP receptor 1A in differentiating and mature adipocytes, as well as tissue-resident myeloid cells. Metabolic variables were assessed by glucose and insulin tolerance testing, insulin-stimulated glucose uptake and gene expression analysis. Conditional deletion of Bmpr1a using the aP2 (also known as Fabp4)-Cre strain resulted in a complex phenotype. Knockout mice were clearly resistant to age-related impairment of insulin sensitivity during normal and high-fat-diet feeding and showed significantly improved insulin-stimulated glucose uptake in brown adipose tissue and skeletal muscle. Moreover, knockouts displayed significant reduction of variables of adipose tissue inflammation. Deletion of Bmpr1a in myeloid cells had no impact on insulin sensitivity, while ablation of Bmpr1a in mature adipocytes partially recapitulated the initial phenotype from aP2-Cre driven deletion. Co-cultivation of macrophages with pre-adipocytes lacking Bmpr1a markedly reduced expression of proinflammatory genes. Our findings show that altered BMP signalling in adipose tissue affects the tissue's metabolic properties and systemic insulin resistance by altering the pattern of immune cell infiltration. The phenotype is due to ablation of Bmpr1a specifically in pre-adipocytes and maturing adipocytes rather than an immune cell-autonomous effect. Mechanistically, we provide evidence for a BMP-mediated direct crosstalk between pre-adipocytes and macrophages.

  5. Drosophila insulin-producing cells are differentially modulated by serotonin and octopamine receptors and affect social behavior.

    Directory of Open Access Journals (Sweden)

    Jiangnan Luo

    Full Text Available A set of 14 insulin-producing cells (IPCs in the Drosophila brain produces three insulin-like peptides (DILP2, 3 and 5. Activity in IPCs and release of DILPs is nutrient dependent and controlled by multiple factors such as fat body-derived proteins, neurotransmitters, and neuropeptides. Two monoamine receptors, the octopamine receptor OAMB and the serotonin receptor 5-HT1A, are expressed by the IPCs. These receptors may act antagonistically on adenylate cyclase. Here we investigate the action of the two receptors on activity in and output from the IPCs. Knockdown of OAMB by targeted RNAi led to elevated Dilp3 transcript levels in the brain, whereas 5-HT1A knockdown resulted in increases of Dilp2 and 5. OAMB-RNAi in IPCs leads to extended survival of starved flies and increased food intake, whereas 5-HT1A-RNAi produces the opposite phenotypes. However, knockdown of either OAMB or 5-HT1A in IPCs both lead to increased resistance to oxidative stress. In assays of carbohydrate levels we found that 5-HT1A knockdown in IPCs resulted in elevated hemolymph glucose, body glycogen and body trehalose levels, while no effects were seen after OAMB knockdown. We also found that manipulations of the two receptors in IPCs affected male aggressive behavior in different ways and 5-HT1A-RNAi reduced courtship latency. Our observations suggest that activation of 5-HT1A and OAMB signaling in IPCs generates differential effects on Dilp transcription, fly physiology, metabolism and social interactions. However the findings do not support an antagonistic action of the two monoamines and their receptors in this particular system.

  6. Energy expenditure, body composition and insulin response to glucose in male twins discordant for the Trp64Arg polymorphism of the beta3-adrenergic receptor gene

    DEFF Research Database (Denmark)

    Højlund, K; Christiansen, C; Bjørnsbo, K S;

    2006-01-01

    and environmental background, the Trp64Arg polymorphism of the beta3AR gene is associated with lower fat mass, fasting insulin levels and an appropriate insulin response to glucose. Thus, heterozygosity for the Trp64Arg variant is unlikely to increase the risk of obesity, insulin resistance or type 2 diabetes.......AIM: The tryptophan to arginine change in position 64 (Trp64Arg) polymorphism of the beta3-adrenergic receptor (beta3AR) gene has been associated with an increased prevalence of obesity, insulin resistance and type 2 diabetes. In this, decreased rates of energy expenditure and impaired insulin......-ray absorptiometry scanning and energy expenditure by indirect and direct calorimetry. RESULTS: Twins heterozygous for the Trp64Arg polymorphism showed significantly lower fat mass independent of the method used, and significantly lower fasting insulin and glucose concentrations compared with their homozygous wild...

  7. Uteroplacental insufficiency down regulates insulin receptor and affects expression of key enzymes of long-chain fatty acid (LCFA metabolism in skeletal muscle at birth

    Directory of Open Access Journals (Sweden)

    Puglianiello Antonella

    2008-05-01

    Full Text Available Abstract Background Epidemiological studies have revealed a relationship between early growth restriction and the subsequent development of insulin resistance and type 2 diabetes. Ligation of the uterine arteries in rats mimics uteroplacental insufficiency and serves as a model of intrauterine growth restriction (IUGR and subsequent developmental programming of impaired glucose tolerance, hyperinsulinemia and adiposity in the offspring. The objective of this study was to investigate the effects of uterine artery ligation on the skeletal muscle expression of insulin receptor and key enzymes of LCFA metabolism. Methods Bilateral uterine artery ligation was performed on day 19 of gestation in Sprague-Dawley pregnant rats. Muscle of the posterior limb was dissected at birth and processed by real-time RT-PCR to analyze the expression of insulin receptor, ACCα, ACCβ (acetyl-CoA carboxylase alpha and beta subunits, ACS (acyl-CoA synthase, AMPK (AMP-activated protein kinase, alpha2 catalytic subunit, CPT1B (carnitine palmitoyltransferase-1 beta subunit, MCD (malonyl-CoA decarboxylase in 14 sham and 8 IUGR pups. Muscle tissue was treated with lysis buffer and Western immunoblotting was performed to assay the protein content of insulin receptor and ACC. Results A significant down regulation of insulin receptor protein (p Conclusion Our data suggest that uteroplacental insufficiency may affect skeletal muscle metabolism down regulating insulin receptor and reducing the expression of key enzymes involved in LCFA formation and oxidation.

  8. Association of β3 Adrenergic Receptor and Peroxisome Proliferator-activated Receptor Gamma 2 Polymorphisms With Insulin Sensitivity: A Twin Study

    Institute of Scientific and Technical Information of China (English)

    TIAN-JIAO CHEN; CHENG-YE JI; XIAO-YING ZHENG; YONG-HUA HU

    2007-01-01

    Objective To study the effect of β3 adrenergic receptor (β3AR) Trp64Arg and peroxisome proliferator activated receptor gamma 2 (PPARγ2) Pro12Ala polymorphisms on insulin resistance. Methods One hundred and eight dizygotic twin pairs were enrolled in this study. Microsatellite polymorphism was used to diagnose zygosity of twins. Insulin sensitivity was estimated with logarithm transformed homeostasis model assessment (HOMA). PCR-RFLP analysis was performed to detect the variants. As a supplement to the sib-pair method, identity by state (IBS) was used to analyze the association of polymorphisms with insulin sensitivity. Results The genotype frequencies of Trp64Trg, Trp64Arg, and Arg64Arg were 72.3%, 23.8%, and 3.9%, respectively, while the genotype frequencies of Pro12Pro, Pro12Ala, and Ala12Ala were 89.9%, 9.6%,and 0.5%, respectively. For β3AR Trp64Arg the interclass co-twin correlations of Waist-to-hip ratio (WHR), blood glucose (GLU), and insulin (INS), homeostasis model assessment insulin resistance index (HOMA-IR) of the twin pairs sharing 2alleles of IBS were greater than those sharing 0-1 allele of IBS, and HOMA-IR had statistic significance. For PPARγ2 Pro12Ala most traits of twin pairs sharing 2 alleles of IBS had greater correlations and statistic significance in body mass index (BMI),WHR, percent of body fat (PBF) and GLU, but there were low correlations of either insulin or HOMA-IR of twin pairs sharing 1 or 2 alleles of IBS. The combined effects of the two variations showed less squared significant twin-pair differences of INS and HOMA-IR among twins sharing 4 alleles of IBS. Conclusions β3AR Trp64Arg and PPARγ2 Pro12Ala polymorphisms might be associated with insulin resistance and obesity, and there might be slight synergistic effects between this two gene loci,and further studies are necessary to confirm this finding.

  9. Study of Mutation in Tyrosine Protein Kinase of Insulin Receptor Gene in Patients with Polycystic Ovarian Syndrome

    Institute of Scientific and Technical Information of China (English)

    Min LI; Hong-yu QIU; Yong-yu SUN; Hong-fa LI; Yong-li CHU

    2003-01-01

    Objective To explore the molecular mechanism of insulin resistance in the patients with polycystic ovarian syndrome (PCOS)Methods Polymerase chain reaction, silver staining-single strand conformation polymorphism(PCR-SSCP) and DNA direct sequencing were used to detect the mutation of insulin receptor(INSR) gene in exon 17~21 with the abdominal wall adipose tissue from 31 patients with PCOS (PCOS Group) and 30 patients with pure hysteromyoma in reproductive lift (Control Group).Results Twenty-two variant SSCP patterns in exon 17 of INSR gene were detected. Direct sequence analysis of exon 17 showed that homozygous nonsense mutation was two alleles single nucleotide polymorphism(SNP) at the codon 1058 (CAC→CAT). Exons 18~21 were not detected with any significantly mutation. The INSR gene His1058C→T substitution collecting rate and insulin resistance were significantly higher in the PCOS group than in the control group (P=0.0293, P<0.05, P<0.01).Conclusion It is suggested that the SNP in codon 1058 of the INSR gene might be related with the insulin resistance in PCOS patients, which has hereditary tendency. And the missense mutation,nonsense mutation and frameshift mutation at exons 18~21 in tyrosine protein kinase region of INSR gene for PCOS patients were not frequently observed.

  10. NOVEL ROLES FOR INSULIN RECEPTOR (IR) IN ADIPOCYTES AND SKELETAL MUSCLE CELLS VIA NEW AND UNEXPECTED SUBSTRATES

    Science.gov (United States)

    Ramalingam, Latha; Oh, Eunjin; Thurmond, Debbie C.

    2012-01-01

    The insulin signaling pathway regulates whole-body glucose homeostasis by transducing extracellular signals from the insulin receptor (IR) to downstream intracellular targets, thus coordinating a multitude of biological functions. Dysregulation of IR or its signal transduction is associated with insulin resistance, which may culminate in type 2 diabetes (T2D). Following initial stimulation of IR, insulin signaling diverges into different pathways, activating multiple substrates which have roles in various metabolic and cellular processes. The integration of multiple pathways arising from IR activation continues to expand as new IR substrates are identified and characterized. Accordingly, our review will focus on roles for IR substrates as they pertain to three primary areas: Metabolism/glucose uptake, Mitogenesis/growth, and Aging/Longevity. While IR functions in a seemingly pleotropic manner in many cell types, through these three main roles in fat and skeletal muscle cells, IR multi-tasks to regulate whole-body glucose homeostasis to impact healthspan and lifespan. PMID:23052216

  11. Adipocyte Dynamics and Reversible Metabolic Syndrome in Mice with an Inducible Adipocyte-Specific Deletion of the Insulin Receptor.

    Science.gov (United States)

    Sakaguchi, Masaji; Fujisaka, Shiho; Cai, Weikang; Winnay, Jonathon N; Konishi, Masahiro; O'Neill, Brian T; Li, Mengyao; García-Martín, Rubén; Takahashi, Hirokazu; Hu, Jiang; Kulkarni, Rohit N; Kahn, C Ronald

    2017-02-07

    Insulin and IGF1 signaling are important for adipose tissue development and function; however, their role in mature adipocytes is unclear. Mice with a tamoxifen-inducible knockout of insulin and/or IGF1 receptors (IR/IGF1R) demonstrate a rapid loss of white and brown fat due to increased lipolysis and adipocyte apoptosis. This results in insulin resistance, glucose intolerance, hepatosteatosis, islet hyperplasia with hyperinsulinemia, and cold intolerance. This phenotype, however, resolves over 10-30 days due to a proliferation of preadipocytes and rapid regeneration of both brown and white adipocytes as identified by mTmG lineage tracing. This cycle can be repeated with a second round of receptor inactivation. Leptin administration prior to tamoxifen treatment blocks development of the metabolic syndrome without affecting adipocyte loss or regeneration. Thus, IR is critical in adipocyte maintenance, and this loss of adipose tissue stimulates regeneration of brown/white fat and reversal of metabolic syndrome associated with fat loss. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Insulin and IGF1 receptors are essential for XX and XY gonadal differentiation and adrenal development in mice.

    Directory of Open Access Journals (Sweden)

    Jean-Luc Pitetti

    Full Text Available Mouse sex determination provides an attractive model to study how regulatory genetic networks and signaling pathways control cell specification and cell fate decisions. This study characterizes in detail the essential role played by the insulin receptor (INSR and the IGF type I receptor (IGF1R in adrenogenital development and primary sex determination. Constitutive ablation of insulin/IGF signaling pathway led to reduced proliferation rate of somatic progenitor cells in both XX and XY gonads prior to sex determination together with the downregulation of hundreds of genes associated with the adrenal, testicular, and ovarian genetic programs. These findings indicate that prior to sex determination somatic progenitors in Insr;Igf1r mutant gonads are not lineage primed and thus incapable of upregulating/repressing the male and female genetic programs required for cell fate restriction. In consequence, embryos lacking functional insulin/IGF signaling exhibit (i complete agenesis of the adrenal cortex, (ii embryonic XY gonadal sex reversal, with a delay of Sry upregulation and the subsequent failure of the testicular genetic program, and (iii a delay in ovarian differentiation so that Insr;Igf1r mutant gonads, irrespective of genetic sex, remained in an extended undifferentiated state, before the ovarian differentiation program ultimately is initiated at around E16.5.

  13. Insulin and IGF1 receptors are essential for XX and XY gonadal differentiation and adrenal development in mice.

    Science.gov (United States)

    Pitetti, Jean-Luc; Calvel, Pierre; Romero, Yannick; Conne, Béatrice; Truong, Vy; Papaioannou, Marilena D; Schaad, Olivier; Docquier, Mylène; Herrera, Pedro Luis; Wilhelm, Dagmar; Nef, Serge

    2013-01-01

    Mouse sex determination provides an attractive model to study how regulatory genetic networks and signaling pathways control cell specification and cell fate decisions. This study characterizes in detail the essential role played by the insulin receptor (INSR) and the IGF type I receptor (IGF1R) in adrenogenital development and primary sex determination. Constitutive ablation of insulin/IGF signaling pathway led to reduced proliferation rate of somatic progenitor cells in both XX and XY gonads prior to sex determination together with the downregulation of hundreds of genes associated with the adrenal, testicular, and ovarian genetic programs. These findings indicate that prior to sex determination somatic progenitors in Insr;Igf1r mutant gonads are not lineage primed and thus incapable of upregulating/repressing the male and female genetic programs required for cell fate restriction. In consequence, embryos lacking functional insulin/IGF signaling exhibit (i) complete agenesis of the adrenal cortex, (ii) embryonic XY gonadal sex reversal, with a delay of Sry upregulation and the subsequent failure of the testicular genetic program, and (iii) a delay in ovarian differentiation so that Insr;Igf1r mutant gonads, irrespective of genetic sex, remained in an extended undifferentiated state, before the ovarian differentiation program ultimately is initiated at around E16.5.

  14. Molecular variation and evolution of the tyrosine kinase domains of insulin receptor IRa and IRb genes in Cyprinidae.

    Science.gov (United States)

    Kong, XiangHui; Wang, XuZhen; He, ShunPing

    2011-07-01

    The insulin receptor (IR) gene plays an important role in regulating cell growth, differentiation and development. In the present study, DNA sequences of insulin receptor genes, IRa and IRb, were amplified and sequenced from 37 representative species of the Cyprinidae and from five outgroup species from non-cyprinid Cypriniformes. Based on coding sequences (CDS) of tyrosine kinase regions of IRa and IRb, molecular evolution and phylogenetic relationships were analyzed to better understand the characteristics of IR gene divergence in the family Cyprinidae. IRa and IRb were clustered into one lineage in the gene tree of the IR gene family, reconstructed using the unweighted pair group method with arithmetic mean (UPGMA). IRa and IRb have evolved into distinct genes after IR gene duplication in Cyprinidae. For each gene, molecular evolution analyses showed that there was no significant difference among different groups in the reconstructed maximum parsimony (MP) tree of Cyprinidae; IRa and IRb have been subjected to similar evolutionary pressure among different lineages. Although the amino acid sequences of IRa and IRb tyrosine kinase regions were highly conserved, our analyses showed that there were clear sequence variations between the tyrosine kinase regions of IRa and IRb proteins. This indicates that IRa and IRb proteins might play different roles in the insulin signaling pathway.

  15. Inhibitory Effect of Memantine on Streptozotocin-Induced Insulin Receptor Dysfunction, Neuroinflammation, Amyloidogenesis, and Neurotrophic Factor Decline in Astrocytes.

    Science.gov (United States)

    Rajasekar, N; Nath, Chandishwar; Hanif, Kashif; Shukla, Rakesh

    2016-12-01

    Our earlier studies showed that insulin receptor (IR) dysfunction along with neuroinflammation and amyloidogenesis played a major role in streptozotocin (STZ)-induced toxicity in astrocytes. N-methyl-D-aspartate (NMDA) receptor antagonist-memantine shows beneficial effects in Alzheimer's disease (AD) pathology. However, the protective molecular and cellular mechanism of memantine in astrocytes is not properly understood. Therefore, the present study was undertaken to investigate the effect of memantine on insulin receptors, neurotrophic factors, neuroinflammation, and amyloidogenesis in STZ-treated astrocytes. STZ (100 μM) treatment for 24 h in astrocytes resulted significant decrease in brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF), and insulin-degrading enzyme (IDE) expression in astrocytes. Treatment with memantine (1-10 μM) improved STZ-induced neurotrophic factor decline (BDNF, GDNF) along with IR dysfunction as evidenced by a significant increase in IR protein expression, phosphorylation of IRS-1, Akt, and GSK-3 α/β in astrocytes. Further, memantine attenuated STZ-induced amyloid precursor protein (APP), β-site APP-cleaving enzyme-1 and amyloid-β1-42 expression and restored IDE expression in astrocytes. In addition, memantine also displays protective effects against STZ-induced astrocyte activation showed by reduction of inflammatory markers, nuclear factor kappa-B translocation, glial fibrillary acidic protein, cyclooxygenase-2, tumor necrosis factor-α level, and oxidative-nitrostative stress. The results suggest that besides the NMDA receptor antagonisic activity, effect on astroglial IR and neurotrophic factor may also be an important factor in the beneficial effect of memantine in AD pathology. Graphical Abstract Novel neuroprotective mechanisms of memenatine in streptozotocin-induced toxicity in astrocytes.

  16. Type I Insulin-like Growth Factor Receptor Induces Pulmonary Tumorigenesis

    Directory of Open Access Journals (Sweden)

    Nicolle M. Linnerth

    2009-07-01

    Full Text Available Despite the type I insulin-like growth factor receptor (IGF-IR being highly expressed in more than 80% of human lung tumors, a transgenic model of IGF-IR overexpression in the lung has not been created. We produced two novel transgenic mouse models in which IGF-IR is overexpressed in either lung type II alveolar cells (surfactant protein C [SPC]-IGFIR or Clara cells (CCSP-IGFIR in a doxycycline-inducible manner. Overexpression of IGF-IR in either cell type caused multifocal adenomatous alveolar hyperplasia with papillary and solid adenomas. These tumors expressed thyroid transcription factor 1 and Kruppel-like factor 5 in most tumor cells. Similar to our previous work with lung tumors that developed in the mouse mammary tumor virus-IGF-II transgenic mice, the lung tumors that develop in the SPC-IGFIR and CCSP-IGFIR transgenic mice expressed high levels of the cyclic adenosine monophosphate response element binding protein that was localized primarily to the nucleus. Although elevated IGF-IR expression can initiate lung tumor development, tumors can become independent of IGF-IR signaling as IGF-IR down-regulation in established tumors produced tumor regression in some, but not all, of the tumors. These findings implicate IGF-IR as an important initiator of lung tumorigenesis and suggest that the SPC-IGFIR and CCSP-IGFIR transgenic mice can be used to further our understanding of human lung cancer and the role IGF-IR plays in this disease.

  17. Insulin-like growth factor type-1 receptor down-regulation associated with dwarfism in Holstein calves.

    Science.gov (United States)

    Blum, J W; Elsasser, T H; Greger, D L; Wittenberg, S; de Vries, F; Distl, O

    2007-10-01

    Perturbations in endocrine functions can impact normal growth. Endocrine traits were studied in three dwarf calves exhibiting retarded but proportionate growth and four phenotypically normal half-siblings, sired by the same bull, and four unrelated control calves. Plasma 3,5,3'-triiodothyronine and thyroxine concentrations in dwarfs and half-siblings were in the physiological range and responded normally to injected thyroid-releasing hormone. Plasma glucagon concentrations were different (dwarfs, controls>half-siblings; Pcontrols, Pcontrols, P=0.08). Responses of GH to xylazine and to a GH-releasing-factor analogue were similar in dwarfs and half-siblings. Relative gene expression of IGF-1, IGF-2, GH receptor (GHR), insulin receptor, IGF-1 type-1 and -2 receptors (IGF-1R, IGF-2R), and IGF binding proteins were measured in liver and anconeus muscle. GHR mRNA levels were different in liver (dwarfsdwarfism in studied calves.

  18. Chemokine-like receptor 1 deficiency does not affect the development of insulin resistance and nonalcoholic fatty liver disease in mice

    NARCIS (Netherlands)

    Gruben, Nanda; Vergara, Marcela Aparicio; Kloosterhuis, Niels J.; van der Molen, Henk; Stoelwinder, Stefan; Youssef, Sameh; de Bruin, Alain; Delsing, Dianne J.; Kuivenhoven, Jan Albert; van de Sluis, Bart; Hofker, Marten H.; Koonen, Debby P. Y.

    2014-01-01

    The adipokine chemerin and its receptor, chemokine-like receptor 1 (Cmklr1), are associated with insulin resistance and nonalcoholic fatty liver disease (NAFLD), which covers a broad spectrum of liver diseases, ranging from simple steatosis to nonalcoholic steatohepatitis (NASH). It is possible that

  19. Reevaluation of Fatty acid receptor 1 (FFAR1/GPR40) as drug target for the stimulation of insulin secretion in humans

    DEFF Research Database (Denmark)

    Wagner, Robert; Kaiser, Gabriele; Gerst, Felicia;

    2013-01-01

    The role of free fatty acid receptor 1 (FFAR1/GPR40) in glucose homeostasis is still incompletely understood. Small receptor agonists stimulating insulin secretion are under investigation for the treatment of type 2 diabetes. Surprisingly, genome-wide association studies did not discover diabetes...

  20. In skeletal muscle advanced glycation end products (AGEs) inhibit insulin action and induce the formation of multimolecular complexes including the receptor for AGEs.

    Science.gov (United States)

    Cassese, Angela; Esposito, Iolanda; Fiory, Francesca; Barbagallo, Alessia P M; Paturzo, Flora; Mirra, Paola; Ulianich, Luca; Giacco, Ferdinando; Iadicicco, Claudia; Lombardi, Angela; Oriente, Francesco; Van Obberghen, Emmanuel; Beguinot, Francesco; Formisano, Pietro; Miele, Claudia

    2008-12-26

    Chronic hyperglycemia promotes insulin resistance at least in part by increasing the formation of advanced glycation end products (AGEs). We have previously shown that in L6 myotubes human glycated albumin (HGA) induces insulin resistance by activating protein kinase Calpha (PKCalpha). Here we show that HGA-induced PKCalpha activation is mediated by Src. Coprecipitation experiments showed that Src interacts with both the receptor for AGE (RAGE) and PKCalpha in HGA-treated L6 cells. A direct interaction of PKCalpha with Src and insulin receptor substrate-1 (IRS-1) has also been detected. In addition, silencing of IRS-1 expression abolished HGA-induced RAGE-PKCalpha co-precipitation. AGEs were able to induce insulin resistance also in vivo, as insulin tolerance tests revealed a significant impairment of insulin sensitivity in C57/BL6 mice fed a high AGEs diet (HAD). In tibialis muscle of HAD-fed mice, insulin-induced glucose uptake and protein kinase B phosphorylation were reduced. This was paralleled by a 2.5-fold increase in PKCalpha activity. Similarly to in vitro observations, Src phosphorylation was increased in tibialis muscle of HAD-fed mice, and co-precipitation experiments showed that Src interacts with both RAGE and PKCalpha. These results indicate that AGEs impairment of insulin action in the muscle might be mediated by the formation of a multimolecular complex including RAGE/IRS-1/Src and PKCalpha.

  1. The beta2 adrenergic receptor Gln27Glu polymorphism affects insulin resistance in patients with heart failure: possible modulation by choice of beta blocker.

    Science.gov (United States)

    Vardeny, Orly; Detry, Michelle A; Moran, John J M; Johnson, Maryl R; Sweitzer, Nancy K

    2008-12-01

    Insulin resistance is prevalent in heart failure (HF) patients, and beta2 adrenergic receptors (beta2-AR) are involved in glucose homeostasis. We hypothesized that beta2-AR Gln27Glu and Arg16Gly polymorphisms affect insulin resistance in HF patients, and we explored if effects of beta2-AR polymorphisms on glucose handling are modified by choice of beta blocker. We studied 30 nondiabetic adults with HF and a history of systolic dysfunction; 15 were receiving metoprolol succinate, and 15 were receiving carvedilol. We measured fasting glucose, insulin, and insulin resistance, and we determined beta2-AR genotypes at codons 27 and 16. The cohort was insulin resistant with a mean HOMA-IR score of 3.4 (95% CI, 2.3 to 4.5; normal value, 1.0). Patients with the Glu27Glu genotype exhibited higher insulin and HOMA-IR compared to individuals carrying a Gln allele (P = 0.019). Patients taking carvedilol demonstrated lower insulin resistance if also carrying a wild-type allele at codon 27 (fasting insulin, 9.8 +/- 10.5 versus 20.5 +/- 2.1 for variant, P = 0.072; HOMA-IR, 2.4 +/- 2.7 versus 5.1 +/- 0.6, P = 0.074); those on metoprolol succinate had high insulin resistance irrespective of genotype. The beta2-AR Glu27Glu genotype may be associated with higher insulin concentrations and insulin resistance in patients with HF. Future studies are needed to confirm whether treatment with carvedilol may be associated with decreased insulin and insulin resistance in beta2-AR codon 27 Gln carriers.

  2. Dietary approaches to stop hypertension influence on insulin receptor substrate-1gene expression: A randomized controlled clinical trial

    Directory of Open Access Journals (Sweden)

    Marzieh Kafeshani

    2015-01-01

    Full Text Available Background: Insulin receptor substrate (IRS Type 1 is a main substrate for the insulin receptor, controls insulin signaling in skeletal muscle, adipose tissue, and the vascular, so it is an important candidate gene for insulin resistance (IR. We aimed to compare the effects of the Dietary Approaches to Stop Hypertension (DASH and Usual Dietary Advices (UDA on IRS1 gene expression in women at risk for cardiovascular disease. Materials and Methods: A randomized controlled clinical trial was performed in 44 women at risk for cardiovascular disease. Participants were randomly assigned to a UDA diet or the DASH diet. The DASH diet was rich in fruits, vegetables, whole grains, and low-fat dairy products and low in saturated fat, total fat, cholesterol, refined grains, and sweets, with a total of 2400 mg/day sodium. The UDA diet was a regular diet with healthy dietary advice. Gene expression was assessed by the real-time polymerase chain reaction at the first of study and after 12 weeks. Independent sample t-test and paired-samples t-test were used to compare means of all variables within and between two groups respectively. Results: IRS1 gene expression was increased in DASH group compared with UDA diet (P = 0.00. Weight and waist circumference decreased in DASH group significantly compared to the UDA group (P < 0.05 but the results between the two groups showed no significant difference. Conclusion: DASH diet increased IRS1 gene expression and probably has beneficial effects on IR risks.

  3. Repression of a potassium channel by nuclear hormone receptor and TGF-β signaling modulates insulin signaling in Caenorhabditis elegans.

    Directory of Open Access Journals (Sweden)

    Donha Park

    Full Text Available Transforming growth factor β (TGF-β signaling acts through Smad proteins to play fundamental roles in cell proliferation, differentiation, apoptosis, and metabolism. The Receptor associated Smads (R-Smads interact with DNA and other nuclear proteins to regulate target gene transcription. Here, we demonstrate that the Caenorhabditis elegans R-Smad DAF-8 partners with the nuclear hormone receptor NHR-69, a C. elegans ortholog of mammalian hepatocyte nuclear factor 4α HNF4α, to repress the exp-2 potassium channel gene and increase insulin secretion. We find that NHR-69 associates with DAF-8 both in vivo and in vitro. Functionally, daf-8 nhr-69 double mutants show defects in neuropeptide secretion and phenotypes consistent with reduced insulin signaling such as increased expression of the sod-3 and gst-10 genes and a longer life span. Expression of the exp-2 gene, encoding a voltage-gated potassium channel, is synergistically increased in daf-8 nhr-69 mutants compared to single mutants and wild-type worms. In turn, exp-2 acts selectively in the ASI neurons to repress the secretion of the insulin-like peptide DAF-28. Importantly, exp-2 mutation shortens the long life span of daf-8 nhr-69 double mutants, demonstrating that exp-2 is required downstream of DAF-8 and NHR-69. Finally, animals over-expressing NHR-69 specifically in DAF-28-secreting ASI neurons exhibit a lethargic, hypoglycemic phenotype that is rescued by exogenous glucose. We propose a model whereby DAF-8/R-Smad and NHR-69 negatively regulate the transcription of exp-2 to promote neuronal DAF-28 secretion, thus demonstrating a physiological crosstalk between TGF-β and HNF4α-like signaling in C. elegans. NHR-69 and DAF-8 dependent regulation of exp-2 and DAF-28 also provides a novel molecular mechanism that contributes to the previously recognized link between insulin and TGF-β signaling in C. elegans.

  4. Epigallocatechin gallate improves insulin signaling by decreasing toll-like receptor 4 (TLR4) activity in adipose tissues of high-fat diet rats.

    Science.gov (United States)

    Bao, Suqing; Cao, Yanli; Fan, Chenling; Fan, Yuxin; Bai, Shuting; Teng, Weiping; Shan, Zhongyan

    2014-04-01

    In this study, we investigated the beneficial effects and the underlying mechanism of epigallocatechin gallate (EGCG) in adipose tissues of rats fed with a high-fat diet (HFD). Fasting plasma insulin, epididymal fat coefficient and free fatty acids, homeostasis model assessment-insulin resistance index, and the average glucose infusion rate were determined. EGCG significantly decreased free fatty acids, fasting insulin, homeostasis model assessment-insulin resistance index, and epididymal fat coefficient, and increased glucose infusion rate in HFD group. The levels of toll-like receptor 4, TNF receptor associated factor 6, inhibitor-kappa-B kinase β, p-nuclear factor κB, tumor necrosis factor α, and IL-6 in the EGCG group were all significantly lower than the HFD control group. EGCG also decreased the level of phosphorylated insulin receptor substrate 1 and increased phosphoinositide-3-kinase and glucose transporter isoform 4 in the HFD group. Decreased macrophage infiltration was in EGCG group versus HFD group, and the protein level of CD68 in EGCG group was also significantly lower than that of HFD group. EGCG attenuated inflammation by decreasing the content of macrophages, interfered the toll-like receptor 4 mediated inflammatory response pathway, thus, improving insulin signaling in adipose tissues. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Liquid fructose down-regulates liver insulin receptor substrate 2 and gluconeogenic enzymes by modifying nutrient sensing factors in rats.

    Science.gov (United States)

    Rebollo, Alba; Roglans, Núria; Baena, Miguel; Padrosa, Anna; Sánchez, Rosa M; Merlos, Manuel; Alegret, Marta; Laguna, Juan C

    2014-02-01

    High consumption of fructose-sweetened beverages has been linked to a high prevalence of chronic metabolic diseases. We have previously shown that a short course of fructose supplementation as a liquid solution induces glucose intolerance in female rats. In the present work, we characterized the fructose-driven changes in the liver and the molecular pathways involved. To this end, female rats were supplemented or not with liquid fructose (10%, w/v) for 7 or 14 days. Glucose and pyruvate tolerance tests were performed, and the expression of genes related to insulin signaling, gluconeogenesis and nutrient sensing pathways was evaluated. Fructose-supplemented rats showed increased plasma glucose excursions in glucose and pyruvate tolerance tests and reduced hepatic expression of several genes related to insulin signaling, including insulin receptor substrate 2 (IRS-2). However, the expression of key gluconeogenic enzymes, glucose-6-phosphatase and phosphoenolpyruvate carboxykinase, was reduced. These effects were caused by an inactivation of hepatic forkhead box O1 (FoxO1) due to an increase in its acetylation state driven by a reduced expression and activity of sirtuin 1 (SIRT1). Further contributing to FoxO1 inactivation, fructose consumption elevated liver expression of the spliced form of X-box-binding-protein-1 as a consequence of an increase in the activity of the mammalian target of rapamycin 1 and protein 38-mitogen activated protein kinase (p38-MAPK). Liquid fructose affects both insulin signaling (IRS-2 and FoxO1) and nutrient sensing pathways (p38-MAPK, mTOR and SIRT1), thus disrupting hepatic insulin signaling without increasing the expression of key gluconeogenic enzymes.

  6. Bioactive GLP-1 in gut, receptor expression in pancreas, and insulin response to GLP-1 in diabetes-prone rats.

    Science.gov (United States)

    Valverde, Isabel; Wang, Gen-Sheng; Burghardt, Karolina; Kauri, Lisa M; Redondo, Araceli; Acitores, Alicia; Villanueva-Peñacarrillo, Maria L; Courtois, Philippe; Sener, Abdullah; Cancelas, Jesús; Malaisse, Willy J; Scott, Fraser W

    2004-02-01

    Glucagon-like peptide-1 (GLP-1) is the most insulinogenic of the glucagon-like peptides secreted mainly by L cells in the small and large intestine in response to the ingestion of nutrients. It binds to a specific GLP-1 receptor (GLP-1R) on beta-cells and can increase islet neogenesis and beta-cell mass. It is not clear whether the transmission of information from the gut to islet beta-cells by messengers such as GLP-1 is different in individuals who develop autoimmune diabetes. In the present study the expression of bioactive GLP-1 protein in the gut and its receptor in the pancreas was examined in diabetes-prone BioBreeding (BBdp) rats in the period before overt diabetes and in age-matched control, non-diabetes-prone BB (BBc) rats. An N-terminal directed antibody specific for the bioactive forms of GLP-1 (GLP-1(7-37) and GLP-1(7-36amide)) was used to mea-sure GLP-1 by radioimmunoassay in proximal, median, and distal gut. Pancreas GLP-1R area fraction, GLP-1R gene expression, and insulin content were analyzed, as were plasma GLP-1, glucose, and insulin. The concentration of GLP-1 protein in the jejunum and ileum of BBdp rats was lower than in BBc rats. Although these animals maintained normal blood glucose, there was impaired pancreatic endocrine function, characterized by low baseline insulin concentration in plasma and pancreas. GLP-1R mRNA expression was threefold less in islets isolated from BBdp rats, and GLP-1R+ islet area fraction in pancreas sections was decreased. When injected iv with GLP-1, BBdp rats displayed lower second-phase insulin response (and insulin/glucose ratios) compared with BBc rats. Thus, young BBdp rats displayed decreased concentrations of bioactive GLP-1 in jejunum and ileum, reduced GLP-1R in islets, and lower second-phase insulin response to iv GLP-1 than controls. The decrease in insulinogenic and islet beta-cell mass-promoting signal from GLP-1 in BBdp rats may contribute to impaired glucoregulation and ineffective maintenance of

  7. In vivo imaging of insulin receptors by PET: preclinical evaluation of iodine-125 and iodine-124 labelled human insulin

    Energy Technology Data Exchange (ETDEWEB)

    Iozzo, P.; Osman, S.; Glaser, M.; Knickmeier, M.; Ferrannini, E.; Pike, V.W.; Camici, P.G.; Law, M.P. E-mail: marilyn.law@csc.mrc.ac.uk

    2002-01-01

    [A{sub 14}-*I]iodoinsulin was prepared for studies to assess the suitability of labeled iodoinsulin for positron emission tomography (PET). Iodine-125 was used to establish the methods and for preliminary studies in rats. Further studies and PET scanning in rats were carried out using iodine-124. Tissue and plasma radioactivity was measured as the uptake index (UI={l_brace}cpm{center_dot}(g tissue){sup -1}{r_brace}/{l_brace}cpm injected{center_dot}(g body weight){sup -1}{r_brace}) at 1 to 40 min after intravenous injection of either [A{sub 14}-{sup 125}I]iodoinsulin or [A{sub 14}-{sup 124}I]iodoinsulin. For both radiotracers, initial clearance of radioactivity from plasma was rapid (T{sub 1/2} {approx} 1 min), reaching a plateau (UI = 2.8) at {approx} 5 min which was maintained for 35 min. Tissue biodistributions of the two radiotracers were comparable; at 10 min after injection, UI for myocardium was 2.4, liver, 4.0, pancreas, 5.4, brain, 0.17, kidney, 22, lung, 2.3, muscle, 0.54 and fat, 0.28. Predosing rats with unlabelled insulin reduced the UI for myocardium (0.95), liver (1.8), pancreas (1.2) and brain (0.08), increased that for kidney (61) but had no effect on that for lung (2.5), muscle (0.50) or fat (0.34). Analysis of radioactivity in plasma demonstrated a decrease of [{sup 125}I]iodoinsulin associated with the appearance of labeled metabolites; the percentage of plasma radioactivity due to [{sup 125}I]iodoinsulin was 40% at 5 min and 10% at 10 min. The heart, liver and kidneys were visualized using [{sup 124}I]iodoinsulin with PET.

  8. GLP-1 receptor agonism ameliorates hepatic VLDL overproduction and de novo lipogenesis in insulin resistance

    Directory of Open Access Journals (Sweden)

    Jennifer Taher

    2014-12-01

    Conclusion: Exendin-4 prevents fructose-induced dyslipidemia and hepatic VLDL overproduction in insulin resistance through an indirect mechanism involving altered energy utilization, decreased hepatic lipid synthesis and also requires an intact parasympathetic signaling pathway.

  9. Higher-Resolution Structure of the Human Insulin Receptor Ectodomain: Multi-Modal Inclusion of the Insert Domain.

    Science.gov (United States)

    Croll, Tristan I; Smith, Brian J; Margetts, Mai B; Whittaker, Jonathan; Weiss, Michael A; Ward, Colin W; Lawrence, Michael C

    2016-03-01

    Insulin receptor (IR) signaling is critical to controlling nutrient uptake and metabolism. However, only a low-resolution (3.8 Å) structure currently exists for the IR ectodomain, with some segments ill-defined or unmodeled due to disorder. Here, we revise this structure using new diffraction data to 3.3 Å resolution that allow improved modeling of the N-linked glycans, the first and third fibronectin type III domains, and the insert domain. A novel haptic interactive molecular dynamics strategy was used to aid fitting to low-resolution electron density maps. The resulting model provides a foundation for investigation of structural transitions in IR upon ligand binding.

  10. Effects of insulin, insulin-like growth factor-Ⅰ and-Ⅱ on proliferation and intracellular signaling in endometrial carcinoma cells with different expression levels of insulin receptor isoform A

    Institute of Scientific and Technical Information of China (English)

    WANG Chun-fang; ZHANG Guo; ZHAO Li-jun; LI Xiao-ping; QI Wen-juan; WANG Jian-liu; WEI Li-hui

    2013-01-01

    Background Hyperinsulinemia,insulin-like growth factor (IGF)-Ⅰ and-Ⅱ (IGF-Ⅱ) are associated with increased risk of endometrial carcinoma.Insulin receptor isoform A (IR-A) is more frequently expressed in endometrial carcinoma than in normal endometrial tissues.To better understand their roles in endometrial carcinoma,we investigated the effects of insulin,IGF-Ⅰ,and IGF-Ⅱ in endometrial carcinomas cells with different IR-A expression levels.Methods To explore the role of IR-A in mediating the activity of IGF-Ⅰ,IGF-Ⅱ,and insulin,we investigate the cellular proliferation of endometrial carcinoma cell lines RL95-2 and RL95-2-IR-A by MTS assays.Then we examined the protein kinase Akt phosphorylation and extracellular signal-regulated kinase (ERK) 1/2 phosphorylation in both cell lines by Western blotting.The effect of IGF-Ⅱ and AG1024 on cell cycle progression and apoptosis was assessed by flowcytometry.To examine whether the effects of IGFs were mediated by IR-A,we blocked IGF-Ⅰ receptor (IGF-IR) in both cell lines using AG1024,an IGF-IR-specific inhibitor.Results IGF-Ⅰ and IGF-Ⅱ significantly enhanced proliferation of both cell lines (P <0.05).By contrast,insulin significantly increased proliferation of RL95-2-IR-A cells only (P <0.05).IGF-Ⅰ and IGF-Ⅱ significantly increased pAkt levels in RL95-2 cells and pERK1/2 levels in RL95-2-IR-A cells (all,P <0.05).Insulin increased pERK1/2 levels in RL95-2-IR-A cells only (P <0.05).LY294002 and PD98059 inhibited the specific signaling activities and cellular proliferation.After AG1024 pretreatment,neither IGF-Ⅰ nor IGF-Ⅱ affected pAkt levels in RL95-2 cells.IGF-Ⅱ,but not IGF-Ⅰ,increased pERK1/2 levels in RL95-2-IR-A cells.After AG1024 pretreatment,the proliferation rate and DNA content corresponding to the S phase increased and apoptosis decreased significantly in IGF-Ⅱ-treated RL95-2-IR-A cells only (P <0.05).Conclusions The proliferation effect of insulin is mediated by IR

  11. Testosterone treatment increases androgen receptor and aromatase gene expression in myotubes from patients with PCOS and controls, but does not induce insulin resistance

    DEFF Research Database (Denmark)

    Eriksen, Mette Brandt; Glintborg, Dorte; Nielsen, Michael Friberg Bruun;

    2014-01-01

    Polycystic ovary syndrome (PCOS) is associated with insulin resistance and increased risk of type 2 diabetes. Skeletal muscle is the major site of insulin mediated glucose disposal and the skeletal muscle tissue is capable to synthesize, convert and degrade androgens. Insulin sensitivity...... in the synthesis and conversion of testosterone (HSD17B1, HSD17B2, CYP19A1, SRD5A1-2, AR, ER-α, HSD17B6 and AKR1-3) in myotubes from ten patients with PCOS and ten matched controls. Testosterone treatment significantly increased aromatase and androgen receptor gene expression levels in patients and controls....... Glucose transport in myotubes was comparable in patients with PCOS vs. controls and was unchanged by testosterone treatment (p=0.21 PCOS vs. controls). These results suggest that testosterone treatment of myotubes increases the aromatase and androgen receptor gene expression without affecting insulin...

  12. RNA interference targeting mu-opioid receptors reverses the inhibition of fentanyl on glucose-evoked insulin release of rat islets

    Institute of Scientific and Technical Information of China (English)

    QIAN Tao-lai; ZHANG Lei; WANG Xin-hua; LIU Sheng; MA Liang; LU Ying

    2010-01-01

    Background Mu opioid receptor plays an important role in many physiological functions. Fentanyl is a widely used opioid receptor agonist for analgesia. This study was conducted to test the role of mu-opioid receptor on insulin release by determining whether fentanyl affected insulin release from freshly isolated rat pancreatic islets and if small interfering RNAs (siRNA) targeting mu-opioid receptor in the islets could knock down mu-opioid receptor expression.Methods Islets were isolated from ripe SD rats' pancreas by common bile duct intraductal collagenase V digestion and purified by discontinuous Ficoll density gradient centrifugation. The siRNA knock-down of mu-opioid receptor mRNA and protein in islet cells was analyzed by semi-quantitative real time-PCR and Western blotting. After siRNA-transfection for 48 hours, the islets were co-cultured with fentanyl as follows: 0 ng/ml, 3 ng/ml and 30 ng/ml for 48 hours. Then glucose-evoked insulin release was performed. As a control, the insulin release was also analyzed in islets without siRNA-trasfection after being co-cultured with fentanyl for 48 hours.Results After 48 hours of transfections, specific siRNA targeting of mu-opioid receptors produced significant reduction of mu-opioid receptor mRNA and protein (P <0.01). Fentanyl significantly inhibited glucose-evoked insulin release in islets in a concentration dependent manner (P <0.01). But after siRNA-transfection for 48 hours, the inhibition on glucose-evoked insulin reiease was reversed (P <0.01).Conclusions RNA interference specifically reduces mu-opioid receptor mRNA and protein expression, leading to reversal of the fentanyl-induced inhibition on glucose-evoked insulin release of rat islets. The activation of opioid receptor induced by fentanyl functions to inhibit insulin release. The use of RNAi presents a promising tool for future research in diabetic mechanisms and a novel therapy for diabetes.

  13. Chemokine-like receptor 1 deficiency does not affect the development of insulin resistance and nonalcoholic fatty liver disease in mice.

    Directory of Open Access Journals (Sweden)

    Nanda Gruben

    Full Text Available The adipokine chemerin and its receptor, chemokine-like receptor 1 (Cmklr1, are associated with insulin resistance and nonalcoholic fatty liver disease (NAFLD, which covers a broad spectrum of liver diseases, ranging from simple steatosis to nonalcoholic steatohepatitis (NASH. It is possible that chemerin and/or Cmklr1 exert their effects on these disorders through inflammation, but so far the data have been controversial. To gain further insight into this matter, we studied the effect of whole-body Cmklr1 deficiency on insulin resistance and NAFLD. In view of the primary role of macrophages in hepatic inflammation, we also transplanted bone marrow from Cmklr1 knock-out (Cmklr1-/- mice and wild type (WT mice into low-density lipoprotein receptor knock-out (Ldlr-/- mice, a mouse model for NASH. All mice were fed a high fat, high cholesterol diet containing 21% fat from milk butter and 0.2% cholesterol for 12 weeks. Insulin resistance was assessed by an oral glucose tolerance test, an insulin tolerance test, and by measurement of plasma glucose and insulin levels. Liver pathology was determined by measuring hepatic inflammation, fibrosis, lipid accumulation and the NAFLD activity score (NAS. Whole-body Cmklr1 deficiency did not affect body weight gain or food intake. In addition, we observed no differences between WT and Cmklr1-/- mice for hepatic inflammatory and fibrotic gene expression, immune cell infiltration, lipid accumulation or NAS. In line with this, we detected no differences in insulin resistance. In concordance with whole-body Cmklr1 deficiency, the absence of Cmklr1 in bone marrow-derived cells in Ldlr-/- mice did not affect their insulin resistance or liver pathology. Our results indicate that Cmklr1 is not involved in the pathogenesis of insulin resistance or NAFLD. Thus, we recommend that the associations reported between Cmklr1 and insulin resistance or NAFLD should be interpreted with caution.

  14. A novel unidirectional cross-talk from the insulin-like growth factor-I receptor to leptin receptor in human breast cancer cells.

    Science.gov (United States)

    Ozbay, Tuba; Nahta, Rita

    2008-06-01

    Obesity is a major risk factor for the development and progression of breast cancer. Increased circulating levels of the obesity-associated hormones leptin and insulin-like growth factor-I (IGF-I) and overexpression of the leptin receptor (Ob-R) and IGF-I receptor (IGF-IR) have been detected in a majority of breast cancer cases and during obesity. Due to correlations between increased leptin, Ob-R, IGF-I, and IGF-IR in breast cancer, we hypothesized that molecular interactions may exist between these two signaling pathways. Coimmunoprecipitation and immunoblotting showed that IGF-IR and Ob-R interact in the breast cancer cell lines MDA-MB-231, MCF7, BT474, and SKBR3. Stimulation of cells with IGF-I promoted Ob-R phosphorylation, which was blocked by IGF-IR kinase inhibition. In addition, IGF-I activated downstream signaling molecules in the leptin receptor and IGF-IR pathways. In contrast to IGF-I, leptin did not induce phosphorylation of IGF-IR, indicating that receptor cross-signaling is unidirectional, occurring from IGF-IR to Ob-R. Our results show, for the first time, a novel interaction and cross-talk between the IGF-I and leptin receptors in human breast cancer cells.

  15. Effects of Acute Pinitol Supplementation on Plasma Pinitol Concentration, Whole Body Glucose Tolerance, and Activation of the Skeletal Muscle Insulin Receptor in Older Humans

    OpenAIRE

    Stull, A. J.; Wood, K V; Thyfault, J. P.; Campbell, W.W.

    2009-01-01

    Limited research with rodents and humans suggests that oral ingestion of pinitol (3-O-methyl-d-chiro-inositol) might positively influence glucose tolerance. This double-blinded, placebo-controlled, and cross-over study assessed the effects of acute pinitol supplementation on plasma pinitol concentration, glucose tolerance, insulin sensitivity, and activation of the skeletal muscle insulin receptor. Fifteen older, nondiabetic subjects (62 ± 1 years, mean ± SEM) completed four, 1-day trials. Su...

  16. The Addition of Liquid Fructose to a Western-Type Diet in LDL-R(-/-) Mice Induces Liver Inflammation and Fibrogenesis Markers without Disrupting Insulin Receptor Signalling after an Insulin Challenge.

    Science.gov (United States)

    Sangüesa, Gemma; Baena, Miguel; Hutter, Natalia; Montañés, José Carlos; Sánchez, Rosa María; Roglans, Núria; Laguna, Juan Carlos; Alegret, Marta

    2017-03-15

    A high consumption of fat and simple sugars, especially fructose, has been related to the development of insulin resistance, but the mechanisms involved in the effects of these nutrients are not fully understood. This study investigates the effects of a Western-type diet and liquid fructose supplementation, alone and combined, on insulin signalling and inflammation in low-density lipoprotein (LDL) receptor-deficient mice (LDL-R(-/-)). LDL-R(-/-) mice were fed chow or Western diet ±15% fructose solution for 12 weeks. Plasma glucose and insulin, and the expression of genes related to inflammation in the liver and visceral white adipose tissue (vWAT), were analysed. V-akt murine thymoma viral oncogene homolog-2 (Akt) activation was measured in the liver of the mice after a single injection of saline or insulin. None of the dietary interventions caused inflammation in vWAT, whereas the Western diet induced hepatic inflammation, which was further enhanced by liquid fructose, leading also to a significant increase in fibrogenesis markers. However, there was no change in plasma glucose or insulin, or insulin-induced Akt phosphorylation. In conclusion, hepatic inflammation and fibrogenesis markers induced by a Western diet supplemented with liquid fructose in LDL-R(-/-) mice are not associated with a significant impairment of hepatic insulin signalling.

  17. 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.

    OpenAIRE

    Caro, J F; Ittoop, O; Pories, W J; Meelheim, D; Flickinger, E G; Thomas, F; 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...

  18. Reduced Insulin/Insulin-Like Growth Factor Receptor Signaling Mitigates Defective Dendrite Morphogenesis in Mutants of the ER Stress Sensor IRE-1

    Science.gov (United States)

    Salzberg, Yehuda; Cohen-Berkman, Moran; Biederer, Thomas; Bülow, Hannes E.

    2017-01-01

    Neurons receive excitatory or sensory inputs through their dendrites, which often branch extensively to form unique neuron-specific structures. How neurons regulate the formation of their particular arbor is only partially understood. In genetic screens using the multidendritic arbor of PVD somatosensory neurons in the nematode Caenorhabditis elegans, we identified a mutation in the ER stress sensor IRE-1/Ire1 (inositol requiring enzyme 1) as crucial for proper PVD dendrite arborization in vivo. We further found that regulation of dendrite growth in cultured rat hippocampal neurons depends on Ire1 function, showing an evolutionarily conserved role for IRE-1/Ire1 in dendrite patterning. PVD neurons of nematodes lacking ire-1 display reduced arbor complexity, whereas mutations in genes encoding other ER stress sensors displayed normal PVD dendrites, specifying IRE-1 as a selective ER stress sensor that is essential for PVD dendrite morphogenesis. Although structure function analyses indicated that IRE-1’s nuclease activity is necessary for its role in dendrite morphogenesis, mutations in xbp-1, the best-known target of non-canonical splicing by IRE-1/Ire1, do not exhibit PVD phenotypes. We further determined that secretion and distal localization to dendrites of the DMA-1/leucine rich transmembrane receptor (DMA-1/LRR-TM) is defective in ire-1 but not xbp-1 mutants, suggesting a block in the secretory pathway. Interestingly, reducing Insulin/IGF1 signaling can bypass the secretory block and restore normal targeting of DMA-1, and consequently normal PVD arborization even in the complete absence of functional IRE-1. This bypass of ire-1 requires the DAF-16/FOXO transcription factor. In sum, our work identifies a conserved role for ire-1 in neuronal branching, which is independent of xbp-1, and suggests that arborization defects associated with neuronal pathologies may be overcome by reducing Insulin/IGF signaling and improving ER homeostasis and function. PMID

  19. Differential effects of early-life NMDA receptor antagonism on aspartame-impaired insulin tolerance and behavior.

    Science.gov (United States)

    Collison, Kate S; Inglis, Angela; Shibin, Sherin; Andres, Bernard; Ubungen, Rosario; Thiam, Jennifer; Mata, Princess; Al-Mohanna, Futwan A

    2016-12-01

    We have previously showed that lifetime exposure to aspartame, commencing in utero via the mother's diet, may impair insulin tolerance and cause behavioral deficits in adulthood via mechanisms which are incompletely understood. The role of the CNS in regulating glucose homeostasis has been highlighted by recent delineation of the gut-brain axis, in which N-methyl-d-aspartic acid receptors (NMDARs) are important in maintaining glucose homeostasis, in addition to regulating certain aspects of behavior. Since the gut-brain axis can be modulated by fetal programming, we hypothesized that early-life NMDAR antagonism may affect aspartame-induced glucose deregulation in adulthood, and may alter the aspartame behavioral phenotype. Accordingly, C57Bl/6J mice were chronically exposed to aspartame commencing in utero, in the presence and absence of maternal administration of the competitive NMDAR antagonist CGP 39551, from conception until weaning. Drug/diet interactions in adulthood glucocentric and behavioral parameters were assessed. Aspartame exposure elevated blood glucose and impaired insulin-induced glucose disposal during an insulin tolerance test, which could be normalized by NMDAR antagonism. The same effects were not observed in control diet mice, suggesting an early-life drug/diet interaction. Behavioral analysis of adult offspring indicated that NMDAR antagonism of control diet mice caused hyperlocomotion and impaired spatial navigation. Conversely hypolocomotion, reduced exploratory activity and increased anxiety-related behavior were apparent in aspartame diet mice with early-life NMDAR antagonism.

  20. A highly pleiotropic amino acid polymorphism in the Drosophila insulin receptor contributes to life-history adaptation

    Science.gov (United States)

    Paaby, Annalise B.; Bergland, Alan O.; Behrman, Emily L.; Schmidt, Paul S.

    2016-01-01

    Finding the specific nucleotides that underlie adaptive variation is a major goal in evolutionary biology, but polygenic traits pose a challenge because the complex genotype–phenotype relationship can obscure the effects of individual alleles. However, natural selection working in large wild populations can shift allele frequencies and indicate functional regions of the genome. Previously, we showed that the two most common alleles of a complex amino acid insertion–deletion polymorphism in the Drosophila insulin receptor show independent, parallel clines in frequency across the North American and Australian continents. Here, we report that the cline is stable over at least a five-year period and that the polymorphism also demonstrates temporal shifts in allele frequency concurrent with seasonal change. We tested the alleles for effects on levels of insulin signaling, fecundity, development time, body size, stress tolerance, and life span. We find that the alleles are associated with predictable differences in these traits, consistent with patterns of Drosophila life-history variation across geography that likely reflect adaptation to the heterogeneous climatic environment. These results implicate insulin signaling as a major mediator of life-history adaptation in Drosophila, and suggest that life-history trade-offs can be explained by extensive pleiotropy at a single locus. PMID:25319083

  1. Fibroblast growth factor receptor 4 (FGFR4) deficiency improves insulin resistance and glucose metabolism under diet-induced obesity conditions.

    Science.gov (United States)

    Ge, Hongfei; Zhang, Jun; Gong, Yan; Gupte, Jamila; Ye, Jay; Weiszmann, Jennifer; Samayoa, Kim; Coberly, Suzanne; Gardner, Jonitha; Wang, Huilan; Corbin, Tim; Chui, Danny; Baribault, Helene; Li, Yang

    2014-10-31

    The role of fibroblast growth factor receptor 4 (FGFR4) in regulating bile acid synthesis has been well defined; however, its reported role on glucose and energy metabolism remains unresolved. Here, we show that FGFR4 deficiency in mice leads to improvement in glucose metabolism, insulin sensitivity, and reduction in body weight under high fat conditions. Mechanism of action studies in FGFR4-deficient mice suggest that the effects are mediated in part by increased plasma levels of adiponectin and the endocrine FGF factors FGF21 and FGF15, the latter of which increase in response to an elevated bile acid pool. Direct actions of increased bile acids on bile acid receptors, and other potential indirect mechanisms, may also contribute to the observed metabolic changes. The results described herein suggest that FGFR4 antagonists alone, or in combination with other agents, could serve as a novel treatment for diabetes.

  2. Testosterone treatment increases androgen receptor and aromatase gene expression in myotubes from patients with PCOS and controls, but does not induce insulin resistance.

    Science.gov (United States)

    Eriksen, Mette Brandt; Glintborg, Dorte; Nielsen, Michael Friberg Bruun; Jakobsen, Marianne Antonius; Brusgaard, Klaus; Tan, Qihua; Gaster, Michael

    2014-09-05

    Polycystic ovary syndrome (PCOS) is associated with insulin resistance and increased risk of type 2 diabetes. Skeletal muscle is the major site of insulin mediated glucose disposal and the skeletal muscle tissue is capable to synthesize, convert and degrade androgens. Insulin sensitivity is conserved in cultured myotubes (in vitro) from patients with PCOS, but the effect of testosterone on this insulin sensitivity is unknown. We investigated the effect of 7days testosterone treatment (100nmol/l) on glucose transport and gene expression levels of hormone receptors and enzymes involved in the synthesis and conversion of testosterone (HSD17B1, HSD17B2, CYP19A1, SRD5A1-2, AR, ER-α, HSD17B6 and AKR1-3) in myotubes from ten patients with PCOS and ten matched controls. Testosterone treatment significantly increased aromatase and androgen receptor gene expression levels in patients and controls. Glucose transport in myotubes was comparable in patients with PCOS vs. controls and was unchanged by testosterone treatment (p=0.21 PCOS vs. controls). These results suggest that testosterone treatment of myotubes increases the aromatase and androgen receptor gene expression without affecting insulin sensitivity and if testosterone is implicated in muscular insulin resistance in PCOS, this is by and indirect mechanism.

  3. Quasi-Steady-State Analysis based on Structural Modules and Timed Petri Net Predict System’s Dynamics: The Life Cycle of the Insulin Receptor

    Directory of Open Access Journals (Sweden)

    Jennifer Scheidel

    2015-12-01

    Full Text Available The insulin-dependent activation and recycling of the insulin receptor play an essential role in the regulation of the energy metabolism, leading to a special interest for pharmaceutical applications. Thus, the recycling of the insulin receptor has been intensively investigated, experimentally as well as theoretically. We developed a time-resolved, discrete model to describe stochastic dynamics and study the approximation of non-linear dynamics in the context of timed Petri nets. Additionally, using a graph-theoretical approach, we analyzed the structure of the regulatory system and demonstrated the close interrelation of structural network properties with the kinetic behavior. The transition invariants decomposed the model into overlapping subnetworks of various sizes, which represent basic functional modules. Moreover, we computed the quasi-steady states of these subnetworks and demonstrated that they are fundamental to understand the dynamic behavior of the system. The Petri net approach confirms the experimental results of insulin-stimulated degradation of the insulin receptor, which represents a common feature of insulin-resistant, hyperinsulinaemic states.

  4. Modulation of Insulin Receptor Substrate-1 and Some Inflammatory Variables in Hyperinsulinemic Rats Treated with Cinnamon Extract

    Directory of Open Access Journals (Sweden)

    Mohamed H. Mahfouz

    2010-01-01

    Full Text Available Cinnamon Extract (CE has shown to be generally safe when ingested and to have many pharmacological properties. Problem statement: Study the effects of daily intake of CE on the modulation of hepatic, cardiac Insulin Receptor Substrate-1 (IRS-1 and their relations to some inflammatory variables in hyperinsulinemic rats. Approach: The influence of CE administered orally was studied in hyperinsulinemic rats. Eighteen male Wistar rats were divided into 3 groups of 6 rats each. Group 1; control animals received starch as control diet, while Groups 2; rats were fed a "high-fructose diet"(60%. Group 3; fructose-fed rats received orally CE (0.5 mL/rat/day from the 16th day of fructose feeding in experimental period. The animals were maintained in their respective groups for 30 days. At the end of the experimental period, Serum levels of glucose, insulin, lipid profile, Total Antioxidant Capacity (TAC, Malondialdehyde (MDA, sialic acid and soluble Fas (sFas were assayed. Hepatic and cardiac IRS-1 levels were also evaluated. Results: Fed high fructose diet to rats induced significant elevations in serum levels of glucose, insulin, triacylglycerol, HDL-c, sialic acid, sFas and MDA, while the level of serum TAC was significantly reduced as compared to controls. Also significant reduction in the levels of hepatic and cardiac IRS-1 were recorded as compared to controls. Oral administration of cinnamon extract to fructose-fed rats alleviated the effects of fructose and these rats showed a normal level of the parameters studied. The percentage changes of IRS-1 level in fructose-fed rats before and after treatment with CE were 38.51 for liver and 31.92% for cardiac muscle. This increase in IRS-1 level after treatment is still lowered than control level with the percentage change -11.82 and -9.93% for liver and cardiac muscle respectively. There was a significant positive correlation between IRS-1 and TAC level whereas there was negative correlation between IRS-1

  5. The relationship between the L1 and L2 domains of the insulin and epidermal growth factor receptors and leucine-rich repeat modules

    Directory of Open Access Journals (Sweden)

    Ward Colin W

    2001-07-01

    Full Text Available Abstract Background Leucine-rich repeats are one of the more common modules found in proteins. The leucine-rich repeat consensus motif is LxxLxLxxNxLxxLxxLxxLxx- where the first 11–12 residues are highly conserved and the remainder of the repeat can vary in size Leucine-rich repeat proteins have been subdivided into seven subfamilies, none of which include members of the epidermal growth factor receptor or insulin receptor families despite the similarity between the 3D structure of the L domains of the type I insulin-like growth factor receptor and some leucine-rich repeat proteins. Results Here we have used profile searches and multiple sequence alignments to identify the repeat motif Ixx-LxIxx-Nx-Lxx-Lxx-Lxx-Lxx- in the L1 and L2 domains of the insulin receptor and epidermal growth factor receptors. These analyses were aided by reference to the known three dimensional structures of the insulin-like growth factor type I receptor L domains and two members of the leucine rich repeat family, porcine ribonuclease inhibitor and internalin 1B. Pectate lyase, another beta helix protein, can also be seen to contain the sequence motif and much of the structural features characteristic of leucine-rich repeat proteins, despite the existence of major insertions in some of its repeats. Conclusion Multiple sequence alignments and comparisons of the 3D structures has shown that right-handed beta helix proteins such as pectate lyase and the L domains of members of the insulin receptor and epidermal growth factor receptor families, are members of the leucine-rich repeat superfamily.

  6. De novo 19p13.2 microdeletion encompassing the insulin receptor and resistin genes in a patient with obesity and learning disability.

    Science.gov (United States)

    Wangensteen, Teresia; Retterstøl, Lars; Rødningen, Olaug K; Hjelmesaeth, Jøran; Aukrust, Pål; Halvorsen, Bente

    2013-06-01

    Genetic studies have provided novel insights of appetite regulation and pathophysiology of obesity. The adipose tissue is an active endocrine organ secreting several hormones contributing to insulin resistance and the development of the comorbidities of obesity, such as type 2 diabetes and cardiovascular disease. Herein, we report on a patient with severe obesity and mild learning disability with a 750 kb de novo deletion of chromosome 19. The deletion encompasses several genes, including resistin and the first part of the insulin receptor, genes that are relevant for obesity. This novel deletion may therefore represent a region for obesity research. Plasma analyses and gene expression demonstrated that the deletion resulted in haploinsufficiency for resistin and insulin receptor in the patient compared to controls. We then studied the biochemical and adipocytokine profile in these subjects. We observed no differences in glucose and lipid parameters between the patient and the controls. Thus, haploinsufficiency of insulin receptor and resistin does not appear to influence glucose and lipid metabolism. However, the patient had considerably higher values of adiponectin and TNFα than controls. In conclusion, we identified a 19p13.2 microdeletion encompassing the insulin receptor and resistin genes resulting in haploinsufficiency in an obese, but otherwise healthy patient. No firm conclusions could be drawn regarding the potential effect of the microdeletion on adipokine profile. Copyright © 2013 Wiley Periodicals, Inc.

  7. AT1 receptor blockade attenuates insulin resistance and myocardial remodeling in rats with diet-induced obesity.

    Directory of Open Access Journals (Sweden)

    Silvio A Oliveira-Junior

    Full Text Available BACKGROUND: Although obesity has been associated with metabolic and cardiac disturbances, the carrier mechanisms for these responses are poorly understood. This study analyzed whether angiotensin II blockade attenuates metabolic and cardiovascular disorders in rats with diet-induced obesity. MATERIAL AND METHODS: Wistar-Kyoto (n = 40 rats were subjected to control (C; 3.2 kcal/g and hypercaloric diets (OB; 4.6 kcal/g for 30 weeks. Subsequently, rats were distributed to four groups: C, CL, OB, and OBL. L groups received Losartan (30 mg/kg/day for five weeks. After this period we performed in vivo glucose tolerance and insulin tolerance tests, and measured triacylglycerol, insulin, angiotensin-converting enzyme activity (ACE, and leptin levels. Cardiovascular analyzes included systolic blood pressure (SBP, echocardiography, myocardial morphometric study, myosin heavy chain composition, and measurements of myocardial protein levels of angiotensin, extracellular signal-regulated (ERK1/2, c-Jun amino-terminal kinases (JNK, insulin receptor subunit β (βIR, and phosphatidylinositol 3-kinase (PI3K by Western Blot. RESULTS: Glucose metabolism, insulin, lipid, and ACE activity disorders observed with obesity were minimized by Losartan. Moreover, obesity was associated with increased SBP, myocardial hypertrophy, interstitial fibrosis and improved systolic performance; these effects were also minimized with Losartan. On a molecular level, OB exhibited higher ERK, Tyr-phosphorylated βIR, and PI3K expression, and reduced myocardial angiotensin and JNK expression. ERK and JNK expression were regulated in the presence of Losartan, while angiotensin, Tyr-βRI, total and Tyr-phosphorylated PI3K expression were elevated in the OBL group. CONCLUSION: Angiotensin II blockade with Losartan attenuates obesity-induced metabolic and cardiovascular changes.

  8. Targeting the insulin-like growth factor-1 receptor to overcome bortezomib resistance in preclinical models of multiple myeloma.

    Science.gov (United States)

    Kuhn, Deborah J; Berkova, Zuzana; Jones, Richard J; Woessner, Richard; Bjorklund, Chad C; Ma, Wencai; Davis, R Eric; Lin, Pei; Wang, Hua; Madden, Timothy L; Wei, Caimiao; Baladandayuthapani, Veerabhadran; Wang, Michael; Thomas, Sheeba K; Shah, Jatin J; Weber, Donna M; Orlowski, Robert Z

    2012-10-18

    Proteasome inhibition with bortezomib is a validated approach to the treatment of multiple myeloma, but drug resistance often emerges and limits its utility in the retreatment setting. To begin to identify some of the mechanisms involved, we developed bortezomib-resistant myeloma cell lines that, unlike previously reported models, showed no β5 subunit mutations. Instead, up-regulation of the insulin-like growth factor (IGF)-1 axis was identified, with increased autocrine and paracrine secretion of IGF-1, leading to increased activation of the IGF-1 receptor (IGF-1R). Exogenous IGF-1 reduced cellular sensitivity to bortezomib, whereas pharmacologic or small hairpin RNA-mediated IGF-1R suppression enhanced bortezomib sensitivity in cell lines and patient samples. In vitro studies with OSI-906, a clinically relevant dual IGF-1R and insulin receptor inhibitor, showed it acted synergistically with bortezomib, and potently resensitized bortezomib-resistant cell lines and patient samples to bortezomib. Importantly, OSI-906 in combination with bortezomib also overcame bortezomib resistance in an in vivo model of myeloma. Taken together, these data support the hypothesis that signaling through the IGF-1/IGF-1R axis contributes to acquired bortezomib resistance, and provide a rationale for combining bortezomib with IGF-1R inhibitors like OSI-906 to overcome or possibly prevent the emergence of bortezomib-refractory disease in the clinic.

  9. Codon 972 polymorphism in the insulin receptor substrate-1 gene, obesity, and risk of noninsulin-dependent diabetes mellitus

    Energy Technology Data Exchange (ETDEWEB)

    Sigal, R.J.; Doria, A.; Warram, J.H.; Krolewski, A.S. [Joslin Diabetes Center, Boston, MA (United States)

    1996-04-01

    Because of the role of insulin receptor substrate-1 in insulin action, the insulin receptor substrate-1 gene is a candidate gene for noninsulin-dependent diabetes mellitus (NIDDM). Modest associations between NIDDM and a GGG-AGG single base substitution (corresponding to a glycine-arginine amino acid substitution) in codon 972 of the gene have been found, but none reached statistical significance. To examine further how large a proportion of NIDDM cases could be caused by the mutation, we performed a stratified analysis combining the results from the 6 earlier studies and those from our panel of 192 unrelated NIDDM subjects and 104 healthy controls. In addition, we looked for a possibility that the codon 972 mutation plays a role only in the presence of certain conditions. Genomic DNA samples obtained from NIDDM cases and healthy controls were genotyped using a PCR-restriction fragment length polymorphism protocol modified for genomic DNA. The GGG{r_arrow}AGG substitution was found in 5.7% of the diabetic subjects (11 of 192) and 6.9% of the controls (7 of 104). The difference between groups was not statistically significant, and it was not different from the results of other studies. The Mantel-Haenszel summary odds ratio across all studies was 1.49 (P < 0.05; 95% confidence intervals, 1.01-2.2). This summary odds ratio is consistent with a small proportion of NIDDM cases ({approximately}3%) being caused by the mutation. Exploratory subgroup analyses on our panel suggested a clustering of NIDDM, the codon 972 mutation, and overweight, raising the hypothesis that the mutation may predispose to NIDDM only in the presence of excess body weight. 9 refs., 2 tabs.

  10. Abnormal glucose tolerance and insulin resistance in polycystic ovary syndrome amongst the Taiwanese population- not correlated with insulin receptor substrate-1 Gly972Arg/Ala513Pro polymorphism

    Directory of Open Access Journals (Sweden)

    Liang Shu-Fen

    2006-04-01

    Full Text Available Abstract Background Insulin resistance and glucose dysmetabolism in polycystic ovary syndrome (PCOS are related with the polymorphisms in the genes encoding the insulin receptor substrate (IRS proteins, especially Gly972Arg/Ala513Pro polymorphism being reported to be associated with type-2 diabetes and PCOS. We intended to assess the prevalence of abnormal glucose tolerance (AGT and insulin resistance in Taiwanese PCOS women. We also tried to assess whether the particular identity of Gly972Arg/Ala513Pro polymorphic alleles of the IRS-1 gene mutation can be used as an appropriate diagnostic indicator for PCOS. Methods We designed a prospective clinical study. Forty-seven Taiwanese Hoklo and Hakka women, diagnosed with PCOS were enrolled in this study as were forty-five healthy Hoklo and Hakka women as the control group. Insulin resistance was evaluated with fasting insulin, fasting glucose/insulin ratio, and homeostasis model assessment index for insulin resistance (HOMAIR. The genomic DNA of the subjects was amplified by PCR and digested by restriction fragmented length polymorphism (RFLP with Bst N1 used for codon 972 and Dra III for codon 513. Results AGT was found in 46.8% of these PCOS patients and was significantly related to high insulin resistance rather than the low insulin resistance. Those patients with either insulin resistance or AGT comprised the majority of PCOS affected patients (AGT + fasting insulin ≥17: 83%, AGT + glucose/insulin ratio ≥6.5: 85.1%, AGT + HOMAIR ≥ 2: 87.2%, and AGT + HOMAIR ≥ 3.8: 72.3%. None of the tested samples revealed any polymorphism due to the absence of any Dra III recognition site or any Bst N1 recognition site in the amplified PCR fragment digested by restriction fragmented length polymorphism. Conclusion There is significantly high prevalence of AGT and insulin resistance in PCOS women, but Gly972Arg and Ala513Pro polymorphic alleles of IRS-1 are rare and are not associated with the elevated

  11. Effects of the selective estrogen receptor modulator, raloxifene, on the somatotropic axis and insulin-glucose homeostasis.

    Science.gov (United States)

    Oleksik, A M; Duong, T; Pliester, N; Asma, G; Popp-Snijders, C; Lips, P

    2001-06-01

    Raloxifene is the first selective estrogen receptor modulator registered for the prevention and treatment of postmenopausal osteoporosis. In addition to direct effects on bone cells, estrogen and raloxifene may act indirectly via changes in hormonal homeostasis. However, the menopause-related decrease in serum insulin-like growth factor I (IGF-I) and the increase in insulin or glucose are not always reversed by estrogen replacement. Especially orally administered estrogen was reported to decrease serum IGF-I levels. Understanding the effects of estrogens and raloxifene on the GH-IGF axis and insulin-glucose homeostasis are important because of their link to bone metabolism and cardiovascular health. We investigated the effects of raloxifene on the GH-IGF-I axis and insulin-glucose homeostasis in a cross-sectional study in the third year of the Multiple Outcomes of Raloxifene Evaluation trial, a double blind, placebo-controlled, prospective study in postmenopausal women with osteoporosis (T-score of -2.5 or less or at least two moderate vertebral fractures). Patients with diabetes mellitus were excluded from this additional study. A fasting blood sample was obtained (0 h), and women received an sc injection of 0.05 mg recombinant human GH (Humatrope)/kg BW. The second blood sample was obtained 24 h later (24 h). GH, IGF-I, IGF-binding protein-3 (IGFBP-3), insulin, and glucose were measured. Group characteristics were tested by nonparametric ANOVA. The dose-response to raloxifene was tested by linear regression models, with age and body mass as covariates. Seven women were taking placebo, 16 were taking raloxifene (60 mg/day), and 9 were taking raloxifene (120 mg/day). Patients from the 60 mg raloxifene group were the oldest (mean +/- SD, 64.4 +/- 4.2 vs. 69.3 +/- 6.9 and 63.3 +/- 5.9 yr for placebo, 60 mg/day raloxifene, and 120 mg/day raloxifene, respectively; P = 0.05). Compared with placebo users, patients taking raloxifene had higher body mass index (24.7 +/- 1

  12. Experimental diabetes increases insulin-like growth factor I and II receptor concentration and gene expression in kidney

    Energy Technology Data Exchange (ETDEWEB)

    Werner, H.; Shen-Orr, Z.; Stannard, B.; Burguera, B.; Roberts, C.T. Jr.; LeRoith, D. (National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD (USA))

    1990-12-01

    Insulinlike growth factor I (IGF-I) is a mitogenic hormone with important regulatory roles in growth and development. One of the target organs for IGF-I action is the kidney, which synthesizes abundant IGF-I receptors and IGF-I itself. To study the involvement of IGF-I and the IGF-I receptor in the development of nephropathy, one of the major complications of diabetes mellitus, we measured the expression of these genes in the kidney and in other tissues of the streptozocin-induced diabetic rat. The binding of 125I-labeled IGF-I to crude membranes was measured in the same tissues. We observed a 2.5-fold increase in the steady-state level of IGF-I-receptor mRNA in the diabetic kidney, which was accompanied by a 2.3-fold increase in IGF-I binding. In addition to this increase in IGF-I binding to the IGF-I receptor, there was also binding to a lower-molecular-weight material that may represent an IGF-binding protein. No change was detected in the level of IGF-I-peptide mRNA. Similarly, IGF-II-receptor mRNA levels and IGF-II binding were significantly increased in the diabetic kidney. IGF-I- and IGF-II-receptor mRNA levels and IGF-I and IGF-II binding returned to control values after insulin treatment. Because the IGF-I receptor is able to transduce mitogenic signals on activation of its tyrosine kinase domain, we hypothesize that, among other factors, high levels of receptor in the diabetic kidney may also be involved in the development of diabetic nephropathy. Increased IGF-II-receptor expression in the diabetic kidney may be important for the intracellular transport and packaging of lysosomal enzymes, although a role for this receptor in signal transduction cannot be excluded. Finally, the possible role of IGF-binding proteins requires further study.

  13. Insulin up-regulates natriuretic peptide clearance receptor expression in the subcutaneous fat depot in obese subjects: a missing link between CVD risk and obesity?

    Science.gov (United States)

    Pivovarova, Olga; Gögebakan, Özlem; Klöting, Nora; Sparwasser, Andrea; Weickert, Martin O; Haddad, Isam; Nikiforova, Victoria J; Bergmann, Andreas; Kruse, Michael; Seltmann, Anne-Cathrin; Blüher, Matthias; Pfeiffer, Andreas F H; Rudovich, Natalia

    2012-05-01

    Natriuretic peptides (NP) regulate cardiovascular homeostasis and have multiple metabolic properties. Decreased levels of NP or "natriuretic handicap" are signs of insulin resistance such as central obesity. Increased expression of NP clearance receptor (NPRC) in sc adipose tissue (SAT) was observed in insulin-resistant subjects. We hypothesized that insulin acutely regulates NP receptor expression in adipose tissue. NPRA, NPRB, and NPRC mRNA expression was measured in paired samples of visceral adipose tissue (VAT) and SAT from 157 subjects (108 with type 2 diabetes). The effect of insulin on NPR gene expression in SAT was studied in euglycemic-hyperinsulinemic and hyperglycemic-hyperinsulinemic clamp experiments. Additionally, the effect of insulin and glucose on NPR expression in the culture of primary human monocytes and macrophages was tested. NPRA and NPRC gene expression was higher in VAT compared with SAT (P < 0.01), but only NPRC gene expression strongly correlated with fasting insulin levels (r = 0.65, P = 0.04 × 10(-3); and r = 0.54, P = 0.002, for VAT and SAT, respectively). NPRB expression was lower in VAT than in SAT in subjects with type 2 diabetes and was lower compared with nondiabetic subjects. NPRC gene expression was up-regulated in SAT during both euglycemic- and hyperglycemic-hyperinsulinemic clamps (P = 0.038 and P = 0.048, respectively), and was increased in high glucose and insulin treatment in monocytes (70.2%; P = 0.01), but not in mature macrophages. Insulin increased expression of NPRC in SAT independently of circulating glucose concentrations. Thus, insulin might suppress circulating NP via up-regulation of NPRC expression in obesity, providing a novel link between hyperinsulinemia and obesity.

  14. Divergent Roles of IRS (Insulin Receptor Substrate) 1 and 2 in Liver and Skeletal Muscle.

    Science.gov (United States)

    Eckstein, Sabine Sarah; Weigert, Cora; Lehmann, Rainer

    2017-01-01

    IRS1 and IRS2 are the most important representatives of the IRS protein family and critical nodes in insulin/IGF1-signaling. Although they are quite similar in their structural and functional features they show tissue-specific differences. In this review, we outline the functions of IRS1 and IRS2 in skeletal muscle and liver with regard to their importance for metabolism, growth and differentiation. Mechanisms contributing to IRS1 and IRS2 dysregulation in disease states as well as consequences thereof are discussed. IRS1 plays the dominant role in skeletal muscle. It is crucial for normal growth and differentiation of myofibers, insulin-dependent glucose uptake and glycogen synthesis. The presence of IRS2 in skeletal muscle is negligible for insulin-induced glucose uptake and the general role of IRS2 in muscle is still not fully understood. In liver IRS1 and IRS2 are important to mediate insulindependent regulation of glucose and lipid metabolism and complement each other in the diurnal regulation thereof. IRS1 in the liver is more important for signaling in the late refeeding period, whereas IRS2 signaling is mostly dominating in the period directly after food intake and during fasting. Importantly, the expression level of IRS1 and IRS2 is different within the liver lobule, which could be an explanation for the phenomenon of selective insulin resistance. Dysregulated muscular or hepatic abundance and/or phosphorylation status of IRS1 and IRS2 are important factors in the pathogenesis of insulin resistance, type 2 diabetes and muscle wasting. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  15. Effect of Kaiyu Qingwei Granule (开郁清胃颗粒) on Insulin Receptor in Liver and Skeletal Muscular Cell Membrane in Diabetes Mellitus Rats

    Institute of Scientific and Technical Information of China (English)

    LIU Hong-fang (柳红芳); TONG Xiao-lin(仝小林); WANG Qing-guo(王庆国); ZUO Ping-ping(左萍萍); GUO An-chen(郭安臣); LIU Hong-xing(刘红星)

    2003-01-01

    Objective: To investigate the effect of Kaiyu Qingwei granule (KYQWG,开郁清胃颗粒) on the insulin binding capacity of liver and skeletal muscular cell membrane and serum insulin-like growth factor-1 (IGF-1) in streptozotocin-induced diabetic rats. Methods:Rats in four experimental groups were investigated: the control group, the model group, the KYQWG group and the Metformin group. The insulin binding rate (IBR) of liver and skeletal muscular cell membrane was detected by receptor-ligand radiometric method and changes of serum levels of glucose, insulin and IGF-1 were observed before and after 4 weeks of medication. Results: The KYQWG group had a lower blood glucose level and IBR of liver and muscular cell membrane, as compared with those in the model group (P<0.01 or P<0.05), and a higher level of IGF-1 than that in the model group(P<0.01), but had no obvious changes in the serum level of insulin. Conclusion: KYQWG may increase the serum level of IGF-1 in diabetic rats, thus to decrease the insulin resistance at ante-receptor sites and improve the sugar metabolic disturbance in rats with diabetes mellitus.

  16. Orexin A modulates INS-1E cell proliferation and insulin secretion via extracellular signal-regulated kinase and transient receptor potential channels.

    Science.gov (United States)

    Skrzypski, M; Khajavi, N; Mergler, S; Billert, M; Szczepankiewicz, D; Wojciechowicz, T; Nowak, K W; Strowski, M Z

    2016-10-01

    Orexins A (OXA) and B (OXB) control energy homeostasis by regulating food intake, energy expenditure and sleep-wake cycle. Several studies showed that OXA stimulates insulin secretion and proliferation of beta cells. However, mechanisms of action are still not well understood. Here, we investigated whether ERK and transient receptor potential channels (TRPs) play a role in mediating the effect of OXA on cell growth, insulin production, and secretion using the established INS-1E cell line. Cell proliferation was measured using BrdU assay. Insulin mRNA expression was detected by real-time PCR. Insulin secretion was assessed using ELISA. Intracellular calcium levels were measured using fluorescence calcium imaging (fura-2/AM). Extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation was detected by Western blot. TRP channel activity was blocked by lanthanum (III) chloride (La(3+); 100 - 300 μM) or ruthenium red (RuR; 10 μM). OXA (100 nM) stimulated INS-1E cell proliferation, insulin secretion, intracellular Ca(2+) concentration and ERK1/2 phosphorylation, without changing insulin mRNA expression. Inhibition of ERK1/2 by 10 μM U0126 attenuated OXA-stimulated INS-1E cell proliferation. Blockade of TRP channel activity by La(3+) or RuR rendered OXA ineffective at modulating Ca(2+) regulation and insulin release. In contrast, the L-type channel blocker nifedipine (10 μM) failed to affect OXA-stimulated insulin release. Taken together, OXA increases INS-1E cell proliferation via ERK1/2-dependent mechanism. Furthermore, OXA stimulates insulin secretion from INS-1E cells. TRPs are relevant for OXA-stimulated insulin secretion and intracellular calcium regulation.

  17. INS-1 cell glucose-stimulated insulin secretion is reduced by the downregulation of the 67 kDa laminin receptor.

    Science.gov (United States)

    Sabra, Georges; Dubiel, Evan A; Kuehn, Carina; Khalfaoui, Taoufik; Beaulieu, Jean-François; Vermette, Patrick

    2015-12-01

    Understanding β cell-extracellular matrix (ECM) interactions can advance our knowledge of the mechanisms that control glucose homeostasis and improve culture methods used in islet transplantation for the treatment of diabetes. Laminin is the main constituent of the basement membrane and is involved in pancreatic β cell survival and function, even enhancing glucose-stimulated insulin secretion. Most of the studies on cell responses towards laminin have focused on integrin-mediated interactions, while much less attention has been paid on non-integrin receptors, such as the 67 kDa laminin receptor (67LR). The specificity of the receptor-ligand interaction through the adhesion of INS-1 cells (a rat insulinoma cell line) to CDPGYIGSR-, GRGDSPC- or CDPGYIGSR + GRGDSPC-covered surfaces was evaluated. Also, the effects of the 67LR knocking down over glucose-stimulated insulin secretion were investigated. Culture of the INS-1 cells on the bioactive surfaces was improved compared to the low-fouling carboxymethyl dextran (CMD) surfaces, while downregulation of the 67LR resulted in reduced cell adhesion to surfaces bearing the CDPGYIGSR peptide. Glucose-stimulated insulin secretion was hindered by downregulation of the 67LR, regardless of the biological motif available on the biomimetic surfaces on which the cells were cultured. This finding illustrates the importance of the 67LR in glucose-stimulated insulin secretion and points to a possible role of the 67LR in the mechanisms of insulin secretion.

  18. Specific suppression of insulin sensitivity in growth hormone receptor gene-disrupted (GHR-KO) mice attenuates phenotypic features of slow aging.

    Science.gov (United States)

    Arum, Oge; Boparai, Ravneet K; Saleh, Jamal K; Wang, Feiya; Dirks, Angela L; Turner, Jeremy G; Kopchick, John J; Liu, Jun-Li; Khardori, Romesh K; Bartke, Andrzej

    2014-12-01

    In addition to their extended lifespans, slow-aging growth hormone receptor/binding protein gene-disrupted (knockout) (GHR-KO) mice are hypoinsulinemic and highly sensitive to the action of insulin. It has been proposed that this insulin sensitivity is important for their longevity and increased healthspan. We tested whether this insulin sensitivity of the GHR-KO mouse is necessary for its retarded aging by abrogating that sensitivity with a transgenic alteration that improves development and secretory function of pancreatic β-cells by expressing Igf-1 under the rat insulin promoter 1 (RIP::IGF-1). The RIP::IGF-1 transgene increased circulating insulin content in GHR-KO mice, and thusly fully normalized their insulin sensitivity, without affecting the proliferation of any non-β-cell cell types. Multiple (nonsurvivorship) longevity-associated physiological and endocrinological characteristics of these mice (namely beneficial blood glucose regulatory control, altered metabolism, and preservation of memory capabilities) were partially or completely normalized, thus supporting the causal role of insulin sensitivity for the decelerated senescence of GHR-KO mice. We conclude that a delayed onset and/or decreased pace of aging can be hormonally regulated.

  19. Dual silencing of insulin-like growth factor-I receptor and epidermal growth factor receptor in colorectal cancer cells is associated with decreased proliferation and enhanced apoptosis.

    Science.gov (United States)

    Kaulfuss, Silke; Burfeind, Peter; Gaedcke, Jochen; Scharf, Jens-Gerd

    2009-04-01

    Overexpression and activation of tyrosine kinase receptors are common features of colorectal cancer. Using the human colorectal cancer cell lines DLD-1 and Caco-2, we evaluated the role of the insulin-like growth factor-I (IGF-I) receptor (IGF-IR) and epidermal growth factor receptor (EGFR) in cellular functions of these cells. We used the small interfering RNA (siRNA) technology to specifically down-regulate IGF-IR and EGFR expression. Knockdown of IGF-IR and EGFR resulted in inhibition of cell proliferation of DLD-1 and Caco-2 cells. An increased rate of apoptosis was associated with siRNA-mediated silencing of IGF-IR and EGFR as assessed by activation of caspase-3/caspase-7. The combined knockdown of both EGFR and IGF-IR decreased cell proliferation and induced cell apoptosis more effectively than did silencing of either receptor alone. Comparable effects on cell proliferation and apoptosis were observed after single and combinational treatment of cells by the IGF-IR tyrosine kinase inhibitor NVP-AEW541 and/or the EGFR tyrosine kinase inhibitor erlotinib. Combined IGF-IR and EGFR silencing by either siRNAs or tyrosine kinase inhibitors diminished the phosphorylation of downstream signaling pathways AKT and extracellular signal-regulated kinase (ERK)-1/2 more effectively than did the single receptor knockdown. Single IGF-IR knockdown inhibited IGF-I-dependent phosphorylation of AKT but had no effect on IGF-I- or EGF-dependent phosphorylation of ERK1/2, indicating a role of EGFR in ligand-dependent ERK1/2 phosphorylation. The present data show that inhibition of the IGF-IR transduction cascade augments the antipoliferative and proapoptotic effects of EGFR inhibition in colorectal cancer cells. A clinical application of combination therapy targeting both EGFR and IGF-IR could be a promising therapeutic strategy.

  20. Effects of acute pinitol supplementation on plasma pinitol concentration, whole body glucose tolerance, and activation of the skeletal muscle insulin receptor in older humans.

    Science.gov (United States)

    Stull, A J; Wood, K V; Thyfault, J P; Campbell, W W

    2009-05-01

    Limited research with rodents and humans suggests that oral ingestion of pinitol (3- O-methyl- D- CHIRO-inositol) might positively influence glucose tolerance. This double-blinded, placebo-controlled, and cross-over study assessed the effects of acute pinitol supplementation on plasma pinitol concentration, glucose tolerance, insulin sensitivity, and activation of the skeletal muscle insulin receptor. Fifteen older, nondiabetic subjects (62+/-1 years, mean+/-SEM) completed four, 1-day trials. Subjects consumed a non-nutritive beverage with nothing (placebo) or 1,000 mg pinitol. Sixty minutes later, the subjects consumed beverages that were either energy- and carbohydrate-free (Sham) or contained 75 g glucose (OGTT). Blood samples were collected frequently over the 240-min testing period. For the OGTT trials only, vastus lateralis samples were obtained before the placebo and pinitol supplementation and 60 min after consuming the 75 g glucose beverage. Plasma pinitol concentration increased and was maintained for 240 min. Pinitol did not influence the fasting state and 180-min area under the curves for plasma glucose and insulin during the Sham and OGTT trials or hepatic (placebo 0.83+/-0.08; pinitol 0.80+/-0.08) and whole-body (placebo 6.10+/-0.54; pinitol 6.22+/-0.52) insulin sensitivities. Activation of the muscle insulin receptor was increased by 140% with glucose ingestion (Pre 0.62+/-0.12; Post 1.49+/-0.35), but pinitol did not influence this response. These results show that the pinitol supplement was quickly absorbed, but did not acutely influence indices of whole-body glucose tolerance and insulin sensitivity, or the activation of the skeletal muscle insulin receptor in older, nondiabetic humans.

  1. In silico prediction of B cell epitopes of the extracellular domain of insulin-like growth factor-1 receptor

    Directory of Open Access Journals (Sweden)

    Vahid Bayrami

    2016-12-01

    Full Text Available The insulin-like growth factor-1 receptor (IGF-1R is a transmembrane receptor with tyrosine kinase activity. The receptor plays a critical role in cancer. Using monoclonal antibodies (MAbs against the IGF-1R, typically blocks ligand binding and enhances down-regulation of the cell-surface IGF-1R. Some MAbs such as cixutumumab are under clinical trial investigation. Targeting multiple distinct epitopes on IGF-1R, might be an effective strategy to inhibit IGF-1R pathway in cancer. In this study, new linear B cell epitopes for the extracellular domains of IGF-1R were predicted by in silico methods using a combination of linear B cell epitope prediction web servers such as ABCpred, Bepired, BCPREDs, Bcepred and Elliprro. Moreover, Discotope, B-pred and PEPOP web server tools were employed to predict new conformational B cell epitopes. In contrast to previously reported epitopes from extracellular region of the IGF-1R, we predicted new linear P8: (RQPQDGYLYRHNYCSK and conformational Pc4: (HYYYAGVCVPACPPNTYRFE, Ppc6: (KMCPSTGKRENNESAPDNDT and Ppc20: (ANILSAESSDSEFMQEPSGFI epitopes. These epitopes are useful for further study as peptide antigens to actively immune host animals to develop new MAbs. Furthermore, the epitopes can be used in peptide-based cancer vaccines design.

  2. Expression and regulation of mRNAs for insulin-like growth factor-I receptor and LH receptor in corpora lutea

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Relationship between insulin-like growth factor-I receptor (IGF-IR) and luteinizing hormone receptor (LHR) mRNA expression as well as their regulation was determined in rat corpora lutea (CL) . In the CL of estrous cycle rat, LHR mRNA positive CL expressed high level of mRNA of IGF-IR. While the expression of LHR mRNA decreased on estrus, the CL still expressed relatively high level of IGF-IR mRNA. In pseudopregnant rat CL, the expression level of LHR mRNA was low on day 1, the most intense signals were detected on day 8, the signals of LHR mRNA became undetectable on day 14. In contrast to LHR expression, the high level of IGF-IR mRNA was observed in pseudopregnant CL of day 1, and thereafter its signals were detected from day 2 to day 14. Pregnant rat CL expressed both LHR and IGF-IR mRNAs. IGF-I stimulated LHR expression in CL. PGF2 inhibited expression of IGF-IR and LHR. PGE2 negated the inhibiting effects of PGF2. These data suggest that IGF-I may be involved in regulating CL function, and maintaining CL structure through changes in expression of its receptors. Inhibited expression of IGF-IR by PGF2 may be part of mechanisms for regression of CL.

  3. Ovarian receptors for insulin and insulin-like growth factor I (IGF-I) and effects of IGF-I on steroid production by isolated follicular layers of the preovulatory coho salmon ovarian follicle.

    Science.gov (United States)

    Maestro, M A; Planas, J V; Moriyama, S; Gutiérrez, J; Planas, J; Swanson, P

    1997-05-01

    In this study, receptors for insulin and insulin-like growth factor I (IGF-I) in isolated theca-interstitial layers and granulosa cells of the coho salmon preovulatory ovary were characterized, and the effects of IGF-I on ovarian steroidogenesis were examined. Specific receptors for insulin and IGF-I were found in granulosa and theca-interstitial layers. In both follicular layers, IGF-I receptors were greater in number and higher in affinity than insulin receptors. The effects of IGF-I on in vitro production of testosterone (T) and 17 alpha-hydroxyprogesterone (17OH-P) by theca-interstitial layers and of 17 beta-estradiol (E2) and 17 alpha, 20 beta-dihydroxy-4-pregnen-3-one (17,20 beta-P) by granulosa cell layers were evaluated during the preovulatory period. Both human and salmon recombinant IGF-I inhibited the basal and GTH II-stimulated T and 17OH-P production by theca-interstitial layers throughout the preovulatory period. In contrast, IGF-I stimulated the production of both E2 and 17,20 beta-P by granulosa cell layers prior to germinal vesicle breakdown (GVBD) but only stimulated the production of 17,20 beta-P by granulosa cell layers after GVBD. The inhibitory effects of IGF-I on steroid production by the theca-interstitial layer and the opposite stimulatory effects on steroid production by the granulosa cell layer, coupled by the presence of specific IGF-I receptors in both follicular layers, suggest that IGF-I may play a role in the regulation of steroidogenesis in the preovulatory coho salmon ovary.

  4. Green tea epigallocatechin gallate inhibits insulin stimulation of adipocyte glucose uptake via the 67-kilodalton laminin receptor and AMP-activated protein kinase pathways.

    Science.gov (United States)

    Hsieh, Chi-Fen; Tsuei, Yi-Wei; Liu, Chi-Wei; Kao, Chung-Cheng; Shih, Li-Jane; Ho, Low-Tone; Wu, Liang-Yi; Wu, Chi-Peng; Tsai, Pei-Hua; Chang, Hsin-Huei; Ku, Hui-Chen; Kao, Yung-Hsi

    2010-10-01

    Insulin and (-)-epigallocatechin gallate (EGCG) are reported to regulate obesity and fat accumulation, respectively. This study investigated the pathways involved in EGCG modulation of insulin-stimulated glucose uptake in 3T3-L1 and C3H10T1/2 adipocytes. EGCG inhibited insulin stimulation of adipocyte glucose uptake in a dose- and time-dependent manner. The concentration of EGCG that decreased insulin-stimulated glucose uptake by 50-60% was approximately 5-10 µM for a period of 2 h. At 10 µM, EGCG and gallic acid were more effective than (-)-epicatechin, (-)-epigallocatechin, and (-)-epicatechin 3-gallate. We identified the EGCG receptor [also known as the 67-kDa laminin receptor (67LR)] in fat cells and extended the findings for this study to clarify whether EGCG-induced changes in insulin-stimulated glucose uptake in adipocytes could be mediated through the 67LR. Pretreatment of adipocytes with a 67LR antibody, but not normal rabbit immunoglobulin, prevented the effects of EGCG on insulin-increased glucose uptake. This suggests that the 67LR mediates the effect of EGCG on insulin-stimulated glucose uptake in adipocytes. Moreover, pretreatment with an AMP-activated protein kinase (AMPK) inhibitor, such as compound C, but not with a glutathione (GSH) activator, such as N-acetyl-L-cysteine (NAC), blocked the antiinsulin effect of EGCG on adipocyte glucose uptake. These data suggest that EGCG exerts its anti-insulin action on adipocyte glucose uptake via the AMPK, but not the GSH, pathway. The results of this study possibly support that EGCG mediates fat content. © Georg Thieme Verlag KG Stuttgart · New York.

  5. Sex-specific effects of naturally occurring variants in the dopamine receptor D2 locus on insulin secretion and Type 2 diabetes susceptibility

    DEFF Research Database (Denmark)

    Guigas, B; de Leeuw van Weenen, J E; van Leeuwen, N

    2014-01-01

    AIMS: Modulation of dopamine receptor D2 (DRD2) activity affects insulin secretion in both rodents and isolated pancreatic β-cells. We hypothesized that single nucleotide polymorphisms in the DRD2/ANKK1 locus may affect susceptibility to Type 2 diabetes in humans. METHODS: Four potentially...

  6. CNTO736, a novel glucagon-like peptide-1 receptor agonist, ameliorates insulin resistance and inhibits very low-density lipoprotein production in high-fat-fed mice

    NARCIS (Netherlands)

    Parlevliet, E.T.; Schröder-van der Elst, J.P.; Corssmit, E.P.M.; Picha, K.; O'Neil, K.; Stojanovic-Susulic, V.; Ort, T.; Havekes, L.M.; Romijn, J.A.; Pijl, H.

    2009-01-01

    CNTO736 is a glucagon-like peptide (GLP) 1 receptor agonist that incorporates a GLP-1 peptide analog linked to the Mimeti-body platform. We evaluate the potential of acute and chronic CNTO736 treatment on insulin sensitivity and very low-density lipoprotein (VLDL) metabolism. For acute studies, diet

  7. Peroxisome proliferator-activated receptor alpha improves pancreatic adaptation to insulin resistance in obese mice and reduces lipotoxicity in human islets

    NARCIS (Netherlands)

    Lalloyer, Fanny; Vandewalle, Brigitte; Percevault, Frederic; Torpier, Gerard; Kerr-Conte, Julie; Oosterveer, Maaike; Paumelle, Rejane; Fruchart, Jean-Charles; Kuipers, Folkert; Pattou, Francois; Fievet, Catherine; Staels, Bart

    Peroxisome proliferator-activated receptor (PPAR) alpha is a transcription factor controlling lipid and glucose homeostasis. PPAR alpha-deficient (-/-) mice are protected from high-fat diet-induced insulin resistance. However, the impact of PPAR alpha in the pathophysiological setting of

  8. Differential effects of pharmacological liver X receptor activation on hepatic and peripheral insulin sensitivity in lean and ob/ob mice

    NARCIS (Netherlands)

    Grefhorst, A; van Dijk, TH; Hammer, A; van der Sluijs, FH; Havinga, R; Havekes, LM; Romijn, JA; Groot, PH; Reijngoud, DJ; Kuipers, F

    2005-01-01

    Liver X receptor (LXR) agonists have been proposed to act as anti-diabetic drugs. However, pharmacological LXR activation leads to severe hepatic steatosis, a condition usually associated with insulin resistance and type 2 diabetes mellitus. To address this apparent contradiction, lean and ob/ob mic

  9. Increased oxidative stress and apoptosis in the hypothalamus of diabetic male mice in the insulin receptor substrate-2 knockout model

    Science.gov (United States)

    Canelles, Sandra; Argente, Jesús; Barrios, Vicente

    2016-01-01

    ABSTRACT Insulin receptor substrate-2-deficient (IRS2−/−) mice are considered a good model to study the development of diabetes because IRS proteins mediate the pleiotropic effects of insulin-like growth factor-I (IGF-I) and insulin on metabolism, mitogenesis and cell survival. The hypothalamus might play a key role in the early onset of diabetes, owing to its involvement in the control of glucose homeostasis and energy balance. Because some inflammatory markers are elevated in the hypothalamus of diabetic IRS2−/− mice, our aim was to analyze whether the diabetes associated with the absence of IRS2 results in hypothalamic injury and to analyze the intracellular mechanisms involved. Only diabetic IRS2−/− mice showed increased cell death and activation of caspase-8 and -3 in the hypothalamus. Regulators of apoptosis such as FADD, Bcl-2, Bcl-xL and p53 were also increased, whereas p-IκB and c-FLIPL were decreased. This was accompanied by increased levels of Nox-4 and catalase, enzymes involved in oxidative stress. In summary, the hypothalamus of diabetic IRS2−/− mice showed an increase in oxidative stress and inflammatory markers that finally resulted in cell death via substantial activation of the extrinsic apoptotic pathway. Conversely, non-diabetic IRS2−/− mice did not show cell death in the hypothalamus, possibly owing to an increase in the levels of circulating IGF-I and in the enhanced hypothalamic IGF-IR phosphorylation that would lead to the stimulation of survival pathways. In conclusion, diabetes in IRS2-deficient male mice is associated with increased oxidative stress and apoptosis in the hypothalamus. PMID:27013528

  10. Ryanodine receptor type I and nicotinic acid adenine dinucleotide phosphate receptors mediate Ca2+ release from insulin-containing vesicles in living pancreatic beta-cells (MIN6).

    Science.gov (United States)

    Mitchell, Kathryn J; Lai, F Anthony; Rutter, Guy A

    2003-03-28

    We have demonstrated recently (Mitchell, K. J., Pinton, P., Varadi, A., Tacchetti, C., Ainscow, E. K., Pozzan, T., Rizzuto, R., and Rutter, G. A. (2001) J. Cell Biol. 155, 41-51) that ryanodine receptors (RyR) are present on insulin-containing secretory vesicles. Here we show that pancreatic islets and derived beta-cell lines express type I and II, but not type III, RyRs. Purified by subcellular fractionation and membrane immuno-isolation, dense core secretory vesicles were found to possess a similar level of type I RyR immunoreactivity as Golgi/endoplasmic reticulum (ER) membranes but substantially less RyR II than the latter. Monitored in cells expressing appropriately targeted aequorins, dantrolene, an inhibitor of RyR I channels, elevated free Ca(2+) concentrations in the secretory vesicle compartment from 40.1 +/- 6.7 to 90.4 +/- 14.8 microm (n = 4, p < 0.01), while having no effect on ER Ca(2+) concentrations. Furthermore, nicotinic acid adenine dinucleotide phosphate (NAADP), a novel Ca(2+)-mobilizing agent, decreased dense core secretory vesicle but not ER free Ca(2+) concentrations in permeabilized MIN6 beta-cells, and flash photolysis of caged NAADP released Ca(2+) from a thapsigargin-insensitive Ca(2+) store in single MIN6 cells. Because dantrolene strongly inhibited glucose-stimulated insulin secretion (from 3.07 +/- 0.51-fold stimulation to no significant glucose effect; n = 3, p < 0.01), we conclude that RyR I-mediated Ca(2+)-induced Ca(2+) release from secretory vesicles, possibly potentiated by NAADP, is essential for the activation of insulin secretion.

  11. The farnesoid X receptor modulates adiposity and peripheral insulin sensitivity in mice

    NARCIS (Netherlands)

    Cariou, B; van Harmelen, K; Duran-Sandoval, D; van Dijk, TH; Grefhorst, A; Abdelkarim, M; Caron, S; Torpier, G; Fruchart, JC; Gonzalez, FJ; Kuipers, F; Staels, B

    2006-01-01

    The farnesoid X receptor (FXR) is a bile acid (BA)-activated nuclear receptor that plays a major role in the regulation of BA and lipid metabolism. Recently, several studies have suggested a potential role of FXR in the control of hepatic carbohydrate metabolism, but its contribution to the

  12. Insulin-like growth factor II: complexity of biosynthesis and receptor binding

    DEFF Research Database (Denmark)

    Gammeltoft, S; Christiansen, Jan; Nielsen, F C

    1991-01-01

    , Man-6-P induces cellular responses. We have studied rat brain neuronal precursor cells where Man-6-P acted as a mitogen suggesting that phosphomannosylated proteins may act as growth factors via the Man-6-P/IGF-II receptor. In conclusion, the gene expression and mechanism of action of IGF-II is very...... and the mannose-6-phosphate (Man-6-P)/IGF-II receptor. There is consensus that the cellular effects of IGF-II are mediated by the IGF-I receptor via activation of its intrinsic tyrosine kinase. The Man-6-P/IGF-II receptor is involved in endocytosis of lysosomal enzymes and IGF-II. In selected cell types, however...... complex suggesting that its biological actions can be regulated at different levels including the transcription, translation, posttranslational processing, receptor binding and intracellular signalling....

  13. Insulin Receptor Substrate-1 (IRS-1 Gly927Arg: Correlation with Gestational Diabetes Mellitus in Saudi Women

    Directory of Open Access Journals (Sweden)

    Khalid Khalaf Alharbi

    2014-01-01

    Full Text Available Pregnant women with gestational diabetes mellitus (GDM and type 2 diabetes mellitus (T2DM share a common pathophysiology associated with similar risk factors. Genetic variants used to determine the risk of developing T2DM might also be associated with the prevalence of GDM. The aim of the present study was to scrutinize the relationship between the G972R polymorphism of the insulin receptor substrate-1 (IRS-1 gene with GDM in the Saudi female population. This is a case-control study that monitored 500 Saudi women. Subjects with GDM (n=200 were compared with non-GDM (n=300 controls. We opted to evaluate rs1801278 polymorphism in the IRS1 gene, which plays a critical role in the insulin-signaling pathway. Genotyping was performed with the Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP method. The frequency of the rs1801278 polymorphism was significantly higher in women with GDM than in women with non-GDM (for TT + CT versus CC: P=0.02. Additionally, there was a significant increase in the frequency of the Arg-encoding mutant allele from GDM to non-GDM (for T versus C: P=0.01. Our results suggest that the rs1801278 polymorphism in the IRS-1 gene is involved in the occurrence of GDM in the Saudi population.

  14. Insulin receptor substrate-1 (IRS-1) Gly927Arg: correlation with gestational diabetes mellitus in Saudi women.

    Science.gov (United States)

    Alharbi, Khalid Khalaf; Khan, Imran Ali; Abotalib, Zeinab; Al-Hakeem, Malak Mohammed

    2014-01-01

    Pregnant women with gestational diabetes mellitus (GDM) and type 2 diabetes mellitus (T2DM) share a common pathophysiology associated with similar risk factors. Genetic variants used to determine the risk of developing T2DM might also be associated with the prevalence of GDM. The aim of the present study was to scrutinize the relationship between the G972R polymorphism of the insulin receptor substrate-1 (IRS-1) gene with GDM in the Saudi female population. This is a case-control study that monitored 500 Saudi women. Subjects with GDM (n = 200) were compared with non-GDM (n = 300) controls. We opted to evaluate rs1801278 polymorphism in the IRS1 gene, which plays a critical role in the insulin-signaling pathway. Genotyping was performed with the Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) method. The frequency of the rs1801278 polymorphism was significantly higher in women with GDM than in women with non-GDM (for TT + CT versus CC: P = 0.02). Additionally, there was a significant increase in the frequency of the Arg-encoding mutant allele from GDM to non-GDM (for T versus C: P = 0.01). Our results suggest that the rs1801278 polymorphism in the IRS-1 gene is involved in the occurrence of GDM in the Saudi population.

  15. Computational Analysis of Damaging Single-Nucleotide Polymorphisms and Their Structural and Functional Impact on the Insulin Receptor

    Directory of Open Access Journals (Sweden)

    Zabed Mahmud

    2016-01-01

    Full Text Available Single-nucleotide polymorphisms (SNPs associated with complex disorders can create, destroy, or modify protein coding sites. Single amino acid substitutions in the insulin receptor (INSR are the most common forms of genetic variations that account for various diseases like Donohue syndrome or Leprechaunism, Rabson-Mendenhall syndrome, and type A insulin resistance. We analyzed the deleterious nonsynonymous SNPs (nsSNPs in INSR gene based on different computational methods. Analysis of INSR was initiated with PROVEAN followed by PolyPhen and I-Mutant servers to investigate the effects of 57 nsSNPs retrieved from database of SNP (dbSNP. A total of 18 mutations that were found to exert damaging effects on the INSR protein structure and function were chosen for further analysis. Among these mutations, our computational analysis suggested that 13 nsSNPs decreased protein stability and might have resulted in loss of function. Therefore, the probability of their involvement in disease predisposition increases. In the lack of adequate prior reports on the possible deleterious effects of nsSNPs, we have systematically analyzed and characterized the functional variants in coding region that can alter the expression and function of INSR gene. In silico characterization of nsSNPs affecting INSR gene function can aid in better understanding of genetic differences in disease susceptibility.

  16. In vivo tissue specific modulation of rat insulin receptor gene expression in an experimental model of mineralocorticoid excess.

    Science.gov (United States)

    Campión, J; Lahera, V; Cachofeiro, V; Maestro, B; Dávila, N; Carranza, M C; Calle, C

    1998-08-01

    Insulin receptor (IR) gene expression at the mRNA level was investigated in hindlimb skeletal muscle, epididymal adipose tissue and in the liver of rats exposed to prolonged in vivo administration of deoxycorticosterone acetate (DOCA). Following treatment, plasma insulin levels were reduced while glucose levels increased compared to values in control rats. DOCA-treated animals showed an increase in blood pressure and a reduction in body weight. This treatment also induced hypokalemia and decreased plasma protein levels. Sodium levels were unaffected. Moreover, no differences in DNA and protein content or in the indicator of cell size (protein/DNA) were observed in the skeletal muscle or adipose tissue of animals. In contrast, there was a clear increase in the protein and DNA contents of the liver with no change in the indicator of cell size. Northern blot assays revealed 2 major IR mRNA species of approximately 9.5 and 7.5 Kb in the 3 tissues from control animals. DOCA treatment induced no change in the levels of either RNA species in skeletal muscle. However, a decrease of approximately 22% was detected in the levels of both species in adipose tissue whereas the liver showed an increase of 64%. These results provide the first evidence for an in vivo tissue-specific modulation of IR mRNA levels under experimental conditions of mineralocorticoid excess.

  17. Effect of Short-Term Administration of Glucagon on Gene Expression of the Insulin Receptor in Primary Cultured Calf Hepatocytes

    Directory of Open Access Journals (Sweden)

    Z. G. Zhang§, X. B. Li§1, G. W. Liu§1, Y. Y. Chen, M. L. Yu, J. G. Wang1, H. B. Wang, L. Liu1, Y. F. Li, L. Gao, Zhe Wang1*, L. Liu and X. L. Zhu1

    2012-06-01

    Full Text Available This study investigated whether increased glucagon levels, caused by the short-term administration of glucagon, lead to an increase in gene expression of the insulin receptor (InsR in calf hepatocytes cultured in vitro. After 72 hrs of culturing, glucagon was added to calf hepatocytes at a five different concentrations of 0, 1, 10, 100 and 1000 nM. InsR mRNA expression was determined by internally controlled reverse transcriptase polymerase chain reaction. No changes in InsR mRNA expression (InsR/β-actin gray scale were detected in hepatocytes treated with glucagon compared with the control group and there were no significant differences between the different concentrations. In conclusion, short-term administration of glucagon did not directly influence the gene expression of InsR in primary cultured calf hepatocytes.

  18. Sweet taste receptor expressed in pancreatic beta-cells activates the calcium and cyclic AMP signaling systems and stimulates insulin secretion.

    Directory of Open Access Journals (Sweden)

    Yuko Nakagawa

    Full Text Available BACKGROUND: Sweet taste receptor is expressed in the taste buds and enteroendocrine cells acting as a sugar sensor. We investigated the expression and function of the sweet taste receptor in MIN6 cells and mouse islets. METHODOLOGY/PRINCIPAL FINDINGS: The expression of the sweet taste receptor was determined by RT-PCR and immunohistochemistry. Changes in cytoplasmic Ca(2+ ([Ca(2+](c and cAMP ([cAMP](c were monitored in MIN6 cells using fura-2 and Epac1-camps. Activation of protein kinase C was monitored by measuring translocation of MARCKS-GFP. Insulin was measured by radioimmunoassay. mRNA for T1R2, T1R3, and gustducin was expressed in MIN6 cells. In these cells, artificial sweeteners such as sucralose, succharin, and acesulfame-K increased insulin secretion and augmented secretion induced by glucose. Sucralose increased biphasic increase in [Ca(2+](c. The second sustained phase was blocked by removal of extracellular calcium and addition of nifedipine. An inhibitor of inositol(1, 4, 5-trisphophate receptor, 2-aminoethoxydiphenyl borate, blocked both phases of [Ca(2+](c response. The effect of sucralose on [Ca(2+](c was inhibited by gurmarin, an inhibitor of the sweet taste receptor, but not affected by a G(q inhibitor. Sucralose also induced sustained elevation of [cAMP](c, which was only partially inhibited by removal of extracellular calcium and nifedipine. Finally, mouse islets expressed T1R2 and T1R3, and artificial sweeteners stimulated insulin secretion. CONCLUSIONS: Sweet taste receptor is expressed in beta-cells, and activation of this receptor induces insulin secretion by Ca(2+ and cAMP-dependent mechanisms.

  19. Insulin-Mimetic Action of Rhoifolin and Cosmosiin Isolated from Citrus grandis (L. Osbeck Leaves: Enhanced Adiponectin Secretion and Insulin Receptor Phosphorylation in 3T3-L1 Cells

    Directory of Open Access Journals (Sweden)

    Yerra Koteswara Rao

    2011-01-01

    Full Text Available Citrus grandis (L. Osbeck (red wendun leaves have been used in traditional Chinese medicine to treat several illnesses including diabetes. However, there is no scientific evidence supporting these actions and its active compounds. Two flavone glycosides, rhoifolin and cosmosiin were isolated for the first time from red wendun leaves and, identified these leaves are rich source for rhoifolin (1.1%, w/w. In differentiated 3T3-L1 adipocytes, rhoifolin and cosmosiin showed dose-dependent response in concentration range of o.oo1–5 μM and 1–20 μM, respectively, in biological studies beneficial to diabetes. Particularly, rhoifolin and cosmosiin at 0.5 and 20 μM, respectively showed nearly similar response to that 10 nM of insulin, on adiponectin secretion level. Furthermore, 5 μM of rhoifolin and 20 μM of cosmosiin showed equal potential with 10 nM of insulin to increase the phosphorylation of insulin receptor-β, in addition to their positive effect on GLUT4 translocation. These findings indicate that rhoifolin and cosmosiin from red wendun leaves may be beneficial for diabetic complications through their enhanced adiponectin secretion, tyrosine phosphorylation of insulin receptor-β and GLUT4 translocation.

  20. Molecular mechanism of insulin resistance

    Indian Academy of Sciences (India)

    Samir Bhattacharya; Debleena Dey; Sib Sankar Roy

    2007-03-01

    Free fatty acids are known to play a key role in promoting loss of insulin sensitivity, thereby causing insulin resistance and type 2 diabetes. However, the underlying mechanism involved is still unclear. In searching for the cause of the mechanism, it has been found that palmitate inhibits insulin receptor (IR) gene expression, leading to a reduced amount of IR protein in insulin target cells. PDK1-independent phosphorylation of PKCε causes this reduction in insulin receptor gene expression. One of the pathways through which fatty acid can induce insulin resistance in insulin target cells is suggested by these studies. We provide an overview of this important area, emphasizing the current status.

  1. MicroRNA-99a inhibits insulin-induced proliferation, migration, dedifferentiation, and rapamycin resistance of vascular smooth muscle cells by inhibiting insulin-like growth factor-1 receptor and mammalian target of rapamycin.

    Science.gov (United States)

    Zhang, Zi-Wei; Guo, Rui-Wei; Lv, Jin-Lin; Wang, Xian-Mei; Ye, Jin-Shan; Lu, Ni-Hong; Liang, Xing; Yang, Li-Xia

    2017-04-29

    Patients with type 2 diabetes mellitus (T2DM) are characterized by insulin resistance and are subsequently at high risk for atherosclerosis. Hyperinsulinemia has been associated with proliferation, migration, and dedifferentiation of vascular smooth muscle cells (VSMCs) during the pathogenesis of atherosclerosis. Moreover, insulin-like growth factor-1 receptor (IGF-1R) and mammalian target of rapamycin (mTOR) have been demonstrated to be the underlying signaling pathways. Recently, microRNA-99a (miR-99a) has been suggested to regulate the phenotypic changes of VSMCs in cancer cells. However, whether it is involved in insulin-induced changes of VSCMs has not been determined. In this study, we found that insulin induced proliferation, migration, and dedifferentiation of mouse VSMCs in a dose-dependent manner. Furthermore, the stimulating effects of high-dose insulin on proliferation, migration, and dedifferentiation of mouse VSMCs were found to be associated with the attenuation of the inhibitory effects of miR-99a on IGF-1R and mTOR signaling activities. Finally, we found that the inducing effect of high-dose insulin on proliferation, migration, and dedifferentiation of VSMCs was partially inhibited by an active mimic of miR-99a. Taken together, these results suggest that miR-99a plays a key regulatory role in the pathogenesis of insulin-induced proliferation, migration, and phenotype conversion of VSMCs at least partly via inhibition of IGF-1R and mTOR signaling. Our results provide evidence that miR-99a may be a novel target for the treatment of hyperinsulinemia-induced atherosclerosis. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Landmarks in insulin research

    Directory of Open Access Journals (Sweden)

    Michael eLawrence

    2011-11-01

    Full Text Available Ever since the discovery of insulin and its role in the regulation of glucose uptake and utilization, there has been great interest in insulin, its structure and the way in which it interacts with its receptor and effects signal transduction. As the 90th anniversary of the discovery of insulin approaches, it is timely to provide an overview of the landmark discoveries relating to the structure and function of this remarkable molecule and its receptor.

  3. Landmarks in Insulin Research

    OpenAIRE

    Ward, Colin W.; Lawrence, Michael C.

    2011-01-01

    Ever since the discovery of insulin and its role in the regulation of glucose uptake and utilization, there has been great interest in insulin, its structure and the way in which it interacts with its receptor and effects signal transduction. As the 90th anniversary of the discovery of insulin approaches, it is timely to provide an overview of the landmark discoveries relating to the structure and function of this remarkable molecule and its receptor.

  4. Distinct growth hormone receptor signaling modes regulate skeletal muscle development and insulin sensitivity in mice

    OpenAIRE

    Mavalli, Mahendra D.; DiGirolamo, Douglas J; FAN, Yong; Riddle, Ryan C.; Kenneth S Campbell; van Groen, Thomas; Frank, Stuart J; Sperling, Mark A.; Esser, Karyn A.; Bamman, Marcas M.; Clemens, Thomas L.

    2010-01-01

    Skeletal muscle development, nutrient uptake, and nutrient utilization is largely coordinated by growth hormone (GH) and its downstream effectors, in particular, IGF-1. However, it is not clear which effects of GH on skeletal muscle are direct and which are secondary to GH-induced IGF-1 expression. Thus, we generated mice lacking either GH receptor (GHR) or IGF-1 receptor (IGF-1R) specifically in skeletal muscle. Both exhibited impaired skeletal muscle development characterized by reductions ...

  5. Effects of GLP-1 receptor agonists on insulin sensitivity%GLP-1受体激动剂的胰岛素增敏效应

    Institute of Scientific and Technical Information of China (English)

    郑仁东; 刘超

    2012-01-01

    Insulin resistance and lack of insulin secretion is the main pathogenesis of type 2 diabetes.Researches have shown that glucagon-like peptide-1 ( GLP-1 ) receptor agonists could effectively improve the function of pancreatic β cell,and promote the secretion of insulin.Moreover,GLP-1 receptor agonists could regulate signal transduction,increase adipocytes differentiation and glucose uptake,decrease expression of inflammation factors,reduce weight and so on.Therefore,it can improve insulin resistance,increase insulin sensitivity.%2型糖尿病的发病机制主要涉及胰岛素抵抗张胰岛素分泌缺乏.研究表明,胰高血糖素样肽-1受体激动剂在有效改善胰岛β细胞功能,促进胰岛素分泌的同时,还能够作用于细胞信号转导,促进脂肪细胞分化和葡萄糖摄取,并通过减轻相关炎性反应因子表达,降低体重等,改善胰岛素抵抗,增加胰岛素敏感性.

  6. Alteration in insulin action

    DEFF Research Database (Denmark)

    Tanti, J F; Gual, P; Grémeaux, T

    2004-01-01

    Insulin resistance, when combined with impaired insulin secretion, contributes to the development of type 2 diabetes. Insulin resistance is characterised by a decrease in insulin effect on glucose transport in muscle and adipose tIssue. Tyrosine phosphorylation of insulin receptor substrate 1 (IRS......-1) and its binding to phosphatidylinositol 3-kinase (PI 3-kinase) are critical events in the insulin signalling cascade leading to insulin-stimulated glucose transport. Modification of IRS-1 by serine phosphorylation could be one of the mechanisms leading to a decrease in IRS-1 tyrosine...... to phosphorylate these serine residues have been identified. These exciting results suggest that serine phosphorylation of IRS-1 is a possible hallmark of insulin resistance in biologically insulin responsive cells or tIssues. Identifying the pathways by which "diabetogenic" factors activate IRS-1 kinases...

  7. Pharmacological regulation of insulin secretion in MIN6 cells through the fatty acid receptor GPR40: identification of agonist and antagonist small molecules.

    Science.gov (United States)

    Briscoe, Celia P; Peat, Andrew J; McKeown, Stephen C; Corbett, David F; Goetz, Aaron S; Littleton, Thomas R; McCoy, David C; Kenakin, Terry P; Andrews, John L; Ammala, Carina; Fornwald, James A; Ignar, Diane M; Jenkinson, Stephen

    2006-07-01

    1. Long chain fatty acids have recently been identified as agonists for the G protein-coupled receptors GPR40 and GPR120. Here, we present the first description of GW9508, a small-molecule agonist of the fatty acid receptors GPR40 and GPR120. In addition, we also describe the pharmacology of GW1100, a selective GPR40 antagonist. These molecules were used to further investigate the role of GPR40 in glucose-stimulated insulin secretion in the MIN6 mouse pancreatic beta-cell line. 2. GW9508 and linoleic acid both stimulated intracellular Ca2+ mobilization in human embryonic kidney (HEK)293 cells expressing GPR40 (pEC50 values of 7.32+/-0.03 and 5.65+/-0.06, respectively) or GPR120 (pEC50 values of 5.46+/-0.09 and 5.89+/-0.04, respectively), but not in the parent HEK-293 cell line. 3. GW1100 dose dependently inhibited GPR40-mediated Ca2+ elevations stimulated by GW9508 and linoleic acid (pIC50 values of 5.99+/-0.03 and 5.99+/-0.06, respectively). GW1100 had no effect on the GPR120-mediated stimulation of intracellular Ca2+ release produced by either GW9508 or linoleic acid. 4. GW9508 dose dependently potentiated glucose-stimulated insulin secretion in MIN6 cells, but not in primary rat or mouse islets. Furthermore, GW9508 was able to potentiate the KCl-mediated increase in insulin secretion in MIN6 cells. The effects of GW9508 on insulin secretion were reversed by GW1100, while linoleic acid-stimulated insulin secretion was partially attenuated by GW1100. 5. These results add further evidence to a link between GPR40 and the ability of fatty acids to acutely potentiate insulin secretion and demonstrate that small-molecule GPR40 agonists are glucose-sensitive insulin secretagogues.

  8. Analysis of the insulin receptor gene in noninsulin-dependent diabetes mellitus by denaturing gradient gel blots: A clinical research center study

    Energy Technology Data Exchange (ETDEWEB)

    Magre, J.; Goldfine, A.B.; Warram, J.H. [Harvard Medical School, Boston, MA (United States)] [and others

    1995-06-01

    We have used a new technique of denaturing gradient gel blotting to determine the prevalence of alterations in the intracellular domain of the insulin receptor in normal individuals and subjects with non-insulin-dependent diabetes mellitus (NIDDM). This method detects DNA sequence differences as restriction fragment melting polymorphisms (RFMP) and is sensitive to changes in sequence at both restriction sites and within the fragments themselves. Using restriction digests with AluI, HaeIII, HinfI, RsaI, Sau3A, and Sau96, 12 RFMPs were found to localize to the region of the {beta}-subunit of the insulin receptor gene. Using exon-specific probes, these RFMPs could be localized to specific regions surrounding individual exons, including exons, 14, 15, 16, 18, 20, and 22. In general, linkage disequilibrium between polymorphisms was inversely related to their distance in the gene structure, although there was a {open_quotes}hot spot{close_quotes} for recombination between exons 19 and 20. No difference in melting temperatures or allele frequency was observed between NIDDM patients and controls. These data indicate that the region of the insulin receptor gene coding for the intracellular portion of the {beta}-subunit is highly polymorphic and that polymorphisms surrounding specific exons can be identified by denaturing gradient gel blotting, but there is no evidence that variation at this locus contributes to NIDDM susceptibility in most individuals. 36 refs., 3 figs., 3 tabs.

  9. Relationship between melatonin receptor 1B and insulin receptor substrate 1 polymorphisms with gestational diabetes mellitus: a systematic review and meta-analysis.

    Science.gov (United States)

    Zhang, Yan; Sun, Cheng-Ming; Hu, Xiang-Qin; Zhao, Yue

    2014-08-22

    Studies have investigated the relationship between genetic variants and risk of gestational diabetes mellitus (GDM). However, the results remain inconclusive. The aim of this study was to investigate the association of rs10830963 and rs1387153 variants in melatonin receptor 1B (MTNR1B) and rs1801278 variant in insulin receptor substrate 1 (IRS1) with GDM susceptibility. Electronic database of PubMed, Medline, Embase, and CNKI (China National Knowledge Infrastructure) were searched for relevant studies between 2005 and 2014. The odds ratio (OR) with its 95% confidence interval (CI) were employed to estimate the association. Total ten case-control studies, including 3428 GDM cases and 4637 healthy controls, met the inclusion criteria. Our results showed a significant association between the three genetic variants and GDM risk, rs10830963 with a P-value less than 0.0001, rs1387153 with a P-value of 0.0002, and rs1801278 with a P-value of 0.001. Furthermore, all the genetic models in these three polymorphisms were associated with increased risks of GDM as well (P< = 0.009). In conclusion, our study found that the genetic polymorphisms rs10830963 and rs1387153 in MTNR1B and rs1801278 in IRS1 were associated with an increased risk of developing GDM. However, further studies with gene-gene and gene-environmental interactions should be considered.

  10. Expression and regulation of mRNAs for insulin-like growth factor-I receptor and LH receptor in corpora lutea

    Institute of Scientific and Technical Information of China (English)

    罗文祥; 祝诚

    2000-01-01

    Relationship between insulin-like growth factor-l receptor (IGF-IR) and luteinizing hormone receptor (LHR) mRNA expression as well as their regulation was determined in rat corpora lutea (CL) . In the CL of estrous cycle rat, LHR mRNA positive CL expressed high level of mRNA of IGF-IR. While the expression of LHR mRNA decreased on estrus, the CL still expressed relatively high level of IGF-IR mRNA. In pseudopregnant rat CL, the expression level of LHR mRNA was low on day 1, the most intense signals were detected on day 8, the signals of LHR mRNA became undetectable on day 14. In contrast to LHR expression, the high level of IGF-IR mRNA was observed in pseudopregnant CL of day 1, and thereafter its signals were detected from day 2 to day 14. Pregnant rat CL expressed both LHR and IGF-IR mRNAs. IGF-I stimulated LHR expression in CL. PGF2ainhibited expression of IGF-IR and LHR. PGE2 negated the inhibiting effects of PGF2α. These data suggest that IGF-I may be involved in regulating CL function, and maintai

  11. Insulin Resistance

    DEFF Research Database (Denmark)

    Jensen, Benjamin Anderschou Holbech

    Insulin resistance (IR) is escalating with alarming pace and is no longer restricted to westernized countries. As a forerunner for some of the most serious threats to human health including metabolic syndrome, cardiovascular diseases, and type 2-diabetes, the need for new treatment modalities...... interventions. We further show that improving the inflammatory toning, using fish oil as fat source, protects mice against diet induced obesity and -inflammation while preserving insulin sensitivity, even in the absence of free fatty acid receptor 4. Conversely, HFD-induced intestinal dysbiosis is associated...

  12. Systemic administration of kainic acid induces selective time dependent decrease in [{sup 125}I]insulin-like growth factor I, [{sup 125}I]insulin-like growth factor II and [{sup 125}I]insulin receptor binding sites in adult rat hippocampal formation

    Energy Technology Data Exchange (ETDEWEB)

    Quirion, R. [Department of Pharmacology and Therapeutics, McGill University, Montreal (Canada); Chabot, J.-G.; Dore, S. [Douglas Hospital Research Center, Department of Psychiatry, McGill University, Montreal (Canada); Seto, D. [Department of Pharmacology and Therapeutics, McGill University, Montreal (Canada); Kar, S. [Douglas Hospital Research Center, Department of Psychiatry, McGill University, Montreal (Canada)

    1997-08-11

    Administration of kainic acid evokes acute seizure in hippocampal pathways that results in a complex sequence of functional and structural alterations resembling human temporal lobe epilepsy. The structural alterations induced by kainic acid include selective loss of neurones in CA1-CA3 subfields and the hilar region of the dentate gyrus followed by sprouting and permanent reorganization of the synaptic connections of the mossy fibre pathways. Although the neuronal degeneration and process of reactive synaptogenesis have been extensively studied, at present little is known about means to prevent pathological conditions leading to kainate-induced cell death. In the present study, to address the role of insulin-like growth factors I and II, and insulin in neuronal survival as well as synaptic reorganization following kainate-induced seizure, the time course alterations of the corresponding receptors were evaluated. Additionally, using histological preparations, the temporal profile of neuronal degeneration and hypertrophy of resident astroglial cells were also studied. [{sup 125}I]Insulin-like growth factor I binding was found to be decreased transiently in almost all regions of the hippocampal formation at 12 h following treatment with kainic acid. The dentate hilar region however, exhibited protracted decreases in [{sup 125}I]insulin-like growth factor I receptor sites throughout (i.e. 30 days) the study. [{sup 125}I]Insulin-like growth factor II receptor binding sites in the hippocampal formation were found to be differentially altered following systemic administration of kainic acid. A significant decrease in [{sup 125}I]insulin-like growth factor II receptor sites was observed in CA1 subfield and the pyramidal cell layer of the Ammon's horn at all time points studied whereas the hilar region and the stratum radiatum did not exhibit alteration at any time. A kainate-induced decrease in [{sup 125}I]insulin receptor binding was noted at all time points in the

  13. Limited impact on glucose homeostasis of leptin receptor deletion from insulin- or proglucagon-expressing cells

    Directory of Open Access Journals (Sweden)

    Helen Soedling

    2015-09-01

    Conclusions/interpretation: The use here of a highly selective Cre recombinase indicates that leptin signalling plays a relatively minor, age- and sex-dependent role in the control of β cell function in the mouse. No in vivo role for leptin receptors on α cells, nor in other proglucagon-expressing cells, was detected in this study.

  14. Evaluation of protein undernourishment on the condylar process of the Wistar rat mandible correlation with insulin receptor expression

    Directory of Open Access Journals (Sweden)

    Marcelo Arthur CAVALLI

    2015-04-01

    Full Text Available The mandible condylar process cartilage (CP of Wistar rats is a secondary cartilage and acts as a mandibular growth site. This phenomenon depends on adequate proteins intake and hormone actions, including insulin. Objectives The present study evaluated the morphological aspects and the expression of the insulin receptor (IR in the cartilage of the condylar process (CP of rats subjected to protein undernourishment. Material and Methods The nourished group received a 20% casein diet, while the undernourished group (U received a 5% casein diet. The re-nourished groups, R and RR, were used to assess the effects of re-nutrition during puberty and adulthood, respectively. CPs were processed and stained with picro-sirius red, safranin-O and azocarmine. Scanning electron microscopy and immunohistochemistry were also performed. Results The area of the CP cartilage and the number of cells in the chondroblastic layer decreased in the U group, as did the thickness of the CP layer in the joint and hypertrophic layer. Renourishment during the pubertal stage, but not during the adult phase, restored these parameters. The cell number was restored when re-nutrition occurred in the pubertal stage, but not in the adult phase. The extracellular matrix also decreased in the U group, but was restored by re-nutrition during the pubertal stage and further increased in the adult phase. IR expression was observed in all CPs, being higher in the chondroblastic and hypertrophic cartilage layers. The lowest expression was found in the U and RR groups. Conclusions Protein malnutrition altered the cellularity, the area, and the fibrous cartilage complex, as well as the expression of the IRs.

  15. Selective Activation of Estrogen Receptor α Activation Function-1 Is Sufficient to Prevent Obesity, Steatosis, and Insulin Resistance in Mouse.

    Science.gov (United States)

    Guillaume, Maeva; Handgraaf, Sandra; Fabre, Aurélie; Raymond-Letron, Isabelle; Riant, Elodie; Montagner, Alexandra; Vinel, Alexia; Buscato, Melissa; Smirnova, Natalia; Fontaine, Coralie; Guillou, Hervé; Arnal, Jean-François; Gourdy, Pierre

    2017-06-01

    Estrogen receptor α (ERα) regulates gene transcription through two activation functions (ERα-AF1 and ERα-AF2). We recently found that the protection conferred by 17β-estradiol against obesity and insulin resistance requires ERα-AF2 but not ERα-AF1. However, the interplay between the two ERα-AFs is poorly understood in vivo and the metabolic influence of a specific ERα-AF1 action remains to be explored. To this end, wild-type, ERα-deficient, or ERα-AF1-deficient ovariectomized female mice were fed a high-fat diet and concomitantly administered with vehicle or tamoxifen, a selective ER modulator that acts as a ERα-AF1 agonist/ERα-AF2 antagonist. In ovariectomized wild-type mice, tamoxifen significantly reduced food intake and totally prevented adiposity, insulin resistance, and steatosis. These effects were abolished in ERα-deficient and ERα-AF1-deficient mice, revealing the specific role of ERα-AF1 activation. Finally, hepatic gene expression changes elicited by tamoxifen in wild-type mice were abrogated in ERα-AF1-deficient mice. The combination of pharmacologic and transgenic approaches thus indicates that selective ERα-AF1 activation by tamoxifen is sufficient to elicit metabolic protection, contrasting with the specific requirement of ERα-AF2 in the metabolic actions of 17β-estradiol. This redundancy in the ability of the two ERα-AFs to separately mediate metabolic prevention strikingly contrasts with the contribution of both ERα-AFs in breast cancer proliferation, shedding new light on the therapeutic potential of selective ER modulation. Copyright © 2017 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

  16. Effect of insulin and metformin on methylation and glycolipid metabolism of peroxisome proliferator-activated receptor γcoactivator-1A of rat offspring with gestational diabetes mellitus

    Institute of Scientific and Technical Information of China (English)

    Ai-Qin Song; Li-Rong Sun; Yan-Xia Zhao; Yan-Hua Gao; Lei Chen

    2016-01-01

    Objective: To discuss the effect of insulin and metformin on amethylation and glycolipid metabolism of peroxisome proliferator-activated receptor γ coactivator-1A (PPARGC1A) ofrat offspring with gestational diabetes mellitus (GDM). Methods: A total of 45 pregnant rats received the intraperitoneal injection of streptozotocin to establish the pregnant rat model of GDM. A total of 21 pregnant rats with GDM were randomly divided into three groups, with 7 rats in each group, namely the insulin group, metformin group and control group. Rats in the insulin group received the abdominal subcutaneous injection of 1 mL/kg recombinant insulin glargine at 18: 00 every day. Rats in the metformin group received the intragastric infusion of metformin hydrochloride at 18: 00 every day, with the first dose of 300 mg/kg. The doses of two groups were adjusted every 3 d to maintain the blood glucose level at 2.65-7.62 mmol/L. Rats in the control group received the intragastric infusion of 1 mL normal saline at 18:00 every day. After the natural delivery of pregnant rats, 10 offspring rats were randomly selected from each group. At birth, 4 wk and 8 wk after the birth of offspring rats, the weight of offspring rats was measured. The blood glucose level of offspring rats was measured at 4 wk and 8 wk, while the level of serum insulin, triglyceride and leptin was measured at 8 wk.Results: The weight of offspring rats at birth in the insulin group and metformin group was significantly lower than the one in the control group (P0.05). The fasting blood glucose and random blood glucose in the insulin group and metformin group at 4 wk and 8 wk were all significantly lower than ones in the control group (P0.05). The expression of PPARGC1A mRNA in the insulin group and metformin group was significantly higher and the methylation level of PPARGC1A was significantly lower than the one in the control group (P0.05). Insulin and leptin at 8 wk in the insulin group and metformin group were

  17. Obesidad, inflamación e insulino-resistencia: papel de los ligandos del receptor gp 130 Obesity, inflammation and insulin resistance: role of gp 130 receptor ligands

    Directory of Open Access Journals (Sweden)

    B. Marcos-Gómez

    2008-08-01

    like C-reactive protein. In this context, some cytokines of the interleukin-6 (IL-6 family have been involved in the inflammatory processes associated to obesity. In addition to IL-6, the IL-6 cytokine family includes IL-11, ciliary neurotrophic factor (cntf, cardiotrophin-1 (CT-1, cardiotrophin-like cytokine (CLC, leukemia inhibitory factor (LIF y Oncostatin M (OsM. These proteins are also known as gp130 cytokines because all of them exert their action via the glycoprotein 130 (gp130 as a common transducer protein within their functional receptor complexes. However, their role in obesity and related disorders is controversial; thus, whereas some studies have described the involvement of gp130 cytokines in the development of obesity and its related cluster of pathophysiologic conditions like insulin-resistance, fatty liver and cardiovascular diseases, other trials have proposed the gp130 receptor ligands as therapeutic targets in the treatment of obesity and its related disorders. In fact, CNTF treatment has demonstrated to be effective in the reduction of body weight, by promoting the inhibition of food intake and the activation of the energy expenditure, together with an improvement of insulin sensitivity. This review analyzes the potential therapeutic role of some of the gp130 ligands in obesity and related diseases.

  18. Novel CoQ10 antidiabetic mechanisms underlie its positive effect: modulation of insulin and adiponectine receptors, Tyrosine kinase, PI3K, glucose transporters, sRAGE and visfatin in insulin resistant/diabetic rats.

    Directory of Open Access Journals (Sweden)

    Mohamed M Amin

    Full Text Available As a nutritional supplement, coenzyme Q10 (CoQ10 was tested previously in several models of diabetes and/or insulin resistance (IR; however, its exact mechanisms have not been profoundly explicated. Hence, the objective of this work is to verify some of the possible mechanisms that underlie its therapeutic efficacy. Moreover, the study aimed to assess the potential modulatory effect of CoQ10 on the antidiabetic action of glimebiride. An insulin resistance/type 2 diabetic model was adopted, in which rats were fed high fat/high fructose diet (HFFD for 6 weeks followed by a single sub-diabetogenic dose of streptozotocin (35 mg/kg, i.p.. At the end of the 7(th week animals were treated with CoQ10 (20 mg/kg, p.o and/or glimebiride (0.5 mg/kg, p.o for 2 weeks. CoQ10 alone opposed the HFFD effect and increased the hepatic/muscular content/activity of tyrosine kinase (TK, phosphatidylinositol kinase (PI3K, and adiponectin receptors. Conversely, it decreased the content/activity of insulin receptor isoforms, myeloperoxidase and glucose transporters (GLUT4; 2. Besides, it lowered significantly the serum levels of glucose, insulin, fructosamine and HOMA index, improved the serum lipid panel and elevated the levels of glutathione, sRAGE and adiponectin. On the other hand, CoQ10 lowered the serum levels of malondialdehyde, visfatin, ALT and AST. Surprisingly, CoQ10 effect surpassed that of glimepiride in almost all the assessed parameters, except for glucose, fructosamine, TK, PI3K, and GLUT4. Combining CoQ10 with glimepiride enhanced the effect of the latter on the aforementioned parameters.These results provided a new insight into the possible mechanisms by which CoQ10 improves insulin sensitivity and adjusts type 2 diabetic disorder. These mechanisms involve modulation of insulin and adiponectin receptors, as well as TK, PI3K, glucose transporters, besides improving lipid profile, redox system, sRAGE, and adipocytokines. The study also points to the

  19. Glucose-Dependent Insulin Secretion in Pancreatic β-Cell Islets from Male Rats Requires Ca2+ Release via ROS-Stimulated Ryanodine Receptors.

    Directory of Open Access Journals (Sweden)

    Paola Llanos

    Full Text Available Glucose-stimulated insulin secretion (GSIS from pancreatic β-cells requires an increase in intracellular free Ca2+ concentration ([Ca2+]. Glucose uptake into β-cells promotes Ca2+ influx and reactive oxygen species (ROS generation. In other cell types, Ca2+ and ROS jointly induce Ca2+ release mediated by ryanodine receptor (RyR channels. Therefore, we explored here if RyR-mediated Ca2+ release contributes to GSIS in β-cell islets isolated from male rats. Stimulatory glucose increased islet insulin secretion, and promoted ROS generation in islets and dissociated β-cells. Conventional PCR assays and immunostaining confirmed that β-cells express RyR2, the cardiac RyR isoform. Extended incubation of β-cell islets with inhibitory ryanodine suppressed GSIS; so did the antioxidant N-acetyl cysteine (NAC, which also decreased insulin secretion induced by glucose plus caffeine. Inhibitory ryanodine or NAC did not affect insulin secretion induced by glucose plus carbachol, which engages inositol 1,4,5-trisphosphate receptors. Incubation of islets with H2O2 in basal glucose increased insulin secretion 2-fold. Inhibitory ryanodine significantly decreased H2O2-stimulated insulin secretion and prevented the 4.5-fold increase of cytoplasmic [Ca2+] produced by incubation of dissociated β-cells with H2O2. Addition of stimulatory glucose or H2O2 (in basal glucose to β-cells disaggregated from islets increased RyR2 S-glutathionylation to similar levels, measured by a proximity ligation assay; in contrast, NAC significantly reduced the RyR2 S-glutathionylation increase produced by stimulatory glucose. We propose that RyR2-mediated Ca2+ release, induced by the concomitant increases in [Ca2+] and ROS produced by stimulatory glucose, is an essential step in GSIS.

  20. PPAR-γ activation increases insulin secretion through the up-regulation of the free fatty acid receptor GPR40 in pancreatic β-cells.

    Directory of Open Access Journals (Sweden)

    Hyo-Sup Kim

    Full Text Available BACKGROUND: It has been reported that peroxisome proliferator-activated receptor (PPAR-γ and their synthetic ligands have direct effects on pancreatic β-cells. We investigated whether PPAR-γ activation stimulates insulin secretion through the up-regulation of GPR40 in pancreatic β-cells. METHODS: Rat insulinoma INS-1 cells and primary rat islets were treated with rosiglitazone (RGZ and/or adenoviral PPAR-γ overexpression. OLETF rats were treated with RGZ. RESULTS: PPAR-γ activation with RGZ and/or adenoviral PPAR-γ overexpression increased free fatty acid (FFA receptor GPR40 expression, and increased insulin secretion and intracellular calcium mobilization, and was blocked by the PLC inhibitors, GPR40 RNA interference, and GLUT2 RNA interference. As a downstream signaling pathway of intracellular calcium mobilization, the phosphorylated levels of CaMKII and CREB, and the downstream IRS-2 and phospho-Akt were significantly increased. Despite of insulin receptor RNA interference, the levels of IRS-2 and phospho-Akt was still maintained with PPAR-γ activation. In addition, the β-cell specific gene expression, including Pdx-1 and FoxA2, increased in a GPR40- and GLUT2-dependent manner. The levels of GPR40, phosphorylated CaMKII and CREB, and β-cell specific genes induced by RGZ were blocked by GW9662, a PPAR-γ antagonist. Finally, PPAR-γ activation up-regulated β-cell gene expressions through FoxO1 nuclear exclusion, independent of the insulin signaling pathway. Based on immunohistochemical staining, the GLUT2, IRS-2, Pdx-1, and GPR40 were more strongly expressed in islets from RGZ-treated OLETF rats compared to control islets. CONCLUSION: These observations suggest that PPAR-γ activation with RGZ and/or adenoviral overexpression increased intracellular calcium mobilization, insulin secretion, and β-cell gene expression through GPR40 and GLUT2 gene up-regulation.

  1. Relative expression of the p75 neurotrophin receptor, tyrosine receptor kinase A, and insulin receptor in SH-SY5Y neuroblastoma cells and hippocampi from Alzheimer's disease patients.

    Science.gov (United States)

    Ito, Shingo; Ménard, Michel; Atkinson, Trevor; Brown, Leslie; Whitfield, James; Chakravarthy, Balu

    2016-12-01

    We have previously shown in SH-SY5Y human neuroblastoma cells that the expressions of basal (75 kDa) and high molecular weight (HMW; 85 kDa) isoforms of the p75 neurotrophic receptor (p75NTR) are stimulated by amyloid-β peptide1-42 oligomers (AβOs) via the insulin-like growth factor-1 receptor (IGF-1R). On the other hand, it is known that AβOs inhibit insulin receptor (IR) signaling. The purpose of the present study was to determine the involvement of IR signaling in the regulation of p75 neurotrophin receptor (p75NTR) protein isoform expression in cultured SH-SY5Y cells and in hippocampi from late-stage human Alzheimer's disease (AD) brains. Interestingly, insulin induced the expression of basal and HMW p75NTR isoforms in SH-SY5Y cells, suggesting the presence of cross-talk between the IR and IGF-1R for the regulation of p75NTR expression. Reducing IR signaling with an IR kinase inhibitor (AG 1024) or IR-targeted siRNAs increased HMW p75NTR expression and reduced tyrosine receptor kinase-A (Trk-A) expression as well as postsynaptic density protein 95 (PSD95) expression in SH-SY5Y cells. Both basal and HMW p75NTR isoforms were increased in the hippocampi of post-mortem late-stage human AD brains (relative to non-AD brains), and the protein expression of HMW p75NTR was negatively associated with Trk-A expression, PSD95 expression, and IR expression. Thus, increased p75NTR expression, specifically an increased p75NTR-to-Trk-A ratio, is likely to play a role in synaptic loss and neuronal cell death in late-stage AD. Collectively, these findings suggest that increased expression of the p75NTR due to IR signaling inhibition by AβOs might be involved in the pathology of AD.

  2. Alternative splicing of exon 17 and a missense mutation in exon 20 of the insulin receptor gene in two brothers with a novel syndrome of insulin resistance (congenital fiber-type disproportion myopathy).

    Science.gov (United States)

    Vorwerk, P; Christoffersen, C T; Müller, J; Vestergaard, H; Pedersen, O; De Meyts, P

    1999-01-01

    The insulin receptor (IR) in two brothers with a rare syndrome of congenital muscle fiber type disproportion myopathy (CFTDM) associated with diabetes and severe insulin resistance was studied. By direct sequencing of Epstein-Barr virus-transformed lymphocytes both patients were found to be compound heterozygotes for mutations in the IR gene. The maternal allele was alternatively spliced in exon 17 due to a point mutation in the -1 donor splice site of the exon. The abnormal skipping of exon 17 shifts the amino acid reading frame and leads to a truncated IR, missing the entire tyrosine kinase domain. In the correct spliced variant, the point mutation is silent and results in a normally translated IR. The paternal allele carries a missense mutation in the tyrosine kinase domain. All three cDNA variants were present in the lymphocytes of the patients. Purified IR from 293 cells overexpressing either of the two mutated receptors lacked basal or stimulated IR beta-subunit autophosphorylation. A third brother who inherited both normal alleles has an normal muscle phenotype and insulin sensitivity, suggesting a direct linkage of these IR mutations with the CFTDM phenotype.

  3. Inhibition of Gastric Inhibitory Polypeptide Receptor Signaling in Adipose Tissue Reduces Insulin Resistance and Hepatic Steatosis in High-Fat Diet-Fed Mice.

    Science.gov (United States)

    Joo, Erina; Harada, Norio; Yamane, Shunsuke; Fukushima, Toru; Taura, Daisuke; Iwasaki, Kanako; Sankoda, Akiko; Shibue, Kimitaka; Harada, Takanari; Suzuki, Kazuyo; Hamasaki, Akihiro; Inagaki, Nobuya

    2017-04-01

    Gastric inhibitory polypeptide receptor (GIPR) directly induces energy accumulation in adipose tissue in vitro. However, the importance of the direct effect of GIPR signaling on adipose tissue in vivo remains unclear. In the current study, we generated adipose tissue-specific GIPR knockout (GIPR(adipo-/-)) mice and investigated the direct actions of GIP in adipose tissue. Under high-fat diet (HFD)-fed conditions, GIPR(adipo-/-) mice had significantly lower body weight and lean body mass compared with those in floxed GIPR (GIPR(fl/fl)) mice, although the fat volume was not significantly different between the two groups. Interestingly, insulin resistance, liver weight, and hepatic steatosis were reduced in HFD-fed GIPR(adipo-/-) mice. Plasma levels of interleukin-6 (IL-6), a proinflammatory cytokine that induces insulin resistance, were reduced in HFD-fed GIPR(adipo-/-) mice compared with those in HFD-fed GIPR(fl/fl) mice. Suppressor of cytokine signaling 3 (SOCS3) signaling is located downstream of the IL-6 receptor and is associated with insulin resistance and hepatic steatosis. Expression levels of SOCS3 mRNA were significantly lower in adipose and liver tissues of HFD-fed GIPR(adipo-/-) mice compared with those of HFD-fed GIPR(fl/fl) mice. Thus, GIPR signaling in adipose tissue plays a critical role in HFD-induced insulin resistance and hepatic steatosis in vivo, which may involve IL-6 signaling. © 2017 by the American Diabetes Association.

  4. The Dual Amylin- and Calcitonin-Receptor Agonist KBP-042 Increases Insulin Sensitivity and Induces Weight Loss in Rats with Obesity

    DEFF Research Database (Denmark)

    Hjuler, Sara Toftegaard; Gydesen, Sofie; Andreassen, Kim Vietz

    2016-01-01

    Objective: In this study, KBP-042, a dual amylin- and calcitonin-receptor agonist, was investigated as a treatment of obesity and insulin resistance in five different doses (0.625 μg/kg-10 μg/kg) compared with saline-treated and pair-fed controls. Methods: Rats with obesity received daily s.c. ad...... combines two highly relevant features, namely weight loss and insulin sensitivity, and is thus an excellent candidate for chronic treatment of obesity and insulin resistance....... a sustained weight loss of up to 20% without any significant weight reduction in the pair-fed groups. Decreases in adipose tissues and lipid deposition in the liver were observed, while plasma adiponectin was increased and plasma leptin levels were decreased. Acute administration of KBP-042 led to impaired......Objective: In this study, KBP-042, a dual amylin- and calcitonin-receptor agonist, was investigated as a treatment of obesity and insulin resistance in five different doses (0.625 μg/kg-10 μg/kg) compared with saline-treated and pair-fed controls. Methods: Rats with obesity received daily s...

  5. miR-146a-5p inhibits TNF-α-induced adipogenesis via targeting insulin receptor in primary porcine adipocytes.

    Science.gov (United States)

    Wu, Di; Xi, Qian-Yun; Cheng, Xiao; Dong, Tao; Zhu, Xiao-Tong; Shu, Gang; Wang, Li-Na; Jiang, Qing-Yan; Zhang, Yong-Liang

    2016-08-01

    TNF-α is a multifunctional cytokine participating in immune disorders, inflammation, and tumor development with regulatory effects on energy metabolism. Our work focused on the function of TNF-α in adipogenesis of primary porcine adipocytes. TNF-α could suppress the insulin receptor (IR) at the mRNA and protein levels. Microarray analysis of TNF-α-treated porcine adipocytes was used to screen out 29 differentially expressed microRNAs (miRNAs), 13 of which were remarkably upregulated and 16 were intensely downregulated. These 29 differentially expressed miRNAs were predicted to mainly participate in the insulin signaling pathway, adipocytokine signaling pathway, and type 2 diabetes mellitus pathway by Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses. miR-146a-5p, reportedly involved in immunity and cancer relevant processes, was one of the most highly differentially expressed miRNAs after TNF-α treatment. Red Oil O staining and TG assay revealed that miR-146a-5p suppressed adipogenesis. A dual-luciferase reporter and siRNA assay verified that miR-146a-5p targeted IR and could inhibit its protein expression. miR-146a-5p was also validated to be involved in the insulin signaling pathway by reducing tyrosine phosphorylation of insulin receptor substrate-1. Our study provides the first evidence of miR-146a-5p targeting IR, which facilitates future studies related to obesity and diabetes using pig models.

  6. Identification of plant extracts with potential antidiabetic properties: effect on human peroxisome proliferator-activated receptor (PPAR), adipocyte differentiation and insulin-stimulated glucose uptake.

    Science.gov (United States)

    Christensen, Kathrine B; Minet, Ariane; Svenstrup, Henrik; Grevsen, Kai; Zhang, Hongbin; Schrader, Eva; Rimbach, Gerald; Wein, Silvia; Wolffram, Siegfried; Kristiansen, Karsten; Christensen, Lars P

    2009-09-01

    Thiazolidinediones (TZDs) are insulin sensitizing drugs used to treat type 2 diabetes. The primary target of the TZDs is the peroxisome proliferator-activated receptor (PPAR) gamma, a key regulator of adipogenesis and glucose homeostasis. Currently prescribed TZDs are full PPARgamma agonists, and their use is associated with several side effects. Partial PPARgamma agonists appear to be associated with fewer side effects but may still confer the desired insulin sensitizing action. Extracts from common medicinal/food plants were tested in a screening platform comprising a series of bioassays, including tests for PPARgamma, alpha and delta transactivation, adipocyte differentiation and insulin-stimulated glucose uptake, allowing identification of plants containing potentially interesting PPAR agonists. Twenty-two plant extracts out of 133 were found to increase insulin-stimulated glucose uptake and 18 extracts were found to activate PPARgamma, 3 to activate PPARalpha and gamma, 6 to activate PPARdelta and gamma, and 9 to activate PPARgamma, alpha and delta. Among the 24 different plant species tested in the platform, 50% were shown to contain compounds capable of activating PPARgamma and stimulating insulin-dependent glucose uptake with no or little effect on adipocyte differentiation warranting further studies and characterization.

  7. Adipose-specific peroxisome proliferator-activated receptor γ knockout causes insulin resistance in fat and liver but not in muscle

    OpenAIRE

    He, Weimin; Barak, Yaacov; Hevener, Andrea; Olson, Peter; Liao, Debbie; Le, Jamie; Nelson, Michael; Ong, Estelita; Olefsky, Jerrold M.; Evans, Ronald M

    2003-01-01

    Syndrome X, typified by obesity, insulin resistance (IR), dyslipidemia, and other metabolic abnormalities, is responsive to antidiabetic thiazolidinediones (TZDs). Peroxisome proliferator-activated receptor (PPAR) γ, a target of TZDs, is expressed abundantly in adipocytes, suggesting an important role for this tissue in the etiology and treatment of IR. Targeted deletion of PPARγ in adipose tissue resulted in marked adipocyte hypocellularity and hypertrophy, elevated levels of plasma free fat...

  8. Vitamin D receptor gene polymorphisms, dietary promotion of insulin resistance, and colon and rectal cancer.

    OpenAIRE

    Murtaugh, Maureen A.; Sweeney, Carol; Ma, Khe-ni; Potter, John D.; Caan, Bette J.; Wolff, Roger K.; Slattery, Martha L

    2006-01-01

    Biomarkers of individual susceptibility: field studies. Biomarker: vitamin D receptor (VDR) gene polymorphisms Effect studied: colon and rectal cancer risk. Tissue/biological material/sample size: colon, rectum. Method of analysis: genotyping of the VDR gene Study design: case-control studyStudy size: colon cancer (1,698 cases and 1,861 controls); rectal cancer (752 cases and 960 controls) Impact on outcome (including dose-response): The lowest colon cancer risk was observed with the Ff/ff Fo...

  9. Tyrosine kinase of insulin-like growth factor receptor as target for novel treatment and prevention strategies of colorectal cancer

    Institute of Scientific and Technical Information of China (English)

    Michael H(o)pfner; Andreas P Sutter; Alexander Huether; Viola Baradari; Hans Scherübl

    2006-01-01

    AIM: To investigate the antineoplastic potency of the novel insulin-like growth factor 1 receptor (IGF-1R) tyrosine kinase inhibitor (TKI) NVP-AEW541 in cell lines and primary cell cultures of human colorectal cancer (CRC).METHODS: Cells of primary colorectal carcinomas were from 8 patients. Immunostaining and crystal violet staining were used for analysis of growth factor receptor protein expression and detection of cell number changes,respectively. Cytotoxicity was determined by measuring the release of the cytoplasmic enzyme lactate dehydrogenase (LDH). The proportion of apoptotic cells was determined by quantifying the percentage of sub-G1(hypodiploid) cells. Cell cycle status reflected by the DNA content of the nuclei was detected by flow cytometry.RESULTS: NVP-AEW541 dose-dependently inhibited the proliferation of colorectal carcinoma cell lines and primary cell cultures by inducing apoptosis and cell cycle arrest. Apoptosis was characterized by caspase-3 activation and nuclear degradation. Cell cycle was arrested at the G1/S checkpoint. The NVP-AEW541-mediated cell cycle-related signaling involved the inactivation of Akt and extracellular signal-regulated kinase (ERK) 1/2, the upregulation of the cyclin-dependent kinase inhibitors p21Waf1/CIP1 and p27Kip1, and the downregulation of the cell cycle promoter cyclin D1. Moreover, BAX was upregulated during NVP-AEW541-induced apoptosis, whereas Bcl-2 was downregulated. Measurement of LDH release showed that the antineoplastic effect of NVP-AEW541 was not due to general cytotoxicity of the compound.However, augmented antineoplastic effects were observed in combination treatments of NVP-AEW541 with either 5-FU, or the EGFR-antibody cetuximab, or the HMG-CoA-reductase inhibitor fluvastatin.CONCLUSION: IGF-1R-TK inhibition is a promising novel approach for either mono- or combination treatment strategies of colorectal carcinoma and even for CRC chemoprevention.

  10. Mammary tumors that become independent of the type I insulin-like growth factor receptor express elevated levels of platelet-derived growth factor receptors

    Directory of Open Access Journals (Sweden)

    Campbell Craig I

    2011-11-01

    Full Text Available Abstract Background Targeted therapies are becoming an essential part of breast cancer treatment and agents targeting the type I insulin-like growth factor receptor (IGF-IR are currently being investigated in clinical trials. One of the limitations of targeted therapies is the development of resistant variants and these variants typically present with unique gene expression patterns and characteristics compared to the original tumor. Results MTB-IGFIR transgenic mice, with inducible overexpression of the IGF-IR were used to model mammary tumors that develop resistance to IGF-IR targeting agents. IGF-IR independent mammary tumors, previously shown to possess characteristics associated with EMT, were found to express elevated levels of PDGFRα and PDGFRβ. Furthermore, these receptors were shown to be inversely expressed with the IGF-IR in this model. Using cell lines derived from IGF-IR-independent mammary tumors (from MTB-IGFIR mice, it was demonstrated that PDGFRα and to a lesser extent PDGFRβ was important for cell migration and invasion as RNAi knockdown of PDGFRα alone or PDGFRα and PDGFRβ in combination, significantly decreased tumor cell migration in Boyden chamber assays and suppressed cell migration in scratch wound assays. Somewhat surprisingly, concomitant knockdown of PDGFRα and PDGFRβ resulted in a modest increase in cell proliferation and a decrease in apoptosis. Conclusion During IGF-IR independence, PDGFRs are upregulated and function to enhance tumor cell motility. These results demonstrate a novel interaction between the IGF-IR and PDGFRs and highlight an important, therapeutically relevant pathway, for tumor cell migration and invasion.

  11. A rare co-segregation-mutation in the insulin receptor substrate 1 gene in one Chinese family with ankylosing spondylitis.

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    Ju Rong

    Full Text Available Ankylosing spondylitis (AS; MIM 106300 is a common rheumatic disease with strong genetic components affecting approximately 0.3% of the population. The exact genetic mechanism of AS remains elusive. Our previous study showed that AS could be transmitted in an autosomal dominant inheritance mode and a 6-cM candidate region located on the chromosome 2q36.1-36.3 was mapped in a Chinese family. Mutation screening was conducted within the candidate region in the family and other AS by sequencing, and the novel mutation will be further validated in other AS families, sporadic cases and healthy controls by mass spectrometry. We identified a rare non-synonymous mutation (Arg580Gly in insulin receptor substrate 1 (IRS1 co-segregated with disease phenotype in patients of the family, which was not found in other AS families, sporadic patients and healthy controls. In the study, we found a rare non-synonymous mutation in IRS1 co-segregation in one Chinese family with AS, which indicated a new candidate disease causative gene for AS.

  12. microRNA-141 inhibits thyroid cancer cell growth and metastasis by targeting insulin receptor substrate 2.

    Science.gov (United States)

    Dong, Su; Meng, Xianying; Xue, Shuai; Yan, Zewen; Ren, Peiyou; Liu, Jia

    2016-01-01

    microRNA-141 (miR-141), a member of the miR-200 family, and has been reported to involve in tumor initiation and development in many types of cancers. However, the function and underlying molecular mechanism of miR-141 in thyroid cancer remains unclear. Therefore, the aim of this study is to identify its expression, function, and molecular mechanism in thyroid cancer. In this study, we found that miR-141 expression levels were downregulated in human thyroid cancer specimens compared to the adjacent normal tissues, and its expression were strongly correlated with clinical stages and lymph node metastases. Function assays showed that overexpression of miR-141 inhibited cell proliferation, induced cell apoptosis, and decreased migration, invasion in thyroid cancer cells, as well as tumor growth in nude mice. Moreover, insulin receptor substrate 2 (IRS2), a known oncogene, was confirmed as a direct target of miR-141, and IRS2 expression levels were upregulated in thyroid cancer, and its expression were inversely correlated with miR-141 expression levels in human thyroid cancer specimens. Forced expression of IRS2 reversed the inhibition effect induced by miR-141 overexpression in thyroid cancer cells. Taken together, our study provides the first evidence that miR-141 suppressed thyroid cancer cell growth and metastasis through inhibition of IRS2. Thus, miR-141 might serve as a promising therapeutic strategy for thyroid cancer treatment.

  13. Biologic Roles of Estrogen Receptor-β and Insulin-Like Growth Factor-2 in Triple-Negative Breast Cancer

    Directory of Open Access Journals (Sweden)

    Nalo Hamilton

    2015-01-01

    Full Text Available Triple-negative breast cancer (TNBC occurs in 10–15% of patients yet accounts for almost half of all breast cancer deaths. TNBCs lack expression of estrogen and progesterone receptors and HER-2 overexpression and cannot be treated with current targeted therapies. TNBCs often occur in African American and younger women. Although initially responsive to some chemotherapies, TNBCs tend to relapse and metastasize. Thus, it is critical to find new therapeutic targets. A second ER gene product, termed ERβ, in the absence of ERα may be such a target. Using human TNBC specimens with known clinical outcomes to assess ERβ expression, we find that ERβ1 associates with significantly worse 5-year overall survival. Further, a panel of TNBC cell lines exhibit significant levels of ERβ protein. To assess ERβ effects on proliferation, ERβ expression in TNBC cells was silenced using shRNA, resulting in a significant reduction in TNBC proliferation. ERβ-specific antagonists similarly suppressed TNBC growth. Growth-stimulating effects of ERβ may be due in part to downstream actions that promote VEGF, amphiregulin, and Wnt-10b secretion, other factors associated with tumor promotion. In vivo, insulin-like growth factor-2 (IGF-2, along with ERβ1, is significantly expressed in TNBC and stimulates high ERβ mRNA in TNBC cells. This work may help elucidate the interplay of metabolic and growth factors in TNBC.

  14. Expression of the genes for insulin-like growth factors and their receptors in bone during skeletal growth

    Science.gov (United States)

    Bikle, D. D.; Harris, J.; Halloran, B. P.; Roberts, C. T.; Leroith, D.; Morey-Holton, E.

    1994-01-01

    Insulin-like growth factors (IGF) are important regulators of skeletal growth. To determine whether the capacity to produce and respond to these growth factors changes during skeletal development, we measured the protein and mRNA levels for IGF-I, IGF-II, and their receptors (IGF-IR and IGF-IIR, respectively) in the tibia and femur of rats before and up to 28 mo after birth. The mRNA levels remained high during fetal development but fell after birth, reaching a nadir by 3-6 wk. This fall was most pronounced for IGF-II and IGF-IIR mRNA and least pronounced for IGF-I mRNA. However, after 6 wk, both IGF-I and IGF-IR mRNA levels recovered toward the levels observed at birth. In the prenatal bones, the signals for the mRNAs of IGF-II and IGF-IIR were stronger than the signals for the mRNAs of IGF-I and IGF-IR, although the content of IGF-I was three- to fivefold greater than that of IGF-II. IGF-II levels fell postnatally, whereas the IGF-I content rose after birth such that the ratio IGF-I/IGF-II continued to increase with age. We conclude that, during development, rat bone changes its capacity to produce and respond to IGFs with a progressive trend toward the dominance of IGF-I.

  15. Bisubstrate analog probes for the insulin receptor protein tyrosine kinase: molecular yardsticks for analyzing catalytic mechanism and inhibitor design.

    Science.gov (United States)

    Hines, Aliya C; Parang, Keykavous; Kohanski, Ronald A; Hubbard, Stevan R; Cole, Philip A

    2005-08-01

    Bisubstrate analogs have the potential to provide enhanced specificity for protein kinase inhibition and tools to understand catalytic mechanism. Previous efforts led to the design of a peptide-ATP conjugate bisubstrate analog utilizing aminophenylalanine in place of tyrosine and a thioacetyl linker to the gamma-phosphate of ATP which was a potent inhibitor of the insulin receptor kinase (IRK). In this study, we have examined the contributions of various electrostatic and structural elements in the bisubstrate analog to IRK binding affinity. Three types of changes (seven specific analogs in all) were introduced: a Tyr isostere of the previous aminophenylalanine moiety, modifications of the spacer between the adenine and the peptide, and deletions and substitutions within the peptide moiety. These studies allowed a direct evaluation of the hydrogen bond strength between the anilino nitrogen of the bisubstrate analog and the enzyme catalytic base Asp and showed that it contributes 2.5 kcal/mol of binding energy, in good agreement with previous predictions. Modifications of the linker length resulted in weakened inhibitory affinity, consistent with the geometric requirements of an enzyme-catalyzed dissociative transition state. Alterations in the peptide motif generally led to diminished inhibitory potency, and only some of these effects could be rationalized based on prior kinetic and structural studies. Taken together, these results suggest that a combination of mechanism-based design and empirical synthetic manipulation will be necessary in producing optimized protein kinase bisubstrate analog inhibitors.

  16. Hypoglycemic effects of Trichosanthes kirilowii and its protein constituent in diabetic mice: the involvement of insulin receptor pathway.

    Science.gov (United States)

    Lo, Hsin-Yi; Li, Tsai-Chung; Yang, Tse-Yen; Li, Chia-Cheng; Chiang, Jen-Huai; Hsiang, Chien-Yun; Ho, Tin-Yun

    2017-01-18

    Diabetes is a serious chronic metabolic disorder. Trichosanthes kirilowii Maxim. (TK) is traditionally used for the treatment of diabetes in traditional Chinese medicine (TCM). However, the clinical application of TK on diabetic patients and the hypoglycemic efficacies of TK are still unclear. A retrospective cohort study was conducted to analyze the usage of Chinese herbs in patients with type 2 diabetes in Taiwan. Glucose tolerance test was performed to analyze the hypoglycemic effect of TK. Proteomic approach was performed to identify the protein constituents of TK. Insulin receptor (IR) kinase activity assay and glucose tolerance tests in diabetic mice were further used to elucidate the hypoglycemic mechanisms and efficacies of TK. By a retrospective cohort study, we found that TK was the most frequently used Chinese medicinal herb in type 2 diabetic patients in Taiwan. Oral administration of aqueous extract of TK displayed hypoglycemic effects in a dose-dependent manner in mice. An abundant novel TK protein (TKP) was further identified by proteomic approach. TKP interacted with IR by docking analysis and activated the kinase activity of IR. In addition, TKP enhanced the clearance of glucose in diabetic mice in a dose-dependent manner. In conclusion, this study applied a bed-to-bench approach to elucidate the hypoglycemic efficacies and mechanisms of TK on clinical usage. In addition, we newly identified a hypoglycemic protein TKP from TK. Our findings might provide a reasonable explanation of TK on the treatment of diabetes in TCM.

  17. Orthologs of Human Disease Associated Genes and RNAi Analysis of Silencing Insulin Receptor Gene in Bombyx mori

    Directory of Open Access Journals (Sweden)

    Zan Zhang

    2014-10-01

    Full Text Available The silkworm, Bombyx mori L., is an important economic insect that has been domesticated for thousands of years to produce silk. It is our great interest to investigate the possibility of developing the B. mori as human disease model. We searched the orthologs of human disease associated genes in the B. mori by bi-directional best hits of BLAST and confirmed by searching the OrthoDB. In total, 5006 genes corresponding to 1612 kinds of human diseases had orthologs in the B. mori, among which, there are 25 genes associated with diabetes mellitus. Of these, we selected the insulin receptor gene of the B. mori (Bm-INSR to study its expression in different tissues and at different developmental stages and tissues. Quantitative PCR showed that Bm-INSR was highly expressed in the Malpighian tubules but expressed at low levels in the testis. It was highly expressed in the 3rd and 4th instar larvae, and adult. We knocked down Bm-INSR expression using RNA interference. The abundance of Bm-INSR transcripts were dramatically reduced to ~4% of the control level at 6 days after dsRNA injection and the RNAi-treated B. mori individuals showed apparent growth inhibition and malformation such as abnormal body color in black, which is the typical symptom of diabetic patients. Our results demonstrate that B. mori has potential use as an animal model for diabetic mellitus research.

  18. Insulin-like growth factor-1 receptor in mature osteoblasts is required for periosteal bone formation induced by reloading

    Science.gov (United States)

    Kubota, Takuo; Elalieh, Hashem Z.; Saless, Neema; Fong, Chak; Wang, Yongmei; Babey, Muriel; Cheng, Zhiqiang; Bikle, Daniel D.

    2012-01-01

    Skeletal loading and unloading has a pronounced impact on bone remodeling, a process also regulated by insulin-like growth factor 1 (IGF-1) signaling. Skeletal unloading leads to resistance to the anabolic effect of IGF-1, while reloading after unloading restores responsiveness to IGF-1. However, a direct study of the importance of IGF-1 signaling in the skeletal response to mechanical loading remains to be tested. In this study, we assessed the skeletal response of osteoblast-specific Igf-1 receptor deficient (Igf-1r−/−) mice to unloading and reloading. The mice were hindlimb unloaded for 14 days and then reloaded for 16 days. Igf-1r−/− mice displayed smaller cortical bone and diminished periosteal and endosteal bone formation at baseline. Periosteal and endosteal bone formation decreased with unloading in Igf-1r+/+ mice. However, the recovery of periosteal bone formation with reloading was completely inhibited in Igf-1r−/− mice, although reloading-induced endosteal bone formation was not hampered. These changes in bone formation resulted in the abolishment of the expected increase in total cross-sectional area with reloading in Igf-1r−/− mice compared to the control mice. These results suggest that the Igf-1r in mature osteoblasts has a critical role in periosteal bone formation in the skeletal response to mechanical loading. PMID:23976802

  19. Androgen receptor roles in insulin resistance and obesity in males: the linkage of androgen-deprivation therapy to metabolic syndrome.

    Science.gov (United States)

    Yu, I-Chen; Lin, Hung-Yun; Sparks, Janet D; Yeh, Shuyuan; Chang, Chawnshang

    2014-10-01

    Prostate cancer (PCa) is one of the most frequently diagnosed malignancies in men. Androgen-deprivation therapy (ADT) is the first-line treatment and fundamental management for men with advanced PCa to suppress functions of androgen/androgen receptor (AR) signaling. ADT is effective at improving cancer symptoms and prolonging survival. However, epidemiological and clinical studies support the notion that testosterone deficiency in men leads to the development of metabolic syndrome that increases cardiovascular disease risk. The underlying mechanisms by which androgen/AR signaling regulates metabolic homeostasis in men are complex, and in this review, we discuss molecular mechanisms mediated by AR signaling that link ADT to metabolic syndrome. Results derived from various AR knockout mouse models reveal tissue-specific AR signaling that is involved in regulation of metabolism. These data suggest that steps be taken early to manage metabolic complications associated with PCa patients receiving ADT, which could be accomplished using tissue-selective modulation of AR signaling and by treatment with insulin-sensitizing agents.

  20. Solid lipid nanoparticles carrying chemotherapeutic drug across the blood-brain barrier through insulin receptor-mediated pathway.

    Science.gov (United States)

    Kuo, Yung-Chih; Shih-Huang, Chun-Yuan

    2013-09-01

    Carmustine (BCNU)-loaded solid lipid nanoparticles (SLNs) were grafted with 83-14 monoclonal antibody (MAb) (83-14 MAb/BCNU-SLNs) and applied to the brain-targeting delivery. Human brain-microvascular endothelial cells (HBMECs) incubated with 83-14 MAb/BCNU-SLNs were stained to demonstrate the interaction between the nanocarriers and expressed insulin receptors (IRs). The results revealed that the particle size of 83-14 MAb/BCNU-SLNs decreased with an increasing weight percentage of Dynasan 114 (DYN). Storage at 4 °C for 6 weeks slightly deformed the colloidal morphology. In addition, poloxamer 407 on 83-14 MAb/BCNU-SLNs induced cytotoxicity to RAW264.7 cells and inhibited phagocytosis by RAW264.7 cells. An increase in the weight percentage of DYN from 0% to 67% slightly reduced the viability of RAW264.7 cells and promoted phagocytosis. Moreover, the transport ability of 83-14 MAb/BCNU-SLNs across the blood-brain barrier (BBB) in vitro enhanced with an increasing weight percentage of Tween 80. 83-14 MAb on MAb/BCNU-SLNs stimulated endocytosis by HBMECs via IRs and enhanced the permeability of BCNU across the BBB. 83-14 MAb/BCNU-SLNs can be a promising antitumor drug delivery system for transporting BCNU to the brain.

  1. Insulin receptor A and Sirtuin 1 synergistically improve learning and spatial memory following chronic salidroside treatment during hypoxia.

    Science.gov (United States)

    Barhwal, Kalpana; Das, Saroj K; Kumar, Ashish; Hota, Sunil K; Srivastava, Ravi B

    2015-10-01

    Hypoxia has been reported to cause hippocampal neurodegeneration resulting in learning and memory deficits. In the present study, we investigated the potential of salidroside, a glucoside derivative of tyrosol, in ameliorating hypoxia-induced neurodegeneration and memory impairment. Morris water maze test showed improvement in learning and spatial memory of salidroside-treated hypoxic rats correlating with increased dendritic intersections and arborization. Salidroside administration increased phosphorylation of insulin receptor subunit A (IRA) at Y972, Y1162/63, and Y1146 sites and subsequent activation of AMP-activated protein kinase (AMPK) α subunit isoforms pAMPKα1 and pAMPKα2 resulting in mitochondrial biogenesis. Contrarily, silencing of IRA in salidroside-supplemented hypoxic hippocampal cells could not improve cell viability or alter pAMPKα1 and pAMPKα2 expression. Rats administered with salidroside showed elevated expression of phosphorylated cAMP response element-binding protein in the hippocampus. Salidroside administration also resulted in increased sirtuin 1 (SIRT1) activity through a cytochrome P4502E1 (CYP2E1)-regulated mechanism that was independent of pIRA. Taken together, these findings suggest a synergistic role of pIRA and SIRT1 in salidroside-mediated neuroprotection, mitochondrial biogenesis, and cognitive improvement during hypoxia. We propose a novel mechanism for salidroside-mediated neuroprotection in hypoxia. © 2015 International Society for Neurochemistry.

  2. EXPRESSION OF IGFBP-6 IN COLORECTAL CANCER: THE RELATION WITH INSULIN-LIKE GROWTH FACTOR RECEPTOR, ADIPONECTIN LEVEL AND ITS RECEPTORS

    Directory of Open Access Journals (Sweden)

    N. V. Yunusova

    2015-01-01

    Full Text Available The aim of the study was to investigate the expression of insulin-like growth factor binding protein 6 (IGFBP-6 in cancer tissues in relation with clinical and morphological parameters, IGF-IR expression, serum adiponectin level and its receptors (AdipoR1, AdipoR2 in patients with colorectal cancer.Material and Methods. The study included 31 patients with colorectal cancer (T2–4N0–2M0. Serum adiponectin level, AdipoR1 and AdipoR2 expression were evaluated with ELISA. IGF-IR expression was evaluated in tumor tissue by flow cytometry. IGFBP-6 expression was evaluated with Western blotting.Results. The dependence of IGFBP-6 expression, AdipoR1, AdipoR2 on tumor invasion and lymph nodes status were revealed. There is no association IGFBP-6 expression, AdipoR1 and AdipoR2 expression and serum adiponectin level with metabolic syndrome. The revealed positive relationships between IGFBP-6 expression and AdipoR1 expression, between IGFBP-6 expression and AdipoR2 expression, between IGF-IR and AdipoR1 expression show cross-talk between IGF-IR and adiponectin/AdipoR1 pathways in colorectal carcinomas.

  3. Circulating Insulin-Like Growth Factor I Regulates Its Receptor in the Brain of Male Mice.

    Science.gov (United States)

    Trueba-Saiz, A; Fernandez, A M; Nishijima, T; Mecha, M; Santi, A; Munive, V; Aleman, I Torres

    2017-02-01

    The role of IGF-1 and its receptor (IGF-1R) in brain pathology is still unclear. Thus, either reduction of IGF-IR or treatment with IGF-1, two apparently opposite actions, has proven beneficial in brain diseases such as Alzheimer's dementia. A possible explanation of this discrepancy is that IGF-1 down-regulates brain IGF-1R levels, as previously seen in a mouse Alzheimer's dementia model. We now explored whether under normal conditions IGF-1 modulates its receptor. We first observed that in vitro, IGF-1 reduced IGF-1R mRNA levels in all types of brain cells including neurons, astrocytes, microglia, endothelial cells, and oligodendrocytes. IGF-1 also inhibited its own expression in neurons and brain endothelium. Next, we analyzed the in vivo actions of IGF-1. Because serum IGF-1 can enter the brain, we injected mice with IGF-1 ip. As soon as 1 hour after the injection, decreased hippocampal IGF-1 levels were observed, followed by increased IGF-1 and IGF-1R mRNAs 6 hours later. Because environmental enrichment (EE) stimulates the entrance of serum IGF-1 into the brain, we analyzed whether a physiological entrance of IGF-1 also produced changes in brain IGF-1R. Stimulation of IGF-1R by EE triggered a gradual decrease in hippocampal IGF-1 levels. After 6 hours of EE exposure, IGF-1 levels reached a significant decrease in parallel with increased IGF-1R expression. After longer times, IGF-1R mRNA levels returned to baseline. Thus, under nonpathological conditions, IGF-1 regulates brain IGF-1R. Because baseline IGF-1R levels are rapidly restored, a tight control of brain IGF-1R expression seems to operate under physiological conditions. Copyright © 2017 by the Endocrine Society.

  4. Studies of the Pro12Ala polymorphism of the peroxisome proliferator-activated receptor-gamma2 (PPAR-gamma2) gene in relation to insulin sensitivity among glucose tolerant caucasians

    DEFF Research Database (Denmark)

    Ek, J; Andersen, G; Urhammer, S A;

    2001-01-01

    We examined whether the Pro12-Ala polymorphism of the human peroxisome proliferator-activated receptor-gamma2 (PPAR-gamma2) gene was related to altered insulin sensitivity among glucose-tolerant subjects or a lower accumulated incidence or prevalence of IGT and Type II (non-insulin-dependent) dia......We examined whether the Pro12-Ala polymorphism of the human peroxisome proliferator-activated receptor-gamma2 (PPAR-gamma2) gene was related to altered insulin sensitivity among glucose-tolerant subjects or a lower accumulated incidence or prevalence of IGT and Type II (non...

  5. Studies of the Pro12Ala polymorphism of the peroxisome proliferator-activated receptor-gamma2 (PPAR-gamma2) gene in relation to insulin sensitivity among glucose tolerant caucasians

    DEFF Research Database (Denmark)

    Ek, J; Andersen, G; Urhammer, S A

    2001-01-01

    We examined whether the Pro12-Ala polymorphism of the human peroxisome proliferator-activated receptor-gamma2 (PPAR-gamma2) gene was related to altered insulin sensitivity among glucose-tolerant subjects or a lower accumulated incidence or prevalence of IGT and Type II (non-insulin-dependent) dia......We examined whether the Pro12-Ala polymorphism of the human peroxisome proliferator-activated receptor-gamma2 (PPAR-gamma2) gene was related to altered insulin sensitivity among glucose-tolerant subjects or a lower accumulated incidence or prevalence of IGT and Type II (non...

  6. All-atom structural models for complexes of insulin-like growth factors IGF1 and IGF2 with their cognate receptor.

    Science.gov (United States)

    Vashisth, Harish; Abrams, Cameron F

    2010-07-16

    Type 1 insulin-like growth factor receptor (IGF1R) is a membrane-spanning glycoprotein of the insulin receptor family that has been implicated in a variety of cancers. The key questions related to molecular mechanisms governing ligand recognition by IGF1R remain unanswered, partly due to the lack of testable structural models of apo or ligand-bound receptor complexes. Using a homology model of the IGF1R ectodomain IGF1RDeltabeta, we present the first experimentally consistent all-atom structural models of IGF1/IGF1RDeltabeta and IGF2/IGF1RDeltabeta complexes. Our explicit-solvent molecular dynamics (MD) simulation of apo-IGF1RDeltabeta shows that it displays asymmetric flexibility mechanisms that result in one of two binding pockets accessible to growth factors IGF1 and IGF2, as demonstrated via an MD-assisted Monte Carlo docking procedure. Our MD-generated ensemble of structures of apo and IGF1-bound IGF1RDeltabeta agrees reasonably well with published small-angle X-ray scattering data. We observe simultaneous contacts of each growth factor with sites 1 and 2 of IGF1R, suggesting cross-linking of receptor subunits. Our models provide direct evidence in favor of suggested electrostatic complementarity between the C-domain (IGF1) and the cysteine-rich domain (IGF1R). Our IGF1/IGF1RDeltabeta model provides structural bases for the observation that a single IGF1 molecule binds to IGF1RDeltabeta at low concentrations in small-angle X-ray scattering studies. We also suggest new possible structural bases for differences in the affinities of insulin, IGF1, and IGF2 for their noncognate receptors.

  7. Substance P (SP)-neurokinin-1 receptor (NK-1R) alters adipose tissue responses to high-fat diet and insulin action.

    Science.gov (United States)

    Karagiannides, Iordanes; Stavrakis, Dimitris; Bakirtzi, Kyriaki; Kokkotou, Efi; Pirtskhalava, Tamara; Nayeb-Hashemi, Hamed; Bowe, Collin; Bugni, James M; Nuño, Miriam; Lu, Bao; Gerard, Norma P; Leeman, Susan E; Kirkland, James L; Pothoulakis, Charalabos

    2011-06-01

    Peripheral administration of a specific neurokinin-1 receptor (NK-1R) antagonist to mice leads to reduced weight gain and circulating levels of insulin and leptin after high-fat diet (HFD). Here, we assessed the contribution of substance P (SP) and NK-1R in diet-induced obesity using NK-1R deficient [knockout (KO)] mice and extended our previous findings to show the effects of SP-NK-1R interactions on adipose tissue-associated insulin signaling and glucose metabolic responses. NK-1R KO and wild-type (WT) littermates were fed a HFD for 3 wk, and obesity-associated responses were determined. Compared with WT, NK-1 KO mice show reduced weight gain and circulating levels of leptin and insulin in response to HFD. Adiponectin receptor mRNA levels are higher in mesenteric fat and liver in NK-1 KO animals compared with WT, after HFD. Mesenteric fat from NK-1R KO mice fed with HFD has reduced stress-activated protein kinase/c-Jun N-terminal kinase and protein kinase C activation compared with WT mice. After glucose challenge, NK-1R KO mice remove glucose from the circulation more efficiently than WT and pair-fed controls, suggesting an additional peripheral effect of NK-1R-mediated signaling on glucose metabolism. Glucose uptake experiments in isolated rat adipocytes showed that SP directly inhibits insulin-mediated glucose uptake. Our results further establish a role for SP-NK-1R interactions in adipose tissue responses, specifically as they relate to obesity-associated pathologies such as glucose intolerance and insulin resistance. Our results highlight this pathway as an important therapeutic approach for type 2 diabetes.

  8. Expression of human apolipoprotein E4 reduces insulin-receptor substrate 1 expression and Akt phosphorylation in the ageing liver

    Directory of Open Access Journals (Sweden)

    Qi-Rui Ong

    2014-01-01

    Full Text Available The diabetic drug rosiglitazone was reported to improve glucose tolerance in insulin-resistant ApoE3 but not ApoE4 knock-in mice. We therefore examined whether apolipoprotein E (ApoE has genotype-specific effects on liver insulin function. At 12 weeks, no difference in liver insulin signaling was detected between fasting ApoE3 and ApoE4 mice. At 72 weeks however, ApoE4 mice had lower IRS-1 and PI3K expression, and reduced Akt phosphorylation. This decline was associated with lower insulin and higher glucose in ApoE4 mouse liver. Liver cholesterol was not affected. These results show that ApoE4 expression reduces liver insulin signaling and insulin levels, leading to higher glucose content.

  9. Potentiation of insulin secretion and improvement of glucose intolerance by combining a novel G protein-coupled receptor 40 agonist DS-1558 with glucagon-like peptide-1 receptor agonists.

    Science.gov (United States)

    Nakashima, Ryutaro; Yano, Tatsuya; Ogawa, Junko; Tanaka, Naomi; Toda, Narihiro; Yoshida, Masao; Takano, Rieko; Inoue, Masahiro; Honda, Takeshi; Kume, Shoen; Matsumoto, Koji

    2014-08-15

    G protein-coupled receptor 40 (GPR40) is a Gq-coupled receptor for free fatty acids predominantly expressed in pancreatic β-cells. In recent years, GPR40 agonists have been investigated for use as novel therapeutic agents in the treatment of type 2 diabetes. We discovered a novel small molecule GPR40 agonist, (3S)-3-ethoxy-3-(4-{[(1R)-4-(trifluoromethyl)-2,3-dihydro-1H-inden-1-yl]oxy}phenyl)propanoic acid (DS-1558). The GPR40-mediated effects of DS-1558 on glucose-stimulated insulin secretion were evaluated in isolated islets from GPR40 knock-out and wild-type (littermate) mice. The GPR40-mediated effects on glucose tolerance and insulin secretion were also confirmed by an oral glucose tolerance test in these mice. Furthermore, oral administration of DS-1558 (0.03, 0.1 and 0.3mg/kg) significantly and dose-dependently improved hyperglycemia and increased insulin secretion during the oral glucose tolerance test in Zucker fatty rats, the model of insulin resistance and glucose intolerance. Next, we examined the combination effects of DS-1558 with glucagon like peptide-1 (GLP-1). DS-1558 not only increased the glucose-stimulated insulin secretion by GLP-1 but also potentiated the maximum insulinogenic effects of GLP-1 after an intravenous glucose injection in normal Sprague Dawley rats. Furthermore, the glucose lowering effects of exendin-4, a GLP-1 receptor agonist, were markedly potentiated by the DS-1558 (3mg/kg) add-on in diabetic db/db mice during an intraperitoneal glucose tolerance test. In conclusion, our results indicate that add-on GPR40 agonists to GLP-1 related agents might be a potential treatment compared to single administration of these compounds. Therefore the combinations of these agents are a novel therapeutic option for type 2 diabetes.

  10. Cholesterol reduction ameliorates glucose-induced calcium handling and insulin secretion in islets from low-density lipoprotein receptor knockout mice.

    Science.gov (United States)

    Souza, J C; Vanzela, E C; Ribeiro, R A; Rezende, L F; de Oliveira, C A; Carneiro, E M; Oliveira, H C F; Boschero, A C

    2013-04-01

    Changes in cellular cholesterol level may contribute to beta cell dysfunction. Islets from low density lipoprotein receptor knockout (LDLR(-/-)) mice have higher cholesterol content and secrete less insulin than wild-type (WT) mice. Here, we investigated the association between cholesterol content, insulin secretion and Ca(2+) handling in these islets. Isolated islets from both LDLR(-/-) and WT mice were used for measurements of insulin secretion (radioimmunoassay), cholesterol content (fluorimetric assay), cytosolic Ca(2+) level (fura-2AM) and SNARE protein expression (VAMP-2, SNAP-25 and syntaxin-1A). Cholesterol was depleted by incubating the islets with increasing concentrations (0-10mmol/l) of methyl-beta-cyclodextrin (MβCD). The first and second phases of glucose-stimulated insulin secretion (GSIS) were lower in LDLR(-/-) than in WT islets, paralleled by an impairment of Ca(2+) handling in the former. SNAP-25 and VAMP-2, but not syntaxin-1A, were reduced in LDLR(-/-) compared with WT islets. Removal of excess cholesterol from LDLR(-/-) islets normalized glucose- and tolbutamide-induced insulin release. Glucose-stimulated Ca(2+) handling was also normalized in cholesterol-depleted LDLR(-/-) islets. Cholesterol removal from WT islets by 0.1 and 1.0mmol/l MβCD impaired both GSIS and Ca(2+) handling. In addition, at 10mmol/l MβCD WT islet showed a loss of membrane integrity and higher DNA fragmentation. Abnormally high (LDLR(-/-) islets) or low cholesterol content (WT islets treated with MβCD) alters both GSIS and Ca(2+) handling. Normalization of cholesterol improves Ca(2+) handling and insulin secretion in LDLR(-/-) islets. Copyright © 2013 Elsevier B.V. All rights reserved.

  11. Implication of insulin receptor A isoform and IRA/IGF-IR hybrid receptors in the aortic vascular smooth muscle cell proliferation: role of TNF-α and IGF-II.

    Science.gov (United States)

    Gómez-Hernández, Almudena; Escribano, Óscar; Perdomo, Liliana; Otero, Yolanda F; García-Gómez, Gema; Fernández, Silvia; Beneit, Nuria; Benito, Manuel

    2013-07-01

    To assess the role of insulin receptor (IR) isoforms (IRA and IRB) in the proliferation of vascular smooth muscle cells (VSMCs) involved in the atherosclerotic process, we generated new VSMC lines bearing IR (wild-type VSMCs; IRLoxP(+/+) VSMCs), lacking IR (IR(-/-) VSMCs) or expressing IRA (IRA VSMCs) or IRB (IRB VSMCs). Insulin and different proatherogenic stimuli induced a significant increase of IRA expression in IRLoxP(+/+) VSMCs. Moreover, insulin, through ERK signaling, and the proatherogenic stimuli, through ERK and p38 signaling, induced a higher proliferation in IRA than IRB VSMCs. The latter effect might be due to IRA cells showing a higher expression of angiotensin II, endothelin 1, and thromboxane 2 receptors and basal association between IRA and these receptors. Furthermore, TNF-α induced in a ligand-dependent manner a higher association between IRA and TNF-α receptor 1 (TNF-R1). On the other hand, IRA overexpression might favor the atherogenic actions of IGF-II. Thereby, IGF-II or TNF-α induced IRA and IGF-I receptor (IGF-IR) overexpression as well as an increase of IRA/IGF-IR hybrid receptors in VSMCs. More importantly, we observed a significant increase of IRA, TNF-R1, and IGF-IR expression as well as higher association of IRA with TNF-R1 or IGF-IR in the aorta from ApoE(-/-) and BATIRKO mice, 2 models showing vascular damage. In addition, anti-TNF-α treatment prevented those effects in BATIRKO mice. Finally, our data suggest that the IRA isoform and its association with TNF-R1 or IGF-IR confers proliferative advantage to VSMCs, mainly in response to TNF-α or IGF-II, which might be of significance in the early atherosclerotic process.

  12. Insulin-like growth factors (IGFs) stimulate the release of alpha 1-antichymotrypsin and soluble IGF-II/mannose 6-phosphate receptor from MCF7 breast cancer cells.

    Science.gov (United States)

    Confort, C; Rochefort, H; Vignon, F

    1995-09-01

    The growth of hormone-responsive MCF7 human breast cancer cells is controlled by steroid hormones and growth factors. By metabolic labeling of cells grown in steroid- and growth factor-stripped serum conditions, we show that insulin-like growth factors (IGF-I and IGF-II) increase by approximately 5-fold the release of several proteins including cathepsin D, alpha 1-antichymotrypsin, and soluble forms of the multifunctional IGF-II/mannose 6-phosphate (M6P) receptor. Two soluble forms of IGF-II/M6P receptors were detected, one major (approximately 260 kilodaltons) and one minor (approximately 85 kilodaltons) that probably represents a proteolytic fragment of the larger soluble molecule. IGFs increased receptor release in a dose-dependent fashion with 50-60% of newly synthesized receptor released at 5-10 nM IGFs. The release of IGF-II/M6P receptors correlated with the levels of secreted cathepsin D in different human breast cancer cells or in rats stable transfectants that are constitutively expressing variable levels of human cathepsin D. IGFs had a stronger effect on IGF-II/M6P receptor release, whereas estradiol treatment preferentially enhanced the release of protease and antiprotease. We thus demonstrate that in human breast cancer cells, IGFs not only act as strong mitogens but also regulate release of alpha 1-antichymotrypsin, IGF-II/M6P-soluble receptor, and cathepsin D; three proteins that potentially regulate cell proliferation and/or invasion.

  13. Novel covalently linked insulin dimer engineered to investigate the function of insulin dimerization

    DEFF Research Database (Denmark)

    Vinther, Tine N.; Norrman, Mathias; Strauss, Holger M.

    2012-01-01

    An ingenious system evolved to facilitate insulin binding to the insulin receptor as a monomer and at the same time ensure sufficient stability of insulin during storage. Insulin dimer is the cornerstone of this system. Insulin dimer is relatively weak, which ensures dissociation into monomers...

  14. A Novel Partial Agonist of Peroxisome Proliferator-Activated Receptor γ with Excellent Effect on Insulin Resistance and Type 2 Diabetes.

    Science.gov (United States)

    Liu, Hui-juan; Zhang, Cheng-yu; Song, Fei; Xiao, Ting; Meng, Jing; Zhang, Qiang; Liang, Cai-li; Li, Shan; Wang, Jing; Zhang, Bo; Liu, Yan-rong; Sun, Tao; Zhou, Hong-gang

    2015-06-01

    Partial agonists of peroxisome proliferator-activated receptor γ (PPARγ) reportedly reverse insulin resistance in patients with type 2 diabetes mellitus. In this work, a novel non-thiazolidinedione-partial PPARγ ligand, MDCCCL1636 [N-(4-hydroxyphenethyl)-3-mercapto-2-methylpropanamide], was investigated. The compound displayed partial agonist activity in biochemical and cell-based transactivation assays and reversed insulin resistance. MDCCCL1636 showed a potential antidiabetic effect on an insulin-resistance model of human hepatocarcinoma cells (HepG2). High-fat diet-fed streptozotocin-induced diabetic rats treated with MDCCCL1636 for 56 days displayed reduced fasting serum glucose and reversed dyslipidemia and pancreatic damage without significant weight gain. Furthermore, MDCCCL1636 had lower toxicity in vivo and in vitro than pioglitazone. MDCCCL1636 also potentiated glucose consumption and inhibited the impairment in insulin signaling targets, such as AKT, glycogen synthase kinase 3β, and glycogen synthase, in HepG2 human hepatoma cells. Overall, our results suggest that MDCCCL1636 is a promising candidate for the prevention and treatment of type 2 diabetes mellitus.

  15. C333H ameliorated insulin resistance through selectively modulating peroxisome proliferator-activated receptor γ in brown adipose tissue of db/db mice.

    Science.gov (United States)

    Zhang, Ning; Chen, Wei; Zhou, Xinbo; Zhou, Xiaolin; Xie, Xinni; Meng, Aimin; Li, Song; Wang, Lili

    2013-01-01

    Peroxisome proliferator-activated receptor γ (PPARγ) is a unique target for insulin sensitizer agents. These drugs have been used for the clinical treatment of type 2 diabetes for almost twenty years. However, serious safety issues are associated with the PPARγ agonist thiazolidinediones (TZDs). Selective PPARγ modulators (SPPARMs) which retain insulin sensitization without TZDs-like side effects are emerging as a promising new generation of insulin sensitizers. C333H is a novel structure compound synthesized by our laboratory. In diabetic rodent models, C333H has insulin-sensitizing and glucose-lowering activity comparable to that of TZDs, and causes no significant increase in body weight or adipose tissue weight in db/db mice. In diabetic db/db mice, C333H elevated circulating high molecular weight adiponectin isoforms, decreased PPARγ 273 serine phosphorylation in brown adipose tissue and selectively modulated the expression of a subset of PPARγ target genes in adipose tissue. In vitro, C333H weakly recruited coactivator and weakly dissociated corepressor activity. These findings suggest that C333H has similar properties to SPPARMs and may be a potential therapeutic agent for the treatment of type 2 diabetes.

  16. Sustained Brown Fat Stimulation and Insulin Sensitization by a Humanized Bispecific Antibody Agonist for Fibroblast Growth Factor Receptor 1/βKlotho Complex

    Directory of Open Access Journals (Sweden)

    Ganesh Kolumam

    2015-07-01

    Full Text Available Dissipating excess calories as heat through therapeutic stimulation of brown adipose tissues (BAT has been proposed as a potential treatment for obesity-linked disorders. Here, we describe the generation of a humanized effector-less bispecific antibody that activates fibroblast growth factor receptor (FGFR 1/βKlotho complex, a common receptor for FGF21 and FGF19. Using this molecule, we show that antibody-mediated activation of FGFR1/βKlotho complex in mice induces sustained energy expenditure in BAT, browning of white adipose tissue, weight loss, and improvements in obesity-associated metabolic derangements including insulin resistance, hyperglycemia, dyslipidemia and hepatosteatosis. In mice and cynomolgus monkeys, FGFR1/βKlotho activation increased serum high-molecular-weight adiponectin, which appears to contribute over time by enhancing the amplitude of the metabolic benefits. At the same time, insulin sensitization by FGFR1/βKlotho activation occurs even before the onset of weight loss in a manner that is independent of adiponectin. Together, selective activation of FGFR1/βKlotho complex with a long acting therapeutic antibody represents an attractive approach for the treatment of type 2 diabetes and other obesity-linked disorders through enhanced energy expenditure, insulin sensitization and induction of high-molecular-weight adiponectin.

  17. Tesaglitazar, a dual peroxisome proliferator-activated receptor alpha/gamma agonist, improves apolipoprotein levels in non-diabetic subjects with insulin resistance

    DEFF Research Database (Denmark)

    Schuster, H.; Fagerberg, B.; Edwards, S.

    2008-01-01

    Aim: To determine the effects of the peroxisome proliferator-activated receptor (PPAR) alpha/gamma agonist tesaglitazar on serum levels of apolipoprotein (apo) A-I, apoB, and apoCIII in non-diabetic insulin-resistant subjects. Methods: This randomized, double-blind, multicentre, placebo-controlle......Aim: To determine the effects of the peroxisome proliferator-activated receptor (PPAR) alpha/gamma agonist tesaglitazar on serum levels of apolipoprotein (apo) A-I, apoB, and apoCIII in non-diabetic insulin-resistant subjects. Methods: This randomized, double-blind, multicentre, placebo...... associated with insulin resistance. (C) 2007 Elsevier Ireland Ltd. All rights reserved Udgivelsesdato: 2008/3......-controlled trial examined the effect of tesaglitazar (0.1, 0.25, 0.5, and 1 mg) once daily for 12 weeks on apolipoprotein levels in 390 abdominally obese subjects with hypertriglyceridaemia. Results: Tesaglitazar dose-dependently increased serum concentrations of apoA-I (p

  18. Modulating effects of omega-3 fatty acids and pioglitazone combination on insulin resistance through toll-like receptor 4 in type 2 diabetes mellitus.

    Science.gov (United States)

    Eraky, Salma M; Abdel-Rahman, Noha; Eissa, Laila A

    2017-06-17

    Toll-like receptor 4 (TLR-4) plays important roles in innate immunity. Changes in the reduction-oxidation balance of tissues can lead to a pro-inflammatory state and insulin resistance. An action thought to be mediated by TLRs. Omega-3 fatty acids and Peroxisome Proliferator Activated Receptor gamma (PPAR-γ) agonists as pioglitazone are used for decreasing inflammation. The aim of this study is to investigate the anti-diabetic effects of combining omega -3 fatty acid with pioglitazone on type 2 diabetes, and the modifying effects on TLR-4. Type 2 diabetes was induced in male Sprague-Dawley rats by combination of high fat diet and low dose streptozotocin (35mg/kg). Diabetic rats were treated with omega-3 fatty acids (10% W/W diet), pioglitazone (20mg/kg), and their combination for 4 weeks. Omega-3 fatty acids and the combination treatment significantly decreased TLR-4 activation. Omega-3 fatty acids, pioglitazone, and their combination significantly decreased TLR-4 mRNA expression, hepatic malondialdehyde, total cholesterol and triglycerides levels, compared to diabetic group. Pioglitazone and the combination significantly decreased blood glucose levels and improved insulin resistance. In conclusion, combining omega-3 fatty acids with pioglitazone showed potential effects in lowering blood glucose levels and improving lipid profile and insulin resistance. Such effects are mediated through modulation of TLR-4. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Sustained Brown Fat Stimulation and Insulin Sensitization by a Humanized Bispecific Antibody Agonist for Fibroblast Growth Factor Receptor 1/βKlotho Complex.

    Science.gov (United States)

    Kolumam, Ganesh; Chen, Mark Z; Tong, Raymond; Zavala-Solorio, Jose; Kates, Lance; van Bruggen, Nicholas; Ross, Jed; Wyatt, Shelby K; Gandham, Vineela D; Carano, Richard A D; Dunshee, Diana Ronai; Wu, Ai-Luen; Haley, Benjamin; Anderson, Keith; Warming, Søren; Rairdan, Xin Y; Lewin-Koh, Nicholas; Zhang, Yingnan; Gutierrez, Johnny; Baruch, Amos; Gelzleichter, Thomas R; Stevens, Dale; Rajan, Sharmila; Bainbridge, Travis W; Vernes, Jean-Michel; Meng, Y Gloria; Ziai, James; Soriano, Robert H; Brauer, Matthew J; Chen, Yongmei; Stawicki, Scott; Kim, Hok Seon; Comps-Agrar, Laëtitia; Luis, Elizabeth; Spiess, Christoph; Wu, Yan; Ernst, James A; McGuinness, Owen P; Peterson, Andrew S; Sonoda, Junichiro

    2015-07-01

    Dissipating excess calories as heat through therapeutic stimulation of brown adipose tissues (BAT) has been proposed as a potential treatment for obesity-linked disorders. Here, we describe the generation of a humanized effector-less bispecific antibody that activates fibroblast growth factor receptor (FGFR) 1/βKlotho complex, a common receptor for FGF21 and FGF19. Using this molecule, we show that antibody-mediated activation of FGFR1/βKlotho complex in mice induces sustained energy expenditure in BAT, browning of white adipose tissue, weight loss, and improvements in obesity-associated metabolic derangements including insulin resistance, hyperglycemia, dyslipidemia and hepatosteatosis. In mice and cynomolgus monkeys, FGFR1/βKlotho activation increased serum high-molecular-weight adiponectin, which appears to contribute over time by enhancing the amplitude of the metabolic benefits. At the same time, insulin sensitization by FGFR1/βKlotho activation occurs even before the onset of weight loss in a manner that is independent of adiponectin. Together, selective activation of FGFR1/βKlotho complex with a long acting therapeutic antibody represents an attractive approach for the treatment of type 2 diabetes and other obesity-linked disorders through enhanced energy expenditure, insulin sensitization and induction of high-molecular-weight adiponectin.

  20. Recent advancements in small molecule inhibitors of insulin-like growth factor-1 receptor (IGF-1R) tyrosine kinase as anticancer agents.

    Science.gov (United States)

    Negi, Arvind; Ramarao, P; Kumar, Raj

    2013-04-01

    Advancements in understanding of the genetics, genomics, biochemistry and the pharmacology of cancer inhuman, have driven the current cancer chemotherapy to intently focus on development of target-based approaches rather than conventional approaches. From among the various targets identified, validated and inhibited at different hallmarks of cancer, protein tyrosine kinases (PTKs) have been exploited the most. Insulin receptors (IRs), insulin like growth factor receptors (IGF-1R) and their hybrid receptors belong to tyrosine kinase receptor (TKR) family, constitute a structural homology among them and generate a growth promoting IGF system on binding with either insulin, IGF-1 or IGF-2. The system induces the mitogenic effects through a torrent of cell signals produced as a result of cross talk with other growth promoting peptides and steroidal hormones, ultimately resulting in hijacking apoptosis and increasing cell proliferation and cell survival in cancer cells. Various strategies such as anti-IGF-1R antibodies, IGF-1 mimetic peptides, antisense strategies, IGF-1R specific peptide aptamers, targeted degradation of IGF-1R and expression of dominant negative IGF-1R mutants have been explored to inhibit the IGF-1R signaling. However, targeting IGF-1R with small molecules has gained considerable attention in last few years due to their ease of synthesis, ease of optimization of absorption,distribution, metabolism, excretion and toxicity (ADMET) parameters, oral route of administration, lesser side effects and cost effectiveness. The present review provides a broad overview and discusses the highlights on discoveries, SAR studies and binding interactions of small molecules with either IGF-1R active or allosteric sites reported till date.

  1. Insulin-like growth factor 1 receptor and response to anti-IGF1R antibody therapy in osteosarcoma.

    Directory of Open Access Journals (Sweden)

    Yu Cao

    Full Text Available Survival outcomes for patients with osteosarcoma (OS have remained stagnant over the past three decades. Insulin-like growth factor 1 receptor (IGF1R is over-expressed in a number of malignancies, and anti-IGF1R antibodies have and are currently being studied in clinical trials. Understanding the molecular aberrations which result in increased tumor response to anti-IGF1R therapy could allow for the selection of patients most likely to benefit from IGF1R targeted therapy.IGF1R mRNA expression was assessed by RT PCR in OS patient primary tumors, cell lines, and xenograft tumors. IGF1R copy number was assessed by 3 approaches: PCR, FISH, and dot blot analysis. Exons 1-20 of IGF1R were sequenced in xenograft tumors and 87 primary OS tumors, and surface expression of IGF1R was assessed by flow cytometry. Levels of mRNA and protein expression, copy number, and mutation status were compared with tumor response to anti-IGF1R antibody therapy in 4 OS xenograft models.IGF1R mRNA is expressed in OS. Primary patient samples and xenograft samples had higher mRNA expression and copy number compared with corresponding cell lines. IGF1R mRNA expression, cell surface expression, copy number, and mutation status were not associated with tumor responsiveness to anti-IGF1R antibody therapy.IGF1R is expressed in OS, however, no clear molecular markers predict response to IGF1R antibody-mediated therapy. Additional pre-clinical studies assessing potential predictive biomarkers and investigating targetable molecular pathways critical to the proliferation of OS cells are needed.

  2. Hyperosmotic stress inhibits insulin receptor substrate-1 function by distinct mechanisms in 3T3-L1 adipocytes

    DEFF Research Database (Denmark)

    Gual, Philippe; Gonzalez, Teresa; Grémeaux, Thierry

    2003-01-01

    . In addition, prolonged osmotic stress enhanced the degradation of IRS proteins through a rapamycin-insensitive pathway and a proteasome-independent process. These data support evidence of new mechanisms involved in osmotic stress-induced cellular insulin resistance. Short-term osmotic stress induces......-regulation of insulin action....

  3. [Insulin receptor expression in subcellular fractions of muscular and adipose tissue as the factor of the tissue insulin resistance development in rats under conditions of the high-energy diet].

    Science.gov (United States)

    Kondro, M M; Halenova, T I; Kuznietsova, M Iu; Savchuk, O M

    2013-01-01

    Nowadays the problem of insulin resistance, which has close cause-effect relations with obesity, diabetes mellitus type 2, metabolic syndrome, etc., is of urgent importance in medicine. We have revealed bidirectional changes of the IR content in crude membrane and cytosol of the adipose tissue cells in rats under conditions of the long-term high-energy diet. It is possible that reduction of the IR content in the adipose tissue cells has been predetermined by the disruption of lipid bilayer of adipocytes as a result of peroxidation processes activation. Increase in the IR content in the cytosol of cells of this tissue may indicate the activation of synthesis of this protein; however, it is possible that the IR translocation process disorder occurs due to the damage of plasma membrane, preventing the transfer of newly synthesized molecules of the receptor to the membrane and causing their accumulation in cytosol. The obtained results show that the tissues react to the long-term consumption of high-energy food in different ways. Thus, the content of insulin receptors in the plasma membrane of the muscle tissue cells increases, and, on the contrary, it decreases in adipose tissue cells. Such results may indicate that IR development at the late period of the experiment is likely the result of the adipose tissue cells disfunction. The obtained data may be of high significance in understanding the mechanism of the IR development under conditions of the long-term consumption of the high-energy food.

  4. Peroxisome proliferator-activated receptor alpha (PPARalpha) potentiates, whereas PPARgamma attenuates, glucose-stimulated insulin secretion in pancreatic beta-cells

    DEFF Research Database (Denmark)

    Ravnskjaer, Kim; Boergesen, Michael; Rubi, Blanca

    2005-01-01

    Fatty acids (FAs) are known to be important regulators of insulin secretion from pancreatic beta-cells. FA-coenzyme A esters have been shown to directly stimulate the secretion process, whereas long-term exposure of beta-cells to FAs compromises glucose-stimulated insulin secretion (GSIS...... receptor alpha (RXRalpha) in INS-1E beta-cells synergistically and in a dose- and ligand-dependent manner increases the expression of known PPARalpha target genes and enhances FA uptake and beta-oxidation. In contrast, ectopic expression of PPARgamma/RXRalpha increases FA uptake and deposition...... proton gradient. Importantly, whereas expression of PPARgamma/RXRalpha attenuates GSIS, the expression of PPARalpha/RXRalpha potentiates GSIS in rat islets and INS-1E cells without affecting the mitochondrial membrane potential. These results show a strong subtype specificity of the two PPAR subtypes...

  5. Activation of α7 nicotinic acetylcholine receptor decreases on-site mortality in crush syndrome through insulin signaling-Na/K-ATPase pathway

    Directory of Open Access Journals (Sweden)

    Bo-Shi eFan

    2016-03-01

    Full Text Available On-site mortality in crush syndrome remains high due to lack of effective drugs based on definite diagnosis. Anisodamine is widely used in China for treatment of shock, and activation of α7 nicotinic acetylcholine receptor (α7nAChR mediates such antishock effect. The present work was designed to test whether activation of α7nAChR with anisodamine decreased mortality in crush syndrome shortly after decompression. Sprague-Dawley rats and C57BL/6 mice with crush syndrome were injected with anisodamine (20 mg/kg and 28 mg/kg respectively, i.p. 30 min before decompression. Survival time, serum potassium, insulin, and glucose levels were observed shortly after decompression. Involvement of α7nAChR was verified with methyllycaconitine (selective α7nAChR antagonist and PNU282987 (selective α7nAChR agonist, or in α7nAChR knockout mice. Effect of anisodamine was also appraised in C2C12 myotubes. Anisodamine reduced mortality and serum potassium and enhanced insulin sensitivity shortly after decompression in animals with crush syndrome, and PNU282987 exerted similar effects. Such effects were counteracted by methyllycaconitine or in α7nAChR knockout mice. Mortality and serum potassium in rats with hyperkalemia were also reduced by anisodamine. Phosphorylation of Na/K-ATPase was enhanced by anisodamine in C2C12 myotubes. Inhibition of tyrosine kinase on insulin receptor, phosphoinositide 3-kinase, mammalian target of rapamycin, signal transducer and activator of transcription 3, and Na/K-ATPase counteracted the effect of anisodamine on extracellular potassium. These findings demonstrated that activation of α7nAChR could decrease on-site mortality in crush syndrome, at least in part based on the decline of serum potassium through insulin signaling-Na/K-ATPase pathway.

  6. 2型糖尿病患者血清胰岛素受体抗体的检测%The detection of anti-insulin receptor antibodies in serum of diabetes mellitus

    Institute of Scientific and Technical Information of China (English)

    朱宁; 王嘉仪; 王维兆; 汤新之

    2001-01-01

    Objective: To establish a method of detecting anti-insulin receptor antibodies of serum and study the relationship between anti-insulin receptor antibody and insulin resistance.Methods: The specfic 125I-insulin binding to insulin receptor with serum was measured by radioimmunoassay. Results: CV (coefficient of variation) within the batch was 4.9%. CV between the batches was 12.5%. There were anti-insulin receptor antibodies in 3 of 26 diabetes mellitus. Conclusion: Anti-insulin receptor antibodies could have resulted in insulin resistance.%目的:建立血清胰岛素受体抗体的检测方法,探讨胰岛素受体抗体与胰岛素抵抗的关系。方法:放射免疫分[摘要]目的:建立血清胰岛素受体抗体的检测方法,探讨胰岛素受体抗体与胰岛素抵抗的关系。方法:放射免疫分析法测定去胰岛素血清对125I-胰岛素与胰岛素受体特异结合的影响。结果:批内变异系数为4.9%,批间变异系数为12.5%。26例2型糖尿病患者中有3例呈胰岛素受体抗体阳性。结论:胰岛素受体抗体与胰岛素抵抗密切相关。

  7. Estrogen and exercise may enhance beta-cell function and mass via insulin receptor substrate 2 induction in ovariectomized diabetic rats.

    Science.gov (United States)

    Choi, Soo Bong; Jang, Jin Sun; Park, Sunmin

    2005-11-01

    The prevalence and progression of type 2 diabetes have increased remarkably in postmenopausal women. Although estrogen replacement and exercise have been studied for their effect in modulating insulin sensitivity in the case of insufficient estrogen states, their effects on beta-cell function and mass have not been studied. Ovariectomized (OVX) female rats with 90% pancreatectomy were given a 30% fat diet for 8 wk with a corresponding administration of 17beta-estradiol (30 microg/kg body weight) and/or regular exercise. Amelioration of insulin resistance by estrogen replacement or exercise was closely related to body weight reduction. Insulin secretion in first and second phases was lower in OVX during hyperglycemic clamp, which was improved by estrogen replacement and exercise but not by weight reduction induced by restricted diets. Both estrogen replacement and exercise overcame reduced pancreatic beta-cell mass in OVX rats via increased proliferation and decreased apoptosis of beta-cells, but they did not exhibit an additive effect. However, restricted diets did not stimulate beta-cell proliferation. Increased beta-cell proliferation was associated with the induction of insulin receptor substrate-2 and pancreatic homeodomain protein-1 via the activation of the cAMP response element binding protein. Estrogen replacement and exercise shared a common pathway, which led to the improvement of beta-cell function and mass, via cAMP response element binding protein activation, explaining the lack of an additive effect with combined treatments. In conclusion, decreased beta-cell mass leading to impaired insulin secretion triggers glucose dysregulation in estrogen insufficiency, regardless of body fat. Regular moderate exercise eliminates the risk factors of contracting diabetes in the postmenopausal state.

  8. Severely Obese Adolescents and Adults Exhibit a Different Association of Circulating Levels of Adipokines and Leukocyte Expression of the Related Receptors with Insulin Resistance

    Directory of Open Access Journals (Sweden)

    Antonello E. Rigamonti

    2013-01-01

    Full Text Available Obese adults frequently exhibit a low-grade inflammation and insulin resistance, which have been hypothesized to be established early in childhood. Aim of this study was to evaluate the age-dependent relationships between inflammatory state and insulin resistance in obese adolescents and adults. Clinical and metabolic parameters, circulating adipokines (TNF-α, adiponectin, and leptin, ghrelin, their leukocyte receptors (TNFR1, ADIPOR2, OBRL and GHSR1a, and acute phase reactants (CRP and white blood cells were assessed in lean and obese adolescents compared with the adult counterparts. Only obese adults had higher HOMA-IR, insulin, and triglycerides compared to the lean group. An inflammatory state was present in obese adolescents and adults, as demonstrated by the higher values of CRP and neutrophils. There were no group differences in circulating levels of TNF-α and leukocyte expression of TNFR1. Adiponectin concentrations and leukocyte expression of ADIPOR2 were higher in the lean groups than in the corresponding obese counterparts. For leptin and leukocyte expression of OBRL, the results were opposed. Circulating levels of ghrelin were higher in lean adolescents and adults than the related lean groups, while there was a higher leukocyte expression of GHSR1a in (only lean adults than obese adults. When the analysis was performed in (lean or obese adults, TNF-α, neutrophils, leptin, and GHSR1a were predictors of HOMA-IR. None of the considered independent variables accounted for the degree of insulin resistance in the adolescent group. In conclusion, a dissociation between the low-grade inflammation and insulin resistance is supposed to exist in the early phases of obesity.

  9. Insulin Secretagogues

    Science.gov (United States)

    ... 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) ...

  10. Solution structure of human insulin-like growth factor II; recognition sites for receptors and binding proteins.

    OpenAIRE

    Terasawa, H; Kohda, D.; Hatanaka, H; Nagata, K.; Higashihashi, N; Fujiwara, H.; Sakano, K; Inagaki, F.

    1994-01-01

    The three-dimensional structure of human insulin-like growth factor II was determined at high resolution in aqueous solution by NMR and simulated annealing based calculations. The structure is quite similar to those of insulin and insulin-like growth factor I, which consists of an alpha-helix followed by a turn and a strand in the B-region and two antiparallel alpha-helices in the A-region. However, the regions of Ala1-Glu6, Pro31-Arg40 and Thr62-Glu67 are not well-defined for lack of distanc...

  11. The insulin receptor substrate-1-related 4PS substrate but not the interleukin-2R gamma chain is involved in interleukin-13-mediated signal transduction.

    Science.gov (United States)

    Wang, L M; Michieli, P; Lie, W R; Liu, F; Lee, C C; Minty, A; Sun, X J; Levine, A; White, M F; Pierce, J H

    1995-12-01

    Interleukin-13 (IL-13) induced a potent mitogenic response in IL-3-dependent TF-1 cells and DNA synthesis to a lesser extent in MO7E and FDC-P1 cells. IL-13 stimulation of these lines, like IL-4 and insulin-like growth factor-1 (IGF-1), resulted in tyrosine phosphorylation of a 170-kD substrate. The tyrosine-phosphorylated 170-kD substrate strongly associated with the 85-kD subunit of phosphoinositol-3 (PI-3) kinase and with Grb-2. Anti-4PS serum readily detected the 170-kD substrate in lysates from both TF-1 and FDC-P1 cells stimulated with IL-13 or IL-4. These data provide evidence that IL-13 induces tyrosine phosphorylation of the 4PS substrate, providing an essential interface between the IL-13 receptor and signaling molecules containing SH2 domains. IL-13 and IL-4 stimulation of murine L cell fibroblasts, which endogenously express the IL-4 receptor (IL-4R alpha) and lack expression of the IL-2 receptor gamma subunit (IL-2R gamma), resulted in tyrosine phosphorylation of insulin receptor substrate-1 (IRS-1)/4PS. Enhanced tyrosine phosphorylation of IRS-1/4PS was observed in response to IL-4, but not IL-13 treatment of L cells transfected with the IL-2R gamma chain. These results indicate that IL-13 does not use the IL-2R gamma subunit in its receptor complex and that expression of IL-2R gamma enhances, but is not absolutely required for mediating IL-4-induced tyrosine phosphorylation of IRS-1/4PS.

  12. Prolonged Activation of the Htr2b Serotonin Receptor Impairs Glucose Stimulated Insulin Secretion and Mitochondrial Function in MIN6 Cells

    Science.gov (United States)

    Cataldo, Luis Rodrigo; Mizgier, María L.; Bravo Sagua, Roberto; Jaña, Fabián; Cárdenas, César; Llanos, Paola; Busso, Dolores; Olmos, Pablo; Galgani, José E.; Santos, José L.; Cortés, Víctor A.

    2017-01-01

    Aims Pancreatic β-cells synthesize and release serotonin (5 hydroxytryptamine, 5HT); however, the role of 5HT receptors on glucose stimulated insulin secretion (GSIS) and the mechanisms mediating this function is not fully understood. The aims of this study were to determine the expression profile of 5HT receptors in murine MIN6 β-cells and to examine the effects of pharmacological activation of 5HT receptor Htr2b on GSIS and mitochondrial function. Materials and Methods mRNA levels of 5HT receptors in MIN6 cells were quantified by RT qPCR. GSIS was assessed in MIN6 cells in response to global serotonergic activation with 5HT and pharmacological Htr2b activation or inhibition with BW723C86 or SB204741, respectively. In response to Htr2b activation also was evaluated the mRNA and protein levels of PGC1α and PPARy by RT-qPCR and western blotting and mitochondrial function by oxygen consumption rate (OCR) and ATP cellular content. Results We found that mRNA levels of most 5HT receptors were either very low or undetectable in MIN6 cells. By contrast, Htr2b mRNA was present at moderate levels in these cells. Preincubation (6 h) of MIN6 cells with 5HT or BW723C86 reduced GSIS and the effect of 5HT was prevented by SB204741. Preincubation with BW723C86 increased PGC1α and PPARy mRNA and protein levels and decreased mitochondrial respiration and ATP content in MIN6 cells. Conclusions Our results indicate that prolonged Htr2b activation in murine β-cells decreases glucose-stimulated insulin secretion and mitochondrial activity by mechanisms likely dependent on enhanced PGC1α/PPARy expression. PMID:28129327

  13. Molecular mechanisms of insulin resistance

    African Journals Online (AJOL)

    insulin action from receptor to the alteration of blood glucose. Hence, in order to ... and regulation of the insulin receptor in our efforts to unravel the cause of this ... defined mechanisms of signal transduction. Structure ..... found in muscle and fat is the most important and mediates ..... glycogen metabolism in skeletal muscle.

  14. The Role of Insulin, Insulin Growth Factor, and Insulin-Degrading Enzyme in Brain Aging and Alzheimer's Disease

    Directory of Open Access Journals (Sweden)

    Claude Messier

    2005-01-01

    Full Text Available Most brain insulin comes from the pancreas and is taken up by the brain by what appears to be a receptor-based carrier. Type 2 diabetes animal models associated with insulin resistance show reduced insulin brain uptake and content. Recent data point to changes in the insulin receptor cascade in obesity-related insulin resistance, suggesting that brain insulin receptors also become less sensitive to insulin, which could reduce synaptic plasticity. Insulin transport to the brain is reduced in aging and in some animal models of type 2 diabetes; brain insulin resistance may be present as well. Studies examining the effect of the hyperinsulinic clamp or intranasal insulin on cognitive function have found a small but consistent improvement in memory and changes in brain neuroelectric parameters in evoked brain potentials consistent with improved attention or memory processing. These effects appear to be due to raised brain insulin levels. Peripheral levels of Insulin Growth Factor-I (IGF-I are associated with glucose regulation and influence glucose disposal. There is some indication that reduced sensitivity to insulin or IGF-I in the brain, as observed in aging, obesity, and diabetes, decreases the clearance of Aβ amyloid. Such a decrease involves the insulin receptor cascade and can also increase amyloid toxicity. Insulin and IGF-I may modulate brain levels of insulin degrading enzyme, which would also lead to an accumulation of Aβ amyloid.

  15. Insulin-like growth factor receptor 1 mRNA expression as a prognostic marker in advanced non-small cell lung cancer

    DEFF Research Database (Denmark)

    Vilmar, Adam; Santoni-Rugiu, Eric; Cillas, Jesus Garcia-Fon

    2014-01-01

    BACKGROUND: The insulin-like growth factor 1 receptor (IGF1R) has yet to be established as a biomarker in non-small cell lung cancer (NSCLC) but could prove useful in customized chemotherapy. We explored its prognostic value using both quantitative real-time reverse transcriptase polymerase chain.......039 and 10.9 vs. 14.3 months, p=0.038, respectively). IGF1R protein expression showed a similar, although non-significant tendency. CONCLUSION: IGF1R mRNA expression may be a prognostic biomarker in advanced NSCLC and should be investigated in a larger population....

  16. Insulin-like growth factor 1 receptor expression in advanced non-small-cell lung cancer and its impact on overall survival

    Directory of Open Access Journals (Sweden)

    Humar Mojca

    2017-05-01

    Full Text Available The insulin-like growth factor 1 receptor (IGF1R expression has been addressed as a potential prognostic marker in non-small-cell lung cancer (NSCLC in various studies; however, the associations between IGF1R expression and prognosis of advanced NSCLC patients is still controversial. The aim of our observational, cohort study was to evaluate the expression of IGF1R in advanced NSCLC and its prognostic role. A subgroup analysis was performed to address the influence of pre-existing type 2 diabetes mellitus (T2DM status on IGF1R expression and overall survival (OS.