Severe Hepatic Insulin Resistance Induces Vascular Dysfunction: Improvement by Liver-Specific Insulin Receptor Isoform A Gene Therapy in a Murine Diabetic Model

Background: Cardiovascular dysfunction is linked to insulin-resistant states. In this paper, we analyzed whether the severe hepatic insulin resistance of an inducible liver-specific insulin receptor knockout (iLIRKO) might generate vascular insulin resistance and dysfunction, and whether insulin receptor (IR) isoforms gene therapy might revert it. Methods: We studied in vivo insulin signaling in aorta artery and heart from iLIRKO. Vascular reactivity and the mRNA levels of genes involved in vascular dysfunction were analyzed in thoracic aorta rings by qRT-PCR. Finally, iLIRKO mice were treated with hepatic-specific gene therapy to analyze vascular dysfunction improvement. Results: Our results suggest that severe hepatic insulin resistance was expanded to cardiovascular tissues. This vascular insulin resistance observed in aorta artery from iLIRKO mice correlated with a reduction in both PI3K/AKT/eNOS and p42/44 MAPK pathways, and it might be implicated in their vascular alterations characterized by endothelial dysfunction, hypercontractility and eNOS/iNOS levels’ imbalance. Finally, regarding long-term hepatic expression of IR isoforms, IRA was more efficient than IRB in the improvement of vascular dysfunction observed in iLIRKO mice. Conclusion: Severe hepatic insulin resistance is sufficient to produce cardiovascular insulin resistance and dysfunction. Long-term hepatic expression of IRA restored the vascular damage observed in iLIRKO mice.

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Mechanisms of Hemorrhage-Induced Hepatic Insulin Resistance: Role of Tumor Necrosis Factor-α

Endocrinology ◽

10.1210/en.2004-0524 ◽

2004 ◽

Vol 145 (11) ◽

pp. 5168-5176 ◽

Cited By ~ 35

Author(s):

Yuchen Ma ◽

Balazs Toth ◽

Adam B. Keeton ◽

LaWanda T. Holland ◽

Irshad H. Chaudry ◽

...

Keyword(s):

Insulin Resistance ◽

Insulin Receptor ◽

Tyrosine Phosphorylation ◽

Burn Injury ◽

Serine Phosphorylation ◽

Hepatic Insulin Resistance ◽

Surgical Trauma ◽

Hepatic Expression ◽

Protein Levels ◽

Induce Insulin Resistance

Abstract Hemorrhage, sepsis, burn injury, surgical trauma and critical illness all induce insulin resistance. Recently we found that trauma and hemorrhage acutely induced hepatic insulin resistance in the rat. However, the mechanisms of this hemorrhage-induced acute hepatic insulin resistance are unknown. Here we report on the mechanisms of this hepatic insulin resistance. Protein levels and phosphorylation of the insulin receptor and insulin receptor substrate-1/2 (IRS-1/2) were measured, as was the association between IRS-1/2 and phosphatidylinositol 3-kinase (PI3K). Also examined were the hepatic expression of TNFα and TNFα-induced serine phosphorylation of IRS-1. Insulin receptor and IRS-1/2 protein levels and insulin-induced tyrosine phosphorylation of the insulin receptor were unaltered. In contrast, insulin-induced tyrosine phosphorylation of IRS-1/2 and association between IRS-1/2 and PI3K were dramatically reduced after hemorrhage. Hepatic levels of TNFα mRNA and protein were increased as was phosphorylation of IRS-1 serine 307 after hemorrhage. Our data provide the first evidence that compromised IRS-1/2 tyrosine phosphorylation and their association with PI3K contribute to hemorrhage-induced acute hepatic insulin resistance. Increased local TNFα may play a role in inducing this hepatic insulin resistance after trauma and hemorrhage.

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Central Insulin Signaling Is Attenuated by Long-Term Insulin Exposure via Insulin Receptor Substrate-1 Serine Phosphorylation, Proteasomal Degradation, and Lysosomal Insulin Receptor Degradation

Endocrinology ◽

10.1210/en.2009-0838 ◽

2010 ◽

Vol 151 (1) ◽

pp. 75-84 ◽

Cited By ~ 38

Author(s):

Christopher M. Mayer ◽

Denise D. Belsham

Keyword(s):

Insulin Resistance ◽

Insulin Receptor ◽

Insulin Signaling ◽

Time Course ◽

Proteasomal Degradation ◽

Serine Phosphorylation ◽

Neuronal Function ◽

Protein Levels ◽

Phosphorylated Akt

Abstract Central insulin signaling is critical for the prevention of insulin resistance. Hyperinsulinemia contributes to insulin resistance, but it is not yet clear whether neurons are subject to cellular insulin resistance. We used an immortalized, hypothalamic, clonal cell line, mHypoE-46, which exemplifies neuronal function and expresses the components of the insulin signaling pathway, to determine how hyperinsulinemia modifies neuronal function. Western blot analysis indicated that prolonged insulin treatment of mHypoE-46 cells attenuated insulin signaling through phospho-Akt. To understand the mechanisms involved, time-course analysis was performed. Insulin exposure for 4 and 8 h phosphorylated Akt and p70-S6 kinase (S6K1), whereas 8 and 24 h treatment decreased insulin receptor (IR) and IR substrate 1 (IRS-1) protein levels. Insulin phosphorylation of S6K1 correlated with IRS-1 ser1101 phosphorylation and the mTOR-S6K1 pathway inhibitor rapamycin prevented IRS-1 serine phosphorylation. The proteasomal inhibitor epoxomicin and the lysosomal pathway inhibitor 3-methyladenine prevented the degradation of IRS-1 and IR by insulin, respectively, and pretreatment with rapamycin, epoxomicin, or 3-methyladenine prevented attenuation of insulin signaling by long-term insulin exposure. Thus, a sustained elevation of insulin levels diminishes neuronal insulin signaling through mTOR-S6K1-mediated IRS-1 serine phosphorylation, proteasomal degradation of IRS-1 and lysosomal degradation of the IR.

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Programming of growth, insulin resistance and vascular dysfunction in offspring of late gestation diabetic rats

Clinical Science ◽

10.1042/cs20080550 ◽

2009 ◽

Vol 117 (3) ◽

pp. 129-138 ◽

Cited By ~ 32

Author(s):

Emily M. Segar ◽

Andrew W. Norris ◽

Jian-Rong Yao ◽

Shanming Hu ◽

Stacia L. Koppenhafer ◽

...

Keyword(s):

Insulin Resistance ◽

Vascular Function ◽

Vascular Dysfunction ◽

Diabetic Rats ◽

Late Gestation ◽

Group Differences ◽

Pregnant Rats ◽

Increased Risk ◽

Specific Insulin ◽

Diabetic Mothers

ODM (offspring of diabetic mothers) have an increased risk of developing metabolic and cardiovascular dysfunction; however, few studies have focused on the susceptibility to disease in offspring of mothers developing diabetes during pregnancy. We developed an animal model of late gestation diabetic pregnancy and characterized metabolic and vascular function in the offspring. Diabetes was induced by streptozotocin (50 mg/kg of body weight, intraperitoneally) in pregnant rats on gestational day 13 and was partially controlled by twice-daily injections of insulin. At 2 months of age, ODM had slightly better glucose tolerance than controls (P<0.05); however, by 6 months of age this trend had reversed. A euglycaemic–hyperinsulinamic clamp revealed insulin resistance in male ODM (P<0.05). In 6–8-month-old female ODM, aortas had significantly enhanced contractility in response to KCl, ET-1 (endothelin-1) and NA (noradrenaline). No differences in responses to ET-1 and NA were apparent with co-administration of L-NNA (NG-nitro-L-arginine). Relaxation in response to ACh (acetylcholine), but not SNP (sodium nitroprusside), was significantly impaired in female ODM. In contrast, males had no between-group differences in response to vasoconstrictors, whereas relaxation to SNP and ACh was greater in ODM compared with control animals. Thus the development of diabetes during pregnancy programmes gender-specific insulin resistance and vascular dysfunction in adult offspring.

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Expression and Significance of Lipin1 and AMPKα in Hepatic Insulin Resistance in Diet-Induced Insulin Resistance Rats

Experimental and Clinical Endocrinology & Diabetes ◽

10.1055/s-0031-1298013 ◽

2012 ◽

Vol 120 (02) ◽

pp. 84-88 ◽

Cited By ~ 1

Author(s):

S. Chen ◽

X. Zhuang ◽

Y. Liu ◽

A. Sun ◽

C. Chen

Keyword(s):

Insulin Resistance ◽

High Fat Diet ◽

Diet Group ◽

Hepatic Insulin Resistance ◽

Control Group ◽

Mrna Levels ◽

Ampk Signaling ◽

Protein Levels ◽

Obese Rats ◽

Male Wistar Rats

AbstractLipin1, a lately indentified adipokine, may link obesity with insulin resistance and diabetes. The present study aimed to investigate the changes and significance of lipin1 expression and lipin1-AMPK signaling in diet-induced hepatic insulin resistance.24 4-week-old Male Wistar rats were randomly divided into 2 groups: (1) control group (CO), (2) high-fat diet group (HF). Insulin sensitivity was evaluated by hyperinsulinemic-euglycemic clamp technique. The mRNA levels of α1 and α2 subunit of AMPKα as well as Lipin1 were measured using Real-time RT-PCR. The activities of AMPKα and Akt were evaluated by detection of p-AMPKα (Thr-172) and p-Akt (ser473) by Western blot.After treatment of 4 months, HF group showed significantly increased levels of body weight, fasting plasma glucose and insulin levels; Plasma and liver total cholesterol (TC), triglycerides (TG) levels were also markedly elevated; Lipin1 expression at both mRNA and protein levels were significantly deceased. Compared with CO group, the mRNA and protein levels of AMPKα1 and AMPKα2 were not changed, whereas the p-AMPK (Thr-172) and p-AKT (ser473) levels in liver were significantly decreased in HF group.These findings indicated that the decrease in lipin1 expression and AMPKα activation may contribute to hepatic insulin resistance in diet-induced obese rats.

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Tissue-specific insulin resistance in mice with mutations in the insulin receptor, IRS-1, and IRS-2

Journal of Clinical Investigation ◽

10.1172/jci7917 ◽

2000 ◽

Vol 105 (2) ◽

pp. 199-205 ◽

Cited By ~ 353

Author(s):

Yoshiaki Kido ◽

Deborah J. Burks ◽

Dominic Withers ◽

Jens C. Bruning ◽

C. Ronald Kahn ◽

...

Keyword(s):

Insulin Resistance ◽

Insulin Receptor ◽

Tissue Specific ◽

Specific Insulin

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Hyperinsulinemia Enhances Hepatic Expression of the Fatty Acid Transporter Cd36 and Provokes Hepatosteatosis and Hepatic Insulin Resistance

Journal of Biological Chemistry ◽

10.1074/jbc.m115.640292 ◽

2015 ◽

Vol 290 (31) ◽

pp. 19034-19043 ◽

Cited By ~ 45

Author(s):

Pär Steneberg ◽

Alexandros G. Sykaras ◽

Fredrik Backlund ◽

Jurate Straseviciene ◽

Ingegerd Söderström ◽

...

Keyword(s):

Insulin Resistance ◽

Fatty Acid ◽

Hepatic Insulin Resistance ◽

Hepatic Expression ◽

Fatty Acid Transporter ◽

Acid Transporter

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Interleukin-6 Depletion Selectively Improves Hepatic Insulin Action in Obesity

Endocrinology ◽

10.1210/en.2004-1468 ◽

2005 ◽

Vol 146 (8) ◽

pp. 3417-3427 ◽

Cited By ~ 172

Author(s):

Peter J. Klover ◽

Alicia H. Clementi ◽

Robert A. Mooney

Keyword(s):

Insulin Resistance ◽

Adipose Tissue ◽

Insulin Receptor ◽

Endogenous Glucose Production ◽

Hepatic Insulin Resistance ◽

Stat3 Phosphorylation ◽

Insulin Dependent ◽

Significant Change

Abstract Obesity and insulin resistance are considered chronic inflammatory states, in part because circulating IL-6 is elevated. Exogenous IL-6 can induce hepatic insulin resistance in vitro and in vivo. The importance of endogenous IL-6, however, to insulin resistance of obesity is unresolved. To test the hypothesis that IL-6 contributes to the inflammation and insulin resistance of obesity, IL-6 was depleted in Lepob mice by injection of IL-6-neutralizing antibody. In untreated Lepob mice, signal transducer and activator of transcription-3 (STAT3) activation was increased compared with that in lean controls, consistent with an inflammatory state. With IL-6 depletion, activation of STAT3 in liver and adipose tissue and expression of haptoglobin were reduced. Expression of the IL-6-dependent, hepatic acute phase protein fibrinogen was also decreased. Using the hyperinsulinemic-euglycemic clamp technique, insulin-dependent suppression of endogenous glucose production was 89% in IL-6-depleted Lepob mice, in contrast to only 32% in Lepob controls, indicating a marked increase in hepatic insulin sensitivity. A significant change in glucose uptake in skeletal muscle after IL-6 neutralization was not observed. In a direct comparison of hepatic insulin signaling in Lepob mice treated with anti-IL-6 vs. IgG-treated controls, insulin-dependent insulin receptor autophosphorylation and activation of Akt (pSer473) were increased by nearly 50% with IL-6 depletion. In adipose tissue, insulin receptor signaling showed no significant change despite major reductions in STAT3 phosphorylation and haptoglobin expression. In diet-induced obese mice, depletion of IL-6 improved insulin responsiveness in 2-h insulin tolerance tests. In conclusion, these results indicate that IL-6 plays an important and selective role in hepatic insulin resistance of obesity.

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Response of ApoA-IV in pigs to long-term increased dietary oil intake and to the degree of unsaturation of the fatty acids

British Journal Of Nutrition ◽

10.1079/bjn20041266 ◽

2004 ◽

Vol 92 (5) ◽

pp. 763-769 ◽

Cited By ~ 11

Author(s):

María A. Navarro ◽

Sergio Acín ◽

Ricardo Carnicer ◽

Mario A. Guzmán-García ◽

José M. Arbonés-Mainar ◽

...

Keyword(s):

Fatty Acids ◽

Sunflower Oil ◽

Control Diet ◽

Dietary Lipids ◽

Degree Of Saturation ◽

Plasma Lipoproteins ◽

Mrna Levels ◽

Hepatic Expression

ApoA-IV is a protein constituent of HDL particles; the gene coding for it is a member of the ApoA-I–ApoC-III–ApoA-IV cluster. To investigate the effects of the quantity and the degree of saturation of dietary lipid on the long-term response of this Apo, and on the hypothetical coordinated regulation of the cluster in vivo, pigs were fed isoenergetic, cholesterol-free, low-lipid or lipid-enriched diets (containing either extra olive oil (rich in MUFA) or sunflower oil (rich in n−6 PUFA)) for 42 d. In animals fed on the control diet, ApoA-IV was mainly associated with plasma lipoproteins. An increase in plasma ApoA-IV concentration, mainly in the lipoprotein-free fraction, was induced by the lipid-enriched diets, independent of the degree of saturation of the fatty acids involved. The latter diets also led to increases in hepatic ApoA-I, ApoA-IV and ApoC-III mRNA levels, more so with the sunflower oil-rich diet. The present results show that porcine plasma ApoA-IV levels and their association with lipoproteins are very sensitive to increases in dietary lipids, independent of the degree of fatty acid saturation. Furthermore, hepatic expression of RNA appears to be coordinated along with that of the other members of the gene cluster.

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Perturbation of glucose flux in the liver by decreasing F26P2 levels causes hepatic insulin resistance and hyperglycemia

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00126.2006 ◽

2006 ◽

Vol 291 (3) ◽

pp. E536-E543 ◽

Cited By ~ 21

Author(s):

Chaodong Wu ◽

Salmaan A. Khan ◽

Li-Jen Peng ◽

Honggui Li ◽

Steven G. Carmella ◽

...

Keyword(s):

Insulin Resistance ◽

Hepatic Glucose Production ◽

Glucose Production ◽

Hepatic Insulin Resistance ◽

Peroxisome Proliferator ◽

Mrna Levels ◽

Peroxisome Proliferator Activated Receptor ◽

Glucose Flux ◽

Hepatic Glucose

Hepatic insulin resistance is one of the characteristics of type 2 diabetes and contributes to the development of hyperglycemia. How changes in hepatic glucose flux lead to insulin resistance is not clearly defined. We determined the effects of decreasing the levels of hepatic fructose 2,6-bisphosphate (F26P2), a key regulator of glucose metabolism, on hepatic glucose flux in the normal 129J mice. Upon adenoviral overexpression of a kinase activity-deficient 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase, the enzyme that determines F26P2 level, hepatic F26P2 levels were decreased twofold compared with those of control virus-treated mice in basal state. In addition, under hyperinsulinemic conditions, hepatic F26P2 levels were much lower than those of the control. The decrease in F26P2 leads to the elevation of basal and insulin-suppressed hepatic glucose production. Also, the efficiency of insulin to suppress hepatic glucose production was decreased (63.3 vs. 95.5% suppression of the control). At the molecular level, a decrease in insulin-stimulated Akt phosphorylation was consistent with hepatic insulin resistance. In the low hepatic F26P2 states, increases in both gluconeogenesis and glycogenolysis in the liver are responsible for elevations of hepatic glucose production and thereby contribute to the development of hyperglycemia. Additionally, the increased hepatic gluconeogenesis was associated with the elevated mRNA levels of peroxisome proliferator-activated receptor-γ coactivator-1α and phospho enolpyruvate carboxykinase. This study provides the first in vivo demonstration showing that decreasing hepatic F26P2 levels leads to increased gluconeogenesis in the liver. Taken together, the present study demonstrates that perturbation of glucose flux in the liver plays a predominant role in the development of a diabetic phenotype, as characterized by hepatic insulin resistance.

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