5[beta]-reductase (AKR1D1) is a potent regulator of hepatic insulin sensitivity, carbohydrate and lipid metabolism in vitro and in vivo

Angiotensin II (ANGII) increases insulin sensitivity in diabetic and non-diabetic subjects, even at subpressor doses, and because there is 'crosstalk' between ANGII and insulin-signaling pathways the underlying mechanism may not be due solely to changes in regional blood flow. A series of experimental studies was undertaken to evaluate the effects of ANGII on glucose and lipid metabolism in vivo and in vitro. Groups of fructose-fed, insulin-resistant Sprague-Dawley (SD) rats were pre-treated with 0.3 mg/kg per day of the AT(1)-receptor antagonist L-158 809 (n=16), or vehicle (n=16), by oral gavage. This was prior to an oral glucose tolerance test (day 5) and measurement of the effects of ANGII infusion (20 ng/kg per min i.v. for 3 h) on whole-body insulin sensitivity using the insulin suppression test (day 7). The effect of ANGII infusion on total triglyceride secretion rate (TGSR) was evaluated in normal SD rats pretreated for 7 days with L-158 809 (n=12) or vehicle (n=12). AT(1)- and AT(2)- receptor mRNA expression and [(3)H]2-deoxyglucose uptake were assessed in cultured L6 myoblasts. Short-term treatment with L-158 809 had no effect on glucose tolerance or fasting triglyceride levels in fructose-fed rats. ANGII infusion had no effect on insulin sensitivity in fructose-fed rats pretreated with vehicle (steady-state plasma glucose (SSPG) values 8.1+/-1.6 vs 8. 4+/-0.4 mmol/l), but pretreatment with L-158 809 resulted in ANGII having a modest insulin antagonist effect in this insulin-resistant model (SSPG values 9.6+/-0.3 vs 7.1+/-0.6, P<0.03). ANGII infusion had no significant effect on TGSR (e.g. 24.6+/-1.4 vs 28.4+/-0.9 mg/100 g per h in vehicle-treated animals). RT-PCR analysis showed that L6 cells express both AT(1)- and AT(2)-receptor mRNA. Incubation with ANGII (10(-9) and 10(-8) M) had no significant effect on the dose-response curve for insulin-stimulated [(3)H]2-deoxyglucose uptake. For example, C(I200) values (dose of insulin required to increase glucose uptake by 200%) were 4.5 x 10(-9) M (control) vs 3.9 x 10(-9) M and 6.2 x 10(-9) M, whereas the positive control (glucagon-like peptide-1) increased insulin sensitivity. Thus, ANGII infusion may have a modest insulin antagonist effect on glucose disposal in insulin-resistant fructose-fed rats pretreated with an AT(1)-blocker, but ANGII has no effect on TGSR or in vitro glucose uptake in L6 myoblasts. These findings are relevant to recent clinical discussions about the metabolic effects of ANGII and renin-angiotensin system blockade.

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Nicotinic Acid Effects on Insulin Sensitivity and Hepatic Lipid Metabolism: An In Vivo to In Vitro Study

Hormone and Metabolic Research ◽

10.1055/s-0034-1372600 ◽

2014 ◽

Vol 46 (06) ◽

pp. 390-396 ◽

Cited By ~ 9

Author(s):

E. Blond ◽

J. Rieusset ◽

M. Alligier ◽

S. Lambert-Porcheron ◽

N. Bendridi ◽

...

Keyword(s):

Lipid Metabolism ◽

Insulin Sensitivity ◽

Nicotinic Acid ◽

In Vitro Study ◽

Vitro Study ◽

Hepatic Lipid Metabolism ◽

Hepatic Lipid

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Adipose Tissue Macrophage-Derived Exosomal miRNAs Can Modulate In Vivo and In Vitro Insulin Sensitivity

Yearbook of Paediatric Endocrinology ◽

10.1530/ey.15.11.14 ◽

2018 ◽

Author(s):

Ying W ◽

Riopel M ◽

Bandyopadhyay G ◽

Dong Y ◽

Birmingham A ◽

...

Keyword(s):

Adipose Tissue ◽

Insulin Sensitivity ◽

Tissue Macrophage ◽

Adipose Tissue Macrophage ◽

Exosomal Mirnas

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YAP1 overexpression contributes to the development of enzalutamide resistance by induction of cancer stemness and lipid metabolism in prostate cancer

Oncogene ◽

10.1038/s41388-021-01718-4 ◽

2021 ◽

Author(s):

Hsiu-Chi Lee ◽

Chien-Hui Ou ◽

Yun-Chen Huang ◽

Pei-Chi Hou ◽

Chad J. Creighton ◽

...

Keyword(s):

Prostate Cancer ◽

Lipid Metabolism ◽

Critical Issue ◽

Castration Resistant Prostate Cancer ◽

Cancer Stemness ◽

New Treatment ◽

Underlying Mechanisms ◽

Transcriptional Complex

AbstractMetastatic castration-resistant prostate cancer (mCRPC) is a malignant and lethal disease caused by relapse after androgen-deprivation (ADT) therapy. Since enzalutamide is innovated and approved by US FDA as a new treatment option for mCRPC patients, drug resistance for enzalutamide is a critical issue during clinical usage. Although several underlying mechanisms causing enzalutamide resistance were previously identified, most of them revealed that drug resistant cells are still highly addicted to androgen and AR functions. Due to the numerous physical functions of AR in men, innovated AR-independent therapy might alleviate enzalutamide resistance and prevent production of adverse side effects. Here, we have identified that yes-associated protein 1 (YAP1) is overexpressed in enzalutamide-resistant (EnzaR) cells. Furthermore, enzalutamide-induced YAP1 expression is mediated through the function of chicken ovalbumin upstream promoter transcription factor 2 (COUP-TFII) at the transcriptional and the post-transcriptional levels. Functional analyses reveal that YAP1 positively regulates numerous genes related to cancer stemness and lipid metabolism and interacts with COUP-TFII to form a transcriptional complex. More importantly, YAP1 inhibitor attenuates the growth and cancer stemness of EnzaR cells in vitro and in vivo. Finally, YAP1, COUP-TFII, and miR-21 are detected in the extracellular vesicles (EVs) isolated from EnzaR cells and sera of patients. In addition, treatment with EnzaR-EVs induces the abilities of cancer stemness, lipid metabolism and enzalutamide resistance in its parental cells. Taken together, these results suggest that YAP1 might be a crucial factor involved in the development of enzalutamide resistance and can be an alternative therapeutic target in prostate cancer.

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Regulation of Mitochondria-Associated Membranes (MAMs) by NO/sGC/PKG Participates in the Control of Hepatic Insulin Response

Cells ◽

10.3390/cells8111319 ◽

2019 ◽

Vol 8 (11) ◽

pp. 1319 ◽

Cited By ~ 5

Author(s):

Arthur Bassot ◽

Marie-Agnès Chauvin ◽

Nadia Bendridi ◽

Jingwei Ji-Cao ◽

Guillaume Vial ◽

...

Keyword(s):

Insulin Sensitivity ◽

Insulin Signaling ◽

Soluble Guanylate Cyclase ◽

Insulin Response ◽

Cyclophilin D ◽

Hepatic Insulin Sensitivity ◽

Physiological Conditions ◽

Huh7 Cells ◽

The Impact

Under physiological conditions, nitric oxide (NO) produced by the endothelial NO synthase (eNOS) upregulates hepatic insulin sensitivity. Recently, contact sites between the endoplasmic reticulum and mitochondria named mitochondria-associated membranes (MAMs) emerged as a crucial hub for insulin signaling in the liver. As mitochondria are targets of NO, we explored whether NO regulates hepatic insulin sensitivity by targeting MAMs. In Huh7 cells, primary rat hepatocytes and mouse livers, enhancing NO concentration increased MAMs, whereas inhibiting eNOS decreased them. In vitro, those effects were prevented by inhibiting protein kinase G (PKG) and mimicked by activating soluble guanylate cyclase (sGC) and PKG. In agreement with the regulation of MAMs, increasing NO concentration improved insulin signaling, both in vitro and in vivo, while eNOS inhibition disrupted this response. Finally, inhibition of insulin signaling by wortmannin did not affect the impact of NO on MAMs, while experimental MAM disruption, using either targeted silencing of cyclophilin D or the overexpression of the organelle spacer fetal and adult testis-expressed 1 (FATE-1), significantly blunted the effects of NO on both MAMs and insulin response. Therefore, under physiological conditions, NO participates to the regulation of MAM integrity through the sGC/PKG pathway and concomitantly improves hepatic insulin sensitivity. Altogether, our data suggest that the induction of MAMs participate in the impact of NO on hepatocyte insulin response.

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Effects of prolonged Acipimox treatment on glucose and lipid metabolism and on in vivo insulin sensitivity in patients with non-insulin dependent diabetes mellitus

Acta Endocrinologica ◽

10.1530/acta.0.1270344 ◽

1992 ◽

Vol 127 (4) ◽

pp. 344-350 ◽

Cited By ~ 32

Author(s):

Allan A Vaag ◽

Henning Beck-Nielsen

Keyword(s):

Lipid Metabolism ◽

Insulin Sensitivity ◽

Treatment Period ◽

Blood Glucose Control ◽

Glucose Disposal ◽

Prolonged Treatment ◽

Double Blind Study ◽

Glucose And Lipid Metabolism ◽

Fasting Plasma

The effect of prolonged treatment with Acipimox on in vivo peripheral insulin sensitivity, and on glucose and lipid metabolism, was investigated in patients with NIDDM in a double-blind study. Twelve NIDDM patients were randomized to treatment with either placebo or Acipimox in pharmacological doses (250 mg×3) for three months. Fasting plasma glucose, insulin, C-peptide and HbA1c concentrations were unaffected after three months of acipimox treatment. However, fasting plasma non-esterifled fatty acid (NEFA) concentrations were twofold elevated after Acipimox treatment (1.34±0.09 vs 0.66±0.09 mmol/l; p<0.05). Despite this, repeated acute Acipimox administration after the three months' treatment period enhanced total insulin-stimulated glucose disposal to the same extent as acute Acipimox administration before the treatment period (367±59 vs 392±66 mg·m−2·min−1, NS; both p<0.05 vs placebo glucose disposal) (267±44 mg·m−2·min−1). In conclusion, insulin resistance or tachyphylaxis towards the effects of Acipimox on insulin stimulated glucose disposal was not induced during prolonged Acipimox treatment. The lack of improvement of blood glucose control in the patients with NIDDM may be due to the demonstrated rebound effect of lipolysis.

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Hepatic Lipid Accumulation Induced by a High-fat Diet Is Regulated by Nrf2 Through Multiple Pathways

10.21203/rs.3.rs-775710/v1 ◽

2021 ◽

Author(s):

sheng Qiu ◽

Zerong Liang ◽

Qinan Wu ◽

Miao Wang ◽

Mengliu Yang ◽

...

Keyword(s):

Lipid Metabolism ◽

Lipid Accumulation ◽

High Fat Diet ◽

Underlying Mechanism ◽

Luciferase Assay ◽

High Fat ◽

Hepatic Lipid ◽

Hepatic Lipid Accumulation

Abstract BackgroundNuclear factor erythroid 2-related factor 2 (Nrf2) is reportedly involved in hepatic lipid metabolism, but the results are contradictory and the underlying mechanism thus remains unclear. Herein we focused on elucidating the effects of Nrf2 on hepatic adipogenesis and on determining the possible underlying mechanism. We established a metabolic associated fatty liver disease (MAFLD) model in high fat diet (HFD) fed Nrf2 knockout (Nrf2 KO) mice; further, a cell model of lipid accumulation was established using mouse primary hepatocytes (MPHs) treated with free fatty acids (FAs). Using these models, we investigated the relationship between Nrf2 and autophagy and its role in the development of MAFLD.ResultsWe observed that Nrf2 expression levels were up-regulated in patients with MAFLD and diet-induced obese mice. Nrf2 deficiency led to hepatic lipid accumulation in vivo and in vitro, in addition to, promoting lipogenesis mainly by increasing SREBP-1 activity. Moreover, Nrf2 deficiency attenuated autophagic flux and inhibited the fusion of autophagosomes and lysosomes in vivo and in vitro. Weakened autophagy caused reduced lipolysis in the liver. Importantly, Chromatin immunoprecipitation-qPCR (ChIP-qPCR) and dual-luciferase assay results proved that Nrf2 bound to LAMP1 promoter and regulated its transcriptional activity. We accordingly report that Nrf2-LAMP1 interaction has an indispensable role in Nrf2-regulated hepatosteatosis. ConclusionsThese data collectively confirm that Nrf2 deficiency promotes hepatosteatosis by enhancing SREBP-1 activity and attenuating autophagy. To conclude, our data reveal a novel multi-pathway effect of Nrf2 on lipid metabolism in the liver, and we believe that multi-target intervention of Nrf2 signaling is a promising new strategy for the prevention and treatment of MAFLD.

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Mechanisms of vanadium action: insulin-mimetic or insulin-enhancing agent?

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y00-053 ◽

2000 ◽

Vol 78 (10) ◽

pp. 829-847 ◽

Cited By ~ 55

Author(s):

Margaret C Cam ◽

Roger W Brownsey ◽

John H McNeill

Keyword(s):

Lipid Metabolism ◽

Metabolic Effects ◽

Isolated Cells ◽

Insulin Mimetic ◽

Endogenous Insulin ◽

Carbohydrate And Lipid Metabolism ◽

Low Concentrations ◽

Tissue Sensitivity ◽

High Concentrations

The demonstration that the trace element vanadium has insulin-like properties in isolated cells and tissues and in vivo has generated considerable enthusiasm for its potential therapeutic value in human diabetes. However, the mechanisms by which vanadium induces its metabolic effects in vivo remain poorly understood, and whether vanadium directly mimics or rather enhances insulin effects is considered in this review. It is clear that vanadium treatment results in the correction of several diabetes-related abnormalities in carbohydrate and lipid metabolism, and in gene expression. However, many of these in vivo insulin-like effects can be ascribed to the reversal of defects that are secondary to hyperglycemia. The observations that the glucose-lowering effect of vanadium depends on the presence of endogenous insulin whereas metabolic homeostasis in control animals appears not to be affected, suggest that vanadium does not act completely independently in vivo, but augments tissue sensitivity to low levels of plasma insulin. Another crucial consideration is one of dose-dependency in that insulin-like effects of vanadium in isolated cells are often demonstrated at high concentrations that are not normally achieved by chronic treatment in vivo and may induce toxic side effects. In addition, vanadium appears to be selective for specific actions of insulin in some tissues while failing to influence others. As the intracellular active forms of vanadium are not precisely defined, the site(s) of action of vanadium in metabolic and signal transduction pathways is still unknown. In this review, we therefore examine the evidence for and against the concept that vanadium is truly an insulin-mimetic agent at low concentrations in vivo. In considering the effects of vanadium on carbohydrate and lipid metabolism, we conclude that vanadium acts not globally, but selectively and by enhancing, rather than by mimicking the effects of insulin in vivo.Key words: vanadium, insulin-mimetic, insulin-like, insulin-enhancing.

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Abstract 76: MicroRNA-144 Regulates Hepatic ABCA1 and Plasma HDL Following Activation of the Nuclear Receptor FXR

Arteriosclerosis Thrombosis and Vascular Biology ◽

10.1161/atvb.33.suppl_1.a76 ◽

2013 ◽

Vol 33 (suppl_1) ◽

Author(s):

Thomas Vallim ◽

Elizabeth Tarling ◽

Tammy Kim ◽

Mete Civelek ◽

Angel Baldan ◽

...

Keyword(s):

Lipid Metabolism ◽

Nuclear Receptor ◽

Molecular Mechanisms ◽

Lipoprotein Metabolism ◽

Density Lipoprotein ◽

Hdl Cholesterol ◽

Farnesoid X Receptor ◽

Abca1 Protein

Rationale The bile acid receptor Farnesoid-X-Receptor (FXR) regulates many aspects of lipid metabolism by various complex and not fully understood molecular mechanisms. We set out to investigate the molecular mechanisms for FXR-dependent regulation of lipid and lipoprotein metabolism. Objective To identify FXR-regulated microRNAs that were subsequently involved in regulating lipid metabolism. Methods and Results ATP binding cassette transporter A1 (ABCA1) is a major determinant of plasma High Density Lipoprotein (HDL)-cholesterol levels. Here we show that activation of the nuclear receptor FXR in vivo increases hepatic levels of miR-144, which in turn lower hepatic ABCA1 and plasma HDL levels. We identified two complementary sequences to miR-144 in the 3’ untranslated region (UTR) of ABCA1 mRNA that are necessary for miR-144-dependent regulation. Overexpression of miR-144 in vitro decreased both cellular ABCA1 protein and cholesterol efflux to lipid-poor apolipoprotein A-I (ApoA-I) protein, whilst overexpression in vivo reduced hepatic ABCA1 protein and plasma HDL- cholesterol. Conversely, silencing miR-144 in mice increased hepatic ABCA1 protein and HDL- cholesterol. In addition, we utilized tissue-specific FXR deficient mice to show that induction of miR-144 and FXR-dependent hypolipidemia requires hepatic, but not intestinal FXR. Finally, we identified functional FXR response elements (FXREs) upstream of the miR-144 locus, consistent with direct FXR regulation. Conclusion In conclusion, we have identified a pathway involving FXR, miR-144 and ABCA1 that together regulate plasma HDL cholesterol. This pathway may be therapeutically targeted in the future in order to increase HDL levels.

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