scholarly journals Leptin as a Potential Regulator of FGF21

2016 ◽  
Vol 38 (3) ◽  
pp. 1218-1225 ◽  
Author(s):  
Mohamed Asrih ◽  
Christelle Veyrat-Durebex ◽  
Anne-Laure Poher ◽  
Jacqueline Lyautey ◽  
Françoise Rohner-Jeanrenaud ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Hepg2 Cells ◽  
Wistar Rats ◽  
Metabolic Diseases ◽  
Fibroblast Growth Factor 21 ◽  
New Findings ◽  
Expression Site ◽  
Fgf21 Expression

Background/Aims: Fibroblast growth factor 21 (FGF21), a potent metabolic regulator, has been shown to improve insulin sensitivity in animal models of insulin resistance. Several studies have focused on identifying mediators of FGF21 effects. However, the identification of factors involved in FGF21 regulation is far from complete. As leptin is a potent metabolic modulator as well, we aimed at characterizing whether leptin may regulate FGF21. Methods: We investigated a potential regulation of FGF21 by leptin in vivo in Wistar rats and in vitro using human derived hepatocarcinoma HepG2 cells. This model was chosen as the liver is considered the main FGF21 expression site. Results: We found that leptin injections increased plasma FGF21 levels in adult Wistar rats. This was confirmed in vitro, as leptin increased FGF21 expression in HepG2 cells. We also showed that the leptin effect on FGF21 expression was mediated by STAT3 activation in HepG2 cells. Conclusion: New findings regarding a leptin-STAT3-FGF21 axis were provided in this study, although investigating the exact mechanisms linking leptin and FGF21 are still needed. These results are of great interest in the context of identifying potential new clinical approaches to treat metabolic diseases associated with insulin resistance, such as obesity and type 2 diabetes.

scholarly journals Exposure to the Widely Used Pyrethroid Pesticide Deltamethrin, Does Not Exacerbate High Fat Diet Induced Obesity or Insulin Resistance in C57BL/6J Mice

2021 ◽  
Vol 5 (Supplement_1) ◽  
pp. A45-A46
Author(s):  
Evangelia Evelyn Tsakiridis ◽  
Marisa Morrow ◽  
Andrea Llanos ◽  
Bo Wang ◽  
Alison Holloway ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Glycemic Control ◽  
Metabolic Diseases ◽  
Uncoupling Protein ◽  
Diet Induced Obesity ◽  
Brown Adipose ◽  
Pyrethroid Pesticide ◽  
First Time

Abstract Deltamethrin is a commonly used pesticide for the control of mosquito populations. Despite widespread use, the effects of deltamethrin on adiposity and glucose homeostasis have been equivocal with some studies showing increased, decreased and no effect on adiposity and glycemic control. However, no study to date has investigated the effect of deltamethrin in mice housed at thermoneutral temperatures, which is important for modelling metabolic diseases in rodents due to reduced thermal stress and constitutive activation of brown adipose tissue. In the current study we demonstrate for the first time that deltamethrin reduces uncoupling protein-1 expression in brown adipocytes cultured in vitro at concentrations as low as 1pm. Meanwhile, in-vivo deltamethrin does not appear to alter glycemic control or promote adiposity at exposures equivalent to 0.01, 0.1 or 1.0 mg/kg/day. Together, our study demonstrates environmentally relevant exposure to deltamethrin does not exacerbate diet induced obesity or insulin resistance.

scholarly journals Psoralea corylifolia L. Seed Extract Attenuates Methylglyoxal-Induced Insulin Resistance by Inhibition of Advanced Glycation End Product Formation

2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Cao-Sang Truong ◽  
Eunhui Seo ◽  
Hee-Sook Jun
Keyword(s):  
Oxidative Stress ◽  
Insulin Resistance ◽  
Hepg2 Cells ◽  
Product Formation ◽  
The Body ◽  
Psoralea Corylifolia ◽  
Advanced Glycation ◽  
Metabolic Conditions

Accumulation of advanced glycation end products (AGEs) in the body has been implicated in the pathogenesis of metabolic conditions, such as diabetes mellitus. Methylglyoxal (MGO), a major precursor of AGEs, has been reported to induce insulin resistance in both in vitro and in vivo studies. Psoralea corylifolia seeds (PCS) have been used as a traditional medicine for several diseases, but their potential application in treating insulin resistance has not yet been evaluated. This study is aimed at investigating whether PCS extract could attenuate insulin resistance induced by MGO. Male C57BL/6N mice (6 weeks old) were administered 1% MGO in their drinking water for 18 weeks, and the PCS extract (200 or 500 mg/kg) was orally administered daily from the first day of the MGO administration. We observed that both 200 and 500 mg/kg PCS extract treatment significantly improved glucose tolerance and insulin sensitivity and markedly restored p-Akt and p-IRS1/2 expression in the livers of the MGO-administered mice. Additionally, the PCS extract significantly increased the phosphorylation of Akt and IRS-1/2 and glucose uptake in MGO-treated HepG2 cells. Further studies showed that the PCS extract inhibited MGO-induced AGE formation in the HepG2 cells and in the sera of MGO-administered mice. PCS extract also increased the expression of glyoxalase 1 (GLO1) in the liver tissue of MGO-administered mice. The PCS extract significantly decreased the phosphorylation of ERK, p38, and NF-κB and suppressed the mRNA expression of proinflammatory molecules including TNF-α and IL-1β and iNOS in MGO-administered mice. Additionally, we demonstrated that the PCS extract attenuated oxidative stress, as evidenced by the reduced ROS production in the MGO-treated cells and the enhanced expression of antioxidant enzymes in the liver of MGO-administered mice. Thus, PCS extract ameliorated the MGO-induced insulin resistance in HepG2 cells and in mice by reducing oxidative stress via the inhibition of AGE formation. These findings suggest the potential of PCS extract as a candidate for the prevention and treatment of insulin resistance.

scholarly journals Orphan Nuclear Receptor Nur77 Mediates Fasting-Induced Hepatic Fibroblast Growth Factor 21 Expression

Endocrinology ◽  
2014 ◽  
Vol 155 (8) ◽  
pp. 2924-2931 ◽  
Author(s):  
Ae-Kyung Min ◽  
Kwi-Hyun Bae ◽  
Yun-A Jung ◽  
Yeon-Kyung Choi ◽  
Mi-Jin Kim ◽  
...  
Keyword(s):  
Growth Factor ◽  
Fibroblast Growth Factor ◽  
Nuclear Receptor ◽  
Fibroblast Growth Factor 21 ◽  
Orphan Nuclear Receptor ◽  
Fibroblast Growth ◽  
Cultured Hepatocytes ◽  
Fgf21 Expression

The fasting-induced hepatic hormone, fibroblast growth factor 21 (FGF21), is a potential candidate for the treatment of metabolic syndromes. Although peroxisome proliferator-activated receptor (PPAR)α is known to play a major role in the induction of hepatic FGF21 expression, other fasting-induced transcription factors that induce FGF21 expression have not yet been fully studied. In the present study, we investigated whether the fasting-induced activation of the orphan nuclear receptor Nur77 increases hepatic FGF21 expression. We found that fasting induced hepatic Nur77 and FGF21 expression. Glucagon and forskolin increased Nur77 and FGF21 expression in vivo and in vitro, respectively, and adenovirus-mediated overexpression of Nur77 (Ad-Nur77) increased FGF21 expression in vitro and in vivo. Moreover, knockdown of endogenous Nur77 expression by siRNA-Nur77 abolished the effect of forskolin on FGF21 expression. The results of ChIP assays, EMSA, and mutagenesis analysis showed that Nur77 bound to the putative NBRE of the FGF21 promoter in cultured hepatocytes and fasting induced Nur77 binding to the FGF21 promoter in vivo. Knockdown of PPARα partially inhibited forskolin-induced FGF21 expression, suggesting PPARα involvement in glucagon-stimulated FGF21 expression. In addition, double knockdown of PPARα and Nur77 further diminished FGF21 expression in cultured hepatocytes. In conclusion, this study shows that Nur77 mediates fasting-induced hepatic FGF21 expression, and suggests an alternative mechanism via which hepatic FGF21 transcription is mediated under fasting conditions.

scholarly journals Berberine improves hepatic insulin resistance by activating the SIRT1/Opa1 pathway: An in vitro and in vivo study

2021 ◽  
Author(s):  
Jia Xu ◽  
Yining Zhang ◽  
Zhiyi Yu ◽  
Yueqi Guan ◽  
Yuqian Lv ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Animal Models ◽  
Hepg2 Cells ◽  
Insulin Signalling ◽  
Morphological Changes ◽  
Mitochondrial Fusion ◽  
Hepatic Insulin Resistance ◽  
Inner Mitochondrial Membrane

Abstract Aim: This study explored whether abnormality in the inner mitochondrial membrane fusion protein optic atrophy 1 (Opa1) causes hepatic insulin resistance and whether berberine (BBR) can prevent hepatic insulin resistance through the SIRT1/Opa1 pathway. Method: High-fat diet (HFD)-fed mice and db/db mice were used as animal models to study hepatic insulin resistance in vivo . Insulin resistance, morphological changes, and mitochondrial injury of the liver were examined to explore the effects of BBR. SIRT1/Opa1 protein expressions were determined to confirm whether the signalling pathway was damaged in the model animals and involved in BBR treatment. A palmitate (PA)-induced hepatocyte insulin resistance model was established in HepG2 cells in vitro . Opa1 silencing and SIRT1 overexpression were induced to verify whether Opa1 abnormality causes hepatocyte insulin resistance and whether SIRT1 could improve this dysfunction. BBR treatment and SIRT1 silencing were employed to prove that BBR can prevent hepatic insulin resistance by activating the SIRT1/Opa1 pathway. Results: We found that Opa1 deficiency caused imbalance in mitochondrial fusion/fission and impaired insulin signalling in the HepG2 cells. SIRT1 and BBR overexpression ameliorated PA-induced insulin resistance, increased Opa1, and improved mitochondrial function. SIRT1 silencing could partly reverse the effects of BBR in the HepG2 cells. SIRT1 and Opa1 were downregulated in the animal models. BBR attenuated hepatic insulin resistance and enhanced SIRT1/Opa1 signalling in the the db/db mice. Conclusion: Opa1 silencing-mediated mitochondrial fusion/fission imbalance could lead to hepatocyte insulin resistance. BBR may improve hepatic insulin resistance by regulating the SIRT1/Opa1 pathway, and thus, it may be used to treat type 2 diabetes.

scholarly journals GRP75 Regulates Mitochondrial-Supercomplex Turnover to Modulate Insulin Sensitivity

2021 ◽  
Author(s):  
Qiongya Zhao ◽  
Ting Luo ◽  
Feng Gao ◽  
Yinxu Fu ◽  
Bin Li ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Insulin Sensitivity ◽  
Metabolic Diseases ◽  
Chain Complex ◽  
Complex Activity ◽  
Insulin Resistant ◽  
Mitochondrial Homeostasis ◽  
Dna Release

GRP75, defined as a major component of both mitochondrial quality control system and mitochondria-associated membrane, plays a key role in mitochondrial homeostasis. In this study, we assessed the roles of GRP75, other than as a component, in insulin action in both<i> in vitro</i> and <i>in vivo</i> models with insulin resistance. We found that GRP75 was downregulated in HFD-fed mice, and induction of <i>Grp75</i> in mice could prevent HFD induced obesity and insulin resistance. Mechanistically, GRP75 influenced insulin sensitivity by regulating mitochondrial function through its modulation of mitochondrial-supercomplex turnover rather than MAM communication: GRP75 was negatively associated with respiratory-chain complex activity and was essential for mitochondrial-supercomplex assembly and stabilization. Moreover, mitochondrial dysfunction in <i>Grp75</i>-knockdown cells might further increase mitochondrial fragmentation, thus trigger cytosolic mitochondrial DNA release and activate the cGAS/STING-dependent pro-inflammatory response.<b> </b>Therefore, GRP75 can serve as a potential therapeutic target of insulin resistant-related diabetes or other metabolic diseases.

scholarly journals GRP75 Regulates Mitochondrial-Supercomplex Turnover to Modulate Insulin Sensitivity

2021 ◽  
Author(s):  
Qiongya Zhao ◽  
Ting Luo ◽  
Feng Gao ◽  
Yinxu Fu ◽  
Bin Li ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Insulin Sensitivity ◽  
Metabolic Diseases ◽  
Chain Complex ◽  
Complex Activity ◽  
Insulin Resistant ◽  
Mitochondrial Homeostasis ◽  
Dna Release

GRP75, defined as a major component of both mitochondrial quality control system and mitochondria-associated membrane, plays a key role in mitochondrial homeostasis. In this study, we assessed the roles of GRP75, other than as a component, in insulin action in both<i> in vitro</i> and <i>in vivo</i> models with insulin resistance. We found that GRP75 was downregulated in HFD-fed mice, and induction of <i>Grp75</i> in mice could prevent HFD induced obesity and insulin resistance. Mechanistically, GRP75 influenced insulin sensitivity by regulating mitochondrial function through its modulation of mitochondrial-supercomplex turnover rather than MAM communication: GRP75 was negatively associated with respiratory-chain complex activity and was essential for mitochondrial-supercomplex assembly and stabilization. Moreover, mitochondrial dysfunction in <i>Grp75</i>-knockdown cells might further increase mitochondrial fragmentation, thus trigger cytosolic mitochondrial DNA release and activate the cGAS/STING-dependent pro-inflammatory response.<b> </b>Therefore, GRP75 can serve as a potential therapeutic target of insulin resistant-related diabetes or other metabolic diseases.

scholarly journals Low-dose naltrexone rescues inflammation and insulin resistance associated with hyperinsulinemia

2020 ◽  
Vol 295 (48) ◽  
pp. 16359-16369
Author(s):  
Abhinav Choubey ◽  
Khyati Girdhar ◽  
Aditya K. Kar ◽  
Shaivya Kushwaha ◽  
Manoj Kumar Yadav ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Inflammatory Mediators ◽  
Low Dose ◽  
Metabolic Diseases ◽  
Nuclear Translocation ◽  
Critical Role ◽  
Systemic Insulin Resistance ◽  
Low Dose Naltrexone

The incidence of diabetes, obesity, and metabolic diseases has reached an epidemic status worldwide. Insulin resistance is a common link in the development of these conditions, and hyperinsulinemia is a central hallmark of peripheral insulin resistance. However, how hyperinsulinemia leads to systemic insulin resistance is less clear. We now provide evidence that hyperinsulinemia promotes the release of soluble pro-inflammatory mediators from macrophages that lead to systemic insulin resistance. Our observations suggest that hyperinsulinemia induces sirtuin1 (SIRT1) repression and stimulates NF-κB p65 nuclear translocation and transactivation of NF-κB to promote the extracellular release of pro-inflammatory mediators. We further showed that low-dose naltrexone (LDN) abrogates hyperinsulinemia-mediated SIRT1 repression and prevents NF-κB p65 nuclear translocation. This, in turn, attenuates the hyperinsulinemia-induced release of pro-inflammatory cytokines and reinstates insulin sensitivity both in in vitro and in vivo diet-induced hyperinsulinemic mouse model. Notably, our data indicate that Sirt1 knockdown or inhibition blunts the anti-inflammatory properties of LDN in vitro. Using numerous complementary in silico and in vitro experimental approaches, we demonstrated that LDN can bind to SIRT1 and increase its deacetylase activity. Together, these data support a critical role of SIRT1 in inflammation and insulin resistance in hyperinsulinemia. LDN improves hyperinsulinemia-induced insulin resistance by reorienting macrophages toward anti-inflammation. Thus, LDN treatment may provide a novel therapeutic approach against hyperinsulinemia-associated insulin resistance.

scholarly journals Exercise-Induced Irisin, the Fat Browning Myokine, as a Potential Anticancer Agent

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
George-Emmanuel Maalouf ◽  
Diala El Khoury
Keyword(s):  
Insulin Resistance ◽  
Anticancer Agent ◽  
Metabolic Diseases ◽  
Fat Metabolism ◽  
Positive Effects ◽  
Different Types ◽  
Negative Effect ◽  
Exercise Induced

Irisin is a recently discovered myokine that plays an important role in fat metabolism through the browning of white adipose tissue. This myokine is usually secreted after exercise by improving energy balance and has shown great potential as a possible treatment for some metabolic diseases such as obesity, insulin resistance, and inflammation. Obesity has been linked to a higher incidence of some cancers. Furthermore, some studies have shown irisin to have direct positive effects on different types of cancers. Although it is hard to relay conclusions from in vitro to in vivo studies, the majority of the available data favor irisin as a potential substance for cancer regression through reducing proinflammatory markers linked to obesity. However, some controversies remain on the exact benefits of irisin on cancer with some studies showing no or even a negative effect of irisin on cancer. This review summarizes these 2 differing viewpoints and synthesizes them to form a clearer picture of exercise-induced irisin’s effects on cancer.

scholarly journals Aberrant Ca2+ homeostasis in adipocytes links inflammation to metabolic dysregulation in obesity

2020 ◽  
Author(s):  
Ekin Guney ◽  
Ana Paula Arruda ◽  
Gunes Parlakgul ◽  
Erika Cagampan ◽  
Nina Min ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Adipose Tissue ◽  
Metabolic Diseases ◽  
Dependent Manner ◽  
Metabolic Inflammation ◽  
Metabolic Dysregulation ◽  
Initiation And Propagation ◽  
Impaired Insulin Action

SummaryChronic metabolic inflammation is a key feature of obesity, insulin resistance and diabetes, although the initiation and propagation mechanisms of metaflammation are not fully established, particularly in the adipose tissue. Here we show that in adipocytes, altered regulation of the Ca2+ channel inositol triphosphate receptor (IP3Rs) is a key, adipocyte-intrinsic, event involved in the emergence and propagation of inflammatory signaling and the resulting insulin resistance. Inflammation, either induced by cytokine exposure in vitro or by obesity in vivo lead to increased expression and activity of IP3Rs in adipocytes in a JNK-dependent manner. This results in increased cytosolic Ca2+ and impaired insulin action. In mice, adipocyte-specific loss of IP3R1/2 protected against adipose tissue inflammation and insulin resistance despite significant diet-induced weight gain. Thus, this work reveals that IP3R over-activation and the resulting increase in cytosolic Ca2+ is a key link between obesity, inflammation and insulin resistance, and suggests that approaches to target adipocyte Ca2+ homeostasis may offer new therapeutic opportunities against metabolic diseases, especially since GWAS studies also implicate this locus in human obesity.

scholarly journals DPHC From Alpinia officinarum Ameliorates Oxidative Stress and Insulin Resistance via Activation of Nrf2/ARE Pathway in db/db Mice and High Glucose-Treated HepG2 Cells

2022 ◽  
Vol 12 ◽  
Author(s):  
Xuguang Zhang ◽  
Yuxin Zhang ◽  
Mingyan Zhou ◽  
Yiqiang Xie ◽  
Xiujuan Dong ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Insulin Resistance ◽  
High Glucose ◽  
Hepg2 Cells ◽  
Fasting Blood Glucose ◽  
Heme Oxygenase 1 ◽  
Related Factor ◽  
Alpinia Officinarum

(R)-5-hydroxy-1,7-diphenyl-3-heptanone (DPHC) from the natural plant Alpinia officinarum has been reported to have antioxidation and antidiabetic effects. In this study, the therapeutic effect and molecular mechanism of DPHC on type 2 diabetes mellitus (T2DM) were investigated based on the regulation of oxidative stress and insulin resistance (IR) in vivo and in vitro. In vivo, the fasting blood glucose (FBG) level of db/db mice was significantly reduced with improved glucose tolerance and insulin sensitivity after 8 weeks of treatment with DPHC. In vitro, DPHC ameliorated IR because of its increasing glucose consumption and glucose uptake of IR-HepG2 cells induced by high glucose. In addition, in vitro and in vivo experiments showed that DPHC could regulate the antioxidant enzyme levels including superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px), thereby reducing the occurrence of oxidative stress and improving insulin resistance. Western blotting and polymerase chain reaction results showed that DPHC could promote the expressions of nuclear factor erythroid 2-related factor 2 (Nrf2), the heme oxygenase-1 (HO-1), protein kinase B (AKT), and glucose transporter type 4 (GLUT4), and reduced the phosphorylation levels of c-Jun N-terminal kinase (JNK) and insulin receptor substrate-1 (IRS-1) on Ser307 both in vivo and in vitro. These findings verified that DPHC has the potential to relieve oxidative stress and IR to cure T2DM by activating Nrf2/ARE signaling pathway in db/db mice and IR-HepG2 cells.

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