scholarly journals Crosstalk between the AMP-activated kinase and insulin signaling pathways rescues murine blastocyst cells from insulin resistance

Reproduction ◽  
2008 ◽  
Vol 136 (3) ◽  
pp. 335-344 ◽  
Author(s):  
Erica Louden ◽  
Maggie M Chi ◽  
Kelle H Moley
Keyword(s):  
Insulin Resistance ◽  
Signaling Pathways ◽  
Insulin Signaling ◽  
Kinase Activity ◽  
Pi3 Kinase ◽  
Ampk Activation ◽  
Embryonic Cells ◽  
Insulin Resistant

Maternal insulin resistance results in poor pregnancy outcomes. In vivo and in vitro exposure of the murine blastocyst to high insulin or IGF1 results in the down-regulation of the IGF1 receptor (IGF1R). This in turn leads to decreased glucose uptake, increased apoptosis, as well as pregnancy resorption and growth restriction. Recent studies have shown that blastocyst activation of AMP-activated protein kinase (AMPK) reverses these detrimental effects; however, the mechanism was not clear. The objective of this study was to determine how AMPK activation rescues the insulin-resistant blastocyst. Using trophoblast stem (TS) cells derived from the blastocyst, insulin resistance was recreated by transfecting with siRNA to Igf1r and down-regulating expression of the protein. These cells were then exposed to AMPK activators 5-aminoimidazole-4-carboxamide riboside and phenformin, and evaluated for apoptosis, insulin-stimulated 2-deoxyglucose uptake, PI3-kinase activity, and levels of phospho-AKT, phospho-mTor, and phospho-70S6K. Surprisingly, disrupted insulin signaling led to decreased AMPK activity in TS cells. Activators reversed these effects by increasing the AMP/ATP ratio. Moreover, this treatment increased insulin-stimulated 2-deoxyglucose transport and cell survival, and led to an increase in PI3-kinase activity, as well as increased P-mTOR and p70S6K levels. This study is the first to demonstrate significant crosstalk between the AMPK and insulin signaling pathways in embryonic cells, specifically the enhanced response of PI3K/AKT/mTOR to AMPK activation. Decreased insulin signaling also resulted in decreased AMPK activation. These findings provide mechanistic targets in the AMPK signaling pathway that may be essential for improved pregnancy success in insulin-resistant states.

PI3-kinase activity modulates apo B available for hepatic VLDL production in apobec-1−/− mice

2006 ◽  
Vol 291 (3) ◽  
pp. G382-G388 ◽  
Author(s):  
Doru V. Chirieac ◽  
Nicholas O. Davidson ◽  
Charles E. Sparks ◽  
Janet D. Sparks
Keyword(s):  
Insulin Resistance ◽  
Kinase Activity ◽  
Pi3 Kinase ◽  
Apo B ◽  
Glucose Injection ◽  
Primary Mouse ◽  
Mouse Hepatocytes ◽  
Vldl Triglyceride

Insulin regulates hepatic VLDL production by activation of phosphatidylinositide 3-kinase (PI3-kinase) which decreases apo B available for lipid assembly. The current study evaluated the dependence of the VLDL apolipoprotein B (apo B) pathway on PI3-kinase activity in vivo. VLDL production was examined in B100 only, apo B mRNA editing catalytic subunit 1 ( apobec-1 −/−) mice, using the Triton WR 1339 method. Glucose injection suppressed VLDL triglyceride production by 28% in male and by 32% in female mice compared with saline-injected controls. When wortmannin was injected to inhibit PI3-kinase, VLDL triglyceride production was increased by 52% in males and by 89% in females, and VLDL B100 levels paralleled triglyceride changes. Pulse-chase experiments in primary mouse hepatocytes showed that wortmannin increased net freshly synthesized B100 availability by >35%. To test whether physiological insulin resistance produced equivalent effects to wortmannin, we studied male apobec-1 −/− mice who became hyperlipidemic on being fed a fructose-enriched diet. Fructose-fed apobec-1 −/− mice had significantly higher VLDL triglyceride and B100 production rates compared with chow-fed mice, and rates were refractile to glucose or wortmannin. Hepatic VLDL triglyceride and B100 production in wortmannin-injected chow-fed mice equaled that observed in fructose-fed mice. Together, results suggest in vivo and in vitro that wortmannin-sensitive PI3-kinases maintain a basal level of VLDL suppression that is sensitive to changes in activation and that can increase VLDL production when PI3-kinase is inhibited to levels similar to those induced by insulin resistance.

Resveratrol improves insulin signaling in a tissue-specific manner under insulin-resistant conditions only: in vitro and in vivo experiments in rodents

Metabolism ◽  
2012 ◽  
Vol 61 (3) ◽  
pp. 424-433 ◽  
Author(s):  
Wonyoung Kang ◽  
Hyun Ju Hong ◽  
Jian Guan ◽  
Dong Geon Kim ◽  
Eun-Jin Yang ◽  
...  
Keyword(s):  
Insulin Signaling ◽  
Tissue Specific ◽  
Insulin Resistant ◽  
In Vivo Experiments ◽  
Specific Manner

scholarly journals Src acts as the target of matrine to inhibit the proliferation of cancer cells by regulating phosphorylation signaling pathways

2020 ◽  
Author(s):  
Xi Zhang ◽  
Hui Xu ◽  
Xiaoyang Bi ◽  
Guoqing Hou ◽  
Andong Liu ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Cancer Cells ◽  
Signaling Pathways ◽  
Kinase Activity ◽  
Src Kinase ◽  
Kinase Domain ◽  
Akt Phosphorylation ◽  
In Vivo Experiments

Background and Purpose: Identification of accurate targets is essential for a successful development of targeted therapy in cancer. Studies have shown that matrine has antitumor activity against many types of cancers. However, the direct target in cancer cells of its anticancer effect has not been identified. The purpose of this study was to find the molecular target of matrine to inhibit the proliferation of cancer cells and explore its mechanism of action. Experimental Approach: The effect of matrine on the proliferation of cancer cells were examined by MTT assay. Pull-down assay and liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) were performed to explore the target of matrine. A series of in vitro and in vivo experiments were conducted to reveal the mechanisms by which matrine targeted Src to regulate the downstream signaling pathways of Src in cancer cells. Key Results: Herein we showed that matrine inhibited the proliferation of cancer in vitro and in vivo. Pull-down assay with matrine-amino coupling resins (MA beads) and LC-MS/MS identified Src as the target of matrine. Src kinase domain is required for its interaction with matrine and Ala392 in the kinase domain participated in matrine-Src interaction. Intriguingly, matrine was proven to inhibit Src kinase activity in a non-ATP-competitive manner by blocking the autophosphorylation of Tyr419. Matrine down-regulated the phosphorylation levels of MAPK/ERK, JAK2/STAT3 and PI3K/Akt signaling pathways. Conclusions and Implications: Collectively, matrine targeted Src, inhibited kinase activity and down-regulated its downstream MAPK/ERK, JAK2/STAT3 and PI3K/Akt phosphorylation signaling pathways to inhibit the proliferation of cancer cells.

scholarly journals Loss of PI3 kinase association improves the sensitivity of secondary mutation of KIT to Imatinib

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Guangrong Zhu ◽  
Jun Shi ◽  
Shaoting Zhang ◽  
Yue Guo ◽  
Ling Huang ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Targeted Therapy ◽  
Kinase Activity ◽  
Cell Transformation ◽  
Pi3 Kinase ◽  
Driver Mutations ◽  
Secondary Mutation ◽  
Lipid Kinase

Abstract Background KIT mutations are the predominant driver mutations in gastrointestinal stromal tumors (GISTs), and targeted therapy against KIT has improved treatment outcome dramatically. However, gaining secondary mutation of KIT confers drug resistance of GISTs leading to treatment failure. Results In this study, we found that secondary mutation of KIT dramatically increases the ligand-independent activation of the receptor and their resistance to the often used KIT inhibitor Imatinib in the treatment of GISTs. PI3 kinase plays essential roles in the cell transformation mediated by the primary mutation of KIT. We found that loss of PI3 kinase association, but not the inhibition of the lipid kinase activity of PI3 kinase, inhibits the ligand-independent activation of secondary mutations of KIT, and increases their sensitivity to Imatinib, and loss of PI3 kinase association inhibits secondary mutations of KIT mediated cell survival and proliferation in vitro. The in vivo assay further showed that the growth of tumors carrying secondary mutations of KIT is more sensitive to Imatinib when PI3 kinase association is blocked while inhibition of the lipid kinase activity of PI3 kinase cannot inhibit tumor growth, indicating that PI3 kinase is important for the drug resistance of secondary mutation of KIT independent of the lipid kinase activity of PI3 kinase. Conclusions Our results suggested that PI3 kinase is necessary for the ligand-independent activation of secondary mutations of KIT, and loss of PI3 kinase association improves the sensitivity of secondary mutations to the targeted therapy independent of the lipid kinase activity of PI3 kinase.

Abstract 630: Novel Chimeric Anti-proteoglycan Antibody Inhibits Arterial Retention of Proatherogenic Lipoproteins in a Rat Model of Insulin Resistance

2016 ◽  
Vol 36 (suppl_1) ◽  
Author(s):  
Yosdel Soto ◽  
Rabban Mangat ◽  
Ana M Vázquez ◽  
Spencer D Proctor
Keyword(s):  
Insulin Resistance ◽  
Monoclonal Antibody ◽  
Ex Vivo ◽  
Dependent Manner ◽  
Insulin Resistant ◽  
Remnant Lipoproteins ◽  
Preferential Binding ◽  
Carotid Vessels

Background: The response-to-retention hypothesis for atherosclerosis describes subendothelial retention of apolipoprotein B-containing lipoproteins mediated by proteoglycans (PG). Further we know that diabetes is also associated with both increased circulating chylomicron remnants and remodeling of proatherogenic PGs. We have recently reported antiatherogenic properties of a novel chimeric monoclonal antibody (chP3R99) that recognizes PG sulfated molecules. Hypothesis: chP3R99 monoclonal antibody may interfere with the interaction of atherogenic lipoproteins with arterial sulfated PGs during insulin resistance. Methods and Results: chP3R99 antibody recognized sulfated glycosaminoglycans by ELISA showing a preferential binding to chondroitin sulfate. Also, chP3R99 blocked the interaction of proatherogenic lipoproteins with this glycosaminoglycan in vitro in a dose-dependent manner and its intravenous injection into healthy Sprague-Dawly rats (n=6, 1 mg/animal) inhibited LDL (4 mg/kg; intraperitoneally) aortic retention. To further assess this property in an insulin resistant condition, carotid arteries from control and JCR:LA-cp rats (n=4) were perfused ex vivo with apoB48 containing remnant lipoproteins (prepared via rabbit hepatectomy procedure), with or without Cy3-LDL (150 μg/mL) for 20 minutes. Confocal microscopy analysis revealed an increased arterial retention of both remnants (3.6 fold) and LDL (2.8 fold) in carotid vessels from insulin resistant rats relative to control. However, chP3R99 pre-perfusion resulted in decreased retention of remnants (-30%) and LDL (-60%) associated arterial cholesterol. Data suggests that the chP399 antibody may interfere with the arterial attachment of both remnants and LDL in vivo, but with differential efficacy. Conclusions: Relative to LDL, remnant lipoproteins had preferential accumulation in arterial vessels from insulin resistant rats ex vivo , which could then be inhibited by acute pre-exposure to the chP3R99 antibody. These in vivo data support the concept for an innovative approach to target the retention of proatherogenic lipoproteins in a pre-clinical setting.

scholarly journals Insulin Regulates Glucagon-Like Peptide-1 Secretion from the Enteroendocrine L Cell

Endocrinology ◽  
2009 ◽  
Vol 150 (2) ◽  
pp. 580-591 ◽  
Author(s):  
Gareth E. Lim ◽  
Guan J. Huang ◽  
Nina Flora ◽  
Derek LeRoith ◽  
Christopher J. Rhodes ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Oral Glucose ◽  
Phosphatidylinositol 3 Kinase ◽  
Insulin Resistant ◽  
L Cell ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1 ◽  
Phosphatidylinositol 3

Insulin resistance and type 2 diabetes mellitus are associated with impaired postprandial secretion of glucagon-like peptide-1 (GLP-1), a potent insulinotropic hormone. The direct effects of insulin and insulin resistance on the L cell are unknown. We therefore hypothesized that the L cell is responsive to insulin and that insulin resistance impairs GLP-1 secretion. The effects of insulin and insulin resistance were examined in well-characterized L cell models: murine GLUTag, human NCI-H716, and fetal rat intestinal cells. MKR mice, a model of chronic hyperinsulinemia, were used to assess the function of the L cell in vivo. In all cells, insulin activated the phosphatidylinositol 3 kinase-Akt and MAPK kinase (MEK)-ERK1/2 pathways and stimulated GLP-1 secretion by up to 275 ± 58%. Insulin resistance was induced by 24 h pretreatment with 10−7m insulin, causing a marked reduction in activation of Akt and ERK1/2. Furthermore, both insulin-induced GLP-1 release and secretion in response to glucose-dependent insulinotropic peptide and phorbol-12-myristate-13-acetate were significantly attenuated. Whereas inhibition of phosphatidylinositol 3 kinase with LY294002 potentiated insulin-induced GLP-1 release, secretion was abrogated by inhibiting the MEK-ERK1/2 pathway with PD98059 or by overexpression of a kinase-dead MEK1-ERK2 fusion protein. Compared with controls, MKR mice were insulin resistant and displayed significantly higher fasting plasma insulin levels. Furthermore, they had significantly higher basal GLP-1 levels but displayed impaired GLP-1 secretion after an oral glucose challenge. These findings indicate that the intestinal L cell is responsive to insulin and that insulin resistance in vitro and in vivo is associated with impaired GLP-1 secretion. Insulin is a novel secretagogue of the incretin hormone, glucagon-like peptide-1 (GLP-1), and L cell insulin resistance impairs heterologous secretagogue-induced GLP-1 secretion in vitro and in vivo.

In vivo insulin signaling through PI3-kinase is impaired in skeletal muscle of adult rat offspring exposed to ethanol in utero

2005 ◽  
Vol 99 (2) ◽  
pp. 528-534 ◽  
Author(s):  
Li Chen ◽  
Xing-Hai Yao ◽  
B. L. G. Nyomba
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Insulin Receptor ◽  
Insulin Signaling ◽  
In Utero ◽  
Pi3 Kinase ◽  
Adult Rat ◽  
Rat Offspring ◽  
Significant Difference

It is now known that prenatal ethanol (EtOH) exposure is associated with impaired glucose tolerance and insulin resistance in rat offspring, but the underlying mechanism(s) is not known. To test the hypothesis that in vivo insulin signaling through phosphatidylinositol 3 (PI3)-kinase is reduced in skeletal muscle of adult rat offspring exposed to EtOH in utero, we gave insulin intravenously to these rats and probed steps in the PI3-kinase insulin signaling pathway. After insulin treatment, EtOH-exposed rats had decreased tyrosine phosphorylation of the insulin receptor β-subunit and of insulin receptor substrate-1 (IRS-1), as well as reduced IRS-1-associated PI3-kinase in the gastrocnemius muscle compared with control rats. There was no significant difference in basal or insulin-stimulated Akt activity between EtOH-exposed rats and controls. Insulin-stimulated PKC isoform ζ phosphorylation and membrane association were reduced in EtOH-exposed rats compared with controls. Muscle insulin binding and peptide contents of insulin receptor, IRS-1, p85 subunit of PI3-kinase, Akt/PKB, and atypical PKC isoform ζ were not different between EtOH-exposed rats and controls. Thus insulin resistance in rat offspring exposed to EtOH in utero may be explained, at least in part, by impaired insulin signaling through the PI3-kinase pathway in skeletal muscle.

scholarly journals Growth Hormone Signaling in Vivo in Human Muscle and Adipose Tissue: Impact of Insulin, Substrate Background, and Growth Hormone Receptor Blockade

2008 ◽  
Vol 93 (7) ◽  
pp. 2842-2850 ◽  
Author(s):  
Charlotte Nielsen ◽  
Lars C. Gormsen ◽  
Niels Jessen ◽  
Steen Bønløkke Pedersen ◽  
Niels Møller ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Growth Hormone ◽  
Signaling Pathways ◽  
Cross Talk ◽  
Insulin Signaling ◽  
Human Muscle ◽  
Receptor Blockade ◽  
Gh Receptor ◽  
Igf I

Abstract Context: GH induces insulin resistance in muscle and fat, and in vitro data indicate that this may involve cross-talk between the signaling pathways of the two hormones. Objective: Our objective was to investigate GH and insulin signaling in vivo in human muscle and fat tissue in response to GH, GH receptor blockade, and insulin stimulation. Design: We conducted two randomized crossover studies. Participants: Sixteen healthy males participated. Intervention: GH was administered as a bolus (n = 8) and constant infusion (n = 8). The bolus study included three arms: 1) control (saline), 2) GH (0.5 mg iv), and 3) GH blockade (pegvisomant 30 mg sc), each combined with a hyperinsulinemic glucose clamp. The infusion study included two arms: 1) GH infusion (45 ng/·kg·min, 5.5 h) and 2) saline infusion (5.5 h) combined with a hyperinsulinemic glucose clamp during the final 2.5 h. Main Outcome Measures: Muscle and fat biopsies were subjected to Western blotting for expression of Stat5/p-Stat5, Akt/p-Akt, and ERK1/2/p-ERK1/2 and to real-time RT-PCR for expression of SOCS1–3 and IGF-I mRNA. Results: GH significantly reduced insulin sensitivity. The GH bolus as well as GH infusion induced phosphorylation of Stat5 in muscle and fat, and SOCS3 and IGF-I mRNA expression increased after GH infusion. Hyperinsulinemia induced Akt phosphorylation in both tissues, irrespective of GH status. In muscle, ERK1/2 phosphorylation was increased by insulin, but insulin per se did not induce phosphorylation of Stat5. Conclusions: GH exposure associated with insulin resistance acutely translates into GH receptor signaling in human muscle and fat without evidence of cross-talk with insulin signaling pathways. The molecular mechanisms subserving GH-induced insulin resistance in humans remain unclarified.

scholarly journals AMPK Enhances Insulin-Stimulated GLUT4 Regulation via Lowering Membrane Cholesterol

Endocrinology ◽  
2012 ◽  
Vol 153 (5) ◽  
pp. 2130-2141 ◽  
Author(s):  
Kirk M. Habegger ◽  
Nolan J. Hoffman ◽  
Colin M. Ridenour ◽  
Joseph T. Brozinick ◽  
Jeffrey S. Elmendorf
Keyword(s):  
Insulin Resistance ◽  
Cholesterol Synthesis ◽  
Glucose Transporter ◽  
Zucker Rats ◽  
Membrane Cholesterol ◽  
Filamentous Actin ◽  
Cholesterol Lowering ◽  
Insulin Resistant

AMP-activated protein kinase (AMPK) enhances glucose transporter GLUT4 regulation. AMPK also suppresses energy-consuming pathways such as cholesterol synthesis. Interestingly, recent in vitro and in vivo data suggest that excess membrane cholesterol impairs GLUT4 regulation. Therefore, this study tested whether a beneficial, GLUT4-regulatory aspect of AMPK stimulation involved cholesterol lowering. Using L6 myotubes stably expressing an exofacial myc-epitope-tagged-GLUT4, AMPK stimulation by 5-aminoimidazole-4-carboxamide-1-β-d-ribonucleoside (AICAR; 45 min, 1 mm) or 2,4-dinitrophenol (DNP; 30 min, 200 μm) increased cell surface GLUT4myc labeling by approximately ∼25% (P < 0.05). Insulin (20 min, 100 nm) also increased GLUT4myc labeling by about 50% (P < 0.05), which was further enhanced (∼25%, P < 0.05) by AICAR or DNP. Consistent with AMPK-mediated suppression of cholesterol synthesis, AICAR and DNP decreased membrane cholesterol by 20–25% (P < 0.05). Whereas AMPK knockdown prevented the enhanced basal and insulin-stimulated GLUT4myc labeling by AICAR and DNP, cholesterol replenishment only blocked the AMPK-associated enhancement in insulin action. Cells cultured in a hyperinsulinemic milieu, resembling conditions in vivo that promote the progression/worsening of insulin resistance, displayed an increase in membrane cholesterol. This occurred concomitantly with a loss of cortical filamentous actin (F-actin) and defects in GLUT4 regulation by insulin. These derangements were prevented by AMPK stimulation. Examination of skeletal muscle from insulin-resistant Zucker rats revealed a similar elevation in membrane cholesterol and loss of F-actin. Lowering cholesterol to control levels restored F-actin structure and insulin sensitivity. In conclusion, these data suggest a novel aspect of GLUT4 regulation by AMPK involves membrane cholesterol lowering. Moreover, this AMPK-mediated process protected against hyperinsulinemia-induced insulin resistance.

scholarly journals PEG-BHD1028 Peptide Regulates Insulin Resistance and Fatty Acid β-Oxidation, and Mitochondrial Biogenesis by Binding to Two Heterogeneous Binding Sites of Adiponectin Receptors, AdipoR1 and AdipoR2

2021 ◽  
Vol 22 (2) ◽  
pp. 884
Author(s):  
In Kyung Lee ◽  
Gyuyoup Kim ◽  
Do-Hwi Kim ◽  
Brian B. Kim
Keyword(s):  
Insulin Resistance ◽  
Fatty Acid ◽  
Mitochondrial Biogenesis ◽  
Binding Sites ◽  
Action Spectrum ◽  
C2c12 Cells ◽  
In Vivo Models ◽  
Insulin Resistant

Adiponectin plays multiple critical roles in modulating various physiological processes by binding to its receptors. The functions of PEG-BHD1028, a potent novel peptide agonist to AdipoRs, was evaluated using in vitro and in vivo models based on the reported action spectrum of adiponectin. To confirm the design concept of PEG-BHD1028, the binding sites and their affinities were analyzed using the SPR (Surface Plasmon Resonance) assay. The results revealed that PEG-BHD1028 was bound to two heterogeneous binding sites of AdipoR1 and AdipoR2 with a relatively high affinity. In C2C12 cells, PEG-BHD1028 significantly activated AMPK and subsequent pathways and enhanced fatty acid β-oxidation and mitochondrial biogenesis. Furthermore, it also facilitated glucose uptake by lowering insulin resistance in insulin-resistant C2C12 cells. PEG-BHD1028 significantly reduced the fasting plasma glucose level in db/db mice following a single s.c. injection of 50, 100, and 200 μg/Kg and glucose tolerance at a dose of 50 μg/Kg with significantly decreased insulin production. The animals received 5, 25, and 50 μg/Kg of PEG-BHD1028 for 21 days significantly lost their weight after 18 days in a range of 5–7%. These results imply the development of PEG-BHD1028 as a potential adiponectin replacement therapeutic agent.

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