scholarly journals AMPK, a metabolic sensor, is involved in isoeugenol-induced glucose uptake in muscle cells

2015 ◽  
Vol 228 (2) ◽  
pp. 105-114 ◽  
Author(s):  
Nami Kim ◽  
Jung Ok Lee ◽  
Hye Jeong Lee ◽  
Yong Woo Lee ◽  
Hyung Ip Kim ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Glucose Uptake ◽  
Glucose Transporter ◽  
Gene Encoding ◽  
Beneficial Effects ◽  
Calcium Calmodulin Dependent ◽  
L6 Myotubes ◽  
Glut4 Expression ◽  
Compound C ◽  
Dependent Protein

Isoeugenol exerts various beneficial effects on human health. However, the mechanisms underlying these effects are poorly understood. In this study, we observed that isoeugenol activated AMP-activated protein kinase (AMPK) and increased glucose uptake in rat L6 myotubes. Isoeugenol-induced increase in intracellular calcium concentration and glucose uptake was inhibited by STO-609, an inhibitor of calcium/calmodulin-dependent protein kinase kinase (CaMKK). Isoeugenol also increased the phosphorylation of protein kinase C-α (PKCα). Chelation of calcium with BAPTA-AM blocked isoeugenol-induced AMPK phosphorylation and glucose uptake. Isoeugenol stimulated p38MAPK phosphorylation that was inhibited after pretreatment with compound C, an AMPK inhibitor. Isoeugenol also increased glucose transporter type 4 (GLUT4) expression and its translocation to the plasma membrane. GLUT4 translocation was not observed after the inhibition of AMPK and CaMKK. In addition, isoeugenol activated the Akt substrate 160 (AS160) pathway, which is downstream of the p38MAPK pathway. Knockdown of the gene encoding AS160 inhibited isoeugenol-induced glucose uptake. Together, these results indicate that isoeugenol exerts beneficial health effects by activating the AMPK/p38MAPK/AS160 pathways in skeletal muscle.

scholarly journals Ethanolic Extract of Folium Sennae Mediates the Glucose Uptake of L6 Cells by GLUT4 and Ca2+

Molecules ◽  
2018 ◽  
Vol 23 (11) ◽  
pp. 2934 ◽  
Author(s):  
Ping Zhao ◽  
Qian Ming ◽  
Junying Qiu ◽  
Di Tian ◽  
Jia Liu ◽  
...  
Keyword(s):  
Diabetes Mellitus ◽  
Protein Kinase ◽  
Glucose Uptake ◽  
G Protein ◽  
Glucose Transporter ◽  
Ethanolic Extract ◽  
High Morbidity ◽  
L6 Cells ◽  
Glut4 Expression ◽  
Compound C

In today’s world, diabetes mellitus (DM) is on the rise, especially type 2 diabetes mellitus (T2DM), which is characterized by insulin resistance. T2DM has high morbidity, and therapies with natural products have attracted much attention in the recent past. In this paper, we aimed to study the hypoglycemic effect and the mechanism of an ethanolic extract of Folium Sennae (FSE) on L6 cells. The glucose uptake of L6 cells was investigated using a glucose assay kit. We studied glucose transporter 4 (GLUT4) expression and AMP-activated protein kinase (AMPK), protein kinase B (PKB/Akt), and protein kinase C (PKC) phosphorylation levels using western blot analysis. GLUT4 trafficking and intracellular Ca2+ levels were monitored by laser confocal microscopy in L6 cells stably expressing IRAP-mOrange. GLUT4 fusion with plasma membrane (PM) was observed by myc-GLUT4-mOrange. FSE stimulated glucose uptake; GLUT4 expression and translocation; PM fusion; intracellular Ca2+ elevation; and the phosphorylation of AMPK, Akt, and PKC in L6 cells. GLUT4 translocation was weakened by the AMPK inhibitor compound C, PI3K inhibitor Wortmannin, PKC inhibitor Gö6983, G protein inhibitor PTX/Gallein, and PLC inhibitor U73122. Similarly, in addition to PTX/Gallein and U73122, the IP3R inhibitor 2-APB and a 0 mM Ca2+-EGTA solution partially inhibited the elevation of intracellular Ca2+ levels. BAPTA-AM had a significant inhibitory effect on FSE-mediated GLUT4 activities. In summary, FSE regulates GLUT4 expression and translocation by activating the AMPK, PI3K/Akt, and G protein–PLC–PKC pathways. FSE causes increasing Ca2+ concentration to complete the fusion of GLUT4 vesicles with PM, allowing glucose uptake. Therefore, FSE may be a potential drug for improving T2DM.

Nitric oxide increases GLUT4 expression and regulates AMPK signaling in skeletal muscle

2007 ◽  
Vol 293 (4) ◽  
pp. E1062-E1068 ◽  
Author(s):  
Vitor A. Lira ◽  
Quinlyn A. Soltow ◽  
Jodi H. D. Long ◽  
Jenna L. Betters ◽  
Jeff E. Sellman ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Skeletal Muscle ◽  
Glucose Transporter ◽  
No Donor ◽  
Ampk Signaling ◽  
L6 Myotubes ◽  
Glut4 Expression ◽  
Compound C ◽  
Cgmp Analog

Nitric oxide (NO) and 5′-AMP-activated protein kinase (AMPK) are involved in glucose transport and mitochondrial biogenesis in skeletal muscle. Here, we examined whether NO regulates the expression of the major glucose transporter in muscle (GLUT4) and whether it influences AMPK-induced upregulation of GLUT4. At low levels, the NO donor S-nitroso- N-penicillamine (SNAP, 1 and 10 μM) significantly increased GLUT4 mRNA (∼3-fold; P < 0.05) in L6 myotubes, and cotreatment with the AMPK inhibitor compound C ablated this effect. The cGMP analog 8-bromo-cGMP (8-Br-cGMP, 2 mM) increased GLUT4 mRNA by ∼50% ( P < 0.05). GLUT4 protein expression was elevated 40% by 2 days treatment with 8-Br-cGMP, whereas 6 days treatment with 10 μM SNAP increased GLUT4 expression by 65%. Cotreatment of cultures with the guanylyl cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3,-a]quinoxalin-1-one prevented the SNAP-induced increase in GLUT4 protein. SNAP (10 μM) also induced significant phosphorylation of α-AMPK and acetyl-CoA carboxylase and translocation of phosphorylated α-AMPK to the nucleus. Furthermore, L6 myotubes exposed to 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR) for 16 h presented an approximately ninefold increase in GLUT4 mRNA, whereas cotreatment with the non-isoform-specific NOS inhibitor NG-nitro-l-arginine methyl ester, prevented ∼70% of this effect. In vivo, GLUT4 mRNA was increased 1.8-fold in the rat plantaris muscle 12 h after AICAR injection, and this induction was reduced by ∼50% in animals cotreated with the neuronal and inducible nitric oxide synthases selective inhibitor 1-(2-trifluoromethyl-phenyl)-imidazole. We conclude that, in skeletal muscle, NO increases GLUT4 expression via a cGMP- and AMPK-dependent mechanism. The data are consistent with a role for NO in the regulation of AMPK, possibly via control of cellular activity of AMPK kinases and/or AMPK phosphatases.

scholarly journals MerTK signaling in macrophages promotes the synthesis of inflammation resolution mediators by suppressing CaMKII activity

2018 ◽  
Vol 11 (549) ◽  
pp. eaar3721 ◽  
Author(s):  
Bishuang Cai ◽  
Canan Kasikara ◽  
Amanda C. Doran ◽  
Rajasekhar Ramakrishnan ◽  
Raymond B. Birge ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Inflammatory Diseases ◽  
Critical Role ◽  
Mitogen Activated Protein Kinase ◽  
Gene Encoding ◽  
Endoplasmic Reticulum Calcium ◽  
Calcium Calmodulin Dependent ◽  
Mitogen Activated Protein ◽  
Dependent Protein ◽  
Inflammation Resolution

Inflammation resolution counterbalances excessive inflammation and restores tissue homeostasis after injury. Failure of resolution contributes to the pathology of numerous chronic inflammatory diseases. Resolution is mediated by endogenous specialized proresolving mediators (SPMs), which are derived from long-chain fatty acids by lipoxygenase (LOX) enzymes. 5-LOX plays a critical role in the biosynthesis of two classes of SPMs: lipoxins and resolvins. Cytoplasmic localization of the nonphosphorylated form of 5-LOX is essential for SPM biosynthesis, whereas nuclear localization of phosphorylated 5-LOX promotes proinflammatory leukotriene production. We previously showed that MerTK, an efferocytosis receptor on macrophages, promotes SPM biosynthesis by increasing the abundance of nonphosphorylated, cytoplasmic 5-LOX. We now show that activation of MerTK in human macrophages led to ERK-mediated expression of the gene encoding sarcoplasmic/endoplasmic reticulum calcium ATPase 2 (SERCA2), which decreased the cytosolic Ca2+ concentration and suppressed the activity of calcium/calmodulin-dependent protein kinase II (CaMKII). This, in turn, reduced the activities of the mitogen-activated protein kinase (MAPK) p38 and the kinase MK2, resulting in the increased abundance of the nonphosphorylated, cytoplasmic form of 5-LOX and enhanced SPM biosynthesis. In a zymosan-induced peritonitis model, an inflammatory setting in which macrophage MerTK activation promotes resolution, inhibition of ERK activation delayed resolution, which was characterized by an increased number of neutrophils and decreased amounts of SPMs in tissue exudates. These findings contribute to our understanding of how MerTK signaling induces 5-LOX–derived SPM biosynthesis and suggest a therapeutic strategy to boost inflammation resolution in settings where defective resolution promotes disease progression.

scholarly journals Reduction of Insulin-Stimulated Glucose Uptake in L6 Myotubes by the Protein Kinase Inhibitor SB203580 Is Independent of p38MAPK Activity

Endocrinology ◽  
2005 ◽  
Vol 146 (9) ◽  
pp. 3773-3781 ◽  
Author(s):  
C. N. Antonescu ◽  
C. Huang ◽  
W. Niu ◽  
Z. Liu ◽  
P. A. Eyers ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Glucose Uptake ◽  
Glucose Transporter ◽  
Kinase Inhibitor ◽  
Dominant Negative ◽  
Small Interfering Rnas ◽  
Insulin Stimulation ◽  
L6 Myotubes ◽  
Low Levels ◽  
Glucose Transporter Glut4

Abstract Insulin increases glucose uptake through translocation of the glucose transporter GLUT4 to the plasma membrane. We previously showed that insulin activates p38MAPK, and inhibitors of p38MAPKα and p38MAPKβ (e.g. SB203580) reduce insulin-stimulated glucose uptake without affecting GLUT4 translocation. This observation suggested that insulin may increase GLUT4 activity via p38α and/or p38β. Here we further explore the possible participation of p38MAPK through a combination of molecular strategies. SB203580 reduced insulin stimulation of glucose uptake in L6 myotubes overexpressing an SB203580-resistant p38α (drug-resistant p38α) but barely affected phosphorylation of the p38 substrate MAPK-activated protein kinase-2. Expression of dominant-negative p38α or p38β reduced p38MAPK phosphorylation by 70% but had no effect on insulin-stimulated glucose uptake. Gene silencing via isoform-specific small interfering RNAs reduced expression of p38α or p38β by 60–70% without diminishing insulin-stimulated glucose uptake. SB203580 reduced photoaffinity labeling of GLUT4 by bio-LC-ATB-BMPA only in the insulin-stimulated state. Unless low levels of p38MAPK suffice to regulate glucose uptake, these results suggest that the inhibition of insulin-stimulated glucose transport by SB203580 is likely not mediated by p38MAPK. Instead, changes experienced by insulin-stimulated GLUT4 make it susceptible to inhibition by SB203580.

scholarly journals Dandelion Chloroform Extract Promotes Glucose Uptake via the AMPK/GLUT4 Pathway in L6 Cells

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Ping Zhao ◽  
Qian Ming ◽  
Mingrui Xiong ◽  
Guanjun Song ◽  
Li Tan ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Glucose Uptake ◽  
Laser Scanning ◽  
Chloroform Extract ◽  
Cell Culture Supernatant ◽  
Glut4 Translocation ◽  
L6 Cells ◽  
Glut4 Expression ◽  
Compound C ◽  
Number Of Patients

The number of patients with type 2 diabetes mellitus (T2DM) is increasing rapidly worldwide. Glucose transporter 4 (GLUT4) is one of the main proteins that transport blood glucose into the cells and is a target in the treatment of T2DM. In this study, we investigated the mechanism of action of dandelion chloroform extract (DCE) on glucose uptake in L6 cells. The glucose consumption of L6 cell culture supernatant was measured by a glucose uptake assay kit, and the dynamic changes of intracellular GLUT4 and calcium (Ca2+) levels were monitored by laser scanning confocal microscopy in L6 cell lines stably expressing IRAP-mOrange. The GLUT4 fusion with the plasma membrane (PM) was traced via myc-GLUT4-mOrange. GLUT4 expression and AMP-activated protein kinase (AMPK), protein kinase B (PKB/Akt), protein kinase C (PKC), and phosphorylation levels were determined by performing western blotting. GLUT4 mRNA expression was detected by real-time PCR. DCE up-regulated GLUT4 expression, promoted GLUT4 translocation and fusion to the membrane eventually leading to glucose uptake, and induced AMPK phosphorylation in L6 cells. The AMPK inhibitory compound C significantly inhibited DCE-induced GLUT4 expression and translocation while no inhibitory effect was observed by the phosphatidylinositol 3-kinase (PI3K) inhibitor Wortmannin and PKC inhibitor Gö6983. These data suggested that DCE promoted GLUT4 expression and transport to the membrane through the AMPK signaling pathway, thereby stimulating GLUT4 fusion with PM to enhance glucose uptake in L6 cells. DCE-induced GLUT4 translocation was also found to be Ca2+-independent. Together, these findings indicate that DCE could be a new hypoglycemic agent for the treatment of T2DM.

scholarly journals Eicosapentaenoic Acid (EPA) Modulates Glucose Metabolism by Targeting AMP-Activated Protein Kinase (AMPK) Pathway

2019 ◽  
Vol 20 (19) ◽  
pp. 4751 ◽  
Author(s):  
Nami Kim ◽  
Mi Sun Kang ◽  
Miso Nam ◽  
Shin Ae Kim ◽  
Geum-Sook Hwang ◽  
...  
Keyword(s):  
Protein Kinase ◽  
P38 Mapk ◽  
Molecular Mechanisms ◽  
Glucose Transporter ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Omega 3 ◽  
Beneficial Effects ◽  
Calcium Calmodulin Dependent ◽  
Amp Activated Protein Kinase

EPA, an omega-3 polyunsaturated fatty acid, exerts beneficial effects on human health. However, the molecular mechanisms underlying EPA function are poorly understood. The object was to illuminate molecular mechanism underlying EPA’s role. Here, 1H-NMR-based metabolic analysis showed enhanced branched-chain amino acids (BCAAs) and lactate following EPA treatment in skeletal muscle cells. EPA regulated mitochondrial oxygen consumption rate. Furthermore, EPA induced calcium/calmodulin-dependent protein kinase kinase (CaMKK) through the generation of intracellular calcium. This induced the phosphorylation of AMP-activated protein kinase (AMPK) and p38 mitogen-activated protein kinase (p38 MAPK) that led to glucose uptake, and the translocation of glucose transporter type 4 (GLUT4) in muscles. In conclusion, EPA exerts benign effects on glucose through the activation of AMPK-p38 MAPK signaling pathways in skeletal muscles.

scholarly journals In vitro and in silico characterization of adiponectin-receptor agonist dipeptides

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Yuna Lee ◽  
Akihiro Nakano ◽  
Saya Nakamura ◽  
Kenta Sakai ◽  
Mitsuru Tanaka ◽  
...  
Keyword(s):  
Glucose Uptake ◽  
Glucose Transporter ◽  
Adenosine Monophosphate ◽  
Adiponectin Receptor ◽  
L6 Myotubes ◽  
Glut4 Expression ◽  
Binding Pockets ◽  
Dynamics Simulations ◽  
In Silico Characterization

AbstractThe aim of this study is to develop a dipeptide showing an adiponectin receptor 1 (AdipoR1) agonistic effect in skeletal muscle L6 myotubes. Based on the structure of the AdipoR1 agonist, AdipoRon, 15 synthetic dipeptides were targeted to promote glucose uptake in L6 myotubes. Tyr-Pro showed a significant increase in glucose uptake among the dipeptides, while other dipeptides, including Pro-Tyr, failed to exert this effect. Tyr-Pro induces glucose transporter 4 (Glut4) expression in the plasma membrane, along with adenosine monophosphate-activated protein kinase (AMPK) activation. In AdipoR1-knocked down cells, the promotion by Tyr-Pro was ameliorated, indicating that Tyr-Pro may directly interact with AdipoR1 as an agonist, followed by the activation of AMPK/Glut4 translocation in L6 myotubes. Molecular dynamics simulations revealed that a Tyr-Pro molecule was stably positioned in the two potential binding pockets (sites 1 and 2) of the seven-transmembrane receptor, AdipoR1, anchored in a virtual 1-palmitoyl-2-oleoyl-phosphatidylcholine membrane. In conclusion, we demonstrated the antidiabetic function of the Tyr-Pro dipeptide as a possible AdipoR1 agonist.

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