AMP-activated protein kinase inhibits TGF-β-, angiotensin II-, aldosterone-, high glucose-, and albumin-induced epithelial-mesenchymal transition

2013 ◽  
Vol 304 (6) ◽  
pp. F686-F697 ◽  
Author(s):  
Jang Han Lee ◽  
Ji Hyun Kim ◽  
Ja Seon Kim ◽  
Jai Won Chang ◽  
Soon Bae Kim ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Protein Kinase ◽  
High Glucose ◽  
Renal Fibrosis ◽  
Epithelial Mesenchymal Transition ◽  
Urinary Albumin ◽  
Heme Oxygenase 1 ◽  
Mesenchymal Transition ◽  
Compound C ◽  
Amp Activated Protein Kinase

The epithelial-mesenchymal transition (EMT) is a novel mechanism that promotes renal fibrosis. Transforming growth factor-β (TGF-β), angiotensin II, aldosterone, high glucose, and urinary albumin are well-known causes of EMT and renal fibrosis. We examined whether and how activation of AMP-activated protein kinase (AMPK) suppressed EMT induced by the above agents in tubular epithelial cells. All experiments were performed using HK-2 cells. Protein expression was measured by Western blot analysis. Intracellular reactive oxygen species (ROS) were analyzed by flow cytometry. Exposure of tubular cells to TGF-β (10 ng/ml), angiotensin II (1 μM), aldosterone (100 nM), high glucose (30 mM), and albumin (5 mg/ml) for 5 days induced EMT, as shown by upregulation of α-smooth muscle actin and downregulation of E-cadherin. ROS and NADPH oxidase 4 (Nox4) expression were increased, and antioxidants such as tiron and N-acetylcysteine inhibited EMT induction. Metformin (the best known clinical activator of AMPK) suppressed EMT induction through inhibition of ROS via induction of heme oxygenase-1 and endogenous antioxidant thioredoxin. An AMPK inhibitor (compound C) and AMPK small interfering RNA blocked the effect of metformin, and another AMPK activator [5-aminoimidazole-4-carboxamide-1β riboside (AICAR)] exerted the same effects as metformin. In conclusion, AMPK activation might be beneficial in attenuating the tubulointerstitial fibrosis induced by TGF-β, angiotensin II, aldosterone, high glucose, and urinary albumin.

Activation of AMP-activated protein kinase inhibits ER stress and renal fibrosis

2015 ◽  
Vol 308 (3) ◽  
pp. F226-F236 ◽  
Author(s):  
Hyosang Kim ◽  
Soo Young Moon ◽  
Joon-Seok Kim ◽  
Chung Hee Baek ◽  
Miyeon Kim ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Mouse Model ◽  
Er Stress ◽  
Heme Oxygenase ◽  
Renal Fibrosis ◽  
Transforming Growth Factor ◽  
Initiation Factor ◽  
Heme Oxygenase 1 ◽  
Compound C ◽  
Amp Activated Protein Kinase

It has been suggested that endoplasmic reticulum (ER) stress facilitates fibrotic remodeling. Therefore, modulation of ER stress may serve as one of the possible therapeutic approaches to renal fibrosis. We examined whether and how activation of AMP-activated protein kinase (AMPK) suppressed ER stress induced by chemical ER stress inducers [tunicamycin (TM) and thapsigargin (TG)] and also nonchemical inducers in tubular HK-2 cells. We further investigated the in vivo effects of AMPK on ER stress and renal fibrosis. Western blot analysis, immunofluorescence, small interfering (si)RNA experiments, and immunohistochemical staining were performed. Metformin (the best known clinical activator of AMPK) suppressed TM- or TG-induced ER stress, as shown by the inhibition of TM- or TG-induced upregulation of glucose-related protein (GRP)78 and phosphorylated eukaryotic initiation factor-2α through induction of heme oxygenase-1. Metformin inhibited TM- or TG-induced epithelial-mesenchymal transitions as well. Compound C (AMPK inhibitor) blocked the effect of metformin, and 5-aminoimidazole-4-carboxamide-1β riboside (another AMPK activator) exerted the same effects as metformin. Transfection with siRNA targeting AMPK blocked the effect of metformin. Consistent with the results of cell culture experiments, metformin reduced renal cortical GRP78 expression and increased heme oxygenase-1 expression in a mouse model of ER stress-induced acute kidney injury by TM. Activation of AMPK also suppressed ER stress by transforming growth factor-β, ANG II, aldosterone, and high glucose. Furthermore, metformin reduced GRP78 expression and renal fibrosis in a mouse model of unilateral ureteral obstruction. In conclusion, AMPK may serve as a promising therapeutic target through reducing ER stress and renal fibrosis.

scholarly journals Coenzyme Q10 Attenuates High Glucose-Induced Endothelial Progenitor Cell Dysfunction through AMP-Activated Protein Kinase Pathways

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Hsiao-Ya Tsai ◽  
Chih-Pei Lin ◽  
Po-Hsun Huang ◽  
Szu-Yuan Li ◽  
Jia-Shiong Chen ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Coenzyme Q10 ◽  
High Glucose ◽  
Endothelial Progenitor Cell ◽  
Progenitor Cell ◽  
Heme Oxygenase 1 ◽  
Diabetic Patients ◽  
No Production ◽  
Endothelial Progenitor ◽  
Amp Activated Protein Kinase

Coenzyme Q10 (CoQ10), an antiapoptosis enzyme, is stored in the mitochondria of cells. We investigated whether CoQ10 can attenuate high glucose-induced endothelial progenitor cell (EPC) apoptosis and clarified its mechanism. EPCs were incubated with normal glucose (5 mM) or high glucose (25 mM) enviroment for 3 days, followed by treatment with CoQ10 (10 μM) for 24 hr. Cell proliferation, nitric oxide (NO) production, and JC-1 assay were examined. The specific signal pathways of AMP-activated protein kinase (AMPK), eNOS/Akt, and heme oxygenase-1 (HO-1) were also assessed. High glucose reduced EPC functional activities, including proliferation and migration. Additionally, Akt/eNOS activity and NO production were downregulated in high glucose-stimulated EPCs. Administration of CoQ10 ameliorated high glucose-induced EPC apoptosis, including downregulation of caspase 3, upregulation of Bcl-2, and increase in mitochondrial membrane potential. Furthermore, treatment with CoQ10 reduced reactive oxygen species, enhanced eNOS/Akt activity, and increased HO-1 expression in high glucose-treated EPCs. These effects were negated by administration of AMPK inhibitor. Transplantation of CoQ10-treated EPCs under high glucose conditions into ischemic hindlimbs improved blood flow recovery. CoQ10 reduced high glucose-induced EPC apoptosis and dysfunction through upregulation of eNOS, HO-1 through the AMPK pathway. Our findings provide a potential treatment strategy targeting dysfunctional EPC in diabetic patients.

scholarly journals Nobiletin Inhibits Hepatic Lipogenesis via Activation of AMP-Activated Protein Kinase

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Taewon Yuk ◽  
Younghwa Kim ◽  
Jinwoo Yang ◽  
Jeehye Sung ◽  
Heon Sang Jeong ◽  
...  
Keyword(s):  
Protein Kinase ◽  
High Glucose ◽  
Lipid Accumulation ◽  
Hepg2 Cells ◽  
Fatty Acid Synthase ◽  
Regulatory Element ◽  
Hepatic Lipogenesis ◽  
Nonalcoholic Fatty Liver ◽  
Compound C ◽  
Amp Activated Protein Kinase

We aimed to investigate the effects of nobiletin on hepatic lipogenesis in high glucose-induced lipid accumulation in HepG2 cells. Nobiletin, a citrus polymethoxyflavonoid with six methoxy groups, is present abundantly in the peels of citrus fruits. HepG2 cells were incubated in Dulbecco’s modified Eagle’s medium containing high glucose (25 mM) and subsequently treated with nobiletin at different concentrations (5, 25, and 50 μM). Results showed that nobiletin markedly inhibited high glucose-induced hepatic lipid accumulation in HepG2 cells. In addition, it reduced the protein expression of lipogenic factors, including sterol regulatory element-binding protein 1c (SREBP-1c) and fatty acid synthase (FAS). Nobiletin significantly increased the phosphorylation of AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase. Pretreatment with compound C, an AMPK inhibitor, abolished the inhibitory effects of nobiletin on SREBP-1c and FAS expression. These results suggested that nobiletin might attenuate high glucose-induced lipid accumulation in HepG2 hepatocytes via modulation of AMPK signaling pathway. Therefore, nobiletin might be useful for the prevention and treatment of nonalcoholic fatty liver diseases.

scholarly journals Knockdown of AMP-activated protein kinase α2 affects the epithelial-mesenchymal transition in rat renal tubular epithelial cells by downregulating v-ets erythroblastosis virus E26 oncogene homolog-1 and ribosomal protein S6 kinase A1

2019 ◽  
Author(s):  
Xiaoming Yin ◽  
Fujiang Ma ◽  
Xu Fan ◽  
Qi Zhao ◽  
Xin Liu ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Epithelial Mesenchymal Transition ◽  
Mapk Pathway ◽  
S6 Kinase ◽  
Mesenchymal Transition ◽  
Qrt Pcr ◽  
Ribosomal Protein S6 ◽  
Renal Tubular ◽  
Amp Activated Protein Kinase ◽  
Tgf Β1

Background. The epithelial mesenchymal transition (EMT) plays an important regulatory role in obstructive nephropathy and renal fibrosis. As an intracellular energy receptor, AMP-activated protein kinase (AMPK) is essential in the process of the EMT. The aim of this study was to reveal changes in the expression of AMPKα2 and to elucidate which AMPKα2 genes play a role during the EMT. Methods. In this study, TGF-β1 was used to induce the EMT in normal rat renal tubular epithelial (NRK-52E) cells. The shAMPKα2 lentivirus was used to interfere with AMPKα2 expression in EMT-derived NRK-52E cells, where AMPKα2 expression and the EMT were detected. Differential gene expression after the AMPKα2 knockout in EMT-derived NRK-52E cells was examined using a gene microarray. Possible regulatory pathways were analyzed using ingenuity pathway analysis (IPA) and differentially expressed genes were partially verified by quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting. Results. It was found that AMPKα2 was upregulated in TGF-β1-induced EMT-derived NRK-52E cells. The EMT progression was significantly inhibited after the expression of AMPKα2 was downregulated by the shAMPKα2 lentivirus. A total of 1,588 differentially expressed genes were detected after the AMPKα2 knockout in NRK-52E cells in which EMT occurred. The ERK/MAPK pathway was significantly inhibited after the AMPKα2 knockdown, as indicated by the IPA analysis. Furthermore, qRT-PCR and western blot results revealed that the expression of AMPKα2, v-ets erythroblastosis virus E26 oncogene homolog-1 (ETS1), and ribosomal protein S6 kinase A1 (RPS6KA1) was upregulated after the EMT in NRK-52E cells, while expression of ETS1 and RPS6KA1 was downregulated after the AMPKα2 knockout. Conclusions. AMPKα2 plays an important role in the regulation of rat renal tubular EMT, which may be achieved by modulating ETS1 and RPS6KA1 in the ERK/MAPK pathway.

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