Metformin Inhibits Abdominal Aortic Aneurysm Formation through the Activation of the AMPK/mTOR Signaling Pathway

2021 ◽  
pp. 1-11
Author(s):  
Jiaan He ◽  
Nan Li ◽  
Yichuan Fan ◽  
Xingzhi Zhao ◽  
Chengwei Liu ◽  
...  
Keyword(s):  
Abdominal Aortic Aneurysm ◽  
Aortic Aneurysm ◽  
Signaling Pathway ◽  
Mtor Signaling ◽  
Protective Mechanism ◽  
Mtor Signaling Pathway ◽  
Sprague Dawley ◽  
Downstream Signaling ◽  
Compound C ◽  
Abdominal Aortic

Background and Objective: Epidemiological evidence suggests that the antidiabetic drug metformin (MET) can also inhibit abdominal aortic aneurysm (AAA) formation. However, the underlying protective mechanism remains unknown. It has been reported that phosphorylated AMP-activated protein kinase (AMPK) levels are significantly lower in AAA tissues than control aortic tissues. AMPK activation can inhibit the downstream signaling molecule called mechanistic target of rapamycin (mTOR), which has also been reported be upregulated in thoracic aneurysms. Thus, blocking mTOR signaling could attenuate AAA progression. MET is a known agonist of AMPK. Therefore, in this study, we investigated if MET could inhibit formation of AAA by activating the AMPK/mTOR signaling pathway. Materials and Methods: The AAA animal model was induced by intraluminal porcine pancreatic elastase (PPE) perfusion in male Sprague Dawley rats. The rats were treated with MET or compound C (C.C), which is an AMPK inhibitor. AAA formation was monitored by serial ultrasound. Aortas were collected 4 weeks after surgery and subjected to immunohistochemistry, Western blot, and transmission electron microscopy analyses. Results: MET treatment dramatically inhibited the formation of AAA 4 weeks after PPE perfusion. MET reduced the aortic diameter, downregulated both macrophage infiltration and matrix metalloproteinase expression, decreased neovascularization, and preserved the contractile phenotype of the aortic vascular smooth muscle cells. Furthermore, we detected an increase in autophagy after MET treatment. All of these effects were reversed by the AMPK inhibitor C.C. Conclusion: This study demonstrated that MET activates AMPK and suppresses AAA formation. Our study provides a novel mechanism for MET and suggests that MET could be potentially used as a therapeutic candidate for preventing AAA.

Active vitamin D activates chondrocyte autophagy to reduce osteoarthritis via mediating the AMPK–mTOR signaling pathway

2020 ◽  
Vol 98 (3) ◽  
pp. 434-442 ◽  
Author(s):  
Chunyu Kong ◽  
Changlei Wang ◽  
Yuquan Shi ◽  
Lei Yan ◽  
Junhua Xu ◽  
...  
Keyword(s):  
Vitamin D ◽  
Signaling Pathway ◽  
Therapeutic Option ◽  
Serum Levels ◽  
Mtor Signaling ◽  
Mtor Signaling Pathway ◽  
Ampk Signaling ◽  
Hydroxyvitamin D ◽  
Compound C ◽  
Safranin O

Osteoarthritis (OA) is a common joint degenerative disease. Vitamin D (VD) is essential for bone health. We hypothesized that active VD could be used as a therapeutic treatment for OA. Low serum levels of 25-hydroxyvitamin D [25(OH)D] have been found in patients with OA, and thus the serum level of VD could be diagnostic of OA. To test this, we established a mouse model of OA. The results from staining with hematoxylin–eosin and Safranin O – Fast Green indicated that active VD reduced the symptoms of OA in mice. The results from Western blotting indicated that treatment with VD increased the activity of the p-AMPK–AMPK signaling pathway and decreased the p-mTOR–mTOR pathway; it also increased the ratio of LC3II:LC3I antibodies and the protein expression levels of Beclin-1, but decreased the level of p62. Further, treatment with VD reduced the levels of tumor necrosis factor-α and interleukin-6 both in cartilage tissues and in chondrocytes. Administration of the AMPK inhibitor compound C and autophagy inhibitor 3-methyladenine (3-MA) reversed these changes following VD treatment. In addition, the results from transfection with mRFP-GFP-LC3 indicated that active VD led to autophagosome aggregation in OA chondrocytes. 3-MA inhibited cell autophagy and promoted inflammation in OA. This study provides evidence that active VD activate chondrocyte autophagy to reduce OA inflammation via activating the AMPK–mTOR signaling pathway. Treatment with active VD could be a novel therapeutic option for OA.

scholarly journals NOX2-Derived Hydrogen Peroxide Impedes the AMPK/Akt-mTOR Signaling Pathway in Parkinson's Disease in Vitro Models

2021 ◽  
Author(s):  
Ruijie Zhang ◽  
Nana Zhang ◽  
Xiaoqing Dong ◽  
Xin Chen ◽  
Jing Ma ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Parkinson’S Disease ◽  
Hydrogen Peroxide ◽  
Parkinson's Disease ◽  
Signaling Pathway ◽  
Neuronal Apoptosis ◽  
Mtor Signaling ◽  
Regulatory Proteins ◽  
Mtor Signaling Pathway ◽  
Compound C

Abstract Oxidative stress is closely related to the pathogenesis of Parkinson's disease (PD), a typical neurodegenerative disease. NADPH oxidase 2 (NOX2) is involved in hydrogen peroxide (H2O2) generation. Recently, we have reported that H2O2 and PD toxins, including 6-hydroxydopamine (6-OHDA), 1-Methyl-4-phenylpyridin-1-ium (MPP+) and rotenone, induce neuronal apoptosis by inhibiting mTOR pathway. Here, we show that 6-OHDA, MPP+ or rotenone induced H2O2 generation by upregulation of NOX2 and its regulatory proteins (p22phox, p40phox, p47phox, p67phox, and Rac1), leading to apoptotic cell death in PC12 cells and primary neurons. Pretreatment with catalase, a H2O2-scavenging enzyme, significantly blocked PD toxins-evoked NOX2-derived H2O2, thereby hindering activation of AMPK, inhibition of Akt/mTOR, induction of apoptosis in neuronal cells. Similar events were also seen in the cells pretreated with Mito-TEMPO, a mitochondria-specific superoxide scavenger, implying a mitochondrial H2O2-dependent mechanism involved. Further research revealed that inhibiting NOX2 with apocynin or silencing NOX2 attenuated the effects of PD toxins on AMPK/Akt/mTOR and apoptosis in the cells. Of importance, ectopic expression of constitutively active Akt or dominant negative AMPKα, or inhibition of AMPK with compound C suppressed PD toxins-induced expression of NOX2 and its regulatory proteins, as well as consequential H2O2 and apoptosis in the cells. Taken together, these results indicate that certain PD toxins can impede the AMPK/Akt-mTOR signaling pathway leading to neuronal apoptosis by eliciting NOX2-derived H2O2. Our findings suggest that neuronal loss in PD may be prevented by regulating of NOX2, AMPK/Akt-mTOR signaling and/or administering antioxidants to ameliorate oxidative stress.

scholarly journals Knockdown of long noncoding RNA GAS5 reduces vascular smooth muscle cell apoptosis by inactivating EZH2-mediated RIG-I signaling pathway in abdominal aortic aneurysm

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Tianming Le ◽  
Xin He ◽  
Jianhua Huang ◽  
Shuai Liu ◽  
Yang Bai ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Abdominal Aortic Aneurysm ◽  
Aortic Aneurysm ◽  
Signaling Pathway ◽  
Cell Apoptosis ◽  
Rna Binding ◽  
Ectopic Expression ◽  
Tunel Staining ◽  
Ang Ii ◽  
Abdominal Aortic

Abstract Background Abdominal aortic aneurysm (AAA), an irreversible cardiovascular disease prevalent in the artery, causes the increase of the aneurysm diameter over time, and is a fatal phenomenon inducing sidewall rupture. Long noncoding RNAs (lncRNAs) serve as promising biomarkers for AAA. In the present study, we sought to define the role of lncRNA growth-arrest-specific transcript 5 (GAS5) in growth of smooth muscle cells (SMC) and progression of AAA. Methods Initially, we established angiotensin II (Ang II)-induced AAA mouse models and Ang II-treated vascular SMC model. RT-qPCR and Western blot analysis were adopted to determine expression of GAS5 and zeste homolog 2 (EZH2). After ectopic expression and depletion experiments in Ang II-treated mice and vascular SMCs, cell apoptosis was detected in SMCs using flow cytometry and in mice using TUNEL staining. The binding of GAS5 and EZH2 was evaluated using RNA binding protein immunoprecipitation (RIP) and Co-IP assays. Results Increased GAS5 and RIG-I but decreased EZH2 were found in aortic tissues of AAA mice. EZH2 overexpression inhibited AAA formation and suppressed SMC apoptosis. Functionally, EZH2 blocked the RIG-I signaling pathway and consequently inhibited SMC apoptosis. GAS5 regulated EZH2 transcription in a negative manner in SMCs. Knockdown of GAS5 attenuated SMC apoptosis, which was reversed by EZH2 inhibition or RIG-I overexpression. Conclusions The current study demonstrated that GAS5 induced SMC apoptosis and subsequent AAA onset by activating EZH2-mediated RIG-I signaling pathway, highlighting GAS5 as a novel biomarker for AAA.

scholarly journals Apelin-13 Regulates Angiotensin II-Induced Cx43 Downregulation and Autophagy via the AMPK/mTOR Signaling Pathway in HL-1 Cells

2020 ◽  
pp. 813-822
Author(s):  
Y CHEN ◽  
X QIAO ◽  
L ZHANG ◽  
X LI ◽  
Q LIU
Keyword(s):  
Atrial Fibrillation ◽  
Angiotensin Ii ◽  
Signaling Pathway ◽  
Connexin 43 ◽  
Mtor Signaling ◽  
Atrial Remodeling ◽  
Mtor Signaling Pathway ◽  
Cx43 Expression ◽  
Compound C ◽  
Cell Hypertrophy

Atrial fibrillation is associated with atrial remodeling, in which connexin 43 (Cx43) and cell hypertrophy play important roles. In this study, apelin-13, an aliphatic peptide, was used to explore the protective effects of the adenosine monophosphate-activated protein kinase (AMPK)/mTOR signaling pathway on Cx43 expression and autophagy, using murine atrial HL-1 cells. The expression of Cx43, AMPK, B-type natriuretic peptide (BNP) and pathway-related proteins was detected by Western blot analysis. Cellular fluorescence imaging was used to visualize Cx43 distribution and the cytoskeleton. Our results showed that the Cx43 expression was significantly decreased in HL-1 cells treated with angiotensin II but increased in cells additionally treated with apelin-13. Meanwhile, apelin-13 decreased BNP expression and increased AMPK expression. However, the expression of Cx43 and LC3 increased by apelin-13 was inhibited by treatment with compound C, an AMPK inhibitor. In addition, rapamycin, an mTOR inhibitor, promoted the development of autophagy, further inhibited the protective effect on Cx43 expression and increased cell hypertrophy. Thus, apelin-13 enhances Cx43 expression and autophagy via the AMPK/mTOR signaling pathway, and serving as a potential therapeutic target for atrial fibrillation.

Emodin Ameliorate High Glucose-induced Podocyte Apoptosis via Regulating AMPK/mTOR- mediated Autophagy Signaling Pathway

2021 ◽  
Author(s):  
Hong Liu ◽  
Yanglin Hu ◽  
Ge Shi ◽  
Wenqiang Yang ◽  
Fei Xiong ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
High Glucose ◽  
Cell Apoptosis ◽  
Caspase 3 ◽  
Therapeutic Option ◽  
Mtor Signaling ◽  
Mtor Signaling Pathway ◽  
Trypan Blue Exclusion ◽  
Compound C

Abstract Background: Podocyte apoptosis and autophagy dysfunction have been considered to be one of the important causes of diabetic nephropathy (DN). Emodin has the function of regulating autophagy. The present study was performed to investigate the effect of emodin on high glucose (HG)-induced podocyte apoptosis and whether the potential anti-apoptotic mechanism of emodin is related to the induction of AMPK/mTOR-mediated autophagy in MPC5 cells in vitro.Methods: The viability and apoptosis of podocytes (MPC5 cells) were detected using CCK-8 assay, trypan blue exclusion assay and flow cytometry analysis, respectively. The expression levels of Cleaved caspase-3, autophagy maker LC3 I/II, and AMPK/mTOR signaling pathway-related proteins were evaluated with western blot analysis. The changes of morphology and RFP-LC3 fluorescence were observed under microscopy.Results: HG (20-160 mmol/L) dose-dependently induced cell apoptosis in MPC5 cells, whereas emodin (4 μmol/L) significantly ameliorated HG-induced cell apoptosis and caspase-3 cleavage. Emodin (4 μmol/L) significantly increased LC3-II levels and induced RFP-LC3-containing punctate structures in MPC5 cells. Furthermore, the protective effects of emodin were mimicked by rapamycin (100 nmol/L). Moreover, emodin increased the phosphorylation of AMPK and suppressed the phosphorylation of mTOR. The AMPK inhibitor compound C (10 μmol/L) abolished emodin-induced autophagy activation.Conclusion: Emodin ameliorated HG-induced apoptosis of MPC5 cells in vitro that involved induction of autophagy through the AMPK/mTOR signaling pathway, which might provide a potential therapeutic option for DN.

scholarly journals Neferine Enhances Autophagy to Alleviate Cytotoxicity and Apoptosis Induced by CSE in AEC-II through AMPK/mTOR Signaling Pathway

2020 ◽  
Author(s):  
Mengmeng Wang ◽  
Haiyang Yu ◽  
Yuqing Sun ◽  
Pengpeng Cheng ◽  
Qian Wang ◽  
...  
Keyword(s):  
Protective Effect ◽  
Signaling Pathway ◽  
Cell Model ◽  
Cell Damage ◽  
Case Fatality ◽  
Chronic Respiratory Disease ◽  
Mtor Signaling ◽  
Autophagic Flux ◽  
Mtor Signaling Pathway ◽  
Compound C

Abstract COPD is a clinical common chronic respiratory disease, its incidence case fatality rate is higher, there is currently no cure drugs and methods. In this study, in order to make clear its role in the development of autophagy in COPD, COPD cell model is established.To further explore whether regulating autophagy could have a protective effect to fight against CSE-induced cytotoxicity and apoptosis, we choose neferine as an autophagy inducer. Neferine activated cell autophagy in an vitro CSE-induced COPD cell model and gradually attenuated CSE-induced cell apoptosis. Furthermore, this process happens largely through the AMPK/mTOR signaling pathway. As a autophagic flux inhibitor, chloroquine abolished the prosurvival autophagy effect, and AMPK inhibitor Compound C blocked neferine-mediated autophagy and then neferine failed to protect COPD cell model from CSE-induced apoptosis. Overall,our findings suggested that neferine possibly has a potentially protective effect in cell damage mechanisms caused by CSE. It hints that neferine has the prospect of turning into a potential therapeutics to cure CSE-induced cytotoxicity and apoptosis and even COPD patients.

scholarly journals 17β-Estradiol Induces Mitophagy Upregulation to Protect Chondrocytes via the SIRT1-Mediated AMPK/mTOR Signaling Pathway

2021 ◽  
Vol 11 ◽  
Author(s):  
Runhong Mei ◽  
Peng Lou ◽  
Guanchao You ◽  
Tianlong Jiang ◽  
Xuefeng Yu ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Western Blotting ◽  
Mtor Signaling ◽  
Sirtuin 1 ◽  
Mtor Signaling Pathway ◽  
Compound C ◽  
Transmission Electron ◽  
Sirt1 Inhibitor ◽  
17Β Estradiol ◽  
Related Proteins

Increasing evidence reveals that estrogen, especially 17β-estradiol (17β-E2), is associated with articular cartilage metabolism disorder and postmenopausal osteoarthritis (OA). SIRT1, AMPK, and mTOR are regarded as critical mitophagy regulators. Recent studies have shown that mitophagy displays a protective effect against OA, but the molecular mechanism is not well known. This study aimed to investigate the effect of 17β-E2 on Sirtuin-1 (SIRT1) expression and the induction of mitophagy upregulation by 17β-E2 via the SIRT1-mediated AMP-activated protein kinase (AMPK)/mammalian target of the rapamycin (mTOR) signaling pathway to protect chondrocytes. ATDC5 chondrocytes were treated with different concentrations of 17β-E2 (0 M, 1 × 10-9 M, 1 × 10-8 M, and 1 × 10-7 M) for 24 h or pretreatment with or without NAM (SIRT1 inhibitor), Compound C (AMPK inhibitor) and S1842 (mTOR inhibitor) for 30 min prior to treatment with 17β-E2 (1 × 10-7 M) for 24 in each groups. Expression of SIRT1 was evaluated by real-time PCR, Western blotting and confocal immunofluorescence staining. Then, the mitophagosomes in cells were observed under a transmission electron microscopy (TEM), and the AMPK/mTOR signaling pathway was detected by Western blotting. The mitophagy-related proteins, p-AMPK, p-mTOR, p-JNK, and p-p38 were also identified by Western blot analysis. The chondrocytes viability and proliferation were determined by MTT and 5-Bromo-2’-deoxyuridine (BrdU) assay. These experiments were independently repeated 3 times The study found that 17β-E2 increased the expression level of SIRT1, p-AMPK, and mitophagy-related proteins but decreased p-mTOR expression, and then induced mitophagy upregulation in chondrocytes. More mitochondrial autophagosomes were observed in 17β-E2-treated chondrocytes under a transmission electron microscope. Also, 17β-E2 improved cell viability and proliferation with the higher expression of SIRT1 and activation of the AMPK/mTOR signaling pathway. However, SIRT1 inhibitor nicotinamide (NAM) and AMPK inhibitor Compound C blocked the beneficial effect of 17β-E2. In summary, this study was novel in demonstrating that 17β-E2 induced mitophagy upregulation to protect chondrocytes via the SIRT1-mediated AMPK/mTOR signaling pathway.

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