scholarly journals AMP-Activated Protein Kinase Alleviates Extracellular Matrix Accumulation in High Glucose-Induced Renal Fibroblasts through mTOR Signaling Pathway

2015 ◽  
Vol 35 (1) ◽  
pp. 191-200 ◽  
Author(s):  
Xia Luo ◽  
Lingyan Deng ◽  
Laxmi Pangeni Lamsal ◽  
Wenjuan Xu ◽  
Cheng Xiang ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Protein Kinase ◽  
Signaling Pathway ◽  
High Glucose ◽  
Mtor Signaling ◽  
Dependent Manner ◽  
Mtor Signaling Pathway ◽  
Matrix Synthesis ◽  
Matrix Accumulation ◽  
Amp Activated Protein Kinase

Background/Aims: Extracellular matrix accumulation contributes significantly to the pathogenesis of diabetic nephropathy. Although AMP-activated protein kinase (AMPK) has been found to inhibit extracellular matrix synthesis by experiments in vivo and vitro, its role in alleviating the deposition of extracellular matrix in renal interstitial fibroblasts has not been well defined. Methods: Currently, we conducted this study to investigate the effects of AMPK on high glucose-induced extracellular matrix synthesis and involved intracellular signaling pathway by using western blot in the kidney fibroblast cell line (NRK-49f). Results: Collagen IV protein levels were significantly increased by high glucose in a time-dependent manner. This was associated with a decrease in Thr72 phosphorylation of AMPK and an increase in phosphorylation of mTOR on Ser2448. High glucose-induced extracellular matrix accumulation and mTOR activation were significantly inhibited by the co-treatment of rAAV-AMPKα1312 (encoding constitutively active AMPKα1) whereas activated by r-AAV-AMPKα1D157A (encoding dominant negative AMPKα1). In cultured renal fibroblasts, overexpression of AMPKα1D157A upregulated mTOR signaling and matrix synthesis, which were ameliorated by co-treatment with the inhibitor of mTOR, rapamycin. Conclusion: Collectively, these findings indicate that AMPK exerts renoprotective effects by inhibiting the accumulation of extracellular matrix through mTOR signaling pathway.

scholarly journals (Pro)renin receptor regulates autophagy and apoptosis in podocytes exposed to high glucose

2015 ◽  
Vol 309 (3) ◽  
pp. E302-E310 ◽  
Author(s):  
Caixia Li ◽  
Helmy M. Siragy
Keyword(s):  
Signaling Pathway ◽  
High Glucose ◽  
Caspase 3 ◽  
Mtor Signaling ◽  
Autophagic Flux ◽  
Bafilomycin A1 ◽  
Mtor Signaling Pathway ◽  
Autophagosome Formation ◽  
Podocyte Injury ◽  
Protein Levels

High glucose reduces autophagy and enhances apoptosis of podocytes. Previously, we reported that high glucose induced podocyte injury through upregulation of the (pro)renin receptor (PRR). We hypothesized that increasing PRR reduces autophagy and increases apoptosis of mouse podocytes exposed to high glucose via activation of the PI3K/Akt/mTOR signaling pathway. Mouse podocytes were cultured in normal (5 mmol/l) or high (25 mmol/l) d-glucose for 48 h. High glucose significantly increased mRNA and protein levels of PRR, phosphorylation of PI3K/Akt/mTOR, and p62. In contrast, high glucose decreased activation of UNC-51-like kinase-1 (ULK1) by phosphorylating Ser757 and protein levels of microtubule-associated protein-1 light chain 3B (LC3B)-II and Lamp-2. Bafilomycin A1 increased LC3BII and p62 accumulation in high-glucose-treated cells. High glucose reduced the autophagic flux. Confocal microscopy studies showed significant reduction in the protein level of LC3B in response to high glucose. Cyto-ID autophagy staining showed a significant decrease in autophagosome formation with high glucose. In the absence of PRR, activation of Akt with sc-79 or mTOR with MHY-1485 increased p62 accumulation. Caspase-3/7 activity and apoptosis monitored by TUNEL assay were significantly increased in podocytes treated with high glucose. PRR siRNA significantly reversed the effects of high glucose. Based on these data, we conclude that high glucose decreases autophagy and increases apoptosis in mouse podocytes through the PRR/PI3K/Akt/mTOR signaling pathway.

scholarly journals Ginsenoside Rg3 Suppresses Proliferation and Induces Apoptosis in Human Osteosarcoma

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Yi Li ◽  
Jinying Lu ◽  
Furong Bai ◽  
Yanan Xiao ◽  
Yiran Guo ◽  
...  
Keyword(s):  
Western Blot ◽  
Signaling Pathway ◽  
Mtor Signaling ◽  
Assay Method ◽  
Osteosarcoma Cell ◽  
Dependent Manner ◽  
Ginsenoside Rg3 ◽  
Mtor Signaling Pathway ◽  
Human Osteosarcoma ◽  
Human Osteosarcoma Cells

Osteosarcoma is the most common primary malignancy of bone in children and the elderly. Recently, more and more researches have demonstrated that Ginsenoside Rg3 (Rg3) is involved in chemotherapy resistance in many cancer, making it a promising Chinese herbal monomer for oncotherapy. In this study, we investigated the efficacy of Rg3 in human osteosarcoma cell lines (MG-63, U-2OS, and SaOS-2). Cell proliferation was measured by CCK8 assay. The migration of cells was examined using the scratch assay method. Quantification of apoptosis was assessed further by flow cytometry. In addition, the expression of apoptosis-related genes (caspase9, caspase3, Bcl2, and Bax) were investigated using RT-PCR. We further investigated the protein level expression of Bcl 2, cleaved-caspase3, and PI3K/AKT/mTOR signaling pathway factors by Western blot assay. Our results revealed that Rg3 inhibited the proliferation and migration of human osteosarcoma cells and induced apoptosis in a concentration- and time-dependent manner. Western blot results showed that Rg3 reduced the protein expression of Bcl2 and PI3K/AKT/mTORbut increased the levels of cleaved-caspase3. Therefore, we hypothesized Rg3 inhibits the proliferation of osteosarcoma cell line and induces their apoptosis by affecting apoptosis-related genes (Bcl2, caspase3) as well as the PI3K/AKT/mTOR signaling pathway. To conclude, Rg3 is a new therapeutic agent against osteosarcoma.

scholarly journals Melatonin-induced Cell Rejuvenation from Long-term Ex-vivo passaging Functioned by its Restoration of Damaged Cell Autophagic Processes

2020 ◽  
Author(s):  
Yi-Zhou Tan ◽  
Xin-Yue Xu ◽  
Ji-Min Dai ◽  
Yuan Yin ◽  
Xiao-Tao He ◽  
...  
Keyword(s):  
Stem Cells ◽  
Signaling Pathway ◽  
Cellular Senescence ◽  
Ex Vivo ◽  
Mtor Signaling ◽  
Beclin 1 ◽  
Dependent Manner ◽  
Mtor Signaling Pathway ◽  
Associated Proteins

Abstract Background: Stem cells undergone long-term ex-vivo expansion are most likely functionally compromised (namely cellular senescence) in terms of their stem cell properties and therapeutic potentials. Due to the ability to attenuate cellular senescence, melatonin (MLT) has been proposed as an adjuvant across long-term cell expansion protocols, but the underlying mechanism remains largely unknown. Methods: Human periodontal ligament stem cells (PDLSCs) were isolated and cultured ex-vivo for 15 passages, and passage 2, 7 and 15 cells were used to interrogate the cellular senescence and alteration in cell autophagy during long-term expansion. The cellular senescence features were evidenced by senescence-associated β-galacotosidase (SA-β-gal) activity and the expression of senescence-related proteins including p53, p21, p16 and γ-H2AX. Electronic microscope was used to observe the autophagic vesicles. Adenovirus mRFP-GFP-LC3 was transfected to indicate the alteration of autophagic flux during long-term expansion, and the autophagy-associated proteins Atg7, Beclin-1, LC3-II and p62 were evaluated by Western blot. Results: It was found that long-term in-vitro passaging led to an accumulated SA-β-gal, elevated expressions of p53, p21, p16 and γ-H2AX, along with downregulated autophagy-associated proteins Atg7, Beclin-1 and LC3 as well as a mounting autophagy substrate p62. In accordance with expectation, supplemented with MLT not only ameliorated cells to a younger state but also restored the impaired autophagy level in senescent cells. Additionally, we demonstrated that autophagy inhibitor could block such MLT-induced cell rejuvenation. When the underlying signaling pathways involved was interrogated, we found that MLT receptor (MT) participated in mediating MLT-related autophagy restoration by regulating PI3K/AKT/mTOR signaling pathway.Conclusions: The present study suggests that MLT may rejuvenate long-term expansion-caused cellular senescence by restoring autophagy, more likely via PI3K/AKT/mTOR signaling pathway in an MT-dependent manner. This is the first report identifying the MT-dependent PI3K/AKT/mTOR signaling involved in MLT-induced autophagy alteration, pointing to a potential target for using autophagy-restoring agents such as MLT to develop optimized clinical-scale cell production protocols.

scholarly journals Activated mTORC1-SIRT6 Mediates Myofibroblast Differentiation and Idiopathic Pulmonary Fibrosis

2021 ◽  
Author(s):  
Ji Zhang ◽  
Yi Hu ◽  
Huiping Huang ◽  
Qun Liu ◽  
Yang Du ◽  
...  
Keyword(s):  
Pulmonary Fibrosis ◽  
Signaling Pathway ◽  
Mtor Signaling ◽  
Signalling Pathway ◽  
Lung Fibroblasts ◽  
Myofibroblast Differentiation ◽  
Dependent Manner ◽  
Mtor Signaling Pathway ◽  
Mtorc1 Pathway ◽  
Tgf Β1

Abstract BackgroundIdiopathic pulmonary fibrosis (IPF) is characterised by accumulation of myofibroblasts and deposition of extracellular matrix proteins. Fibroblast-to-myofibroblast transdifferentiation and myofibroblast hyperproliferation plays a major role in pulmonary fibrosis. Moreover, mTOR signaling pathway and SIRT6 play a critical role in pulmonary fibrosis. However, the mechanisms whether SIRT6 affect the myofibroblasts differentiation during IPF remain unclear.MethodWe investigated myofibroblast differentiation using a bleomycin-induced mouse pulmonary fibrosis model and TGF-b1 induced human fetal lung fibroblasts (MRC5) in vitro. We used both SIRT6 siRNA and rapamycin to study the role of SIRT6 and mTOR signaling pathway in the normal human lung fibroblasts and the myofibroblasts from human IPF lungs.ResultsOur data show that high level of SIRT6 was detected in IPF samples, and SIRT6 was significantly upregulated by TGF-β1 in a time and concentration-dependent manner. SIRT6 expression and activation of mTORC1 signalling pathway were upregulated in fibrotic lung tissues and primary lung fibroblasts isolated from patients with IPF and bleomycin-challenged mice. Furthermore, rapamycin treatment inhibited mTORC1 pathway activity and SIRT6 protein expression. SIRT6 SiRNA failed to mediate the activity of mTORC1 pathway and autophagy induction. However, SIRT6 knockdown could promote TGF-b1 induced pro-fibrotic cytokines.ConclusionActivated mTORC1 signalling pathway regulated SIRT6 overexpression. Deficiency of SIRT6 mediated myofibroblasts differentiation through induced pro-fibrotic cytokines production in the present of TGF-β1. The study indicated that manipulations of SIRT6 expression may provide a new therapeutic strategy to prevent and reverse the progression of pulmonary fibrosis.

Metformin suppresses the esophageal carcinogenesis in rats treated with NMBzA through inhibiting AMPK/mTOR signaling pathway

2018 ◽  
Vol 40 (5) ◽  
pp. 669-679 ◽  
Author(s):  
Hongjun Fan ◽  
Xiying Yu ◽  
Zhigeng Zou ◽  
Wei Zheng ◽  
Xin Deng ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Precancerous Lesions ◽  
Epidemiological Studies ◽  
Mtor Signaling ◽  
Mtor Signaling Pathway ◽  
Tumor Sphere ◽  
Esophageal Epithelial Cells ◽  
Amp Activated Protein Kinase

Abstract Metformin is a widely used antidiabetic drug for the management of type 2 diabetes mellitus. Recently, epidemiological studies demonstrate that metformin has anticancer effects on esophageal squamous cell carcinoma (ESCC) and other cancers. However, the effects and potential mechanisms of metformin on ESCC remain elusive. In this study, we used N-nitroso-N-methylbenzylamine (NMBzA), a special carcinogen for esophagi, to develop a rat ESCC model, in which the carcinogenesis progression of ESCC in rat was induced and promoted. We investigated the effects of metformin on carcinogenesis of ESCC in this model. Our results revealed that metformin significantly decreased the incidence and precancerous lesions of ESCC and inhibited proliferation and promoted apoptosis of esophageal epithelial cells in rat treated with NMBzA. Moreover, metformin also increased apoptosis and inhibited migration, colony formation and tumor sphere formation of human ESCC cells in vitro. Immunohistochemistry and western blotting showed that without interfering the metabolism of NMBzA, metformin inhibited the inflammation of esophagi via reducing the expressions of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) and interleukin-6 (IL-6). Treatment of metformin led to activation of AMP-activated protein kinase (AMPK) and attenuated signaling of the downstream molecules such as p-mTOR, p-p70S6K and cyclin D1 expression both in vivo and in vitro. Taken together, our study demonstrated that metformin suppressed the carcinogenesis of ESCC through inhibiting AMPK/mammalian target of the rapamycin (mTOR) signaling pathway, resulting in its chemopreventive effects on the carcinogenesis of ESCC.

scholarly journals Justicidin B Inhibits PDGF-BB-Induced Proliferation and ECM Accumulation in Mesangial Cells via Nrf2/HO-1 and Akt/mTOR Signaling Pathway

2020 ◽  
Vol 15 (5) ◽  
pp. 1934578X2092382
Author(s):  
Zhong-zhu Ai ◽  
Shan-shan Zhou ◽  
Song-tao Wu ◽  
Zong-chao Hong ◽  
Yu Zhang ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Signaling Pathway ◽  
Herbal Remedy ◽  
Mtor Signaling ◽  
Inflammatory Factors ◽  
Heme Oxygenase 1 ◽  
Related Factor ◽  
Mtor Signaling Pathway ◽  
Matrix Deposition ◽  
Mesangial Area

Mesangial proliferative glomerulonephritis (MsPGN) is characterized by mesangial cell proliferation, inflammation, and extracellular matrix deposition in the mesangial area, which develops into glomerulosclerosis and contributes to end-stage renal disease. Justicidin B is a bioactive compound isolated from Justicia procumbens L., a traditional herbal remedy that reduces proteinuria in nephritis. However, the mechanism of Justicidin B’s therapeutic effect on MsPGN remains unclear. This study was aimed to explore the positive effect of Justicidin B on MsPGN. The results showed that Justicidin B attenuated the proliferation induced by platelet-derived growth factor-BB (PDGF-BB) in MCs and blocked cell cycle progression. Likewise, inflammatory factors, including monocyte chemotactic protein 1 (MCP-1) and tumor necrosis factor alpha (TNF-α), in MCs were decreased after treatment with Justicidin B. In addition, Justicidin B exhibited antioxidant activity in PDGF-BB-induced MCs, shown by the decreased production of malondialdehyde and T-AOC, and increased the expression of superoxide dismutase. Besides, Justicidin B suppressed extracellular matrix (ECM) deposition by reducing the protein levels of collagen IV and fibronectin. Furthermore, we found that Justicidin B significantly inhibited activation of the Akt/mammalian target of rapamycin (mTOR) signaling pathway in MCs induced by PDGF-BB, but enhanced the levels of proteins in the nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase 1 (HO-1) pathway. Taken together, Justicidin B prevented PDGF-BB-induced proliferation, inflammation, oxidative stress, and ECM accumulation via regulating the activation of the Nrf2/HO-1 pathway and the Akt/mTOR signaling pathway.

Gambogic Acid Affects Ribosomal Occurrence in Glioma Cells by Downregulating the Phosphoinositide Kinase-3/Protein Kinase B/Mammalian Target of Rapamycin Signaling Pathway

2020 ◽  
Vol 20 (6) ◽  
pp. 3361-3372 ◽  
Author(s):  
Guoxuan Luo ◽  
Shengqiang Jiang ◽  
Xu Zhang ◽  
Yunzhi Ling ◽  
Hengshan Luo ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Signaling Pathway ◽  
Protein Kinase B ◽  
Mammalian Target Of Rapamycin ◽  
Glioma Cells ◽  
Mtor Signaling ◽  
Target Of Rapamycin ◽  
Gambogic Acid ◽  
Mtor Signaling Pathway ◽  
Phosphoinositide Kinase

Gambogic acid (GA) is a natural compound with a polyprenylated xanthone structure that has antiinflammatory, antioxidant, and neuroprotective properties and acts as a chemopreventive agent. GA exhibits anti-tumor, antimicrobial, and anti-proliferative effects on cancer cells. In the current study, the effect of GA on phosphoinositide kinase-3 (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling pathway was examined in human U251 glioma cells. Cell viability and apoptosis were evaluated by MTT and Annexin V/PI Double Staining. The expressions of P38, AKT, and mTOR were evaluated by western blot and qRT-PCR, respectively. MagBeads Total RNA Extraction Kit was used to isolate cell tissue RNA. GA decreased the phosphorylation of P38, AKT, and mTOR. Inhibitors of PI3K (LY294002) enhanced the phosphorylation of P38, AKT, and mTOR. GA reduced the phosphorylation of ribosomal protein precursors (Pre) and upstream binding factor (UBF), and insulin-like growth factor I (IGF-1) further enhanced the cell proliferation and expression of Pre and UBF. These results suggested that downregulation of PI3K/AKT/mTOR signaling pathway may be an important mediator in GA-affected ribosomal occurrence in glioma cells.

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