Mesangial cell NADPH oxidase upregulation in high glucose is protein kinase C dependent and required for collagen IV expression

2006 ◽  
Vol 290 (2) ◽  
pp. F345-F356 ◽  
Author(s):  
L. Xia ◽  
H. Wang ◽  
H. J. Goldberg ◽  
S. Munk ◽  
I. G. Fantus ◽  
...  

Excess collagen IV expression by mesangial cells contributes to diabetic glomerulosclerosis. We hypothesized that in high glucose reactive oxygen species (ROS) generation by NADPH oxidase is PKC dependent and required for collagen IV expression by mesangial cells. In rat mesangial cells cultured in 5 mM (NG) or 25 mM d-glucose (HG), RT-PCR and Western immunoblotting detected p22phox and p47phox mRNA and protein, respectively. Quantitative real-time RT-PCR analyzed collagen IV mRNA. With the use of confocal microscopy, ROS were detected with dichlorofluorescein and intracellular collagen IV by immunofluorescence. In HG, ROS were generated within 1 h, sustained up to 48 h, and prevented by a NADPH oxidase inhibitor, diphenylenechloride iodonium (DPI), or a conventional PKC isozyme inhibitor, Gö6976. In NG, phorbol myristate acetate stimulated ROS generation that was inhibited with DPI. In HG, expression of p22phox and p47phox was increased within 3 to 6 h and inhibited by Gö6976. In HG, Gö6976 or transfection with antisense against p22phox reversed the 1.8-fold increase in collagen IV mRNA. In HG, the antioxidants Tempol or Tiron, or transfection with antisense against p22phox or p47phox, prevented ROS generation and the 2.3-fold increase in collagen IV protein. Increased mitochondrial redox potential in HG was unaffected by transfection with antisense against p22phox. We conclude that in HG, mesangial cell ROS generation by upregulated NADPH oxidase is dependent on conventional PKC isozymes and also required for collagen IV expression.

2012 ◽  
Vol 302 (1) ◽  
pp. F159-F172 ◽  
Author(s):  
Y. Zhang ◽  
F. Peng ◽  
B. Gao ◽  
A. J. Ingram ◽  
J. C. Krepinsky

Glomerular matrix accumulation is a hallmark of diabetic nephropathy. We previously showed that RhoA activation by high glucose in mesangial cells (MC) leads to matrix upregulation (Peng F, Wu D, Gao B, Ingram AJ, Zhang B, Chorneyko K, McKenzie R, Krepinsky JC. Diabetes 57: 1683–1692, 2008). Here, we study the mechanism whereby RhoA is activated. In primary rat MC, RhoA activation required glucose entry and metabolism. Broad PKC inhibitors (PMA, bisindolylmaleimide, Gö6976), as well as specific PKCβ blockade with an inhibitor and small interfering RNA (siRNA), prevented RhoA activation by glucose. PKCβ inhibition also abrogated reactive oxygen species (ROS) generation by glucose. The ROS scavenger N-acetylcysteine (NAC) or NADPH oxidase inhibitors apocynin and DPI prevented glucose-induced RhoA activation. RhoA and some PKC isoforms localize to caveolae. Chemical disruption of these microdomains prevented RhoA and PKCβ1 activation by glucose. In caveolin-1 knockout cells, glucose did not induce RhoA and PKCβ1 activation; these responses were rescued by caveolin-1 reexpression. Furthermore, glucose-induced ROS generation was significantly attenuated by chemical disruption of caveolae and in knockout cells. Downstream of RhoA signaling, activator protein-1 (AP-1) activation was also inhibited by disrupting caveolae, was absent in caveolin-1 knockout MC and rescued by caveolin-1 reexpression. Finally, transforming growth factor (TGF)-β1 upregulation, mediated by AP-1, was prevented by RhoA signaling inhibition and by disruption or absence of caveolae. In conclusion, RhoA activation by glucose is dependent on PKCβ1-induced ROS generation, most likely through NADPH oxidase. The activation of PKCβ1 and its downstream effects, including upregulation of TGF-β1, requires caveolae. These microdomains are thus important mediators of the profibrogenic process associated with diabetic nephropathy.


2009 ◽  
Vol 2009 ◽  
pp. 1-11 ◽  
Author(s):  
Catharine Whiteside ◽  
Hong Wang ◽  
Ling Xia ◽  
Snezana Munk ◽  
Howard J. Goldberg ◽  
...  

Peroxisome proliferator-activated receptor (PPARγ), a ligand-dependent transcription factor, negatively modulates high glucose effects. We postulated that rosiglitazone (RSG), an activator of PPARγprevents the upregulation of vascular endothelial growth factor (VEGF) and collagen IV by mesangial cells exposed to high glucose. Primary cultured rat mesangial cells were growth-arrested in 5.6 mM (NG) or 25 mM D-glucose (HG) for up to 48 hours. In HG, PPARγmRNA and protein were reduced within 3 h, and enhanced ROS generation, expression ofp22phox, VEGF and collagen IV, and PKC-ζmembrane association were prevented by RSG. In NG, inhibition of PPARγcaused ROS generation and VEGF expression that were unchanged by RSG. Reduced AMP-activated protein kinase (AMPK) phosphorylation in HG was unchanged with RSG, and VEGF expression was unaffected by AMPK inhibition. Hence, PPARγis a negative modulator of HG-induced signaling that acts through PKC-ζbut not AMPK and regulates VEGF and collagen IV expression by mesangial cells.


2008 ◽  
Vol 295 (6) ◽  
pp. F1705-F1714 ◽  
Author(s):  
Ling Xia ◽  
Hong Wang ◽  
Snezana Munk ◽  
Janice Kwan ◽  
Howard J. Goldberg ◽  
...  

Conversion of normally quiescent mesangial cells into extracellular matrix-overproducing myofibroblasts in response to high ambient glucose and transforming growth factor (TGF)-β1 is central to the pathogenesis of diabetic nephropathy. Previously, we reported that mesangial cells respond to high glucose by generating reactive oxygen species (ROS) from NADPH oxidase dependent on protein kinase C (PKC) -ζ activation. We investigated the role of TGF-β1 in this action of high glucose on primary rat mesangial cells within 1–48 h. Both high glucose and exogenous TGF-β1 stimulated PKC-ζ kinase activity, as measured by an immune complex kinase assay and immunofluorescence confocal cellular imaging. In high glucose, Akt Ser473 phosphorylation appeared within 1 h and Smad2/3 nuclear translocation was prevented with neutralizing TGF-β1 antibodies. Neutralizing TGF-β1 antibodies, or a TGF-β receptor kinase inhibitor (LY364947), or a phosphatidylinositol 3,4,5-trisphosphate (PI3) kinase inhibitor (wortmannin), prevented PKC-ζ activation by high glucose. TGF-β1 also stimulated cellular membrane translocation of PKC-α, -β1, -δ, and -ε, similar to high glucose. High glucose and TGF-β1 enhanced ROS generation by mesangial cell NADPH oxidase, as detected by 2,7-dichlorofluorescein immunofluorescence. This response was abrogated by neutralizing TGF-β1 antibodies, LY364947, or a specific PKC-ζ pseudosubstrate peptide inhibitor. Expression of constitutively active PKC-ζ in normal glucose caused upregulation of p22phox, a likely mechanism of NADPH oxidase activation. We conclude that very early responses of mesangial cells to high glucose include autocrine TGF-β1 stimulation of PKC isozymes including PI3 kinase activation of PKC-ζ and consequent generation of ROS by NADPH oxidase.


1996 ◽  
Vol 316 (3) ◽  
pp. 985-992 ◽  
Author(s):  
Nadia Abdel WAHAB ◽  
Katherine HARPER ◽  
Roger M. MASON

Post-mitotic cultures of human mesangial cells were maintained in media containing 4–30 mM D-glucose for up to 28 days. Changes in mRNA and protein levels for specific macromolecules occurred between 7 and 14 days after initiating hyperglycaemic conditions. Slot blot analysis showed 2–3-fold increases in mRNAs for collagen type I, fibronectin, versican and perlecan, whereas mRNA for decorin was increased by up to 20-fold. Levels of mRNAs for biglycan and syndecan were unaffected by hyperglycaemic culture. Reverse transcriptase PCR (RT–PCR) confirmed that decorin mRNA levels are greatly elevated and also showed increased transcription of the TGF-β1 gene in hyperglycaemic cultures. Western analysis and ELISA indicated accumulations of collagen types I and III, laminin and fibronectin in the cell layers and media of hyperglycaemic cultures with increasing time. Type IV collagen did not accumulate in either compartment of hyperglycaemic mesangial cell cultures. Collagen types I, III, and fibronectin did not accumulate in the cell layers of hyperglycaemic human dermal fibroblasts, indicating a cell-specific response in mesangial cultures. Decorin and versican, but not biglycan, were increased in the hyperglycaemic mesangial cell culture media. There were no apparent changes in core proteins for decorin and biglycan in fibroblast media. Transforming growth factor β1 (TGF-β1) in hyperglycaemic mesangial cell cultures increased 5-fold after 7 days, but decreased thereafter to only approx. 2-fold after 28 days. The changes in TGF-β1 mRNA, as detected by RT–PCR, and protein followed one another closely.


2013 ◽  
Vol 113 (suppl_1) ◽  
Author(s):  
Yu Chen ◽  
Jingang Cui ◽  
Qinbo Yang ◽  
Chenglin Jia ◽  
Minqi Xiong ◽  
...  

Myocardial fibrosis results from cardiac injuries caused by various pathophysiological mechanisms including myocardial infarction, leading to destruction of myocardial architecture and progressive cardiac dysfunction. Oxidative stress is likely involved in myocardial ischemic injury and the subsequent tissue remodeling mediated by myocardial fibrogenesis. Our current study aimed to evaluate the implication of NADPH oxidase in overproduction of reactive oxygen species and its contribution to the pathogenesis of myocardial fibrogenesis after ischemic injuries. The effects of Apocynin, a selective NADPH oxidase inhibitor, were evaluated in the mouse model of isoproterenol-induced myocardial injury by histopathological approaches and whole-genome gene expression profiling. The results demonstrated that Apocynin was able to inhibit the development of ISO-induced myocardial necrotic lesions and fibrogenesis in a dose-dependent manner. Moreover, the preventive effects of Apocynin on myocardial injuries were associated with suppressed expression of genes implicated in inflammation responses and extracellular matrix, which were remarkably upregulated by isoproterenol administration. In summary, o ur study provides proof-of-concept for the involvement of NADPH oxidase-mediated ROS generation in myocardial ischemic injuries and fibrogenesis, which will benefit the mechanism-based therapeutic development targeting NADPH oxidase and oxidative stress in treating myocardial fibrosis and related disorders.


2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Ablikim Abliz ◽  
Chen Chen ◽  
Wenhong Deng ◽  
Weixing Wang ◽  
Rongze Sun

PCBs, widespread endocrine disruptors, cause the disturbance of thyroid hormone (TH) homeostasis in humans and animals. However, the exact mechanism of thyroid dysfunction caused by PCBs is still unknown. In order to clarify the hypotheses that NADPH oxidase (NOX) and subsequent NF-κB pathway may play roles in thyroid dysfunction, sixty Sprague-Dawley rats were randomly divided into four groups: control group, PCB153 treated (PCB) group, received apocynin with PCB153 treatment (APO + PCB) group, and drug control (APO) group. Serum thyroid hormone levels were evaluated. The morphological change of thyroid tissue was analyzed under the light and transmission electron microscopy. NOX2, 8-OHdG, and NF-κB expression in the thyroid tissue was evaluated by immune-histochemical staining. Oxidative stress and inflammatory cytokines were detected. The following results were reduced after apocynin treatment: (1) serum thyroid hormone, (2) thyroid pathological injuries, (3) thyroid MDA, (4) thyroid ultrastructural change, (5) serum inflammatory cytokines, and (6) thyroid expression of NOX2, 8-OHdG, and NF-κB. These results suggested that NOX inhibition attenuates thyroid dysfunction induced by PCB in rats, presumably because of its role in preventing ROS generation and inhibiting the activation of NF-κB pathway. Our findings may provide new therapeutic targets for PCBs induced thyroid dysfunction.


2001 ◽  
Vol 280 (4) ◽  
pp. F667-F674 ◽  
Author(s):  
Chhinder P. Sodhi ◽  
Sarojini A. Phadke ◽  
Daniel Batlle ◽  
Atul Sahai

The effect of hypoxia on the proliferation and collagen synthesis of cultured rat mesangial cells was examined under normal-glucose (NG, 5 mM) and high-glucose (HG, 25 mM)-media conditions. In addition, a role for osteopontin (OPN) in mediating these processes was assessed. Quiescent cultures were exposed to hypoxia (3% O2) and normoxia (18% O2) in a serum-free medium with NG or HG, and cell proliferation, collagen synthesis, and OPN expression were assessed. Cells exposed to hypoxia in NG medium resulted in significant increases in [3H]thymidine incorporation, cell number, and [3H]proline incorporation, respectively. HG incubations also produced significant stimulation of these parameters under normoxic conditions, which were markedly enhanced in cells exposed to hypoxia in HG medium. In addition, hypoxia and HG stimulated the mRNA levels of type IV collagen, and the combination of hypoxia and HG resulted in additive increases in type IV collagen expression. Hypoxia and HG also stimulated OPN mRNA and protein levels in an additive fashion. A neutralizing antibody to OPN or its β3-integrin receptor significantly blocked the effect of hypoxia and HG on proliferation and collagen synthesis. In conclusion, these results demonstrate for the first time that hypoxia in HG medium produces exaggerated mesangial cell growth and type IV collagen synthesis. In addition, OPN appears to play a role in mediating the accelerated mesangial cell growth and collagen synthesis found in a hyperglycemic and hypoxic environment.


2021 ◽  
Vol 7 ◽  
Author(s):  
Lin Liao ◽  
Jie Chen ◽  
Chuanfu Zhang ◽  
Yue Guo ◽  
Weiwei Liu ◽  
...  

Glomerular hypertrophy is an early morphological alteration in diabetic nephropathy. Cyclin-Dependent Kinases have been shown to be required for high glucose (HG)-induced hypertrophy; however, the upstream regulators of CDKN1B in glomerular hypertrophy remain unclear. Herein we describe a novel pathway in which Long noncoding RNA (lncRNA) NEAT1 regulates the progression of mesangial cell hypertrophy via a competing endogenous RNA (ceRNA) mechanism. Real-time PCR was performed to detect the relative NEAT1 and miR-222-3p expressions and further confirmed the relationship between NEAT1 and miR-222-3p. Cell cycle was evaluated by flow cytometry. The related mechanisms were explored by Western blot, RNA immunoprecipitation and chromatin immunoprecipitation assay. We show that NEAT1 forms double stranded RNA (dsRNA) with miR-222-3p, thus limiting miR-222-3p’s binding with CDKN1B. This release of CDKN1B mRNA leads to elevated CDKN1B protein expression, resulting in hypertrophy. In addition, we demonstrated that STAT3 which is activated by HG induces the transcription of NEAT1 by binding to its promoter. Our findings underscore an unexpected role of lncRNAs on gene regulation and introduce a new mode of proliferation regulation in mesangial cells.


Molecules ◽  
2018 ◽  
Vol 24 (1) ◽  
pp. 80 ◽  
Author(s):  
Mei-Fen Chen ◽  
Shorong-Shii Liou ◽  
Tang-Yao Hong ◽  
Shung-Te Kao ◽  
I-Min Liu

Gigantol is a bibenzyl compound derived from several medicinal orchids. This biologically active compound has shown promising therapeutic potential against diabetic cataracts, but whether this compound exerts beneficial effects on the other diabetic microvascular complications remains unclear. This study was carried out to examine effects of gigantol on high glucose-induced renal cell injury in cultured mouse kidney mesangial cells (MES-13). MES-13 cells were pretreated with gigantol (1, 5, 10 or 20 μmol/L) for 1 h followed by further exposure to high (33.3 mmol/L) glucose for 48 h. Gigantol concentration dependently enhanced cell viability followed by high glucose treatment in MES-13 cells. High glucose induced reactive oxygen species (ROS) generation, malondialdehyde production and glutathione deficiency were recoved in MES-13 cells pretreated with gigantol. High glucose triggered cell apoptosis via the the loss of mitochondrial membrane potential, depletion of adenosine triphosphate, upregulation of caspases 9 and 3, enhancement of cytochrome c release, and subsequent interruption of the Bax/Bcl-2 balance. These detrimental effects were ameliorated by gigantol. High glucose also induced activation of JNK, p38 mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) in MES-13 cells, which were blocked by gigantol. The results suggest that treatment MES-13 cells with gigantol halts high glucose-induced renal dysfunction through the suppression of the ROS/MAPK/NF-κB signaling pathways. Our data are of value to the understanding the mechanism for gigantol, and would benefit the study of drug development or food supplement for diabetes and nephropathy.


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