CREB, NF-κB, and NADPH oxidase coordinately upregulate indoxyl sulfate-induced angiotensinogen expression in proximal tubular cells

2013 ◽  
Vol 304 (7) ◽  
pp. C685-C692 ◽  
Author(s):  
Hidehisa Shimizu ◽  
Shinichi Saito ◽  
Yukihiro Higashiyama ◽  
Fuyuhiko Nishijima ◽  
Toshimitsu Niwa
Keyword(s):  
Nadph Oxidase ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Indoxyl Sulfate ◽  
Pyrrolidine Dithiocarbamate ◽  
Uremic Toxin ◽  
Proximal Tubular Cells ◽  
Induced Expression ◽  
Tubular Cells ◽  
Nadph Oxidase 4 ◽  
Proximal Tubular

In chronic kidney disease (CKD), indoxyl sulfate, a uremic toxin, accumulates in serum, and the expression of angiotensinogen (AGT) is upregulated in renal proximal tubular cells. The present study aimed to determine the relationship between indoxyl sulfate and the upregulation of AGT expression in proximal tubular cells. Indoxyl sulfate induced expression of AGT in rat renal cortex and in cultured human proximal tubular cells (HK-2). In proximal tubular cells, indoxyl sulfate induced phosphorylation of cAMP response element-binding protein (CREB) on Ser-133, and small interfering RNA (siRNA) specific to CREB inhibited indoxyl sulfate-induced AGT expression. Our previous study demonstrated that indoxyl sulfate activated nuclear factor-κB (NF-κB) through reactive oxygen species (ROS) production. NF-κB inhibitors (pyrrolidine dithiocarbamate and isohelenin), NF-κB p65 siRNA, an antioxidant [ N-acetylcysteine (NAC)], and a nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor [diphenyleneiodonium (DPI)] suppressed indoxyl sulfate-induced AGT expression. Both NAC and DPI suppressed indoxyl sulfate-induced expression of NF-κB p65 and CREB. CREB siRNA suppressed indoxyl sulfate-induced NF-κB p65 expression, whereas both NF-κB inhibitors and NF-κB p65 siRNA prevented indoxyl sulfate-induced CREB expression. Furthermore, we focused on the expression of NADPH oxidase 4 (NOX4), because indoxyl sulfate induced NOX4 expression in vascular smooth muscle cells and vascular endothelial cells. Indoxyl sulfate induced the expression of NOX4 in proximal tubular cells, which was suppressed by NAC, DPI, NF-κB inhibitors, NF-κB p65 siRNA, and CREB siRNA. Taken together, CREB, NF-κB, and NOX4 coordinately upregulate indoxyl sulfate-induced AGT expression in proximal tubular cells.

Indoxyl sulfate inhibits proliferation of human proximal tubular cells via endoplasmic reticulum stress

2010 ◽  
Vol 299 (3) ◽  
pp. F568-F576 ◽  
Author(s):  
Takahisa Kawakami ◽  
Reiko Inagi ◽  
Takehiko Wada ◽  
Tetsuhiro Tanaka ◽  
Toshiro Fujita ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Kinase Inhibitor ◽  
Indoxyl Sulfate ◽  
Uremic Toxin ◽  
Proximal Tubular Cells ◽  
Trypan Blue Exclusion ◽  
Tubular Cells ◽  
Activating Transcription Factor 4 ◽  
Proximal Tubular

Uremic toxins can deteriorate renal function, but little is known about its mechanism. Because tubular injury is central to progression of chronic kidney disease (CKD), we investigated the effects of a representative uremic toxin indoxyl sulfate (IS) on tubular cells. IS induced endoplasmic reticulum (ER) stress in cultured human proximal tubular cells, demonstrated by the increase in C/EBP homologous protein (CHOP) in the immunoblots. Moreover, administration of an oral adsorbent AST-120 reduced serum IS concentration and decreased tubular expression of CHOP in immunohistochemistry in 5/6-nephretomized, CKD model, rats. Furthermore, we disclosed that IS inhibited proliferation of tubular cells in 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium and 5-bromo-2′-deoxyuridine assay, whereas the results of trypan blue exclusion and lactate dehydrogenase assay showed that IS did not promote cell death. This inhibition was mitigated by small interfering (si) RNA against CHOP. Furthermore, IS increased the cyclin-dependent kinase inhibitor p21WAF1/CIP1(p21). Surprisingly, this was mediated by the inflammatory cytokine interleukin (IL)-6, the expression of which was decreased by siRNA against activating transcription factor 4, another ER stress marker; however, the induction of IL-6 and p21 by IS was not suppressed by siRNA targeted to CHOP, suggesting that they were downstream of ER stress, but independent of CHOP. Moreover, we found that their upregulation was dependent on ERK, using the ERK pathway inhibitor U-0126. Collectively, we demonstrated that IS induced ER stress in tubular cells and inhibited cell proliferation via two pathways downstream of ER stress, namely CHOP and ERK-IL-6-p21. These are possible targets for suppressing progression of CKD.

scholarly journals Indoxyl Sulfate Induces Apoptosis and Hypertrophy in Human Kidney Proximal Tubular Cells

2018 ◽  
Vol 46 (4) ◽  
pp. 449-459 ◽  
Author(s):  
Robert J. Ellis ◽  
David M. Small ◽  
Keng Lim Ng ◽  
David A. Vesey ◽  
Luis Vitetta ◽  
...  
Keyword(s):  
Kidney Function ◽  
Transforming Growth Factor ◽  
Primary Cultures ◽  
Human Kidney ◽  
Transforming Growth Factor Β ◽  
Indoxyl Sulfate ◽  
Uremic Toxin ◽  
Proximal Tubular Cells ◽  
Tubular Cells ◽  
Proximal Tubular

Indoxyl sulfate (IS) is a protein-bound uremic toxin that accumulates in patients with declining kidney function. Although generally thought of as a consequence of declining kidney function, emerging evidence demonstrates direct cytotoxic role of IS on endothelial cells and cardiomyocytes, largely through the expression of pro-inflammatory and pro-fibrotic factors. The direct toxicity of IS on human kidney proximal tubular epithelial cells (PTECs) remains a matter of debate. The current study explored the effect of IS on primary cultures of human PTECs and HK-2, an immortalized human PTEC line. Pathologically relevant concentrations of IS induced apoptosis and increased the expression of the proapoptotic molecule Bax in both cell types. IS impaired mitochondrial metabolic activity and induced cellular hypertrophy. Furthermore, statistically significant upregulation of pro-fibrotic (transforming growth factor-β, fibronectin) and pro-inflammatory molecules (interleukin-6, interleukin-8, and tumor necrosis factor-α) in response to IS was observed. Albumin had no influence on the toxicity of IS. The results of this study suggest that IS directly induced a pro-inflammatory and pro-fibrotic phenotype in proximal tubular cells. In light of the associated apoptosis, hypertrophy, and metabolic dysfunction, this study demonstrates that IS may play a role in the progression of chronic kidney disease.

Indoxyl sulfate upregulates renal expression of ICAM-1 via production of ROS and activation of NF-κB and p53 in proximal tubular cells

Life Sciences ◽  
2013 ◽  
Vol 92 (2) ◽  
pp. 143-148 ◽  
Author(s):  
Hidehisa Shimizu ◽  
Maimaiti Yisireyili ◽  
Yukihiro Higashiyama ◽  
Fuyuhiko Nishijima ◽  
Toshimitsu Niwa
Keyword(s):  
Indoxyl Sulfate ◽  
Proximal Tubular Cells ◽  
Tubular Cells ◽  
Proximal Tubular ◽  
Renal Expression

Indoxyl sulfate upregulates renal expression of MCP-1 via production of ROS and activation of NF-κB, p53, ERK, and JNK in proximal tubular cells

Life Sciences ◽  
2012 ◽  
Vol 90 (13-14) ◽  
pp. 525-530 ◽  
Author(s):  
Hidehisa Shimizu ◽  
Dilinaer Bolati ◽  
Yukihiro Higashiyama ◽  
Fuyuhiko Nishijima ◽  
Kazuya Shimizu ◽  
...  
Keyword(s):  
Indoxyl Sulfate ◽  
Proximal Tubular Cells ◽  
Tubular Cells ◽  
Proximal Tubular ◽  
Renal Expression

scholarly journals Indoxyl Sulfate-Induced Activation of (Pro)Renin Receptor Is Involved in Expression of TGF-β1 and α-Smooth Muscle Actin in Proximal Tubular Cells

Endocrinology ◽  
2014 ◽  
Vol 155 (5) ◽  
pp. 1899-1907 ◽  
Author(s):  
Shinichi Saito ◽  
Hidehisa Shimizu ◽  
Maimaiti Yisireyili ◽  
Fuyuhiko Nishijima ◽  
Atsushi Enomoto ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Actin ◽  
Nuclear Factor Κb ◽  
Indoxyl Sulfate ◽  
Muscle Actin ◽  
Proximal Tubular Cells ◽  
Tubular Cells ◽  
Proximal Tubular ◽  
Renal Expression ◽  
Tgf Β1

Activation of (pro)renin receptor (PRR) is involved in the progression of chronic kidney disease. However, the role of indoxyl sulfate, a uremic toxin, in the activation of PRR is not clear. The present study aimed to clarify the role of indoxyl sulfate in activation of PRR, in relation to renal expression of fibrotic genes. Renal expression of PRR and renin/prorenin was up-regulated in chronic kidney disease rats compared with normal rats, whereas AST-120 suppressed these expression by reducing serum levels of indoxyl sulfate. Furthermore, administration of indoxyl sulfate to normotensive and hypertensive rats increased renal expression of PRR and renin/prorenin. Indoxyl sulfate induced expression of PRR and prorenin in cultured human proximal tubular cells (HK-2 cells). Indoxyl sulfate-induced PRR expression was inhibited by small interfering RNAs of signal transducer and activator of transcription 3 (Stat3) and nuclear factor-κB p65 in proximal tubular cells. N-acetylcysteine, an antioxidant, and diphenyleneiodonium, an inhibitor of nicotinamide adenine dinucleotide phosphate oxidase, suppressed indoxyl sulfate-induced PRR expression in proximal tubular cells. N-acetylcysteine prevented indoxyl sulfate-induced phosphorylation of Stat3 in proximal tubular cells. PRR small interfering RNA inhibited indoxyl sulfate-induced expression of TGF-β1 and α-smooth muscle actin in proximal tubular cells. Taken together, indoxyl sulfate-induced up-regulation of prorenin expression and activation of PRR through production of reactive oxygen species and activation of Stat3 and nuclear factor-κB play an important role in the expression of TGF-β1 and α-smooth muscle actin in proximal tubular cells. Thus, indoxyl sulfate-induced activation of prorenin/PRR might be involved in renal fibrosis.

scholarly journals NADPH oxidase inhibition reduces tubular sodium transport and improves kidney oxygenation in diabetes

2012 ◽  
Vol 302 (12) ◽  
pp. R1443-R1449 ◽  
Author(s):  
Patrik Persson ◽  
Peter Hansell ◽  
Fredrik Palm
Keyword(s):  
Nadph Oxidase ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Diabetic Rats ◽  
Filtration Fraction ◽  
Tubular Cells ◽  
Proximal Tubular ◽  
Oxidase Inhibition ◽  
Streptozotocin Diabetic Rats ◽  
Nadph Oxidase Inhibition

Sustained hyperglycemia is associated with increased oxidative stress resulting in decreased intrarenal oxygen tension (Po2) due to increased oxygen consumption (Qo2). Chronic blockade of the main superoxide radicals producing system, the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, normalizes Qo2 by isolated proximal tubular cells (PTC) and reduces proteinuria in diabetes. The aim was to investigate the effects of acute NADPH oxidase inhibition on tubular Na+ transport and kidney Po2 in vivo. Glomerular filtration rate (GFR), renal blood flow (RBF), filtration fraction (FF), Na+ excretion, fractional Li+ excretion, and intrarenal Po2 was measured in control and streptozotocin-diabetic rats during baseline and after acute NADPH oxidase inhibition using apocynin. The effects on tubular transporters were investigated using freshly isolated PTC. GFR was increased in diabetics compared with controls (2.2 ± 0.3 vs. 1.4 ± 0.1 ml·min−1·kidney−1). RBF was similar in both groups, resulting in increased FF in diabetics. Po2 was reduced in cortex and medulla in diabetic kidneys compared with controls (34.4 ± 0.7 vs. 42.5 ± 1.2 mmHg and 15.7 ± 1.2 vs. 25.5 ± 2.3 mmHg, respectively). Na+ excretion was increased in diabetics compared with controls (24.0 ± 4.7 vs. 9.0 ± 2.0 μm·min−1·kidney−1). In controls, all parameters were unaffected. However, apocynin increased Na+ excretion (+112%) and decreased fractional lithium reabsorption (−10%) in diabetics, resulting in improved cortical (+14%) and medullary (+28%) Po2. Qo2 was higher in PTC isolated from diabetic rats compared with control. Apocynin, dimethylamiloride, and ouabain reduced Qo2, but the effects of combining apocynin with either dimethylamiloride or ouabain were not additive. In conclusion, NADPH oxidase inhibition reduces tubular Na+ transport and improves intrarenal Po2 in diabetes.

NF-κB plays an important role in indoxyl sulfate-induced cellular senescence, fibrotic gene expression, and inhibition of proliferation in proximal tubular cells

2011 ◽  
Vol 301 (5) ◽  
pp. C1201-C1212 ◽  
Author(s):  
Hidehisa Shimizu ◽  
Dilinaer Bolati ◽  
Ayinuer Adijiang ◽  
Gulinuer Muteliefu ◽  
Atsushi Enomoto ◽  
...  
Keyword(s):  
Gene Expression ◽  
Promoter Activity ◽  
Indoxyl Sulfate ◽  
Proximal Tubular Cells ◽  
Inhibition Of Proliferation ◽  
P53 Expression ◽  
Transfected Cells ◽  
Tubular Cells ◽  
Proximal Tubular ◽  
Tgf Β1

We previously demonstrated that indoxyl sulfate induces senescence and dysfunction of proximal tubular cells by activating p53 expression. However, little is known about the role of nuclear factor (NF)-κB in these processes. The present study examines whether activation (phosphorylation) of NF-κB by indoxyl sulfate promotes senescence and dysfunction in human proximal tubular cells (HK-2 cells). Indoxyl sulfate induced phosphorylation of NF-κB p65 on Ser-276, which was suppressed by N-acetylcysteine, an antioxidant. Furthermore, indoxyl sulfate induced NF-κB p65 expression. Inhibitors of NF-κB (pyrrolidine dithiocarbamate and isohelenin) and NF-κB p65 small interfering RNA (siRNA) suppressed indoxyl sulfate-induced senescence-associated β-galactosidase activity and expression of p53, transforming growth factor (TGF)-β1, and α-smoothe muscle actin (SMA). The induction of p53 expression and p53 promoter activity by indoxyl sulfate were inhibited by pifithrin-α, p-nitro, an inhibitor of p53, whereas p53-transfected cells showed enhanced p53 promoter activity. NF-κB inhibitors suppressed indoxyl sulfate-induced p21 expression, whereas NF-κB p65 siRNA enhanced its expression. NF-κB inhibitors partially alleviated indoxyl sulfate-induced inhibition of cellular proliferation. NF-κB p65 siRNA-transfected cells showed less proliferation in the presence of indoxyl sulfate than control cells. Phosphorylated NF-κB p65 was expressed and colocalized with p53, p21, β-galactosidase, TGF-β1, and α-SMA in the kidneys of chronic renal failure (CRF) rats. AST-120, which reduces serum indoxyl sulfate level, suppressed their expression in the CRF rat kidneys. Taken together, NF-κB plays an important role in indoxyl sulfate-induced cellular senescence, fibrotic gene expression, and inhibition of proliferation in proximal tubular cells. More notably, indoxyl sulfate accelerates proximal tubular cell senescence with progression of CRF through reactive oxygen species-NF-κB-p53 pathway.

Sign in / Sign up

Export Citation Format

Share Document