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 ◽  
...  
Life Sciences ◽  
2013 ◽  
Vol 92 (2) ◽  
pp. 143-148 ◽  
Author(s):  
Hidehisa Shimizu ◽  
Maimaiti Yisireyili ◽  
Yukihiro Higashiyama ◽  
Fuyuhiko Nishijima ◽  
Toshimitsu Niwa

Endocrinology ◽  
2014 ◽  
Vol 155 (5) ◽  
pp. 1899-1907 ◽  
Author(s):  
Shinichi Saito ◽  
Hidehisa Shimizu ◽  
Maimaiti Yisireyili ◽  
Fuyuhiko Nishijima ◽  
Atsushi Enomoto ◽  
...  

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.


2013 ◽  
Vol 304 (7) ◽  
pp. C685-C692 ◽  
Author(s):  
Hidehisa Shimizu ◽  
Shinichi Saito ◽  
Yukihiro Higashiyama ◽  
Fuyuhiko Nishijima ◽  
Toshimitsu Niwa

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.


2001 ◽  
Vol 12 (11) ◽  
pp. 2392-2399 ◽  
Author(s):  
SHI-NONG WANG ◽  
JANINE LAPAGE ◽  
RAIMUND HIRSCHBERG

Abstract. Bone morphogenetic protein—7 (BMP7), a member of the transforming growth factor—β (TGF—β) superfamily of cytokines, is highly expressed in renal tubules and generally promotes maintenance of epithelial phenotype. It was examined whether, during the evolution of experimental diabetic nephropathy, the renal expression of BMP7 and BMP7 receptors declines, and the hypothesis that loss of BMP7 activity is profibrogenic in proximal tubular cells was tested. Moreover,in vitrostudies in cultured proximal tubular cells were performed to examine putative mechanisms that cause these changes. At 15 wk of streptozotocin-induced diabetes, renal expression of BMP7 is declined by about half, and it decreased further by 30 wk to <10% of timed controls. Renal expression of the high-affinity BMP type II receptor and the type I receptor Alk2 (activin receptor—like kinase-2) decreased. Alk3 tended to decrease, but Alk6 remained unchanged. During the evolution of diabetic nephropathy, the secreted BMP antagonist gremlin increased substantially. In cultured tubular cells, TGF-β reduced BMP7 and Alk3 expression and increased gremlin but did not interrupt BMP7-induced activation of smad5 or Erk1 and -2. In contrast, BMP7 did not alter TGF-β expression. Neutralization of endogenous BMP7 in cultured proximal tubular cells raised the expression of fibronectin and tended to increase collagen α1III mRNA levels. In conclusion, in experimental diabetic nephropathy, renal tubular BMP7 and some of its receptors decreased and gremlin, a secreted BMP antagonist, increased. Some, but not all, of these changes are explained by increased TGF-β. The loss of BMP7 activityper seis profibrogenic in tubular cells.


2011 ◽  
Vol 301 (5) ◽  
pp. C1201-C1212 ◽  
Author(s):  
Hidehisa Shimizu ◽  
Dilinaer Bolati ◽  
Ayinuer Adijiang ◽  
Gulinuer Muteliefu ◽  
Atsushi Enomoto ◽  
...  

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.


2013 ◽  
Vol 37 (2) ◽  
pp. 97-103 ◽  
Author(s):  
Hidehisa Shimizu ◽  
Maimaiti Yisireyili ◽  
Fuyuhiko Nishijima ◽  
Toshimitsu Niwa

2010 ◽  
Vol 299 (3) ◽  
pp. F568-F576 ◽  
Author(s):  
Takahisa Kawakami ◽  
Reiko Inagi ◽  
Takehiko Wada ◽  
Tetsuhiro Tanaka ◽  
Toshiro Fujita ◽  
...  

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.


PLoS ONE ◽  
2014 ◽  
Vol 9 (3) ◽  
pp. e91517 ◽  
Author(s):  
Hwee-Yeong Ng ◽  
Maimaiti Yisireyili ◽  
Shinichi Saito ◽  
Chien-Te Lee ◽  
Yelixiati Adelibieke ◽  
...  

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