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Aim To investigate the effect of sphingo-sine kinase 1 (SphK1 )on unilateral ureteral obstruc-tion(UUO)-induced tubulointerstitial fibrosis and ex-plore the possible mechanism.Methods The CD-1 mice were randomly divided into four groups:sham-op-eration group(Sham),PF-543 treatment control group (Sham +PF-543),model group(UUO)and PF-543 treatment group(UUO +PF-543).On 1 ,3,7 and 1 4 d after operation,eight mice were selected randomly from each group and sacrificed.The protein expressions of SphK1 ,mature TGF-β1 ,FN,ColⅠ,LC3,Beclin1 ,Atg5 and Atg1 2 were observed by Western blot.The histo-logical changes were examined by Masson′s trichrome stain.Immunhistochemistry was performed to measure the levels of expression of SphK1 ,FN and Col Ⅰ. Transmission electron microscope was used to observe the autophagic body.Results SphK1 expression and autophagy were both upregulated in a mouse model of kidney fibrosis induced by UUO. Meanwhile, in-creased mature TGF-β1 and deposition of extracellular matrix(ECM)were observed in tubulointerstitial areas compared with sham-operated mice.After intraperito-neal injection with the SphK1 specific inhibitor PF-543 in UUO mice,enhanced expression of SphK1 and acti-vated autophagy were significantly abrogated.Howev-er,aggravation of renal fibrosis was detected when SphK1 inhibitor PF-543 was applied to suppress SphK1 expression in UUO mice.Conclusion SphK1 activa-tion is renoprotective through the induction of autoph-agy in the pathogenesis of kidney fibrosis.
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Aim To investigate the effects of high glu-cose on cholesterol metabolism in renal tubular cells and the intervention of the anthocyanins. Methods HK-2 cells were grown in the DMEM medium supple-mented with 10% FBS and were divided into 5 groups:normal glucose group, high glucose group, mannitol group, C3G group and Cy group. Effect of anthocya-nins on cell viability was detected with MTT, and cho-lesterol accumulation was detected with Amplex Red Cholesterol Assay kit and Filipin staining. Expression of ABCA1 was detected with RT-qPCR and Western Blot. Results In compared with control groups, HG significantly promoted cholesterol mass inside the cell and decreased the cholesterol concentration in the me-dium after treatment for 24 h or 48 h. The levels of mRNA and protein of ABCA1 were detected with RT-qPCR and Western blot, and both were decreased in the presence of HG. Whereas treatment with C3G and Cy markedly attenuated HG-induced cholesterol mass inside the cell by up-regulating the expression of AB-CA1. Conclusions High glucose can reduce the ex-pressions of the ABCA1, and then decrease cholesterol efflux and increase the cholesterol accumulation in HK-2 cells. Anthocyanins can decrease cholesterol accu-mulation by up-regulating the expression of ABCA1.
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Objective To observe the effects of uric acid (UA) on mitochondrial oxidative damage and apoptosis in renal tubular epithelial cells (HK-2),and investigate the possible mechanism.Methods HK-2 cells were exposed to UA (480 μmol/L,720 μmol/L) for different time (0 h,24 h,48 h)in vitro.The mitochondrial ROS production was detected by MitoSOX staining.The mitochondrial membrane potential was measured by JC-1 staining.The expressions of prohibitin and AIF were examined by Western blotting and irnmunofluorescence cytochemistry.The cell apoptosis was measured by Annexin V-FITC/PI staining.Results The mitochondrial ROS production in HK-2 cells exposed to 480 μ mol/L UA was increased than that of control group at 24 h (P ＜ 0.05),and increased gradually with UA concentration and incubation time increasing,while the mitochondrial membrane potential was reduced at the same time.There were no significant changes in AIF expression and apoptosis rate of HK -2 cells exposed to 480 μmol/L UA for 24 h compared with that of control group (P ＞ 0.05),while both of them were up-regulated when HK-2 cells were exposed to 480 μmol/L UA for 48 h and 720 μmol/L JA for 24 h and 48 h (P ＜ 0.05).The prohibitin expression in HK-2 cells exposed to 480 μmol/L UA was reduced than that of control group at 24 h (P ＜ 0.05),and down-regulated gradually with UA concentration and incubation time increasing.Conclusion Uric acid can induce the mitochondrial ROS production increased,the mitochondrial membrane potential reduced,the prohibitin expression down-regulated and the mitochondrial apoptosis pathway activated in HK-2 cells.
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Aim To investigate the effects of suppressor of cytokine signaling-1(SOCS-1)on advanced glycation end products(AGEs)induced-renal tubular epithelial-myofibroblast transdifferentiation and activation of JAK/STAT in cultured human renal tubular epithelial cells(HKC).Methods Stable transfections of HKC with pCR3.1 vector and pCR3.1/SOCS-1 were performed with Lipofectamine 2000,and cells were selected with geneticin.Cells were stimulated with BSA and AGEs. The protein expressions of SOCS-1,α-SMA,E-cadherin,Col I,signal transducer and activatior of transcription 1,3(STAT1,STAT3),p-STAT1 and p-STAT3 were observed by Western blot.The protein synthesis of TGF-β_1 in the supernatants of the HKC was detected by enzyme-linked immunoadsorbent assay(ELISA).α-SMA and E-cadherin mRNA were measured by reverse transcription and polymerase chain reaction(RT-PCR).Results Compared with control group,the expression levels of α-SMA protein and mRNA and Col I were significantly increased in HKC with AGEs stimulation and there was a higher concentrations of TGF-β_1 in the supernatants.However,the expression of E-cadherin protein and mRNA were decreased with AGEs stimulation.Overexpression of SOCS-1 inhibited AGEs-induced activation of STAT1 and STAT3 and high expression of α-SMA protein and mRNA and Col I,and reversed the expression of E-cadherin protein and mRNA induced by AGEs.Meanwhile,overexpression of SOCS-1 reduced the concentration of TGF-β_1 in the supernatants of HKC with AGEs stimulation.Conclusion Overexpression of SOCS-1 inhibits AGEs-induced renal tubular epithelial-myofibroblast transdifferentiation maybe partly through blocking activation of JAK/STAT.
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Objective To investigate the effect of suppressor of cytokine signaling-1 (SOCS-1)on expression of monocyte chemoattractant protein-1 (MCP-1)in human glomerular mesangial cells (HMCs) under high concentration of glucose. Methods Stable transfections of HMC with pCR3.1 vector and pCR3. 1-SOCS-1 were performed with hpofectamine 2000, and cells were selected with geneticin. Cells were stimulated with low glucose (LG, 5.5 mmol/L), high glucose (HG, 30 mmol/L), LG plus mannitol (24.5 mmol/L) and AG490 (10 μmol/L). The protein expression levels of SOCS-1, signal transducer and activators of transcription 1,3 (STAT1, STAT3),p-STAT1 and p-STAT3 were observed by Western blotting. The protein synthesis of MCP-1, FN and type Ⅳ collagen in the supernatants of the HMCs were detected by ELISA and radioimmunoassay. The expression level of SOCS-1 and MCP-1 mRNA was measured by BT-PCR.Results HG induced the expression of SOCS-1 protein and mRNA in HMCs in time-dependant manner, peaked at 4 h, and gradually decreased to baseline at 24 h. Compared with low glucose control group, the phosphorylation levels of STAT1 and STAT3 and the expression of MCP-1 mRNA [(0.39±0.05) vs (0.16±0.02)]were significantly increased in HMCs under high glucose medium (P ＜0.01 ). Exposure of HMCs to high glucose conditions showed high concentration of MCP-1 [(459±67) ng/L vs (241±19) ng/L], fibronectin [(5.84±0.61) mg/L vs (3.41±0.31) mg/L]and type Ⅳ collagen [(16.45±2.30) μg/L vs (9.56±1.52) μg/L]in the supernatants (all P＜0.01).Overexpression of SOCS-1 inhibited the phosphorylation levels of STAT1 and STAT3 and the expression of MCP-1 mRNA [(0.34±0.04) vs (0.42±0.05)]in HMCs under high glucose condition (all P＜0.05). Compared with vector control group, the concentration of MCP-1 [(387±47) ng/L vs (463±56) ng/L], fibronectin [(4.61±0.57) mg/L vs (5.76±0.74) mg/L]and type Ⅳ collagen [(13.4±2.32) μg/L vs (17.1±2.57) μg/L]was decreased in supernatants of HMCs with SOCS-1 overexpression (all P＜0.05). Compared with HG group, the expression of MCP-1 mRNA (0.31±0.04) and the concentration of MCP-1 [(361±53) ng/L], FN [(5.46±0.71) mg/L]and type Ⅳ collagen [(15.2±1.97) μg/L]in supernatants were decreased in HMCs treated with AG490.Conclusion Overexpression of SOCS-1 inhibits overproduction of MCP-1 and ECM proteins in HMCs under high glucose conditions, which may be partly by regulating the phosphoryhtion of STAT1 and STAT3.
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Objective To examine the expression of TGF-?1/Smads signaling pathway in renal tubulointerstitial fibrosis.Methods Male SD rats were divided into control,sham operation and tubulointerstitial fibrosis groups.They were sacrificed at day 3,7,14,28 after operation.Use masson coloration to examine the area of pathological changes.The level of TGF?1,p-Smad2/3 and smad7 protein was examined by immunohistochemistry staining and Western blot.The level of TGF-?1 mRNA and smad7 mRNA was analyzed by RTPCR.Results Compared with sham operation group,TGF-?1 and p-Smad2/3 were significantly increased in UUO rats,while smad7 protein reduced in it.The mRNA of TGF-?1 and smad 7 increased from day 3 to day 28.Smads protein plays an important role in the synthesis and accumulation of extracellular matrix in tubulointerstitial area.The reduction of smad 7 protein may be a major cause of the interstitial fibrosis in this model.Conclusion TGF-? /Smads protein pathway perhaps is essential in the development of tubulointerstitial fibrosis.
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Aim To investigate the effects of fluvastatin on epithelial-myofibroblast transdifferentiation and activation of ERK1/2 in HKC cells stimulated by AGEs. Methods HKC are divided into four groups: control group, AGEs group, AGEs plus fluvastatin group and AGEs plus ERK1/2 MAP kinase inhibitor PD98059 group. Immunocytochemistry staining was used to detect expression of ?-SMA. The protein expressions of ?-SMA, E-cadherin, Col I, ERK1/2 and p-ERK1/2 were observed by Western blot. The protein synthesis of TGF-?1 in the supernatants of the HKC was detected by enzyme-linked immunoadsorbent assay (ELISA).?-SMA and E-cadherin mRNA were measured by reverse transcription and polymerase chain reaction (RT-PCR). Results Compared with those of control group,the expressions of ?-SMA protein and mRNA,and Col I were significantly increased in HKC cells with AGEs stimulation and there was high concentration of TGF-?1 in the supernatants. However, the expressions of E-cadherin protein and mRNA were decreased with AGEs stimulation. AGEs induced ERK1/2 phosphorylation in HKC in a time-dependent manner, being significant at 15 minutes and peak occured at 1 h. PD98059 and fluvastatin inhibited AGEs-induced activation of ERK1/2 and high expression of Col I and ?-SMA protein and mRNA, and reversed the expression of E-cadherin protein and mRNA induced by AGEs. Meanwhile, fluvastatin and PD98059 reduced the concentration of TGF-?1 in the supernatants of HKC with AGEs stimulation. Conclusions Fluvastatin inhibited AGEs-induced HKC epithelial-myofibroblast transdifferentiation and collagen I synthesis might be partly through blocking activation of ERK1/2.
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Aim To observe the effect of valsartan on expression of Smads of HKCs stimulated by TGF-?1.Methods HKCs were divided into three groups:control group,TGF-?1 group and valsartan group.Total protein was firstly abstracted at 30 min after stimulation to detect p-Smad2/3 protein by Western blot.Total RNA and protein were abstracted at 48 hours after stimulation.The expressions of Smad2/3,Smad7 were measured by Western blot.Smad2mRNA and Smad7mRNA were measured by RT-PCR.Meanwhile, The protein synthesis of Col Ⅰ in the supernatants of the HKCs was detected by Western blot.MTT assay was used to investigate the effect of valsartan on proliferation of HKCs stimulated by 5 ?g?L-1 TGF-?1 at different time and different drug concentration.Results Western blot analysis indicated that TGF-?1 stimulation could increase the expression of Smad2/3 and activate phosphorylation of Smad2/3 at 48 hour.At the same time,Smad7 decreased.Valsartan could reduce the level of Smad2/3 and p-Smad2/3 but it did not have any effect on the expression of Smad7 protein.RT-PCR analysis also showed that the expression of Smad2mRNA or Smad7mRNA was higher after TGF-?1 stimulation than control group,while valsartan could down-regulate the expression of Smad2mRNA.There was no difference of the expression of Smad7mRNA between the TGF-?1 stimulation group and valsartan treatment group.Valsartan could also greatly ameliorate the secretion of Col Ⅰ in the supernatants of the HKCs stimulated by TGF-?1 detected by Western blot.Compared with control group,TGF-?1 supressed the proliferation of HKCs,While 1,10 and 100 ?mol?L-1 valsartan ameliorated it and the effect was dependent of dose.Conclusion Valsartan has some renal protective effects on renal interstitial fibrosis,partly through inhibiting TGF-?/Smads signaling pathway.
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Aim To construct eukaryotic expression vector of shRNA(small hairpin RNA)for human SREBP-1(sterol regulation element binding protein-1)gene and explore its effects on lipid droplet formation in human renal proximal tubular epithelial cell line(HKC)under the stimulation of high glucose.Methods Two eukaryotic expression vectors of shRNA were constructed for human SREBP-1 gene.The HKC cells were transfected with negative control plasmid(pGenesil-1-HK)and two recombinant vectors(pGenesil-1-SREBP1-1 and pGenesil-1-SREBP1-2)and then were cultured under the stimulation of high glucose for about 48 h.The expression of SREBP-1 mRNA and FAS mRNA was detected by RT-PCR and SREBP-1 protein expression was investigated by Western blot.Lipid droplets were detected by Oil Red O staining.Results DNA sequencing showed that the target segments were successfully cloned into pGenesil-1 vector respectively.RT-PCR indicated that two recombinant vectors could inhibit the expression of SREBP-1 mRNA and FAS mRNA in HKC cells under the stimulation of high glucose.Similarly,SREBP-1 protein was also inhibited by the transfection with recombinant vectors.Oil Red O staining found that silencing of SREBP-1 gene resulted in lipid droplets decrease.Conclusions The eukaryotic expression vector of shRNA for human SREBP-1 gene was successfully constructed,and the expression of SREBP-1 was inhibited effectively by the expressed siRNA in HKC cells that resulted in lipid droplets decrease through FAS mRNA transcription inhibition.
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Aim To investigate the effects of valsartan on activation of signal transducers and activators of transcription 1,3 in glomerular mesangial cells(GMCs) under high concentration of glucose.Methods we used high concentration glucose and valsartan to stimulate the cultured rat GMCs in vitro.The protein expressions of signal transducer and activatior of transcription 1,3(STAT1,STAT3),p-STAT1 and p-STAT3 were observed by Western blot.The protein synthesis of TGF-?_1,fibronectin and type IV collagen in the supernatants of the GMCs were detected by enzyme-linked immunoadsorbent assay(ELISA) and radioimmunoassay.TGF-?_1 mRNA was measured by reverse transcription and polymerase chain reaction(RT-PCR).Results Compared with low glucose control group,the expressions of p-STAT1,p-STAT3 and TGF?_1 mRNA were significantly increased in GMCs under high concentration glucose medium and there observed the high concentration of TGF-?_1,fibronectin and type IV collagen in the supernatants.The expression levels of p-STAT1,p-STAT3 and TGF-?_1 mRNA were significantly lower in the valsartan group than in those the high concentration glucose group.The concentration of TGF-?_1,fibronectin and type IV collagen in the supernatants in the valsartan group were lower than that in the high concentration glucose control group.Conclusion Valsartan can inhibit overproduction of TGF-?_1 and ECM proteins in GMCs under high concentration of glucose,partly by regulating the phosphorylation of STAT1 and STAT3.