We investigated the protective effects of electromagnetic field (EMF) on the survival of the human renal proximal tubular cell line, HK-2, using an in vitro hypoxia/reoxygenation (H/R) injury model. The survival rate of cells cultured under H/R condition declined significantly, while the intracellular reactive oxygen species (ROS) levels markedly increased. The 10 Hz/1 mT EMF exposure reversed the H/R induced reduction in cell survival and induction of intracellular ROS. Our results suggest that 10 Hz/1 mT EMF exposure could inhibit H/R-induced cell death of HK-2 via suppression of intracellular ROS production and that this treatment might be clinically useful for the amelioration of renal ischemia/reperfusion injury.
Cell Hypoxia ; Cell Line ; Electromagnetic Fields ; Humans ; Kidney Tubules, Proximal ; cytology ; metabolism ; radiation effects ; Reactive Oxygen Species ; metabolism ; Reperfusion Injury ; prevention & control

The expression of hypoxia-inducible factor (HIF) is influenced by reactive oxygen species (ROS). Effect of bilirubin on HIF-1 expression in proximal tubular cells was investigated under physiological oxygen concentration, which is relative hypoxic condition mimicking oxygen content in the medulla of renal tissue. The human kidney (HK2) cells were cultured in 5% oxygen with or without bilirubin. HIF-1alpha protein expression was increased by bilirubin treatment at 0.01-0.2 mg/dL concentration. The messenger RNA expression of HIF-1alpha was increased by 1.69+/-0.05 folds in the cells cultured with 0.1 mg/dL bilirubin, compared to the control cells. The inhibitors of PI3K/mTOR, PI3K/AKT, and ERK 1/2 pathways did not attenuate increased HIF-1alpha expression by bilirubin. HIF-1alpha expression decreased by 10 microM exogenous hydrogen peroxide (H2O2); scavenger of ROS with or without bilirubin in the HK2 cells increased HIF-1alpha concentration more than that in the cells without bilirubin. Exogenous H2O2 decreased the phosphorylation of P70S6 kinase, which was completely reversed by bilirubin treatment. Knockdown of NOX4 gene by small interfering RNA (siRNA) increased HIF-1alpha mRNA expression. In coonclusion, bilirubin enhances HIF-1alpha transcription as well as the up-regulation of HIF-1alpha protein translation through the attenuation of ROS and subunits of NADPH oxidase.
Bilirubin/*pharmacology ; Cell Line ; Epithelial Cells/cytology/metabolism ; Humans ; Hydrogen Peroxide/toxicity ; Hypoxia-Inducible Factor 1, alpha Subunit/genetics/*metabolism ; Kidney Tubules, Proximal/cytology ; Mitogen-Activated Protein Kinase 1/metabolism ; Mitogen-Activated Protein Kinase 3/metabolism ; NADPH Oxidase/antagonists & inhibitors/genetics/metabolism ; Oxygen/*pharmacology ; Phosphatidylinositol 3-Kinases/metabolism ; Phosphorylation/drug effects ; Proto-Oncogene Proteins c-akt/metabolism ; RNA Interference ; Ribosomal Protein S6 Kinases, 70-kDa/metabolism ; Signal Transduction/drug effects ; TOR Serine-Threonine Kinases/metabolism ; Transcriptional Activation/*drug effects ; Up-Regulation/drug effects

We evaluated the effect of cobalt chloride (CoCl2) on TNF-alpha and IFN-gamma-induced-inflammation and reactive oxygen species (ROS) in renal tubular epithelial cells (HK-2 cells). We treated HK-2 cells with CoCl2 before the administration of TNF-alpha/IFN-gamma. To regulate hemeoxygenase-1 (HO-1) expression, the cells were treated CoCl2 or HO-1 siRNA. CoCl2 reduced the generation of ROS induced by TNF-alpha/IFN-gamma. TNF-alpha/IFN-gamma-treated-cells showed an increase in the nuclear translocation of phosphorylated NF-kappaBp65 protein, the DNA-binding activity of NF-kappaBp50 and NF-kappaB transcriptional activity and a decrease in IkappaBalpha protein expression. These changes were restored by CoCl2. We noted an intense increase in monocyte chemoattractant protein-1 (MCP-1) and regulated on activation normal T cell expressed and secreted (RANTES) production in TNF-alpha/IFN-gamma-treated cells. We demonstrated that this effect was mediated through NF-kappaB signaling because an NF-kappaB inhibitor significantly reduced MCP-1 and RANTES production. CoCl2 effectively reduced MCP-1 and RANTES production. The expression of HO-1 was increased by CoCl2 and decreased by HO-1 siRNA. However, knockdown of HO-1 by RNA interference did not affect MCP-1 or RANTES production. We suggest that CoCl2 has a protective effect on TNF-alpha/IFN-gamma-induced inflammation through the inhibition of NF-kappaB and ROS in HK-2 cells. However, CoCl2 appears to act in an HO-1-independent manner.
Cell Line ; Chemokine CCL2/metabolism ; Chemokine CCL5/metabolism ; Cobalt/*pharmacology ; Epithelial Cells/cytology/metabolism ; Heme Oxygenase-1/antagonists & inhibitors/genetics/metabolism ; Humans ; *Inflammation ; Interferon-gamma/pharmacology ; Kidney Tubules, Proximal/cytology ; NF-kappa B/antagonists & inhibitors/genetics/*metabolism ; NF-kappa B p50 Subunit/genetics/metabolism ; Oxidative Stress/*drug effects ; Phosphorylation ; Protein Binding ; RNA Interference ; RNA, Small Interfering/metabolism ; Transcription Factor RelA/metabolism ; Tumor Necrosis Factor-alpha/pharmacology

BACKGROUNDSurfactant protein A (SP-A) contributes to the regulation of sepsis-induced acute lung injury. In a previous study, we demonstrated the expression and localization of SP-A in the kidneys. The present study evaluated the effect of SP-A on lipopolysaccharide (LPS)-induced tumor necrosis factor-a (TNF-α) expression and its underlying mechanisms in the human renal tubular epithelial (HK-2) cells.

METHODSIndirect immunofluorescence assay was used to detect SP-A distribution and expression in HK-2 cells. HK-2 cells were treated with various concentrations of LPS (0, 0.1, 1, 2, 5, and 10 mg/L) for 8 hours and with 5 mg/L LPS for different times (0, 2, 4, 8, 16, and 24 hours) to determine the effects of LPS on SP-A and TNF-α expression. Then, HK-2 cells were transfected with SP-A siRNA to analyze nuclear factor κB (NF-κB) P65 and TNF-α expression of HK-2 cells after LPS-treatment.

RESULTSIndirect immunofluorescence assay revealed that SP-A is localized to the membrane and cytoplasm of HK-2 cells. Interestingly, SP-A1/SP-A2 and TNF-a expression were found to be significantly increased in HK-2 cells upon LPS treatment. Transfection of LPS-treated HK-2 cells with SP-A siRNA resulted in significant increases in the levels of NF-κB P65 protein and TNF-α mRNA and protein compared to those in non-transfected LPS-treated HK-2 cells.

CONCLUSIONSP-A plays an important role in protecting cells against sepsis-induced acute kidney injury by inhibiting NF-κB activity to modulate LPS-induced increase in TNF-α expression.

Cell Line ; Epithelial Cells ; cytology ; drug effects ; metabolism ; Fluorescent Antibody Technique, Indirect ; Humans ; Kidney Tubules, Proximal ; cytology ; Lipopolysaccharides ; pharmacology ; Pulmonary Surfactant-Associated Protein A ; metabolism ; pharmacology ; Tumor Necrosis Factor-alpha ; metabolism

OBJECTIVETo investigate the role of tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) in regulating both angiogenesis and the expressions of phosphatase and tensin homologue deleted on chromosome 10 (PTEN) and vascular endothelial growth factor (VEGF)/Flk-1 expression in human proximal tubular epithelial cells (HKC).

METHODSHKC cells were transfected with two recombinant plasmids containing sense and antisense full-length TIMP-1 cDNA (TIMP-1S-pcDNA3.0 and TIMP-1AS-pcDNA3.0, respectively) constructed previously, or treated with 100 µmol/L MMP-2/MMP-9 inhibitor III (with similar cellular enzyme suppression activity with sense TIMP-1 plasmid). The mRNA expression of TIMP-1, MMP-2, MMP-9, PTEN, VEGF and Flk-1 were examined by RT-PCR. In each group, the expression of PTEN, VEGF and Flk-1 were also detected using an indirect immunofluorescence assay.

RESULTSCompared with non-transfected cells and cells transfected with the empty vector, sense TIMP-1-transfected cells showed obviously upregulated PTEN expression (P<0.05) and significantly lowered gelatinase activity (P<0.05) and VEGF and Flk-1 expressions (P<0.05). Transfection with the antisense TIMP-1 plasmid produced the reverse results (P<0.05). MMP-2/MMP-9 inhibitor III did not obviously affected the expression of PTEN, VEGF or Flk-1 as compared with the non-transfected or empty vector-transfected cells.

CONCLUSIONIn the aging progress, the renal tissues express high levels of TIMP-1 to upregulate PTEN expression via a MMP-independent pathway, and subsequently down-regulates the expression of VEGF and Flk-1 to cause aging-related impairment of renal angiogenesis. These findings provide new evidence for understanding the role of TIMP-1 in renal aging.

Cells, Cultured ; Epithelial Cells ; metabolism ; Humans ; Kidney Tubules, Proximal ; cytology ; Matrix Metalloproteinase Inhibitors ; PTEN Phosphohydrolase ; metabolism ; RNA, Messenger ; genetics ; Tissue Inhibitor of Metalloproteinase-1 ; genetics ; metabolism ; Transfection ; Vascular Endothelial Growth Factor A ; metabolism ; Vascular Endothelial Growth Factor Receptor-2 ; metabolism

OBJECTIVETo study effects of Yishen Kangxian Compound (YKC) and benazepril containing serums on HK-2 cells (human renal proximal tubule epithelial cells) in the process of renal tubular epithelial cells to mesenchymal myofibroblasts transdifferentiation (TEMT) by gene chip.

METHODSYKC and benazepril containing serums were prepared. Their inhibitory effects on HK-2 cells in the transforming growth factor-beta1 (TGF-beta1)-induced TEMT process were observed. HK-2 cells were randomly divided into four groups, i.e., the blank control group, the model group, the benazepril group, and the YKC group. The gross RNAs were extracted and purified by taking advantage of the HumanHT-12 v4 of IlluminaBeadChip. Differentially expressed genes were obtained after they were reversely transcribed to cDNA, incorporating biotin labeling probe, hybridized with GeneChip, picture signals of fluorescence in gene array scanned and compared with differential genes by computer analysis.

RESULTSDifferentially expressed genes were successfully identified by gene chip. Compared with the model group, there were 227 differentially expressed genes in the benazepril group, including 118 up-regulated genes and 109 downregulated genes. Compared with the model group, there were 97 differentially expressed genes in the YKC group, including 69 up-regulated genes and 28 down-regulated genes. The Gene Ontology (GO) analysis indicated that YKC was more actively involved in the regulatory process than benazepril in terms of cell damage, apoptosis, growth, NF-KB, protein kinase, neuron, and blood vessel growth.

CONCLUSIONSYKC and benazepril could inhibit the TEMT process of HK-2 cells. But YKC also had taken part in cell damage, apoptosis, growth,and more pathways of early stage TEMT.

Cell Line ; Cell Transdifferentiation ; drug effects ; Drugs, Chinese Herbal ; pharmacology ; Epithelial Cells ; cytology ; drug effects ; Genomics ; Humans ; Kidney Tubules, Proximal ; cytology ; pathology

Erbin, a member of Leucine-rich repeat and PDZ-containing protein family, was found to inhibit TGF-β-induced epithelial-mesenchymal transition (EMT) in our previous study. However, the mechanism of Erbin in regulating EMT is unclear. Semaphorin protein Sema4C, with PDZ binding site at C-terminal has been recognized as a positive regulator of EMT. Here, we aimed to examine the interaction between Erbin and Sema4C. HK2 cells were treated with TGF-β1, or transfected with Erbin and (or) Sema4C. Interaction of Erbin and Sema4C was identified by immunoprecipitation. RT-PCR was used to detect the expression of Erbin and Sema4C at mRNA level after transfection. The expression levels of Erbin, Sema4C, and markers of EMT were measured by using Western blotting or ELISA. After HK2 cells were stimulated with 10 ng/mL TGF-β1 for 72 h, the protein expression levels of Erbin and Sema4C were both up-regulated, and immunoprecipitation results showed Erbin interacted with Sema4C in HK2 cells both at endogenous and exogenous levels. Furthermore, overexpression of Sema4C suppressed E-cadherin, induced vimentin and promoted fibronectin secretion, indicating Sema4C promotes the process of EMT. However, HK2 cells overexpressing Erbin were resistant to Sema4C-induced EMT. In contrast, Erbin specific siRNA promoted EMT induced by Sema4C. Taken together, these results suggest that Erbin can interact with Sema4C, and co-expression of Erbin blocks the process of Sema4C-induced EMT.
Adaptor Proteins, Signal Transducing ; genetics ; metabolism ; Blotting, Western ; Cadherins ; metabolism ; Cell Line ; Epithelial-Mesenchymal Transition ; Humans ; Immunoprecipitation ; Kidney Tubules, Proximal ; cytology ; drug effects ; metabolism ; Protein Binding ; RNA Interference ; Reverse Transcriptase Polymerase Chain Reaction ; Semaphorins ; genetics ; metabolism ; Transfection ; Transforming Growth Factor beta1 ; pharmacology ; Vimentin ; metabolism

OBJECTIVETo observe the expressions of Wnt/beta-catenin and the effects of tanshinone IIA (TII A) on Wnt/beta-catenin signaling pathway in high glucose induced renal tubular epithelial cell transdifferentiation.

METHODSHuman kidney proximal tubular epithelial cells (HK-2) were divided into three groups, i. e., the normal glucose group, the high glucose group, and the high glucose plus tanshinone IIA group. The expression of beta-catenin was observed using immunocytochemical staining. The protein expression of beta-catenin, E-cadherin, and alpha-smooth muscle actin (alpha-SMA) were detected by Western blot. The mRNA levels of beta-catenin and E-cadherin were detected by RT-PCR.

RESULTSCompared with the normal glucose group, both the protein and the mRNA expressions of beta-catenin were significantly enhanced (P < 0.01), the expression of E-cadherin significantly decreased (P < 0.01), the expression of beta-catenin increased in the cytoplasm and nucleus in the high glucose group. TIIA at the final concentration of 100 micromol/L significantly reduced the ectopic expression of beta-catenin. At that concentration, the protein and mRNA expressions of beta-catenin in the nucleus significantly decreased, while the protein and mRNA expressions of E-cadherin were up-regulated. Meanwhile, the expression of alpha-SMA obviously decreased.

CONCLUSIONSWnt/beta-catenin signaling pathway participated in the high glucose induced renal tubular epithelial cell transdifferentiation. TIIA inhibited the transdifferentiation process possibly through down-regulating the activities of Wnt/beta-catenin signaling pathway, thus further playing a role in renal protection.

Cadherins ; metabolism ; Cell Line ; Cell Transdifferentiation ; drug effects ; Diterpenes, Abietane ; pharmacology ; Epithelial Cells ; cytology ; drug effects ; metabolism ; Glucose ; adverse effects ; Humans ; Kidney Tubules, Proximal ; cytology ; drug effects ; metabolism ; Wnt Signaling Pathway ; drug effects ; beta Catenin ; metabolism

OBJECTIVETo explore the different expression of proteins between human clear-cell renal cell carcinoma (ccRCC) cell line RLC-310 and normal renal proximal tubule epithelial cell line HK-2, and to search new differentially expressed proteins of RCC.

METHODSRLC-310 and HK-2 cells were cultured in vitro. The total proteins were separated by ProteomeLab PF 2D protein fractionation system and the differential expression protein fractions of the two cell lines were analyzed and identified by capillary liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS/MS). RT-PCR and Western blot were used to confirm the representative differential expression at mRNA and protein levels.

RESULTSOne hundred and ninty-six differentially expressed proteins were identified. These differentially expressed proteins involved in many aspects, including cell proliferation and anti-apoptosis, energy metabolism, mitochondria reduction and oxidation, oxidative stress and resistance, cell signaling, invasion and adhesion, cytoskeleton and motion, neovascularization, etc. Except for previously reported RCC associated proteins: annexin A2, fatty acid-binding protein, vimentin, fibronectin, and so on, Septin-9 was firstly found highly expressed in RLC-310 cells when compared with that in the HK-2 cells. Moreover, the overexpression of Septin-9 was confirmed by RT-PCR and Western blot analysis at both mRNA and protein levels (P < 0.05).

CONCLUSIONSThe human ccRCC cell line RLC-310 cells display differential protein profiles compared with those of the normal renal cell line HK-2 cells. The identified differential expression proteins are involved in many aspects of RCC development. It is worth further study and elucidate the molecular mechanisms of RCC. The representative differential protein Septin-9 deserves further study its role in the angiogenesis of ccRCC.

Carcinoma, Renal Cell ; metabolism ; pathology ; Cell Line ; Cell Line, Tumor ; Epithelial Cells ; cytology ; metabolism ; Gene Expression Profiling ; Gene Expression Regulation, Neoplastic ; Humans ; Kidney Neoplasms ; metabolism ; pathology ; Kidney Tubules, Proximal ; cytology ; Proteomics ; methods ; RNA, Messenger ; metabolism ; Septins ; genetics ; metabolism

This study is to investigate the protection effect of schisandrin B (Sch B) against oxidation stress of HK-2 cells induced by cisplatin and the mechanisms involved. HK-2 cells were cultured and divided into different groups: solvent control group, cisplatin exposure group, positive group, Sch B treatment group. Cell viability and toxicity were evaluated by MTT and LDH assay. GSH level and SOD enzymes activities were also measured. DCFH-DA as fluorescence probe was used to detect ROS level by fluorescence microplate reader. Nrf2 translocation was detected by Western blotting. Real time Q-PCR was used to detect expressions of NQO1, HO-1 and GCLC mRNA level. The results showed that Sch B could significantly inhibit the decline of cell viability induced by cisplatin treatment (P < 0.05) and the protective effect was in a dose dependent manner. Furthermore, Sch B treatment significantly inhibited the increase of ROS level induced by cisplatin and reversed the decrease of GSH level (P < 0.05). When Sch B concentration was up to 5 micromol x L(-1), SOD enzyme activities were also enhanced significantly compared with that of the cisplatin group (P < 0.05). It was shown that Sch B could cause nuclear accumulation of Nrf2 in association with downstream activation of Nrf2 mediated oxidative response genes such as GCLC, NQO1 and HO-1. These results suggested Sch B could protect against the oxidative damage of HK-2 cells induced by cisplatin via the activation of Nrf2/ARE signal pathway.
Antineoplastic Agents ; toxicity ; Antioxidants ; isolation & purification ; pharmacology ; Cell Line ; Cell Survival ; drug effects ; Cisplatin ; toxicity ; Cyclooctanes ; isolation & purification ; pharmacology ; Glutamate-Cysteine Ligase ; genetics ; metabolism ; Glutathione ; metabolism ; Heme Oxygenase-1 ; genetics ; metabolism ; Humans ; Kidney Tubules, Proximal ; cytology ; metabolism ; L-Lactate Dehydrogenase ; metabolism ; Lignans ; isolation & purification ; pharmacology ; NAD(P)H Dehydrogenase (Quinone) ; genetics ; metabolism ; NF-E2-Related Factor 2 ; genetics ; metabolism ; Polycyclic Compounds ; isolation & purification ; pharmacology ; RNA, Messenger ; metabolism ; Reactive Oxygen Species ; metabolism ; Schisandra ; chemistry ; Signal Transduction ; Superoxide Dismutase ; metabolism