The renin/prorenin receptor (RnR) has recently been cloned and demonstrated to exist in different cells in the cardiovascular and renal systems, playing an important role in physiological and pathophysiological situations. In the present study, we used immunofluorescence method to identify whether and where the RnR expressed in cultured rat renal mesangial cells (MCs) and rat kidney. By using the prorenin handle region peptide (HRP) as a decoy peptide of the RnR, we observed the distribution of the HRP-RnR complex in the MCs. Our results showed that the RnR was localized in the perinuclear zone and plasma membrane of the MCs. At the organ level, the RnR was observed in the mesangium of cortical glomeruli in rat kidney. The FITC-labeled HRP (FITC-HRP) translocated from cell culture medium into the cytoplasm within 30 s. Colocalization of the HRP and RnR was observed mainly on the cell membrane and in the perinuclear zone of cytoplasm by using immunofluorescence and confocal microscopy. At 30 min the FITC-HRP was mainly observed in the nucleus while the RnR remained in the perinuclear zone of cytoplasm. Taken together, our results confirm the expression of RnR in the renal MCs. It is suggested that internalization of the RnR after binding with its ligand is at least one of the pathways through which the RnR exerts its biological actions.
Animals ; Kidney ; metabolism ; Mesangial Cells ; metabolism ; Rats ; Receptors, Cell Surface ; metabolism

Cell Line ; Glucose ; metabolism ; pharmacology ; Humans ; Mesangial Cells ; drug effects ; metabolism ; Tumor Necrosis Factor-alpha ; metabolism

OBJECTIVE: To construct mesangial cell lines over- or under- expressing glucocorticoid receptor beta (GRbeta), to investigate the effect of GRbeta on glucocorticoid biological function, and to determine whether the overexpression of GRbeta explains the glucocorticoid-resistant in glomerular mesangial cells (GMCs). METHODS: The recombinant human sense or anti-sense gene of GRbeta was transferred into the rat GMCs by retrovirus-mediated stable transfection technique. Expression of hGRbeta mRNA in GMCs was determined by reverse transcription of total RNA followed by quantitative reverse transcription-polymerase chain reaction (RT-PCR), and the product of RT-PCR was then analyzed by gene sequencing. The expression of hGRbeta protein in GMCs was tested by Western blot. The inhibitory rate of dexamethasone-mediated cells on lipopolysaccharide (LPS)-stimulated GMC proliferation was detected to assess the effect of GRbeta at different expression levels on the glucocorticoid action. The cell proliferative activity in different cells with different levels of GRbeta was tested by MTT chromatometry. The change of cell cycle was analyzed by flow cytometry. RESULTS: RT-PCR and gene sequencing showed that the recombinant sense and anti-sense genes were correctly integrated into genomic DNA of mesangial cells. The protein expression tested by Western blot showed that GRbeta in cells inserted with the sense hGRbeta gene was higher than those cells inserted with the anti-sense hGRbeta gene (109.74+/-10.63 vs. 19.08+/-1.01, P<0.05). The inhibitory rate of cell proliferation induced by dexamethasone was lower in GMCs transfected with sense hGRbeta gene than those transfected with anti-sense hGRbeta gene (18.47%+/-2.12% vs. 60.33%+/- 5.29%,P<0.05). Under the inhibition of dexamethasone, the decreased cell number of S-stage cells was significantly lower, and the increased cell number of G1- stage cells was significantly higher in GMCs transfected with sense hGRbeta gene than those of non-transfected cells. CONCLUSION The overexpression of GRbeta may inhibit the glucocorticoid action in GMCs. The GRbeta level in mesangial cells may be an important factor in determining whether they are sensitive or resistant to glucocorticoid.
Animals ; Cell Line ; Dexamethasone ; pharmacology ; Glucocorticoids ; pharmacology ; Male ; Mesangial Cells ; metabolism ; Rats ; Rats, Sprague-Dawley ; Receptors, Glucocorticoid ; genetics ; metabolism ; Transfection

BACKGROUNDDiabetic nephropathy (DN) is the leading cause of end-stage renal disease. Various treatment regimens and combinations of therapies provide only partial renoprotection. Therefore new approaches are needed to retard the progression of DN. The aim of the present study was to evaluate the role of a novel spiroalkaloid from Acorus tatarinowii named acortatarin A (AcorA) in inhibiting high glucose-induced extracellular matrix accumulation in mesangial cells (MCs).

METHODSThe cytotoxity of AcorA on MCs was examined by 3-(4,5-dimethylthiazol-2-yl)-2.5-diphenyltetrazolium bromide (MTT) assay. The expression of fibronectin and collagen IV was examined by real time PCR and western blotting. The expression of p22(phox) and p47(phox) was detected by western blot. The interaction between p22(phox) and p47(phox) was examined by co-immunoprecipitation. The phosphorylation of p47(phox) was examined by immunoprecipitation. The phosphorylation of protein kinase C (PKC) α, PKCβ, phospholiase C gamma (PLCγ1), and the p85 subunit of PI3K was determined by Western blotting.

RESULTSAcorA significantly inhibited high glucose-induced activation of NADPH oxidase, a ROS-generating enzyme, by increasing phosphorylation of p47(phox) and enhancing interaction between p22(phox) and p47(phox). Preincubation of AcorA with MCs inhibited high glucose-induced collagen IV and fibronectin production in a dose-dependent manner. Moreover, AcorA attenuated high glucose enhanced phosphorylation of PKCα, PKCβ, PLCγ1, and the p85 subunit of PI3K.

CONCLUSIONAcorA inhibits high glucose-induced extracellular matrix production via blocking NADPH oxidase activation.

Animals ; Blotting, Western ; Cell Line ; Extracellular Matrix ; metabolism ; Glucose ; metabolism ; Immunoprecipitation ; Mesangial Cells ; drug effects ; metabolism ; Morpholines ; metabolism ; Rats ; Real-Time Polymerase Chain Reaction ; Spiro Compounds ; metabolism

BACKGROUNDThe renoprotective mechanisms of adenosine monophosphate (AMP)-activated protein kinase (AMPK) agonist - metformin have not been stated clearly. We hypothesized that metformin may ameliorate inflammation via AMPK interaction with critical inflammatory cytokines. The aim of this study was to observe the effects of metformin on expression of nuclear factor-κB (NF-κB), monocyte chemoattractant protein-1 (MCP-1), intercellular adhesion molecule-1 (ICAM-1) and transforming growth factor-beta 1 (TGF-β1) induced by high glucose (HG) in cultured rat glomerular mesangial cells (MCs).

METHODSMCs were cultured in the medium with normal concentration glucose (group NG, 5.6 mmol/L), high concentration glucose (group HG, 25 mmol/L) and different concentrations of metformin (group M1, M2, M3). After 48-hour exposure, the supernatants and MCs were collected. The expression of NF-κB, MCP-1, ICAM-1, and TGF-β1 mRNA was analyzed by real time polymerase chain reaction. Western blotting was used to detect the expression of AMPK, phospho-Thr-172 AMPK (p-AMPK), NF-κB p65, MCP-1, ICAM-1, and TGF-β1 protein.

RESULTSAfter stimulated by HG, the expression of NF-κB, MCP-1, ICAM-1, TGF-β1 mRNA and protein of MCs in group HG increased significantly compared with group NG (P < 0.05). Both genes and protein expression of NF-κB, MCP-1, ICAM-1, TGF-β1 of MCs induced by high glucose were markedly reduced after metformin treatment in a dose-dependent manner (P < 0.05). The expression of p-AMPK increased with the rising of metformin concentration, presenting the opposite trend, while the level of total-AMPK protein was unchanged with exposure to HG or metformin. Conlusion Metformin can suppress the expression of NF-κB, MCP-1, ICAM-1 and TGF-β1 of glomerular MCs induced by high glucose via AMPK activation, which may partly contribute to its reno-protection.

AMP-Activated Protein Kinases ; metabolism ; Animals ; Cells, Cultured ; Glomerular Mesangium ; cytology ; Glucose ; pharmacology ; Mesangial Cells ; drug effects ; metabolism ; Metformin ; pharmacology ; NF-kappa B ; metabolism ; Rats

OBJECTIVETo investigate the effect of exendin-4 on the expression of monocyte chemoattractant protein-1 (MCP-1) and fibronectin (FN) in rat glomerular mesangial cells in vitro.

METHODSRat glomerular mesangial cells were divided into 5 groups, namely control group, tumor necrosis factor-α (TNF-α) group (10 ng/ml), TNF-α (10 ng/ml)+E1 (1 nmol/L exendin-4) group, TNF-α (10 ng/ml)+E5 (5 nmol/L exendin-4) group, and TNF-α (10 ng/ml)+E10 (10 nmol/L exendin-4) group. After cultured 24 h or 48 h, RNA were extracted to determine the expression of MCP-1 with real-time PCR, the supernatant were collected to determine the expression of MCP-1 and FN with ELISA.

RESULTSCompared with control group, the cells treated with TNF-α for 24 h showed significantly increase the expression of MCP-1 and FN (P<0.01), exendin-4 significantly reduced the expression of MCP-1 and FN in TNF-α+E5 group and TNF-α+E10 group (P<0.05). After 48h incubation, the expression of MCP-1 and FN increased significantly in TNF-α group (P<0.01), which was lowered by exendin-4 in TNF-α+E1,TNF-α+E5 and TNF-α+E10 groups (P<0.05).

CONCLUSIONExendin-4 has an intrinsic capability to concentration- and time-dependently inhibit TNF-α-induced expression of MCP-1 and FN in rat mesangial cells, suggesting the beneficial effect of exendin-4 in preventing and treating diabetic nephropathy.

Animals ; Cells, Cultured ; Chemokine CCL2 ; metabolism ; Diabetic Nephropathies ; metabolism ; Glomerular Mesangium ; cytology ; Mesangial Cells ; drug effects ; metabolism ; Peptides ; pharmacology ; Rats ; Tumor Necrosis Factor-alpha ; pharmacology ; Venoms ; pharmacology

OBJECTIVETo study the morphologic changes of collagen type III glomerulopathy and to investigate the possible cellular origin for collagen III production.

METHODSLight microscopy, immunofluorescent staining, immunohistochemistry (for collagen I, III and IV and alpha-SMA) and electron microscopy studies on 3 renal biopsy cases of collagen type III glomerulopathy were performed.

RESULTSTwo cases presented with nephrotic syndrome, one of which was associated with systemic hypertension. The third case showed renal impairment and renal hypertension. None had any known family history of renal diseases. Light microscopy showed diffuse thickened glomerular basement membrane and expanded mesangium with deposition of weakly PAS-positive homogeneous material not associated with mesangial cell proliferation. Electron microscopy revealed massive collagen fiber deposits in the subendothelial spaces and mesangium. The mesangial cells also contained bundles of microfilaments in the subplasmalemmal regions. Immunohistochemically, the diffuse positivity for type III collagen corresponded to the homogeneous material seen under light microscopy. The staining for type I and IV collagens was negative. Alpha-SMA was expressed in many mesangial cells.

CONCLUSIONSThe diagnosis of collagen type III glomerulopathy can be made on the basis of detailed morphologic examination and ancillary investigations. It is possible that activated mesangial cells may be the cellular origin of collagen III.

Actins ; metabolism ; Adult ; Collagen Type III ; metabolism ; Female ; Glomerular Basement Membrane ; pathology ; ultrastructure ; Glomerulonephritis ; metabolism ; pathology ; Humans ; Male ; Mesangial Cells ; metabolism ; pathology ; Middle Aged

OBJECTIVETo investigate the effects of very low-density lipoprotein (VLDL) on cellular lipid accumulation and the expression of monocyte chemoattractant protein-1 (MCP-1) in human mesangial cells.

METHODSAn established stable human mesangial cell line (HMCL) was used in all experiments. VLDL-induced cellular lipid deposition was visualized by Oil Red O staining and analyzed quantitatively by standard enzymatic procedures. MCP-1 mRNA and protein expression levels in treated HMCLs were determined by real-time quantitative RT-PCR and enzyme-linked immunosorbent assay, respectively. For adhesion study, HMCLs were treated with VLDL for 12 hours, followed by a one-hour incubation with THP-1 cells.

RESULTSVLDL induced cellular lipid accumulation in HMCLs in a time- (0-24 h) and dose- (0-200 microg/ml) dependent manner, and the principal component of accumulated lipid is triglyceride. In HMCLs, MCP-1 mRNA expression was promoted by VLDL in a time- (0-6 h) and dose- (0-100 microg/ml) dependent manner, and VLDL also enhanced MCP-1 secretion in a dose-dependent manner. Such an effect was accompanied by increased adhesion of monocytes to HMCLs.

CONCLUSIONSVLDL can induce cellular triglyceride accumulation and upregulate the expression of MCP-1 in human mesangial cells. Hence, VLDL may be involved in the pathogenesis of lipid-mediated renal injury.

Cell Line ; Chemokine CCL2 ; genetics ; metabolism ; Humans ; Lipoproteins, VLDL ; pharmacology ; toxicity ; Mesangial Cells ; cytology ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Triglycerides ; metabolism

OBJECTIVETo study effects of Chinese Herbal Compounds (CHC) for blood activating stasis removing (BASR), qi benefiting Shen invigorating (QBSI) on high glucose stimulated proliferation of renal mesangial cells (RMCs) and expressions of fibronectin (FN).

METHODSRats' RMCs were dealt with high glucose and different concentrations of Chinese medicine for 24 and 48 h respectively. The proliferation of RMCs was detected with 4-A thiazolyl blue. mRNA expressions of FN was detected by real time quantitative PCR. The protein expression of FN was detected by ELISA.

RESULTSCompared with the control group, the proliferation obviously increased (P < 0.05, P < 0.01) after 24 and 48 h of treatment in the high glucose group, mRNA and protein expressions of FN also increased (P < 0.01). There was no statistical difference in the proliferation of RMCs or expressions of FN at 24 h between each CHC group and the high glucose group (P > 0.05). Compared with the high glucose group, the proliferation of RMCs and expressions of FN at 24 h each obviously decreased in the CHC group (P < 0.05, P < 0.01).

CONCLUSIONSHigh glucose could promote the proliferation of RMCs and induce expressions of FN. No obvious effect could be stimulated by CHC treatment for 24 h. The proliferation of RMCs, protein and mRNA expressions of FN could be reversed by CHC treatment for 48 h.

Animals ; Cells, Cultured ; Drugs, Chinese Herbal ; pharmacology ; Fibronectins ; metabolism ; Glucose ; adverse effects ; Kidney Tubules ; cytology ; Male ; Mesangial Cells ; drug effects ; metabolism ; RNA, Messenger ; genetics ; Rats

BACKGROUNDOxidative Stress and p38 mitogen-activated protein kinase (p38MAPK) play a vital role in renal fibrosis. Pioglitazone can protect kidney but the underlying mechanisms are less clear. The purpose of this study was to investigate the effect of pioglitazone on oxidative stress and whether the severity of oxidative stress was associated with the phosphorylation level of p38MAPK.

METHODSRat mesangial cells were cultured and randomly assigned to control group, high glucose group and pioglitazone group. After 48-hour exposure, the supernatants and cells were collected. The protein levels of p22(phox), p47(phox), phosphorylated p38MAPK, total p38MAPK were measured by Western blotting. The gene expressions of p22(phox), p47(phox) were detected by RT-PCR. The levels of intracellular reactive oxygen species (ROS) were determined by flow cytometry. The levels of superoxide dismutase (SOD) and maleic dialdehyde (MDA) in the supernatant were determined respectively.

RESULTSCompared with the control group, the expression levels of p22(phox), p47(phox), phospho-p38 and ROS significantly increased, activity of SOD decreased in high glucose group, while the level of MDA greatly increased (P < 0.01). Pioglitazone significantly suppressed p22(phox), p47(phox) expressions and oxidative stress induced by high glucose. The expressions of p22(phox), p47(phox), phospho-p38MAPK and ROS generation were markedly reduced after pioglitazone treatment (P < 0.05). The activity of SOD in the the supernatant increased (P < 0.05), while the level of MDA decreased greatly by pioglitazone (P < 0.05). The level of oxidative stress was associated with the phosphorylation level of p38MAPK (P < 0.01).

CONCLUSIONPioglitazone can inhibit oxidative stress through suppressing NADPH oxidase expression and p38MAPK phosphorylation.

Animals ; Blotting, Western ; Glucose ; pharmacology ; Mesangial Cells ; drug effects ; enzymology ; NADPH Oxidases ; genetics ; metabolism ; Rats ; Reactive Oxygen Species ; metabolism ; Thiazolidinediones ; pharmacology ; p38 Mitogen-Activated Protein Kinases ; genetics ; metabolism