OBJECTIVETo study the role and possible mechanisms of gap junctional intercellular communication (GJIC) involved in mesangial cell (MC) proliferation which could be inhibited by bufalin.

METHODSRat mesangial cells were cultured in vitro. The effect of bufalin on platelet-derived growth factor-BB (PDGF-BB)-induced MC proliferation was evaluated by MTT assay. The function of GJIC was detected by Lucifer Yellow scrape loading and dye transfer (SLDT). mRNA levels of Cx43, Cx45 and Cx40 were measured by RT-PCR. Intracellular calcium concentrations ([Ca(2+)]i) were examined in laser scanning confocal microscopy after loading by Fura-3/AM.

RESULTSMTT indicated that bufalin could inhibited PDGF-BB-induced MC proliferation (P<0.01). Compared with the hormal control group, PDGF-BB inhibited GJIC function, increased the expression of Cx45 and Cx40 (P<0.01) without altering the Cx43 (P>0.05) in gene level and also increased [Ca(2+)]i. However, bufalin treatment enhanced GJIC function, decreased Cx45 mRNA and Cx40 mRNA expression (P<0.01), and reduced [Ca(2+)]i (P<0.01).

CONCLUSIONSBufalin inhibits PDGF-BB-induced MC proliferation, and its possible mechanisms may be related to regulation of Cx45 and Cx40 expression in the gene level, reduction of [Ca(2+)]i and enhancement of GJIC function.

Animals ; Bufanolides ; pharmacology ; Calcium ; metabolism ; Cell Communication ; drug effects ; Cell Proliferation ; drug effects ; Cells, Cultured ; Gap Junctions ; drug effects ; Mesangial Cells ; drug effects ; physiology ; ultrastructure ; Proto-Oncogene Proteins c-sis ; pharmacology ; Rats

OBJECTIVETo study the biological impact and mechanism of recombinant tissue factor pathway inhibitor (rTFPI) on apoptosis of rat kidney mesangial cells (MsC).

METHODSTFPI expression in human glomerular minor lesion (GML), mesangial proliferative glomerulonephritis (MPGN) and cultured rat MsC was detected using immunohistochemistry and immunofluorescence, respectively. Rat MsC were incubated with rTFPI and its variant peptides. Morphological changes of apoptosis were investigated by Hoechst 33258 and the apoptotic rate was assessed by flow cytometry. DNA fragmentation and effect of rTFPI on expression of caspase-3, Fas and bcl-2 were studied using gel electrophoresis and Western blot respectively.

RESULTSThe expression of TFPI in MPGN was higher than that in GML. TFPI was expressed in cultured rat mesangial cells. Apoptosis of MsC was induced by rTFPI, especially by its C-termianl, in a dose- and time-dependent manner. Apoptosis ratios of MsC treated with rTFPI were 2.1, 3.0 and 4.9 times more than control, respectively. Expression of gene caspase-3 and Fas was up-regulated in a dose-dependent manner wherease bcl-2 expression did not show any changes.

CONCLUSIONrTFPI induces apoptosis in cultured rat mesangial cells by its C-terminal possibly via Fas/FasL pathway.

Animals ; Apoptosis ; drug effects ; physiology ; Caspase 3 ; metabolism ; Cells, Cultured ; drug effects ; DNA Fragmentation ; Flow Cytometry ; Humans ; Lipoproteins ; metabolism ; pharmacology ; Mesangial Cells ; cytology ; drug effects ; enzymology ; metabolism ; Peptides ; pharmacology ; Rats ; bcl-Associated Death Protein ; metabolism ; pharmacology

OBJECTIVETo investigate fibronectin synthesis in SD rat mesangial cells after transforming growth factor-beta1 (TGF-beta1) is silenced by the short interfering RNA (siRNA) expressed by reconstructed pGEFP-C1 vectors.

METHODSDepending upon the 538th - 556th (A) and 895th - 913th (B) nucleotides of rat TGF-beta1 gene, a nucleotide (A or B) was constructed into a small hairpin nucleotide which was separately (A or B) or together (A plus B) inserted into a pGEFP-C1 vector with three reconstructed pGEFP-C1 vectors separately expressing the siRNAs for A or/and B. TGF-beta1 and fibronectin were dynamically investigated for their interrelationship by ELISA in the supernatant and RT-PCR in their extracted total RNA.

RESULTSThe siRNA hairpin-like molecules were constructed according to the 538th - 556th nucleotides of rat TGF-beta1 gene were able to markedly silence the expression of TGF-beta1 mRNA (P < 0.01) and protein (P < 0.01) at 48 h. Lipfectamin 2000 transfection stimulated the peak secretion of fibronectin at 24 h in the control and the experimental group whose TGF-beta1 was not silenced, but the silence of TGF-beta1 in both experimental groups delayed the top values of fibronectin to 48 h (P < 0.01).

CONCLUSIONThe silence of TGF-beta1 by siRNA decreased the fibronectin expression, but the latter was possibly not completely TGF-dependent.

Animals ; Cells ; Cells, Cultured ; Fibronectins ; metabolism ; Mesangial Cells ; drug effects ; metabolism ; RNA Interference ; drug effects ; physiology ; RNA, Messenger ; metabolism ; RNA, Small Interfering ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Transforming Growth Factor beta1 ; chemistry ; genetics

The role of serum and glucocorticoid-induced kinase 1 (SGK1) pathway in the connective tissue growth factor (CTGF) expression was investigated in cultured human mesangial cells (HMCs) under high glucose. By using RT-PCR and Western blot, the effect of SGK1 on the CTGF expression in HMCs under high glucose was examined. Overexpression of active SGK1 in HMCs transfected with pIRES2-EGFP-S422D hSGK1 (SD) could increase the expression of phosphorylated SGK1 and CTGF as compared with HMCs groups transfected with pIRES2-EGFP (FP) under high glucose or normal glucose. Overexpression of inactive SGK1 in HMCs transfected with pIRES2-EGFP-K127N hSGK1 (KN) could decrease phosphorylated SGK1 and CTGF expression as compared with HMCs groups transfected with FP under high glucose. In conclusion, these results suggest that high glucose-induced CTGF expression is mediated through the active SGK1 in HMCs.
Cells, Cultured ; Connective Tissue Growth Factor/genetics ; Connective Tissue Growth Factor/*metabolism ; Glucose/*pharmacology ; Immediate-Early Proteins/metabolism ; Immediate-Early Proteins/*physiology ; Mesangial Cells/cytology ; Mesangial Cells/*metabolism ; Protein-Serine-Threonine Kinases/metabolism ; Protein-Serine-Threonine Kinases/*physiology ; Signal Transduction/drug effects

OBJECTIVETo investigate the effect of Jiangtang Yishen Recipe (JTYSR) on high insulin induced cell proliferation of human glomerular mesangial cells (HMCs) and the expression of insulin receptor substrate 1 (IRS-1) and phosphatidylinositol-3-kinase (PI-3K).

METHODSHMCs were divided into 4 groups, i.e., the negative control group, the high insulin model group, the JTYSR group, and the LY294002 group. The concentration of insulin, JTYSR, and LY294002 was respectively confirmed by pre-experiment. Different culture solution was respectively added for different groups. RPMI1640 culture solution was added for HMCs in the negative control group, while HMCs in the rest 3 groups were cultured by 100 nmol/L insulin for 24 h. Meanwhile, HMCs from the JTYSR group and the LY294002 group were exposed to 125 mg/L JTYSR and 80 micromol/L LY294002 respectively for further 48 h. The proliferation of HMCs was detected by MTT and flow cytometry. The protein expression of IRS-1 and PI-3K in HMC was detected by immunohistochemical assay and Western blot. Results The proliferation of HMCs induced by high insulin could be significantly lowered, and the protein expression of IRS-1 and PI-3K could be down-regulated in the JTYSR group and the LY294002 group (P <0.01). Compared with the LY294002 group, the protein expression of IRS-1 and PI-3K could be slightly down-regulated in the JTYSR group (P <0.05).

CONCLUSIONJTYSR could lower high insulin induced proliferation of HMCs, and its mechanism might be related to insulin signaling pathway.

Cell Proliferation ; drug effects ; Chromones ; Drugs, Chinese Herbal ; pharmacology ; Humans ; Insulin Receptor Substrate Proteins ; metabolism ; Mesangial Cells ; physiology ; Morpholines ; Phosphatidylinositol 3-Kinase ; metabolism ; Phosphatidylinositol 3-Kinases ; metabolism ; Signal Transduction

OBJECTIVETo investigate the effects of rapamycin on cholesterol homeostasis of glomerular mesangial cells and the underlying mechanisms.

METHODSIntracellular cholesterol accumulation was measured by Oil Red O staining and high performance liquid chromatography. The effects of rapamycin on interleukin-1 beta (IL-1 beta)-induced mRNA and protein changes of low-density lipoprotein receptor (LDLR) and ATP-binding cassette transporter A1 (ABCA1) were assayed by quantitative real-time PCR and Western blot. Transient expressions of 3 types of mammalian target of rapamycin (mTOR), including mTOR-WT (wild type), mTOR-RR (rapamycin resistant, with kinase activity), and mTOR-RR-KD (rapamycin resistant, without kinase activity), were obtained by plasmid transfection.

RESULTSRapamycin had no significant influence on intracellular cholesterol concentration under normal condition, but it significantly decreased the intracellular cholesterol concentration in the presence of IL-1 beta. Rapamycin dose-dependently suppressed the increased expression of LDLR induced by IL-1 beta and up-regulated the suppressed expression of ABCA1 caused by IL-1 beta. Transient expression of 3 types of mTOR all reduced ABCA1 mRNA expression significantly, which all could be overroded by rapamycin.

CONCLUSIONSRapamycin may contribute to the maintaining of glomerular mesangial cell intracellular cholesterol homeostasis under inflammatory state by both reducing cholesterol uptake and increasing cholesterol efflux. And the effect may be not completely mediated by mTOR.

ATP Binding Cassette Transporter 1 ; ATP-Binding Cassette Transporters ; genetics ; metabolism ; Animals ; Cell Line ; Cholesterol ; metabolism ; Homeostasis ; drug effects ; Humans ; Immunosuppressive Agents ; pharmacology ; Interleukin-1beta ; metabolism ; Mesangial Cells ; cytology ; drug effects ; metabolism ; Receptors, LDL ; genetics ; metabolism ; Signal Transduction ; physiology ; Sirolimus ; pharmacology

TGF-beta1-induced glomerular mesangial cell (GMC) injury is a prominent characteristic of renal pathology in several kidney diseases, and a ternary protein complex consisting of PINCH-1, integrin-linked kinase (ILK) and alpha-parvin plays a pivotal role in the regulation of cell behavior such as cell proliferation and hypertrophy. We report here that PINCH-1-ILK-alpha-parvin (PIP) complex regulates the TGF-beta1-induced cell proliferation and hypertrophy in cultured rat GMCs. When GMCs were treated with TGF-beta1 for 1, 2 and 3 days, the PIP complex formation was up-regulated after 1 day, but it was down-regulated on day 2. Cell numbers were significantly elevated on day 2, but dramatically decreased on day 3. In contrast, a significant increase in cellular protein contents was observed 3 days after TGF-beta1-treatment. TGF-beta1 induced early increase of caspase-3 activity. In GMCs incubated with TGF-beta1 for 2 days, cytosolic expression of p27(Kip1) was dramatically reduced, but its nuclear expression was remarkably elevated. A significantly decreased expression of phospho-Akt (Ser 473) was observed in the cells treated with TGF-beta1 for 1 day. TGF-beta1 induced early increase of phospho-p27(Kip1) (Thr 157) expression with subsequent decrease, and similar responses to TGF-beta1 were observed in the p38 phosphorylation (Thr 180/Thr 182). Taken together, TGF-beta1 differently regulates the PIP complex formation of GMCs in an incubation period-dependant fashion. The TGF-beta1-induced up- and down-regulation of the PIP complex formation likely contributes to the pleiotropic effects of TGF-beta1 on mesangial cell proliferation and hypertrophy through cellular localization of p27(Kip1) and alteration of Akt and p38 phosphorylation. TGF-beta1-induced alteration of the PIP complex formation may be importantly implicated in the development and progression of glomerular failure shown in several kidney diseases.
Animals ; *Cell Enlargement ; *Cell Proliferation ; Cells, Cultured ; Cyclin-Dependent Kinase Inhibitor p27/metabolism ; Cytoskeletal Proteins/*metabolism ; DNA-Binding Proteins/*metabolism ; Male ; Mesangial Cells/drug effects/*physiology ; Microfilament Proteins/*metabolism ; Phosphorylation ; Protein-Serine-Threonine Kinases/*metabolism ; Rats ; Rats, Sprague-Dawley ; Signal Transduction ; Transforming Growth Factor beta1/*pharmacology ; p38 Mitogen-Activated Protein Kinases/metabolism