High Glucose-induced Mesangial Cell Research Articles

Inhibitory Effects of Salvianolic Acid B on the High Glucose-Induced Mesangial Proliferation via NF-.KAPPA.B-Dependent Pathway

Salvianolic acid B (Sal B) is one of the major water-soluble compounds isolated from Radix Salviae Miltiorrhizae (Danshen in Chinese) that has been reported to be beneficial to treatment of diabetic complications. However, the mechanisms involved in these effects are not discussed in relation to mesangial proliferation via modulation of NF-kappaB. To explain this, human mesangial cells were pretreated with or without Sal B (0.1, 1, 10 microM) for 24 h and stimulated with high glucose (30 mM). Then the effects of Sal B on mesangial cells proliferation, extracellular matrix production and the possible mechanisms were evaluated by methylthiazoletetrazolium assay, flow cytometry assay, enzyme-linked immunosorbent assay, gelatin zymography assay and western blot assay. These results indicated that Sal B could inhibit high glucose-induced mesangial cells proliferation and extracellular matrix production in a dose-dependent manner, partially through modulating the cell-cycle progress and MMP-2 and MMP-9 activities via suppressing NF-kappaB activation, suggesting that Sal B may be a promising agent for treating diabetic nephropathy.

Chemically Modified Heparin Inhibits Mesangial Cell Proliferation Induced by High Glucose through Interfering with the Cell Cycle

The aims of this study were to investigate whether chemically modified non-anticoagulation heparin derivate (Periodate-Oxidized/Borohydride-Reduced modified heparin (OR-heparin)) can inhibit high glucose-induced human mesangial cell proliferation and its influence on the cell cycle. OR-heparin with low anticoagulation activity inhibited high glucose-induced early proliferation in a dose-dependent manner. OR-heparin released high glucose-arrested mesangial cells at G(1) phase, and dose-dependently increased S phase. OR-heparin also inhibited high glucose-activated ERK1/2 phosphorylation, induced p27(Kip1) expression, and suppressed reactive oxygen species (ROS) accumulation in a dose-dependent manner. Our results suggest that OR-heparin releases high glucose-arrested cells on G(1) phase and inhibits high glucose-induced mesangial cell proliferation through blocking ERK1/2 phosphorylation and delaying S phase progression, which may be in correlation with OR-heparin suppressing ROS accumulation.

Wnt/β-Catenin Signaling Modulates Survival of High Glucose–Stressed Mesangial Cells

Glomerulosclerosis and diabetic nephropathy are attributable to high glucose induction of mesangial cell apoptosis. Whereas Wnt signaling has been found to regulate renal morphogenesis and pathogenesis, the biologic role of Wnt/beta-catenin signaling in controlling high glucose-induced mesangial cell apoptosis is not well defined. Herein is reported that Wnt/beta-catenin signaling is required for protecting glomerular mesangial cells from high glucose-mediated cell apoptosis. High glucose downregulated Wnt4 and Wnt5a expression and the subsequent nuclear translocation of beta-catenin, whereas it increased glycogen synthase kinase-3beta (GSK-3beta) and caspase-3 activities and apoptosis of glomerular mesangial cells. Suppression of GSK-3beta activation or increase in nuclear beta-catenin by transfection of Wnt4 or Wnt5a or stable beta-catenin (S33Y) reversed Akt activation and reduced the high glucose-mediated caspase-3 cleavage and cell apoptosis. Pharmacologic inhibition of GSK-3beta by recombinant Wnt5a or bromoindirubin-3'-oxime or LiCl increased Akt phosphorylation and beta-catenin translocation and abrogated high glucose-mediated proapoptotic activities. Exogenous bromoindirubin-3'-oxime treatment reduced phospho-Ser(9)-GSK-3beta and beta-catenin expression and apoptosis of cells adjacent to glomeruli in diabetic kidneys and attenuated urinary protein secretion in diabetic rats. Taken together, mesangial cells responded to high glucose by impairing that canonical Wnt pathway to increase proapoptotic activities. Sustaining Wnt/beta-catenin signaling is beneficial for promoting survival of mesangial cells that are exposed to high glucose stress.

Activation of phosphoinositide 3-kinase in response to high glucose leads to regulation of reactive oxygen species-related nuclear factor-kappaB activation and cyclooxygenase-2 expression in mesangial cells.

Hyperglycemia causes glomerular mesangial cell proliferation and increases matrix synthesis, contributing to early diabetic glomerulopathy. Immunohistochemical and functional correlations of renal cyclooxygenase-2 in experimental diabetes have been identified. However, the role of cyclooxygenase-2 in early diabetes-induced mesangial cell proliferation remains unknown. The authors tested the hypothesis that hyperglycemia modulates an intrarenal cyclooxygenase-2 expression, which might mediate the mesangial cell proliferation via a possible phosphoinositide 3-kinase/Akt pathway. Expression of cyclooxygenase-2, but not cyclooxygenase-1, could be induced in mesangial cells cultured under high glucose. Antioxidants (pyrrolidine dithiocarbamate and N-acetyl-l-cysteine) and phosphoinositide 3-kinase inhibitors [2-(4-morpholinyl)-8-phenyl-1(4H)-benzopyran-4-one hydrochloride (LY294002) and wortmannin] effectively inhibited this high glucose-induced response. Moreover, high glucose markedly triggered the activation of phosphoinositide 3-kinase and Akt in mesangial cells, suggesting that a phosphoinositide 3-kinase/Akt pathway is involved in the high glucose-induced responses. Phosphoinositide 3-kinase inhibitors could also effectively attenuate the high glucose-triggered intracellular reactive oxygen species generation and nuclear factor-kappaB activation. Likewise, blocking the phosphoinositide 3-kinase or Akt activity with the dominant-negative vectors DN-p85 or DN-Akt, respectively, also greatly diminished the high glucose-triggered reactive oxygen species generation and nuclear factor-kappaB activation. Treatment of mesangial cells with LY294002 and cyclooxygenase-2 inhibitors [N-[2-(cyclohexyloxyl)-4-nitrophenyl]-methane sulfonamide (NS398) and aspirin] effectively inhibited the high glucose-induced mesangial cell proliferation. These results suggest that high glucose may trigger the reactive oxygen species-regulated nuclear factor-kappaB activation and cyclooxygenase-2 expression and cell proliferation in mesangial cells through a phosphoinositide 3-kinase-dependent pathway.

Sp1-decoy oligodeoxynucleotide inhibits high glucose-induced mesangial cell proliferation

Mesangial expansion caused by cell proliferation and glomerular extracellular matrix accumulation is one of the earliest renal abnormalities observed at the onset of hyperglycemia in diabetes mellitus. Transcription factor Sp1 is implicated in the transcriptional regulation of a wide range of genes participating in cell proliferation, and is assumed to play an essential role in mesangial expansion. We have generated a phosphorothioated double-stranded Sp1-decoy oligodeoxynucleotide that effectively blocks Sp1 binding to the promoter region for transcriptional regulation of transforming growth factor-β1 and plasminogen activator inhibitor-1. The Sp1-decoy oligodeoxynucleotide suppressed transcription of these cytokines and proliferation of primary rat mesangial cells in response to high glucose. These results suggest that the Sp1-decoy oligodeoxynucleotide could be a powerful tool in preventing the pathogenesis of renal hypertrophy.

Sp1-decoy oligodeoxynucleotide inhibits high glucose-induced mesangial cell proliferation

Sp1-decoy oligodeoxynucleotide inhibits high glucose-induced mesangial cell proliferation

The cyclin kinase inhibitor p21WAF1, CIP1 is increased in experimental diabetic nephropathy: potential role in glomerular hypertrophy.

High glucose inhibits mesangial cell proliferation in vitro and induces hypertrophy in mesangial cells in culture and in experimental diabetic nephropathy. Cell growth is ultimately controlled at the level of the cell cycle by cell cycle regulatory proteins. Cell cycle progression requires that cyclin-dependent kinases be activated by cyclins. Cyclin kinase inhibitors (CKI) inactivate cyclin-dependent kinases, causing cell cycle arrest. In the current study, high glucose-induced mesangial cell hypertrophy in vitro is shown to be associated with increased levels of the CKI p21, but not p27. In the streptozotocin model of experimental diabetes in the mouse, glomerular hypertrophy was associated with a selective increase in p21 expression, whereas the levels of the CKI p27 and p57 did not change. Unlike many other forms of glomerular injury, diabetic nephropathy was not associated with increased apoptosis. These results support a role for p21 in causing glomerular cell hypertrophy in diabetic nephropathy.

High glucose-induced mesangial cell altered contractility: role of the polyol pathway.

Glomerular mesangial cells cultured in high glucose conditions display impaired contractile responsiveness. It was postulated that glucose metabolism through the polyol pathway leads to altered mesangial cell contractility involving protein kinase C. Rat mesangial cells were growth-arrested for 24 h with 0.5% fetal bovine serum in either normal (5.6 mmol/l) or high (30 mmol/l) glucose concentrations or high glucose plus the aldose reductase inhibitor, ARI-509 (100 micromol/l). The reduction of cell planar surface area (contraction) in response to endothelin-1 (0.1 micromol/l), or to phorbol 12-myristate 13-acetate (50 pmol/l), was studied by videomicroscopy. In response to endothelin-1, mesangial cells in normal glucose contracted to 52+/-3% of initial planar area. In high glucose, the significantly (p < 0.05) smaller cell size and no contractile responsiveness to endothelin-1 were normalized with ARI-509. Membrane-associated diacylglycerol, measured by a kinase specific 32P-phosphorylation assay, in high glucose was unchanged after 3 h, but significantly increased (p < 0.05) after 24 h which was normalized with ARI-509. Protein kinase C activity, measured by in situ 32P-phosphorylation of the epidermal growth factor receptor substrate was: increased by 32% at 3 h of high glucose, unchanged by ARI-509; and decreased significantly (p < 0.05) at 24 h compared to cells in normal glucose, normalized by ARI-509. Total cellular protein kinase C-alpha, -delta and -epsilon, analysed by immunoblotting, were unchanged in high glucose at 24 h. Only protein kinase C-epsilon content was reduced by ARI-509 in both normal and high glucose. Therefore, high glucose-induced loss of mesangial cell contractility, diacylglycerol accumulation and altered protein kinase C activity are mediated through activation of the polyol-pathway, although no specific relationship between elevated diacylglycerol and protein kinase C activity was observed. In high glucose, altered protein kinase C function, or another mechanism related to the polyol pathway, contribute to loss of mesangial cell contractile responsiveness.