scholarly journals Thrombospondin-1 Is the Key Activator of TGF-β1 in Human Mesangial Cells Exposed to High Glucose

2001 ◽  
Vol 12 (4) ◽  
pp. 703-712 ◽  
Author(s):  
NATALIA YEVDOKIMOVA ◽  
NADIA ABDEL WAHAB ◽  
ROGER M. MASON
Keyword(s):  
Growth Factor ◽  
High Glucose ◽  
Transforming Growth Factor ◽  
Mesangial Cells ◽  
Activation Mechanism ◽  
Plasminogen Activator Inhibitor 1 ◽  
Human Mesangial Cells ◽  
Thrombospondin 1 ◽  
Tgf Β1 ◽  
Pai 1

Abstract. Elevated levels of transforming growth factor-β1 (TGF-β1) are synthesized by human mesangial cells that are cultured in medium that contains high concentrations of glucose and mediate increased synthesis of fibronectin (FN), plasminogen activator inhibitor-1 (PAI-1), and changes in the expression of other genes. TGF-β1 is synthesized as a latent complex. Previous work indicated that high-glucose conditions also upregulate expression of thrombospondin-1 (TSP-1), a potential activator of latent TGF-β1. With the use of the synthetic peptide GGWSHW, an inhibitor of the TSP-1 activation mechanism, endogenous TSP-1 is shown to be responsible for converting high levels of latent TGF-β1 to bioactive growth factor over 3 wk of exposure of mesangial cells to 30 mM D-glucose. Peptide inhibition of TGF-β1 activation by TSP-1 in high-glucose conditions completely suppressed increases in FN and PAI-1 expression. Treating mesangial cells maintained in high glucose with a TSP-1 antisense oligonucleotide reduced TSP-1 expression to levels found in 4 mM D-glucose cultures, prevented TGF-β1 activation, and normalized expression of FN.

scholarly journals Receptor-mediated nonproteolytic activation of prorenin and induction of TGF-β1 and PAI-1 expression in renal mesangial cells

2012 ◽  
Vol 303 (1) ◽  
pp. F11-F20 ◽  
Author(s):  
Jiandong Zhang ◽  
Jie Wu ◽  
Chunyan Gu ◽  
Nancy A. Noble ◽  
Wayne A. Border ◽  
...  
Keyword(s):  
Diabetic Nephropathy ◽  
Growth Factor ◽  
Transforming Growth Factor ◽  
Mesangial Cells ◽  
Plasminogen Activator Inhibitor ◽  
Transforming Growth Factor Β ◽  
Diabetic Patients ◽  
Ang Ii ◽  
Plasminogen Activator Inhibitor 1 ◽  
Pai 1

While elevated plasma prorenin levels are commonly found in diabetic patients and correlate with diabetic nephropathy, the pathological role of prorenin, if any, remains unclear. Prorenin binding to the (pro)renin receptor [(p)RR] unmasks prorenin catalytic activity. We asked whether elevated prorenin could be activated at the site of renal mesangial cells (MCs) through receptor binding without being proteolytically converted to renin. Recombinant inactive rat prorenin and a mutant prorenin that is noncleavable, i.e., cannot be activated proteolytically, are produced in 293 cells. After MCs were incubated with 10−7 M native or mutant prorenin for 6 h, cultured supernatant acquired the ability to generate angiotensin I (ANG I) from angiotensinogen, indicating both prorenins were activated. Small interfering RNA (siRNA) against the (p)RR blocked their activation. Furthermore, either native or mutant rat prorenin at 10−7 M alone similarly and significantly induced transforming growth factor-β1, plasminogen activator inhibitor-1 (PAI-1), and fibronectin mRNA expression, and these effects were blocked by (p)RR siRNA, but not by the ANG II receptor antagonist, saralasin. When angiotensinogen was also added to cultured MCs with inactive native or mutant prorenin, PAI-1 and fibronectin were further increased significantly compared with prorenin or mutant prorenin alone. This effect was blocked partially by treatment with (p)RR siRNA or saralasin. We conclude that prorenin binds the (p)RR on renal MCs and is activated nonproteolytically. This activation leads to increased expression of PAI-1 and transforming growth factor-β1 via ANG II-independent and ANG II-dependent mechanisms. These data provide a mechanism by which elevated prorenin levels in diabetes may play a role in the development of diabetic nephropathy.

scholarly journals Involvement of p300/CBP and epigenetic histone acetylation in TGF-β1-mediated gene transcription in mesangial cells

2013 ◽  
Vol 304 (5) ◽  
pp. F601-F613 ◽  
Author(s):  
Hang Yuan ◽  
Marpadga A. Reddy ◽  
Guangdong Sun ◽  
Linda Lanting ◽  
Mei Wang ◽  
...  
Keyword(s):  
Diabetic Nephropathy ◽  
Histone Acetylation ◽  
Transforming Growth Factor ◽  
Mesangial Cells ◽  
Mrna Levels ◽  
Creb Binding Protein ◽  
Diabetic Mice ◽  
Plasminogen Activator Inhibitor 1 ◽  
Tgf Β1 ◽  
Pai 1

Transforming growth factor-β1 (TGF-β1)-induced expression of plasminogen activator inhibitor-1 (PAI-1) and p21 in renal mesangial cells (MCs) plays a major role in glomerulosclerosis and hypertrophy, key events in the pathogenesis of diabetic nephropathy. However, the involvement of histone acetyl transferases (HATs) and histone deacetylases (HDACs) that regulate epigenetic histone lysine acetylation, and their interaction with TGF-β1-responsive transcription factors, are not clear. We evaluated the roles of histone acetylation, specific HATs, and HDACs in TGF-β1-induced gene expression in rat mesangial cells (RMCs) and in glomeruli from diabetic mice. Overexpression of HATs CREB binding protein (CBP) or p300, but not p300/CBP-activating factor, significantly enhanced TGF-β1-induced PAI-1 and p21 mRNA levels as well as transactivation of their promoters in RMCs. Conversely, they were significantly attenuated by HAT domain mutants of CBP and p300 or overexpression of HDAC-1 and HDAC-5. Chromatin immunoprecipitation assays showed that TGF-β1 treatment led to a time-dependent enrichment of histone H3-lysine9/14-acetylation (H3K9/14Ac) and p300/CBP occupancies around Smad and Sp1 binding sites at the PAI-1 and p21 promoters. TGF-β1 also enhanced the interaction of p300 with Smad2/3 and Sp1 and increased Smad2/3 acetylation. High glucose-treated RMCs exhibited increased PAI-1 and p21 levels, and promoter H3K9/14Ac, which were blocked by TGF-β1 antibodies. Furthermore, increased PAI-1 and p21 expression was associated with elevated promoter H3K9/14Ac levels in glomeruli from diabetic mice. Thus TGF-β1-induced PAI-1 and p21 expression involves interaction of p300/CBP with Smads and Sp1, and increased promoter access via p300/CBP-induced H3K9/14Ac. This in turn can augment glomerular dysfunction linked to diabetic nephropathy.

scholarly journals Transforming Growth Factor-β Is a Potent Inhibitor of Extracellular Matrix Degradation by Cultured Human Mesangial Cells

1999 ◽  
Vol 10 (4) ◽  
pp. 790-795 ◽  
Author(s):  
WILLIAM H. BARICOS ◽  
SHIRLEY L. CORTEZ ◽  
MICHAEL DEBOISBLANC ◽  
SHI XIN
Keyword(s):  
Extracellular Matrix ◽  
Growth Factor ◽  
Renal Disease ◽  
Transforming Growth Factor ◽  
Mesangial Cells ◽  
Potent Inhibitor ◽  
Matrix Degradation ◽  
Human Mesangial Cells ◽  
Ecm Degradation ◽  
Tgf Β1

Abstract. Accumulation of the glomerular extracellular matrix (ECM) is a pivotal event in the progression from acute glomerular injury to end-stage renal disease. Although enhanced ECM synthesis has been demonstrated to contribute to ECM accumulation, the role of decreased ECM degradation is largely unknown. It was previously shown that glomerular ECM degradation is mediated by a plasminogen activator (PA)/plasmin/matrix metalloproteinase 2 (MMP-2) cascade. However, little information is available regarding the factors that regulate the activity of this degradative cascade in normal or pathologic states. Transforming growth factor-β1 (TGF-β1) is shown here to be a potent inhibitor of ECM degradation by cultured human mesangial cells. Using human mesangial cells grown on thin films of 125I-labeled Matrigel, dose-dependent inhibition of ECM degradation in the presence of TGF-β1 was observed, reaching >90% inhibition with 0.4 ng/ml TGF-β1. Addition of anti-TGF-β antibodies (4 μg/ml) in the absence of exogenous TGF-β increased ECM degradation (1.8 ± 0.2-fold versus controls, P < 0.05). In contrast, platelet-derived growth factor, at concentrations up to 10 ng/ml, had no effect on ECM degradation. TGF-β completely blocked the conversion of plasminogen to plasmin and markedly reduced the conversion of latent MMP-2 to active MMP-2. TGF-β did not significantly alter the levels of tissue PA, total MMP-2, or tissue inhibitor of metalloproteinase-1, but did increase the levels of PA inhibitor-1 (1.8-fold, P < 0.05), the major physiologic inhibitor of PA. These data document that TGF-β is a potent inhibitor of ECM degradation by cultured human mesangial cells, and they suggest that decreased mesangial matrix degradation, caused by TGF-β-mediated decreases in the activity of the PA/plasmin/MMP-2 cascade, may contribute to the glomerular matrix accumulation that occurs in progressive renal disease.

scholarly journals Elevated level of ambient glucose stimulates the synthesis of high-molecular-weight hyaluronic acid by human mesangial cells. The involvement of transforming growth factor beta1 and its activation by thrombospondin-1.

2006 ◽  
Vol 53 (2) ◽  
pp. 383-393 ◽  
Author(s):  
Natalia Yu Yevdokimova
Keyword(s):  
Molecular Weight ◽  
Growth Factor ◽  
High Molecular Weight ◽  
High Glucose ◽  
Structural Integrity ◽  
Transforming Growth Factor ◽  
Mesangial Cells ◽  
Lower Molecular Weight ◽  
Transforming Growth Factor Beta1 ◽  
Thrombospondin 1

The dysregulation of the metabolism of glycosaminoglycan and protein components of extracellular matrix (ECM) is a typical feature of diabetic complications. High glucose-induced enrichment of ECM with hyaluronan (HA) not only affects tissue structural integrity, but influences cell metabolic response due to the variety of effects depending on the HA polymer molecular weight. TSP-1-dependent activation of TGFbeta1 axis is known to mediate numerous matrix disorders in diabetes, but its role concerning HA has not been studied so far. In this work we demonstrated that 30 mM D-glucose increased the incorporation of [(3)H]glucosamine in high-molecular-weight (> 2000 kDa) HA of medium and matrix compartments of human mesangial cultures. Simultaneously, the synthesis of HA with lower molecular weight and HA degradation were not altered. The cause of the increased high-molecular-weight HA synthesis consisted in the up-regulation of hyaluronan synthase (HAS) 2 mRNA without alterations of the expression of HAS3, which generates HA of lower molecular weight. D-Glucose at 30 mM also stimulated the production of transforming growth factor beta1 (TGFbeta1), the excessive activation of which was determined by the up-regulation of thrombospondin-1 (TSP-1). The blockage of TGFbeta1 action either by neutralizing anti-TGFbeta1 antibodies or by quenching the TGFbeta1 activation (with TSP-1-derived synthetic GGWSHW peptide) abolished the effect of high glucose on HAS2 mRNA expression and normalized the synthesis of HA. Exogenous human TGFbeta1 had the same effect on HAS2 expression and HA synthesis as high glucose treatment. Therefore, we supposed that TSP-1-dependent TGFbeta1 activation is involved in the observed high glucose effect on HA metabolism. Since high-molecular-weight HA polymers, unlike middle- and low-molecular weight HA oligosaccharides, are known to possess anti-inflammatory and anti-fibrotic functions, we suppose that the enrichment of mesangial matrix with high-molecular-weight HA may represent an endogenous mechanism to limit renal injury in diabetes.

Decorin suppresses transforming growth factor-β-induced expression of plasminogen activator inhibitor-1 in human mesangial cells through a mechanism that involves Ca2+-dependent phosphorylation of Smad2 at serine-240

2002 ◽  
Vol 362 (3) ◽  
pp. 643-649 ◽  
Author(s):  
Nadia ABDEL-WAHAB ◽  
Stephen J. WICKS ◽  
Roger M. MASON ◽  
Andrew CHANTRY
Keyword(s):  
Growth Factor ◽  
Plasminogen Activator ◽  
Transforming Growth Factor ◽  
Mesangial Cells ◽  
Plasminogen Activator Inhibitor ◽  
Transforming Growth Factor Β ◽  
Receptor Activation ◽  
Plasminogen Activator Inhibitor 1 ◽  
Human Mesangial Cells ◽  
Activator Inhibitor

Transforming growth factor-β (TGFβ) is a key mediator of extracellular matrix (ECM) accumulation in sclerotic kidney diseases such as diabetic nephropathy. One of the main target cells for TGFβ in the kidney are glomerular mesangial cells, which respond by increasing expression of ECM proteins, such as collagens, laminin and fibronectin, while suppressing the expression of ECM-degrading proteases and increasing the synthesis of ECM protease inhibitors, including plasminogen activator inhibitor-1. Previous studies have shown that exposure of mesangial cells to chronic high-glucose conditions, such as those seen in diabetes, increases ECM deposition in a mechanism involving glucose-mediated up-regulation of TGFβ expression. Naturally occurring inhibitors of this TGFβ-dependent fibrotic response include decorin, a small leucine-rich proteoglycan. While the mechanism by which TGFβ stimulates gene expression via the Smad signal-transduction pathway is becoming clear, the precise mechanism by which decorin may impinge upon TGFβ activity remains to be established. In this study, for the first time we provide evidence that decorin can disrupt glucose- and TGFβ/Smad-dependent transcriptional events in human mesangial cells through a mechanism that involves an increase in Ca2+ signalling, the activation of Ca2+/calmodulin-dependent protein kinase II and ensuing phosphorylation of Smad2 at Ser-240. We show that decorin also induces Ser-240 phospho-Smad hetero-oligomerization with Smad4 and the nuclear localization of this complex independently of TGFβ receptor activation. Thus, in human mesangial cells, the mechanism of decorin-mediated inhibition of TGFβ signalling may involve activation of Ca2+ signalling, the subsequent phosphorylation of Smad2 at a key regulatory site, and the sequestration of Smad4 in the nucleus.

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