Upregulation of type I collagen by TGF-β in mesangial cells is blocked by PPARγ activation

2002 ◽  
Vol 282 (4) ◽  
pp. F639-F648 ◽  
Author(s):  
Feng Zheng ◽  
Alessia Fornoni ◽  
Sharon J. Elliot ◽  
Youfei Guan ◽  
Matthew D. Breyer ◽  
...  
Keyword(s):  
Type I Collagen ◽  
Transforming Growth Factor ◽  
Mesangial Cells ◽  
Dominant Negative ◽  
Peroxisome Proliferator ◽  
Type I ◽  
Collagen Mrna ◽  
Collagen Expression ◽  
Pparγ Agonist ◽  
Pparγ Expression

We found that peroxisome proliferator-activated receptor-γ (PPARγ) mRNA was reduced by 77% in glomeruli of diabetic mice. Because mesangial cells play an important role in diabetic nephropathy, we examined regulation of type I collagen expression by PPARγ and transforming growth factor-β1 (TGF-β1) in mouse mesangial cells in the presence of 6 and 25 mM glucose. Mesangial cells contained functionally active PPARγ. Exposure to 25 mM glucose resulted in reduced PPARγ expression and transcriptional activity, accompanied by increased type I collagen expression. Restoration of PPARγ activity to normal levels in cells cultured in 25 mM glucose, by transfection with a PPARγ expression construct and treatment with the PPARγ agonist troglitazone, returned type I collagen levels toward normal values. Activation of PPARγ by troglitazone also decreased type I collagen mRNA and blocked TGF-β1-mediated upregulation of type I collagen mRNA and protein. Moreover, PPARγ activation suppressed basal and activated TGF-β1 responses in mesangial cells. This action was blocked by transfection of cells with a dominant-negative PPARγ construct. In summary, PPARγ suppresses the increased type I collagen mRNA and protein expression mediated by TGF-β1 in mesangial cells.

TGF-β-regulated collagen type I accumulation: role of Src-based signals

2007 ◽  
Vol 292 (4) ◽  
pp. C1361-C1369 ◽  
Author(s):  
Rangnath Mishra ◽  
Ling Zhu ◽  
Richard L. Eckert ◽  
Michael S. Simonson
Keyword(s):  
Type I Collagen ◽  
Collagen Type ◽  
Transforming Growth Factor ◽  
Mesangial Cells ◽  
Collagen Type I ◽  
Dominant Negative ◽  
Dominant Negative Mutant ◽  
Type I ◽  
Small Interference Rna ◽  
Collagen Secretion

Transforming growth factor-β (TGF-β) stimulates myofibroblast transdifferentiation, leading to type I collagen accumulation and fibrosis. We investigated the function of Src in TGF-β-induced collagen I accumulation. In human mesangial cells, PTyr416 Src (activated Src) was 3.3-fold higher in TGF-β-treated cells than in controls. Src activation by TGF-β was blocked by rottlerin and by a dominant negative mutant of protein kinase Cδ (PKCδ), showing that TGF-β activates Src by a PKCδ-based mechanism. Pharmacological inhibitors and a dominant negative Src mutant prevented the increase in collagen type I secretion in cells exposed to TGF-β. Similarly, on-target Src small interference RNA (siRNA) prevented type I collagen secretion in response to TGF-β, but off-target siRNA complexes had no effect. It is well established in mesangial cells that upregulation of type I collagen by TGF-β requires extracellular signal-regulated kinase 1/2 (ERK1/2), and we found that activation of ERK1/2 by TGF-β requires Src. In conclusion, these results suggest that stimulation of collagen type I secretion by TGF-β requires a PKCδ-Src-ERK1/2 signaling motif.

scholarly journals Interdependence of HIF-1α and TGF-β/Smad3 signaling in normoxic and hypoxic renal epithelial cell collagen expression

2011 ◽  
Vol 300 (4) ◽  
pp. F898-F905 ◽  
Author(s):  
Rajit K. Basu ◽  
Susan Hubchak ◽  
Tomoko Hayashida ◽  
Constance E. Runyan ◽  
Paul T. Schumacker ◽  
...  
Keyword(s):  
Signaling Pathways ◽  
Renal Fibrosis ◽  
Type I Collagen ◽  
Transforming Growth Factor ◽  
Dominant Negative ◽  
Type I ◽  
Mrna Levels ◽  
Renal Epithelial Cell ◽  
Collagen Expression ◽  
Tgf Β1

Increasing evidence suggests that chronic kidney disease may develop following acute kidney injury and that this may be due, in part, to hypoxia-related phenomena. Hypoxia-inducible factor (HIF) is stabilized in hypoxic conditions and regulates multiple signaling pathways that could contribute to renal fibrosis. As transforming growth factor (TGF)-β is known to mediate renal fibrosis, we proposed a profibrotic role for cross talk between the TGF-β1 and HIF-1α signaling pathways in kidney cells. Hypoxic incubation increased HIF-1α protein expression in cultured human renal tubular epithelial cells and mouse embryonic fibroblasts. TGF-β1 treatment further increased HIF-1α expression in cells treated with hypoxia and also increased HIF-1α in normoxic conditions. TGF-β1 did not increase HIF-1α mRNA levels nor decrease the rate of protein degradation, suggesting that it enhances normoxic HIF-1α translation. TGF-β receptor (ALK5) kinase activity was required for increased HIF-1α expression in response to TGF-β1, but not to hypoxia. A dominant negative Smad3 decreased the TGF-β-stimulated reporter activity of a HIF-1α-sensitive hypoxia response element. Conversely, a dominant negative HIF-1α construct decreased Smad-binding element promoter activity in response to TGF-β. Finally, blocking HIF-1α transcription with a biochemical inhibitor, a dominant negative construct, or gene-specific knockdown decreased basal and TGF-β1-stimulated type I collagen expression, while HIF-1α overexpression increased both. Taken together, our data demonstrate cooperation in signaling between Smad3 and HIF-1α and suggest a new paradigm in which HIF-1α is necessary for normoxic, TGF-β1-stimulated renal cell fibrogenesis.

Mechanical stretch modulates TGF-β1 and α1(I) collagen expression in fetal human intestinal smooth muscle cells

1999 ◽  
Vol 277 (5) ◽  
pp. G1074-G1080 ◽  
Author(s):  
Jorge A. Gutierrez ◽  
Hilary A. Perr
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Type I Collagen ◽  
Intestinal Smooth Muscle ◽  
Type I ◽  
Collagen Mrna ◽  
Collagen Expression ◽  
Collagen Protein ◽  
Mrna Content ◽  
Tgf Β1

Intestinal muscle undergoes stretch intermittently during peristalsis and persistently proximal to obstruction. The influence of this pervasive biomechanical force on developing smooth muscle cell function remains unknown. We adapted a novel in vitro system to study whether stretch modulates transforming growth factor-β1 (TGF-β1) and type I collagen protein and component α1 chain [α1(I) collagen] expression in fetal human intestinal smooth muscle cells. Primary confluent cells at 20-wk gestation, cultured on flexible silicone membranes, were subjected to two brief stretches or to 18 h tonic stretch. Nonstretched cultures served as controls. TGF-β1 protein was measured by ELISA and type I collagen protein was assayed by Western blot. TGF-β1 and α1(I) collagen mRNA abundance was determined by Northern blot analysis, quantitated by phosphorimaging, and normalized to 18S rRNA. Transcription was examined by nuclear run-on assay. Tonic stretch increased TGF-β1 protein 40%, type I collagen protein 100%, TGF-β1 mRNA content 2.16-fold, and α1(I) collagen mRNA 3.80-fold and enhanced transcription of TGF-β1 and α1(I) collagen by 3.1- and 4.25-fold, respectively. Brief stretch stimulated a 50% increase in TGF-β1 mRNA content but no change in α1(I) collagen. Neutralizing anti-TGF-β1 ablated stretch-mediated effects on α1(I) collagen. Therefore, stretch upregulates transcription for TGF-β1, which stimulates α1(I) collagen gene expression in smooth muscle from developing gut.

TGF-β-activated kinase 1 and TAK1-binding protein 1 cooperate to mediate TGF-β1-induced MKK3-p38 MAPK activation and stimulation of type I collagen

2007 ◽  
Vol 292 (5) ◽  
pp. F1471-F1478 ◽  
Author(s):  
Sung Il Kim ◽  
Joon Hyeok Kwak ◽  
Mareena Zachariah ◽  
Yanjuan He ◽  
Lin Wang ◽  
...  
Keyword(s):  
P38 Mapk ◽  
Type I Collagen ◽  
Mesangial Cells ◽  
Constitutive Expression ◽  
Mapk Signaling ◽  
Signaling Cascade ◽  
Type I ◽  
Protein Levels ◽  
Collagen Expression ◽  
P38α Mapk

We have previously demonstrated that transforming growth factor-β1 (TGF-β1) rapidly activates the mitogen-activated protein kinase kinase 3 (MKK3)-p38 MAPK signaling cascade, leading to the induction of type I collagen synthesis in mouse glomerular mesangial cells (Wang L, Ma R, Flavell RA, Choi ME. J Biol Chem 277: 47257–47262, 2002). In the present study, we investigated the functional role of upstream TGF-β-activated kinase 1 (TAK1) and TAK1-binding protein 1 (TAB1) in the TGF-β1 signaling cascade. Rapid activation of endogenous TAK1 activity by TGF-β1 was observed in mouse mesangial cells. Transient overexpression of TAK1 with TAB1 enhanced the activation of MKK3 and p38 MAPK with or without TGF-β1 stimulation, whereas a dominant-negative mutant of TAK1 (TAK1DN) suppressed TGF-β1-induced activation of MKK3 and p38 MAPK. Moreover, constitutive expression of TAK1DN reduced steady-state protein levels of MKK3 and p38 MAPK as well as MKK3 phosphorylation. Increased p38α MAPK activity by ectopic expression of either TAB1 or wild-type p38α MAPK resulted in enhanced TGF-β1-induced type I collagen expression. In contrast, constitutive expression of TAK1DN inhibited collagen induction. Taken together, our data indicate that TAK1 and TAB1 play a pivotal role as upstream signal transducers activating the MKK3-p38 MAPK signaling cascade that leads to the induction of type I collagen expression by TGF-β1. In addition, our findings also suggest that TAK1 has a novel function in regulation of the steady-state protein levels of MKK3 and p38 MAPK.

scholarly journals Altered bleomycin-induced lung fibrosis in osteopontin-deficient mice

2004 ◽  
Vol 286 (6) ◽  
pp. L1311-L1318 ◽  
Author(s):  
Jeffrey S. Berman ◽  
David Serlin ◽  
Xinfang Li ◽  
Geoffrey Whitley ◽  
John Hayes ◽  
...  
Keyword(s):  
Lung Fibrosis ◽  
Type I Collagen ◽  
Transforming Growth Factor ◽  
Matrix Metalloproteinase 2 ◽  
Mouse Lung ◽  
Matricellular Protein ◽  
Type Iii Collagen ◽  
Type I ◽  
Osteopontin Expression ◽  
Collagen Expression

Osteopontin is a multifunctional matricellular protein abundantly expressed during inflammation and repair. Osteopontin deficiency is associated with abnormal wound repair characterized by aberrant collagen fibrillogenesis in the heart and skin. Recent gene microarray studies found that osteopontin is abundantly expressed in both human and mouse lung fibrosis. Macrophages and T cells are known to be major sources of osteopontin. During lung fibrosis, however, osteopontin expression continues to increase when inflammation has receded, suggesting alternative sources of ostepontin during this response. In this study, we demonstrate immunoreactivity for osteopontin in lung epithelial and inflammatory cells in human usual interstitial pneumonitis and murine bleomycin-induced lung fibrosis. After treatment with bleomycin, osteopontin-null mice develop lung fibrosis characterized by dilated distal air spaces and reduced type I collagen expression compared with wild-type controls. There is also a significant decrease in levels of active transforming growth factor-β1 and matrix metalloproteinase-2 in osteopontin null mice. Type III collagen expression and total collagenase activity are similar in both groups. These results demonstrate that osteopontin expression is associated with important fibrogenic signals in the lung and that the epithelium may be an important source of osteopontin during lung fibrosis.

PPARγ agonists inhibit TGF-β induced pulmonary myofibroblast differentiation and collagen production: implications for therapy of lung fibrosis

2005 ◽  
Vol 288 (6) ◽  
pp. L1146-L1153 ◽  
Author(s):  
Heather A. Burgess ◽  
Louis Eugene Daugherty ◽  
Thomas H. Thatcher ◽  
Heather F. Lakatos ◽  
Denise M. Ray ◽  
...  
Keyword(s):  
Pulmonary Fibrosis ◽  
Target Genes ◽  
Type I Collagen ◽  
Smooth Muscle Actin ◽  
Dominant Negative ◽  
Lung Fibroblasts ◽  
Peroxisome Proliferator ◽  
Type I ◽  
Myofibroblast Differentiation ◽  
Pparγ Agonists

Pulmonary fibrosis is a progressive life-threatening disease for which no effective therapy exists. Myofibroblasts are one of the key effector cells in pulmonary fibrosis and are the primary source of extracellular matrix production. Drugs that inhibit the differentiation of fibroblasts to myofibroblasts have potential as antifibrotic therapies. Peroxisome proliferator-activated receptor (PPAR)-γ is a transcription factor that upon ligation with PPARγ agonists activates target genes containing PPAR response elements. PPARγ agonists have anti-inflammatory activities and may have potential as antifibrotic agents. In this study, we examined the abilities of PPARγ agonists to block two of the most important profibrotic activities of TGF-β on pulmonary fibroblasts: myofibroblast differentiation and production of excess collagen. Both natural (15d-PGJ2) and synthetic (ciglitazone and rosiglitazone) PPARγ agonists inhibited TGF-β-driven myofibroblast differentiation, as determined by α-smooth muscle actin-specific immunocytochemistry and Western blot analysis. PPARγ agonists also potently attenuated TGF-β-driven type I collagen protein production. A dominant-negative PPARγ partially reversed the inhibition of myofibroblast differentiation by 15d-PGJ2 and rosiglitazone, but the irreversible PPARγ antagonist GW-9662 did not, suggesting that the antifibrotic effects of the PPARγ agonists are mediated through both PPARγ-dependent and independent mechanisms. Thus PPARγ agonists have novel and potent antifibrotic effects in human lung fibroblasts and may have potential for therapy of fibrotic diseases in the lung and other tissues.

Relationships between mesangial cell proliferation and types I and IV collagen mRNA levels in vitro

1995 ◽  
Vol 269 (3) ◽  
pp. C554-C562 ◽  
Author(s):  
C. J. He ◽  
L. J. Striker ◽  
M. Tsokos ◽  
C. W. Yang ◽  
E. P. Peten ◽  
...  
Keyword(s):  
Type I Collagen ◽  
Mesangial Cell ◽  
Mesangial Cells ◽  
Methyl Cellulose ◽  
Collagen Gel ◽  
Type I ◽  
Mrna Levels ◽  
Collagen Mrna ◽  
Type Iv

Changes in the composition of the mesangial extracellular matrix (ECM) and cell turnover are present in glomerular disease. To determine if ECM changes play a role in perpetuating mesangial cell dysfunction, we examined a line of mouse mesangial cells cultured on films or gels of several ECM components and also on methyl cellulose, an inert substrate that prevents attachment. Cells on films of fibronectin or type IV or I collagen had persistently high growth rates and high levels of alpha 1-I and alpha 1-IV collagen mRNAs. In contrast, on gels of type IV or I collagen or matrigel, the growth rate was low. The alpha 1-IV collagen mRNA levels were low on type IV collagen gel or matrigel, whereas the alpha 1-I collagen mRNA levels remained high. In contrast, the alpha 1-I collagen mRNA levels were low on type I collagen gel, and the alpha 1-IV collagen mRNA levels were high. Cells on methyl cellulose formed floating aggregates, did not proliferate, and had a 5- to 10-fold decrease in both alpha 1-I and alpha 1-IV collagen mRNA levels. These phenotypic changes were largely reversible. Finally, when matrigel was layered over cells on fibronectin films, alpha 1-IV collagen mRNA levels decreased, but alpha 1-I collagen mRNA levels and proliferation remained high. Thus proliferation and alpha 1-I and alpha 1-IV collagen mRNA levels in mesangial cells were independently regulated and depended on attachment and the nature of the adjacent matrix.

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