scholarly journals Fate-determining mechanisms in epithelial–myofibroblast transition: major inhibitory role for Smad3

2010 ◽  
Vol 188 (3) ◽  
pp. 383-399 ◽  
Author(s):  
András Masszi ◽  
Pam Speight ◽  
Emmanuel Charbonney ◽  
Monika Lodyga ◽  
Hiroyasu Nakano ◽  
...  
Keyword(s):  
Transforming Growth Factor ◽  
Nuclear Translocation ◽  
Smooth Muscle Actin ◽  
Transforming Growth Factor Β ◽  
Muscle Actin ◽  
Intercellular Contacts ◽  
Related Transcription Factor ◽  
Myogenic Program ◽  
Critical Process ◽  
Organ Fibrosis

Epithelial–myofibroblast (MF) transition (EMyT) is a critical process in organ fibrosis, leading to α–smooth muscle actin (SMA) expression in the epithelium. The mechanism underlying the activation of this myogenic program is unknown. We have shown previously that both injury to intercellular contacts and transforming growth factor β (TGF-β) are indispensable for SMA expression (two-hit model) and that contact disruption induces nuclear translocation of myocardin-related transcription factor (MRTF). Because the SMA promoter harbors both MRTF-responsive CC(A/T)-rich GG element (CArG) boxes and TGF-β–responsive Smad-binding elements, we hypothesized that the myogenic program is mobilized by a synergy between MRTF and Smad3. In this study, we show that the synergy between injury and TGF-β exclusively requires CArG elements. Surprisingly, Smad3 inhibits MRTF-driven activation of the SMA promoter, and Smad3 silencing renders injury sufficient to induce SMA expression. Furthermore, Smad3 is degraded under two-hit conditions, thereby liberating the myogenic program. Thus, Smad3 is a critical timer/delayer of MF commitment in the epithelium, and EMyT can be dissected into Smad3-promoted (mesenchymal) and Smad3-inhibited (myogenic) phases.

scholarly journals Smad2 and Smad3 Play Different Roles in Rat Hepatic Stellate Cell Function and α-Smooth Muscle Actin Organization

2005 ◽  
Vol 16 (9) ◽  
pp. 4214-4224 ◽  
Author(s):  
Masayuki Uemura ◽  
E. Scott Swenson ◽  
Marianna D.A. Gaça ◽  
Frank J. Giordano ◽  
Michael Reiss ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Transforming Growth Factor ◽  
Cell Function ◽  
Stellate Cell ◽  
Smooth Muscle Actin ◽  
Focal Adhesions ◽  
Transforming Growth Factor Β ◽  
Dominant Negative ◽  
Muscle Actin ◽  
Actin Organization

Hepatic stellate cells (HSC) play a central role in the pathogenesis of liver fibrosis, transdifferentiating in chronic liver disease from “quiescent” HSC to fibrogenic myofibroblasts. Transforming growth factor-β (TGF-β), acting both directly and indirectly, is a critical mediator of this process. To characterize the function of the TGF-β signaling intermediates Smad2 and Smad3 in HSC, we infected primary rat HSC in culture with adenoviruses expressing wild-type and dominant negative Smads 2 and 3. Smad3-overexpressing cells exhibited increased deposition of fibronectin and type 1 collagen, increased chemotaxis, and decreased proliferation compared with uninfected cells and those infected with Smad2 or either dominant negative, demonstrating different biological functions for the two Smads. Additionally, coinfection experiments suggested that Smad2 and Smad3 signal via independent pathways. Smad3-overexpressing cells as well as TGF-β-treated cells demonstrated more focal adhesions and increased α-smooth muscle actin (α-SMA) organization in stress fibers, although all cells reached the same level of α-SMA expression, indicating that Smad3 also regulates cytoskeletal organization in HSC. We suggest that TGF-β, signaling via Smad3, plays an important role in the morphological and functional maturation of hepatic myofibroblasts.

Differential regulation of TGFβ type-I receptor expressions in TGFβ1-induced myofibroblast differentiation

2020 ◽  
Vol 98 (12) ◽  
pp. 841-848
Author(s):  
Asma Gah ◽  
Mir S. Adil ◽  
Harika Sabbineni ◽  
Arti Verma ◽  
Payaningal R. Somanath
Keyword(s):  
Transforming Growth Factor ◽  
Smooth Muscle Actin ◽  
Transforming Growth Factor Β ◽  
Gene Expression Omnibus ◽  
Type I ◽  
Database Analysis ◽  
3T3 Fibroblasts ◽  
Nih 3T3 ◽  
Organ Fibrosis ◽  
Geo Database

Fibroblast-to-myofibroblast (FibroMF) differentiation is crucial for embryogenesis and organ fibrosis. Although transforming growth factor-β (TGFβ) is the primary mediator of FibroMF differentiation, the type-I receptor (TGFβRI) responsible for this has not yet been confirmed. In the current study, we investigated the ALK1 and ALK5 expressions in TGFβ1-stimulated NIH 3T3 fibroblasts to compare with the data from the Gene Expression Omnibus (GEO) repository. In our results, whereas TGFβ1 treatment promoted FibroMF differentiation accompanied by increased ALK5 expression and reduced ALK1 expression, TGFβ1-induced FibroMF differentiation and increased α-smooth muscle actin (αSMA) and ALK5 expression were inhibited by co-treatment with ALK5 inhibitor SB431542. GEO database analysis indicated increased ALK5 expression and reduced ALK1 expression in fibrotic compared to normal mouse or human tissues correlating with organ fibrosis progression. Finally, the inhibitors of Akt, mTOR, and β-catenin suppressed TGFβ1-induced ALK5 expression, indicating that the Akt pathway promotes FibroMF differentiation via ALK5 expression and fibrosis.

scholarly journals Nitro-oleic acid inhibits the high glucose-induced epithelial-mesenchymal transition in peritoneal mesothelial cells and attenuates peritoneal fibrosis

2020 ◽  
Vol 318 (2) ◽  
pp. F457-F467
Author(s):  
Wenyan Su ◽  
Haiping Wang ◽  
ZiYan Feng ◽  
Jing Sun
Keyword(s):  
Peritoneal Dialysis ◽  
Oleic Acid ◽  
Transforming Growth Factor ◽  
Epithelial Mesenchymal Transition ◽  
Smooth Muscle Actin ◽  
Transforming Growth Factor Β ◽  
Muscle Actin ◽  
Peritoneal Fibrosis ◽  
Mesenchymal Transition ◽  
Peritoneal Mesothelial Cells

As an electrophilic nitroalkene fatty acid, nitro-oleic acid (OA-NO2) exerts multiple biological effects that contribute to anti-inflammation, anti-oxidative stress, and antiapoptosis. However, little is known about the role of OA-NO2 in peritoneal fibrosis. Thus, in the present study, we examined the effects of OA-NO2 on the high glucose (HG)-induced epithelial-mesenchymal transition (EMT) in human peritoneal mesothelial cells (HPMCs) and evaluated the morphological and immunohistochemical changes in a rat model of peritoneal dialysis-related peritoneal fibrosis. In in vitro experiments, we found that HG reduced the expression level of E-cadherin and increased Snail, N-cadherin, and α-smooth muscle actin expression levels in HPMCs. The above-mentioned changes were attenuated by pretreatment with OA-NO2. Additionally, OA-NO2 also inhibited HG-induced activation of the transforming growth factor-β1/Smad signaling pathway and NF-κB signaling pathway. Meanwhile, OA-NO2 inhibited HG-induced phosphorylation of Erk and JNK. The results from the in vivo experiments showed that OA-NO2 notably relieved peritoneal fibrosis by decreasing the thickness of the peritoneum; it also inhibited expression of transforming growth factor-β1, α-smooth muscle actin, N-cadherin, and vimentin and enhanced expression of E-cadherin in the peritoneum. Collectively, these results suggest that OA-NO2 inhibits the HG-induced epithelial-mesenchymal transition in HPMCs and attenuates peritoneal dialysis-related peritoneal fibrosis.

scholarly journals Differential topical susceptibility to TGFβ in intact and injured regions of the epithelium: key role in myofibroblast transition

2013 ◽  
Vol 24 (21) ◽  
pp. 3326-3336 ◽  
Author(s):  
Pam Speight ◽  
Hiroyasu Nakano ◽  
Thomas J. Kelley ◽  
Boris Hinz ◽  
András Kapus
Keyword(s):  
Transforming Growth Factor ◽  
Smooth Muscle Actin ◽  
Retention Factor ◽  
Inhibitory Effect ◽  
Transforming Growth Factor Β1 ◽  
Cell Contact ◽  
Muscle Actin ◽  
Local Effects ◽  
Wound Model ◽  
Related Transcription Factor

Induction of epithelial–myofibroblast transition (EMyT), a robust fibrogenic phenotype change hallmarked by α-smooth muscle actin (SMA) expression, requires transforming growth factor-β1 (TGFβ) and the absence/uncoupling of intracellular contacts. This suggests that an “injured” epithelium may be topically susceptible to TGFβ. To explore this concept, we use an epithelial wound model in which intact and contact-deprived regions of the same monolayer can be analyzed simultaneously. We show that TGFβ elicits dramatically different responses at these two loci. SMA expression and initially enhanced nuclear Smad3 accumulation followed by Smad3 mRNA and protein down-regulation occur exclusively at the wound. Mechanistically, three transcriptional coactivators whose localization is regulated by cell contact integrity are critical for these local effects. These are myocardin-related transcription factor (MRTF), the driver of the SMA promoter; β-catenin, which counteracts the known inhibitory effect of Smad3 on MRTF and maintains MRTF protein stability and mRNA expression in the wound; and TAZ, a Hippo effector and Smad3 retention factor. Remarkably, active TAZ stimulates the SMA and suppresses the Smad3 promoter, whereas TAZ silencing prevents wound-restricted expression of SMA and loss of Smad3. Such locus-specific reprogramming might play key roles in wound healing and the susceptibility of the injured epithelium to fibrogenesis.

TNF-α neutralization ameliorates obstruction-induced renal fibrosis and dysfunction

2007 ◽  
Vol 292 (4) ◽  
pp. R1456-R1464 ◽  
Author(s):  
K. K. Meldrum ◽  
R. Misseri ◽  
P. Metcalfe ◽  
C. A. Dinarello ◽  
K. L. Hile ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Western Blot ◽  
Renal Fibrosis ◽  
Transforming Growth Factor ◽  
Smooth Muscle Actin ◽  
Transforming Growth Factor Β ◽  
Unilateral Ureteral Obstruction ◽  
Muscle Actin ◽  
Renal Obstruction ◽  
Tnf Α

Upper urinary tract obstruction results in tubulointerstitial fibrosis and a progressive decline in renal function. Although several inflammatory mediators have been implicated in the pathophysiology of renal obstruction, the contribution of TNF-α to obstruction-induced fibrosis and renal dysfunction has not been thoroughly evaluated. To study this, male Sprague-Dawley rats were subjected to left unilateral ureteral obstruction vs. sham operation. Rats received either vehicle or a pegylated form of soluble TNF receptor type 1 (PEG-sTNFR1) every 84 h. The kidneys were harvested 1, 3, or 7 days postoperatively, and tissue samples were analyzed for TNF-α expression (ELISA), macrophage infiltration (ED-1 staining), transforming growth factor-β1 expression (ELISA, RT-PCR), collagen I and IV activity (Western Blot, immunohistochemistry), α-smooth muscle actin accumulation (immunohistochemistry, Western blot analysis), and angiotensinogen expression (Western blot). In a separate arm, the glomerular filtration rate (inulin clearance) of rats subjected to unilateral ureteral obstruction in the presence of either vehicle or PEG-sTNFR1 was determined. Renal obstruction induced increased tissue TNF-α and transforming growth factor-β1 levels, collagen I and IV activity, interstitial volume, α-smooth muscle actin accumulation, angiotensinogen expression, and renal dysfunction, whereas treatment with PEG-sTNFR1 significantly reduced each of these markers of renal fibrosis. These results demonstrate that TNF-α mediates obstruction-induced renal fibrosis and identify TNF-α neutralization as a potential therapeutic option for the amelioration of obstruction-induced renal injury.

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