scholarly journals Impaired non‐canonical transforming growth factor‐β signalling prevents profibrotic phenotypes in cultured peptidylarginine deiminase 4‐deficient murine cardiac fibroblasts

Author(s):  
Hanane Akboua ◽  
Kaveh Eghbalzadeh ◽  
Ugur Keser ◽  
Thorsten Wahlers ◽  
Adnana Paunel‐Görgülü
2018 ◽  
Vol 315 (4) ◽  
pp. H745-H755 ◽  
Author(s):  
JoAnn Trial ◽  
Katarzyna A. Cieslik

The cardiac fibroblast plays a central role in tissue homeostasis and in repair after injury. With aging, dysregulated cardiac fibroblasts have a reduced capacity to activate a canonical transforming growth factor-β-Smad pathway and differentiate poorly into contractile myofibroblasts. That results in the formation of an insufficient scar after myocardial infarction. In contrast, in the uninjured aged heart, fibroblasts are activated and acquire a profibrotic phenotype that leads to interstitial fibrosis, ventricular stiffness, and diastolic dysfunction, all conditions that may lead to heart failure. There is an apparent paradox in aging, wherein reparative fibrosis is impaired but interstitial, adverse fibrosis is augmented. This could be explained by analyzing the effectiveness of signaling pathways in resident fibroblasts from young versus aged hearts. Whereas defective signaling by transforming growth factor-β leads to insufficient scar formation by myofibroblasts, enhanced activation of the ERK1/2 pathway may be responsible for interstitial fibrosis mediated by activated fibroblasts. Listen to this article's corresponding podcast at https://ajpheart.podbean.com/e/fibroblast-phenotypic-changes-in-the-aging-heart/ .


2019 ◽  
Vol 316 (3) ◽  
pp. H596-H608 ◽  
Author(s):  
Rachel C. Childers ◽  
Ian Sunyecz ◽  
T. Aaron West ◽  
Mary J. Cismowski ◽  
Pamela A. Lucchesi ◽  
...  

Hemodynamic load regulates cardiac remodeling. In contrast to pressure overload (increased afterload), hearts subjected to volume overload (VO; preload) undergo a distinct pattern of eccentric remodeling, chamber dilation, and decreased extracellular matrix content. Critical profibrotic roles of cardiac fibroblasts (CFs) in postinfarct remodeling and in response to pressure overload have been well established. Little is known about the CF phenotype in response to VO. The present study characterized the phenotype of primary cultures of CFs isolated from hearts subjected to 4 wk of VO induced by an aortocaval fistula. Compared with CFs isolated from sham hearts, VO CFs displayed a “hypofibrotic” phenotype, characterized by a ~50% decrease in the profibrotic phenotypic markers α-smooth muscle actin, connective tissue growth factor, and collagen type I, despite increased levels of profibrotic transforming growth factor-β1 and an intact canonical transforming growth factor-β signaling pathway. Actin filament dynamics were characterized, which regulate the CF phenotype in response to biomechanical signals. Actin polymerization was determined by the relative amounts of G-actin monomers versus F-actin. Compared with sham CFs, VO CFs displayed ~78% less F-actin and an increased G-actin-to-F-actin ratio (G/F ratio). In sham CFs, treatment with the Rho kinase inhibitor Y-27632 to increase the G/F ratio resulted in recapitulation of the hypofibrotic CF phenotype observed in VO CFs. Conversely, treatment of VO CFs with jasplakinolide to decrease the G/F ratio restored a more profibrotic response (>2.5-fold increase in α-smooth muscle actin, connective tissue growth factor, and collagen type I). NEW & NOTEWORTHY The present study is the first to describe a “hypofibrotic” phenotype of cardiac fibroblasts isolated from a volume overload model. Our results suggest that biomechanical regulation of actin microfilament stability and assembly is a critical mediator of cardiac fibroblast phenotypic modulation.


2010 ◽  
Vol 87 (4) ◽  
pp. 647-655 ◽  
Author(s):  
Sashwati Roy ◽  
Savita Khanna ◽  
Ali Azad ◽  
Rebecca Schnitt ◽  
Guanglong He ◽  
...  

2018 ◽  
Vol 315 (3) ◽  
pp. H658-H668 ◽  
Author(s):  
Danah S. Al-Hattab ◽  
Hamza A. Safi ◽  
Raghu S. Nagalingam ◽  
Rushita A. Bagchi ◽  
Matthew T. Stecy ◽  
...  

Numerous physiological and pathological events, from organ development to cancer and fibrosis, are characterized by an epithelial-to-mesenchymal transition (EMT), whereby adherent epithelial cells convert to migratory mesenchymal cells. During cardiac development, proepicardial organ epithelial cells undergo EMT to generate fibroblasts. Subsequent stress or damage induces further phenotype conversion of fibroblasts to myofibroblasts, causing fibrosis via synthesis of an excessive extracellular matrix. We have previously shown that the transcription factor scleraxis is both sufficient and necessary for the conversion of cardiac fibroblasts to myofibroblasts and found that scleraxis knockout reduced cardiac fibroblast numbers by 50%, possibly via EMT attenuation. Scleraxis induced expression of the EMT transcriptional regulators Twist1 and Snai1 via an unknown mechanism. Here, we report that scleraxis binds to E-box consensus sequences within the Twist1 and Snai1 promoters to transactivate these genes directly. Scleraxis upregulates expression of both genes in A549 epithelial cells and in cardiac myofibroblasts. Transforming growth factor-β induces EMT, fibrosis, and scleraxis expression, and we found that transforming growth factor-β-mediated upregulation of Twist1 and Snai1 completely depends on the presence of scleraxis. Snai1 knockdown upregulated the epithelial marker E-cadherin; however, this effect was lost after scleraxis overexpression, suggesting that scleraxis may repress E-cadherin expression. Together, these results indicate that scleraxis can regulate EMT via direct transactivation of the Twist1 and Snai1 genes. Given the role of scleraxis in also driving the myofibroblast phenotype, scleraxis appears to be a critical controller of fibroblast genesis and fate in the myocardium and thus may play key roles in wound healing and fibrosis. NEW & NOTEWORTHY The molecular mechanism by which the transcription factor scleraxis mediates Twist1 and Snai1 gene expression was determined. These results reveal a novel means of transcriptional regulation of epithelial-to-mesenchymal transition and demonstrate that transforming growth factor-β-mediated epithelial-to-mesenchymal transition is dependent on scleraxis, providing a potential target for controlling this process.


Hypertension ◽  
2001 ◽  
Vol 38 (2) ◽  
pp. 261-266 ◽  
Author(s):  
Nadia Abdelaziz ◽  
Federico Colombo ◽  
Isabelle Mercier ◽  
Angelino Calderone

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Shaukat A Khan ◽  
Takeshi Tsuda

Introduction: Transforming growth factor (TGF)-β is a potent growth factor that induces myocardial hypertrophy, but an interaction between circulating and myocardial TGF-β has been poorly understood. An extracellular matrix protein, fibulin-2, mediates exogenous TGF-β-induced endogenous TGF-β up-regulation in isolated cardiac fibroblasts. Hypothesis: Systemic TGF-β-induced myocardial hypertrophy is mediated primarily by enhanced myocardial TGF-β via paracrine fashion. Methods: We created double mutant mice with TGF-β1 over-expressing transgenic mice (TG) and fibulin-2 knockout mice (KO). TG developed myocardial hypertrophy due to excessive circulating hepatic TGF-β. We studied TGF-β dynamics between tissues and circulation during hypertrophic changes. Results: TG/WT developed significant myocardial hypertrophy at 8 weeks compared with non-TG (NTG) groups. Hypertrophy in TG/KO was significantly attenuated compared with TG/WT. Myocardial TGF-β mRNA level was significantly up-regulated in TG/WT compared with TG/KO or NGT groups, so was Smad2 activation, but myocardial TGF-β bioactivity was no different among all four groups. Serum carrier-bound TGF-β was significantly higher in TG/WT than in TG/KO or NTG groups, but free unbound TGF-β level was equally elevated in TG groups compared with NTG groups. Thus, hypertrophy in TG/WT may be attributed to increased serum carrier-bound TGF-β levels, not to either myocardial TGF-β activity or serum unbound TGF-β levels. Endogenous TGF-β mRNA level in kidney and liver was equally increased in TG group compared with NTG group, and was comparable in all 4 groups in lung, suggesting fibulin-2 was not involved in TGF-β-induced TGF-β synthesis in kidney, liver, or lung. Conclusions: Hepatic TGF-β-induced-myocardial TGF-β up-regulation was mediated by fibulin-2. In TG/WT, up-regulated myocardial TGF-β was mainly secreted into circulation as a soluble carrier-bound form and did not directly induce hypertrophy via paracrine fashion. It is this circulating endogenous myocardial TGF-β rather than transgene-induced hepatic TGF-β that is responsible for myocardial hypertrophy in TG/WT. Heart is a major endocrine organ in secreting circulating endogenous TGF-β in inducing myocardial hypertrophy.


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