scholarly journals The ER Unfolded Protein Response Effector, ATF6, Reduces Cardiac Fibrosis and Decreases Activation of Cardiac Fibroblasts

2020 ◽  
Vol 21 (4) ◽  
pp. 1373
Author(s):  
Winston T. Stauffer ◽  
Erik A. Blackwood ◽  
Khalid Azizi ◽  
Randal J. Kaufman ◽  
Christopher C. Glembotski
Keyword(s):  
Cardiac Fibrosis ◽  
Transforming Growth Factor ◽  
Cardiac Fibroblasts ◽  
Smooth Muscle Actin ◽  
Transforming Growth Factor Β ◽  
Cell Types ◽  
Unfolded Protein ◽  
Disease States ◽  
Activating Transcription Factor ◽  
Protein Response

Activating transcription factor-6 α (ATF6) is one of the three main sensors and effectors of the endoplasmic reticulum (ER) stress response and, as such, it is critical for protecting the heart and other tissues from a variety of environmental insults and disease states. In the heart, ATF6 has been shown to protect cardiac myocytes. However, its roles in other cell types in the heart are unknown. Here we show that ATF6 decreases the activation of cardiac fibroblasts in response to the cytokine, transforming growth factor β (TGFβ), which can induce fibroblast trans-differentiation into a myofibroblast phenotype through signaling via the TGFβ–Smad pathway. ATF6 activation suppressed fibroblast contraction and the induction of α smooth muscle actin (αSMA). Conversely, fibroblasts were hyperactivated when ATF6 was silenced or deleted. ATF6 thus represents a novel inhibitor of the TGFβ–Smad axis of cardiac fibroblast activation.

scholarly journals The AP-1 Transcription Factor Fosl-2 Regulates Autophagy in Cardiac Fibroblasts during Myocardial Fibrogenesis

2021 ◽  
Vol 22 (4) ◽  
pp. 1861
Author(s):  
Jemima Seidenberg ◽  
Mara Stellato ◽  
Amela Hukara ◽  
Burkhard Ludewig ◽  
Karin Klingel ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Molecular Mechanisms ◽  
Cardiac Fibrosis ◽  
Type I Collagen ◽  
Transforming Growth Factor ◽  
Cardiac Fibroblasts ◽  
Smooth Muscle Actin ◽  
Beclin 1 ◽  
Type I ◽  
Alpha Smooth Muscle Actin

Background: Pathological activation of cardiac fibroblasts is a key step in development and progression of cardiac fibrosis and heart failure. This process has been associated with enhanced autophagocytosis, but molecular mechanisms remain largely unknown. Methods and Results: Immunohistochemical analysis of endomyocardial biopsies showed increased activation of autophagy in fibrotic hearts of patients with inflammatory cardiomyopathy. In vitro experiments using mouse and human cardiac fibroblasts confirmed that blockade of autophagy with Bafilomycin A1 inhibited fibroblast-to-myofibroblast transition induced by transforming growth factor (TGF)-β. Next, we observed that cardiac fibroblasts obtained from mice overexpressing transcription factor Fos-related antigen 2 (Fosl-2tg) expressed elevated protein levels of autophagy markers: the lipid modified form of microtubule-associated protein 1A/1B-light chain 3B (LC3BII), Beclin-1 and autophagy related 5 (Atg5). In complementary experiments, silencing of Fosl-2 with antisense GapmeR oligonucleotides suppressed production of type I collagen, myofibroblast marker alpha smooth muscle actin and autophagy marker Beclin-1 in cardiac fibroblasts. On the other hand, silencing of either LC3B or Beclin-1 reduced Fosl-2 levels in TGF-β-activated, but not in unstimulated cells. Using a cardiac hypertrophy model induced by continuous infusion of angiotensin II with osmotic minipumps, we confirmed that mice lacking either Fosl-2 (Ccl19CreFosl2flox/flox) or Atg5 (Ccl19CreAtg5flox/flox) in stromal cells were protected from cardiac fibrosis. Conclusion: Our findings demonstrate that Fosl-2 regulates autophagocytosis and the TGF-β-Fosl-2-autophagy axis controls differentiation of cardiac fibroblasts. These data provide a new insight for the development of pharmaceutical targets in cardiac fibrosis.

Aucubin Protects against TGFβ1-Induced Cardiac Fibroblasts Activation by Mediating the AMPKα/mTOR Signaling Pathway

Planta Medica ◽  
2017 ◽  
Vol 84 (02) ◽  
pp. 91-99 ◽  
Author(s):  
Yang Xiao ◽  
Wei Chang ◽  
Qing-Qing Wu ◽  
Xiao-Han Jiang ◽  
Ming-Xia Duan ◽  
...  
Keyword(s):  
Cardiac Fibrosis ◽  
Transforming Growth Factor ◽  
Cardiac Fibroblasts ◽  
Smooth Muscle Actin ◽  
Mammalian Target Of Rapamycin ◽  
Transforming Growth Factor Β1 ◽  
Neonatal Rat ◽  
Cell Counting ◽  
Compound C ◽  
Underlying Mechanisms

AbstractFibrosis is a key feature of various cardiovascular diseases and compromises cardiac systolic and diastolic performance. The lack of effective anti-fibrosis drugs is a major contributor to the increasing prevalence of heart failure. The present study was performed to investigate whether the iridoid aucubin alleviates cardiac fibroblast activation and its underlying mechanisms. Neonatal rat cardiac fibroblasts were incubated with aucubin (1, 10, 20, 50 µM) followed by transforming growth factor β1 (TGFβ1, 10 ng/mL) stimulation for 24 h. Fibrosis proliferation was measured by cell counting kit-8 assay. The differentiation of fibroblasts into myofibroblasts was determined by measuring the expression of α-smooth muscle actin. Then, the expressions levels of cardiac fibrosis-related proteins in myofibroblasts were analyzed by western blot and real-time PCR to confirm the anti-fibrosis effect of aucubin. As a result, aucubin suppressed TGFβ1-induced proliferation in fibroblasts and inhibited the TGFβ1-induced activation of fibroblasts to myofibroblasts. In addition, aucubin further attenuated fibrosis-related protein expression in myofibroblasts. Furthermore, this protective effect was related to increased adenosine 5′-monophosphate-activated protein kinase (AMPK) phosphorylation and decreased mammalian target of rapamycin (mTOR) phosphorylation, which was confirmed by an mTOR inhibitor (rapamycin), an AMPK agonist (AICAR) and an AMPKα inhibitor compound C. Collectively, our findings suggest that aucubin protects against TGFβ1-induced fibroblast proliferation, activation and function by regulating the AMPKα/mTOR signal axis.

GHSR deficiency exacerbates cardiac fibrosis: role in macrophage inflammasome activation and myofibroblast differentiation

2019 ◽  
Vol 116 (13) ◽  
pp. 2091-2102 ◽  
Author(s):  
Mo Wang ◽  
Lei Qian ◽  
Jing Li ◽  
Hao Ming ◽  
Li Fang ◽  
...  
Keyword(s):  
Cardiac Fibrosis ◽  
Transforming Growth Factor ◽  
Cardiac Fibroblasts ◽  
Cardiovascular Effects ◽  
Transforming Growth Factor Β ◽  
Underlying Mechanism ◽  
Marker Genes ◽  
Inflammasome Activation ◽  
Growth Hormone Secretagogue Receptor ◽  
Growth Hormone Secretagogue

Abstract Aims Sustained activation of β-adrenergic signalling induces cardiac fibrosis, which marks progression to heart failure. GHSR (growth hormone secretagogue receptor) is the receptor for ghrelin, which is an orexigenic gastric hormone with newly defined cardiovascular effects. The present study determined the effects of GHSR deficiency in a mouse model of isoproterenol (ISO)-induced cardiac fibrosis and examined the underlying mechanism. Methods and results Histochemical studies showed that GHSR deficiency exacerbated cardiac fibrosis. Quantitative RT–PCR, western blotting, and immunofluorescence staining demonstrated that cardiac fibroblasts isolated from GHSR−/− mice exhibited increased expression of marker genes for myofibroblast trans-differentiation (α-SMA, SM22, and calponin) upon transforming growth factor-β treatment compared to wild-type mice. RNA-sequencing of heart transcriptomes revealed that differentially expressed genes in GHSR−/− hearts were enriched in such biological processes as extracellular matrix organization, inflammatory response, lipid metabolism, cell cycle, migration, and adhesion. Particularly, GHSR deficiency increased Wnt/β-catenin pathway activation in ISO-induced myocardial fibrosis. In addition, loss of GHSR in macrophages instigated inflammasome activation with increased cleavage and release of interleukin-18. Conclusion These results for the first time demonstrated that GHSR deficiency aggravated ISO-induced cardiac fibrosis, suggesting that GHSR was a potential target for the intervention of cardiac fibrosis.

scholarly journals Role of the cytoskeleton in the development of a hypofibrotic cardiac fibroblast phenotype in volume overload heart failure

2019 ◽  
Vol 316 (3) ◽  
pp. H596-H608 ◽  
Author(s):  
Rachel C. Childers ◽  
Ian Sunyecz ◽  
T. Aaron West ◽  
Mary J. Cismowski ◽  
Pamela A. Lucchesi ◽  
...  
Keyword(s):  
Growth Factor ◽  
Transforming Growth Factor ◽  
Cardiac Fibroblasts ◽  
Smooth Muscle Actin ◽  
Pressure Overload ◽  
Volume Overload ◽  
Transforming Growth Factor Β ◽  
Collagen Type I ◽  
Tissue Growth ◽  
Type I

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.

scholarly journals Myofibroblasts and Fibrosis

2020 ◽  
Vol 127 (3) ◽  
pp. 427-447
Author(s):  
Andrew A. Gibb ◽  
Michael P. Lazaropoulos ◽  
John W. Elrod
Keyword(s):  
Physiological Response ◽  
Cardiac Fibrosis ◽  
Transforming Growth Factor ◽  
Cardiac Fibroblasts ◽  
Functional Decline ◽  
Transforming Growth Factor Β ◽  
Acute Injury ◽  
Myofibroblast Differentiation ◽  
And Function ◽  
Organ Fibrosis

Cardiac fibrosis is mediated by the activation of resident cardiac fibroblasts, which differentiate into myofibroblasts in response to injury or stress. Although myofibroblast formation is a physiological response to acute injury, such as myocardial infarction, myofibroblast persistence, as occurs in heart failure, contributes to maladaptive remodeling and progressive functional decline. Although traditional pathways of activation, such as TGFβ (transforming growth factor β) and AngII (angiotensin II), have been well characterized, less understood are the alterations in mitochondrial function and cellular metabolism that are necessary to initiate and sustain myofibroblast formation and function. In this review, we highlight recent reports detailing the mitochondrial and metabolic mechanisms that contribute to myofibroblast differentiation, persistence, and function with the hope of identifying novel therapeutic targets to treat, and potentially reverse, tissue organ fibrosis.

scholarly journals Autophagy and the unfolded protein response promote profibrotic effects of TGF-β1 in human lung fibroblasts

2018 ◽  
Vol 314 (3) ◽  
pp. L493-L504 ◽  
Author(s):  
Saeid Ghavami ◽  
Behzad Yeganeh ◽  
Amir A. Zeki ◽  
Shahla Shojaei ◽  
Nicholas J. Kenyon ◽  
...  
Keyword(s):  
Unfolded Protein Response ◽  
Transforming Growth Factor ◽  
Treatment Options ◽  
Transforming Growth Factor Β ◽  
Lung Fibroblasts ◽  
Protein Markers ◽  
Unfolded Protein ◽  
The Unfolded Protein Response ◽  
Protein Response ◽  
Tgf Β1

Idiopathic pulmonary fibrosis (IPF) is a lethal fibrotic lung disease in adults with limited treatment options. Autophagy and the unfolded protein response (UPR), fundamental processes induced by cell stress, are dysregulated in lung fibroblasts and epithelial cells from humans with IPF. Human primary cultured lung parenchymal and airway fibroblasts from non-IPF and IPF donors were stimulated with transforming growth factor-β1 (TGF-β1) with or without inhibitors of autophagy or UPR (IRE1 inhibitor). Using immunoblotting, we monitored temporal changes in abundance of protein markers of autophagy (LC3βII and Atg5-12), UPR (BIP, IRE1α, and cleaved XBP1), and fibrosis (collagen 1α2 and fibronectin). Using fluorescent immunohistochemistry, we profiled autophagy (LC3βII) and UPR (BIP and XBP1) markers in human non-IPF and IPF lung tissue. TGF-β1-induced collagen 1α2 and fibronectin protein production was significantly higher in IPF lung fibroblasts compared with lung and airway fibroblasts from non-IPF donors. TGF-β1 induced the accumulation of LC3βII in parallel with collagen 1α2 and fibronectin, but autophagy marker content was significantly lower in lung fibroblasts from IPF subjects. TGF-β1-induced collagen and fibronectin biosynthesis was significantly reduced by inhibiting autophagy flux in fibroblasts from the lungs of non-IPF and IPF donors. Conversely, only in lung fibroblasts from IPF donors did TGF-β1 induce UPR markers. Treatment with an IRE1 inhibitor decreased TGF-β1-induced collagen 1α2 and fibronectin biosynthesis in IPF lung fibroblasts but not those from non-IPF donors. The IRE1 arm of the UPR response is uniquely induced by TGF-β1 in lung fibroblasts from human IPF donors and is required for excessive biosynthesis of collagen and fibronectin in these cells.

Abstract 430: Immature Cardiac Fibroblasts With Upregulated P53 Contributed to Fibrosis in Ikke Deficient Mouse Myocardial Infarction Model

2020 ◽  
Vol 127 (Suppl_1) ◽  
Author(s):  
Yong Sook Kim ◽  
Hyang Hee Cho ◽  
Ju Hee Jun ◽  
Dong Im Cho ◽  
Meeyoung Cho ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Cardiac Fibrosis ◽  
Transforming Growth Factor ◽  
Inflammatory Responses ◽  
Cardiac Fibroblasts ◽  
Smooth Muscle Actin ◽  
Healing Process ◽  
Wound Healing Process ◽  
Coronary Artery Ligation ◽  
Artery Ligation

Background: Inhibitor of NF-κB kinase (IKK), an upstream of nuclear factor-kappa B (NF-κB), is a critical modulator for pathophysiological inflammation. IKKε is a non-classical IKK and has been studied in infectious diseases and cancers. However, the role of IKKε in a myocardial infarction (MI) has not been addressed. Methods and Results: In this study, we used IKKε knockout (KO) mice to induce MI by coronary artery ligation. The IKKε KO group showed poor early survival rate, large cardiac fibrosis (14.7±4.8% in KO vs. 31.1±10.2% in WT, p <0.05), and low fractional shortening (13.47±1.21% in KO vs. 16.36±4.46% in WT, p <0.05) compared with WT group. Next, we investigated the inflammatory responses and found that inflammatory markers such as inducible nitric oxide synthase (iNOS) and CD80 were much higher in both cardiac macrophages and bone marrow-derived macrophages (BMDM) in the IKKε KO group than in the wild type (WT) group. To explore the responsible mediator, we performed phosphorylated protein array and found phosphorylated p38 was significantly downregulated in the IKKε knockout BMDM. Conversely, both knockdown of p38 by siRNA and inhibition of p38 by SB203580 treatment in RAW264.7 cells upregulated iNOS. More interestingly, IKKε deficient cardiac fibroblasts showed highly accumulated nuclear p53 and exhibited immature differentiation. The levels of myofibroblast markers containing α-smooth muscle actin, periostin, and transforming growth factor-β1 were lower, and functional contractility was substantially impaired in the cardiac fibroblasts isolated from IKKε KO mice. Conclusion: Our data showed excessive inflammation was associated with p38 inactivation in macrophages and pathological fibrosis was resulted from immature myofibroblast phenotype with p53 upregulation. Collectively, IKKε is involved in the control of inflammation resolution and wound healing process in the infarcted myocardium.

scholarly journals Calpain 9 as a therapeutic target in TGFβ-induced mesenchymal transition and fibrosis

2019 ◽  
Vol 11 (501) ◽  
pp. eaau2814 ◽  
Author(s):  
David H. Kim ◽  
James D. Beckett ◽  
Varun Nagpal ◽  
Manuel A. Seman-Senderos ◽  
Russell A. Gould ◽  
...  
Keyword(s):  
Cardiac Fibrosis ◽  
Transforming Growth Factor ◽  
Transforming Growth Factor Β ◽  
Cell Types ◽  
Cysteine Proteases ◽  
Breast Epithelial Cell ◽  
Epithelial Cell Line ◽  
Loss Of Function ◽  
Mesenchymal Transition ◽  
Breast Epithelial Cell Line

Fibrosis is a common pathologic outcome of chronic disease resulting in the replacement of normal tissue parenchyma with a collagen-rich extracellular matrix produced by myofibroblasts. Although the progenitor cell types and cellular programs giving rise to myofibroblasts through mesenchymal transition can vary between tissues and diseases, their contribution to fibrosis initiation, maintenance, and progression is thought to be pervasive. Here, we showed that the ability of transforming growth factor–β (TGFβ) to efficiently induce myofibroblast differentiation of cultured epithelial cells, endothelial cells, or quiescent fibroblasts is dependent on the induced expression and activity of dimeric calpains, a family of non-lysosomal cysteine proteases that regulate a variety of cellular events through posttranslational modification of diverse substrates. siRNA-based gene silencing demonstrated that TGFβ-induced mesenchymal transition of a murine breast epithelial cell line was dependent on induction of expression of calpain 9 (CAPN9), an isoform previously thought to be restricted to the gastrointestinal tract. Mice lacking functional CAPN9 owing to biallelic targeting of Capn9 were viable and fertile but showed overt protection from bleomycin-induced lung fibrosis, carbon tetrachloride–induced liver fibrosis, and angiotensin II–induced cardiac fibrosis and dysfunction. A predicted loss-of-function allele of CAPN9 is common in Southeast Asia, with the frequency of homozygosity matching the prediction of Hardy-Weinberg equilibrium. Together with the highly spatially restricted pattern of CAPN9 expression under physiologic circumstances and the heartiness of the murine knockout, these data provide a strong signature for tolerance of therapeutic strategies for fibrosis aimed at CAPN9 antagonism.

scholarly journals Retinoid X receptor agonists attenuates cardiomyopathy in streptozotocin-induced type 1 diabetes through LKB1-dependent anti-fibrosis effects

2020 ◽  
Vol 134 (6) ◽  
pp. 609-628 ◽  
Author(s):  
Dajun Chai ◽  
Xiaoyan Lin ◽  
Qiaowen Zheng ◽  
Changsheng Xu ◽  
Hong Xie ◽  
...  
Keyword(s):  
Myocardial Fibrosis ◽  
Cardiac Fibrosis ◽  
Transforming Growth Factor ◽  
Cardiac Fibroblasts ◽  
Transforming Growth Factor Β ◽  
Underlying Mechanism ◽  
Left Ventricular ◽  
Retinoid X Receptor ◽  
Sprague Dawley

Abstract Diabetic cardiac fibrosis increases ventricular stiffness and facilitates the occurrence of diastolic dysfunction. Retinoid X receptor (RXR) plays an important role in cardiac development and has been implicated in cardiovascular diseases. In the present study, we investigated the effects of RXR agonist treatment on streptozotocin (STZ)-induced diabetic cardiomyopathy (DCM) and the underlying mechanism. Sprague–Dawley (SD) rats induced by STZ injection were treated with either RXR agonist bexarotene (Bex) or vehicle alone. Echocardiography was performed to determine cardiac structure and function. Cardiac fibroblasts (CFs) were treated with high glucose (HG) with or without the indicated concentration of Bex or the RXR ligand 9-cis-retinoic acid (9-cis-RA). The protein abundance levels were measured along with collagen, body weight (BW), blood biochemical indexes and transforming growth factor-β (TGF-β) levels. The effects of RXRα down-regulation by RXRα small interfering RNA (siRNA) were examined. The results showed that bexarotene treatment resulted in amelioration of left ventricular dysfunction by inhibiting cardiomyocyte apoptosis and myocardial fibrosis. Immunoblot with heart tissue homogenates from diabetic rats revealed that bexarotene activated liver kinase B1 (LKB1) signaling and inhibited p70 ribosomal protein S6 kinase (p70S6K). The increased collagen levels in the heart tissues of DCM rats were reduced by bexarotene treatment. Treatment of CFs with HG resulted in significantly reduced LKB1 activity and increased p70S6K activity. RXRα mediated the antagonism of 9-cis-RA on HG-induced LKB1/p70S6K activation changes in vitro. Our findings suggest that RXR agonist ameliorates STZ-induced DCM by inhibiting myocardial fibrosis via modulation of the LKB1/p70S6K signaling pathway. RXR agonists may serve as novel therapeutic agents for the treatment of DCM.

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