Abstract 13837: Adrenergic Receptors β2 and β3 Transduce Differential Signals in Cardiac Fibroblasts

Background: Cardiac fibroblasts (CFs) are the most prevalent cell types in heart and play important roles in cardiac remodeling. While the roles of β-adrenergic receptor (βAR) signaling in cardiomyocytes (CMs) are well characterized, those in CFs remain to be elusive due to lack of convenient method to assess those signaling. There are three subtypes of, βAR β1, β2, β3 and β2AR is reported to be expressed in CFs by which enhances cell proliferation and production of inflammatory cytokines. Clinical efficacy of non-selective β blocker carvedilol for heart failure (HF) surpasses that of β1 selective blocker metoprolol, suggesting critical roles of β2 and β3AR in the pathogenesis of HF. Objective: To elucidate the signaling downstream βARs in CFs in heart. Methods and Results: Caveolae is an important microdomain for signal transduction, such as βAR, present in CMs or CFs. To elucidate βAR signaling of caveolae in CFs, we generated a fusion protein composed of phospholamban (PLN) and caveolin3 (Cav3) representing PKA activation as phosphorylation at S16 of PLN and CaMKII as that at T17 in caveolae. Thus, activation of PKA or CaMKII is detectable by anti-phospho-S16 or T17 antibody, respectively. In neonatal rat CFs (NRCFs) infected PLN-Cav3 adenovirus, stimulation by isoproterenol (ISO) led to enhanced phosphorylation of both S16 and T17, suggesting PKA and CaMKII activation in caveolae of CFs. RT-PCR analyses showed β2AR and β3AR were present in NRCFs. Stimulation with β2AR selective agonists activated both PKA and CaMKII, while β3AR elicited solely PKA activation, analyzed by using β3AR selective agonist/antagonist. In addition, in order to examine the significance of βAR stimulation for heart failure, we administered ISO continuously for two weeks in β2ARKO mice. As a result, fibrosis was suppressed in β2ARKO mice compared with wild-type mice (0.35% vs 2.37%, p<0.05) suggesting critical roles of β2AR in development of cardiac fibrosis caused by βAR stimulation in mice. Conclusions: Both β2 and β3AR are expressed in NRCFs and transduce distinct signaling and β2AR selective stimulation elicit development of cardiac fibrosis via activation of CaMKII signaling. Thus, selective βAR regulation could be potential novel anti-fibrotic therapeutics in HF.

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Abstract 370: MicroRNA-19b Contributes to Cardiac Fibrosis

Circulation Research ◽

10.1161/res.117.suppl_1.370 ◽

2015 ◽

Vol 117 (suppl_1) ◽

Author(s):

Ping Chen ◽

Dongchao Lv ◽

Jiahong Xu ◽

Qiulian Zhou ◽

Qi Sun ◽

...

Keyword(s):

Heart Failure ◽

Cardiac Fibrosis ◽

Cardiac Fibroblasts ◽

Suppressor Gene ◽

Tissue Growth ◽

Neonatal Rat ◽

Cell Counting ◽

Mrna Levels ◽

And Migration ◽

Proliferation And Migration

Fibrosis is one of the most important characteristics of cardiac remodeling during heart failure. The accumulation of extracellular matrix (ECM) within myocardium is the major feature of cardiac fibrosis. microRNA (miR)-19b, a key functional member of miR-19-72 cluster family, has been suggested to be involved in aging-induced heart failure through regulating ECM-related proteins, such as connective tissue growth factor (CTGF), thrombospondin-1 (TSP-1), collagen-1A1, and collagen-3A1. In the current study, we aimed to investigate the role of miR-19b in cardiac fibroblast function and ECM production using neonatal rat cardiac fibroblasts in primary culture. We found that overexpression of miR-19b increased, while inhibition of miR-19b decreased the proliferation and migration of cardiac fibroblasts, using Cell Counting Kit-8 (CCK-8) (0.660±0.019 vs 0.720±0.014 in nc-mimic and miR-19b mimic, 0.506±0.009 vs 0.454±0.008 in nc-inhibitor and miR-19b inhibitor, respectively), EdU incorporation assay (0.059±0.002 vs 0.096±0.006 in nc-mimic and miR-19b mimic, 0.059±0.006 vs 0.040±0.003 in nc-inhibitor and miR-19b inhibitor, respectively), and wound healing assay (0.528±0.024 vs 0.896±0.027 in nc-mimic and miR-19b mimic,0.520±0.028 vs 0.174±0.019 in nc-inhibitor and miR-19b inhibitor, respectively), respectively. Meanwhile, the inhibition of miR-19b downregulated the mRNA levels of α-SMA (0.556±0.048 vs 1.038±0.137 in nc-inhibitor and miR-19b inhibitor, respectively) and collagen-1 (1.023±0.116 vs 0.551±0.033 in nc-inhibitor and miR-19b inhibitor, respectively) in cardiac fibroblasts, indicating a reduction in fibroblast activation and ECM production via miR-19b inhibition. Furthermore, we found that PTEN was negatively regulated by miR-19b in cardiac fibroblasts using western blot analysis. PTEN, a well-known tumor-suppressor gene, has been known to inhibit cell proliferation and migration. However, it remains to be further clarified whether PTEN could mediate the effect of miR-19b in the proliferation, migration and activation of fibroblasts. These data might provide important evidence suggesting that miR-19b could be a potential therapeutic target for cardiac fibrosis.

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Prevention of Fibrosis and Pathological Cardiac Remodeling by Salinomycin

Circulation Research ◽

10.1161/circresaha.120.317791 ◽

2021 ◽

Author(s):

Ryan M Burke ◽

Ronald A Dirkx, Jr. ◽

Pearl Quijada ◽

Janet K Lighthouse ◽

Amy Mohan ◽

...

Keyword(s):

Heart Failure ◽

Mouse Models ◽

Cardiac Remodeling ◽

Cardiac Fibrosis ◽

Cardiac Fibroblasts ◽

Functional Decline ◽

Cell Types ◽

Ischemic Heart ◽

Interventional Treatment ◽

Heart Failure Patients

Rationale: Cardiomyopathy is characterized by the deposition of extracellular matrix by activated resident cardiac fibroblasts, called myofibroblasts. There are currently no therapeutic approaches to blunt the development of pathological fibrosis and ventricle chamber stiffening that ultimately leads to heart failure. Objective: We undertook a high-throughput screen to identify small molecule inhibitors of myofibroblast activation that might limit the progression of heart failure. We evaluated the therapeutic efficacy of the polyether ionophore salinomycin in patient derived cardiac fibroblasts and pre-clinical mouse models of ischemic and non-ischemic heart failure. Methods and Results: Here, we demonstrate that salinomycin displays potent anti-fibrotic activity in cardiac fibroblasts obtained from heart failure patients. In pre-clinical studies, salinomycin prevents cardiac fibrosis and functional decline in mouse models of ischemic and non-ischemic heart disease. Remarkably, interventional treatment with salinomycin attenuates pre-established pathological cardiac remodeling secondary to hypertension, and limits scar expansion when administered after a severe myocardial infarction. Mechanistically, salinomycin inhibits cardiac fibroblast activation by preventing p38/MAPK and Rho signaling. Salinomycin also promotes cardiomyocyte survival and improves coronary vessel density, suggesting that cardioprotection conferred by salinomycin occurs via the integration of multiple mechanisms in multiple relevant cardiac cell types. Conclusions: These data establish salinomycin as an anti-fibrotic agent that targets multiple cardioprotection pathways, thereby holding promise for the treatment of heart failure patients.

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Abstract 173: Expanded Role for Thrombin/PAR1 Signaling in Cardiac Fibroblast Activation

Circulation Research ◽

10.1161/res.111.suppl_1.a173 ◽

2012 ◽

Vol 111 (suppl_1) ◽

Author(s):

Aaron N Snead ◽

Paul A Insel

Keyword(s):

Heart Failure ◽

Wound Repair ◽

Cardiac Fibrosis ◽

Morphological Changes ◽

Cardiac Fibroblasts ◽

Acute Injury ◽

Rt Pcr ◽

Adult Rat ◽

Developing Heart ◽

Cardiovascular Cells

Cardiac fibrosis is a feature of numerous types of heart disease that lead to disability and death and is characterized by the transformation of cardiac fibroblasts (CFs) to myofibroblasts (myofibs) that synthesize and release large amounts of collagen-rich extracellular matrix (ECM), thereby resulting in reduced cardiac function and eventually heart failure. CFs are the most abundant cell type in the heart and regulate the production of ECM as a normal part of wound repair but disease can result if CFs become overactive, at least in part by increased transformation to myofibs. Cardiac fibrosis can occur spontaneously in advanced age, after acute injury (e.g., myocardial infarction) and in disease states (e.g., diabetes mellitus and heart failure). We sought to identify novel therapeutic targets for cardiac fibrosis by using an unbiased approach (RT-PCR array) to define the most abundantly expressed G protein-coupled receptors (GPCRs) predicted to regulate the CF/myofib transformation. Certain GPCRs, e.g. angiotensin and endothelin receptors, can promote cardiac fibrosis but few others are known to do this. We hypothesized that previously unrecognized GPCRs play an important role in regulating the function of CFs. Using the RT-PCR GPCR array, we found that the protease-activated receptor 1 (PAR1) is the most abundant GPCR in adult rat CFs (rCFs). Thrombin activation of PAR1 in rCFs elevates (with distinct kinetics) the expression of a variety of pro-fibrotic markers, induces morphological changes to the myofib phenotype and stimulates synthesis of collagen, the primary ECM component without affecting cell proliferation. The thrombin-induced initiation of a proliferation-independent pro-fibrotic response in adult rCFs contrasts with effects of thrombin in neonatal rCFs, suggesting a differential wound repair response in the adult versus the still-developing heart. By defining the level of expression of GPCRs in rCFs and revealing an expanded role for PAR1 in the wound repair response of the heart, the data provide a proof-of-principle that our approach can identify novel functional and disease-relevant GPCRs in CFs-- and likely in other cardiovascular cells as well.

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Abstract 304: Estrogen Plays a Protective Role in Advanced Heart Failure by Suppressing Cardiac Fibrosis Associated Genes via miR129 Induction

Circulation Research ◽

10.1161/res.113.suppl_1.a304 ◽

2013 ◽

Vol 113 (suppl_1) ◽

Author(s):

Salil Sharma ◽

Andrea Iorga ◽

Harnek Singh ◽

Jingyaun Li ◽

Mansoureh Eghbali

Keyword(s):

Heart Failure ◽

Target Genes ◽

Cardiac Fibrosis ◽

Cardiac Fibroblasts ◽

Pressure Overload ◽

Neonatal Rat ◽

Fibroblast Proliferation ◽

Short Term ◽

Short Term Treatment

We have previously shown that short term treatment of estrogen(E2) can rescue advance heart failure(HF) and decreases associated fibrosis. We hypothesized that E2 can reduce fibrosis by regulating the levels of specific microRNAs including miR129-5p(miR129) through ERβ mediated mechanism. We used transaortic constriction to induce HF in male mice, and once the ejection fraction (EF) reached ~30%, one group of animals was sacrificed (HF), and the other group received 17b-estradiol via a subcutaneous pellet implant (0.012mg/pellet, n=16) (E2) for 10 days. Sham-operated mice served as CTRL. Serial echocardiography was performed to monitor cardiac structure and function. Short-term E2 treatment rescued pressure overload-induced decompensated HF in mice by restoring the EF from 33.17±1.12% to 53.05±1.29 (p <0.001, n=16). E2 decreased both interstitial and perivascular fibrosis in HF. Microarray analysis comparing HF with E2 revealed ~70 microRNAs including miR129 regulated by E2. qPCR validation revealed that E2 treatment upregulates miR129 by 2 folds compared to HF restoring it to CTRL levels. Treatment of HF with ERβ agonist (DPN), but not ERα agonist (PPT) resulted in the upregulation of miR129 indicating the E2 mediated induction of miR129 is mediated through ERβ. In vitro, angiotensin II treatment significantly downregulated miR129 expression in neonatal rat fibroblasts (NRVF) which was restored by E2 and DPN but not by E2+ERβ antagonist (PHPT) further confirming the role of ERβ in regulating miR129. In vitro, OE of miR129 in both neonatal and adult rat cardiac fibroblasts (ARVF) resulted in significant downregulation of transcripts of many in-silico predicted pro-fibrotic target genes including EGFR, RUNX, GREM1, COL2A, PDGFA, PDGFRA and the transcription factor SOX4. OE of miR129 in fibroblasts also resulted in downregulation of EGFR protein. Gain of miR129 prevented the transition of fibroblasts to myofibroblasts in both NRVF and ARVF and inhibited fibroblast proliferation in vitro. In conclusion, E2 treatment during HF induces miR129 likely through ERβ. MiR129 represses fibrosis by targeting key genes associated with cardiac fibrosis, inhibits fibroblast proliferation and fibroblast to myofibroblast transition.

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

Planta Medica ◽

10.1055/s-0043-118663 ◽

2017 ◽

Vol 84 (02) ◽

pp. 91-99 ◽

Cited By ~ 6

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.

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EPRS Regulates Proline-rich Pro-fibrotic Protein Synthesis during Cardiac Fibrosis

10.1101/777490 ◽

2019 ◽

Cited By ~ 1

Author(s):

Jiangbin Wu ◽

Kadiam C Venkata Subbaiah ◽

Li Huitong Xie ◽

Feng Jiang ◽

Deanne Mickelsen ◽

...

Keyword(s):

Heart Failure ◽

Cardiac Remodeling ◽

Translational Control ◽

Cardiac Fibrosis ◽

Cardiac Fibroblasts ◽

Mrna Translation ◽

Trna Synthetase ◽

Mouse Heart ◽

List Type ◽

Human And Mouse

AbstractRationaleIncreased protein synthesis of pro-fibrotic genes is a common feature of cardiac fibrosis, a major manifestation of heart failure. Despite this important observation, critical factors and molecular mechanisms for translational control of pro-fibrotic genes during cardiac fibrosis remain unclear.ObjectiveThis study aimed to test the hypothesis that cardiac stress-induced expression of a bifunctional aminoacyl-tRNA synthetase (ARS), glutamyl-prolyl-tRNA synthetase (EPRS), is preferentially required for the translation of proline codon-rich (PRR) pro-fibrotic mRNAs in cardiac fibroblasts during cardiac fibrosis.Methods and ResultsBy analyses of multiple available unbiased large-scale screening datasets of human and mouse heart failure, we have discovered that EPRS acts as an integrated node among all the ARSs in various cardiac pathogenic processes. We confirmed that EPRS was induced at both mRNA and protein level (∼1.5-2.5 fold increase) in failing hearts compared with non-failing hearts using our cohort of human and mouse heart samples. Genetic knockout of one allele of Eprs globally (Eprs+/-) using CRISPR-Cas9 technology or in a myofibroblast-specific manner (Eprsflox/+; PostnMCM/+) strongly reduces cardiac fibrosis (∼50% reduction) in isoproterenol- and transverse aortic constriction-induced heart failure mouse models. Inhibition of EPRS by a prolyl-tRNA synthetase (PRS)-specific inhibitor, halofuginone (Halo), significantly decreased the translation efficiency of proline-rich collagens in cardiac fibroblasts. Furthermore, using transcriptome-wide RNA-Seq and polysome profiling-Seq in Halo-treated fibroblasts, we identified multiple novel Pro-rich genes in addition to collagens, such as Ltbp2 and Sulf1, which are translationally regulated by EPRS. As a major EPRS downstream effector, SULF1 is highly enriched in human and mouse myofibroblast. siRNA-mediated knockdown of SULF1 attenuates cardiac myofibroblast activation and collagen deposition.ConclusionsOur results indicate that EPRS preferentially controls the translational activation of proline codon-rich pro-fibrotic genes in cardiac fibroblasts and augments pathological cardiac remodeling.Novelty and SignificanceWhat is known?TGF-β and IL-11 increase synthesis of pro-fibrotic proteins during cardiac fibrosis.Many pro-fibrotic genes contain Pro genetic codon rich motifs such as collagens.EPRS is an essential house-keeping enzyme required for ligating Pro to tRNAPro for the synthesis of Pro-containing proteins.What New Information Does This Article Contribute?This study is a pioneering investigation of translational control mechanisms of pro-fibrotic gene expression in cardiac fibrosis.EPRS mRNA and protein expression are induced in failing human hearts and mouse hearts undergoing pathological cardiac remodeling.The first demonstration of the in vivo function of EPRS in cardiac remodeling. Heterozygous Eprs global knockout and myofibroblast-specific tamoxifen-inducible Eprs conditional knockout mice show reduced pathological cardiac fibrosis under stress, suggesting that the reduction of EPRS is cardioprotective.Identification of novel preferential translational target genes of EPRS. We found that EPRS regulates translation of Pro-rich (PRR) transcripts, which comprise most of the ECM and secretory signaling molecules. Among those targets, we identified multiple novel PRR genes such as LTBP2 and SULF1.SULF1 is validated as a myofibroblast marker protein in human and mouse heart failure and a potential anti-fibrosis target gene.In cardiac fibroblasts, the synthesis of pro-fibrotic proteins is upregulated by cardiac stressors to activate extracellular matrix deposition and impair cardiac function. In this study, we have discovered an EPRS-PRR gene axis that influences translational homeostasis of pro-fibrotic proteins and promotes pathological cardiac remodeling and fibrosis. EPRS is identified as a common node downstream of multiple cardiac stressors and a novel regulatory factor that facilitates pro-fibrotic mRNA translation in cardiac fibrosis. Global and myofibroblast-specific genetic ablation of EPRS can effectively reduce cardiac fibrosis. This study reveals a novel translational control mechanism that modulates cardiac fibrosis and heart function. Mild inhibition of PRR mRNA translation could be a general therapeutic strategy for the treatment of heart disease. These findings provide novel insights into the translational control mechanisms of cardiac fibrosis and will promote the development of novel therapeutics by inhibiting pro-fibrotic translation factors or their downstream effectors.

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Bone Morphogenetic Protein 9 Reduces Cardiac Fibrosis and Improves Cardiac Function in Heart Failure

Circulation ◽

10.1161/circulationaha.117.031635 ◽

2018 ◽

Vol 138 (5) ◽

pp. 513-526 ◽

Cited By ~ 19

Author(s):

Kevin J. Morine ◽

Xiaoying Qiao ◽

Sam York ◽

Peter S. Natov ◽

Vikram Paruchuri ◽

...

Keyword(s):

Heart Failure ◽

Cardiac Fibrosis ◽

Cardiac Fibroblasts ◽

Human Subjects ◽

Lv Function ◽

Transverse Aortic Constriction ◽

Aortic Constriction ◽

Bone Morphogenetic Protein 9 ◽

Human Cardiac Fibroblasts ◽

Tgf Β1

Background: Heart failure is a growing cause of morbidity and mortality worldwide. Transforming growth factor beta (TGF-β1) promotes cardiac fibrosis, but also activates counterregulatory pathways that serve to regulate TGF-β1 activity in heart failure. Bone morphogenetic protein 9 (BMP9) is a member of the TGFβ family of cytokines and signals via the downstream effector protein Smad1. Endoglin is a TGFβ coreceptor that promotes TGF-β1 signaling via Smad3 and binds BMP9 with high affinity. We hypothesized that BMP9 limits cardiac fibrosis by activating Smad1 and attenuating Smad3, and, furthermore, that neutralizing endoglin activity promotes BMP9 activity. Methods: We examined BMP9 expression and signaling in human cardiac fibroblasts and human subjects with heart failure. We used the transverse aortic constriction–induced model of heart failure to evaluate the functional effect of BMP9 signaling on cardiac remodeling. Results: BMP9 expression is increased in the circulation and left ventricle (LV) of human subjects with heart failure and is expressed by cardiac fibroblasts. Next, we observed that BMP9 attenuates type I collagen synthesis in human cardiac fibroblasts using recombinant human BMP9 and a small interfering RNA approach. In BMP9 –/– mice subjected to transverse aortic constriction, loss of BMP9 activity promotes cardiac fibrosis, impairs LV function, and increases LV levels of phosphorylated Smad3 (pSmad3), not pSmad1. In contrast, treatment of wild-type mice subjected to transverse aortic constriction with recombinant BMP9 limits progression of cardiac fibrosis, improves LV function, enhances myocardial capillary density, and increases LV levels of pSmad1, not pSmad3 in comparison with vehicle-treated controls. Because endoglin binds BMP9 with high affinity, we explored the effect of reduced endoglin activity on BMP9 activity. Neutralizing endoglin activity in human cardiac fibroblasts or in wild-type mice subjected to transverse aortic constriction–induced heart failure limits collagen production, increases BMP9 protein levels, and increases levels of pSmad1, not pSmad3. Conclusions: Our results identify a novel functional role for BMP9 as an endogenous inhibitor of cardiac fibrosis attributable to LV pressure overload and further show that treatment with either recombinant BMP9 or disruption of endoglin activity promotes BMP9 activity and limits cardiac fibrosis in heart failure, thereby providing potentially novel therapeutic approaches for patients with heart failure.

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Abstract 92: Platelet Derived Growth Factor Receptor Alpha Signaling is Required for Cardiac Fibroblast Survival and Proliferation

Circulation Research ◽

10.1161/res.119.suppl_1.92 ◽

2016 ◽

Vol 119 (suppl_1) ◽

Author(s):

Malina J Ivey ◽

Michelle D Tallquist

Keyword(s):

Preliminary Data ◽

Cardiac Fibrosis ◽

Heart Function ◽

Cardiac Fibroblasts ◽

Growth Factor Receptor ◽

Cell Types ◽

Fibroblast Proliferation ◽

Artery Ligation ◽

Developing Heart ◽

Factor Receptor Alpha

Cardiac fibrosis contributes significantly to heart disease and is a hallmark of decreased cardiac function. Currently, there are no treatments that attenuate fibrosis, but identification of signaling pathways required for fibroblast function would provide some potential targets. PDGFRα is a receptor tyrosine kinase that is required for fibroblast formation in the developing heart, and preliminary data indicates that it is also required for maintenance of resident fibroblasts and expansion of activated fibroblasts after injury. Preliminary experiments demonstrate that loss of PDGFRα expression in adult cardiac fibroblasts results in 50% reduction in the number of the resident fibroblasts by 4 days after gene deletion. This was further validated using an independent fibroblast marker, collagen1a1GFP. Based on the low basal level of fibroblast proliferation, we hypothesize that PDGFRα signaling is essential for fibroblast survival and that fibroblasts undergo rapid turnover in the absence of PDGFRα signaling. Future studies will determine the exact mechanism of this loss. We have also begun to elucidate which PDGFRα downstream signals promote fibroblast maintenance. Using a PDGFRα-dependent-PI3K-deficient mouse model, preliminary data indicates that PDGFRα-dependent PI3K signaling is essential for cell survival. We are also investigating the role of PDGFRα signaling after myocardial infarction. Using recently described genetic tools to follow fibroblasts after injury, we have determined that fibroblasts reach their peak of proliferation within a week after permanent left anterior descending artery ligation. This injury-induced proliferation is reduced by 50% after deletion of PDGFRα. Therefore, we have demonstrated that PDGFRα has a role in fibroblast maintenance in the healthy heart, as well as a role in fibroblast proliferation after injury. Our studies will continue to illuminate additional roles for PDGFRα in the fibroblast, as well as the implications of fibroblast loss on other cell types and overall heart function.

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Pirfenidone exhibits cardioprotective effects by regulating myocardial fibrosis and vascular permeability in pressure-overloaded hearts

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00137.2015 ◽

2015 ◽

Vol 309 (3) ◽

pp. H512-H522 ◽

Cited By ~ 44

Author(s):

Kiyoshi Yamagami ◽

Toru Oka ◽

Qi Wang ◽

Takamaru Ishizu ◽

Jong-Kook Lee ◽

...

Keyword(s):

Heart Failure ◽

Endothelial Cells ◽

Vascular Permeability ◽

Molecular Mechanisms ◽

Cardiac Fibrosis ◽

Transforming Growth Factor ◽

Cardiac Fibroblasts ◽

Chronic Phase ◽

Vehicle Group

Although cardiac fibrosis causes heart failure, its molecular mechanisms remain elusive. In this study, we investigated the mechanisms of cardiac fibrosis and examined the effects of the antifibrotic drug pirfenidone (PFD) on chronic heart failure. To understand the responsible mechanisms, we generated an in vivo pressure-overloaded heart failure model via transverse aortic constriction (TAC) and examined the effects of PFD on chronic-phase cardiac fibrosis and function. In the vehicle group, contractile dysfunction and left ventricle fibrosis progressed further from 4 to 8 wk after TAC but were prevented by PFD treatment beginning 4 wk after TAC. We isolated cardiac fibroblasts and vascular endothelial cells from the left ventricles of adult male mice and investigated the cell-type-specific effects of PFD. Transforming growth factor-β induced upregulated collagen 1 expression via p38 phosphorylation and downregulated claudin 5 (Cldn5) expression in cardiac fibroblasts and endothelial cells, respectively; both processes were inhibited by PFD. Moreover, PFD inhibited changes in the collagen 1 and Cldn5 expression levels, resulting in reduced fibrosis and serum albumin leakage into the interstitial space during the chronic phase in TAC hearts. In conclusion, PFD inhibited cardiac fibrosis by suppressing both collagen expression and the increased vascular permeability induced by pressure overload.

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The Cell Surface Receptors Ror1/2 Control Cardiac Myofibroblast Differentiation

10.1101/2021.03.02.433549 ◽

2021 ◽

Author(s):

Nicholas W. Chavkin ◽

Soichi Sano ◽

Ying Wang ◽

Kosei Oshima ◽

Hayato Ogawa ◽

...

Keyword(s):

Heart Failure ◽

Planar Cell Polarity ◽

Cardiac Fibrosis ◽

Cardiac Fibroblasts ◽

Cardiac Injury ◽

Pressure Overload ◽

Orphan Receptor ◽

Myofibroblast Differentiation ◽

Cultured Fibroblasts

AbstractBackgroundA hallmark of heart failure is cardiac fibrosis, which results from the injury-induced differentiation response of resident fibroblasts to myofibroblasts that deposit extracellular matrix. During myofibroblast differentiation, fibroblasts progress through polarization stages of early pro-inflammation, intermediate proliferation, and late maturation, but the regulators of this progression are poorly understood. Planar cell polarity receptors, receptor tyrosine kinase like orphan receptor 1 and 2 (Ror1/2), can function to promote cell differentiation and transformation. In this study, we investigated the role of the Ror1/2 in a model of heart failure with emphasis on myofibroblast differentiation.Methods and ResultsThe role of Ror1/2 during cardiac myofibroblast differentiation was studied in cell culture models of primary murine cardiac fibroblast activation and in knockout mouse models that underwent transverse aortic constriction (TAC) surgery to induce cardiac injury by pressure overload. Expression of Ror1 and Ror2 were robustly and exclusively induced in fibroblasts in hearts after TAC surgery, and both were rapidly upregulated after early activation of primary murine cardiac fibroblasts in culture. Cultured fibroblasts isolated from Ror1/2-KO mice displayed a pro-inflammatory phenotype indicative of impaired myofibroblast differentiation. Although the combined ablation of Ror1/2 in mice did not result in a detectable baseline phenotype, TAC surgery led to the death of all mice by day 6 that was associated with myocardial hyper-inflammation and vascular leakage.ConclusionsTogether, these results show that Ror1/2 are essential for the progression of myofibroblast differentiation and for the adaptive remodeling of the heart in response to pressure overload.

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