Targeted Disruption ofSmad4in Cardiomyocytes Results in Cardiac Hypertrophy and Heart Failure

MicroRNA-452-5p regulates fibrogenesis via targeting TGF-β/SMAD4 axis in SCN5A-knockdown human cardiac fibroblasts

The mutated SCN5A gene encoding defective Nav1.5 protein causes arrhythmic ailments and is associated with enhanced cardiac fibrosis. This study investigated whether SCN5A mutation directly affects cardiac fibroblasts and explored how defective SCN5A relates to cardiac fibrosis. SCN5A knockdown (SCN5AKD) human cardiac fibroblasts (HCF) had higher collagen, α-SMA, and fibronectin expressions. Micro-RNA deep sequencing and qPCR analysis revealed the downregulation of miR-452-5p and bioinformatic analysis divulged maladaptive upregulation of transforming growth factor β (TGF-β) signaling in SCN5AKD HCF. Luciferase reporter assays validated miR-452-5p targets SMAD4 in SCN5AKD HCF. Moreover, miR-452-5p mimic transfection in SCN5AKD HCF or AAV9-mediated miR-452-5p delivery in isoproterenol-induced heart failure (HF) rats, resulted in the attenuation of TGF-β signaling and fibrogenesis. The exogenous miR-452-5p significantly improved the poor cardiac function in HF rats. In conclusion, miR-452-5p regulates cardiac fibrosis progression by targeting the TGF-β/SMAD4 axis under the loss of the SCN5A gene.

Prospective of Pancreatic Cancer Diagnosis Using Cardiac Sensing

Pancreatic carcinoma (Ca Pancreas) is the third leading cause of cancer-related deaths in the world. The malignancies of the pancreas can be diagnosed with the help of various imaging modalities. An endoscopic ultrasound with a tissue biopsy is so far considered to be the gold standard in terms of the detection of Ca Pancreas, especially for lesions <2 mm. However, other methods, like computed tomography (CT), ultrasound, and magnetic resonance imaging (MRI), are also conventionally used. Moreover, newer techniques, like proteomics, radiomics, metabolomics, and artificial intelligence (AI), are slowly being introduced for diagnosing pancreatic cancer. Regardless, it is still a challenge to diagnose pancreatic carcinoma non-invasively at an early stage due to its delayed presentation. Similarly, this also makes it difficult to demonstrate an association between Ca Pancreas and other vital organs of the body, such as the heart. A number of studies have proven a correlation between the heart and pancreatic cancer. The tumor of the pancreas affects the heart at the physiological, as well as the molecular, level. An overexpression of the SMAD4 gene; a disruption in biomolecules, such as IGF, MAPK, and ApoE; and increased CA19-9 markers are a few of the many factors that are noted to affect cardiovascular systems with pancreatic malignancies. A comprehensive review of this correlation will aid researchers in conducting studies to help establish a definite relation between the two organs and discover ways to use it for the early detection of Ca Pancreas.

Integrated Proteomics Unveils Nuclear PDE3A2 as a Regulator of Cardiac Myocyte Hypertrophy

BACKGROUND

Signaling by cAMP is organized in multiple distinct subcellular nanodomains regulated by cAMP-hydrolyzing PDEs (phosphodiesterases). Cardiac β-adrenergic signaling has served as the prototypical system to elucidate cAMP compartmentalization. Although studies in cardiac myocytes have provided an understanding of the location and properties of a handful of cAMP subcellular compartments, an overall view of the cellular landscape of cAMP nanodomains is missing.

METHODS

Here, we combined an integrated phosphoproteomics approach that takes advantage of the unique role that individual PDEs play in the control of local cAMP, with network analysis to identify previously unrecognized cAMP nanodomains associated with β-adrenergic stimulation. We then validated the composition and function of one of these nanodomains using biochemical, pharmacological, and genetic approaches and cardiac myocytes from both rodents and humans.

RESULTS

We demonstrate the validity of the integrated phosphoproteomic strategy to pinpoint the location and provide critical cues to determine the function of previously unknown cAMP nanodomains. We characterize in detail one such compartment and demonstrate that the PDE3A2 isoform operates in a nuclear nanodomain that involves SMAD4 (SMAD family member 4) and HDAC-1 (histone deacetylase 1). Inhibition of PDE3 results in increased HDAC-1 phosphorylation, leading to inhibition of its deacetylase activity, derepression of gene transcription, and cardiac myocyte hypertrophic growth.

CONCLUSIONS

We developed a strategy for detailed mapping of subcellular PDE-specific cAMP nanodomains. Our findings reveal a mechanism that explains the negative long-term clinical outcome observed in patients with heart failure treated with PDE3 inhibitors.

The KLF7/PFKL/ACADL axis modulates cardiac metabolic remodelling during cardiac hypertrophy in male mice

The main hallmark of myocardial substrate metabolism in cardiac hypertrophy or heart failure is a shift from fatty acid oxidation to greater reliance on glycolysis. However, the close correlation between glycolysis and fatty acid oxidation and underlying mechanism by which causes cardiac pathological remodelling remain unclear. We confirm that KLF7 simultaneously targets the rate-limiting enzyme of glycolysis, phosphofructokinase-1, liver, and long-chain acyl-CoA dehydrogenase, a key enzyme for fatty acid oxidation. Cardiac-specific knockout and overexpression KLF7 induce adult concentric hypertrophy and infant eccentric hypertrophy by regulating glycolysis and fatty acid oxidation fluxes in male mice, respectively. Furthermore, cardiac-specific knockdown phosphofructokinase-1, liver or overexpression long-chain acyl-CoA dehydrogenase partially rescues the cardiac hypertrophy in adult male KLF7 deficient mice. Here we show that the KLF7/PFKL/ACADL axis is a critical regulatory mechanism and may provide insight into viable therapeutic concepts aimed at the modulation of cardiac metabolic balance in hypertrophied and failing heart.

Mechanism of action of non-coding RNAs and traditional Chinese medicine in myocardial fibrosis: Focus on the TGF-β/Smad signaling pathway

Cardiac fibrosis is a serious public health problem worldwide that is closely linked to progression of many cardiovascular diseases (CVDs) and adversely affects both the disease process and clinical prognosis. Numerous studies have shown that the TGF-β/Smad signaling pathway plays a key role in the progression of cardiac fibrosis. Therefore, targeted inhibition of the TGF-β/Smad signaling pathway may be a therapeutic measure for cardiac fibrosis. Currently, as the investigation on non-coding RNAs (ncRNAs) move forward, a variety of ncRNAs targeting TGF-β and its downstream Smad proteins have attracted high attention. Besides, Traditional Chinese Medicine (TCM) has been widely used in treating the cardiac fibrosis. As more and more molecular mechanisms of natural products, herbal formulas, and proprietary Chinese medicines are revealed, TCM has been proven to act on cardiac fibrosis by modulating multiple targets and signaling pathways, especially the TGF-β/Smad. Therefore, this work summarizes the roles of TGF-β/Smad classical and non-classical signaling pathways in the cardiac fibrosis, and discusses the recent research advances in ncRNAs targeting the TGF-β/Smad signaling pathway and TCM against cardiac fibrosis. It is hoped, in this way, to give new insights into the prevention and treatment of cardiac fibrosis.

SMAD4 loss-of-function mutation predisposes to congenital heart disease

Congenital heart disease (CHD) represents the most frequent developmental deformity in human beings and accounts for substantial morbidity and mortality worldwide. Accumulating investigations underscore the strong inherited basis of CHD, and pathogenic variations in >100 genes have been related to CHD. Nevertheless, the heritable defects underpinning CHD remain elusive in most cases, mainly because of the pronounced genetic heterogeneity. In this investigation, a four-generation family with CHD was recruited and clinically investigated. Via whole-exome sequencing and Sanger sequencing assays in selected family members, a heterozygous variation in the SMAD4 gene (coding for a transcription factor essential for cardiovascular morphogenesis), NM_005359.6: c.285T > A; p.(Tyr95*), was identified to be in co-segregation with autosomal-dominant CHD in the entire family. The truncating variation was not observed in 460 unrelated non-CHD volunteers employed as control subjects. Functional exploration by dual-reporter gene analysis demonstrated that Tyr95*-mutant SMAD4 lost transactivation of its two key downstream target genes NKX2.5 and ID2, which were both implicated with CHD. Additionally, the variation nullified the synergistic transcriptional activation between SMAD4 and GATA4, another transcription factor involved in CHD. These data strongly indicate SMAD4 may be associated with CHD and shed more light on the molecular pathogenesis underlying CHD, implying potential implications for antenatal precise prevention and prognostic risk stratification of the patients affected with CHD.

Characterization and Validation of ceRNA-Mediated Pathway–Pathway Crosstalk Networks Across Eight Major Cardiovascular Diseases

Pathway analysis is considered as an important strategy to reveal the underlying mechanisms of diseases. Pathways that are involved in crosstalk can regulate each other and co-regulate downstream biological processes. Furthermore, some genes in the pathways can function with other genes via the relationship of the competing endogenous RNA (ceRNA) mechanism, which has also been demonstrated to play key roles in cellular biology. However, the comprehensive analysis of ceRNA-mediated pathway crosstalk is lacking. Here, we constructed the landscape of the ceRNA-mediated pathway–pathway crosstalk of eight major cardiovascular diseases (CVDs) based on sequencing data from ∼2,800 samples. Some common features shared by numerous CVDs were uncovered. A fraction of the pathway–pathway crosstalk was conserved in multiple CVDs and a core pathway–pathway crosstalk network was identified, suggesting the similarity of pathway–pathway crosstalk among CVDs. Experimental evidence also demonstrated that the pathway crosstalk was functioned in CVDs. We split all hub pathways of each pathway–pathway crosstalk network into three categories, namely, common hubs, differential hubs, and specific hubs, which could highlight the common or specific biological mechanisms. Importantly, after a comparison analysis of the hub pathways of networks, ∼480 hub pathway-induced common modules were identified to exert functions in CVDs broadly. Moreover, we performed a random walk algorithm on the hub pathway-induced sub-network and identified 23 potentially novel CVD-related pathways. In summary, our study revealed the potential molecular regulatory mechanisms of ceRNA crosstalk in pathway–pathway crosstalk levels and provided a novel routine to investigate the pathway–pathway crosstalk in cardiology. All CVD pathway–pathway crosstalks are provided in http://www.licpathway.net/cepathway/index.html.

Long noncoding RNA H19 suppresses cardiac hypertrophy through the MicroRNA-145-3p/SMAD4 axis

Sustained cardiac hypertrophy (CH) contributes to many heart diseases. Long noncoding RNAs (lncRNAs) collectively play critical roles in cardiovascular diseases (CVDs). However, the roles of lncRNA H19 in CH are still unclear. A CH model was constructed utilizing isoproterenol (ISO). We demonstrated H19 could participate in regulating ISO-induced CH development both in vivo and in vitro. The online databases DIANA and TargetScan were used to predict the targets of H19 and MicroRNA-145-3p (miR-145-3p), respectively. Luciferase reporter assay was used to verify the downstream targets. The results showed that H19 was decreased under ISO stimulation. The H19 overexpression resulted in significant decrease in mouse heart size and weight, left ventricular systolic dysfunction, left ventricular posterior wall thickness and cardiac hypertrophic growth, while promoted the increase of left ventricular ejection fraction and left ventricle fraction shortening. H19 also inhibited protein expression levels of CH markers, such as atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and MYH7. Luciferase assays results showed that miR-145-3p was a target of H19 and SMAD4 was a target of miR-145-3p. We found that H19 regulated SMAD4 by sponging miR-145-3p. Knockout of miR-145-3p or overexpression of SMAD4 facilitated H19-induced decreases in ANP, BNP, and MYH7. Collectively, our findings have indicated that the H19/miR-145-3p/SMAD4 axis should be a negative regulator involved in CH progression.

Transforming growth factor-β in myocardial disease

Transforming growth factor-β (TGFβ) isoforms are upregulated and activated in myocardial diseases and have an important role in cardiac repair and remodelling, regulating the phenotype and function of cardiomyocytes, fibroblasts, immune cells and vascular cells. Cardiac injury triggers the generation of bioactive TGFβ from latent stores, through mechanisms involving proteases, integrins and specialized extracellular matrix (ECM) proteins. Activated TGFβ signals through the SMAD intracellular effectors or through non-SMAD cascades. In the infarcted heart, the anti-inflammatory and fibroblast-activating actions of TGFβ have an important role in repair; however, excessive or prolonged TGFβ signalling accentuates adverse remodelling, contributing to cardiac dysfunction. Cardiac pressure overload also activates TGFβ cascades, which initially can have a protective role, promoting an ECM-preserving phenotype in fibroblasts and preventing the generation of injurious, pro-inflammatory ECM fragments. However, prolonged and overactive TGFβ signalling in pressure-overloaded cardiomyocytes and fibroblasts can promote cardiac fibrosis and dysfunction. In the atria, TGFβ-mediated fibrosis can contribute to the pathogenic substrate for atrial fibrillation. Overactive or dysregulated TGFβ responses have also been implicated in cardiac ageing and in the pathogenesis of diabetic, genetic and inflammatory cardiomyopathies. This Review summarizes the current evidence on the role of TGFβ signalling in myocardial diseases, focusing on cellular targets and molecular mechanisms, and discussing challenges and opportunities for therapeutic translation.

Mechanism of miR-30b-5p-Loaded PEG-PLGA Nanoparticles for Targeted Treatment of Heart Failure

Objective: Exploring the effectiveness of miR-30b-5p-loaded PEG-PLGA nanoparticles (NPs) for the treatment of heart failure and the underlying mechanism.

Methods: PEG-PLGA characteristics with different loading amounts were first examined to determine the loading, encapsulation, and release of miR-30b-5p from NPs. The effects of miR-30b-5p NPs on cardiac function and structure were assessed by immunofluorescence, echocardiography, HE/Masson staining, and TUNEL staining. The effects of NPs on the expression of factors related to cardiac hypertrophy and inflammation were examined by RT-PCR and western blotting, and the mechanism of miR-30b-5p treatment on heart failure was explored by dual luciferase reporter assay and RT-PCR.

Results: The size of PEG-PLGA NPs with different loading amounts ranged from 200 to 300 nm, and the zeta potential of PEG-PLGA NPs was negative. The mean entrapment efficiency of the NPs for miR-30b-5p was high (81.8 ± 2.1%), and the release rate reached 5 days with more than 90% release. Distribution experiments showed that NPs were mainly distributed in the heart and had a protective effect on myocardial injury and cardiac function. Compared with a rat model of cardiac failure and miR-30b-5p-non-loaede NP groups, the expression of cardiac hypertrophy markers (ANP, BNPβ-MHC) and inflammatory factors (IL-1β, IL-6) were significantly decreased. Dual luciferase reporter assay assays indicated that miR-30b-5p exerted its effects mainly by targeting TGFBR2.

Conclusion: PEG-PLGA NPs loaded with miR-30b-5p improved cardiac function, attenuated myocardial injury, and regulated the expression of factors associated with cardiac hypertrophy and inflammation by targeting TGFBR2.

PRMT5 Prevents Dilated Cardiomyopathy via Suppression of Protein O-GlcNAcylation

[Figure: see text].

E2F transcription factor 1 (E2F1) promotes the transforming growth factor TGF-β1 induced human cardiac fibroblasts differentiation through promoting the transcription of CCNE2 gene

The differentiation of cardiac fibroblast to myofibroblast is the key process of cardiac fibrosis. In the study, we aimed to determine the function of E2F Transcription Factor 1 (E2F1) in human cardiac fibroblasts (HCFs) differentiation, search for its downstream genes and elucidate the function of them in HCFs differentiation. As a result, we found that E2F1 was up-regulated in TGF-β1-induced HCFs differentiation. Silencing the expression of E2F1 by siRNA in HCFs, we found that the expression of differentiation-related genes (Collagen-1, α-Smooth muscle actin, and Fibronectin-1) was significantly suppressed, combining with proliferation and migration assay, we determined that HCFs differentiation was decreased. Luciferase report assay and immunoprecipitation proved that the oncogene CCNE2 was a direct target gene of E2F1, overexpression of CCNE2 was found in differentiated HCFs, silencing the expression of CCNE2 by siRNA decreased HCFs differentiation. Our research suggested that E2F1 and its downstream target gene CCNE2 play a vital role in TGF-β1-induced HCFs differentiation, thus E2F1 and CCNE2 may be a potential therapeutic target for cardiac fibrosis.

Methyl Ferulic Acid Attenuates Human Cardiac Fibroblasts Differentiation and Myocardial Fibrosis by Suppressing pRB-E2F1/CCNE2 and RhoA/ROCK2 Pathway

Background: Myocardial fibrosis is a key pathological process after myocardial infarction, which leads to poor outcomes in patients at the end stage. Effective treatments for improving prognosis of myocardial fibrosis are needed to be further developed. Methyl ferulic acid (MFA), a biologically active monomer extracted and purified from the Chinese herbal medicine, is reported as an attenuator in many diseases. In this study, we aim to reveal the role it plays in myocardial fibrosis after myocardial infarction and its possible mechanism. Results: Firstly, we found that MFA attenuated the expression of fibrosis-related proteins and the ability of migration and proliferation in TGF-β1-induced human cardiac fibroblasts (HCFs). Then, myocardial fibrosis after myocardial infarction models on mouse was built to reveal the in vivo affection of MFA. After 28 days of treatments, fibrosis areas, cardiac function, and expression of fibrosis-related proteins were all improved in the MFA-treated group than the myocardial infarction group. Finally, to elucidate the mechanism of phenomenon we observed, we found that MFA attenuated HCF differentiation after myocardial infarction by suppressing the migration and proliferation in HCFs, which was by suppressing the pRB-E2F1/CCNE2 and the RhoA/ROCK2 pathway. Conclusion: Our findings showed that MFA attenuated the expression of fibrosis-related proteins, and the ability of migration and proliferation in HCFs improved the cardiac function of myocardial infarction mice; meanwhile, the mechanism of that was by suppressing the pRB-E2F1/CCNE2 and the RhoA/ROCK2 pathway.

Different cardiovascular and pulmonary phenotypes for single- and double-knock-out mice deficient in BMP9 and BMP10

Aims

BMP9 and BMP10 mutations were recently identified in patients with pulmonary arterial hypertension, but their specific roles in the pathogenesis of the disease are still unclear. We aimed to study the roles of BMP9 and BMP10 in cardiovascular homeostasis and pulmonary hypertension using transgenic mouse models deficient in Bmp9 and/or Bmp10.

Methods and results

Single- and double-knockout mice for Bmp9 (constitutive) and/or Bmp10 (tamoxifen inducible) were generated. Single-knock-out (KO) mice developed no obvious age-dependent phenotype when compared with their wild-type littermates. However, combined deficiency in Bmp9 and Bmp10 led to vascular defects resulting in a decrease in peripheral vascular resistance and blood pressure and the progressive development of high-output heart failure and pulmonary hemosiderosis. RNAseq analysis of the lungs of the double-KO mice revealed differential expression of genes involved in inflammation and vascular homeostasis. We next challenged these mice to chronic hypoxia. After 3 weeks of hypoxic exposure, Bmp10-cKO mice showed an enlarged heart. However, although genetic deletion of Bmp9 in the single- and double-KO mice attenuated the muscularization of pulmonary arterioles induced by chronic hypoxia, we observed no differences in Bmp10-cKO mice. Consistent with these results, endothelin-1 levels were significantly reduced in Bmp9 deficient mice but not Bmp10-cKO mice. Furthermore, the effects of BMP9 on vasoconstriction were inhibited by bosentan, an endothelin receptor antagonist, in a chick chorioallantoic membrane assay.

Conclusions

Our data show redundant roles for BMP9 and BMP10 in cardiovascular homeostasis under normoxic conditions (only combined deletion of both Bmp9 and Bmp10 was associated with severe defects) but highlight specific roles under chronic hypoxic conditions. We obtained evidence that BMP9 contributes to chronic hypoxia-induced pulmonary vascular remodelling, whereas BMP10 plays a role in hypoxia-induced cardiac remodelling in mice.

Mending a broken heart: In vitro, in vivo and in silico models of congenital heart disease

Birth defects contribute to ∼0.3% of global infant mortality in the first month of life, and congenital heart disease (CHD) is the most common birth defect among newborns worldwide. Despite the significant impact on human health, most treatments available for this heterogenous group of disorders are palliative at best. For this reason, the complex process of cardiogenesis, governed by multiple interlinked and dose-dependent pathways, is well investigated. Tissue, animal and, more recently, computerized models of the developing heart have facilitated important discoveries that are helping us to understand the genetic, epigenetic and mechanobiological contributors to CHD aetiology. In this Review, we discuss the strengths and limitations of different models of normal and abnormal cardiogenesis, ranging from single-cell systems and 3D cardiac organoids, to small and large animals and organ-level computational models. These investigative tools have revealed a diversity of pathogenic mechanisms that contribute to CHD, including genetic pathways, epigenetic regulators and shear wall stresses, paving the way for new strategies for screening and non-surgical treatment of CHD. As we discuss in this Review, one of the most-valuable advances in recent years has been the creation of highly personalized platforms with which to study individual diseases in clinically relevant settings.

Network Analysis Reveals Proteins Associated with Aortic Dilatation in Mucopolysaccharidoses

Mucopolysaccharidoses are caused by a deficiency of enzymes involved in the degradation of glycosaminoglycans. Heart diseases are a significant cause of morbidity and mortality in MPS patients, even in conditions in which enzyme replacement therapy is available. In this sense, cardiovascular manifestations, such as heart hypertrophy, cardiac function reduction, increased left ventricular chamber, and aortic dilatation, are among the most frequent. However, the downstream events which influence the heart dilatation process are unclear. Here, we employed systems biology tools together with transcriptomic data to investigate new elements that may be involved in aortic dilatation in Mucopolysaccharidoses syndrome. We identified candidate genes involved in biological processes related to inflammatory responses, deposition of collagen, and lipid accumulation in the cardiovascular system that may be involved in aortic dilatation in the Mucopolysaccharidoses I and VII. Furthermore, we investigated the molecular mechanisms of losartan treatment in Mucopolysaccharidoses I mice to underscore how this drug acts to prevent aortic dilation. Our data indicate that the association between the TGF-b signaling pathway, Fos, and Col1a1 proteins can play an essential role in aortic dilation's pathophysiology and its subsequent improvement by losartan treatment.

The role of Smad signaling cascades in cardiac fibrosis

Most myocardial pathologic conditions are associated with cardiac fibrosis, the expansion of the cardiac interstitium through deposition of extracellular matrix (ECM) proteins. Although replacement fibrosis plays a reparative role after myocardial infarction, excessive, unrestrained or dysregulated myocardial ECM deposition is associated with ventricular dysfunction, dysrhythmias and adverse prognosis in patients with heart failure. The members of the Transforming Growth Factor (TGF)-β superfamily are critical regulators of cardiac repair, remodeling and fibrosis. TGF-βs are released and activated in injured tissues, bind to their receptors and transduce signals in part through activation of cascades involving a family of intracellular effectors the receptor-activated Smads (R-Smads). This review manuscript summarizes our knowledge on the role of Smad signaling cascades in cardiac fibrosis. Smad3, the best-characterized member of the family plays a critical role in activation of a myofibroblast phenotype, stimulation of ECM synthesis, integrin expression and secretion of proteases and anti-proteases. In vivo, fibroblast Smad3 signaling is critically involved in scar organization and exerts matrix-preserving actions. Although Smad2 also regulates fibroblast function in vitro, its in vivo role in rodent models of cardiac fibrosis seems more limited. Very limited information is available on the potential involvement of the Smad1/5/8 cascade in cardiac fibrosis. Dissection of the cellular actions of Smads in cardiac fibrosis, and identification of patient subsets with overactive or dysregulated myocardial Smad-dependent fibrogenic responses are critical for design of successful therapeutic strategies in patients with fibrosis-associated heart failure.

Targeting cardiac fibrosis in heart failure with preserved ejection fraction: mirage or miracle?

Cardiac fibrosis is central to the pathology of heart failure, particularly heart failure with preserved ejection fraction (HFpEF). Irrespective of the underlying profibrotic condition (e.g. ageing, diabetes, hypertension), maladaptive cardiac fibrosis is defined by the transformation of resident fibroblasts to matrix-secreting myofibroblasts. Numerous profibrotic factors have been identified at the molecular level (e.g. TGFβ, IL11, AngII), which activate gene expression programs for myofibroblast activation. A number of existing HF therapies indirectly target fibrotic pathways; however, despite multiple clinical trials in HFpEF, a specific clinically effective antifibrotic therapy remains elusive. Therapeutic inhibition of TGFβ, the master-regulator of fibrosis, has unfortunately proven toxic and ineffective in clinical trials to date, and new approaches are needed. In this review, we discuss the pathophysiology and clinical implications of interstitial fibrosis in HFpEF. We provide an overview of trials targeting fibrosis in HFpEF to date and discuss the promise of potential new therapeutic approaches and targets in the context of underlying molecular mechanisms.

Genetic Tools to Study Cardiovascular Biology

Progress in biomedical science is tightly associated with the improvement of methods and genetic tools to manipulate and analyze gene function in mice, the most widely used model organism in biomedical research. The joint effort of numerous individual laboratories and consortiums has contributed to the creation of a large genetic resource that enables scientists to image cells, probe signaling pathways activities, or modify a gene function in any desired cell type or time point, à la carte. However, as these tools significantly increase in number and become more sophisticated, it is more difficult to keep track of each tool's possibilities and understand their advantages and disadvantages. Knowing the best currently available genetic technology to answer a particular biological question is key to reach a higher standard in biomedical research. In this review, we list and discuss the main advantages and disadvantages of available mammalian genetic technology to analyze cardiovascular cell biology at higher cellular and molecular resolution. We start with the most simple and classical genetic approaches and end with the most advanced technology available to fluorescently label cells, conditionally target their genes, image their clonal expansion, and decode their lineages.

Multi-organ transcriptomic landscape of Ambystoma velasci metamorphosis

Metamorphosis is a postembryonic developmental process that involves morphophysiological and behavioral changes, allowing organisms to adapt into a novel environment. In some amphibians, aquatic organisms undergo metamorphosis to adapt in a terrestrial environment. In this process, these organisms experience major changes in their circulatory, respiratory, digestive, excretory and reproductive systems. We performed a transcriptional global analysis of heart, lung and gills during diverse stages of Ambystoma velasci to investigate its metamorphosis. In our analyses, we identified eight gene clusters for each organ, according to the expression patterns of differentially expressed genes. We found 4064 differentially expressed genes in the heart, 4107 in the lung and 8265 in the gills. Among the differentially expressed genes in the heart, we observed genes involved in the differentiation of cardiomyocytes in the interatrial zone, vasculogenesis and in the maturation of coronary vessels. In the lung, we found genes differentially expressed related to angiogenesis, alveolarization and synthesis of the surfactant protein. In the case of the gills, the most prominent biological processes identified are degradation of extracellular matrix, apoptosis and keratin production. Our study sheds light on the transcriptional responses and the pathways modulation involved in the transformation of the facultative metamorphic salamander A. velasci in an organ-specific manner.

KLF10 is upregulated in osteoarthritis and inhibits chondrocyte proliferation and migration by upregulating Acvr1 and suppressing inhbb expression

BACKGROUD

Osteoarthritis (OA) is a common disease caused by chondrocyte dysfunction. KLF10 is a member of the Sp1-like transcription factor family that is involved in regulating osteoblasts, but its expression and regulatory mechanism(s) in chondrocytes are unclear. In the present study, we aimed to investigate the regulatory role of KLF10 on the pathological process of OA.

METHODS

KLF10 expression in the cartilaginous tissue of patients with osteoarthritis (OA) was evaluated by immunohistochemistry (IHC). Next, we generated an OA mouse model, and the histological changes in cartilage tissue were verified using H&E staining, Safranin O-Fast Green staining, and IHC assays. KLF10 expression in the articular chondrocytes of OA mice was determined by qRT-PCR and Western blotting. To investigate the role of KLF10 in regulating cell proliferation and migration, a KLF10 overexpression plasmid was constructed and transfected into primary mouse chondrocytes. Subsequently, we used RNA sequencing (RNA-seq) to screen differentially expressed genes in chondrocytes with or without KLF10 overexpression. qRT-PCR was used for verification purposes.

RESULTS

We found that KLF10 was upregulated in the cartilaginous tissue of patients with OA as well as in cartilaginous tissue of the OA mouse model. KLF10 overexpression inhibited the proliferation and migration of chondrocytes. Furthermore, RNA sequencing results identified increased expression of Acvr1 and decreased expression of Inhbb in cells overexpressing KLF10. Changes in mRNA expression of Acvr1 and Inhbb were confirmed by qRT-PCR.

CONCLUSIONS

KLF10 inhibits chondrocyte proliferation and migration by regulating the expression of Acvr1 and Inhbb in both human and mouse OA. These data suggest that KLF10 may be a potential therapeutic target for the treatment of OA.

Enhanced cardiomyocyte reactive oxygen species signaling promotes ibrutinib-induced atrial fibrillation

Atrial fibrillation (AF) occurs in up to 11% of cancer patients treated with ibrutinib. The pathophysiology of ibrutinib promoted AF is complicated, as there are multiple interactions involved; the detailed molecular mechanisms underlying this are still unclear. Here, we aimed to determine the electrophysiological and molecular mechanisms of burst-pacing-induced AF in ibrutinib-treated mice. The results indicated differentially expressed proteins in ibrutinib-treated mice, identified through proteomic analysis, were found to play a role in oxidative stress-related pathways. Finally, treatment with an inhibitor of NADPH oxidase (NOX) prevented and reversed AF development in ibrutinib-treated mice. It was showed that the related protein expression of reactive oxygen species (ROS) in the ibrutinib group was significantly increased, including NOX2, NOX4, p22-phox, XO and TGF-β protein expression. It was interesting that ibrutinib group also significantly increased the expression of ox-CaMKII, p-CaMKII (Thr-286) and p-RyR2 (Ser2814), causing enhanced abnormal sarcoplasmic reticulum (SR) Ca²⁺ release and mitochondrial structures, as well as atrial fibrosis and atrial hypertrophy in ibrutinib-treated mice, and apocynin reduced the expression of these proteins. Ibrutinib-treated mice were also more likely to develop AF, and AF occurred over longer periods. In conclusion, our study has established a pathophysiological role for ROS signaling in atrial cardiomyocytes, and it may be that ox-CaMKII and p-CaMKII (Thr-286) are activated by ROS to increase AF susceptibility following ibrutinib treatment. We have also identified the inhibition of NOX as a potential novel AF therapy approach.

Dysregulated Tgfbr2/ERK-Smad4/SOX2 Signaling Promotes Lung Squamous Cell Carcinoma Formation

Lung squamous cell carcinoma (SCC) is a common type of lung cancer. There is limited information on the genes and pathways that initiate lung SCC. Here, we report that loss of TGFβ type II receptor (Tgfbr2), frequently deleted in human lung cancer, led to predominant lung SCC development in Kras^G12D mice with a short latency, high penetrance, and extensive metastases. Tgfbr2-loss-driven lung SCCs resembled the salient features of human lung SCC, including histopathology, inflammatory microenvironment, and biomarker expression. Surprisingly, loss of Smad4, a key mediator of Tgfbr2, failed to drive lung SCC; instead, low levels of phosphorylated ERK1/2, a Smad-independent downstream effector of Tgfbr2, were tightly associated with lung SCC in both mouse and human. Mechanistically, inhibition of phosphorylated ERK1/2 significantly upregulated the expression of SOX2, an oncogenic driver of lung SCC, and cooperated with SMAD4 repression to elevate SOX2. Inhibition of ERK1/2 in Smad4^fl/fl ;Kras^G12D mice led to extensive lung SCC formation that resembled the SCC phenotype of Tgfbr2-deficient mice. Overall, we reveal a key role of ERK1/2 in suppressing SCC formation and demonstrate that dysregulated Tgfbr2/ERK-Smad4/SOX2 signaling drives lung SCC formation. We also present a mouse model of metastatic lung SCC that may be valuable for screening therapeutic targets. SIGNIFICANCE: This study sheds new light on the mechanisms underlying lung SCC formation driven by mutated Kras.

A generally conserved response to hypoxia in iPSC-derived cardiomyocytes from humans and chimpanzees

Despite anatomical similarities, there are differences in susceptibility to cardiovascular disease (CVD) between primates; humans are prone to myocardial ischemia, while chimpanzees are prone to myocardial fibrosis. Induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) allow for direct inter-species comparisons of the gene regulatory response to CVD-relevant perturbations such as oxygen deprivation, a consequence of ischemia. To gain insight into the evolution of disease susceptibility, we characterized gene expression levels in iPSC-CMs in humans and chimpanzees, before and after hypoxia and re-oxygenation. The transcriptional response to hypoxia is generally conserved across species, yet we were able to identify hundreds of species-specific regulatory responses including in genes previously associated with CVD. The 1,920 genes that respond to hypoxia in both species are enriched for loss-of-function intolerant genes; but are depleted for expression quantitative trait loci and cardiovascular-related genes. Our results indicate that response to hypoxic stress is highly conserved in humans and chimpanzees.

Cardiomyocyte SMAD4-Dependent TGF-β Signaling is Essential to Maintain Adult Heart Homeostasis

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SMAD4 is the central intracellular mediator of TGF-β pathway.

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CM-specific loss of SMAD4 causes cardiac dysfunction independent of fibrotic remodeling.

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Deletion CM-SMAD4 affects CM survival.

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CM-SMAD4 loss leads to down-regulation of several ion channels’ genes, resulting in cardiac conduction abnormalities.

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CM-SMAD4 deletion alters sarcomere shortening kinetics, in parallel with reduction in cardiac myosin-binding protein C levels.

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These results demonstrate a fundamental role for CM-SMAD4–dependent TGF-β signaling in adult heart homeostasis.

The role of the transforming growth factor (TGF)-β pathway in myocardial fibrosis is well recognized. However, the precise role of this signaling axis in cardiomyocyte (CM) biology is not defined. In TGF-β signaling, SMAD4 acts as the central intracellular mediator. To investigate the role of TGF-β signaling in CM biology, the authors deleted SMAD4 in adult mouse CMs. We demonstrate that CM-SMAD4–dependent TGF-β signaling is critical for maintaining cardiac function, sarcomere kinetics, ion-channel gene expression, and cardiomyocyte survival. Thus, our findings raise a significant concern regarding the therapeutic approaches that rely on systemic inhibition of the TGF-β pathway for the management of myocardial fibrosis.

SMAD4 Is Essential for Human Cardiac Mesodermal Precursor Cell Formation

Understanding stage‐specific molecular mechanisms of human cardiomyocyte (CM) progenitor formation and subsequent differentiation are critical to identify pathways that might lead to congenital cardiovascular defects and malformations. In particular, gene mutations in the transforming growth factor (TGF)β superfamily signaling pathways can cause human congenital heart defects, and murine loss of function studies of a central component in this pathway, Smad4, leads to early embryonic lethality. To define the role of SMAD4 at the earliest stages of human cardiogenesis, we generated SMAD4 mutant human embryonic stem cells (hESCs). Herein, we show that the loss of SMAD4 has no effect on hESC self‐renewal, or neuroectoderm formation, but is essential for the formation of cardiac mesoderm, with a subsequent complete loss of CM formation during human ES cell cardiogenesis. Via transcriptional profiling, we show that SMAD4 mutant cell lines fail to generate cardiac mesodermal precursors, clarifying a role of NODAL/SMAD4 signaling in cardiac mesodermal precursor formation via enhancing the expression of primitive streak genes. Since SMAD4 relative pathways have been linked to congenital malformations, it will become of interest to determine whether these may due, in part, to defective cell fate decision during cardiac mesodermal precursor formation. Stem Cells2018 Stem Cells2019;37:216–225

MiR-378 and BMP-Smad can influence the proliferation of sheep myoblast

MicroRNA (miRNA) is a sort of endogenous ~20-25 nt non-coding RNAs, and it can regulate a variety of biological events. We found the miR-378 may involve in regulating the muscle development of sheep during our previous research. However, the molecular mechanism of miR-378 regulating myoblast proliferation is still unclear. In this research, we predicted that BMP2 (Bone morphogenetic protein 2) was the target gene of miR-378 and the BMP-Smad signal pathway that BMP2 participated in playing an important role in the muscle development. Therefore, we tried to determine whether miR-378 influence myoblast proliferation of sheep through the BMP-Smad signal pathway. The results indicated that inhibit BMP-Smad signal pathway by interfering Smad4 to promote proliferation of sheep myoblasts; promote BMP-Smad signal pathway by interfering Smad7 to inhibit proliferation of sheep myoblasts; over-expression miR-378 promotes BMP-Smad signal pathway and myoblast proliferation in sheep; interfering miR-378 inhibits BMP-Smad signal pathway and myoblast proliferation in sheep. However, when both of which functioned at the myoblast, miR-378 could not fully depend on BMP-Smad signal pathway to regulate myoblast proliferation. In sum, both miR-378 and BMP-Smad can influence the proliferation of myoblast, but miR-378 does not target the 3' UTR of sheep BMP2.

RNA binding protein 24 deletion disrupts global alternative splicing and causes dilated cardiomyopathy

RNA splicing contributes to a broad spectrum of post-transcriptional gene regulation during normal development, as well as pathological manifestation of heart diseases. However, the functional role and regulation of splicing in heart failure remain poorly understood. RNA binding protein (RBP), a major component of the splicing machinery, is a critical factor in this process. RNA binding motif protein 24 (RBM24) is a tissue-specific RBP which is highly expressed in human and mouse heart. Previous studies demonstrated the functional role of RBM24 in the embryonic heart development. However, the role of RBM24 in postnatal heart development and heart disease has not been investigated. In this paper, using conditional RBM24 knockout mice, we demonstrated that ablation of RBM24 in postnatal heart led to rapidly progressive dilated cardiomyopathy (DCM), heart failure, and postnatal lethality. Global splicing profiling revealed that RBM24 regulated a network of genes related to cardiac function and diseases. Knockout of RBM24 resulted in misregulation of these splicing transitions which contributed to the subsequent development of cardiomyopathy. Notably, our analysis identified RBM24 as a splice factor that determined the splicing switch of a subset of genes in the sacomeric Z-disc complex, including Titin, the major disease gene of DCM and heart failure. Together, this study identifies regulation of RNA splicing by RBM24 as a potent player in remodeling of heart during postnatal development, and provides novel mechanistic insights to the pathogenesis of DCM.

GDF11 Modulates Ca2+-Dependent Smad2/3 Signaling to Prevent Cardiomyocyte Hypertrophy

Growth differentiation factor 11 (GDF11), a member of the transforming growth factor-β family, has been shown to act as a negative regulator in cardiac hypertrophy. Ca²⁺ signaling modulates cardiomyocyte growth; however, the role of Ca²⁺-dependent mechanisms in mediating the effects of GDF11 remains elusive. Here, we found that GDF11 induced intracellular Ca²⁺ increases in neonatal rat cardiomyocytes and that this response was blocked by chelating the intracellular Ca²⁺ with BAPTA-AM or by pretreatment with inhibitors of the inositol 1,4,5-trisphosphate (IP₃) pathway. Moreover, GDF11 increased the phosphorylation levels and luciferase activity of Smad2/3 in a concentration-dependent manner, and the inhibition of IP₃-dependent Ca²⁺ release abolished GDF11-induced Smad2/3 activity. To assess whether GDF11 exerted antihypertrophic effects by modulating Ca²⁺ signaling, cardiomyocytes were exposed to hypertrophic agents (100 nM testosterone or 50 μM phenylephrine) for 24 h. Both treatments increased cardiomyocyte size and [³H]-leucine incorporation, and these responses were significantly blunted by pretreatment with GDF11 over 24 h. Moreover, downregulation of Smad2 and Smad3 with siRNA was accompanied by inhibition of the antihypertrophic effects of GDF11. These results suggest that GDF11 modulates Ca²⁺ signaling and the Smad2/3 pathway to prevent cardiomyocyte hypertrophy.

The TGFβ superfamily in cardiac dysfunction

TGFβ superfamily includes the transforming growth factor βs (TGFβs), bone morphogenetic proteins (BMPs), growth and differentiation factors (GDFs) and Activin/Inhibin families of ligands. Among the 33 members of TGFβ superfamily ligands, many act on multiple types of cells within the heart, including cardiomyocytes, cardiac fibroblasts/myofibroblasts, coronary endothelial cells, smooth muscle cells, and immune cells (e.g. monocytes/macrophages and neutrophils). In this review, we highlight recent discoveries on TGFβs, BMPs, and GDFs in different cardiac residential cellular components, in association with functional impacts in heart development, injury repair, and dysfunction. Specifically, we will review the roles of TGFβs, BMPs, and GDFs in cardiac hypertrophy, fibrosis, contractility, metabolism, angiogenesis, and regeneration.

The Impact of Human Parvovirus B19 Infection on Heart Failure and Anemia with Reference to Iron Metabolism Markers in an Adult Woman

A 35-year-old woman with fever, edema and rash was admitted. Pleural effusion and cardiomegaly were observed. A laboratory analysis revealed anemia with iron deficiency and elevated human parvovirus B19 (B19V) immunoglobulin M. The patient's hepcidin-25 and erythroferrone levels were not elevated compared to those observed later in her clinical course. On the other hand, her growth differentiation factor-15 (GDF-15) levels were elevated. She was diagnosed to have heart failure symptoms and anemia with specific iron metabolism abnormalities due to a B19V infection. After providing supportive treatment, the heart failure symptoms disappeared and her anemia had improved. This case emphasizes the need to include a B19V infection in the differential diagnosis when we encounter cases demonstrating reversible heart failure with anemia.

Quantitative single-molecule study of TGF-β/Smad signaling

TGF-β/Smad signaling pathway triggers diverse cellular responses among different cell types and environmental conditions. Quantitative analysis of protein-protein interactions involved in TGF-β/Smad signaling is demanded for understanding the molecular mechanism of this signaling pathway. Live-cell single-molecule microcopy with high spatiotemporal resolution is a new tool to monitor key molecular events in a real-time manner. In this review, we mainly presented the recent work on the quantitative characterization of TGF-β/Smad signaling proteins by single-molecule method, and showed how it enabled us to obtain new insights about this canonical signaling process.

Effects of Wenxin Keli on Cardiac Hypertrophy and Arrhythmia via Regulation of the Calcium/Calmodulin Dependent Kinase II Signaling Pathway

We investigated the effects of Wenxin Keli (WXKL) on the Calcium/Calmodulin dependent kinase II (CaMK II) signal transduction pathway with transverse aortic constriction (TAC) rats. Echocardiographic measurements were obtained 3 and 9 weeks after the surgery. Meanwhile, the action potentials (APDs) were recorded using the whole-cell patch clamp technique, and western blotting was used to assess components of the CaMK II signal transduction pathway. At both 3 and 9 weeks after treatment, the fractional shortening (FS%) increased in the WXKL group compared with the TAC group. The APD90 of the TAC group was longer than that of the Sham group and was markedly shortened by WXKL treatment. Western blotting results showed that the protein expressions of CaMK II, phospholamban (PLB), and ryanodine receptor 2 (RYR2) were not statistically significant among the different groups at both treatment time points. However, WXKL treatment decreased the protein level and phosphorylation of CaMK II (Thr-286) and increased the protein level and phosphorylation of PLB (Thr-17) and the phosphorylation of RYR2 (Ser-2814). WXKL also decreased the accumulation of type III collagen fibers. In conclusion, WXKL may improve cardiac function and inhibit the arrhythmia by regulating the CaMK II signal transduction pathway.

Manipulating PML SUMOylation via Silencing UBC9 and RNF4 Regulates Cardiac Fibrosis

The promyelocytic leukemia protein (PML) is essential in the assembly of dynamic subnuclear structures called PML nuclear bodies (PML-NBs), which are involved in regulating diverse cellular functions. However, the possibility of PML being involved in cardiac disease has not been examined. In mice undergoing transverse aortic constriction (TAC) and arsenic trioxide (ATO) injection, transforming growth factor β1 (TGF-β1) was upregulated along with dynamic alteration of PML SUMOylation. In cultured neonatal mouse cardiac fibroblasts (NMCFs), ATO, angiotensin II (Ang II), and fetal bovine serum (FBS) significantly triggered PML SUMOylation and the assembly of PML-NBs. Inhibition of SUMOylated PML by silencing UBC9, the unique SUMO E2-conjugating enzyme, reduced the development of cardiac fibrosis and partially improved cardiac function in TAC mice. In contrast, enhancing SUMOylated PML accumulation, by silencing RNF4, a poly-SUMO-specific E3 ubiquitin ligase, accelerated the induction of cardiac fibrosis and promoted cardiac function injury. PML colocalized with Pin1 (a positive regulator for TGF-β1 mRNA expression in PML-NBs) and increased TGF-β1 activity. These findings suggest that the UBC9/PML/RNF4 axis plays a critical role as an important SUMO pathway in cardiac fibrosis. Modulating the protein levels of the pathway provides an attractive therapeutic target for the treatment of cardiac fibrosis and heart failure.

Triptolide Upregulates Myocardial Forkhead Helix Transcription Factor p3 Expression and Attenuates Cardiac Hypertrophy

The forkhead/winged helix transcription factor (Fox) p3 can regulate the expression of various genes, and it has been reported that the transfer of Foxp3-positive T cells could ameliorate cardiac hypertrophy and fibrosis. Triptolide (TP) can elevate the expression of Foxp3, but its effects on cardiac hypertrophy remain unclear. In the present study, neonatal rat ventricular myocytes (NRVM) were isolated and stimulated with angiotensin II (1 μmol/L) to induce hypertrophic response. The expression of Foxp3 in NRVM was observed by using immunofluorescence assay. Fifty mice were randomly divided into five groups and received vehicle (control), isoproterenol (Iso, 5 mg/kg, s.c.), one of three doses of TP (10, 30, or 90 μg/kg, i.p.) for 14 days, respectively. The pathological morphology changes were observed after Hematoxylin and eosin, lectin and Masson's trichrome staining. The levels of serum brain natriuretic peptide (BNP) and troponin I were determined by enzyme-linked immunosorbent assay and chemiluminescence, respectively. The mRNA and protein expressions of α- myosin heavy chain (MHC), β-MHC and Foxp3 were determined using real-time PCR and immunohistochemistry, respectively. It was shown that TP (1, 3, 10 μg/L) treatment significantly decreased cell size, mRNA and protein expression of β-MHC, and upregulated Foxp3 expression in NRVM. TP also decreased heart weight index, left ventricular weight index and, improved myocardial injury and fibrosis; and decreased the cross-scetional area of the myocardium, serum cardiac troponin and BNP. Additionally, TP markedly reduced the mRNA and protein expression of myocardial β-MHC and elevated the mRNA and protein expression of α-MHC and Foxp3 in a dose-dependent manner. In conclusion, TP can effectively ameliorate myocardial damage and inhibit cardiac hypertrophy, which is at least partly related to the elevation of Foxp3 expression in cardiomyocytes.

microRNA expression profiling and functional annotation analysis of their targets modulated by oxidative stress during embryonic heart development in diabetic mice

Maternal pregestational diabetes mellitus (PGDM) induces congenital heart defects (CHDs). The molecular mechanism underlying PGDM-induced CHDs is unknown. microRNAs (miRNAs), small non-coding RNAs, repress gene expression at the posttranscriptional level and play important roles in heart development. We performed a global miRNA profiling study to assist in revealing potential miRNAs modulated by PGDM and possible developmental pathways regulated by miRNAs during heart development. A total of 149 mapped miRNAs in the developing heart were significantly altered by PGDM. Bioinformatics analysis showed that the majority of the 2111 potential miRNA target genes were associated with cardiac development-related pathways including STAT3 and IGF-1 and transcription factors (Cited2, Zeb2, Mef2c, Smad4 and Ets1). Overexpression of the antioxidant enzyme, superoxide dismutase 1, reversed PGDM-altered miRNAs, suggesting that oxidative stress is responsible for dysregulation of miRNAs. Thus, our study provides the foundation for further investigation of a miRNA-dependent mechanism underlying PGDM-induced CHDs.

GDF 15--A Novel Biomarker in the Offing for Heart Failure

Background:

Several diagnostic and prognostic biomarkers are being explored in heart failure. GDF-15 belongs to the transforming growth factor β (TGF-β) cytokine family that is highly up regulated in inflammatory conditions. We undertook this systematic review to summarize the current evidence on the utility of GDF-15 as a biomarker in heart failure.

Design and Methods:

Multiple electronic databases for studies that reported the association between GDF- 15 and heart failure were searched using different electronic databases such as MEDLINE, Science Direct, Springer Link, Scopus, Cochrane Reviews, and Google Scholar using pre-defined inclusion- exclusion criteria.

Results:

Twenty one original studies were identified that included data from 20,920 study participants. GDF 15 was found to be a strong prognosticator of all-cause mortality in heart failure patients. Several studies found the benefit of using GDF-15 as a component of a multi-biomarker strategy in prognosticating patients with heart failure.

Conclusion:

More studies are warranted to elucidate the molecular pathways involving GDF-15 and to see how knowledge about GDF-15 can be used to make therapeutic decisions in the clinic.

Fibulin-2 is essential for angiotensin II-induced myocardial fibrosis mediated by transforming growth factor (TGF)-β

Fibrosis is an ominous pathological process in failing myocardium, but its pathogenesis is poorly understood. We recently reported that loss of an extracellular matrix (ECM) protein, fibulin-2, protected against ventricular dysfunction after myocardial infarction (MI) in association with absence of activation of transforming growth factor (TGF)-β signaling and suppressed upregulation of ECM protein expression during myocardial remodeling. Here we investigated the role of fibulin-2 in the development of myocardial hypertrophy and fibrosis induced by continuous pressor-dosage of angiotensin II (Ang II) infusion. Both wild type (WT) and fibulin-2 null (Fbln2KO) mice developed comparable hypertension and myocardial hypertrophy by Ang II infusion. However, myocardial fibrosis with significant upregulation of collagen type I and III mRNA was only seen in WT but not in Fbln2KO mice.Transforming growth factor (TGF)-β1 mRNA and its downstream signal, Smad2, were significantly upregulated in WT by Ang II, whereas there were no Ang II-induced changes in Flbn2KO, suggesting fibulin-2 is necessary for Ang II-induced TGF-β signaling that induces myocardial fibrosis. To test whether fibulin-2 is sufficient for Ang II-induced TGF-β upregulation, isolated Flbn2KO cardiac fibroblasts were treated with Ang II after transfecting with fibulin-2 expression vector or pretreating with recombinant fibulin-2 protein. Ang II-induced TGF-β signaling in Fbln2KO cells was partially rescued by exogenous fibulin-2, suggesting that fibulin-2 is required and probably sufficient for Ang II-induced TGF-β activation. Smad2 phosphorylation was induced just by adding recombinant fibulin-2 to KO cells, suggesting that extracellular interaction between fibulin-2 and latent TGF-β triggered initial TGF-β activation. Our study indicates that Ang II cannot induce TGF-β activation without fibulin-2 and that fibulin-2 has an essential role in Ang II-induced TGF-β signaling and subsequent myocardial fibrosis. Fibulin-2 can be considered as a critical regulator of TGF-β that induces myocardial fibrosis.

miR-199-sponge transgenic mice develop physiological cardiac hypertrophy

AIMS

Overexpression of either member of the miR-199 family, miR-199a-5p, or miR-199b-5p (hereinafter referred to as miR-199a or miR-199b) promotes pathological cardiac hypertrophy, but little is known about the role of endogenous miR-199 in cardiac development and disease. Our study aimed to determine the physiological function of the endogenous miR-199 family in cardiac homeostasis maintenance.

METHODS AND RESULTS

We generated a sponge transgenic mouse model with a specific disruption of miR-199 in the heart. To our surprise, we found that knockdown of endogenous miR-199 caused physiological cardiac hypertrophy characterized by an increased heart weight and cardiomyocyte size, but with normal cardiac morphology and function. Furthermore, we also identified PGC1α as the target gene of the miR-199 family, and PGC1α was also increased in sponge transgenic mice.

CONCLUSION

Inhibition of endogenous miR-199 led to physiological cardiac hypertrophy probably due to the up-regulation of PGC1α, uncovering a surprising role for endogenous miR-199 in the maintenance of cardiac homeostasis.

Altered long noncoding RNA expression profiles in the myocardium of rats with ischemic heart failure

AIMS

Despite significant advances in the treatment of coronary artery disease, the prevalence of ischemic heart failure is still increasing rapidly. Long noncoding RNAs are a novel class of gene regulators and may contribute to disease cause. The aim of the present study was to investigate the expression profiles of long noncoding RNAs and their potential functional roles in ischemic heart failure.

METHODS

We applied a well-established ischemic heart failure rat model and performed long noncoding RNA microarray experiments on the left ventricular tissue of rats with ischemic heart failure and under sham control. Differentially expressed long noncoding RNAs and mRNAs were identified through fold-change filtering. Bioinformatic analyses were performed to predict the potential biological roles of key long noncoding RNAs.

RESULTS

We found that 1197 long noncoding RNAs and 2066 mRNAs were upregulated, whereas 1403 long noncoding RNAs and 2871 mRNAs were downregulated in failing hearts (fold-change > 2.0). We also identified 331 pairs of differentially expressed long noncoding RNAs and nearby coding genes, which contained 291 long noncoding RNAs and 296 mRNAs. Expression levels of four long noncoding RNA-mRNA pairs, which might be involved in the pathogenesis of ischemic heart failure were confirmed by quantitative real-time PCR.

CONCLUSION

Our study identified a set of long noncoding RNAs that were aberrantly expressed in rats with ischemic heart failure and might be involved in the pathogenesis of ischemic heart failure. The results of our study may provide a novel perspective for better understanding the molecular basis of ischemic heart failure.

Molecular switches under TGFβ signalling during progression from cardiac hypertrophy to heart failure

Cardiac hypertrophy is a mechanism to compensate for increased cardiac work load, that is, after myocardial infarction or upon pressure overload. However, in the long run cardiac hypertrophy is a prevailing risk factor for the development of heart failure. During pathological remodelling processes leading to heart failure, decompensated hypertrophy, death of cardiomyocytes by apoptosis or necroptosis and fibrosis as well as a progressive dysfunction of cardiomyocytes are apparent. Interestingly, the induction of hypertrophy, cell death or fibrosis is mediated by similar signalling pathways. Therefore, tiny changes in the signalling cascade are able to switch physiological cardiac remodelling to the development of heart failure. In the present review, we will describe examples of these molecular switches that change compensated hypertrophy to the development of heart failure and will focus on the importance of the signalling cascades of the TGFβ superfamily in this process. In this context, potential therapeutic targets for pharmacological interventions that could attenuate the progression of heart failure will be discussed.

Myhre syndrome: Clinical features and restrictive cardiopulmonary complications

Myhre syndrome, a connective tissue disorder characterized by deafness, restricted joint movement, compact body habitus, and distinctive craniofacial and skeletal features, is caused by heterozygous mutations in SMAD4. Cardiac manifestations reported to date have included patent ductus arteriosus, septal defects, aortic coarctation and pericarditis. We present five previously unreported patients with Myhre syndrome. Despite varied clinical phenotypes all had significant cardiac and/or pulmonary pathology and abnormal wound healing. Included herein is the first report of cardiac transplantation in patients with Myhre syndrome. A progressive and markedly abnormal fibroproliferative response to surgical intervention is a newly delineated complication that occurred in all patients and contributes to our understanding of the natural history of this disorder. We recommend routine cardiopulmonary surveillance for patients with Myhre syndrome. Surgical intervention should be approached with extreme caution and with as little invasion as possible as the propensity to develop fibrosis/scar tissue is dramatic and can cause significant morbidity and mortality.

miR-199a impairs autophagy and induces cardiac hypertrophy through mTOR activation

Basal autophagy is tightly regulated by transcriptional and epigenetic factors to maintain cellular homeostasis. Dysregulation of cardiac autophagy is associated with heart diseases, including cardiac hypertrophy, but the mechanism governing cardiac autophagy is rarely identified. To analyze the in vivo function of miR-199a in cardiac autophagy and cardiac hypertrophy, we generated cardiac-specific miR-199a transgenic mice and showed that overexpression of miR-199a was sufficient to inhibit cardiomyocyte autophagy and induce cardiac hypertrophy in vivo. miR-199a impaired cardiomyocyte autophagy in a cell-autonomous manner by targeting glycogen synthase kinase 3β (GSK3β)/mammalian target of rapamycin (mTOR) complex signaling. Overexpression of autophagy related gene 5 (Atg5) attenuated the hypertrophic effects of miR-199a overexpression on cardiomyocytes, and activation of autophagy using rapamycin was sufficient to restore cardiac autophagy and decrease cardiac hypertrophy in miR-199a transgenic mice. These results reveal a novel role of miR-199a as a key regulator of cardiac autophagy, suggesting that targeting miRNAs controlling autophagy as a potential therapeutic strategy for cardiac disease.

Cardiac Fibrosis Alleviated by Exercise Training Is AMPK-Dependent

Regular exercise can protect the heart against external stimuli, but the mechanism is not well understood. We determined the role of adenosine monophosphate-activated protein kinase (AMPK) in regulating swimming exercise-mediated cardiac protection against β-adrenergic receptor overstimulation with isoproterenol (ISO) in mice. Ten-week-old AMPKα2^+/+ and AMPKα2-knockout (AMPKα2^-/-) littermates were subjected to 4 weeks of swimming training (50 min daily, 6 days a week) or housed under sedentary conditions. The mice received daily subcutaneous injection of ISO (5 mg/kg/d), a nonselective β-adrenergic receptor agonist, during the last 2 weeks of swimming training. Swimming training alleviated ISO-induced cardiac fibrosis in AMPKα2^+/+ mice but not AMPKα2^-/- mice. Swimming training activated cardiac AMPK in AMPKα2^+/+ mice. Furthermore, swimming training attenuated ISO-induced production of reactive oxygen species (ROS) and expression of NADPH oxidase and promoted the expression of antioxidant enzymes in AMPKα2^+/+ mice but not AMPKα2^-/- mice. In conclusion, swimming training attenuates ISO-induced cardiac fibrosis by inhibiting the NADPH oxidase–ROS pathway mediated by AMPK activation. Our findings provide a new mechanism for the cardioprotective effects of exercise.

GDF-15 as a Target and Biomarker for Diabetes and Cardiovascular Diseases: A Translational Prospective

Growth differentiation factor-15 (GDF-15) is a stress responsive cytokine. It is highly expressed in cardiomyocytes, adipocytes, macrophages, endothelial cells, and vascular smooth muscle cells in normal and pathological condition. GDF-15 increases during tissue injury and inflammatory states and is associated with cardiometabolic risk. Increased GDF-15 levels are associated with cardiovascular diseases such as hypertrophy, heart failure, atherosclerosis, endothelial dysfunction, obesity, insulin resistance, diabetes, and chronic kidney diseases in diabetes. Increased GDF-15 level is linked with the progression and prognosis of the disease condition. Age, smoking, and environmental factors are other risk factors that may increase GDF-15 level. Most of the scientific studies reported that GDF-15 plays a protective role in different tissues. However, few reports show that the deficiency of GDF-15 is beneficial against vascular injury and inflammation. GDF-15 protects heart, adipose tissue, and endothelial cells by inhibiting JNK (c-Jun N-terminal kinase), Bad (Bcl-2-associated death promoter), and EGFR (epidermal growth factor receptor) and activating Smad, eNOS, PI3K, and AKT signaling pathways. The present review describes the different animal and clinical studies and patent updates of GDF-15 in diabetes and cardiovascular diseases. It is a challenge for the scientific community to use GDF-15 information for patient monitoring, clinical decision-making, and replacement of current treatment strategies for diabetic and cardiovascular diseases.

Geft is dispensable for the development of the second heart field

Geft is a guanine nucleotide exchange factor, which can specifically activate Rho family of small GTPase by catalyzing the exchange of bound GDP for GTP. Geft is highly expressed in the excitable tissue as heart and skeletal muscle and plays important roles in many cellular processes, such as cell proliferation, migration, and cell fate decision. However, the in vivo role of Geft remains unknown. Here, we generated a Geft conditional knockout mouse by flanking exons 5-17 of Geft with loxP sites. Cre-mediated deletion of the Geft gene in heart using Mef2c-Cre transgenic mice resulted in a dramatic decrease of Geft expression. Geft knockout mice develop normally and exhibit no discernable phenotype, suggesting Geft is dispensable for the development of the second heart field in mouse. The Geft conditional knockout mouse will be a valuable genetic tool for uncovering the in vivo roles of Geft during development and in adult homeostasis.