Role of the Wnt-Frizzled system in cardiac pathophysiology: a rapidly developing, poorly understood area with enormous potential

Patient-specific genomics and cross-species functional analysis implicate LRP2 in hypoplastic left heart syndrome

Congenital heart diseases (CHDs), including hypoplastic left heart syndrome (HLHS), are genetically complex and poorly understood. Here, a multidisciplinary platform was established to functionally evaluate novel CHD gene candidates, based on whole-genome and iPSC RNA sequencing of a HLHS family-trio. Filtering for rare variants and altered expression in proband iPSCs prioritized 10 candidates. siRNA/RNAi-mediated knockdown in healthy human iPSC-derived cardiomyocytes (hiPSC-CM) and in developing Drosophila and zebrafish hearts revealed that LDL receptor-related protein LRP2 is required for cardiomyocyte proliferation and differentiation. Consistent with hypoplastic heart defects, compared to patents the proband's iPSC-CMs exhibited reduced proliferation. Interestingly, rare, predicted-damaging LRP2 variants were enriched in a HLHS cohort; however, understanding their contribution to HLHS requires further investigation. Collectively, we have established a multi-species high-throughput platform to rapidly evaluate candidate genes and their interactions during heart development, which are crucial first steps toward deciphering oligogenic underpinnings of CHDs, including hypoplastic left hearts.

Genetic Factors Involved in Cardiomyopathies and in Cancer

Cancer therapy-induced cardiomyopathy (CCM) manifests as left ventricular (LV) dysfunction and heart failure (HF). It is associated withparticular pharmacological agents and it is typically dose dependent, but significant individual variability has been observed. History of prior cardiac disease, abuse of toxics, cardiac overload conditions, age, and genetic predisposing factors modulate the degree of the cardiac reserve and the response to the injury. Genetic/familial cardiomyopathies (CMY) are increasingly recognized in general populations with an estimated prevalence of 1:250. Association between cardiac and oncologic diseases regarding genetics involves not only the toxicity process, but pathogenicity. Genetic variants in germinal cells that cause CMY (LMNA, RAS/MAPK) can increase susceptibility for certain types of cancer. The study of mutations found in cancer cells (somatic) has revealed the implication of genes commonly associated with the development of CMY. In particular, desmosomal mutations have been related to increased undifferentiation and invasiveness of cancer. In this article, the authors review the knowledge on the relevance of environmental and genetic background in CCM and give insights into the shared genetic role in the pathogenicity of the cancer process and development of CMY.

Reduction of Secreted Frizzled-Related Protein 5 Drives Vascular Calcification through Wnt3a-Mediated Rho/ROCK/JNK Signaling in Chronic Kidney Disease

Vascular calcification (VC) is commonly associated with bone loss in patients with chronic kidney disease (CKD). The Wingless-related integration site (Wnt) regulates osteoblast activation through canonical signaling pathways, but the common pathophysiology of these pathways during VC and bone loss has not been identified. A rat model of adenine-induced CKD with VC was used in this study. The rats were fed 0.75% adenine (2.5% protein, 0.92% phosphate) with or without intraperitoneal injection of calcitriol (0.08 µg/kg/day) for 4 weeks. Angiotensin II (3 µM)-induced VC was achieved in high phosphate medium (3 mM) through its effect on vascular smooth muscle cells (VSMCs). In an mRNA profiler polymerase chain reaction assay of the Wnt signaling pathway, secreted frizzled-related protein 5 (sFRP5) levels were significantly decreased in the CKD rat model compared with the control group. The repression of sFRP5 on VSMC trans-differentiation was mediated through Rho/Rho-associated coiled coil containing protein kinase (ROCK) and c-Jun N-terminal kinase (JNK) pathways activated by Wnt3a. In a proof of concept study conducted with patients with CKD, serum sFRP5 concentrations were significantly lower in subjects with VC than in those without VC. Our findings suggest that repression of sFRP5 is associated with VC in the CKD environment via activation of the noncanonical Wnt pathway, and thus that sFRP5 might be a novel therapeutic target for VC in CKD.

Wnt/β-catenin in ischemic myocardium: interactions and signaling pathways as a therapeutic target

Cardiovascular disease (CVD) is still a factor of mortality in the whole world. Through canonical and noncanonical pathways and with different receptors, the Wnt/β-catenin signaling pathway plays an essential role in response to heart injuries. Wnt regulates the mobilization and proliferation of cells in endothelium and epicardium in an infarcted heart. Therefore, with its profibrotic effects as well as its antagonism with other proteins, Wnt/β-catenin signaling pathway leads to beneficial effects on fibrosis and cardiac remodeling in myocardium. In addition, Wnt increases the proliferation and differentiation of cardiac progenitors in an ischemic heart. Complex interactions and dual activity of Wnt, the changes in its expression, and mutations that can change its activity during heart development have an adverse effect on cardiac myocardium after injury. However, targeting the Wnt in myocardium with cellular and molecular pathways can be suggested to improve and repair ischemic heart. Given these challenges, in this review article, we deal with the role of Wnt/β-catenin signaling pathway as well as its interactions with other cells and molecules in an ischemic myocardium.

Biomarkers for the identification of cardiac fibroblast and myofibroblast cells

Experimental research has recognized the importance of cardiac fibroblast and myofibroblast cells in heart repair and function. In a normal healthy heart, the cardiac fibroblast plays a central role in the structural, electrical, and chemical aspects within the heart. Interestingly, the transformation of cardiac fibroblast cells to cardiac myofibroblast cells is suspected to play a vital part in the development of heart failure. The ability to differentiate between the two cells types has been a challenge. Myofibroblast cells are only expressed in the stressed or failing heart, so a better understanding of cell function may identify therapies that aid repair of the damaged heart. This paper will provide an outline of what is currently known about cardiac fibroblasts and myofibroblasts, the physiological and pathological roles within the heart, and causes for the transition of fibroblasts into myoblasts. We also reviewed the potential markers available for characterizing these cells and found that there is no single-cell specific marker that delineates fibroblast or myofibroblast cells. To characterize the cells of fibroblast origin, vimentin is commonly used. Cardiac fibroblasts can be identified using discoidin domain receptor 2 (DDR2) while α-smooth muscle actin is used to distinguish myofibroblasts. A known cytokine TGF-β₁ is well established to cause the transformation of cardiac fibroblasts to myofibroblasts. This review will also discuss clinical treatments that inhibit or reduce the actions of TGF-β₁ and its contribution to cardiac fibrosis and heart failure.

EM-mosaic detects mosaic point mutations that contribute to congenital heart disease

BACKGROUND

The contribution of somatic mosaicism, or genetic mutations arising after oocyte fertilization, to congenital heart disease (CHD) is not well understood. Further, the relationship between mosaicism in blood and cardiovascular tissue has not been determined.

METHODS

We developed a new computational method, EM-mosaic (Expectation-Maximization-based detection of mosaicism), to analyze mosaicism in exome sequences derived primarily from blood DNA of 2530 CHD proband-parent trios. To optimize this method, we measured mosaic detection power as a function of sequencing depth. In parallel, we analyzed our cohort using MosaicHunter, a Bayesian genotyping algorithm-based mosaic detection tool, and compared the two methods. The accuracy of these mosaic variant detection algorithms was assessed using an independent resequencing method. We then applied both methods to detect mosaicism in cardiac tissue-derived exome sequences of 66 participants for which matched blood and heart tissue was available.

RESULTS

EM-mosaic detected 326 mosaic mutations in blood and/or cardiac tissue DNA. Of the 309 detected in blood DNA, 85/97 (88%) tested were independently confirmed, while 7/17 (41%) candidates of 17 detected in cardiac tissue were confirmed. MosaicHunter detected an additional 64 mosaics, of which 23/46 (50%) among 58 candidates from blood and 4/6 (67%) of 6 candidates from cardiac tissue confirmed. Twenty-five mosaic variants altered CHD-risk genes, affecting 1% of our cohort. Of these 25, 22/22 candidates tested were confirmed. Variants predicted as damaging had higher variant allele fraction than benign variants, suggesting a role in CHD. The estimated true frequency of mosaic variants above 10% mosaicism was 0.14/person in blood and 0.21/person in cardiac tissue. Analysis of 66 individuals with matched cardiac tissue available revealed both tissue-specific and shared mosaicism, with shared mosaics generally having higher allele fraction.

CONCLUSIONS

We estimate that ~ 1% of CHD probands have a mosaic variant detectable in blood that could contribute to cardiac malformations, particularly those damaging variants with relatively higher allele fraction. Although blood is a readily available DNA source, cardiac tissues analyzed contributed ~ 5% of somatic mosaic variants identified, indicating the value of tissue mosaicism analyses.

Direct and Indirect Suppression of Scn5a Gene Expression Mediates Cardiac Na+ Channel Inhibition by Wnt Signalling

BACKGROUND

Myocardial infarction and heart failure are associated with reduced voltage-gated Na⁺ current (I_Na) that promotes arrhythmias and sudden deaths. We have previously shown that the Wnt/β-catenin signalling (Wnt signalling), which is active in heart disease, reduces cardiac I_Na, suggesting that Wnt signalling may be a potential therapeutic target. However, because Wnt signalling is required for the homeostasis of many noncardiac tissues, administration of Wnt inhibitors to heart patients would cause significant side effects. The present study aims to elucidate the molecular mechanisms of cardiac I_Na inhibition by Wnt, which would identify cardiac-specific therapeutic targets.

METHODS

Wnt signalling was activated in neonatal rat ventricular myocytes by Wnt3a protein. Adenovirus expressing Wnt3a was injected into the adult rat ventricle. CRISPR/Cas9 and chromatin immunoprecipitation were used for mechanistic studies.

RESULTS

Wnt signalling activation in neonatal rat ventricular myocytes reduced Na_v1.5 protein and Scn5a mRNA, but increased Tbx3, a known suppressor of Scn5a. Chromatin immunoprecipitation showed that Wnt signalling inhibits Scn5a expression through downstream mediator (TCF4) binding to both Tbx3 and Scn5a promoters. Overexpression or knockdown of Tbx3 directly modified Na_v1.5 and I_Na, whereas CRISPR/Cas9-induced mutations at TCF4 binding sites within the Scn5a promoter attenuated Wnt inhibition of Scn5a and Na_v1.5. In adult rat hearts, adenovirus expressing Wnt3a reduced Na_v1.5, increased QRS duration in electrocardiogram, and increased the susceptibility to ventricular tachycardia.

CONCLUSIONS

Wnt signalling inhibits the Na⁺ channel by direct and indirect (via Tbx3) suppression of Scn5a transcription. Strategies to block TCF4 binding to the Tbx3 and Scn5a promoters would represent novel strategies for cardiac-specific inhibition of the Wnt pathway to rescue I_Na and prevent sudden cardiac deaths.

Lack of association between TCF7L2 gene variants and type 2 diabetes mellitus in a Brazilian sample of patients with the risk for cardiovascular disease

OBJECTIVE

Genetic variants in the transcription factor 7-like 2 (TCF7L2) gene have been described as the most noteworthy ones regarding the type 2 diabetes mellitus (T2DM) liability. This work is aimed to evaluate the association between rs12255372 and rs7903146 polymorphisms and T2DM in patients with cardiovascular disease (CAD) risk.

METHODS

A sample of six hundred and forty-seven patients that underwent the coronary angiography in a Cardiac Catheterization Lab was evaluated. The patients were investigated for the presence of T2DM and coronary stenosis. The TCF7L2 polymorphisms were genotyped by real-time PCR and the haplotype analysis was performed with the MLOCUS software. All genetic tests were carried out by considering the haplotype combinations in patients divided into three groups: 0 - carrying none disease risk allele, 1 - carrying one or two risk alleles and 2 - carrying three or four risk alleles.

RESULTS

No significant associations between TCF7L2 risk haplotypes and the presence of T2DM or CAD were detected.

CONCLUSIONS

Our results indicate that the TCF7L2 rs12255372 and rs7903146 polymorphisms do not influence T2DM in Brazilian patients with the high risk for CAD. Therefore, we assume that these variants may only be relevant for a specific subgroup of T2DM patients or some particular human population.

Interventions in WNT Signaling to Induce Cardiomyocyte Proliferation: Crosstalk with Other Pathways

Myocardial infarction is a frequent cardiovascular event and a major cause for cardiomyocyte loss. In adult mammals, cardiomyocytes are traditionally considered to be terminally differentiated cells, unable to proliferate. Therefore, the wound-healing response in the infarct area typically yields scar tissue rather than newly formed cardiomyocytes. In the last decade, several lines of evidence have challenged the lack of proliferative capacity of the differentiated cardiomyocyte: studies in zebrafish and neonatal mammals have convincingly demonstrated the regenerative capacity of cardiomyocytes. Moreover, multiple signaling pathways have been identified in these models that-when activated in adult mammalian cardiomyocytes-can reactivate the cell cycle in these cells. However, cardiomyocytes frequently exit the cell cycle before symmetric division into daughter cells, leading to polyploidy and multinucleation. Now that there is more insight into the reactivation of the cell cycle machinery, other prerequisites for successful symmetric division of cardiomyocytes, such as the control of sarcomere disassembly to allow cytokinesis, require more investigation. This review aims to discuss the signaling pathways involved in cardiomyocyte proliferation, with a specific focus on wingless/int-1 protein signaling. Comparing the conflicting results from in vitro and in vivo studies on this pathway illustrates that the interaction with other cells and structures around the infarct is likely to be essential to determine the outcome of these interventions. The extensive crosstalk with other pathways implicated in cardiomyocyte proliferation calls for the identification of nodal points in the cell signaling before cardiomyocyte proliferation can be moved forward toward clinical application as a cure of cardiac disease. SIGNIFICANCE STATEMENT: Evidence is mounting that proliferation of pre-existing cardiomyocytes can be stimulated to repair injury of the heart. In this review article, an overview is provided of the different signaling pathways implicated in cardiomyocyte proliferation with emphasis on wingless/int-1 protein signaling, crosstalk between the pathways, and controversial results obtained in vitro and in vivo.

Cardiac-Specific Overexpression of Catalytically Inactive Corin Reduces Edema, Contractile Dysfunction, and Death in Mice with Dilated Cardiomyopathy

Humans with dilated cardiomyopathy (DCM) and heart failure (HF) develop low levels of corin, a multi-domain, cardiac-selective serine protease involved in natriuretic peptide cleavage and sodium and water regulation. However, experimental restoration of corin levels markedly attenuates HF progression. To determine whether the beneficial effects of corin in HF require catalytic activity, we engineered cardiac overexpression of an enzymatically inactive corin transgene (corin-Tg(i)). On a wild-type (WT) background, corin-Tg(i) had no evident phenotypic effects. However, in a well-established genetic model of DCM, corin-Tg(i)/DCM mice had increased survival (p < 0.01 to 0.001) vs. littermate corin-WT/DCM controls. Pleural effusion (p < 0.01), lung edema (p < 0.05), systemic extracellular free water (p < 0.01), and heart weight were decreased (p < 0.01) in corin-Tg(i)/DCM vs. corin-WT/DCM mice. Cardiac ejection fraction and fractional shortening improved (p < 0.01), while ventricular dilation decreased (p < 0.0001) in corin-Tg(i)/DCM mice. Plasma atrial natriuretic peptide, cyclic guanosine monophosphate, and neprilysin were significantly decreased. Cardiac phosphorylated glycogen synthase kinase-3β (pSer9-GSK3β) levels were increased in corin(i)-Tg/DCM mice (p < 0.01). In summary, catalytically inactive corin-Tg(i) decreased fluid retention, improved contractile function, decreased HF biomarkers, and diminished cardiac GSK3β activity. Thus, the protective effects of cardiac corin on HF progression and survival in experimental DCM do not require the serine protease activity of the molecule.

Relaxin reverses maladaptive remodeling of the aged heart through Wnt-signaling

Healthy aging results in cardiac structural and electrical remodeling that increases susceptibility to cardiovascular diseases. Relaxin, an insulin-like hormone, suppresses atrial fibrillation, inflammation and fibrosis in aged rats but the mechanisms-of-action are unknown. Here we show that relaxin treatment of aged rats reverses pathological electrical remodeling (increasing Nav1.5 expression and localization of Connexin43 to intercalated disks) by activating canonical Wnt signaling. In isolated adult ventricular myocytes, relaxin upregulated Nav1.5 (EC₅₀ = 1.3 nM) by a mechanism inhibited by the addition of Dickkopf-1. Furthermore, relaxin increased the levels of connexin43, Wnt1, and cytosolic and nuclear β-catenin. Treatment with Wnt1 or CHIR-99021 (a GSK3β inhibitor) mimicked the relaxin effects. In isolated fibroblasts, relaxin blocked TGFβ-induced collagen elevation in a Wnt dependent manner. These findings demonstrate a close interplay between relaxin and Wnt-signaling resulting in myocardial remodeling and reveals a fundamental mechanism of great therapeutic potential.

Overexpression of microRNA‑155 alleviates palmitate‑induced vascular endothelial cell injury in human umbilical vein endothelial cells by negatively regulating the Wnt signaling pathway

The present study aimed to investigate the effect of microRNA155 (miR‑155) on palmitate‑induced vascular endothelial cell injury in human umbilical vein endothelial cells (HUVECs) via the regulation of the Wnt signaling pathway. HUVECs were treated with 0.1 mM palmitate. After transfection with mimic, antagomir or the Wnt pathway inhibitor XAV939, HUVECs were divided into six treatment groups: Control, palmitate, mimic + palmitate, mimic + palmitate + XAV939, antagomir + palmitate, antagomir + palmitate + XAV939. miR‑155 expression was detected using reverse transcription‑quantitative PCR. The expression levels of the Wnt signaling pathway‑related factors β‑catenin and Cyclin D, and the inflammatory factors interleukin‑6 (IL‑6) and tumor necrosis factor‑α (TNF‑α), were detected using western blot analysis. MTT and Transwell assays were used to detect the proliferation and migration of cells, respectively. Apoptosis and reactive oxygen species (ROS) levels were determined using flow cytometry. The localization of β‑catenin in cells was determined by immunofluorescence. Palmitate reduced the expression level of miR‑155 in HUVECs. In palmitate‑induced HUVECs, overexpression of miR‑155 promoted cell proliferation, reduced the levels of apoptosis, downregulated IL‑6 and TNF‑α expression, and reduced ROS levels. Inhibition of the Wnt signaling pathway enhanced the anti‑endothelial cell injury effect caused by the overexpression of miR‑155 in palmitate‑induced HUVECs, thereby promoting proliferation, reducing apoptosis, downregulating the levels of inflammatory factors and reducing ROS levels. In summary, overexpression of miR‑155 inhibited palmitate‑induced apoptosis, ROS production and levels of inflammatory factors, and promoted the proliferation of HUVECs by negatively regulating the Wnt signaling pathway. This present study provides a theoretical basis for the prevention and treatment of cardiovascular diseases associated with endothelial cell injury.

Analysis of potential roles of combinatorial microRNA regulation in occurrence of valvular heart disease with atrial fibrillation based on computational evidences

Background

Atrial fibrillation (AF) is the most common arrhythmia. Patients with valvular heart disease (VHD) frequently have AF. Growing evidence demonstrates that a specifically altered pattern of microRNA (miRNA) expression is related to valvular heart disease with atrial fibrillation (AF-VHD) processes. However, the combinatorial regulation by multiple miRNAs in inducing AF-VHD remains largely unknown.

Methods

The work identified AF-VHD-specific miRNAs and their combinations through mapping miRNA expression profile into differential co-expression network. The expressions of some dysregulated miRNAs were measured by quantitative reverse transcription polymerase chain reaction (qRT-PCR). The regulations of signaling pathways by the combinatorial miRNAs were predicted by enrichment analysis tools.

Results

Thirty-two differentially expressed (DE) miRNAs were identified to be AF-VHD-specific, some of which were new findings. These miRNAs interacted to form 5 combinations. qRT-PCR confirmed the different expression of several identified miRNAs, which illustrated the reliability and biomarker potentials of 32 dysregulation miRNAs. The biological characteristics of combinatorial miRNAs related to AF-VHD were highlighted. Twelve signaling pathways regulated by combinatorial miRNAs were predicted to be possibly associated with AF-VHD.

Conclusions

The AF-VHD-related signaling pathways regulated by combinatorial miRNAs may play an important role in the occurrence of AF-VHD. The work brings new insights into biomarkers and miRNA combination regulation mechanism in AF-VHD as well as further biological experiments.

A context-specific cardiac β-catenin and GATA4 interaction influences TCF7L2 occupancy and remodels chromatin driving disease progression in the adult heart

Chromatin remodelling precedes transcriptional and structural changes in heart failure. A body of work suggests roles for the developmental Wnt signalling pathway in cardiac remodelling. Hitherto, there is no evidence supporting a direct role of Wnt nuclear components in regulating chromatin landscapes in this process. We show that transcriptionally active, nuclear, phosphorylated(p)Ser675-β-catenin and TCF7L2 are upregulated in diseased murine and human cardiac ventricles. We report that inducible cardiomyocytes (CM)-specific pSer675-β-catenin accumulation mimics the disease situation by triggering TCF7L2 expression. This enhances active chromatin, characterized by increased H3K27ac and TCF7L2 occupancies to cardiac developmental and remodelling genes in vivo. Accordingly, transcriptomic analysis of β-catenin stabilized hearts shows a strong recapitulation of cardiac developmental processes like cell cycling and cytoskeletal remodelling. Mechanistically, TCF7L2 co-occupies distal genomic regions with cardiac transcription factors NKX2–5 and GATA4 in stabilized-β-catenin hearts. Validation assays revealed a previously unrecognized function of GATA4 as a cardiac repressor of the TCF7L2/β-catenin complex in vivo, thereby defining a transcriptional switch controlling disease progression. Conversely, preventing β-catenin activation post-pressure-overload results in a downregulation of these novel TCF7L2-targets and rescues cardiac function. Thus, we present a novel role for TCF7L2/β-catenin in CMs-specific chromatin modulation, which could be exploited for manipulating the ubiquitous Wnt pathway.

Dkk1 exacerbates doxorubicin-induced cardiotoxicity by inhibiting the Wnt/β-catenin signaling pathway

The cancer clinical therapy of doxorubicin (Dox) treatment is limited by its life-threatening cardiotoxic effects. Dickkopf-1 (Dkk1), the founding and best-studied member of the Dkk family, functions as an antagonist of canonical Wnt/β-catenin. Dkk1 is considered to play a broad role in a variety of biological processes, but its effects on Dox-induced cardiomyopathy are poorly understood. Here, we found that the level of Dkk1 was significantly increased in Dox-treated groups, and this increase exacerbated Dox-induced cardiomyocyte apoptosis and mitochondrial dysfunction. Overexpressing Dkk1 aggravated Dox-induced cardiotoxicity in H₉C₂ cells. Similar results were detected when adding active Dkk1 protein extracellularly. Conversely, adding specific antibody blocking extracellular Dkk1 attenuated the cardiotoxic response to Dox. Adenovirus encoding Dkk1 was transduced through intramyocardial injection and exacerbated Dox-induced cardiomyocyte apoptosis, mitochondrial damage and heart injury in vivo Furthermore, Wnt/β-catenin signaling was inhibited during Dox-induced cardiotoxicity, and the re-activation of β-catenin prevented the effect of overexpressed Dkk1 and Dox-induced cardiotoxicity. In conclusion, these results reveal the crucial role of the Dkk1-Wnt/β-catenin signaling axis in the process of Dox-induced cardiotoxicity and provide novel insights into the potential mechanism of cardiomyopathy caused by clinical application of Dox.

Cardioprotective actions of relaxin

Relaxin is a hormone of pregnancy first discovered for its ability to induce ligament relaxation in nonpregnant guinea pig and is important for softening of the birth canal during parturition, decidualization, implantation, nipple development and increased maternal renal perfusion, glomerular filtration, and cardiac output. Subsequently, relaxin has been shown to exert multiple beneficial cardiovascular effects during pathological events such as hypertension, atrial fibrillation, heart failure and myocardial infarction, including suppression of arrhythmia and inflammation, and reversal of fibrosis. Despite extensive studies, the mechanisms underlying relaxin's effects are not well understood. Relaxin signals primarily through its G protein coupled receptor, the relaxin family peptide receptor-1, to activate multiple signaling pathways and this review summarizes our understanding of these pathways as they relate to the cardioprotective actions of relaxin, focusing on relaxin's anti-fibrotic, anti-arrhythmic and anti-inflammatory properties. Further, this review includes a brief overview of relaxin in clinical trials for heart failure and progress in the development of relaxin mimetics.

Cardiac endothelial cell transcriptome in neonatal, adult, and remodeling hearts

Cardiac microvascular endothelial cells (CMVECs) are the most numerous cells in the myocardium and orchestrate cardiogenesis during development, regulate adult cardiac function, and modulate pathophysiology of heart failure. It has been shown that the transcriptome of CMVECs differs from other endothelial cell types, but transcriptomic changes in cardiac endothelial cells during cardiac maturation and cardiac remodeling have not been studied. CMVECs were isolated from rat hearts based on CD31 expression and were immediately processed for RNA sequencing. We compared gene expression levels from primary CMVECs of neonatal hearts, normal adult hearts, and infarcted hearts. Between neonatal and adult CMVECs, 6,838 genes were differentially expressed, indicating that CMVECs undergo a substantial transformation during postnatal cardiac growth. A large fraction of genes upregulated in neonatal CMVECs are part of mitosis pathways, whereas a large fraction of genes upregulated in adult CMVECs are part of cellular response, secretory, signaling, and cell adhesion pathways. Between CMVECs of normal adult hearts and infarcted hearts, 159 genes were differentially expressed. We found a limited degree of overlap (55 genes) between the differentially expressed genes in neonatal and infarcted-hearts. Of 46 significantly upregulated genes in the infarcted heart, 46% were also upregulated in neonatal hearts relative to sham. Of 113 significantly downregulated genes in the infarcted-hearts, 30% were also downregulated in neonatal hearts relative to sham. These data demonstrate that CMVECs undergo dramatic changes from neonatal to adult and more subtle changes between normal state and cardiac remodeling.

4-O-Methylhonokiol Influences Normal Cardiovascular Development in Medaka Embryo

Although 4-O-Methylhonokiol (MH) effects on neuronal and immune cells have been established, it is still unclear whether MH can cause a change in the structure and function of the cardiovascular system. The overarching goal of this study was to evaluate the effects of MH, isolated from Magnolia grandiflora, on the development of the heart and vasculature in a Japanese medaka model in vivo to predict human health risks. We analyzed the toxicity of MH in different life-stages of medaka embryos. MH uptake into medaka embryos was quantified. The LC₅₀ of two different exposure windows (stages 9–36 (0–6 days post fertilization (dpf)) and 25–36 (2–6 dpf)) were 5.3 ± 0.1 μM and 9.9 ± 0.2 μM. Survival, deformities, days to hatch, and larval locomotor response were quantified. Wnt 1 was overexpressed in MH-treated embryos indicating deregulation of the Wnt signaling pathway, which was associated with spinal and cardiac ventricle deformities. Overexpression of major proinflammatory mediators and biomarkers of the heart were detected. Our results indicated that the differential sensitivity of MH in the embryos was developmental stage-specific. Furthermore, this study demonstrated that certain molecules can serve as promising markers at the transcriptional and phenotypical levels, responding to absorption of MH in the developing embryo.

βIV-Spectrin regulates STAT3 targeting to tune cardiac response to pressure overload

Heart failure (HF) remains a major source of morbidity and mortality in the US. The multifunctional Ca2+/calmodulin-dependent kinase II (CaMKII) has emerged as a critical regulator of cardiac hypertrophy and failure, although the mechanisms remain unclear. Previous studies have established that the cytoskeletal protein βIV-spectrin coordinates local CaMKII signaling. Here, we sought to determine the role of a spectrin-CaMKII complex in maladaptive remodeling in HF. Chronic pressure overload (6 weeks of transaortic constriction [TAC]) induced a decrease in cardiac function in WT mice but not in animals expressing truncated βIV-spectrin lacking spectrin-CaMKII interaction (qv3J mice). Underlying the observed differences in function was an unexpected differential regulation of STAT3-related genes in qv3J TAC hearts. In vitro experiments demonstrated that βIV-spectrin serves as a target for CaMKII phosphorylation, which regulates its stability. Cardiac-specific βIV-spectrin-KO (βIV-cKO) mice showed STAT3 dysregulation, fibrosis, and decreased cardiac function at baseline, similar to what was observed with TAC in WT mice. STAT3 inhibition restored normal cardiac structure and function in βIV-cKO and WT TAC hearts. Our studies identify a spectrin-based complex essential for regulation of the cardiac response to chronic pressure overload. We anticipate that strategies targeting the new spectrin-based "statosome" will be effective at suppressing maladaptive remodeling in response to chronic stress.

Adult height and risk of 50 diseases: a combined epidemiological and genetic analysis

BACKGROUND

Adult height is associated with risk of several diseases, but the breadth of such associations and whether these associations are primary or due to confounding are unclear. We examined the association of adult height with 50 diseases spanning multiple body systems using both epidemiological and genetic approaches, the latter to identify un-confounded associations and possible underlying mechanisms.

METHODS

We examined the associations for adult height (using logistic regression adjusted for potential confounders) and genetically determined height (using a two-sample Mendelian randomisation approach with height-associated genetic variants as instrumental variables) in 417,434 individuals of white ethnic background participating in the UK Biobank. We undertook pathway analysis of height-associated genes to identify biological processes that could link height and specific diseases.

RESULTS

Height was associated with 32 diseases and genetically determined height associated with 12 diseases. Of these, 11 diseases showed a concordant association in both analyses, with taller height associated with reduced risks of coronary artery disease (odds ratio per standard deviation (SD) increase in height OR_epi = 0.80, 95% CI 0.78-0.81; OR per SD increase in genetically determined height OR_gen = 0.86, 95% CI 0.82-0.90), hypertension (OR_epi = 0.83, 95% CI 0.82-0.84; OR_gen = 0.88, 95% CI 0.85-0.91), gastro-oesophageal reflux disease (OR_epi = 0.85, 95% CI 0.84-0.86; OR_gen = 0.94, 95% CI 0.92-0.97), diaphragmatic hernia (OR_epi = 0.81, 95% CI 0.79-0.82; OR_gen = 0.91, 95% CI 0.88-0.94), but increased risks of atrial fibrillation (OR_epi = 1.42, 95% CI 1.38-1.45; OR_gen = 1.33, 95% CI 1.26-1.40), venous thromboembolism (OR_epi = 1.18, 95% CI 1.16-1.21; OR_gen = 1.15, 95% CI 1.11-1.19), intervertebral disc disorder (OR_epi = 1.15, 95% CI 1.13-1.18; OR_gen = 1.14, 95% CI 1.09-1.20), hip fracture (OR_epi = 1.19, 95% CI 1.12-1.26; OR_gen = 1.27, 95% CI 1.17-1.39), vasculitis (OR_epi = 1.15, 95% CI 1.11-1.19; OR_gen = 1.20, 95% CI 1.14-1.28), cancer overall (OR_epi = 1.09, 95% CI 1.08-1.11; OR_gen = 1.06, 95% CI 1.04-1.08) and breast cancer (OR_epi = 1.08, 95% CI 1.06-1.10; OR_gen = 1.07, 95% CI 1.03-1.11). Pathway analysis showed multiple height-associated pathways associating with individual diseases.

CONCLUSIONS

Adult height is associated with risk of a range of diseases. We confirmed previously reported height associations for coronary artery disease, atrial fibrillation, venous thromboembolism, intervertebral disc disorder, hip fracture and cancer and identified potential novel associations for gastro-oesophageal reflux disease, diaphragmatic hernia and vasculitis. Multiple biological mechanisms affecting height may affect the risks of these diseases.

Regulatory Mechanisms of the Wnt/β-Catenin Pathway in Diabetic Cutaneous Ulcers

Skin ulcers are a serious complication of diabetes. Diabetic patients suffer from vascular lesions and complications such as peripheral neuritis, peripheral vascular lesions, and collagen abnormalities, which result in skin wounds that are refractory and often develop into chronic ulcers. The healing of skin ulcers requires an inflammatory reaction, wound proliferation, remodeling regulation, and control of stem cells. Studies investigating diabetic cutaneous ulcers have focused on cellular and molecular levels. Diabetes can cause nerve and blood vessel damage, and persistent high blood sugar levels can cause systemic multisite nerve damage based on peripheral neuropathy. The long-term hyperglycemia state enables the polyol glucose metabolism pathway to be activated, increasing the accumulation of toxic substances in the vascular injured nerve tissue cells. Sustained hyperglycemia leads to dysfunction of epithelial cells, leading to a decrease in pro-angiogenic signaling and nitric oxide production. In addition, due to impaired leukocyte function in hyperglycemia, immune function is impaired and the immune response at relevant sites is insufficient, making diabetic foot more difficult to heal. The Wnt/β-catenin pathway is a highly conserved signal transduction pathway involved in a variety of biological processes, such as cell proliferation, apoptosis, and differentiation. It is considered an important pathway involved in the healing of skin wounds. This article summarizes the mechanism of action of the Wnt/β-catenin pathway involved in the inflammatory responses to diabetic ulcers, wound proliferation, wound remodeling, and stem cells. The interactions between the Wnt signal pathway and other metabolic pathways are also discussed.

The role of Wnt signaling in the healing myocardium: a focus on cell specificity

Various cell types are involved in the healing process after myocardial infarction (MI). Besides cardiac resident cells (such as cardiomyocytes, fibroblasts and endothelial cells) already present at the lesion site, a massive influx of leukocytes (mainly monocytes and neutrophils) is observed within hours after the ischemic event. So far, little is known about modes of interaction of these cells. Wnt signaling is an evolutionary conserved signaling cassette known to play an important role in cell-cell communication. While the overall reactivation of Wnt signaling upon ischemic injury is well described, the precise expression pattern of Wnt proteins, however, is far from understood. We here describe known Wnt components that partake in MI healing and differentiate cell-specific aspects. The secretion of Wnt proteins and their antagonists in the context of cardiac inflammation after MI appear to be tightly regulated in a spatial-temporal manner. Overall, we aim to stress the importance of elucidating not only Wnt component-specific aspects, but also their sometimes contradicting effects in different target cells. A better understanding of Wnt signaling in MI healing may eventually lead to the development of successful therapeutic approaches in an often considered "un-druggable" pathway.

Fluoxetine Inhibits Canonical Wnt Signaling to Impair Embryoid Body Morphogenesis: Potential Teratogenic Mechanisms of a Commonly Used Antidepressant

Fluoxetine is one of the most commonly prescribed antidepressants in the selective serotonin reuptake inhibitor (SSRI) class. Epidemiologic studies have suggested a link between maternal fluoxetine use during pregnancy and an increased incidence of birth defects. However, the mechanisms by which fluoxetine adversely impacts embryonic developments are unknown. Here, we used the mouse P19C5 embryoid body (EB) as a 3D morphogenesis model to investigate the developmental toxicity of fluoxetine. Morphological and molecular changes in P19C5 EBs replicate the processes of axial elongation and patterning seen in early embryos, and these changes are specifically and sensitively altered by exposure to developmental toxicants. Treatment with fluoxetine, or its major metabolite, norfluoxetine, adversely affected EB morphogenesis at concentrations of 6 µM and above. Treatment with other serotonin reuptake inhibitors or serotonin itself did not impair EB morphogenesis, suggesting that the adverse effects of fluoxetine are independent of serotonin signaling. Gene expression analyses showed that various key developmental regulators were affected by fluoxetine, particularly those involved in mesodermal differentiation. Reporter assays demonstrated that fluoxetine inhibited canonical Wnt signaling, and that the pharmacologic activation of canonical Wnt signaling partially alleviated the morphogenetic effects of fluoxetine. Fluoxetine also exhibited cytostatic effects independently of inhibition of the serotonin transporter or canonical Wnt signaling. These results suggest that the SSRI-independent actions of fluoxetine, namely inhibition of canonical Wnt signaling and reduction of cellular proliferation, are largely responsible for the observed adverse morphogenetic impacts. This study provides mechanistic insight for further investigations on the teratogenicity of fluoxetine.

Differential Wnt-mediated programming and arrhythmogenesis in right versus left ventricles

Several inherited arrhythmias, including Brugada syndrome and arrhythmogenic cardiomyopathy, primarily affect the right ventricle and can lead to sudden cardiac death. Among many differences, right and left ventricular cardiomyocytes derive from distinct progenitors, prompting us to investigate how embryonic programming may contribute to chamber-specific conduction and arrhythmia susceptibility. Here, we show that developmental perturbation of Wnt signaling leads to chamber-specific transcriptional regulation of genes important in cardiac conduction that persists into adulthood. Transcriptional profiling of right versus left ventricles in mice deficient in Wnt transcriptional activity reveals global chamber differences, including genes regulating cardiac electrophysiology such as Gja1 and Scn5a. In addition, the transcriptional repressor Hey2, a gene associated with Brugada syndrome, is a direct target of Wnt signaling in the right ventricle only. These transcriptional changes lead to perturbed right ventricular cardiac conduction and cellular excitability. Ex vivo and in vivo stimulation of the right ventricle is sufficient to induce ventricular tachycardia in Wnt transcriptionally inactive hearts, while left ventricular stimulation has no effect. These data show that embryonic perturbation of Wnt signaling in cardiomyocytes leads to right ventricular arrhythmia susceptibility in the adult heart through chamber-specific regulation of genes regulating cellular electrophysiology.

A novel porcupine inhibitor blocks WNT pathways and attenuates cardiac hypertrophy

WNT pathways are critically involved in the cardiac hypertrophy growth. Porcupine, an acyltransferase that specifically enables secretion of all WNT ligands, became a highly druggable target for inhibiting WNT pathways. Here we test if a novel small-molecule porcupine inhibitor CGX1321, which has entered human clinical trials as an anti-cancer agent, exerts an anti-hypertrophic effect. Transverse aortic constriction (TAC) was performed to induce cardiac hypertrophy on four-month-old male C57 mice. Cardiac function was measured with echocardiography. Histological analysis was performed to detect cardiomyocyte size and molecular expressions. CGX1321 was administrated daily for 4 weeks post TAC injury. As a result, CGX1321 improved cardiac function and animal survival of post-TAC mice. CGX1321 significantly reduced cardiomyocyte hypertrophy, cardiomyocyte apoptosis and fibrosis induced by TAC injury. CGX1321 significantly inhibited TAC induced nuclear translocation of β-catenin and the elevation of Frizzled-2, cyclin-D1 and c-myc expression, indicating its inhibitory effect on canonical WNT pathway. Furthermore, CGX1321 inhibited TAC induced nuclear translocation of nuclear factor of activated T-cells and the elevation of phosphorylated c-Jun expression, suggesting its inhibitory function on non-canonical WNT pathway. We conclude that CGX1321 inhibits both canonical and non-canonical WNT pathways, and attenuates cardiac hypertrophy. Our findings support the porcupine inhibitors as a class of new drugs to be potentially used for treating patients with cardiac hypertrophy.

Long Non-Coding RNAs in Multifactorial Diseases: Another Layer of Complexity

Multifactorial diseases such as cancer, cardiovascular conditions and neurological, immunological and metabolic disorders are a group of diseases caused by the combination of genetic and environmental factors. High-throughput RNA sequencing (RNA-seq) technologies have revealed that less than 2% of the genome corresponds to protein-coding genes, although most of the human genome is transcribed. The other transcripts include a large variety of non-coding RNAs (ncRNAs), and the continuous generation of RNA-seq data shows that ncRNAs are strongly deregulated and may be important players in pathological processes. A specific class of ncRNAs, the long non-coding RNAs (lncRNAs), has been intensively studied in human diseases. For clinical purposes, lncRNAs may have advantages mainly because of their specificity and differential expression patterns, as well as their ideal qualities for diagnosis and therapeutics. Multifactorial diseases are the major cause of death worldwide and many aspects of their development are not fully understood. Recent data about lncRNAs has improved our knowledge and helped risk assessment and prognosis of these pathologies. This review summarizes the involvement of some lncRNAs in the most common multifactorial diseases, with a focus on those with published functional data.

Cardiac Remodeling: Endothelial Cells Have More to Say Than Just NO

The heart is a highly structured organ consisting of different cell types, including myocytes, endothelial cells, fibroblasts, stem cells, and inflammatory cells. This pluricellularity provides the opportunity of intercellular communication within the organ, with subsequent optimization of its function. Intercellular cross-talk is indispensable during cardiac development, but also plays a substantial modulatory role in the normal and failing heart of adults. More specifically, factors secreted by cardiac microvascular endothelial cells modulate cardiac performance and either positively or negatively affect cardiac remodeling. The role of endothelium-derived small molecules and peptides—for instance NO or endothelin-1—has been extensively studied and is relatively well defined. However, endothelial cells also secrete numerous larger proteins. Information on the role of these proteins in the heart is scattered throughout the literature. In this review, we will link specific proteins that modulate cardiac contractility or cardiac remodeling to their expression by cardiac microvascular endothelial cells. The following proteins will be discussed: IL-6, periostin, tenascin-C, thrombospondin, follistatin-like 1, frizzled-related protein 3, IGF-1, CTGF, dickkopf-3, BMP-2 and−4, apelin, IL-1β, placental growth factor, LIF, WISP-1, midkine, and adrenomedullin. In the future, it is likely that some of these proteins can serve as markers of cardiac remodeling and that the concept of endothelial function and dysfunction might have to be redefined as we learn more about other factors secreted by ECs besides NO.

The Mingle-Mangle of Wnt Signaling and Extracellular Vesicles: Functional Implications for Heart Research

Wnt signaling is an important pathway in health and disease and a key regulator of stem cell maintenance, differentiation, and proliferation. During heart development, Wnt signaling controls specification, proliferation and differentiation of cardiovascular cells. In this regard, the role of activated Wnt signaling in cardiogenesis is well defined. However, the knowledge about signaling transmission has been challenged. Recently, the packaging of hydrophobic Wnt proteins on extracellular vesicles (EVs) has emerged as a mechanism to facilitate their extracellular spreading and their functioning as morphogens. EVs spread systemically and therefore can have pleiotropic effects on very different cell types. They are heavily studied in tumor biology where they affect tumor growth and vascularization and can serve as biomarkers in liquid biopsies. In this review we will highlight recent discoveries of factors involved in the release of Wnts on EVs and its potential implications in the communication between physiological and pathological heart cells.

Heart Failure as an Aging-Related Phenotype

The molecular pathophysiology of heart failure, which is one of the leading causes of mortality, is not yet fully understood. Heart failure can be regarded as a systemic syndrome of aging-related phenotypes. Wnt/β-catenin signaling and the p53 pathway, both of which are key regulators of aging, have been demonstrated to play a critical role in the pathogenesis of heart failure. Circulating C1q was identified as a novel activator of Wnt/β-catenin signaling, promoting systemic aging-related phenotypes including sarcopenia and heart failure. On the other hand, p53 induces the apoptosis of cardiomyocytes in the failing heart. In these molecular mechanisms, the cross-talk between cardiomyocytes and non-cardiomyocytes (e,g,. endothelial cells, fibroblasts, smooth muscle cells, macrophages) deserves mentioning. In this review, we summarize recent advances in the understanding of the molecular pathophysiology underlying heart failure, focusing on Wnt/β-catenin signaling and the p53 pathway.

WNT Signaling in Cardiac and Vascular Disease

WNT signaling is an elaborate and complex collection of signal transduction pathways mediated by multiple signaling molecules. WNT signaling is critically important for developmental processes, including cell proliferation, differentiation and tissue patterning. Little WNT signaling activity is present in the cardiovascular system of healthy adults, but reactivation of the pathway is observed in many pathologies of heart and blood vessels. The high prevalence of these pathologies and their significant contribution to human disease burden has raised interest in WNT signaling as a potential target for therapeutic intervention. In this review, we first will focus on the constituents of the pathway and their regulation and the different signaling routes. Subsequently, the role of WNT signaling in cardiovascular development is addressed, followed by a detailed discussion of its involvement in vascular and cardiac disease. After highlighting the crosstalk between WNT, transforming growth factor-β and angiotensin II signaling, and the emerging role of WNT signaling in the regulation of stem cells, we provide an overview of drugs targeting the pathway at different levels. From the combined studies we conclude that, despite the sometimes conflicting experimental data, a general picture is emerging that excessive stimulation of WNT signaling adversely affects cardiovascular pathology. The rapidly increasing collection of drugs interfering at different levels of WNT signaling will allow the evaluation of therapeutic interventions in the pathway in relevant animal models of cardiovascular diseases and eventually in patients in the near future, translating the outcomes of the many preclinical studies into a clinically relevant context.

Cardiac myocyte miR-29 promotes pathological remodeling of the heart by activating Wnt signaling

Chronic cardiac stress induces pathologic hypertrophy and fibrosis of the myocardium. The microRNA-29 (miR-29) family has been found to prevent excess collagen expression in various organs, particularly through its function in fibroblasts. Here, we show that miR-29 promotes pathologic hypertrophy of cardiac myocytes and overall cardiac dysfunction. In a mouse model of cardiac pressure overload, global genetic deletion of miR-29 or antimiR-29 infusion prevents cardiac hypertrophy and fibrosis and improves cardiac function. Targeted deletion of miR-29 in cardiac myocytes in vivo also prevents cardiac hypertrophy and fibrosis, indicating that the function of miR-29 in cardiac myocytes dominates over that in non-myocyte cell types. Mechanistically, we found cardiac myocyte miR-29 to de-repress Wnt signaling by directly targeting four pathway factors. Our data suggests that, cell- or tissue-specific antimiR-29 delivery may have therapeutic value for pathological cardiac remodeling and fibrosis.

MicroRNA-29 is known to reduce collagen production in fibroblasts thereby inhibiting fibrosis in various organs. Here, Sassi et al. show that miR-29 can also enhance fibrotic signalling and pathological hypertrophy of the heart through its action in cardiomyocytes.

Decoy Wnt receptor (sLRP6E1E2)-expressing adenovirus induces anti-fibrotic effect via inhibition of Wnt and TGF-β signaling

Aberrant activation of the canonical Wingless type (Wnt) signaling pathway plays a key role in the development of hypertrophic scars and keloids, and this aberrant activation of Wnt pathway can be a potential target for the development of novel anti-fibrotic agents. In this study, we evaluated the anti-fibrotic potential of a soluble Wnt decoy receptor (sLRP6E1E2)-expressing non-replicating adenovirus (Ad; dE1-k35/sLRP6E1E2) on human dermal fibroblasts (HDFs), keloid fibroblasts (KFs), and keloid tissue explants. Higher Wnt3a and β-catenin expression was observed in the keloid region compared to the adjacent normal tissues. The activity of β-catenin and mRNA expression of type-I and -III collagen were significantly decreased following treatment with dE1-k35/sLRP6E1E2 in HDFs and KFs. The expression of LRP6, β-catenin, phosphorylated glycogen synthase kinase 3 beta, Smad 2/3 complex, and TGF-β1 were decreased in Wnt3a- or TGF-β1-activated HDFs, following administration of dE1-k35/sLRP6E1E2. Moreover, dE1-k35/sLRP6E1E2 markedly inhibited nuclear translocation of both β-catenin and Smad 2/3 complex. The expression levels of type-I and -III collagen, fibronectin, and elastin were also significantly reduced in keloid tissue explants after treatment with dE1-k35/sLRP6E1E2. These results indicate that Wnt decoy receptor-expressing Ad can degrade extracellular matrix in HDFs, KFs, and primary keloid tissue explants, and thus it may be beneficial for treatment of keloids.

Defective Wnt3 expression by testicular Sertoli cells compromise male fertility

Testicular Sertoli cells make a niche for the division and differentiation of germ cells. Sertoli cells respond to increased follicle-stimulating hormone (FSH) and testosterone (T) levels at the onset of puberty by producing paracrine factors which affect germ cells and trigger robust onset of spermatogenesis. Such paracrine support to germ cells is absent during infancy, despite Sertoli cells being exposed to high FSH and T within the infant testis. This situation is similar to certain cases of male idiopathic infertility where post-pubertal Sertoli cells fail to support germ cell division and differentiation in spite of endogenous or exogenous hormonal support. Defective Sertoli cells in such individuals may fail to express the full complement of their paracrine repertoire. Identification and supplementation with such factors may overcome Sertoli cells deficiencies and help trigger quantitatively and qualitatively normal differentiation of germ cells. To this end, we compared the transcriptome of FSH- and T-treated infant and pubertal monkey Sertoli cells by DNA microarray. Expression of Wnt3, a morphogen of the Wnt/β-catenin pathway, was higher in pubertal Sertoli cells relative to infant Sertoli cells. Transgenic mice were generated by us in which Wnt3 expression was curtailed specifically in post-pubertal Sertoli cells by shRNA. Subfertility and oligozoospermia were noticed in such animals with low Wnt3 expression in post-pubertal Sertoli cells along with diminished expression of Connexin43, a gap-junctional molecule essential for germ cell development. We report that the FSH- and T-targetedf Wnt3 governs Sertoli cell-mediated regulation of spermatogenesis and hence is crucial for fertility.

Wnt5a is associated with right ventricular dysfunction and adverse outcome in dilated cardiomyopathy

The Wingless (Wnt) pathway has been implicated in the pathogenesis of dilated cardiomyopathy (DCM). To explore the role of Wnt modulators Wnt5a and sFRP3 in DCM patients we analyzed the expression of Wnt5a and sFRP3 in plasma and myocardium of DCM patients and evaluated their effects on NFAT luciferase activity in neonatal mouse cardiomyocytes. Elevated circulating Wnt5a (n = 102) was associated with increased pulmonary artery pressures, decreased right ventricular function and adverse outcome, with a stronger association in more severely affected patients. A higher Wnt5a/sFRP3 ratio (n = 25) was found in the right ventricle vs. the left ventricle and was correlated with NFAT activation as well as pulmonary artery pressures. Wnt5a induced NFAT activation and sFRP3 release in cardiomyocytes in vitro, while sFRP3 antagonized Wnt5a. Wnt5a is associated with right ventricular dysfunction and adverse outcome in DCM patients and may promote the progression of DCM through NFAT signaling.

Wnt/β-catenin pathway in arrhythmogenic cardiomyopathy

Wnt/β-catenin signaling pathway plays essential roles in heart development as well as cardiac tissue homoeostasis in adults. Abnormal regulation of this signaling pathway is linked to a variety of cardiac disease conditions, including hypertrophy, fibrosis, arrhythmias, and infarction. Recent studies on genetically modified cellular and animal models document a crucial role of Wnt/β-catenin signaling in the molecular pathogenesis of arrhythmogenic cardiomyopathy (AC), an inherited disease of intercalated discs, typically characterized by ventricular arrhythmias and progressive substitution of the myocardium with fibrofatty tissue. In this review, we summarize the conflicting published data regarding the Wnt/β-catenin signaling contribution to AC pathogenesis and we report the identification of a new potential therapeutic molecule that prevents myocyte injury and cardiac dysfunction due to desmosome mutations in vitro and in vivo by interfering in this signaling pathway. Finally, we underline the potential function of microRNAs, epigenetic regulatory RNA factors reported to participate in several pathological responses in heart tissue and in the Wnt signaling network, as important modulators of Wnt/β-catenin signaling transduction in AC.

Elucidation of the precise regulatory mechanism of Wnt/β-catenin signaling in AC molecular pathogenesis could provide fundamental insights for new mechanism-based therapeutic strategy to delay the onset or progression of this cardiac disease.

1,25-Dihydroxyvitamin-D3 prevents the development of diabetic cardiomyopathy in type 1 diabetic rats by enhancing autophagy via inhibiting the β-catenin/TCF4/GSK-3β/mTOR pathway

Diabetic cardiomyopathy (DCM) can increase the risk of heart failure and death in diabetic patients. However, no effective approaches are available to prevent its progression and development. Studies have shown that vitamin D is greatly implicated in cardiac hypertrophy and fibrosis, and there is a high prevalence of vitamin D deficiency in diabetic patients. In this study, we investigated whether 1,25-Dihydroxyvitamin-D3 (1,25D3) can improve DCM through a vitamin D receptor (VDR)-dependent mechanism associated with autophagy and the β-catenin/T-cell factor/lymphoid enhancer factor (TCF4)/glycogen synthase kinase-3β (GSK-3β)/mammalian target of rapamycin (mTOR) pathway. In this study, streptozotocin (STZ)-induced type 1 diabetic rats were established and were treated with 1,25D3 and/or chloroquine and/or VDR gene silencing for 8 weeks before being sacrificed. Compared with untreated diabetic rats, 1,25D3 partly attenuated the myocardial hypertrophy and interstitial fibrosis, improved cardiac function and restored the impaired cardiac autophagy in diabetic rats, all of which were reversed by silencing the VDR gene in diabetic rats. In high-glucose cultured H9C2 cells, 1,25D3 increased autophagy in a dose-dependent manner. Besides, the β-catenin/TCF4/GSK-3β and mTOR signaling were activated both in diabetic rats and in high-glucose cultured H9C2 cells. Treatment with 1,25D3 inhibited the β-catenin/TCF4/GSK-3β and mTOR signaling in H9C2 cells, whereas co-treatment with lithium chloride (LiCl) reversed this situation and abolished the beneficial effect of 1,25D3 on autophagy. These data suggest that 1,25D3 may improve DCM in type 1 diabetic rats by modulating autophagy through the β-catenin/TCF4/GSK-3β and mTOR pathway. Vitamin D may exist as a new therapeutic target for the treatment of DCM.

Wnt5a is elevated in heart failure and affects cardiac fibroblast function

Wnt signaling is dysregulated in heart failure (HF) and may promote cardiac hypertrophy, fibrosis, and inflammation. Blocking the Wnt ligand Wnt5a prevents HF in animal models. However, the role of Wnt5a in human HF and its functions in cardiac cells remain unclear. Here, we investigated Wnt5a regulation in HF patients and its effects on primary mouse and human cardiac fibroblasts. Serum Wnt5a was elevated in HF patients and associated with hemodynamic, neurohormonal, and clinical measures of disease severity. In failing human hearts, Wnt5a protein correlated with interleukin (IL)-6 and tissue inhibitor of metalloproteinase (TIMP)-1. Wnt5a messenger RNA (mRNA) levels were markedly upregulated in failing myocardium and both mRNA and protein levels declined following left ventricular assist device therapy. In primary mouse and human cardiac fibroblasts, recombinant Wnt5a dose-dependently upregulated mRNA and protein release of IL-6 and TIMP-1. Wnt5a did not affect β-catenin levels, but activated extracellular signal-regulated kinase 1/2 (ERK1/2) signaling. Importantly, inhibition of ERK1/2 activation attenuated Wnt5a-induced release of IL-6 and TIMP-1. In conclusion, our results show that Wnt5a is elevated in the serum and myocardium of HF patients and is associated with measures of progressive HF. Wnt5a induces IL-6 and TIMP-1 in cardiac fibroblasts, which might promote myocardial inflammation and fibrosis, and thereby contribute to HF progression.

KEY MESSAGES

• Wnt5a is elevated in serum and myocardium of HF patients and is associated with measures of progressive HF. • In cardiac fibroblasts, Wnt5a upregulates interleukin (IL)-6 and tissue inhibitor of metalloproteinase (TIMP)-1 through the ERK pathway. • Wnt5a-mediated effects might promote myocardial inflammation and fibrosis, and thereby contribute to HF progression.

Pigment epithelium-derived factor alleviates endothelial injury by inhibiting Wnt/β-catenin pathway

Background

Oxidized low-density lipoprotein (ox-LDL) can induce endothelial injury and plays a vital role in the procession and development of atherosclerosis. Little is known regarding whether Wnt/β-catenin pathway is involved in ox-LDL-induced endothelial injury or whether it further promotes atherosclerosis via increased oxidative stress. This study aimed to investigate the role of Wnt/β-catenin pathway in ox-LDL-induced vascular endothelial injury and determine whether pigment epithelium-derived factor (PEDF) could alleviate ox-LDL-induced endothelial injury by inhibiting Wnt/β-catenin pathway.

Methods

Injury of human umbilical vein endothelial cells (HUVECs) was evaluated with an MTT assay, by monitoring lactate dehydrogenase (LDH) release and determining the apoptotic ratio. The expression of β-catenin (non-phosphorylated-β-catenin), disheveled-1 (Dvl-1) and Cyclin D1 was analyzed with western blotting and quantitative real-time PCR. Oxidative stress status was assessed by measuring the levels of reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD) and nitric oxide (NO).

Results

Exposure of HUVECs to ox-LDL led to a decrease in cell viability and an increase in LDH release and apoptosis with concomitant enhancement of oxidative stress, as assessed by increased ROS and MDA generation, as well as decreased SOD activity and NO levels. Similar to lithium chloride (LiCl, a Wnt/β-catenin pathway activator), ox-LDL up-regulated the expression of β-catenin, Dvl-1 and Cyclin D1, markers of Wnt/β-catenin pathway activation. However, ox-LDL-induced activation of Wnt/β-catenin pathway, as well as ox-LDL-induced cell injury and oxidative stress, were synergistically promoted by LiCl and mitigated by Dickkopf 1 (DKK-1), an inhibitor of Wnt/β-catenin pathway. Additionally, ox-LDL-induced HUVEC injury and apoptosis, oxidative stress and activation of Wnt/β-catenin pathway were suppressed by PEDF, while they were further strengthened by a small interfering RNA of PEDF.

Conclusion

Wnt/β-catenin pathway may mediate ox-LDL-induced endothelial injury via oxidative stress, and PEDF ameliorates endothelial injury by suppressing Wnt/β-catenin pathway and subsequently reducing oxidative stress.

Electronic supplementary material

The online version of this article (doi:10.1186/s12944-017-0407-8) contains supplementary material, which is available to authorized users.

Cdon deficiency causes cardiac remodeling through hyperactivation of WNT/β-catenin signaling

On pathological stress, Wnt signaling is reactivated and induces genes associated with cardiac remodeling and fibrosis. We have previously shown that a cell surface receptor Cdon (cell-adhesion associated, oncogene regulated) suppresses Wnt signaling to promote neuronal differentiation however its role in heart is unknown. Here, we demonstrate a critical role of Cdon in cardiac function and remodeling. Cdon is expressed and predominantly localized at intercalated disk in both mouse and human hearts. Cdon-deficient mice develop cardiac dysfunction including reduced ejection fraction and ECG abnormalities. Cdon^-/- hearts exhibit increased fibrosis and up-regulation of genes associated with cardiac remodeling and fibrosis. Electrical remodeling was demonstrated by up-regulation and mislocalization of the gap junction protein, Connexin 43 (Cx43) in Cdon^-/- hearts. In agreement with altered Cx43 expression, functional analysis both using Cdon^-/- cardiomyocytes and shRNA-mediated knockdown in rat cardiomyocytes shows aberrant gap junction activities. Analysis of the underlying mechanism reveals that Cdon^-/- hearts exhibit hyperactive Wnt signaling as evident by β-catenin accumulation and Axin2 up-regulation. On the other hand, the treatment of rat cardiomyocytes with a Wnt activator TWS119 reduces Cdon levels and aberrant Cx43 activities, similarly to Cdon-deficient cardiomyocytes, suggesting a negative feedback between Cdon and Wnt signaling. Finally, inhibition of Wnt/β-catenin signaling by XAV939, IWP2 or dickkopf (DKK)1 prevented Cdon depletion-induced up-regulation of collagen 1a and Cx43. Taken together, these results demonstrate that Cdon deficiency causes hyperactive Wnt signaling leading to aberrant intercellular coupling and cardiac fibrosis. Cdon exhibits great potential as a target for the treatment of cardiac fibrosis and cardiomyopathy.

Role of Noncanonical Wnt Signaling Pathway in Human Aortic Valve Calcification

OBJECTIVE

The mechanisms underlying the pathogenesis of aortic valve calcification remain unclear. With accumulating evidence demonstrating that valve calcification recapitulates bone development, the crucial roles of noncanonical Wnt ligands WNT5a, WNT5b, and WNT11 in osteogenesis make them critical targets in the study of aortic valve calcification.

APPROACH AND RESULTS

Using immunohistochemistry, real-time qPCR, Western blotting, and tissue culture, we examined the tissue distribution of WNT5a, WNT5b, and WNT11 in noncalcified and calcified aortic valves and their effects on human aortic valve interstitial cells (HAVICs). Only focal strong immunostaining for WNT5a was seen in and around areas of calcification. Abundant immunostaining for WNT5b and WNT11 was seen in inflammatory cells, fibrosis, and activated myofibroblasts in areas of calcified foci. There was significant correlation between WNT5b and WNT11 overall staining and presence of calcification, lipid score, fibrosis, and microvessels (P<0.05). Real-time qPCR and Western blotting revealed abundant expression of both Wnts in stenotic aortic valves, particularly in bicuspid valves. Incubation of HAVICs from noncalcified valves with the 3 noncanonical Wnts significantly increased cell apoptosis and calcification (P<0.05). Treatment of HAVICs with the mitogen-activated protein kinase-38β and GSK3β inhibitors significantly reduced their mineralization (P<0.01). Raman spectroscopy identified the inorganic phosphate deposits as hydroxyapatite and showed a significant increase in hydroxyapatite deposition in HAVICs in response to WNT5a and WNT11 (P<0.05). Similar crystallinity was seen in the deposits found in HAVICs treated with Wnts and in calcified human aortic valves.

CONCLUSIONS

These findings suggest a potential role for noncanonical Wnt signaling in the pathogenesis of aortic valve calcification.

Role of Wnt/β-catenin, Wnt/c-Jun N-terminal kinase and Wnt/Ca2+ pathways in cisplatin-induced chemoresistance in ovarian cancer

The aim of the present study was to explore the expression of Wnt signaling proteins β-catenin, c-Jun N-terminal kinase (JNK) and Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) in ovarian cancer cells, and assess the correlation between this expression and cisplatin-induced chemoresistance. SKOV3 ovarian carcinoma cells and SKOV3/DDP (cisplatin resistant) cells were treated with cisplatin in the absence or presence of a Wnt signaling activator (CHIR-99021, glycogen synthase kinase 3β inhibitor) or inhibitor (XAV-939, tankyrase inhibitor). Following incubation for 48 h, cell viability, proliferation and cytotoxicity were measured using a sensitive colorimetric cell counting kit. Expression levels of β-catenin, JNK and CaMKII were detected by western blot and immunofluorescence staining. The results of the current study identified that β-catenin and JNK expression levels were significantly higher (P<0.01 and P<0.05 respectively), while CaMKII expression was lower (P>0.05), in SKOV3/DDP cells compared with SKOV3 cells. Moreover, following treatment with 20 µM cisplatin, reduced expression of β-catenin and JNK (P<0.05 and P<0.01 respectively), and increased expression of CaMKII (P<0.01), was observed in SKOV3 and SKOV3/DPP cell lines. Furthermore, inhibition of β-catenin signaling by XAV-939 effectively reversed cisplatin chemoresistance in SKOV3/DDP cells. Similarly, XAV-939 downregulated JNK expression (P<0.001), but upregulated CaMKII expression (P<0.001), in SKOV3/DDP cells. In conclusion, abnormal activation of Wnt/β-catenin and Wnt/JNK signaling pathways in ovarian cancer cells promotes cisplatin resistance, while the Wnt/Ca²⁺ signaling pathway reduces cisplatin resistance. This indicates that β-catenin, JNK and CaMKII are potential therapeutic targets in chemoresistant ovarian cancers.

Global phosphoproteomic profiling reveals perturbed signaling in a mouse model of dilated cardiomyopathy

Phospholamban (PLN) plays a central role in Ca²⁺ homeostasis in cardiac myocytes through regulation of the sarco(endo)plasmic reticulum Ca²⁺-ATPase 2A (SERCA2A) Ca²⁺ pump. An inherited mutation converting arginine residue 9 in PLN to cysteine (R9C) results in dilated cardiomyopathy (DCM) in humans and transgenic mice, but the downstream signaling defects leading to decompensation and heart failure are poorly understood. Here we used precision mass spectrometry to study the global phosphorylation dynamics of 1,887 cardiac phosphoproteins in early affected heart tissue in a transgenic R9C mouse model of DCM compared with wild-type littermates. Dysregulated phosphorylation sites were quantified after affinity capture and identification of 3,908 phosphopeptides from fractionated whole-heart homogenates. Global statistical enrichment analysis of the differential phosphoprotein patterns revealed selective perturbation of signaling pathways regulating cardiovascular activity in early stages of DCM. Strikingly, dysregulated signaling through the Notch-1 receptor, recently linked to cardiomyogenesis and embryonic cardiac stem cell development and differentiation but never directly implicated in DCM before, was a prominently perturbed pathway. We verified alterations in Notch-1 downstream components in early symptomatic R9C transgenic mouse cardiomyocytes compared with wild type by immunoblot analysis and confocal immunofluorescence microscopy. These data reveal unexpected connections between stress-regulated cell signaling networks, specific protein kinases, and downstream effectors essential for proper cardiac function.

Magnetic resonance imaging of infarct-induced canonical wingless/integrated (Wnt)/β-catenin/T-cell factor pathway activation, in vivo

AIMS

Combined magnetic resonance imaging (MRI) of molecular and morpho-functional changes might prove highly valuable for the elucidation of pathological processes involved in the development of cardiac diseases. Our aim was to test a novel MRI reporter gene for in vivo assessment of the canonical Wnt/β-catenin/TCF pathway activation, an important regulator of post-ischaemic cardiac remodelling.

METHODS AND RESULTS

We designed and developed a chimeric construct encoding for both of iron-binding human ferritin heavy chain (hFTH) controlled by the β-catenin-responsive TCF/lymphoid-enhancer binding factor (Lef) promoter and constitutively expressed green fluorescent protein (GFP). It was carried by adeno-associated virus serotype 9 (rAAV9) vectors and delivered to the peri-infarct myocardium of rats subjected to coronary ligation (n = 11). By 1.5 T MRI and a multiecho T2* gradient echo sequence, we detected iron accumulation only in the border zone of the transduced infarcted hearts. In the same cardiac area, post-mortem histological analysis confirmed the co-existence of iron accumulation and GFP. The iron signal was absent when rats (n = 6) were chronically treated with SEN195 (10 mg/kg/day), a small-molecular inhibitor of β-catenin/TCF-dependent gene transcription. Canonical Wnt pathway inhibition attenuated the post-ischaemic remodelling process, as demonstrated by the significant preservation of cardiac function, the 42 ± 1% increase of peri-infarct arteriolar density and 43 ± 3% reduction in infarct scar size compared with untreated animals.

CONCLUSIONS

The TCF/Lef promoter-hFTH construct is a novel and reliable MRI reporter gene for in vivo detection of the canonical Wnt/β-catenin/TCF activation state in response to cardiac injury and therapeutic interventions.

Molecular profiling of dilated cardiomyopathy that progresses to heart failure

Dilated cardiomyopathy (DCM) is defined by progressive functional and structural changes. We performed RNA-seq at different stages of disease to define molecular signaling in the progression from pre-DCM hearts to DCM and overt heart failure (HF) using a genetic model of DCM (phospholamban missense mutation, PLN^R9C/+). Pre-DCM hearts were phenotypically normal yet displayed proliferation of nonmyocytes (59% relative increase vs. WT, P = 8 × 10^-4) and activation of proinflammatory signaling with notable cardiomyocyte-specific induction of a subset of profibrotic cytokines including TGFβ2 and TGFβ3. These changes progressed through DCM and HF, resulting in substantial fibrosis (17.6% of left ventricle [LV] vs. WT, P = 6 × 10^-33). Cardiomyocytes displayed a marked shift in metabolic gene transcription: downregulation of aerobic respiration and subsequent upregulation of glucose utilization, changes coincident with attenuated expression of PPARα and PPARγ coactivators -1α (PGC1α) and -1β, and increased expression of the metabolic regulator T-box transcription factor 15 (Tbx15). Comparing DCM transcriptional profiles with those in hypertrophic cardiomyopathy (HCM) revealed similar and distinct molecular mechanisms. Our data suggest that cardiomyocyte-specific cytokine expression, early fibroblast activation, and the shift in metabolic gene expression are hallmarks of cardiomyopathy progression. Notably, key components of these profibrotic and metabolic networks were disease specific and distinguish DCM from HCM.

Activation of endothelial β-catenin signaling induces heart failure

Activation of β-catenin-dependent canonical Wnt signaling in endothelial cells plays a key role in angiogenesis during development and ischemic diseases, however, other roles of Wnt/β-catenin signaling in endothelial cells remain poorly understood. Here, we report that sustained activation of β-catenin signaling in endothelial cells causes cardiac dysfunction through suppressing neuregulin-ErbB pathway in the heart. Conditional gain-of-function mutation of β-catenin, which activates Wnt/β-catenin signaling in Bmx-positive arterial endothelial cells (Bmx/CA mice) led to progressive cardiac dysfunction and 100% mortality at 40 weeks after tamoxifen treatment. Electron microscopic analysis revealed dilatation of T-tubules and degeneration of mitochondria in cardiomyocytes of Bmx/CA mice, which are similar to the changes observed in mice with decreased neuregulin-ErbB signaling. Endothelial expression of Nrg1 and cardiac ErbB signaling were suppressed in Bmx/CA mice. The cardiac dysfunction of Bmx/CA mice was ameliorated by administration of recombinant neuregulin protein. These results collectively suggest that sustained activation of Wnt/β-catenin signaling in endothelial cells might be a cause of heart failure through suppressing neuregulin-ErbB signaling, and that the Wnt/β-catenin/NRG axis in cardiac endothelial cells might become a therapeutic target for heart failure.

Thymosin β4 Prevents Angiotensin II-Induced Cardiomyocyte Growth by Regulating Wnt/WISP Signaling

Thymosin beta-4 (Tβ4) is a ubiquitous protein with many properties relating to cell proliferation and differentiation that promotes wound healing and modulates inflammatory mediators. However, the role of Tβ4 in cardiomyocyte hypertrophy is currently unknown. The purpose of this study was to determine the cardio-protective effect of Tβ4 in angiotensin II (Ang II)-induced cardiomyocyte growth. Neonatal rat ventricular cardiomyocytes (NRVM) were pretreated with Tβ4 followed by Ang II stimulation. Cell size, hypertrophy marker gene expression and Wnt signaling components, β-catenin, and Wnt-induced secreted protein-1 (WISP-1) were evaluated by quantitative real-time PCR, Western blotting and fluorescent microscopy. Pre-treatment of Tβ4 resulted in reduction of cell size, hypertrophy marker genes and Wnt-associated gene expression, and protein levels; induced by Ang II in cardiomyocyte. WISP-1 was overexpressed in NRVM and, the effect of Tβ4 in Ang II-induced cardiomyocyte growth was evaluated. WISP-1 overexpression promoted cardiomyocytes growth and was reversed by pretreatment with Tβ4. This is the first report which demonstrates that Tβ4 targets Wnt/WISP-1 to protect Ang II-induced cardiomyocyte growth. J. Cell. Physiol. 231: 1737-1744, 2016. © 2015 Wiley Periodicals, Inc.