Increased β-catenin accumulation and nuclear translocation are associated with concentric hypertrophy in cardiomyocytes

Low-density lipoprotein receptor-related protein 6 ameliorates cardiac hypertrophy by regulating CTSD/HSP90α signaling during pressure overload

Pressure overload induces pathological cardiac remodeling, including cardiac hypertrophy and fibrosis, resulting in cardiac dysfunction or heart failure. Recently, we observed that the low-density lipoprotein receptor-related protein 6 (LRP6), has shown potential in enhancing cardiac function by mitigating cardiac fibrosis in a mouse model subjected to pressure overload. In this study, we investigated the role of LRP6 as a potential modulator of pressure overload-induced cardiac hypertrophy and elucidated the underlying molecular mechanisms. We performed transverse aortic constriction (TAC) to induce pressure overload in cardiomyocyte-specific LRP6 overexpression mice (LRP6-over mice) and in control mice (α-myosin heavy chain (α-MHC) Mer-Cre-Mer Tg mice or named MCM mice). Cardiac function and hypertrophy were assessed using echocardiography. LRP6-over mice showed improved cardiac function and reduced hypertrophy after TAC, compared with MCM mice. We also applied mechanical stretch to cultured neonatal rat cardiomyocytes to model pressure overload in vitro. Mass spectrometry analysis showed that LRP6 interacts with HSP90α and cathepsin D (CTSD) in cardiomyocytes under mechanical stress. Further analysis demonstrated that LRP6 facilitates CTSD-mediated degradation of HSP90α, consequently inhibiting β-catenin activation and reducing cardiac hypertrophy post-TAC. Treatment with recombinant HSP90α protein or the CTSD inhibitor, pepstatin A, partly abolished the protective effect of LRP6 overexpression on myocardial hypertrophy and cardiac function after TAC in mice. Collectively, our data suggest that LRP6 protects against pressure overload-induced myocardial remodeling and that the CTSD/HSP90α/β-catenin axis may be a potential therapeutic target.

Targeting Wnt Pathways with Small Molecules as New Approach in Cardiovascular Disease

The increasing incidences of morbidity and mortality associated with cardiovascular diseases represent significant difficulties for clinical treatment and have a major impact on patient health. Wnt signaling pathways are highly conserved and are well known for their regulatory roles in embryonic development, tissue regeneration, and adult tissue homeostasis. Wnt signaling is classified into two distinct pathways: canonical Wnt/β-catenin signaling and noncanonical pathways, including planar cell polarity and Wnt/Ca2+ pathways. A growing body of experimental evidence suggests the involvement of both canonical and non-canonical Wnt signaling pathways in the development of cardiovascular diseases, including myocardial hypertrophy, arrhythmias, diabetic cardiomyopathy, arrhythmogenic cardiomyopathy, and myocardial infarction. Thus, to enhance patient quality of life, diagnosing and treating cardiac illnesses may require a thorough understanding of the molecular functions played by the Wnt pathway in these disorders. Many small-molecule inhibitors specifically target various components within the Wnt signaling pathways, such as Frizzled, Disheveled, Porcupine, and Tankyrase. This study aims to present an overview of the latest findings regarding the functions of Wnt signaling in human cardiac disorders and possible inhibitors of Wnt, which could lead to novel approaches for treating cardiac ailments.

LncRNA CCAT2 Knockdown Alleviates Pressure Overload or Ang II-Induced Cardiac Hypertrophy Via Disruption of the Wnt/β-Catenin Signaling

BACKGROUND

Sustained pathological cardiac hypertrophy (CH) is an independent risk factor for increased incidence and mortality of cardiovascular events.

OBJECTIVES

This research was designed to unravel the role of long non-coding RNA (LncRNA) CCAT2 in CH progression.

METHODS

Transverse aortic constriction (TAC) procedures were conducted to construct a pressure overload-induced in vivo CH model. Angiotensin II (Ang II) treatment was utilized to induce hypertrophic rat cardiomyocyte H9c2 cells.

RESULTS

In vivo results showed that silencing of CCAT2 reduced cardiomyocyte surface area, alleviated cardiac fibrosis, and decreased β-MHC, ANP, and BNP levels in CH mouse models. In vitro results revealed that CCAT2 knockdown reduced cell surface area and attenuated β-MHC, ANP, and BNP levels in hypertrophic H9c2 cells. Besides, CCAT2 silencing decreased the levels of active β-catenin, phosphorylated-GSK-3β, and Wnt target genes (c-Myc, cyclinD1, and c-Jun) in CH mice and hypertrophic H9c2 cells. Importantly, treatment with the Wnt/β-catenin pathway activator LiCl reversed the suppression of CCAT2 knockdown on H9c2 cell surface area and MHC, ANP, and BNP levels.

CONCLUSIONS

Collectively, CCAT2 silencing plays a protective role against CH through inactivating the Wnt/β-catenin signaling, which suggests that CCAT2 might become a promising therapeutic target for CH.

Evaluation of the Canonical Wnt Signaling Pathway in the Hearts of Hypertensive Rats of Various Etiologies

Wnt/β-catenin signaling dysregulation is associated with the pathogenesis of many human diseases, including hypertension and heart disease. The aim of this study was to immunohistochemically evaluate and compare the expression of the Fzd8, WNT1, GSK-3β, and β-catenin genes in the hearts of rats with spontaneous hypertension (SHRs) and deoxycorticosterone acetate (DOCA)-salt-induced hypertension. The myocardial expression of Fzd8, WNT1, GSK-3β, and β-catenin was detected by immunohistochemistry, and the gene expression was assessed with a real-time PCR method. In SHRs, the immunoreactivity of Fzd8, WNT1, GSK-3β, and β-catenin was attenuated in comparison to that in normotensive animals. In DOCA-salt-induced hypertension, the immunoreactivity of Fzd8, WNT1, GSK-3β, and β-catenin was enhanced. In SHRs, decreases in the expression of the genes encoding Fzd8, WNT1, GSK-3β, and β-catenin were observed compared to the control group. Increased expression of the genes encoding Fzd8, WNT1, GSK-3β, and β-catenin was demonstrated in the hearts of rats with DOCA-salt-induced hypertension. Wnt signaling may play an essential role in the pathogenesis of arterial hypertension and the accompanying heart damage. The obtained results may constitute the basis for further research aimed at better understanding the role of the Wnt/β-catenin pathway in the functioning of the heart.

The role of β-catenin in cardiac diseases

The Wnt/β-catenin signaling pathway is a classical Wnt pathway that regulates the stability and nuclear localization of β-catenin and plays an important role in adult heart development and cardiac tissue homeostasis. In recent years, an increasing number of researchers have implicated the dysregulation of this signaling pathway in a variety of cardiac diseases, such as myocardial infarction, arrhythmias, arrhythmogenic cardiomyopathy, diabetic cardiomyopathies, and myocardial hypertrophy. The morbidity and mortality of cardiac diseases are increasing, which brings great challenges to clinical treatment and seriously affects patient health. Thus, understanding the biological roles of the Wnt/β-catenin pathway in these diseases may be essential for cardiac disease treatment and diagnosis to improve patient quality of life. In this review, we summarize current research on the roles of β-catenin in human cardiac diseases and potential inhibitors of Wnt/β-catenin, which may provide new strategies for cardiac disease therapies.

Huoxin pill prevents excessive inflammation and cardiac dysfunction following myocardial infarction by inhibiting adverse Wnt/β‑catenin signaling activation

BACKGROUND

Myocardial infarction (MI) is the most common cause of cardiac injury, resulting in widespread and irreversible damage to the heart. The incidence of MI gives rise to the excessive production of inflammatory cytokines that further promotes myocardial dysfunction. Wnt/β-catenin signaling pathway is adversely activated during MI and plays an important role in the modulation of the inflammatory response following tissue injury. Huoxin pill (HXP) is a Traditional Chinese Medicine formulation that has been long used in the treatment of cardiovascular diseases, however its mechanisms of cardioprotection remain unclear.

METHODS

We performed murine models of MI in order to model myocardial ischemic damage and examine the effect and underlying mechanism of HXP in protecting against myocardial ischemic injury. We further constructed conditional cardiomyocyte-specific β-catenin knockout mice and induced surgical MI in order to better understand the role of Wnt/β-catenin signaling following myocardial infarction in the adult heart.

RESULTS

HXP administration strongly protected against cardiac ischemic injury, improved cardiac function, and markedly decreased the expression of pro-inflammatory cytokines following MI. Nuclear activation of β‑catenin resulted in significantly increased nuclear translocation and activation of NF-κB. In contrast, cardiomyocyte-specific deletion of β-catenin decreased NF-κB activation and exhibited beneficial effects following ischemic injury. Hence, HXP protected against MI-induced ischemic injury and excessive inflammatory response via inhibiting Wnt/β‑catenin signaling.

CONCLUSIONS

Our study elucidated the role of HXP in protecting against ischemic myocardial injury via preventing MI-induced inflammatory response, which was mediated by its ability to inhibit adverse Wnt/β‑catenin signaling activation. Thus, our study provides the basis for the implementation of HXP as an effective therapeutic strategy in protecting against myocardial ischemic diseases.

The role of the Wnt / β-catenin pathway and the functioning of the heart in arterial hypertension - A review

Many factors and molecular pathways are involved in the pathogenesis of arterial hypertension. The increase in blood pressure may be determined by the properties of specific gene products and their associated action with environmental factors. In recent years, much attention has been paid to the Wnt/β-catenin signaling pathway which is essential for organ damage repair and homeostasis. Deregulation of the activity of the Wnt/β-catenin pathway may be directly or indirectly related to myocardial hypertrophy, as well as to cardiomyocyte remodeling and remodeling processes in pathological states of this organ. There are reports pointing to the role of the Wnt/β-catenin pathway in the course and development of organ complications in conditions of arterial hypertension. This paper presents the current state of knowledge of the role of the Wnt/β-catenin pathway in the regulation of arterial pressure and its impact on the physiology and the development of the complications of arterial hypertension in the heart.

Resuscitating the Field of Cardiac Regeneration: Seeking Answers from Basic Biology

Heart failure (HF) is one of the leading causes for hospital admissions worldwide. HF patients are classified based on the chronic changes in left ventricular ejection fraction (LVEF) as preserved (LVEF ≥ 50%), reduced (LVEF ≤ 40%), or mid-ranged (40% < LVEF < 50%) HFs. Treatments nowadays can prevent HFrEF progress, whereas only a few of the treatments have been proven to be effective in improving the survival of HFpEF. In this review, numerous mediators involved in the pathogenesis of HF are summarized. The regional upstream signaling and their diagnostic and therapeutic potential are also discussed. Additionally, the recent challenges and development in cardiac regenerative therapy that hold opportunities for future research and clinical translation are discussed.

Chronic colitis upregulates microRNAs suppressing brain-derived neurotrophic factor in the adult heart

Ulcerative colitis and Crohn's disease are classified as chronic inflammatory bowel diseases (IBD) with known extraintestinal manifestations. The interplay between heart and gut in IBD has previously been noted, but the mechanisms remain elusive. Our objective was to identify microRNAs mediating molecular remodeling and resulting cardiac impairment in a rat model of colitis. To induce chronic colitis, dextran sodium sulfate (DSS) was given to adult rats for 5 days followed by 9 days with normal drinking water for 4 cycles over 8 weeks. Echocardiography was performed to evaluate heart function. DSS-induced colitis led to a significant decrease in ejection fraction, increased left ventricular mass and size, and elevated B-type natriuretic protein. MicroRNA profiling showed a total of 56 miRNAs significantly increased in the heart by colitis, 8 of which are predicted to target brain-derived neurotrophic factor (BDNF). RT-qPCR validated the increases of miR-1b, Let-7d, and miR-155. Transient transfection revealed that miR-155 significantly suppresses BDNF in H9c2 cells. Importantly, DSS colitis markedly decreased BDNF in both myocardium and serum. Levels of various proteins critical to cardiac homeostasis were also altered. Functional studies showed that BDNF increases cell viability and mitigates H2O2-induced oxidative damage in H9c2 cells, demonstrating its protective role in the adult heart. Mechanistically, cellular experiments identified IL-1β as the inflammatory mediator upregulating cardiac miR-155; this effect was confirmed in adult rats. Furthermore, IL-1β neutralizing antibody ameliorated the DSS-induced increase in miR-155 and concurrent decrease in BDNF in the adult heart, showing therapeutic potential. Our findings indicate that chronic colitis impairs heart function through an IL-1β→miR-155→BDNF signaling axis.

Histone H4R3 symmetric di-methylation by Prmt5 protects against cardiac hypertrophy via regulation of Filip1L/β-catenin

BACKGROUND AND PURPOSE

Although histone lysine methylation has been extensively studied for their participation in pathological cardiac hypertrophy, the potential regulatory role of histone arginine methylation remains to be elucidated. The present study focused on H4R3 symmetric di-methylation (H4R3me2s) induced by protein arginine methyltransferase 5 (Prmt5), and explored its epigenetic regulation and underlying mechanisms in cardiomyocyte hypertrophy.

METHODS AND RESULTS

1. The expressions of Prmt5 and H4R3me2s were suppressed in cardiac hypertrophy models in vivo and in vitro; 2. Prmt5 silencing or its inhibitor EPZ, or knockdown of cooperator of Prmt5 (Copr5) to disrupt H4R3me2s, facilitated cardiomyocyte hypertrophy, whereas overexpression of wild type Prmt5 rather than the inactive mutant protected cardiomyocytes against hypertrophy; 3. ChIP-sequence analysis identified Filip1L as a target gene of Prmt5-induced H4R3me2s; 4. Knockdown or inhibition of Prmt5 impaired Filip1L transcription and subsequently prevented β-catenin degradation, thus augmenting cardiomyocyte hypertrophy.

CONCLUSIONS

The present study reveals that Prmt5-induced H4R3me2s ameliorates cardiomyocyte hypertrophy by transcriptional upregulation of Filip1L and subsequent enhancement of β-catenin degradation. Deficiency of Prmt5 and the resulting suppression of H4R3me2s might facilitate the development of pathological cardiac hypertrophy. Prmt5 might serve as a key epigenetic regulator in pathological cardiac hypertrophy.

Curcumol Inhibits Lung Adenocarcinoma Growth and Metastasis via Inactivation of PI3K/AKT and Wnt/-Catenin Pathway

Curcumol (Cur), isolated from the Traditional Chinese Medical plant Rhizoma Curcumae, is the bioactive component of sesquiterpene reported to possess antitumor activity. However, its bioactivity and mechanisms against lung adenocarcinoma are still unclear. We investigated its effect on lung adenocarcinoma and elucidated its underlying molecular mechanisms. In vitro, Cur effectively suppressed proliferation, migration, and invasion of lung adenocarcinoma cells A549 and H460, which were associated with the altered expressions of signaling molecules, including p-AKT, p-PI3K, p-LRP5/6, AXIN, APC, GSK3 and p--catenin, matrix metalloproteinase (MMP)-2, and MMP-9. Furthermore, Cur significantly induced cell apoptosis of A549 and H460 by promoting the expression of Bax, caspase 3, and caspase 9 and suppressing the expression of Bcl-2, and arrested the cell cycle at the G₀/G₁ phase by lowering the levels of cyclin D1, CDK1, and CDK4. In vivo experiment revealed that Cur could inhibit lung tumor growth and lung metastasis, which were consistent with these in vitro results. In xenograft model mice, Cur strongly decreased tumor weight and tumor volume, which may be related to the downregulation of p-AKT and p-PI3K by immunofluorescence analysis. In addition, a lung metastasis model experiment suggested that Cur dramatically decreased the ratio of lung/total weight, tumor metastatic nodules, and the expressions of MMP-2 and MMP-9 in lung tissues compared with the control. Overall, these data suggested that the inhibitory activity of Cur on lung adenocarcinoma via the inactivation of PI3K/Akt and Wnt/-catenin pathways, at least in part, indicates that curcumol may be a potential antitumor agent for lung adenocarcinoma therapy.

β-catenin/LEF1/IGF-IIR Signaling Axis Galvanizes the Angiotensin-II- induced Cardiac Hypertrophy

Cardiovascular diseases have a high prevalence worldwide and constitute the leading causes of mortality. Recently, malfunctioning of β-catenin signaling has been addressed in hypertensive heart condition. Ang-II is an important mediator of cardiovascular remodeling processes which not only regulates blood pressure but also leads to pathological cardiac changes. However, the contribution of Ang-II/β-catenin axis in hypertrophied hearts is ill-defined. Employing in vitro H9c2 cells and in vivo spontaneously hypertensive rats (SHR) cardiac tissue samples, western blot analysis, luciferase assays, nuclear-cytosolic protein extracts, and immunoprecipitation assays, we found that under hypertensive condition β-catenin gets abnormally induced that co-activated LEF1 and lead to cardiac hypertrophy changes by up-regulating the IGF-IIR signaling pathway. We identified putative LEF1 consensus binding site on IGF-IIR promoter that could be regulated by β-catenin/LEF1 which in turn modulate the expression of cardiac hypertrophy agents. This study suggested that suppression of β-catenin expression under hypertensive condition could be exploited as a clinical strategy for cardiac pathological remodeling processes.

At the heart of inter- and intracellular signaling: the intercalated disc

Proper cardiac function requires the synchronous mechanical and electrical coupling of individual cardiomyocytes. The intercalated disc (ID) mediates coupling of neighboring myocytes through intercellular signaling. Intercellular communication is highly regulated via intracellular signaling, and signaling pathways originating from the ID control cardiomyocyte remodeling and function. Herein, we present an overview of the inter- and intracellular signaling that occurs at and originates from the intercalated disc in normal physiology and pathophysiology. This review highlights the importance of the intercalated disc as an integrator of signaling events regulating homeostasis and stress responses in the heart and the center of several pathophysiological processes mediating the development of cardiomyopathies.