Secreted frizzled-related protein 2 prevents pressure-overload-induced cardiac hypertrophy by targeting the Wnt/β-catenin pathway

SP1-mediated transcriptional repression of SFRP5 is correlated with cardiac fibroblast activation and atrial myocyte apoptosis in the development of atrial fibrillation

Secreted frizzled related protein 5 (SFRP5) is a recognized cardioprotective protein with diminished expression in atrial fibrillation (AF). This study investigates SFRP5's function in AF-related cardiac fibrosis and cardiomyocyte apoptosis, exploring the underlying dysregulation causes. Utilizing C57BL/6 mice, mouse cardiac fibroblasts (CFs), and HC-1 mouse atrial myocyte cell line, AF models were induced by angiotensin Ⅱ (Ang Ⅱ). SFRP5 levels were consistently decreased in plasma samples from clinical patients, modeled mice, and CF culture supernatants. Treatment with recombinant SFRP5 restored its levels, mitigating Ang Ⅱ-induced AF in mice and ameliorating atrial tissue fibrosis and oxidative stress. In vitro, SFRP5 recombinant protein suppressed CF activation and fibrosis-related markers. The study identified Sp1 transcription factor (SP1) binding to the SFRP5 promoter, causing transcriptional repression. SP1 knockdown reinstated SFRP5 levels in mice and CFs, thus suppressing fibrosis. Additionally, SP1 knockdown attenuated Ang Ⅱ-induced apoptosis in HC-1 cells, but this effect was counteracted by concurrent SFRP5 knockdown. In conclusion, this investigation underscores that SP1 mediates SFRP5 loss during AF by transcriptional repression, contributing to fibrosis and myocyte apoptosis. These findings illuminate potential therapeutic interventions targeting the SFRP5-SP1 axis in AF-related cardiac complications.

Hair follicle-resident progenitor cells are a major cellular contributor to heterotopic subcutaneous ossifications in a mouse model of Albright hereditary osteodystrophy

Heterotopic ossifications (HOs) are the pathologic process by which bone inappropriately forms outside of the skeletal system. Despite HOs being a persistent clinical problem in the general population, there are no definitive strategies for their prevention and treatment due to a limited understanding of the cellular and molecular mechanisms contributing to lesion development. One disease in which the development of heterotopic subcutaneous ossifications (SCOs) leads to morbidity is Albright hereditary osteodystrophy (AHO). AHO is caused by heterozygous inactivation of GNAS, the gene that encodes the α-stimulatory subunit (Gαs) of G proteins. Previously, we had shown using our laboratory's AHO mouse model that SCOs develop around hair follicles (HFs). Here we show that SCO formation occurs due to inappropriate expansion and differentiation of HF-resident stem cells into osteoblasts. We also show in AHO patients and mice that Secreted Frizzled Related Protein 2 (SFRP2) expression is upregulated in regions of SCO formation and that elimination of Sfrp2 in male AHO mice exacerbates SCO development. These studies provide key insights into the cellular and molecular mechanisms contributing to SCO development and have implications for potential therapeutic modalities not only for AHO patients but also for patients suffering from HOs with other etiologies.

Increased Secreted Frizzled-Related Protein 2 in Hypertension-Induced Left Ventricular Remodeling

Background

Secreted frizzled-related protein 2 (sFRP2) is involved in various cardiovascular diseases. However, its relevance in left ventricular (LV) remodeling in patients with hypertension (HTN) is obscure.

Methods

In this study, 196 patients with HTN were included, 59 with echocardiographic LV remodeling. A total of 100 healthy subjects served as normal controls. The serum-sFRP2 level was measured by enzyme-linked immunosorbent assay (ELISA). Data were collected from medical records for baseline characteristics, biochemistry tests, and echocardiography. Receiver operating characteristic (ROC) curves were used to assess the distinguishing value of sFRP2 for LV remodeling in patients with HTN. Spearman rank correlation analysis was utilized to identify factors correlated with sFRP2. Cardiac sFRP2 was determined by Western blot and quantitative polymerase chain reaction (qPCR).

Results

The level of serum-sFRP2 was higher in HTN patients with echocardiographic LV remodeling than their non-remodeling counterparts. ROC analysis showed that the area under the curve (AUC) for sFRP2 in distinguishing echocardiographic LV remodeling in HTN patients was 0.791 (95% confidence interval (CI): 0.714-0.869). The sFRP2 was negatively correlated with LV dimension and positively correlated with relative wall thickness (RWT). The expression of sFRP2 was higher in hypertrophic hearts, which could be reversed by myricetin.

Conclusions

The serum level and cardiac sFRP2 increased in the setting of LV remodeling and decreased by myricetin. Serum sFRP2 may be a promising distinguishing factor for LV remodeling in HTN patients.

Secreted frizzled-related protein 2 ameliorates diabetic cardiomyopathy by activating mitophagy

OBJECTIVES

Secreted frizzled-related protein 2 (SFRP2), a novel adipokine that used to be considered an inhibitor of the canonical Wnt pathway, may play a protective role in metabolic disorders. However, its effect on diabetic cardiomyopathy was still unclear. Accumulating evidence indicates that mitophagy can protect cardiac function in the diabetic heart. The present study aimed to explore the roles of SFRP2 on diabetic cardiomyopathy, focusing on the effects and mechanisms for regulating mitophagy.

METHODS

Wild-type H9c2 cells, Sfrp2 overexpression and knockdown H9c2 cells were exposed to a glucolipotoxic milieu. Reactive oxygen species (ROS) production, cell viability, apoptosis, mitophagy and lysosomal activity were detected. The interaction of SFRP2 with frizzled 5 (FZD5), and its effect on expression and intracellular localization of transcription factor EB (TFEB) and β-catenin were also explored. Diabetic rats and Sfrp2 overexpression diabetic rats were constructed to further document the findings from the in vitro study.

RESULTS

The expression of SFRP2 was low and mitophagy was inhibited in H9c2 cells in a glucolipotoxic milieu. Sfrp2 overexpression activated mitophagy and reduced H9c2 cells injury, whereas Sfrp2 deficiency inhibited mitophagy and worsened this injury. Consistent with the in vitro findings, Sfrp2 overexpression ameliorated the impairment in cardiac function of diabetic rats by activating mitophagy. Sfrp2 overexpression upregulated the expression of calcineurin and TFEB, but did not affect β-catenin in vitro and in vivo. The calcineurin inhibitor tacrolimus can inhibit mitophagy and worsen cell injury in Sfrp2 overexpression H9c2 cells. Furthermore, we found that FZD5 is required for the SFRP2-induced activation of the calcineurin/TFEB pathway and interacts with SFRP2 in H9c2 cells. Transfection with small interfering RNA targeting FZD5 opposed the effects of Sfrp2 overexpression on mitophagy and cell survival in a glucolipotoxic environment.

CONCLUSIONS

SFRP2 can protect the diabetic heart by interacting with FZD5 and activating the calcineurin/TFEB pathway to upregulate mitophagy in H9c2 cells.

IRX2 activated by jumonji domain-containing protein 2A is crucial for cardiac hypertrophy and dysfunction in response to the hypertrophic stimuli

BACKGROUND

Iroquois homeobox 2 (IRX2) is a member of the Iroquois family whose upregulation has been potentially correlated to cardiac hypertrophy. This work studied the function of IRX2 and its related molecules in hypertrophic cardiomyopathy (HCM).

METHODS

A GEO dataset GSE32453 was analyzed to identify aberrantly expressed genes in HCM. Altered expression of IRX2 was induced in mice by lentivirus injection, followed by angiotensin II (Ang II) treatment to induce HCM. The function of IRX2 knockdown in ventricular dysfunction, heart volume and pathological changes in mice, and in surface area, oxidative stress and apoptosis of isolated cardiomyocytes were examined. Binding relationship between jumonji domain-containing protein 2A (JMJD2A) and IRX2 was predicted by online tools and validated. The interaction between JMJD2A and IRX2 in HCM development was examined by joint interventions.

RESULTS

IRX2 was highly expressed in heart tissues with HCM. IRX2 knockdown prevented mice from Ang II-induced ventricular dysfunction, cardiac hypertrophy, inflammation and fibrosis in mouse heart, and it decreased the levels of cardiac hypertrophy-related markers, oxidative stress response, and apoptosis of Ang II-treated cardiomyocytes. JMJD2A catalyzed demethylation of H3K9me3 near the IRX2 promoter to activate its transcription. JMJD2A knockdown similarly exerted protective functions against cardiac hypertrophy in vivo and in vitro, but the protection was blocked upon further IRX2 upregulation. IRX2 was found to increase the Wnt/β-catenin signaling activation.

CONCLUSION

This work reports that JMJD2A activates IRX2 transcription and the Wnt/β-catenin signaling to induce cardiac hypertrophy and dysfunction in HCM.

Inhibition of activin A receptor signalling attenuates age-related pathological cardiac remodelling

In the heart, ageing is associated with DNA damage, oxidative stress, fibrosis and activation of the activin signalling pathway, leading to cardiac dysfunction. The cardiac effects of activin signalling blockade in progeria are unknown. This study investigated the cardiac effects of progeria induced by attenuated levels of Ercc1, which is required for DNA excision and repair, and the impact of activin signalling blockade using a soluble activin receptor type IIB (sActRIIB). DNA damage and oxidative stress were significantly increased in Ercc1^Δ/− hearts, but were reduced by sActRIIB treatment. sActRIIB treatment improved cardiac systolic function and induced cardiomyocyte hypertrophy in Ercc1^Δ/− hearts. RNA-sequencing analysis showed that in Ercc1^Δ/− hearts, there was an increase in pro-oxidant and a decrease in antioxidant gene expression, whereas sActRIIB treatment reversed this effect. Ercc1^Δ/− hearts also expressed higher levels of anti-hypertrophic genes and decreased levels of pro-hypertrophic ones, which were also reversed by sActRIIB treatment. These results show for the first time that inhibition of activin A receptor signalling attenuates cardiac dysfunction, pathological tissue remodelling and gene expression in Ercc1-deficient mice and presents a potentially novel therapeutic target for heart diseases.

Summary: Attenuated DNA repair is associated with pathological cardiac remodelling and gene expression. Much of this phenotype is attenuated by inhibition of the activin signalling pathway using soluble activin receptor treatment.

Liquiritin Attenuates Angiotensin II-Induced Cardiomyocyte Hypertrophy via ATE1/TAK1-JNK1/2 Pathway

Objective

To investigate the protective effect and mechanism of liquiritin (LIQ) on cardiomyocyte hypertrophy induced by angiotensin II (Ang II).

Methods

H9c2 cells were pretreated with LIQ before and after Ang II treatment. CCK8 assay was performed to evaluate cell viability. The cell surface area was measured by phalloidin staining. The mRNA expression of atrial and B-type natriuretic peptides (ANP and BNP, respectively) and β-myosin heavy chain (β-MHC) was determined by quantitative reverse transcription-polymerase chain reaction (RT-qPCR); the protein levels of arginyltransferase 1 (ATE1), transforming growth factor beta-activated kinase 1 (TAK1), phos-TAK1, c-Jun N-terminal kinases1/2 (JNK1/2), and phos-JNK1/2 were determined by Western blotting. After constructing the ATE1 overexpression cell models with the pcDNA3.1/ATE1, the abovementioned indicators were tested using the introduced methods.

Results

LIQ at a concentration of ≤30 μM was not cytotoxic to H9c2 cells before exposure to Ang II. The protective effect of LIQ was best observed at 30 μM after Ang II treatment. Phalloidin staining and RT-qPCR results indicated that the deposition of Ang II increased the cell surface area and levels of ANP, BNP, and β-MHC. On the other hand, Western blotting results showed that Ang II increased the ATE1 protein levels and TAK1 and JNK1/2 phosphorylation, which were significantly alleviated after LIQ treatment. LIQ also directly inhibited the ATE1 overexpression in H9c2 cells transfected with pcDNA3.1/ATE1 and further inhibited TAK1 and JNK1/2 phosphorylation.

Conclusion

LIQ can attenuate Ang II-induced cardiomyocyte hypertrophy by regulating the ATE1/TAK1-JNK1/2 pathway.

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.

Indoxyl sulfate reduces Ito,f by activating ROS/MAPK and NF-κB signaling pathways

There is a high prevalence of ventricular arrhythmias related to sudden cardiac death in patients with chronic kidney disease (CKD). To explored the possible mechanism of CKD-related ventricular arrhythmias, a CKD rat model was created, and indoxyl sulfate (IS) was further used in vivo and in vitro. This project used the following methods: patch clamp, electrocardiogram, and some molecular biology experimental techniques. IS was found to be significantly elevated in the serum of CKD rats. Interestingly, the expression levels of the fast transient outward potassium current-related (Ito,f-related) proteins (Kv4.2, Kv4.3, and KChIP2) in the heart of CKD rats and rats treated with IS decreased. IS dose-dependently reduced Ito,f density, accompanied by the decreases in Kv4.2, Kv4.3, and KChIP2 proteins in vitro. IS also prolonged the action potential duration and QT interval, and paroxysmal ventricular tachycardia could be induced by IS. In-depth studies have shown that ROS/p38MAPK, ROS-p44/42 MAPK, and NF-κB signaling pathways play key roles in the reduction of Ito,f density and Ito,f-related proteins caused by IS. These data suggest that IS reduces Ito,f-related proteins and Ito,f density by activating ROS/MAPK and NF-κB signaling pathways, and the action potential duration and QT interval are subsequently prolonged, which contributes to increasing the susceptibility to arrhythmia in CKD.

Inverse Associations Between Circulating Secreted Frizzled Related Protein 2 (sFRP2) and Cardiometabolic Risk Factors

Background: Secreted frizzled-related protein 2 (sFRP2) plays an important role in metabolic syndrome and cardiovascular diseases (CVDs); However, its relevance with cardiometabolic diseases remains to be elucidated. We aimed to determine the serum levels of sFRP2 in patients at different stages of heart failure (HF) with or without type 2 diabetes mellitus (T2DM), and assess the correlation between circulating sFRP2 levels and cardiometabolic risk factors. Methods: In this study, serum samples from 277 patients visiting Zhongshan Hospital affiliated to Fudan University were collected. These patients were clinically diagnosed and categorized as five groups, including the control group, pre-clinical HF group, pre-clinical HF+T2DM group, HF group and HF+T2DM group. Serum sFRP2 levels were measured with enzyme-linked immunosorbent assay (ELISA) tests and the clinical characteristics of each patient were recorded. Spearman rank correlation analysis and multiple stepwise linear regression analysis were conducted. Univariate and multivariate logistic regression analysis were performed to screen risk factors for HF in patients with CVDs. Results: Serum sFRP2 levels were significantly lower in the HF+T2DM group compared with the other four groups. Spearman rank correlation analysis showed that sFRP2 was negatively correlated with parameters including patients' age, fasting plasma glucose (FPG), glycated hemoglobin A1c (HbA1c), cardiac troponin T (cTNT), N-terminal pro-B-type natriuretic peptide (NT-proBNP), high-sensitivity C-reactive protein (hs-CRP), left atrial dimension (LAD) and left ventricular posterior wall (LVPW), and positively correlated with hemoglobin, estimated glomerular filtration rate (eGFR), albumin, total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and left ventricular ejection fraction (LVEF). However, in multiple regression analysis, significant associations with ln(sFRP2) were observed only in FPG, hs-CRP and LAD. Higher serum sFRP2 was significantly linked to lower odds of HF in patients with CVDs. Conclusion: sFRP2 progressively decreased when glucose homeostasis and cardiac function deteriorated. sFRP2 acted as a risk factor for HF in patients with CVDs, especially in those with concomitant T2DM.

Yap Promotes Noncanonical Wnt Signals From Cardiomyocytes for Heart Regeneration

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Epigenetic alterations of TGFβ and its main canonical signaling mediators in the context of cardiac fibrosis

Cardiac fibrosis is a pathological process that presents a continuous overproduction of extracellular matrix (ECM) components in the myocardium, which negatively influences the progression of many cardiac diseases. Transforming growth factor β (TGFβ) is the main ligand that triggers the production of pro-fibrotic ECM proteins. In the cardiac fibrotic process, TGFβ and its canonical signaling mediators are tightly regulated at different levels as well as epigenetically. Cardiac fibroblasts are one of the most important TGFβ target cells activated after cardiac injury. TGFβ-driven fibroblast activation is subject to epigenetic modulation and contributes to the progression of cardiac fibrosis, mainly through the expression of pro-fibrotic molecules implicated in the disease. In this review, we describe epigenetic regulation related to canonical TGFβ signaling in cardiac fibroblasts.

miR-155-5p upregulation ameliorates myocardial insulin resistance via mTOR signaling in chronic alcohol drinking rats

Background

Chronic alcohol intake is associated with an increased risk of alcoholic cardiomyopathy, which may present with pathological changes such as myocardial insulin resistance, leading to ventricular dilation and cardiac dysfunction. Although a correlation between microRNA-155 (miR-155) and insulin signaling has been identified, the underlying mechanism has not been elucidated to date. The purpose of the study was to determine whether overexpression of miR-155-5p in vivo could ameliorate chronic alcohol-induced myocardial insulin resistance and cardiac dysfunction.

Material and Methods

Wistar rats were fed with either alcohol or water for 20 weeks to establish chronic alcohol intakes model. Then the alcohol group were divided into three groups: model group, miRNA-155 group and AAV-NC group. Rats undergoing alcohol treatment were injected with AAV-miRNA-155 (adeno-associated virus 9) or its negative control AAV-NC, respectively. Gene expression was determined by real-time PCR, and protein expression was determined by western blot. Echocardiography was performed to assess terminal cardiac function. Insulin responsiveness was determined through the quantification of phosphorylated insulin receptor substrate 1 (ser 307) and phosphorylated insulin receptor (Tyr 1185) levels.

Results

We found that cardiac function was attenuated in chronic alcohol intake rats, with an activated mammalian target of rapamycin (mTOR) signaling pathway, accompanied by an increase in p-IRS1(ser 307) and a decrease in p-IR (Tyr 1185) level in myocardial tissue. Also, alcohol drinking significantly up-regulated miR-155-5p level and its overexpression decreased p-IRS1 (ser 307) and increased p-IR (Tyr 1185) levels, and meanwhile inhibited the mTOR signaling pathway.

Conclusion

miR-155-5p upregulation ameliorates myocardial insulin resistance via the mTOR signaling in chronic alcohol drinking rats. We propose that miR-155 may serve as a novel potential therapeutic target for alcoholic heart disease.