Transcription Factors Involved in the Development and Prognosis of Cardiac Remodeling

Cardiomyocytic FoxP3 Attenuates Expression of β Isoform of Myosin Heavy Chain During Cardiac Hypertrophy and Effects of Triptolide

Cardiac hypertrophy, a maladaptive response to chronic stress, progresses to heart failure through mechanisms requiring deeper exploration. While forkhead helix transcription factor P3 (FoxP3) is well-known as a key regulator in CD4+ T cells, its role in cardiomyocytes remains unclear. Here, by using isoproterenol (ISO)-induced cardiac hypertrophy models (40 mg/kg daily for in vivo study and 10 μmol/L for in vitro study), we revealed the protective role of FoxP3 in cardiac hypertrophy. Though modulating FoxP3 expression using siRNA or plasmid in cardiomyocytes, we found that FoxP3 knockdown exacerbated ISO-induced hypertrophic responses, while overexpression of FoxP3 attenuated hypertrophic effects. The protective function of cardiomyocytic FoxP3 in vivo was further confirmed by infection of adeno-associated virus. Mechanically, the cardiomyocytic FoxP3 decreased the expression of nuclear factor of activated T cells c3 (NFATc3), a key regulator of hypertrophy-related genes, to suppress hypertrophy-related genes, including atrial natriuretic peptide, brain natriuretic peptide and β-myosin heavy chain (β-MHC), and thus ameliorate hypertrophic responses. Besides, the immunoprecipitation and immunofluorescence determination showed that FoxP3 could interact with NFATc3 in the nucleus to form a transcription complex, thereby regulating the transcription activity of NFATc3. Chromatin immunoprecipitation (ChIP) and electrophoretic mobility shift assays (EMSAs) revealed the specific binding sequences of FoxP3 in the β-MHC promoter region, with binding occupancy reduced by ISO, suggesting that FoxP3 could interact with NFATc3 to down-regulate the β-MHC expression. Importantly, we identified triptolide (TP), a bioactive natural product, as a potent inducer of FoxP3 expression. Both in vivo (10 μg/kg daily) and in vitro (10 μmol/L) studies demonstrated that TP significantly reversed cardiac hypertrophy by upregulating FoxP3 expression, thereby inhibiting NFATc3-mediated β-MHC transcription. These findings highlight cardiomyocytic FoxP3 as a novel protective factor, elucidating its underlying mechanisms and demonstrating the therapeutic potential of TP in this process.

Mesenchymal stem cells may alleviate angiotensin II-induced myocardial fibrosis and hypertrophy by upregulating SFRS3 expression

INTRODUCTION AND OBJECTIVES

The development of cardiac fibrosis (CF) and hypertrophy (CH) can lead to heart failure. Mesenchymal stem cells (MSCs) have shown promise in treating cardiac diseases. However, the relationship between MSCs and splicing factor arginine/serine rich-3 (SFRS3) remains unclear. In this study, our objectives are to investigate the effect of MSCs on SFRS3 expression, and their impact on CF and CH. Additionally, we aim to explore the function of the overexpression of SFRS3 in angiotensin II (Ang II)-treated cardiac fibroblasts (CFBs) and cardiac myocytes (CMCs).

METHODS

Rat cardiac fibroblasts (rCFBs) or rat cardiac myocytes (rCMCs) were co-cultured with rat MSCs (rMSCs). The function of SFRS3 in Ang II-induced rCFBs and rCMCs was studied by overexpressing SFRS3 in these cells, both with and without the presence of rMSCs. We assessed the expression of SFRS3 and evaluated the cell cycle, proliferation and apoptosis of rCFBs and rCMCs. We also measured the levels of interleukin (IL)-β, IL-6 and tumor necrosis factor (TNF)-α and assessed the degree of fibrosis in rCFBs and hypertrophy in rCMCs.

RESULTS

rMSCs induced SFRS3 expression and promoted cell cycle, proliferation, while reducing apoptosis of Ang II-treated rCFBs and rCMCs. Co-culture of rMSCs with these cells also repressed cytokine production and mitigated the fibrosis of rCFBs, as well as hypertrophy of rCMCs triggered by Ang II. Overexpression of SFRS3 in the rCFBs and rCMCs yielded identical effects to rMSC co-culture.

CONCLUSION

MSCs may alleviate Ang II-induced cardiac fibrosis and cardiomyocyte hypertrophy by increasing SFRS3 expression in vitro.

BIT: Bayesian Identification of Transcriptional Regulators from Epigenomics-Based Query Region Sets

Transcriptional regulators (TRs) are master controllers of gene expression and play a critical role in both normal tissue development and disease progression. However, existing computational methods for identification of TRs regulating specific biological processes have significant limitations, such as relying on distance on a linear chromosome or binding motifs that have low specificity. Many also use statistical tests in ways that lack interpretability and rigorous confidence measures. We introduce BIT, a novel Bayesian hierarchical model for in-silico TR identification. Leveraging a comprehensive library of TR ChIP-seq data, BIT offers a fully integrated Bayesian approach to assess genome-wide consistency between user-provided epigenomic profiling data and the TR binding library, enabling the identification of critical TRs while quantifying uncertainty. It avoids estimation and inference in a sequential manner or numerous isolated statistical tests, thereby enhancing accuracy and interpretability. BIT successfully identified critical TRs in perturbation experiments, functionally essential TRs in various cancer types, and cell-type-specific TRs within heterogeneous cell populations, offering deeper biological insights into transcriptional regulation.

Role of KLF4 and SIAT7A interaction accelerates myocardial hypertrophy induced by Ang II

Sialylation catalysed by sialyltransferase 7A (SIAT7A) plays a role in the development of cardiac hypertrophy. However, the regulatory mechanisms upstream of SIAT7A in this context remain poorly elucidated. Previous study demonstrated that KLF4 activates the SIAT7A gene in ischemic myocardium by binding to its promoter region. Nevertheless, the potential involvement of KLF4 in regulating SIAT7A expression in Ang II-induced hypertrophic cardiomyocytes remains uncertain. This study seeks to deepen the underlying mechanisms of the KLF4 and SIAT7A interaction in the progression of Ang II-induced cardiac hypertrophy. The results showed a concurrent increase in SIAT7A and KLF4 levels in hypertrophic myocardium of essential hypertension patients and in hypertrophic cardiomyocytes stimulated by Ang II. In vitro experiments revealed that reducing KLF4 levels led to a decrease in both SIAT7A synthesis and Sialyl-Tn antigen expression, consequently inhibiting Ang II-induced cardiomyocyte hypertrophy. Intriguingly, reducing SIAT7A levels also resulted in decreased KLF4 expression and suppression cardiomyocyte hypertrophy. Consistent with this, elevating SIAT7A levels increased KLF4 expression and exacerbated cardiomyocyte hypertrophy in both in vivo and in vitro experiments. Additionally, a time-course analysis indicated that KLF4 expression preceded that of SIAT7A. Luciferase reporter assays further confirmed that modulating SIAT7A levels directly influenced the transcriptional activity of KLF4 in cardiomyocytes. In summary, KLF4 expression is upregulated in cardiomyocytes treated with Ang II, which subsequently induces the expression of SIAT7A. The elevated levels of SIAT7A, in turn, enhance the transcription of KLF4. These findings suggest a positive feedback loop between KLF4 and SIAT7A-Sialyl-Tn, ultimately promoting Ang II-induced cardiac hypertrophy.

Vincristine attenuates isoprenaline-induced cardiac hypertrophy in male Wistar rats via suppression of ROS/NO/NF-қB signalling pathways

Vincristine (VCR), a vinca alkaloid with anti-tumor and anti-oxidant properties, is acclaimed to possess cardioprotective action. However, the molecular mechanism underlying this protective effect remains unknown. This study investigated the effects of VCR on isoprenaline (ISO), a beta-adrenergic receptor agonist, induced cardiac hypertrophy in male Wistar rats. Animals were pre-treated with ISO (1 mg/kg) intraperitoneally for 14 days before VCR (25 μg/kg) intraperitoneal injection from days 1 to 28. Thereafter, mechanical, and electrical activities of the hearts of the rats were measured using a non-invasive blood pressure monitor and an electrocardiograph, respectively. After which, the heart was homogenized, and supernatants were assayed for contractile proteins: endothelin-1, cardiac troponin-1, angiotensin-II, and creatine kinase-MB, with markers of oxidative/nitrergic stress (SOD, CAT, MDA, GSH, and NO), inflammation (TNF-a and IL-6, NF-kB), and caspase-3 indicative of VCR reduced elevated blood pressure and reversed the abnormal electrocardiogram. ISO-induced increased endothelin-1, cardiac troponin-1, angiotensin-II, and creatine phosphokinase-MB, which were reversed by VCR. ISO also increased TNF-α, IL-6, NF-kB expression with increased caspase-3-mediated apoptosis in the heart. However, VCR reduced ISO-induced inflammation and apoptosis, with improved endogenous antioxidant agents (GSH, SOD, CAT) relative to ISO controls. Moreso, VCR, protected against ISO-induced histoarchitectural degeneration of cardiac myofibre. The result of this study revealed that VCR treatment significantly reverses ISO-induced cardiac hypertrophic phenotypes, via mechanisms connected to improved levels of proteins involved in excitation-contraction, and suppression of oxido-inflammatory and apoptotic pathways.

Modeling cardiomyocyte signaling and metabolism predicts genotype-to-phenotype mechanisms in hypertrophic cardiomyopathy

Familial hypertrophic cardiomyopathy (HCM) is a significant precursor of heart failure and sudden cardiac death, primarily caused by mutations in sarcomeric and structural proteins. Despite the extensive research on the HCM genotype, the complex and context-specific nature of many signaling and metabolic pathways linking the HCM genotype to phenotype has hindered therapeutic advancements for patients. Here, we have developed a computational model of HCM encompassing cardiomyocyte signaling and metabolic networks and their associated interactions. Utilizing a stochastic logic-based ODE approach, we linked cardiomyocyte signaling to the metabolic network through a gene regulatory network and post-translational modifications. We validated the model against published data on activities of signaling species in the HCM context and transcriptomes of two HCM mouse models (i.e., R403Q-αMyHC and R92W-TnT). Our model predicts that HCM mutation induces changes in metabolic functions such as ATP synthase deficiency and a transition from fatty acids to carbohydrate metabolism. The model indicated major shifts in glutamine-related metabolism and increased apoptosis after HCM-induced ATP synthase deficiency. We predicted that the transcription factors STAT, SRF, GATA4, TP53, and FoxO are the key regulators of cardiomyocyte hypertrophy and apoptosis in HCM in alignment with experiments. Moreover, we identified shared (e.g., activation of PGC1α by AMPK, and FHL1 by titin) and context-specific mechanisms (e.g., regulation of Ca2+ sensitivity by titin in HCM patients) that may control genotype-to-phenotype transition in HCM across different species or mutations. We also predicted potential combination drug targets for HCM (e.g., mavacamten plus ROS inhibitors) preventing or reversing HCM phenotype (i.e., hypertrophic growth, apoptosis, and metabolic remodeling) in cardiomyocytes. This study provides new insights into mechanisms linking genotype to phenotype in familial hypertrophic cardiomyopathy and offers a framework for assessing new treatments and exploring variations in HCM experimental models.

Basic science of cardiac contractility modulation therapy: Molecular and electrophysiological mechanisms

In heart failure with reduced ejection fraction and heart failure with preserved ejection fraction, profound cellular and molecular changes have recently been documented in the failing myocardium. These changes include altered calcium handling and metabolic efficiency of the cardiac myocyte, reactivation of the fetal gene program, changes in the electrophysiological properties of the heart, and accumulation of collagen (fibrosis) at the interstitial level. Cardiac contractility modulation therapy is an innovative device-based therapy currently approved for heart failure with reduced ejection fraction in patients with narrow QRS complex and under investigation for the treatment of heart failure with preserved ejection fraction. This therapy is based on the delivery of high-voltage biphasic electrical signals to the septal wall of the right ventricle during the absolute refractory period of the myocardium. At the cellular level, in patients with heart failure with reduced ejection fraction, cardiac contractility modulation therapy has been shown to restore calcium handling and improve the metabolic status of cardiac myocytes, reverse the heart failure-associated fetal gene program, and reduce the extent of interstitial fibrosis. This review summarizes the preclinical literature on the use of cardiac contractility modulation therapy in heart failure with reduced and preserved ejection fraction, correlating the molecular and electrophysiological effects with the clinical benefits demonstrated by this therapy.

The benign nature and rare occurrence of cardiac myxoma as a possible consequence of the limited cardiac proliferative/ regenerative potential: a systematic review

BACKGROUND

Cardiac Myxoma is a primary tumor of heart. Its origins, rarity of the occurrence of primary cardiac tumors and how it may be related to limited cardiac regenerative potential, are not yet entirely known. This study investigates the key cardiac genes/ transcription factors (TFs) and signaling pathways to understand these important questions.

METHODS

Databases including PubMed, MEDLINE, and Google Scholar were searched for published articles without any date restrictions, involving cardiac myxoma, cardiac genes/TFs/signaling pathways and their roles in cardiogenesis, proliferation, differentiation, key interactions and tumorigenesis, with focus on cardiomyocytes.

RESULTS

The cardiac genetic landscape is governed by a very tight control between proliferation and differentiation-related genes/TFs/pathways. Cardiac myxoma originates possibly as a consequence of dysregulations in the gene expression of differentiation regulators including Tbx5, GATA4, HAND1/2, MYOCD, HOPX, BMPs. Such dysregulations switch the expression of cardiomyocytes into progenitor-like state in cardiac myxoma development by dysregulating Isl1, Baf60 complex, Wnt, FGF, Notch, Mef2c and others. The Nkx2-5 and MSX2 contribute predominantly to both proliferation and differentiation of Cardiac Progenitor Cells (CPCs), may possibly serve roles based on the microenvironment and the direction of cell circuitry in cardiac tumorigenesis. The Nkx2-5 in cardiac myxoma may serve to limit progression of tumorigenesis as it has massive control over the proliferation of CPCs. The cardiac cell type-specific genetic programming plays governing role in controlling the tumorigenesis and regenerative potential.

CONCLUSION

The cardiomyocytes have very limited proliferative and regenerative potential. They survive for long periods of time and tightly maintain the gene expression of differentiation genes such as Tbx5, GATA4 that interact with tumor suppressors (TS) and exert TS like effect. The total effect such gene expression exerts is responsible for the rare occurrence and benign nature of primary cardiac tumors. This prevents the progression of tumorigenesis. But this also limits the regenerative and proliferative potential of cardiomyocytes. Cardiac Myxoma develops as a consequence of dysregulations in these key genes which revert the cells towards progenitor-like state, hallmark of CM. The CM development in carney complex also signifies the role of TS in cardiac cells.

Transcription factor-mediated direct cellular reprogramming yields cell-type specific DNA methylation signature

Direct reprogramming, inducing the conversion of one type of somatic cell into another by the forced expression of defined transcription factors, is a technology with anticipated medical applications. However, due to the many unresolved aspects of the induction mechanisms, it is essential to thoroughly analyze the epigenomic state of the generated cells. Here, we performed comparative genome-wide DNA methylation analyses of mouse embryonic fibroblasts (MEFs) and cells composing organoids formed by intestinal stem cells (ISCs) or induced ISCs (iISCs) that were directly induced from MEFs. We found that the CpG methylation state was similar between cells forming ISC organoids and iISC organoids, while they differed widely from those in MEFs. Moreover, genomic regions that were differentially methylated between ISC organoid- and iISC organoid-forming cells did not significantly affect gene expression. These results demonstrate the accuracy and safety of iISC induction, leading to the medical applications of this technology.

Transcriptional regulation of macrophages in heart failure

Adverse cardiac remodeling after acute myocardial infarction is the most important pathological mechanism of heart failure and remains a major problem in clinical practice. Cardiac macrophages, derived from tissue resident macrophages and circulating monocyte, undergo significant phenotypic and functional changes following cardiac injury and play crucial roles in inflammatory response and tissue repair response. Currently, numerous studies indicate that epigenetic regulatory factors and transcription factors can regulate the transcription of inflammatory and reparative genes and timely conversion of inflammatory macrophages into reparative macrophages and then alleviate cardiac remodeling. Accordingly, targeting transcriptional regulation of macrophages may be a promising option for heart failure treatment. In this review, we not only summarize the origin and function of cardiac macrophages, but more importantly, describe the transcriptional regulation of macrophages in heart failure, aiming to provide a potential therapeutic target for heart failure.

Regulatory mechanism of icariin in cardiovascular and neurological diseases

Cardiovascular diseases (CVDs) and neurological diseases are widespread diseases with substantial rates of morbidity and mortality around the world. For the past few years, the preventive effects of Chinese herbal medicine on CVDs and neurological diseases have attracted a great deal of attention. Icariin (ICA), the main constituent of Epimedii Herba, is a flavonoid. It has been shown to provide neuroprotection, anti-tumor, anti-osteoporosis, and cardiovascular protection. The endothelial protection, anti-inflammatory, hypolipidemic, antioxidative stress, and anti-apoptosis properties of ICA can help stop the progression of CVDs and neurological diseases. Therefore, our review summarized the known mechanisms and related studies of ICA in the prevention and treatment of cardio-cerebrovascular diseases (CCVDs), to better understand its therapeutic potential.

PLAU is associated with cell migration and invasion and is regulated by transcription factor YY1 in cervical cancer

Cervical cancer, one of the most common malignancies, has a poor survival rate. The identification of more biomarkers for cervical cancer diagnosis and therapy is urgently needed. Plasminogen activator urokinase (PLAU) exerts multiple biological effects in various physiological and pathological processes; however the role of PLAU in cervical cancer progression is not fully understood. In the present study, the involvement and transcriptional regulation of PLAU in cervical cancer were explored. The expression of PLAU in cervical cancer was first analyzed, and PLAU was found to be overexpressed. In vitro experiments demonstrated that the migration and invasion of HeLa and HT3 cells were significantly suppressed by PLAU knockdown. Additionally, the core promoter of PLAU was confirmed, and the transcription factor YinYang 1 (YY1) was found to regulate PLAU mRNA expression. Overall, the present study elucidated the direct association between PLAU and cervical cancer, suggesting the YY1/PLAU axis as a potential novel therapeutic target for cervical cancer.

Upregulation of Phospholipase C Gene Expression Due to Norepinephrine-Induced Hypertrophic Response

The activation of phospholipase C (PLC) is thought to have a key role in the cardiomyocyte response to several different hypertrophic agents such as norepinephrine, angiotensin II and endothelin-1. PLC activity results in the generation of diacylglycerol and inositol trisphosphate, which are downstream signal transducers for the expression of fetal genes, increased protein synthesis, and subsequent cardiomyocyte growth. In this article, we describe the signal transduction elements that regulate PLC gene expression. The discussion is focused on the norepinephrine- α₁-adrenoceptor signaling pathway and downstream signaling processes that mediate an upregulation of PLC isozyme gene expression. Evidence is also indicated to demonstrate that PLC activities self-regulate the expression of PLC isozymes with the suggestion that PLC activities may be part of a coordinated signaling process for the perpetuation of cardiac hypertrophy. Accordingly, from the information provided, it is plausible that specific PLC isozymes could be targeted for the mitigation of cardiac hypertrophy.

Role of Phospholipase C in Catecholamine-induced Increase in Myocardial Protein Synthesis

The activation of the α1-adrenoceptor-(α1-AR) by norepinephrine results in the G-protein (Gqα) mediated increase in the phosphoinositide-specific phospholipase C (PLC) activity. The byproducts of PLC hydrolytic activity, namely, 1,2-diacylglycerol and inositol-1,4,5-trisphosphate, are important downstream signal transducers for increased protein synthesis in the cardiomyocyte and the subsequent hypertrophic response. In this article, evidence is outlined to demonstrate the role of cardiomyocyte PLC isozymes in the catecholamine-induced increase in protein synthesis by using a blocker of α1-AR and an inhibitor of PLC. The discussion will be focused on the α1-AR-Gqα-PLC-mediated hypertrophic signaling pathway from the viewpoint that it may compliment the other β1-AR-Gs protein-adenylyl cyclase signal transduction mechanisms in the early stages of cardiac hypertrophy development, but may become more relevant at the late stage of cardiac hypertrophy. From the information provided here, it is suggested that some specific PLC isozymes may potentially serve as important targets for the attenuation of cardiac hypertrophy in the vulnerable patient population at-risk for heart failure.