Search Results (98)

Cardiac physiology and pathology have been extensively explored at the transcriptional level. Still, they are less understood at the translational level, including three major knowledge gaps: pathophysiological impact, molecular mechanisms, and therapeutic implications of translational control in cardiac biology and heart disease. This review aims to provide a summary of the most recent key findings in this emerging field of translational control in heart health and disease, covering the physiological functions, disease pathogenesis, biochemical mechanisms, and development of potential RNA-based, translation-manipulating drugs. Translation of mRNA to protein is the final step in the central dogma for protein synthesis. Translation machinery includes a family of essential “housekeeping” factors and enzymes required for mRNA translation. These translation factors ensure the accurate processing of mRNA to protein according to the genetic code and maintain the optimal quality and quantity of cellular proteins for normal cardiac function. Translation factors also regulate the efficiency, speed, and fidelity of protein production and play a role in cardiac pathological remodeling under stress conditions. This review first introduces the techniques and methods used to study the translational regulation of gene expression in the cardiac system. We then summarize discoveries of a variety of pathophysiological functions and molecular mechanisms of translational control in cardiac health and disease, focusing on two primary symptoms, cardiac hypertrophy and fibrosis. In these sessions, we discuss the translational regulation directed by specific regulatory factors in cardiac physiology and how their genetic mutations, expression dysregulation, or functional alterations contribute to the etiology of heart disease. Notably, translational control exhibits extensive crosstalk with other processes, including transcriptional regulation, mitochondrial metabolism, and sarcomere homeostasis. Furthermore, recent findings have revealed the role of translational regulation in cardiomyocyte proliferation and heart regeneration, providing new approaches for creating regenerative medicine. Because transcript-specific translational regulation of both pathological and protective proteins occurs in heart disease, target-selective translation inhibitors and enhancers can be developed. These inhibitors and enhancers offer valuable insights into novel therapeutic targets and the development of RNA-based drugs for heart disease treatment. Full article

Background: Alternative splicing is an important mechanism of transcriptomic and proteomic diversity and is progressively involved in cardiovascular disease (CVD) pathogenesis. Serum response factor (SRF), a critical transcription factor in cardiac development and function, may itself undergo splicing regulation, potentially altering its function in disease states. Objective: The objective of this study is to identify SRF-associated alternative splicing events in cardiac pathological conditions and examine regulatory interactions with splicing factors using RNA-seq data. Methods: Three human heart RNA-seq databases (PRJNA198165, PRJNA477855, PRJNA678360) were used, comprising various cardiac conditions like non-ischemic cardiomyopathy (NICM), ischemic cardiomyopathy (ICM), dilated cardiomyopathy (DCM), and heart failure with reduced ejection fraction (HFrEF), with and without left ventricular assist device (LVAD) support. Splicing events were identified using the rMATS tool, and correlation analyses were performed between SRF and predicted splicing factors. Functional enrichment of SRF-correlated genes was assessed via Gene Ontology (GO) and KEGG pathways. Results: The skipped exon (SE) events were the predominant splicing type across all datasets. SRF chr6, including (Exon 2, 43,173,847–43,174,113), (Exon 4, 43,176,548–43,176,667), and (Exon 5, 43,178,294-43,178,485), were most frequently involved in SE and mutually exclusive exon (MXE) events across multiple heart failure subtypes. Correlation analysis revealed strong positive associations between SRF and several splicing factors (HNRNPL, HNRNPD, SRSF5, and SRSF8). GO and KEGG analyses revealed enrichment of muscle development, sarcomere structure, lipid metabolism, and immune signaling pathways. Conclusions: Our study shows that SRF is subject to extensive alternative splicing in heart failure, particularly at Exon 2 and Exon 5, suggesting isoform-specific roles in cardiac remodeling. The strong co-expression with specific splicing factors delineates a regulatory axis that may explain the pathological transcriptome in cardiomyopathy. These findings provide a foundation for exploring splicing-based biomarkers and therapeutic targets in cardiac pathology for SRF. Full article

Cardiovascular disease encompasses a wide group of conditions that affect the heart and blood vessels. Of these diseases, cardiomyopathies and arrhythmias specifically have been well-studied in their relationship to cardiac dyads, nanoscopic structures that connect electrical signals to muscle contraction. The proper development and positioning of dyads is essential in excitation–contraction (EC) coupling and, thus, beating of the heart. Three proteins, namely CMYA5, JPH2, and BIN1, are responsible for maintaining the dyadic cleft between the T-tubule and junctional sarcoplasmic reticulum (jSR). Various other dyadic proteins play integral roles in the primary function of the dyad—translating a propagating action potential (AP) into a myocardial contraction. Ca²⁺, a secondary messenger in this process, acts as an allosteric activator of the sarcomere, and its cytoplasmic concentration is regulated by the dyad. Loss-of-function mutations have been shown to result in cardiomyopathies and arrhythmias. Adeno-associated virus (AAV) gene therapy with dyad components can rescue dyadic dysfunction, which results in cardiomyopathies and arrhythmias. Overall, the dyad and its components serve as essential mediators of calcium homeostasis and excitation–contraction coupling in the mammalian heart and, when dysfunctional, result in significant cardiac dysfunction, arrhythmias, morbidity, and mortality. Full article

Background/Objectives: Cardiac aging involves the progressive structural and functional decline of the myocardium. Endurance training is a well-recognized non-pharmacological intervention that counteracts this decline, yet the molecular mechanisms driving exercise-induced cardiac rejuvenation remain inadequately elucidated. This study aimed to identify key effector genes and regulatory pathways by integrating human cardiac aging transcriptomic data with multi-omic exercise response datasets. Methods: A systems biology framework was developed to integrate age-downregulated genes (n = 243) from the GTEx human heart dataset and endurance-exercise-responsive genes (n = 634) from the MoTrPAC mouse dataset. Thirty-seven overlapping genes were identified and subjected to Enrichr for pathway enrichment, KEA3 for kinase analysis, and ChEA3 for transcription factor prediction. Candidate effector genes were ranked using ToppGene and ToppNet, with integrated prioritization via the FLAMES linear scoring algorithm. Results: Pathway enrichment revealed complementary patterns: aging-associated genes were enriched in mitochondrial dysfunction and sarcomere disassembly, while exercise-responsive genes were linked to protein synthesis and lipid metabolism. TTN, PDK family kinases, and EGFR emerged as major upstream regulators. NKX2-5, MYOG, and YBX3 were identified as shared transcription factors. SMPX ranked highest in integrated scoring, showing both functional relevance and network centrality, implying a pivotal role in mechano-metabolic coupling and cardiac stress adaptation. Conclusions: By integrating cardiac aging and exercise-responsive transcriptomes, 37 effector genes were identified as molecular bridges between aging decline and exercise-induced rejuvenation. Aging involved mitochondrial and sarcomeric deterioration, while exercise promoted metabolic and structural remodeling. SMPX ranked highest for its roles in mechano-metabolic coupling and redox balance, with X-inactivation escape suggesting sex-specific relevance. Other top genes (e.g., KLHL31, MYPN, RYR2) form a regulatory network supporting exercise-mediated cardiac protection, offering targets for future validation and therapy. Full article

Hypertrophic cardiomyopathy (HCM) is the most common monogenic heart disease, with an estimated prevalence of 1:600 in the general population, and is associated with significant morbidity. HCM is characterized by left ventricular hypertrophy and interventricular septal thickening due to sarcomere protein gene mutations. The recent emergence of cardiac myosin inhibitors (CMIs), specifically mavacamten and aficamten, has introduced a paradigm shift in HCM management by directly targeting the hypercontractile state of the disease. This review comprehensively discusses the molecular mechanisms of mavacamten and aficamten, highlighting their biochemical similarities and differences from available data. It evaluates their reported efficacy in completed clinical trials, such as reducing left ventricular outflow tract (LVOT) obstruction, improving functional capacity, and enhancing quality of life in HCM. It further provides insight and updates to ongoing trials of both CMIs. Finally, it compares and elaborates on the safety profiles of mavacamten and aficamten, discussing their favorable safety profiles shown in completed studies. In current clinical practice, only mavacamten is approved for use, and clinical insights concerning both CMIs are limited, but encouraging. In summary, cardiac myosin inhibitors are a promising class of disease-modifying drugs for HCM with proven short-term safety and efficacy, but limited data are available to fully determine their long-term effects and efficacy in diverse patient populations. Ongoing research is necessary to further explore and define their role in HCM management. Full article

The hypertrophic cardiomyopathy (HCM) clinical phenotype includes sarcomeric HCM, which is the most common form of inherited cardiomyopathy with a population prevalence of 1:500, and phenocopies such as cardiac amyloidosis and Anderson–Fabry disease, which are considered rare diseases. Identification of cardiac and non-cardiac red flags in the context of multi-organ syndrome, multimodality imaging, including echocardiography, cardiac magnetic resonance, and genetic testing, has a central role in the diagnostic pathway. Identifying the specific disease underlying the hypertrophic phenotype is very important since many disease-modifying therapies are currently available, and phase 3 trials for new treatments have been completed or are ongoing. In particular, many chemotherapy agents (alkylating agents, proteasome inhibitors, immunomodulatory drugs, and monoclonal antibodies targeting clonal cells) allowing one to treat AL amyloidosis, transthyretin stabilizers (tafamidis and acoramidis), and gene silencers (patisiran and vutrisiran) are available in transthyretin cardiac amyloidosis, and enzyme replacement therapies (agalsidase-alpha, agalsidase-beta, and pegunigalsidase-alpha) or oral chaperone therapy (migalastat) can be used in Anderson–Fabry disease. In addition, the introduction of cardiac myosin inhibitors (mavacamten and aficamten) has deeply modified the treatment of hypertrophic obstructive cardiomyopathy. The aim of this review is to describe the new disease-modifying treatments available in HCM and phenocopies in light of current scientific evidence. Full article

Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiomyopathy, caused by either sarcomere protein or other gene mutations. It is a complex and highly heterogeneous disorder, with phenotypes ranging from asymptomatic to severe disease, characterized by asymmetric left ventricular (LV) hypertrophy unexplained by loading conditions, which is also associated with myocardial fiber disarray, and preserved or increased ejection fraction without LV dilation. Comprehensive personal and family history, physical examination, and ECG testing raise suspicion of HCM, and echocardiogram represents the first-line imaging modality for confirming a diagnosis. Moreover, contrast-enhanced cardiac magnetic resonance (CMR) imaging has increasingly emerged as a fundamental diagnostic and prognostic tool in HCM management. This article reviews the role of CMR in HCM identification and differentiation from phenotypic mimics, characterization of HCM phenotypes, monitoring of disease progression, evaluation of pre- and post-septal reduction treatments, and selection of candidates for implantable cardioverter-defibrillator. By providing information on cardiac morphology and function and tissue characterization, CMR is particularly helpful in the quantification of myocardial wall thickness, the detection of hypertrophy in areas blind to echocardiogram, subtle morphologic features in the absence of LV hypertrophy, myocardial fibrosis, and apical aneurysm, the evaluation of LV outflow tract obstruction, and the assessment of LV function in end-stage dilated HCM. Full article

Background/Objectives: Hypertrophic cardiomyopathy (HCM) is a common genetic cardiac disorder marked by abnormal thickening of the left ventricular myocardium, often leading to arrhythmias and heart failure. Mutations in sarcomeric protein genes, particularly MYBPC3, which encodes cardiac myosin-binding protein C (cMyBP-C), are major contributors to HCM pathogenesis. This study aims to investigate the structural and functional effects of two HCM-associated missense mutations, p.S236G and p.E334K, located within the C0–C2 domains of cMyBP-C. Methods: Following in silico analysis, a bacterial expression system was applied, enabling the discrete C0–C2 domains of wild-type (cMyBP-C^WT) and mutant (cMyBP-C^S236G and cMyBP-C^E334K) cMyBP-C proteins to be expressed and purified as recombinant proteins. Structural and stability changes were assessed using circular dichroism (CD), differential scanning calorimetry (DSC), and chemical denaturation assays. Functional impact on actin binding was also evaluated in vitro. Results: CD analysis revealed altered secondary structure in both mutants compared to the wild-type protein. Thermal and chemical stability assays indicated increased stability in the cMyBP-C^E334K mutant, suggesting that it exhibits a more rigid conformation. This increased rigidity corresponded with a significant reduction in the actin-binding affinity relative to the wild-type protein. Conclusions: Our findings demonstrate specific detrimental effects of the p.E334K mutation and underscore the importance of understanding the structural and functional consequences of HCM-associated mutations to assist the development of targeted therapeutic strategies. Full article

Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiovascular condition in the world, affecting around 1 in 500 people. HCM is characterized by ventricular wall thickening, decreased ventricular chamber volume, and diastolic dysfunction. Inherited HCM is most commonly caused by sarcomere gene mutations; however, approximately 50% of patients do not present with a known mutation, highlighting the need for further research into additional pathological mutations. The alpha-B crystallin (CRYAB) mutation CRYAB^R123W was previously identified as a novel sarcomere-independent mutation causing HCM associated with pathological NFAT signaling in the setting of pressure overload. We generated stable H9C2 cell lines expressing FLAG-tagged wild-type and mutant CRYAB, which demonstrated that CRYAB^R123W increases calcineurin activity. Using AlphaFold to predict structural and interaction changes, we generated a model where CRYAB^R123W uniquely binds to the autoinhibitory domain of calcineurin. Co-immunoprecipitation using the CRYAB FLAG tag followed by mass spectrometry showed novel and distinct changes in the protein interaction patterns of CRYAB^R123W. Finally, mouse heart extracts from our wild-type CRYAB and CRYAB^R123W models with and without pressure overload caused by transverse aortic constriction (TAC) were used in global proteomic and phosphoproteomic mass spectrometry analysis, which showed dysregulation in cytoskeletal, metabolomic, cardiac, and immune function. Our data illustrate how CRYAB^R123W drives calcineurin activation and exhibits distinct changes in protein interaction and cellular pathways during the development of HCM and pathological cardiac hypertrophy. Full article

The mechanisms of pathogenesis of hypertrophic cardiomyopathy are associated with mutations in the sarcomere genes of cardiomyocytes and metabolic disorders of the cell, including mitochondrial dysfunction. Mitochondria are characterized by the presence of their own DNA and enzyme complexes involved in oxidative reactions, which cause damage to mitochondrial protein structures and membranes by reactive oxygen species. Mitochondrial dysfunctions can also be associated with mutations in the genes encoding mitochondrial proteins and lead to a violation of protective functions such as mitophagy, mitochondrial fusion, and fission. Mutations in myofibril proteins can negatively affect mitochondria through increased oxidative stress due to an increased need for ATP. Mitochondrial dysfunction is associated with impaired ATP synthesis and cardiac contractility, leading to clinical manifestations of hypertrophic cardiomyopathy. The current review was designed to characterize the role of mitochondria in the pathogenesis of hypertrophic cardiomyopathy based on published data; the search for publications was based on the analysis of articles including the keywords “hypertrophic cardiomyopathy, mitochondria, dysfunction” in the PubMed and Scopus databases up to January 2025. Full article

Background/Objectives: Pediatric hypertrophic cardiomyopathy (HCM) is the most common genetic myocardial disorder in children and a leading cause of sudden cardiac death (SCD) among the young. Its phenotypic variability, driven by incomplete penetrance and variable expressivity, presents significant challenges in diagnosis and clinical management. Methods: In this study, we report a unique case of a 16-month-old female diagnosed with HCM caused by a rare genetic deletion. Molecular analysis was performed using a multigene panel and chromosomal microarray analysis (CMA). Results: Molecular tests identified a 30 kb deletion encompassing the MYH6 and MYH7 genes. These genes are critical components of sarcomeric architecture, with known associations to HCM and other cardiomyopathies. Conclusions: This case underscores the clinical and genetic heterogeneity of HCM, highlighting the importance of considering genomic deletions involving key sarcomeric genes in the diagnostic evaluation. Full article

Background/Objectives: Hypertrophic cardiomyopathy (HCM) is the most common genetic heart disease. The most frequently mutated genes encode proteins of the thick filament of the sarcomere, while mutations in thin-filament genes are rare findings in HCM cohorts. Recent studies have revealed distinct mechanisms of disease development linked to thin-filament mutations, highlighting the need for further investigation into this rare subgroup. Methods: A total of 82 adult patients with sarcomere-positive HCM were enrolled. Baseline characteristics and nearly five years of follow-up data from 15 patients with thin-filament mutations were analyzed and compared with those from 67 patients with thick-filament mutations and findings from other studies. Results: Compared to thick-filament HCM patients, individuals with thin-filament mutations exhibited significantly lower maximum left ventricular wall thickness, as measured by both echocardiography (p = 0.024) and cardiac magnetic resonance (p = 0.006), showed more rapid progression to advanced heart failure (HR = 5.6, p = 0.018), and less often underwent septal reduction therapy (p = 0.025). None of the thin-filament HCM patients experienced malignant arrhythmic events. Conclusions: In adults, thin-filament HCM is associated with a ‘thinner’ phenotype and a more rapid progression to advanced heart failure compared to thick-filament HCM. Data on a higher risk of malignant arrhythmias in thin-filament HCM remain controversial between studies and rather depend on the age of onset and genotype in each particular family. Full article

Cardiomyopathy represents the most important life-limiting condition of Duchenne muscular dystrophy (DMD) patients after the age of 20. Genetic alterations in the DMD gene result in the absence of functional dystrophin protein, leading to skeletal/cardiac muscle impairment. The DMD incidence is one in 5000 live male births. Identifying the genetic background, in addition to DMD disease-causing variants, is one of the unmet needs in understanding the cardiac disease’s pathogenetic mechanisms and its prognostic implications. The clinical scenario is made even more intricate by the difficulty in predicting the onset and progression of cardiomyopathy, as no clear genotype/phenotype correspondence has been found thus far. The evaluation of genes involved in the onset of primary cardiomyopathies could explore the hypothesis that changes in cytoskeletal and sarcomeric protein function are the modulators of ventricular dysfunction in DMD patients. In the last decade, with the advent of next-generation sequencing (NGS) technology, many disease-causing genes and modifiers have been identified. Assessing the genetic origin of the phenotypic variability of the disease in both the onset and progression of cardiomyopathy in DMD would be extremely helpful in managing these patients. This review article aims to spotlight the genetic background associated with Cardiomyopathy in DMD patients toward a more predictive personalized model of care. Full article

Alternative splicing allows a single gene to produce a variety of protein isoforms. Changes in splicing isoform usage characterize virtually every stage of the differentiation process and define the physiological differences between cardiomyocytes with different function, at different stages of development, and pathological function. Recent identification of cardiac splicing factors provided insights into the mechanisms underlying alternative splicing and revealed how these splicing factors impact functional properties of the heart. Alterations of the splicing of sarcomeric genes, cell signaling proteins, and ion channels have been associated with the development of pathological conditions such as cardiomyopathy and arrhythmia. RBM20, RBM24, PTBP1, RBFOX, and QKI play key roles in cardiac development and pathology. A better understanding of their regulation will yield insights into healthy cardiac development and inform the development of molecular therapeutics. Full article

MYBPC3, encoding cardiac myosin binding protein-C (cMyBP-C), is the most mutated gene known to cause hypertrophic cardiomyopathy (HCM). However, since little is known about the underlying etiology, additional in vitro studies are crucial to defining the underlying molecular mechanisms. Accordingly, this study aimed to investigate the molecular mechanisms underlying the pathogenesis of HCM associated with a polymorphic variant (D389V) in MYBPC3 by using isogenic human-induced pluripotent stem cell (hiPSC)-derived cardiac organoids (hCOs). The hiPSC-derived cardiomyocytes (hiPSC-CMs) and hCOs were generated from human subjects to define the molecular, cellular, functional, and energetic changes caused by the MYBPC3^D389V variant, which is associated with increased fractional shortening and highly prevalent in South Asian descendants. Recombinant C0-C2, N’ region of cMyBP-C (wild-type and D389V), and myosin S2 proteins were also utilized to perform binding and motility assays in vitro. Confocal and electron microscopic analyses of hCOs generated from noncarriers (NC) and carriers of the MYBPC3^D389V variant revealed the presence of highly organized sarcomeres. Furthermore, functional experiments showed hypercontractility, faster calcium cycling, and faster contractile kinetics in hCOs expressing MYBPC3^D389V than NC hCOs. Interestingly, significantly increased cMyBP-C phosphorylation in MYBPC3^D389V hCOs was observed, but without changes in total protein levels, in addition to higher oxidative stress and lower mitochondrial membrane potential (ΔΨm). Next, spatial mapping revealed the presence of endothelial cells, fibroblasts, macrophages, immune cells, and cardiomyocytes in the hCOs. The hypercontractile function was significantly improved after the treatment of the myosin inhibitor mavacamten (CAMZYOS^®) in MYBPC3^D389V hCOs. Lastly, various vitro binding assays revealed a significant loss of affinity in the presence of MYBPC3^D389V with myosin S2 region as a likely mechanism for hypercontraction. Conceptually, we showed the feasibility of assessing the functional and molecular mechanisms of HCM using highly translatable hCOs through pragmatic experiments that led to determining the MYBPC3^D389V hypercontractile phenotype, which was rescued by the administration of a myosin inhibitor. Full article