Missense mutations in the rod domain of the lamin A/C gene as causes of dilated cardiomyopathy and conduction-system disease

Naturally occurring canine laminopathy leading to a dilated and fibrosing cardiomyopathy in the Nova Scotia Duck Tolling Retriever

Dilated cardiomyopathy (DCM) is characterized by decreased systolic function and dilation of one or both ventricles, often leading to heart failure or sudden death. Two 10-month-old sibling Nova Scotia Duck Tolling Retrievers (NSDTR) died acutely with evidence of dilated cardiomyopathy with myocardial fibrosis. Association analysis using two cases and 35 controls identified three candidate regions homozygous in the two cases. Whole genome sequencing identified a frameshift deletion in the LMNA gene (NC_049228.1:g.41688530del, NP_001274080:p.(Asp576ThrfsTer124)). Three retrospectively identified NSDTRs with sudden death before 2 years of age and severe myocardial fibrosis were also homozygous for the deletion. One 5 year old with sudden death and myocardial fibrosis was heterozygous for the deletion. This variant was not identified in 722 dogs of other breeds, nor was it identified to be homozygous in 784 NSDTR. LMNA codes for lamin A/C proteins, which are type V intermediate filaments that provide structural support to the nuclear membrane. In humans, LMNA variants can cause DCM with sudden death as well as diseases of striated muscles, lipodystrophy, neuropathies, and accelerated aging disorders. This frameshift deletion is predicted to affect processing of prelamin A into lamin A. Pedigree analysis in the NSDTR and functional evaluation of heterozygotes is consistent with a predominantly recessive mode of inheritance and possibly low penetrance in heterozygotes in contrast to people, where most pathogenic LMNA variants are dominantly inherited.

Systematic in vivo candidate evaluation uncovers therapeutic targets for LMNA dilated cardiomyopathy and risk of Lamin A toxicity

BACKGROUND

Dilated cardiomyopathy (DCM) is a severe, non-ischemic heart disease which ultimately results in heart failure (HF). Decades of research on DCM have revealed diverse aetiologies. Among them, familial DCM is the major form of DCM, with pathogenic variants in LMNA being the second most common form of autosomal dominant DCM. LMNA DCM is a multifactorial and complex disease with no specific treatment thus far. Many studies have demonstrated that perturbing candidates related to various dysregulated pathways ameliorate LMNA DCM. However, it is unknown whether these candidates could serve as potential therapeutic targets especially in long term efficacy.

METHODS

We evaluated 14 potential candidates including Lmna gene products (Lamin A and Lamin C), key signaling pathways (Tgfβ/Smad, mTor and Fgf/Mapk), calcium handling, proliferation regulators and modifiers of LINC complex function in a cardiac specific Lmna DCM model. Positive candidates for improved cardiac function were further assessed by survival analysis. Suppressive roles and mechanisms of these candidates in ameliorating Lmna DCM were dissected by comparing marker gene expression, Tgfβ signaling pathway activation, fibrosis, inflammation, proliferation and DNA damage. Furthermore, transcriptome profiling compared the differences between Lamin A and Lamin C treatment.

RESULTS

Cardiac function was restored by several positive candidates (Smad3, Yy1, Bmp7, Ctgf, aYAP1, Sun1, Lamin A, and Lamin C), which significantly correlated with suppression of HF/fibrosis marker expression and cardiac fibrosis in Lmna DCM. Lamin C or Sun1 shRNA administration achieved consistent, prolonged survival which highly correlated with reduced heart inflammation and DNA damage. Importantly, Lamin A treatment improved but could not reproduce long term survival, and Lamin A administration to healthy hearts itself induced DCM. Mechanistically, we identified this lapse as caused by a dose-dependent toxicity of Lamin A, which was independent from its maturation.

CONCLUSIONS

In vivo candidate evaluation revealed that supplementation of Lamin C or knockdown of Sun1 significantly suppressed Lmna DCM and achieve prolonged survival. Conversely, Lamin A supplementation did not rescue long term survival and may impart detrimental cardiotoxicity risk. This study highlights a potential of advancing Lamin C and Sun1 as therapeutic targets for the treatment of LMNA DCM.

AAV9-mediated SMN gene therapy rescues cardiac desmin but not lamin A/C and elastin dysregulation in Smn2B/- spinal muscular atrophy mice

Structural, functional and molecular cardiac defects have been reported in spinal muscular atrophy (SMA) patients and mouse models. Previous quantitative proteomics analyses demonstrated widespread molecular defects in the severe Taiwanese SMA mouse model. Whether such changes are conserved across different mouse models, including less severe forms of the disease, has yet to be established. Here, using the same high-resolution proteomics approach in the less-severe Smn2B/- SMA mouse model, 277 proteins were found to be differentially abundant at a symptomatic timepoint (post-natal day (P) 18), 50 of which were similarly dysregulated in severe Taiwanese SMA mice. Bioinformatics analysis linked many of the differentially abundant proteins to cardiovascular development and function, with intermediate filaments highlighted as an enriched cellular compartment in both datasets. Lamin A/C was increased in the cardiac tissue, whereas another intermediate filament protein, desmin, was reduced. The extracellular matrix (ECM) protein, elastin, was also robustly decreased in the heart of Smn2B/- mice. AAV9-SMN1-mediated gene therapy rectified low levels of survival motor neuron protein and restored desmin levels in heart tissues of Smn2B/- mice. In contrast, AAV9-SMN1 therapy failed to correct lamin A/C or elastin levels. Intermediate filament proteins and the ECM have key roles in cardiac function and their dysregulation may explain cardiac impairment in SMA, especially since mutations in genes encoding these proteins cause other diseases with cardiac aberration. Cardiac pathology may need to be considered in the long-term care of SMA patients, as it is unclear whether currently available treatments can fully rescue peripheral pathology in SMA.

Hutchinson-Gilford progeria patient-derived cardiomyocyte model of carrying LMNA gene variant c.1824 C > T

Cardiovascular diseases, atherosclerosis, and strokes are the most common causes of death in patients with Hutchinson-Gilford progeria syndrome (HGPS). The LMNA variant c.1824C > T accounts for ~ 90% of HGPS cases. The detailed molecular mechanisms of Lamin A in the heart remain elusive due to the lack of appropriate in vitro models. We hypothesize that HGPS patient's induced pluripotent stem cell (iPSC)-derived cardiomyocytes (iCMCs) will provide a model platform to study the cardio-pathologic mechanisms associated with HGPS. To elucidate the effects of progerin in cardiomyocytes, we first obtained skin fibroblasts (SFs) from a de-identified HGPS patient (hPGP1, proband) and both parents from the Progeria Research Foundation. Through Sanger sequencing and restriction fragment length polymorphism, with the enzyme EciI, targeting Lamin A, we characterized hPGP1-SFs as heterozygous mutants for the LMNA variant c.1824 C > T. Additionally, we performed LMNA exon 11 bisulfite sequencing to analyze the methylation status of the progeria cells. Furthermore, we reprogrammed the three SFs into iPSCs and differentiated them into iCMCs, which gained a beating on day 7. Through particle image velocimetry analysis, we found that hPGP1-iCMCs had an irregular contractile function and decreased cardiac-specific gene and protein expressions by qRT-PCR and Western blot. Our progeria-patient-derived iCMCs were found to be functionally and structurally defective when compared to normal iCMCs. This in vitro model will help in elucidating the role of Lamin A in cardiac diseases and the cardio-pathologic mechanisms associated with progeria. It provides a new platform for researchers to study novel treatment approaches for progeria-associated cardiac diseases.

Mechanism of COVID-19-Induced Cardiac Damage from Patient, In Vitro and Animal Studies

PURPOSE OF REVIEW

Though patient studies have been important for understanding the disease, research done in animals and cell culture complement our knowledge from patient data and provide insight into the mechanism of the disease. Understanding how COVID causes damage to the heart is essential to understanding possible long-term consequences.

RECENT FINDINGS

COVID-19 is primarily a disease that attacks the lungs; however, it is known to have important consequences in many other tissues including the heart. Though myocarditis does occur in some patients, for most cases of cardiac damage, the injury arises from scarring either due to myocardial infarction or micro-infarction. The main focus is on how COVID affects blood flow through the coronaries. We review how endothelial activation leads to a hypercoagulative state in COVID-19. We also emphasize the effects that the cytokine storm can directly have on the regulation of coronary blood flow. Since the main two cell types that can be infected in the heart are pericytes and cardiomyocytes, we further describe the known effects on pericyte function and how that can further lead to microinfarcts within the heart. Though many of these effects are systemic, this review focuses on the consequences on cardiac tissue of this dysregulation and the role that it has in the formation of myocardial scarring.

Cardiomyopathy in Asian Cohorts: Genetic and Epigenetic Insights

Previous studies on cardiomyopathies have been particularly valuable for clarifying pathological mechanisms in heart failure, an etiologically heterogeneous disease. In this review, we specifically focus on cardiomyopathies in Asia, where heart failure is particularly pertinent. There has been an increase in prevalence of cardiomyopathies in Asia, in sharp contrast with the decline observed in Western countries. Indeed, important disparities in cardiomyopathy incidence, clinical characteristics, and prognosis have been reported in Asian versus White cohorts. These have been accompanied by emerging descriptions of a distinct rare and common genetic basis for disease among Asian cardiomyopathy patients marked by an increased burden of variants with uncertain significance, reclassification of variants deemed pathogenic based on evidence from predominantly White cohorts, and the discovery of Asian-specific cardiomyopathy-associated loci with underappreciated pathogenicity under conventional classification criteria. Findings from epigenetic studies of heart failure, particularly DNA methylation studies, have complemented genetic findings in accounting for the phenotypic variability in cardiomyopathy. Though extremely limited, findings from Asian ancestry-focused DNA methylation studies of cardiomyopathy have shown potential to contribute to general understanding of cardiomyopathy pathophysiology by proposing disease and cause-relevant pathophysiological mechanisms. We discuss the value of multiomics study designs incorporating genetic, methylation, and transcriptomic information for future DNA methylation studies in Asian cardiomyopathy cohorts to yield Asian ancestry-specific insights that will improve risk stratification in the Asian population.

Phenotyping heart failure by genetics and associated conditions

Heart failure is a highly heterogeneous disease, and genetic testing may allow phenotypic distinctions that are incremental to those obtainable from imaging. Advances in genetic testing have allowed for the identification of deleterious variants in patients with specific heart failure phenotypes (dilated cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, and hypertrophic cardiomyopathy), and many of these have specific treatment implications. The diagnostic yield of genetic testing in heart failure is modest, and many rare variants are associated with incomplete penetrance and variable expressivity. Environmental factors and co-morbidities have a large role in the heterogeneity of the heart failure phenotype. Future endeavours should concentrate on the cumulative impact of genetic polymorphisms in the development of heart failure.

Multi-omic analysis of mandibuloacral dysplasia type A patient iPSC-derived MSC senescence reveals miR-311 as a novel biomarker for MSC senescence

Mandibuloacral dysplasia type A (MADA) is a rare genetic progeroid syndrome associated with lamin A/C (LMNA) mutations. Pathogenic mutations of LMNA result in nuclear structural abnormalities, mesenchymal tissue damage and progeria phenotypes. However, it remains elusive how LMNA mutations cause mesenchymal-derived cell senescence and disease development. Here, we established an in vitro senescence model using induced pluripotent stem cell-derived mesenchymal stem cells (iMSCs) from MADA patients with homozygous LMNA p.R527C mutation. When expanded to passage 13 in vitro, R527C iMSCs exhibited marked senescence and attenuation of stemness potential, accompanied by immunophenotypic changes. Transcriptome and proteome analysis revealed that cell cycle, DNA replication, cell adhesion and inflammation might play important roles in senescence. In-depth evaluation of changes in extracellular vesicle (EV) derived iMSCs during senescence revealed that R527C iMSC-EVs could promote surrounding cell senescence by carrying pro-senescence microRNAs (miRNAs), including a novel miRNA called miR-311, which can serve as a new indicator for detecting chronic and acute mesenchymal stem cell (MSC) senescence and play a role in promoting senescence. Overall, this study advanced our understanding of the impact of LMNA mutations on MSC senescence and provided novel insights into MADA therapy as well as the link between chronic inflammation and aging development.

The Genetic Evaluation of Dilated Cardiomyopathy

Dilated cardiomyopathy (DCM) is a common cause of heart failure and is the primary indication for heart transplantation. A genetic etiology can be found in 20-35% of patients with DCM, especially in those with a family history of cardiomyopathy or sudden cardiac death at an early age. With advancements in genome sequencing, the understanding of genotype-phenotype relationships in DCM has expanded with over 60 genes implicated in the disease. Subsequently, these findings have increased adoption of genetic testing in the management of DCM, which has allowed for improved risk stratification and identification of at risk family members. In this review, we discuss the genetic evaluation of DCM with a focus on practical genetic testing considerations, genotype-phenotype associations, and insights into upcoming personalized therapies.

Genetic Risk Stratification in Arrhythmogenic Left Ventricular Cardiomyopathy

Arrhythmogenic left ventricular cardiomyopathy is characterized by early malignant ventricular arrhythmia associated with varying degrees and times of onset of left ventricular dysfunction. Variants in numerous genes have been associated with this phenotype. Here, the authors review the literature on recent cohort studies of patients with variants in desmoplakin, lamin A/C, filamin-C, phospholamban, RBM20, TMEM43, and selected channelopathy genes also associated with structural disease. Unlike traditional sudden cardiac death risk assessment in nonischemic cardiomyopathy, left ventricular systolic function is an insensitive predictor of risk in patients with these genetic diagnoses.

From gene-discovery to gene-tailored clinical management: 25 years of research in channelopathies and cardiomyopathies

In the early nineties, few years before the birth of Europace, the clinical and scientific world of familial arrhythmogenic conditions was revolutionized by the identification of the first disease-causing genes. The explosion of genetic studies over a 15-year period led to the discovery of major disease-causing genes in practically all channelopathies and cardiomyopathies, bringing insight into the pathophysiological mechanisms of these conditions. The birth of next generation sequencing allowed a further step forward and other significant genes, as CALM1-3 in channelopathies and FLN C and TTN in cardiomyopathies were identified. Genotype-phenotype studies allowed the implementation of the genetic results in diagnosis, risk stratification, and therapeutic management with a different level of evidence in different arrhythmogenic conditions. The influence of common genetic variants, i.e. SNPs, on disease manifestation was proved in mid-twenties, and in the last 10 years with the advent of genome-wide association studies performed in familial arrhythmogenic diseases, the concept of polygenic risk score has been consolidated. Now, we are at the start of another amazing phase, i.e. the initiation of first gene therapy clinical trials.

Caenorhabditis elegans models for striated muscle disorders caused by missense variants of human LMNA

Striated muscle laminopathies caused by missense mutations in the nuclear lamin gene LMNA are characterized by cardiac dysfunction and often skeletal muscle defects. Attempts to predict which LMNA variants are pathogenic and to understand their physiological effects lag behind variant discovery. We created Caenorhabditis elegans models for striated muscle laminopathies by introducing pathogenic human LMNA variants and variants of unknown significance at conserved residues within the lmn-1 gene. Severe missense variants reduced fertility and/or motility in C. elegans. Nuclear morphology defects were evident in the hypodermal nuclei of many lamin variant strains, indicating a loss of nuclear envelope integrity. Phenotypic severity varied within the two classes of missense mutations involved in striated muscle disease, but overall, variants associated with both skeletal and cardiac muscle defects in humans lead to more severe phenotypes in our model than variants predicted to disrupt cardiac function alone. We also identified a separation of function allele, lmn-1(R204W), that exhibited normal viability and swimming behavior but had a severe nuclear migration defect. Thus, we established C. elegans avatars for striated muscle laminopathies and identified LMNA variants that offer insight into lamin mechanisms during normal development.

Nuclear proteostasis imbalance in laminopathy-associated premature aging diseases

Laminopathies are a group of rare genetic disorders with heterogeneous clinical phenotypes such as premature aging, cardiomyopathy, lipodystrophy, muscular dystrophy, microcephaly, epilepsy, and so on. The cellular phenomena associated with laminopathy invariably show disruption of nucleoskeleton of lamina due to deregulated expression, localization, function, and interaction of mutant lamin proteins. Impaired spatial and temporal tethering of lamin proteins to the lamina or nucleoplasmic aggregation of lamins are the primary molecular events that can trigger nuclear proteotoxicity by modulating differential protein-protein interactions, sequestering quality control proteins, and initiating a cascade of abnormal post-translational modifications. Clearly, laminopathic cells exhibit moderate to high nuclear proteotoxicity, raising the question of whether an imbalance in nuclear proteostasis is involved in laminopathic diseases, particularly in diseases of early aging such as HGPS and laminopathy-associated premature aging. Here, we review nuclear proteostasis and its deregulation in the context of lamin proteins and laminopathies.

Genetic Abnormalities of the Sinoatrial Node and Atrioventricular Conduction

The peculiar electrophysiological properties of the sinoatrial node and the cardiac conduction system are key components of the normal physiology of cardiac impulse generation and propagation. Multiple genes and transcription factors and metabolic proteins are involved in their development and regulation. In this review, we have summarized the genetic underlying causes, key clinical findings, and the latest available clinical evidence. We will discuss clinical diagnosis and management of the genetic conditions associated with conduction disorders that are more prevalent in clinical practice, for this reason, very rare genetic diseases presenting sinus node or cardiac conduction system abnormalities are not discussed.

Lamin A/C cardiomyopathy presenting as high-grade atrioventricular (AV) block, atrial fibrillation, heart failure and ventricular tachycardia in a single-family cluster

Mutations in the lamin A/C (LMNA) gene have been associated with both cardiac and skeletal muscle abnormalities. Cardiac manifestations in LMNA cardiomyopathy have a variable age of onset and range from mild to life-threatening. We describe a case series illustrating manifestations of LMNA mutation in a single family with an extensive history of cardiac disease, including sudden cardiac death, and the implications for diagnosis and management. This discussion highlights potential presentations of LMNA mutations and the importance of genetic testing in patients with a family history of conduction abnormalities.

Overview of cellular homeostasis-associated nuclear envelope lamins and associated input signals

With the discovery of the role of the nuclear envelope protein lamin in human genetic diseases, further diverse roles of lamins have been elucidated. The roles of lamins have been addressed in cellular homeostasis including gene regulation, cell cycle, cellular senescence, adipogenesis, bone remodeling as well as modulation of cancer biology. Features of laminopathies line with oxidative stress-associated cellular senescence, differentiation, and longevity and share with downstream of aging-oxidative stress. Thus, in this review, we highlighted various roles of lamin as key molecule of nuclear maintenance, specially lamin-A/C, and mutated LMNA gene clearly reveal aging-related genetic phenotypes, such as enhanced differentiation, adipogenesis, and osteoporosis. The modulatory roles of lamin-A/C in stem cell differentiation, skin, cardiac regulation, and oncology have also been elucidated. In addition to recent advances in laminopathies, we highlighted for the first kinase-dependent nuclear lamin biology and recently developed modulatory mechanisms or effector signals of lamin regulation. Advanced knowledge of the lamin-A/C proteins as diverse signaling modulators might be biological key to unlocking the complex signaling of aging-related human diseases and homeostasis in cellular process.

Novel Phenotype of LMNA Variant c.154C>G Affecting Heart, Liver, and Lipid and Iron Metabolism: A Case Report

Mutations in the LMNA gene cause heterogeneous phenotypes such as myopathy, progeroid syndromes, hereditary neuropathies, cardiomyopathies, or lipodystrophies. A specific LMNA mutation manifesting as dilated cardiomyopathy (dCMP), and iron metabolism disorder has not been reported. The patient is a 50-year-old female with palpitations and fatigue since childhood, hyperlipidemia for 25 years, gastroesophageal reflux for 20 years, arterial hypertension for eight years, and iron deficiency for one year, requiring intravenous iron supplementation. Family history was positive for dCMP, malignant ventricular arrhythmias (MVAs), and sudden cardiac death (SCD). She was diagnosed with dCMP at the age of 49. Genetic workup revealed the variant c.154C>G (p.Leu52Val) in LMNA, which was also found in two female cousins. Because of ventricular tachycardia in the long-term ECG recordings, an implantable cardioverter-defibrillator (ICD) was implanted in addition to antiarrhythmic, antihypertensive, heart failure, and lipid-lowering treatment. With this therapy, the patient remained in stable condition during the one-year follow-up and was able to successfully carry out her job. In summary, this case shows that the variant c.154C>G (p.Leu52Val) in LMNA manifests not only with dCMP, but also with hyperlipidemia, steatosis, gastroesophageal reflux, arterial hypertension, and iron deficiency. Primary prophylaxis with an ICD and additional symptomatic treatment can stabilise the condition and eventually prevent familial SCD.

TEAD1 trapping by the Q353R-Lamin A/C causes dilated cardiomyopathy

Mutations in the LMNA gene encoding Lamin A and C (Lamin A/C), major components of the nuclear lamina, cause laminopathies including dilated cardiomyopathy (DCM), but the underlying molecular mechanisms have not been fully elucidated. Here, by leveraging single-cell RNA sequencing (RNA-seq), assay for transposase-accessible chromatin using sequencing (ATAC-seq), protein array, and electron microscopy analysis, we show that insufficient structural maturation of cardiomyocytes owing to trapping of transcription factor TEA domain transcription factor 1 (TEAD1) by mutant Lamin A/C at the nuclear membrane underlies the pathogenesis of Q353R-LMNA-related DCM. Inhibition of the Hippo pathway rescued the dysregulation of cardiac developmental genes by TEAD1 in LMNA mutant cardiomyocytes. Single-cell RNA-seq of cardiac tissues from patients with DCM with the LMNA mutation confirmed the dysregulated expression of TEAD1 target genes. Our results propose an intervention for transcriptional dysregulation as a potential treatment of LMNA-related DCM.

A Case of Cardiogenic Stroke With a Novel LMNA Variant (c. 1135C>A; p.Leu379Ile)

Laminopathy is muscular dystrophy caused by an LMNA gene mutation. It is characterized by cardiac disease such as atrial fibrillation. We report a case of laminopathy in a 49-year-old woman who presented with cardiogenic stroke. She had experienced weakness in her limb-girdle muscles since childhood, atrial fibrillation, cardiomyopathy, and mild contracture of the ankle joints, and had a familial history of heart disease. Gene analysis identified a novel heterozygous variant, c. 1135C>A (p.Leu379Ile), in the LMNA gene. Laminopathy can be an underlying disease in ischemic stroke, especially in young to middle age.

Nuclear Calcium in Cardiac (Patho)Physiology: Small Compartment, Big Impact

The nucleus of a cardiomyocyte has been increasingly recognized as a morphologically distinct and partially independent calcium (Ca²⁺) signaling microdomain, with its own Ca²⁺-regulatory mechanisms and important effects on cardiac gene expression. In this review, we (1) provide a comprehensive overview of the current state of research on the dynamics and regulation of nuclear Ca²⁺ signaling in cardiomyocytes, (2) address the role of nuclear Ca²⁺ in the development and progression of cardiac pathologies, such as heart failure and atrial fibrillation, and (3) discuss novel aspects of experimental methods to investigate nuclear Ca²⁺ handling and its downstream effects in the heart. Finally, we highlight current challenges and limitations and recommend future directions for addressing key open questions.

Epigenetics in LMNA-Related Cardiomyopathy

Mutations in the gene for lamin A/C (LMNA) cause a diverse range of diseases known as laminopathies. LMNA-related cardiomyopathy is a common inherited heart disease and is highly penetrant with a poor prognosis. In the past years, numerous investigations using mouse models, stem cell technologies, and patient samples have characterized the phenotypic diversity caused by specific LMNA variants and contributed to understanding the molecular mechanisms underlying the pathogenesis of heart disease. As a component of the nuclear envelope, LMNA regulates nuclear mechanostability and function, chromatin organization, and gene transcription. This review will focus on the different cardiomyopathies caused by LMNA mutations, address the role of LMNA in chromatin organization and gene regulation, and discuss how these processes go awry in heart disease.

Cytological Samples: An Asset for the Diagnosis and Therapeutic Management of Patients with Lung Cancer

BACKGROUND

Lung cancer has become the leading cause of cancer death for men and women. Most patients are diagnosed at an advanced stage when surgery is no longer a therapeutic option. At this stage, cytological samples are often the less invasive source for diagnosis and the determination of predictive markers. We assessed the ability of cytological samples to perform diagnosis, and to establish molecular profile and PD-L1 expression, which are essential for the therapeutic management of patients.

METHODS

We included 259 cytological samples with suspected tumor cells and assessed the ability to confirm the type of malignancy by immunocytochemistry. We summarized results of molecular testing by next generation sequencing (NGS) and PD-L1 expression from these samples. Finally, we analyzed the impact of these results in the patient management.

RESULTS

Among the 259 cytological samples, 189 concerned lung cancers. Of these, immunocytochemistry confirmed the diagnosis in 95%. Molecular testing by NGS was obtained in 93% of lung adenocarcinomas and non-small cell lung cancer. PD-L1 results were obtained in 75% of patients tested. The results obtained with cytological samples led to a therapeutic decision in 87% of patients.

CONCLUSION

Cytological samples are obtained by minimally invasive procedures and can provide enough material for the diagnosis and therapeutic management in lung cancer patients.

Inhibitory Activity of Saussurea costus Extract against Bacteria, Candida, Herpes, and SARS-CoV-2

Medicinal herbs have long been utilized to treat various diseases or to relieve the symptoms of some ailments for extended periods. The present investigation demonstrates the phytochemical profile, molecular docking, anti-Candida activity, and anti-viral activity of the Saussurea costus acetic acid extract. GC-MS analysis of the extract revealed the presence of 69 chemical compounds. The chemical compounds were alkaloids (4%), terpenoids (79%), phenolic compounds (4%), hydrocarbons (7%), and sterols (6%). Molecular docking was used to study the inhibitory activity of 69 identified compounds against SARS-CoV-2. In total, 12 out of 69 compounds were found to have active properties exhibiting SARS-CoV-2 inhibition. The binding scores of these molecules were significantly low, ranging from -7.8 to -5.6 kcal/mol. The interaction of oxatricyclo [20.8.0.0(7,16)] triaconta-1(22),7(16),9,13,23,29-hexaene with the active site is more efficient. Furthermore, the extract exhibited significant antimicrobial activity (in vitro) against Candida albicans, which was the most susceptible microorganism, followed by Bacillus cereus, Salmonella enterica, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa, respectively. On the other hand, its antiviral activity was evaluated against HSV-1 and SARS-CoV-2, and the results showed a significant positive influence against HSV-1 (EC₅₀ = 82.6 g/mL; CC₅₀ = 162.9 g/mL; selectivity index = 1.9). In spite of this, no impact could be observed in terms of inhibiting the entry of SARS-CoV-2 in vitro.

Actin-microtubule cytoskeletal interplay mediated by MRTF-A/SRF signaling promotes dilated cardiomyopathy caused by LMNA mutations

Mutations in the lamin A/C gene (LMNA) cause dilated cardiomyopathy associated with increased activity of ERK1/2 in the heart. We recently showed that ERK1/2 phosphorylates cofilin-1 on threonine 25 (phospho(T25)-cofilin-1) that in turn disassembles the actin cytoskeleton. Here, we show that in muscle cells carrying a cardiomyopathy-causing LMNA mutation, phospho(T25)-cofilin-1 binds to myocardin-related transcription factor A (MRTF-A) in the cytoplasm, thus preventing the stimulation of serum response factor (SRF) in the nucleus. Inhibiting the MRTF-A/SRF axis leads to decreased α-tubulin acetylation by reducing the expression of ATAT1 gene encoding α-tubulin acetyltransferase 1. Hence, tubulin acetylation is decreased in cardiomyocytes derived from male patients with LMNA mutations and in heart and isolated cardiomyocytes from Lmna^{p.H222P/H222P} male mice. In Atat1 knockout mice, deficient for acetylated α-tubulin, we observe left ventricular dilation and mislocalization of Connexin 43 (Cx43) in heart. Increasing α-tubulin acetylation levels in Lmna^{p.H222P/H222P} mice with tubastatin A treatment restores the proper localization of Cx43 and improves cardiac function. In summary, we show for the first time an actin-microtubule cytoskeletal interplay mediated by cofilin-1 and MRTF-A/SRF, promoting the dilated cardiomyopathy caused by LMNA mutations. Our findings suggest that modulating α-tubulin acetylation levels is a feasible strategy for improving cardiac function.

Integrated analysis of WGCNA and machine learning identified diagnostic biomarkers in dilated cardiomyopathy with heart failure

The etiologies and pathogenesis of dilated cardiomyopathy (DCM) with heart failure (HF) remain to be defined. Thus, exploring specific diagnosis biomarkers and mechanisms is urgently needed to improve this situation. In this study, three gene expression profiling datasets (GSE29819, GSE21610, GSE17800) and one single-cell RNA sequencing dataset (GSE95140) were obtained from the Gene Expression Omnibus (GEO) database. GSE29819 and GSE21610 were combined into the training group, while GSE17800 was the test group. We used the weighted gene co-expression network analysis (WGCNA) and identified fifteen driver genes highly associated with DCM with HF in the module. We performed the least absolute shrinkage and selection operator (LASSO) on the driver genes and then constructed five machine learning classifiers (random forest, gradient boosting machine, neural network, eXtreme gradient boosting, and support vector machine). Random forest was the best-performing classifier established on five Lasso-selected genes, which was utilized to select out NPPA, OMD, and PRELP for diagnosing DCM with HF. Moreover, we observed the up-regulation mRNA levels and robust diagnostic accuracies of NPPA, OMD, and PRELP in the training group and test group. Single-cell RNA-seq analysis further demonstrated their stable up-regulation expression patterns in various cardiomyocytes of DCM patients. Besides, through gene set enrichment analysis (GSEA), we found TGF-β signaling pathway, correlated with NPPA, OMD, and PRELP, was the underlying mechanism of DCM with HF. Overall, our study revealed NPPA, OMD, and PRELP serving as diagnostic biomarkers for DCM with HF, deepening the understanding of its pathogenesis.

Describing the natural history of clinical, biochemical and radiological outcomes of children with familial partial lipodystrophy type 2 (FPLD2) from the United Kingdom: A retrospective case series

CONTEXT

Familial partial lipodystrophy type 2 (FPLD2) results from autosomal dominant mutations in the LMNA gene, causing lack of subcutaneous fat deposition and excess ectopic fat accumulation, leading to metabolic complications and reduced life expectancy. The rarity of the condition means that the natural history of FPLD2 throughout childhood is not well understood. We report outcomes in a cohort of 12 (5M) children with a genetic diagnosis of FPLD2, under the care of the UK National Severe Insulin Resistance Service (NSIRS) which offers multidisciplinary input including dietetic, in addition to screening for comorbidities.

OBJECTIVE

To describe the natural history of clinical, biochemical and radiological outcomes of children with FPLD2.

DESIGN

A retrospective case note review of children with a genetic diagnosis of FPLD2 who had been seen in the paediatric NSIRS was performed.

PATIENTS

Twelve (5M) individuals diagnosed with FPLD2 via genetic testing before age 18 and who attended the NSIRS clinic were included.

MEASUREMENTS

Relationships between metabolic variables (HbA1c, triglycerides, fasting insulin, fasting glucose and alanine transaminase [ALT]) across time, from first visit to most recent, were explored using a multivariate model, adjusted for age and gender. The age of development of comorbidities was recorded.

RESULTS

Three patients (all female) developed diabetes between 12 and 19 years and were treated with Metformin. One female has hypertrophic cardiomyopathy and four (1M) patients developed mild hepatic steatosis at a median [range] age of 14(12-15) years. Three (1M) patients reported mental health problems related to lipodystrophy. There was no relationship between biochemical results and age. Patients with diabetes had higher concentrations of ALT than patients who did not have diabetes, adjusted for age, gender and body mass index standard deviation scores.

CONCLUSIONS

Despite dietetic input, some patients, more commonly females, developed comorbidities after the age of 10. The absence of relationships between biochemical results and age likely reflects a small cohort size. We propose that, while clinical review and dietetic support are beneficial for children with FPLD2, formal screening for comorbidities before age 10 may not be of benefit. Clinical input from an multidisciplinary team including dietician, psychologist and clinician should be offered after diagnosis.

Genetic Ablation of the DNA Damage Response Pathway Attenuates Lamin-Associated Dilated Cardiomyopathy in Mice

Hereditary dilated cardiomyopathy (DCM) is a primary disease of cardiac myocytes caused by mutations in genes encoding proteins with a diverse array of functions. Mutations in the LMNA gene, encoding the nuclear envelope protein lamin A/C, are the second most common causes of DCM. The phenotype is characterized by progressive cardiac dysfunction, leading to refractory heart failure, myocardial fibrosis, cardiac arrhythmias, and sudden cardiac death. The molecular pathogenesis of DCM caused by the LMNA mutations is not well known. The LMNA protein is involved in nuclear membrane stability. It is also a guardian of the genome involved in the processing of the topoisomerases at the transcriptionally active domain and the repair of double-stranded DNA breaks (DSBs). Deletion of the mouse Lmna gene in cardiac myocytes leads to premature death, DCM, myocardial fibrosis, and apoptosis. The phenotype is associated with increased expression of the cytosolic DNA sensor cyclic GMP-AMP synthase (CGAS) and activation of the DNA damage response (DDR) pathway. Genetic blockade of the DDR pathway, upon knockout of the Mb21d1 gene encoding CGAS, prolonged survival, improved cardiac function, partially restored levels of molecular markers of heart failure, and attenuated myocardial apoptosis and fibrosis in the LMNA-deficient mice. The findings indicate that targeting the CGAS/DDR pathway might be beneficial in the treatment of DCM caused by mutations in the LMNA gene.

Slower diffusion and anomalous association of R453W lamin A protein alter nuclear architecture in AD-EDMD

Lamins maintain the shape and rigidity of the nucleus in the form of a proteinaceous scaffold underneath the inner nuclear membrane (INM) and provide anchorage to chromatin and other nuclear proteins. Mutations in the human LMNA gene encoding lamin A/C cause about 16 different diseases with distinct phenotypes collectively termed as laminopathies which affect primarily the muscle tissues as well as adipose tissues, neuromuscular junctions and multiple other organs in progeroid syndromes. Lamins contain several domains of which Ig-fold is one of the well characterized and structured domains that harbours many mutations leading to deleterious interactions with other nuclear proteins. In this work, we have elucidated the effects of 3 such mutations namely R453W, W498C and W498R on the dynamics and flexibility of the Ig-fold domain and the consequent effect on the assembly into lamina by live cell imaging, fluorescence correlation spectroscopy (FCS) and molecular dynamics (MD) simulations. From our simulation studies, we concluded that R453W exhibits the highest fluctuation at the residues 475 and 525 in the Ig fold domain compared to the wild type and other mutants. This resulted in pronounced random self-association which could be corroborated by lower diffusivity values obtained from FCS. This is the first report where such an alteration in the full length has been documented by gross changes in diffusional properties as a sequel to a mutation in the Ig fold domain.

Genotype-phenotype Correlates in Arrhythmogenic Cardiomyopathies

PURPOSE OF THE REVIEW

The definition of arrhythmogenic cardiomyopathy (ACM) has expanded beyond desmosomal arrhythmogenic right ventricular cardiomyopathy (ARVC) to include other genetic cardiomyopathies with a significant arrhythmia burden. Emerging data on genotype-phenotype correlations has led recent consensus guidelines to urge genetic testing as a critical component of not only diagnosis but also management of ACM.

RECENT FINDINGS

Plakophilin-2 (PKP2) ARVC/ACM is most likely to meet ARVC Task Force Criteria with right sided involvement and ventricular arrhythmias, while desmoplakin (DSP) ACM may have a normal electrocardiogram (ECG) and has a subepicardial LV scar pattern. Extra-desmosomal ACM including ACM associated with transmembrane protein 43 and phospholamban variants may have characteristic ECG patterns and biventricular cardiomyopathy. Lamin A/C and SCN5A cardiomyopathy often have heart block on ECG with DCM, but are distinct from DCM in that they have significantly elevated arrhythmic risk. Newer genes, especially filamin-C (FLNC) also may have distinct imaging scar patterns, arrhythmia risk, and risk predictors. Recognition of these key differences have implications for clinical management and reinforce the importance of genetic testing in the diagnosis and the emerging opportunities for genotype-specific management of ACM patients.

The E262K mutation in Lamin A links nuclear proteostasis imbalance to laminopathy-associated premature aging

Deleterious, mostly de novo, mutations in the lamin A (LMNA) gene cause spatio-functional nuclear abnormalities that result in several laminopathy-associated progeroid conditions. In this study, exome sequencing in a sixteen-year-old male with manifestations of premature aging led to the identification of a mutation, c.784G>A, in LMNA, resulting in a missense protein variant, p.Glu262Lys (E262K), that aggregates in nucleoplasm. While bioinformatic analyses reveal the instability and pathogenicity of LMNAE262K , local unfolding of the mutation-harboring helical region drives the structural collapse of LMNAE262K into aggregates. The E262K mutation also disrupts SUMOylation of lysine residues by preventing UBE2I binding to LMNAE262K , thereby reducing LMNAE262K degradation, aggregated LMNAE262K sequesters nuclear chaperones, proteasomal proteins, and DNA repair proteins. Consequently, aggregates of LMNAE262K disrupt nuclear proteostasis and DNA repair response. Thus, we report a structure-function association of mutant LMNAE262K with toxicity, which is consistent with the concept that loss of nuclear proteostasis causes early aging in laminopathies.

Biology of myocardial recovery in advanced heart failure with long-term mechanical support

Cardiac remodeling is an adaptive, compensatory biological process following an initial insult to the myocardium that gradually becomes maladaptive and causes clinical deterioration and chronic heart failure (HF). This biological process involves several pathophysiological adaptations at the genetic, molecular, cellular, and tissue levels. A growing body of clinical and translational investigations demonstrated that cardiac remodeling and chronic HF does not invariably result in a static, end-stage phenotype but can be at least partially reversed. One of the paradigms which shed some additional light on the breadth and limits of myocardial elasticity and plasticity is long term mechanical circulatory support (MCS) in advanced HF pediatric and adult patients. MCS by providing (a) ventricular mechanical unloading and (b) effective hemodynamic support to the periphery results in functional, structural, cellular and molecular changes, known as cardiac reverse remodeling. Herein, we analyze and synthesize the advances in our understanding of the biology of MCS-mediated reverse remodeling and myocardial recovery. The MCS investigational setting offers access to human tissue, providing an unparalleled opportunity in cardiovascular medicine to perform in-depth characterizations of myocardial biology and the associated molecular, cellular, and structural recovery signatures. These human tissue findings have triggered and effectively fueled a "bedside to bench and back" approach through a variety of knockout, inhibition or overexpression mechanistic investigations in vitro and in vivo using small animal models. These follow-up translational and basic science studies leveraging human tissue findings have unveiled mechanistic myocardial recovery pathways which are currently undergoing further testing for potential therapeutic drug development. Essentially, the field is advancing by extending the lessons learned from the MCS cardiac recovery investigational setting to develop therapies applicable to the greater, not end-stage, HF population. This review article focuses on the biological aspects of the MCS-mediated myocardial recovery and together with its companion review article, focused on the clinical aspects, they aim to provide a useful framework for clinicians and investigators.

Identification and functional characterization of BICD2 as a candidate disease gene in an consanguineous family with dilated cardiomyopathy

Background

Familial dilated cardiomyopathy (DCM) is a genetic cardiomyopathy that is associated with reduced left ventricle function or systolic function. Fifty-one DCM-causative genes have been reported, most of which are inherited in an autosomal dominant manner. However, recessive DCM-causative gene is rarely observed.

Methods

Whole-exome sequencing (WES) was performed in a consanguineous family with DCM to identify candidate variants. Sanger sequencing was utilized to confirm the variant. We then checked the DCM candidate gene in 210 sporadic DCM cases. We next explored BICD2 function in both embryonic and adult bicd2-knockout zebrafish models. In vivo cardiac function of bicd2-knockout fish was detected by echocardiography and RNA-seq.

Results

We identified an autosomal recessive and evolutionarily conserved missense variant, NM_001003800.1:c.2429G > A, in BICD2, which segregated with the disease phenotype in a consanguineous family with DCM. Furthermore, we confirmed the presence of BICD2 variants in 3 sporadic cases. Knockout of bicd2 resulted in partial embryonic lethality in homozygotes, suggesting a vital role for bicd2 in embryogenesis. Heart dilation and decreased ejection fraction, cardiac output and stroke volume were observed in bicd2-knockout zebrafish, suggesting a phenotype similar to human DCM. Furthermore, RNA-seq confirmed a larger transcriptome shift in in bicd2 homozygotes than in heterozygotes. Gene set enrichment analysis of bicd2-deficient fish showed the enrichment of altered gene expression in cardiac pathways and mitochondrial energy metabolism.

Conclusions

Our study first shows that BICD2 is a novel candidate gene associated with familial DCM, and our findings will facilitate further insights into the molecular pathological mechanisms of DCM.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-022-01349-y.

Sarcomere protein modulation: The new frontier in cardiovascular medicine and beyond

Over the past decade, the constant progress in science and technologies has provided innovative drug molecules that address specific disease mechanisms thus opening the era of drugs targeting the underlying pathophysiology of the disease. In this scenario, a new paradigm of modulation has emerged, following the development of small molecules capable of interfering with sarcomere contractile proteins. Potential applications include heart muscle disease and various forms of heart failure, although promising targets also include conditions affecting the skeletal muscle, such as degenerative neuromuscular diseases. In cardiac patients, a cardiac myosin stimulator, omecamtiv mecarbil, has shown efficacy in heart failure with reduced systolic function, lowering heart failure related events or cardiovascular death, while two inhibitors, mavacamten and aficamten, in randomized trials targeting hypertrophic cardiomyopathy, have been shown to reduce hypercontractility and left ventricular outflow obstruction improving functional capacity. Based on years of intensive basic and translational research, these agents are the prototypes of active pipelines promising to deliver an array of molecules in the near future. We here review the available evidence and future perspectives of myosin modulation in cardiovascular medicine.

Proteomics research of SARS-CoV-2 and COVID-19 disease

Currently, coronavirus disease 2019 (COVID-19) is still spreading in a global scale, exerting a massive health and socioeconomic crisis. Deep insights into the molecular functions of the viral proteins and the pathogenesis of this infectious disease are urgently needed. In this review, we comprehensively describe the proteome of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and summarize their protein interaction map with host cells. In the protein interaction network between the virus and the host, a total of 787 host prey proteins that appeared in at least two studies or were verified by co-immunoprecipitation experiments. Together with 29 viral proteins, a network of 1762 proximal interactions were observed. We also review the proteomics results of COVID-19 patients and proved that SARS-CoV-2 hijacked the host's translation system, post-translation modification system, and energy supply system via viral proteins, resulting in various immune disorders, multiple cardiomyopathies, and cholesterol metabolism diseases.

LMNA mutation leads to cardiac sodium channel dysfunction in the Emery-Dreifuss muscular dystrophy patient

Pathogenic variants in the LMNA gene are known to cause laminopathies, a broad range of disorders with different clinical phenotypes. LMNA genetic variants lead to tissue-specific pathologies affecting various tissues and organs. Common manifestations of laminopathies include cardiovascular system abnormalities, in particular, cardiomyopathies and conduction disorders. In the present study, we used induced pluripotent stem cells from a patient carrying LMNA p.R249Q genetic variant to create an in vitro cardiac model of laminopathy. Induced pluripotent stem cell-derived cardiomyocytes with LMNA p.R249Q genetic variant showed a decreased sodium current density and an impaired sodium current kinetics alongside with changes in transcription levels of cardiac-specific genes. Thus, we obtained compelling in vitro evidence of an association between LMNA p.R249Q genetic variant and cardiac-related abnormalities.

Dilated cardiomyopathy in the era of precision medicine: latest concepts and developments

Dilated cardiomyopathy (DCM) is an umbrella term entailing a wide variety of genetic and non-genetic etiologies, leading to left ventricular systolic dysfunction and dilatation, not explained by abnormal loading conditions or coronary artery disease. The clinical presentation can vary from asymptomatic to heart failure symptoms or sudden cardiac death (SCD) even in previously asymptomatic individuals. In the last 2 decades, there has been striking progress in the understanding of the complex genetic basis of DCM, with the discovery of additional genes and genotype-phenotype correlation studies. Rigorous clinical work-up of DCM patients, meticulous family screening, and the implementation of advanced imaging techniques pave the way for a more efficient and earlier diagnosis as well as more precise indications for implantable cardioverter defibrillator implantation and prevention of SCD. In the era of precision medicine, genotype-directed therapies have started to emerge. In this review, we focus on updates of the genetic background of DCM, characteristic phenotypes caused by recently described pathogenic variants, specific indications for prevention of SCD in those individuals and genotype-directed treatments under development. Finally, the latest developments in distinguishing athletic heart syndrome from subclinical DCM are described.

Mortality Among Patients With Early-Onset Atrial Fibrillation and Rare Variants in Cardiomyopathy and Arrhythmia Genes

Importance

Patients with early-onset atrial fibrillation (AF) are enriched for rare variants in cardiomyopathy and arrhythmia genes. The clinical significance of these rare variants in patients with early-onset AF is unknown.

Objective

To assess the association between rare variants in cardiomyopathy and arrhythmia genes detected in patients with early-onset AF and time to death.

Design, Setting, and Participants

This prospective cohort study included participants with AF diagnosed before 66 years of age who underwent whole-genome sequencing through the National Heart, Lung and Blood Institute's Trans-Omics for Precision Medicine program. Participants were enrolled from November 23, 1999, to June 2, 2015. Data were analyzed from February 26 to September 19, 2021.

Exposures

Rare variants identified in a panel of 145 genes that are included in cardiomyopathy and arrhythmia panels used by commercial clinical genetic testing laboratories.

Main Outcomes and Measures

The primary study outcome was time to death and was adjudicated from medical records and the National Death Index. Multivariable Cox proportional hazards regression was used to evaluate the association of disease-associated variants with risk of death after adjustment for age at AF diagnosis, sex, race, body mass index, left ventricular ejection fraction, and an interaction term of age at AF diagnosis and disease-associated variant status.

Results

Among 1293 participants (934 [72%] male; median age at enrollment, 56.0 years; IQR, 48.0-61.0 years), disease-associated (pathogenic or likely pathogenic) rare variants were found in 131 (10%). During a median follow-up of 9.9 years (IQR, 6.9-13.2 years), 219 participants (17%) died. In univariable analysis, disease-associated variants were associated with an increased risk of mortality (hazard ratio, [HR], 1.5; 95% CI, 1.0-2.1; P = .05); the association remained significant in multivariable modeling when adjusted for age at AF diagnosis, sex, race, body mass index, left ventricular ejection fraction, and an interaction term between disease-associated variant status and age at AF diagnosis. The interaction demonstrated that disease-associated variants were associated with a significantly higher risk of mortality compared with no disease-associated variant when AF was diagnosed at a younger age (P = .008 for interaction). Higher body mass index (per IQR: HR, 1.4; 95% CI, 1.2-1.6; P < .001) and lower left ventricular ejection fraction (per IQR: HR, 0.8; 95% CI, 0.7-0.8; P < .001) were associated with higher mortality risk. There were 73 cardiomyopathy-related deaths, 40 sudden deaths, and 10 stroke-related deaths. Mortality among patients with the most prevalent genes with disease-associated variants was 26% (10 of 38 patients) for TTN, 33% (6 of 18) for MYH7, 22% (2 of 9) for LMNA, 0% (0 of 10) for MYH6, and 0% (0 of 8) for KCNQ1.

Conclusions and Relevance

The findings suggest that rare variants in cardiomyopathy and arrhythmia genes may be associated with increased risk of mortality among patients with early-onset AF, especially those diagnosed at a younger age. Genetic testing may provide important prognostic information for patients with early-onset AF.

Transcriptome analysis uncovers the autophagy-mediated regulatory patterns of the immune microenvironment in dilated cardiomyopathy

The relationship between autophagy and immunity has been well studied. However, little is known about the role of autophagy in the immune microenvironment during the progression of dilated cardiomyopathy (DCM). Therefore, this study aims to uncover the effect of autophagy on the immune microenvironment in the context of DCM. By investigating the autophagy gene expression differences between healthy donors and DCM samples, 23 dysregulated autophagy genes were identified. Using a series of bioinformatics methods, 13 DCM‐related autophagy genes were screened and used to construct a risk prediction model, which can well distinguish DCM and healthy samples. Then, the connections between autophagy and immune responses including infiltrated immunocytes, immune reaction gene‐sets and human leukocyte antigen (HLA) genes were systematically evaluated. In addition, two autophagy‐mediated expression patterns in DCM were determined via the unsupervised consensus clustering analysis, and the immune characteristics of different patterns were revealed. In conclusion, our study revealed the strong effect of autophagy on the DCM immune microenvironment and provided new insights to understand the pathogenesis and treatment of DCM.

A Comprehensive Outlook on Dilated Cardiomyopathy (DCM): State-Of-The-Art Developments with Special Emphasis on OMICS-Based Approaches

Dilated cardiomyopathy (DCM) remains an enigmatic cardiovascular disease (CVD) condition characterized by contractile dysfunction of the myocardium due to dilation of the ventricles. DCM is one of the major forms of CVD contributing to heart failure. Dilation of the left or both ventricles with systolic dysfunction, not explained by known causes, is a hallmark of DCM. Progression of DCM leads to heart failure. Genetic and various other factors greatly contribute to the development of DCM, but the etiology has still remained elusive in a large number of cases. A significant number of studies have been carried out to identify the genetic causes of DCM. These candidate-gene studies revealed that mutations in the genes of the fibrous, cytoskeletal, and sarcomeric proteins of cardiomyocytes result in the development of DCM. However, a significant proportion of DCM patients are idiopathic in nature. In this review, we holistically described the symptoms, causes (in adults and newborns), genetic basis, and mechanistic progression of DCM. Further, we also summarized the state-of-the-art diagnosis, available biomarkers, treatments, and ongoing clinical trials of potential drug regimens. DCM-mediated heart failure is on the rise worldwide including in India. The discovery of biomarkers with a better prognostic value is the need of the hour for better management of DCM-mediated heart failure patients. With the advent of next-generation omics-based technologies, it is now possible to probe systems-level alterations in DCM patients pertaining to the identification of novel proteomic and lipidomic biomarkers. Here, we also highlight the onset of a systems-level study in Indian DCM patients by applying state-of-the-art mass-spectrometry-based “clinical proteomics” and “clinical lipidomics”.

Dilated cardiomyopathy caused by a pathogenic nucleotide variant in RBM20 in an Iranian family

Introduction

Dilated cardiomyopathy (DCM) is characterized by the dilation and impaired contraction of 1 or both ventricles and can be caused by a variety of disorders. Up to 50% of idiopathic DCM cases have heritable familial diseases, and the clinical screening of family members is recommended. Identifying a genetic cause that can explain the DCM risk in the family can help with better screening planning and clinical decision-making. Whole-exome sequencing (WES) has aided significantly in the detection of causative genes in many genetically heterogeneous diseases. In the present study, we applied WES to identify the causative genetic variant in a family with heritable DCM.

Methods

WES was applied to identify genetic variants on a 26-year-old man as the proband of a family with DCM. Subsequently, Sanger sequencing was performed to confirm the variant in the patient and all the available affected and unaffected family members. The pathogenicity of the variant was evaluated through co-segregation analysis in the family and employment of in silico predictive software.

Results

WES demonstrated the missense pathogenic heterozygous nucleotide variant, c.1907G > A, (p.Arg636His, rs267607004, NM_0011343), in exon 9 of the RBM20 gene in the proband. The variant was co-segregated in all the affected family members in a heterozygous form and the unaffected family members. The in silico analysis confirmed the variant as pathogenic.

Conclusion

Pathogenic RBM20 nucleotide variants are associated with arrhythmogenic DCM. We believe that our report is the first to show an RBM20 variant in Iranian descent associated with DCM.

A novel deletion mutation accompanied by a point mutation in Lamin A/C gene: Screened from a dilated cardiomyopathy family

BACKGROUND

There are 30%-40% of patients with dilated cardiomyopathy (DCM) having genetic causes, among which Lamin A and C gene (LMNA) mutation is the second most frequent DCM-related mutation, and Lamin A/C may be involved in the pathogenesis of DCM through the regulation of gene transcription or the direct effect of cell structure. Methods: Echocardiography and electrocardiogram were used to diagnose DCM and arrhythmia in a DCM family. Then, linked mutations on LMNA were screened out by high-throughput sequencing and verified by Sanger sequencing in all research individuals. Meanwhile, Human Genome Variation Society (HGVS) and Integrative Genomics Viewer (IGV) were used to analyse the characteristics of the mutated Lamin A/C protein. Finally, mutated-type and wild-type LMNA plasmid was transfected into AC-16 cardiomyocytes with the form of a lentivirus vector, and its effect on nucleus and actin was studied by immunofluorescence detection.

RESULTS

In this study, we found a new frame-shifted mutation of LMNA (p.Ser414Alafs*66) linked with another point mutation from a DCM family by using High-throughput sequencing, and this deletion mutation led to a truncation of Lamin A/C. By analysing the clinical characteristics of this DCM family, we found that all DCM patients with arrhythmia were carriers of this co-segregation mutation. In the cytological experiment, we found that the mutated-type transfections showed weaker fluorescent intensities on both actin and cell nucleus.

CONCLUSIONS

A co-segregation mutation of LMNA (Point mutation chr1 156107548 c.1712 G>A and truncated frame-shifted mutation chr1 156106086 c.1240delA) was found from a DCM family, and this type of mutation could participate in the pathogenesis of DCM by affecting the expression of actin.

Exploring Key Genes to Construct a Diagnosis Model of Dilated Cardiomyopathy

Background

Dilated cardiomyopathy (DCM) is characterized by left ventricular dilatation and systolic dysfunction. The pathogenesis and etiologies of DCM remain elusive. This study aims to identify the key genes to construct a genetic diagnosis model of DCM.

Methods

A total of 257 DCM samples from five independent cohorts were enrolled. The Weighted Gene Co-Expression Network Analysis (WGCNA) was performed to identify the key modules associated with DCM. The latent mechanisms and protein-protein interaction network underlying the key modules were further revealed. Subsequently, we developed and validated a LASSO diagnostic model in five independent cohorts.

Results

Two key modules were identified using WGCNA. Novel mechanisms related to the extracellular, mitochondrial matrix or IL-17 signaling pathway were pinpointed, which might significantly influence DCM. Besides, 23 key genes were screened out by combining WGCNA and differential expression analysis. Based on the key genes, a genetic diagnosis model was constructed and validated using five cohorts with excellent AUCs (0.975, 0.954, 0.722, 0.850, 0.988). Finally, significant differences in immune infiltration were observed between the two groups divided by the diagnostic model.

Conclusion

Our study revealed several novel pathways and key genes to provide potential targets and biomarkers for DCM treatment. A key genes’ diagnosis model was built to offer a new tool for diagnosing DCM.

LMNA Determines Nuclear Morphology During Syncytialization of Human Trophoblast Stem Cells

Upon implantation, the trophectoderm differentiates into the multi-nucleated primitive syncytiotrophoblast (pSTB) through a process called primary syncytialization to facilitate maternal-fetal interactions and to establish a pregnancy. However, ethical issues and limited access to human embryos around the time of embryo implantation hinder the investigation of the detailed molecular mechanisms underpinning this event in humans. Here we established human trophoblast stem cells (hTSCs) from human blastocysts. We characterized nuclear enlargement in STB differentiated from hTSCs, which recapitulate morphological nuclear features of pSTB in human embryos. Specifically, we revealed that CRISPR/Cas9-mediated LMNA disruption perturbated nuclear volume during hTSCs syncytialization. Overall, our results not only provide an interesting insight into mechanisms underlying nuclear enlargement during primary syncytialization but highlight the hTSCs as an indispensable model in understanding human trophoblast differentiation during implantation.

Genetic Insights into Primary Restrictive Cardiomyopathy

Restrictive cardiomyopathy is a rare cardiac disease causing severe diastolic dysfunction, ventricular stiffness and dilated atria. In consequence, it induces heart failure often with preserved ejection fraction and is associated with a high mortality. Since it is a poor clinical prognosis, patients with restrictive cardiomyopathy frequently require heart transplantation. Genetic as well as non-genetic factors contribute to restrictive cardiomyopathy and a significant portion of cases are of unknown etiology. However, the genetic forms of restrictive cardiomyopathy and the involved molecular pathomechanisms are only partially understood. In this review, we summarize the current knowledge about primary genetic restrictive cardiomyopathy and describe its genetic landscape, which might be of interest for geneticists as well as for cardiologists.