Vinculin (VCL) is a key adapter protein located in force-bearing costamere complexes, which mechanically couples the sarcomere to the ECM. Heterozygous vinculin frameshift genetic variants can contribute to cardiomyopathy when external stress is applied, but the mechanosensitive pathways underpinning VCL haploinsufficiency remain elusive. Here, we show that in response to extracellular matrix stiffening, heterozygous loss of VCL disrupts force-mediated costamere protein recruitment, thereby impairing cardiomyocyte contractility and sarcomere organization. Analyses of human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) harboring either VCL c.659dupA or VCL c.74del7 heterozygous VCL frameshift variants revealed that these VCL mutant hPSC-CMs exhibited heightened contractile strain energy, morphological maladaptation, and sarcomere disarray on stiffened matrix. Mechanosensitive recruitment of costameric talin 2, paxillin, focal adhesion kinase, and α-actinin was significantly reduced in vinculin variant cardiomyocytes. Despite poorly formed costamere complexes and sarcomeres, elevated expression of integrin β1 and cortical actin on stiff substrates may rescue force transmission on stiff substrates, an effect that is recapitulated in WT CMs by ligating integrin receptors and blocking mechanosensation. Together, these data support that heterozygous loss of VCL contributes to adverse cardiomyocyte remodeling by impairing adhesion-mediated force transmission from the costamere to the cytoskeleton. (191 words).

Takotsubo syndrome (TTS) primarily manifests as a cardiomyopathy induced by physical or emotional stress, remains a poorly understood condition with no established treatments. In this study, we investigated the potential of sacubitril/valsartan (sac/val) to increase the survival of TTS patients and reduce inflammation and myocardial fibrosis in experimental models.

Brugada Syndrome (BrS) is an inherited arrhythmia syndrome characterised by ST-segment elevation in the right precordial ECG leads and is associated with an increased risk of sudden cardiac death. We identify and characterise a novel SCN3B variant encoding the regulatory β3-subunit of the cardiac voltage-gated sodium channel, Na1.5.

Angiogenesis plays a pivotal role in ischemic cardiovascular disease, accompanied by epigenetic regulation during this process. Sirtuin 6 (SIRT6) has been implicated in the regulation of DNA repair, transcription and aging, with its deacetylase activity fully studied. However, the role of SIRT6 demyristoylase activity remains less clear, with even less attention given to its myristoylated substrates. In this study, we report that endothelial specific SIRT6 knockout attenuated angiogenesis in mice, while SIRT6 was observed to promote migration and tube formation in endothelial cell. Notably, we further determined that SIRT6 affects the intracellular VEGFA and global myristoylation level under hypoxia. Moreover, ALK14 (myristic acids analogue) treatment and SIRT6 knockdown results in a significant decrease in VEGFA secretion under hypoxia, implying the involvement of SIRT6 demyristoylase activity in angiogenesis. Mechanistically, CLICK IT assay verified that VEGFA is a myristoylated substrate of SIRT6. Further, overexpression of SIRT6 mutants (R65A, G60A and H133Y) results in profound differences in VEGFA secretion, indicating that SIRT6 promotes VEGFA secretion through demyristoylation but not deacetylation. Finally, overexpression of SIRT6 rescued the diminishment of endothelial migration, tube formation and sprouting caused by ALK14 treatment. Overall, our study demonstrates that SIRT6 regulates angiogenesis by demyristoylating VEGFA and increasing VEGFA secretion. Therefore, modulation of SIRT6 demyristoylase activity may represent a therapeutic strategy for ischemic cardiovascular disease.

Acute aortic dissection (AAD) is a life-threatening cardiovascular emergency, which is closely related to the vascular smooth muscle cells (VSMCs) phenotypic switching and extracellular matrix (ECM) degradation. Previous studies have found that the secreted extracellular glycoprotein Follistatin-like 1 (FSTL1) is demonstrated as a protective factor for cardiovascular diseases. However, the role of FSTL1 in AAD remains elusive. We aimed to investigate whether FSTL1 could regulate VSMCs phenotypic switching and ECM degradation in AAD. Firstly, we found that FSTL1 expression in aorta was significantly decreased in human AAD examined by western blot and immunohistochemical staining. Then we established a mouse AAD model by administering β-aminopropionitrile (BAPN) dissolved in drinking water for 28 days. We found that FSTL1 expression in aorta was also decreased in mouse AAD. Exogenous supplement with recombinant human FSTL1 protein could rescue VSMCs phenotypic switching and ECM degradation to reduce the occurrence and progression of mouse AAD. In vitro, FSTL1 protein and adenovirus overexpressing FSTL1 (ad-FSTL1) reversed the primary VSMCs phenotypic switching and decreased the expression of MMP2 induced by PDGF-BB. Knocking down FSTL1 initiates VSMCs phenotypic switching and increases the expression of MMP2. In terms of mechanisms, AMPK phosphorylation was decreased and could be improved by FSTL1 protein in mouse AAD. FSTL1 protein and ad-FSTL1 reversed the decreased AMPK phosphorylation induced by PDGF-BB in primary VSMCs. These findings indicate that FSTL1 protects against VSMCs phenotypic switching and ECM degradation in AAD, and targeting FSTL1 may be a potential new strategy for prevention and treatment of AAD.

Cardiologists have analyzed daily patterns in the incidence of sudden cardiac death to identify environmental, behavioral, and physiological factors that trigger fatal arrhythmias. Recent studies have indicated an overall increase in sudden cardiac arrest during daytime hours when the frequency of arrhythmogenic triggers is highest. The risk of fatal arrhythmias arises from the interaction between these triggers-such as elevated sympathetic signaling, catecholamine levels, heart rate, afterload, and platelet aggregation-and the heart's susceptibility (myocardial substrate) to them. A healthy myocardial substrate has structural and functional properties that protect against arrhythmias. However, individuals with cardiovascular disease often exhibit structural and electrophysiological alterations in the myocardial substrate that predispose them to sustained lethal arrhythmias. This review focuses on how day-night and circadian rhythms, both extrinsic and intrinsic, influence the protective properties of the myocardial substrate. Specifically, it explores recent advances in the temporal regulation of ion channel gene transcription, drawing on data from comprehensive bioinformatics resources (CircaDB, CircaAge, and CircaMET) and recent RNA sequencing studies. We also examine potential mechanisms underlying the temporal regulation of mRNA expression and the challenges in linking rhythmic mRNA expression to corresponding changes in protein levels. As chronobiological research in cardiology progresses, we anticipate the development of novel therapeutic strategies to enhance the protective properties of the myocardial substrate to reduce the risk of fatal arrhythmias and sudden cardiac arrest.

Hypertrophic Cardiomyopathy (HCM) is often caused by heterozygous mutations in β-myosin heavy chain (MYH7, β-MyHC). In addition to hyper- or hypocontractile effects of HCM-mutations, heterogeneity in contractile function (contractile imbalance) among individual cardiomyocytes was observed in end-stage HCM-myocardium. Contractile imbalance might be induced by burst-like transcription, leading to unequal fractions of mutant versus wildtype mRNA and protein in individual cardiomyocytes (allelic imbalance). Until now it is not known if allelic and contractile imbalance are present early in HCM-development or rather occur in response to disease-associated remodeling. To address this question, we used patient-specific human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) with heterozygous MYH7-mutations R723G and G741R as models of early-stage HCM without secondary adaptions upon disease progression. R723G-hiPSC-CMs showed typical HCM-markers like hypertrophy and myofibrillar disarray. Using RNA-FISH and allele-specific single-cell-PCR, we show for both cell lines that MYH7 is transcribed in bursts. Highly variable mutant vs. wildtype MYH7-mRNA fractions in individual HCM-hiPSC-CMs indicated allelic imbalance. HCM-hiPSC-CM-lines showed functional alterations like slowed twitch contraction kinetics and reduced calcium sensitivity of myofibrillar force generation. A significantly larger variability in force generation or twitch parameters of individual HCM-hiPSC-CMs compared to WT-hiPSC-CMs indicated contractile imbalance. Our results with early-stage hiPSC-CMs strongly suggest that burst-like transcription and allelic imbalance are general features of CMs, which together with mutation-induced changes of sarcomere contraction could induce contractile imbalance in heterozygous CMs, presumably aggravating development of HCM. Genetic or epigenetic approaches targeting functional heterogeneity in HCM could lead to promising future therapies, in addition to myosin modulation.

Sodium/glucose cotransporter 2 inhibitors (SGLT2is) like empagliflozin have demonstrated cardioprotective effects in patients with or without diabetes. SGLT2is have been shown to selectively inhibit the late component of cardiac sodium current (late I). Induction of late I is the primary mechanism in the pathophysiology of congenital long QT syndrome type 3 (LQT3) gain-of-function mutations in the SCN5A gene encoding Nav1.5. We investigated empagliflozin's effect on late I in thirteen known LQT3 mutations located in distinct regions of the channel.

Treatment of cancer patients with tyrosine kinase inhibitors (TKIs) often results in hypertension, but the underlying mechanism remains unclear. This study aimed to examine the role of mitochondrial morphology and function, particularly mitochondria-associated endoplasmic reticulum membranes (MAMs), in sunitinib-induced hypertension.

To investigate the role and mechanism of MAPK14/AIFM2 pathway in Ang II-induced atrial fibrillation in rats.

Optogenetic stimulation combined with optical mapping of membrane potential (Vm) and calcium transients (CaT) is a powerful electrophysiological tool. We developed a novel experimental platform in which tissue is stimulated optogenetically while Vm and CaT are imaged simultaneously. The Vm indicator is an organic dye, while the CaT indicator is genetically encoded. We used cardiac spheroids containing cardiomyocytes and fibroblasts differentiated from human induced pluripotent stem cells as model tissue. The spheroids were genetically encoded with an optogenetic actuator, CheRiff, and the calcium indicator jRCaMP1b. The Vm indicator was the organic dye RH237. CheRiff was excited using blue light (450 nm), and both RH237 and jRCaMP1b were excited using a single band of green light (either 525-575 nm or 558-575 nm). Fluorescence emission was split and imaged by two cameras (CaT: 595-665 nm; Vm: >700 nm). The spheroids were successfully stimulated optogenetically and Vm and CaT were recorded simultaneously without cross-talk using both excitation light bands. The 525-575 nm band produced higher signal-to-noise ratios than the 558-575 nm band, but caused a slight increase in tissue excitability because of CheRiff activation. The optogenetic actuator and CaT indicator are genetically encoded and can be expressed in engineered tissue constructs. In contrast, the Vm indicator is an organic dye that can stain any tissue. This system is well-suited for studying coupling between engineered tissue grafts and host tissue because the two tissue types can be stimulated independently, and tissue activation can be unambiguously attributed to either graft or host.

Sox17-Erg direct reprogramming is a potent tool for the in vitro and in vivo generation of arterial-like induced-endothelial cells from fibroblasts. In this study, we illustrate the pioneering roles of both Sox17 and Erg in the endothelial cell reprogramming process and demonstrate that emergent gene expression only occurs when both factors are co-expressed. Bioinformatic analyses and molecular validation reveal both Bach2 and Etv4 as integral mediators of Sox17-Erg reprogramming with different roles in lung and heart fibroblast reprogramming. The generated organ-specific induced endothelial cells express molecular signatures similar to vasculature found in the starting cell's organ of origin and the starting chromatin architecture plays a role in the acquisition of this organ-specific identity. Overall, the Sox17-Erg reprogramming mechanism provides foundational knowledge for the future recapitulation of vascular heterogeneity through direct reprogramming.

Our previous single-cell RNA sequencing study in the adult human heart revealed that cardiomyocytes from both the atrium and ventricle display high activities of Krüppel-like factor 2 (KLF2) regulons. However, the role of the transcription factor KLF2 in cardiomyocyte biology remains largely unexplored.

Abnormal valve development is the most common congenital heart malformation. The transcription factor Sox7 plays a critical role in the development of vascular and cardiac septation. However, it remains unclear whether Sox7 is required for heart valve development. In the present study, Sox7 was strongly expressed in the endocardial and mesenchymal cells of the developing aortic valve in mice and humans, and that endocardial cell specific deletion of Sox7 (Nfatc1 Cre;Sox7) in mice leads to congenital aortic stenosis basing on our echocardiography data and multiple staining results. Mechanistically, Sox7 influences extracellular matrix (ECM) remodeling of the valve through regulating MMP9. Meanwhile, Sox7 also affects other valvular remodeling processes, including apoptosis and proliferation of valvular cells in Sox7 deficiency mice. Similarly, in valvular interstitial cells (VICs), Sox7 overexpression increased the protein levels of cleaved caspase3 and TUNEL-positive VICs, while Ki67-positive VICs decreased. The reverse trend was observed in VICs with Sox7 deficiency. Significant enhancement of Rbm25 transcriptional levels was observed in the Sox7 overexpression group, and the mRNA and protein levels of calcification markers such as Osterix, Osteopontin and Runx2 were reduced. The reverse trend was observed in VICs with Sox7 deficiency. Von Kossa staining and Alizarin Red staining also demonstrated that sever calcification in Nfatc1 Cre;Sox7 mice. Moreover, we detected the Sox7 protein expression in human fetal aortic valves in patients with aortic stenosis, in which Sox7 positive mesenchymal cells were decreased. Taken together, these findings identify Sox7 as a potential pathogenic gene responsible for congenital aortic stenosis in human. Our study provides novel strategies for the diagnosis and treatment of congenital valvular malformation.

Cardiovascular disease (CVD) is the leading cause of death for women worldwide. One of the risk factors for CVD in women is complications during pregnancy. Pregnancy complications include a wide arena of pathologies, including hypertension, preeclampsia, gestational diabetes, preterm delivery and miscarriage. Interestingly, increased evidence in recent years highlights a novel link between maternal shift work during pregnancy and increased risk for pregnancy complications, specifically hypertension and diabetes, while knowledge on other CVDs, such heart failure, atherosclerosis, ischemic heart disease, and stroke in pregnant shift working mothers is still scarce. Notably, shift work during pregnancy results in significant changes to the circadian rhythm of both the mother and fetus, therefore, engaging into shift work during pregnancy may adversely affect the cardiovascular health of both the mother and offspring, and carry into adulthood. Herein, we highlight the novel relationship between maternal shift work during pregnancy and the increased risk for pregnancy complications that may increase risk for CVD later in life. Furthermore, we provide mechanistic insights of the hemodynamic processes that are disrupted in response to maternal shift work and may explain the increased risk for cardiovascular disease. Understanding how shift work during pregnancy influences the prevalence for heart disease is of paramount clinical importance for minimizing the risk for cardiovascular disease for both the mother and offspring.

Coronary stenting operations have become the main option for the treatment of coronary heart disease. Vessel recovery after stenting has emerged as a critical factor in reducing possible complications. In this study, we evaluated the feasibility, safety and efficacy of locally administered intraluminal gene therapy delivered using a specialized infusion balloon catheter.

The age of the U.S. population is increasing alongside a growing burden of age-related cardiovascular disease. Circadian rhythms are critical for human health and are disrupted with aging and cardiovascular disease. The goal of the present review is to summarize how cardiac circadian rhythms change with age and how this might contribute to the increasing burden of age-associated heart disease. Further, we will review what is known about interventions to slow aging and whether they impact cardiac clock function, as well as whether time-of-day or chronotherapy may improve cardiac function with age. Although much remains to be understood about the circadian biology of cardiac aging, we propose that altered circadian clock output should be considered a hallmark of aging and that efforts to fix the clock are warranted for healthy cardiac aging.