Elimination of CaMKIIδ Autophosphorylation by CRISPR-Cas9 Base Editing Improves Survival and Cardiac Function in Heart Failure in Mice

Increased Myocardial MARK4 Expression in Patients with Heart Failure and Sleep-Disordered Breathing

Cardiovascular diseases are the leading cause of morbidity and mortality worldwide, underscoring the urgent need for novel therapeutic targets and strategies. The kinase MARK4 (MAP (microtubule-associated proteins)/microtubule affinity-regulating kinase 4) regulates microtubule-associated proteins pivotal for cell polarity, protein stability, and intracellular signaling. Animal models of heart failure revealed elevated MARK4 levels, which correlated with impaired cardiac contractility. However, the involvement of MARK4 and its potential as a molecular drug target has not yet been explored in the myocardium of cardiovascular patients. We investigated the MARK4 mRNA expression in human myocardial biopsies of 152 high-risk cardiovascular patients undergoing cardiac surgery. Comprehensive echocardiography as well as testing for sleep-disordered breathing (SDB), a critical comorbidity in heart failure, were assessed preoperatively. We observed a substantial upregulation of myocardial MARK4 expression in patients with impaired cardiac contractility, resulting in an inverse correlation with the left ventricular ejection fraction. Myocardial MARK4 expression also correlated with echocardiographic E/e', a central parameter of diastolic dysfunction. Mechanistically, our analyses revealed that MARK4 expression increases in SDB and under hypoxic conditions, as evidenced by significant correlations between myocardial MARK4 expression and factors like mean oxygen saturation, time with oxygen saturation below 90%, and the oxygen desaturation index. Multivariable regression analysis revealed that both left ventricular ejection fraction and mean oxygen saturation were independently associated with dysregulated MARK4 levels, even when controlling for important clinical covariables as potential confounders. Taken together, our findings demonstrate that MARK4 expression is highly increased in the myocardium of cardiovascular high-risk patients, suggesting it is a potential molecular target against cardiovascular diseases.

NEDD4-Mediated GSNOR Degradation Aggravates Cardiac Hypertrophy and Dysfunction

BACKGROUND

The decrease in S-nitrosoglutathione reductase (GSNOR) leads to an elevation of S-nitrosylation, thereby exacerbating the progression of cardiomyopathy in response to hemodynamic stress. However, the mechanisms under GSNOR decrease remain unclear. Here, we identify NEDD4 (neuronal precursor cell expressed developmentally downregulated 4) as a novel molecule that plays a crucial role in the pathogenesis of pressure overload-induced cardiac hypertrophy, by modulating GSNOR levels, thereby demonstrating significant therapeutic potential.

METHODS

Protein synthesis and degradation inhibitors were used to verify the reasons for the decrease in GSNOR. Mass spectrometry and database filtering were used to uncover NEDD4, the E3 Ub (ubiquitin) ligase, involved in GSNOR decrease. NEDD4 cardiomyocyte-specific deficiency mice were used to evaluate the role of NEDD4 and NEDD4-induced ubiquitination of GSNOR in cardiac hypertrophy in vivo. Both IBM (indolebutenate methyl ester derivatives), a highly specific NEDD4 inhibitor, and indole-3-carbinol, a NEDD4 inhibitor currently undergoing phase 2 clinical trial, were used to effectively suppress the NEDD4/GSNOR axis.

RESULTS

GSNOR protein levels were reduced, while mRNA levels remained unchanged in myocardium samples from hypertrophic patients and transverse aortic constriction-induced mice, indicating GSNOR is regulated by ubiquitination. NEDD4, an E3 Ub ligase, was associated with GSNOR ubiquitination, which exhibited significantly higher expression levels in hypertrophic myocardial samples. Moreover, either the NEDD4 enzyme-dead mutant or GSNOR nonubiquitylated mutant decreased GSNOR ubiquitination and inhibited cardiac hypertrophic growth. Cardiomyocyte-specific NEDD4 deficiency inhibited cardiac hypertrophy in vitro and in vivo. NEDD4 inhibitor IBM effectively suppressed GSNOR ubiquitination and cardiac hypertrophy. Clinically, indole-3-carbinol, a NEDD4 inhibitor in phase II clinical trials used as an antitumor drug, demonstrated comparable efficacy.

CONCLUSIONS

Our findings showed that upregulated NEDD4 leads to GSNOR ubiquitination and subsequent degradation, thereby facilitating the progression of cardiac hypertrophy. NEDD4 inhibitors may serve as a potential therapeutic strategy for the treatment of cardiac hypertrophy and heart failure.

Myocardial DYRK1B Expression Is Increased in Patients with Impaired Cardiac Contractility and Sleep-Disordered Breathing

Heart failure and cardiovascular disease represent a significant burden on healthcare systems worldwide. Recent evidence associates an increased expression of the dual-specificity tyrosine phosphorylation-regulated kinase 1B (DYRK1B) with an impaired cardiac function in mice. However, there remains a paucity of data on myocardial DYRK1B expression in patients with cardiovascular disease in the context of other comorbidities. In our study, we examined DYRK1B mRNA expression in human right atrial appendage biopsies from 159 patients undergoing elective coronary artery bypass surgery. Each patient was tested for sleep-disordered breathing the night prior to surgery. In this large representative study cohort with cardiovascular high-risk patients, we found that an impaired cardiac function as well as sleep-disordered breathing (SDB), including various oxidative stress parameters, were associated with an increased myocardial DYRK1B expression. A multivariate regression analysis revealed left ventricular ejection fraction and the presence of SDB as significant predictors of the myocardial DYRK1B expression independent of other clinical covariates. Based on these findings, DYRK1B represents a promising molecular target in patients with heart failure and reduced ejection fraction as well in patients with sleep-disordered breathing.

LMNA-related cardiomyopathy: From molecular pathology to cardiac gene therapy

BACKGROUND

The genetic variants of LMNA cause an array of diseases that often affect the heart. LMNA-related cardiomyopathy exhibits high-penetrance and early-onset phenotypes that lead to late-stage heart failure or lethal arrhythmia. As a subtype of dilated cardiomyopathy and arrhythmogenic cardiomyopathy, LMNA-related cardiac dysfunction is resistant to existing cardiac therapeutic strategies, leaving a major unmet clinical need in cardiomyopathy management.

AIM OF REVIEW

Here we comprehensively summarize current knowledge about the genetic basis, disease models and pathological mechanisms of LMNA-related cardiomyopathy. Recent translational studies were highlighted to indicate new therapeutic modalities such as gene supplementation, gene silencing and genome editing therapy, which offer potential opportunities to overcome the difficulties in the development of specific drugs for this disease.

KEY SCIENTIFIC CONCEPTS OF REVIEW

LMNA-related cardiomyopathy involves many diverse disease mechanisms that preclude small-molecule drugs that target only a small fraction of the mechanisms. Agreeing to this notion, the first-in-human clinical trial for this disease recently reported futility. By contrast, gene therapy offers the new hope to directly intervene LMNA variants and demonstrates a tremendous potential for breakthrough therapy for this disease. Concepts in this review are also applicable to studies of other genetic diseases that lack effective therapeutics.

Gene editing in common cardiovascular diseases

Cardiovascular diseases are the leading cause of morbidity and mortality worldwide, highlighting the high socioeconomic impact. Current treatment strategies like compound-based drugs or surgeries are often limited. On the one hand, systemic administration of substances is frequently associated with adverse side effects; on the other hand, they typically provide only short-time effects requiring daily intake. Thus, new therapeutic approaches and concepts are urgently needed. The advent of CRISPR-Cas9 genome editing offers great promise for the correction of disease-causing hereditary mutations. As such mutations are often very rare, gene editing strategies to correct them are not broadly applicable to many patients. Notably, there is recent evidence that gene editing technology can also be deployed to disrupt common pathogenic signaling cascades in a targeted, specific, and efficient manner, which offers a more generalizable approach. However, several challenges remain to be addressed ranging from the optimization of the editing strategy itself to a suitable delivery strategy up to potential immune responses to the editing components. This review article discusses important CRISPR-Cas9-based gene editing approaches with their advantages and drawbacks and outlines opportunities in their application for treatment of cardiovascular diseases.

Empagliflozin prevents heart failure through inhibition of the NHE1-NO pathway, independent of SGLT2

Sodium glucose cotransporter 2 inhibitors (SGLT2i) constitute the only medication class that consistently prevents or attenuates human heart failure (HF) independent of ejection fraction. We have suggested earlier that the protective mechanisms of the SGLT2i Empagliflozin (EMPA) are mediated through reductions in the sodium hydrogen exchanger 1 (NHE1)-nitric oxide (NO) pathway, independent of SGLT2. Here, we examined the role of SGLT2, NHE1 and NO in a murine TAC/DOCA model of HF. SGLT2 knockout mice only showed attenuated systolic dysfunction without having an effect on other signs of HF. EMPA protected against systolic and diastolic dysfunction, hypertrophy, fibrosis, increased Nppa/Nppb mRNA expression and lung/liver edema. In addition, EMPA prevented increases in oxidative stress, sodium calcium exchanger expression and calcium/calmodulin-dependent protein kinase II activation to an equal degree in WT and SGLT2 KO animals. In particular, while NHE1 activity was increased in isolated cardiomyocytes from untreated HF, EMPA treatment prevented this. Since SGLT2 is not required for the protective effects of EMPA, the pathway between NHE1 and NO was further explored in SGLT2 KO animals. In vivo treatment with the specific NHE1-inhibitor Cariporide mimicked the protection by EMPA, without additional protection by EMPA. On the other hand, in vivo inhibition of NOS with L-NAME deteriorated HF and prevented protection by EMPA. In conclusion, the data support that the beneficial effects of EMPA are mediated through the NHE1-NO pathway in TAC/DOCA-induced heart failure and not through SGLT2 inhibition.

CaMKIIδ-dependent dysregulation of atrial Na+ homeostasis promotes pro-arrhythmic activity in an obstructive sleep apnea mouse model

Background

Obstructive sleep apnea (OSA) has been linked to various pathologies, including arrhythmias such as atrial fibrillation. Specific treatment options for OSA are mainly limited to symptomatic approaches. We previously showed that increased production of reactive oxygen species (ROS) stimulates late sodium current through the voltage-dependent Na+ channels via Ca2+/calmodulin-dependent protein kinase IIδ (CaMKIIδ), thereby increasing the propensity for arrhythmias. However, the impact on atrial intracellular Na+ homeostasis has never been demonstrated. Moreover, the patients often exhibit a broad range of comorbidities, making it difficult to ascertain the effects of OSA alone.

Objective

We analyzed the effects of OSA on ROS production, cytosolic Na+ level, and rate of spontaneous arrhythmia in atrial cardiomyocytes isolated from an OSA mouse model free from comorbidities.

Methods

OSA was induced in C57BL/6 wild-type and CaMKIIδ-knockout mice by polytetrafluorethylene (PTFE) injection into the tongue. After 8 weeks, their atrial cardiomyocytes were analyzed for cytosolic and mitochondrial ROS production via laser-scanning confocal microscopy. Quantifications of the cytosolic Na+ concentration and arrhythmia were performed by epifluorescence microscopy.

Results

PTFE treatment resulted in increased cytosolic and mitochondrial ROS production. Importantly, the cytosolic Na+ concentration was dramatically increased at various stimulation frequencies in the PTFE-treated mice, while the CaMKIIδ-knockout mice were protected. Accordingly, the rate of spontaneous Ca2+ release events increased in the wild-type PTFE mice while being impeded in the CaMKIIδ-knockout mice.

Conclusion

Atrial Na+ concentration and propensity for spontaneous Ca2+ release events were higher in an OSA mouse model in a CaMKIIδ-dependent manner, which could have therapeutic implications.

Role of CaMKII in diabetes induced vascular injury and its interaction with anti-diabetes therapy

Diabetes mellitus is a metabolic disorder denoted by chronic hyperglycemia that drives maladaptive structural changes and functional damage to the vasculature. Attenuation of this pathological remodeling of blood vessels remains an unmet target owing to paucity of information on the metabolic signatures of this process. Ca2+/calmodulin-dependent kinase II (CaMKII) is expressed in the vasculature and is implicated in the control of blood vessels homeostasis. Recently, CaMKII has attracted a special attention in view of its chronic upregulated activity in diabetic tissues, yet its role in the diabetic vasculature remains under investigation.This review highlights the physiological and pathological actions of CaMKII in the diabetic vasculature, with focus on the control of the dialogue between endothelial (EC) and vascular smooth muscle cells (VSMC). Activation of CaMKII enhances EC and VSMC proliferation and migration, and increases the production of extracellular matrix which leads to maladaptive remodeling of vessels. This is manifested by activation of genes/proteins implicated in the control of the cell cycle, cytoskeleton organization, proliferation, migration, and inflammation. Endothelial dysfunction is paralleled by impaired nitric oxide signaling, which is also influenced by CaMKII signaling (activation/oxidation). The efficiency of CaMKII inhibitors is currently being tested in animal models, with a focus on the genetic pathways involved in the regulation of CaMKII expression (microRNAs and single nucleotide polymorphisms). Interestingly, studies highlight an interaction between the anti-diabetic drugs and CaMKII expression/activity which requires further investigation. Together, the studies reviewed herein may guide pharmacological approaches to improve health-related outcomes in patients with diabetes.

Regulated cell death in myocardial ischemia-reperfusion injury

Myocardial ischemia-reperfusion (I/R) injury most commonly occurs in coronary artery disease when prompt reperfusion is used to salvage the ischemic myocardium. Cardiomyocyte death is a significant component of myocardial I/R injury and its mechanism was previously thought to be limited to apoptosis and necrosis. With the discovery of novel types of cell death, ferroptosis, necroptosis, and pyroptosis have been shown to be involved in myocardial I/R. These new forms of regulated cell death cause cardiomyocyte loss and exacerbate I/R injury by affecting reactive oxygen species (ROS) generation, calcium stress, and inflammatory cascades, subsequently mediating adverse remodeling, cardiac dysfunction, and heart failure. Herein, we review the roles of ferroptosis, necroptosis, and pyroptosis in myocardial I/R and discuss their contribution to pathology.

Insights into the Interaction of Heart Failure with Preserved Ejection Fraction and Sleep-Disordered Breathing

Heart failure with preserved ejection fraction (HFpEF) is emerging as a widespread disease with global socioeconomic impact. Patients with HFpEF show a dramatically increased morbidity and mortality, and, unfortunately, specific treatment options are limited. This is due to the various etiologies that promote HFpEF development. Indeed, cluster analyses with common HFpEF comorbidities revealed the existence of several HFpEF phenotypes. One especially frequent, yet underappreciated, comorbidity is sleep-disordered breathing (SDB), which is closely intertwined with the development and progression of the "obese HFpEF phenotype". The following review article aims to provide an overview of the common HFpEF etiologies and phenotypes, especially in the context of SDB. As general HFpEF therapies are often not successful, patient- and phenotype-individualized therapeutic strategies are warranted. Therefore, for the "obese HFpEF phenotype", a better understanding of the mechanistic parallels between both HFpEF and SDB is required, which may help to identify potential phenotype-individualized therapeutic strategies. Novel technologies like single-cell transcriptomics or CRISPR-Cas9 gene editing further broaden the groundwork for deeper insights into pathomechanisms and precision medicine.