RNA helicase DDX5 maintains cardiac function by regulating CamkIIδ alternative splicing [RNA-seq]
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE248443 | GEO | 2024/12/02
REPOSITORIES: GEO
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Project description:The cardiomyocyte-specific deletion of Ddx5 in mice resulted in heart failure characterized by diminished cardiac function, enlarged heart chambers, and heightened fibrosis. Proteomic analysis unveiled the involvement of DDX5 in RNA splicing within cardiomyocytes. Our study identified DDX5 as a regulator of the abnormal splicing of CamkIIδ, preventing the generation of CaMKIIδA. This isoform activates LTCC through serine phosphorylation of Cacna1c, disrupting Ca2+ homeostasis. Consistently, DDX5-depleted cardiomyocytes exhibited elevated intracellular Ca2+ transients and increased sarcoplasmic reticulum Ca2+ content.
2024-12-02 | GSE248444 | GEO
Project description:Muscle contraction depends on strictly controlled Ca2+ transients within myocytes. A major player maintaining these transients is the sarcoplasmic/endoplasmic reticulum Ca2+ ATPase, SERCA. Activity of SERCA is regulated by binding of micropeptides and impaired expression or function of these peptides results in cardiomyopathy. To date, it is not known how homeostasis or turnover of the micropeptides is regulated. We found that the Drosophila endopeptidase Neprilysin 4 hydrolyzes SERCA-inhibitory Sarcolamban peptides in membranes of the sarcoplasmic reticulum, thereby ensuring proper regulation of SERCA. Cleavage was necessary and sufficient to maintain homeostasis and function of the micropeptides. Analyses on human Neprilysin, sarcolipin, and ventricular cardiomyocytes indicated that the regulatory mechanism is evolutionarily conserved. By identifying a neprilysin as essential regulator of SERCA activity and Ca2+ homeostasis in cardiomyocytes, these data contribute to a more comprehensive understanding of the complex mechanisms that control muscle contraction and heart function in health and disease.
2022-06-01 | PXD027738 | Pride
Project description:Zebrafish ncx1h (also known as slc8a1a) encodes a cardiac specific sodium-calcium exchanger 1 (NCX1h), a primary Ca 2+ efflux effector in cardiomyocytes. The zebrafish tremblor (tre) mutant lacks functional NCX1h and, consequentially, cyclic Ca2+ transients are abolished. In this study, we investigated the effect of aberrant Ca2+ homeostasis in cardiomyocytes on gene expression. Wild type and ncx1 mutant hearts at 48 hours post fertilization were isolated for RNA preparation and gene expression analysis was performed using an Affymetrix Zebrafish GeneChip.
2017-09-20 | E-MTAB-5850 | biostudies-arrayexpress
Project description:Arrhythmogenic cardiomyopathy (ACM) is characterized by life-threatening ventricular arrhythmias and sudden cardiac death and affects hundreds of thousands of patients worldwide. The deletion of Arginine 14 (p.R14del) in the phospholamban (PLN) gene has been implicated in the pathogenesis of ACM. PLN is a key regulator of sarcoplasmic reticulum (SR) Ca2+ cycling and cardiac contractility. Despite global gene and protein expression studies, the molecular mechanisms of PLN-R14del ACM pathogenesis remain unclear. Using a humanized PLN-R14del mouse model and human induced pluripotent stem cell derived cardiomyocytes (iPSC-CMs), we investigated the transcriptome-wide mRNA splicing changes associated with the R14del mutation. We identified >200 significant alternative splicing (AS) events and distinct AS profiles were observed in the right (RV) and left (LV) ventricles in PLN- R14del compared to WT mouse hearts. Enrichment analysis of the AS events showed that the most affected biological process was associated with “cardiac cell action potential”, specifically in the RV. We found that splicing of 2 key genes, Trpm4andCamk2d, which encode proteins regulating calcium homeostasis in the heart, were altered in PLN-R14del mouse hearts and human iPSC-CMs. Bioinformatical analysis pointed to the tissue-specific splicing factors Srrm4 and Nova1 as likely upstream regulators of the observed splicing changes in the PLN-R14del cardiomyocytes. Our findings suggest that aberrant splicing may affect Ca2+- homeostasis in the heart, contributing to the increased risk of arrythmogenesis in PLN- R14del ACM.
2022-11-22 | GSE217921 | GEO
Project description:Intracellular calcium (Ca2+) overload is known to play a critical role in the development of cardiac dysfunction. Despite the remarkable improvement in managing the progression of heart disease, developing effective therapies for heart failure (HF) remains a challenge. A better understanding of molecular mechanisms that maintain proper Ca2+ levels and contractility in the injured heart could be of therapeutic value. Here, we report that the transcription factor Zinc finger E-box-binding homeobox2 (ZEB2) is induced by Hypoxia-inducible factor 1-alpha (HIF1a) in hypoxic cardiomyocytes and regulates a network of genes involved in Ca2+-handling and contractility during ischemic heart disease. Gain- and loss-of-function studies in genetic mouse models revealed ZEB2 in cardiomyocytes to be necessary and sufficient to protect the heart against ischemia-induced diastolic dysfunction and structural remodeling. Moreover, RNA sequencing (RNA-seq) of ZEB2-overexpressing (Zeb2 cTg) hearts post-injury implicated ZEB2 in regulating numerous Ca2+-handling and contractility-related genes. Mechanistically, ZEB2 overexpression increased the phosphorylation of phospholamban (PLN) at both serine-16 and threonine-17, implying enhanced activity of sarcoplasmic reticulum Ca2+-ATPase (SERCA2a), thereby augmenting SR Ca2+ uptake and contractility. Furthermore, we observed a decrease in the activity of Ca2+-dependent calcineurin/NFAT signaling in Zeb2 cTg hearts, which is the main driver of pathological cardiac remodeling. On a post-transcriptional level, we showed that ZEB2 expression can be regulated by the cardiomyocyte-specific microRNA-208a (miR-208a). Blocking the function of miR-208a with antimiR-208a increased ZEB2 expression in the heart and effectively protected from the development of pathological cardiac hypertrophy. Together, we present ZEB2 as a central regulator of contractility and Ca2+-handling components in the mammalian heart. Further mechanistic understanding of the role of ZEB2 in regulating Ca2+ homeostasis in cardiomyocytes is an essential step towards the development of improved therapies for HF.
2024-12-19 | GSE236827 | GEO
Project description:Background: The phospholamban (PLN) p.Arg14del mutation belongs to the established causes of dilated cardiomyopathy, with the molecular disease mechanisms incompletely understood. We used human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes, CRISPR/Cas9 gene editing and patient heart samples to investigate the molecular pathomechanisms of PLN p.Arg14del cardiomyopathy. Methods and results: Patient dermal fibroblasts carrying the PLN p.Arg14del mutation were reprogrammed into hiPSC, isogenic controls were established by CRISPR/Cas9. Cells were differentiated into cardiomyocytes and characterized in 2D and 3D-engineered heart tissue (EHT) format. Mutant cardiomyocytes revealed significantly prolonged Ca2+ transient decay time, Ca2+-load dependent irregular beating pattern and lower peak force compared to isogenic controls. While this data support the reported super-inhibitory effect of PLN p.Arg14del on the sarcoplasmic/endoplasmic reticulum Ca2+ ATPase, an unchanged SR Ca2+ content argued against disturbed SR Ca2+ cycling as the sole cause of contractile dysfunction. Label-free proteomic analysis of p.Arg14del EHTs revealed less endoplasmic reticulum (ER), ribosomal and mitochondrial proteins. Electron microscopy showed dilation of the rough ER, large lipid droplets in close association with mitochondria and reduced mitochondrial number. Follow-up experiments confirmed impairment of the rough ER/mitochondria compartment and enhanced oxidative stress in PLN p.Arg14del. Relevance for human disease was demonstrated by immunohistochemistry of human heart samples. PLN p.Arg14del end-stage heart failure samples revealed perinuclear aggregates positive for ER marker proteins and oxidative stress in comparison to ischemic heart failure - and non-failing donor heart samples. Surprisingly, transduction of PLN p.Arg14del EHTs with the Ca2+ binding protein GCaMP6f reversed the contractile, molecular and morphological disease phenotype. Conclusion: This study identified impairment of the rough ER/mitochondria compartment without SR dysfunction as a novel disease mechanism underlying PLN p.Arg14del cardiomyopathy. The pathology was improved by Ca2+-scavenging, suggesting impaired local Ca2+ cycling as an important disease culprit.
2021-04-12 | PXD020175 | Pride
Project description:: The adult heart develops hypertrophy to reduce ventricular wall stress and maintain cardiac function in response to an increased workload. Although pathological hypertrophy generally progresses to heart failure, physiological hypertrophy may be cardioprotective. Cardiac-specific overexpression of the lipid-droplet protein perilipin 5 (Plin5) promotes cardiac hypertrophy, but it is unclear if this response is beneficial. We analyzed human RNA-sequencing data from the left ventricle and showed that cardiac PLIN5 expression correlates with upregulation of cardiac contraction-related processes. To investigate how elevated cardiac Plin5 levels affect cardiac contractility, we generated mice with cardiac-specific overexpression of Plin5 (MHC-Plin5 mice). These mice displayed increased left ventricular mass and cardiomyocyte size but preserved heart function. Quantitative proteomics identified sarcoplasmic/endoplasmic reticulum Ca2+ ATPase 2 (SERCA2) as a Plin5-interacting protein. Phosphorylation of phospholamban, the master regulator of SERCA2, was increased in MHC-Plin5 versus wild-type cardiomyocytes. Live imaging showed increases in intracellular Ca2+ release during contraction, Ca2+ removal during relaxation, and SERCA2 function in MHC-Plin5 versus wild-type cardiomyocytes. These results identify a role for Plin5 in improving cardiac contractility through enhanced Ca2+ signaling.
2023-01-20 | PXD035121 | Pride
Project description:In differentiated skeletal muscle, intracellular Ca2+ concentrations rise dramatically upon membrane depolarization, constituting the link between excitation and contraction (EC). Transient rises in [Ca2+]i mainly emerge from Ca2+ released by the type 1 ryanodine receptor (RYR1) and, in non-adult muscle, by the inositol 1,4,5-triphosphate receptor (IP3R) of the sarcoplasmic reticulum (SR), the dominant Ca2+ store in skeletal muscle. While the IP3R-mediated, slow Ca2+ transients, have been implicated in cell signaling and development, RYR1’s non-contractile role(s) remain obscure. We used a homozygous mouse RyR1 knockout model (dyspedic) to investigate the effects of the absence of a functional RYR1 and, consequently, the lack of RyR1-mediated Ca2+ signaling during embryogenesis. While heterozygous mice of the model are undistinguishable from WT littermates, homozygous dyspedic mice die at birth from asphyxia, since their skeletal muscle does not support EC coupling. Furthermore, they display abnormal spine curvature, subcutaneous hematomas, small limbs, and enlarged neck. Skeletal muscles from front and hind limbs of dyspedic embryos (day E18.5) were subjected to microarray analyses, revealing 318 genes, significantly regulated by at least 50 % compared to control heterozygous littermates.
2016-02-01 | E-MTAB-3608 | biostudies-arrayexpress
Project description:L-type voltage-gated calcium channels (LTCCs) regulate crucial physiological processes in the heart. They are composed of the Cav1 pore-forming subunit and the accessory subunits Cav, Cav2 and Cav. Cav is a cytosolic soluble protein that regulates channel trafficking and activity, but it also exerts other LTCC-independent functions. Cardiac hypertrophy, a relevant risk factor for the development of congestive heart failure, depends on the activation of calcium-dependent pro-hypertrophic signaling cascades; however, the role of LTCCs in this pathology remains controversial. Here, by using shRNA-mediated Cav silencing, we demonstrate that Cav2 downregulation enhances 1-adrenergic receptor agonist-induced cardiomyocyte hypertrophy in an LTCC-independent manner. We report that a pool of Cav2 is targeted to the nucleus in cardiomyocytes and that the expression of this nuclear fraction decreases during in vitro and in vivo induction of cardiac hypertrophy. Moreover, the overexpression of nucleus-targeted Cav2 in cardiomyocytes inhibits in vitro-induced hypertrophy. Quantitative proteomic analyses showed that Cav2 knockdown leads to changes in the expression of diverse myocyte proteins, including reduction of calpastatin, an endogenous inhibitor of the calcium-dependent protease calpain. Accordingly, Cav2-deficient cardiomyocytes had a two-fold increase in calpain activity as compared to control cells. Furthermore, inhibition of calpain activity in Cav2-deficient cells abolished the enhanced 1-adrenergic receptor agonist-induced hypertrophy observed in these cells. Our findings indicate that in cardiomyocytes, a nuclear pool of Cav2 participates in cellular functions that are independent of LTCC activity. They also indicate that a downregulation of nuclear Cav2 during cardiac hypertrophy promotes the activation of calpain-dependent hypertrophic pathways.
2021-09-09 | PXD016483 | Pride
Project description:BACKGROUND: Cardiac hypertrophy compensates for increased biomechanical stress of the heart induced by prevalent cardiovascular pathologies, but can result in cardiac failure if left untreated. We hypothesized that the tail-anchored protein Dysferlin with multiple Ca2+-binding C2-domains is critical for the integrity of the transverse-axial tubule (TAT) network inside cardiomyocytes, and contributes to the proliferation of TAT endomembranes during pressure overload-induced cardiac hypertrophy. OBJECTIVE: To reveal the impact of the membrane fusion and repair protein Dysferlin on TAT network stabilization and proliferation necessary for the hypertrophic growth of cardiomyocytes. METHODS AND RESULTS: Super-resolution light and electron microscopy of mouse cardiomyocytes identified a specific localization of Dysferlin in a vesicular compartment in nanometric proximity to contact sites of the TAT network with the sarcoplasmic reticulum (SR), a.k.a. junctional complexes for Ca2+-induced Ca2+ release. Mass spectrometry was used to characterize the cardiac Dysferlin interactome, thereby identifying a novel protein interaction with the membrane-tethering SR protein Juncophilin-2, a known interactor of L-type Ca2+ channels and Ryanodine Receptor Ca2+ release channels in junctional complexes. While the Dysferlin knockout caused a mild progressive phenotype of dilated cardiomyopathy in the mouse heart, global proteome analysis revealed changes preceding systolic failure. Following transverse aortic constriction (TAC), Dysferlin protein expression was significantly increased in hypertrophied wild-type myocardium, while Dysferlin knockout animals presented markedly reduced left-ventricular hypertrophy. Live-cell membrane imaging demonstrated a profound reorganization of the TAT network in wild-type left-ventricular myocytes post-TAC with robust proliferation of axial tubules, which critically depended on the increased expression of Dysferlin within newly-emerging tubule components. CONCLUSIONS: Dysferlin represents a new molecular target in cardiac disease that protects the integrity of tubule-SR junctional complexes for regulated excitation-contraction coupling, and controls TAT network reorganization and tubular membrane proliferation in cardiomyocyte hypertrophy induced by pressure-overload.
2024-07-15 | PXD053037 | Pride