Search Results (220)

The Sarco Endoplasmic Reticulum Ca²⁺-ATPase (SERCA) pumps cytosolic Ca²⁺ into the endoplasmic reticulum lumen (ER) to maintain cytosolic and ER Ca²⁺ levels under physiological conditions. Previous reports suggest that cellular Ca²⁺ homeostasis is compromised in Alzheimer’s Disease (AD) and that SERCA activity can modulate the phenotype of AD mouse models. Here, we used a C. elegans strain that overexpresses the most toxic human ß-amyloid peptide (Aß_(1-42)) in body-wall muscle cells to study the effects of SERCA (sca-1) silencing on Aß_(1-42)-induced body-wall muscle dysfunction. sca-1 knockdown reduced the percentage of paralyzed worms, improved locomotion in free-mobility assays, and restored pharynx pumping in Aß_(1-42)-overexpressing worms. At the cellular level, sca-1 silencing partially prevented Aß_(1-42)-induced exacerbated mitochondrial respiration and mitochondrial ROS production and restored mitochondrial organization around sarcomeres. sca-1 knockdown reduced the number and size of Aß_(1-42) aggregates in body–wall muscle cells and prevented the formation of Aß_(1-42) oligomers. Aß_(1-42) expression induced a slower kinetics of spontaneous cytosolic Ca²⁺ transients in muscle cells and sca-1 partially restored these changes. We propose that partial sca-1 loss of function prevents the toxicity associated with beta-amyloid accumulation by reducing the formation of Aß_(1-42) oligomers and improving mitochondrial function, in a mechanism that requires remodeling of cytosolic Ca²⁺ dynamics and partial ER Ca²⁺ depletion. Full article

Background: Cardiac glycosides such as digoxin have been commonly used for patients with heart failure; however, their toxicity remains a main concern. 17βH-neriifolin (SNA209), a cardiac glycoside compound, has been recently isolated from Ceberra odollum Gaertn and was shown to improve the heart’s pumping ability in failing hearts ex vivo. Thus, this study aimed to investigate the potential use of SNA209 as a treatment for isoprenaline (ISO)-induced heart failure in rats. Methods: Forty male Wistar rats were randomly divided into five groups. Heart failure was induced by isoprenaline (ISO, 10 mg/kg/s.c) for 14 days daily, followed by SNA209 treatment (5 mg/kg; p.o) for another 14 days daily. Control rats were given saline as a vehicle for ISO and DMSO as a vehicle for SNA209. Results: Systolic and diastolic blood pressure (SBP and DBP) in all ISO-treated groups were significantly increased compared to the control group (p < 0.05), and SNA209 treatment managed to reduce the SBP and DBP. Additionally, SNA209 treatment significantly increased the heart rate and normalized the ECG parameters in ISO-treated rats. Pro-B-type natriuretic peptide and troponin T level, a cardiac injury markers, was remarkably reduced by SNA209 in the ISO-treated group. Cardiac hypertrophy was evident in increased cardiomyocyte size in ISO groups; however, SNA reduced the cardiomyocyte size. The left ventricular developed pressure (LVDP) in ISO treated with SNA209 was significantly raised, indicating a chronotropic effect. Cardiac Na⁺/K⁺-ATPase expression of the α1 subunit, sarcoplasmic/endoplasmic reticulum Ca²⁺ ATPase 2a (SERCA2a), and sodium–calcium exchanger subunit were significantly increased in the SNA treatment groups. Conclusions: The SNA 209 treatment improved cardiac function and structure, likely via modulating intracellular calcium management, so underscoring its potential as an adjuvant therapy for heart failure. Full article

Human embryonic stem cell-derived cardiomyocytes (hESC-CMs) tend to show a mixed population of action potential (AP) types, including atrial-like (A-like) and ventricular-like (V-like) APs. In the present study, we investigated the membrane currents underlying these two AP types in hESC-CMs. These were generated using standard (Std) and retinoic acid (RA)-based differentiation protocols. Patch clamp methodology was used to correlate AP morphology with major cardiac ion currents by applying alternating current and voltage clamp protocols to each cell, and to measure L-type Ca²⁺ current (I_Ca,L) and Na⁺-Ca²⁺ exchange current (I_NCX) in detail, whereas Ca²⁺ transients were measured ratiometrically using Indo-1. A- and V-like APs were found in both Std and RA-treated hESC-CMs and the AP plateau amplitude (AP_plat), as a measure of fast phase-1 repolarization, appeared the best AP criterion to separate these two AP types. Traditional voltage clamp experiments revealed a significantly smaller I_Ca,L density in RA-treated hESC-CMs, as well as larger densities of the transient outward and delayed rectifier K⁺ currents (I_to1 and I_K, respectively), without changes in the inward rectifier K⁺ current (I_K1). The AP_plat showed strong and moderate correlations with the densities of I_Ca,L and I_K, respectively, in the absence of a clear-cut correlation with the density of I_to1. Using pre-recorded, typical A- and V-like APs, AP clamp demonstrated that the I_Ca,L-mediated Ca²⁺ influx during the V-like AP in Std hESC-CMs is 3.15 times larger than the influx during the A-like AP in RA-treated hESC-CMs. Ca²⁺ transients of A-like hESC-CMs have a lower diastolic and systolic level, as well as a lower amplitude, than those of Std hESC-CMs, while their duration is shorter due to enhanced SERCA activity. In conclusion, I_Ca,L is an important determinant of the differently shaped A- and V-like APs in hESC-CMs. Furthermore, the Ca²⁺ homeostasis differs between A- and V-like hESC-CMs due to the smaller I_Ca,L and enhanced SERCA activity during A-like APs, resulting in a strongly reduced Ca²⁺ influx, which will cause a substantial reduction in I_NCX, further contributing to the shorter A-like APs. Full article

Heart-specific overexpression of transcriptional regulator JDP2 (jun dimerization protein 2) for 5 weeks provokes paroxysmal atrial fibrillation (AF) in mice. We now investigated whether AF and atrial remodeling will be reversible upon termination of JDP2 overexpression, and whether paroxysmal AF converts to permanent AF in the presence of maintained JDP2 overexpression. Cardiac-specific JDP2 overexpression for 5 weeks, resulting in paroxysmal AF, was either continued or repressed via a tet-off system for another 5 weeks. ECGs were recorded weekly. Thereafter, heart and lung weights, and atrial mRNA and protein expression were determined. Extending JDP2 overexpression did not aggravate the AF phenotype, still paroxysmal AF, prolongation of PQ intervals, and atrial hypertrophy were present. This phenotype was completely reversible upon cessation of JDP2 overexpression. A massive downregulation of connexin40 and calcium handling proteins, including SERCA2a, calsequestrin, and ryanodine receptor, was observed in atria after prolonged JDP2 overexpression. In conclusion, atrial remodeling and paroxysmal AF under JDP2 overexpression are not sufficient to maintain or aggravate AF in the absence of JDP2. The comparison of the two groups indicates that the downregulation of calcium proteins and connexins is an important factor in the maintenance of the disease. Full article

It is well recognized that patients with type 2 diabetes mellitus (T2DM) exhibit significant impairment of immune function resulting in a higher frequency of infections. We hypothesize in this study that a likely contributor to immune dysfunction in T2DM is alteration of T lymphocyte signaling functions induced by chronic hyperglycemia. In this study we have utilized the established UC Davis Type 2 Diabetes Mellitus (UCD-T2DM) rat model of human T2DM to investigate whether progressive hyperglycemia diminishes T cell receptor (TCR)-releasable endoplasmic reticulum (ER) Ca²⁺ stores, an essential early antigen-stimulated signal driving T cell activation. Furthermore, results from this study demonstrate that chronic hyperglycemia markedly alters the expression profile of the sarco/endoplasmic reticulum Ca²⁺-ATPase (SERCA) Ca²⁺ ion pumps, which are the major enzymatic ion transporters maintaining replenished TCR-sensitive Ca²⁺ pools. We conducted companion experiments using Jurkat T lymphocytes exposed to high glucose which allowed finer resolution of early disruptions to ER Ca²⁺ store integrity and greater clarity on SERCA isoform-specific roles in diabetes-induced Ca²⁺ signal dysregulation. In summary, these experiments suggest that hyperglycemia in T2DM drives an ER stress state manifesting in reduced expression of the SERCA pumps, erosion of ER Ca²⁺ stores and culminating in T cell and immune dysfunction. Full article

Background/Objectives: Ellagic acid (EA) is a polyphenol found in several fruits and vegetables, including pomegranate, nuts and berries. It exhibits significant health benefits, mainly cardio- and vaso-protective; indeed, EA protects the myocardium against infarction and inhibits cardiac fibrosis. These beneficial effects may be, at least in part, promoted by calcium release from and uptake by the sarcoplasmic reticulum, which are crucial events for cardiac relaxation and contraction. Regardless, the exact mechanism is currently unclear. Methods: A deeper investigation of the role of EA in cardiac contractility and the underlying mechanism has been carried out by using an ex vivo model of isolated and perfused rat heart. Results and Discussion: EA perfusion (100 nM–10 µM) did not influence the coronary flow (CF), suggesting the absence of a vasoactivity, but significantly increased contractility parameters (LVDP and dP/dt). Interestingly, a more marked effect of EA on LVDP and dP/dt values was observed when it was perfused in the presence of AngII. Cyclopiazonic acid (CA) and red ruthenium (RR), specific antagonists of SERCA and RyRs, respectively, were used to explore the contribution of EA when the intracellular calcium handling was altered. In the presence of CA, EA, perfused at increasing concentrations, showed a very modest positive inotropism (significant only at 1 µM). Instead, RR, which significantly compromised all functional parameters, completely masked the effects of EA; furthermore, a marked reduction in CF and a dramatic impact on the positive inotropism occurred. Conclusions: These results demonstrate the positive inotropism of EA on isolated and perfused hearts and suggest that the RyRs may be a main target through which EA plays its effects, since inhibition with RR almost completely blocks the positive inotropism. Full article

The growth of tumor cells is accompanied by an increased rate of endoplasmic reticulum stress (ERS), the accumulation of misfolded proteins, and the activation of a network of adaptive signaling pathways known as the unfolded protein response (UPR). Although the UPR is an adaptive reaction aiming to restore ER proteostasis, prolonged and severe ERS leads to cell death. Taking into account that the components of the ERS/UPR machinery in cancers of different types can be overexpressed or downregulated, both the induction of excessive ERS and suppression of UPR have been proposed as therapeutic strategies to sensitize cells to conventional chemotherapy. This narrative review presents a several examples of using natural and synthetic compounds that can either induce persistent ERS by selectively blocking ER Ca²⁺ pumps (SERCA) to disrupt ER Ca²⁺ homeostasis, or altering the activity of UPR chaperones and sensors (GRP78, PERK, IRE1α, and ATF6) to impair protein degradation signaling. The molecular alterations induced by miscellaneous inhibitors of ERS/UPR effectors are described as well. These agents showed promising therapeutic effects as a part of combination therapy in preclinical experimental settings; however, the number of clinical trials is still limited, while their results are inconsistent. Multiple side effects, high toxicity to normal cells, or poor bioavailability also hampers their clinical application. Since the pharmacological modulation of ERS/UPR is a valuable approach to sensitize cancer cells to standard chemotherapy, the search for more selective agents with better stability and low toxicity, as well as the development of more efficient delivery systems that can increase their therapeutic specificity, are highly required goals for future studies. Full article

Right heart failure (RHF) is a major cause of morbidity and mortality, often resulting from pulmonary arterial hypertension and characterized by impaired calcium (Ca²⁺) handling and maladaptive remodeling. Phosphodiesterase 9A (PDE9A), a cGMP-specific phosphodiesterase, has been proposed as a potential contributor to RHF pathogenesis by suppressing the cardioprotective cGMP–PKG signaling pathway—a conclusion largely extrapolated from left-sided heart failure models. This review examines existing evidence regarding PDE9A’s role in RHF, focusing on its effects on intracellular calcium cycling, fibrosis, hypertrophy, and contractile dysfunction. Data from preclinical models demonstrate that pathological stress upregulates PDE9A expression in cardiomyocytes, leading to diminished PKG activation, impaired SERCA2a function, RyR2 instability, and increased arrhythmogenic Ca²⁺ leak. Pharmacological or genetic inhibition of PDE9A restores cGMP signaling, improves calcium handling, attenuates hypertrophic and fibrotic remodeling, and enhances ventricular compliance. Early-phase clinical studies in heart failure populations suggest that PDE9A inhibitors are well tolerated and effectively augment cGMP levels, although dedicated trials in RHF are still needed. Overall, these findings indicate that targeting PDE9A may represent a promising therapeutic strategy to improve outcomes in RHF by directly addressing the molecular mechanisms underlying calcium mishandling and myocardial remodeling. Full article

Obesity is a major risk factor for atrial fibrillation (AF), the most common serious cardiac arrhythmia, but the molecular mechanisms underlying obesity-induced AF remain unclear. In this study, we subjected mice to a chronic high-fat diet and acute sympathetic activation to investigate how obesity promotes AF. Surface electrocardiography revealed that obesity and sympathetic activation synergize during intracardiac tachypacing to induce AF. At the cellular level, this combination facilitated delayed afterdepolarizations in atrial myocytes, implicating altered Ca²⁺ dynamics. Interestingly, obesity did not affect the expression of key atrial Ca²⁺-handling proteins, including the cardiac sarcoplasmic reticulum Ca²⁺-ATPase (SERCA2a). However, obesity increases the proportion of inhibitory phospholamban (PLN) monomers and decreases PLN phosphorylation, suggesting reduced SERCA2a activity. Paradoxically, Ca²⁺ reuptake in atrial myocytes from obese mice was similar to that achieved by potent small-molecule SERCA2a activators. We found that adrenergic stimulation increased Ca²⁺ transient amplitude without altering Ca²⁺ reuptake in myocytes from obese mice. Transcriptomic analysis revealed that a high-fat diet upregulated neuronatin, a protein involved in obesity that enhances SERCA2-mediated Ca²⁺ reuptake in neurons. We propose that obesity enables SERCA2a activation independently of PLN regulation, while adrenergic stimulation triggers arrhythmogenic Ca²⁺-induced Ca²⁺ release, promoting AF. In conclusion, this study demonstrates that obesity causes a paradoxical dysregulation of SERCA2a in atrial myocytes, with increased activity despite higher levels of inhibitory PLN monomers and reduced PLN phosphorylation. These findings offer new insights into the cellular mechanisms of obesity-induced AF and suggest potential therapeutic targets. Full article

Growth traits are critical economic characteristics in aquaculture. This study aimed to identify the candidate genes associated with the growth of C. fuscus by integrating QTL mapping for growth traits and the RNA-seq analysis of differentially expressed genes (DEGs) between two extreme body size groups (big-sized group and small-sized group). QTL mapping was performed on eight growth traits—body weight, body height, body length, body width, orbital diameter, caudal peduncle length, caudal peduncle height, and pre-dorsal length—using 200 individuals from a full-sibling line. Seventeen growth-related QTL were identified across eight linkage groups, explaining phenotypic variance ranging from 8.00% to 11.90%. A total of 162 functional genes were annotated within these QTL intervals. RNA-seq analysis identified 3824 DEGs between the big-sized and small-sized groups, with 2252 genes upregulated and 1572 downregulated in the big group. By integrating QTL mapping and RNA-seq data, 27 candidate genes were identified, including myostatin (mstnb), epidermal growth factor receptor (egfr), and sarcoplasmic/endoplasmic reticulum calcium ATPase 1 (serca1). These findings provide crucial insights into the genetic regulation of growth in C. fuscus and lay a foundation for future genetic selection strategies. Full article

: Heart failure with preserved ejection fraction (HFpEF) accounts for approximately 50% of heart failure cases and is primarily characterized by impaired diastolic function, leading to increased ventricular filling pressures and symptoms like dyspnea and reduced exercise tolerance. Significant gender-specific differences are observed, with women, particularly post-menopausal, experiencing higher prevalence and distinct clinical profiles compared to men. Diastolic dysfunction in HFpEF involves altered cellular mechanisms such as reduced SERCA2a expression, impacting calcium handling and myocardial relaxation. Diagnostic strategies mainly employ echocardiography, including Doppler imaging, tissue Doppler imaging, and strain imaging, to assess ventricular relaxation and stiffness. However, early identification remains challenging, necessitating advanced tools like cardiac magnetic resonance and exercise stress testing for accurate diagnosis, especially in women who often present with subtle symptoms. Treatment options for HFpEF have traditionally been limited, but recent trials, notably EMPEROR-PRESERVED and DELIVER, demonstrated significant cardiovascular benefits using sodium–glucose cotransporter-2 (SGLT2) inhibitors. Additionally, glucagon-like peptide-1 receptor agonists (GLP-1 RAs) have shown promising results, particularly in obese patients. Despite these advances, gender differences in therapeutic response necessitate further research for personalized management strategies. Understanding sex-specific pathophysiological mechanisms and optimizing diagnostic criteria remain essential to improving prognosis and quality of life in HFpEF patients. Full article

Darier′s disease (DD) is a rare, autosomal dominant genodermatosis caused by pathogenic variants in the ATP2A2 gene, which encodes the SERCA2 protein, an endoplasmic reticulum ATPase Ca²⁺ transporter. These mutations impair the intracellular calcium homeostasis leading to increased protein misfolding, endoplasmic reticulum (ER) stress response, and the activation of the unfolded protein response (UPR), culminating in keratinocyte apoptosis and anomalies in interfollicular epidermal stratification. Clinically, the disease is characterized by the presence of skin lesions with hyperkeratotic papules and an increased susceptibility to inflammatory reactions, bacterial and viral infections. The histological hallmarks include acantholysis, dyskeratosis, and increased apoptotic keratinocytes, referred to as “corp ronds”. The SERCA2b isoform is expressed not only in the epidermis but it is present ubiquitously in all tissues, suggesting that its alteration may have multi-organ effects. The review aims to provide a broad overview of the pathology, from intracellular dysfunction to the clinical manifestations, elucidating the molecular effects of SERCA2 variants found in DD patients and exploring the potential cell signaling pathways that may contribute to disease progression. Beginning with an examination of the cellular alterations, our work then shifts to exploring their impact in an organ-specific context, providing insights into new potential therapeutic strategies tailored to clinical manifestations. Full article

The Colorado Potato Beetle (CPB, Leptinotarsa decemlineata Say, Coleoptera: Chrysomelidae) remains a destructive agricultural pest worldwide that continually overcomes conventional control methods. In recent years, RNA interference (RNAi) has emerged as an alternative for its management; however, although promising results have been reported, its effectiveness has been influenced by several factors, including the length of double-stranded RNA (dsRNA), the delivery method, stability, and especially the selection of the target gene. In this study, we designed and synthesized 290 bp dsRNAs targeting the SERCA and CPR genes from L. decemlineata, which encode the Sarco/Endoplasmic Reticulum Ca²⁺-ATPase and NADPH–Cytochrome P450 Reductase, respectively. Both dsRNAs successfully reduced transcript levels in larvae, with dsSERCA achieving ~60% knockdown by day 3 and dsCPR achieving ~50% knockdown by day 7. Furthermore, both treatments affected the larval growth and survival rate. However, while the dsCPR-treated larvae showed a 59% reduction in weight gain, the administration of dsSERCA had a strong phenotypic effect on the larvae, leading to decreased feeding, a 50.4% reduction in weight gain, and ultimately, 100% mortality. These results suggest that the SERCA and CPR genes could be promising targets for L. decemlineata control and emphasize the importance of appropriate target gene selection for RNAi silencing, as well as the need to explore and validate new genes for RNAi-mediated pest management. Full article

RBFOX1 is an RNA-binding protein that regulates alternative splicing and RNA processing in the neurons, skeletal muscle, and heart. We intended to define the role of RBFOX1 in regulating calcium homeostasis to maintain normal cardiac function. We generated cardiomyocyte-specific Rbfox1 gene-deletion mice (cKO). The cardiomyocyte-specific deletion of RBFOX1 was confirmed by Western blotting and immunohistochemistry. The cKO mice showed mild hypertrophy and depressed cardiac function under homeostatic conditions, which did not deteriorate with age. Pressure overload by trans-aortic constriction (TAC) caused exaggerated cardiac hypertrophy and accelerated heart failure in cKO compared with wild-type mice. We performed Western blotting to assess the expression of important Ca²⁺-handling proteins, which showed alterations in the phosphorylation of PLN and CAMKII and decreased expression of SERCA2. We measured the Ca²⁺ dynamics and noted significantly delayed Ca²⁺ reuptake into the sarcoplasmic reticulum. Importantly, the decrease in SERCA2 expression was not due to reduced mRNA expression or altered splicing. To assess the possibility of the post-transcriptional regulation of SERCA2 expression by RBFOX1, we performed RNA immunoprecipitation (RIP), which showed the binding of RBFOX1 protein to Serca2 mRNA, which was confirmed in luciferase assays with the Serca2a 3′-untranslated region fused to luciferase. Finally, we performed a puromycin incorporation experiment, which showed that RBFOX1 enhances SERCA2 protein translation. Our results show that RBFOX1 plays a crucial role in regulating the expression of Ca²⁺-handling genes to maintain normal cardiac function. We show an important post-transcriptional role of RBFOX1 in regulating SERCA2 expression. Full article

Background: The oviduct is an organ that participates in multiple critical reproductive processes and provides essential nutritional support while maintaining a specialized microenvironment. It is particularly vulnerable to damage following heat stress-induced hyperthermia. Therefore, mitigating heat-induced damage to oviduct epithelial cells while preserving their physiological integrity under hyperthermia represents a critical therapeutic goal. Objective: This study aims to simulate the cellular damage state in yak oviduct epithelial cells (YOECs) under thermal challenge by increasing the incubation temperature of cultured cells, while observing changes in cellular injury upon supplementation with 17β-estradiol (E₂), in order to explore the underlying cellular regulatory mechanisms involved. Results: After 48 h of exposure to 41 °C, YOECs exhibited elevated HSP70 and HSP90 protein expression levels, reduced OVGP1 protein expression, and increased apoptotic cells. Compared to the 41 °C group, the E₂ + 41 °C group displayed decreased HSP70 protein levels, increased OVGP1 protein expression, and reduced apoptotic cell numbers. Additionally, changes in endoplasmic reticulum calcium ion (ER-Ca²⁺) distribution and fluorescence intensity variations in ER-Ca²⁺ regulatory proteins SERCA and IP3R3 were analyzed in the 37 °C, 41 °C, and E₂ + 41 °C groups. The ER-Ca²⁺ distribution pattern in the E₂ + 41 °C group remained similar to that of the 37 °C group. However, the fluorescence intensity levels of SERCA and IP3R3 proteins in the E₂ + 41 °C group did not recover to levels comparable to the 37 °C group. Conclusion: These findings suggest that E₂ may mitigate thermal challenge-induced cellular damage in YOECs by maintaining ER-Ca²⁺ homeostasis, thereby preserving cellular functionality under elevated temperatures. Full article