Search Results (184)

Forty per cent of major depression patients are resistant to antidepressant medication. Thus, it is necessary to search for alternative treatments. Melatonin (N-acetyl-5-hydroxytryptamine) enhances neurogenesis and neuronal survival in the adult mouse hippocampal dentate gyrus. Additionally, melatonin stimulates the activity of Ca²⁺/Calmodulin-dependent Kinase II (CaMKII), promoting dendrite formation and neurogenic processes in human olfactory neuronal precursors and rat organotypic cultures. Similarly, ketamine, an N-methyl-D-aspartate receptor (NMDAR) antagonist, modulates CaMKII activity. Importantly, co-treatment of low doses of ketamine (10⁻⁷ M) in combination with melatonin (10⁻⁷ M) produces additive effects on neurogenic responses in olfactory neuronal precursors. Importantly, enhanced neurogenic responses are produced by conventional antidepressants like ISSRs. The goal of this study was to investigate whether hippocampal CaMKII participates in the signaling pathway elicited by combining doses of melatonin with ketamine acutely administered to mice, 30 min before being subjected to the forced swimming test. The results showed that melatonin, in conjunction with ketamine, significantly enhances CaMKII activation and changes its subcellular distribution in the dentate gyrus of the hippocampus. Remarkably, melatonin causes nuclear translocation of the active form of CaMKII. Luzindole, a non-selective MT₁ and MT₂ receptor antagonist, abolished these effects, suggesting that CaMKII is downstream of the melatonin receptor pathway that causes the antidepressant-like effects. These findings provide molecular insights into the combined effects of melatonin and ketamine on neuronal plasticity-related signaling pathways and pave the way for combating depression using combination therapy. Full article

Reactive oxygen species (ROS) play a dual role as both essential signaling molecules and harmful mediators of damage. Imbalances in the redox state of the liver can overwhelm antioxidant defenses and promote mitochondrial dysfunction, oxidative damage, and inflammation. Complex feedback loops between ROS and immune signaling pathways are a hallmark of pathological liver conditions, such as hepatic ischemia–reperfusion injury (IRI). This is a major cause of liver transplant failure and is of increasing significance due to the increased use of marginally discarded livers for transplantation. This review outlines the major enzymatic and metabolic sources of ROS in hepatic IRI, including mitochondrial reverse electron transport, NADPH oxidases, cytochrome P450 enzymes, and endoplasmic reticulum stress. Hepatocyte injury activates redox feedback loops that initiate immune cascades through DAMP release, toll-like receptor signaling, and cytokine production. Emerging regulatory mechanisms, such as succinate accumulation and cytosolic calcium–CAMKII signaling, further shape oxidative dynamics. Pharmacological therapies and the use of antioxidant and immunomodulatory approaches, including nanoparticles and redox-sensitive therapeutics, are discussed as protective strategies. A deeper understanding of how redox and immune feedback loops interact is an exciting and active area of research that warrants further clinical investigation. Full article

The L-type calcium channels (LTCCs) function as the main entry points that convert myocyte membrane depolarization into calcium transients, which drive every heartbeat. There is increasing evidence to show that maladaptive remodeling of these channels is the cause of heart failure with reduced ejection fraction (HFrEF) and heart failure with preserved ejection fraction (HFpEF). Recent experimental, translational, and clinical studies have improved our understanding of the roles LTCC expression, micro-domain trafficking, and post-translational control have in disrupting excitation–contraction coupling, provoking arrhythmias, and shaping phenotype specific hemodynamic compromise. We performed a systematic search of the PubMed and Google Scholar databases (2015–2025, English) and critically evaluated 17 eligible publications in an effort to organize the expanding body of work. This review combines existing data about LTCC density and T-tubule architecture with β-adrenergic and Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) signaling and downstream sarcoplasmic reticulum crosstalk to explain how HFrEF presents with contractile insufficiency and how HFpEF shows diastolic calcium overload and stiffening. Additionally, we highlight the emerging therapeutic strategies aimed at restoring calcium homeostasis such as CaMKII inhibitors, ryanodine receptor type 2 (RyR2) stabilizers, and selective LTCC modulators without compromising systolic reserve. The review establishes LTCC dysregulation as a single mechanism that causes myocardial dysfunction while remaining specific to each phenotype, thus offering clinicians and researchers a complete reference for current concepts and future precision therapy approaches in heart failure. Full article

Background/Objectives: Type 2 diabetes mellitus (T2DM) is a major global health challenge, primarily driven by insulin resistance and beta-cell dysfunction. This study investigated the roles of p21-activated kinase 1 (PAK1) and calcium/calmodulin-dependent protein kinase II (CAMKII) in insulin secretion, aiming to elucidate their involvement in this process and their implications in T2DM pathophysiology. Methods: Using the Beta-TC-6 insulinoma cell line, we assessed colocalization and interaction of PAK1 and CAMKII under glucose stimulation through indirect immuno-fluorescence (IFI) and proximity ligation assays (PLA). To examine their expression dynamics in a physiological context, we performed immunohistochemistry (IHC) on pancreatic sections from wild-type (WT), prediabetic, and T2DM murine models. Additionally, bioinformatic analysis of publicly available RNA sequencing (RNA-Seq) data from human islets of healthy donors, prediabetic individuals, and T2DM patients provided translational validation. Results: High glucose conditions significantly increased PAK1-CAMKII colocalization, correlating with enhanced insulin secretion. Pharmacological inhibition of these kinases reduced insulin release, confirming their regulatory roles. Murine and human islet analyses showed a progressive increase in kinase expression from prediabetes to T2DM, highlighting their relevance in disease progression. Conclusions: The coordinated function of PAK1 and CaMKII in insulin secretion suggests their potential as biomarkers and therapeutic targets in T2DM. Further studies are warranted to explore their mechanistic roles and therapeutic applications in preserving beta-cell function. 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

Introduction: This case report examines the impact of a novel combined neuromuscular electrical stimulation (Comb-NMES) regimen on muscle glucose signaling, fiber type distribution, and metabolic function in a patient with acute spinal cord injury (SCI) and lower motor neuron lesions (LMNLs). Case Report: A 32-year-old male with complete T9 SCI underwent a ten-session Comb-NMES intervention targeting the quadriceps. Muscle biopsies and blood samples were analyzed pre- and post-intervention to evaluate changes in muscle fiber types, key metabolic proteins, fasting insulin, glucose, and lipid profiles. Results: The intervention led to a 74.7% and 28.2% reduction in fasting insulin and glucose, respectively. Muscle analysis showed significant increases in CaMK II, Hexokinase II, and IRS-1, indicating improved glucose metabolism. Conclusions: Comb-NMES training markedly improved metabolic control and muscle glucose metabolism in a patient with acute SCI and LMNLs. Enhanced insulin sensitivity and glucose utilization were evidenced by upregulated metabolic proteins, which suggests that Comb-NMES is a promising intervention for improving muscle and metabolic health in SCI patients with LMNLs. Further studies are needed to confirm these benefits and explore the long-term effects. Full article

During skeletal muscle unloading, phosphoinositide 3-kinase (PI3K), and especially PI3K gamma (PI3Kγ), can be activated by changes in membrane potential. Activated IP3 can increase the ability of Ca²⁺ to enter the nucleus through IP3 receptors. This may contribute to the activation of transcription factors that initiate muscle atrophy processes. LY294002 inhibitor was used to study the role of PI3K in the ATP-dependent regulation of skeletal muscle signaling during three days of unloading. Inhibition of PI3K during soleus muscle unloading slows down the atrophic processes and prevents the accumulation of ATP and the expression of the E3 ubiquitin ligase MuRF1 and ubiquitin. It also prevents the increase in the expression of IP3 receptors and regulates the activity of Ca²⁺-dependent signaling pathways by reducing the mRNA expression of the Ca²⁺-dependent marker calcineurin (CaN) and decreasing the phosphorylation of CaMKII. It also affects the regulation of markers of anabolic signaling in unloaded muscles: IRS1 and 4E-BP. PI3K is an important mediator of skeletal muscle atrophy during unloading. Developing strategies for the localized skeletal muscle release of PI3K inhibitors might be one of the future treatments for inactivity and disease-induced muscle atrophy. Full article

Irbesartan improves ventricular remodeling (VR) following myocardial infarction (MI). This study investigates whether irbesartan attenuates VR by reducing aldosterone production in the heart and its underlying mechanisms. MI was induced in male Sprague–Dawley rats through coronary artery ligation. The MI rats were randomly assigned to two groups: one received a vehicle, and the other received 100 mg/kg/day of irbesartan for 5 weeks. Cardiac function and myocardial fibrosis were assessed using echocardiography and Masson’s trichrome staining, respectively. The impact of angiotensin II (Ang II) stimulation on cardiac microvascular endothelial cells (CMECs) from commercial sources was determined using ELISA, real-time PCR, and Western blotting. Irbesartan reduced left ventricular mass index, collagen composition, and aldosterone levels while enhancing cardiac function in MI rats. In vitro, Ang II time-dependently stimulated aldosterone secretion and CYP11B2 mRNA expression in CMECs (p < 0.05). Additionally, Ang II significantly upregulated p-CREB protein levels. However, these effects were abrogated by irbesartan and partially attenuated by CaMK inhibitor KN93 (p < 0.05). In conclusion, our study demonstrated that improvement in VR by irbesartan coincided with reduced CREB phosphorylation in CMECs and reduced aldosterone synthesis in the non-infarcted tissue. These effects may be mediated by blocking the AT1 receptor. Full article

The spontaneous firing of the sinoatrial (SA) node, the physiological pacemaker of the heart, is generated within sinoatrial nodal cells (SANCs) and is regulated by a “coupled-clock” pacemaker system, which integrates a “membrane clock”, the ensemble of ion channel currents, and an intracellular “Ca²⁺ clock”, sarcoplasmic reticulum-generated local submembrane Ca²⁺ releases via ryanodine receptors. The interactions within a “coupled-clock” system are modulated by phosphorylation of surface membrane and sarcoplasmic reticulum proteins. Though the essential role of a high basal cAMP level and PKA-dependent phosphorylation for basal spontaneous SANC firing is well recognized, the role of basal CaMKII-dependent phosphorylation remains uncertain. This is a critical issue with respect to how cardiac pacemaker cells fire spontaneous action potentials. This review aspires to explain and unite apparently contradictory results of pharmacological studies in the literature that have demonstrated a fundamental role of basal CaMKII activation for basal cardiac pacemaker function, as well as studies in mice with genetic CaMKII inhibition which have been interpreted to indicate that basal spontaneous SANC firing is independent of CaMKII activation. The assessment of supporting and opposing data regarding CaMKII effects on phosphorylation of Ca²⁺-cycling proteins and spontaneous firing of SANC in the basal state leads to the necessary conclusion that CaMKII activity and CaMKII-dependent phosphorylation do regulate basal cardiac pacemaker function. Full article

Chronic exposure to high altitudes causes pathophysiological cardiac changes that are characterized by cardiac dysfunction, cardiac hypertrophy, and decreased energy reserves. However, finding specific pharmacological interventions for these pathophysiological changes is challenging. In this study, we identified tetramethylpyrazine (TMP) as a promising drug candidate for cardiac dysfunction caused by simulated high-altitude exposure. By utilizing hypobaric chambers to simulate high-altitude environments, we found that TMP improved cardiac function, alleviated cardiac hypertrophy, and reduced myocardial injury in hypobaric hypoxic mice. RNA sequencing showed that TMP also upregulated heart-contraction-related genes that were suppressed by hypobaric hypoxia exposure. Mechanistically, TMP inhibited hypobaric hypoxia-induced cardiac Ca²⁺/calmodulin-dependent kinase II (CaMKII) activation and exerted cardioprotective effects by inhibiting CaMKII. Our data suggest that TMP application may be a promising approach for treating high-altitude-induced cardiac dysfunction, and they highlight the crucial role of CaMKII in hypobaric hypoxia-induced cardiac pathophysiology. Full article

Aggressiveness is one of the personality traits of crustaceans, playing a crucial role in their growth, life history, and adaptability by influencing resource acquisition. However, the neuroregulatory mechanisms of aggressiveness in crustaceans remain poorly understood. The thoracic ganglion offers valuable insights into complementary aspects of aggression control. This study identified the aggressiveness of swimming crabs Portunus trituberculatus, conducted transcriptomic and metabolomic analyses of the thoracic ganglia, and confirmed the neural regulatory effects on aggressiveness. Behavioral analyses showed that highly aggressive individuals exhibited increased frequency and duration of chela extension, more frequent attacks, approaches and retreats, as well as extended movement distances. Omics analysis revealed 11 key candidate genes and three metabolites associated with aggressiveness, which were primarily enriched in pathways related to energy metabolism and neurodegeneration. Injection of an NMDAR activator significantly decreased aggressiveness in highly aggressive crabs, accompanied by a significant increase in NMDAR protein fluorescence intensity and downregulation of NR2B, CaMKII, and CREB genes. Conversely, when lowly aggressive crabs were injected with an NMDAR inhibitor, they showed increased aggressiveness alongside significantly decreased NMDAR protein fluorescence intensity, upregulated NR2B expression, and downregulated CaMKII and CREB genes. These results suggest that NMDAR within the thoracic ganglia serves as a key receptor in modulating aggressiveness in P. trituberculatus, potentially by influencing neural energy state via the NMDAR-CaMKII pathway, which in turn affects oxidative phosphorylation, cAMP, and FoxO pathways. Full article

Denervation-induced calcium/calmodulin-dependent protein kinase II (CaMKII) activation and inflammation can result in muscle atrophy. Curcumin and bisdemethoxycurcumin are well known to exhibit an anti-inflammatory effect. In addition, curcumin has been shown to attenuate CaMKII activation in neuronal cells. This study aimed to examine the effect of curcumin or bisdemethoxycurcumin on CaMKII activation, inflammation, and muscle cross-sectional area (CSA) in spinal nerve ligated rats. Sixteen female rats were assigned to sham (CON), spinal nerve ligation (SNL), SNL+ curcumin 100 mg/kg BW (100CUR), and SNL+ bisdemethoxycurcumin 50 mg/kg BW (50CMO) for 4 weeks. Ipsilateral (surgical) soleus and tibialis anterior (TA) muscles was stained for dystrophin to measure CSA. Ipsilateral and contralateral (non-surgical) plantaris muscles were analyzed for protein content for acetylcholine receptor (AChR), CaMKII, CaMKII^Thr286, nuclear factor-κB (NF-κB), NF-κB^Ser536, and interleukin-1β (IL-1β) and normalized to α-tubulin and then CON. A significant (p < 0.050) group effect was observed for TA CSA where CON (11,082.25 ± 1617.68 μm²; p < 0.001) and 100CUR (9931.04 ± 2060.87 μm²; p = 0.018) were larger than SNL (4062.25 ± 151.86 μm²). In the ipsilateral plantaris, the SNL (4.49 ± 0.69) group had greater CaMKII activation compared to CON (1.00 ± 0.25; p = 0.010), 100CUR (1.12 ± 0.45; p = 0.017), and 50CMO (0.78 ± 0.19; p = 0.009). The ipsilateral plantaris (2.11 ± 0.66) had greater IL-1β protein content than the contralateral leg (0.65 ± 0.14; p = 0.041) in the SNL group. In plantaris, the SNL (1.65 ± 0.51) group had greater NF-κB activation compared to CON (1.00 ± 0.29; p = 0.021), 100CUR (0.61 ± 0.10; p = 0.003), 50CMO (0.77 ± 0.25; p = 0.009) groups. The observed reduction in Ca²⁺ signaling and inflammation in type II plantaris muscle fibers might reflect the changes within the type II TA muscle fibers which may contribute to the mitigation of TA mass loss with curcumin supplementation. Full article

A pervasive exposure to stressors and the consumption of fructose-containing beverages usually go hand-in-hand in everyday life. In contrast to their metabolic outcomes, their impact on the brain and behavior is still understudied. We examined the behavioral response to a novelty (open field test), the expression of biochemical indicators of neuronal activity (Egr1 and FosB/ΔFosB), the synaptic potentiation (CaMKIIα and pCaMKII^Thr286), the synaptic plasticity (synaptophysin, PSD95, gephyrin, and drebrin), and the GABAergic system (parvalbumin and GAD67), along with the glucocorticoid receptor (GR) and AMPK, in the medial prefrontal cortex of female Wistar rats subjected to liquid fructose supplementation (F), chronic unpredictable stress (S), or both (SF) over 9 weeks. The only hallmark of the F group was an increased expression of pCaMKII^Thr286, which was also observed in the S group, but not in the SF group. The SF group did not show hyperactivity, a decreased expression of FosB, or an increased expression of parvalbumin, as the S group did. The SF group, as with the S group, showed a decreased expression of the GR, although the basal level of corticosterone was unchanged. The SF group showed, as de novo marks, thigmotactic behavior, increased drebrin, and decreased gephyrin expression. These findings suggest that the long-term consumption of fructose, which itself has subtle neurobehavioral consequences, in combination with stress prevents some of its effects, but also contributes to novel outcomes not seen in single treatments. Full article

Several ion currents in the mammalian ventricular myocardium are substantially regulated by the sympathetic nervous system via β-adrenergic receptor activation, including the slow delayed rectifier K⁺ current and the L-type calcium current. This study investigated the downstream mechanisms of β-adrenergic receptor stimulation by isoproterenol (ISO) on the inward rectifier (I_K1) and the rapid delayed rectifier (I_Kr) K⁺ currents using action potential voltage clamp (APVC) and conventional voltage clamp techniques in isolated canine left ventricular cardiomyocytes. I_K1 and I_Kr were dissected by 50 µM BaCl₂ and 1 µM E-4031, respectively. Acute application of 10 nM ISO significantly increased I_K1 under the plateau phase of the action potential (0–+20 mV) using APVC, and similar results were obtained with conventional voltage clamp. However, β-adrenergic receptor stimulation did not affect the peak current density flowing during terminal repolarization or the overall I_K1 integral. The ISO-induced enhancement of I_K1 was blocked by the calcium/calmodulin kinase II (CaMKII) inhibitor KN-93 (1 µM) but not by the protein kinase A inhibitor H-89 (3 µM). Neither KN-93 nor H-89 affected the I_K1 density under baseline conditions (in the absence of ISO). In contrast, parameters of the I_Kr current were not affected by β-adrenergic receptor stimulation with ISO. These findings suggest that sympathetic activation enhances I_K1 in canine left ventricular cells through the CaMKII pathway, while I_Kr remains unaffected under the experimental conditions used. Full article

Ras homolog family member A (RhoA) acts as a signaling hub in many cellular processes, including cytoskeletal dynamics, division, migration, and adhesion. RhoA activity is tightly spatiotemporally controlled, but whether downstream effectors share these activation dynamics is unknown. We developed a novel single-color FRET biosensor to measure Rho-associated kinase (ROCK) activity with high spatiotemporal resolution in live cells. We report the validation of the Rho-Kinase Activity Reporter (RhoKAR) biosensor. RhoKAR activation was specific to ROCK activity and was insensitive to PKA activity. We then assessed the mechanisms of ROCK activation in mouse fibroblasts. Increasing intracellular calcium with ionomycin increased RhoKAR activity and depleting intracellular calcium with EGTA decreased RhoKAR activity. We also investigated the signaling intermediates in this process. Blocking calmodulin or CaMKII prevented calcium-dependent activation of ROCK. These results indicate that ROCK activity is increased by calcium in fibroblasts and that this activation occurs downstream of CaM/CaMKII. Full article