Search Results (115)

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

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

Previous studies have demonstrated neuronal and microglial Fyn, a Src family kinase (SFK), and how its interactions with tau contribute to epileptogenesis. Saracatinib, a Fyn/SFK inhibitor, modifies disease progression in rat kainate (KA) epilepsy models. In this study, we investigated neuronal-specific fyn knockdown effects on Fyn–tau signaling, neurodegeneration, and gliosis using a calcium/calmodulin-dependent protein kinase II (CaMKII)-promoter-driven adeno-associated viral vector (AAV9)-mediated fyn-shRNA injection in the rat hippocampus. Eight days following AAV administration, rats received repeated low-dose KA injections intraperitoneally to induce status epilepticus (SE). Both fyn-shRNA and control groups showed comparable SE severity, indicating inadequate neuronal fyn knockdown at this timepoint. Two weeks post fyn-shRNA injection, hippocampal Fyn significantly decreased, alongside reductions in NR2B, pNR2B^Y1472, PSD95, and total tau. There was also a compensatory activation of SFK (pSFK^Y416:Fyn) and tau hyperphosphorylation (AT8:total tau), negatively correlating with NeuN expression. Proximity ligation assay indicated unchanged Fyn–tau interactions, suggesting tau interactions with alternative SH3 domain proteins. Persistent neuronal loss, astrogliosis, and microgliosis suggested limited effectiveness of neuronal-specific fyn knockdown at this timepoint. An extended-duration fyn knockdown study, or using broad SFK inhibitors such as saracatinib or tau-SH3 blocking peptides, may effectively prevent SE-induced epileptogenesis. 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

The electrophysiological mechanisms underlying melatonin’s actions and the electrophysiological consequences of superimposed therapeutic hypothermia (TH) in preventing cardiac ischemia-reperfusion (IR) injury-induced arrhythmias remain largely unknown. This study aimed to unveil these issues using acute IR-injured hearts. Rabbits were divided into heart failure (HF), HF+melatonin, control, and control+melatonin groups. HF was induced by rapid right ventricular pacing. Melatonin was administered orally (10 mg/kg/day) for four weeks, and IR was created by 60-min coronary artery ligation and 30-min reperfusion. The hearts were then excised and Langendorff-perfused for optical mapping studies at normothermia, followed by TH. Melatonin significantly reduced ventricular fibrillation (VF) maintenance. In failing hearts, melatonin reduced the spatially discordant alternans (SDA) inducibility mainly by modulating intracellular Ca²⁺ dynamics via upregulation of sarcoplasmic reticulum Ca²⁺-ATPase (SERCA2a) and calsequestrin 2 and attenuating the downregulation of phosphorylated phospholamban protein expression. In control hearts, melatonin improved conduction slowing and reduced dispersion of action potential duration (APD_dispersion) by upregulating phosphorylated connexin 43, attenuating the downregulation of SERCA2a and phosphorylated phospholamban and attenuating the upregulation of phosphorylated Ca²⁺/calmodulin-dependent protein kinase II. TH significantly retarded intracellular Ca²⁺ decay slowed conduction, and increased APD_dispersion, thereby facilitating SDA induction, which counteracted the beneficial effects of melatonin in reducing VF maintenance. 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

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

Insulin resistance (IR) is the principal pathophysiological change occurring in diabetes mellitus (DM). Baicalein, a bioactive flavonoid primarily extracted from the medicinal plant Scutellaria baicalensis Georgi, has been shown in our previous research to be a potential natural glucagon-like peptide-1 receptor (GLP-1R) agonist. However, the exact therapeutic effect of baicalein on DM and its underlying mechanisms remain elusive. In this study, we investigated the therapeutic effects of baicalein on diabetes and sought to clarify its underlying molecular mechanisms. Our results demonstrated that baicalein improves hyperglycemic, hyperinsulinemic, and glucometabolic disorders in mice with induced diabetes via GLP-1R. This was confirmed by the finding that baicalein’s effects on improving IR were largely diminished in mice with whole-body Glp1r ablation. Complementarily, network pharmacology analysis highlighted the pivotal involvement of the phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT) insulin signaling pathway in the therapeutic actions of baicalein on IR. Our mechanism research significantly confirmed that baicalein mitigates hepatic and muscular IR through the PI3K/AKT signal pathway, both in vitro and in vivo. Furthermore, we demonstrated that baicalein enhances glucose uptake in skeletal muscle cells under IR conditions through the Ca²⁺/calmodulin-dependent protein kinase II (CaMKII)-adenosine 5′-monophosphate-activated protein kinase (AMPK)-glucose transporter 4 (GLUT4) signaling pathway in a GLP-1R-dependent manner. In conclusion, our findings confirm the therapeutic effects of baicalein on IR and reveal that it improves IR in liver and muscle tissues through the PI3K/AKT insulin signaling pathway in a GLP-1R dependent manner. Moreover, we clarified that baicalein enhances the glucose uptake in skeletal muscle tissue through the Ca²⁺/CaMKII-AMPK-GLUT4 signal pathway. Full article

The effects of enhanced late I_Na, a persistent component of the Na⁺ channel current, on the intracellular ion dynamics and the automaticity of the pulmonary vein cardiomyocytes were studied with fluorescent microscopy. Anemonia viridis toxin II (ATX- II), an enhancer of late I_Na, caused increases in the basal Na⁺ and Ca²⁺ concentrations, increases in the number of Ca²⁺ sparks and Ca²⁺ waves, and the generation of repetitive Ca²⁺ transients. These phenomena were inhibited by eleclazine, a blocker of the late I_Na; SEA0400, an inhibitor of the Na⁺/Ca²⁺ exchanger (NCX); H89, a protein kinase A (PKA) inhibitor; and KN-93, a Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) inhibitor. These results suggest that enhancement of late I_Na in the pulmonary vein cardiomyocytes causes disturbance of the intracellular ion environment through activation of the NCX and Ca²⁺-dependent enzymes. Such mechanisms are probably involved in the ectopic electrical activity of the pulmonary vein myocardium. Full article

Sodium fluoride (NaF) is a fluoride application recommended by the World Health Organization for its efficacy and safety in preventing dental caries. Gingival fibroblasts that constitute the majority of connective tissue cells play a major role in wound healing via the expression of growth factors, including fibroblast growth factor-2 (FGF-2) and transforming growth factor-beta (TGF-β). This study examined the effect of NaF mouthwash on FGF-2 and TGF-β expression in human gingival fibroblasts (HGnFs). Fibroblasts were exposed to a medium with 225 ppmF NaF for 1 min, then switched to either 15 ppmF NaF for continuous stimulation or no NaF for transient stimulation. Continuous NaF stimulation significantly increased the gene and protein expression of FGF-2 and TGF-β in HGnFs compared to controls, suggesting NaF’s potential role in modulating periodontal tissue wound healing. Signaling pathway investigations showed the involvement of heterotrimeric GTP-binding proteins, calcium/calmodulin-dependent kinase II (CaMKII), and extracellular signal-regulated kinase (ERK) phosphorylation. Inhibiting CaMKII reduced NaF-induced FGF-2 and TGF-β expression, while ERK phosphorylation increased after NaF stimulation. These results highlight NaF mouthwash’s potential in promoting wound healing in extraction sockets, particularly during the mixed dentition period. Understanding NaF’s effects is clinically relevant due to the common use of fluoride products. Full article

Pediatric neuroblastomas (NBs) are heterogeneous, aggressive, therapy-resistant embryonal tumors that originate from cells of neural crest origin committed to the sympathoadrenal progenitor cell lineage. Stress- and drug-resistance mechanisms drive post-therapeutic relapse and metastatic progression, the characterization and inhibition of which are major goals in improving therapeutic responses. Stress- and drug-resistance mechanisms in NBs include alternative TrkAIII splicing of the neurotrophin receptor tropomyosin-related kinase A (NTRK1/TrkA), which correlates with post-therapeutic relapse and advanced-stage metastatic disease. The TrkAIII receptor variant exerts oncogenic activity in NB models by mechanisms that include stress-induced mitochondrial importation and activation. In this study, we characterize novel targetable and non-targetable participants in this pro-survival mechanism in TrkAIII-expressing SH-SY5Y NB cells, using dithiothreitol (DTT) as an activator and a variety of inhibitors by regular and immunoprecipitation Western blotting of purified mitochondria and IncuCyte cytotoxicity assays. We report that stress-induced TrkAIII misfolding initiates this mechanism, resulting in Grp78, Ca²⁺-calmodulin, adenosine ribosylating factor (Arf) and Hsp90-regulated mitochondrial importation. TrkAIII imported into inner mitochondrial membranes is cleaved by Omi/high temperature requirement protein A2 (HtrA2) then activated by a mechanism dependent upon calmodulin kinase II (CaMKII), alpha serine/threonine kinase (Akt), mitochondrial Ca²⁺ uniporter and reactive oxygen species (ROS), involving inhibitory mitochondrial protein tyrosine phosphatase (PTPase) oxidation, resulting in phosphoinositide 3 kinase (PI3K) activation of mitochondrial Akt, which enhances stress resistance. This novel pro-survival function for misfolded TrkAIII mitigates the cytotoxicity of mitochondrial Ca²⁺ homeostasis disrupted during integrated stress responses, and is prevented by clinically approved Trk and Akt inhibitors and also by inhibitors of 78kDa glucose regulated protein (Grp78), heat shock protein 90 (Hsp90), Ca²⁺-calmodulin and PI3K. This identifies Grp78, Ca²⁺-calmodulin, Hsp90, PI3K and Akt as novel targetable participants in this mechanism, in addition to TrkAIII, the inhibition of which has the potential to enhance the stress-induced elimination of TrkAIII-expressing NB cells, with the potential to improve therapeutic outcomes in NBs that exhibit TrkAIII expression and activation. Full article

The excessive activation of glutamate in the brain is a factor in the development of vascular dementia. γ-Oryzanol is a natural compound that has been shown to enhance brain function, but more research is needed to determine its potential as a treatment for vascular dementia. This study investigated if γ-oryzanol can delay or improve glutamate neurotoxicity in an in vitro model of differentiated HT-22 cells and explored its neuroprotective mechanisms. The differentiated HT-22 cells were treated with 0.1 mmol/L glutamate for 24 h then given γ-oryzanol at appropriate concentrations or memantine (10 µmol/L) for another 24 h. Glutamate produced reactive oxygen species and depleted glutathione in the cells, which reduced their viability. Mitochondrial dysfunction was also observed, including the inhibition of mitochondrial respiratory chain complex I activity, the collapse of mitochondrial transmembrane potential, and the reduction of intracellular ATP levels in the HT-22 cells. Calcium influx triggered by glutamate subsequently activated type II calcium/calmodulin-dependent protein kinase (CaMKII) in the HT-22 cells. The activation of CaMKII-ASK1-JNK MAP kinase cascade, decreased Bcl-2/Bax ratio, and increased Apaf-1-dependent caspase-9 activation were also observed due to glutamate induction, which were associated with increased DNA fragmentation. These events were attenuated when the cells were treated with γ-oryzanol (0.4 mmol/L) or the N-methyl-D-aspartate receptor antagonist memantine. The results suggest that γ-oryzanol has potent neuroprotective properties against glutamate excitotoxicity in differentiated HT-22 cells. Therefore, γ-oryzanol could be a promising candidate for the development of therapies for glutamate excitotoxicity-associated neurodegenerative diseases, including vascular dementia. Full article

Muscle regeneration, representing an essential homeostatic process, relies mainly on the myogenic progress of resident satellite cells, and it is modulated by multiple physical and nutritional factors. Here, we investigated how myogenic differentiation-related factors and pathways respond to the first limiting amino acid lysine (Lys) in the fast and slow muscles, and their satellite cells (SCs), of swine. Thirty 28-day-old weaned piglets with similar body weights were subjected to three diet regimens: control group (d 0–28: 1.31% Lys, n = 12), Lys-deficient group (d 0–28: 0.83% Lys, n = 12), and Lys rescue group (d 0–14: 0.83% Lys; d 15–28: 1.31% Lys, n = 6). Pigs on d 15 and 29 were selectively slaughtered for muscular parameters evaluation. Satellite cells isolated from fast (semimembranosus) and slow (semitendinosus) muscles were also selected to investigate differentiation ability variations. We found Lys deficiency significantly hindered muscle development in both fast and slow muscles via the distinct manipulation of myogenic regulatory factors and the Wnt/Ca²⁺ pathway. In the SC model, Lys deficiency suppressed the Wnt/Ca²⁺ pathways and myosin heavy chain, myogenin, and myogenic regulatory factor 4 in slow muscle SCs but stimulated them in fast muscle SCs. When sufficient Lys was attained, the fast muscle-derived SCs Wnt/Ca²⁺ pathway (protein kinase C, calcineurin, calcium/calmodulin-dependent protein kinase II, and nuclear factor of activated T cells 1) was repressed, while the Wnt/Ca²⁺ pathway of its counterpart was stimulated to further the myogenic differentiation. Lys potentially manipulates the differentiation of porcine slow and fast muscle myofibers via the Wnt/Ca²⁺ pathway in opposite trends. Full article

Purpose: It is well known that inhibition of Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) provides cardiac protection in cases of myocardial ischemia–reperfusion injury. However, there are currently no cytoplasm-impermeable drugs that target CaMKII. The aim of this study was to develop curcumin albumin nanoparticles (HSA-CCM NPs) containing AC3-I and investigate their protective effects on hypoxia–reoxygenation (H/R)-induced injuries in adult rat cardiomyocytes and ischemia–reperfusion (I/R) injuries in isolated rat hearts. Methods: HSA-CCM NPs were synthesized using β-ME methods, while the membrane-impermeable peptide AC3-I was covalently linked via a disulfide bond to synthesize AC3-I@HSA-CCM NPs (AC3-I@NPs). Nanoparticle stability and drug release were characterized. To assess the cardiomyocyte uptake of AC3-I@NPs, AC3-I@NPs were incubated with cardiomyocytes under normoxia and hypoxia, respectively. The cardioprotective effect of AC3-I@NPs was determined by using a lactate dehydrogenase kit (LDH) and PI/Hoechst staining. The phosphorylation of phospholamban (p-PLB) was detected by Western blotting in hypoxia–reoxygenation and electric field stimulation models. To further investigate the protective role of AC3-I@NPs against myocardial ischemia–reperfusion injury, we collected coronary effluents and measured creatine kinase (CK) and LDH release in Langendorff rat hearts. Results:AC3-I@NPs were successfully prepared and characterized. Both HSA-CCM NPs and AC3-I@NPs were taken up by cardiomyocytes. AC3-I@NPs protected cardiomyocytes from injury caused by hypoxia–reoxygenation, as demonstrated by decreased cardiomyocyte death and LDH release. AC3-I@NPs reduced p-PLB levels evoked by hypoxia–reoxygenation and electrical field stimulation in adult rat cardiac myocytes. AC3-I@NPs decreased the release of LDH and CK from coronary effluents. Conclusions: AC3-I@NPs showed protective effects against myocardial injuries induced by hypoxia–reoxygenation in cardiomyocytes and ischemia–reperfusion in isolated hearts. Full article