Oxidant stress promotes disease by activating CaMKII

Unveiling the role of CaMKII in retinal degeneration: from biological mechanism to therapeutic strategies

Ca2+/calmodulin-dependent protein kinase II (CaMKII) is a family of broad substrate specificity serine (Ser)/threonine (Thr) protein kinases that play a crucial role in the Ca2+-dependent signaling pathways. Its significance as an intracellular Ca2+ sensor has garnered abundant research interest in the domain of neurodegeneration. Accumulating evidences suggest that CaMKII is implicated in the pathology of degenerative retinopathies such as diabetic retinopathy (DR), age-related macular degeneration (AMD), retinitis pigmentosa (RP) and glaucoma optic neuropathy. CaMKII can induce the aberrant proliferation of retinal blood vessels, influence the synaptic signaling, and exert dual effects on the survival of retinal ganglion cells and pigment epithelial cells. Researchers have put forth multiple therapeutic agents, encompassing small molecules, peptides, and nucleotides that possess the capability to modulate CaMKII activity. Due to its broad range isoforms and splice variants therapeutic strategies seek to inhibit specifically the CaMKII are confronted with considerable challenges. Therefore, it becomes crucial to discern the detrimental and advantageous aspects of CaMKII, thereby facilitating the development of efficacious treatment. In this review, we summarize recent research findings on the cellular and molecular biology of CaMKII, with special emphasis on its metabolic and regulatory mechanisms. We delve into the involvement of CaMKII in the retinal signal transduction pathways and discuss the correlation between CaMKII and calcium overload. Furthermore, we elaborate the therapeutic trials targeting CaMKII, and introduce recent developments in the zone of CaMKII inhibitors. These findings would enrich our knowledge of CaMKII, and shed light on the development of a therapeutic target for degenerative retinopathy.

Aqueous Ozone Exposure Inhibits Sporulation in the Cyclospora cayetanensis Surrogate Eimeria acervulina

Ozone is a potent disinfecting agent used to treat potable water and wastewater, effectively clearing protozoa such as Giardia and Cryptosporidium spp. It is unclear whether ozone treatment of water or fresh produce can reduce the spread of the emerging parasite Cyclospora cayetanensis, which causes cyclosporiasis in humans. Obtaining viable C. cayetanensis oocysts to evaluate inactivation methods is challenging because we lack the means to propagate them in vitro, because of delays in case reporting, and because health departments typically add inactivating fixatives to clinical specimens. Research in various surrogate organisms has sought to bolster understanding of the biology of C. cayetanensis. Among these surrogates is the poultry parasite Eimeria acervulina, a closely related and easily cultured parasite of economic significance. We used this surrogate to evaluate the consequences of ozone treatment, using the sporulation state as an indicator of infectious potential. Treating with ozonated water acidified with citric acid reduced sporulation ability in a dose-dependent manner; treatment with up to 4.93 mg/L initial concentration of ozone resulted in a 93% inactivation of sporulation by 7 days posttreatment. This developmental arrest was accompanied by transcriptional changes in genes involved in regulating the response to reactive oxygen species (ROS) in a time course that is consistent with the production of oxygen free radicals. This study shows that ozone is highly effective in preventing sporulation of E. acervulina, a model coccidian used as a surrogate for Cyclospora. Furthermore, ozone exposure induced molecular responses to general oxidative stress, documented with several well-characterized antioxidant enzymes.

CaMKII activity and metabolic imbalance-related neurological diseases: Focus on vascular dysfunction, synaptic plasticity, amyloid beta accumulation, and lipid metabolism

Metabolic syndrome (MetS) is characterized by insulin resistance, hyperglycemia, excessive fat accumulation and dyslipidemia, and is known to be accompanied by neuropathological symptoms such as memory loss, anxiety, and depression. As the number of MetS patients is rapidly increasing globally, studies on the mechanisms of metabolic imbalance-related neuropathology are emerging as an important issue. Ca2+/calmodulin-dependent kinase II (CaMKII) is the main Ca2+ sensor and contributes to diverse intracellular signaling in peripheral organs and the central nervous system (CNS). CaMKII exerts diverse functions in cells, related to mechanisms such as RNA splicing, reactive oxygen species (ROS) generation, cytoskeleton, and protein-protein interactions. In the CNS, CaMKII regulates vascular function, neuronal circuits, neurotransmission, synaptic plasticity, amyloid beta toxicity, lipid metabolism, and mitochondrial function. Here, we review recent evidence for the role of CaMKII in neuropathologic issues associated with metabolic disorders.

Innovative pathological network-based multitarget approaches for Alzheimer's disease treatment

Alzheimer's disease (AD) is the most prevalent neurodegenerative disease and is a major health threat globally. Its prevalence is forecasted to exponentially increase during the next 30 years due to the global aging population. Currently, approved drugs are merely symptomatic, being ineffective in delaying or blocking the relentless disease advance. Intensive AD research describes this disease as a highly complex multifactorial disease. Disclosure of novel pathological pathways and their interconnections has had a major impact on medicinal chemistry drug development for AD over the last two decades. The complex network of pathological events involved in the onset of the disease has prompted the development of multitarget drugs. These chemical entities combine pharmacological activities toward two or more drug targets of interest. These multitarget-directed ligands are proposed to modify different nodes in the pathological network aiming to delay or even stop disease progression. Here, we review the multitarget drug development strategy for AD during the last decade.

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.

Similarities and Differences of Vascular Calcification in Diabetes and Chronic Kidney Disease

Presently, the mechanism of occurrence and development of vascular calcification (VC) is not fully understood; a range of evidence suggests a positive association between diabetes mellitus (DM) and VC. Furthermore, the increasing burden of central vascular disease in patients with chronic kidney disease (CKD) may be due, at least in part, to VC. In this review, we will review recent advances in the mechanisms of VC in the context of CKD and diabetes. The study further unveiled that VC is induced through the stimulation of pro-inflammatory factors, which in turn impairs endothelial function and triggers similar mechanisms in both disease contexts. Notably, hyperglycemia was identified as the distinctive mechanism driving calcification in DM. Conversely, in CKD, calcification is facilitated by mechanisms including mineral metabolism imbalance and the presence of uremic toxins. Additionally, we underscore the significance of investigating vascular alterations and newly identified molecular pathways as potential avenues for therapeutic intervention.

Corilagin inhibits angiotensin II-induced atrial fibrosis and fibrillation in mice through the PI3K-Akt pathway

Objectives

Corilagin (Cor) is reported as beiing hepatoprotective, anti-inflammatory, antibacterial, and anti-oxidant, while the effect on atrial fibrosis remains unknown. Therefore, we investigated the protective effect of Cor in angiotensin II (Ang II)-induced atrial fibrosis and atrial fibrillation (AF).

Materials and Methods

C57BL/6 mice (male, 8-10 weeks, n = 40) were subcutaneously infused either with saline or Ang II (2.0 mg/kg/day) and Cor (30 mg/kg) intraperitoneally injected 2 hr before Ang II infusion for 4 weeks. Mice were grouped into the control group (n=8), Cor group (n=8), Ang II group (n=8), and Ang II + Cor group (n=8). Morphological, histological, and biochemical examinations were performed. In vivo, transesophageal burst pacing was used to generate AF.

Results

Cor treatment markedly reduced Ang II-induced AF development in mice. Ang II + Cor therapy potentially decreased the atrial fibrotic area. It significantly decreased the increase in smooth muscle alpha-actin (α-SMA), CTGF, Collagen I, and Collagen III expressions brought on by Ang II treatment. Moreover, Ang II + Cor treatment remarkably decreased the malondialdehyde (MDA) content, whereas superoxide dismutase (SOD) and catalase (CAT) activities were potentially increased (all, P<0.001). In addition, Ang II + Cor significantly reduced Ang II-induced interleukin 1 beta (IL-1β), interleukin 6 (IL-6), and tumor necrosis factor-alpha (TNF-α) concentrations in atrial tissues. Furthermore, Cor significantly inhibited Ang II-induced p-PI3K, p-Akt, and NF-κB p-p65 protein expression in atrial tissues.

Conclusion

Our data speculated that Cor could have a protective effect against Ang II-induced atrial fibrosis and AF via down-regulation of the PI3K-Akt pathway.

Glucose fluctuations aggravated the late sodium current induced ventricular arrhythmias via the activation of ROS/CaMKII pathway

BACKGROUND

Recent evidence revealed that glucose fluctuation might be more likely to cause arrhythmia than persistent hyperglycemia, whereas its mechanisms were elusive. We aimed to investigate the effect of glucose fluctuation on the occurrence of ventricular arrhythmia and its mechanism.

METHODS

Streptozotocin (STZ) induced diabetic rats were randomized to five groups: the controlled blood glucose (C-STZ) group, uncontrolled blood glucose (U-STZ) group, fluctuated blood glucose (GF-STZ) group, and GF-STZ rats with 100 mg/kg Tempol (GF-STZ + Tempol) group or with 5 mg/kg KN93 (GF-STZ + KN93) group. Six weeks later, the susceptibility of ventricular arrhythmias and the electrophysiological dysfunctions of ventricular myocytes were evaluated using electrocardiogram and patch-clamp technique, respectively. The levels of reactive oxygen species (ROS) and oxidized CaMKII (ox-CaMKII) were determined by fluorescence assay and Western blot, respectively. Neonatal rat cardiomyocytes and H9C2 cells in vitro were used to explore the underlying mechanisms.

RESULTS

The induction rate of ventricular arrhythmias was 10%, 55%, and 90% in C-STZ group, U-STZ group, and GF-STZ group, respectively (P < 0.05). The electrophysiological dysfunctions of ventricular myocytes, including action potential duration at repolarization of 90% (APD90), APD90 short-term variability (APD90-STV), late sodium current (INa-L), early after depolarization (EAD) and delayed after depolarizations (DAD), as well as the levels of ROS and ox-CaMKII, were significantly increased in GF-STZ group. In vivo and ex vivo, inhibition of ROS or ox-CaMKII reversed these effects. Inhibition of INa-L also significantly alleviated the electrophysiological dysfunctions. In vitro, inhibition of ROS increase could significantly decrease the ox-CaMKII activation induced by glucose fluctuations.

CONCLUSIONS

Glucose fluctuations aggravated the INa-L induced ventricular arrhythmias though the activation of ROS/CaMKII pathway.

Quercetin alleviates zearalenone-induced apoptosis and necroptosis of porcine renal epithelial cells by inhibiting CaSR/CaMKII signaling pathway

Zearalenone (ZEA) is a mycotoxin that is highly contaminated in feed and can cause severe toxic effects on the kidneys and other organs of animals. Quercetin (QUE) is a plant-derived flavonoid with a variety of detoxification properties, but the mechanism by which QUE detoxifies the toxic effects induced by ZEA has not yet been fully elucidated. We treated porcine kidney cells (PK15) with 80 μM ZEA and/or 30 μM QUE. The results showed that ROS and MDA levels were increased, antioxidant system levels were down-regulated, anti-apoptotic factor expression levels were decreased, and apoptotic and necroptosis-related factors were up-regulated after ZAE exposure. In addition, the results of Ca2+ staining, mitochondrial membrane potential, and mitochondrial dynamics-related indicators showed that ZEA induced Ca2+ overload in PK15 cells and increased mitochondrial Ca2+ uptake (MCU expression increased). The accumulated ROS and free Ca2+ further aggravate mitochondrial damage and eventually lead to mitochondrial pathway apoptosis and necroptosis. Nevertheless, QUE targets CaSR to inhibit the CaSR/CaMKII pathway and regulate calcium homeostasis, thereby alleviating apoptosis and necroptosis mediated by mitochondrial dynamic disorder and dysfunction. The present study demonstrated the mechanism by which ZEA induces apoptosis and necroptosis in PK15 and the protective role of QUE in this process.

Differential Effects of High Fat Diets on Resilience to H2O2-Induced Cell Death in Mouse Cerebral Arteries: Role for Processed Carbohydrates

High fat, western-style diets increase vascular oxidative stress. We hypothesized that smooth muscle cells and endothelial cells adapt during the consumption of high fat diets to become more resilient to acute oxidative stress. Male C57Bl/6J mice were fed a western-style diet high in fat and processed carbohydrates (WD), a high fat diet that induces obesity (DIO), or their respective control (CD) and standard (SD) diets for 16 weeks. Posterior cerebral arteries (PCAs) were isolated and pressurized for study. During acute exposure to H₂O₂ (200 µM), smooth muscle cell and endothelial cell death were reduced in PCAs from WD, but not DIO mice. WD selectively attenuated mitochondrial membrane potential depolarization and vessel wall Ca²⁺ influx during H₂O₂ exposure. Selective inhibition of transient receptor potential (TRP) V4 or TRPC3 channels reduced smooth muscle cell and endothelial cell death in concert with the vessel wall [Ca²⁺]_i response to H₂O₂ for PCAs from CD mice and eliminated differences between CD and WD. Inhibiting Src kinases reduced smooth muscle cell death along with [Ca²⁺]_i response to H₂O₂ only in PCAs from CD mice and eliminated differences between diets. However, Src kinase inhibition did not alter endothelial cell death. These findings indicate that consuming a WD, but not high fat alone, leads to adaptations that limit Ca²⁺ influx and vascular cell death during exposure to acute oxidative stress.

Impaired intracellular calcium homeostasis enhances protein O-GlcNAcylation and promotes vascular calcification and stiffness in diabetes

Vascular calcification is accelerated in patients with diabetes mellitus and increases risk of cardiovascular events and mortality. Vascular smooth muscle cells (VSMC) play a key role in regulating vascular tone and contribute significantly to the development of diabetic vasculopathy. In this study, the function of stromal interaction molecule 1 (STIM1), an important regulator for intracellular calcium homeostasis, in diabetic vascular calcification was investigated, and the underlying molecular mechanisms were uncovered. A SMC-specific STIM1 deletion mouse model (STIM1Δ/Δ) was generated by breeding the STIM1 floxed mice (STIM1f/f) with SM22α-Cre transgenic mice. Using aortic arteries from the STIM1Δ/Δ mice and their STIM1f/f littermates, we found that SMC-specific STIM1 deletion induced calcification of aortic arteries cultured in osteogenic media ex vivo. Furthermore, STIM1 deficiency promoted osteogenic differentiation and calcification of VSMC from the STIM1Δ/Δ mice. In the low-dose streptozotocin (STZ)-induced mouse model of diabetes, SMC-specific STIM1 deletion markedly enhanced STZ-induced vascular calcification and stiffness in the STIM1Δ/Δ mice. The diabetic mice with SMC-specific STIM1 ablation also exhibited increased aortic expression of the key osteogenic transcription factor, Runx2, and protein O-GlcNAcylation, an important post-translational modulation that we have reported to promote vascular calcification and stiffness in diabetes. Consistently, elevation of O-GlcNAcylation was demonstrated in aortic arteries and VSMC from the STIM1Δ/Δ mice. Inhibition of O-GlcNAcylation with a pharmacological inhibitor abolished STIM1 deficiency-induced VSMC calcification, supporting a critical role of O-GlcNAcylation in mediating STIM1 deficiency-induced VSMC calcification. Mechanistically, we identified that STIM1 deficiency resulted in impaired calcium homeostasis, which activated calcium signaling and increased endoplasmic reticulum (ER) stress in VSMC, while inhibition of ER stress attenuated STIM1-induced elevation of protein O-GlcNAcylation. In conclusion, the study has demonstrated a causative role of SMC-expressed STIM1 in regulating vascular calcification and stiffness in diabetes. We have further identified a novel mechanisms underlying STIM1 deficiency-induced impairment of calcium homeostasis and ER stress in upregulation of protein O-GlcNAcylation in VSMC, which promotes VSMC osteogenic differentiation and calcification in diabetes.

Tilianin improves cognition in a vascular dementia rodent model by targeting miR-193b-3p/CaM- and miR-152-3p/CaMKIIα-mediated inflammatory and apoptotic pathways

Introduction

Although vascular dementia (VaD) is the second most prevalent form of dementia, there is currently a lack of effective treatments. Tilianin, isolated from the traditional drug Dracocephalum moldavica L., may protect against ischemic injury by inhibiting oxidative stress and inflammation via the CaMKII-related pathways but with weak affinity with the CaMKII molecule. microRNAs (miRNAs), functioning in post-transcriptional regulation of gene expression, may play a role in the pathological process of VaD via cognitive impairment, neuroinflammatory response, and neuronal dysfunction. This study aimed to investigate the role of tilianin in VaD therapy and the underlying mechanism through which tilianin regulates CaMKII signaling pathways based on miRNA-associated transcriptional action.

Methods

Rats with 2-vessel occlusion (2VO), a standard model of VaD, were treated with tilianin, vehicle control, and target overexpression or downregulation. High-throughput sequencing, qRT-PCR, and western blot analyses were utilized to identify the downstream target genes and signaling pathways of tilianin involved in VaD.

Results

Our results showed that tilianin ameliorated cognitive deficits, neurodegeneration, and microglial and astrocytic activation in rats with 2VO. Subsequent high-throughput sequencing and qRT-PCR analyses revealed that tilianin increased the downregulated miR-193b-3p and miR-152-3p levels in the cortex and hippocampus of 2VO rats. Mechanistically, miR-193b-3p targeting CaM and miR-152-3p targeting CaMKIIα were identified to play a role in VaD-associated pathology, inhibiting the p38 MAPK/NF--κB p65 pathway and decreasing TNF-α and IL-6 levels. Further gain- and loss-of-function experiments for these key genes showed that tilianin-exerted cognitive improvement by activating the p38 MAPK/NF--κB p65 and Bcl-2/Bax/caspase-3/PARP pathways in the brain of 2VO rats was abolished by miR-193b-3p and miR-152-3p inhibition. Moreover, CaM and CaMKIIα overexpression eliminated the elevated effects of miR-193b-3p and miR-152-3p on tilianin's protection against ischemic injury through increased inflammatory reactions and apoptotic signaling.

Discussion

Together, these findings indicate that tilianin improves cognition by regulating the miR-193b-3p/CaM- and miR-152-3p/CaMKIIα-mediated inflammatory and apoptotic pathways, suggesting a potential small-molecule regulator of miRNA associated with inflammatory signaling for VaD treatment.

Novel preventive effect of isorhamnetin on electrical and structural remodeling in atrial fibrillation

Isorhamnetin, a natural flavonoid, has strong antioxidant and antifibrotic effects, and a regulatory effect against Ca2+-handling. Atrial remodeling due to fibrosis and abnormal intracellular Ca2+ activities contributes to initiation and persistence of atrial fibrillation (AF). The present study investigated the effect of isorhamnetin on angiotensin II (AngII)-induced AF in mice. Wild-type male mice (C57BL/6J, 8 weeks old) were assigned to three groups: (1) control group, (2) AngII-treated group, and (3) AngII- and isorhamnetin-treated group. AngII (1000 ng/kg/min) and isorhamnetin (5 mg/kg) were administered continuously via an implantable osmotic pump for two weeks and intraperitoneally one week before initiating AngII administration, respectively. AF induction and electrophysiological studies, Ca2+ imaging with isolated atrial myocytes and HL-1 cells, and action potential duration (APD) measurements using atrial tissue and HL-1 cells were performed. AF-related molecule expression was assessed and histopathological examination was performed. Isorhamnetin decreased AF inducibility compared with the AngII group and restored AngII-induced atrial effective refractory period prolongation. Isorhamnetin eliminated abnormal diastolic intracellular Ca2+ activities induced by AngII. Isorhamnetin also abrogated AngII-induced APD prolongation and abnormal Ca2+ loading in HL-1 cells. Furthermore, isorhamnetin strongly attenuated AngII-induced left atrial enlargement and atrial fibrosis. AngII-induced elevated expression of AF-associated molecules, such as ox-CaMKII, p-RyR2, p-JNK, p-ERK, and TRPC3/6, was improved by isorhamnetin treatment. The findings of the present study suggest that isorhamnetin prevents AngII-induced AF vulnerability and arrhythmogenic atrial remodeling, highlighting its therapeutic potential as an anti-arrhythmogenic pharmaceutical or dietary supplement.

The emerging role of autophagy and mitophagy in tauopathies: From pathogenesis to translational implications in Alzheimer's disease

Alzheimer's disease (AD) is the most prevalent neurodegenerative disease, affecting more than 55 million individuals worldwide in 2021. In addition to the "amyloid hypothesis," an increasing number of studies have demonstrated that phosphorylated tau plays an important role in AD pathogenesis. Both soluble tau oligomers and insoluble tau aggregates in the brain can induce structural and functional neuronal damage through multiple pathways, eventually leading to memory deficits and neurodegeneration. Autophagy is an important cellular response to various stress stimuli and can generally be categorized into non-selective and selective autophagy. Recent studies have indicated that both types of autophagy are involved in AD pathology. Among the several subtypes of selective autophagy, mitophagy, which mediates the selective removal of mitochondria, has attracted increasing attention because dysfunctional mitochondria have been suggested to contribute to tauopathies. In this review, we summarize the latest findings on the bidirectional association between abnormal tau proteins and defective autophagy, as well as mitophagy, which might constitute a vicious cycle in the induction of neurodegeneration. Neuroinflammation, another important feature in the pathogenesis and progression of AD, has been shown to crosstalk with autophagy and mitophagy. Additionally, we comprehensively discuss the relationship between neuroinflammation, autophagy, and mitophagy. By elucidating the underlying molecular mechanisms governing these pathologies, we highlight novel therapeutic strategies targeting autophagy, mitophagy and neuroinflammation, such as those using rapamycin, urolithin, spermidine, curcumin, nicotinamide, and actinonin, for the prevention and treatment of AD.

Activation of cannabinoid receptor 2 attenuates Angiotensin II-induced atrial fibrillation via a potential NOX/CaMKII mechanism

Background

Atrial fibrillation (AF) is the most frequent arrythmia managed in clinical practice. Several mechanisms have been proposed to contribute to the occurrence and persistence of AF, in which oxidative stress plays a non-negligible role. The endocannabinoid system (ECS) is involved in a variety physiological and pathological processes. Cannabinoid receptor 1 (CB1R) and cannabinoid receptor 2 (CB2R) are expressed in the heart, and studies have shown that activating CB2R has a protective effect on the myocardium. However, the role of CB2R in AF is unknown.

Materials and methods

Angiotensin II (Ang II)-infused mice were treated with the CB2R agonist AM1241 intraperitoneally for 21 days. Atrial structural remodeling, AF inducibility, electrical transmission, oxidative stress and fibrosis were measured in mice.

Results

The susceptibility to AF and the level of oxidative stress were increased significantly in Ang II-infused mice. In addition, nicotinamide adenine dinucleotide phosphate oxidase 2 (NOX2), NOX4, and oxidized Ca²⁺/calmodulin-dependent protein kinase II (ox-CaMKII) were highly expressed. More importantly, treatment with AM1241 activated CB2R, resulting in a protective effect.

Conclusion

The present study demonstrates that pharmacological activation of CB2R exerts a protective effect against AF via a potential NOX/CaMKII mechanism. CB2R is a potential therapeutic target for AF.

Role of Ca2+/Calmodulin-Dependent Protein Kinase Type II in Mediating Function and Dysfunction at Glutamatergic Synapses

Glutamatergic synapses harbor abundant amounts of the multifunctional Ca²⁺/calmodulin-dependent protein kinase type II (CaMKII). Both in the postsynaptic density as well as in the cytosolic compartment of postsynaptic terminals, CaMKII plays major roles. In addition to its Ca²⁺-stimulated kinase activity, it can also bind to a variety of membrane proteins at the synapse and thus exert spatially restricted activity. The abundance of CaMKII in glutamatergic synapse is akin to scaffolding proteins although its prominent function still appears to be that of a kinase. The multimeric structure of CaMKII also confers several functional capabilities on the enzyme. The versatility of the enzyme has prompted hypotheses proposing several roles for the enzyme such as Ca²⁺ signal transduction, memory molecule function and scaffolding. The article will review the multiple roles played by CaMKII in glutamatergic synapses and how they are affected in disease conditions.

Are TRPA1 and TRPV1 channel-mediated signalling cascades involved in UVB radiation-induced sunburn?

Burn injuries are underappreciated injuries associated with substantial morbidity and mortality. Overexposure to ultraviolet (UV) radiation has dramatic clinical effects in humans and is a significant public health concern. Although the mechanisms underlying UVB exposure are not fully understood, many studies have made substantial progress in the pathophysiology of sunburn in terms of its molecular aspects in the last few years. It is well established that the transient receptor potential ankyrin 1 (TRPA1), and vanilloid 1 (TRPV1) channels modulate the inflammatory, oxidative, and proliferative processes underlying UVB radiation exposure. However, it is still unknown which mechanisms underlying TRPV1/A1 channel activation are elicited in sunburn induced by UVB radiation. Therefore, in this review, we give an overview of the TRPV1/A1 channel-mediated signalling cascades that may be involved in the pathophysiology of sunburn induced by UVB radiation. These data will undoubtedly help to explain the various features of sunburn and contribute to the development of novel therapeutic approaches to better treat it.

Small extracellular vesicles derived from patients with persistent atrial fibrillation exacerbate arrhythmogenesis via miR-30a-5p

Small extracellular vesicles (sEVs) are nanometer-sized membranous vesicles that contribute to the pathogenesis of atrial fibrillation (AF). Here, we investigated the role of sEVs derived from patients with persistent AF in the pathophysiology of AF. First, we evaluated the pathological effects of sEVs derived from the peripheral blood of patients with persistent AF (AF-sEVs). AF-sEVs treatment reduced cell viability, caused abnormal Ca2+ handling, induced reactive oxygen species (ROS) production, and led to increased CaMKII activation of non-paced and paced atrial cardiomyocytes. Next, we analyzed the miRNA profile of AF-sEVs to investigate which components of AF-sEVs promote arrhythmias, and we selected six miRNAs that correlated with CaMKII activation. qRT-PCR experiment identified that miR-30a-5p was significantly downregulated in AF-sEVs, paced cardiomyocytes, and atrial tissues of patients with persistent AF. CaMKII was predicted by bioinformatics analysis as a miR-30a-5p target gene and validated by a dual luciferase reporter; hence, we evaluated the effects of miR-30a-5p on paced cardiomyocytes and validated miR-30a-5p as a pro-arrhythmic signature of AF-sEVs. Consequently, AF-sEVs-loaded with miR-30a-5p attenuated pacing-induced Ca2+-handling abnormalities, whereas AF-sEVs-loaded with anti-miR-30a-5p reversed the change in paced cardiomyocytes. Taken together, the regulation of CaMKII by miR-30a-5p revealed that miR-30a-5p is a major mediator for AF-sEVs-mediated AF pathogenesis. Accordingly, these findings suggest that sEVs derived from patients with persistent AF exacerbate arrhythmogenesis via miR-30a-5p.

Ellagic Acid Prevents Myocardial Infarction-induced Left Ventricular Diastolic Dysfunction in Ovariectomized Rats

Estrogen deficiency is associated with increased oxidative stress, which can contribute to left ventricular diastolic dysfunction (LVDD). We hypothesized that oral treatment with ellagic acid (EA), a potent and natural antioxidant compound, can improve MI-induced LVDD in ovariectomized rats, by reducing the formation of reactive oxygen species (ROS). Ovariectomized rats MI-induced LVDD followed by treatment with vehicle (DD) or EA (DD+EA) for 4 weeks. Non-LVDD-induced rats treated with vehicle (S) or EA (S+EA) were used as controls. Left ventricular systolic pressure: LVSP; left ventricular end-diastolic pressure: LVEDP; maximum rate of pressure rise: +dP/dt and fall: -dP/dt) were evaluated in all animals after treatment. Left ventricle superoxide anion formation was quantified in situ by fluorescence. Phospho-CAMKII, SOD2, catalase and gp91-phox abundances were evaluated by Western blot analyses. SOD and catalase activities were measured by spectrophotometry. The results showed that the LVEDP was significantly increased in both DD and DD+EA groups compared to S and S+EA. However, LVEDP in the DD+EA group was significantly decreased compared to DD, indicating an EA-mediated effect. In the DD group, superoxide production and gp91-phox protein abundance were increased while SOD2 abundance was decreased when compared to the S and S+EA groups. An increase in SOD activity was also observed in the DD+EA group. EA treatment reduced CaMKII phosphorylation in the DD+EA group compared to the DD. We concluded that EA treatment attenuated diastolic dysfunction in our experimental model, via reduction of ROS and CaMKII activity, indicating EA as a promising natural therapeutic option for cardiac dysfunction.

Dendritic cell immunoreceptor drives atopic dermatitis by modulating oxidized CaMKII-involved mast cell activation

Allergens have been identified as potential triggers in patients with atopic dermatitis (AD). AD patients are highly sensitive to cockroach allergen. The underlying mechanism, however, remains undetermined. Here, we established a cockroach allergen-induced AD-like mouse model and demonstrated that repeated exposure to cockroach allergen led to aggravated mouse skin inflammation, characterized by increased type 2 immunity, type 2 innate lymphoid cells (ILC2s), and mast cells. Increased skin mast cells were also observed in AD patients. AD mice with mast cell-deficient mice (kitW-sh/W-sh) showed diminished skin inflammation, suggesting that mast cells are required in allergen-induced skin inflammation. Furthermore, dendritic cell immuno-receptor (DCIR) is up-regulated in skin mast cells of AD patients and mediates allergen binding and uptake. DCIR-/- mice or reconstituted kitW-sh/W-sh mice with DCIR-/- mast cells showed a significant reduction in AD-like inflammation. Both in vitro and in vivo analyses demonstrated that DCIR-/- mast cells had reduced IgE-mediated mast cell activation and passive cutaneous anaphylaxis. Mechanistically, DCIR regulates allergen-induced IgE-mediated mast cell ROS generation and oxidation of calmodulin kinase II (ox-CaMKII). ROS-resistant CaMKII (MM-VVδ) prevents allergen-induced mast cell activation and inflammatory mediator release. Our study reveals a previously unrecognized DCIR-ROS-CaMKII axis that controls allergen-induced mast cell activation and AD-like inflammation.

Hypochlorite-Modified LDL Induces Arrhythmia and Contractile Dysfunction in Cardiomyocytes

Neutrophil-derived myeloperoxidase (MPO) and its potent oxidant, hypochlorous acid (HOCl), gained attention as important oxidative mediators in cardiac damage and dysfunction. As cardiomyocytes generate low-density lipoprotein (LDL)-like particles, we aimed to identify the footprints of proatherogenic HOCl-LDL, which adversely affects cellular signalling cascades in various cell types, in the human infarcted myocardium. We performed immunohistochemistry for MPO and HOCl-LDL in human myocardial tissue, investigated the impact of HOCl-LDL on electrophysiology and contractility in primary cardiomyocytes, and explored underlying mechanisms in HL-1 cardiomyocytes and human atrial appendages using immunoblot analysis, qPCR, and silencing experiments. HOCl-LDL reduced ICa,L and IK1, and increased INaL, leading to altered action potential characteristics and arrhythmic events including early- and delayed-afterdepolarizations. HOCl-LDL altered the expression and function of CaV1.2, RyR2, NCX1, and SERCA2a, resulting in impaired contractility and Ca2+ homeostasis. Elevated superoxide anion levels and oxidation of CaMKII were mediated via LOX-1 signaling in HL-1 cardiomyocytes. Furthermore, HOCl-LDL-mediated alterations of cardiac contractility and electrophysiology, including arrhythmic events, were ameliorated by the CaMKII inhibitor KN93 and the INaL blocker, ranolazine. This study provides an explanatory framework for the detrimental effects of HOCl-LDL compared to native LDL and cardiac remodeling in patients with high MPO levels during the progression of cardiovascular disease.

Bridging micro/nano-platform and airway allergy intervention

Allergic airway diseases, with incidence augmenting visibly as industrial development and environmental degradation, are characterized by sneezing, itching, wheezing, chest tightness, airway obstruction, and hyperresponsiveness. Current medical modalities attempt to combat these symptoms mostly by small molecule chemotherapeutants, such as corticosteroids, antihistamines, etc., via intranasal approach which is one of the most noninvasive, rapid-absorbed, and patient-friendly routes. Nevertheless, inherent defects for irritation to respiratory mucosa, drug inactivation and degradation, and rapid drug dispersal to off-target sites are inevitable. Lately, intratracheal micro/nano therapeutic systems are emerging as innovative alternatives for airway allergy interventions. This overview introduces several potential application directions of mic/nano-platform in the treatment of airway allergic diseases, including carriers, therapeutic agents, and immunomodulators. The improvement of the existing drug therapy of respiratory allergy management by micro/nano-platform is described in detail. The challenges of the micro/nano-platform nasal approach in the treatment of airway allergy are summarized and the development of micro/nano-platform is also prospected. Although still a burgeoning area, micro/nano therapeutic systems are gradually turning to be realistic orientations as crucial future alternative therapeutic options in allergic airway inflammation interventions.

Catecholamine-induced cardiotoxicity: A critical element in the pathophysiology of stroke-induced heart injury

Cerebrovascular diseases such as ischemic stroke, brain hemorrhage, and subarachnoid hemorrhage provoke cardiac complications such as heart failure, neurogenic stress-related cardiomyopathy and Takotsubo cardiomyopathy. With regards to the pathophysiology of stroke-induced heart injury, several mechanisms have been postulated to contribute to this complex interaction between brain and heart, including damage from gut dysbiosis, immune and systematic inflammatory responses, microvesicle- and microRNA-mediated vascular injury and damage from a surge of catecholamines. All these cerebrovascular diseases may trigger pronounced catecholamine surges through diverse ways, including stimulation of hypothalamic-pituitary adrenal axis, dysregulation of autonomic system, and secretion of adrenocorticotropic hormone. Primary catecholamines involved in this pathophysiological response include norepinephrine (NE) and epinephrine. Both are important neurotransmitters that connect the nervous system with the heart, leading to cardiac damage via myocardial ischemia, calcium (Ca²⁺) overload, oxidative stress, and mitochondrial dysfunction. In this review, we will aim to summarize the molecular mechanisms behind catecholamine-induced cardiotoxicity including Ca²⁺ overload, oxidative stress, apoptosis, cardiac hypertrophy, interstitial fibrosis, and inflammation. In addition, we will focus on how synchronization among these pathways evokes cardiotoxicity.

Enhanced Heart Failure in Redox-Dead Cys17Ser PKARIα Knock-In Mice

Background PKARIα (protein kinase A type I-α regulatory subunit) is redox-active independent of its physiologic agonist cAMP. However, it is unknown whether this alternative mechanism of PKARIα activation may be of relevance to cardiac excitation-contraction coupling. Methods and Results We used a redox-dead transgenic mouse model with homozygous knock-in replacement of redox-sensitive cysteine 17 with serine within the regulatory subunits of PKARIα (KI). Reactive oxygen species were acutely evoked by exposure of isolated cardiac myocytes to AngII (angiotensin II, 1 µmol/L). The long-term relevance of oxidized PKARIα was investigated in KI mice and their wild-type (WT) littermates following transverse aortic constriction (TAC). AngII increased reactive oxygen species in both groups but with RIα dimer formation in WT only. AngII induced translocation of PKARI to the cell membrane and resulted in protein kinase A-dependent stimulation of I_Ca (L-type Ca current) in WT with no effect in KI myocytes. Consequently, Ca transients were reduced in KI myocytes as compared with WT cells following acute AngII exposure. Transverse aortic constriction-related reactive oxygen species formation resulted in RIα oxidation in WT but not in KI mice. Within 6 weeks after TAC, KI mice showed an enhanced deterioration of contractile function and impaired survival compared with WT. In accordance, compared with WT, ventricular myocytes from failing KI mice displayed significantly reduced Ca transient amplitudes and lack of I_Ca stimulation. Conversely, direct pharmacological stimulation of I_Ca using Bay K8644 rescued Ca transients in AngII-treated KI myocytes and contractile function in failing KI mice in vivo. Conclusions Oxidative activation of PKARIα with subsequent stimulation of I_Ca preserves cardiac function in the setting of acute and chronic oxidative stress.

Tilianin Ameliorates Cognitive Dysfunction and Neuronal Damage in Rats with Vascular Dementia via p-CaMKII/ERK/CREB and ox-CaMKII-Dependent MAPK/NF-κB Pathways

Vascular dementia (VaD) is a common cause of cognitive decline and dementia of vascular origin, but the precise pathological mechanisms are unknown, and so effective clinical treatments have not been established. Tilianin, the principal active compound of total flavonoid extract from Dracocephalum moldavica L., is a candidate therapy for cardio-cerebrovascular diseases in China. However, its potential in the treatment of VaD is unclear. The present study is aimed at investigating the protective effects of tilianin on VaD and exploring the underlying mechanism of the action. A model of VaD was established by permanent 2-vessel occlusion (2VO) in rats. Human neurons (hNCs) differentiated from human-induced pluripotent stem cells were used to establish an oxygen-glucose deprivation (OGD) model. The therapeutic effects and potential mechanisms of tilianin were identified using behavioral tests, histochemistry, and multiple molecular biology techniques such as Western blot analysis and gene silencing. The results demonstrated that tilianin modified spatial cognitive impairment, neurodegeneration, oxidation, and apoptosis in rats with VaD and protected hNCs against OGD by increasing cell viability and decreasing apoptosis rates. A study of the mechanism indicated that tilianin restored p-CaMKII/ERK1/2/CREB signaling in the hippocampus, maintaining hippocampus-independent memory. In addition, tilianin inhibited an ox-CaMKII/p38 MAPK/JNK/NF-κB associated inflammatory response caused by cerebral oxidative stress imbalance in rats with VaD. Furthermore, specific CaMKIIα siRNA action revealed that tilianin-exerted neuroprotection involved increase of neuronal viability, inhibition of apoptosis, and suppression of inflammation, which was dependent on CaMKIIα. In conclusion, the results suggested the neuroprotective effect of tilianin in VaD and the potential mechanism associated with dysfunction in the regulation of p-CaMKII-mediated long-term memory and oxidation and inflammation involved with ox-CaMKII, which may lay the foundation for clinical trials of tilianin for the treatment of VaD in the future.

The oxidation-resistant CaMKII-MM281/282VV mutation does not prevent arrhythmias in CPVT1

Catecholaminergic polymorphic ventricular tachycardia type 1 (CPVT1) is an inherited arrhythmogenic disorder caused by missense mutations in the cardiac ryanodine receptors (RyR2), that result in increased β-adrenoceptor stimulation-induced diastolic Ca2+ leak. We have previously shown that exercise training prevents arrhythmias in CPVT1, potentially by reducing the oxidation of Ca2+ /calmodulin-dependent protein kinase type II (CaMKII). Therefore, we tested whether an oxidation-resistant form of CaMKII protects mice carrying the CPVT1-causative mutation RyR2-R2474S (RyR2-RS) against arrhythmias. Antioxidant treatment (N-acetyl-L-cysteine) reduced the frequency of β-adrenoceptor stimulation-induced arrhythmogenic Ca2+ waves in isolated cardiomyocytes from RyR2-RS mice. To test whether the prevention of CaMKII oxidation exerts an antiarrhythmic effect, mice expressing the oxidation-resistant CaMKII-MM281/282VV variant (MMVV) were crossed with RyR2-RS mice to create a double transgenic model (RyR2-RS/MMVV). Wild-type mice served as controls. Telemetric ECG surveillance revealed an increased incidence of ventricular tachycardia and an increased arrhythmia score in both RyR2-RS and RyR2-RS/MMVV compared to wild-type mice, both following a β-adrenoceptor challenge (isoprenaline i.p.), and following treadmill exercise combined with a β-adrenoceptor challenge. There were no differences in the incidence of arrhythmias between RyR2-RS and RyR2-RS/MMVV mice. Furthermore, no differences were observed in β-adrenoceptor stimulation-induced Ca2+ waves in RyR2-RS/MMVV compared to RyR2-RS. In conclusion, antioxidant treatment reduces β-adrenoceptor stimulation-induced Ca2+ waves in RyR2-RS cardiomyocytes. However, oxidation-resistant CaMKII-MM281/282VV does not protect RyR2-RS mice from β-adrenoceptor stimulation-induced Ca2+ waves or arrhythmias. Hence, alternative oxidation-sensitive targets need to be considered to explain the beneficial effect of antioxidant treatment on Ca2+ waves in cardiomyocytes from RyR2-RS mice.

Calcium/Calmodulin-Dependent Protein Kinase II in Cerebrovascular Diseases

Cerebrovascular disease is the most common life-threatening and debilitating condition that often leads to stroke. The multifunctional calcium/calmodulin-dependent protein kinase II (CaMKII) is a key Ca2+ sensor and an important signaling protein in a variety of biological systems within the brain, heart, and vasculature. In the brain, past stroke-related studies have been mainly focused on the role of CaMKII in ischemic stroke in neurons and established CaMKII as a major mediator of neuronal cell death induced by glutamate excitotoxicity and oxidative stress following ischemic stroke. However, with growing understanding of the importance of neurovascular interactions in cerebrovascular diseases, there are clearly gaps in our understanding of how CaMKII functions in the complex neurovascular biological processes and its contributions to cerebrovascular diseases. Additionally, emerging evidence demonstrates novel regulatory mechanisms of CaMKII and potential roles of the less-studied CaMKII isoforms in the ischemic brain, which has sparked renewed interests in this dynamic kinase family. This review discusses past findings and emerging evidence on CaMKII in several major cerebrovascular dysfunctions including ischemic stroke, hemorrhagic stroke, and vascular dementia, focusing on the unique roles played by CaMKII in the underlying biological processes of neuronal cell death, neuroinflammation, and endothelial barrier dysfunction triggered by stroke. We also highlight exciting new findings, promising therapeutic agents, and future perspectives for CaMKII in cerebrovascular systems.

Calcium and Heart Failure: How Did We Get Here and Where Are We Going?

The occurrence and prevalence of heart failure remain high in the United States as well as globally. One person dies every 30 s from heart disease. Recognizing the importance of heart failure, clinicians and scientists have sought better therapeutic strategies and even cures for end-stage heart failure. This exploration has resulted in many failed clinical trials testing novel classes of pharmaceutical drugs and even gene therapy. As a result, along the way, there have been paradigm shifts toward and away from differing therapeutic approaches. The continued prevalence of death from heart failure, however, clearly demonstrates that the heart is not simply a pump and instead forces us to consider the complexity of simplicity in the pathophysiology of heart failure and reinforces the need to discover new therapeutic approaches.

TRAM-Related TLR4 Pathway Antagonized by IRAK-M Mediates the Expression of Adhesion/Coactivating Molecules on Low-Grade Inflammatory Monocytes

Low-grade inflammatory monocytes critically contribute to the pathogenesis of chronic inflammatory diseases such as atherosclerosis. The elevated expression of coactivating molecule CD40 as well as key adhesion molecule CD11a is a critical signature of inflammatory monocytes from both human patients with coronary artery diseases as well as in animal models of atherosclerosis. In this study, we report that subclinical superlow-dose LPS, a key risk factor for low-grade inflammation and atherosclerosis, can potently trigger the induction of CD40 and CD11a on low-grade inflammatory monocytes. Subclinical endotoxin-derived monocytes demonstrate immune-enhancing effects and suppress the generation of regulatory CD8+CD122+ T cells, which further exacerbate the inflammatory environment conducive for chronic diseases. Mechanistically, subclinical endotoxemia activates TRAM-mediated signaling processes, leading to the activation of MAPK and STAT5, which is responsible for the expression of CD40 and CD11a. We also demonstrate that TRAM-mediated monocyte polarization can be suppressed by IRAK-M. IRAK-M-deficient monocytes have increased expression of TRAM, elevated induction of CD40 and CD11a by subclinical-dose endotoxin, and are more potent in suppressing the CD8 regulatory T cells. Mice with IRAK-M deficiency generate an increased population of inflammatory monocytes and a reduced population of CD8 T regulatory cells. In contrast, mice with TRAM deficiency exhibit a significantly reduced inflammatory monocyte population and an elevated CD8 T regulatory cell population. Together, our data reveal a competing intracellular circuitry involving TRAM and IRAK-M that modulate the polarization of low-grade inflammatory monocytes with an immune-enhancing function.

CaMKII in Regulation of Cell Death During Myocardial Reperfusion Injury

Cardiovascular disease is the leading cause of death worldwide. In spite of the mature managements of myocardial infarction (MI), post-MI reperfusion (I/R) injury results in high morbidity and mortality. Cardiomyocyte Ca²⁺ overload is a major factor of I/R injury, initiating a cascade of events contributing to cardiomyocyte death and myocardial dysfunction. Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) plays a critical role in cardiomyocyte death response to I/R injury, whose activation is a key feature of myocardial I/R in causing intracellular mitochondrial swelling, endoplasmic reticulum (ER) Ca²⁺ leakage, abnormal myofilament contraction, and other adverse reactions. CaMKII is a multifunctional serine/threonine protein kinase, and CaMKIIδ, the dominant subtype in heart, has been widely studied in the activation, location, and related pathways of cardiomyocytes death, which has been considered as a potential targets for pharmacological inhibition. In this review, we summarize a brief overview of CaMKII with various posttranslational modifications and its properties in myocardial I/R injury. We focus on the molecular mechanism of CaMKII involved in regulation of cell death induced by myocardial I/R including necroptosis and pyroptosis of cardiomyocyte. Finally, we highlight that targeting CaMKII modifications and cell death involved pathways may provide new insights to understand the conversion of cardiomyocyte fate in the setting of myocardial I/R injury.

Comparative study on beneficial effects of vitamins B and D in attenuating doxorubicin induced cardiotoxicity in rats: Emphasis on calcium homeostasis

The use of doxorubicin (DOX) to treat various tumors is limited by its cardiotoxicity. This study aimed to investigate and compare the cardioprotective effects of nicotinamide (NAM) and alfacalcidol (1α(OH)D₃), against DOX-induced cardiotoxicity. Sprague Dawley male rats received DOX (5 mg/kg, i.p.) once/week for four consecutive weeks. Treated groups received either NAM (600 mg/kg, p.o.) for 28 consecutive days or 1α(OH)D₃ (0.5 ug/kg, i.p.) once/week for four consecutive weeks. DOX elicited marked cardiac tissue injury manifested by elevated serum cardiotoxicity indices, conduction and histopathological abnormalities. Both NAM and 1α(OH)D₃ successfully reversed all these changes. From the mechanistic point of view, DOX provoked intense cytosolic and mitochondrial calcium (Ca²⁺) overload hence switching on calpain1 (CPN1) and mitochondrial-mediated apoptotic cascades as confirmed by upregulating Bax and caspase-3 while downregulating Bcl-2 expression. DOX also disrupted cardiac bioenergetics as evidenced by adenosine triphosphate (ATP) depletion and a declined ATP/ADP ratio. Moreover, DOX upregulated the Ca²⁺ sensor; calmodulin kinase II gamma (CaMKII-δ) which further contributed to cardiac damage. Interestingly, co-treatment with either NAM or 1α(OH)D₃ reversed all DOX associated abnormalities by preserving Ca²⁺ homeostasis, replenishing ATP stores and obstructing apoptotic events. Additionally, DOX prompted nuclear factor kappa B (NF-κB) dependent inflammatory responses and subsequently upregulated interleukin-6 (IL-6) expression. Co-treatment with NAM or 1α(OH)D₃ effectively obstructed these inflammatory signals. Remarkably, NAM showed superior beneficial cardioprotective properties over 1α(OH)D₃. Both NAM and 1α(OH)D₃ efficiently attenuated DOX-cardiomyopathy mainly via preserving Ca²⁺ homeostasis and diminishing apoptotic and inflammatory pathways. NAM definitely exhibited effective cardioprotective capabilities over 1α(OH)D₃.

Interactive Roles of CaMKII/Ryanodine Receptor Signaling and Inflammation in Lung Diseases

Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) is a multifunctional protein kinase and has been recently recognized to play a vital role in pathological events in the pulmonary system. CaMKII has diverse downstream targets that promote vascular disease, asthma, and cancer, so improved understanding of CaMKII signaling has the potential to lead to new therapies for lung diseases. Multiple studies have demonstrated that CaMKII is involved in redox modulation of ryanodine receptors (RyRs). CaMKII can be directly activated by reactive oxygen species (ROS) which then regulates RyR activity, which is essential for Ca²⁺-dependent processes in lung diseases. Furthermore, both CaMKII and RyRs participate in the inflammation process. However, their role in the pulmonary physiology in response to ROS is still an ambiguous one. Because CaMKII and RyRs are important in pulmonary biology, cell survival, cell cycle control, and inflammation, it is possible that the relationship between ROS and CaMKII/RyRs signal complex will be necessary for understanding and treating lung diseases. Here, we review roles of CaMKII/RyRs in lung diseases to understand with how CaMKII/RyRs may act as a transduction signal to connect prooxidant conditions into specific downstream pathological effects that are relevant to rare and common forms of pulmonary disease.

Nutraceutical, Dietary, and Lifestyle Options for Prevention and Treatment of Ventricular Hypertrophy and Heart Failure

Although well documented drug therapies are available for the management of ventricular hypertrophy (VH) and heart failure (HF), most patients nonetheless experience a downhill course, and further therapeutic measures are needed. Nutraceutical, dietary, and lifestyle measures may have particular merit in this regard, as they are currently available, relatively safe and inexpensive, and can lend themselves to primary prevention as well. A consideration of the pathogenic mechanisms underlying the VH/HF syndrome suggests that measures which control oxidative and endoplasmic reticulum (ER) stress, that support effective nitric oxide and hydrogen sulfide bioactivity, that prevent a reduction in cardiomyocyte pH, and that boost the production of protective hormones, such as fibroblast growth factor 21 (FGF21), while suppressing fibroblast growth factor 23 (FGF23) and marinobufagenin, may have utility for preventing and controlling this syndrome. Agents considered in this essay include phycocyanobilin, N-acetylcysteine, lipoic acid, ferulic acid, zinc, selenium, ubiquinol, astaxanthin, melatonin, tauroursodeoxycholic acid, berberine, citrulline, high-dose folate, cocoa flavanols, hawthorn extract, dietary nitrate, high-dose biotin, soy isoflavones, taurine, carnitine, magnesium orotate, EPA-rich fish oil, glycine, and copper. The potential advantages of whole-food plant-based diets, moderation in salt intake, avoidance of phosphate additives, and regular exercise training and sauna sessions are also discussed. There should be considerable scope for the development of functional foods and supplements which make it more convenient and affordable for patients to consume complementary combinations of the agents discussed here. Research Strategy: Key word searching of PubMed was employed to locate the research papers whose findings are cited in this essay.

Chronic Ca2+/Calmodulin-Dependent Protein Kinase II Inhibition Rescues Advanced Heart Failure

Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) is upregulated in congestive heart failure (CHF), contributing to electrical, structural, and functional remodeling. CaMKII inhibition is known to improve CHF, but its direct cardiac effects in CHF remain unclear. We hypothesized that CaMKII inhibition improves cardiomyocyte function, [Ca²⁺]_i regulation, and β-adrenergic reserve, thus improving advanced CHF. In a 16-week study, we compared plasma neurohormonal levels and left ventricular (LV)- and myocyte-functional and calcium transient ([Ca²⁺]_iT) responses in male Sprague-Dawley rats (10/group) with CHF induced by isoproterenol (170 mg/kg sq for 2 days). In rats with CHF, we studied the effects of the CaMKII inhibitor KN-93 or its inactive analog KN-92 (n = 4) (70 µg/kg per day, mini-pump) for 4 weeks. Compared with controls, isoproterenol-treated rats had severe CHF with 5-fold-increased plasma norepinephrine and about 50% decreases in ejection fraction (EF) and LV contractility [slope of LV end-systolic pressure-LV end-systolic volume relation (E_ES)] but increased time constant of LV relaxation (τ). They also showed significantly reduced myocyte contraction [maximum rate of myocyte shortening (dL/dt_max)], relaxation (dL/dt_max), and [Ca²⁺]_iT Isoproterenol superfusion caused significantly fewer increases in dL/dt_max and [Ca²⁺]_iT KN-93 treatment prevented plasma norepinephrine elevation, with increased basal and acute isoproterenol-stimulated increases in EF and E_ES and decreased τ in CHF. KN-93 treatment preserved normal myocyte contraction, relaxation, [Ca²⁺]_iT, and β-adrenergic reserve, whereas KN-92 treatment failed to improve LV and myocyte function, and plasma norepinephrine remained high in CHF. Thus, chronic CaMKII inhibition prevented CHF-induced activation of the sympathetic nervous system, restoring normal LV and cardiomyocyte basal and β-adrenergic-stimulated contraction, relaxation, and [Ca²⁺]_iT, thereby playing a rescue role in advanced CHF. SIGNIFICANCE STATEMENT: We investigated the therapeutic efficacy of late initiation of chronic Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) inhibition on progression of advanced congestive heart failure (CHF). Chronic CaMKII inhibition prevented CHF-induced activation of the sympathetic nervous system and restored normal intrinsic cardiomyocyte basal and β-adrenergic receptor-stimulated relaxation, contraction, and [Ca²⁺]_i regulation, leading to reversal of CHF progression. These data provide new evidence that CaMKII inhibition is able and sufficient to rescue a failing heart, and thus cardiac CaMKII inhibition is a promising target for improving CHF treatment.

Rbfox-1 contributes to CaMKIIα expression and intracerebral hemorrhage-induced secondary brain injury via blocking micro-RNA-124

RNA-binding protein fox-1 homolog 1 (Rbfox-1), an RNA-binding protein in neurons, is thought to be associated with many neurological diseases. To date, the mechanism on which Rbfox-1 worsens secondary cell death in ICH remains poorly understood. In this study, we aimed to explore the role of Rbfox-1 in intracerebral hemorrhage (ICH)-induced secondary brain injury (SBI) and to identify its underlying mechanisms. We found that the expression of Rbfox-1 in neurons was significantly increased after ICH, which was accompanied by increases in the binding of Rbfox-1 to Ca²⁺/calmodulin-dependent protein kinase II (CaMKIIα) mRNA and the protein level of CaMKIIα. In addition, when exposed to exogenous upregulation or downregulation of Rbfox-1, the protein level of CaMKIIα showed a concomitant trend in brain tissue, which further suggested that CaMKIIα is a downstream-target protein of Rbfox-1. The upregulation of both proteins caused intracellular-Ca²⁺ overload and neuronal degeneration, which exacerbated brain damage. Furthermore, we found that Rbfox-1 promoted the expression of CaMKIIα via blocking the binding of micro-RNA-124 to CaMKIIα mRNA. Thus, Rbfox-1 is expected to be a promising therapeutic target for SBI after ICH.

Loss of CASK Accelerates Heart Failure Development

[Figure: see text].

Protein Lipoxidation: Basic Concepts and Emerging Roles

Protein lipoxidation is a non-enzymatic post-translational modification that consists of the covalent addition of reactive lipid species to proteins. This occurs under basal conditions but increases in situations associated with oxidative stress. Protein targets for lipoxidation include metabolic and signalling enzymes, cytoskeletal proteins, and transcription factors, among others. There is strong evidence for the involvement of protein lipoxidation in disease, including atherosclerosis, neurodegeneration, and cancer. Nevertheless, the involvement of lipoxidation in cellular regulatory mechanisms is less understood. Here we review basic aspects of protein lipoxidation and discuss several features that could support its role in cell signalling, including its selectivity, reversibility, and possibilities for regulation at the levels of the generation and/or detoxification of reactive lipids. Moreover, given the great structural variety of electrophilic lipid species, protein lipoxidation can contribute to the generation of multiple structurally and functionally diverse protein species. Finally, the nature of the lipoxidised proteins and residues provides a frameshift for a complex interplay with other post-translational modifications, including redox and redox-regulated modifications, such as oxidative modifications and phosphorylation, thus strengthening the importance of detailed knowledge of this process.

MICAL1 constrains cardiac stress responses and protects against disease by oxidizing CaMKII

Oxidant stress can contribute to health and disease. Here we show that invertebrates and vertebrates share a common stereospecific redox pathway that protects against pathological responses to stress, at the cost of reduced physiological performance, by constraining Ca2+/calmodulin-dependent protein kinase II (CaMKII) activity. MICAL1, a methionine monooxygenase thought to exclusively target actin, and MSRB, a methionine reductase, control the stereospecific redox status of M308, a highly conserved residue in the calmodulin-binding (CaM-binding) domain of CaMKII. Oxidized or mutant M308 (M308V) decreased CaM binding and CaMKII activity, while absence of MICAL1 in mice caused cardiac arrhythmias and premature death due to CaMKII hyperactivation. Mimicking the effects of M308 oxidation decreased fight-or-flight responses in mice, strikingly impaired heart function in Drosophila melanogaster, and caused disease protection in human induced pluripotent stem cell-derived cardiomyocytes with catecholaminergic polymorphic ventricular tachycardia, a CaMKII-sensitive genetic arrhythmia syndrome. Our studies identify a stereospecific redox pathway that regulates cardiac physiological and pathological responses to stress across species.

Cardiac transmembrane ion channels and action potentials: cellular physiology and arrhythmogenic behavior

Cardiac arrhythmias are among the leading causes of mortality. They often arise from alterations in the electrophysiological properties of cardiac cells and their underlying ionic mechanisms. It is therefore critical to further unravel the pathophysiology of the ionic basis of human cardiac electrophysiology in health and disease. In the first part of this review, current knowledge on the differences in ion channel expression and properties of the ionic processes that determine the morphology and properties of cardiac action potentials and calcium dynamics from cardiomyocytes in different regions of the heart are described. Then the cellular mechanisms promoting arrhythmias in congenital or acquired conditions of ion channel function (electrical remodeling) are discussed. The focus is on human-relevant findings obtained with clinical, experimental, and computational studies, given that interspecies differences make the extrapolation from animal experiments to human clinical settings difficult. Deepening the understanding of the diverse pathophysiology of human cellular electrophysiology will help in developing novel and effective antiarrhythmic strategies for specific subpopulations and disease conditions.

CaMKII exacerbates heart failure progression by activating class I HDACs

BACKGROUND

Persistent cardiac Ca²⁺/calmodulin dependent Kinase II (CaMKII) activation plays an essential role in heart failure development. However, the molecular mechanisms underlying CaMKII induced heart failure progression remains incompletely understood. Histone deacetylases (HDACs) are critical for transcriptional responses to stress, and contribute to expression of pathological genes causing adverse ventricular remodeling. Class I HDACs, including HDAC1, HDAC2 and HDAC3, promote pathological cardiac hypertrophy, whereas class IIa HDACs suppress cardiac hypertrophy. While it is known that CaMKII deactivates class IIa HDACs to enhance cardiac hypertrophy, the role of CaMKII in regulating class I HDACs during heart failure progression is unclear.

METHODS AND RESULTS

CaMKII increases the deacetylase activity of recombinant HDAC1, HDAC2 and HDAC3 via in vitro phosphorylation assays. Phosphorylation sites on HDAC1 and HDAC3 are identified with mass spectrometry. HDAC1 activity is also increased in cardiac-specific CaMKIIδ_C transgenic mice (CaMKIIδ_C-tg). Beyond post-translational modifications, CaMKII induces HDAC1 and HDAC3 expression. HDAC1 and HDAC3 expression are significantly increased in CaMKIIδ_C-tg mice. Inhibition of CaMKII by overexpression of the inhibitory peptide AC3-I in the heart attenuates the upregulation of HDAC1 after myocardial infarction surgery. Importantly, a potent HDAC1 inhibitor Quisinostat improves downregulated autophagy genes and cardiac dysfunction in CaMKIIδ_C-tg mice. In addition to Quisinostat, selective class I HDACs inhibitors, Apicidin and Entinostat, HDAC3 specific inhibitor RGFP966, as well as HDAC1 and HDAC3 siRNA prevent CaMKII overexpression induced cardiac myocyte hypertrophy.

CONCLUSION

CaMKII activates class I HDACs in heart failure, which may be a central mechanism for heart failure progression. Selective class I HDACs inhibition may be a novel therapeutic avenue to alleviate CaMKII hyperactivity induced cardiac dysfunction.

The calmodulin redox sensor controls myogenesis

Muscle aging is accompanied by blunted muscle regeneration in response to injury and disuse. Oxidative stress likely underlies this diminished response, but muscle redox sensors that act in regeneration have not yet been characterized. Calmodulin contains multiple redox sensitive methionines whose oxidation alters the regulation of numerous cellular targets. We have used the CRISPR-Cas9 system to introduce a single amino acid substitution M109Q that mimics oxidation of methionine to methionine sulfoxide in one or both alleles of the CALM1 gene, one of three genes encoding the muscle regulatory protein calmodulin, in C2C12 mouse myoblasts. When signaled to undergo myogenesis, mutated myoblasts failed to differentiate into myotubes. Although early myogenic regulatory factors were present, cells with the CALM1 M109Q mutation in one or both alleles were unable to withdraw from the cell cycle and failed to express late myogenic factors. We have shown that a single oxidative modification to a redox-sensitive muscle regulatory protein can halt myogenesis, suggesting a molecular target for mitigating the impact of oxidative stress in age-related muscle degeneration.

Mechanisms of artemether toxicity on single cardiomyocytes and protective effect of nanoencapsulation

BACKGROUND AND PURPOSE

The artemisinin derivative, artemether, has antimalarial activity with potential neurotoxic and cardiotoxic effects. Artemether in nanocapsules (NC-ATM) is more efficient than free artemether for reducing parasitaemia and increasing survival of Plasmodium berghei-infected mice. NCs also prevent prolongation of the QT interval of the ECG. Here, we assessed cellular cardiotoxicity of artemether and how this toxicity was prevented by nanoencapsulation.

EXPERIMENTAL APPROACH

Mice were treated with NC-ATM orally (120 mg·kg^-1 twice daily) for 4 days. Other mice received free artemether, blank NCs, and vehicle for comparison. We measured single-cell contraction, intracellular Ca²⁺ transient using fluorescent Indo-1AM Ca²⁺ dye, and electrical activity using the patch-clamp technique in freshly isolated left ventricular myocytes. The acute effect of free artemether was also tested on cardiomyocytes of untreated animals.

KEY RESULTS

Artemether prolonged action potentials (AP) upon acute exposure (at 0.1, 1, and 10 μM) of cardiomyocytes from untreated mice or after in vivo treatment. This prolongation was unrelated to blockade of K⁺ currents, increased Ca²⁺ currents or promotion of a sustained Na⁺ current. AP lengthening was abolished by the NCX inhibitor SEA-0400. Artemether promoted irregular Ca²⁺ transients during pacing and spontaneous Ca²⁺ events during resting periods. NC-ATM prevented all effects. Blank NCs had no effects compared with vehicle.

CONCLUSION AND IMPLICATIONS

Artemether induced NCX-dependent AP lengthening (explaining QTc prolongation) and disrupted Ca²⁺ handling, both effects increasing pro-arrhythmogenic risks. NCs prevented these adverse effects, providing a safe alternative to the use of artemether alone, especially to treat malaria.

Xanthine oxidase inhibitor allopurinol improves atrial electrical remodeling in diabetic rats by inhibiting CaMKII/NCX signaling

AIMS

Atrial fibrillation (AF) is a common arrhythmia which is associated with higher risk of stroke, heart failure and all-cause mortality. Abnormal Ca²⁺ handling in diabetes mellitus (DM) can cause delayed depolarization involved with increased NCX activity. Complicated mechanisms are involved in atrial remodeling, of which CaMKII may be a key node signal. Therefore, we intend to explore whether CaMKII activation induces atrial electrical remodeling by regulating NCX expression in this study.

MAIN METHODS

Adult male SD rats were used to establish a diabetic rat model, divided into three groups: the control group, DM group and allopurinol group. Hemodynamic and ECG indicators were recorded, after which electrophysiological studies were conducted. The protein expression of CaMKII, p-CaMKII, XO, MnSOD and NCX was measured by Western blot and immunohistochemistry. H&E and Masson staining were applied for observing myocardial fibrosis. HL-1 cells were cultured for the measurement of ROS generation.

KEY FINDINGS

The arrangement of atrial myocytes was disordered and the collagen volume fraction of the atrium tissue was elevated in the DM group compared with the control group, and improved by allopurinol. Higher incidence of inducible AF, reduced conduction velocity and higher conduction inhomogeneity were observed in diabetic rats. These electrophysiological abnormalities were accompanied by higher oxidative stress and protein expression of p-CaMKII and NCX. Allopurinol prevented the development of these abnormal changes.

SIGNIFICANCE

Allopurinol can improve atrial electrical remodeling by inhibiting CaMKII activity and protein expression of NCX. These data indicate xanthine oxidase inhibition can reduce oxidative stress and ameliorate atrial electrical remodeling.

MicroRNA and ROS Crosstalk in Cardiac and Pulmonary Diseases

Reactive oxygen species (ROS) affect many cellular functions and the proper redox balance between ROS and antioxidants contributes substantially to the physiological welfare of the cell. During pathological conditions, an altered redox equilibrium leads to increased production of ROS that in turn may cause oxidative damage. MicroRNAs (miRNAs) regulate gene expression at the post-transcriptional level contributing to all major cellular processes, including oxidative stress and cell death. Several miRNAs are expressed in response to ROS to mediate oxidative stress. Conversely, oxidative stress may lead to the upregulation of miRNAs that control mechanisms to buffer the damage induced by ROS. This review focuses on the complex crosstalk between miRNAs and ROS in diseases of the cardiac (i.e., cardiac hypertrophy, heart failure, myocardial infarction, ischemia/reperfusion injury, diabetic cardiomyopathy) and pulmonary (i.e., idiopathic pulmonary fibrosis, acute lung injury/acute respiratory distress syndrome, asthma, chronic obstructive pulmonary disease, lung cancer) compartments. Of note, miR-34a, miR-144, miR-421, miR-129, miR-181c, miR-16, miR-31, miR-155, miR-21, and miR-1/206 were found to play a role during oxidative stress in both heart and lung pathologies. This review comprehensively summarizes current knowledge in the field.

Coniferyl ferulate exerts antidepressant effect via inhibiting the activation of NMDAR-CaMKII-MAPKs and mitochondrial apoptotic pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Xiaoyaosan (XYS), composed of Radix Bupleuri, Radix Angelicae Sinensis, Radix Paeoniae Alba, Rhizoma Atractylodis Macrocephalae, Poria, Herba Menthae, Rhizoma Zingiberis Recens and Radix Glycyrrhizae, is a valuable traditional Chinese medicine (TCM) which is used for the treatment of depression in China. In our previous experiments, we found that coniferyl ferulate (CF) was the main active constituent of Xiaoyaosan based on UPLC-PDA guided isolation technique. However, the antidepressant effect and mechanisms of CF is still unknown.

AIM OF THE STUDY

In the current study, we aim to explore the possible mechanisms involved in the neuroprotective effect of CF in glutamate-injured PC12 cells, and further to confirm the anti-depressant effect of CF on the model of behavioral despair in vivo.

MATERIAL AND METHODS

The model of glutamate-injured PC12 cells was employed to investigate the possible mechanisms involved in the neuroprotective effect of CF. The model of behavioral despair was carried out to examine the in vivo anti-depressant effect of CF.

RESULTS

The results showed that CF significantly attenuated the decrease of cell viability, the release of lactate dehydrogenase (LDH), and the increase of apoptosis rates induced by glutamate. CF could also suppress the influx of Ca²⁺ and the elevation of p-NR2B, p-CaMK II, p-JNK, and p-p38 level induced by glutamate. Besides, CF could also inhibit the generation of reactive oxygen species (ROS), the decrease of SOD activity, the elevation of malondialdehyde (MDA) level, and suppress the loss of mitochondrial membrane potential (MMPs) and the activation Bcl-2/Bax mediated apoptotic pathways induced by glutamate. Furthermore, CF obviously decreased the immobility time in tail suspension test (TST) and forced swimming test (FST).

CONCLUSION

In conclusion, CF exert the indeed anti-depressant effect. The inhibition of NMDAR-CaMKII-MAPKs signaling pathway, oxidative stress, and mitochondrial apoptotic pathways were involved in the anti-depressant effect of CF.

Hyperglycemia Acutely Increases Cytosolic Reactive Oxygen Species via O-linked GlcNAcylation and CaMKII Activation in Mouse Ventricular Myocytes

RATIONALE

Diabetes mellitus is a complex, multisystem disease, affecting large populations worldwide. Chronic CaMKII (Ca²⁺/calmodulin-dependent kinase II) activation may occur in diabetes mellitus and be arrhythmogenic. Diabetic hyperglycemia was shown to activate CaMKII by (1) O-linked attachment of N-acetylglucosamine (O-GlcNAc) at S280 leading to arrhythmia and (2) a reactive oxygen species (ROS)-mediated oxidation of CaMKII that can increase postinfarction mortality.

OBJECTIVE

To test whether high extracellular glucose (Hi-Glu) promotes ventricular myocyte ROS generation and the role played by CaMKII.

METHODS AND RESULTS

We tested how extracellular Hi-Glu influences ROS production in adult ventricular myocytes, using DCF (2',7'-dichlorodihydrofluorescein diacetate) and genetically targeted Grx-roGFP2 redox sensors. Hi-Glu (30 mmol/L) significantly increased the rate of ROS generation-an effect prevented in myocytes pretreated with CaMKII inhibitor KN-93 or from either global or cardiac-specific CaMKIIδ KO (knockout) mice. CaMKII KO or inhibition also prevented Hi-Glu-induced sarcoplasmic reticulum Ca²⁺ release events (Ca²⁺ sparks). Thus, CaMKII activation is required for Hi-Glu-induced ROS generation and sarcoplasmic reticulum Ca²⁺ leak in cardiomyocytes. To test the involvement of O-GlcNAc-CaMKII pathway, we inhibited GlcNAcylation removal by Thiamet G (ThmG), which mimicked the Hi-Glu-induced ROS production. Conversely, inhibition of GlcNAcylation (OSMI-1 [(αR)-α-[[(1,2-dihydro-2-oxo-6-quinolinyl)sulfonyl]amino]-N-(2-furanylmethyl)-2-methoxy-N-(2-thienylmethyl)-benzeneacetamide]) prevented ROS induction in response to either Hi-Glu or ThmG. Moreover, in a CRSPR-based knock-in mouse in which the functional GlcNAcylation site on CaMKIIδ was ablated (S280A), neither Hi-Glu nor ThmG induced myocyte ROS generation. So CaMKIIδ-S280 is required for the Hi-Glu-induced (and GlcNAc dependent) ROS production. To identify the ROS source(s), we used different inhibitors of NOX (NADPH oxidase) 2 (Gp91ds-tat peptide), NOX4 (GKT137831), mitochondrial ROS (MitoTempo), and NOS (NO synthase) pathway inhibitors (L-NAME, L-NIO, and L-NPA). Only NOX2 inhibition or KO prevented Hi-Glu/ThmG-induced ROS generation.

CONCLUSIONS

Diabetic hyperglycemia induces acute cardiac myocyte ROS production by NOX2 that requires O-GlcNAcylation of CaMKIIδ at S280. This novel ROS induction may exacerbate pathological consequences of diabetic hyperglycemia.

L-carnitine supplementation attenuates NAFLD progression and cardiac dysfunction in a mouse model fed with methionine and choline-deficient diet

Non-alcoholic fatty liver disease (NAFLD) is a common cause of chronic liver disorder. NAFLD, associated lipotoxicity, fibrosis, oxidative stress, and altered mitochondrial metabolism, is responsible for systemic inflammation, which contributes to organ dysfunction in extrahepatic tissues, including the heart. We investigated the ability of L-carnitine (LC) to oppose the pathogenic mechanisms underlying NAFLD progression and associated heart dysfunction, in a mouse model of methionine-choline-deficient diet (MCDD). Mice were divided into three groups: namely, the control group (CONTR) fed with a regular diet and two groups fed with MCDD for 6 weeks. In the last 3 weeks, one of the MCDD groups received LC (200 mg/kg each day) through drinking water (MCDD + LC). The hepatic lipid accumulation and oxidative stress decreased after LC supplementation, which also reduced hepatic fibrosis via modulation of α-smooth muscle actin (αSMA), peroxisome-activated receptor gamma (PPARγ), and nuclear factor kappa B (NfƙB) expression. LC ameliorated systemic inflammation, mitigated cardiac reactive oxygen species (ROS) production, and prevented fibrosis progression by acting on signal transducer and activator of transcription 3 (STAT3), extracellular signal-regulated kinase 1-2 (ERK1-2), and αSMA. This study confirms the existence of a relationship between fatty liver disease and cardiac abnormalities and highlights the role of LC in controlling liver oxidative stress, steatosis, fibrosis, and NAFLD-associated cardiac dysfunction.

Challenges and Opportunities for Therapeutic Targeting of Calmodulin Kinase II in Heart

Heart failure remains a major health burden around the world. Despite great progress in delineation of molecular mechanisms underlying development of disease, standard therapy has not advanced at the same pace. The multifunctional signaling molecule Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) has received considerable attention over recent years for its central role in maladaptive remodeling and arrhythmias in the setting of chronic disease. However, these basic science discoveries have yet to translate into new therapies for human patients. This review addresses both the promise and barriers to developing translational therapies that target CaMKII signaling to abrogate pathologic remodeling in the setting of chronic disease. Efforts in small molecule design are discussed, as well as alternative targeting approaches that exploit novel avenues for compound delivery and/or genetic approaches to affect cardiac CaMKII signaling. These alternative strategies provide hope for overcoming some of the challenges that have limited the development of new therapies.