Activation of CaMKII via ER-stress mediates coxsackievirus B3-induced cardiomyocyte apoptosis

Phytochemical regulation of CaMKII in Alzheimer's disease: A review of molecular mechanisms and therapeutic potential

Alzheimer's disease (AD) is a common neurodegenerative disorder that leads to cognitive decline. CaMKII is a calcium-regulated kinase that is crucial for synaptic plasticity and memory. Phytochemicals with diverse origins, safety, and biological activity have attracted considerable attention in AD research. This systematic analysis of phytochemicals targeting CaMKII reveals their neuroprotective mechanisms against AD pathogenesis, highlighting CaMKII as a promising therapeutic target that warrants further preclinical investigation and drug development. We conducted a comprehensive review of the literature of phytochemicals that target CaMKII as a protective mechanism against AD. The search was conducted across multiple databases, including PubMed, Web of Science, China National Knowledge Internet, and Google Scholar, and covered the period from January 2000 to October 2024. A total of 301 articles were retrieved, of which 22 articles were included. The results showed that flavonoid, glycoside, terpene, and polyphenol analogs positively regulated CaMKII expression, whereas alkaloid analogs negatively regulated CaMKII expression. Different components of traditional Chinese medicine played different roles in CaMKII expression. Flavonoid compounds upregulated the expression of SYN, PSD-95, MAP2, and GluR1 to exert neuroprotective effects. Alkaloid and glycoside analogs inhibited Aβ deposition and tau hyperphosphorylation. Terpene analogs upregulated the SYN, PSD-95, NMDAR, BDNF, and PI3K/Akt signaling pathways to exert neuroprotection. Polyphenol analogs upregulated PSD-95, Munc18-1, SNAP25, SYN, and BDNF to exert neuroprotective effects. Emerging evidence demonstrates that select phytochemicals and traditional Chinese medicine compounds exert neuroprotective effects in AD by modulating CaMKII activity, thereby reducing Aβ accumulation, attenuating tau hyperphosphorylation, and enhancing synaptic plasticity, suggesting promising therapeutic potential.

Deep insight into cytokine storm: from pathogenesis to treatment

Cytokine storm (CS) is a severe systemic inflammatory syndrome characterized by the excessive activation of immune cells and a significant increase in circulating levels of cytokines. This pathological process is implicated in the development of life-threatening conditions such as fulminant myocarditis (FM), acute respiratory distress syndrome (ARDS), primary or secondary hemophagocytic lymphohistiocytosis (HLH), cytokine release syndrome (CRS) associated with chimeric antigen receptor-modified T (CAR-T) therapy, and grade III to IV acute graft-versus-host disease following allogeneic hematopoietic stem cell transplantation. The significant involvement of the JAK-STAT pathway, Toll-like receptors, neutrophil extracellular traps, NLRP3 inflammasome, and other signaling pathways has been recognized in the pathogenesis of CS. Therapies targeting these pathways have been developed or are currently being investigated. While novel drugs have demonstrated promising therapeutic efficacy in mitigating CS, the overall mortality rate of CS resulting from underlying diseases remains high. In the clinical setting, the management of CS typically necessitates a multidisciplinary team strategy encompassing the removal of abnormal inflammatory or immune system activation, the preservation of vital organ function, the treatment of the underlying disease, and the provision of life supportive therapy. This review provides a comprehensive overview of the key signaling pathways and associated cytokines implicated in CS, elucidates the impact of dysregulated immune cell activation, and delineates the resultant organ injury associated with CS. In addition, we offer insights and current literature on the management of CS in cases of FM, ARDS, systemic inflammatory response syndrome, treatment-induced CRS, HLH, and other related conditions.

Hantaan virus infection induces human mucosal-associated invariant T cell pyroptosis through IRE1α pathway

Hantaan virus (HTNV) triggers an epidemic of hemorrhagic fever with renal syndrome (HFRS), which is predominantly prevalent in Asia. Mucosal-associated invariant T (MAIT) cells, categorized as innate-like T lymphocytes, perform crucial functions in the innate host defense mechanism during virus infection. We previously showed that MAIT cells played antiviral roles in vitro. But marked reduction of MAIT cells was present in the peripheral blood of HFRS patients. Till now, the role of MAIT cells in vivo and the mechanisms of HTNV-induced the MAIT cell deficiency have not yet been fully explored. In this study, by combining the clinical samples, MAIT deficiency mice and in vitro infected MAIT cell models, we find that pyroptosis was the main reason of MAIT cell loss in the peripheral blood of HFRS patients. The molecular mechanisms are related to the overload of calcium in the endoplasmic reticulum (ER) of MAIT cells, which subsequently induces inosital-requiring enzyme-1α (IRE1α)-mediated ER-stress and following pyroptosis. ER-stress inhibitor can reverse the pyroptosis of MAIT cells during HTNV infection. In conclusion, this study firstly reveals the underlying molecular mechanisms for the deficiency of MAIT cells during HTNV infection, and suggests a potential way to stabilize the MAIT cells population in HFRS.

CaMKIIδ, Stabilized by RNA N6-Methyladenosine Reader IGF2BP2, Boosts Coxsackievirus B3-Induced Myocardial Inflammation via Interacting with TIRAP

Calcium/calmodulin-dependent protein kinase II (CaMKII) has been demonstrated to be aberrantly activated in viral myocarditis (VMC), but the role of its subtype CaMKIIδ in VMC remains unclear.VMC mice and cardiomyocytes models were induced by Coxsackievirus B3 (CVB3) treatment. Mice that underwent sham surgery and saline-treated cardiomyocytes served as controls. Body weight, survival, left ventricular ejection fraction (LVEF), and fractional shortening (LVFS) were measured, and HE staining was performed to evaluate heart function in VMC mice model and sham control. Inflammation factors in serum or cell supernatant were detected by ELISA. Expressions of CaMKIIδ, Toll/interleukin-1 receptor domain containing adaptor protein (TIRAP), insulin-like growth factor 2 mRNA binding protein 2 (IGF2BP2), nuclear factor NF-kappaB (NF-κB) signals, and inflammation factors were examined by quantitative real time polymerase chain reaction (qRT-PCR) or western blot. CCK-8, EdU, and flow cytometry were used to evaluate cell behaviors. Co-immunoprecipitation (Co-IP), RNA immunoprecipitation (RIP), and RNA pull-down were utilized to validate molecule interaction. Methylated RNA immunoprecipitation (MeRIP) was performed to measure N6-methyladenosine (m6A) level of specific molecule.CaMKIIδ was upregulated in VMC mice and CVB3-treated primary cardiomyocytes, of which knockdown improved cell viability, proliferation, and suppressed cell apoptosis in vitro, thereby alleviating myocarditis in vivo. The stability of CaMKIIδ was attributed to the presence of IGF2BP2 through m6A modification. Loss of CaMKIIδ repressed NF-κB pathway via negatively and directly regulating TIRAP to be involved in inflammatory damage.CaMKIIδ, stabilized by m6A reader IGF2BP2, modulated NF-κB pathway via interacting with TIRAP to alter cell viability, proliferation, and apoptosis, thereby affecting VMC outcome.

Assessment of Kinome-Wide Activity Remodeling upon Picornavirus Infection

Picornaviridae represent a large family of single-stranded positive RNA viruses of which different members can infect both humans and animals. These include the enteroviruses (e.g., poliovirus, coxsackievirus, and rhinoviruses) as well as the cardioviruses (e.g., encephalomyocarditis virus). Picornaviruses have evolved to interact with, use, and/or evade cellular host systems to create the optimal environment for replication and spreading. It is known that viruses modify kinase activity during infection, but a proteome-wide overview of the (de)regulation of cellular kinases during picornavirus infection is lacking. To study the kinase activity landscape during picornavirus infection, we here applied dedicated targeted mass spectrometry-based assays covering ∼40% of the human kinome. Our data show that upon infection, kinases of the MAPK pathways become activated (e.g., ERK1/2, RSK1/2, JNK1/2/3, and p38), while kinases involved in regulating the cell cycle (e.g., CDK1/2, GWL, and DYRK3) become inactivated. Additionally, we observed the activation of CHK2, an important kinase involved in the DNA damage response. Using pharmacological kinase inhibitors, we demonstrate that several of these activated kinases are essential for the replication of encephalomyocarditis virus. Altogether, the data provide a quantitative understanding of the regulation of kinome activity induced by picornavirus infection, providing a resource important for developing novel antiviral therapeutic interventions.

CaMKII may regulate renal tubular epithelial cell apoptosis through YAP/NFAT2 in acute kidney injury mice

AIM

Renal tubular epithelial cell (RTEC) apoptosis is important in acute kidney injury (AKI). Calcium/calmodulin-dependent protein kinase II (CaMKII) plays an important role in cell apoptosis, but its potential role in AKI remains unknown.

METHODS

Using co-immunoprecipitation, immunofluorescence, immunohistochemistry, western blotting, flow cytometry, and cell transfection, this study aimed to verify whether CaMKII is involved in RTEC apoptosis and to explore the underlying mechanism.

RESULTS

We found that CaMKII was involved in RTEC apoptosis. In adriamycin-induced AKI mice, serum creatinine levels, cell apoptosis, CaMKII activity, and nuclear factor of activated T cells 2 (NFAT2) levels increased, whereas nuclear Yes-associated protein (YAP) expression decreased; inhibition of CaMKII activity reversed these changes. Phosphorylated CaMKII could bind to phosphorylated YAP in the cytoplasm and block it from entering the nucleus, thereby failing to inhibit NFAT2-mediated cell apoptosis. Sequestrated phosphorylated YAP in the RTEC cytoplasm was finally degraded by ubiquitination.

CONCLUSION

CaMKII may regulate RTEC apoptosis through YAP/NFAT2 in AKI mice. CaMKII may be a potent molecular target for AKI treatment.

4-Phenyl-butyric Acid Inhibits Japanese Encephalitis Virus Replication via Inhibiting Endoplasmic Reticulum Stress Response

Japanese encephalitis virus (JEV) infection causes host endoplasmic reticulum stress (ERS) reaction, and then induces cell apoptosis through the UPR pathway, invading the central nervous system and causing an inflammation storm. The endoplasmic reticulum stress inhibitor, 4-phenyl-butyric acid (4-PBA), has an inhibitory effect on the replication of flavivirus. Here, we studied the effect of 4-PBA on JEV infection both in vitro and vivo. The results showed that 4-PBA treatment could significantly decrease the titer of JEV, inhibit the expression of the JEV NS3 protein (in vitro, p < 0.01) and reduce the positive rate of the JEV E protein (in vivo, p < 0.001). Compared to the control group, 4-PBA treatment can restore the weight of JEV-infected mice, decrease the level of IL-1β in serum and alleviate the abnormalities in brain tissue structure. Endoplasmic reticulum stress test found that the expression level of GRP78 was much lower and activation levels of PERK and IRE1 pathways were reduced in the 4-PBA treatment group. Furthermore, 4-PBA inhibited the UPR pathway activated by NS3, NS4b and NS5 RdRp. The above results indicated that 4-PBA could block JEV replication and inhibit ER stress caused by JEV. Interestingly, 4-PBA could reduce the expression of NS5 by inhibiting transcription (p < 0.001), but had no effect on the expression of NS3 and NS4b. This result may indicate that 4-PBA has antiviral activity independent of the UPR pathway. In summary, the effect of 4-PBA on JEV infection is related to the inhibition of ER stress, and it may be a promising drug for the treatment of Japanese encephalitis.

Mitochondria Dysfunction at the Heart of Viral Myocarditis: Mechanistic Insights and Therapeutic Implications

The myocardium/heart is the most mitochondria-rich tissue in the human body with mitochondria comprising approximately 30% of total cardiomyocyte volume. As the resident "powerhouse" of cells, mitochondria help to fuel the high energy demands of a continuously beating myocardium. It is no surprise that mitochondrial dysfunction underscores the pathogenesis of many cardiovascular ailments, including those of viral origin such as virus-induced myocarditis. Enteroviruses have been especially linked to injuries of the myocardium and its sequelae dilated cardiomyopathy for which no effective therapies currently exist. Intriguingly, recent mechanistic insights have demonstrated viral infections to directly damage mitochondria, impair the mitochondrial quality control processes of the cell, such as disrupting mitochondrial antiviral innate immune signaling, and promoting mitochondrial-dependent pathological inflammation of the infected myocardium. In this review, we briefly highlight recent insights on the virus-mitochondria crosstalk and discuss the therapeutic implications of targeting mitochondria to preserve heart function and ultimately combat viral myocarditis.

Inhibitory of active dual cancer targeting 5-Fluorouracil nanoparticles on liver cancer in vitro and in vivo

The chitosan (CS) material as the skeleton nano-drug delivery system has the advantages of sustained release, biodegradability, and modifiability, and has broad application prospects. In the previous experiments, biotin (Bio) was grafted onto CS to synthesize biotin-modified chitosan (Bio-CS), and it was confirmed that it has liver cancer targeting properties. Single-targeted nanomaterials are susceptible to pathological and physiological factors, resulting in a state of ineffective binding between ligands and receptors, so there is still room for improvement in the targeting of liver cancer. Based on the high expression of folate (FA) receptors on the surface of liver cancers, FA was grafted onto Bio-CS by chemical synthesis to optimize the synthesis of folic acid-modified biotinylated chitosan (FA-CS-Bio), verified by infrared spectroscopy and hydrogen^-1 nuclear magnetic resonance spectroscopy. The release of FA-CS-Bio/fluorouracil (5-FU) had three obvious stages: fast release stage, steady release stage, and slow release stage, with an obvious sustained release effect. Compared with Bio-CS, FA-CS-Bio could promote the inhibition of the proliferation and migration of liver cancer by 5-FU, and the concentration of 5-FU in hepatoma cells was significantly increased dose-dependently. Laser confocal experiments confirmed that FA-CS-Bio caused a significant increase in the fluorescence intensity in liver cancer cells. In terms of animal experiments, FA-CS-Bio increased the concentration of 5-FU in liver cancer tissue by 1.6 times on the basis of Bio-CS and the number of monophotons in liver cancer tissue by in vivo dynamic imaging experiments was significantly stronger than that of Bio-CS, indicating that the targeting ability of FA-CS-Bio was further improved. Compared with Bio-CS, FA-CS-Bio can significantly prolong the survival time of 5-FU in the orthotopic liver cancer transplantation model in mice, and has a relieving effect on liver function damage and bone marrow suppression caused by 5-FU. In conclusion, FA-CS-Bio nanomaterials have been optimized for synthesis. In vivo and in vitro experiments confirmed that FA-CS-Bio can significantly improve the targeting of liver cancer compared with Bio-CS. FA-CS-Bio/5-FU nanoparticles can improve the targeted inhibition of the proliferation and migration of liver cancer cells, prolong the survival period of tumor-bearing mice, and alleviate the toxic and side effects.

Dysregulation of host cell calcium signaling during viral infections: Emerging paradigm with high clinical relevance

Viral infections are one of the leading causes of human illness. Viruses take over host cell signaling cascades for their replication and infection. Calcium (Ca2+) is a versatile and ubiquitous second messenger that modulates plethora of cellular functions. In last two decades, a critical role of host cell Ca2+ signaling in modulating viral infections has emerged. Furthermore, recent literature clearly implicates a vital role for the organellar Ca2+ dynamics (influx and efflux across organelles) in regulating virus entry, replication and severity of the infection. Therefore, it is not surprising that a number of viral infections including current SARS-CoV-2 driven COVID-19 pandemic are associated with dysregulated Ca2+ homeostasis. The focus of this review is to first discuss the role of host cell Ca2+ signaling in viral entry, replication and egress. We further deliberate on emerging literature demonstrating hijacking of the host cell Ca2+ dynamics by viruses. In particular, a variety of viruses including SARS-CoV-2 modulate lysosomal and cytosolic Ca2+ signaling for host cell entry and replication. Moreover, we delve into the recent studies, which have demonstrated the potential of several FDA-approved drugs targeting Ca2+ handling machinery in inhibiting viral infections. Importantly, we discuss the prospective of targeting intracellular Ca2+ signaling for better management and treatment of viral pathogenesis including COVID-19. Finally, we highlight the key outstanding questions in the field that demand critical and timely attention.

In Vitro Model Systems of Coxsackievirus B3-Induced Myocarditis: Comparison of Commonly Used Cell Lines and Characterization of CVB3-Infected iCell® Cardiomyocytes

Coxsackievirus B3 (CVB3) belongs to the enteroviruses, which are a well-known cause of acute and chronic myocarditis, primarily infecting cardiac myocytes. As primary human cardiomyocytes are difficult to obtain, viral myocarditis is quite frequently studied in vitro in different non-cardiac and cardiac-like cell lines. Recently, cardiomyocytes that have been differentiated from human-induced pluripotent stem cells have been described as a new model system to study CVB3 infection. Here, we compared iCell^® Cardiomyocytes with other cell lines that are commonly used to study CVB3 infection regarding their susceptibility and patterns of infection and the mode of cell death. iCell^® Cardiomyocytes, HeLa cells, HL-1 cells and H9c2 cells were infected with CVB3 (Nancy strain). The viral load, CVB3 RNA genome localization, VP1 expression (including the intracellular localization), cellular morphology and the expression of cell death markers were compared. The various cell lines clearly differed in their permissiveness to CVB3 infection, patterns of infection, viral load, and mode of cell death. When studying the mode of cell death of CVB3-infected iCell^® Cardiomyocytes in more detail, especially regarding the necroptosis key players RIPK1 and RIPK3, we found that RIPK1 is cleaved during CVB3 infection. iCell^® Cardiomyocytes represent well the natural host of CVB3 in the heart and are thus the most appropriate model system to study molecular mechanisms of CVB3-induced myocarditis in vitro. Doubts are raised about the suitability of commonly used cell lines such as HeLa cells, HL-1 cells and H9c2 cells to evaluate molecular pathways and processes occurring in vivo in enteroviral myocarditis.

RIPK3-Mediated Necroptosis in Diabetic Cardiomyopathy Requires CaMKII Activation

Activation of Ca²⁺/calmodulin-dependent protein kinase (CaMKII) has been proved to play a vital role in cardiovascular diseases. Receptor-interaction protein kinase 3- (RIPK3-) mediated necroptosis has crucially participated in cardiac dysfunction. The study is aimed at investigating the effect as well as the mechanism of CaMKII activation and necroptosis on diabetic cardiomyopathy (DCM). Wild-type (WT) and the RIPK3 gene knockout (RIPK3^−/−) mice were intraperitoneally injected with 60 mg/kg/d streptozotocin (STZ) for 5 consecutive days. After 12 w of feeding, 100 μL recombinant adenovirus solution carrying inhibitor 1 of protein phosphatase 1 (I1PP1) gene was injected into the caudal vein of mice. Echocardiography, myocardial injury, CaMKII activity, necroptosis, RIPK1 expression, mixed lineage kinase domain-like protein (MLKL) phosphorylation, and mitochondrial ultrastructure were measured. The results showed that cardiac dysfunction, CaMKII activation, and necroptosis were aggravated in streptozotocin- (STZ-) stimulated mice, as well as in (Lepr) KO/KO (db/db) mice. RIPK3 deficiency alleviated cardiac dysfunction, CaMKII activation, and necroptosis in DCM. Furthermore, I1PP1 overexpression reversed cardiac dysfunction, myocardial injury and necroptosis augment, and CaMKII activity enhancement in WT mice with DCM but not in RIPK3^−/− mice with DCM. The present study demonstrated that CaMKII activation and necroptosis augment in DCM via a RIPK3-dependent manner, which may provide therapeutic strategies for DCM.

Novel Insight into the Role of Endoplasmic Reticulum Stress in the Pathogenesis of Myocardial Ischemia-Reperfusion Injury

Impaired function of the endoplasmic reticulum (ER) is followed by evolutionarily conserved cell stress responses, which are employed by cells, including cardiomyocytes, to maintain and/or restore ER homeostasis. ER stress activates the unfolded protein response (UPR) to degrade and remove abnormal proteins from the ER lumen. Although the UPR is an intracellular defense mechanism to sustain cardiomyocyte viability and heart function, excessive activation initiates ER-dependent cardiomyocyte apoptosis. Myocardial ischemia/reperfusion (I/R) injury is a pathological process occurring during or after revascularization of ischemic myocardium. Several molecular mechanisms contribute to the pathogenesis of cardiac I/R injury. Due to the dual protective/degradative effects of ER stress on cardiomyocyte viability and function, it is of interest to understand the basic concepts, regulatory signals, and molecular processes involved in ER stress following myocardial I/R injury. In this review, therefore, we present recent findings related to the novel components of ER stress activation. The complex effects of ER stress and whether they mitigate or exacerbate myocardial I/R injury are summarized to serve as the basis for research into potential therapies for cardioprotection through control of ER homeostasis.

Fulminant myocarditis: a comprehensive review from etiology to treatments and outcomes

Fulminant myocarditis (FM) is characterized by a rapid progressive decline in cardiac function and a high mortality rate. Since the first report of FM patients in the 1980s, several clinical trials and research studies have been published increasing our knowledge regarding FM. Currently, the diagnosis of FM depends on various techniques including electrocardiography, echocardiography, endomyocardial biopsy, and cardiac magnetic resonance. The development of mechanical circulation support (MCS) devices and progress in our understanding of the pathophysiological mechanisms underlying FM, treatment regimens have evolved from simple symptomatic treatment to a life support-based comprehensive treatment approach. The core mechanism underlying the development of FM is the occurrence of an inflammatory cytokine storm. This review provides a comprehensive account of the current understanding of FM pathophysiology and knowledge regarding its etiology, pathophysiology, treatments, and outcomes.

Atherogenic L5 LDL induces cardiomyocyte apoptosis and inhibits KATP channels through CaMKII activation

Background

Cardiac Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) activation plays a critical role in cardiomyocyte (CM) apoptosis and arrhythmia. Functional ATP-sensitive potassium (K_ATP) channels are essential for cardiac protection during ischemia. In cultured CMs, L5 low-density lipoprotein (LDL) induces apoptosis and QTc prolongation. L5 is a highly electronegative and atherogenic aberrant form of LDL, and its levels are significantly higher in patients with cardiovascular-related diseases. Here, the role of L5 in cardiac injury was studied by evaluating the effects of L5 on CaMKII activity and K_ATP channel physiology in CMs.

Methods

Cultured neonatal rat CMs (NRCMs) were treated with a moderate concentration (ie, 7.5 μg/mL) of L5 or L1 (the least electronegative LDL subfraction). NRCMs were examined for apoptosis and viability, CaMKII activity, and the expression of phosphorylated CaMKIIδ and NOX2/gp91^phox. The function of K_ATP and action potentials (APs) was analyzed by using the patch-clamp technique.

Results

In NRCMs, L5 but not L1 significantly induced cell apoptosis and reduced cell viability. Furthermore, L5 decreased Kir6.2 expression by more than 50%. Patch-clamp analysis showed that L5 reduced the K_ATP current (I_KATP) density induced by pinacidil, a K_ATP opener. The partial recovery of the inward potassium current during pinacidil washout was susceptible to subsequent inhibition by the I_KATP blocker glibenclamide. Suppression of I_KATP by L5 significantly prolonged the AP duration. L5 also significantly increased the activity of CaMKII, the phosphorylation of CaMKIIδ, and the expression of NOX2/gp91^phox. L5-induced apoptosis was prevented by the addition of the CaMKII inhibitor KN93 and the reactive oxygen species scavenger Mn (III)TBAP.

Conclusions

L5 but not L1 induces CM damage through the activation of the CaMKII pathway and increases arrhythmogenicity in CMs by modulating the AP duration. These results help to explain the harmful effects of L5 in cardiovascular-related disease.