A pivotal role for the multifunctional calcium/calmodulin-dependent protein kinase II in T cells: from activation to unresponsiveness

Therapeutic Potential of Intermittent Hypoxia in Atrial Fibrillation

Intermittent hypoxia (IH) has been extensively studied in recent years, demonstrating adverse and beneficial effects on several physiological systems. However, the precise mechanism underlying its cardiac effects on the heart remains unclear. This study aims to explore the effect of treatment on atrial fibrillation under IH conditions, providing data that can potentially be used in the treatment of heart disease. An atrial fibrillation (AF) model was induced by injecting monocrotaline (MCT, 60 mg/kg) into rats. The study included 32 rats divided into four groups: Control, Control + IH, AF, and AF + IH. We evaluated molecular changes associated with AF using ELISA and Western blot and performed electrophysiological experiments to evaluate AF. Arrhythmia-related calcium and fibrosis markers were investigated. Phosphorylation levels of CaMKII, Phospholamban, and RyR2 all increased in the AF group but decreased in the IH-exposed group. Additionally, fibrosis marker expressions such as SMA, MMP2, MMP9, and TGF-β increased in the AF group but were significantly downregulated with IH treatment. Connexin 43 and AQP4 expression were restored in the IH-treated group. These findings suggest that IH may prevent AF by downregulating the expression of calcium-handling proteins and fibrosis-associated proteins in an AF-induced rat model.

GSNOR overexpression enhances CAR-T cell stemness and anti-tumor function by enforcing mitochondrial fitness

Chimeric antigen receptor-T (CAR-T) cell has been developed as a promising agent for patients with refractory or relapsed lymphoma and leukemia, but not all the recipients could achieve a long-lasting remission. The limited capacity of in vivo expansion and memory differentiation post activation is one of the major reasons for suboptimal CAR-T therapeutic efficiency. Nitric oxide (NO) plays multifaceted roles in mitochondrial dynamics and T cell activation, but its function on CAR-T cell persistence and anti-tumor efficacy remains unknown. Herein, we found the continuous signaling from CAR not only promotes excessive NO production, but also suppressed S-nitrosoglutathione reductase (GSNOR) expression in T cells, which collectively led to increased protein S-nitrosylation, resulting in impaired mitochondrial fitness and deficiency of T cell stemness. Intriguingly, enforced expression of GSNOR promoted memory differentiation of CAR-T cell after immune activation, rendered CAR-T better resistance to mitochondrial dysfunction, further enhanced CAR-T cell expansion and anti-tumor capacity in vitro and in a mouse tumor model. Thus, we revealed a critical role of NO in restricting CAR-T cell persistence and functionality, and defined that GSNOR overexpression may provide a solution to combat NO stress and render patients with more durable protection from CAR-T therapy.

Calmodulin Contributes to Lipolysis and Inflammatory Responses in Clinical Ketosis Cows through the TLR4/IKK/NF-κB Pathway

Clinical ketosis is a detrimental metabolic disease in dairy cows, often accompanied by severe lipolysis and inflammation in adipose tissue. Our previous study suggested a 2.401-fold upregulation in the calmodulin (CaM) level in the adipose tissue of cows with clinical ketosis. Therefore, we hypothesized that CaM may regulate lipolysis and inflammatory responses in cows with clinical ketosis. To verify the hypothesis, we conducted a thorough veterinary assessment of clinical symptoms and serum β-hydroxybutyrate (BHB) concentration. Subsequently, we collected subcutaneous adipose tissue samples from six healthy and six clinically ketotic Holstein cows at 17 ± 4 days postpartum. Commercial kits were used to test the abundance of BHB, non-esterified fatty acid (NEFA), the liver function index (LFI), interleukin-6 (IL-6), IL-1β, and tumor necrosis factor-α (TNF-α). We found that cows with clinical ketosis exhibited higher levels of BHB, NEFA, LFI, IL-6, IL-1β, TNF-α, and lower glucose levels than healthy cows. Furthermore, the abundance of CaM, toll-like receptor 4 (TLR4), inhibitor of nuclear factor κB kinase subunit β (IKK), phosphorylated nuclear factor κB p65/nuclear factor κB p65 (p-NF-κB p65/NF-κB p65), adipose triacylglycerol lipase (ATGL), and phosphorylated hormone-sensitive lipase/hormone-sensitive lipase (p-HSL/HSL) was increased, while that of perilipin-1 (PLIN1) was decreased in the adipose tissue of cows with clinical ketosis. To investigate the mechanism underlying the responses, we isolated the primary bovine adipocytes from the adipose tissue of healthy cows and induced the inflammatory response mediated by TLR4/IKK/NF-κB p65 with lipopolysaccharide (LPS). Additionally, we treated the primary bovine adipocytes with CaM overexpression adenovirus and CaM small interfering RNA. In vitro, LPS upregulated the abundance of TLR4, IKK, p-NF-κB p65, ATGL, p-HSL/HSL, and CaM and downregulated PLIN1. Furthermore, CaM silencing downregulated the abundance of LPS-activated p-HSL/HSL, TLR4, IKK, and p-NF-κB p65 and upregulated PLIN1 in bovine adipocytes, except for ATGL. However, CaM overexpression upregulated the abundance of LPS-activated p-HSL/HSL, TLR4, IKK, and p-NF-κB p65 and downregulated PLIN1 expression in bovine adipocytes. These data suggest that CaM promotes lipolysis in adipocytes through HSL and PINL1 while activating the TLR4/IKK/NF-κB inflammatory pathway to stimulate an inflammatory response. There is a positive feedback loop between CaM, lipolysis, and inflammation. Inhibiting CaM may act as an adaptive mechanism to alleviate metabolic dysregulation in adipose tissue, thereby relieving lipolysis and inflammatory responses.

Understanding the pathogenic significance of altered calcium-calmodulin signaling in T cells in autoimmune diseases

Calcium/calmodulin-dependent protein kinase IV (CaMK4) serves as a pivotal mediator in the regulation of gene expression, influencing the activity of transcription factors within a variety of immune cells, including T cells. Altered CaMK4 signaling is implicated in autoimmune diseases such as systemic lupus erythematosus, rheumatoid arthritis, and psoriasis, which are characterized by dysregulated immune responses and clinical complexity. These conditions share common disturbances in immune cell functionality, cytokine production, and autoantibody generation, all of which are associated with disrupted calcium-calmodulin signaling. This review underscores the consequences of dysregulated CaMK4 signaling across these diseases, with an emphasis on its impact on Th17 differentiation and T cell metabolism-processes central to maintaining immune homeostasis. A comprehensive understanding of roles of CaMK4 in gene regulation across various autoimmune disorders holds promise for the development of targeted therapies, particularly for diseases driven by Th17 cell dysregulation.

Targeting NLRP3 signaling reduces myocarditis-induced arrhythmogenesis and cardiac remodeling

BACKGROUND

Myocarditis substantially increases the risk of ventricular arrhythmia. Approximately 30% of all ventricular arrhythmia cases in patients with myocarditis originate from the right ventricular outflow tract (RVOT). However, the role of NLRP3 signaling in RVOT arrhythmogenesis remains unclear.

METHODS

Rats with myosin peptide-induced myocarditis (experimental group) were treated with an NLRP3 inhibitor (MCC950; 10 mg/kg, daily for 14 days) or left untreated. Then, they were subjected to electrocardiography and echocardiography. Ventricular tissue samples were collected from each rat's RVOT, right ventricular apex (RVA), and left ventricle (LV) and examined through conventional microelectrode and histopathologic analyses. In addition, whole-cell patch-clamp recording, confocal fluorescence microscopy, and Western blotting were performed to evaluate ionic currents, intracellular Ca2+ transients, and Ca2+-modulated protein expression in individual myocytes isolated from the RVOTs.

RESULTS

The LV ejection fraction was lower and premature ventricular contraction frequency was higher in the experimental group than in the control group (rats not exposed to myosin peptide). Myocarditis increased the infiltration of inflammatory cells into cardiac tissue and upregulated the expression of NLRP3; these observations were more prominent in the RVOT and RVA than in the LV. Furthermore, experimental rats treated with MCC950 (treatment group) improved their LV ejection fraction and reduced the frequency of premature ventricular contraction. Histopathological analysis revealed higher incidence of abnormal automaticity and pacing-induced ventricular tachycardia in the RVOTs of the experimental group than in those of the control and treatment groups. However, the incidences of these conditions in the RVA and LV were similar across the groups. The RVOT myocytes of the experimental group exhibited lower Ca2+ levels in the sarcoplasmic reticulum, smaller intracellular Ca2+ transients, lower L-type Ca2+ currents, larger late Na+ currents, larger Na+-Ca2+ exchanger currents, higher reactive oxygen species levels, and higher Ca2+/calmodulin-dependent protein kinase II levels than did those of the control and treatment groups.

CONCLUSION

Myocarditis may increase the rate of RVOT arrhythmogenesis, possibly through electrical and structural remodeling. These changes may be mitigated by inhibiting NLRP3 signaling.

Calcium-Associated Proteins in Neuroregeneration

The dysregulation of intracellular calcium levels is a critical factor in neurodegeneration, leading to the aberrant activation of calcium-dependent processes and, ultimately, cell death. Ca2+ signals vary in magnitude, duration, and the type of neuron affected. A moderate Ca2+ concentration can initiate certain cellular repair pathways and promote neuroregeneration. While the peripheral nervous system exhibits an intrinsic regenerative capability, the central nervous system has limited self-repair potential. There is evidence that significant variations exist in evoked calcium responses and axonal regeneration among neurons, and individual differences in regenerative capacity are apparent even within the same type of neurons. Furthermore, some studies have shown that neuronal activity could serve as a potent regulator of this process. The spatio-temporal patterns of calcium dynamics are intricately controlled by a variety of proteins, including channels, ion pumps, enzymes, and various calcium-binding proteins, each of which can exert either positive or negative effects on neural repair, depending on the cellular context. In this concise review, we focus on several calcium-associated proteins such as CaM kinase II, GAP-43, oncomodulin, caldendrin, calneuron, and NCS-1 in order to elaborate on their roles in the intrinsic mechanisms governing neuronal regeneration following traumatic damage processes.

The interplay of inflammation, exosomes and Ca2+ dynamics in diabetic cardiomyopathy

Diabetes mellitus is one of the prime risk factors for cardiovascular complications and is linked with high morbidity and mortality. Diabetic cardiomyopathy (DCM) often manifests as reduced cardiac contractility, myocardial fibrosis, diastolic dysfunction, and chronic heart failure. Inflammation, changes in calcium (Ca²⁺) handling and cardiomyocyte loss are often implicated in the development and progression of DCM. Although the existence of DCM was established nearly four decades ago, the exact mechanisms underlying this disease pathophysiology is constantly evolving. Furthermore, the complex pathophysiology of DCM is linked with exosomes, which has recently shown to facilitate intercellular (cell-to-cell) communication through biomolecules such as micro RNA (miRNA), proteins, enzymes, cell surface receptors, growth factors, cytokines, and lipids. Inflammatory response and Ca²⁺ signaling are interrelated and DCM  has been known to adversely affect many of these signaling molecules either qualitatively and/or quantitatively. In this literature review, we have demonstrated that Ca²⁺ regulators are tightly controlled at different molecular and cellular levels during various biological processes in the heart. Inflammatory mediators, miRNA and exosomes are shown to interact with these regulators, however how these mediators are linked to Ca²⁺ handling during DCM pathogenesis remains elusive. Thus, further investigations are needed to understand the mechanisms to restore cardiac Ca²⁺ homeostasis and function, and to serve as potential therapeutic targets in the treatment of DCM.

RIPK3 controls MAIT cell accumulation during development but not during infection

Cell death mechanisms in T lymphocytes vary according to their developmental stage, cell subset and activation status. The cell death control mechanisms of mucosal-associated invariant T (MAIT) cells, a specialized T cell population, are largely unknown. Here we report that MAIT cells express key necroptotic machinery; receptor-interacting protein kinase 3 (RIPK3) and mixed lineage kinase domain-like (MLKL) protein, in abundance. Despite this, we discovered that the loss of RIPK3, but not necroptotic effector MLKL or apoptotic caspase-8, specifically increased MAIT cell abundance at steady-state in the thymus, spleen, liver and lungs, in a cell-intrinsic manner. In contrast, over the course of infection with Francisella tularensis, RIPK3 deficiency did not impact the magnitude of the expansion nor contraction of MAIT cell pools. These findings suggest that, distinct from conventional T cells, the accumulation of MAIT cells is restrained by RIPK3 signalling, likely prior to thymic egress, in a manner independent of canonical apoptotic and necroptotic cell death pathways.

Inhibition of calcium/calmodulin-dependent protein kinase IV in arthritis: dual effect on Th17 cell activation and osteoclastogenesis

OBJECTIVE

To investigate the role of calcium/calmodulin-dependent protein kinase IV (CaMK4) in the development of joint injury in a mouse model of arthritis and patients with RA.

METHODS

Camk4-deficient, Camk4flox/floxLck-Cre, and mice treated with CaMK4 inhibitor KN-93 or KN-93 encapsulated in nanoparticles tagged with CD4 or CD8 antibodies were subjected to collagen-induced arthritis (CIA). Inflammatory cytokine levels, humoral immune response, synovitis, and T-cell activation were recorded. CAMK4 gene expression was measured in CD4+ T cells from healthy participants and patients with active RA. Micro-CT and histology were used to assess joint pathology. CD4+ and CD14+ cells in patients with RA were subjected to Th17 or osteoclast differentiation, respectively.

RESULTS

CaMK4-deficient mice subjected to CIA displayed improved clinical scores and decreased numbers of Th17 cells. KN-93 treatment significantly reduced joint destruction by decreasing the production of inflammatory cytokines. Furthermore, Camk4flox/floxLck-Cre mice and mice treated with KN93-loaded CD4 antibody-tagged nanoparticles developed fewer Th17 cells and less severe arthritis. CaMK4 inhibition mitigated IL-17 production by CD4+ cells in patients with RA. The number of in vitro differentiated osteoclasts from CD14+ cells in patients with RA was significantly decreased with CaMK4 inhibitors.

CONCLUSION

Using global and CD4-cell-targeted pharmacologic approaches and conditionally deficient mice, we demonstrate that CaMK4 is important in the development of arthritis. Using ex vivo cell cultures from patients with RA, CaMK4 is important for both Th17 generation and osteoclastogenesis. We propose that CaMK4 inhibition represents a new approach to control the development of arthritis.

Voltage-Gated T-Type Calcium Channel Modulation by Kinases and Phosphatases: The Old Ones, the New Ones, and the Missing Ones

Calcium (Ca2+) can regulate a wide variety of cellular fates, such as proliferation, apoptosis, and autophagy. More importantly, changes in the intracellular Ca2+ level can modulate signaling pathways that control a broad range of physiological as well as pathological cellular events, including those important to cellular excitability, cell cycle, gene-transcription, contraction, cancer progression, etc. Not only intracellular Ca2+ level but the distribution of Ca2+ in the intracellular compartments is also a highly regulated process. For this Ca2+ homeostasis, numerous Ca2+ chelating, storage, and transport mechanisms are required. There are also specialized proteins that are responsible for buffering and transport of Ca2+. T-type Ca2+ channels (TTCCs) are one of those specialized proteins which play a key role in the signal transduction of many excitable and non-excitable cell types. TTCCs are low-voltage activated channels that belong to the family of voltage-gated Ca2+ channels. Over decades, multiple kinases and phosphatases have been shown to modulate the activity of TTCCs, thus playing an indirect role in maintaining cellular physiology. In this review, we provide information on the kinase and phosphatase modulation of TTCC isoforms Cav3.1, Cav3.2, and Cav3.3, which are mostly described for roles unrelated to cellular excitability. We also describe possible potential modulations that are yet to be explored. For example, both mitogen-activated protein kinase and citron kinase show affinity for different TTCC isoforms; however, the effect of such interaction on TTCC current/kinetics has not been studied yet.

Calcium/Calmodulin-Stimulated Protein Kinase II (CaMKII): Different Functional Outcomes from Activation, Depending on the Cellular Microenvironment

Calcium/calmodulin-stimulated protein kinase II (CaMKII) is a family of broad substrate specificity serine (Ser)/threonine (Thr) protein kinases widely expressed in many tissues that is capable of mediating diverse functional responses depending on its cellular and molecular microenvironment. This review briefly summarises current knowledge on the structure and regulation of CaMKII and focuses on how the molecular environment, and interaction with binding partner proteins, can produce different populations of CaMKII in different cells, or in different subcellular locations within the same cell, and how these different populations of CaMKII can produce diverse functional responses to activation following an increase in intracellular calcium concentration. This review also explores the possibility that identifying and characterising the molecular interactions responsible for the molecular targeting of CaMKII in different cells in vivo, and identifying the sites on CaMKII and/or the binding proteins through which these interactions occur, could lead to the development of highly selective inhibitors of specific CaMKII-mediated functional responses in specific cells that would not affect CaMKII-mediated responses in other cells. This may result in the development of new pharmacological agents with therapeutic potential for many clinical conditions.

Investigation of Rare Non-Coding Variants in Familial Multiple Myeloma

Multiple myeloma (MM) is a plasma cell malignancy whereby a single clone of plasma cells over-propagates in the bone marrow, resulting in the increased production of monoclonal immunoglobulin. While the complex genetic architecture of MM is well characterized, much less is known about germline variants predisposing to MM. Genome-wide sequencing approaches in MM families have started to identify rare high-penetrance coding risk alleles. In addition, genome-wide association studies have discovered several common low-penetrance risk alleles, which are mainly located in the non-coding genome. Here, we further explored the genetic basis in familial MM within the non-coding genome in whole-genome sequencing data. We prioritized and characterized 150 upstream, 5' untranslated region (UTR) and 3' UTR variants from 14 MM families, including 20 top-scoring variants. These variants confirmed previously implicated biological pathways in MM development. Most importantly, protein network and pathway enrichment analyses also identified 10 genes involved in mitogen-activated protein kinase (MAPK) signaling pathways, which have previously been established as important MM pathways.

Adeno-associated virus-mediated expression of an inactive CaMKIIβ mutant enhances muscle mass and strength in mice

A concurrent reduction in muscle mass and strength is frequently observed in numerous conditions, including neuromuscular disease, ageing, and muscle inactivity due to limb immobilization or prolonged bed rest. Thus, identifying the molecular mechanisms that control skeletal muscle mass and strength is fundamental for developing interventions aimed at counteracting muscle loss (muscle atrophy). It was recently reported that muscle atrophy induced by denervation of motor nerves was associated with increased expression of Ca2+/calmodulin-dependent protein serine/threonine kinase II β (CaMKIIβ) in muscle. In addition, treatment with KN-93 phosphate, which inhibits CaMKII-family kinases, partly suppressed denervation-induced muscle atrophy. Therefore, to test a possible role for CaMKIIβ in muscle mass regulation, we generated and injected recombinant adeno-associated virus (AAV) vectors encoding wild-type (AAV-WT), inactive (AAV-K43 M), or constitutively active (AAV-T287D) CaMKIIβ into the left hindlimb tibialis anterior muscle of mice at three months of age. Although AAV-WT infection induced expression of exogenous CaMKIIβ in the hindlimb muscle, no significant changes in muscle mass and strength were observed. By contrast, AAV-K43 M or AAV-T287D infection induced exogenous expression of the corresponding mutants and significantly increased or decreased the muscle mass and strength of the infected hind limb, respectively. Together, these findings demonstrate the potential of CaMKIIβ as a novel therapeutic target for enhancing muscle mass and strength.

CRAC Channel Controls the Differentiation of Pathogenic B Cells in Lupus Nephritis

Store-operated Ca²⁺ release-activated Ca²⁺ (CRAC) channel is the main Ca²⁺ influx pathway in lymphocytes and is essential for immune response. Lupus nephritis (LN) is an autoimmune disease characterized by the production of autoantibodies due to widespread loss of immune tolerance. In this study, RNA-seq analysis revealed that calcium transmembrane transport and calcium channel activity were enhanced in naive B cells from patients with LN. The increased expression of ORAI1, ORAI2, and STIM2 in naive B cells from patients with LN was confirmed by flow cytometry and Western blot, implying a role of CRAC channel in B-cell dysregulation in LN. For in vitro study, CRAC channel inhibition by YM-58483 or downregulation by ORAI1-specific small-interfering RNA (siRNA) decreased the phosphorylation of Ca²⁺/calmodulin-dependent protein kinase2 (CaMK2) and suppressed Blimp-1 expression in primary human B cells, resulting in decreased B-cell differentiation and immunoglobulin G (IgG) production. B cells treated with CaMK2-specific siRNA showed defects in plasma cell differentiation and IgG production. For in vivo study, YM-58483 not only ameliorated the progression of LN but also prevented the development of LN. MRL/lpr lupus mice treated with YM-58483 showed lower percentage of plasma cells in the spleen and reduced concentration of anti-double-stranded DNA antibodies in the sera significantly. Importantly, mice treated with YM-58483 showed decreased immune deposition in the glomeruli and alleviated kidney damage, which was further confirmed in NZM2328 lupus mice. Collectively, CRAC channel controlled the differentiation of pathogenic B cells and promoted the progression of LN. This study provides insights into the pathogenic mechanisms of LN and that CRAC channel could serve as a potential therapeutic target for LN.

In vitro and in vivo study on prevention of myocardial ischemic injury by taurine

Background

Myocardial ischemia (MI) often causes angina, arrhythmia, and cardiac insufficiency, sometimes resulting in death. Ischemia-induced myocardial tissue damage is attributed to the hypoxic damage of myocardial cells producing apoptosis and decreased proliferation. Taurine has been shown to improve MI, but its mechanism is largely unknown.

Methods

In this study, the relationship between taurine and severity of MI in vivo was evaluated by quantifying myocardial infarct areas and metabolic indicators of myocardial damage and measuring taurine levels in cardiac muscle and plasma by high performance liquid chromatography (HPLC). To elucidate how taurine might suppress ischemic injury, we established an in vitro ischemia model with isolated primary rat cardiomyocytes cultured without serum or glucose and under hypoxia. We evaluated the indicators of MI and damage, including lactic dehydrogenase (LDH), creatine kinase (CK), and cardiac troponin I (cTnI). We also examined the levels of taurine transporter (TauT), cysteine dioxygenase (CDO), and cysteine sulfinate decarboxylase (CSD) proteins involved in transport and synthesis of taurine in the myocardium and those of 2 apoptosis-associated proteins, namely, Bcl-2 associated X protein (BAX) and B-cell lymphoma-2 (Bcl-2).

Results

Exposure of myocardial cells to ischemia led to the decrease of taurine content, the suppression of cell proliferation, and led to calcium ion overload and apoptosis. Pretreatment with taurine alleviated the ischemic damage, with concomitant elevation of intracellular taurine concentrations. Molecular mechanism analysis showed that pretreatment with taurine upregulated the TauT, CDO, and CSD, 2 rate-limiting enzymes involved in taurine synthesis. These effects facilitated both taurine transport into cells and taurine synthesis, leading to taurine accumulation. In addition, apoptosis inhibition by taurine appeared to be mediated by upregulated Bcl-2 and downregulated BAX, as well as inhibition of calcium overload by suppression of calcium binding protein.

Conclusions

We demonstrated that TauT is critical for the attenuation of myocardial ischemic damage by taurine, facilitating taurine absorption and synthesis. These findings provided new insights and a theoretical foundation for future studies examining taurine as a potential treatment for MI.

Physical interactions driving the activation/inhibition of calcium/calmodulin dependent protein kinase II

CaMKII is a protein kinase whose function is regulated by the binding of the Calcium/Calmodulin complex (Ca²⁺/CaM). It is a major player in the Long Term Potentiation process where it acts as a molecular switch, oscillating between inhibited and active conformations. The mechanism for the switching is thought to be initiated by Ca²⁺/CaM binding, which allows the trans-phosphorylation of a subunit of CaMKII by a neighboring kinase, leading to the active state of the system. A combination of all-atom and coarse-grained MD simulations with free energy calculations, led us to reveal an interplay of electrostatic forces exerted by Ca²⁺/CaM on CaMKII, which initiate the activation process. The highly electrically charged Ca²⁺/CaM neutralizes basic regions in the linker domain of CaMKII, facilitating its opening and consequent activation. The emerging picture of CaMKII's behavior highlights the preponderance of electrostatic interactions, which are modulated by the presence of Ca²⁺/CaM and the phosphorylation of key sites.

S1PR4 ablation reduces tumor growth and improves chemotherapy via CD8+ T cell expansion

Tumor immunosuppression is a limiting factor for successful cancer therapy. The lipid sphingosine-1-phosphate (S1P), which signals through 5 distinct G protein-coupled receptors (S1PR1-5), has emerged as an important regulator of carcinogenesis. However, the utility of targeting S1P in tumors is hindered by S1P's impact on immune cell trafficking. Here, we report that ablation of the immune cell-specific receptor S1PR4, which plays a minor role in immune cell trafficking, delayed tumor development and improved therapy success in murine models of mammary and colitis-associated colorectal cancer through increased CD8+ T cell abundance. Transcriptome analysis revealed that S1PR4 affected proliferation and survival of CD8+ T cells in a cell-intrinsic manner via the expression of Pik3ap1 and Lta4h. Accordingly, PIK3AP1 expression was connected to increased CD8+ T cell proliferation and clinical parameters in human breast and colon cancer. Our data indicate a so-far-unappreciated tumor-promoting role of S1P by restricting CD8+ T cell expansion via S1PR4.

Differential DNA methylation in recovery from shift work disorder

The human DNA methylome is responsive to our environment, but its dynamics remain underexplored. We investigated the temporal changes to DNA methylation (DNAme) in relation to recovery from a shift work disorder (SWD) by performing a paired epigenome-wide analysis in an occupational cohort of 32 shift workers (25 men, age = 43.8 ± 8.8 years, 21 SWD cases). We found that the effect of vacation on DNAme was more prominent in the SWD-group as compared to controls, with respect to the amount of significantly differentially methylated positions (DMPs; P_unadj < 0.05) 6.5 vs 3.7%, respectively. The vast majority (78%) of these DMPs were hypomethylated in SWD but not in controls (27%) during the work period. The Gene Ontology Cellular component "NMDA glutamate receptor" (P_FDR < 0.05) was identified in a pathway analysis of the top 30 genes in SWD. In-depth pathway analyses revealed that the Reactome pathway "CREB phosphorylation through the activation of CaMKII" might underlie the recovery. Furthermore, three DMPs from this pathway, corresponding to GRIN2C, CREB1, and CAMK2B, correlated with the degree of recovery (P_unadj < 0.05). Our findings provide evidence for the dynamic nature of DNAme in relation to the recovery process from a circadian disorder, with biological relevance of the emerging pathways.

Current Insights and Future Prospects for Targeting IL-17 to Treat Patients With Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by immune cell abnormalities which lead to the production of autoantibodies and the deposition of immune complexes. Interleukin (IL)-17-producing cells play an important role in the pathogenesis of the disease, making them an attractive therapeutic target. Studies in lupus-prone mice and of ex vivo cells from patients with SLE humans have shown that IL-17 represents a promising therapeutic target. Here we review molecular mechanisms involved in IL-17 production and Th17 cell differentiation and function and an update on the role of IL-17 in autoimmune diseases and the expected usefulness for targeting IL-17 therapeutically.

CaMKIIγ regulates the viability and self-renewal of acute myeloid leukaemia stem-like cells by the Alox5/NF-κB pathway

Acute myeloid leukaemia (AML) is a frequently fatal malignant disease of haematopoietic stem and progenitor cells. The molecular and phenotypic characteristics of AML are highly heterogeneous. Our previous study concluded that CaMKIIγ was the trigger of chronic myeloid leukaemia progression from the chronic phase to blast crisis, but how CaMKIIγ influences AML stem-like cells remains elusive. In this study, we found that CaMKIIγ was overexpressed in AML patients and AML cell lines, as measured by qRT-PCR and Western blot assays. Moreover, CaMKIIγ decreased when the disease was in remission. Using an shRNA lentivirus expression system, we established CaMKIIγ stable-knockdown AML cell lines and found that knockdown of CaMKIIγ inhibited the viability and self-renewal of AML stem-like cell lines. Additionally, the ratio of CD₃₄ ⁺ AML cell lines decreased, and CaMKIIγ knockdown induced the downregulation of Alox5 levels. We further detected downstream molecules of the Alox5/NF-κB pathway and found that c-myc and p-IκBα decreased while total IκBα remained normal. In conclusion, our study describes a new role for CaMKIIγ as a stem-like cell marker that is highly regulated by the Alox5/NF-κB pathway in AML stem-like cells. CaMKIIγ can participate in the viability and self-renewal of AML stem-like cells by regulating the Alox5/NF-κB pathway.

Basic concepts and physical-chemical phenomena, that have conceptual meaning for the formation of systemic clinical thinking and formalization of the knowledge of systemic structural-functional organization of the human’s organism

From the point of view of perception and generalization processes there are complex, logic and conceptual forms of thinking. Its conceptual form is the highest result of interaction between thinking and speech. While realizing it, human uses the concept, which are logically formed thoughts, that are the meaning of representation in thinking of unity of meaningful features, relations of subjects or phenomena of objective reality. Special concepts, that are used in the science and technique are called terms. They perform a function of corresponding, special, precise marking of subjects and phenomena, their features and interactions. Scientific knowledge are in that way an objective representation of material duality in our consciousness. Certain complex of terms forms a terminological system, that lies in the basis of corresponding sphere of scientific knowledge and conditions a corresponding form and way of thinking. Clinical thinking is a conceptual form, that manifests and represents by the specialized internal speech with gnostic motivation lying in its basis. Its structural elements are corresponding definitions, terms and concepts. Cardinal features of clinical systems are consistency, criticality, justification and substantiation. Principles of perception and main concepts are represented in the article along with short descriptions of physical and chemical phenomena, that have conceptual meaning for the formation of systematic clinical thinking and formalization of systemic structural-functional organization of the human’s organism

Calcium/calmodulin-dependent protein kinase IV signaling pathway is upregulated in experimental necrotizing enterocolitis

PURPOSE

Activation of calcium/calmodulin-dependent protein kinase IV (CaMKIV) has been shown to increase intestinal injury and inhibit epithelial cell proliferation in dextran sulfate sodium (DSS)-induced colitis mice. However, the role of CaMKIV in necrotizing enterocolitis (NEC) is unknown. We aimed to study the expression and activation of CaMKIV in experimental NEC.

METHODS

Following ethical approval, NEC (n = 10) was induced in C57BL/6 mouse pups by hypoxia, gavage hyperosmolar formula feeding and lipopolysaccharide from postnatal days P5 to 9. Breastfed pups served as control (n = 10). Mouse pups were sacrificed on P9 and the terminal ileum was harvested. Gene NEC injury was scored blindly by three independent investigators. CaMKIV, CREM and IL17 gene expression, and CaMKIV and pCaMKIV protein expression were assessed. The data were compared using Mann-Whitney U test. P < 0.05 was considered significant.

RESULTS

Intestinal injury was induced in the NEC mice and confirmed by histological scoring and inflammatory cytokine IL6. CaMKIV and its downstream target genes of CREM and IL17 were significantly elevated in NEC mice relative to control. Similarly, phosphorylated-CaMKIV (pCaMKIV), the active form of CaMKIV, was more notably expressed in the NEC ileal tissue relative to control ileal tissue. Elevated pCaMKIV protein expression was also confirmed by western blot.

CONCLUSION

CaMKIV expression and activation are upregulated in experimental NEC suggesting a potential contributing factor in the pathogenesis of NEC.

Rapamycin inhibits B-cell activating factor (BAFF)-stimulated cell proliferation and survival by suppressing Ca2+-CaMKII-dependent PTEN/Akt-Erk1/2 signaling pathway in normal and neoplastic B-lymphoid cells

B-cell activating factor (BAFF) is a crucial survival factor for B cells, and excess BAFF contributes to development of autoimmune diseases. Recent studies have shown that rapamycin can prevent BAFF-induced B-cell proliferation and survival, but the underlying mechanism remains to be elucidated. Here we found that rapamycin inhibited human soluble BAFF (hsBAFF)-stimulated cell proliferation by inducing G₁-cell cycle arrest, which was through downregulating the protein levels of CDK2, CDK4, CDK6, cyclin A, cyclin D1, and cyclin E. Rapamycin reduced hsBAFF-stimulated cell survival by downregulating the levels of anti-apoptotic proteins (Mcl-1, Bcl-2, Bcl-xL and survivin) and meanwhile upregulating the levels of pro-apoptotic proteins (BAK and BAX). The cytostatic and cytotoxic effects of rapamycin linked to its attenuation of hsBAFF-elevated intracellular free Ca²⁺ ([Ca²⁺]_i). In addition, rapamycin blocked hsBAFF-stimulated B-cell proliferation and survival by preventing hsBAFF from inactivating PTEN and activating the Akt-Erk1/2 pathway. Overexpression of wild type PTEN or ectopic expression of dominant negative Akt potentiated rapamycin's suppression of hsBAFF-induced Erk1/2 activation and proliferation/viability in Raji cells. Interestingly, PP242 (mTORC1/2 inhibitor) or Akt inhibitor X, like rapamycin (mTORC1 inhibitor), reduced the basal or hsBAFF-induced [Ca²⁺]_i elevations. Chelating [Ca²⁺]_i with BAPTA/AM, preventing [Ca²⁺]_i elevation using EGTA, 2-APB or verapamil, inhibiting CaMKII with KN93, or silencing CaMKII strengthened rapamycin's inhibitory effects. The results indicate that rapamycin inhibits BAFF-stimulated B-cell proliferation and survival by blunting mTORC1/2-mediated [Ca²⁺]_i elevations and suppressing Ca²⁺-CaMKII-dependent PTEN/Akt-Erk1/2 signaling pathway. Our finding underscores that rapamycin may be exploited for prevention of excessive BAFF-induced aggressive B-cell malignancies and autoimmune diseases.

Transcriptome sequencing reveals phagocytosis as the main immune response in the pathogen-challenged sea urchin Strongylocentrotus intermedius

The clarification of host immune responses to causative bacteria of spotting disease in the sea urchin Strongylocentrotus intermedius is vital to preventing and controlling this disease, especially to selective breeding for disease resistance. For this purpose, sea urchins were challenged with the causative bacterium Vibrio sp. to obtain spotting diseased and undiseased samples. We conducted next-generation sequencing to assess the key genes/pathways in control (CG), diseased (DG), and undiseased (UG) groups. A total of 454.1 million clean reads were obtained and assembled into 23,899 UniGenes with an N50 of 1359 bp, with 86.11% of them matching the genome sequence of the sea urchin S. purpuratus. A total of 8415 UniGenes were mapped to the non-redundant database. Salmon expression analysis revealed 725 significantly differentially expressed genes (DEGs) among CG, DG, and UG. These DEGs were enriched into 72 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, including a core set of immune correlated pathways notably in the phagosome, vitamin digestion and absorption, Wnt signaling, and Notch signaling pathways. DG was evidently upregulated in these immune pathways and could enhance phagocytosis directly or indirectly. Thus, phagocytosis was the main coelomic cellular immune response in S. intermedius challenged by spotting disease causative bacterium. The expression patterns of 10 DEGs were confirmed via RT-qPCR, and the expression levels were consistent with the results of RNA-seq. Furthermore, 9899 SSRs were identified, and 123,692, 151,827, and 114,368 candidate SNPs were identified from CG, DG, and UG, respectively. These results provide basic information for our understanding of sea urchin antibacterial immunity.

Suppression of the Peripheral Immune System Limits the Central Immune Response Following Cuprizone-Feeding: Relevance to Modelling Multiple Sclerosis

Cuprizone (CPZ) preferentially affects oligodendrocytes (OLG), resulting in demyelination. To investigate whether central oligodendrocytosis and gliosis triggered an adaptive immune response, the impact of combining a standard (0.2%) or low (0.1%) dose of ingested CPZ with disruption of the blood brain barrier (BBB), using pertussis toxin (PT), was assessed in mice. 0.2% CPZ(±PT) for 5 weeks produced oligodendrocytosis, demyelination and gliosis plus marked splenic atrophy (37%) and reduced levels of CD4 (44%) and CD8 (61%). Conversely, 0.1% CPZ(±PT) produced a similar oligodendrocytosis, demyelination and gliosis but a smaller reduction in splenic CD4 (11%) and CD8 (14%) levels and no splenic atrophy. Long-term feeding of 0.1% CPZ(±PT) for 12 weeks produced similar reductions in CD4 (27%) and CD8 (43%), as well as splenic atrophy (33%), as seen with 0.2% CPZ(±PT) for 5 weeks. Collectively, these results suggest that 0.1% CPZ for 5 weeks may be a more promising model to study the ‘inside-out’ theory of Multiple Sclerosis (MS). However, neither CD4 nor CD8 were detected in the brain in CPZ±PT groups, indicating that CPZ-mediated suppression of peripheral immune organs is a major impediment to studying the ‘inside-out’ role of the adaptive immune system in this model over long time periods. Notably, CPZ(±PT)-feeding induced changes in the brain proteome related to the suppression of immune function, cellular metabolism, synaptic function and cellular structure/organization, indicating that demyelinating conditions, such as MS, can be initiated in the absence of adaptive immune system involvement.

CaMKII Activity in the Inflammatory Response of Cardiac Diseases

Inflammation is a physiological process by which the body responds to external insults and stress conditions, and it is characterized by the production of pro-inflammatory mediators such as cytokines. The acute inflammatory response is solved by removing the threat. Conversely, a chronic inflammatory state is established due to a prolonged inflammatory response and may lead to tissue damage. Based on the evidence of a reciprocal regulation between inflammation process and calcium unbalance, here we described the involvement of a calcium sensor in cardiac diseases with inflammatory drift. Indeed, the Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) is activated in several diseases with an inflammatory component, such as myocardial infarction, ischemia/reperfusion injury, pressure overload/hypertrophy, and arrhythmic syndromes, in which it actively regulates pro-inflammatory signaling, among which includes nuclear factor kappa-B (NF-κB), thus contributing to pathological cardiac remodeling. Thus, CaMKII may represent a key target to modulate the severity of the inflammatory-driven degeneration.

The role of IL-17 in systemic lupus erythematosus and its potential as a therapeutic target

INTRODUCTION

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by autoantibodies production and immune complex deposition with systemic clinical manifestations. Interleukin (IL)-17-producing cells play a crucial role in disease pathogenesis and represent an attractive therapeutic target. Areas covered: This review provides an update on the possibility of targeting IL-17 in SLE. The rational for this approach as well as currently available and future targets are discussed. Expert opinion: Although human expression studies and animal models indicate that IL-17 blocking may be a promising therapeutic strategy for SLE, direct evidence for IL-17 inhibition in SLE patients is unavailable. Biologic therapies and small-molecule drugs that target IL-17 production are required for the achievement of a favorable clinical effect in SLE patients.

Molecular biomarkers in cardiac hypertrophy

Cardiac hypertrophy is characterized by an increase in myocyte size in the absence of cell division. This condition is thought to be an adaptive response to cardiac wall stress resulting from the enhanced cardiac afterload. The pathogenesis of heart dysfunction, which is one of the primary causes of morbidity and mortality in elderly people, is often associated with myocardial remodelling caused by cardiac hypertrophy. In order to well understand the potential mechanisms, we described the molecules involved in the development and progression of myocardial hypertrophy. Increasing evidence has indicated that micro‐RNAs are involved in the pathogenesis of cardiac hypertrophy. In addition, molecular biomarkers including vascular endothelial growth factor B, NAD‐dependent deacetylase sirtuin‐3, growth/differentiation factor 15 and glycoprotein 130, also play important roles in the development of myocardial hypertrophy. Knowing the regulatory mechanisms of these biomarkers in the heart may help identify new molecular targets for the treatment of cardiac hypertrophy.

BAFF inhibits autophagy promoting cell proliferation and survival by activating Ca2+-CaMKII-dependent Akt/mTOR signaling pathway in normal and neoplastic B-lymphoid cells

B cell activating factor from the TNF family (BAFF) is implicated in not only the physiology of normal B cells, but also the pathophysiology of aggressive B cells related to malignant and autoimmune diseases. Autophagy plays a crucial role in balancing the beneficial and detrimental effects of immunity and inflammation. However, little is known about whether and how excessive BAFF mediates autophagy contributing to B-cell proliferation and survival. Here, we show that excessive human soluble BAFF (hsBAFF) inhibited autophagy with a concomitant reduction of LC3-II in normal and B-lymphoid (Raji) cells. Knockdown of LC3 not only potentiated hsBAFF inhibition of autophagy, but also attenuated hsBAFF activation of Akt/mTOR pathway, thereby diminishing hsBAFF-induced B-cell proliferation/viability. Further, we found that hsBAFF inhibition of autophagy was Akt/mTOR-dependent. This is supported by the findings that hsBAFF increased mTORC1-mediated phosphorylation of ULK1 (Ser757); Akt inhibitor X, mTORC1 inhibitor rapamycin, mTORC1/2 inhibitor PP242, expression of dominant negative Akt, or knockdown of mTOR attenuated hsBAFF-induced phosphorylation of ULK1, decrease of LC3-II level, and increase of cell proliferation/viability. Chelating intracellular free Ca²⁺ ([Ca²⁺]_i) with BAPTA/AM or preventing [Ca²⁺]_i elevation using EGTA or 2-APB profoundly blocked hsBAFF-induced activation of Akt/mTOR, phosphorylation of ULK1 and decrease of LC3-II, as well as increase of cell proliferation/viability. Similar effects were observed in the cells where CaMKII was inhibited by KN93 or knocked down by CaMKII shRNA. Collectively, these results indicate that hsBAFF inhibits autophagy promoting cell proliferation and survival through activating Ca²⁺-CaMKII-dependent Akt/mTOR signaling pathway in normal and neoplastic B-lymphoid cells. Our findings suggest that manipulation of intracellular Ca²⁺ level or CaMKII, Akt, or mTOR activity to promote autophagy may be exploited for prevention of excessive BAFF-induced aggressive B lymphocyte disorders and autoimmune diseases.

The role of CaMK4 in immune responses

Calcium/calmodulin-dependent protein kinase IV (CaMK4) is a multifunctional serine/threonine kinase that regulates gene expression by activating transcription factors in a wide range of immune cells including T cells and antigen-presenting cells. The function of CaMK4 is suggested to be abnormal mainly in systemic lupus erythematosus (SLE), which is characterized by autoantibody production, immune complex formation, and immune dysregulation. Although accumulating evidence indicates that CaMK4 plays important roles in the immune responses, the precise molecular mechanisms underlying the development of autoimmune diseases and inflammatory disorders have not been established. In this review, we briefly summarize the role of CaMK4 in immune responses. We also discuss T-cell signaling pathways that control interleukin (IL)-17 production in patients with lupus nephritis and in glomerulonephritis in lupus-prone mice. A better understanding of the signaling and gene regulation of CaMK4 will lead to the identification of novel therapeutic targets in Th17 driven-autoimmune diseases.

Activation of CaMKIIγ potentiates T-cell acute lymphoblastic leukemia leukemogenesis via phosphorylating FOXO3a

Ca²⁺/calmodulin–dependent protein kinase II γ (CaMKIIγ) can regulate the proliferation and differentiation of myeloid leukemia cells and accelerate chronic myeloid leukemia blast crisis, but the role of CaMKIIγ in T-cell acute lymphoblastic leukemia (T-ALL) leukemogenesis remains poorly understood. We observed that activated (autophosphorylated) CaMKIIγ was invariably present in T-ALL cell lines and in the majority of primary T-ALL samples. Overexpression of CaMKIIγ enhanced the proliferation, colony formation, in vivo tumorigenesis and increased DNA damage of T-ALL leukemia cells. Furthermore, inhibition of CaMKIIγ activity with a pharmacologic inhibitor, gene knock-out, dominant-negative constructs or enhancement of CaMKIIγ activity by overexpression constructs revealed that the activated CaMKIIγ could phosphorylate FOXO3a. In Jurkat cells, the activated CaMKIIγ phosphorylated FOXO3a via directly or indirectly phosphorylating AKT, excluded FOXO3a from the nucleus and inhibited its transcriptional activity. These results indicate that the activated CaMKIIγ may play a key role in T-ALL leukemogenesis, and targeting CaMKIIγ might be a value approach in the treatment of T-ALL.

Stabilization of the c-Myc Protein by CAMKIIγ Promotes T Cell Lymphoma

Although high c-Myc protein expression is observed alongside MYC amplification in some cancers, in most cases protein overexpression occurs in the absence of gene amplification, e.g., T cell lymphoma (TCL). Here, Ca2+/calmodulin-dependent protein kinase II γ (CAMKIIγ) was shown to stabilize the c-Myc protein by directly phosphorylating it at serine 62 (S62). Furthermore, CAMKIIγ was shown to be essential for tumor maintenance. Inhibition of CAMKIIγ with a specific inhibitor destabilized c-Myc and reduced tumor burden. Importantly, high CAMKIIγ levels in patient TCL specimens correlate with increased c-Myc and pS62-c-Myc levels. Together, the CAMKIIγ:c-Myc axis critically influences the development and maintenance of TCL and represents a potential therapeutic target for TCL.

Comparison of distribution and toxicity of different types of zinc-based nanoparticles

Zinc-based nanoparticles (Zn-NPs), mainly zinc oxide (ZnO) NPs, have promising application in a wide area, but their potential harmful effects on environment and human health have been continuously raised together with their high dissolution rate. In this study, we coated the surface of ZnO NPs with phosphate (ZnP NPs) and sulfide (ZnS NPs) which have very low solubility in water, administered orally (0.5 and 1 mg/kg) to mice for 28 days, and then compared their biodistribution and toxicity. As expected, ZnO NPs were rapidly ionized in an artificial gastric fluid. On the other hand, ZnO NPs were more particlized in an artificial intestinal fluid than ZnP and ZnS NPs. After repeated dosing, all three types of Zn-NPs the most distributed in the spleen and thymus and altered the level of redox reaction-related metal ions in the tissues. We also found that three types of Zn-NPs clearly disturb tissue ion homeostasis and influence immune regulation function. However, there were no remarkable difference in distribution and toxicity following repeated exposure of three types of Zn-NPs, although Na+ and K+ level in the spleen and thymus were notably higher in mice exposed to ZnO NPs compared to ZnP and ZnS NPs. Taken together, we suggest that all three types of Zn-NPs may influence human health by disrupting homeostasis of trace elements and ions in the tissues. In addition, the surface transformation of ZnO NPs with phosphate and sulfide may not attenuate toxicity due to the higher particlization rate of ZnO NPs in the intestine, at least in part. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1363-1374, 2017.

T cell activation requires force generation

The T cell receptor requires force for triggering. Here, Hu and Butte show that T cells generate pushing and pulling forces against an antigen-coated AFM cantilever in an actin-dependent fashion. Exogenous, oscillating forces delivered by the cantilever rescued T cell receptor signaling in the absence of an intact F-actin cytoskeleton. These findings highlight the importance of mechanical forces in T cell activation.

Triggering of the T cell receptor (TCR) integrates both binding kinetics and mechanical forces. To understand the contribution of the T cell cytoskeleton to these forces, we triggered T cells using a novel application of atomic force microscopy (AFM). We presented antigenic stimulation using the AFM cantilever while simultaneously imaging with optical microscopy and measuring forces on the cantilever. T cells respond forcefully to antigen after calcium flux. All forces and calcium responses were abrogated upon treatment with an F-actin inhibitor. When we emulated the forces of the T cell using the AFM cantilever, even these actin-inhibited T cells became activated. Purely mechanical stimulation was not sufficient; the exogenous forces had to couple through the TCR. These studies suggest a mechanical–chemical feedback loop in which TCR-triggered T cells generate forceful contacts with antigen-presenting cells to improve access to antigen.

Role of TRP ion channels in cancer and tumorigenesis

Transient receptor potential (TRP) channels are recently identified proteins that form a versatile family of ion channels, the majority of which are calcium permeable and exhibit complex regulatory patterns with sensitivity to multiple environmental factors. While this sensitivity has captured early attention, leading to recognition of TRP channels as environmental and chemical sensors, many later studies concentrated on the regulation of intracellular calcium by TRP channels. Due to mutations, dysregulation of ion channel gating or expression levels, normal spatiotemporal patterns of local Ca(2+) distribution become distorted. This causes deregulation of downstream effectors sensitive to changes in Ca(2+) homeostasis that, in turn, promotes pathophysiological cancer hallmarks, such as enhanced survival, proliferation and invasion. These observations give rise to the appreciation of the important contributions that TRP channels make to many cellular processes controlling cell fate and positioning these channels as important players in cancer regulation. This review discusses the accumulated scientific knowledge focused on TRP channel involvement in regulation of cell fate in various transformed tissues.

Transcriptomic-Wide Discovery of Direct and Indirect HuR RNA Targets in Activated CD4+ T Cells

Due to poor correlation between steady state mRNA levels and protein product, purely transcriptomic profiling methods may miss genes posttranscriptionally regulated by RNA binding proteins (RBPs) and microRNAs (miRNAs). RNA immunoprecipitation (RIP) methods developed to identify in vivo targets of RBPs have greatly elucidated those mRNAs which may be regulated via transcript stability and translation. The RBP HuR (ELAVL1) and family members are major stabilizers of mRNA. Many labs have identified HuR mRNA targets; however, many of these analyses have been performed in cell lines and oftentimes are not independent biological replicates. Little is known about how HuR target mRNAs behave in conditional knock-out models. In the present work, we performed HuR RIP-Seq and RNA-Seq to investigate HuR direct and indirect targets using a novel conditional knock-out model of HuR genetic ablation during CD4+ T activation and Th2 differentiation. Using independent biological replicates, we generated a high coverage RIP-Seq data set (>160 million reads) that was analyzed using bioinformatics methods specifically designed to find direct mRNA targets in RIP-Seq data. Simultaneously, another set of independent biological replicates were sequenced by RNA-Seq (>425 million reads) to identify indirect HuR targets. These direct and indirect targets were combined to determine canonical pathways in CD4+ T cell activation and differentiation for which HuR plays an important role. We show that HuR may regulate genes in multiple canonical pathways involved in T cell activation especially the CD28 family signaling pathway. These data provide insights into potential HuR-regulated genes during T cell activation and immune mechanisms.

Rapamycin inhibits BAFF-stimulated cell proliferation and survival by suppressing mTOR-mediated PP2A-Erk1/2 signaling pathway in normal and neoplastic B-lymphoid cells

B-cell activating factor (BAFF) is involved in not only physiology of normal B cells, but also pathophysiology of aggressive B cells related to malignant and autoimmune diseases. Rapamycin, a lipophilic macrolide antibiotic, has recently shown to be effective in the treatment of human lupus erythematosus. However, how rapamycin inhibits BAFF-stimulated B-cell proliferation and survival has not been fully elucidated. Here, we show that rapamycin inhibited human soluble BAFF (hsBAFF)-induced cell proliferation and survival in normal and B-lymphoid (Raji and Daudi) cells by activation of PP2A and inactivation of Erk1/2. Pretreatment with PD98059, down-regulation of Erk1/2, expression of dominant negative MKK1, or overexpression of wild-type PP2A potentiated rapamycin's suppression of hsBAFF-activated Erk1/2 and B-cell proliferation/viability, whereas expression of constitutively active MKK1, inhibition of PP2A by okadaic acid, or expression of dominant negative PP2A attenuated the inhibitory effects of rapamycin. Furthermore, expression of a rapamycin-resistant and kinase-active mTOR (mTOR-T), but not a rapamycin-resistant and kinase-dead mTOR-T (mTOR-TE), conferred resistance to rapamycin's effects on PP2A, Erk1/2 and B-cell proliferation/viability, implying mTOR-dependent mechanism involved. The findings indicate that rapamycin inhibits BAFF-stimulated cell proliferation/survival by targeting mTOR-mediated PP2A-Erk1/2 signaling pathway in normal and neoplastic B-lymphoid cells. Our data highlight that rapamycin may be exploited for preventing excessive BAFF-induced aggressive B-cell malignancies and autoimmune diseases.

BAFF activates Erk1/2 promoting cell proliferation and survival by Ca2+-CaMKII-dependent inhibition of PP2A in normal and neoplastic B-lymphoid cells

B-cell activating factor (BAFF) is involved in not only the physiology of normal B cells, but also the pathophysiology of aggressive B cells related to malignant and autoimmune diseases. However, how excessive BAFF promotes aggressive B-cell proliferation and survival is not well understood. Here we show that excessive human soluble BAFF (hsBAFF) enhanced cell proliferation and survival in normal and B-lymphoid (Raji) cells, which was associated with suppression of PP2A, resulting in activation of Erk1/2. This is supported by the findings that pretreatment with U0126 or PD98059, expression of dominant negative MKK1, or overexpression of PP2A prevented hsBAFF-induced activation of Erk1/2 and cell proliferation/viability in the cells. It appears that hsBAFF-mediated PP2A-Erk1/2 pathway and B-cell proliferation/viability was Ca(2+)-dependent, as pretreatment with BAPTA/AM, EGTA or 2-APB significantly attenuated these events. Furthermore, we found that inhibiting CaMKII with KN93 or silencing CaMKII also attenuated hsBAFF-mediated PP2A-Erk1/2 signaling and B-cell proliferation/viability. The results indicate that BAFF activates Erk1/2, in part through Ca(2+)-CaMKII-dependent inhibition of PP2A, increasing cell proliferation/viability in normal and neoplastic B-lymphoid cells. Our data suggest that inhibitors of CaMKII and Erk1/2, activator of PP2A or manipulation of intracellular Ca(2+) may be exploited for prevention of excessive BAFF-induced aggressive B-cell malignancies and autoimmune diseases.

hsBAFF promotes proliferation and survival in cultured B lymphocytes via calcium signaling activation of mTOR pathway

B-cell activating factor of the TNF family (BAFF, also called BLyS, TALL-1, THANK, or zTNF4) has revealed its critical function in B lymphocyte proliferation and survival, as well as the pathogenesis of autoimmune disease. However, the molecular mechanisms of excess BAFF-extended aggressive B lymphocytes have not been completely defined. Here we show that excessive hsBAFF-elevated [Ca(2+)]i activated mammalian target of rapamycin (mTOR) signaling pathway, leading to proliferation and survival in B lymphocytes. This is supported by the findings that intracellular Ca(2+) chelator (BAPTA/AM) or mTOR inhibitor (rapamycin) abolished the events. Sequentially, we observed that preventing [Ca(2+)]i elevation using EGTA or 2-APB dramatically inhibited hsBAFF activation of mTOR signaling, as well as cell growth and survival, suggesting that hsBAFF-induced extracellular Ca(2+) influx and ER Ca(2+) release elevates [Ca(2+)]i contributing to B lymphocyte proliferation and survival via activation of mTOR signaling. Further, we noticed that pretreatment with BAPTA/AM, EGTA or 2-APB blocked hsBAFF-increased phosphorylation of calcium/calmodulin-dependent protein kinase II (CaMKII), and inhibiting CaMKII with KN93 attenuated hsBAFF-activated mTOR signaling, as well as cell growth and survival, revealing that the effects of hsBAFF-elevated [Ca(2+)]i on mTOR signaling as well as proliferation and survival in B lymphocytes is through stimulating phosphorylation of CaMKII. The results indicate that hsBAFF activates mTOR pathway triggering B lymphocyte proliferation and survival by calcium signaling. Our findings suggest that manipulation of intracellular Ca(2+) level or CaMKII and mTOR activity may be exploited for the prevention of excessive BAFF-induced aggressive B lymphocyte disorders and autoimmune diseases.

Synthesis and structure based optimization of 2-(4-phenoxybenzoyl)-5-hydroxyindole as a novel CaMKII inhibitor

Based on 2-(4-phenoxybenzoyl)-5-hydroxyindole (2), a novel structural class of CaMKII inhibitors were synthesized and further optimized. The strong acidity of the hydroxyl group and the lipophilic group at the 4 and 6-positions were found to be necessary for strong CaMKII inhibition. Compound 25 was identified as a promising compound with 50-fold more potent inhibitory activity for CaMKII than 2. Compound 25 also showed high selectivity for CaMKII over off-target kinases.

Analysis of candidate genes of spontaneous arthritis in mice deficient for interleukin-1 receptor antagonist

Previously, we identified a major quantitative trait locus (QTL) on mouse chromosome 1 that regulates the susceptibility to arthritis in an F2 population generated from arthritis-prone BALB/c and arthritis-resistant DBA/1 mice deficient for interleukin-1 receptor antagonist. To further select candidate genes for the QTL, we analyzed the expression patterns of arthritis in 38 F2 individuals and compared the expression levels of key candidate genes to the parental strains. Two distinct subpopulations of arthritic mice were identified in the 38 F2 mice. One subgroup of diseased mice was characterized by myeloid cell dominant inflammation, whereas the other was mainly associated with increased anti-apoptotic activities of inflammatory cells. Several differentially expressed important candidate genes in parental strains in the QTL region are relevant to myeloid cell, apoptotic activities, or to both. About one-quarter of those genes have been previously linked to arthritis in literature. The present study reveals two distinct subpopulations of arthritic mice with spontaneous arthritis due to deficiency for interleukin-1 receptor antagonist, suggesting that genes with function relevant to myeloid cell and/or apoptotic activities are most likely the key candidate genes for the QTL.

Calcium/calmodulin-dependent protein kinase II regulates IL-10 production by human T lymphocytes: a distinct target in the calcium dependent pathway

Calcium (Ca2+) plays an essential role in lymphocyte activation and differentiation by affecting signaling pathways leading to cytokine production. Among the enzymes responding to calcium increase, Ca2+/calmodulin-dependent protein kinase II (CaMKII) has been involved in anergy with a still poorly characterized role. IL-10 produced by different T lymphocyte subpopulations is critical mediator of tolerance. We tested the hypothesis that CaMKII may be involved in IL-10 production. We report that CaMKII upregulates IL-10 production by primary human T lymphocytes stimulated through the antigen receptor or bypassing that. Overexpression of constitutively active mutant forms of Calcineurin or CaMKII specifically increase IL-10 protein product and IL-10 mRNA accumulation in T lymphocytes. By cotransfecting constitutively active CaMKII with luciferase reporter plasmids carrying specific fragments or the whole IL-10 promoter, we show that CaMKII specifically activates IL-10 promoter activity, whereas it inhibits IL-2 and IL-4 promoter. This effect is mediated by the first 500 bp fragment, which contains binding sites for Myocyte Enhancer Factor-2 (MEF2). A constitutively active mutant of CaMKII activated a luciferase reporter plasmid under the control of MEF2, when cotransfected in T lymphocytes stimulated by Ionomycin and PMA, whereas its inhibitor KN-62 inhibited MEF2 binding in cell lysates of the same cells. Moreover, overexpression of MEF2 enhanced by 2.5-fold IL-10 promoter activity. Our data for the first time suggest a distinct role of CaMKII in the induction of anergy in T lymphocytes, by differential regulation of IL-10 and IL-2 gene transcription suggest MEF2 as a molecular target which can integrate different calcium signals.

Preference of IRES-mediated initiation of translation during hibernation in golden-mantled ground squirrels, Spermophilus lateralis

Mammalian hibernation involves virtual cessation of energetically consumptive processes normally vital to homeostasis, including gene transcription and protein synthesis. As animals enter torpor, the bulk of initiation of translation is blocked at a body temperature of 18°C in golden-mantled ground squirrels [Spermophilus (Callospermophilus) lateralis]. Previous data demonstrated regulation of cap-dependent initiation of translation during torpor. We asked what happens to cap-independent, specifically, internal ribosome entry site (IRES)-mediated initiation of translation during hibernation. We analyzed polysome fractions for mRNAs that are known to contain or not to contain IRES elements. Here, we show that mRNAs harboring IRES elements preferentially associate with ribosomes as a torpor bout progresses. Squirrels allowed to naturally complete a torpor cycle have a higher IRES preference index than those animals that are prematurely aroused from torpor. Data indicate that this change in preference is not associated with gene expression, i.e., change is due to change in mRNA association with ribosomes as opposed to mRNA abundance. Thus, although processes like transcription and translation are virtually arrested during torpor, ribosomes are preferentially loaded with IRES-containing transcripts when squirrels arouse from torpor and translation resumes. Differential translation of preexisting mRNAs may allow for the preferential production of key stress proteins critical for survival of physiological insults that are lethal to other mammals.

Structure and activity relationship of 2-(substituted benzoyl)-hydroxyindoles as novel CaMKII inhibitors

A series of novel 2-substituted-5-hydroxyindoles were synthesized and evaluated for their inhibitory activity against CaMKII. Structure and activity relationship results indicated that potent inhibitory activity could be achieved by modification at the para-position of the phenyl ring of the high throughput screening hit compound 2. Among the prepared compounds, we identified 14 as a novel CaMKII inhibitor with an activity stronger than that of KN-93, a known CaMKII inhibitor.

5,6,7,8-Tetrahydropyrido[4,3-d]pyrimidines as novel class of potent and highly selective CaMKII inhibitors

A novel series of 5,6,7,8-tetrahydropyrido[4,3-d]pyrimidines containing substituted phenyl sulfonamide are synthesized and evaluated for their inhibitory activity against CaMKII. Substituents on the phenyl group had significant impact on CaMKII inhibition, in particular, the inhibitory activity of 8p was 25-fold higher than that of KN-93, a known CaMKII inhibitor. Michaelis-Menten analysis of a representative compound suggested that the synthesized pyrimidines are calmodulin non-competitive inhibitors. Finally, 8p exhibited more than 100-fold higher selectivity for CaMKII over five types of off-target kinases.