Deregulation of interferon-gamma receptor 1 expression and its implications for lung adenocarcinoma progression

Interferon-gamma (IFN-γ) plays a dual role in cancer; it is both a pro- and an antitumorigenic cytokine, depending on the type of cancer. The deregulation of the IFN-γ canonic pathway is associated with several disorders, including vulnerability to viral infections, inflammation, and cancer progression. In particular, the interplay between lung adenocarcinoma (LUAD) and viral infections appears to exist in association with the deregulation of IFN-γ signaling. In this mini-review, we investigated the status of the IFN-γ signaling pathway and the expression level of its components in LUAD. Interestingly, a reduction in IFNGR1 expression seems to be associated with LUAD progression, affecting defenses against viruses such as severe acute respiratory syndrome coronavirus 2. In addition, alterations in the expression of IFNGR1 may inhibit the antiproliferative action of IFN-γ signaling in LUAD.

Reprogramming of cardiac phosphoproteome, proteome, and transcriptome confers resilience to chronic adenylyl cyclase-driven stress

Our prior study (Tarasov et al., 2022) discovered that numerous adaptive mechanisms emerge in response to cardiac-specific overexpression of adenylyl cyclase type 8 (TGAC8) which included overexpression of a large number of proteins. Here, we conducted an unbiased phosphoproteomics analysis in order to determine the role of altered protein phosphorylation in the adaptive heart performance and protection profile of adult TGAC8 left ventricle (LV) at 3-4 months of age, and integrated the phosphoproteome with transcriptome and proteome. Based on differentially regulated phosphoproteins by genotype, numerous stress-response pathways within reprogrammed TGAC8 LV, including PKA, PI3K, and AMPK signaling pathways, predicted upstream regulators (e.g. PDPK1, PAK1, and PTK2B), and downstream functions (e.g. cell viability, protein quality control), and metabolism were enriched. In addition to PKA, numerous other kinases and phosphatases were hyper-phosphorylated in TGAC8 vs. WT. Hyper-phosphorylated transcriptional factors in TGAC8 were associated with increased mRNA transcription, immune responses, and metabolic pathways. Combination of the phosphoproteome with its proteome and with the previously published TGAC8 transcriptome enabled the elucidation of cardiac performance and adaptive protection profiles coordinately regulated at post-translational modification (PTM) (phosphorylation), translational, and transcriptional levels. Many stress-response signaling pathways, i.e., PI3K/AKT, ERK/MAPK, and ubiquitin labeling, were consistently enriched and activated in the TGAC8 LV at transcriptional, translational, and PTM levels. Thus, reprogramming of the cardiac phosphoproteome, proteome, and transcriptome confers resilience to chronic adenylyl cyclase-driven stress. We identified numerous pathways/function predictions via gene sets, phosphopeptides, and phosphoproteins, which may point to potential novel therapeutic targets to enhance heart adaptivity, maintaining heart performance while avoiding cardiac dysfunction.

Setting sail: Maneuvering SHP2 activity and its effects in cancer

Since the discovery of tyrosine phosphorylation being a critical modulator of cancer signaling, proteins regulating phosphotyrosine levels in cells have fast become targets of therapeutic intervention. The nonreceptor protein tyrosine phosphatase (PTP) coded by the PTPN11 gene "SHP2" integrates phosphotyrosine signaling from growth factor receptors into the RAS/RAF/ERK pathway and is centrally positioned in processes regulating cell development and oncogenic transformation. Dysregulation of SHP2 expression or activity is linked to tumorigenesis and developmental defects. Even as a compelling anti-cancer target, SHP2 was considered "undruggable" for a long time owing to its conserved catalytic PTP domain that evaded drug development. Recently, SHP2 has risen from the "undruggable curse" with the discovery of small molecules that manipulate its intrinsic allostery for effective inhibition. SHP2's unique domain arrangement and conformation(s) allow for a truly novel paradigm of inhibitor development relying on skillful targeting of noncatalytic sites on proteins. In this review we summarize the biological functions, signaling properties, structural attributes, allostery and inhibitors of SHP2.

A comprehensive review of SHP2 and its role in cancer

Src homology 2-containing protein tyrosine phosphatase 2 (SHP2) is a non-receptor protein tyrosine phosphatase ubiquitously expressed mainly in the cytoplasm of several tissues. SHP2 modulates diverse cell signaling events that control metabolism, cell growth, differentiation, cell migration, transcription and oncogenic transformation. It interacts with diverse molecules in the cell, and regulates key signaling events including RAS/ERK, PI3K/AKT, JAK/STAT and PD-1 pathways downstream of several receptor tyrosine kinases (RTKs) upon stimulation by growth factors and cytokines. SHP2 acts as both a phosphatase and a scaffold, and plays prominently oncogenic functions but can be tumor suppressor in a context-dependent manner. It typically acts as a positive regulator of RTKs signaling with some inhibitory functions reported as well. SHP2 expression and activity is regulated by such factors as allosteric autoinhibition, microRNAs, ubiquitination and SUMOylation. Dysregulation of SHP2 expression or activity causes many developmental diseases, and hematological and solid tumors. Moreover, upregulated SHP2 expression or activity also decreases sensitivity of cancer cells to anticancer drugs. SHP2 is now considered as a compelling anticancer drug target and several classes of SHP2 inhibitors with different mode of action are developed with some already in clinical trial phases. Moreover, novel SHP2 substrates and functions are rapidly growing both in cell and cancer. In view of this, we comprehensively and thoroughly reviewed literatures about SHP2 regulatory mechanisms, substrates and binding partners, biological functions, roles in human cancers, and different classes of small molecule inhibitors target this oncoprotein in cancer.

A scalable, open-source implementation of a large-scale mechanistic model for single cell proliferation and death signaling

Mechanistic models of how single cells respond to different perturbations can help integrate disparate big data sets or predict response to varied drug combinations. However, the construction and simulation of such models have proved challenging. Here, we developed a python-based model creation and simulation pipeline that converts a few structured text files into an SBML standard and is high-performance- and cloud-computing ready. We applied this pipeline to our large-scale, mechanistic pan-cancer signaling model (named SPARCED) and demonstrate it by adding an IFNγ pathway submodel. We then investigated whether a putative crosstalk mechanism could be consistent with experimental observations from the LINCS MCF10A Data Cube that IFNγ acts as an anti-proliferative factor. The analyses suggested this observation can be explained by IFNγ-induced SOCS1 sequestering activated EGF receptors. This work forms a foundational recipe for increased mechanistic model-based data integration on a single-cell level, an important building block for clinically-predictive mechanistic models.

Epithelial-to-mesenchymal transition hinders interferon-γ-dependent immunosurveillance in lung cancer cells

The epithelial-to-mesenchymal transition (EMT) is involved in cancer metastasis; nevertheless, interferon (IFN)-γ induces anticancer activities by causing cell growth suppression, cytotoxicity, and migration inhibition. Regarding the poor response to exogenously administered IFN-γ as anticancer therapy, it was hypothesized that malignant cells may acquire a means of escaping from IFN-γ immunosurveillance, likely through an EMT-related process. A genomic analysis of human lung cancers revealed a negative link between the EMT and IFN-γ signaling, while compared to human lung adenocarcinoma A549 cells, IFN-γ-hyporesponsive AS2 cells exhibited mesenchymal characteristics. Chemically, physically, and genetically engineered EMT attenuated IFN-γ-induced IFN regulatory factor 1 transactivation. Poststimulation of transforming growth factor-β induced the EMT and also selectively retarded IFN-γ-responsive gene expression as well as IFN-γ-induced signal transducer and activator of transcription 1 activation, major histocompatibility complex I, and CD54 expression, cell migration/invasion inhibition, and direct/indirect cytotoxicity. Without changes in IFN-γ receptors, excessive oxidative activation of Src homology-2 containing phosphatase 2 (SHP2) in cells undergoing the EMT primarily caused cellular hyporesponsiveness to IFN-γ signaling and cytotoxicity, while combining an SHP2 inhibitor or antioxidant sensitized EMT-associated AS2 and mesenchymal A549 cells to IFN-γ-induced priming effects on tumor necrosis factor-related apoptosis-inducing ligand cytotoxicity. In cell line-derived xenograft models, combined treatment with IFN-γ and an SHP2 inhibitor induced enhanced anticancer activities. These results imply that EMT-associated SHP2 activation inhibits IFN-γ signaling, facilitating lung cancer cell escape from IFN-γ immunosurveillance.

Role of Glycogen Synthase Kinase-3 in Interferon-γ-Mediated Immune Hepatitis

Glycogen synthase kinase-3 (GSK-3), a serine/threonine kinase, is a vital glycogen synthase regulator controlling glycogen synthesis, glucose metabolism, and insulin signaling. GSK-3 is widely expressed in different types of cells, and its abundant roles in cellular bioregulation have been speculated. Abnormal GSK-3 activation and inactivation may affect its original bioactivity. Moreover, active and inactive GSK-3 can regulate several cytosolic factors and modulate their diverse cellular functional roles. Studies in experimental liver disease models have illustrated the possible pathological role of GSK-3 in facilitating acute hepatic injury. Pharmacologically targeting GSK-3 is therefore suggested as a therapeutic strategy for liver protection. Furthermore, while the signaling transduction of GSK-3 facilitates proinflammatory interferon (IFN)-γ in vitro and in vivo, the blockade of GSK-3 can be protective, as shown by an IFN-γ-induced immune hepatitis model. In this study, we explored the possible regulation of GSK-3 and the potential relevance of GSK-3 blockade in IFN-γ-mediated immune hepatitis.

Lithium inhibits tryptophan catabolism via the inflammation-induced kynurenine pathway in human microglia

Despite its decades' long therapeutic use in psychiatry, the biological mechanisms underlying lithium's mood-stabilizing effects have remained largely elusive. Here, we investigated the effect of lithium on tryptophan breakdown via the kynurenine pathway using immortalized human microglia cells, primary human microglia isolated from surgical specimens, and microglia-like cells differentiated from human induced pluripotent stem cells. Interferon (IFN)-γ, but not lipopolysaccharide, was able to activate immortalized human microglia, inducing a robust increase in indoleamine-2,3-dioxygenase (IDO1) mRNA transcription, IDO1 protein expression, and activity. Further, chromatin immunoprecipitation verified enriched binding of both STAT1 and STAT3 to the IDO1 promoter. Lithium counteracted these effects, increasing inhibitory GSK3β^S9 phosphorylation and reducing STAT1^S727 and STAT3^Y705 phosphorylation levels in IFN-γ treated cells. Studies in primary human microglia and hiPSC-derived microglia confirmed the anti-inflammatory effects of lithium, highlighting that IDO activity is reduced by GSK3 inhibitor SB-216763 and STAT inhibitor nifuroxazide via downregulation of P-STAT1^S727 and P-STAT3^Y705 . Primary human microglia differed from immortalized human microglia and hiPSC derived microglia-like cells in their strong sensitivity to LPS, resulting in robust upregulation of IDO1 and anti-inflammatory cytokine IL-10. While lithium again decreased IDO1 activity in primary cells, it further increased release of IL-10 in response to LPS. Taken together, our study demonstrates that lithium inhibits the inflammatory kynurenine pathway in the microglia compartment of the human brain.

Glycogen Synthase Kinase-3: A Focal Point for Advancing Pathogenic Inflammation in Depression

Increasing evidence indicates that the host immune response has a monumental role in the etiology of major depressive disorder (MDD), motivating the development of the inflammatory hypothesis of depression. Central to the involvement of chronic inflammation in MDD is a wide range of signaling deficits induced by the excessive secretion of pro-inflammatory cytokines and imbalanced T cell differentiation. Such signaling deficits include the glutamatergic, cholinergic, insulin, and neurotrophin systems, which work in concert to initiate and advance the neuropathology. Fundamental to the communication between such systems is the protein kinase glycogen synthase kinase-3 (GSK-3), a multifaceted protein critically linked to the etiology of MDD and an emerging target to treat pathogenic inflammation. Here, a consolidated overview of the widespread multi-system involvement of GSK-3 in contributing to the neuropathology of MDD will be discussed, with the feed-forward mechanistic links between all major neuronal signaling pathways highlighted.

Evidence that knock down of GSK-3β in Chronic Myelogenous Leukemia cells augments IFN-γ-induced apoptosis

The role of interferon-gamma (IFN-γ) in Chronic Myelogenous/Myeloid Leukemia (CML) and in the treatment of CML remains unclear; specifically, the effect of IFN-γ on apoptosis. There is reported interplay between IFN-γ and glycogen synthase kinase-3 (GSK-3), a kinase which has been implicated in both cell death and, conversely, cell survival. Thus, we utilized the CML-derived HAP1 cell line and a mutant HAP1 GSK-3β knocked-down cell line (GSK-3β 31bp) to investigate whether GSK-3 modulates IFN-γ's action on CML cells. Significantly less GSK-3β 31bp cells, relative to HAP1 cells, were present after 48 h treatment with IFN-γ. IFN-γ treatment significantly decreased GSK-3β 31bp substrate adhesiveness (relative to HAP1 cells); an observation often correlated with cell death. Fluorescence microscopy revealed that IFN-γ induces a modest level of apoptosis in the HAP1 cells and that IFN-γ induced apoptosis is significantly enhanced in GSK-3β 31bp cells. Utilizing a complementary GSK-3β knocked-down cell line (8bp) we found, via flow cytometric analysis, that IFN-γ induced apoptosis is significantly enhanced in GSK-3β 8bp cells relative to HAP1 cells. Combined, our findings suggest that IFN-γ induces apoptosis of CML cells and that loss of GSK-3β significantly augments IFN-γ-induced apoptosis.

The role of glycogen synthase kinase 3 beta in multiple sclerosis

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system (CNS) that leads to progressive neurological disability due to axonal deterioration. Although MS presents profound heterogeneity in the clinical course, its underlying central mechanism is active demyelination and neurodegeneration associated with inflammation. Multiple autoimmune and neuroinflammatory pathways are involved in the demyelination process of MS. Analysis of MS lesions has shown that inflammatory genes are upregulated. Glycogen synthase kinase-3 (GSK-3) is part of the mitogen-activated protein kinase (MAPK) family and has important roles in many signaling cascades. GSK-3 is a highly conserved serine/threonine protein kinase expressed in both the central and the peripheral nervous systems. GSK-3 modulates several biological processes through phosphorylation of protein kinases, including cell signaling, neuronal growth, apoptosis and production of pro-inflammatory cytokines and interleukins, allowing adaptive changes in events such as cellular proliferation, migration, inflammation, and immunity. GSK-3 occurs in mammals in two isoforms GSK-3α and GSK-3β, both of which are common in the brain, although GSK-3α is found particularly in the cerebral cortex, cerebellum, striated hippocampus and Purkinje cells, while GSK-3β is found in all brain regions. In patients with chronic progressive MS, expression of GSK-3β is elevated in several brain regions such as the corpus callosum and cerebral cortex. GSK-3β inhibition may play a role in glial cell activation, reducing pathological pain induced by nerve injury by formalin injection. According to the role of GSK-3β in pathological conditions, the aim of this article is review of the role of GSK-3β in multiple sclerosis and inflammation of neurons.

An Oncogenic Alteration Creates a Microenvironment that Promotes Tumor Progression by Conferring a Metabolic Advantage to Regulatory T Cells

Only a small percentage of patients afflicted with gastric cancer (GC) respond to immune checkpoint blockade (ICB). To study the mechanisms underlying this resistance, we examined the immune landscape of GC. A subset of these tumors was characterized by high frequencies of regulatory T (Treg) cells and low numbers of effector T cells. Genomic analyses revealed that these tumors bore mutations in RHOA that are known to drive tumor progression. RHOA mutations in cancer cells activated the PI3K-AKT-mTOR signaling pathway, increasing production of free fatty acids that are more effectively consumed by Treg cells than effector T cells. RHOA mutant tumors were resistant to PD-1 blockade but responded to combination of PD-1 blockade with inhibitors of the PI3K pathway or therapies targeting Treg cells. We propose that the metabolic advantage conferred by RHOA mutations enables Treg cell accumulation within GC tumors, generating an immunosuppressive TME that underlies resistance to ICB.

Cell signaling and the aging of B cells

The uniqueness of each B cell lies in the structural diversity of the B-cell antigen receptor allowing the virtually limitless recognition of antigens, a necessity to protect individuals against a range of challenges. B-cell development and response to stimulation are exquisitely regulated by a group of cell surface receptors modulating various signaling cascades and their associated genetic programs. The effects of these signaling pathways in optimal antibody-mediated immunity or the aberrant promotion of immune pathologies have been intensely researched in the past in young individuals. In contrast, we are only beginning to understand the contribution of these pathways to the changes in B cells of old organisms. Thus, critical transcription factors such as E2A and STAT5 show differential expression or activity between young and old B cells. As a result, B-cell physiology appears altered, and antibody production is impaired. Here, we discuss selected phenotypic changes during B-cell aging and attempt to relate them to alterations of molecular mechanisms.

Allosteric Inhibition of SHP2 Stimulates Antitumor Immunity by Transforming the Immunosuppressive Environment

The protein tyrosine phosphatase SHP2 binds to phosphorylated signaling motifs on regulatory immunoreceptors including PD-1, but its functional role in tumor immunity is unclear. Using preclinical models, we show that RMC-4550, an allosteric inhibitor of SHP2, induces antitumor immunity, with effects equivalent to or greater than those resulting from checkpoint blockade. In the tumor microenvironment, inhibition of SHP2 modulated T-cell infiltrates similar to checkpoint blockade. In addition, RMC-4550 drove direct, selective depletion of protumorigenic M2 macrophages via attenuation of CSF1 receptor signaling and increased M1 macrophages via a mechanism independent of CD8⁺ T cells or IFNγ. These dramatic shifts in polarized macrophage populations in favor of antitumor immunity were not seen with checkpoint blockade. Consistent with a pleiotropic mechanism of action, RMC-4550 in combination with either checkpoint or CSF1R blockade caused additive antitumor activity with complete tumor regressions in some mice; tumors intrinsically sensitive to SHP2 inhibition or checkpoint blockade were particularly susceptible. Our preclinical findings demonstrate that SHP2 thus plays a multifaceted role in inducing immune suppression in the tumor microenvironment, through both targeted inhibition of RAS pathway-dependent tumor growth and liberation of antitumor immune responses. Furthermore, these data suggest that inhibition of SHP2 is a promising investigational therapeutic approach. SIGNIFICANCE: Inhibition of SHP2 causes direct and selective depletion of protumorigenic M2 macrophages and promotes antitumor immunity, highlighting an investigational therapeutic approach for some RAS pathway-driven cancers.

GSK3: A Kinase Balancing Promotion and Resolution of Inflammation

GSK3 has been implicated for years in the regulation of inflammation and addressed in a plethora of scientific reports using a variety of experimental (disease) models and approaches. However, the specific role of GSK3 in the inflammatory process is still not fully understood and controversially discussed. Following a detailed overview of structure, function, and various regulatory levels, this review focusses on the immunoregulatory functions of GSK3, including the current knowledge obtained from animal models. Its impact on pro-inflammatory cytokine/chemokine profiles, bacterial/viral infections, and the modulation of associated pro-inflammatory transcriptional and signaling pathways is discussed. Moreover, GSK3 contributes to the resolution of inflammation on multiple levels, e.g., via the regulation of pro-resolving mediators, the clearance of apoptotic immune cells, and tissue repair processes. The influence of GSK3 on the development of different forms of stimulation tolerance is also addressed. Collectively, the role of GSK3 as a kinase balancing the initiation/perpetuation and the amelioration/resolution of inflammation is highlighted.

The Emerging Roles of NDR1/2 in Infection and Inflammation

The nuclear Dbf2-related (NDR) kinases NDR1 and NDR2 belong to the NDR/LATS (large tumor suppressor) subfamily in the Hippo signaling pathway. They are highly conserved from yeast to humans. It is well-known that NDR1/2 control important cellular processes, such as morphological changes, centrosome duplication, cell proliferation, and apoptosis. Recent studies revealed that NDR1/2 also play important roles in the regulation of infection and inflammation. In this review, we summarized the roles of NDR1/2 in the modulation of inflammation induced by cytokines and innate immune response against the infection of bacteria and viruses, emphasizing on how NDR1/2 regulate signaling transduction through Hippo pathway-dependent and -independent manners.

Schistosoma egg antigens suppress LPS-induced inflammation in human IMR-90 cells by modulation of JAK/STAT1 signaling

BACKGROUND

The regulation of the balance between inflammatory and anti-inflammatory events during the treatment of pulmonary infection is very important. Soluble Schistosoma egg antigens (SEA) can effectively inhibit the expression of cytokines during hepatic acute inflammation. However, the mechanisms by which these proteins suppress the inflammatory responses in lung cells remain unclear. The purpose of this study was to investigate the ability of SEA to inhibit pulmonary inflammation.

METHODS

The effects of SEA were investigated in LPS-treated lung IMR-90 cells. The involvement of the JAK/STAT-1 signaling pathway in these effects was evaluated by employing CBA assays, quantitative polymerase chain reaction, and western blotting experiments.

RESULTS

Pretreatment of IMR-90 cells with appropriate concentrations of SEA protected cells against the cytotoxic effects of LPS-induced inflammation in a time-dependent manner. SEA pretreatment significantly attenuated the LPS-induced activation of the JAK/STAT1 signaling pathway, including the upregulation of JAK1/2 and STAT1, as well as the production of inflammatory cytokines. The level of phosphorylated STAT1 gradually declined in response to increasing concentrations of SEA. Based on these findings, we hypothesize that SEA-induced anti-inflammatory effects initiate with the downregulation of the IFN-γ-JAK-STAT1 signaling pathway, resulting in the attenuation of LPS-induced inflammation in IMR-90 cells.

CONCLUSION

Our study is the first to demonstrate the anti-inflammatory activity of SEA in an in vitro model of pulmonary inflammation, involving the modulation of JAK/STAT1 signaling. We propose SEA as potential therapeutic or preventive agents for the selective suppression of STAT1 and the control of inflammatory response in lung IMR-90 cells.

Grass carp STK38 regulates IFN I expression by decreasing the phosphorylation level of GSK3β

As a member of NDR protein kinase family and a novel protein kinase of Hippo signal pathway, Serine/threonine kinase 38 (STK38) plays a very significant role in the innate immune. In mammals, STK38 performs its function by combining with GSK3β. Nowadays, there are few reports of STK38 in fish. In order to explain the function of fish STK38 in the innate immunity, we cloned the ORF of grass carp (Ctenopharyngodon idella) STK38 (CiSTK38) and the related kinase GSK3β (CiGSK3β). Phylogenetic trees revealed that CiSTK38 and CiGSK3β evolved closer kinship with sinocyclocheilus grahami STK38 and siniperca chuatsi GSK3β respectively. CiSTK38 and CiGSK3β can respond to the intradermal injection of poly (I:C) in grass carp different tissues and the transfection of poly I:C in CIK cells. Subcellular localization revealed the CiGSK3β were broadly distributed through the cytoplasm, whereas CiSTK38 were observed both in cytoplasm and nucleus. However, when they were co-transferred into cells, the two proteins were found to aggregate in the nucleus. GST-pulldown and co-immunoprecipitation analysis revealed that CiSTK38 can physically interact with CiGSK3β. Phos-tag PAGE illustrated CiSTK38 can decrease the phosphorylation and auto-phosphorylation level of CiGSK3β at Ser9 and at Tyr216. To investigate the functional correlation between CiSTK38 and CiGSK3β, we overexpressed CiSTK38 and CiGSK3β in CIK cells and found that they can up-regulate the expression of IFN I. In short, we demonstrated that CiSTK38 can confer CiGSK3β kinase activity by reducing its phosphorylation level. Result from this study strongly suggested that the anti-viral immune effects elicited by poly (I:C) in part were mediated through activation of CiGSK3β. The findings provided scientific basis for the anti-viral immune mechanism of STK38 and GSK3β in fish.

Streptolysin S induces mitochondrial damage and macrophage death through inhibiting degradation of glycogen synthase kinase-3β in Streptococcus pyogenes infection

Group A Streptococcus (GAS) infection is associated with a variety of human diseases. Previous studies indicate GAS infection leads to RAW264.7 cell death, but the mechanism is unclear. Here, analyzing the timing of reactive oxygen species (ROS) production and using mitochondrial ROS scavenger, we found the wild type GAS-induced RAW264.7 cell death was associated with mitochondrial ROS. The wild type GAS infection could activate glycogen synthase kinase-3β (GSK-3β). Inhibition of GSK-3β activity by lithium chloride or decreasing GSK-3β expression by lentivirus-mediated short hairpin RNA for GSK-3β could not only decrease the wild type GAS-induced mitochondrial ROS generation, mitochondria damage and cell death, but also reduced GAS intracellular replication. Streptolysin S (SLS), a GAS toxin, played the important role on GAS-induced macrophage death. Compared to the wild type GAS with its isogenic sagB mutant (SLS mutant)-infected macrophages, we found sagB mutant infection caused less mitochondrial ROS generation and cell death than those of the wild type GAS-infected ones. Furthermore, the sagB mutant, but not the wild type or the sagB-complementary mutant, could induce GSK-3β degradation via a proteasome-dependent pathway. These results suggest that a new mechanism of SLS-induced macrophage death was through inhibiting GSK-3β degradation and further enhancing mitochondrial damage.

Molecular control of protein synthesis, glucose metabolism, and apoptosis in the brain of hibernating thirteen-lined ground squirrels

Thirteen-lined ground squirrels (Ictidomys tridecemlineatus) are excellent models for studying acute brain ischemia because they show high resistance to reductions in blood flow and oxygen delivery without evidence of neurological damage. In this study, we analyzed the insulin signaling pathway and regulation of mitochondrial substrate oxidation in three regions of ground squirrel brain (forebrain, cerebellum, and brainstem), comparing summer, late torpor, and interbout arousal conditions. We found select decreases in phospho-Akt in the cerebellum during torpor compared with summer animals, as well as select increases in the forebrain during interbout arousal, suggesting that Akt may influence either metabolism or cytoprotective pathways. The phosphoprotein abundance of glycogen synthase kinase 3 beta (GSK3β) showed the most consistent trend across all three brain regions, with peak increases observed during deep torpor, suggesting a crucial role for this protein during hibernation. Furthermore, all three regions of the brain showed increased phospho-protein abundance of pyruvate dehydrogenase at serine 232 during both deep torpor and interbout arousal, and serine 300 during interbout arousal only, whereas other phosphorylation sites showed a region-specific expression pattern. Information collected from these studies sheds light on the molecular controls governing insulin signaling and fuel utilization in the brain of hibernating ground squirrels.

nSMase2 (Type 2-Neutral Sphingomyelinase) Deficiency or Inhibition by GW4869 Reduces Inflammation and Atherosclerosis in Apoe-/- Mice

OBJECTIVE

Atherosclerosis is a chronic multifactorial and inflammatory disease of large and medium arteries and the leading cause of cardiovascular diseases worldwide. The aim of this study was to investigate whether and how the nSMase2 (type 2-neutral sphingomyelinase), a key enzyme of sphingolipid metabolism, may contribute to the development of atherosclerotic lesions.

APPROACH AND RESULTS

The role of nSMase2 in atherosclerosis was investigated in Apoe^-/-;Smpd3^fro/fro mice, mutant for nSMase2, and in Apoe^-/-;Smpd3^+/+ mice intraperitoneally injected with GW4869, a pharmacological nSMase2 inhibitor. The defect or inhibition of nSMase2 resulted in a reduction of atherosclerotic lesions and a decrease in macrophage infiltration and lipid deposition, although cholesterolemia remained unchanged. nSMase2 inhibition decreased the inflammatory response of murine endothelial cells to oxLDL (oxidized low-density lipoprotein), as assessed by the significant reduction of MCP-1 (monocyte chemoattractant protein 1), ICAM-1 (intercellular adhesion molecule-1), and VCAM-1 (vascular cell adhesion molecule-1) mRNA expressions and macrophage recruitment. Likewise, in RAW264.7 or in macrophages isolated from Apoe^-/-/Smpd3^fro/fro or Apoe^-/-/Smpd3^+/+ mice stimulated by lipopolysaccharides, nSMase2 inhibition resulted in a decrease in the expression of inflammatory molecules. Mechanistically, the anti-inflammatory response resulting from nSMase2 inhibition involves Nrf2 (nuclear factor [erythroid-derived 2]-like 2 or NF-E2-related factor-2) activation in both endothelial cells and macrophages, as assessed by the lack of protective effect of GW4869 in endothelial cells silenced for Nrf2 by small interfering RNAs, and in lipopolysaccharide-stimulated macrophages issued from Nrf2-KO mice.

CONCLUSIONS

The genetic deficiency or inhibition of nSMase2 strongly decreases the development of atherosclerotic lesions in Apoe^-/- mice, by reducing inflammatory responses through a mechanism involving the Nrf2 pathway. Inhibitors of nSMase2 may, therefore, constitute a novel approach to slow down atherosclerosis progression.

SIRT2 deacetylase regulates the activity of GSK3 isoforms independent of inhibitory phosphorylation

Glycogen synthase kinase 3 (GSK3) is a critical regulator of diverse cellular functions involved in the maintenance of structure and function. Enzymatic activity of GSK3 is inhibited by N-terminal serine phosphorylation. However, alternate post-translational mechanism(s) responsible for GSK3 inactivation are not characterized. Here, we report that GSK3α and GSK3β are acetylated at Lys246 and Lys183, respectively. Molecular modeling and/or molecular dynamics simulations indicate that acetylation of GSK3 isoforms would hinder both the adenosine binding and prevent stable interactions of the negatively charged phosphates. We found that SIRT2 deacetylates GSK3β, and thus enhances its binding to ATP. Interestingly, the reduced activity of GSK3β is associated with lysine acetylation, but not with phosphorylation at Ser9 in hearts of SIRT2-deficient mice. Moreover, GSK3 is required for the anti-hypertrophic function of SIRT2 in cardiomyocytes. Overall, our study identified lysine acetylation as a novel post-translational modification regulating GSK3 activity.

An increase in galectin-3 causes cellular unresponsiveness to IFN-γ-induced signal transduction and growth inhibition in gastric cancer cells

Glycogen synthase kinase (GSK)-3β facilitates interferon (IFN)-γ signaling by inhibiting Src homology-2 domain-containing phosphatase (SHP) 2. Mutated phosphoinositide 3-kinase (PI3K) and phosphatase and tensin homolog (PTEN) cause AKT activation and GSK-3β inactivation to induce SHP2-activated cellular unresponsiveness to IFN-γ in human gastric cancer AGS cells. This study investigated the potential role of galectin-3, which acts upstream of AKT/GSK-3β/SHP2, in gastric cancer cells. Increasing or decreasing galectin-3 altered IFN-γ signaling. Following cisplatin-induced galectin-3 upregulation, surviving cells showed cellular unresponsiveness to IFN-γ. Galectin-3 induced IFN-γ resistance independent of its extracellular β-galactoside-binding activity. Galectin-3 expression was not regulated by PI3K activation or by a decrease in PTEN. Increased galectin-3 may cause GSK-3β inactivation and SHP2 activation by promoting PDK1-induced AKT phosphorylation at a threonine residue. Overexpression of AKT, inactive GSK-3β^R96A, SHP2, or active SHP2^D61A caused cellular unresponsiveness to IFN-γ in IFN-γ-sensitive MKN45 cells. IFN-γ-induced growth inhibition and apoptosis in AGS cells were observed until galectin-3 expression was downregulated. These results demonstrate that an increase in galectin-3 facilitates AKT/GSK-3β/SHP2 signaling, causing cellular unresponsiveness to IFN-γ.

Vascular mechanotransduction data in a rodent model of diabetes: Pressure-induced regulation of SHP2 and associated signaling in the rat inferior vena cava

The effect of diabetes on vascular mechano-transductive response is of great concern. Given the higher rate of vein graft failures associated with diabetes, understanding the multiple cellular and molecular events associated with vascular remodeling is of vital importance. This article represents data related to a study published in Cardiovascular Diabetology [1] (Rice et al., 2006) and Open Journal of Endocrine and Metabolic Diseases [2] (Rice et al., 2015) evaluating the effect of pressurization on rat inferior venae cavae (IVC). Provided within this articles is information related to the method and processing of raw data related to our prior publish work and Data in Brief articles [3], [4] (Rice et al., 2017), as well as the evaluation of alternation in SHP-2 signaling and associated proteins in response to mechanical force. IVC from lean and obese animals were exposed to a 30 min perfusion of 120 mm Hg pressure and evaluated for changes in expression of SHP2, BCL-3, BCL-XL, HSP 27, HSP 70, and PI3K p85, along with the phosphorylation of SHP-2 (Tyr 542).

Post-translational modification of the interferon-gamma receptor alters its stability and signaling

The IFN gamma receptor 1 (IFNGR1) binds IFN-γ and activates gene transcription pathways crucial for controlling bacterial and viral infections. Although decreases in IFNGR1 surface levels have been demonstrated to inhibit IFN-γ signaling, little is known regarding the molecular mechanisms controlling receptor stability. Here, we show in epithelial and monocytic cell lines that IFNGR1 displays K48 polyubiquitination, is proteasomally degraded, and harbors three ubiquitin acceptor sites at K277, K279, and K285. Inhibition of glycogen synthase kinase 3 beta (GSK3β) destabilized IFNGR1 while overexpression of GSK3β increased receptor stability. We identified critical serine and threonine residues juxtaposed to ubiquitin acceptor sites that impacted IFNGR1 stability. In CRISPR-Cas9 IFNGR1 generated knockout cell lines, cellular expression of IFNGR1 plasmids encoding ubiquitin acceptor site mutations demonstrated significantly impaired STAT1 phosphorylation and decreased STAT1-dependent gene induction. Thus, IFNGR1 undergoes rapid site-specific polyubiquitination, a process modulated by GSK3β. Ubiquitination appears to be necessary for efficient IFNGR1-dependent gamma gene induction and represents a relatively uncharacterized regulatory mechanism for this receptor.

Reciprocal regulation of TLR2-mediated IFN-β production by SHP2 and Gsk3β

Toll-like receptor 2 (TLR2) mediates the innate immune response to bacterial lipopeptides and peptidoglycans by stimulating the production of inflammatory cytokines. However, the mechanisms by which TLR2 signaling regulates type I interferon (IFN)-β production are poorly understood. Here, we identified Src homology 2-containing protein tyrosine phosphatase 2 (SHP2) as a negative regulator of TLR2-induced IFN-β production. Pharmacological inhibition or reduced expression of SHP2 potentiated TLR2 agonist-mediated IFN-β transcription and STAT1 activation, whereas overexpression of SHP2 impaired IFN-β transcription and STAT1 activation. SHP2 physically associated with the glycogen synthase kinase 3β (Gsk3β) in an agonist-dependent manner. Gsk3β positively regulates transcription of IFN-β following TLR2 stimulation by inhibiting the phosphorylation of SHP2. SHP2 inhibited the transcriptional activity of IRF-1 and IRF-8 at the IFN-β promoter. Remarkably, IRF-1 and IRF-8 are recruited to the IFN-β promoter in a SHP2 phosphatase activity-dependent manner. These findings provide insight into the mechanisms by which SHP2 and Gsk3β work together to modulate TLR2-mediated IFN-β production in macrophages.

Soluble Egg Antigen Activates M2 Macrophages via the STAT6 and PI3K Pathways, and Schistosoma Japonicum Alternatively Activates Macrophage Polarization to Improve the Survival Rate of Septic Mice

Sepsis is one of the most challenging health problems worldwide. Our previous study showed that chronic schistosoma japonica (SJ) infection might increase serum anti-inflammatory factors to play a protective role, thus improving the survival rate of septic mice. Further research revealed that SJ infection promoted J774A.1 macrophage differentiation into M2 macrophages; suppressed LPS-induced activation of M1 macrophages; up-regulated CD163, IL-10, and TGF-β1 expression; inhibited TNF-α and iNOS expression; and blocked the effect of LPS-promoted TNF-α and iNOS expression. Furthermore, adoptive transfer of ex vivo programed M2 macrophages significantly increased the survival rate of septic mice. In vitro studies suggested that soluble egg antigen (SEA) from SJ played the same role as worm infection but had no impact on M1 macrophages. SEA reduced LPS-induced TNF-α and iNOS expression, decreased the inhibitory effect of LPS on IL-10 and TGF-β1 expression, increased STAT6 phosphorylation, and up-regulated PI3K and Akt expression but inhibited SOCS1 expression. When PI3K inhibitors were added, SEA-induced expression of CD163, IL-10, and arg1 might be reduced. Therefore, worm infection has a protective effect in septic mice in which SEA may play a key role via the STAT6 and PI3K pathways. This finding may provide a favorable solution for the treatment of sepsis, especially early cases. J. Cell. Biochem. 118: 4230-4239, 2017. © 2017 Wiley Periodicals, Inc.

Reactive oxygen species are required for zoledronic acid-induced apoptosis in osteoclast precursors and mature osteoclast-like cells

Inhibiting osteoclasts and osteoclast precursors to reduce bone resorption is an important strategy to treat osteoclast-related diseases, such as osteoporosis, inflammatory bone loss, and malignant bone metastasis. However, the mechanism by which apoptosis is induced in the osteoclasts and their precursors are not completely understood. Here, we used nitrogen-containing bisphosphonate zoledronic acid (ZA) to induce cell apoptosis in human and murine osteoclast precursors and mature osteoclast-like cells. Caspase-3-mediated cell apoptosis occurred following the ZA (100 μM) treatment. Reactive oxygen species (ROS) were also generated in a time-dependent manner. Following knock-down of the p47^phox expression, which is required for ROS activation, or co-treatment with the ROS inhibitor, N-acetyl-L-cysteine, ZA-induced apoptosis was significantly suppressed in both osteoclast precursors and mature osteoclast-like cells. The ROS-activated mitogen-activated protein kinases pathways did not trigger cell apoptosis. However, a ROS-regulated Mcl-1 decrease simultaneously with glycogen synthase kinase (GSK)-3β promoted cell apoptosis. These findings show that ZA induces apoptosis in osteoclast precursors and mature osteoclast-like cells by triggering ROS- and GSK-3β-mediated Mcl-1 down-regulation.

Escape from IFN-γ-dependent immunosurveillance in tumorigenesis

Immune interferon (IFN), also known as IFN-γ, promotes not only immunomodulation but also antimicrobial and anticancer activity. After IFN-γ binds to the complex of IFN-γ receptor (IFNGR) 1-IFNGR2 and subsequently activates its downstream signaling pathways, IFN-γ immediately causes transcriptional stimulation of a variety of genes that are principally involved in its biological activities. Regarding IFN-γ-dependent immunosurveillance, IFN-γ can directly suppress tumorigenesis and infection and/or can modulate the immunological status in both cancer cells and infected cells. Regarding the anticancer effects of IFN-γ, cancer cells develop strategies to escape from IFN-γ-dependent cancer immunosurveillance. Immune evasion, including the recruitment of immunosuppressive cells, secretion of immunosuppressive factors, and suppression of cytotoxic T lymphocyte responses, is speculated to be elicited by the oncogenic microenvironment. All of these events effectively downregulate IFN-γ-expressing cells and IFN-γ production. In addition to these extrinsic pathways, cancer cells may develop cellular tolerance that manifests as hyporesponsiveness to IFN-γ stimulation. This review discusses the potential escape mechanisms from IFN-γ-dependent immunosurveillance in tumorigenesis.

Neuronal seipin knockout facilitates Aβ-induced neuroinflammation and neurotoxicity via reduction of PPARγ in hippocampus of mouse

Background

A characteristic phenotype of congenital generalized lipodystrophy 2 (CGL2) that is caused by loss-of-function of seipin gene is mental retardation. Seipin is highly expressed in hippocampal pyramidal cells and astrocytes. Neuronal knockout of seipin in mice (seipin-KO mice) reduces the hippocampal peroxisome proliferator-activated receptor gamma (PPARγ) level without the loss of pyramidal cells. The down-regulation of PPARγ has gained increasing attention in neuroinflammation of Alzheimer’s disease (AD). Thus, the present study focused on exploring the influence of seipin depletion on β-amyloid (Aβ)-induced neuroinflammation and Aβ neurotoxicity.

Methods

Adult male seipin-KO mice were treated with a single intracerebroventricular (i.c.v.) injection of Aβ_25–35 (1.2 nmol/mouse) or Aβ_1–42 (0.1 nmol/mouse), generally a non-neurotoxic dose in wild-type (WT) mice. Spatial cognitive behaviors were assessed by Morris water maze and Y-maze tests, and hippocampal CA1 pyramidal cells and inflammatory responses were examined.

Results

The Aβ_{25–35/1–42} injection in the seipin-KO mice caused approximately 30–35 % death of pyramidal cells and production of Hoechst-positive cells with the impairment of spatial memory. In comparison with the WT mice, the number of astrocytes and microglia in the seipin-KO mice had no significant difference, whereas the levels of IL-6 and TNF-α were slightly increased. Similarly, the Aβ_{25–35/1–42} injection in the seipin-KO mice rather than the WT mice could stimulate the activation of astrocytes or microglia and further elevated the levels of IL-6 and TNF-α. Treatment of the seipin-KO mice with the PPARγ agonist rosiglitazone (rosi) could prevent Aβ_{25–35/1–42}-induced neuroinflammation and neurotoxicity, which was blocked by the PPARγ antagonist GW9962. In the seipin-KO mice, the level of glycogen synthase kinase-3β (GSK3β) phosphorylation at Tyr216 was elevated, while at Ser9, it was reduced compared to the WT mice, which were corrected by the rosi treatment but were unaffected by the Aβ_25–35 injection.

Conclusions

Seipin deficiency in astrocytes increases GSK3β activity and levels of IL-6 and TNF-α through reducing PPARγ, which can facilitate Aβ_{25–35/1–42}-induced neuroinflammation to cause the death of neuronal cells and cognitive deficits.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-016-0598-3) contains supplementary material, which is available to authorized users.

Downregulated Expression of PTPN9 Contributes to Human Hepatocellular Carcinoma Growth and Progression

Human hepatocellular carcinoma (HCC) is one of the most common malignant cancers, whose molecular mechanisms is remains largely. PTPN9 has recently been reported to play a critical role in breast cancer development. However, the role of PTPN9 in human HCC remains elusive. The present study aimed at investigating the potential role of PTPN9 in HCC. Western blot and immunohistochemistry were used to examine the expression of PTPN9 protein in HCC and adjacent non-tumorous tissues in 45 patients. Furthermore, Cell Counting Kit-8, flow cytometry and RNA interference experiments were performed to analyze the role of PTPN9 in the regulation of HCC cell proliferation. We showed that the expression level of PTPN9 was significantly reduced in HCC, compared with adjacent non-tumorous tissues. PTPN9 expression was inversely associated with Tumor size (P = 0.014), serum AFP level (P = 0.004) and Ki-67 expression. Low expression of PTPN9 predicted poor survival in HCC patients. Moreover, PTPN9 interference assay that PTPN9 inhibited cell proliferation in HepG2 cells. Cell apoptosis assay revealed that, silencing of PTPN9 expression significantly reduced cell apoptosis, compared with control ShRNA treatment group. Our results suggested that PTPN9 expression was down-regulated in HCC tumor tissues, and reduced PTPN9 expression was associated with worsened overall survival in HCC patients. Depletion of PTPN9 inhibits the apoptosis and promotes the proliferation of HCC cells.

Enterovirus 71 Proteins 2A and 3D Antagonize the Antiviral Activity of Gamma Interferon via Signaling Attenuation

Enterovirus 71 (EV71) infection causes severe mortality involving multiple possible mechanisms, including cytokine storm, brain stem encephalitis, and fulminant pulmonary edema. Gamma interferon (IFN-γ) may confer anti-EV71 activity; however, the claim that disease severity is highly correlated to an increase in IFN-γ is controversial and would indicate an immune escape initiated by EV71. This study, investigating the role of IFN-γ in EV71 infection using a murine model, showed that IFN-γ was elevated. Moreover, IFN-γ receptor-deficient mice showed higher mortality rates and more severe disease progression with slower viral clearance than wild-type mice. In vitro results showed that IFN-γ pretreatment reduced EV71 yield, whereas EV71 infection caused IFN-γ resistance with attenuated IFN-γ signaling in IFN regulatory factor 1 (IRF1) gene transactivation. To study the immunoediting ability of EV71 proteins in IFN-γ signaling, 11 viral proteins were stably expressed in cells without cytotoxicity; however, viral proteins 2A and 3D blocked IFN-γ-induced IRF1 transactivation following a loss of signal transducer and activator of transcription 1 (STAT1) nuclear translocation. Viral 3D attenuated IFN-γ signaling accompanied by a STAT1 decrease without interfering with IFN-γ receptor expression. Restoration of STAT1 or blocking 3D activity was able to rescue IFN-γ signaling. Interestingly, viral 2A attenuated IFN-γ signaling using another mechanism by reducing the serine phosphorylation of STAT1 following the inactivation of extracellular signal-regulated kinase without affecting STAT1 expression. These results demonstrate the anti-EV71 ability of IFN-γ and the immunoediting ability by EV71 2A and 3D, which attenuate IFN-γ signaling through different mechanisms.

IMPORTANCE

Immunosurveillance by gamma interferon (IFN-γ) may confer anti-enterovirus 71 (anti-EV71) activity; however, the claim that disease severity is highly correlated to an increase in IFN-γ is controversial and would indicate an immune escape initiated by EV71. IFN-γ receptor-deficient mice showed higher mortality and more severe disease progression, indicating the anti-EV71 property of IFN-γ. However, EV71 infection caused cellular insusceptibility in response to IFN-γ stimulation. We used an in vitro system with viral protein expression to explore the novel IFN-γ inhibitory properties of the EV71 2A and 3D proteins through the different mechanisms. According to this study, targeting either 2A or 3D pharmacologically and/or genetically may sustain a cellular susceptibility in response to IFN-γ, particularly for IFN-γ-mediated anti-EV71 activity.

Changes in Susceptibility to Oncolytic Vesicular Stomatitis Virus during Progression of Prostate Cancer

A major challenge to oncolytic virus therapy is that individual cancers vary in their sensitivity to oncolytic viruses, even when these cancers arise from the same tissue type. Variability in response may arise due to differences in the initial genetic lesions leading to cancer development. Alternatively, susceptibility to viral oncolysis may change during cancer progression. These hypotheses were tested using cells from a transgenic mouse model of prostate cancer infected with vesicular stomatitis virus (VSV). Primary cultures from murine cancers derived from prostate-specific Pten deletion contained a mixture of cells that were susceptible and resistant to VSV. Castration-resistant cancers contained a higher percentage of susceptible cells than cancers from noncastrated mice. These results indicate both susceptible and resistant cells can evolve within the same tumor. The role of Pten deletion was further investigated using clonal populations of murine prostate epithelial (MPE) progenitor cells and tumor-derived Pten(-/-) cells. Deletion of Pten in MPE progenitor cells using a lentivirus vector resulted in cells that responded poorly to interferon and were susceptible to VSV infection. In contrast, tumor-derived Pten(-/-) cells expressed higher levels of the antiviral transcription factor STAT1, activated STAT1 in response to VSV, and were resistant to VSV infection. These results suggest that early in tumor development following Pten deletion, cells are primarily sensitive to VSV, but subsequent evolution in tumors leads to development of cells that are resistant to VSV infection. Further evolution in castration-resistant tumors leads to tumors in which cells are primarily sensitive to VSV.

IMPORTANCE

There has been a great deal of progress in the development of replication-competent viruses that kill cancer cells (oncolytic viruses). However, a major problem is that individual cancers vary in their sensitivity to oncolytic viruses, even when these cancers arise from the same tissue type. The experiments presented here were to determine whether both sensitive and resistant cells are present in prostate cancers originating from a single genetic lesion in transgenic mice, prostate-specific deletion of the gene for the tumor suppressor Pten. The results indicate that murine prostate cancers are composed of both cells that are sensitive and cells that are resistant to oncolytic vesicular stomatitis virus (VSV). Furthermore, androgen deprivation led to castration-resistant prostate cancers that were composed primarily of cells that were sensitive to VSV. These results are encouraging for the use of VSV for the treatment of prostate cancers that are resistant to androgen deprivation therapy.

Inflammation and lithium: clues to mechanisms contributing to suicide-linked traits

Suicide is one of the leading causes of death in the United States, yet it remains difficult to understand the mechanistic provocations and to intervene therapeutically. Stress is recognized as a frequent precursor to suicide. Psychological stress is well established to cause activation of the inflammatory response, including causing neuroinflammation, an increase of inflammatory molecules in the central nervous system (CNS). Neuroinflammation is increasingly recognized as affecting many aspects of CNS functions and behaviors. In particular, much evidence demonstrates that inflammatory markers are elevated in traits that have been linked to suicidal behavior, including aggression, impulsivity and depression. Lithium is recognized as significantly reducing suicidal behavior, is anti-inflammatory and diminishes aggression, impulsivity and depression traits, each of which is associated with elevated inflammation. The anti-inflammatory effects of lithium result from its inhibition of glycogen synthase kinase-3 (GSK3). GSK3 has been demonstrated to strongly promote inflammation, aggressive behavior in rodents and depression-like behaviors in rodents, whereas regulation of impulsivity by GSK3 has not yet been investigated. Altogether, evidence is building supporting the hypothesis that stress activates GSK3, which in turn promotes inflammation, and that inflammation is linked to behaviors associated with suicide, including particularly aggression, impulsivity and depression. Further investigation of these links may provide a clearer understanding of the causes of suicidal behavior and provide leads for the development of effective preventative interventions, which may include inhibitors of GSK3.

Roles and regulation of neutral sphingomyelinase-2 in cellular and pathological processes

Our understanding of the functions of ceramide signaling has advanced tremendously over the past decade. In this review, we focus on the roles and regulation of neutral sphingomyelinase 2 (nSMase2), an enzyme that generates the bioactive lipid ceramide through the hydrolysis of the membrane lipid sphingomyelin. A large body of work has now implicated nSMase2 in a diverse set of cellular functions, physiological processes, and disease pathologies. We discuss different aspects of this enzyme's regulation from transcriptional, post-translational, and biochemical. Furthermore, we highlight nSMase2 involvement in cellular processes including inflammatory signaling, exosome generation, cell growth, and apoptosis, which in turn play important roles in pathologies such as cancer metastasis, Alzheimer's disease, and other organ systems disorders. Lastly, we examine avenues where targeted nSMase2-inhibition may be clinically beneficial in disease scenarios.

Helicobacter pylori infection activates Src homology-2 domain-containing phosphatase 2 to suppress IFN-γ signaling

Helicobacter pylori infection not only induces gastric inflammation but also increases the risk of gastric tumorigenesis. IFN-γ has antimicrobial effects; however, H. pylori infection elevates IFN-γ-mediated gastric inflammation and may suppress IFN-γ signaling as a strategy to avoid immune destruction through an as-yet-unknown mechanism. This study was aimed at investigating the mechanism of H. pylori-induced IFN-γ resistance. Postinfection of viable H. pylori decreased IFN-γ-activated signal transducers and activators of transcription 1 and IFN regulatory factor 1 not only in human gastric epithelial MKN45 and AZ-521 but also in human monocytic U937 cells. H. pylori caused an increase in the C-terminal tyrosine phosphorylation of Src homology-2 domain-containing phosphatase (SHP) 2. Pharmacologically and genetically inhibiting SHP2 reversed H. pylori-induced IFN-γ resistance. In contrast to a clinically isolated H. pylori strain HP238, the cytotoxin-associated gene A (CagA) isogenic mutant strain HP238(CagAm) failed to induce IFN-γ resistance, indicating that CagA regulates this effect. Notably, HP238 and HP238(CagAm) differently caused SHP2 phosphorylation; however, imaging and biochemical analyses demonstrated CagA-mediated membrane-associated binding with phosphorylated SHP2. CagA-independent generation of reactive oxygen species (ROS) contributed to H. pylori-induced SHP2 phosphorylation; however, ROS/SHP2 mediated IFN-γ resistance in a CagA-regulated manner. This finding not only provides an alternative mechanism for how CagA and ROS coregulate SHP2 activation but may also explain their roles in H. pylori-induced IFN-γ resistance.

Autophagy facilitates cytokine-induced ICAM-1 expression

ICAM-1 can be induced by inflammatory cytokines such as IFN-γ and TNF-α. This study investigated whether autophagy regulates ICAM-1 given that autophagy facilitates signaling of these two cytokines. Exogenous IFN-γ induced ICAM-1 in human lung epithelial A549 cells carrying wild type p53, a transcription factor reported for ICAM-1, but not in PC14PE6/AS2 (AS2) cells carrying mutated p53. However, IFN-γ also induced ICAM-1 in A549 cells with short hairpin RNA-silenced p53. No changes in IFN-γ receptor expression were observed in AS2 cells, but IFN-γ-activated Jak2/STAT1/IFN regulatory factor 1 was markedly decreased. In AS2 cells, increased levels of reactive oxygen species induced the activation of Src homology domain-containing phosphatase 2 (SHP2), while SHP2 was essential for IFN-γ resistance. AS2 cells showed autophagy resistance, and the manipulation of the autophagy pathway altered IFN-γ resistance. Aberrant Bcl-2 expression and mammalian target of rapamycin activation contributed to both autophagy resistance and IFN-γ resistance. Autophagy, but not p53, also modulated TNF-α-induced NF-κB activation and ICAM-1 expression. Inhibiting autophagy decreased the adhesion of human monocytic U937 cells to IFN-γ-treated A549 cells. These results demonstrated that IFN-γ and TNF-α induced ICAM-1 expression through a common pathway that was regulated by autophagy, but not p53.

Induction of TRIM22 by IFN-γ Involves JAK and PC-PLC/PKC, but Not MAPKs and pI3K/Akt/mTOR Pathways

Tripartite motif (TRIM) 22 plays an important role in interferons (IFNs)-mediated antiviral activity. We previously demonstrated that interferon regulatory factor-1 (IRF-1) played a central role in IFN-γ-induced TRIM22 expression via binding to a special cis-element named 5' extended IFN-stimulating response element (5'eISRE). In this study, we sought to identify the signaling pathways involved in TRIM22 induction by IFN-γ. By using various pharmacological inhibitors, it was found that the activity of tyrosine kinase and phosphatidylcholine-phospholipase C (PC-PLC), but not phosphatidylinositol-phospholipase C (PI-PLC) and phospholipase D (PLD), was required for IFN-γ-induced TRIM22 expression in HepG2 cells. Tyrosine kinase Janus kinase (JAK), not SRC and PYK2, played an indispensable role in TRIM22 induction. Inhibition of protein kinase C (PKC) activity also significantly attenuated IFN-γ induction of TRIM22. Although treatment with IFN-γ resulted in the stimulation of mitogen-activated protein kinases (MAPKs) (p38, ERK, and JNK) and pI3K/Akt/mTOR pathways in HepG2 cells, the inhibition of their activity did not affect IFN-γ-stimulated TRIM22 expression. Further studies showed that overexpression of JAK1 and PKCα activated TRIM22 promoter activity in a 5'eISRE-dependent manner, and inhibition of not only JAK but also PC-PLC/PKC pathways significantly attenuated IFN-γ-induced IRF-1 expression in HepG2 cells. Taken together, these data indicated that IFN-γ induced TRIM22 expression via activation of JAK and PC-PLC/PKC signaling pathways, which involved the cis-element 5'eISRE and the transactivator IRF-1.

Regulation of Th1 cells and experimental autoimmune encephalomyelitis by glycogen synthase kinase-3

Experimental autoimmune encephalomyelitis (EAE) is a rodent model of multiple sclerosis (MS), a debilitating autoimmune disease of the CNS, for which only limited therapeutic interventions are available. Because MS is mediated in part by autoreactive T cells, particularly Th17 and Th1 cells, in the current study, we tested whether inhibitors of glycogen synthase kinase-3 (GSK3), previously reported to reduce Th17 cell generation, also alter Th1 cell production or alleviate EAE. GSK3 inhibitors were found to impede the production of Th1 cells by reducing STAT1 activation. Molecularly reducing the expression of either of the two GSK3 isoforms demonstrated that Th17 cell production was sensitive to reduced levels of GSK3β and Th1 cell production was inhibited in GSK3α-deficient cells. Administration of the selective GSK3 inhibitors TDZD-8, VP2.51, VP0.7, or L803-mts significantly reduced the clinical symptoms of myelin oligodendrocyte glycoprotein35-55-induced EAE in mice, nearly eliminating the chronic progressive phase, and reduced the number of Th17 and Th1 cells in the spinal cord. Administration of TDZD-8 or L803-mts after the initial disease episode alleviated clinical symptoms in a relapsing-remitting model of proteolipid protein139-151-induced EAE. Furthermore, deletion of GSK3β specifically in T cells was sufficient to alleviate myelin oligodendrocyte glycoprotein35-55-induced EAE. These results demonstrate the isoform-selective effects of GSK3 on T cell generation and the therapeutic effects of GSK3 inhibitors in EAE, as well as showing that GSK3 inhibition in T cells is sufficient to reduce the severity of EAE, suggesting that GSK3 may be a feasible target for developing new therapeutic interventions for MS.

Regulatory role of GSK-3 β on NF- κ B, nitric oxide, and TNF- α in group A streptococcal infection

Group A streptococcus (GAS) imposes a great burden on humans. Efforts to minimize the associated morbidity and mortality represent a critical issue. Glycogen synthase kinase-3β (GSK-3β) is known to regulate inflammatory response in infectious diseases. However, the regulation of GSK-3β in GAS infection is still unknown. The present study investigates the interaction between GSK-3β, NF-κB, and possible related inflammatory mediators in vitro and in a mouse model. The results revealed that GAS could activate NF-κB, followed by an increased expression of inducible nitric oxide synthase (iNOS) and NO production in a murine macrophage cell line. Activation of GSK-3β occurred after GAS infection, and inhibition of GSK-3β reduced iNOS expression and NO production. Furthermore, GSK-3β inhibitors reduced NF-κB activation and subsequent TNF-α production, which indicates that GSK-3β acts upstream of NF-κB in GAS-infected macrophages. Similar to the in vitro findings, administration of GSK-3β inhibitor in an air pouch GAS infection mouse model significantly reduced the level of serum TNF-α and improved the survival rate. The inhibition of GSK-3β to moderate the inflammatory effect might be an alternative therapeutic strategy against GAS infection.

Phospholipases of mineralization competent cells and matrix vesicles: roles in physiological and pathological mineralizations

The present review aims to systematically and critically analyze the current knowledge on phospholipases and their role in physiological and pathological mineralization undertaken by mineralization competent cells. Cellular lipid metabolism plays an important role in biological mineralization. The physiological mechanisms of mineralization are likely to take place in tissues other than in bones and teeth under specific pathological conditions. For instance, vascular calcification in arteries of patients with renal failure, diabetes mellitus or atherosclerosis recapitulates the mechanisms of bone formation. Osteoporosis—a bone resorbing disease—and rheumatoid arthritis originating from the inflammation in the synovium are also affected by cellular lipid metabolism. The focus is on the lipid metabolism due to the effects of dietary lipids on bone health. These and other phenomena indicate that phospholipases may participate in bone remodelling as evidenced by their expression in smooth muscle cells, in bone forming osteoblasts, chondrocytes and in bone resorbing osteoclasts. Among various enzymes involved, phospholipases A₁ or A₂, phospholipase C, phospholipase D, autotaxin and sphingomyelinase are engaged in membrane lipid remodelling during early stages of mineralization and cell maturation in mineralization-competent cells. Numerous experimental evidences suggested that phospholipases exert their action at various stages of mineralization by affecting intracellular signaling and cell differentiation. The lipid metabolites—such as arachidonic acid, lysophospholipids, and sphingosine-1-phosphate are involved in cell signaling and inflammation reactions. Phospholipases are also important members of the cellular machinery engaged in matrix vesicle (MV) biogenesis and exocytosis. They may favour mineral formation inside MVs, may catalyse MV membrane breakdown necessary for the release of mineral deposits into extracellular matrix (ECM), or participate in hydrolysis of ECM. The biological functions of phospholipases are discussed from the perspective of animal and cellular knockout models, as well as disease implications, development of potent inhibitors and therapeutic interventions.

Increased expression of tyrosine phosphatase SHP-2 in Helicobacter pylori-infected gastric cancer

AIM

To explore the alteration of tyrosine phosphatase SHP-2 protein expression in gastric cancer and to assess its prognostic values.

METHODS

Three hundred and five consecutive cases of gastric cancer were enrolled into this study. SHP-2 expression was carried out in 305 gastric cancer specimens, of which 83 were paired adjacent normal gastric mucus samples, using a tissue microarray immunohistochemical method. Correlations were analyzed between expression levels of SHP-2 protein and tumor parameters or clinical outcomes. Serum anti-Helicobacter pylori (H. pylori) immunoglobulin G was detected with enzyme-linked immunosorbent assay. Cox proportional hazards model was used to evaluate prognostic values by compassion of the expression levels of SHP-2 and disease-specific survivals in patients.

RESULTS

SHP-2 staining was found diffuse mainly in the cytoplasm and the weak staining was also observed in the nucleus in gastric mucosa cells. Thirty-two point five percent of normal epithelial specimen and 62.6% of gastric cancer specimen were identified to stain with SHP-2 antibody positively (P < 0.001). Though SHP-2 staining intensities were stronger in the H. pylori (+) group than in the H. pylori (-) group, no statistically significant difference was found in the expression levels of SHP-2 between H. pylori (+) and H. pylori (-) gastric cancer (P = 0.40). The SHP-2 expression in gastric cancer was not significantly associated with cancer stages, lymph node metastases, and distant metastasis of the tumors (P = 0.34, P = 0.17, P = 0.52). Multivariate analysis demonstrated no correlation between SHP-2 expression and disease-free survival (P = 0.86).

CONCLUSION

Increased expression of SHP-2 protein in gastric cancer specimen suggesting the aberrant up-regulation of SHP-2 protein might play an important role in the gastric carcinogenesis.

Lithium controls central nervous system autoimmunity through modulation of IFN-γ signaling

Inhibitors of glycogen synthase kinase 3 (GSK3) are being explored as therapy for chronic inflammatory diseases. We previously demonstrated that the GSK inhibitor lithium is beneficial in experimental autoimmune encephalomyelitis (EAE), the mouse model of multiple sclerosis. In this study we report that lithium suppresses EAE induced by encephalitogenic interferon-γ (IFN-γ)-producing T helper (Th1) cells but not by interleukin (IL)-17-producing T helper (Th17) cells. The therapeutic activity of lithium required functional IFN-γ-signaling, but not the receptor for type I IFN (IFNAR). Inhibitor/s of GSK3 attenuated IFN-γ dependent activation of the transcription factor STAT1 in naïve T cells as well as in encephalitogenic T cells and Th1 cells. The inhibition of STAT1 activation was associated with reduced IFN-γ production and decreased expansion of encephalitogenic Th1 cells. Furthermore, lithium treatment induced Il27 expression within the spinal cords of mice with EAE. In contrast, such treatment of Ifngr(-/-) mice did not induce Il27 and was associated with lack of therapeutic response. Our study reveals a novel mechanism for the efficacy of GSK3 targeting in EAE, through the IFN-γ-STAT1 axis that is independent IFNAR-STAT1 axis. Overall our findings set the framework for the use of GSK3 inhibitors as therapeutic agents in autoimmune neuroinflammation.

Inhibiting glycogen synthase kinase-3 decreases 12-O-tetradecanoylphorbol-13-acetate-induced interferon-γ-mediated skin inflammation

Glycogen synthase kinase-3 (GSK-3) facilitates interferon (IFN)-γ signaling. Because IFN-γ is involved in inflammatory skin diseases, such as psoriasis, the aim of this study was to investigate the pathogenic role of GSK-3 in 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced IFN-γ-mediated ear skin inflammation. TPA (3 μg per ear) induced acute skin inflammation in the ears of C57BL/6 mice, including edema, infiltration of granulocytes but not T cells, and IFN-γ receptor 1-mediated deregulation of intercellular adhesion molecule 1 (CD54). TPA/IFN-γ induced GSK-3 activation, which in turn activated signal transducer and activator of transcription 1. Inhibiting GSK-3 pharmacologically, by administering 6-bromoindirubin-3'-oxime (1.5 μg per ear), and genetically, with lentiviral-based short-hairpin RNA, reduced TPA-induced acute skin inflammation but not T-cell infiltration. It is noteworthy that inhibiting GSK-3 decreased TPA-induced IFN-γ production and the nuclear translocation of T-box transcription factor Tbx21, a transcription factor of IFN-γ, in CD3-positive T cells. In chronic TPA-induced skin inflammation, inhibiting GSK-3 attenuated epidermis hyperproliferation and dermis angiogenesis. These results demonstrate the dual role of GSK-3 in TPA-induced skin inflammation that is not only to facilitate IFN-γ signaling but also to regulate IFN-γ production. Inhibiting GSK-3 may be a potential treatment strategy for preventing such effects.

Annexin A2 silencing induces G2 arrest of non-small cell lung cancer cells through p53-dependent and -independent mechanisms

Annexin A2 (ANXA2) overexpression is required for cancer cell proliferation; however, the molecular mechanisms underlying ANXA2-mediated regulation of the cell cycle are still unknown. ANXA2 is highly expressed in non-small cell lung cancer (NSCLC) and is positively correlated with a poor prognosis. NSCLC A549 cells lacking ANXA2 exhibited defects in tumor growth in vivo and in cell proliferation in vitro without cytotoxicity. ANXA2 knockdown induced cell cycle arrest at G(2) phase. Unexpectedly, ANXA2 silencing increased the expression of p53 and its downstream genes, which resulted in p53-dependent and -independent G(2) arrest. Aberrant JNK inactivation, which was observed in ANXA2-deficient cells, inhibited cell proliferation following G(2) arrest. A lack of ANXA2 caused a loss of JNK-regulated c-Jun expression, resulting in an increase in p53 transcription. These results demonstrate a novel role for ANXA2 in NSCLC cell proliferation by facilitating the cell cycle partly through the regulation of p53 via JNK/c-Jun.

The Jak/STAT pathway is involved in synaptic plasticity

The Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway is involved in many cellular processes, including cell growth and differentiation, immune functions and cancer. It is activated by various cytokines, growth factors, and protein tyrosine kinases (PTKs) and regulates the transcription of many genes. Of the four JAK isoforms and seven STAT isoforms known, JAK2 and STAT3 are highly expressed in the brain where they are present in the postsynaptic density (PSD). Here, we demonstrate a new neuronal function for the JAK/STAT pathway. Using a variety of complementary approaches, we show that the JAK/STAT pathway plays an essential role in the induction of NMDA-receptor dependent long-term depression (NMDAR-LTD) in the hippocampus. Therefore, in addition to established roles in cytokine signaling, the JAK/STAT pathway is involved in synaptic plasticity in the brain.

Protein tyrosine phosphatase Meg2 dephosphorylates signal transducer and activator of transcription 3 and suppresses tumor growth in breast cancer

Introduction

Signal transducer and activator of transcription 3 (STAT3) is over-activated or phosphorylated in breast cancers. The hyper-phosphorylation of STAT3 was attributed to either up-regulated phosphorylation by several tyrosine-kinases or down-regulated activity of phosphatases. Although several factors have been identified to phosphorylate STAT3, it remains unclear how STAT3 is dephosphorylated by PTPMeg2. The aim of this study was to determine the role of PTPMeg2 as a phosphatase in regulation of the activity of STAT3 in breast cancers.

Methods

Immunoprecipitation assays were used to study the interaction of STAT3 with PTPMeg2. A series of biochemistry experiments were performed to evaluate the role of PTPMeg2 in the dephosphorylation of STAT3. Two breast cancer cell lines MCF7 (PTPMeg2 was depleted as it was endogenously high) and MDA-MB-231 (PTPMeg2 was overexpressed as it was endogenously low) were used to compare the level of phosphorylated STAT3 and the tumor growth ability in vitro and in vivo. Samples from breast carcinoma (n = 73) were subjected to a pair-wise Pearson correlation analysis for the correlation of levels of PTPMeg2 and phosphorylated STAT3.

Results

PTPMeg2 directly interacts with STAT3 and mediates its dephosphorylation in the cytoplasm. Over-expression of PTPMeg2 decreased tyrosine phosphorylation of STAT3 while depletion of PTPMeg2 increased its phosphorylation. The decreased tyrosine phosphorylation of STAT3 is coupled with suppression of STAT3 transcriptional activity and reduced tumor growth in vitro and in vivo. Levels of PTPMeg2 and phosphorylated STAT3 were inversely correlated in breast cancer tissues (P = 0.004).

Conclusions

PTPMeg2 is an important phosphatase for the dephosphorylation of STAT3 and plays a critical role in breast cancer development.