Pro-inflammatory cytokines and environmental stress cause p38 mitogen-activated protein kinase activation by dual phosphorylation on tyrosine and threonine

When PIP2 Meets p53: Nuclear Phosphoinositide Signaling in the DNA Damage Response

The mechanisms that maintain genome stability are critical for preventing tumor progression. In the past decades, many strategies were developed for cancer treatment to disrupt the DNA repair machinery or alter repair pathway selection. Evidence indicates that alterations in nuclear phosphoinositide lipids occur rapidly in response to genotoxic stresses. This implies that nuclear phosphoinositides are an upstream element involved in DNA damage signaling. Phosphoinositides constitute a new signaling interface for DNA repair pathway selection and hence a new opportunity for developing cancer treatment strategies. However, our understanding of the underlying mechanisms by which nuclear phosphoinositides regulate DNA damage repair, and particularly the dynamics of those processes, is rather limited. This is partly because there are a limited number of techniques that can monitor changes in the location and/or abundance of nuclear phosphoinositide lipids in real time and in live cells. This review summarizes our current knowledge regarding the roles of nuclear phosphoinositides in DNA damage response with an emphasis on the dynamics of these processes. Based upon recent findings, there is a novel model for p53's role with nuclear phosphoinositides in DNA damage response that provides new targets for synthetic lethality of tumors.

Regulation of c-Fos gene transcription by stimulus-responsive protein kinases

The basic region leucin zipper (bZIP) protein c-Fos constitutes together with other bZIP proteins the AP-1 transcription factor complex. Expression of the c-Fos gene is regulated by numerous extracellular signaling molecules including mitogens, metabolites, and ligands for receptor tyrosine kinases, G protein-coupled receptors, and cytokine receptors. Here, we analyzed the effects of the stimulus-responsive MAP kinases ERK1/2 (extracellular signal-regulated protein kinase), JNK (c-Jun N-terminal protein kinase) and p38 protein kinase on transcription of the c-Fos gene. We used chromatin-integrated c-Fos promoter-luciferase reporter genes containing inactivating point mutations of DNA binding sites for distinct transcription factors. ERK1/2, JNK, and p38 protein kinases were specifically activated following expression of either a mutant of B-Raf, a truncated version of mitogen-activated/extracellular signal responsive kinase kinase kinase-1 (MEKK1), or a mutant of MAP kinase kinase-6 (MKK6), respectively. The results show that the DNA binding sites for serum response factor (SRF) and for the ternary complex factor (TCF) are of major importance for stimulating c-Fos promoter activity by MAP kinases. ERK1/2 and p38-induced stimulation of the c-Fos promoter additionally required the DNA binding site for the transcription factor AP-1. Mutation of the DNA binding site for STAT had no or only a small effect on c-Fos promoter activity. We conclude that MAP kinases do not activate distinct transcription factors involving distinct genetic elements. Rather, these kinases mainly target SRF and TCF proteins, leading to an activation of transcription of the c-Fos gene via the serum response element.

Non-psychotropic Cannabis sativa L. phytocomplex modulates microglial inflammatory response through CB2 receptors-, endocannabinoids-, and NF-κB-mediated signaling

Cannabis sativa L. is increasingly emerging for its protective role in modulating neuroinflammation, a complex process orchestrated among others by microglia, the resident immune cells of the central nervous system. Phytocannabinoids, especially cannabidiol (CBD), terpenes, and other constituents trigger several upstream and downstream microglial intracellular pathways. Here, we investigated the molecular mechanisms of a CBD- and terpenes-enriched C. sativa extract (CSE) in an in vitro model of neuroinflammation. We evaluated the effect of CSE on the inflammatory response induced by exposure to lipopolysaccharide (LPS) in BV-2 microglial cells, compared with CBD and β-caryophyllene (CAR), CB2 receptors (CB2r) inverse and full agonist, respectively. The LPS-induced upregulation of the pro-inflammatory cytokines IL-1β, IL-6, and TNF-α was significantly attenuated by CSE and only partially by CBD, whereas CAR was ineffective. In BV-2 cells, these anti-inflammatory effects exerted by CSE phytocomplex were only partially dependent on CB2r modulation and they were mediated by the regulation of enzymes responsible for the endocannabinoids metabolism, by the inhibition of reactive oxygen species release and the modulation of JNK/p38 cascade with consequent NF-κB p65 nuclear translocation suppression. Our data suggest that C. sativa phytocomplex and its multitarget mechanism could represent a novel therapeutic strategy for neuroinflammatory-related diseases.

Molecular Mechanism Based on Histopathology, Antioxidant System and Transcriptomic Profiles in Heat Stress Response in the Gills of Japanese Flounder

As an economically important flatfish in Asia, Japanese flounder is threatened by continuously rising temperatures due to global warming. To understand the molecular responses of this species to temperature stress, adult Japanese flounder individuals were treated with two kinds of heat stress—a gradual temperature rise (GTR) and an abrupt temperature rise (ATR)—in aquaria under experimental conditions. Changes in histopathology, programmed cell death levels and the oxidative stress status of gills were investigated. Histopathology showed that the damage caused by ATR stress was more serious. TUNEL signals confirmed this result, showing more programmed cell death in the ATR group. In addition, reactive oxygen species (ROS) levels and the 8-O-hDG contents of both the GTR and ATR groups increased significantly, and the total superoxide dismutase (T-SOD) activities and total antioxidant capacity (T-AOC) levels decreased in the two stressed groups, which showed damage to antioxidant systems. Meanwhile, RNA-seq was utilized to illustrate the molecular mechanisms underyling gill damage. Compared to the control group of 18 °C, 507 differentially expressed genes (DEGs) were screened in the GTR group; 341 were up-regulated and 166 were down-regulated, and pathway enrichment analysis indicated that they were involved in regulation and adaptation, including chaperone and folding catalyst pathways, the mitogen-activated protein kinase signaling (MAPK) pathway and DNA replication protein pathways. After ATR stress, 1070 DEGs were identified, 627 were up-regulated and 423 were down-regulated, and most DEGs were involved in chaperone and folding catalyst and DNA-related pathways, such as DNA replication proteins and nucleotide excision repair. The annotation of DEGs showed the great importance of heat shock proteins (HSPs) in protecting Japanese flounder from heat stress injury; 12 hsp genes were found after GTR, while 5 hsp genes were found after ATR. In summary, our study records gill dysfunction after heat stress, with different response patterns observed in the two experimental designs; chaperones were activated to defend heat stress after GTR, while replication was almost abandoned due to the severe damage consequent on ATR stress.

The dualistic role of the purinergic P2Y12-receptor in an in vivo model of Parkinson's disease: Signalling pathway and novel therapeutic targets

Parkinson's disease (PD) is a chronic, progressive neurodegenerative condition; characterized with the degeneration of the nigrostriatal dopaminergic pathway and neuroinflammation. During PD progression, microglia, the resident immune cells in the central nervous system (CNS) display altered activity, but their role in maintaining PD development has remained unclear to date. The purinergic P2Y12-receptor (P2Y12R), which is expressed on the microglia in the CNS has been shown to regulate microglial activity and responses; however, the function of the P2Y12R in PD is unknown. Here we show that MPTP-induced PD symptoms in mice are associated with marked neuroinflammatory changes and P2Y12R contribute to the activation of microglia and progression of the disease. Surprisingly, while pharmacological or genetic targeting of the P2Y12R augments acute mortality in MPTP-treated mice, these interventions protect against the neurodegenerative cell loss and the development of neuroinflammation in vivo. Pharmacological inhibition of receptors during disease development reverses the symptoms of PD and halts disease progression. We found that P2Y12R regulates ROCK and p38 MAPK activity and control cytokine production. Our principal finding is that the receptor has a dualistic role in PD: functional P2Y12Rs are essential to initiate a protective inflammatory response, since the lack of the receptor leads to reduced survival; however, at later stages of neurodegeneration, P2Y12Rs are apparently responsible for maintaining the activated state of microglia and stimulating pro-inflammatory cytokine response. Understanding protective and detrimental P2Y12R-mediated actions in the CNS may reveal novel approaches to control neuroinflammation and modify disease progression in PD.

Kinase Inhibition as Treatment for Acute and Chronic Graft-Versus-Host Disease

Allogeneic hematopoietic stem cell transplantation (allo-HCT) is a potentially curative therapy for patients suffering from hematological malignancies via the donor immune system driven graft-versus-leukemia effect. However, the therapy is mainly limited by severe acute and chronic graft-versus-host disease (GvHD), both being life-threatening complications after allo-HCT. GvHD develops when donor T cells do not only recognize remaining tumor cells as foreign, but also the recipient’s tissue, leading to a severe inflammatory disease. Typical GvHD target organs include the skin, liver and intestinal tract. Currently all approved strategies for GvHD treatment are immunosuppressive therapies, with the first-line therapy being glucocorticoids. However, therapeutic options for glucocorticoid-refractory patients are still limited. Novel therapeutic approaches, which reduce GvHD severity while preserving GvL activity, are urgently needed. Targeting kinase activity with small molecule inhibitors has shown promising results in preclinical animal models and clinical trials. Well-studied kinase targets in GvHD include Rho-associated coiled-coil-containing kinase 2 (ROCK2), spleen tyrosine kinase (SYK), Bruton’s tyrosine kinase (BTK) and interleukin-2-inducible T-cell kinase (ITK) to control B- and T-cell activation in acute and chronic GvHD. Janus Kinase 1 (JAK1) and 2 (JAK2) are among the most intensively studied kinases in GvHD due to their importance in cytokine production and inflammatory cell activation and migration. Here, we discuss the role of kinase inhibition as novel treatment strategies for acute and chronic GvHD after allo-HCT.

MicroRNA-124 Promotes Singapore Grouper Iridovirus Replication and Negatively Regulates Innate Immune Response

Viral infections seriously affect the health of organisms including humans. Now, more and more researchers believe that microRNAs (miRNAs), one of the members of the non-coding RNA family, play significant roles in cell biological function, disease occurrence, and immunotherapy. However, the roles of miRNAs in virus infection (entry and replication) and cellular immune response remain poorly understood, especially in low vertebrate fish. In this study, based on the established virus-cell infection model, Singapore grouper iridovirus (SGIV)-infected cells were used to explore the roles of miR-124 of Epinephelus coioides, an economically mariculture fish in southern China and Southeast Asia, in viral infection and host immune responses. The expression level of E. coioides miR-124 was significantly upregulated after SGIV infection; miR-124 cannot significantly affect the entry of SGIV, but the upregulated miR-124 could significantly promote the SGIV-induced cytopathic effects (CPEs), the viral titer, and the expressions of viral genes. The target genes of miR-124 were JNK3/p38α mitogen-activated protein kinase (MAPK). Overexpression of miR-124 could dramatically inhibit the activation of NF-κB/activating protein-1 (AP-1), the transcription of proinflammatory factors, caspase-9/3, and the cell apoptosis. And opposite results happen when the expression of miR-124 was inhibited. The results suggest that E. coioides miR-124 could promote viral replication and negatively regulate host immune response by targeting JNK3/p38α MAPK, which furthers our understanding of virus and host immune interactions.

Low-Salt Diet Attenuates B-Cell- and Myeloid-Cell-Driven Experimental Arthritides by Affecting Innate as Well as Adaptive Immune Mechanisms

A link between high sodium chloride (salt) intake and the development of autoimmune diseases was previously reported. These earlier studies demonstrated exacerbation of experimental autoimmune encephalomyelitis and colitis by excess salt intake associated with Th17- and macrophage-mediated mechanisms. Little is known about the impact of dietary salt intake on experimental arthritides. Here, we investigated if salt restriction can exert beneficial effects on collagen-induced arthritis (CIA) and K/BxN serum transfer-induced arthritis (STIA). CIA depends on both adaptive and innate immunity, while STIA predominantly mimics the innate immune cell-driven effector phase of arthritis. In both models, low salt (LS) diet significantly decreased arthritis severity compared to regular salt (RS) and high salt (HS) diet. We did not observe an aggravation of arthritis with HS diet compared to RS diet. Remarkably, in STIA, LS diet was as effective as IL-1 receptor blocking treatment. Complement-fixing anti-CII IgG2a antibodies are associated with inflammatory cell infiltration and cartilage destruction. LS diet reduced anti-CII IgG2a levels in CIA and decreased the anti-CII IgG2a/IgG1 ratios pointing toward a more Th2-like response. Significantly less inflammatory joint infiltrates and cartilage breakdown associated with reduced protein concentrations of IL-1 beta (CIA and STIA), IL-17 (CIA), and the monocyte chemoattractant protein-1 (MCP-1) (CIA) were detected in mice receiving LS diet compared to HS diet. However, we did not find a reduced IL-17A expression in CD4+ T cells upon salt restriction in CIA. Analysis of mRNA transcripts and immunoblots revealed a link between LS diet and inhibition of the p38 MAPK (mitogen-activated protein kinase)/NFAT5 (nuclear factor of activated T-cells 5) signaling axis in STIA. Further experiments indicated a decreased leukodiapedesis under LS conditions. In conclusion, dietary salt restriction ameliorates CIA and STIA, indicating a beneficial role of LS diet during both the immunization and effector phase of immune-mediated arthritides by predominantly modulating the humoral immunity and the activation status of myeloid lineage cells. Hence, salt restriction might represent a supportive dietary intervention not only to reduce cardiovascular risk, but also to improve human inflammatory joint diseases like rheumatoid arthritis.

Sustained compensatory p38 MAPK signaling following treatment with MAPK inhibitors induces the immunosuppressive protein CD73 in cancer: combined targeting could improve outcomes

RAS-MAPK signaling promotes immune evasion and cancer cell survival, and MAPK inhibitors (MAPKis) are frequently used as cancer therapies. Despite progress elucidating the direct effects of MAPKi on immune cells, their indirect effect on the tumor microenvironment (TME) through changes in tumor cells remains incompletely understood. Here, we present evidence of a rapid compensatory response to MAPKi that is driven by sustained p38 MAPK signaling and by which cancer cells can upregulate the immunosuppressive protein CD73 to reduce the antitumor immune response. This compensatory response also results in decreased sensitivity toward MAPKi, and, accordingly, combining anti-CD73 antibodies and MAPKi significantly enhances the antitumor effect compared to single-agent treatment in vivo. Combining MAPKi and anti-CD73 was accompanied by significant alterations in intratumor immune cell composition, supporting the effect of MAPKi-induced CD73 expression on the TME. We show that high CD73 expression significantly correlates with worse outcome in MAPKi-treated colorectal cancer patients, highlighting the potential clinical importance of increased CD73 expression following MAPKi treatment. Our findings may explain the diminished effect of MAPKi in cancer patients and provides further rationale for combined anti-CD73 and MAPKi treatment.

Identification, evolution and expression analyses of mapk gene family in Japanese flounder (Paralichthys olivaceus) provide insight into its divergent functions on biotic and abiotic stresses response

Mitogen-activated protein kinase (MAPK) are a series of serine/threonine protein kinases showing evolutionary conservation, which can be activated by many stimulus signals and then transfer them from cell membrane to nucleus. MAPKs regulate a variety of biological processes, such as apoptosis, hormone signaling and immune response. In this study, 14 putative mapk genes in Japanese flounder were identified, and their basic physical and chemical properties were characterized. Phylogenetic analysis showed that mapk genes were divided into three main subfamilies, including ERK, JNK and the p38 MAPK. Selection pressure analysis revealed they were evolutionarily-constrained and undergone strong purifying selection. Gene structure and conserved protein motif comparison suggested high levels of conservation in members of mapk gene family. The expression patterns were further investigated in each embryonic and larval development stages and different tissues. In addition, RNA-seq analyses after bacteria and temperature stresses suggested mapk genes had different expression patterns. Three mapk genes showed significant differences in response to E. tarda challenge and five were induced significantly after temperature stress, indicating their potential functions. This systematic analysis provided valuable information for further understanding of the regulation mechanism of mapk gene family under different stresses in Japanese flounder.

Effects of different ischemic preconditioning strategies on physiological and cellular mechanisms of intestinal ischemia/reperfusion injury: Implication from an isolated perfused rat small intestine model

Background

Intestinal ischemia/reperfusion (I/R)-injury often results in sepsis and organ failure and is of major importance in the clinic. A potential strategy to reduce I/R-injury is the application of ischemic preconditioning (IPC) during which repeated, brief episodes of I/R are applied. The aim of this study was to evaluate physiological and cellular effects of intestinal I/R-injury and to compare the influence of in-vivo IPC (iIPC) with ex-vivo IPC (eIPC), in which blood derived factors and nerval regulations are excluded.

Methods

Using an established perfused rat intestine model, effects of iIPC and eIPC on physiological as well as cellular mechanisms of I/R-injury (60 min hypoxia, 30 min reperfusion) were investigated. iIPC was applied by three reversible occlusions of the mesenteric artery in-vivo for 5 min followed by 5 min of reperfusion before isolating the small intestine, eIPC was induced by stopping the vascular perfusion ex-vivo 3 times for 5 min followed by 5 min of reperfusion after isolation of the intestine. Study groups (each N = 8–9 animals) were: iIPC, eIPC, I/R (iIPC group), I/R (eIPC group), iIPC+I/R, eIPC+I/R, no intervention/control (iIPC group), no intervention/control (eIPC group). Tissue morphology/damage, metabolic functions, fluid shifts and barrier permeability were evaluated. Cellular mechanisms were investigated using signaling arrays.

Results

I/R-injury decreased intestinal galactose uptake (iIPC group: p<0.001), increased vascular perfusion pressure (iIPC group: p<0.001; eIPC group: p<0.01) and attenuated venous flow (iIPC group: p<0.05) while lactate-to-pyruvate ratio (iIPC group, eIPC group: p<0.001), luminal flow (iIPC group: p<0.001; eIPC group: p<0.05), goblet cell ratio (iIPC group, eIPC group: p<0.001) and apoptosis (iIPC group, eIPC group: p<0.05) were all increased. Application of iIPC prior to I/R increased vascular galactose uptake (P<0.05) while eIPC had no significant impact on parameters of I/R-injury. On cellular level, I/R-injury resulted in a reduction of the phosphorylation of several MAPK signaling molecules. Application of iIPC prior to I/R increased phosphorylation of JNK2 and p38δ while eIPC enhanced CREB and GSK-3α/β phosphorylation.

Conclusion

Intestinal I/R-injury is associated with major physiological and cellular changes. However, the overall influence of the two different IPC strategies on the acute phase of intestinal I/R-injury is rather limited.

Current Insights of Inhibitors of p38 Mitogen-Activated Protein Kinase in Inflammation

BACKGROUND

The inflammatory process is one of the mechanisms by which our body upholds us from pathogens such as parasites, bacteria, viruses, and other harmful microorganisms. Inflammatory stimuli activate many intracellular signaling pathways such as the nuclear factor-kB (NF-kB) pathway and three mitogen-activated protein kinase (MAPK) pathways, which are mediated through extracellular-signal regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and p38. The p38 has evolved as an enticing target in treating many persistent inflammatory diseases. Hence, designing novel p38 inhibitors targeting MAPK pathways has acquired significance.

OBJECTIVE

Peruse to identify the lead target to discover novel p38MAPK inhibitors with different scaffolds having improved selectivity over the prototype drugs.

METHODS

Structure and the binding sites of p38MAPK were focused. Various scaffolds designed for inhibition and the molecules which have entered the clinical trials are discussed.

RESULTS

This review aspires to present the available information on the structure and the 3D binding sites of p38MAPK, various scaffolds designed for imidazole, urea, benzamide, azoles, quinoxaline, chromone, ketone as a potent p38MAPK inhibitors and their SAR studies and the molecules which have entered the clinical trials.

CONCLUSION

The development of successful selective p38MAPK inhibitors in inflammatory diseases is in progress despite all challenges. It was speculated that p38MAPK also plays an important role in treating diseases such as neuroinflammation, arterial inflammation, vascular inflammation, cancer and so on, which are posing the world with treatment challenges. In this review, clinical trials of drugs are discussed related to inflammatory and its related diseases. Research is in progress to design and develop novel p38MAPK inhibitors with minimal side effects.

Stress-activated kinases as therapeutic targets in pancreatic cancer

Pancreatic cancer is a dismal disease with high incidence and poor survival rates. With the aim to improve overall survival of pancreatic cancer patients, new therapeutic approaches are urgently needed. Protein kinases are key regulatory players in basically all stages of development, maintaining physiologic functions but also being involved in pathogenic processes. c-Jun N-terminal kinases (JNK) and p38 kinases, representatives of the mitogen-activated protein kinases, as well as the casein kinase 1 (CK1) family of protein kinases are important mediators of adequate response to cellular stress following inflammatory and metabolic stressors, DNA damage, and others. In their physiologic roles, they are responsible for the regulation of cell cycle progression, cell proliferation and differentiation, and apoptosis. Dysregulation of the underlying pathways consequently has been identified in various cancer types, including pancreatic cancer. Pharmacological targeting of those pathways has been the field of interest for several years. While success in earlier studies was limited due to lacking specificity and off-target effects, more recent improvements in small molecule inhibitor design against stress-activated protein kinases and their use in combination therapies have shown promising in vitro results. Consequently, targeting of JNK, p38, and CK1 protein kinase family members may actually be of particular interest in the field of precision medicine in patients with highly deregulated kinase pathways related to these kinases. However, further studies are warranted, especially involving in vivo investigation and clinical trials, in order to advance inhibition of stress-activated kinases to the field of translational medicine.

Myofiber stretch induces tensile and shear deformation of muscle stem cells in their native niche

Muscle stem cells (MuSCs) are requisite for skeletal muscle regeneration and homeostasis. Proper functioning of MuSCs, including activation, proliferation, and fate decision, is determined by an orchestrated series of events and communication between MuSCs and their niche. A multitude of biochemical stimuli are known to regulate MuSC fate and function. However, in addition to biochemical factors, it is conceivable that MuSCs are subjected to mechanical forces during muscle stretch-shortening cycles because of myofascial connections between MuSCs and myofibers. MuSCs respond to mechanical forces in vitro, but it remains to be proven whether physical forces are also exerted on MuSCs in their native niche and whether they contribute to the functioning and fate of MuSCs. MuSC deformation in their native niche resulting from mechanical loading of ex vivo myofiber bundles was visualized utilizing mT/mG double-fluorescent Cre-reporter mouse and multiphoton microscopy. MuSCs were subjected to 1 h pulsating fluid shear stress (PFSS) with a peak shear stress rate of 6.5 Pa/s. After PFSS treatment, nitric oxide, messenger RNA (mRNA) expression levels of genes involved in regulation of MuSC proliferation and differentiation, ERK 1/2, p38, and AKT activation were determined. Ex vivo stretching of extensor digitorum longus and soleus myofiber bundles caused compression as well as tensile and shear deformation of MuSCs in their niche. MuSCs responded to PFSS in vitro with increased nitric oxide production and an upward trend in iNOS mRNA levels. PFSS enhanced gene expression of c-Fos, Cdk4, and IL-6, whereas expression of Wnt1, MyoD, Myog, Wnt5a, COX2, Rspo1, Vangl2, Wnt10b, and MGF remained unchanged. ERK 1/2 and p38 MAPK signaling were also upregulated after PFSS treatment. We conclude that MuSCs in their native niche are subjected to force-induced deformations due to myofiber stretch-shortening. Moreover, MuSCs are mechanoresponsive, as evidenced by PFSS-mediated expression of factors by MuSCs known to promote proliferation.

Epigenetic silencing of GCH1promotes hepatocellular carcinoma growth by activating superoxide anion-mediated ASK1/p38 signaling via inhibiting tetrahydrobiopterin de novo biosynthesis

Metabolic reprogramming is a hallmark of cancer, including hepatocellular carcinoma (HCC). However, its role in HCC remains to be elucidated. Herein, we identified GTP cyclohydrolase 1 (GCH1), the first rate-limiting enzyme in tetrahydrobiopterin (BH4) de novo biosynthesis, as a novel metabolic regulator of HCC. GCH1 was frequently down-regulated in HCC tissues and cell lines by promoter methylation. Low GCH1 expression was associated with larger tumor size, increased tumor number, and worse prognosis in two independent cohorts of HCC patients. Functionally, GCH1 silencing promoted HCC growth in vitro and in vivo, while GCH1 overexpression exerted an opposite effect. The metabolite BH4 inhibited HCC growth in vitro and in vivo. GCH1 silencing exerted its growth-promoting effect through directly inhibiting BH4 de novo biosynthesis. Mechanistically, GCH1 silencing activated ASK1/p38 signaling; pharmacological or genetic inhibition of ASK1 or p38 abolished GCH1 silencing-induced growth-promoting effect. Further mechanistic studies found that GCH1 silencing-induced BH4 reduction resulted in an increase of intracellular superoxide anion levels in a dose-dependent manner, which mediated the activation of ASK1/p38 signaling. Collectively, our study reveals that epigenetic silencing of GCH1 promotes HCC growth by activating superoxide anion-mediated ASK1/p38 signaling via inhibiting BH4 de novo biosynthesis, suggesting that targeting GCH1/BH4 pathway may be a promising therapeutic strategy to combat HCC.

The Role of Non-Structural Protein NSs in the Pathogenesis of Severe Fever with Thrombocytopenia Syndrome

Viral non-structural proteins, such as NSs of the newly emerging severe fever with thrombocytopenia syndrome virus, are well established virulence factors, mediating viral pathogenesis and disease progression through various mechanisms. NSs has been described as a potent interferon antagonist and NF-κB agonist, two divergent signaling pathways in many immune responses upon a viral encounter. In this review, we highlight the many mechanisms used by NSs on the host that promote viral replication and hyper-inflammation. Understanding these host-pathogen interactions is crucial for antiviral therapy development.

Identification of 4'-Demethyltangeretin as a Major Urinary Metabolite of Tangeretin in Mice and Its Anti-inflammatory Activities

The present study showed that oral administration of tangeretin (TAN) in mice resulted in the production of 4'-demethyltangeretin (4DT) as a major urinary metabolite. The anti-inflammatory efficacy of TAN and 4DT was determined in RAW 264.7 macrophages stimulated by lipopolysaccharides (LPS). 4DT produced considerably stronger inhibition on the overproduction of prostaglandin E₂ and nitric oxide than TAN did at the same concentrations. Western blot and quantitative polymerase chain reaction analyses indicated that 4DT exerted more potent suppressive activity on the over-expression of interleukin-1β, inducible nitric oxide synthase, and cyclooxygenase-2 than TAN. Treatments with TAN and 4DT diminished LPS-stimulated nuclear factor κB (NFκB) translocation via suppressing the degradation of inhibitor κB (IκBα). Furthermore, both compounds attenuated mitogen-activated protein kinases (MAPKs) and Akt signaling upregulated by LPS. Overall, our findings showed that TAN and 4DT inhibited the LPS-stimulated inflammatory response in macrophages by suppressing Akt/MAPKs/NFκB proinflammatory pathways, while 4DT showed more potent activity than TAN, its parent compound.

Active p38α causes macrovesicular fatty liver in mice

One third of the western population suffers from nonalcoholic fatty liver disease (NAFLD), which may ultimately develop into hepatocellular carcinoma (HCC). The molecular event(s) that triggers the disease are not clear. Current understanding, known as the multiple hits model, suggests that NAFLD is a result of diverse events at several tissues (e.g., liver, adipose tissues, and intestine) combined with changes in metabolism and microbiome. In contrast to this prevailing concept, we report that fatty liver could be triggered by a single mutated protein expressed only in the liver. We established a transgenic system that allows temporally controlled activation of the MAP kinase p38α in a tissue-specific manner by induced expression of intrinsically active p38α allele. Here we checked the effect of exclusive activation in the liver. Unexpectedly, induction of p38α alone was sufficient to cause macrovesicular fatty liver. Animals did not become overweight, showing that fatty liver can be imposed solely by a genetic modification in liver per se and can be separated from obesity. Active p38α-induced fatty liver is associated with up-regulation of MUC13, CIDEA, PPARγ, ATF3, and c-jun mRNAs, which are up-regulated in human HCC. Shutting off expression of the p38α mutant resulted in reversal of symptoms. The findings suggest that p38α plays a direct causative role in fatty liver diseases and perhaps in other chronic inflammatory diseases. As p38α activity was induced by point mutations, it could be considered a proto-inflammatory gene (proto-inflammagene).

CD133 prevents colon cancer cell death induced by serum deprivation through activation of Akt-mediated protein synthesis and inhibition of apoptosis

During the early phase of tumorigenesis, primary malignant cells survive within a low nutrition environment caused by a poorly organized vascular system. Here, we sought to determine the functional significance of CD133 in the survival of cancer cells under nutrient‐poor conditions. Knockdown and overexpression experiments demonstrated that CD133 suppresses colon cancer cell death induced by serum deprivation through activation of Akt‐mediated anti‐apoptosis and protein synthesis pathways. Furthermore, serum deprivation increased the amount of endogenous CD133 protein, which was regulated at least in part by phosphoinositide 3‐kinase. Thus, it is highly likely that CD133 contributes to the acquisition/maintenance of the resistance to stress arising from nutrient deficiency in early avascular tumor tissues.

The p38MAPK-MK2 Signaling Axis as a Critical Link Between Inflammation and Synaptic Transmission

p38 is a mitogen-activated protein kinase (MAPK), that responds primarily to stress stimuli. p38 has a number of targets for phosphorylation, including MAPK-activated protein kinase 2 (MK2). MK2 primarily functions as a master regulator of RNA-binding proteins, indirectly controlling gene expression at the level of translation. The role of MK2 in regulating the synthesis of pro-inflammatory cytokines downstream of inflammation and cellular stress is well-described. A significant amount of evidence, however, now points to a role for the p38^MAPK-MK2 signaling axis in mediating synaptic plasticity through control of AMPA receptor trafficking and the morphology of dendritic spines. These processes are mediated through control of cytoskeletal dynamics via the activation of cofilin-1 and possibly control of the expression of Arc/Arg3.1. There is evidence that MK2 is necessary for group I metabotropic glutamate receptors long-term depression (mGluR-LTD). Disruption of this signaling may play an important role in mediating cognitive dysfunction in neurological disorders such as fragile X syndrome and Alzheimer’s disease. To date, the role of neuronal MK2 mediating synaptic plasticity in response to inflammatory stimuli has not yet been investigated. In immune cells, it is clear that MK2 is phosphorylated following activation of a broad range of cell surface receptors for cytokines and other inflammatory mediators. We propose that neuronal MK2 may be an important player in the link between inflammatory states and dysregulation of synaptic plasticity underlying cognitive functions. Finally, we discuss the potential of the p38^MAPK-MK2 signaling axis as target for therapeutic intervention in a number of neurological disorders.

The Synaptic Dysregulation in Adolescent Rats Exposed to Maternal Immune Activation

Maternal immune activation (MIA) is a risk factor for neurodevelopmental disorders in offspring, but the pathomechanism is largely unknown. The aim of our study was to analyse the molecular mechanisms contributing to synaptic alterations in hippocampi of adolescent rats exposed prenatally to MIA. MIA was evoked in pregnant female rats by i.p. administration of lipopolysaccharide at gestation day 9.5. Hippocampi of offspring (52-53-days-old rats) were analysed using transmission electron microscopy (TEM), qPCR and Western blotting. Moreover, mitochondrial membrane potential, activity of respiratory complexes, and changes in glutathione system were measured. It was found that MIA induced changes in hippocampi morphology, especially in the ultrastructure of synapses, including synaptic mitochondria, which were accompanied by impairment of mitochondrial electron transport chain and decreased mitochondrial membrane potential. These phenomena were in agreement with increased generation of reactive oxygen species, which was evidenced by a decreased reduced/oxidised glutathione ratio and an increased level of dichlorofluorescein (DCF) oxidation. Activation of cyclin-dependent kinase 5, and phosphorylation of glycogen synthase kinase 3β on Ser9 occurred, leading to its inhibition and, accordingly, to hypophosphorylation of microtubule associated protein tau (MAPT). Abnormal phosphorylation and dysfunction of MAPT, the manager of the neuronal cytoskeleton, harmonised with changes in synaptic proteins. In conclusion, this is the first study demonstrating widespread synaptic changes in hippocampi of adolescent offspring prenatally exposed to MIA.

Anti-Inflammatory Action and Mechanisms of Resveratrol

Resveratrol (3,4',5-trihy- droxystilbene), a natural phytoalexin polyphenol, exhibits anti-oxidant, anti-inflammatory, and anti-carcinogenic properties. This phytoalexin is well-absorbed and rapidly and extensively metabolized in the body. Inflammation is an adaptive response, which could be triggered by various danger signals, such as invasion by microorganisms or tissue injury. In this review, the anti-inflammatory activity and the mechanism of resveratrol modulates the inflammatory response are examined. Multiple experimental studies that illustrate regulatory mechanisms and the immunomodulatory function of resveratrol both in vivo and in vitro. The data acquired from those studies are discussed.

Intra-Cellular Calcium Signaling Pathways (PKC, RAS/RAF/MAPK, PI3K) in Lamina Cribrosa Cells in Glaucoma

The lamina cribrosa (LC) is a key site of fibrotic damage in glaucomatous optic neuropathy and the precise mechanisms of LC change remain unclear. Elevated Ca²⁺ is a major driver of fibrosis, and therefore intracellular Ca²⁺ signaling pathways are relevant glaucoma-related mechanisms that need to be studied. Protein kinase C (PKC), mitogen-activated MAPK kinases (p38 and p42/44-MAPK), and the PI3K/mTOR axis are key Ca²⁺ signal transducers in fibrosis and we therefore investigated their expression and activity in normal and glaucoma cultured LC cells. We show, using Western immune-blotting, that hyposmotic-induced cellular swelling activates PKCα, p42/p44, and p38 MAPKs, the activity is transient and biphasic as it peaks between 2 min and 10 min. The expression and activity of PKCα, p38 and p42/p44-MAPKs are significantly (p < 0.05) increased in glaucoma LC cells at basal level, and at different time-points after hyposmotic stretch. We also found elevated mRNA expression of mRNA expression of PI3K, IP3R, mTOR, and CaMKII in glaucoma LC cells. This study has identified abnormalities in multiple calcium signaling pathways (PKCα, MAPK, PI3K) in glaucoma LC cells, which might have significant functional and therapeutic implications in optic nerve head (ONH) fibrosis and cupping in glaucoma.

Wnt signaling in breast cancer: biological mechanisms, challenges and opportunities

Wnt signaling is a highly conserved signaling pathway that plays a critical role in controlling embryonic and organ development, as well as cancer progression. Genome-wide sequencing and gene expression profile analyses have demonstrated that Wnt signaling is involved mainly in the processes of breast cancer proliferation and metastasis. The most recent studies have indicated that Wnt signaling is also crucial in breast cancer immune microenvironment regulation, stemness maintenance, therapeutic resistance, phenotype shaping, etc. Wnt/β-Catenin, Wnt-planar cell polarity (PCP), and Wnt-Ca2+ signaling are three well-established Wnt signaling pathways that share overlapping components and play different roles in breast cancer progression. In this review, we summarize the main findings concerning the relationship between Wnt signaling and breast cancer and provide an overview of existing mechanisms, challenges, and potential opportunities for advancing the therapy and diagnosis of breast cancer.

CDK4/6 and MAPK-Crosstalk as Opportunity for Cancer Treatment

Despite the development of targeted therapies and novel inhibitors, cancer remains an undefeated disease. Resistance mechanisms arise quickly and alternative treatment options are urgently required, which may be partially met by drug combinations. Protein kinases as signaling switchboards are frequently deregulated in cancer and signify vulnerable nodes and potential therapeutic targets. We here focus on the cell cycle kinase CDK6 and on the MAPK pathway and on their interplay. We also provide an overview on clinical studies examining the effects of combinational treatments currently explored for several cancer types.

Accumulation of tissue factor in endothelial cells promotes cellular apoptosis through over-activation of Src1 and involves β1-integrin signalling

Accumulation of tissue factor (TF) within cells leads to cellular apoptosis mediated through p38 and p53 pathways. In this study, the involvement of Src1 in the induction of TF-mediated cell apoptosis, and the mechanisms of Src1 activation were investigated. Human coronary artery endothelial cell (HCAEC) were transfected with plasmids to express the wild-type TF (TF_Wt-tGFP), or a mutant (Ser253 → Ala) which is incapable of being released from cells (TF_Ala253-tGFP). The cells were then activated with PAR2-agonist peptide (SLIGKV-NH) and the phosphorylation of Src and Rac, and also the kinase activity of Src were assessed. Transfected cells were also pre-incubated with pp60c Src inhibitor, FAK inhibitor-14, or a blocking anti-β1-integrin antibody prior to activation and the phosphorylation of p38 as well as cellular apoptosis was examined. Finally, cells were co-transfected with the plasmids, together with a Src1-specific siRNA, activated as above and the cellular apoptosis measured. Activation of PAR2 lead to the phosphorylation of Src1 and Rac1 proteins at 60 min regardless of TF expression. Moreover, Src phosphorylation and kinase activity was prolonged up to 100 min in the presence of TF, with a significantly higher magnitude when the non-releasable TF_Ala253-tGFP was expressed in HCAEC. Inhibition of Src with pp60c, or suppression of Src1 expression in cells, reduced p38 phosphorylation and prevented cellular apoptosis. In contrast, inhibition of FAK had no significant influence on Src kinase activity or cellular apoptosis. Finally, pre-incubation of cells with an inhibitory anti-β1-integrin antibody reduced both Src1 activation and cellular apoptosis. Our data show for the first time that the over-activation of Src1 is a mediator of TF-induced cellular apoptosis in endothelial cells through a mechanism that is dependent on its interaction with β1-integrin.

History and Domestication of Saccharomyces cerevisiae in Bread Baking

The yeast Saccharomyces cerevisiae has been instrumental in the fermentation of foods and beverages for millennia. In addition to fermentations like wine, beer, cider, sake, and bread, S. cerevisiae has been isolated from environments ranging from soil and trees, to human clinical isolates. Each of these environments has unique selection pressures that S. cerevisiae must adapt to. Bread dough, for example, requires S. cerevisiae to efficiently utilize the complex sugar maltose; tolerate osmotic stress due to the semi-solid state of dough, high salt, and high sugar content of some doughs; withstand various processing conditions, including freezing and drying; and produce desirable aromas and flavors. In this review, we explore the history of bread that gave rise to modern commercial baking yeast, and the genetic and genomic changes that accompanied this. We illustrate the genetic and phenotypic variation that has been documented in baking strains and wild strains, and how this variation might be used for baking strain improvement. While we continue to improve our understanding of how baking strains have adapted to bread dough, we conclude by highlighting some of the remaining open questions in the field.

The involvement of toll-like receptors 2 and 4 in human platelet signalling pathways

In addition to haemostasis, platelets play an essential role in mechanisms of inflammation and in immunological reactions. Platelets express various toll-like receptors (TLR) on their surface, among them TLR2 and TLR4, which are important for the recognition of bacterial patterns. This study compared TLR2- and TLR4-dependent platelet signalling and their effect on platelet function. Platelet-rich-plasma and washed platelets were prepared from peripheral blood samples of healthy donors. Pam3CSK4 or LPS (lipopolysaccharides from Escherichia coli) were used for stimulation of TLR2 and TLR4. Intracellular signalling pathways were investigated by Western blot. TLR2- and TLR4-mediated specific transcription factor DNA binding activity was measured by the nuclear factor kappa B (NFκB) transcription factor assay kit. Platelet adhesion and glycoprotein Ib function were assessed by immunofluorescence staining and analysis of ristocetin-induced agglutination. Both, Pam3CSK4 and LPS were able to induce NFκB-mediated and classical activating platelet signalling with a higher stimulatory capacity of TLR2. In addition, TLR2 and TLR4 activation led to a similar activation of inhibitory pathways. In contrast to TLR2, stimulation of TLR4 resulted in decreased Akt/protein kinase B phosphorylation conditioned by enhanced protein phosphatase 2A activity. TLR4-mediated signalling induced platelet adhesion and facilitated ristocetin-induced platelet agglutination. In conclusion, Pam3CSK4 directly induces aggregation via classical activation cascades, whereas LPS enhances platelet adhesion and glycoprotein receptor Ib-dependent platelet agglutination.

Virus-induced p38 MAPK activation facilitates viral infection

Rationale: Many viral infections are known to activate the p38 mitogen-activated protein kinase (MAPK) signaling pathway. However, the role of p38 activation in viral infection and the underlying mechanism remain unclear. The role of virus-hijacked p38 MAPK activation in viral infection was investigated in this study.

Methods: The correlation of hepatitis C virus (HCV) infection and p38 activation was studied in patient tissues and primary human hepatocytes (PHHs) by immunohistochemistry and western blotting. Coimmunoprecipitation, GST pulldown and confocal microscopy were used to investigate the interaction of p38α and the HCV core protein. In vitro kinase assays and mass spectrometry were used to analyze the phosphorylation of the HCV core protein. Plaque assays, quantitative real time PCR (qRT-PCR), western blotting, siRNA and CRISPR/Cas9 were used to determine the effect of p38 activation on viral replication.

Results: HCV infection was associated with p38 activation in clinical samples. HCV infection increased p38 phosphorylation by triggering the interaction of p38α and TGF-β activated kinase 1 (MAP3K7) binding protein 1 (TAB1). TAB1-mediated p38α activation facilitated HCV replication, and pharmaceutical inhibition of p38α activation by SB203580 suppressed HCV infection at the viral assembly step. Activated p38α interacted with the N-terminal region of the HCV core protein and subsequently phosphorylated the HCV core protein, which promoted HCV core protein oligomerization, an essential step for viral assembly. As expected, SB203580 or the HCV core protein N-terminal peptide (CN-peptide) disrupted the p38α-HCV core protein interaction, efficiently impaired HCV assembly and impeded normal HCV replication in both cultured cells and primary human hepatocytes. Similarly, severe fever with thrombocytopenia syndrome virus (SFTSV), herpes simplex virus type 1 (HSV-1) or severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection also activated p38 MAPK. Most importantly, pharmacological blockage of p38 activation by SB203580 effectively inhibited SFTSV, HSV-1 and SARS-CoV-2.

Conclusion: Our study shows that virus-hijacked p38 activation is a key event for viral replication and that pharmacological blockage of p38 activation is an antiviral strategy.

Functions of p38 MAP Kinases in the Central Nervous System

Mitogen-activated protein (MAP) kinases are a central component in signaling networks in a multitude of mammalian cell types. This review covers recent advances on specific functions of p38 MAP kinases in cells of the central nervous system. Unique and specific functions of the four mammalian p38 kinases are found in all major cell types in the brain. Mechanisms of p38 activation and downstream phosphorylation substrates in these different contexts are outlined and how they contribute to functions of p38 in physiological and under disease conditions. Results in different model organisms demonstrated that p38 kinases are involved in cognitive functions, including functions related to anxiety, addiction behavior, neurotoxicity, neurodegeneration, and decision making. Finally, the role of p38 kinases in psychiatric and neurological conditions and the current progress on therapeutic inhibitors targeting p38 kinases are covered and implicate p38 kinases in a multitude of CNS-related physiological and disease states.

TNF-α controls Lipocalin-2 expression in PC-3 prostate cancer cells

Prostate cancer (PCa) is one of the most common and deadly cancers in men worldwide. The surrounding tumor microenvironment (TME) is important in tumor progression, as cytokines and soluble mediators including tumor necrosis factor (TNF-α) or lipocalin-2 (LCN2) can influence tumor growth and formation of metastasis. The exact mechanisms on how these pleiotropic factors affect PCa are still unknown. In this study, we showed for the first time that LCN2 mRNA and protein expression are strongly inducible by TNF-α in the highly metastatic human PCa cell line PC-3. In addition, we observed higher levels of secreted LCN2 in cell culture medium of TNF-α-treated PC-3 cells. We found that different signaling pathways such as p38, NF-κB or JNK were activated shortly after TNF-α treatment. Moreover, the mRNA levels of IL-1β and IL-8 were also significantly increased after 24 h stimulation. Mechanistically, the NF-κB pathway and the JNK signaling axis are directly responsible for LCN2 upregulation. This was shown by the fact that pretreatment with the JNK inhibitors SP600125 or JNK-IN-8 strongly downregulated phosphorylation of c-Jun protein and markedly reduced TNF-α-mediated LCN2 upregulation in PC-3 cells. Likewise, the NF-κB inhibitor QNZ was able to repress TNF-α-induced LCN2 expression in PC-3 cells. Taking into consideration that LCN2 has been described as a tumor promoting factor in PCa, our results indicate that JNK regulates LCN2 expression and unmasks the JNK signaling axis as a possible therapeutic target for patients with PCa.

MAP Kinase-Mediated Activation of RSK1 and MK2 Substrate Kinases

Mitogen-activated protein kinases (MAPKs) control essential eukaryotic signaling pathways. While much has been learned about MAPK activation, much less is known about substrate recruitment and specificity. MAPK substrates may be other kinases that are crucial to promote a further diversification of the signaling outcomes. Here, we used a variety of molecular and cellular tools to investigate the recruitment of two substrate kinases, RSK1 and MK2, to three MAPKs (ERK2, p38α, and ERK5). Unexpectedly, we identified that kinase heterodimers form structurally and functionally distinct complexes depending on the activation state of the MAPK. These may be incompatible with downstream signaling, but naturally they may also form structures that are compatible with the phosphorylation of the downstream kinase at the activation loop, or alternatively at other allosteric sites. Furthermore, we show that small-molecule inhibitors may affect the quaternary arrangement of kinase heterodimers and thus influence downstream signaling in a specific manner.

An overview of mammalian p38 mitogen-activated protein kinases, central regulators of cell stress and receptor signaling

The p38 family is a highly evolutionarily conserved group of mitogen-activated protein kinases (MAPKs) that is involved in and helps co-ordinate cellular responses to nearly all stressful stimuli. This review provides a succinct summary of multiple aspects of the biology, role, and substrates of the mammalian family of p38 kinases. Since p38 activity is implicated in inflammatory and other diseases, we also discuss the clinical implications and pharmaceutical approaches to inhibit p38.

Comparison of signaling profiles in the low dose range following low and high LET radiation

During space travel astronauts will be exposed to a very low, mixed field of radiation containing different high LET particles of varying energies, over an extended period. Thus, defining how human cells respond to these complex low dose exposures is important in ascertaining risk. In the current study, we have chosen to investigate how low doses of three different ion's at various energies uniquely change the kinetics of three different phospho-proteins. A normal hTERT immortalized fibroblast cell line, 82-6, was exposed to a range of lower doses (0.05-0.5 Gy) of radiation of different qualities and energies (Si 1000 MeV/u, Si 300 MeV/u, Si 173 MeV/u, Si 93 MeV/u, Fe 1000 MeV/u, Fe 600 MeV/u, Fe 300 MeV/u, Ti 300 MeV/u, Ti 326 MeV/u, Ti 386 MeV/u), covering a wide span of LET's. Exposed samples were analyzed for the average intensity of signal as a fold over the geometric mean level of the sham controls. Three phospho-proteins known to localize to DNA DSBs following radiation (γH2AX, pATF2, pSMC1) were studied. The kinetics of their response was quantified by flow cytometery at 2 and 24 h post exposure. These studies reveal unique kinetic patterns based on the ion, energy, fluence and time following exposure. In addition, γH2AX phosphorylation patterns are uniquely different from phospho-proteins known to be primarily phosphorylated by ATM. This latter finding suggests that the activating kinase(s), or the phosphatases deactivating these proteins, exhibit differences in their response to various radiation qualities and/ or doses of exposure. Further studies will be needed to better define what the differing kinetics for the kinases activated by the unique radiation qualities plays in the biological effectiveness of the particle.

Refocusing the Brain: New Approaches in Neuroprotection Against Ischemic Injury

A new era for neuroprotective strategies is emerging in ischemia/reperfusion. This has forced to review the studies existing to date based in neuroprotection against oxidative stress, which have undoubtedly contributed to clarify the brain endogenous mechanisms, as well as to identify possible therapeutic targets or biomarkers in stroke and other neurological diseases. The efficacy of exogenous administration of neuroprotective compounds has been shown in different studies so far. However, something must be missing to get these treatments successfully applied in the clinical environment. Here, the mechanisms involved in neuronal protection against physiological level of ROS and the main neuroprotective signaling pathways induced by excitotoxic and ischemic stimuli are reviewed. Also, the endogenous ischemic tolerance in terms of brain self-protection mechanisms against subsequent cerebral ischemia is revisited to highlight how the preconditioning has emerged as a powerful tool to understand these phenomena. A better understanding of endogenous defense against exacerbated ROS and metabolism in nervous cells will therefore aid to design pharmacological antioxidants targeted specifically against oxidative damage induced by ischemic injury, but also might be very valuable for translational medicine.

Inorganic Biomaterials for Regenerative Medicine

Regenerative medicine leverages the innate potential of the human body to efficiently repair and regenerate damaged tissues using engineered biomaterials. By designing responsive biomaterials with the appropriate biophysical and biochemical characteristics, cellular response can be modulated to direct tissue healing. Recently, inorganic biomaterials have been shown to regulate cellular responses including cell-cell and cell-matrix interactions. Moreover, ions released from these mineral-based biomaterials play a vital role in defining cell identity, as well as driving tissue-specific functions. The intrinsic properties of inorganic biomaterials, such as the release of bioactive ions (e.g., Ca, Mg, Sr, Si, B, Fe, Cu, Zn, Cr, Co, Mo, Mn, Au, Ag, V, Eu, and La), can be leveraged to induce phenotypic changes in cells or modulate the immune microenvironment to direct tissue healing and regeneration. Biophysical characteristics of biomaterials, such as topography, charge, size, electrostatic interactions, and stiffness can be modulated by addition of inorganic micro- and nanoparticles to polymeric networks have also been shown to play an important role in their biological response. In this Review, we discuss the recent emergence of inorganic biomaterials to harness the innate regenerative potential of the body. Specifically, we will discuss various biophysical or biochemical effects of inorganic-based materials in directing cellular response for regenerative medicine applications.

Therapeutic potentials and modulatory mechanisms of fatty acids in bone

Bone metabolism is a lifelong process that includes bone formation and resorption. Osteoblasts and osteoclasts are the predominant cell types associated with bone metabolism, which is facilitated by other cells such as bone marrow mesenchymal stem cells (BMMSCs), osteocytes and chondrocytes. As an important component in our daily diet, fatty acids are mainly categorized as long-chain fatty acids including polyunsaturated fatty acids (LCPUFAs), monounsaturated fatty acids (LCMUFAs), saturated fatty acids (LCSFAs), medium-/short-chain fatty acids (MCFAs/SCFAs) as well as their metabolites. Fatty acids are closely associated with bone metabolism and associated bone disorders. In this review, we summarized the important roles and potential therapeutic implications of fatty acids in multiple bone disorders, reviewed the diverse range of critical effects displayed by fatty acids on bone metabolism, and elucidated their modulatory roles and mechanisms on specific bone cell types. The evidence supporting close implications of fatty acids in bone metabolism and disorders suggests fatty acids as potential therapeutic and nutritional agents for the treatment and prevention of metabolic bone diseases.

Inhibitory Activity of a Scorpion Defensin BmKDfsin3 against Hepatitis C Virus

Hepatitis C virus (HCV) infection is a major worldwide health problem which can cause chronic hepatitis, liver fibrosis and hepatocellular carcinoma (HCC). There is still no vaccine to prevent HCV infection. Currently, the clinical treatment of HCV infection mainly relies on the use of direct-acting antivirals (DAAs) which are expensive and have side effects. Here, BmKDfsin3, a scorpion defensin from the venom of Mesobuthus martensii Karsch, is found to dose-dependently inhibit HCV infection at noncytotoxic concentrations and affect viral attachment and post-entry in HCV life cycle. Further experimental results show that BmKDfsin3 not only suppresses p38 mitogen-activated protein kinase (MAPK) activation of HCV-infected Huh7.5.1 cells, but also inhibits p38 activation of Huh7.5.1 cells stimulated by tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) or lipopolysaccharide (LPS). BmKDfsin3 is also revealed to enter into cells. Using an upstream MyD88 dimerization inhibitor ST2345 or kinase IRAK-1/4 inhibitor I, the inhibition of p38 activation represses HCV replication in vitro. Taken together, a scorpion defensin BmKDfsin3 inhibits HCV replication, related to regulated p38 MAPK activation.

MAP kinase phosphatase-1, a gatekeeper of the acute innate immune response

Mitogen-activated protein kinase (MAPK)^§ cascades are crucial signaling pathways in the regulation of the host immune response to infection. MAPK phosphatase (MKP)-1, an archetypal member of the MKP family, plays a pivotal role in the down-regulation of p38 and JNK. Studies using cultured macrophages have demonstrated a pivotal role of MKP-1 in the restraint of the biosynthesis of both pro-inflammatory and anti-inflammatory cytokines as well as chemokines. Using MKP-1 knockout mice, several groups have not only confirmed the critical importance of MKP-1 in the regulation of the cytokine synthesis in vivo during the acute host response to bacterial infections, but also revealed novel functions of MKP-1 in maintaining bactericidal functions and host metabolic activities. RNA-seq analyses on livers of septic mice infected with E. coli have revealed that MKP-1 deficiency caused substantial perturbation in the expression of over 5000 genes, an impressive >20% of the entire murine genome. Among the genes whose expression are dramatically affected by MKP-1 deficiency are those encoding metabolic regulators and acute phase response proteins. These studies demonstrate that MKP-1 is an essential gate-keeper of the acute innate immune response, facilitating pathogen killing and regulating the metabolic response during pathogenic infection. In this review article, we will summarize the studies on the function of MKP-1 during acute innate immune response in the regulation of inflammation, metabolism, and acute phase response. We will also discuss the role of MKP-1 in the actions of numerous immunomodulatory agents.

Genome-wide identification of JNK and p38 gene family in Ctenopharyngodon idella and their expression profiles in response to bacterial challenge

c-Jun N-terminal kinases (JNKs) and p38s are central components of signal transduction pathways, which are stimulated mainly by environmental stress and inflammatory cytokines. Manipulation of JNK and p38 dependent immune responses either boosts or subdues immune responses to infectious diseases or inflammatory disorders. In this study, we analyzed the whole-genome database of the grass carp and identified 4 JNK and 6 p38 genes. JNK and p38 genes of grass carp were distributed in 7 out of 24 chromosomes. All JNK and p38 proteins contained characteristic dual-phosphorylation site. The JNKs contain a specific dual-phosphorylation consensus ((Thr-Pro-Tyr) that is different from that of the p38 proteins (Thr-Gly-Tyr). Deduced gene secondary structure analyses as well as the syntenic analyses further supported their annotation and orthologs. Results of tissue distribution detection revealed that JNK and p38 genes exhibited lower expression in health grass carp. The mRNA expression levels of JNK and p38 genes were significantly up-regulated in tissues and CIK cells after bacterial infection, indicating their potential roles in bacterial-regulated immune responses. These findings in our study will facilitate the further evolutionary characterization of JNK and p38 genes in teleost species and provide a theoretical basis for their functional study.

Impairment of Membrane Repolarization Accompanies Axon Transport Deficits in Glaucoma

Glaucoma is a leading cause of blindness worldwide, resulting from degeneration of retinal ganglion cells (RGCs), which form the optic nerve. In glaucoma, axon transport deficits appear to precede structural degeneration of RGC axons. The period of time between the onset of axon transport deficits and the structural degeneration of RGC axons may represent a therapeutic window for the prevention of irreversible vision loss. However, it is unclear how deficits in axon transport relate to the electrophysiological capacity of RGCs to produce and maintain firing frequencies that encode visual stimuli. Here, we examined the electrophysiological signature of individual RGCs in glaucomatous retina with respect to axon transport facility. Utilizing the Microbead Occlusion Model of murine ocular hypertension, we performed electrophysiological recordings of RGCs with and without deficits in anterograde axon transport. We found that RGCs with deficits in axon transport have a reduced ability to maintain spiking frequency that arises from elongation of the repolarization phase of the action potential. This repolarization phenotype arises from reduced cation flux and K+ dyshomeostasis that accompanies pressure-induced decreases in Na/K-ATPase expression and activity. In vitro studies with purified RGCs indicate that elevated pressure induces early internalization of Na/K-ATPase that, when reversed, stabilizes cation flux and prevents K+ dyshomeostasis. Furthermore, pharmacological inhibition of the Na/K-ATPase is sufficient to replicate pressure-induced cation influx and repolarization phase phenotypes in healthy RGCs. These studies suggest that deficits in axon transport also likely reflect impaired electrophysiological function of RGCs. Our findings further identify a failure to maintain electrochemical gradients and cation dyshomeostasis as an early phenotype of glaucomatous pathology in RGCs that may have significant bearing on efforts to restore RGC health in diseased retina.

Regulation of c-Jun NH2-Terminal Kinase for Islet Transplantation

Islet transplantation has been demonstrated to provide superior glycemic control with reduced glucose lability and hypoglycemic events compared with standard insulin therapy. However, the insulin independence rate after islet transplantation from one donor pancreas has remained low. The low frequency of islet grafting is dependent on poor islet recovery from donors and early islet loss during the first hours following grafting. The reduction in islet mass during pancreas preservation, islet isolation, and islet transplantation leads to β-cell death by apoptosis and the prerecruitment of intracellular death signaling pathways, such as c-Jun NH₂-terminal kinase (JNK), which is one of the stress groups of mitogen-activated protein kinases (MAPKs). In this review, we show some of the most recent contributions to the advancement of knowledge of the JNK pathway and several possibilities for the treatment of diabetes using JNK inhibitors.

Keratins regulate Hsp70-mediated nuclear localization of p38 mitogen-activated protein kinase

Intermediate filament protein keratin 8 (K8) binds to heat shock protein 70 (Hsp70) and p38 MAPK, and is phosphorylated at Ser74 by p38α (MAPK14, hereafter p38). However, a p38 binding site on K8 and the molecular mechanism of K8-p38 interaction related to Hsp70 are unknown. Here, we identify a p38 docking site on K8 (Arg148/149 and Leu159/161) that is highly conserved in other intermediate filaments. A docking-deficient K8 mutation caused increased p38-Hsp70 interaction and enhanced p38 nuclear localization, indicating that the p38 dissociated from mutant K8 makes a complex with Hsp70, which is known as a potential chaperone for p38 nuclear translocation. Comparison of p38 MAPK binding with keratin variants associated with liver disease showed that the K18 I150V variant dramatically reduced binding with p38, which is similar to the effect of the p38 docking-deficient mutation on K8. Because the p38 docking site on K8 (Arg148/149 and Leu159/161) and the K18 Ile150 residue are closely localized in the parallel K8/K18 heterodimer, the K18 I150V mutation might interfere with K8-p38 interaction. These findings show that keratins, functioning as cytoplasmic anchors for p38, modulate p38 nuclear localization and thereby might affect a number of p38-mediated signal transduction pathways.

In Situ Single-Cell Western Blot on Adherent Cell Culture

Integrating 2D culture of adherent mammalian cells with single-cell western blotting (in situ scWB) uses microfluidic design to eliminate the requirement for trypsin release of cells to suspension, prior to single-cell isolation and protein analysis. To assay HeLa cells from an attached starting state, we culture adherent cells in fibronectin-functionalized microwells formed in a thin layer of polyacrylamide gel. To integrate the culture, lysis, and assay workflow, we introduce a one-step copolymerization process that creates protein-decorated microwells. After single-cell culture, we lyse each cell in the microwell and perform western blotting on each resultant lysate. We observe cell spreading after overnight microwell-based culture. scWB reports increased phosphorylation of MAP kinases (ERK1/2, p38) under hypertonic conditions. We validate the in situ scWB with slab-gel western blot, while revealing cell-to-cell heterogeneity in stress responses.