Vacuoles and peroxisomes are involved in Aspergillus fumigatus gliotoxin production and self-protection

Aspergillus fumigatus is a saprophytic fungus that can cause a variety of human diseases known as aspergillosis. Mycotoxin gliotoxin (GT) production is important for its virulence and must be tightly regulated to avoid excess production and toxicity to the fungus. GT self-protection by GliT oxidoreductase and GtmA methyltransferase activities is related to the subcellular localization of these enzymes and how GT can be sequestered from the cytoplasm to avoid increased cell damage. Here, we show that GliT:GFP and GtmA:GFP are localized in the cytoplasm and in vacuoles during GT production. Peroxisomes are also required for proper GT production and self-defense. The Mitogen-Activated Protein (MAP) kinase MpkA is essential for GT production and self-protection, interacts physically with GliT and GtmA and it is necessary for their regulation and subsequent presence in the vacuoles. Our work emphasizes the importance of dynamic compartmentalization of cellular events for GT production and self-defense.

microRNA-203 functions as a natural Ras inhibitor in hepatocellular carcinoma

microRNA-203 (miR203) plays an important role in the formation and development of multiple types of cancers. However, its role in hepatic carcinogenesis has not been well studied. Mitogen-activated protein kinase signaling is known to be activated in hepatocellular carcinoma (HCC), but there is a lack of effective drugs targeting this pathway for HCC treatment. In this study, we investigated the role of miR203 in HCC and the underlying mechanism. We found that miR203 was significantly downregulated in HCC cell lines and patient tissues compared with a hepatocyte cell line (L02) or normal liver tissues. Restoration of miR203 inhibited HCC cell growth and induced cell cycle arrest and apoptosis. In primary and xenograft HCC mouse models, miR203 also significantly blocked HCC growth. Bioinformatic analysis indicated that miR203 directly binds to the 3'UTR of NRas mRNA, resulting in decreased expression of NRas and inactivation of mitogen-activated protein kinase (MAPK) signaling. Activation of MAPK signaling by ectopic NRas expression rescued the cell proliferation blocked by miR203. Together, our findings illustrate the fundamental role of miR203 as a natural inhibitor of RAS/MAPK signaling in hepatic carcinogenesis in vitro and in vivo. In light of the critical and universal activation of the MAPK pathway in HCC, miR203 has the potential to serve as a nucleotide drug for the treatment of HCC with activated MAPK signaling.

Fungal plant pathogen "mutagenomics" reveals tagged and untagged mutations in Zymoseptoria tritici and identifies SSK2 as key morphogenesis and stress-responsive virulence factor

"Mutagenomics" is the combination of random mutagenesis, phenotypic screening, and whole-genome re-sequencing to uncover all tagged and untagged mutations linked with phenotypic changes in an organism. In this study, we performed a mutagenomics screen on the wheat pathogenic fungus Zymoseptoria tritici for altered morphogenetic switching and stress sensitivity phenotypes using Agrobacterium-mediated "random" T-DNA mutagenesis (ATMT). Biological screening identified four mutants which were strongly reduced in virulence on wheat. Whole genome re-sequencing defined the positions of the T-DNA insertion events and revealed several unlinked mutations potentially affecting gene functions. Remarkably, two independent reduced virulence mutant strains, with similarly altered stress sensitivities and aberrant hyphal growth phenotypes, were found to have a distinct loss of function mutations in the ZtSSK2 MAPKKK gene. One mutant strain had a direct T-DNA insertion affecting the predicted protein's N-terminus, while the other possessed an unlinked frameshift mutation towards the C-terminus. We used genetic complementation to restore both strains' wild-type (WT) function (virulence, morphogenesis, and stress response). We demonstrated that ZtSSK2 has a non-redundant function with ZtSTE11 in virulence through the biochemical activation of the stress-activated HOG1 MAPK pathway. Moreover, we present data suggesting that SSK2 has a unique role in activating this pathway in response to specific stresses. Finally, dual RNAseq-based transcriptome profiling of WT and SSK2 mutant strains revealed many HOG1-dependent transcriptional changes in the fungus during early infection and suggested that the host response does not discriminate between WT and mutant strains during this early phase. Together these data define new genes implicated in the virulence of the pathogen and emphasise the importance of a whole genome sequencing step in mutagenomic discovery pipelines.

Thyroid Follicular Epithelial Cell-Derived Cancer: New Approaches and Treatment Strategies

Thyroid follicular epithelial cell-derived cancer includes papillary carcinoma, follicular carcinoma, Hürthle cell carcinoma, poorly differentiated thyroid cancer, and anaplastic thyroid carcinoma. Although the incidence of thyroid cancer has increased over the past 30 years, there has not been a significant increase in patient mortality. Use of increasingly sensitive detection methods such as high-resolution imaging has enabled earlier detection and better characterization of the thyroid malignancies. In the past several years, researchers have evaluated genetic mutations promoting thyroid carcinogenesis and oncogenesis. The identification of genetic mutations is important in understanding tumor initiation and progression. Additionally, these identified mutations may also serve as potential diagnostic or prognostic indicators and therapeutic molecular targets.

Unilateral Nephrectomy Stimulates ERK and Is Associated With Enhanced Na Transport

Nephron loss initiates compensatory hemodynamic and cellular effects on the remaining nephrons. Increases in single nephron glomerular filtration rate and tubular flow rate exert higher fluid shear stress (FSS) on tubules. In principal cell (PC) culture models FSS induces ERK, and ERK is implicated in the regulation of transepithelial sodium (Na) transport, as well as, proliferation. Thus, we hypothesize that high tubular flow and FSS mediate ERK activation in the cortical collecting duct (CCD) of solitary kidney which regulates amiloride sensitive Na transport and affects CCD cell number. Immunoblotting of whole kidney protein lysate was performed to determine phospho-ERK (pERK) expression. Next, sham and unilateral nephrectomized mice were stained with anti-pERK antibodies, and dolichos biflorus agglutinin (DBA) to identify PCs with pERK. Murine PCs (mpkCCD) were grown on semi-permeable supports under static, FSS, and FSS with U0126 (a MEK1/2 inhibitor) conditions to measure the effects of FSS and ERK inhibition on amiloride sensitive Na short circuit current (Isc). pERK abundance was greater in kidney lysate of unilateral vs. sham nephrectomies. The total number of cells in CCD and pERK positive PCs increased in nephrectomized mice (9.3 ± 0.4 vs. 6.1 ± 0.2 and 5.1 ± 0.5 vs. 3.6 ± 0.3 cell per CCD nephrectomy vs. sham, respectively, n > 6 per group, p < 0.05). However, Ki67, a marker of proliferation, did not differ by immunoblot or immunohistochemistry in nephrectomy samples at 1 month compared to sham. Next, amiloride sensitive Isc in static mpkCCD cells was 25.3 ± 1.7 μA/cm² (n = 21), but after exposure to 24 h of FSS the Isc increased to 41.4 ± 2.8 μA/cm² (n = 22; p < 0.01) and returned to 19.1 ± 2.1 μA/cm² (n = 18, p < 0.01) upon treatment with U0126. Though FSS did not alter α- or γ-ENaC expression in mpkCCD cells, γ-ENaC was reduced in U0126 treated cells. In conclusion, pERK increases in whole kidney and, specifically, CCD cells after nephrectomy, but pERK was not associated with active proliferation at 1-month post-nephrectomy. In vitro studies suggest high tubular flow induces ERK dependent ENaC Na absorption and may play a critical role in Na balance post-nephrectomy.

Developmental phenotypes of Arabidopsis plants expressing phosphovariants of AtMYB75

The Arabidopsis transcription factor Myeloblastosis protein 75 (MYB75, AT1G56650) is a well-established transcriptional activator of genes required for anthocyanin and flavonoid production, and a repressor of lignin and other secondary cell wall biosynthesis genes. MYB75 is itself tightly regulated at the transcriptional, translational and post-translational levels, including protein phosphorylation by Arabidopsis MAP kinases Examination of the behavior of different phosphovariant versions of MYB75 in vitro and in vivo revealed that overexpression of the MYB75^T131E phosphovariant had a particularly marked effect on global changes in gene expression suggesting that phosphorylated MYB75 could be involved in a broader range of functions than previously recognized. Here, we describe a range of distinct developmental phenotypes observed among Arabidopsis lines expressing various phosphovariant forms of MYB75. Expression of either MYB75^T131E or MYB75^T131A phosphovariants, from the endogenous MYB75 promoter, in Arabidopsis myb75^- mutants (Nossen background), resulted in severely impaired germination rates, and developmental arrest at early seedling stages. Arabidopsis plants overexpressing MYB75^T131E from a strong constitutive Cauliflower mosaic virus (CaMV35S) promoter displayed slower development, with delayed bolting, flowering and onset of senescence. Conversely, MYB75^T131A -overexpressing lines flowered and set seed earlier than either Col-0 WT controls or other MYB75-overexpressors (MYB75^WT and MYB75^T131E ). Histochemical analysis of mature stems also revealed ectopic vessel development in plants overexpressing MYB75; this phenotype was particularly prominent in the MYB75^T131E phosphovariant. These data suggest that MYB75 plays a significant role in plant development, and that this aspect of MYB75 function is influenced by its phosphorylation status.

Role of azithromycin in antiviral treatment: enhancement of interferon-dependent antiviral pathways and mitigation of inflammation may rely on inhibition of the MAPK cascade?

Azithromycin is a macrolide-type antibiotic used against a broad range of bacterial infection, such as respiratory tract, skin, ear, eye infections, and sexually transmitted diseases. The ongoing severe acute respiratory syndrome (SARS) mediated by Corona Virus 2 (CoVid19) is a global health concern and various countries witnessed the loss of precious human life. In fall 2020, the absence of specific suitable medication or vaccine is still a major cause of concern to fight the pandemic while different countries have already started using their own medication and available resources to save the life of their citizens. At the present, in many countries around the world, we witnessed the use of the antibiotic azithromycin towards the medication of CoVid19; even its effect on anti CoVid19 is still controversial. This mini review aims to address whether azithromycin can affect molecular pathway involved in inflammatory immunity upon viral infection, to find out the rationale behind the use of azithromycin in the treatment of CoVid19. Overall, the data show that the mechanism of action of azithromycin in viral infection may be dependent on a global amplification of the interferon-dependent pathways mediating antiviral responses, leading to a reduction of viral replication, together with a strong impairment of the inflammatory pathways, relying on MAPK cascade inactivation.

Combined effect of recombinant human adenovirus p53 and curcumin in the treatment of liver cancer

The development of an effective therapeutic intervention for liver cancer is a worldwide challenge that remains to be adequately addressed. Of note, TP53, which encodes the p53 protein, is an important tumor suppressor gene, 61% of TP53 is functionally inactivated in liver cancer. Recombinant human adenovirus p53 (rAd-p53) is the first commercial product that has been used for gene therapy. In the present study, the combined mechanistic effects of rAd-p53 and curcumin, a naturally occurring compound with previously reported anti-inflammatory, antioxidant and anti-cancer properties, were assessed in liver cancer cells, using HepG2 cells as the model cell line. The administration of either curcumin or rAd-p53 promoted apoptosis, suppressed epithelial-mesenchymal transition (EMT) and blocked G2/M phase progression in HepG2 cells, which were potentiated further when both agents were applied together. Combined rAd-p53 and curcumin treatment resulted in higher p53 (P<0.01) and p21 (P<0.01) expression compared with rAd-p53 or curcumin were added alone, suggesting an additive effect on TP53 expression. Additionally, curcumin and rAd-p53 were demonstrated to regulate the activation of mitogen-activated protein kinases (MAPKs) ERK1/2, p38 MAPK and JNK. These results indicated that the combination of rAd-p53 with curcumin synergistically potentiates apoptosis and inhibit EMT compared with either rAd-p53 or curcumin treatment alone via the regulation of TP53 regulation. Mechanistically, this effect on TP53 expression may involve the ERK1/2, p38 MAPK and JNK signaling pathways. The current study provides new insights that can potentially advance the development of therapeutic strategies for liver cancer treatment.

Phosphoproteome profiling provides insight into the mechanisms of ventilator-induced lung injury

The incidence of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) is a common health problem in the clinic and is projected to increase in prevalence in the future. Mechanical ventilation is commonly used to provide respiratory support and has become indispensable in emergency and critical medicine. However, ventilator use can result in lung tissue damage, collectively termed ventilator-induced lung injury (VILI). In the present study, phosphoprotein profiling of blood and tissue samples from ventilated and non-ventilated mice was performed and key changes in protein levels and cell signaling during VILI were identified. Activation of the PI3K/AKT and mitogen activated protein kinase signaling pathways, in addition to changes in expression of cancer, inflammatory and cell-death related proteins were detected in response to mechanical ventilation. Focal adhesion-related protein levels and signaling pathways were also significantly altered in an injury model compared with control. VILI can affect patient mortality in ALI and ARDS cases, and no targeted treatment options currently exist. Identifying biomarkers and understanding the signaling pathways associated with VILI is critical for the development of future therapies.

Anti-Inflammatory Potential of Probiotic Strain Weissella cibaria JW15 Isolated from Kimchi through Regulation of NF-κB and MAPKs Pathways in LPS-Induced RAW 264.7 Cells

Probiotics are known to provide the host with immune-modulatory effects and are therefore of remarkable interest for therapeutic and prophylactic applications against various disorders, including inflammatory diseases. Weissella cibaria JW15 (JW15) has been reported to possess probiotic and antioxidant properties. However, the effect of JW15 on inflammatory responses has not yet been reported. Therefore, the objective of the current study was to evaluate the anti-inflammatory potential of JW15 against lipopolysaccharide (LPS) stimulation. The production of pro-inflammatory factors and the cellular signaling pathways following treatment with heat-killed JW15 was examined in LPS-induced RAW 264.7 cells. Treatment with heat-killed JW15 decreased nitric oxide and prostaglandin E₂ production via downregulation of the inducible nitric oxide synthase and cyclooxygenase-2. In addition, treatment with heat-killed JW15 suppressed the expression of pro-inflammatory cytokines, interleukin (IL)-1β, IL-6, and tumor necrosis factor-α. The anti-inflammatory properties of treating with heat-killed JW15 were associated with mitogen-activated protein kinase signaling pathwaymediated suppression of nuclear factor-κB. These results indicated that JW15 possesses antiinflammatory potential and provide a molecular basis regarding the development of functional probiotic products.

Impaired circulating myeloid CD1c+ dendritic cell function in human glioblastoma is restored by p38 inhibition - implications for the next generation of DC vaccines

Current treatments for glioblastoma (GBM) have limited efficacy and significant morbidity and therefore new strategies are urgently needed. Dendritic cells have the power to create anti-tumor immune responses. The greater potency of circulating dendritic cells (DC) over laboratory-generated monocyte-derived DC makes them exciting new immunotherapeutic candidates. To determine the immune status of GBM patients we initially investigated the frequency and function of circulating DC subsets. Furthermore, we tested the therapeutic potential of inhibiting the p38 mitogen-activated protein kinase pathway (p38i) in circulating DC to overcome DC dysfunction. GBM patients (n = 16) had significantly reduced numbers of the major myeloid circulating dendritic cell (cDC2) and plasmacytoid DC vs healthy controls; 1736 vs 4975 (p = 0.028) and 893 vs 2287 cells/mL (P = <0.001) respectively. This inversely correlated with dexamethasone (Dex) dose in a log-linear model, and disease status. Patients' cDC2 were immature with impaired interleukin (IL)-12 secretion, reduced IL-12:IL-10 ratio, and low HLA-DR and CD86 expression. Exposure of healthy donor cDC2 to Dex or GBM cell lysate resulted in a similar low IL-12:IL-10 ratio. Inhibition of p38 restored the IL-12:IL-10 balance in Dex or tumor lysate-conditioned healthy cDC2 and enhanced T-cell proliferation and interferon-gamma (IFNγ) production. Importantly, patient-derived cDC2 showed a similar reversal of DC dysfunction with p38i. This study demonstrates the therapeutic potential of developing the next generation of DC vaccines using enhanced p38i-conditioned cDC2. We will therefore shortly embark on a clinical trial of adoptively transferred, p38 MAPK-inhibited cDC2 in adults with GBM.

Dual inhibition of MEK and p38 impairs tumor growth in KRAS-mutated non-small cell lung cancer

Despite the high frequency of KRAS mutations in non-small cell lung cancer (NSCLC), therapeutic modalities targeting KRAS-mutated NSCLC have not been established. Based on our previous findings that mutant KRAS knockdown sensitized NSCLC cells to a p38 inhibitor, the growth-inhibitory effect of dual MEK and p38 inhibition on tumor growth in NSCLC cells harboring KRAS mutations was investigated. In KRAS-mutated NSCLC cells, the MEK inhibitor, selumetinib, inhibited cell growth in a dose-dependent manner, and its growth-inhibitory effect was enhanced by combined treatment with the p38 inhibitor LY2228820. Similarly, another pair of MEK and p38 inhibitors also exhibited antitumor activity. Small interfering RNAs (siRNAs) against MAPK14, which encodes p38α MAPK, enhanced the growth-inhibitory effect of the MEK inhibitors in NSCLC cells with KRAS mutations. Notably, MEK inhibitors reduced p38 expression levels but increased p38 phosphorylation levels, resulting in sensitization to p38 inhibitors in KRAS-mutated NSCLC cells. These results provide evidence that dual MEK and p38 inhibition could be a potent therapeutic strategy against oncogenic KRAS-driven NSCLC.

Apoptosis of bone marrow mesenchymal stromal/stem cells via the MAPK and endoplasmic reticulum stress signaling pathways

Therapy for myocardial regeneration using bone marrow stromal cells (BM-MSCs) has been applied to improve the cardiac function of subjects with acute myocardial infarction. However, the study of this therapy has encountered a bottleneck because BM-MSCs are prone to apoptosis in ischemic and anoxic environments. The goal of this study was to investigate the expression of mitogen activated protein kinase (MAPK) (p-38, JNK and ERK) and endoplasmic reticulum stress protein (caspase-12 and CHOP) during BM-MSC apoptosis. In a BM-MSC model of hypoxia and serum deprivation (H/SD), we observed the morphology and apoptotic rate of BM-MSCs for 24 h and found that the nuclear shrinkage and apoptosis rate increased gradually and reached a maximum apoptosis rate at the 6 h time point. Then, with the prolongation of the hypoxia time, the number of nuclear shrinkage cells and the apoptosis rate gradually decreased. The expression levels of p-38, JNK, ERK, procaspase-12, caspase-12 and CHOP increased at each H/SD time point. In addition, compared with the H/SD 6 h group, the nuclear shrinkage and apoptosis rate were decreased in the SB202190 and SP600125 groups but increased in the PD98059 group. Further, the expression of caspase-12 in the SB202190 group decreased, while the expression of procaspase-12 increased, compared with the H/SD 6 h group. Overall, our findings suggested that p-38, JNK, CHOP and caspase-12 play important roles in promoting the apoptosis of BM-MSCs, while ERK is contrary to other signals. Moreover, the apoptosis of BM-MSCs was induced by H/SD via the p-38-caspase-12 signaling pathway.

Onset and Progression of Human Osteoarthritis-Can Growth Factors, Inflammatory Cytokines, or Differential miRNA Expression Concomitantly Induce Proliferation, ECM Degradation, and Inflammation in Articular Cartilage?

Osteoarthritis (OA) is a degenerative whole joint disease, for which no preventative or therapeutic biological interventions are available. This is likely due to the fact that OA pathogenesis includes several signaling pathways, whose interactions remain unclear, especially at disease onset. Early OA is characterized by three key events: a rarely considered early phase of proliferation of cartilage-resident cells, in contrast to well-established increased synthesis, and degradation of extracellular matrix components and inflammation, associated with OA progression. We focused on the question, which of these key events are regulated by growth factors, inflammatory cytokines, and/or miRNA abundance. Collectively, we elucidated a specific sequence of the OA key events that are described best as a very early phase of proliferation of human articular cartilage (AC) cells and concomitant anabolic/catabolic effects that are accompanied by incipient pro-inflammatory effects. Many of the reviewed factors appeared able to induce one or two key events. Only one factor, fibroblast growth factor 2 (FGF2), is capable of concomitantly inducing all key events. Moreover, AC cell proliferation cannot be induced and, in fact, is suppressed by inflammatory signaling, suggesting that inflammatory signaling cannot be the sole inductor of all early OA key events, especially at disease onset.

MAP kinases nomenclature: Time for curation

The nomenclature of Mitogen Activated Protein Kinases (MAPKs) takes different formats composed of symbols, prefixes, suffixes, or descriptive acronyms of their functions that sometimes lead to confusion and make the indexed information redundant and inconsistent. To avoid such redundancy and reduce confusion, a curation of the terminology of MAP kinase families, and that of other protein families that present similar nomenclature issues, is required. Some arguable suggestions are presented here toward this goal.

Oxidative stress regulates mitogen‑activated protein kinases and c‑Jun activation involved in heat stress and lipopolysaccharide‑induced intestinal epithelial cell apoptosis

Heat stress and gut‑derived endotoxinemia are common causes of multiple organ dysfunction syndrome in heat stroke patients. Evidence has demonstrated that cell apoptosis in the small intestine serves an important role in the pathogenesis of heatstroke, which leads to increased intestinal permeability to endotoxin or lipopolysaccharides (LPS) from the gut entering the circulation. However, little is known about the potential underlying mechanisms mediating heat stress combined with LPS‑induced intestinal epithelial cell apoptosis. In the present study, LPS combined with heat stress induced production of reactive oxygen species (ROS), mitochondrial membrane potential disruption and cell apoptosis, which eventually led to increased intestinal permeability and reduced epithelial resistance in the IEC‑6 cell line. Inductions in ROS, mitochondrial membrane potential disruption and cell apoptosis were detected by using an ROS assay kit, 5,5',6,6'‑tetrachloro‑1,1',3,3'tetraethylbenzimidazo carbocyanine iodide dye kit and annexin V‑fluorescein isothiocyanate apoptosis kit, respectively. The effect of ROS on mitogen activated protein kinases (MAPKs) and c‑Jun activation was investigated using the antioxidant drug, butylated hydroxyanisole (BHA) by western blotting. The results of the present study demonstrated that ROS is essential to activate p38, extracellular signal‑regulated kinase (ERK) and c‑Jun, but not c‑Jun N‑terminal kinase (JNK), in LPS combined with heat stress treated cells. Furthermore, ROS, and activation of p38, JNK and c‑Jun, were revealed to serve pro‑apoptosis roles which aggravated damage to epithelial barrier integrity, as assessed by flow cytometry using Annexin V‑fluorescein isothiocyanate staining and pretreatment of cells with specific inhibitors of ROS, JNK, p38 and c‑Jun (BHA, SP600125, SB203580 and c‑Jun peptide, respectively). Transepithelial electrical resistance and horseradish peroxidase permeability were detected in cells treated with LPS combined with heat stress, which revealed that ERK serves an anti‑apoptosis role, as determined by pretreatment of cells with PD98059, a specific inhibitor of ERK. In conclusion, these findings suggested a novel role of the ROS signaling pathway which involved activation of MAPKs and c‑Jun, following LPS combined with heat stress‑induced IEC‑6 cell apoptosis and impairment of the epithelial barrier. These results may facilitate understanding of pathological conditions involving ROS, such as heat stroke.

Bone morphogenetic protein 7 alleviates paraquat-induced pulmonary fibrosis via TGF-β1/Erk1/2 pathway

Bone morphogenetic protein 7 (BMP-7) recently demonstrates an anti-fibrotic effect. To evaluate the role of BMP-7 in paraquat (PQ)-induced pulmonary fibrosis, PQ-exposed mice and lung fibroblasts (MRC-5) were treated with BMP-7. Our results showed that BMP-7 treatment could significantly reduce PQ-induced pulmonary fibrosis, accompanied by downregulation of transforming growth factor (TGF)-β1 and collagen I deposition in mouse lungs. Moreover, PQ-induced inviability, apoptosis, high level of collagen I, as well as phosphorylation of Erk1/2, in MRC-5 cells were significantly inhibited by BMP-7 treatment. These findings indicate BMP-7 alleviates PQ-induced pulmonary fibrosis partly via TGF-β1/Erk1/2 pathway, suggesting a promising therapeutic means for PQ-induced fibrotic lung injury.

Combination of mTOR and MAPK Inhibitors-A Potential Way to Treat Renal Cell Carcinoma

Renal cell carcinoma (RCC) is the most common neoplasm that occurs in the kidney and is marked by a unique biology, with a long history of poor response to conventional cancer treatments. In the past few years, there have been significant advancements to understand the biology of RCC. This has led to the introduction of novel targeted therapies in the management of patients with metastatic disease. Patients treated with targeted therapies for RCC had shown positive impact on overall survival, however, no cure is possible and patients need to undergo treatment for long periods of time, which raises challenges to manage the associated adverse events. Moreover, many patients may not respond to it and even response may not last long enough in the responders. Many inhibitors of the Mammalian target of Rapamycin (mTOR) signaling pathway are currently being used in treatment of advanced RCC. Studies showed that inhibitions of mTOR pathways induce Mitogen-Activated Protein Kinase (MAPK) escape cell death and cells become resistant to mTOR inhibitors. Because of this, there is a need to inhibit both pathways with their inhibitors comparatively for a better outcome and treatment of patients with RCC.

The Role of MAPK Modules and ABA during Abiotic Stress Signaling

To respond to abiotic stresses, plants have developed specific mechanisms that allow them to rapidly perceive and respond to environmental changes. The phytohormone abscisic acid (ABA) was shown to be a pivotal regulator of abiotic stress responses in plants, triggering major changes in plant physiology. The ABA core signaling pathway largely relies on the activation of SnRK2 kinases to mediate several rapid responses, including gene regulation, stomatal closure, and plant growth modulation. Mitogen-activated protein kinases (MAPKs) have also been implicated in ABA signaling, but an entire ABA-activated MAPK module was uncovered only recently. In this review, we discuss the evidence for a role of MAPK modules in the context of different plant ABA signaling pathways.

The Sclerotinia sclerotiorum Slt2 mitogen-activated protein kinase ortholog, SMK3, is required for infection initiation but not lesion expansion

Mitogen-activated protein kinases (MAPKs) play a central role in transferring signals and regulating gene expression in response to extracellular stimuli. An ortholog of the Saccharomyces cerevisiae cell wall integrity MAPK was identified in the phytopathogenic fungus Sclerotinia sclerotiorum. Disruption of the S. sclerotiorum Smk3 gene severely reduced virulence on intact host plant leaves but not on leaves stripped of cuticle wax. This was attributed to alterations in hyphal apical dominance leading to the inability to aggregate and form infection cushions. The mutation also caused loss of the ability to produce sclerotia, increased aerial hyphae formation, and altered hyphal hydrophobicity and cell wall integrity. Mutants had slower radial expansion rates on solid media but more tolerance to elevated temperatures. Loss of the SMK3 cell wall integrity MAPK appears to have impaired the ability of S. sclerotiorum to sense its surrounding environment, leading to misregulation of a variety of functions. Many of the phenotypes were similar to those observed in S. sclerotiorum adenylate cyclase and SMK1 MAPK mutants, suggesting that these signaling pathways co-regulate aspects of fungal growth, physiology, and pathogenicity.

Extracellular signal-regulated kinases 1/2 as regulators of cardiac hypertrophy

Cardiac hypertrophy results from increased mechanical load on the heart and through the actions of local and systemic neuro-humoral factors, cytokines and growth factors. These mechanical and neuroendocrine effectors act through stretch, G protein–coupled receptors and tyrosine kinases to induce the activation of a myriad of intracellular signaling pathways including the extracellular signal-regulated kinases 1/2 (ERK1/2). Since most stimuli that provoke myocardial hypertrophy also elicit an acute phosphorylation of the threonine-glutamate-tyrosine (TEY) motif within the activation loops of ERK1 and ERK2 kinases, resulting in their activation, ERKs have long been considered promotors of cardiac hypertrophy. Several mouse models were generated in order to directly understand the causal role of ERK1/2 activation in the heart. These models include direct manipulation of ERK1/2 such as overexpression, mutagenesis or knockout models, manipulations of upstream kinases such as MEK1 and manipulations of the phosphatases that dephosphorylate ERK1/2 such as DUSP6. The emerging understanding from these studies, as will be discussed here, is more complex than originally considered. While there is little doubt that ERK1/2 activation or the lack of it modulates the hypertrophic process or the type of hypertrophy that develops, it appears that not all ERK1/2 activation events are the same. While much has been learned, some questions remain regarding the exact role of ERK1/2 in the heart, the upstream events that result in ERK1/2 activation and the downstream effector in hypertrophy.

Monitoring protein phosphorylation by acrylamide pendant Phos-Tag™ in various plants

The aim of the present study is to rationalize acrylamide pendant Phos-Tag™ in-gel discrimination of phosphorylated and non-phosphorylated plant protein species with standard immunoblot analysis, and optimize sample preparation, efficient electrophoretic separation and transfer. We tested variants of the method including extraction buffers suitable for preservation of phosphorylated protein species in crude extracts from plants and we addressed the importance of the cation (Mn(2+) or Zn(2+)) used in the gel recipe for efficient transfer to PVDF membranes for further immunoblot analysis. We demonstrate the monitoring of Medicago sativa stress-induced mitogen activated protein kinase (SIMK) in stress-treated wild type plants and transgenic SIMKK RNAi line. We further show the hyperosmotically-induced phosphorylation of the previously uncharacterized HvMPK4 of barley. The method is validated using inducible phosphorylation of barley and wheat α-tubulin and of Arabidopsis MPK6. Acrylamide pendant Phos-Tag™offers a flexible tool for studying protein phosphorylation in crops and Arabidopsis circumventing radioactive labeling and the use of phosphorylation specific antibodies.

Differential regulation of EGFR-MAPK signaling by deoxycholic acid (DCA) and ursodeoxycholic acid (UDCA) in colon cancer

A high-fat diet coincides with increased levels of bile acids. This increase in bile acids, particularly deoxycholic acid (DCA), has been strongly associated with the development of colon cancer. Conversely, ursodeoxycholic acid (UDCA) may have chemopreventive properties. Although structurally similar, DCA and UDCA present different biological and pathological effects in colon cancer progression. The differential regulation of cancer by these two bile acids is not yet fully understood. However, one possible explanation for their diverging effects is their ability to differentially regulate signaling pathways involved in the multistep progression of colon cancer, such as the epidermal growth factor receptor (EGFR)-mitogen-activated protein kinase (MAPK) pathway. This review will examine the biological effects of DCA and UDCA on colon cancer development, as well as the diverging effects of these bile acids on the oncogenic signaling pathways that play a role in colon cancer development, with a particular emphasis on bile acid regulation of the EGFR-MAPK pathway.

MAPK transgenic circuit to improve plant stress-tolerance?

Thanks to their distinctive mode of action in a coordinated switch-like way, their multi-tiered signaling cascades and their involvement in cell responses to multiple internal and external stimuli, MAP kinases offer a remarkable possibility to be assembled into what we can call "MAPK transgenic circuits" to improve cell functions. Such circuit could be used to enhance cell signaling efficiency and boost cell functions for several purposes in plant biotechnology, medicine, and pharmaceutical industry.

Zinc ions as effectors of environmental oxidative lung injury

The redox-inert transition metal Zn is a micronutrient that plays essential roles in protein structure, catalysis, and regulation of function. Inhalational exposure to ZnO or to soluble Zn salts in occupational and environmental settings leads to adverse health effects, the severity of which appears dependent on the flux of Zn(2+) presented to the airway and alveolar cells. The cellular toxicity of exogenous Zn(2+) exposure is characterized by cellular responses that include mitochondrial dysfunction, elevated production of reactive oxygen species, and loss of signaling quiescence leading to cell death and increased expression of adaptive and inflammatory genes. Central to the molecular effects of Zn(2+) are its interactions with cysteinyl thiols, which alters their functionality by modulating their reactivity and participation in redox reactions. Ongoing studies aimed at elucidating the molecular toxicology of Zn(2+) in the lung are contributing valuable information about its role in redox biology and cellular homeostasis in normal and pathophysiology.

Humic acid in drinking well water induces inflammation through reactive oxygen species generation and activation of nuclear factor-κB/activator protein-1 signaling pathways: a possible role in atherosclerosis

Humic acid (HA) has been implicated as one of the etiological factors in the peripheral vasculopathy of blackfoot disease (BFD) in Taiwan. However, the underlying pathophysiological mechanisms of BFD are not well defined. In this study, we used an in vitro and in vivo model, in which HA (25-200μg/mL) activated macrophages to produce pro-inflammatory molecules by activating their transcriptional factors. HA exposure induced NO and PGE2 production followed by induction of iNOS and COX-2 through NF-κB/AP-1 transactivation in macrophages. In addition, the production of TNF-α and IL-1β was significantly increased by HA. Moreover, HA-induced iNOS and COX-2 expression were down-regulated by the NF-κB and AP-1 inhibitors pyrrolidine dithiocarbamate (PDTC) and Tanshinone, respectively. Furthermore, generations of ROS and nitrotyrosine, as well as activation of the AKT and MAPKs signaling cascades were observed after HA exposure. Specifically, HA-induced NF-κB activation was mediated by ROS and AKT, and that HA-induced AP-1 activation was mediated by JNK and ERK. Notably, HA-mediated AKT, JNK, and ERK activation was ROS-independent. The inflammatory potential of HA was correlated with increased expression of HO-1 and Nrf2. Furthermore, an in vivo study confirms that mice exposed to HA, the serum levels of TNF-α and IL-1β was significantly increased in a dose-dependent manner. This report marks the first confirmation that environmental exposure of HA induces inflammation in macrophages, which may be one of the main causes of early atherogenesis in blackfoot disease.

Extra-adrenal glucocorticoid synthesis: immune regulation and aspects on local organ homeostasis

Systemic glucocorticoids (GCs) mainly originate from de novo synthesis in the adrenal cortex under the control of the hypothalamus-pituitary-adrenal (HPA)-axis. However, research during the last 1-2 decades has revealed that additional organs express the necessary enzymes and have the capacity for de novo synthesis of biologically active GCs. This includes the thymus, intestine, skin and the brain. Recent research has also revealed that locally synthesized GCs most likely act in a paracrine or autocrine manner and have significant physiological roles in local homeostasis, cell development and immune cell activation. In this review, we summarize the nature, regulation and known physiological roles of extra-adrenal GC synthesis. We specifically focus on the thymus in which GC production (by both developing thymocytes and epithelial cells) has a role in the maintenance of proper immunological function.

Emerging novel roles of neuropeptide Y in the retina: from neuromodulation to neuroprotection

Neuropeptide Y (NPY) and NPY receptors are widely expressed in the central nervous system, including the retina. Retinal cells, in particular neurons, astrocytes, and Müller, microglial and endothelial cells express this peptide and its receptors (Y1, Y2, Y4 and/or Y5). Several studies have shown that NPY is expressed in the retina of various mammalian and non-mammalian species. However, studies analyzing the distribution of NPY receptors in the retina are still scarce. Although the physiological roles of NPY in the retina have not been completely elucidated, its early expression strongly suggests that NPY may be involved in the development of retinal circuitry. NPY inhibits the increase in [Ca(2+)]i triggered by elevated KCl in retinal neurons, protects retinal neural cells against toxic insults and induces the proliferation of retinal progenitor cells. In this review, we will focus on the roles of NPY in the retina, specifically proliferation, neuromodulation and neuroprotection. Alterations in the NPY system in the retina might contribute to the pathogenesis of retinal degenerative diseases, such as diabetic retinopathy and glaucoma, and NPY and its receptors might be viewed as potentially novel therapeutic targets.

Management of diabetic complications: a chemical constituents based approach

ETHNOPHARMACOLOGICAL RELEVANCE

Long term hyperglycemia leads to development of complications associated with diabetes. Diabetic complications are now a global health problem without effective therapeutic approach. Hyperglycemia and oxidative stress are important components for the development of diabetic complications. Over the past few decades, herbal medicines have attracted much attention as potential therapeutic agents in the prevention and treatment of diabetic complications due to their multiple targets and less toxic side effects. This review aims to assess the current available knowledge of medicinal herbs for attenuation and management of diabetic complications and their underlying mechanisms.

MATERIAL AND METHODS

Bibliographic investigation was carried out by scrutinizing classical text books and peer reviewed papers, consulting worldwide accepted scientific databases (SCOPUS, PUBMED, SCIELO, NISCAIR, Google Scholar) to retrieve available published literature. The inclusion criteria for the selection of plants were based upon all medicinal herbs and their active compounds with attributed potentials in relieving diabetic complications. Moreover, plants which have potential effect in ameliorating oxidative stress in diabetic animals have been included.

RESULTS

Overall, 238 articles were reviewed for plant literature and out of the reviewed literature, 127 articles were selected for the study. Various medicinal plants/plant extracts containing flavonoids, alkaloids, phenolic compounds, terpenoids, saponins and phytosterol type chemical constituents were found to be effective in the management of diabetic complications. This effect might be attributed to amelioration of persistent hyperglycemia, oxidative stress and modulation of various metabolic pathways involved in the pathogenesis of diabetic complications.

CONCLUSION

Screening chemical candidate from herbal medicine might be a promising approach for new drug discovery to treat the diabetic complications. There is still a dire need to explore the mechanism of action of various plant extracts and their toxicity profile and to determine their role in therapy of diabetic complications. Moreover, a perfect rodent model which completely mimics human diabetic complications should be developed.

JAK2-targeted anti-inflammatory effect of a resveratrol derivative 2,4-dihydroxy-N-(4-hydroxyphenyl)benzamide

Chemical derivatization of resveratrol has been widely conducted in an effort to overcome its chemical instability and therapeutic potential. In the present study, we examined the anti-inflammatory effects of resveratrol derivatives containing an amide functionality using in vitro macrophage models that were stimulated by Toll-like receptor (TLR) ligands, and using several animal inflammatory disease models. Of the resveratrol derivatives tested, compound 8 (2,4-dihydroxy-N-(4-hydroxyphenyl)benzamide) most strongly inhibited the production of nitric oxide (NO), tumor necrosis factor (TNF)-α, and prostaglandin E2 (PGE2), as well as the mRNA expression of inducible NO synthase (iNOS), TNF-α, and cyclooxygenase (COX)-2 in lipopolysaccharide (LPS)-activated RAW264.7 cells, differentiated U937 cells, and peritoneal macrophages. The inhibitory activity of compound 8 was apparently mediated by suppressing the phosphorylation of signal transducer and activator of transcription (STAT)-1, STAT-3, STAT-5, and interferon regulatory factor (IRF)-3. The direct target of compound 8 was revealed to be Janus kinase 2 (JAK2) but not TANK-binding kinase (TBK) 1 using the direct kinase assay and analyses of complex formation with these molecules. Additionally, upstream kinase of TBK1 seems to be also inhibited by compound 8. This compound also strongly ameliorated mouse inflammatory symptoms seen in arachidonic acid-induced ear edema, dextran sodium sulfate (DSS)-treated colitis, EtOH/HCl-induced gastritis, collagen type II-triggered arthritis, and acetic acid-induced writhing. Therefore, of the resveratrol derivatives that we tested, compound 8 was determined to have the strongest anti-inflammatory activities in vitro and in vivo and may potentially be developed for use as a novel anti-inflammatory drug.

The Hordeum vulgare signalling protein MAP kinase 4 is a regulator of biotic and abiotic stress responses

Mitogen activated protein kinase (MAP kinase) signal transduction pathways are important eukaryotic mechanisms for regulating cellular responses to stress. The objective of this work was to investigate the role of the barley MAP kinase HvMPK4 (a homologue of the Arabidopsis MAP kinase AtMPK1) in the plant response to biotic and abiotic stress. Transgenic barley plants bearing antisense or overexpression constructs for HvMPK4 were produced, and RNA blot analysis showed that HvMPK4 gene expression was much reduced in the antisense lines and approximately double in the overexpression lines. Three independent lines of each construct were tested for their response to a fungal pathogen and to salt treatment. The antisense lines were more resistant to the hemibiotrophic fungal pathogen Magnaporthe grisea, and showed enhanced levels of salicylic acid (SA) and of hydrogen peroxide following infection; HvMPK4 is thus a negative regulator of SA production post infection. The overexpression lines had constitutively higher levels of jasmonic acid and enhanced levels of ethylene following infection but were not more resistant to the pathogen. However the overexpression lines showed greater tolerance to abiotic stress, as following 2 weeks of salt treatment these lines showed less reduction in fresh and dry weight, accumulated less salt in the leaves and contained enhanced levels of the osmoprotectant amino acid, proline.

The health significance of gas- and particle-phase terpene oxidation products: a review

The reactions between terpenes and ozone (or other oxidants) produce a wide variety of both gas- and particle-phase products. Terpenes are biogenic volatile organic compounds (VOCs) that are also contained in many consumer products. Ozone is present indoors since it infiltrates into the indoor environment and is emitted by some office and consumer equipment. Some of the gaseous products formed are irritating to biological tissues, while the condensed-phase products have received attention due to their contribution to ambient fine particulate matter (PM2.5) and its respective health significance. Despite common scientific questions, the indoor and ambient air research communities have tended to operate in isolation regarding this topic. This review critically evaluates the literature related to terpene oxidation products and attempts to synthesize results of indoor and ambient air studies to better understand the health significance of these materials and identify knowledge gaps. The review documents the results of a literature search covering terpene oxidation chemistry, epidemiological, toxicological, and controlled human exposure studies, as well as health studies focused more generically on secondary organic aerosol (SOA). The literature shows a clear role for gas-phase terpene oxidation products in adverse airway effects at high concentrations; however, whether these effects occur at more environmentally relevant levels is unclear. The evidence for toxicity of particle-phase products is less conclusive. Knowledge gaps and future research needs are outlined, and include the need for more consistency in study designs, incorporation of reaction product measurements into epidemiological studies conducted in both indoor and ambient settings, and more focused research on the toxicity of SOA, especially SOA of biogenic origin.

Molecular characterization of five steroid receptors from pengze crucian carp and their expression profiles of juveniles in response to 17α-ethinylestradiol and 17α-methyltestosterone

Pengze crucian carp (Carassius auratus var. pengze, Pcc), a triploid gynogenetic fish, was used in this study to investigate the cross-talk between EDCs and steroid receptors. The full-length cDNAs of five steroid receptors (esr1, er alpha2, esr2a, esr2b, ar) and partial cDNA of vtg B were isolated. The tissue distributions of these genes were analyzed in adult fish by qRT-PCR. Then the expression profiles of five steroid receptors (esrs and ar) and vtg B were detected in the juveniles exposed to 17α-ethinylestradiol (EE2, 0.1, 1 and 10ng/L) and 17α-methyltestosterone (MT, 50μg/L) for 4weeks. The results demonstrated that esrs, ar, and vtg B were predominantly expressed in liver of adult fish. However, among these detected genes, esr1 and er alpha2 mRNAs are sensitive biomarkers in response to EE2 at 0.1, 1, and 10ng/L for 1 and 2weeks compared to esr2a, esr2b, ar, and vtg B in the juveniles of mono-female gynogenetic fish. Totally, the subtypes of esrs show biphasic responses to EE2 exposures for 4weeks, and most of the EE2 exposures at 0.1, 1, and 10ng/L for 1, 2, 3 and 4weeks did not induce the mRNA expressions of vtg B. However, 1-, 2-, and 4-week 50μg/L MT all significantly stimulated vtg B transcripts. Further investigations are needed to elucidate the mechanism underlying the insensitivity or down-regulation of vtg B mRNA in response to EE2 in juvenile Pcc.

Resveratrol enhances TNF-α production in human monocytes upon bacterial stimulation

BACKGROUND

Resveratrol is a key component of red wine that has been reported to have anti-carcinogenic and anti-aging properties. Additional studies conducted in vitro and in animal models suggested anti-inflammatory properties. However, data from primary human immune cells and in vivo studies are limited.

METHODS

A pilot study was performed including 10 healthy volunteers. Plasma cytokine levels were measured over 48h after oral application of 5g resveratrol. To verify the in vivo findings, cytokine release and gene expression in human peripheral blood mononuclear cells (PBMC) and/or monocytes was assessed after treatment with resveratrol or its metabolites and stimulation with several toll-like receptor (TLR)-agonists. Additionally, the impact on intracellular signaling pathways was analyzed using a reporter cell line and Western blotting.

RESULTS

Resveratrol treated individuals showed a significant increase in tumor necrosis factor-α (TNF-α) levels 24h after treatment compared to baseline. Studies using human PBMC or isolated monocytes confirmed potentiation of TNF-α production with different TLR agonists, while interleukin (IL)-10 was inhibited. Moreover, we observed significantly enhanced nuclear factor 'kappa-light-chain-enhancer' of activated B-cells (NF-κB) activation using a reporter cell line and found increased phosphorylation of p105, which is indicative of alternative NF-κB pathway activation.

GENERAL SIGNIFICANCE

By administering resveratrol to healthy humans and utilizing primary immune cells we were able to detect TNF-α enhancing properties of the agent. In parallel, we found enhanced alternative NF-κB activation. We report on a novel pro-inflammatory property of resveratrol which has to be considered in concepts of its biologic activity.

TGF-β-induced expression of IGFBP-3 regulates IGF1R signaling in human osteosarcoma cells

Signaling pathways initiated by transforming growth factor-β (TGF-β) and insulin-like growth factors (IGFs) are important in osteosarcoma cell growth. We have investigated a role for endogenous IGF binding protein-3 (IGFBP-3) in mediating cross-talk between TGF-β receptor and type I IGF receptor (IGF1R) signaling pathways in MG-63 osteosarcoma cells. TGF-β1 indirectly activated the Ras/Raf/MAPK pathway and induced the expression of IGFBP-3, an important regulator of IGF1R activity. IGFBP-3 attenuated TGF-β1 activation of ERK1/2 and Akt in MG-63 cells, and inhibited TGF-β1-induced cell cycle progression and proliferation. This effect of IGFBP-3 was blocked by inhibiting IGF1R signaling. TGF-β1 phosphorylated Smad2 on the non-receptor substrate sites (Ser245/250/255). Blocking the TGF-β1-induced expression of IGFBP-3 enhanced pSmad2(Ser245/250/255) and increased its nuclear accumulation. These results suggest an important role for TGF-β1 in osteosarcoma cell growth, with the induction of IGFBP-3 by TGF-β1 serving in a negative-feedback loop to control cell growth by preventing activation of the IGF1R.

Oligomerization of rice granule-bound starch synthase 1 modulates its activity regulation

Granule-bound starch synthase 1 (GBSS1) is responsible for amylose synthesis in cereals, and this enzyme is regulated at the transcriptional and post-transcriptional levels. In this study, we show that GBSS1 from Oryza sativa L. (OsGBSS1) can form oligomers in rice endosperm, and oligomerized OsGBSS1 exhibits much higher specific enzymatic activity than the monomer. A monomer-oligomer transition equilibrium for OsGBSS1 occurs in the endosperm during development. Redox potential is a key factor affecting the oligomer percentage as well as the enzymatic activity of OsGBSS1. Adenosine diphosphate glucose, the direct donor of glucose, also impacts OsGBSS1 oligomerization in a concentration-dependent manner. OsGBSS1 oligomerization is influenced by phosphorylation status, which was strongly enhanced by Mitogen-activated protein kinase (MAPK) and ATP treatment and was sharply weakened by protein phosphatase (PPase) treatment. The activity of OsGBSS1 affects the ratio of amylose to amylopectin and therefore the eating quality of rice. Understanding the regulation of OsGBSS1 activity may lead to the improvement of rice eating quality.

Functional expression of the transient receptor potential channel TRPA1, a sensor for toxic lung inhalants, in pulmonary epithelial cells

The cation channel TRPA1 functions as a chemosensory protein and is directly activated by a number of noxious inhalants. A pulmonary expression of TRPA1 has been described in sensory nerve endings and its stimulation leads to the acceleration of inflammatory responses in the lung. Whereas the function of TRPA1 in neuronal cells is well defined, only few reports exist suggesting a role in epithelial cells. The aim of the present study was therefore (1) to evaluate the expression of TRPA1 in pulmonary epithelial cell lines, (2) to characterize TRPA1-promoted signaling in these cells, and (3) to study the extra-neuronal expression of this channel in lung tissue sections. Our results revealed that the widely used alveolar type II cell line A549 expresses TRPA1 at the mRNA and protein level. Furthermore, stimulating A549 cells with known TRPA1 activators (i.e., allyl isothiocyanate) led to an increase in intracellular calcium levels, which was sensitive to the TRPA1 blocker ruthenium red. Investigating TRPA1 coupled downstream signaling cascades it was found that TRPA1 activation elicited a stimulation of ERK1/2 whereas other MAP kinases were not affected. Finally, using epithelial as well as neuronal markers in immunohistochemical approaches, a non-neuronal TRPA1 protein expression was detected in distal parts of the porcine lung epithelium, which was also found examining human lung sections. TRPA1-positive staining co-localized with both epithelial and neuronal markers underlining the observed epithelial expression pattern. Our findings of a functional expression of TRPA1 in pulmonary epithelial cells provide causal evidence for a non-neuronal TRPA1-mediated control of inflammatory responses elicited upon TRPA1-mediated registration of toxic inhalants in vivo.

Chitosan oligosaccharides protect rat primary hippocampal neurons from oligomeric β-amyloid 1-42-induced neurotoxicity

β-Amyloid peptide (Aβ), the major component of senile plaques in patients with Alzheimer's disease (AD), is believed to facilitate the progressive neurodegeneration that occurs in this disease. Mounting natural compounds are proved to be potential candidates for the prevention and treatment of AD. Chitosan oligosaccharides (COSs), the enzymatic hydrolysates of chitosan, have been reported to possess diverse biological activities. Here we investigated the effect of COSs on oligomeric Aβ-mediated toxicity in rat primary hippocampal neurons. Pretreatment with COSs markedly inhibited cell death induced by Aβ exposure as determined by cell viability assay and lactate dehydrogenase release assay. In parallel, the generation of reactive oxygen species and lipid peroxidation were attenuated by COSs. Furthermore, our results indicated that COSs remarkably prevented Aβ-induced cell apoptosis as manifested by depressing the elevation of Bax/Bcl-2 ratio and caspase-3 activation, suggesting that the neuroprotective effect of COSs could be partially due to apoptosis regulation. In addition, pretreatment with COSs significantly blocked Aβ-induced phosphorylation of c-Jun N-terminal kinase. Taken together, these findings may shed light on the role of COSs as a potential therapeutic agent for AD.

A fraction of stem bark extract of Entada africana suppresses lipopolysaccharide-induced inflammation in RAW 264.7 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Entada africana is a plant used in African traditional medicine for the treatment of stomachache, fever, liver related diseases, wound healing, cataract and dysentery.

AIMS OF THE STUDY

This study aimed at evaluating the anti-inflammatory activity of fractions of the stem bark extract of the plant using lipopolysaccharide (LPS)-induced inflammation in RAW 264.7 macrophages model.

MATERIALS AND METHODS

The crude extract was prepared using the mixture CH2Cl2/MeOH (1:1, v/v) and fractionated by flash chromatography using solvents of increasing polarity to obtain five different fractions. The effects of the fractions on the cells viability were studied by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and their inhibitory activity against LPS-induced nitric oxide (NO) production screened by Griess test. The most active fraction was further investigated for its effects on reactive oxygen species (ROS) production using flux cytometry, the expression of inducible nitric oxide synthase (iNOS), pro-and anti-inflammatory cytokines (IL1β, TNFα, IL6, IL10 and IL13) by RT-PCR, and the activity of the enzyme p38 MAPK kinase by enzyme-linked immunosorbent assay (ELISA).

RESULTS

The fractions presented no significant effect on the viability of macrophages at 100 μg/ml after 24h incubation. The CH2Cl2/MeOH 5% (Ea5) fraction was found to be the most potent in inhibiting NO production with a half inhibition concentration (IC50)=18.36 μg/ml, and showed the highest inhibition percentage (89.068%) in comparison with Baicalin (63.34%), an external standard at 50 μg/ml. Ea5, as well as Baicalin significantly (P<0.05) inhibited the expression of TNFα, IL6 and IL1β mRNA, attenuated mRNA expression of inducible NO synthase in a concentration-dependent manner, stimulated the expression of anti-inflammatory cytokines (IL10 and IL13), and showed a 30% inhibition of the activity of p38 MAPK kinase.

CONCLUSION

The results of the present study indicate that the fraction Ea5 of Entada africana possesses most potent in vitro anti-inflammatory activity and may contain compounds useful as a therapeutic agent in the treatment of inflammatory related diseases cause by over-activation of macrophages.

3,5-Diiodo-l-thyronine induces SREBP-1 proteolytic cleavage block and apoptosis in human hepatoma (Hepg2) cells

Thyroid hormone 3,5,3'-triiodo-l-thyronine (T3) is known to affect cell metabolism through both the genomic and non-genomic actions. Recently, we demonstrated in HepG2 cells that T3 controls the expression of SREBP-1, a transcription factor involved in the regulation of lipogenic genes. This occurs by activation of a cap-independent translation mechanism of its mRNA. Such a process is dependent on non-genomic activation of both MAPK/ERK and PI3K/Akt pathways. The physiological role of 3,5-diiodo-l-thyronine (T2), previously considered only as a T3 catabolite, is of growing interest. Evidences have been reported that T2 rapidly affects some metabolic pathways through non-genomic mechanisms. Here, we show that T2, unlike T3, determines the block of proteolytic cleavage of SREBP-1 in HepG2 cells, without affecting its expression at the transcriptional or translational level. Consequently, Fatty Acid Synthase expression is reduced. T2 effects depend on the concurrent activation of MAPKs ERK and p38, of Akt and PKC-δ pathways. Upon the activation of these signals, apoptosis of HepG2 cells seems to occur, starting at 12h of T2 treatment. PKC-δ appears to act as a switch between p38 activation and Akt suppression, suggesting that this PKC may function as a controller in the balance of pro-apoptotic (p38) and anti-apoptotic (Akt) signals in HepG2 cells.

Role of drug-independent stress factors in liver injury associated with diclofenac intake

Although a basic understanding of the chemical and biological events leading to idiosyncratic drug toxicity is still lacking, it appears that drug-independent risk factors that increase reactive metabolite formation or alter cellular stress and immune response may be critical determinants in the response to an otherwise non-toxic drug. Thus, we were interested to determine the impact of various drug-independent stress factors - lipopolysaccharide (LPS), poly I:C (PIC) or glutathione depletion via buthionine sulfoximine (BSO) - on the toxicity of diclofenac (Dcl), a model drug associated with rare but significant cases of serious hepatotoxicity, and to understand if enhanced toxicity occurs through alterations of drug metabolism and/or modulation of stress response pathways. Co-treatment of rats repeatedly given therapeutic doses of Dcl for 7 days with a single dose of LPS 2h before the last Dcl dose resulted in severe liver toxicity. Neither LPS nor diclofenac alone or in combination with PIC or BSO had such an effect. While it is thought that bioactivation to reactive Dcl acyl glucuronides (AG) and subsequent protein adduct formation contribute to Dcl induced liver injury, LC-MS/MS analyses did not reveal increased formation of 4'- and 5-hydroxy-Dcl, Dcl-AG or Dcl-AG dependent protein adducts in animals treated with LPS/Dcl. Hepatic gene expression analysis suggested enhanced activation of NFκB and MAPK pathways and up-regulation of co-stimulatory molecules (IL-1β, TNF-α, CINC-1) by LPS/Dcl and PIC/Dcl, while protective factors (HSPs, SOD2) were down-regulated. LPS/Dcl led to extensive release of pro-inflammatory cytokines (IL-1β, IL-6, IFN-γ, TNF-α) and factors thought to constitute danger signals (HMGB1, CINC-1) into plasma. Taken together, our results show that Dcl enhanced the inflammatory response induced by LPS - and to a lesser extent by PIC - through up-regulation of pro-inflammatory molecules and down-regulation of protective factors. This suggests sensitization of cells to cellular stress mediated by non-drug-related risk factors by therapeutic doses of Dcl, rather than potentiation of Dcl toxicity by the stress factors.

Cognitive improvement by acute growth hormone is mediated by NMDA and AMPA receptors and MEK pathway

It has been reported that Growth hormone (GH) has an immediate effect enhancing excitatory postsynaptic potentials mediated by AMPA and NMDA receptors in hippocampal area CA1. As GH plays a role in adult memory processing, this work aims to study the acute effects of GH on working memory tasks in rodents and the possible involvement of NMDA and AMPA receptors and also the MEK/ERK signalling pathway. To evaluate memory processes, two different tests were used, the spatial working memory 8-arm radial maze, and the novel object recognition as a form of non-spatial working memory test. Acute GH treatment (1mg/kg i.p., 1h) improved spatial learning in the radial maze respect to the control group either in young rats (reduction of 46% in the performance trial time and 61% in the number of errors), old rats (reduction of 38% in trial time and 48% in the number of errors), and adult mice (reduction of 32% in the performance time and 34% in the number of errors). GH treatment also increased the time spent exploring the novel object respect to the familiar object compared to the control group in young rats (from 63% to 79%), old rats (from 53% to 70%), and adult mice (from 61 to 68%). The improving effects of GH on working memory tests were blocked by the NMDA antagonist MK801 dizocilpine (0.025 mg/kg i.p.) injected 10 min before the administration of GH, in both young and old rats. In addition, the AMPA antagonist DNQX (1mg/kg i.p.) injected 10 min before the administration of GH to young rats, blocked the positive effect of GH. Moreover, in mice, the MEK inhibitor SL 327 (20mg/kg i.p.) injected 30 min before the administration of GH, blocked the positive effect of GH on radial maze and the novel object recognition. In conclusion, GH improved working memory processes through both glutamatergic receptors NMDA and AMPA and it required the activation of extracellular MEK/ERK signalling pathway. These effects could be related to the enhancement of excitatory synaptic transmission in the hippocampus reported by GH.

A link between two tumorigenic proteins, CD44 and p21WAF1: CD44 increases phorbol ester-induced expression of p21WAF1 by stabilizing its mRNA and extending protein half-life

The cell surface glycoprotein CD44 enhances phorbol-12-myristate 13-acetate (TPA)-induced expression of p21WAF1 by stabilizing its mRNA and enhancing the protein's half-life in several cell lines. Only the plasma membrane-anchored cytoplasmic tail of CD44 and its interacting ezrin, radixin, moesin (ERM) proteins are required for this effect. A mitogen activated kinase (MEK) inhibitor abolishes the action of CD44 on p21. Down-regulation of p21 dramatically decreased anchorage-independence of a cancer cell line, whereas CD44 expression in this background could partially rescue the phenotype.

Biomechanical force in blood development: extrinsic physical cues drive pro-hematopoietic signaling

The hematopoietic system is dynamic during development and in adulthood, undergoing countless spatial and temporal transitions during the course of one's life. Microenvironmental cues in the many unique hematopoietic niches differ, characterized by distinct soluble molecules, membrane-bound factors, and biophysical features that meet the changing needs of the blood system. Research from the last decade has revealed the importance of substrate elasticity and biomechanical force in determination of stem cell fate. Our understanding of the role of these factors in hematopoiesis is still relatively poor; however, the developmental origin of blood cells from the endothelium provides a model for comparison. Many endothelial mechanical sensors and second messenger systems may also determine hematopoietic stem cell fate, self renewal, and homing behaviors. Further, the intimate contact of hematopoietic cells with mechanosensitive cell types, including osteoblasts, endothelial cells, mesenchymal stem cells, and pericytes, places them in close proximity to paracrine signaling downstream of mechanical signals. The objective of this review is to present an overview of the sensors and intracellular signaling pathways activated by mechanical cues and highlight the role of mechanotransductive pathways in hematopoiesis.

Cytokine regulation by MAPK activated kinase 2 in keratinocytes exposed to sulfur mustard

Uncontrolled inflammation contributes to cutaneous damage following exposure to the warfare agent bis(2-chloroethyl) sulfide (sulfur mustard, SM). Activation of the p38 mitogen activated protein kinase (MAPK) precedes SM-induced cytokine secretion in normal human epidermal keratinocytes (NHEKs). This study examined the role of p38-regulated MAPK activated kinase 2 (MK2) during this process. Time course analysis studies using NHEK cells exposed to 200μM SM demonstrated rapid MK2 activation via phosphorylation that occurred within 15 min. p38 activation was necessary for MK2 phosphorylation as determined by studies using the p38 inhibitor SB203580. To compare the role of p38 and MK2 during SM-induced cytokine secretion, small interfering RNA (siRNA) targeting these proteins was utilized. TNF-α, IL-1β, IL-6 and IL-8 secretion was evaluated 24h postexposure, while mRNA changes were quantified after 8h. TNF-α, IL-6 and IL-8 up regulation at the protein and mRNA level was observed following SM exposure. IL-1β secretion was also elevated despite unchanged mRNA levels. p38 knockdown reduced SM-induced secretion of all the cytokines examined, whereas significant reduction in SM-induced cytokine secretion was only observed with TNF-α and IL-6 following MK2 knockdown. Our observations demonstrate potential activation of other p38 targets in addition to MK2 during SM-induced cytokine secretion.

Sprouty2 but not Sprouty4 is a potent inhibitor of cell proliferation and migration of osteosarcoma cells

As negative regulators of receptor tyrosine kinase-mediated signalling, Sprouty proteins fulfil important roles during carcinogenesis. In this report, we demonstrate that Sprouty2 protein expression inhibits cell proliferation and migration in osteosarcoma-derived cells. Although earlier reports describe a tumour-promoting function, these results indicate that Sprouty proteins also have the potential to function as tumour suppressors in sarcoma. In contrast to Sprouty2, Sprouty4 expression failed to interfere with proliferation and migration of the osteosarcoma-derived cells, possibly due to a less pronounced interference with mitogen-activated protein kinase activity. Sequences within the NH2-terminus are responsible for the specific inhibitory function of Sprouty2 protein.

Anoikis molecular pathways and its role in cancer progression

Anoikis is a programmed cell death induced upon cell detachment from extracellular matrix, behaving as a critical mechanism in preventing adherent-independent cell growth and attachment to an inappropriate matrix, thus avoiding colonizing of distant organs. As anchorage-independent growth and epithelial-mesenchymal transition, two features associated with anoikis resistance, are vital steps during cancer progression and metastatic colonization, the ability of cancer cells to resist anoikis has now attracted main attention from the scientific community. Cancer cells develop anoikis resistance due to several mechanisms, including change in integrins' repertoire allowing them to grow in different niches, activation of a plethora of inside-out pro-survival signals as over-activation of receptors due to sustained autocrine loops, oncogene activation, growth factor receptor overexpression, or mutation/upregulation of key enzymes involved in integrin or growth factor receptor signaling. In addition, tumor microenvironment has also been acknowledged to contribute to anoikis resistance of bystander cancer cells, by modulating matrix stiffness, enhancing oxidative stress, producing pro-survival soluble factors, triggering epithelial-mesenchymal transition and self-renewal ability, as well as leading to metabolic deregulations of cancer cells. All these events help cancer cells to inhibit the apoptosis machinery and sustain pro-survival signals after detachment, counteracting anoikis and constituting promising targets for anti-metastatic pharmacological therapy. This article is part of a Special Section entitled: Cell Death Pathways.

Inhibitory effect of α-lipoic acid on thioacetamide-induced tumor promotion through suppression of inflammatory cell responses in a two-stage hepatocarcinogenesis model in rats

To investigate the protective effect of α-lipoic acid (a-LA) on the hepatocarcinogenic process promoted by thioacetamide (TAA), we used a two-stage liver carcinogenesis model in N-diethylnitrosamine (DEN)-initiated and TAA-promoted rats. We examined the modifying effect of co-administered a-LA on the liver tissue environment surrounding preneoplastic hepatocellular lesions, with particular focus on hepatic macrophages and the mechanism behind the decrease in apoptosis of cells surrounding preneoplastic hepatocellular lesions during the early stages of hepatocellular tumor promotion. TAA increased the number and area of glutathione S-transferase placental form (GST-P)(+) liver cell foci and the numbers of proliferating and apoptotic cells in the liver. Co-administration with a-LA suppressed these effects. TAA also increased the numbers of ED2(+), cyclooxygenase-2(+), and heme oxygenase-1(+) hepatic macrophages as well as the number of CD3(+) lymphocytes. These effects were also suppressed by a-LA. Transcript levels of some inflammation-related genes were upregulated by TAA and downregulated by a-LA in real-time RT-PCR analysis. Outside the GST-P(+) foci, a-LA reduced the numbers of apoptotic cells, active caspase-8(+) cells and death receptor (DR)-5(+) cells. These results suggest that hepatic macrophages producing proinflammatory factors may be activated in TAA-induced tumor promotion. a-LA may suppress tumor-promoting activity by suppressing the activation of these macrophages and the subsequent inflammatory responses. Furthermore, a-LA may suppress tumor-promoting activity by suppressing the DR5-mediated extrinsic pathway of apoptosis and the subsequent regeneration of liver cells outside GST-P(+) foci.

Cellular, molecular, and epigenetic mechanisms in non-associative conditioning: implications for pain and memory

Sensitization is a form of non-associative conditioning in which amplification of behavioral responses can occur following presentation of an aversive or noxious stimulus. Understanding the cellular and molecular underpinnings of sensitization has been an overarching theme spanning the field of learning and memory as well as that of pain research. In this review we examine how sensitization, both in the context of learning as well as pain processing, shares evolutionarily conserved behavioral, cellular/synaptic, and epigenetic mechanisms across phyla. First, we characterize the behavioral phenomenon of sensitization both in invertebrates and vertebrates. Particular emphasis is placed on long-term sensitization (LTS) of withdrawal reflexes in Aplysia following aversive stimulation or injury, although additional invertebrate models are also covered. In the context of vertebrates, sensitization of mammalian hyperarousal in a model of post-traumatic stress disorder (PTSD), as well as mammalian models of inflammatory and neuropathic pain is characterized. Second, we investigate the cellular and synaptic mechanisms underlying these behaviors. We focus our discussion on serotonin-mediated long-term facilitation (LTF) and axotomy-mediated long-term hyperexcitability (LTH) in reduced Aplysia systems, as well as mammalian spinal plasticity mechanisms of central sensitization. Third, we explore recent evidence implicating epigenetic mechanisms in learning- and pain-related sensitization. This review illustrates the fundamental and functional overlay of the learning and memory field with the pain field which argues for homologous persistent plasticity mechanisms in response to sensitizing stimuli or injury across phyla.

mTOR signaling pathway in penile squamous cell carcinoma: pmTOR and peIF4E over expression correlate with aggressive tumor behavior

PURPOSE

Penile squamous cell carcinoma is a rare neoplasm associated with a high risk of metastasis and morbidity. There are limited data on the role of the mTOR signaling pathway in penile squamous cell carcinoma carcinogenesis and tumor maintenance. We assessed a possible role for mTOR signaling pathway activation as a potential predictive biomarker of outcome and a therapeutic target for penile cancer.

MATERIAL AND METHODS

A cohort of 67 patients diagnosed with invasive penile squamous cell carcinoma from 1987 to 2010 who had known HPV status were selected for study. Tissue microarrays were constructed with 67 primary penile squamous cell carcinomas, matched normal tissues and 8 lymph node metastases. Immunohistochemical staining was performed for p53, pmTOR, pERK, p4E-BP1, eIF4E and peIF4E. Expression was evaluated using a semiquantitative H-score on a scale of 0 to 300.

RESULTS

Expression of pmTOR, p4E-BP1, eIF4E and peIF4E was increased in penile tumors compared with matched adjacent normal tissues, indicating activation of the mTOR signaling pathway in penile tumorigenesis. Over expression of pmTOR, peIF4E and p53 was significantly associated with lymph node disease. peIF4E and p53 also correlated with a poor outcome, including recurrence, metastasis or disease specific death. In contrast, pERK and p4E-BP1 were associated with lower pT stages. pmTOR and intense p53 expression was associated with HPV negative tumors.

CONCLUSIONS

Activation of mTOR signaling may contribute to penile squamous cell carcinoma progression and aggressive behavior. Targeting mTOR or its downstream signaling targets, such as peIF4E, may be a valid therapeutic strategy.