Dust mite-derived Der f 3 activates a pro-inflammatory program in airway epithelial cells via PAR-1 and PAR-2

Protease activity of allergens has been suggested to be involved in the pathogenesis of allergic diseases. The major allergen Der f 3 from Dermatophagoides farinae harbors serine protease activity, but its immunopathogenesis remains unclear. This study aims to explore the effect of Der f 3 on the airway epithelial barrier and on the molecular pathways by which Der f 3 induces inflammation. RNA-seq was performed to identify differentially expressed genes in bronchial airway epithelial cells (AEC) between native Der f 3 and heat-inactivated (H) Der f 3, coupled with real-time PCR (RT-PCR) and ELISA for validation. Unlike other protease allergens such as that induce Th2-promoting alarmins (IL-25, IL-33, TSLP) in AECs, Der f 3 induced pro-inflammatory cytokines and chemokines including IL-6, IL-8 and GM-CSF, which are known to promote Th17 response. These pro-inflammatory mediators were induced by Der f 3 via the MAPK and NF-κB pathways as well as the store-operated calcium signaling. Gene silencing with small interfering RNA in A549 and BEAS-2B cells indicated that activation of AECs by Der f 3 was mainly dependent on protease-activated receptor 2 (PAR-2), while PAR-1 was also required for the full activation of AECs. Double knock-down of PAR-1 and PAR-2 largely impaired Der f 3-inducecd IL-8 production and subsequent signaling pathways. Our data suggest that Der f 3 induces pro-inflammatory mediators in human epithelial cell lines via the PARs-MAPK-NF-κB axis. Our results provide a molecular mechanism by which Der f 3 may trigger the Th17-skewed allergic response toward house dust mites.

Zearalenone Induces Estrogen-Receptor-Independent Neutrophil Extracellular Trap Release in Vitro

Zearalenone (ZEA) is a non-steroidal estrogenic mycotoxin synthesized in Fusarium species, mainly Fusarium graminearum and Fusarium culmorum, and it has strong estrogenic activity and causes genotoxic effects, reproductive disorders, and immunosuppressive effects. Neutrophil extracellular trap (NET) has been studied for many years. Initially, NET was considered a form of the innate response that combats invading microorganisms. However, NET is involved in a series of pathophysiological mechanisms, including thrombosis, tissue necrosis, autoinflammation, and even autoimmunity. We recently found that polymorphonuclear neutrophils response to ZEA exposure by undergoing NET formation. However, the molecular mechanisms involved in this process remain poorly characterized. Here, we analyze whether estrogen receptors (ERs) can affect NET formation after ZEA stimulation. The involvement of ERs is investigated with the selective ER antagonists. Moreover, we investigate the mechanisms of NET formation using immunofluorescence staining, fluorescence microplate, and western blot analysis. Our results show that ERs (ERα and ERβ) are not involved in ZEA-induced NET formation, but reactive oxygen species (ROS), extracellular signal-regulated kinase (ERK), and p38 are postulated to be involved. Specifically, we provide data demonstrating that ZEA-induced ROS may promote activation of ERK and p38 as well as subsequent NET release. We are the first to demonstrate this new mechanism of ZEA-induced NET formation, which may help in understanding the role of ZEA in overexposure diseases and provide a relevant basis for therapeutic applications.

Apoptotic effect of enterodiol, the final metabolite of edible lignans, in colorectal cancer cells

BACKGROUND

Enterodiol (END) is transformed by human intestinal bacteria from lignans contained in various whole-grain cereals, nuts, legumes, flaxseed, and vegetables. It is known to have several physiological effects, but its effects on mitogen-activated protein kinase (MAPK) signaling and apoptosis in colorectal cancer (CRC) cells have not yet been elucidated. We therefore investigated the effects of END on apoptosis in CRC cells and whether these effects are mediated via MAPK signaling.

RESULTS

Cell proliferation was decreased by END treatment in a time-dependent manner. In particular, END treatment resulted in an apoptosis rate of up to 40% in CT26 cells but showed no cytotoxicity toward RAW264.7 macrophages. Treatment with END also suppressed the migration of CRC cells in a concentration-dependent manner. The phosphorylation of extracellular signal-regulated kinase (ERK), jun N-terminal kinase (JNK), and p38 was down-regulated with END treatment. Furthermore, END decreased the expression levels of anti-apoptotic proteins in CRC cells.

CONCLUSION

Enterodiol inhibited the growth of CRC cells by controlling the MAPK signaling pathway involved in proliferation and apoptosis. These results demonstrate that END has an apoptotic effect in CRC cells. © 2018 Society of Chemical Industry.

Targeting the ERK Signaling Pathway in Melanoma

The discovery of the role of the RAS/RAF/MEK/ERK pathway in melanomagenesis and its progression have opened a new era in the treatment of this tumor. Vemurafenib was the first specific kinase inhibitor approved for therapy of advanced melanomas harboring BRAF-activating mutations, followed by dabrafenib and encorafenib. However, despite the excellent results of first-generation kinase inhibitors in terms of response rate, the average duration of the response was short, due to the onset of genetic and epigenetic resistance mechanisms. The combination therapy with MEK inhibitors is an excellent strategy to circumvent drug resistance, with the additional advantage of reducing side effects due to the paradoxical reactivation of the MAPK pathway. The recent development of RAS and extracellular signal-related kinases (ERK) inhibitors promises to add new players for the ultimate suppression of this signaling pathway and the control of pathway-related drug resistance. In this review, we analyze the pharmacological, preclinical, and clinical trial data of the various MAPK pathway inhibitors, with a keen interest for their clinical applicability in the management of advanced melanoma.

The GalNAc-T Activation (GALA) Pathway: Drivers and markers

The enzymes GALNTs add GalNAc sugar to Ser and Thr residues, forming the Tn glycan. GALNTs are activated by trafficking from Golgi to ER, a process driven by the Src kinase and negatively regulated by ERK8. This GALNTs activation (aka GALA) pathway induces high Tn levels and is a key driver of liver tumor growth. Recently, Tabak and colleagues have contested our previous data that EGF stimulation can induce GALNTs relocation. Here, we show that relocation induced by EGF is actually detectable in the very images acquired by Tabak et al. Furthermore, we show that over-expression of EGFR strongly enhances EGF-induced relocation and that EGFR appears required to drive relocation induced by ERK8 depletion. Direct co-localisation of GALNT with the ER marker Calnexin is observed after EGF stimulation. We furthermore propose that quantification of O-glycosylation of the ER resident protein PDIA4 provides a mean to quantify GALA independently of imaging. In sum, we demonstrate that the claimed non-reproducibility was due to experimental imaging conditions, that EGFR is indeed a driver of GALA and propose additional markers to facilitate the study of this pathway.

The ubiquitin ligase KBTBD8 regulates PKM1 levels via Erk1/2 and Aurora A to ensure oocyte quality

Tight control of energy metabolism is essential for normal cell function and organism survival. PKM (pyruvate kinase, muscle) isoforms 1 and 2 originate from alternative splicing of PKM pre-mRNA. They are key enzymes in oxidative phosphorylation and aerobic glycolysis, respectively, and are essential for ATP generation. The PKM1:PKM2 expression ratio changes with development and differentiation, and may also vary under metabolic stress and other conditions. Until now, there have been no reports about the function and regulation of PKM isozymes in oocytes. Here, we demonstrate that PKM1 or PKM2 depletion significantly disrupts ATP levels and mitochondrial integrity, and exacerbates free-radical generation and apoptosis in mouse oocytes. We also show that KBTBD8, a female fertility factor in the KBTBD ubiquitin ligase family, selectively regulates PKM1 levels through a signaling cascade that includes Erk1/2 and Aurora A kinases as intermediates. Finally, using RNA sequencing and protein network analysis, we identify several regulatory proteins that may be govern generation of mature PKM1 mRNA. These results suggest KBTBD8 affects PKM1 levels in oocytes via a KBTBD8→Erk1/2→Aurora A axis, and may also affect other essential processes involved in maintaining oocyte quality.

HIF-1α-derived cell-penetrating peptides inhibit ERK-dependent activation of HIF-1 and trigger apoptosis of cancer cells under hypoxia

Hypoxia is frequently encountered in the microenvironment of solid tumors. Hypoxia-inducible factors (HIFs), the main effectors of cell response to hypoxia, promote cancer cell survival and progression. HIF-1α, the oxygen-regulated subunit of HIF-1, is often correlated with oncogenesis and represents an attractive therapeutic target. We have previously reported that activation HIF-1α by ERK involves modification of two serine residues and masking of a nuclear export signal (NES), all inside a 43-amino acid domain termed ERK Targeted Domain (ETD). Overexpression of ETD variants including wild-type, phospho-mimetic (SE) or NES-less (IA) mutant forms caused HIF-1 inactivation in two hepatocarcinoma cell lines, while a phospho-deficient (SA) form was ineffective and acted as a sequence-specific negative control. To deliver these ETD forms directly into cancer cells, they were fused to the HIV TAT-sequence and produced as cell-permeable peptides. When the TAT-ETD peptides were added to the culture medium of Huh7 cells, they entered the cells and, with the exception of ETD-SA, accumulated inside the nucleus, caused mislocalization of endogenous HIF-1α to the cytoplasm, significant reduction of HIF-1 activity and inhibition of expression of specific HIF-1, but not HIF-2, gene targets under hypoxia. More importantly, transduced nuclear TAT-ETD peptides restricted migration, impaired colony formation and triggered apoptotic cell death of cancer cells grown under hypoxia, while they produced no effects in normoxic cells. These data demonstrate the importance of ERK-mediated activation of HIF-1 for low oxygen adaptation and the applicability of ETD peptide derivatives as sequence-specific HIF-1 and cancer cell growth inhibitors under hypoxia.

MhMAPK4 from Malus hupehensis Rehd. decreases cell death in tobacco roots by controlling Cd2+ uptake

Cadmium (Cd) induces cell death in plant roots. Mitogen-activated protein kinase (MAPK) plays a role in the regulation of cell death induced by Cd in plant roots. In this study, MhMAPK4 was isolated from the roots of Malus hupehensis. Subcellular localization showed that the MhMAPK4 protein was located in the cell membrane and cytoplasm and is a transmembrane protein that is characterized by hydrophily. The expression of MhMAPK4 in the roots of M. hupehensis was up-regulated by Cd sulfate and Cd chloride. Phenotypic comparison under Cd stress showed that the growth of wild-type (WT) tobacco was lower than the transgenic lines overexpressing MhMAPK4. The fresh weight and the root length of WT also was lower than that of the transgenic tobacco. The net Cd2+ influx in the tobacco roots was decreased by the overexpression of MhMAPK4, as was root Cd accumulation. The recovery time of the Cd2+ influx to stable state in the transgenic tobacco was also shorter than the WT. The expression of iron-regulated transporter 1 (NtIRT1) and natural resistance associated macrophage protein 5 (NtNRAMP5) was relatively low in the transgenic lines under Cd stress. Cell death and apoptosis in the tobacco roots was reduced following the overexpression of MhMAPK4. The activity of vacuolar processing enzyme (VPE) and the transcript level of VPE in the transgenic tobacco was lower than that of WT under Cd stress. In addition, the electrolyte leakage and malondialdehyde and hydrogen peroxide contents in the transgenic tobacco were lower than those of WT, whereas the antioxidant enzyme activity and expression were higher. These results suggest that MhMAPK4 regulates Cd accumulation by mediating Cd2+ uptake by the roots, and controls Cd-caused cell death by adjusting VPE activity.

Neurofibromin haploinsufficiency results in altered spermatogenesis in a mouse model of neurofibromatosis type 1

The fertility of men with neurofibromatosis 1 (NF1) is reduced. Despite this observation, gonadal function has not been examined in patients with NF1. In order to assess the role of reduced neurofibromin in the testes, we examined testicular morphology and function in an Nf1+/- mouse model. We found that although Nf1+/- male mice are able to reproduce, they have significantly fewer pups per litter than Nf1+/+ control males. Reduced fertility in Nf1+/- male mice is associated with disorganization of the seminiferous epithelium, with exfoliation of germ cells and immature spermatids into the tubule lumen. Morphometric analysis shows that these alterations are associated with decreased Leydig cell numbers and increased spermatid cell numbers. We hypothesized that hyper-activation of Ras in Nf1+/- males affects ectoplasmic specialization, a Sertoli-spermatid adherens junction involved in spermiation. Consistent with this idea, we found increased expression of phosphorylated ERK, a downstream effector of Ras that has been shown to alter ectoplasmic specialization, in Nf1+/- males in comparison to control Nf1+/+ littermates. These data demonstrate that neurofibromin haploinsufficiency impairs spermatogenesis and fertility in a mouse model of NF1.

Competition for Space Induces Cell Elimination through Compaction-Driven ERK Downregulation

The plasticity of developing tissues relies on the adjustment of cell survival and growth rate to environmental cues. This includes the effect of mechanical cues on cell survival. Accordingly, compaction of an epithelium can lead to cell extrusion and cell death. This process was proposed to contribute to tissue homeostasis but also to facilitate the expansion of pretumoral cells through the compaction and elimination of the neighboring healthy cells. However, we know very little about the pathways that can trigger apoptosis upon tissue deformation, and the contribution of compaction-driven death to clone expansion has never been assessed in vivo. Using the Drosophila pupal notum and a new live sensor of ERK, we show first that tissue compaction induces cell elimination through the downregulation of epidermal growth factor receptor/extracellular signal regulated kinase (EGFR/ERK) pathway and the upregulation of the pro-apoptotic protein Hid. Those results suggest that the sensitivity of EGFR/ERK pathway to mechanics could play a more general role in the fine tuning of cell elimination during morphogenesis and tissue homeostasis. Second, we assessed in vivo the contribution of compaction-driven death to pretumoral cell expansion. We found that the activation of the oncogene Ras in clones can downregulate ERK and activate apoptosis in the neighboring cells through their compaction, which eventually contributes to Ras clone expansion. The mechanical modulation of EGFR/ERK during growth-mediated competition for space may contribute to tumor progression.

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Caspase activity in Drosophila pupal notum is regulated by EGFR/ERK and hid

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EGFR/ERK can be activated or downregulated by tissue stretching or compaction

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Cell compaction near fast-growing clones downregulates ERK and triggers cell death

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Compaction-driven ERK downregulation promotes fast-growing clone expansion

Permethrin, a pyrethroid insecticide, regulates ERK1/2 activation through membrane depolarization-mediated pathway in HepG2 hepatocytes

Permethrin is a pyrethroid insecticide that acts thru membrane depolarization and is known to disrupt calcium levels in neurons. Disrupted calcium homeostasis is linked to oxidative stress as well as many other cellular mis-functions and permethrin has been reported to disrupt lipid and glucose metabolism in animals and mammalian cell models. It is not known, however, if permethrin influences calcium levels and its associated cellular mechanisms in liver cells. Thus, the goal of the current study was to investigate the mechanisms of permethrin on calcium-mediated cellular signaling pathway, particularly on activation of extracellular signal-related kinase (ERK1/2 or p42/p44) using human hepatocytes, HepG2. The current results showed that permethrin treatment induced oxidative stress and phosphorylation of ERK1/2, which were dependent upon voltage-sensitive sodium channels (VSSC). It was further determined that permethrin-induced ERK1/2 activation was mediated by the metabotropic glutamate receptors (mGluRs)-phosphoinositide phospholipase C (PLC)-protein kinase C (PKC) pathway, but not by changes of intracellular calcium or ER stress-mediated mechanisms.

Porcine reproductive and respiratory syndrome virus induces interleukin-1β through MyD88/ERK/AP-1 and NLRP3 inflammasome in microglia

Porcine reproductive and respiratory syndrome virus (PRRSV) infection which caused severe reproductive failure and respiratory disorders in swine is accompanied with severe nervous symptoms. Our previous studies demonstrated that microglia, the resident innate immune cells in central nervous system (CNS), could support PRRSV infection and replication in vitro. And PRRSV infection led to the increased expressions of large amounts of proinflammatory cytokines and chemokines which contributed to neuropathogenesis of PRRSV. Interleukin-1β (IL-1β) is one of the increased proinflammatory cytokines, which possesses diverse functions in immune response upon virus infection, including activation of innate immune and modulation of adaptive immune responses. Importantly, considerable evidences indicated that 1L-1β is involved in neuronal injury. Here, we demonstrated that PRRSV infection up-regulated IL-1β expression at both the mRNA and protein levels in microglia in a dose-dependent manner. Myeloid differentiation primary response gene 88 (MyD88), extracellular signal-regulated kinase1/2 (ERK) and activator protein 1 (AP-1) were involved in PRRSV induced IL-1β production in microglia. Moreover, NOD-like receptor protein 3 (NLRP3) inflammasome is activated by PRRSV in microglia, which is required for IL-1β secretion. Taken together, our data indicated that PRRSV infection could induce IL-1β up-regulation, which was likely mediated by MyD88/ERK/AP-1 and NLRP3 inflammasome. These findings will provide new insights into the molecular mechanisms of IL-1β production and some implications for neuropathogenesis of PRRSV.

Tanshinone IIA Attenuates Insulin Like Growth Factor 1 -Induced Cell Proliferation in PC12 Cells through the PI3K/Akt and MEK/ERK Pathways

The insulin like growth factor 1 (IGF-1) and its receptor (IGF-1R) facilitate tumor proliferation and progression. Tanshinone IIA (TSN) is an active diterpene quinone isolated from the roots of the herbal plant Salvia miltiorrhiza. TSN inhibits the proliferation of various types of cancer cells but its role in the IGF-1R-induced proliferation of pheochromocytoma (PC12) cells and the potential mechanisms are largely unknown. This study aims to investigate the anti-proliferative effect of TSN in PC12 cells and its role on IGF-1R signaling transduction. PC12 cells were treated with IGF-1 with or without TSN, methyl thiazolytetrazolium (MTT) assay, and cell counting kit-8 and flow cytometry were used to evaluate the proliferation of PC12 cells. The role of TSN on the apoptosis of PC12 cells were detected by flow cytometry as well. The effects of TSN and IGF-1 on the phosphorylation of IGF-1R, protein kinase B (Akt), extracellular-signal related kinase 1/2 (ERK1/2) and other downstream targets were analyzed by Western blotting analysis. Our results showed that IGF-1 promoted the growth of PC12 cells in a dose-dependent manner and increased the phosphorylation of IGF-1R, whereas TSN attenuated the effect of IGF-1. Interestingly, TSN did not induce cell apoptosis in PC12 cells. Moreover, TSN attenuated the phosphorylation of Akt and ERK1/2 induced by IGF-1, and the phosphorylation of glycogen synthase kinase-3β, forkhead box O3a (FOXO3a) and c-Raf were also inhibited by TSN. Furthermore, TSN inhibited cell growth induced by IGF-1 and blocked the activation of IGF-1R in SH-SY5Y cells. Taken together, TSN has an inhibitory effect on the proliferation of PC12 cells via down-regulation of the phosphorylated IGF-1R and its downstream signaling.

Synephrine Hydrochloride Suppresses Esophageal Cancer Tumor Growth and Metastatic Potential through Inhibition of Galectin-3-AKT/ERK Signaling

A library consisting of 429 food-source compounds was used to screen the natural products with anticancer properties in esophageal squamous cell carcinoma (ESCC). We demonstrated for the first time that synephrine, an active compound isolated from leaves of citrus trees, markedly suppressed cell proliferation (inhibition rate with 20 μM synephrine at day 5:71.1 ± 5.8% and 75.7 ± 6.2% for KYSE30 and KYSE270, respectively) and colony formation (inhibition rate with 10 μM synephrine: 86.5 ± 5.9% and 82.3 ± 4.5% for KYSE30 and KYSE270, respectively), as well as migration (inhibition rate with 10 μM synephrine: 76.9 ± 4.4% and 62.2 ± 5.8% for KYSE30 and KYSE270, respectively) and invasion abilities (inhibition rate with 10 μM synephrine: 73.3 ± 7.5% and 75.3 ± 3.4% for KYSE30 and KYSE270, respectively) of ESCC cells in a dose-dependent manner, without significant toxic effect on normal esophageal epithelial cells. Mechanistically, quantitative proteomics and bioinformatics analyses were performed to explore the synephrine-regulated proteins. Western blot and qRT-PCR data indicated that synephrine may downregulate Galectin-3 to inactivate AKT and ERK pathways. In addition, we found that the sensitivity of ESCC to fluorouracil (5-FU) could be enhanced by synephrine. Furthermore, in vivo experiments showed that synephrine had significant antitumor effect on ESCC tumor xenografts in nude mice (inhibition rate with 20 mg/kg synephrine is 61.3 ± 20.5%) without observed side effects on the animals. Taken together, synephrine, a food-source natural product, may be a potential therapeutic strategy in ESCC.

Sphingosine-1-phosphate signaling in Leishmania donovani infection in macrophages

BACKGROUND

Sphingosine-1-phosphate (S1P) is a crucial regulator of a wide array of cellular processes, such as apoptosis, cell proliferation, migration, and differentiation, but its role in Leishmania donovani infection is unknown.

METHODOLOGY/ PRINCIPAL FINDINGS

In the present study, we observed that L. donovani infection in THP-1 derived macrophages (TDM) leads to decrease in the expression of S1pr2 and S1pr3 at mRNA level. We further observed that Leishmania infection inhibits the phosphorylation of sphingosine kinase 1 (sphK1) in a time-dependent manner. Exogenous S1P supplementation decreases L. donovani induced ERK1/2 phosphorylation and increases p38 phosphorylation in TDM, resulting in a decrease in the intracellular parasite burden in a dose-dependent manner. On the other hand, sphK inhibition by DMS increases ERK1/2 phosphorylation leading to increased IL-10 and parasite load. To gain further insight, cytokines expression were checked in S1P supplemented TDM and we observed increase in IL-12, while decrease IL-10 expression at mRNA and protein levels. In addition, treatment of antagonist of S1PR2 and S1PR3 such as JTE-013 and CAY10444 respectively enhanced Leishmania-induced ERK1/2 phosphorylation and parasite load.

CONCLUSIONS

Our overall study not only reports the significant role of S1P signaling during L. donovani infection but also provides a novel platform for the development of new drugs against Leishmaniasis.

Requirement of ClC-3 in G0/G1 to S Phase Transition Induced by IGF-1 via ERK1/2-Cyclins Cascade in Multiple Myeloma Cells

BACKGROUND

ClC-3 is involved in the proliferation and migration of several cancer cells. However, ClC-3 expression and its role of cell-cycle control in multiple myeloma (MM) has not yet been investigated.

METHODS

MM cells were treated with different concentrations of IGF (30, 100, 300 ng/mL), and their proliferation was examined by CCK-8. The effects of ClC-3 on cell cycle progression was detected by flow cytometry. Western blot was used to analyze the relative levels of ClC3, CD138, P21, P27, CDK, p-Erk1/2, and t-Erk1/2 protein expression. Transfection of RPMI8226 with gpClC-3 cDNA and siRNA alters the expression of ClC-3.

RESULTS

We compared the expression of ClC-3 in primary myeloma cells and in MM cell lines (U266 and RPMI8266) with that in normal plasma cells (PCs) from normal subjects and found that myeloma cells from patients and MM cell lines had significantly higher expression of ClC-3. Additionally, silencing of ClC-3 with the small interfering RNA (siRNA) that targets human ClC-3 decreased proliferation of RPMI8226 after IGF-1 treatment and slowed cell cycle progression from G0/G1 to S phase, which was associated with diminished phosphorylation of ERK1/2, down-expression of cyclin E, cyclin D1 and up-regulation of p27 and p21. By contrast, overexpression of ClC-3 potentiated cell proliferation induced by IGF-1, raised the percentage of S phase cells, enhanced phosphorylation of ERK1/2, downregulated p27 and p21 and upregulated cyclin E and cyclin D1.

CONCLUSIONS

ClC-3 accelerated G0/G1 to S phase transition in the cell cycle by modulating ERK1/2 kinase activity and expression of G1/S transition related proteins, making ClC-3 an attractive therapeutic target in MM.

Expression variation and covariation impair analog and enable binary signaling control

Due to noise in the synthesis and degradation of proteins, the concentrations of individual vertebrate signaling proteins were estimated to vary with a coefficient of variation (CV) of approximately 25% between cells. Such high variation is beneficial for population-level regulation of cell functions but abolishes accurate single-cell signal transmission. Here, we measure cell-to-cell variability of relative protein abundance using quantitative proteomics of individual Xenopus laevis eggs and cultured human cells and show that variation is typically much lower, in the range of 5-15%, compatible with accurate single-cell transmission. Focusing on bimodal ERK signaling, we show that variation and covariation in MEK and ERK expression improves controllability of the percentage of activated cells, demonstrating how variation and covariation in expression enables population-level control of binary cell-fate decisions. Together, our study argues for a control principle whereby low expression variation enables accurate control of analog single-cell signaling, while increased variation, covariation, and numbers of pathway components are required to widen the stimulus range over which external inputs regulate binary cell activation to enable precise control of the fraction of activated cells in a population.

Identification and functional analysis of a stress-responsive MAPK15 in Entamoeba invadens

E. histolytica, a protozoan parasite is the causative agent of amoebiasis in human beings. It exists in two different forms - the motile trophozoite form which undergoes encystation under starvation conditions to form the non-motile, osmotically resistant cyst form. Cellular stresses stimulate several signaling cascades which assist the parasite in counter-attacking such conditions thereby, promoting cell survival. To study the stress-associated pathways activated during encystation, we have used Entamoeba invadens, a reptilian parasite as a model organism because of its ability to undergo encystation under in vitro conditions. In this study, we have identified a stress-responsive MAPK which gets upregulated under different stress conditions, including encystation. Sequence analysis and phylogenetic classification show that the MAPK belongs to the atypical MAPK15 family (henceforth, named EiMAPK15), which does not require an upstream MAPKK for its phosphorylation and activation. The in vitro kinase activity of recombinant EiMAPK15 exhibits its auto-phosphorylation ability. Immunolocalization studies reveal that the protein is mainly cytosolic under normal growing conditions but gets translocated into the nucleus under stress conditions. Knockdown of EiMAPK15 using double-stranded RNA was found to reduce the expression of other encystation-specific genes which in turn, resulted in the decline of the overall encystation efficiency of the cells. Overall, the present work has laid the platform for further characterization of this important MAPK gene in Entamoeba invadens.

Differential expression of miRNA in Carassius auratus gibelio in response to cyprinid herpesvirus 2 infection

miRNAs (microRNAs), a small endogenous non-coding RNAs, play crucial roles in post-transcriptional regulator of genes expression in various biological processes. Cyprinid Herpesvirus-2 (CyHV-2) is a highly pathogenic member of the alloherpesviridae that causes acute mass mortalities in populations of Carassius auratus gibelio and Carassius auratus auratus. However, the molecular mechanisms underlying the pathogenicity of CyHV-2 have not been fully determined. Here, miRNA expression profiles were identified via high-throughput sequencing in the kidney of Carassius auratus gibelio infected or uninfected with CyHV-2. The results showed that a total number of 840 known miRNAs and 48 putative novel miRNAs were identified. Then we compared the expression patterns of miRNAs in the two groups, 23 miRNAs were significantly differentially expressed between the uninfected and infected groups. Further, the expressions of 23 miRNAs were validated by quantitative reverse transcription polymerase chain reaction (qRT-PCR), the results showed that the expression patterns were basically the same with the sequencing. Prediction of targets of differentially expressed miRNAs revealed that the miRNAs participated in the regulation of multiple immune-related signaling pathways, including Chemokine signaling pathway, Apoptosis, Jak-STAT signaling pathway and MAPK signaling pathway. Taken together, these data provide insight into the regulatory mechanisms of miRNA and highlight the function of miRNA in the regulation of the immune response during the interaction between host and virus pathogens.

COP1/DET1/ETS axis regulates ERK transcriptome and sensitivity to MAPK inhibitors

Aberrant activation of MAPK signaling leads to the activation of oncogenic transcriptomes. How MAPK signaling is coupled with the transcriptional response in cancer is not fully understood. In 2 MAPK-activated tumor types, gastrointestinal stromal tumor and melanoma, we found that ETV1 and other Pea3-ETS transcription factors are critical nuclear effectors of MAPK signaling that are regulated through protein stability. Expression of stabilized Pea3-ETS factors can partially rescue the MAPK transcriptome and cell viability after MAPK inhibition. To identify the players involved in this process, we performed a pooled genome-wide RNAi screen using a fluorescence-based ETV1 protein stability sensor and identified COP1, DET1, DDB1, UBE3C, PSMD4, and COP9 signalosome members. COP1 or DET1 loss led to decoupling between MAPK signaling and the downstream transcriptional response, where MAPK inhibition failed to destabilize Pea3 factors and fully inhibit the MAPK transcriptome, thus resulting in decreased sensitivity to MAPK pathway inhibitors. We identified multiple COP1 and DET1 mutations in human tumors that were defective in the degradation of Pea3-ETS factors. Two melanoma patients had de novo DET1 mutations arising after vemurafenib treatment. These observations indicate that MAPK signaling-dependent regulation of Pea3-ETS protein stability is a key signaling node in oncogenesis and therapeutic resistance to MAPK pathway inhibition.

Tumor-derived lactate induces M2 macrophage polarization via the activation of the ERK/STAT3 signaling pathway in breast cancer

Tumor-associated macrophages (TAM) are prominent components of tumor microenvironment (TME) and capable of promoting cancer progression. However, the mechanisms for the formation of M2-like TAMs remain enigmatic. Here, we show that lactate is a pivotal oncometabolite in the TME that drives macrophage M2-polarization to promote breast cancer proliferation, migration, and angiogenesis. In addition, we identified that the activation of ERK/STAT3, major signaling molecules in the lactate signaling pathway, deepens our molecular understanding of how lactate educates TAMs. Moreover, suppression of ERK/STAT3 signaling diminished tumor growth and angiogenesis by abolishing lactate-induced M2 macrophage polarization. Finally, research data of the natural compound withanolide D provide evidence for ERK/STAT3 signaling as a potential therapeutic strategy for the prevention and treatment of breast cancer. These findings suggest that the lactate-ERK/STAT3 signaling pathway is a driver of breast cancer progression by stimulating macrophage M2-like polarization and reveal potential new therapeutic targets for breast cancer treatment.

Forskolin improves sensitivity to doxorubicin of triple negative breast cancer cells via Protein Kinase A-mediated ERK1/2 inhibition

Triple negative breast cancer (TNBC) is an invasive, metastatic, highly aggressive tumor. Cytotoxic chemotherapy represents the current treatment for TNBC. However, relapse and chemo-resistance are very frequent. Therefore, new therapeutic approaches that are able to increase the sensitivity to cytotoxic drugs are needed. Forskolin, a natural cAMP elevating agent, has been used for several centuries in medicine and its safeness has also been demonstrated in modern studies. Recently, forskolin is emerging as a possible novel molecule for cancer therapy. Here, we investigate the effects of forskolin on the sensitivity of MDA-MB-231 and MDA-MB-468 TNBC cells to doxorubicin through MTT assay, flow cytometry-based assays (cell-cycle progression and cell death), cell number counting and immunoblotting experiments. We demonstrate that forskolin strongly enhances doxorubicin-induced antiproliferative effects by cell death induction. Similar effects are observed with IBMX and isoproterenol cAMP elevating agents and 8-Br-cAMP analog, but not by using 8-pCPT-2'-O-Me-cAMP Epac activator. It is important to note that the forskolin-induced potentiation of sensitivity to doxorubicin is accompanied by a strong inhibition of ERK1/2 phosphorylation, is mimicked by ERK inhibitor PD98059 and is prevented by pre-treatment with Protein Kinase A (PKA) and adenylate cyclase inhibitors. Altogether, our data indicate that forskolin sensitizes TNBC cells to doxorubicin via a mechanism depending on the cAMP/PKA-mediated ERK inhibition. Our findings sustain the evidence of anticancer activity mediated by forskolin and encourage the design of future in-vivo/clinical studies in order to explore forskolin as a doxorubicin sensitizer for possible use in TNBC patients.

Somatic NRAS mutation in patient with generalized lymphatic anomaly

Generalized lymphatic anomaly (GLA or lymphangiomatosis) is a rare disease characterized by a diffuse proliferation of lymphatic vessels in skin and internal organs. It often leads to progressive respiratory failure and death, but its etiology is unknown. Here, we isolated lymphangiomatosis endothelial cells from GLA tissue. These cells were characterized by high proliferation and survival rates, but displayed impaired capacities for migration and tube formation. We employed whole exome sequencing to search for disease-causing genes and identified a somatic mutation in NRAS. We used mouse and zebrafish model systems to initially evaluate the role of this mutation in the development of the lymphatic system, and we studied the effect of drugs blocking the downstream effectors, mTOR and ERK, on this disease.

Regulation of human mitogen-activated protein kinase 15 (extracellular signal-regulated kinase 7/8) and its functions: A recent update

Mitogen-activated protein kinase 15 (MAPK15), originally also known as extracellular signal-regulated kinase 7/8, is the most recently identified atypical MAPK and the least studied so far. Examinations of the role of MAPK15 in various cell lines and model systems indicate that MAPK15 participates in a variety of cellular activities such as promoting cell proliferation, cell transformation, and apoptosis; stimulating autophagy; regulating cell division, ciliogenesis, and protein secretion; and maintaining genome stability. As multiple roles of MAPK15 were observed among these studies, therefore, it remains unclear whether MAPK15 acts as a proto-oncogene or tumor suppressor. Here, the recent literature on human MAPK15 and the resulting functions will be discussed.

Convergence of BMI1 and CHD7 on ERK Signaling in Medulloblastoma

We describe molecular convergence between BMI1 and CHD7 in the initiation of medulloblastoma. Identified in a functional genomic screen in mouse models, a BMI1High;CHD7Low expression signature within medulloblastoma characterizes patients with poor overall survival. We show that BMI1-mediated repression of the ERK1/2 pathway leads to increased proliferation and tumor burden in primary human MB cells and in a xenograft model, respectively. We provide evidence that repression of the ERK inhibitor DUSP4 by BMI1 is dependent on a more accessible chromatin configuration in G4 MB cells with low CHD7 expression. These findings extend current knowledge of the role of BMI1 and CHD7 in medulloblastoma pathogenesis, and they raise the possibility that pharmacological targeting of BMI1 or ERK may be particularly indicated in a subgroup of MB with low expression levels of CHD7.