JAK-STAT pathway modulates the roles of iNOS and COX-2 in the cytoprotection of early phase of hydrogen peroxide preconditioning against apoptosis induced by oxidative stress

Apigenin: Molecular Mechanisms and Therapeutic Potential against Cancer Spreading

Due to its propensity to metastasize, cancer remains one of the leading causes of death worldwide. Thanks in part to their intrinsic low cytotoxicity, the effects of the flavonoid family in the prevention and treatment of various human cancers, both in vitro and in vivo, have received increasing attention in recent years. It is well documented that Apigenin (4',5,7-trihydroxyflavone), among other flavonoids, is able to modulate key signaling molecules involved in the initiation of cancer cell proliferation, invasion, and metastasis, including JAK/STAT, PI3K/Akt/mTOR, MAPK/ERK, NF-κB, and Wnt/β-catenin pathways, as well as the oncogenic non-coding RNA network. Based on these premises, the aim of this review is to emphasize some of the key events through which Apigenin suppresses cancer proliferation, focusing specifically on its ability to target key molecular pathways involved in angiogenesis, epithelial-to-mesenchymal transition (EMT), maintenance of cancer stem cells (CSCs), cell cycle arrest, and cancer cell death.

miR-98-5p Prevents Hippocampal Neurons from Oxidative Stress and Apoptosis by Targeting STAT3 in Epilepsy in vitro

Purpose

Epilepsy is a serious mental disease, for which oxidative stress and hippocampal neuron death after seizure is crucial. Numerous miRNAs are involved in epilepsy. However, the function of miR-98-5p in oxidative stress and hippocampal neuron death after seizure is unclear, which is the purpose of current study.

Methods

Magnesium ion (Mg2+)-free solution was used to establish the in vitro epilepsy model in hippocampal neurons. Oxidative stress was exhibited by measuring malondialdehyde (MDA) level and superoxide Dismutase (SOD) activity using enzyme-linked immune sorbent assay (ELISA) kits. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and flow cytometry were applied for the examination of neuron viability and apoptosis, respectively. Quantitative reverse-transcription polymerase chain reaction (qRT-PCR) and Western blot were used to evaluate the mRNA and protein levels of miR-98-5p and signal transducer and activator of transcription (STAT3), respectively. The relationship between miR-98-5p and STAT3 was predicted by TargetScan 7.2, and identified by dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay.

Results

miR-98-5p was decreased in the in vitro epileptic model of hippocampal neurons induced by Mg2+-free solution, whose overexpression rescued oxidative stress and neuron apoptosis in epileptic model. Moreover, overexpression of STAT3, one downstream target of miR-98-5p, partially eliminated the effects of miR-98-5p mimic.

Conclusion

We shed lights on a pivotal mechanism of miR-98-5p in regulating neuron oxidative stress and apoptosis after seizures, providing potential biomarkers for the diagnosis of epilepsy and therapeutic targets for the treatment of epilepsy.

AG1024, an IGF-1 receptor inhibitor, ameliorates renal injury in rats with diabetic nephropathy via the SOCS/JAK2/STAT pathway

Insulin-like-growth factor-1 (IGF-1) is the ligand for insulin-like growth factor-1 receptor (IGF-1R), and the roles of IGF-1/IGF-1R in diabetic nephropathy (DN) are well-characterized previously. However, the biological functions of AG1024 (an IGF-1R inhibitor) in DN remain unknown. This study investigates the roles and related mechanisms of AG-1024 in DN. The experimental DN was established via intraperitoneal injection of streptozotocin, and STZ-induced diabetic rats were treated with AG1024 (20 mg/kg/day) for 8 weeks. The 24 h proteinuria, blood glucose level, serum creatinine, and blood urea nitrogen were measured for biochemical analyses. The increase in 24 h proteinuria, blood glucose level, serum creatinine, and blood urea of DN rats were conspicuously abated by AG1024. After biochemical analyses, the renal tissue specimens were collected, and as revealed by hematoxylin and eosin staining and Masson staining, AG-1024 mitigated typical renal damage and interstitial fibrosis in DN rats. Then, the anti-inflammatory effect of AG-1024 was assessed by western blotting and ELISA. Mechanistically, AG-1024 upregulated SOCS1 and SOCS3 expression and decreased phosphorylated JAK2, STAT1, and STAT3, as shown by western blotting. Collectively, AG-1024 (an IGF-1R inhibitor) ameliorates renal injury in experimental DN by attenuating renal inflammation and fibrosis via the SOCS/JAK2/STAT pathway.

Immune regulation mediated by JAK/STAT signaling pathway in hemocytes of Pacific white shrimps, Litopenaeus vannamei stimulated by lipopolysaccharide

To understand the regulatory mechanism of Janus kinase/Signal Transducers and Activators of Transcription (JAK/STAT) signaling pathway on the immune system of the Pacific white shrimp, Litopenaeus vannamei, RNA interference technique was used to investigate the effects of JAK/STAT signaling pathway on the immune response of hemocyte in Litopenaeus vannamei stimulated by lipopolysaccharide (LPS). The results showed that 1) after 6 h of LPS stimulation, the expression levels of immune genes in hemocyte were significantly up-regulated (P < 0.05), the immune defense ability (hemocyte number, phagocytosis rate, hemagglutination activity, bacteriolytic activity, antibacterial activity, prophenoloxidase system activity) and the hemocyte antioxidant ability were significantly higher than the control group, especially at 12 h. 2) After 48 h of STAT gene interference, the expression levels of immune genes in hemocytes were significantly down-regulated, and the immune defense ability (hemocyte count, phagocytosis rate, plasma agglutination activity, lysozyme activity, antibacterial activity, proPO system activity) and the antioxidant ability were reduced and significantly lower than control. Concurrently, after LPS stimulation, the immune indexes were significantly up-regulated at 12 h to the maximum but was still lower the undisturbed LPS group. These results indicate that JAK/STAT signaling pathway is involved in the immune regulation mechanism of L. vannamei against LPS stimulation through positive regulation of cellular immune and humoral immune. These results provide a basis for further research on the role and status of JAK/STAT signaling pathway in the immune defense of crustaceans.

Dendrobium nobile Alkaloids Protects against H2O2-Induced Neuronal Injury by Suppressing JAK-STATs Pathway Activation in N2A Cells

The purpose of this study was to investigate the preventive effect and mechanism of Dendrobium alkaloids (DNLA) on oxidative stress-related death in neuronal cells. Our results demonstrated that DNLA has a direct neuroprotective effect through oxidative stress in N2A cells induced by hydrogen peroxide (H₂O₂). CCK8, lactate dehydrogenase (LDH), intracellular Ca²⁺, intracellular reactive oxygen species (ROS), and mitochondrial membrane potential (MMP) were used to evaluate the mechanism of DNLA neutralization by H₂O₂-induced injury. Results presented in the paper indicate that treatment with DNLA (35 ng/mL) significantly attenuated decreases in cell viability, release of LDH, and apoptosis after H₂O₂-induced neuronal injury. Furthermore, DNLA significantly reduced intracellular Ca²⁺ up-regulation, ROS production, and inhibited mitochondrial depolarization. Moreover, DNLA treatment significantly downregulated expressions of interleukin (IL)-1β, tumor necrosis factor (TNF)-α, IL-6, nitric oxide synthase, janus kinase-signal transducer and activators of transcription (JAK-STATs) signaling in N2A cells, all of which were H₂O₂-induced. Taken together, our findings suggested that DNLA may inhibit the expression of pro-inflammatory and pro-apoptotic factors by blocking JAK-STATs signaling after oxidative stress injury. This research provides a potential experimental basis for further application of DNLA to prevent various human nervous system diseases caused by oxidative stress.

Phosphatase SHP1 impedes mesenchymal stromal cell immunosuppressive capacity modulated by JAK1/STAT3 and P38 signals

Background

Mesenchymal stromal cells (MSCs) are multiple stromal cells existing in various tissues and have already been employed in animal models and clinical trials to treat immune disorders through potent immunosuppressive capacity. Our previous reports have suggested that MSC immunosuppression is not intrinsic but is acquired upon combined inflammatory cytokine treatment. However, the understanding of detailed molecular mechanisms involved in MSC immunomodulation remains incomplete.

Results

In the study, we report that MSCs derived from viable motheaten (me^v) mice, with deficiency in SH2 domain-containing phosphatase-1 (SHP1), exhibited remarkable increased suppressive effect on activated splenocyte proliferation. Consistently, when MSCs were treated with combined inflammatory cytokines, SHP1-deficient MSCs produced dramatically more iNOS expression compared with wild-type MSCs. SHP1 was found to suppress the phosphorylation of JAK1/STAT3 and P38 signals. The classical animal model of concanavalin A (ConA)-induced liver injury was applied to examine the role of SHP1 in modulation MSC-therapeutic effect in vivo. Consistent with the results in vitro, SHP1-deficient MSCs exhibited dramatically more effective protection against ConA-induced hepatitis, compared to WT MSCs.

Conclusion

Taken together, our study reveals a possible role for SHP1 in modulation of MSC immunosuppression regulated by JAK1/STAT3 and P38 signals.

Protective effect of Cordyceps militaris against hydrogen peroxide-induced oxidative stress in vitro

BACKGROUND/OBJECTIVES

Excessive production of reactive oxygen species (ROS) such as hydroxyl (·OH), nitric oxide (NO), and hydrogen peroxide (H2O2) is reported to induce oxidative stress. ROS generated by oxidative stress can potentially damage glial cells in the nervous system. Cordyceps militaris (CM), a kind of natural herb widely found in East Asia. In this study, we investigated the free radical scavenging activity of the CM extract and its neuroprotective effects in H2O2-induced C6 glial cells.

MATERIALS/METHODS

The ethanol extract of CM (100-1,000 µg/mL) was used to measure DPPH, ·OH, and NO radical scavenging activities. In addition, hydrogen peroxide (H2O2)-induced C6 glial cells were treated with CM at 0.5-2.5 µg/mL for measurement of cell viability, ROS production, and protein expression resulting from oxidative stress.

RESULTS

The CM extract showed high scavenging activities against DPPH, ·OH, and NO radicals at concentration of 1,000 µg/mL. Treatment of CM with H2O2-induced oxidative stress in C6 glial cells significantly increased cell viability, and decreased ROS production. Cyclooxygenase-2 and inducible nitric oxide synthase protein expression was down-regulated in CM-treated groups. In addition, the protein expression level of phospho-p38 mitogen-activated protein kinase (p-p38 MAPK), phospho-c-Jun N-terminal kinase (p-JNK), and phospho-extracellular regulated protein kinases (p-ERK) in H2O2-induced C6 glial cells was down-regulated upon CM administration.

CONCLUSION

CM exhibited radical scavenging activity and protective effect against H2O2 as indicated by the increased cell viability, decreased ROS production, down-regulation of inflammation-related proteins as well as p-p38, p-JNK, and p-ERK protein levels. Therefore, we suggest that CM could play the protective role from oxidative stress in glial cells.

CRISPR/Cas9 Editing of Glia Maturation Factor Regulates Mitochondrial Dynamics by Attenuation of the NRF2/HO-1 Dependent Ferritin Activation in Glial Cells

Microglial cells are brain specific professional phagocytic immune cells that play a crucial role in the inflammation- mediated neurodegeneration especially in Parkinson's disease (PD) and Alzheimer's disease. Glia maturation factor (GMF) is a neuroinflammatory protein abundantly expressed in the brain. We have previously shown that GMF expression is significantly upregulated in the substantia nigra (SN) of PD brains. However, its possible role in PD progression is still not fully understood. The Clustered-Regularly Interspaced Short Palindromic Repeats (CRISPR)-CRISPR Associated (Cas) protein9 (CRISPR/Cas9) system is a simple, rapid and often extremely efficient gene editing tool at desired loci, enabling complete gene knockout or homology directed repair. In this study, we examined the effect of GMF editing by using the CRISPR/Cas9 technique in BV2 microglial cells (hereafter referred to as BV2-G) on oxidative stress and nuclear factor erythroid 2-related factor 2 (NRF2)/Hemeoxygenase1 (HO-1)-dependent ferritin activation after treatment with (1-methyl-4-phenylpyridinium) MPP⁺. Knockout of GMF in BV2-G cells significantly attenuated oxidative stress via reduced ROS production and calcium flux. Furthermore, deficiency of GMF significantly reduced nuclear translocation of NRF2, which modulates HO-1 and ferritin activation, cyclooxygenase 2 (COX2) and nitric oxide synthase 2 (NOS2) expression in BV2 microglial cells. Lack of GMF significantly improved CD11b and CD68 positive microglial cells as compared with untreated cells. Our results also suggest that pharmacological and genetic intervention targeting GMF may represent a promising and a novel therapeutic strategy in controlling Parkinsonism by regulating microglial functions. Targeted regulation of GMF possibly mediates protein aggregation in microglial homeostasis associated with PD progression through regulation of iron metabolism by modulating NRF2-HO1 and ferritin expression.

Carboxymethyl-chitosan attenuates inducible nitric oxide synthase and promotes interleukin-10 production in rat chondrocytes

Osteoarthritis (OA) is a common age-related degenerative joint disease, which is caused by the breakdown of joint cartilage and the underlying bone. Carboxymethyl (CM)-chitosan is a soluble derivative of chitosan that has similar physicochemical properties to the extracellular proteoglycans identified in hyaline cartilage. Previous studies have demonstrated that CM-chitosan serves a protective role in a rabbit OA model. The aim of the present study was to investigate the effect of CM-chitosan on NO production and inflammation through its upregulation of interleukin (IL)-10, and the activation of the janus kinase (JAK)/signal transducer and activator of transcription (STAT)/suppressor of cytokine signaling (SOCS) signaling pathway. In the present study primary rat chondrocytes were induced to inflammation with 2 µg/ml lipopolysaccharide. The cells were subsequently subjected to increasing concentrations of CM-chitosan (50, 100 and 200 µg/ml) and the relative mRNA and protein expression of inducible nitric oxide synthase (iNOS), IL-10, JAK1, STAT3 and SOCS3 were measured by RT-qPCR and western blot analysis respectively. The results revealed that CM-chitosan attenuated inflammation by significantly reducing iNOS expression and upregulating the anti-inflammatory cytokine IL-10 in a dose-dependent manner (P<0.05). The expression of JAK1, STAT3 and SOCS3 were also significantly upregulated by CM-chitosan (all P<0.05). The protective role of CM-chitosan against NO production was due to its upregulation of IL-10 and its activation of the JAK/STAT/SOCS signaling pathway.

Prim-O-glucosylcimifugin Attenuates Lipopolysaccharideinduced Inflammatory Response in RAW 264.7 Macrophages

BACKGROUND

Radix Saposhnikoviae (RS) exerts anti-inflammatory, analgesic, antipyretic, antioxidation effects and has been used in traditional Chinese medicine to treat common colds, headache, and rheumatoid arthritis. Prim-O-glucosylcimifugin (POG) is the highest content chromone and one of the major active constituents in RS.

OBJECTIVE

The study was aimed to explore the anti-inflammation effects of POG in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages.

MATERIALS AND METHODS

Cell viability was detected by Cell Counting Kit-8 assay. Production of nitric oxide (NO), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and IL-6 was assessed by enzyme-linked immunosorbent assay. Real-time polymerase chain reaction and Western blot were performed to analyze mRNA and protein levels, respectively.

RESULTS

During the whole experiment, 15, 50, and 100 μg/mL of POG had no cytotoxicity on RAW 264.7 cells. POG dose-dependently inhibited the production of NO, TNF-α, IL-1β, and IL-6 that were induced by LPS. POG treatment downregulated the mRNA and protein expression inducible NO synthase (iNOS) and cyclooxygenase 2 (COX-2) in LPS-activated RAW 264.7 macrophages in a concentration-dependent manner. Furthermore, LPS-induced JAK2/STAT3 activation was prevented in RAW 264.7 macrophages by POG treatment. STAT3 overexpression significantly reversed the effects of POG on LPS-activated RAW 264.7 macrophages.

CONCLUSION

These results demonstrate that POG exerts anti-inflammatory effects through the inhibition of iNOS and COX-2 expression by inhibiting the phosphorylation of JAK2/STAT3.

SUMMARY

POG exerts anti-inflammatory effects in RAW 264.7 macrophages through the inhibition of iNOS and COX-2 expression by inhibiting JAK2/STAT3 signaling. Abbreviations used: LPS: Lipopolyssacharide; NO: Nitric oxide; TNF-α: Tumor necrosis factor-α; IL: Interleukin; RS: Radix Saposhnikoviae; POG: Prim-O-glucosylcimifugin; iNOS: Inducible NO synthase; COX2: Cyclooxygenase; FBS: Fetal bovine serum; DMSO: Dimethylsulfoxide; CCK-8: Cell Counting Kit; RIPA: Radio immunoprecipitation assay buffer; ECL: Enhanced chemiluminescence; SD: Standard deviation; ELISA: Enzyme-Linked immunosorbent assay.

The Neuro-Protective Effect of the Methanolic Extract of Perilla frutescens var. japonicaand Rosmarinic Acid against H₂O₂-Induced Oxidative Stress in C6 Glial Cells

Neurodegenerative diseases are often associated with oxidative damage in neuronal cells. This study was conducted to investigate the neuro-protective effect of methanolic (MeOH) extract of Perilla frutescens var. japonica and its one of the major compounds, rosmarinic acid, under oxidative stress induced by hydrogen peroxide (H₂O₂) in C6 glial cells. Exposure of C6 glial cells to H₂O₂ enhanced oxidative damage as measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and thiobarbituric acid-reactive substance assays. The MeOH extract and rosmarinic acid prevented oxidative stress by increasing cell viability and inhibiting cellular lipid peroxidation. In addition, the MeOH extract and rosmarinic acid reduced H₂O₂-induced expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) at the transcriptional level. Moreover, iNOS and COX-2 protein expression was down-regulated in H₂O₂-indcued C6 glial cells treated with the MeOH extract and rosmarinic acid. These findings suggest that P. frutescens var. japonica and rosmarinic acid could prevent the progression of neurodegenerative diseases through attenuation of neuronal oxidative stress.

Decreased STAT3 in human idiopathic fetal growth restriction contributes to trophoblast dysfunction

Abnormal trophoblast function is associated with fetal growth restriction (FGR). The JAK-STAT pathway is one of the principal signalling mechanisms by which cytokines and growth factors modulate cell proliferation, differentiation, cell migration and apoptosis. The expression of placental JAK-STAT genes in human idiopathic FGR is unknown. In this study, we propose the hypothesis that JAK-STAT pathway genes are differentially expressed in idiopathic FGR-affected pregnancies and contribute to abnormal feto-placental growth by modulating the expression of the amino acid transporter SNAT2, differentiation marker CGB/human chorionic gonadotrophin beta-subunit (β-hCG) and apoptosis markers caspases 3 and 8, and TP53. Expression profiling of FGR-affected placentae revealed that mRNA levels of STAT3, STAT2 and STAT5B decreased by 69, 52 and 50%, respectively, compared with gestational-age-matched controls. Further validation by real-time PCR and immunoblotting confirmed significantly lower STAT3 mRNA and STAT3 protein (total and phosphorylated) levels in FGR placentae. STAT3 protein was localised to the syncytiotrophoblast (ST) in both FGR and control placentae. ST differentiation was modelled by in vitro differentiation of primary villous trophoblast cells from first-trimester and term placentae, and by treating choriocarcinoma-derived BeWo cells with forskolin in cell culture. Differentiation in these models was associated with increased STAT3 mRNA and protein levels. In BeWo cells treated with siRNA targeting STAT3, the mRNA and protein levels of CGB/β-hCG, caspases 3 and 8, and TP53 were significantly increased, while that of SNAT2 was significantly decreased compared with the negative control siRNA. In conclusion, we report that decreased STAT3 expression in placentae may contribute to abnormal trophoblast function in idiopathic FGR-affected pregnancies.

A novel mechanism for momordin Ic-induced HepG2 apoptosis: involvement of PI3K- and MAPK-dependent PPARγ activation

Momordin Ic is a natural triterpenoid saponin found in various Chinese and Japanese natural medicines such as the fruit of Kochia scoparia (L.) Schrad. Momordin Ic has been previously demonstrated to induce HepG2 cell apoptosis in a ROS-mediated PI3K and MAPK pathway-dependent manner. In the present study, the underlying mechanisms of PI3K and MAPK pathway-mediated PPARγ, and PGC-1α co-regulator activation, as well as the effects of downstream proteins, COX-2 and FoxO4, on cell apoptosis were investigated. The results demonstrated that momordin Ic activated PPARγ and inhibited COX-2. PGC-1α and FoxO4 expressions were increased by the PI3K or MAPK pathways. Furthermore, PPARγ inhibition decreased p-p38 and FoxO4 expression, and restored COX-2 expression. ROS inhibition exerted little effect on PPARγ, COX-2 and FoxO4 expression but affected PGC-1α expression. These results revealed the involvement of PI3K and MAPK-dependent PPARγ activation in momordin Ic-induced apoptosis, providing more detailed information underlying the pro-apoptotic mechanism of momordin Ic in HepG2 cell apoptosis.

Activated δ‑opioid receptors inhibit hydrogen peroxide‑induced apoptosis in liver cancer cells through the PKC/ERK signaling pathway

Apoptotic liver cancer cells have important roles in liver tumorigenesis and liver cancer progression. Recent studies have shown that δ‑opioid receptors are highly expressed in human liver and liver cancer cells. The present study aimed to investigate the role of activated δ‑opioid receptors on human liver cancer cell apoptosis and its interrelation with the mitochondria and the protein kinase C/extracellular‑signal‑regulated kinase (PKC/ERK) signaling pathway. H2O2 was used to induce apoptosis in human liver cancer cells. During apoptosis, mitochondrial transmembrane potentials were observed to decrease, cytochrome c expression was found to increase and B cell lymphoma 2 (Bcl‑2) expression decreased. These findings suggested that H2O2‑induced apoptosis was mediated through the mitochondrial pathway. Of note, activated δ‑opioid receptors were observed to inhibit H2O2‑induced apoptosis in human liver cancer cells. Following δ‑opioid receptor activation, the number of apoptotic liver cancer cells decreased, mitochondrial transmembrane potentials were restored, cytoplasmic cytochrome c and Bcl‑2‑associated X protein expression decreased and Bcl‑2 expression increased. These data suggested that δ‑opioid receptor activation inhibited mitochondria‑mediated apoptosis. In addition, activation of δ‑opioid receptors was observed to increase the expression of PKC and ERK in human liver cancer cells. Furthermore, upon inhibition of the PKC/ERK signaling pathway, the protective effect associated with the δ‑opioid receptor on liver cancer cell apoptosis was inhibited, which was not associated with the status of δ‑opioid receptor activation. These findings suggested that the PKC/ERK signaling pathway has an important role in δ‑opioid receptor‑mediated inhibition of apoptosis in human liver cancer cells.

Topical retinoids in skin ageing: a focused update with reference to sun-induced epidermal vitamin A deficiency

Vitamin A is an important constituent of the epidermis, where it plays a crucial role in epidermal turnover. A deficiency of epidermal vitamin A may be the consequence of nutritional vitamin A deficiency, exposure to sunlight or any UV source, oxidative stress or chronological ageing. As a consequence, any treatment aiming at increasing epidermal vitamin A would exert a protective effect against these deleterious conditions. Retinoids may counteract some deleterious actions of UV radiation by physical and biological mechanisms. Topical natural retinoic acid precursors such as retinaldehyde or retinol are less irritant than acidic retinoids and may prevent epidermal vitamin A deficiency due to nutritional deficiency, exposure to sunlight or any condition leading to free radical production. Retinoids may be combined with other compounds with complementary actions against ageing, nutritional deficiency and cancer, such as antioxidants, to potentiate their beneficial effects in the skin.

Janus kinase 3 activity is necessary for phosphorylation of cytosolic phospholipase A2 and prostaglandin E2 synthesis by macrophages infected with Francisella tularensis live vaccine strain

Francisella tularensis, the causative agent of tularemia, modulates the host immune response to gain a survival advantage within the host. One mechanism of immune evasion is the ability of F. tularensis to induce the synthesis of the small lipid mediator prostaglandin E2 (PGE2), which alters the host T cell response making the host more susceptible to Francisella growth. PGE2 is synthesized by a tightly regulated biosynthetic pathway following stimulation. The synthesis of PGE2 begins with the liberation of arachidonic acid (AA) from membrane phospholipids by cytosolic phospholipase A2 (cPLA2). AA is subsequently converted to the unstable intermediate PGH2 by cyclooxygenase-2 (COX-2), and PGH2 undergoes an isomerization reaction to generate PGE2. Our objective was to identify F. tularensis-activated host signaling pathways that regulate the activity of the enzymes in the PGE2-biosynthetic pathway. In this study, we show that cPLA2, p38 mitogen-activated protein kinase (MAPK), and Janus kinase 3 (JAK3) signaling are necessary for F. tularensis-induced PGE2 production. Inhibition of JAK3 activity reduced the phosphorylation of cPLA2 and COX-2 protein levels. In addition, JAK3 regulates cPLA2 phosphorylation independent of transcription. Moreover, p38 MAPK activity is required for F. tularensis-induced COX-2 protein synthesis, but not for the phosphorylation of cPLA2. This research highlights a unique signaling axis in which JAK3 and p38 MAPK regulate the activity of multiple enzymes of the PGE2-biosynthetic pathway in macrophages infected with F. tularensis.

Susceptibility to DNA damage as a molecular mechanism for non-syndromic cleft lip and palate

Non-syndromic cleft lip/palate (NSCL/P) is a complex, frequent congenital malformation, determined by the interplay between genetic and environmental factors during embryonic development. Previous findings have appointed an aetiological overlap between NSCL/P and cancer, and alterations in similar biological pathways may underpin both conditions. Here, using a combination of transcriptomic profiling and functional approaches, we report that NSCL/P dental pulp stem cells exhibit dysregulation of a co-expressed gene network mainly associated with DNA double-strand break repair and cell cycle control (p = 2.88×10(-2)-5.02×10(-9)). This network included important genes for these cellular processes, such as BRCA1, RAD51, and MSH2, which are predicted to be regulated by transcription factor E2F1. Functional assays support these findings, revealing that NSCL/P cells accumulate DNA double-strand breaks upon exposure to H2O2. Furthermore, we show that E2f1, Brca1 and Rad51 are co-expressed in the developing embryonic orofacial primordia, and may act as a molecular hub playing a role in lip and palate morphogenesis. In conclusion, we show for the first time that cellular defences against DNA damage may take part in determining the susceptibility to NSCL/P. These results are in accordance with the hypothesis of aetiological overlap between this malformation and cancer, and suggest a new pathogenic mechanism for the disease.