BIKE regulates dengue virus infection and is a cellular target for broad-spectrum antivirals.

Global health is threatened by emerging viruses, many of which lack approved therapies and effective vaccines, including dengue, Ebola, and Venezuelan equine encephalitis. We previously reported that AAK1 and GAK, two of the four members of the understudied Numb-associated kinases (NAK) family, control intracellular trafficking of RNA viruses. Nevertheless, the role of BIKE and STK16 in viral infection remained unknown. Here, we reveal a requirement for BIKE, but not STK-16, in dengue virus (DENV) infection. BIKE mediates both early (postinternalization) and late (assembly/egress) stages in the DENV life cycle, and this effect is mediated in part by phosphorylation of a threonine 156 (T156) residue in the µ subunit of the adaptor protein (AP) 2 complex. Pharmacological compounds with potent anti-BIKE activity, including the investigational anticancer drug 5Z-7-oxozeaenol and more selective inhibitors, suppress DENV infection both in vitro and ex vivo. BIKE overexpression reverses the antiviral activity, validating that the mechanism of antiviral action is, at least in part, mediated by BIKE. Lastly, 5Z-7-oxozeaenol exhibits antiviral activity against viruses from three unrelated RNA viral families with a high genetic barrier to resistance. These findings reveal regulation of poorly understood stages of the DENV life cycle via BIKE signaling and establish a proof-of-principle that pharmacological inhibition of BIKE can be potentially used as a broad-spectrum strategy against acute emerging viral infections.

Beclin 1-ATG14L Protein-Protein Interaction Inhibitor Selectively Inhibits Autophagy through Disruption of VPS34 Complex I.

Autophagy, a catabolic recycling process, has been implicated as a critical pathway in cancer. Its role in maintaining cellular homeostasis helps to nourish hypoxic, nutrient-starved tumors and protects them from chemotherapy-induced death. Recent efforts to target autophagy in cancer have focused on kinase inhibition, which has led to molecules that lack specificity due to the multiple roles of key kinases in this pathway. For example, the lipid kinase VPS34 is present in two multiprotein complexes responsible for the generation of phosphatidylinositol-3-phosphate. Complex I generates the autophagosome, and Complex II is crucial for endosomal trafficking. Molecules targeting VPS34 inhibit both complexes, which inhibits autophagy but causes undesirable defects in vesicle trafficking. The lack of specific autophagy modulators has limited the utility of autophagy inhibition as a therapeutic strategy. We hypothesize that disruption of the Beclin 1-ATG14L protein-protein interaction, which is required for the formation, proper localization, and function of VPS34 Complex I but not Complex II, will disrupt Complex I formation and selectively inhibit autophagy. To this end, a high-throughput, cellular NanoBRET assay was developed targeting this interaction. An initial screen of 2560 molecules yielded 19 hits that effectively disrupted the interaction, and it was confirmed that one hit disrupted VPS34 Complex I formation and inhibited autophagy. In addition, the molecule did not disrupt the Beclin 1-UVRAG interaction, critical for VPS34 Complex II, and thus had little impact on vesicle trafficking. This molecule is a promising new tool that is critical for understanding how modulation of the Beclin 1-ATG14L interaction affects autophagy. More broadly, its discovery demonstrates that targeting protein-protein interactions found within the autophagy pathway is a viable strategy for the discovery of autophagy-specific probes and therapeutics.

Inhibition of TLR4/TRIF/IRF3 Signaling Pathway by Curcumin in Breast Cancer Cells.

PURPOSE: Toll-like receptor 4 (TLR4) is over-expressed in breast tumors and thus contributing to the tumor progression and metastasis. Natural products have drawn attention in cancer immunotherapy due to their various biological activities. Curcumin is well investigated in different types of cancer. However, the mechanisms underlying its anti-inflammatory actions have not been extensively elucidated.  For this purpose, we explored the inhibitory effects of curcumin on lipopolysaccharide (LPS)-induced TLR4 dependent TRIF signaling pathway in two subtypes of breast cancer cell lines (MCF-7 and MDA-MB-231) in this study. METHODS: In this context, the cytotoxicity of curcumin and LPS alone and the combination of curcumin with LPS on these cells was evaluated by WST-1 assay.  The expression level of TLR4 and the release of type I interferon (IFN) levels were determined after treatment with curcumin and/or LPS by RT-PCR and ELISA analysis, respectively. Furthermore, the subcellular localization of TLR4 and interferon regulatory factor 3 (IRF3) were detected by immunofluorescence analysis. RESULTS: Curcumin treatment suppressed breast cancer cells viabilities and the activation of TLR4-mediated TRIF signaling pathway by the downregulation of TLR4 and IRF3 expression levels and the inhibition of type I IFN (IFN-α/ß) levels induced by LPS. However, curcumin was more efficient in MDA- MB-231 cells than MCF-7 cells owing to its greater inhibitory efficacy in the LPS- enhanced TLR4 signaling pathway. Furthermore, IFN-α/ß levels induced by TLR4 and IRF3 were decreased in these cells following curcumin treatment. CONCLUSIONS: Consequently, these results demonstrated that the activation of LPS stimulated TLR4/TRIF/IRF3 signaling pathway was mediated by curcumin in breast cancer cells, in vitro. However, more studies are necessary to examine the curcumin's anti-inflammatory activities on TLR4/MyD88/NF-κB as well as other signaling pathways downstream of TLRs in breast cancer.

Molecularly Distinct Clathrin-Coated Pits Differentially Impact EGFR Fate and Signaling.

Adaptor protein 2 (AP2) is a major constituent of clathrin-coated pits (CCPs). Whether it is essential for all forms of clathrin-mediated endocytosis (CME) in mammalian cells is an open issue. Here, we demonstrate, by live TIRF microscopy, the existence of a subclass of relatively short-lived CCPs lacking AP2 under physiological, unperturbed conditions. This subclass is retained in AP2-knockout cells and is able to support the internalization of epidermal growth factor receptor (EGFR) but not of transferrin receptor (TfR). The AP2-independent internalization mechanism relies on the endocytic adaptors eps15, eps15L1, and epsin1. The absence of AP2 impairs the recycling of the EGFR to the cell surface, thereby augmenting its degradation. Accordingly, under conditions of AP2 ablation, we detected dampening of EGFR-dependent AKT signaling and cell migration, arguing that distinct classes of CCPs could provide specialized functions in regulating EGFR recycling and signaling.

A Novel Peptide Interfering with proBDNF-Sortilin Interaction Alleviates Chronic Inflammatory Pain.

Rationale: Brain-derived neurotrophic factor (BDNF) is a key mediator in the development of chronic pain. Sortilin is known to interact with proBDNF and regulate its activity-dependent secretion in cortical neurons. In a rat model of inflammatory pain with intraplantar injection of complete Freund's adjuvant (CFA), we examined the functional role of proBDNF-sortilin interaction in dorsal root ganglia (DRG). Methods: Expression and co-localization of BDNF and sortilin were determined by immunofluorescence. ProBDNF-sortilin interaction interface was mapped using co-immunoprecipitation and bimolecular fluorescence complementation assay. The analgesic effect of intrathecal injection of a synthetic peptide interfering with proBDNF-sortilin interaction was measured in the CFA model. Results: BDNF and sortilin were co-localized and their expression was significantly increased in ipsilateral L4/5 DRG upon hind paw CFA injection. In vivo adeno-associated virus-mediated knockdown of sortilin-1 in L5 DRG alleviated pain-like responses. Mapping by serial deletions in the BDNF prodomain indicated that amino acid residues 71-100 supported the proBDNF-sortilin interaction. A synthetic peptide identical to amino acid residues 89-98 of proBDNF, as compared with scrambled peptide, was found to interfere with proBDNF-sortilin interaction, inhibit activity-dependent release of BDNF in vitro and reduce CFA-induced mechanical allodynia and heat hyperalgesia in vivo. The synthetic peptide also interfered with capsaicin-induced phosphorylation of extracellular signal-regulated kinases in ipsilateral spinal cord of CFA-injected rats. Conclusions: Sortilin-mediated secretion of BDNF from DRG neurons contributes to CFA-induced inflammatory pain. Interfering with proBDNF-sortilin interaction reduced activity-dependent release of BDNF and might serve as a therapeutic approach for chronic inflammatory pain.

Hepatocyte sortilin 1 knockout and treatment with a sortilin 1 inhibitor reduced plasma cholesterol in Western diet-fed mice.

Sortilin 1 (Sort1) is a member of the Vps10p domain intracellular trafficking receptor family. Genetic variations of the SORT1 gene are strongly associated with plasma cholesterol levels in humans. Recent studies have linked Sort1 to regulation of cholesterol metabolism in hepatocytes and pro-inflammatory response in macrophages, but the tissue-specific roles of Sort1 in lipid metabolism have not been well defined. We developed Sort1 floxed mice and investigated the development of Western diet (WD)-induced steatosis, hepatic inflammatory response, and hyperlipidemia in hepatocyte Sort1 KO mice and myeloid cell Sort1 KO mice. Our findings suggest that hepatocyte Sort1 deficiency attenuated diet-induced hepatic steatosis and hypercholesterolemia in mice. In contrast, myeloid Sort1 deficiency did not reduce hepatic cytokine expression or plasma cholesterol levels, but exacerbated hepatic triglyceride accumulation in WD-fed mice. Finally, we showed that treating WD-fed mice with an orally bioavailable Sort1 inhibitor, AF38469, decreased plasma cholesterol and hepatic cytokine expression. AF38469 treatment did not affect diet-induced obesity or insulin resistance, but was associated with reduced hepatic VLDL secretion and higher hepatic cholesterol 7α-hydrolase expression in WD-fed mice. In conclusion, findings from this study suggest that Sort1 loss-of-function in hepatocytes contributes to lower plasma cholesterol, and pharmacological inhibition of Sort1 attenuates diet-induced hypercholesterolemia in mice.

Sortilin inhibition limits secretion-induced progranulin-dependent breast cancer progression and cancer stem cell expansion.

BACKGROUND: Cancer progression is influenced by genetic aberrations in the cancer cell population as well as by other factors including the microenvironment present within a tumour. Direct interactions between various cell types as well as cellular signalling via secreted cytokines can drive key tumourigenic properties associated with disease progression and treatment resistance. Also, cancer stem cell functions are influenced by the microenvironment. This challenging subset of cells has been linked to malignant properties. Within a screen, using in vivo like growth conditions, we identified progranulin as a highly secreted cytokine affecting cancer stem cells in breast cancer. This cytokine is known to play a role in numerous biological and tumour-related processes including therapy resistance in a range of cancer types. METHODS: Different in vitro and in vivo relevant conditions were used to validate breast cancer stem cell expansion mediated by progranulin and its receptor sortilin. Small interfering ribonucleic acid (siRNA) and pharmacological inhibition of sortilin were used to elucidate the role of sortilin as a functional receptor during progranulin-induced breast cancer stem cell propagation, both in vitro and in vivo, using breast cancer xenograft models. In addition, single-cell gene expression profiling as well as a Sox2 reporter breast cancer cell line were used to validate the role of dedifferentiation mediated by progranulin. RESULTS: In various in vivo-like screening assays, progranulin was identified as a potent cancer stem cell activator, highly secreted in ERα-negative breast cancer as well as in ERα-positive breast cancer under hypoxic adaptation. Progranulin exposure caused dedifferentiation as well as increased proliferation of the cancer stem cell pool, a process that was shown to be dependent on its receptor sortilin. Subcutaneous injections of progranulin or its active domain (GRN A) induced lung metastases in breast cancer xenograft models, supporting a major role for progranulin in cancer progression. Importantly, an orally bioavailable small molecule (AF38469) targeting sortilin, blocked GRN A-induced lung metastases and prevented cancer cell infiltration of the skin. CONCLUSION: The collective results suggest that sortilin targeting represents a potential novel breast cancer therapy approach inhibiting tumour progression driven by secretion and microenvironmental influences.

MiR-129-5p inhibits autophagy and apoptosis of H9c2 cells induced by hydrogen peroxide via the PI3K/AKT/mTOR signaling pathway by targeting ATG14.

Ischemic heart disease (IHD) is a significant cause of cardiovascular diseases. MicroRNAs (miRNAs) have been thought to be critical regulators in the heart diseases. The present study was aimed to investigate the effect of miR-129-5p on the autophagy and apoptosis by targeting ATG14 as well as how miR-129-5p worked through the PI3K/AKT/mTOR signaling pathway in H2O2-induced H9c2 cells. H9c2 cells were induced by H2O2, after which the expression of miR-129-5p was decreased. Reverse transcription-quantitative polymerase chain reaction (qRT-PCR) was performed to detect the expression level of miR-129-5p in H9c2 cells. In addition, the expression of miR-129-5p and ATG14 were overexpressed or down-regulated after transfection. The transfection efficiency was verified by qRT-PCR. Cell viability, cell apoptosis, and the expression of autophagy and apoptosis-related proteins were determined by CCK-8, flow cytometry and western blotting, respectively. Furthermore, GFP fusion protein analysis was used to detect the expression level of LC3II which was related to autophagy. As a result, cell viability was decreased and cell autophagy was increased in H2O2-induced H9c2 cells. MiR-129-5p overexpression inhibited cell injury caused by H2O2 in H9c2 cells which was certified by the increased cell viability and decreased cell autophagy and apoptosis. In addition, ATG14 was demonstrated to be a target of miR-129-5p which inhibited cell injury by down-regulation of ATG14. Moreover, phosphorylation of PI3K/AKT/mTOR pathway was activated by miR-129-5p overexpression or ATG14 inhibition to alleviate the autophagy and apoptosis in H2O2-induced H9c2 cells. In conclusion, this study indicated that miR-129-5p inhibited autophagy and apoptosis in H2O2-induced H9c2 cells partly by down-regulation of ATG14 through the activation of PI3K/AKT/mTOR pathway.

Cellular Protein Kinase D Modulators Play a Role during Multiple Steps of Herpes Simplex Virus 1 Egress.

The assembly of new herpes simplex virus 1 (HSV-1) particles takes place in the nucleus. These particles then travel across the two nuclear membranes and acquire a final envelope from a cellular compartment. The contribution of the cell to the release of the virus is, however, little known. We previously demonstrated, using a synchronized infection, that the host protein kinase D and diacylglycerol, a lipid that recruits the kinase to the trans-Golgi network (TGN), promote the release of the virus from that compartment. Given the role this cellular protein plays in the herpes simplex virus 1 life cycle and the many molecules that modulate its activity, we aimed to determine to what extent this virus utilizes the protein kinase D pathway during a nonsynchronized infection. Several molecular protein kinase D (PKD) regulators were targeted by RNA interference and viral production monitored. Surprisingly, many of these modulators negatively impacted the extracellular release of the virus. Overexpression studies, the use of pharmacological reagents, and assays to monitor intracellular lipids implicated in the biology of PKD suggested that these effects were oddly independent of total intracellular diacylglycerol levels. Instead, mapping of the viral intermediates by electron microscopy suggested that some of these modulators could regulate distinct steps along the viral egress pathway, notably nuclear egress. Altogether, this suggests a more complex contribution of PKD to HSV-1 egress than originally anticipated and new research avenues to explore.IMPORTANCE Viruses are obligatory parasites that highjack numerous cellular functions. This is certainly true when it comes to transporting viral particles within the cell. Herpesviruses share the unique property of traveling through the two nuclear membranes by subsequent budding and fusion and acquiring their final envelope from a cellular organelle. Albeit disputed, the overall evidence from many laboratories points to the trans-Golgi network (TGN) as the source of that membrane. Moreover, past findings revealed that the host protein kinase D (PKD) plays an important role at that stage, which is significant given the known implication of that protein in vesicular transport. The present findings suggest that the PKD machinery not only affects the late stages of herpes simplex virus I egress but also modulates earlier steps, such as nuclear egress. This opens up new means to control these viruses.

Knockdown of Linc00515 Inhibits Multiple Myeloma Autophagy and Chemoresistance by Upregulating miR-140-5p and Downregulating ATG14.

BACKGROUND/AIMS: The purpose of our experiments was to investigate the targeting relationship of linc00515, miR-140-5p and ATG14 and to explore the roles of linc00515, miR-140-5p and ATG14 in autophagy and chemoresistance of melphalan-resistant multiple myeloma cells. METHODS: Plasmids that could interfere with the expression of linc00515 and ATG14 were loaded into myeloma cells, which were cultured with melphalan. MTT assay and flow cytometry analysis were utilized to investigate the effect of linc00515, miR-140-5p and ATG14 on the resistance of myeloma cells. QRT-PCR was used to determine the levels of mRNAs. Western blot was utilized to explore the level of ATG14 and autophagy-related proteins. Dual luciferase assay was utilized to explore the targeting relationship between linc00515, miR-140-5p and ATG14. GFP LC3 fluorescence assay was conducted to study the autophagy of cells. RESULTS: The expression of linc00515 and ATG14 were significantly higher in melphalan-resistant myeloma cells. Knockdown of linc00515 and ATG14 led to decreased autophagy and chemoresistance of melphalan-resistant myeloma cells. The forced expression of miR-140-5p suppressed autophagy and chemoresistance of melphalan-resistant myeloma cells. CONCLUSION: Linc00515 enhanced autophagy and chemoresistance of melphalan-resistant myeloma by directly inhibiting miR-140-5p, which elevated ATG14 level.

MicroRNA-181a promotes angiogenesis in colorectal cancer by targeting SRCIN1 to promote the SRC/VEGF signaling pathway.

Colorectal cancer (CRC) is a very common metastatic tumor with active angiogenesis that requires active angiogenesis. Recently, increased microRNA-181a-5p (miR-181a) expression was found to be significantly associated with liver metastasis and poor outcome in CRC patients. In this study, the role of miR-181a in tumor angiogenesis was further investigated. Capillary tube formation assays were used to demonstrate the ability of miR-181a to promote tumor angiogenesis. Bioinformatics analyses identified SRC kinase signaling inhibitor 1 (SRCIN1) as a potential target of miR-181a. Next, two CRC cell lines (HT29 and SW480) were used to clarify the function of miR-181a through SRCIN1 targeting. In addition, the biological effects of SRCIN1 inhibition by miR-181a were examined in vitro by quantitative RT-PCR, western blotting and enzyme-linked immunosorbent assay and in vivo by Matrigel plug angiogenesis assays and immunohistochemical staining. In clinical samples, Fluorescence in situ hybridization and immunofluorescence were performed to detect the relation between miR-181a and SRCIN1. In addition, SRCIN1 protein and miR-181a expression levels in CRC tissues were also measured by western blot and quantitative real-time polymerase chain reaction. MiR-181a markedly augmented the capability of CRC cells to advance tube formation in endothelial cells in vitro. The Matrigel plug assay showed that miR-181a promoted angiogenesis in vivo. In conclusion, miR-181a inhibited SRCIN1, which caused SRC to transform from an inactive status to an active conformation and to trigger vascular endothelial growth factor secretion, leading to increased angiogenesis. MiR-181a dysregulation contributes to angiogenesis in CRC, and downregulation of miR-181a represents a promising, novel strategy to achieve an efficient antiangiogenic response in anti-CRC therapy.

Human Binge Alcohol Intake Inhibits TLR4-MyD88 and TLR4-TRIF Responses but Not the TLR3-TRIF Pathway: HspA1A and PP1 Play Selective Regulatory Roles.

Binge/moderate alcohol suppresses TLR4-MyD88 proinflammatory cytokines; however, alcohol's effects on TLR-TRIF signaling, especially after in vivo exposure in humans, are unclear. We performed a comparative analysis of the TLR4-MyD88, TLR4-TRIF, and TLR3-TRIF pathways in human monocytes following binge alcohol exposure. Mechanistic regulation of TLR-TRIF signaling by binge alcohol was evaluated by analyzing IRF3 and TBK1, upstream regulator protein phosphatase 1 (PP1), and immunoregulatory stress proteins HspA1A and XBP-1 in alcohol-treated human and mouse monocytes/macrophages. Two approaches for alcohol exposure were used: in vivo exposure of primary monocytes in binge alcohol-consuming human volunteers or in vitro exposure of human monocytes/murine macrophages to physiological alcohol concentrations (25-50 mM ethanol), followed by LPS (TLR4) or polyinosinic-polycytidylic acid (TLR3) stimulation ex vivo. In vivo and in vitro binge alcohol exposure significantly inhibited the TLR4-MyD88 cytokines TNF-α and IL-6, as well as the TLR4-TRIF cytokines/chemokines IFN-ß, IP-10, and RANTES, in human monocytes, but not TLR3-TRIF-induced cytokines/chemokines, as detected by quantitative PCR and ELISA. Mechanistic analyses revealed TBK-1-independent inhibition of the TLR4-TRIF effector IRF3 in alcohol-treated macrophages. Although stress protein XBP-1, which is known to regulate IRF3-mediated IFN-ß induction, was not affected by alcohol, HspA1A was induced by in vivo alcohol in human monocytes. Alcohol-induced HspA1A was required for inhibition of TLR4-MyD88 signaling but not TLR4-TRIF cytokines in macrophages. In contrast, inhibition of PP1 prevented alcohol-mediated TLR4-TRIF tolerance in macrophages. Collectively, our results demonstrate that in vivo and in vitro binge alcohol exposure in humans suppresses TLR4-MyD88 and TLR4-TRIF, but not TLR3-TRIF, responses. Whereas alcohol-mediated effects on the PP1-IRF3 axis inhibit the TLR4-TRIF pathway, HspA1A selectively suppresses the TLR4-MyD88 pathway in monocytes/macrophages.

Neurotensin Receptor 3/Sortilin Contributes to Tumorigenesis of Neuroendocrine Tumors Through Augmentation of Cell Adhesion and Migration.

Neurotensin (NTS), a 13-amino acid peptide which is distributed predominantly along gastrointestinal tract, has multiple physiologic and pathologic functions, and its effects are mediated by three distinct NTS receptors (NTSRs). Overexpression and activation of NTS signaling components, especially NTS and/or NTSR1, are closely linked with cancer progression and metastasis in various types of cancers including neuroendocrine tumors (NETs). Although deregulation of NTSR3/sortilin has been implicated in a variety of human diseases, the expression and role of NTSR3/sortilin in NETs have not been elucidated. In this study, we investigated the expression and oncogenic effect of NTSR3/sortilin in NETs. Increased protein levels of NTSR3/sortilin were noted in the majority of human clinical NETs (n=21) by immunohistochemical analyses compared with normal tissues (n=12). Expression of NTS and NTSR3/sortilin was also noted in all tested NET cell lines. In addition, small interfering RNA-mediated knockdown of NTSR3/sortilin decreased cell number without alteration of cell cycle progression and apoptosis induction in NET cell lines BON and QGP-1. Moreover, silencing of NTSR3/sortilin significantly suppressed cell adhesion and cell migration with inhibition of focal adhesion kinase and Src phosphorylation in the NET cells. Our results demonstrate increased expression of NTSR3/sortilin in NET patient tissues and a critical role of NTSR3/sortilin on NET cell adhesion and migration suggesting that NTSR3/sortilin contributes to NET tumorigenesis.

The inhibition of MyD88 and TRIF signaling serve equivalent roles in attenuating myocardial deterioration due to acute severe inflammation.

Myeloid differentiation factor 88 (MyD88) and Toll or interleukin-1 receptor-domain-containing adaptor-inducing interferon-ß (IFN-ß) (TRIF) are two pivotal downstream adaptors of Toll-like receptors. Activation of MyD88 or TRIF signaling in cardiac immune pathology of severe inflammation negatively influences heart function. In the present study, severe septic cardiac injury was induced in C57BL/6 mice by cecum ligation and puncture (CLP). A total of 64 mice were divided randomly into the following four groups (n=16/group; 8 for observation of survival rate, 8 for heart sample analysis): Sham, CLP, anti-MyD88-CLP and anti-TRIF-CLP. Anti-MyD88 and anti-TRIF antibodies were administered to the respective mice through the tail veins 2 h before CLP. Measurements of cardiac function, including M-modes, velocity vector imaging and cardiac troponin I, were performed. Myocardial inflammatory cytokines were examined by reverse transcription-polymerase chain reaction (RT-PCR), myocardial neutrophil infiltration was measured by a myeloperoxidase activity assay, intracellular adhesion molecule and vascular cell adhesion molecule mRNA expression levels were investigated, and histopathological characteristics were evaluated. Levels of mRNA transcripts encoding genes for apoptosis production and MyD88, TRIF, nuclear factor-κB and IFN regulatory factor 3 were investigated by RT-PCR. Mice challenged with CLP demonstrated deleterious cardiac function, increased levels of interleukin-1ß (IL-1ß), IL-6ß, and tumor necrosis factor-α mRNA, increased neutrophil infiltration, and increased apoptosis. In contrast, mice in the anti-MyD88 CLP and anti-TRIF CLP groups retained cardiac function with reduced cytokine release, decreased neutrophil infiltration, and reduced apoptosis. In addition, there was no significant difference between the anti-MyD88 CLP and anti-TRIF CLP groups. Thus, the present study indicated that MyD88 and TRIF blockades serve notable and equivalent roles in protecting cardiac deterioration from severe sepsis by attenuating cytokine release, reducing neutrophil infiltration and alleviating apoptosis.

Pigment epithelium­derived factor protects human glomerular mesangial cells from diabetes via NOXO1­iNOS suppression.

The authors previously reported that pigment epithelium­derived factor (PEDF) protects the diabetic kidney from fibrosis via its anti­oxidative effects. However, the underlying molecular mechanism has never been revealed. The present study aimed to investigate how PEDF protects mesangial cells from diabetes induced damage. Human mesangial cells were exposed to a diabetic environment [30 mmol/l glucose and 200 mg advanced glycation end products (AGEs)] in the absence or presence of PEDF (200 mg/l). The superoxide and peroxynitrite productions were measured by fluorescent assay. The nicotinamide adenine dinucleotide phosphate (NAPDH) oxidases (NOXs; isoforms NOX1, NOX2, and NOX4), NADPH oxidase organizer 1 (NOXO1), DHFR, endothelial nitric oxide synthase (iNOS) and phospho­p38MAPK (p­p38) protein levels were also examined to explore the possible mechanism of the PEDF anti­oxidative properties. The fibrogenesis of mesangial cells in diabetes was associated with increased superoxide generation and peroxynitrite production via iNOS induction and uncoupling. However, elevated transforming growth factor­ß level, reactive oxygen species (ROS) overproduction, iNOS induction and uncoupling were all reversed by NOXO1 suppression following PEDF treatment or NOXO1 silencing. Furthermore, the p38MAPK inhibition only attenuated the ROS/peroxynitrite production partially via abolishment of iNOS induction, however had no effect on iNOS uncoupling and its regulating enzyme: DHFR suppression. PEDF prevented oxidative stress and protected mesangial cells from fibrogenesis in a diabetic environment via dual effects mediated by NOXO1 inhibitory prevention of iNOS induction through p38MAPK inactivation and effects on iNOS coupling through DHFR restoration.

Identification of TBK1 complexes required for the phosphorylation of IRF3 and the production of interferon ß.

The double-stranded RNA mimetic poly(I:C) and lipopolysaccharide (LPS) activate Toll-like receptors 3 (TLR3) and TLR4, respectively, triggering the activation of TANK (TRAF family member-associated NF-κB activator)-binding kinase 1 (TBK1) complexes, the phosphorylation of interferon regulatory factor 3 (IRF3) and transcription of the interferon ß (IFNß) gene. Here, we demonstrate that the TANK-TBK1 and optineurin (OPTN)-TBK1 complexes control this pathway. The poly(I:C)- or LPS-stimulated phosphorylation of IRF3 at Ser396 and production of IFNß were greatly reduced in bone marrow-derived macrophages (BMDMs) from TANK knockout (KO) mice crossed to knockin mice expressing the ubiquitin-binding-defective OPTN[D477N] mutant. In contrast, IRF3 phosphorylation and IFNß production were not reduced significantly in BMDM from OPTN[D477N] knockin mice and only reduced partially in TANK KO BMDM. The TLR3/TLR4-dependent phosphorylation of IRF3 and IFNß gene transcription were not decreased in macrophages from OPTN[D477N] crossed to mice deficient in IκB kinase ε, a TANK-binding kinase related to TBK1. In contrast with the OPTN-TBK1 complex, TBK1 associated with OPTN[D477N] did not undergo phosphorylation at Ser172 in response to poly(I:C) or LPS, indicating that the interaction of ubiquitin chains with OPTN is required to activate OPTN-TBK1 in BMDM. The phosphorylation of IRF3 and IFNß production induced by Sendai virus infection were unimpaired in BMDM from TANK KO × OPTN[D477N] mice, suggesting that other/additional TBK1 complexes control the RIG-I-like receptor-dependent production of IFNß. Finally, we present evidence that, in human HACAT cells, the poly(I:C)-dependent phosphorylation of TBK1 at Ser172 involves a novel TBK1-activating kinase(s).

FOSL1 Inhibits Type I Interferon Responses to Malaria and Viral Infections by Blocking TBK1 and TRAF3/TRIF Interactions.

Innate immune response plays a critical role in controlling invading pathogens, but such an immune response must be tightly regulated. Insufficient or overactivated immune responses may lead to harmful or even fatal consequences. To dissect the complex host-parasite interactions and the molecular mechanisms underlying innate immune responses to infections, here we investigate the role of FOS-like antigen 1 (FOSL1) in regulating the host type I interferon (IFN-I) response to malaria parasite and viral infections. FOSL1 is known as a component of a transcription factor but was recently implicated in regulating the IFN-I response to malaria parasite infection. Here we show that FOSL1 can act as a negative regulator of IFN-I signaling. Upon stimulation with poly(I:C), malaria parasite-infected red blood cells (iRBCs), or vesicular stomatitis virus (VSV), FOSL1 "translocated" from the nucleus to the cytoplasm, where it inhibited the interactions between TNF receptor-associated factor 3 (TRAF3), TIR domain-containing adapter inducing IFN-ß (TRIF), and Tank-binding kinase 1 (TBK1) via impairing K63-linked polyubiquitination of TRAF3 and TRIF. Importantly, FOSL1 knockout chimeric mice had lower levels of malaria parasitemia or VSV titers in peripheral blood and decreased mortality compared with wild-type (WT) mice. Thus, our findings have identified a new role for FOSL1 in negatively regulating the host IFN-I response to malaria and viral infections and have identified a potential drug target for controlling malaria and other diseases. IMPORTANCE: Infections of pathogens can trigger vigorous host immune responses, including activation and production of type I interferon (IFN-I). In this study, we investigated the role of FOSL1, a molecule previously known as a transcription factor, in negatively regulating IFN-I responses to malaria and viral infections. We showed that FOSL1 was upregulated and translocated into the cytoplasm of cells after stimulation for IFN-I production. FOSL1 could affect TRAF3 and TRIF ubiquitination and consequently impaired the association of TRAF3, TRIF, and TBK1, leading to inhibition of IFN-I signaling. In vivo experiments with FOSL1 knockout chimeric mice further validated the negative role of FOSL1 in IFN-I production and antimicrobial responses. This report reveals a new functional role for FOSL1 in IFN-I signaling and dissects the mechanism by which FOSL1 regulates IFN-I responses to malaria and viral infections, which can be explored as a potential drug target for disease control and management.

MiR-346 promotes the biological function of breast cancer cells by targeting SRCIN1 and reduces chemosensitivity to docetaxel.

MicroRNAs (miRNAs) are a class of highly conserved small noncoding RNAs that play pivotal roles at the post-transcriptional level in the biological function of various cancers, including breast cancer. In our study, miR-346 mimic, inhibitor, negative control or si-SRCIN1 were transfected into MCF-7 and MCF-7/Doc cells, respectively. Quantitative real time PCR (qRT-PCR) was used to measure miR-346 and SRCIN1 mRNA expressions and western blot was used to detect the expression of SRCIN1 in protein level. CCK-8 and colony formation were employed to verify cell viability and proliferation. Flow cytometry showed the apoptosis. Transwell was performed to detect migration and invasion. The luciferase reporter assay data showed the target correlation of miR-346 and SRCIN1. Firstly, we found that the expression of miR-346 was higher in breast cancer tissues than in their paired corresponding non-cancerous tissues and there was significant inversed correlation between miR-346 and SRCIN1. Overexpression of miR-346 promoted cell proliferation, colony formation, migration and invasion, and reduced apoptosis, sensitivity to Docetaxel (Doc). SRCIN1 was identified as a direct target of miR-346, whose silencing promoted cell proliferation and the IC50 of Doc. Moreover, SRCIN1 silencing reduced the effect of miR-346 down-expression. Taken together, miR-346 may function as an oncogenic miRNA and mediate chemosensitivity to docetaxel through targeting SRCIN1 in breast cancer, targeted modulation of miR-346 expression may became a potential strategy for the treatment.

TRIF promotes angiotensin II-induced cross-talk between fibroblasts and macrophages in atrial fibrosis.

AIMS: Atrial fibroblasts and macrophages have long been thought to participate in atrial fibrillation (AF). However, which specific mediator may regulate the interaction between them remains unclear. METHODS AND RESULTS: We provided the evidence for the involvement of Toll/IL-1 receptor domain-containing adaptor inducing IFN-ß (TRIF), an important inflammation-related molecule, in the pathophysiology of AF. Patients with AF showed higher levels of angiotensin II (AngII) and TRIF expression and larger number of macrophages infiltration in left atria appendage than individuals with sinus rhythm (SR). In the cell study, AngII induced chemokines expressions in mouse atrial fibroblasts and AngII-stimulated atrial fibroblasts induced the chemotaxis of macrophages, which were reduced by losartan and TRIF siRNA. Meanwhile, AngII-stimulated atrial fibroblasts proliferation was enhanced by macrophages. CONCLUSIONS: Our data demonstrated that TRIF may be a crucial factor promoting the interaction between atrial fibroblasts and macrophages, leading to atrial fibrosis.

Epsin is required for Dishevelled stability and Wnt signalling activation in colon cancer development.

Uncontrolled canonical Wnt signalling supports colon epithelial tumour expansion and malignant transformation. Understanding the regulatory mechanisms involved is crucial for elucidating the pathogenesis of and will provide new therapeutic targets for colon cancer. Epsins are ubiquitin-binding adaptor proteins upregulated in several human cancers; however, the involvement of epsins in colon cancer is unknown. Here we show that loss of intestinal epithelial epsins protects against colon cancer by significantly reducing the stability of the crucial Wnt signalling effector, dishevelled (Dvl2), and impairing Wnt signalling. Consistently, epsins and Dvl2 are correspondingly upregulated in colon cancer. Mechanistically, epsin binds Dvl2 via its epsin N-terminal homology domain and ubiquitin-interacting motifs and prohibits Dvl2 polyubiquitination and degradation. Our findings reveal an unconventional role for epsins in stabilizing Dvl2 and potentiating Wnt signalling in colon cancer cells to ensure robust colon cancer progression. The pro-carcinogenic role of Epsins suggests that they are potential therapeutic targets to combat colon cancer.