NF-κB p65 repression by the sesquiterpene lactone, Helenalin, contributes to the induction of autophagy cell death

Background

This study was to explore the effects of Gan-Lu-Yin (GLY) on the migration of vascular smooth muscle cells (VSMCs) induced by fetal bovine serum and on neointima formation in a rat model of carotid artery balloon injury.

Methods

VSMCs were treated with different concentrations of GLY, and then analyzed with Flow cytometric analysis, zymography, transwell, and western blotting. SD rats received balloon-injury were analyzed with H&E staining.

Results

Our results showed that GLY significantly decreased the thickness of neointima. The inhibition by non-cytoxic doses of GLY of VSMCs migration was through its negative regulatory effects on phosphorylated ERK1/2, PI3K/AKT, and FAK. The data showed that GLY can inhibit the migration of VSMCs cells, and might block injury-induced neointima hyperplasia via the inhibition of VSMCs migration, without inducing apoptosis.

Conclusions

These observations provide a mechanism of GLY in attenuating cell migration, thus as a potential intervention for restenosis.     

Regulation of NF-κB by the CARD proteins

Scaffold proteins play pivotal roles in the regulation of signal transduction pathways by connecting upstream receptors to downstream effector molecules. During the last decade, many scaffold proteins that contain caspase-recruitment domains (CARD) have been identified. Investigating the roles of CARD proteins has revealed that many of them play crucial roles in signaling cascades leading to activation of nuclear factor-κB (NF-κB). In this review, we discuss the contributions of CARD proteins to NF-κB activation in various signaling cascades. In particular, we share some of our personal experiences during the initial investigation of the functions of the CARMA family of CARD proteins and then summarize the roles of these proteins in signaling pathways induced by antigen receptors, G protein-coupled receptors, receptor tyrosine kinase, and C-type lectin receptors in the context of recent progress in these field.     

p-Synephrine suppresses lipopolysaccharide-induced acute lung injury by inhibition of the NF-κB signaling pathway

Objective

We investigated whether p-synephrine exerts potent anti-inflammatory effects against acute lung injury (ALI) induced by lipopolysaccharide (LPS) in vivo, and we further investigated the inhibitory mechanism of p-synephrine in LPS-induced ALI.

Methods

Lipopolysaccharide (0.5 mg/kg) was instilled intranasally in phosphate-buffered saline to induce acute lung injury, and 6, 24, and 48 h after LPS was given, bronchoalveolar lavage fluid was obtained to measure pro-inflammatory mediator. We also evaluated the effects of p-synephrine on LPS-induced the severity of pulmonary injury. The phosphorylation of nuclear factor-κB (NF-κB) p65 protein was analyzed by Western blotting.

Results

Our data showed that p-synephrine significantly reduced the amount of inflammatory cells, the lung wet-to-dry weight (W/D) ratio, reactive oxygen species, myeloperoxidase activity and enhanced superoxide dismutase (SOD) in mice with LPS-induced ALI. Tumor necrosis factor α and interleukin (IL)-6 concentrations decreased significantly while the concentration of IL-10 was significantly increased after p-synephrine pretreatment. In addition, p-synephrine suppressed not only the phosphorylation of NF-κB but also the degradation of its inhibitor (IκBα).

Conclusions

These results suggested that the inhibition of NF-κB activation and the regulation of SOD are involved in the mechanism of p-synephrine’s protection against ALI.     

A novel association between filamin A and NF-κB inducing kinase couples CD28 to inhibitor of NF-κB kinase α and NF-κB activation

CD28 costimulatory molecule plays a critical role in the activation of NF-κB. Indeed, while stimulation of T cells with either professional APCs or anti-TCR plus anti-CD28 antibodies efficiently activates NF-κB, TCR alone fails to do that. Moreover, CD28 stimulation by B7 in the absence of TCR may activate IκB kinase α (IKKα) and a non-canonical NF-κB2-like pathway, in human primary CD4(+) T cells. Despite its functional relevance in NF-κB activation, the molecules connecting autonomous CD28-mediated signals to IKKα and NF-κB activation remain still unknown. In searching for specific upstream activators linking CD28 to the IKKα/NF-κB cascade, we identify a novel constitutive association between filamin A (FLNa) and the NF-κB inducing kinase (NIK), in both Jurkat and human primary T cells. Following CD28 engagement by B7, in the absence of TCR, FLNa-associated NIK is activated and induces IKKα kinase activity. Both proline (P(208)YAP(211)P(212)) and tyrosine residues (Y(206)QPY(209)APP) within the C-terminal proline-rich motif of CD28 are involved in the recruitment of FLNa/NIK complexes to the membrane as well as in the activation of NIK and IKKα.     

GP73 facilitates hepatitis B virus replication by repressing the NF-κB signaling pathway

Hepatitis B virus (HBV) chronically infects approximately 350 million people worldwide, and 600 000 deaths are caused by HBV-related hepatic failure. Golgi protein 73 (GP73) is a serum biomarker for liver diseases, including chronic hepatitis B. Here, we determine the effect of HBV infection on GP73 production and characterized the role of GP73 in HBV replication. Initially, we show that GP73 is highly produced in the sera of HBV-positive patients with chronic liver diseases and in HBV-stimulated leukocytes. In addition, HBV stimulation promotes GP73 production in peripheral blood mononuclear cells isolated from healthy donors and in macrophages derived from human acute monocytic leukemia cells (THP-1). Notably, the hepatitis B surface antigen (HBsAg), but not HBV replication, is required for the activation of GP73 expression. Moreover, in HepG2 cells and Huh7 cells, GP73 facilitates HBV replication and represses nuclear factor kappa B p50 expression, which in turn represses HBV replication and GP73 expression. Finally, we demonstrate that GP73 facilitates HBV replication by repressing the innate immune response and the nuclear factor kappa B signaling pathway. Taken together, we revealed a distinct positive feedback mechanism between HBV replication and GP73 production and suggest that GP73 acts as a potential antiviral target for HBV infection.     

NLRX1 negatively regulates TLR-induced NF-κB signaling by targeting TRAF6 and IKK

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Highlights? NLRX1 negatively regulates Toll-like receptor-mediated NF-κB activation ? NLRX1 disassociates from TRAF6 and then binds to the IKK complex after stimulation ? NLRX1 knockdown enhances NF-κB activation and cytokine production after stimulation ? NLRX1 knockdown in mice enhances susceptibility to septic shock and plasma IL-6     

Control of NF-κB and inflammation by the unfolded protein response

Under inflammatory situations, endoplasmic reticulum (ER) stress occurs at local sites and modulates inflammatory processes. NF-κB is a key regulator for immune and inflammatory responses, and its activity is influenced by ER stress positively or negatively. Recent investigation suggested that ER stress induces activation of NF-κB in the early phase, whereas in the later phase, consequent unfolded protein response (UPR) inhibits NF-κB. This review summarizes current knowledge on potential mechanisms underlying the biphasic, bidirectional regulation of NF-κB by the UPR and possible roles for ER stress in the regulation of inflammation.     

Characterization of mouse embryonic fibroblasts derived from Rassf6 knockout mice shows the implication of Rassf6 in the regulation of NF-κB signaling

RASSF6 is a member of the tumor suppressor Ras association domain family (RASSF) proteins. We have reported using human cancer cell lines that RASSF6 induces apoptosis and cell cycle arrest via p53 and plays tumor suppressive roles. In this study, we generated Rassf6 knockout mice by CRISPR/Cas technology. Contrary to our expectation, Rassf6 knockout mice were apparently healthy. However, Rassf6-null mouse embryonic fibroblasts (MEF) were resistant against ultraviolet (UV)-induced apoptosis/cell cycle arrest and senescence. UV-induced p53-target gene expression was compromised, and DNA repair was delayed in Rassf6-null MEF. More importantly, KRAS active mutant promoted the colony formation of Rassf6-null MEF but not the wild-type MEF. RNA sequencing analysis showed that NF-κB signaling was enhanced in Rassf6-null MEF. Consistently, 7,12-dimethylbenz(a)anthracene (DMBA) induced skin inflammation in Rassf6 knockout mice more remarkably than in the wild-type mice. Hence, Rassf6 deficiency not only compromises p53 function but also enhances NF-κB signaling to lead to oncogenesis.     

Maspin expression is regulated by the non-canonical NF-κB subunit in androgen-insensitive prostate cancer cell lines

Dysregulation of Maspin expression and constitutive activation of NF-κB subunits are important events in tumorigenesis of prostate cancer. Recent finding points that RelB, which contributes to the alternative NF-κB activity, interferes with carcinogenesis in the prostate. We report here, that both the classical and the alternative NF-κB activities are constitutively present in androgen-insensitive human prostate cancer cells. Maspin and RelB expression is correlated negatively in prostate cancer tissues at the later stage. TNF-α signaling triggers the nuclear accumulation of RelB and the concomitant reduction of Maspin expression in a time-dependent manner. In addition, the proteasome inhibitor-induced Maspin expression is accompanied by the reduction of RelB expression. A successful depletion of RelB expression, but not RelA expression, induces Maspin expression. RelB-deficiency abrogates the proteasome inhibitor-induced Maspin expression. Moreover, we demonstrate that the enforced expression of RelB protein in prostate cancer cells inhibits Maspin expression. We propose that RelB is an essential molecule controlling the endogenous and the proteasome inhibitor-induced Maspin expression. Developing a RelB-targeted therapeutic intervention, which might be coupled with the induction of a tumor suppressor Maspin, is valuable in treating advanced, metastatic prostate cancer.