Cells in G_2/M phase increased in human nasopharyngeal carcinoma cell line by EBV-LMP1 through activation of NF-кB and AP-1

Although previous studies showed that the principal oncoprotein encoded by Epstein-Barr virus, latentmembrane protein 1 (LMP1) 5 could induce the nasopharyngeal carcinoma cells in G_2/M phase increased, littleis known about the target molecules and mechanisms. The present study demonstrated that LMP1 couldinduce the accumulation of p53 protein and upregulate its transactivity in a dose dependent manner, whichresulted in the decrease of the kinase activity of cdc2/cyclin B complex and inducing arrest at G2/M phasethrough the activation of NF-κB and AP-1 signaling pathways, and the effect of NF-κB was more obviousthan that of AP-1. This study provided some significant evidence for further elucidating the molecularmechanisms that LMP1 had effects on the surveillance mechanism of cell cycle and promoting the survivalof transformed cells and tumorigenesis.     

Granulocyte-macrophage colony-stimulating factor （GM-CSF） and T-cell responses： what we do and don＇t know

Granulocyte-macrophage colony-stimulating factor （GM-CSF） is an important hematopoietic growth factor and immune modulator. GM-CSF also has profound effects on the functional activities of various circulating leukocytes. It is produced by a variety of cell types including T cells, macrophages, endothelial cells and fibroblasts upon receiving immune stimuli. Although GM-CSF is produced locally, it can act in a paracrine fashion to recruit circulating neutrophils, monocytes and lymphocytes to enhance their functions in host defense. Recent intensive investigations are centered on the application of GM-CSF as an immune adjuvant for its ability to increase dendritic cell （DC） maturation and function as well as macrophage activity. It is used clinically to treat neutropenia in cancer patients undergoing chemotherapy, in AIDS patients during therapy, and in patients after bone marrow transplantation. Interestingly, the hematopoietic system of GM-CSF-deficient mice appears to be normal; the most significant changes are in some specific T cell responses. Although molecular cloning of GM-CSF was carried out using cDNA library oft cells and it is well known that the T cells produce GM-CSF after activation, there is a lack of systematic investigation of this cytokine in production by T cells and its effect on T cell function. In this article, we will focus mainly on the immunobiology of GM-CSF in T cells.     

Oncoprotein p28^GANK binds to RelA and retains NF-κB in the cytoplasm through nuclear export

p28^GANK （also known as PSMD 10, p28 and gankyrin） is an ankyrin repeat anti-apoptotic oncoprotein that is commonly overexpressed in hepatocellular carcinomas and increases the degradation of p53 and Rb. NF-IκB （nuclear factor-κB） is known to be sequestered in the cytoplasm by IκB （inhibitor of NF-κB） proteins [1, 2], but much less is known about the cytoplasmic retention of NF-κB by other cellular proteins. Here we show that p28^GANK inhibits NF-κB activity. As a nuclear-cytoplasmic shuttling protein, p28^GANK directly binds to NF-κB/RelA and exports RelA from nucleus through a chromosomal region maintenance-1 （CRM-1） dependent pathway, which results in the cytoplasmic retention of NF- κB/RelA. We demonstrate that all the ankyrin repeats of p28^GANK are required for the interaction with RelA and that the N terminus of p28^GANK, which contains the nuclear export sequence （NES）, is responsible for suppressing NF-κB/RelA nuclear translocation. These results suggest that overexpression of p28^GANK prevents the nuclear localization and inhibits the activity of NF-κB/RelA.     

Early Pattern of Epstein-Barr Virus Infection in Gastric Epithelial Cells by “Cell-in-cell”

Epstein-Barr virus(EBV)is an important human dsDNA virus,which has been shown to be associated with several malignancies including about 10%of gastric carcinomas.How EBV enters an epithelial cell has been an interesting project for investigation."Cell-in-cell"infection was recently reported an efficient way for the entry of EBV into nasopharynx epithelial cells.The present approach was to explore the feasibility of this mode for EBV infection in gastric epithelial cells and the dynamic change of host inflammatory reaction.The EBV-positive lymphoblastic cells of Akata containing a GFP tag in the viral genome were co-cultured with the gastric epithelial cells(GES-1).The infection situation was observed under fluorescence and electron microscopies.Real-time quantitative PCR and Western-blotting assay were employed to detect the expression of a few specific cytokines and inflammatory factors.The results demonstrated that EBV could get into gastric epithelial cells by"cell-in-cell"infection but not fully successful due to the host fighting.IL-1β,IL-6 and IL-8 played prominent roles in the cellular response to the infection.The activation of NF-κB and HSP70 was also required for the host antiviral response.The results imply that the gastric epithelial cells could powerfully resist the virus invader via cell-in-cell at the early stage through inflammatory and innate immune responses.     

Monocyte/Macrophage-Mediated Innate Immunity in HIV-1 Infection:From Early Response to Late Dysregulation and Links to Cardiovascular Diseases Onset

Although monocytes and macrophages are key mediators of the innate immune system, the focus has largely been on the role of the adaptive immune system in the context of human immunodeficiency virus(HIV) infection. Thus more attention and research work regarding the innate immune system—especially the role of monocytes and macrophages during early HIV-1 infection—is required. Blood monocytes and tissue macrophages are both susceptible targets of HIV-1 infection,and the early host response can determine whether the nature of the infection becomes pathogenic or not. For example,monocytes and macrophages can contribute to the HIV reservoir and viral persistence, and influence the initiation/extension of immune activation and chronic inflammation. Here the expansion of monocyte subsets(classical, intermediate and non-classical) provide an increased understanding of the crucial role they play in terms of chronic inflammation and also by increasing the risk of coagulation during HIV-1 infection. This review discusses the role of monocytes and macrophages during HIV-1 pathogenesis, starting from the early response to late dysregulation that occurs as a result of persistent immune activation and chronic inflammation. Such changes are also linked to downstream targets such as increased coagulation and the onset of cardiovascular diseases.     

Involvement of ayu NOD2 in NF-κB and MAPK signaling pathways: Insights into functional conservation of NOD2 in antibacterial innate immunity

Nucleotide oligomerization domain 2(NOD2) is a major cytoplasmic sensor for pathogens and is critical for the clearance of cytosolic bacteria in mammals.However, studies regarding NOD2, especially the initiated signaling pathways, are scarce in teleost species. In this study, we identified a NOD2 molecule(PaNOD2) from ayu(Plecoglossus altivelis).Bioinformatics analysis showed the structure of NOD2 to be highly conserved during vertebrate evolution. Dual-luciferase reporter assays examined the activation of NF-κB signaling and Western blotting analysis detected the phosphorylation of three MAP kinases(p-38, Erk1/2, and JNK1/2).Functional study revealed that, like its mammalian counterparts, PaNOD2 was the receptor of the bacterial cell wall component muramyl dipeptide(MDP), and the leucine-rich repeat motif was responsible for the recognition and binding of Pa NOD2 with the ligand. Overexpression of PaNOD2 activated the NF-κB signaling pathway, leading to the upregulation of inflammatory cytokines, including TNF-α and IL-1β in HEK293 T cells and ayu head kidney-derived monocytes/macrophages(MO/MΦ).Particularly, we found that PaNOD2 activated the MAPK signaling pathways, as indicated by the increased phosphorylation of p-38, Erk1/2, and JNK1/2, which have not been characterized in any teleost species previously. Our findings proved that the NOD2 molecule and initiated pathways are conserved between mammals and ayu. Therefore, ayu could be used as an animal model to investigate NOD2-based diseases and therapeutic applications.     

The role of Toll-like receptors in non-infectious lung injury

The role of Toll-like receptors （TLRs） in pathogen recognition has been expeditiously advanced in recent years. However, investigations into the function of TLRs in non-infectious tissue injury have just begun. Previously, we and others have demonstrated that fragmented hyaluronan （HA） accumulates during tissue injury. CD44 is required to clear HA during tissue injury, and impaired clearance of HA results in unremitting inflammation. Additionally, fragmented HA stimulates the expression of inflammatory genes by inflammatory cells at the injury site. Recently, we identified that HA fragments require both TLR2 and TLR4 to stimulate mouse macrophages to produce inflammatory chemokines and cytokines. In a non-infectious lung injury model, mice deficient in both TLR2 and TLR4 show an impaired transepithelial migration of inflammatory cells, increased tissue injury, elevated lung epithelial cell apoptosis, and decreased survival. Lung epithelial cell overexpression of high molecular mass HA protected mice against acute lung injury and apoptosis, in part through TLR-dependent basal activation of NF-κB. The exaggerated injury in TLR2 and TLR4 deficient mice appears to be due to impaired HA-TLR interactions on epithelial cells. These studies identify that host matrix component HA and TLR interactions provide signals that initiate inflammatory responses, maintain epithelial cell integrity, and promote recovery from acute lung injury.     

Hsp90 inhibition results in autophagy-mediated proteasome-independent degradation of IκB kinase （IKK）

Autophagic and proteasomal proteolysis are two major pathways for degradation of cellular constituents. Current models suggest that autophagy is responsible for the nonselective bulk degradation of long-lived proteins and organelles while the proteasome specifically degrades short-lived proteins including misfolded proteins caused by the absence of Hsp90 function. Here, we show that the IκB kinase （IKK）, an essential activator of NF-κB, is selectively degraded by autophagy when Hsp90 is inhibited by geldanamycin （GA）, a specific Hsp90 inhibitor showing highly effective anti-tumor activity. We find that in this case inactivation of ubiquitination or proteasome fails to block IKK degradation. However, inhibition of autophagy by an autophagy inhibitor or knockout of Atg5, a key component of the autophagy pathway, significantly rescues IKK from GA-induced degradation. These findings provide the first evidence that an Hsp90 client may be degraded by a mechanism different from the proteasome pathway and establish a molecular link among Hsp90, NF-κB and autophagy     

Mechanisms of the alternative activation of macrophages and non-coding RNAs in the development of radiation-induced lung fibrosis

Radiation-induced lung fibrosis(RILF) is a common side effect of thoracic irradiation therapy and leads to high mortality rates after cancer treatment. Radiation injury induces inflammatory M1 macrophage polarization leading to radiation pneumonitis, the first stage of RILF progression. Fibrosis occurs due to the transition of M1 macrophages to the anti-inflammatory pro-fibrotic M2 phenotype, and the resulting imbalance of macrophage regulated inflammatory signaling. Non-coding RNA signaling has been shown to play a large role in the regulation of the M2 mediated signaling pathways that are associated with the development and progression of fibrosis. While many studies show the link between M2 macrophages and fibrosis, there are only a few that explore their distinct role and the regulation of their signaling by non-coding RNA in RILF. In this review we summarize the current body of knowledge describing the roles of M2 macrophages in RILF, with an emphasis on the expression and functions of non-coding RNAs.