During lytic infection with Epstein-Barr virus (EBV), several viral lytic proteins function to evade immune recognition or to actively suppress immune cells. An EBV lytic transactivator, Zta, induces an immunosuppressive cytokine interleukin 10 (IL-10) in B cells, but whether it regulates IL-10 in the context of epithelial cells is unclear. In this study, we tested nasopharyngeal carcinoma (NPC) cell lines and found that Zta did not induce IL-10 in these epithelial cells. Interestingly, the conditioned medium of Zta-expressing NPC cells enhanced IL-10 production from monocytes. We further revealed that the IL-10-inducing effect involved at least two immunomodulators that were upregulated by Zta and secreted from NPC cells: granulocyte-macrophage colony-stimulating factor (GM-CSF) and prostaglandin E 2 (PGE 2 ). Zta was recruited to and activated the GM-CSF promoter, thus upregulating GM-CSF expression. Zta also activated the promoter of cyclooxygenase-2 (COX-2), and Zta-induced COX-2 increased downstream PGE 2 production. Cotreatment with GM-CSF and PGE 2 synergistically induced IL-10 production from monocytes. The IL-10-inducing effect of the Ztaconditioned medium was reduced when GM-CSF or the COX-2/PGE 2 pathway was blocked. The conditioned medium of NPC cells with EBV lytic infection showed a similar increase of GM-CSF and PGE 2 levels as well as the IL-10-inducing effect on monocytes, and knockdown of Zta abolished all the effects. Therefore, through Zta-induced immunomodulators, EBV lytic infection in NPC cells can direct bystander monocytes to produce IL-10, which may be a novel way of EBV to promote local immunosuppression.Epstein-Barr virus (EBV) establishes lifelong persistence in more than 90% of the adult population worldwide, showing its successful dealings with the human immune system (51). Compared with EBV latent infection, in which only few viral antigens are expressed, the lytic infection expresses abundant viral proteins with high antigenicity, serving as a more attractive target recognized and attacked by the host immune system. To survive under the immune surveillance, EBV is equipped with several lytic proteins that evade immune recognition. For example, major histocompatibility complex (MHC) class I-restricted antigen presentation is inhibited by EBV BNLF2a, which blocks peptide transport (25), and by BILF1, which promotes degradation of MHC class I molecules (62). MHC class II-restricted antigen presentation is hampered by the interaction between EBV BZLF2 and MHC class II molecules (50). Moreover, expression of MHC class I and II genes can be downregulated by other EBV lytic proteins: Zta acting at the transcriptional level and BGLF5 acting at the posttranscriptional level (32,38,52).In addition to the strategies that prevent EBV from being recognized by immune cells, EBV may actively cause suppressive effects on immune cells during the lytic cycle, through several secreted factors that are encoded or induced by EBV.
Zta is a lytic transactivator of Epstein-Barr virus (EBV) and has been shown to promote migration and invasion of epithelial cells. Although previous studies indicate that Zta induces expression of matrix metalloproteinase (MMP) 9 and MMP1, direct evidence linking the MMPs to Zta-induced cell migration and invasion is still lacking. Here we performed a series of in vitro studies to re-examine the expression profile and biologic functions of Zta-induced MMPs in epithelial cells derived from nasopharyngeal carcinoma. We found that, in addition to MMP9, MMP3 was a new target gene upregulated by Zta. Ectopic Zta expression in EBV-negative cells increased both mRNA and protein production of MMP3. Endogenous Zta also contributed to induction of MMP3 expression, migration and invasion of EBV-infected cells. Zta activated the MMP3 promoter through three AP-1 elements, and its DNA-binding domain was required for the promoter binding and MMP3 induction. We further tested the effects of MMP3 and MMP9 on cell motility and invasiveness in vitro. Zta-promoted cell migration required MMP3 but not MMP9. On the other hand, both MMP3 and MMP9 were essential for Zta-induced cell invasion, and co-expression of the two MMPs synergistically increased cell invasiveness. Therefore, this study provides integrated evidence demonstrating that, at least in the in vitro cell models, Zta drives cell migration and invasion through MMPs.
We have identified two azoospermic men with r(Y) in 312 infertile men presenting with non-obstructive azoospermia or oligozoospermia. Their karyotypes were 45,X [9]/46,X, r(Y)(p11q11) [11] (case 1), and 46,X,r(Y)(p11q11) (case 2), respectively. In both cases, the Yp breakpoints were located within the pseudoautosomal region. Both cases had extensive deletions of azoospermia factors (AZFs). Case 1 also had deletion of the putative growth controlling gene (GCY) and the Yq breakpoint was located between sY741 and USP9Y. The Yq breakpoint was located between sY105 and sY109 in case 2. Both cases did not have Turner stigmata except short stature in case 1. By a combination of cytogenetic and molecular genetic tools, we showed r(Y) arose from breakage in both arms of the chromosome with subsequent fusion of two broken ends of the centric fragment to form a continuous ring. Spermatogenic defects in men with r(Y) may result from deletion of Y-linked AZFs combined with synaptic failure.
Background/Aim: Rta, a transactivator of Epstein-Barr virus, is associated with progression of nasopharyngel carcinoma (NPC); however, its mechanism of contribution to the pathogenesis of NPC remains unclear. , a tumor promoter, is detected in NPC. This in vitro study examined whether and how Rta promotes NPC progression by up-regulating IL-6. Materials and Methods: Semiquantitative reverse transcription-polymerase chain reaction (RT-PCR), quantitative real-time PCR, ELISA, immunoblotting assays, reporter gene assays, and transwell migration assays were performed. Results: In NPC cells, Rta up-regulated IL-6 expression at the mRNA and protein levels, and the Rta's C-terminus was essential for promoter activation and expression of IL-6. The induction of IL-6 by Rta also required activation of extracellular signal-regulated kinase 1/2 and activator protein-1. Furthermore, IL-6 secreted from Rta-expressing NPC cells promoted migration of Rtanegative NPC cells by activating IL-6 receptor/Janus kinase/signal transducer and activator of transcription 3 pathway. Conclusion: Rta contributes to progression of NPC cells through induction of IL-6 in vitro.Interleukin-6 (IL-6) is a cytokine that is expressed in multiple tumor tissues, e.g., breast cancer, colorectal cancer and nasopharyngeal carcinoma (NPC) (1-3), suggesting that it exists in the tumor microenvironment. Binding of IL-6 to IL-6 receptor (IL-6R) on tumor cells in a paracrine or an autocrine manner activates the downstream Janus kinase (JAK)/signal transducer and activator of transcription 3 (STAT3) pathway, thus promoting the migration, invasion, or metastasis of tumor cells (4). Patients with NPC exhibit elevated serum IL-6 levels associated with distant metastasis and poor survival (5,6). IL-6 also promotes the growth, migration and invasion of NPC cells (7). Therefore, IL-6 may contribute to NPC progression.Rta, an Epstein-Barr virus (EBV) lytic transactivator, participates in the initiation of EBV reactivation (8). The Nterminus of Rta protein mediates DNA binding and dimerization, whereas its C-terminus contains a transactivation domain functions for regulating its target gene expression and protein-protein interaction (9, 10). Additionally, Rta also has a nuclear localization signal (NLS) in its C-terminus, which helps the protein to enter the nucleus (11). Acting as a transactivator, Rta activates viral or cellular genes via direct binding to the Rta-responsive element (RRE) (9, 12, 13). However, Rta can regulate gene expression through several RRE-independent mechanisms, such as activation of some cellular signaling pathways (14, 15) and interaction with other transcription factors (16).Recently, clues for linking Rta to the pathogenesis of NPC were reported, e.g., the protein was detected in NPC biopsy specimens (17). Moreover, the levels of anti-Rta antibodies 3255 *These Authors contributed equally to this study.
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