Overexpression of syntenin-1 enhances production of low-density hepatitis C virus particles / 第二军医大学学报

Objective To investigate the effect of syntenin-1 on the assembly of hepatitis C virus (HCV) particles. Methods The content of syntenin-1 in human primary hepatocytes was detected by Western blotting analysis. Human hepatocellular carcinoma cell line Huh7.5.1 was transfected with lentiviral plasmids to construct syntenin-1 overexpressed cell line and green fluorescent protein (GFP) overexpressed cell line. After transferring HCV RNA into Huh7.5.1 cells, syntenin-1 overexpressed cells and GFP overexpressed cells by electroporation, the effects of syntenin-1 overexpression on HCV in the cells were investigated in terms of RNA replication, viral protein contents and secretion of infectious virus particles by luciferase analysis, Western blotting and virus titer, respectively. The density of viral particles was assessed by isopycnic ultracentrifugation to analyze the distributions of HCV RNA and infective titer. Results The contents of syntenin-1 in three human primary hepatocytes were higher than that in the Huh7.5.1 cells (P0.01). Syntenin-1 overexpression had no effect on HCV RNA replication in host cells; the infectivity of HCV derived from syntenin-1 overexpressed cells was not significantly different compared with the Huh7.5.1 cells or GFP overexpressed cells. In syntenin-1 overexpressed cell culture supernatants, some infectious HCV particles mainly concentrated in the region of concentration of 1.08-1.16 g/mL gradually transferred to the low-density region of 1.01-1.02 g/mL. Conclusion Syntenin-1 overexpression alters the distribution of density components of infectious HCV particles.

The study on molecular mechanism underlying the pro-invasion and pro-migration of Syntenin in glioma cells / 中国神经精神疾病杂志

Objective To investigate the effect of different gene expression levels of Syntenin on invasion and mi?gration of glioma cells and the underlying molecular mechanisms. Methods Lentiviral RNA interference was used to knockdown the expression of syntenin in U-87 cells. Real-time quantitative PCR was used to detect mRNA expression levels of syntenin . Transwell assay and adhesion assay were used to examine the invasion, migration and adhesion, re?spectively. Western-blot was used to detect the protein expression levels of Syntenin, AKT, p-AKT, and MMP-9. Re?sults The mRNA expression level of Syntenin was greatly reduced in interference group compared with empty vector group (P0.05). Conclusion Syntenin may enhance the invasion and migration ability of glioma though up-regulation of p-AKT, which in turn pro?motes MMP-9 expression in a corresponding signal transduction pathway.

Syntenin increases the invasiveness of small cell lung cancer cells by activating p38, AKT, focal adhesion kinase and SP1

Syntenin is a PDZ domain-containing adaptor protein that has been recently shown to regulate migration and invasion in several tumors. Small cell lung cancer (SCLC) is notorious for its invasiveness and strong potential for metastasis. We therefore studied the influence of syntenin on the invasiveness of SCLC. Immunohistochemistry in tumor tissues showed that syntenin was more frequently expressed in small cell carcinomas than other neuroendocrine tumors, such as carcinoids and neuroblastomas, suggesting that syntenin expression may be related to more aggressive forms of neuroendocrine tumors. In SCLC patients, syntenin overexpression in tumor cells was significantly associated with more extensive and advanced disease at the time of diagnosis (P=0.029). Overexpression of syntenin in SCLC cells that were intrinsically syntenin-low increased the invasiveness of cells and led to the induction of extracellular matrix (ECM)-degrading membrane type 1-matrix metalloproteinase (MT1-MMP) and matrix metalloproteinase 2 (MMP2). In contrast, suppression of syntenin in syntenin-high cells was associated with the downregulation of MT1-MMP. Contrary to the results of previous studies using malignant melanomas and breast carcinomas, signaling cascades were shown to be further transduced through p38 MAPK and PI3K/AKT, with activation of SP1 rather than NF-kappaB, under circumstances not involving ECM interaction. In addition, the upstream molecule focal adhesion kinase was induced by syntenin activation, in spite of the absence of ECM interaction. These results suggest that syntenin might contribute to the invasiveness of SCLC and could be utilized as a new therapeutic target for controlling invasion and metastasis in SCLC.

Syntenin Is Expressed in Human Follicular Dendritic Cells and Involved in the Activation of Focal Adhesion Kinase

Syntenin is an adaptor molecule containing 2 PDZ domains which mediate molecular interactions with diverse integral or cytoplasmic proteins. Most of the results on the biological function of syntenin were obtained from studies with malignant cells, necessitating exploration into the role of syntenin in normal cells. To understand its role in normal cells, we investigated expression and function of syntenin in human lymphoid tissue and cells in situ and in vitro. Syntenin expression was denser in the germinal center than in the extrafollicular area. Inside the germinal center, syntenin expression was obvious in follicular dendritic cells (FDCs). Flow cytometric analysis with isolated cells confirmed a weak expression of syntenin in T and B cells and a strong expression in FDCs. In FDC-like cells, HK cells, most syntenin proteins were found in the cytoplasm compared to weak expression in the nucleus. To study the function of syntenin in FDC, we examined its role in the focal adhesion of HK cells by depleting syntenin by siRNA technology. Knockdown of syntenin markedly impaired focal adhesion kinase phosphorylation in HK cells. These results suggest that syntenin may play an important role in normal physiology as well as in cancer pathology.