[Combination of AD5-10 and epirubicin in treating rheumatoid arthritis].

OBJECTIVE: To investigate the mechanism of anti-death receptor 5-10 (AD5-10) combined with epirubicin in treating rheumatoid arthritis (RA). METHODS: We detected the cell viability of the fibroblast-like synoviocytes (FLS) from RA patients with MTT. The expression level of apoptosis signaling pathways protein, p53, and p21 were evaluated with Western blot. RESULTS: We found that epirubicin, at different doses, could enhance the effect of AD5-10 on FLS, promoting the apoptosis of FLS. The expression levels of caspase-3, -8, -9, c-FLIP, Bcl-2, p53, and p21 in the FLS changed after epirubicin treatment. CONCLUSION: Epirubicin may coordinate with AD5-10 in inducing FLS apoptosis through affecting the levels of p53, p21, c-FLIP, and Bcl-2.

[Expression and purification of heptad repeat region of the mumps virus F protein and analysis of characteristics].

Two Heptad repeat motifs (HR1 and HR2) from paramyxoviruses F protein could form thermostable heterodimers containing high alpha-helix while virus infected host cell. Following that the viral membrane and the host cell membrane were juxtaposed, which leads to membrane fusion. Mumps virus (MuV) is a member of the genus Rubulavirus in the family of Paramyxoviridae. MuV could use similar infection mechanism as well as other paramyxoviruses. In this study the HR1 and HR2 regions of MuV F protein were predicted by a computer program and expressed in E. coli with the GST fusion expression system. The GST fusion or GST-removed proteins were purified with Gluthathion Sepharose 4B Column. GST pull-down experiment suggested the interaction of HR1 and HR2 peptides, and analysis of gel filtration showed two peptides could form multimer, which indicates that the HR regions of MuV F protein may play an important role in virus fusion.

Crystallization and preliminary X-ray diffraction analysis of post-fusion six-helix bundle core structure from Newcastle disease virus F protein.

Fusion of virus members from the Paramyxoviridae family involves two glycoproteins. They are termed attachment glycoprotein (HN, H or G) and fusion protein (F). The F protein contains two highly conserved heptad-repeat (HR) regions, HR1 and HR2. Through conformational changes in the F protein, HR1 and HR2 are believed to form a stable six-helix coiled-coil bundle during the membrane-fusion process. However, no crystal structure has yet been documented for this state in the Newcastle disease virus (NDV, a member of the Paramyxoviridae family) F protein, despite the recent success on its F(0) crystal structure (Chen et al., 2001), which was thought to represent the pre-fusion conformation of F glycoprotein. In this study, a single-chain polypeptide constructed by linking two truncated HR regions of the NDV F protein has been expressed, purified and crystallized by means of the hanging- or sitting-drop vapour-diffusion method. Crystals in hexagonal and trapezoid forms with a resolution limit of 2.6 A were obtained. These crystals belonged to space group C2, with unit-cell parameters a = 66.4, b = 38.2, c = 102.0 A, beta = 100.2 degrees. Crystals in the rhombic form with a resolution limit of 2.5 A were also obtained. These crystals belonged to space group P2(1), with unit-cell parameters a = 59.0, b = 31.9, c = 62.3 A, beta = 117.0 degrees. This will add to the repertoire of viral fusion protein post-fusion state structures and help further the understanding of the molecular mechanism of enveloped virus fusion.