Construction, Expression and Internalization Study of Human Anti-HBsAg Single Chain Antibody/EGFP Fusion Proteins Containing Arg9 / 中国生物工程杂志

Objective: To construct, express and purify ScFvl4/EGFP fusion proteins which containing Arg9, and to study their binding activities and internalization functions. Methods: Arg9 gene was recombined into 5' terminal, 3' terminal of ScFv/EGFP gene and between them respectively before they were cloned into the expression vector pET32a. After induced in E. coli BL21 and purified, their binding activities and internalization were respectively analyzed by indirect ELISA and indirect immunofluorescence analysis. Results: DNA sequencing and restriction endonuclease digestion proved that the four fusion genes were correctly constructed. SDS-PAGE analysis and Western blot showed that they were successfully expressed and purified. Indirect ELISA confirmed that the expressed products had antigen specific binding activities. Indirect immunofluorescence analysis revealed the fusion protein containing Arg9 at its N terminal had much better internalization function, but never internalized into the cells which do not express HBsAg. Conclusion: The four fusion genes were constructed, expressed and purified successfully. The purified fusion proteins maintained the binding activities to HBsAg and the fusion protein containing Arg9 at its N terminal had much better internalization effect.

Investigation of Apoptosis of the SGC7901 Cells Induced by the Expression of the Recombinant Gene of anti-HER2 ScFv/tBid / 中国生物工程杂志

Objetive: To investigate whether apoptosis of SGC7901 cells can be induced by the expression of the recombinant gene of anti-HER2 ScFv/tBid. Methods: The recombinant anti-HER2 ScFv/tBid gene was cloned into vector pCMV and the recombinant plasmid was transfected into SGC7901 cells. The gene expression was detected by RT-PCR and immunofluorescent staining. Cell counting was carried out to show the effect of the gene transfection on cell growth. At the same time, significant apoptotic peak was detected by flow cytometry in recombinant anti-HER2 ScFv/tBid gene transfected cells. Results: The fusion protein of anti-HER2 ScFv/tBid was observed in the cytoplasm of transfected SGC7901 cells. The transfected cells displayed typical cell growth inhibition and apoptosis. Conclusion: Fusion protein of anti-HER2 ScFv/tBid can induce apoptosis of SGC7901.

Growth inhibitory effects of recombinant granzyme B containing different N-terminal translocating peptides / 生物工程学报

Translocating protein and translocating peptides have therapeutic potential against tumors by exposing the cytotoxic domains of toxic proteins to the cell cytosol. The aim of this study is to investigate the effect of N-terminally fused PE translocating peptides on granzyme B (GrBa) activity. PE II-GrBa fusion protein genes were constructed by replacing N-terminal signal and acidic dipeptide sequence of human granzyme B gene with two truncated translocating sequences of Pseudomonas exotoxin A (PE II aa 280-364/358) by recombinant PCR, and then cloned into pIND inducible expression vector. The resulting pIND-PE II-GrBa expression vectors were co-transfected with assistant plasmid pVgRXR into HeLa cells through lipofectamine, followed by selection on G418 and zeocin. The resistant cells were collected and induced with ponasterone A. Western blot analysis demonstrated that ponasterone A induction caused the expression of PE II-GrBa fusion proteins, and indirect immunofluorescence detected giant sized multinucleated cells, suggesting cytoskeletal and mitotic abnormalities as reported in our previous studies. Western blot, enzymatic activity assay and cell counting analysis indicated that two types of PE II-GrBa fusion proteins were capable of cleaving both endogenous and exogenous substrates of granzyme B, and inhibiting the growth of cells. The PE II (aa 280-358)-GrBa was shown to have higher serine protease activity and stronger growth inhibitory effect. Such inhibition was presumably associated with G2 arrest as determined by cell cycle analysis. These data prove that PE II-GrBa fusion proteins have cell inhibitory effect similar to GrBa, and that the shorter PE-derived peptide exerts less influence on GrBa activity. This study helps to optimize the construction of recombinant protein comprising translocating peptides and cytotoxic molecules for tumor cell killing.

Effect of anions and anion channel blockers on vascular tone in rat aorta / 中国应用生理学杂志

<p><b>AIM</b>To investigate the action of anions and anion channel blockers in the regulation of vascular contraction induced by norepinephrine (NE).</p><p><b>METHODS</b>NE-induced contraction was observed in rat aorta by using routine blood vascular perfusion in vitro.</p><p><b>RESULTS</b>The anion channel blockers niflumic acid (NFA) and 5-nitro-2-(3-phenoxylpropylamino)-benzoic acid (NPPB) produced inhibitory effects on NE-evoked contractions in the aorta. NE-induced contraction was not significantly changed after the extracellular Na+ was replaced by choline, in contrast, the vascular was relaxed when the extracellular Cl- was replaced by glutamate. Moreover, the vasoconstriction induced by NE was further enhanced with the replacement of the extracellular Cl- by Br-, which was still sensitive to either NFA or NPPB.</p><p><b>CONCLUSIONS</b>Anion channels play an important role in the regulation of blood vascular tone, which may be responsible for the salt-sensitivity hypertension.</p>

Effects of niflumic acid on the proliferation of human hepatoma cells / 生理学报

The purpose of this work was to investigate the effects of niflumic acid (NFA), a chloride channel blocker, on the proliferation of human hepatoma cell line (HHCC). Cell proliferation was analyzed by cell count and MTT assay. Cell cycle analysis was carried out by flow cytometry. [Ca(2+)](i) was determined by laser scanning confocal system. It was found that NFA decreased significantly the cell number and the MTT optical density (OD) of HHCC cells, and that the OD value was reversed after washout of NFA. Compared with control, NFA blocked cell cycle progression in G(1) phase. Extracellular application of NFA (100 micromol/L) induced a rapid decrease in [Ca(2+)](i). These findings demonstrate that blockage of chloride channels by NFA induces growth arrest of HHCC in G(1) phase, which may be due to the inhibition of Ca(2+)/CaM-dependent signaling pathways.