Influences of Site-directed Mutagenesis of a Recombinant Didintegrin from Gloydius blomhoffi brevicaudus on Its Biological Activities / 中国生物化学与分子生物学报

Arg-Gly-Asp (RGD) is a unique minimal integrin-binding sequence found within several glycoprotein ligands and also in snake-venom disintegrins. Adinbitor, a protein with 73 amino acid residues including 12 cysteins and an RGD motif, was cloned from Gloydius blomhoffi brevicaudus in my laboratory. As a new member of disintegrin family, adinbitor can inhibit both human platelet aggregation induced by ADP and angiogenensis in vivo and in vitro, the typical characters of disintegrin family. To separate the effect of inhibiting platelet aggregation from that of inhibiting angiogenensis, the motif KGD was introduced into adinbitor cDNA to replace RGD by site-directed and PCR-based mutagenesis. The recombinant protein (recombinant adinbitor (KGD)) was expressed in E. coli BL21 and purified through the His· Bind affinity chromatography. Recombinant adinbitor (KGD) could inhibit ADP-induced platelet aggregation with IC50 value of 85 nmol/L. Considerably, it was a more effective inhibitor on platelet aggregation than recombinant adinbitor (RGD), which has an IC50 of 150 nmol/L. Interestingly, recombinant adinbitor (KGD) has no potency in inhibiting angiogenesis in vivo compared with recombinant adinbitor (RGD). These findings showed that KGD containing adinbitor was more suitable for inhibiting ADP-induced human platelet aggregation as a potential and specific inhibitor of human platelet aggregation, which might have promising therapeutic potential as an antithrombotic agent.

Effects of Recombinant Disintegrin rAdinbitor on FAK-Ras/MAPK Pathway in C6 Glioma Cells / 生物化学与生物物理进展

rAdinbitor was cloned from Gloydius blomhoffi brevicaudus in the laboratory. Previous researches had proved that rAdinbitor could inhibit proliferation of C6 glioma cells as well as promote their apoptosis. The molecular mechanism of rAdinbitor’s effects on C6 cells need to be further studied. rAdinbitor was expressed in E. coli BL21/pET23b-adinbitor and purified with Ni Sepharose 6 Fast Flow. The purified protein was confirmed by Western blotting. C6 cells were induced with fibronectin (FN). The effects of rAdinbitor with different concentrations on the expression of FAK, MEK1/2 and Caspase-3 as well as on activity of FAK and ERK1/2 in FN-induced C6 cells were studied by immunoblotting and immunoprecipitation. Results showed that rAdinbitor with different concentrations could obviously reduce the expression of FAK and MEK1/2, increase the expression of Caspase-3, as well as decrease ERK1/2 phosphorylation; besides 10 mg/L rAdinbitor, other concentrations’ rAdinbitor could inhibit FAK phosphorylation obviously. All those effects were dose-dependent. Results indicate that the effects of rAdinbitor on decreasing expression and activity of FAK and inhibiting Ras-MAPK signaling pathway play an important role in suppressing the proliferation of C6. Furthermore, the increase in Caspase-3 expression implies that the increase in apoptosis of C6 cells might be due to the suppression of rAdinbitor on the activity of ILK and PI-3K/Akt pathway.