ABSTRACT
Aim To study the effect of tetrandrine derivative HL-49 on the conformation and biological ac-tivity of Bloom helicase ( BLM ) , and to explore its antitumor mechanism.Methods The effect of HL-49 on the conformation of BLM helicase was studied by ultra- violet spectroscopy.The effects of HL-49 on DNA binding activity, DNA chain dissociation activity and ATPase activity of HL-49 on BLM DNA helicase were analyzed by fluorescence polarization and malachite green-ammonium phosphomolybdate colorimetric method.Results HL-49, a tetrandrine derivative, indirectly inhibited the ATPase activity of BLM DNA heli- case and DNA unwinding activity by reversible binding with DNA.The results of fluorescence polarization experiments showed that HL-49 could not affect the bind ing activity of BLM DNA helicase to DNA (dsDNA/ss- DNA) , but could bind to DNA in a concentration-de- pendent manner (P < 0.01).With the increase of HL- 49 concentration, the DNA unwinding ability of BLM DNA helicase decreased, and the Kobs value decreased gradually.The results of malachite green-ammonium phosphomolybdate colorimetry showed that HL-49 could significantly inhibit the ATPase activity of BLM DNA helicase.Conclusions HL49 can inhibit the ATPase activity and DNA unwinding activity of BLM DNA helicase by the reversible binding with DNA.
ABSTRACT
Aim To investigate the effects of bisbenzyl-isoquinoline alkaloid tetrandrine derivative HL-27 on the biological properties of the BLM642-1290 helicase. Methods Fluorescence polarization technique was used to investigate the effects of bisbenzylisoquinoline alkaloid tetrandrine derivative HL-27 on the DNA bind-ing activity and unwinding activity of the BLM642-1290 helicase. Malachite green-phosphate ammonium molyb-date colorimetry was used to investigate the effects of HL-27 on the ATPase activity of the BLM642-1290 heli-case. Ultraviolet spectral scanning was used to investi-gate the effects of HL-27 on the conformation of the BLM642-1290 helicase. Results When the concentra-tion of HL-27 reached 33.34 μmol·L-1, the inhibi-tion ratio of dsDNA and ssDNA binding activity of the BLM642-1290 helicase was 41.35% and 59.54% , re-spectively. When the concentration of HL-27 reached 50 μmol·L-1, the inhibition ratio of DNA unwinding activity of the BLM642-1290 helicase was 78.68% . When the concentration of HL-27 reached 100 μmol· L-1, the inhibition ratio of ATPase activity of the BLM642-1290 helicase was 43.8% . Conclusion The DNA binding activity, ATPase activity and unwinding activity of the BLM642-1290 helicase can be inhibited by bisbenzylisoquinoline alkaloid tetrandrine derivative HL-27.
ABSTRACT
Mesenchymal stem cells are capable of differentiating into Schwann-like cells. In this study, we induced human umbilical-cord mesenchymal stem cells (HUMSCs) in vitro into neurospheres constituted by neural stem-like cells, and further into cells bearing strong morphological, phenotypic and functional resemblances with Schwann-like cells. These HUMSC-derived Schwann-like cells, after grafting into the injured area of the rats' spinal cord injury (SCI), showed a partial therapeutic effect in terms of improving the motor function. Neurotrophin-3 (NT-3) was reported to improve the local microenvironment of the grafted cells, and we, therefore, further tested the effect of Schwann-like cell grafting combined with NT-3 administration at the site of cell transplantation. The results showed that NT-3 administration significantly promoted the survival of the grafted cells in the host-injured area. Significant improvement in rats treated by Schwann-like cell grafting combined with NT-3 administration was demonstrated in the behavioral test as compared with that in animal models received the cell grafting only. These results suggest that transplantation of the Schwann-like cells combined with NT-3 administration may represent a new strategy of stem cell therapy for spinal cord injury.
