ABSTRACT
Objective To investigate the radioresistant effects of pprI gene of Deinococcus radiodurans on BALB/c mice.Methods Male BALB/c mice in SPF level were applied for this work.The pEGFP-c1 plasmid and pEGFP-c1-pprI gene recombinant plasmid were transferred into anterolateral muscle of mice with in vivo electroporation technology.The mice were irradiated by 6 Gy 60Co γ-rays in whole body and the mortality of mice was observed within 30 days after irradiation.In addition,the mouse were irradiated with 4 Gy γ-rays and then the peripheral blood cell number,apoptosis rates of thymocyte cells,spleen cells and bone marrow cells were observed in the days of 1,7,14,28 and 35 after irradiation while the histopathological changes of lung and testis were observed in the days 7 and 28 after γ-ray irradiation.Results The highest gene transfection efficiency of muscle cells was obtained in a Plasmid injection amount of 50 μg/50 μl and electric field strength of 200 V/cm.The acute radiation mortality of pEGFP-c1-pprI gene recombinant plasmid transfer group was 30％,lower than that of irradiation group (60.0％) and pEGFP-c1 plasmid transfer group (63.3％) after 6 Gy γ-ray irradiation (x2 =4.90,6.24,P ＜ 0.05).Compared with the irradiation group and pEGFP-c1 plasmid transfer group,the WBC count of pEGFP-c1-pprI gene recombinant plasmid group in peripheral blood of mice was significantly higher in the days of 1,7,14 and 28 (F =16.26,8.10,6.37,10.74,P ＜0.05),PLT count was significantly higher in days of 7 and 14 (F =7.36,5.71,P ＜ 0.05),meanwhile the lymphocyte percentage was increased significantly on the 7th day (F =18.43,P ＜ 0.05) after irradiation.On the other hand,the apoptosis rates of thymocyte cells and bone marrow cells were significantly decreased in the days of 1,7,14,28 and 35 (F =3.88,14.91,14.14,39.86,5.65,P ＜0.05 and F=53.70,11.75,21.78,41.40,4.54,P ＜0.05) while the apoptosis rate of spleen cells was significantly decreased in the days of 1,7,14 and 28 (F =97.95,56.61,33.55,14.71,P ＜0.05) after irradiation.Finally,the radiation histopathological changes of lung and testis of the pEGFP-c1-pprI gene recombinant plasmid group were slight and easy to recover.Conclusions Transfection of pprI gene of Deinococcus radiodurans by in vivo electroporation has significant protective effect on the acute radiation injury in BALB/c mice,which may have important clinical applications.
ABSTRACT
Objective To construct the eukaryotic expression vector of pprI gene from Deinococcus radiodurans R1 and investigate its radioresistant effects in eukaryotic cells.Methods A recombinant vector pEGFP-c1-pprI was constructed by DNA recombinant technique.The empty vector pEGFP-c1 and the pEGFP-c1-pprI were transferred into human lung epithelial cells Beas-2B by LipofectamineTM 2000,respectively.Then the infected cells were screened in order to develop a cell line with stable expression of pprI gene.Cell survival rate was tested by clone-forming assay.Cell cycle distribution and apoptosis were detected by a flow cytometry.The fluorescence intensity of reactive oxygen species (ROS) was observed by a fluorescent microscope.γ-H2AX foci in the irradiated cell was detected by immunofluorescence.Results The eukaryotic expression plasmid of pprI prokaryotic gene was constructed and PprI fusion protein was expressed in human lung epithelial cells successfully,and the cell line (2BG) with a stable pprI gene expression was established.After irradiation,the cell survival fraction of 2BG cells was significantly higher than Beas-2B cells so that the value of D0 、Dq and N of the survival curve were increased.Moreover,the fluorescence intensity of ROS and the number of γ-H2AX foci in 2BG cells were also lower than those of B eas-2B cells(F =16.73,19.47,6.94,P ＜ 0.05).Between these two cell lines,the apoptosis rate and cell cycle G2 arrest also had significant difference (F =139.73,237.92,P ＜ 0.05).Conclusions The pprI gene from Deinococcus radiodurans RI can be stably expressed in the eukaryotic cells and it allows the transferred cells to have a radioresistant function.
ABSTRACT
Objective To investigate the mechanism of Deinococcus radiodurans pprI gene in enhancing mice radioresistance to γ-rays by transfecting it in vivo.Methods The male Kunming mice were randomly divided into control group,irradiated group,pCMV-HA transfected group and pCMV-HA-pprI transfected group.The pCMV-HA-pprI plasmid contained pprI gene was injected into the muscle of mice which were exposed to total 6 Gy of γ-ray irradiation.After injection,the in vivo gene electroporation technology was used to transfect the pprI gene into the cells,and Western blot was used to identify the PprI protein,mammalian homolog protein Rad51 corresponding to recA gene downstream of pprI,and protein Rad52.Results In the muscle of the mice of transfected pCMV-HA-pprI group,the protein PprI expressed significantly at 1 d post-irradiation,but there was no expression of pprI gene 7 d post-irradiation and in other groups.In the mice of transfected with pCMV-HA-pprI,the expression of Rad51 protein was significantly increased in the lungs at 1,7 and 14 d post-irradiation,and significantly increased in the liver at 1 and 28 d post-irradiation and increased in the kidneys at 1 and 14 d post-irradition.However,there was no obvious change of Rad52 protein expression in the lungs and livers of mice in all groups.Conlusions The prokaryotic gene pprI could act on the mammalian homologisation analogues rad51 gene downstream of recA gene and then increase the expression level of protein Rad51 which results in the enhancement of radioresistance.