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Objective To monitor the autophagy in osteosarcoma cells by constructing three rLC3B fusion expression vectors,respectively.Methods Rat LC3B gene sequence was amplified by PCR and cloned into pEGFP-C 1 and pmCherry-C1 to construct the fusion expression vector of pEGFP-rLC3B and pmCherry-rLC3B.Subsequently,the EGFP-rLC3B sequence was obtained by PCR with the pEGFP-rLC3B as a template,and cloned into pmCherry-C 1,so the pmCherry-EGFP-rLC3B fusion expression vector was constructed.Three plasmids were transfected into U-2OS cells,and the starvation or Rapamycin was adopted to induce autophagy or the chloroquine or Baf-A1 was used to inhibit autophagy,to verify the above plasmids' function in autophagy detection by laser scanning confocal microscopy.Western blot was used to detect the endogenous LC3B and exogenous EGFPrLC3B,pmCherry-rLC3B and mCherry-EGFP-rLC3B,and to verify the correct expression of exogenous rLC3B and their function of autophagy detection.Finally,cleaved free EGFP was detected by western blot to evaluate the level of autophagic degradation.Results Three fusion expression vectors were constructed successfully through sequencing and restriction enzyme digestion validation.The starvation or Rapamycin was adopted to induce autophagy or the chloroquine or Baf-A 1 was used to inhibit autophagy in transfected U-2OS cells.Clear autophagosomes and autolysosomes were observed by laser scanning confocal microscopy.Endogenous LC3B and exogenous EGFP-rLC3B,pmCherry-rLC3B and mCherry-EGFP-rLC3B were detected through western blot.Finally,western blot verified that the expression of cleaved free EGFP was significantly up-regulated with the increase of starvation time.12 h group increased 1.05 times than the control group and 24 h group increased 1.56 times,showing that the levels of autophagic degradation increased.Conclusion EGFP-rLC3B can be used to detect autophagosome and evaluate the level of autophagic degradation.mCherry-rLC3B can be used to detect autophagosome and autolysosome,but can't distinguish autophagosome from autolysosome.The pmCherry-EGFP-rLC3B has an advantage in the detection of autophagic flux which can distinguish autophagosome from autolysosome.
ABSTRACT
The inverted terminal repeat (ITR) is the only cis element of AAV genome essential for rAAV rescue, replication and packaging. It is prone to mutation or loss when it is latent in host cell or in plasmid. Plasmids with different ITR types were cloned to compare the influence of ITR types on the AAV packaging and infectivity. The vector plasmids were transformed the competent SURE cells to get different colonies. The ITR types of plasmids were screened by digestion with SmaⅠ. AAV vector plasmid pScGFPud has two ITRs at both ends of AAV genome and plasmid pScGFPu has only one ITR at upstream end of AAV genome. When the two plasmids were co-transfected 293 cells to prepare rAAVs, 1.08?1013 viral particles (AAV1-GFPud) were produced from 20-dishes of 293 cells cotransfected with plasmid pScGFPud, 4.28?1012 viral particles (AAV1-GFPu) were produced from 20-dishes of 293 cells cotransfected with plasmid pScGFPu. Virus AAV1-GFPud infected 293, HeLa and NCI H446 cells more efficiently than did virus AAV1-GFPu. This suggests that defect ITRs in AAV genome is deleterious to AAV packaging and AAV infectivity and vector with complete ITRs is favorable to the yield and activity of rAAV.
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AIM: HLCDG1 is a novel gene cloned recently, and its expression inhibits significantly the growth of A549 cells and tumorigenesis of A549 cells transplanted in nude mice. In this study, our aim was to construct HLCDG1 gene short/small interference double-strand RNA (siRNAs) expression vector and to observe its influence on cell cycle and proliferation of A549 cells. METHODS: Using RNA interference (RNAi) techniques, a DNA vector-driven siRNAs expression vector was constructed, and a lung carcinoma cell line stably expressing siRNAs was also selected. Sequentially, using flow cytometry analysis and MTT assay, the changes of cell cycle and cell proliferation in this cell line were observed. RESULTS: Four site-match and one site-mismatch plasmids were constructed, which were named pHL-si-1, pHL-si-2, pHL-si-3, pHL-si-4 and pHL-si-c. These plasmids were co-transfected with a pcDNA3.1(+)/HLCDG1 plasmid into A549 cells, respectively. Among five co-transfected A549 cell lines, a A549 cell line co-transfected by the pcDNA3.1(+)/HLCDG1 and pHL-si-1 plasmids, namely A549-HLCDG1-si-1, showed nearly complete inhibition of HLCDG1 expression. MTT assay and flow cytometry analysis indicated that A549-HLCDG1-si-1 cells, namely the HLCDG1 gene-silencing cells, got a faster growth compared with other HLCDG1 expression cell lines, and that HLCDG1 gene-silencing induced A549-HLCDG1-si-1 cells into S phase and G_2+M phase significantly. CONCLUSION: These results suggest that the HLCDG1 gene is proved to have a markedly inhibitory effect on growth in A549 lung carcinoma cells. This study might provide some understanding of the biological function and molecular mechanism of HLCDG1 gene.
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AIM: To observe the expression of vascular cell adhesion molecule-1 (VCAM-1) in cultured human umbilical vein endothelial cells (HUVEC) by lipid peroxidation injury induced by exposure to diamide. METHODS: Expression of VCAM-1 mRNA and protein in HUVEC was determined by in situ hybridization and a cell enzyme-linked immunosorbent essay (cell ELISA), respectively. RESULTS: The HPIAS-1000 image analytic system in situ hybridization detected that the mean absorbance values in experiment groups(1, 5 and 10 ?mol/L diamide for 8 hours) were 0.147?0.013, 0.292?0.020 and 0.396?0.022, which were 1.91-fold, 3.79-fold and 5.14-fold as much as that of the control group (0.077?0.011), respectively. There was significant statistical difference between groups ( P
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AIM: To investigate the effect of homocysteine (HCY) on the induction of macrophage inflammatory protein-1? (MIP-1?) expression in cultured human umbilical vein endothelial cells (HUVECs). METHODS: After exposure of the cultured HUVECs to HCY at increasing concentrations (0.1, 0.5 and 1 mmol/L) for 8 h, the MIP-1? mRNA expression was determined by in situ hybridization using a MIP-1? cDNA probe, and the MIP-1? protein expression was measured by cell enzyme-linked immunosorbent assay (ELISA) using a goat anti-human MIP-1? monoclonal antibody. RESULTS: The in situ hybridization showed that cultured HUVECs were able to express MIP-1? mRNA at a low level that was purplish blue granules in cytoplasm. After exposure to HCY at the concentrations mentioned above, the expression of MIP-1? mRNA was significantly increased in a dose-dependent manner. Analysis of variance showed that there was significant difference between groups ( F= 606.38, P