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Objective To knock out p21 gene in human malignant rhab doid tumor(MRT)cell line G401 by using CRISPR/Cas9 genome engineering technology. Methods The expression of p21 was detected by reverse transcription quantitative PCR (RT-qPCR) and Western blot assay in several MRT cell lines. The guide RNA was designed by targeting the third exon of p21 gene,which encoded its home domains, and then subcloned into lentiCRISPR v2 vector and validated sequencing. The validated plasmids were further used to package and produce the lentivirus in 293T cells, and the G401 cells were infected, then puromycin was used to screen positive cells, and the clusters of G401 monoclonal cells, were obtained by selecting monoclonal cells and culturing under the microscope. The RNA and protein of new clonal cell line were extracted, and RT-qPCR and Western blot assay were applied to confirm whether p21 was successfully knocked out. Results The p21 was highly expressed in MRT tumor cells. The CRISPR/Cas9 lentivirus plasmids, targeted p21 gene were successfully constructed. Compared with negative control group,the expression of p21 was not detected in G401 monoclonal cells, which were successfully screened. Conclusion In view of the difficult transfection of cells such as G401, p21 knockout stable cell line has been successfully constructed by using CRISPR/Cas9 system, which lays the foundation for further study of the mechanism of p21 in MRT tumors .
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The chemical constituents of Taxus chinensis var. mairei cell cultures were investigated by chromatographic methods, including silica gel column chromatography, Sephadex LH-20 and preparative HPLC. Thirteen compounds were isolated from the 80% ethanol extract of cultured cells and their structures were elucidated by spectral data and physicochemical properties, which were identified as 2α,4α,7β,9α,10β-pentaacetoxy-14β-hydroxytax-11-ene (1), 2α,4α,7β,9α,10β-pentaacetoxytax-11-ene (2), 1β-deoxybaccatin VI (3), 2α-acetoxytaxusin (4), taxuyunnanine C (5), yunnanxane (6), 2α,5α,10β-triacetoxy-14β-propionyloxy-4 (20), 11-taxadiene (7), 2α,5α,10β-triacetoxy-14β-isobutyryloxy-4 (20), 11-taxadiene (8), 2α,5α,10β-triacetoxy-14β-(2'-methyl)butyryloxy-4 (20), 11-taxadiene (9), 13-dehydroxylbaccatin III (10), 13-dehydroxy-10-deacetylbaccatin III (11), paclitaxel (12) and (13) β-sitosterol. Among them, compound 1 is a new compound, and compounds 2, 4, 10 and 11 are isolated from the cell culture of Taxus chinensis var. mairei for the first time.
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This study sought to construct a recombinant vector that expresses anti-GD2/anti-CD16 bispecific single-chain antibody(sc-BsAb), and to assess its biological activities. The anti-GD2 gene and the anti-CD16 gene (NM3E2) were obtained using PCR amplification technique, and then the fusion gene was constructed by overlapping PCR. The sc-BsAb gene was subcloned into the pET-22b(+) plasmid from the pMD18-T easy vector by digestion with NcoI, Hind III restriction endonucleases, whose sites exist in both the vectors. Then the combinant plasmids were transferred into E. coli BL21 (DE3). The expression product in the periplasmic was analyzed by both SDS-PAGE and Western blot technique, then was purified with Ni2+ -NTA superflow affinity chromatography. It was demonstrated that the linker in the sc-BsAb fusion protein is SerGly4Ser. and the molecular is 53 KD.