Expression of low-density lipoprotein receptor-associated protein 11 in colorectal cancer tissues and its effects on proliferation and apoptosis of SW480 cells / 中国肿瘤生物治疗杂志

@#[摘 要] 目的：探讨低密度脂蛋白受体相关蛋白11（LRP11）在结直肠癌（CRC）组织中的表达及其对结肠癌SW480细胞增殖与凋亡的影响。方法：利用生物信息学方法分析TCGA数据库中LRP11在CRC组织中的表达水平。用慢病毒感染技术分别将sh-LRP11及sh-NC质粒转染至SW480细胞，采用qPCR、WB法检测感染后各组细胞中LRP11的mRNA和蛋白的表达，CCK-8法、流式细胞术分别检测细胞的增殖活力、凋亡率及细胞周期分布情况，WB法检测SW480细胞中cyclin D1、BAX、Bcl-2、β-catenin、活化β-catenin等蛋白的表达水平。结果：TCGA数据库数据分析显示，LRP11 mRNA在CRC组织中的表达水平显著高于正常组织（P<0.05）。与sh-NC组比较，sh-LRP11组SW480细胞的增殖活力明显降低、细胞凋亡率显著升高（均P<0.01），细胞中BAX表达显著升高、Bcl-2表达显著降低（均P<0.01）；G0/G1期细胞增多、S期细胞明显减少（均P<0.01），cyclin D1的蛋白表达显著降低（P<0.01）；Wnt/β-catenin信号通路中β-catenin和活化β-catenin的蛋白表达均显著下降（均P<0.01）。结论：LRP11 mRNA在CRC组织中呈高表达，干扰LRP11表达可抑制结肠癌SW480细胞增殖并促进其凋亡，为CRC提供了一种潜在的治疗靶点。

A novel chlorpyrifos hydrolase CPD from Paracoccus sp. TRP: molecular cloning, characterization and catalytic mechanism

Background: Biodegradation is a reliable approach for efficiently eliminating persistent pollutants such as chlorpyrifos. Despite many bacteria or fungi isolated from contaminated environment and capable of degrading chlorpyrifos, limited enzymes responsible for its degradation have been identified, let alone the catalytic mechanism of the enzymes. Results: In present study, the gene cpd encoding a chlorpyrifos hydrolase was cloned by analysis of genomic sequence of Paracoccus sp. TRP. Phylogenetic analysis and BLAST indicated that CPD was a novel member of organophosphate hydrolases. The purified CPD enzyme, with conserved catalytic triad (Ser155-Asp251-His281) and motif Gly-Asp-Ser-Ala-Gly, was significantly inhibited by PMSF, a serine modifier. Molecular docking between CPD and chlorpyrifos showed that Ser155 was adjacent to chlorpyrifos, which indicated that Ser155 may be the active amino acid involved in chlorpyrifos degradation. This speculation was confirmed by site-directed mutagenesis of Ser155Ala accounting for the decreased activity of CPD towards chlorpyrifos. According to the key role of Ser155 in chlorpyrifos degradation and molecular docking conformation, the nucleophilic catalytic mechanism for chlorpyrifos degradation by CPD was proposed. Conclusion: The novel enzyme CPD was capable of hydrolyze chlorpyrifos and Ser155 played key role during degradation of chlorpyrifos.

Combined strategies for improving production of a thermo-alkali stable laccase in Pichia pastoris

Background: Laccases are copper-containing enzymes which have been used as green biocatalysts for many industrial processes. Although bacterial laccases have high stabilities which facilitate their application under harsh conditions, their activities and production yields are usually very low. In this work, we attempt to use a combinatorial strategy, including site-directed mutagenesis, codon and cultivation optimization, for improving the productivity of a thermo-alkali stable bacterial laccase in Pichia pastoris. Results: A D500G mutant of Bacillus licheniformis LS04 laccase, which was constructed by site-directed mutagenesis, demonstrated 2.1-fold higher activity when expressed in P. pastoris. The D500G variant retained similar catalytic characteristics to the wild-type laccase, and could efficiently decolorize synthetic dyes at alkaline conditions. Various cultivation factors such as medium components, pH and temperature were investigated for their effects on laccase expression. After cultivation optimization, a laccase activity of 347 ± 7 U/L was finally achieved for D500G after 3 d of induction, which was about 9.3 times higher than that of wild-type enzyme. The protein yield under the optimized conditions was about 59 mg/L for D500G. Conclusions: The productivity of the thermo-alkali stable laccase from B. licheniformis expressed in P. pastoris was significantly improved through the combination of site-directed mutagenesis and optimization of the cultivation process. The mutant enzyme retains good stability under high temperature and alkaline conditions, and is a good candidate for industrial application in dye decolorization.