基于CRISPR/Cas9技术构建IDO1基因敲除的THP-1细胞株及其表型研究

Construction of IDO1 gene knockout THP-1 cell line using CRISPR/Cas9 and its phenotype identification

目的 采用CRISPR/Cas9技术构建吲哚胺-2,3-双加氧酶1(IDO1)基因敲除的THP-1细胞株,为研究IDO1在巨噬细胞中的作用提供细胞模型。方法 设计靶向IDO1基因的3条向导RNA(guide RNA,gRNA),分别构建IDO1-gRNA重组质粒,酶切及测序鉴定后,包装成Lenti-IDO1-gRNA慢病毒。利用Cas9慢病毒感染THP-1细胞获得稳定表达Cas9蛋白的细胞株,再经Lenti-IDO1-gRNA慢病毒感染敲除IDO1基因,有限稀释法获得单克隆细胞株。T7E1酶切检测gRNA打靶效率,PCR产物测序和Western blot鉴定IDO1基因敲除效果。CCK8法检测IDO1基因敲除对THP-1细胞增殖活性的影响,流式细胞术检测对巨噬细胞标志物CD11b、CD68和CD14表达的影响,中性红法检测巨噬细胞吞噬功能。结果 成功构建了3种IDO1-gRNA重组质粒,3条gRNA均能有效编辑IDO1基因,以gRNA2编辑效率最高。经PCR产物测序和Western blot验证获得了3株THP-1 IDO1-KO单克隆细胞株,并发现IDO1基因敲除可抑制THP-1细胞增殖,下调THP-1巨噬细胞CD11b、CD68表达,上调CD14表达,增强THP-1巨噬细胞吞噬功能。结论 成功构建IDO1基因敲除的THP-1细胞株;IDO1对THP-1细胞增殖活性、分化调节以及THP-1巨噬细胞吞噬功能调节有重要作用,为后续进一步探讨IDO1基因在巨噬细胞中的功能及机制研究奠定基础。

Tryptophan metabolism plays an important role in immunometabolism in sepsis,and the expression of indoleamine 2,3-dioxygenase 1(IDO1),the key enzyme of tryptophan metabolism,is up-regulated during sepsis.This study was designed to construct IDO1 gene knockout THP-1 cell line using CRISPR/Cas9,and to provide a cell model for studying the role of IDO1 in macrophage function.Three gRNAs were designed for the IDO1 gene,and inserted into YKO-Lentiviral gRNA plasmid respectively to construct IDO1-gRNA recombinant plasmid,which then confirmed by restriction enzyme digestion and sequencing,and packaged as Lenti-IDO1-gRNA lentivirus.THP-1 cells were infected with Cas9 lentivirus to construct a THP-1 Cas9 cell line stably expressing Cas9 protein.Then THP-1 Cas9 cells were infected with the Lenti-IDO1-gRNA lentivirus for IDO1 gene knockout,and the monoclonal cell lines were screened by limited dilution method.The efficiency of IDO1 knockout was identified by T7E1 digestion test,PCR product sequencing and Western blotting.The proliferative activity of THP-1 cells was detected by CCK8 assay;the expression of CD11b,CD68 and CD14 in THP-1 macrophages were detected by flow cytometry;and the phagocytic function of THP-1 macrophages was detected by neutral phagocytosis test.T7E1 restriction enzyme digestion results showed that all the three gRNAs could effectively edit IDO1 gene,and gRNA2 had the highest editing efficiency.Sequencing of PCR products showed that IDO1 gene was mutated in three THP-1 IDO1-KO monoclonal cell lines,and Western blot result showed that IDO1 protein was not expressed,suggesting THP-1 IDO1-KO cells were successfully constructed.CCK-8 proliferation assay showed that IDO1 gene knockout could inhibit the proliferation of THP-1 cells.Flow cytometry showed that IDO1 gene knockout downregulated the expression of CD11b and CD68 in THP-1 macrophages,while up-regulated the expression of CD14.The results of neutral red phagocytosis test showed that IDO1 gene knockout promoted the phagocytosis of macrophages.In conclusion,the IDO1 gene knockout THP-1 cell line has successfully constructed by CRISPRCas9,and IDO1 plays an important role in regulating the proliferation activity and differentiation of THP-1 cells,as well as the phagocytic function of THP-1 macrophages.