The Double Nickase Plasmid features a U6 promoter for sgRNA expression, a 20 nt targeting sequence, and a gRNA scaffold to guide Cas9n. It includes a CBh promoter for Cas9n (D10A) and puromycin resistance, GFP for transfection verification, and nuclear localization signals (NLS). The 2A peptide allows co-expression of Cas9n and Puro from a single promoter, enabling precise genome editing with reduced off-target effects.
The Double Nickase Plasmid features a U6 promoter for sgRNA expression, a 20 nt targeting sequence, and a gRNA scaffold to guide Cas9n. It includes a CBh promoter for Cas9n (D10A) and puromycin resistance, GFP for transfection verification, and nuclear localization signals (NLS). The 2A peptide allows co-expression of Cas9n and Puro from a single promoter, enabling precise genome editing with reduced off-target effects.
Cas9n Nickase gRNA Plasmid Targeting: Dual gRNA plasmids create single-strand nicks at precise DNA sequences for efficient genome editing using Cas9n Nickase.
This image illustrates the Cas9n Nickase mechanism used for precise genome editing. Two plasmids (Plasmid 1 and Plasmid 2) are shown, each containing a targeted DNA sequence. The system utilizes single-guide RNAs (sgRNA) to direct Cas9n Nickase to specific genomic locations, represented by the blue and pink DNA strands. The sgRNA scaffold aids in guiding Cas9n to the 20 nucleotide (nt) target sequence on the DNA. Cas9n makes single-strand cuts at NCC and NGG sites, enabling precise gene modifications without creating double-strand breaks.
The Double Nickase Plasmid features a U6 promoter for sgRNA expression, a 20 nt targeting sequence, and a gRNA scaffold to guide Cas9n. It includes a CBh promoter for Cas9n (D10A) and puromycin resistance, GFP for transfection verification, and nuclear localization signals (NLS). The 2A peptide allows co-expression of Cas9n and Puro from a single promoter, enabling precise genome editing with reduced off-target effects.
人类 APTX 基因编码 aprataxin,这是一种 DNA 修复因子,可通过去除 5′ 端 DNA 末端的腺苷酸基团来解析异常的 DNA 连接中间体,从而在单链断裂修复过程中恢复可再次连接的末端。Aprataxin 参与与 PARP 依赖性修复信号相关的基因组维护通路,并与 XRCC1–DNA 连接酶 III 复合体协同作用,保护细胞免受复制相关损伤。APTX 活性缺失会削弱对氧化损伤及拓扑异构酶诱导损伤的修复,促进链断裂积累并提高基因组不稳定性。APTX 功能异常与神经退行性表型相关,因此是在神经元及增殖细胞背景下研究 DNA 损伤应答的重要靶点。
Aprataxin 双切酶质粒(h)由一对匹配的质粒组成,专为在 human 细胞系中对 APTX 位点进行高特异性编辑而设计。每个质粒分别表达Cas9 D10A切口酶和针对APTX内不同DNA链的独特sgRNA。当这两种切口酶被引导至相邻但位于DNA链相反侧的位点时,会产生错位的单链切口,从而共同形成错位双链断裂,这需要两个引导RNA在靶位点上协同发挥作用。由此产生的DNA断裂通过内源性细胞修复途径(最常见的是非同源末端连接(NHEJ))得到修复,从而导致插入或缺失,进而破坏APTX的功能。通过要求双sgRNA在靶位点结合,双切口方法提高了编辑特异性,并为需要对靶向精度进行额外控制的应用提供了互补的CRISPR策略。